Support material formulations usable in additive manufacturing and methods employing same

Abstract

A curable formulation usable as a support material formulation in additive manufacturing of a three-dimensional object such as a denture structure, which forms a hardened mixed layer with a modeling material formulation and provides an object that features improved toughness (e.g., fracture toughness), and additive manufacturing methods employing same are provided. The curable formulation comprises at least one non-curable material which comprises at least one polymeric material featuring water solubility (e.g., ECAH) lower than 200 grams / liter, at least one mono-functional (meth)acrylate featuring low Tg and miscibility in the non-curable material, at least one multi-functional (meth) acrylate featuring at least 10 ethoxylated groups and / or Tg lower than 0 °C, and at least one mono-functional (meth)acrylate. Additive manufacturing of a three- dimensional assembly which comprises a hardened object and a hardened sacrificial structure, and systems employing same are also provided.

Description

[0001] SUPPORT MATERIAL FORMULATIONS USABLE IN ADDITIVE MANUFACTURING AND METHODS EMPLOYING SAME

[0002] RELATED APPLICATIONS

[0003] This application claims the benefit of priority of US Provisional Patent Application No.

[0004] 63 / 740,352 filed on 31 December 2024, the contents of which are incorporated herein by reference in their entirety.

[0005] FIELD AND BACKGROUND OF THE INVENTION

[0006] The present invention, in some embodiments thereof, relates to additive manufacturing, and more particularly, but not exclusively, to support material formulations usable in additive manufacturing of three-dimensional objects that feature, in at least a portion thereof, a hardened material that features high fracture toughness. The present invention, in some embodiments thereof, further relates to a three-dimensional assembly, and a method suitable for fabricating the three-dimensional assembly.

[0007] The present invention, in some embodiments thereof, relates to additive manufacturing and, more particularly, but not exclusively, to curable formulations which are usable in additive manufacturing of dental prostheses, including denture teeth, denture base and monolithic denture structures.

[0008] Additive manufacturing (AM) is a technology enabling fabrication of arbitrarily shaped structures directly from computer data via additive formation steps. The basic operation of any AM system consists of slicing a three-dimensional computer model into thin cross sections, translating the result into two-dimensional position data and feeding the data to control equipment which fabricates a three-dimensional structure in a layer-wise manner.

[0009] Additive manufacturing entails many different approaches to the method of fabrication, including three-dimensional (3D) printing such as 3D inkjet printing, electron beam melting, stereolithography, selective laser sintering, laminated object manufacturing, fused deposition modeling and others.

[0010] Some 3D printing processes, for example, 3D inkjet printing, are being performed by a layer-by-layer inkjet deposition of building materials. Thus, a building material is dispensed from a dispensing head having a set of nozzles to deposit layers on a supporting structure. Depending on the building material, the layers may then be cured or solidified. Curing may be by exposure to a suitable condition, and optionally by using a suitable device.The building material includes an uncured model material (also referred to as “uncured modeling material” or “modeling material formulation”), which is selectively dispensed to produce the desired object, and may also include an uncured support material (also referred to as "uncured supporting material” or “support material formulation”) which provides temporary support to specific regions of the object during building and assures adequate vertical placement of subsequent object layers. The supporting structure is configured to be removed after the object is completed.

[0011] In some known inkjet printing systems, the uncured model material is a photopolymerizable or photocurable material that is cured, hardened or solidified upon exposure to ultraviolet (UV) light after it is jetted. The uncured model material may be a photopolymerizable material formulation that has a composition which, after curing, gives a solid material with mechanical properties that permit the building and handling of the three-dimensional object being built. The modeling material formulation typically include a reactive (curable) component and a photoinitiator. The photo-initiator may enable at least partial solidification (hardening) of the uncured support material by curing with the same UV light applied to form the model material. The solidified material may be rigid, or may have elastic properties.

[0012] The support material is formulated to permit fast and easy cleaning of the object from its support. The support material may be a polymer, which is water-soluble and / or capable of swelling and / or breaking down upon exposure to a liquid solution, e.g., water, alkaline or acidic water solution. The support material formulation may also include a reactive (curable) component and a photo-initiator.

[0013] In order to be compatible with most of the commercially-available print heads utilized in a 3D inkjet printing system, the uncured building materials should feature the following characteristics: a relatively low viscosity (e.g., Brookfield Viscosity of up to 50 centipoises or cps, or up to 35 cps, preferably from 8 to 25 cps) at the working (e.g., jetting) temperature; Surface tension of from about 25 to about 55 Dyne / cm, preferably from about 25 to about 40 Dyne / cm; and a Newtonian liquid behavior and high reactivity to a selected curing condition, to enable fast solidification of the jetted layer upon exposure to a curing condition, of no more than 1 minute, preferably no more than 20 seconds.

[0014] The hardened modeling material which forms the final object typically exhibits a heat deflection temperature (HDT) which is higher than room temperature, in order to assure its usability. Desirably, the hardened modeling material exhibits an HDT of at least 35 °C. For an object to be stable at variable conditions, a higher HDT is known to be desirable. In most cases, itis also desirable that the object exhibits relatively high Izod Notched impact, e.g., higher than 50 or higher than 60 J / m.

[0015] Various three-dimensional printing techniques exist and are disclosed in, e.g., U.S. Patent Nos. 6,259,962, 6,569,373, 6,658,314, 6,850,334, 6,863,859, 7,183,335, 7,209,797, 7,225,045, 7,300,619, 7,500,846, 7,991,498 and 9,031,680 and U.S. Published Application No. 20160339643, all by the same Assignee, and being hereby incorporated by reference in their entirety.

[0016] Several additive manufacturing processes, including three-dimensional inkjet printing, allow additive formation of objects using more than one modeling material, also referred to as “multi-material” AM processes. For example, U.S. Patent Application having Publication No.

[0017] 2010 / 0191360, of the present Assignee, discloses a system which comprises a solid freeform fabrication apparatus having a plurality of print heads, a building material supply apparatus configured to supply a plurality of building materials to the fabrication apparatus, and a control unit configured for controlling the fabrication and supply apparatus. The system has several operation modes. In one mode, all print heads operate during a single building scan cycle of the fabrication apparatus. In another mode, one or more of the print heads is not operative during a single building scan cycle or part thereof.

[0018] In a 3D inkjet printing process such as PolyJet™ (Stratasys® Ltd., Israel), the building material is selectively jetted from one or more inkjet print heads and / or nozzles and deposited onto a fabrication tray in consecutive layers according to a pre-determined configuration as defined by a software file.

[0019] The PolyJet™ technology allows control over the position and composition of each voxel (volume pixel), which affords enormous design versatility and digital programming of multimaterial structures. Other advantages of the PolyJef™ technology is the very high printing resolution, up to 14 pm layer height, and the ability to print multiple materials simultaneously, in a single object. This multi-material 3D printing process often serves for fabrication of complex parts and structures that are comprised of elements having different stiffness, performance, color or transparency. New range of materials, programmed at the voxel level, can be created by the PolyJet™ printing process, using only few starting materials.

[0020] PCT International Patent Application Publication No. WO 2013 / 128452, by the present Assignee, discloses a multi-material approach which involves separate jetting of two components of a cationic polymerizable system and / or a radical polymerizable system, which intermix on the printing tray, leading to a polymerization reaction similar to pre-mixing of the two components before jetting, while preventing their early polymerization on the inkjet head nozzle plate.Current PolyJet™ technology offers the capability to use a range of curable (e.g., polymerizable) materials that provide polymeric materials featuring a variety of properties, ranging, for example, from stiff and hard materials (e.g., curable formulations marketed as the Vero® Family materials) to soft and flexible materials (e.g., curable formulations marketed as the Tango™ and Agilus™ families), and including also objects made using Digital ABS™, which contain a multi-material made of two starting materials (e.g., RGD515 & RGD535 / 531), and simulate properties of engineering plastic. Most of the currently practiced PolyJet™ materials are curable materials which harden or solidify upon exposure to radiation, mostly UV radiation and / or heat, with the most practiced materials being acrylic-based materials.

[0021] Some photocurable (photopolymerizable) modeling material formulations known as usable in 3D inkjet printing are designed to provide, when hardened, a transparent material.

[0022] The use of light emitting diodes (LED) as a source for electromagnetic irradiation has recently become more and more common and desirable in many fields, including additive manufacturing processes such as those that utilize UV-curable materials. Most of the commercially available UV LED light sources emit UVA radiation, at the higher wavelengths of 365 / 395 / 405 nm. The use of such light sources poses severe limitations since photoinitiators that absorb shorter wavelengths, such as, for example, those of the alpha-hydroxy ketone family that absorb at 250-300 nm, cannot be efficiently used. These photoinitiators are typically used for surface curing and the absence thereof adversely affects the process quality.

[0023] Current solutions to limitations posed by the use of UV LED as an irradiation source include the use of hydrogen donors that promote surface curing, such as tertiary amines, thiols and polyethylene glycol-containing materials. However, the use of these materials, while facilitating AM that use UV LED, is accompanied by several drawbacks. For example, tertiary amines impart an increased yellow hue to the cured material; thiols are typically reactive towards UV-curable materials that are commonly used in AM, such as acrylic materials, and thus limit the shelf-lives of formulations containing same; and polyethylene glycol materials are amphiphilic materials that act also as plasticizers or elastomers and hence reduce mechanical stability and increase water absorption of the obtained object.

[0024] During the last decade, efforts have been made to use additive manufacturing such as 3D inkjet printing and digital light processing (DLP) in the denture field.

[0025] For example, U.S. Patent No. 7,476,347 and U.S. Patent Application Publication No.

[0026] 2011 / 0049738 disclose a process for making dentures having integral teeth and a denture base by inkjet three-dimensional printing. The methodologies taught in these patents employ wax-like polymerizable materials, which are needed to be custom-synthesized, incurring additional time andcosts. These materials require the use of more than 70 % filler material, and feature slow reaction rate and high viscosity.

[0027] U.S. Patent Application No. 2019 / 0175455 describes a photocurable composition for manufacturing a dental prosthesis by stereolithography, including: a photopolymerization initiator; and a (meth) acrylic monomer component including an acrylic monomer (X) having no aromatic rings and having a ring structure other than an aromatic ring and two or more acryloyloxy groups in one molecule and having an Mw of from 200 to 800, and at least one of a (meth)acrylic monomer (A) having one or more ether bonds and two (meth) acryloyloxy groups in one molecule and having a defined Mw, a (meth) acrylic monomer (B) having a ring structure other than an aromatic ring and one (meth) acryloyloxy group in one molecule and having a defined Mw, a (meth)acrylic monomer (C) having a hydrocarbon skeleton and two (meth)acryloyloxy groups in one molecule and having a defined Mw, and a (meth)acrylic monomer (D) having one or more aromatic rings and one (meth)acryloyloxy group in one molecule and having a Mw.

[0028] U.S. Patent Application Publication No. 2018 / 0049954 teaches photocurable compositions for artificial teeth and denture base which are usable in 3D inkjet printing or DLP type AM. The compositions include photo-curable organic compounds, surface modified nano-sized inorganic filler, photo-initiator, colorant, and stabilizer. The compositions provide a distinctive denture base and a set of artificial teeth which can thereafter be bonded to one another.

[0029] Additional background art includes Chung et al., Materials (Basel). 2018 Oct; 11(10): 1798; and U.S. Patent No. 9,227,365; U.S. Patent No. 6,242,149; U.S. Patent Application having Publication No. 2010 / 0140850; WO 2009 / 013751; WO 2016 / 063282; WO 2016 / 125170; WO 2017 / 134672; WO 2017 / 134673; WO 2017 / 134674; WO 2017 / 134676; WO 2017 / 068590; WO 2017 / 187434; WO 2018 / 055521; WO 2018 / 055522; WO 2020 / 065654; WO 2023 / 126943; and PCT International Patent Application Publication No. WO 2025 / 008825, all by the present assignee.

[0030] SUMMARY OF THE INVENTION

[0031] According to an aspect of some embodiments of the present invention there is provided a curable formulation usable in additive manufacturing of a three-dimensional object, the curable formulation comprising:

[0032] at least one non-curable material (Component L) which comprises at least one polymeric material featuring water solubility (e.g., ECAH) lower than 200, or lower than 100 or lower than 50, or lower than 10, grams / liter (Component L3 and / or L4);at least one mono-functional (meth) acrylate featuring low Tg (Tg lower than 0, or lower than -20 °C) and miscibility in the at least one Component L3 and / or L4 (Component M);

[0033] at least one multi-functional (meth)acrylate featuring at least 10 ethoxylated groups and / or Tg lower than 0 °C (e.g., Component D2);

[0034] at least one mono-functional (meth)acrylate (Component E); and

[0035] optionally, at least one reactive diluent (Component K).

[0036] According to some embodiments of any of the embodiments described herein, Component L3 and / or L4 features water absorbance lower than 20 %, as described herein.

[0037] According to some embodiments of any of the embodiments described herein, the at least one polymeric material featuring water solubility lower than 200 grams / liter (Component L3 and / or L4) is selected from a polyether and a polyester.

[0038] According to some embodiments of any of the embodiments described herein, the at least one polymeric material featuring water solubility lower than 200 grams / liter (Component L3 and / or L4) is or comprises a polyester.

[0039] According to some embodiments of any of the embodiments described herein, the at least one polymeric material featuring water solubility lower than 200 grams / liter (Component L3 and / or L4) is or comprises a polycaprolactone.

[0040] According to some embodiments of any of the embodiments described herein, the at least one polymeric material featuring water solubility lower than 200 grams / liter has an average molecular weight (Mn) lower than 1,000 or lower than 500 grams / mol (Component L3).

[0041] According to some embodiments of any of the embodiments described herein, the at least one polymeric material featuring water solubility lower than 200 grams / liter is or comprises a polyester, for example, a polycaprolactone, having an average molecular weight (MW) lower than 1,000 or lower than 500 grams / mol (Component L3).

[0042] According to some embodiments of any of the embodiments described herein, the at least one polymeric material featuring water solubility lower than 200 grams / liter features low Tg (Tg lower than 0, or lower than -20 °C).

[0043] According to some embodiments of any of the embodiments described herein, a total amount of the at least one non-curable material (Component L) is at least 40 % by weight of the total weight of the formulation.

[0044] According to some embodiments of any of the embodiments described herein, a total amount of the at least one non-curable material (Component L) ranges from 20 to 60, or from 30 to 60, or from 40 to 60, or from 40 to 50, or from 45 to 55, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.According to some embodiments of any of the embodiments described herein, the at least one non-curable material (Component L) further comprises at least one of a polymeric material featuring water solubility higher than 200 grams / liter (e.g., poly(alkylene glycol)) (Component L2) and a non-poly meric polyol (e.g., diol) (Component LI).

[0045] According to some embodiments of any of the embodiments described herein, Component M comprises an oligomeric or polymeric chain that renders it miscible with the non-curable polymeric material Component L3 and / or L4.

[0046] According to some embodiments of any of the embodiments described herein, Component M has a molecular weight lower than 1,000, or lower than 600 or lower than 500 grams / mol.

[0047] According to some embodiments of any of the embodiments described herein, Component M and the non-curable material (Component L3 and / or Component L4) are selected chemically compatible with one another (e.g., the Component M comprises an oligomeric or polymeric chain featuring repeating backbone units which are the same or are structurally similar).

[0048] According to some embodiments of any of the embodiments described herein, Component M comprises an oligomeric or polymeric polyester (e.g., polycaprolactone) chain and the non-curable polymeric material is or comprises a polyester (e.g., polycaprolactone).

[0049] According to some embodiments of any of the embodiments described herein, Component M is an acrylate featuring the oligomeric or polymeric chain that renders it miscible with the non-curable polymeric material Component L3 and / or L4 (e.g., an oligomeric or polymeric polyester (e.g., polycaprolactone) chain).

[0050] According to some embodiments of any of the embodiments described herein, an amount of the Component M ranges from 5 to 15, preferably from 9 to 15, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0051] According to some embodiments of any of the embodiments described herein, Component E comprises at least one mono-functional acrylate (Component E2 and / or Component E3).

[0052] According to some embodiments of any of the embodiments described herein, each of the at least one mono-functional (meth)acrylate, preferably at least one mono-functional acrylate, in Component E has a molecular weight of no more than 500, or of from 100 to 500 grams / mol, including any intermediate values and subranges therebetween.

[0053] According to some embodiments of any of the embodiments described herein, Component E comprises at least one hydrophilic or amphiphilic (meth)acrylate, preferably at least one hydrophilic or amphiphilic acrylate (Component E3).According to some embodiments of any of the embodiments described herein, Component E comprises at least one mono-functional (meth)acrylate that features Tg higher than 80, or higher than 100 °C.

[0054] According to some embodiments of any of the embodiments described herein, Component E comprises at least one hydrophilic or amphiphilic (meth)acrylate, preferably at least one hydrophilic or amphiphilic acrylate (Component E3) that features Tg higher than 80, or higher than 100 °C.

[0055] According to some embodiments of any of the embodiments described herein, Component E comprises at least one alicyclic, optionally hydrophobic, (meth)acrylate, preferably at least one alicyclic, optionally hydrophobic acrylate (Component E2).

[0056] According to some embodiments of any of the embodiments described herein, Component E comprises at least one mono-functional (meth)acrylate that features Tg lower than 80, or lower than 50, °C.

[0057] According to some embodiments of any of the embodiments described herein, Component E comprises at least one alicyclic, optionally hydrophobic, (meth)acrylate, preferably at least one alicyclic, optionally hydrophobic acrylate (Component E2), that features Tg lower than 80, or lower than 50, or of from 20 to 60, or of from 20 to 50, °C, including any intermediate values and subranges therebetween.

[0058] According to some embodiments of any of the embodiments described herein, Component E comprises at least one hydrophilic or amphiphilic (meth)acrylate, preferably at least one hydrophilic or amphiphilic acrylate (Component E3) and at least one alicyclic, optionally hydrophobic, (meth)acrylate, preferably at least one alicyclic, optionally hydrophobic acrylate (Component E2).

[0059] According to some embodiments of any of the embodiments described herein, a weight ratio of the Component E2 and the Component E3 ranges from 2:1 to 1:1, or from 1.5:1 to 1:1, including any intermediate values and subranges therebetween.

[0060] According to some embodiments of any of the embodiments described herein, an amount of the Component E2 is at least 10 %, or ranges from 10 to 20, or from 10 to 15, or from 10 to 12, %, by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0061] According to some embodiments of any of the embodiments described herein, an amount of the Component E3 is no more than 10 %, or ranges from 5 to 15, or from 5 to 10, %, by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.According to some embodiments of any of the embodiments described herein, a total amount of the Component E ranges from 10 to 40, or from 15 to 40, or from 15 to 30, or from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0062] According to some embodiments of any of the embodiments described herein, Component D2 comprises a multi-functional ethoxylated aromatic methacrylate featuring at least 10 ethoxylated groups, features, when hardened, Tg lower than 0 °C, and has a molecular weight of at least 1,000 grams / mol.

[0063] According to some embodiments of any of the embodiments described herein, an amount of the Component D2 ranges from 5 to 15, or from 10 to 15, or from 10 to 12, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0064] According to some embodiments of any of the embodiments described herein, the curable formulation further comprises the reactive diluent (Component K).

[0065] According to some embodiments of any of the embodiments described herein, Component K comprises a di-functional curable material.

[0066] According to some embodiments of any of the embodiments described herein, Component K is or comprises a divinyl ether.

[0067] According to some embodiments of any of the embodiments described herein, Component K has a molecular weight lower than 500, or lower than 300, grams / mol.

[0068] According to some embodiments of any of the embodiments described herein, an amount of the Component K is lower than 10, or lower than 5, %, or ranges from 1 to 10, or from 1 to 8, or from 1 to 5, or from 3 to 8 or from 3 to 5, 5, by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0069] According to some embodiments of any of the embodiments described herein, the curable formulation further comprises a multi-functional (e.g., tri-functional) (meth)acrylate (Component F).

[0070] According to some embodiments of any of the embodiments described herein, Component F is or comprises a multi-functional (e.g., tri-functional) acrylate.

[0071] According to some embodiments of any of the embodiments described herein, Component F is or comprises a multi-functional (e.g., tri-functional) hydrophilic (meth) acrylate.

[0072] According to some embodiments of any of the embodiments described herein, Component F comprises a multi-functional (e.g., tri-functional) cyclic (meth)acrylate (e.g., cyanurate) (Component Fl).According to some embodiments of any of the embodiments described herein, an amount of the Component F (e.g., Component Fl) ranges from 1 to 5, or from 1 to 3, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0073] According to some embodiments of any of the embodiments described herein, the curable formulation further comprises a dispersant.

[0074] According to some embodiments of any of the embodiments described herein, the dispersant is or comprises a non-curable dispersant.

[0075] According to some embodiments of any of the embodiments described herein, an amount of the dispersant ranges from 0.01 to 1, or from 0.01 to 0.5, or from 0.05 to 0.5, or from 0.1 to 0.5, or from 0.1 to 0.3, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0076] According to some embodiments of any of the embodiments described herein, the curable formulation further comprises a polymerization inhibitor.

[0077] According to some embodiments of any of the embodiments described herein, the curable formulation further comprises a photoinitiator.

[0078] According to some embodiments of any of the embodiments described herein, an amount of the photoinitiator ranges from 1 to 3, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0079] According to some embodiments of any of the embodiments described herein, the curable formulation is usable as a support material formulation in the additive manufacturing of the three-dimensional object.

[0080] According to some embodiments of any of the embodiments described herein, the three-dimensional object is or comprises a denture structure.

[0081] According to some embodiments of any of the embodiments described herein, the curable formulation is usable as a support material formulation in combination with at least one of a Type A formulation and a Type B formulation, as described herein in any of the respective embodiments and any combination thereof.

[0082] According to some embodiments of any of the embodiments described herein, the additive manufacturing of the object is configured to form a hardened mixed layer that comprises a hardened support material formed of the support material formulation and a hardened modeling material formed of at least one modeling material formulation.

[0083] According to some embodiments of any of the embodiments described herein, the three-dimensional object features in at least portion thereof at least one of: Izod impact resistance of at least 100 or at least 120 J / mol; Durability in a drop test as described herein of about 100% in thefirst drop, at least 80 % in the second drop and at least 60 % in the third drop; and mechanical and physical properties in accordance with the requirements of ISO 20795-1.

[0084] According to an aspect of some embodiments of the present invention there is provided a method of additive manufacturing a three-dimensional object, the method comprising dispensing a plurality of layers in a configured pattern corresponding to the shape of the denture object, thereby forming the object, wherein the formation of each of at least a few of the layers comprises dispensing at least one modeling material formulation and at least one support material formulation, and exposing the dispensed formulation to a curing condition to thereby form a hardened modeling material and a hardened support material, wherein the at least one support material formulation is the curable formulation as described herein in any of the respective embodiments and any combination thereof.

[0085] According to some embodiments of any of the embodiments described herein, the dispensing is such that at least a portion of an outer layer of the object comprises a hardened mixture of a hardened modeling material formulation and a hardened support material formulation.

[0086] According to some embodiments of any of the embodiments described herein, a thickness of the outer layer ranges from 100 to 1000 micrometers or from 100 to 500, or from 200 to 500, micrometers, including any intermediate values and subranges therebetween.

[0087] According to some embodiments of any of the embodiments described herein, the dispensing is of a set of at least two modeling material formulations.

[0088] According to some embodiments of any of the embodiments described herein, for at least a few of the layers the dispensing is such that forms a core region and at least one outermost encapsulating region at least partially enveloping or surrounding the core region, wherein each of the core region and the encapsulating region is formed of a different modeling material formulation or a different combination of the at least two modeling material formulations.

[0089] According to some embodiments of any of the embodiments described herein, for at least a few of the layers the dispensing is such that further forms an inner encapsulating region, at least partially enveloping or surrounding the core region, and optionally one or more intermediate encapsulating regions, at least partially enveloping or surrounding the inner encapsulating region, wherein the outermost encapsulating region at least partially surrounds the outermost intermediate encapsulating region, wherein each of the core region and the inner encapsulating region, each of the inner encapsulating region and the intermediate encapsulating region, if present, or the outermost encapsulating region, and each of the intermediate encapsulating region, if present, and the outermost encapsulating region is formed of a different modeling material formulation or a different combination of the at least two modeling material formulations.According to some embodiments of any of the embodiments described herein, the core region is formed of a Type B formulation as described herein in any of the respective embodiments, the inner encapsulating region is formed of a Type A formulation as described herein in any of the respective embodiments, the intermediate encapsulating region is formed of the Type B formulation and the outermost encapsulating region is formed of the Type A formulation, as these formulations are described herein in any of the respective embodiments.

[0090] According to some embodiments of any of the embodiments described herein, the formation of each of at least a few of the layers comprises dispensing at least a first modeling material formulation and a second modeling material formulation, and exposing the dispensed formulations to a curing condition to thereby form a cured modeling material, and is such that forms a core region and at least one outermost encapsulating region at least partially enveloping or surrounding the core region, wherein the core region of formed of the second modeling material formulation or a first combination of the first and the second modeling material formulations, and the encapsulating region is formed of the first modeling material formulation or a second combination of the first and the second modeling material formulation, the second combination being different from the first combination, wherein the first and the second modeling material formulations are such that: the second formulation or the first combination features, when hardened, impact resistance that is higher by at least 2-folds, or at least 5-folds, or at least 10-folds of an impact resistance of the first formulation or the second combination; and / or the first formulation or the second combination features, when hardened, flexural modulus that is higher by at least 2-folds, or at least 5-folds, or at least 10-folds of a flexural modulus of the second formulation or the first combination.

[0091] According to some embodiments of any of the embodiments described herein, the dispensing is such that a hardened support structure is formed, wherein the hardened support structure comprises a hardened bulk embedded with hardened reinforcing elements.

[0092] According to an aspect of some embodiments of the present invention there is provided a three-dimensional assembly fabricated by an additive manufacturing process, the assembly comprising a hardened object and a hardened sacrificial structure supporting at least one surface of the hardened object, the hardened sacrificial structure comprising a bulk embedded with reinforcing elements arranged in a first region and a second region within the bulk, wherein the second region is farther from the at least one surface than the first region, and wherein at least a majority of reinforcing elements within the second region are mechanically tougher than at least a majority of reinforcing elements within the first region.According to some embodiments of any of the embodiments described herein, the bulk is washable off the at least one surface by a jet of water.

[0093] According to some embodiments of any of the embodiments described herein, the bulk is peelable off the at least one surface.

[0094] According to some embodiments of any of the embodiments described herein, the bulk is made of a support material and the reinforcing elements are made of modeling materials.

[0095] According to some embodiments of any of the embodiments described herein, a density of the reinforcing elements is higher in the first region than in the second region.

[0096] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the second region are characterized by a higher elongation at break value than the majority of reinforcing elements within the first region.

[0097] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the first region are characterized by a higher flexural modulus than the majority of reinforcing elements within the second region.

[0098] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the second region are characterized by a higher impact resistance than the majority of reinforcing elements within the first region.

[0099] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the second region are larger that the majority of reinforcing elements within the first region, both laterally and vertically.

[0100] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements are elongated along a building direction of the assembly.

[0101] According to some embodiments of any of the embodiments described herein, a length of the reinforcing elements is shorter than a height of the bulk along the building direction.

[0102] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the first region are shaped as pillars.

[0103] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the second region are shaped as helices.

[0104] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the first region are made of a hardened Type A formulation, as described herein in any of the respective embodiments.

[0105] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the second region are made of a hardened Type B formulation, as described herein in any of the respective embodiments.According to an aspect of some embodiments of the present invention there is provided a method of additive manufacturing a three-dimensional assembly, the method comprising forming a plurality of layers, each responding to a pattern of a slice of computer object data describing the assembly, by dispensing and hardening a plurality of building material formulations, wherein for at least one layer of the assembly the forming comprises: forming within the layer of the assembly a layer of an object; and forming within the layer of the assembly a layer of a sacrificial structure at least partially surrounding the layer of the object by dispensing and hardening building material formulations to form a bulk embedded with reinforcing elements arranged in a first region and a second region within the bulk, wherein the second region is farther from the layer of the object than the first region, and wherein the building material formulations for the reinforcing elements are selected such that once the reinforcing elements are hardened, at least a majority of reinforcing elements within the second region are mechanically tougher than at least a majority of reinforcing elements within the first region.

[0106] According to some embodiments of any of the embodiments described herein, the building material formulations (e.g., one or more support material formulation and / or one or more modeling material formulations) for the bulk are selected such that once the bulk is hardened the bulk is washable off the at least one surface by a jet of water.

[0107] According to some embodiments of any of the embodiments described herein, the building material formulations (e.g., one or more support material formulation and / or one or more modeling material formulations) for the bulk are selected such that once the bulk is hardened is peelable off the at least one surface.

[0108] According to some embodiments of any of the embodiments described herein, the bulk is made of a (hardened) support material and the reinforcing elements are made of (hardened) modeling materials.

[0109] According to some embodiments of any of the embodiments described herein, a density of the reinforcing elements is higher in the first region than in the second region.

[0110] According to some embodiments of any of the embodiments described herein, the building material formulations (e.g., one or more support material formulation and / or one or more modeling material formulations) for the reinforcing elements are selected such that once the reinforcing elements are hardened, the majority of reinforcing elements within the second region are characterized by a higher elongation at break value than the majority of reinforcing elements within the first region.

[0111] According to some embodiments of any of the embodiments described herein, the building material formulations (e.g., one or more support material formulation and / or one or more modelingmaterial formulations) for the reinforcing elements are selected such that once the reinforcing elements are hardened, the majority of reinforcing elements within the first region are characterized by a higher flexural modulus than the majority of reinforcing elements within the second region.

[0112] According to some embodiments of any of the embodiments described herein, the building material formulations (e.g., one or more support material formulation and / or one or more modeling material formulations) for the reinforcing elements are selected such that once the reinforcing elements are hardened, the majority of reinforcing elements within the second region are characterized by a higher impact resistance than the majority of reinforcing elements within the first region.

[0113] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the second region are larger that the majority of reinforcing elements within the first region, both laterally and vertically.

[0114] According to some embodiments of any of the embodiments described herein, the reinforcing elements are elongated along a building direction of the assembly.

[0115] According to some embodiments of any of the embodiments described herein, a length of the reinforcing elements is shorter than a height of the bulk along the building direction.

[0116] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the first region are shaped as pillars.

[0117] According to some embodiments of any of the embodiments described herein, the majority of reinforcing elements within the second region are shaped as helices.

[0118] According to some embodiments of any of the embodiments described herein, for the majority of reinforcing elements within the first region, the building material formulations comprise a Type A modeling material formulation, as described herein in any of the respective embodiments.

[0119] According to some embodiments of any of the embodiments described herein, for the majority of reinforcing elements within the second region, the building material formulations comprise a Type B modeling material formulation, as described herein in any of the respective embodiments.

[0120] According to an aspect of some embodiments of the present invention there is provided a computerized controller for an additive manufacturing system, the computerized controller comprising a circuit configured for operating the additive manufacturing system to execute the method as described herein in any of the respective embodiments.

[0121] According to an aspect of some embodiments of the present invention there is provided an additive manufacturing system comprising a plurality of arrays of nozzles configured to dispensea plurality of building material formulations (e.g., one or more support material formulation and / or one or more modeling material formulations), a hardening system for hardening the building material formulations once dispensed, and the computerized controller as described herein in any of the respective embodiments.

[0122] According to some embodiments of any of the embodiments described herein, the object is or comprises a denture structure.

[0123] According to some embodiments of any of the embodiments described herein, the denture structure is selected from a denture base, an artificial tooth, artificial teeth and a monolithic structure of a denture base and artificial teeth.

[0124] According to an aspect of some embodiments of the present invention there is provided a denture structure obtained by any one of the methods as described herein in any of the respective embodiments and any combination thereof.

[0125] According to some embodiments of any of the embodiments described herein, the denture structure is a monolithic structure of a denture base and artificial teeth.

[0126] According to some embodiments of any of the embodiments described herein, the denture structure features mechanical and physical properties in accordance with the requirements of ISO 20795-1 and biocompatibility properties in accordance with the requirements of ISO 10993-1.

[0127] According to some embodiments of any of the embodiments described herein, the denture structure features flexural modulus, Flexural strength, Kmax and Wf in accordance with the requirements of ISO 20795-1 and durability in a drop test as described herein.

[0128] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and / or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

[0129] Implementation of the method and / or system of embodiments of the invention can involve performing or completing selected tasks manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of embodiments of the method and / or system of the invention, several selected tasks could be implemented by hardware, by software or by firmware or by a combination thereof using an operating system.

[0130] For example, hardware for performing selected tasks according to embodiments of the invention could be implemented as a chip or a circuit. As software, selected tasks according toembodiments of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In an exemplary embodiment of the invention, one or more tasks according to exemplary embodiments of method and / or system as described herein are performed by a data processor, such as a computing platform for executing a plurality of instructions. Optionally, the data processor includes a volatile memory for storing instructions and / or data and / or a non-volatile storage, for example, a magnetic hard-disk and / or removable media, for storing instructions and / or data. Optionally, a network connection is provided as well. A display and / or a user input device such as a keyboard or mouse are optionally provided as well.

[0131] BRIEF DESCRIPTION OF THE DRAWINGS

[0132] Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

[0133] In the drawings:

[0134] FIGs. 1A-D are schematic illustrations of an additive manufacturing system according to some embodiments of the invention;

[0135] FIGs. 2A-2C are schematic illustrations of printing heads according to some embodiments of the present invention;

[0136] FIGs. 3 A and 3B are schematic illustrations demonstrating coordinate transformations according to some embodiments of the present invention;

[0137] FIGs. 4A-B present a notching apparatus (FIG. 4A) and determination of the Kmax and Wf parameters (FIG. 4B), in accordance with ISO 20795-1;

[0138] FIG. 5 presents a schematic illustration of an exemplary calculation of the un-notched impact resistance that a material should feature in order to exhibit a desired performance in a “drop test” as described herein;

[0139] FIG. 6 is a schematic illustration showing a cross-section view of an object part having a core region enclosed by a plurality of encapsulating regions defining an onion-like structure, according to some embodiments of the present invention;

[0140] FIGs. 7A-B are bar graphs showing the un-notched impact resistance (FIG. 7A) and durability in a drop test (FIG. 7B) of exemplary support material formulations tested while designing support material formulations according to the present embodiments;FIG. 8 is a bar graph showing the un-notched impact resistance of exemplary support material formulations according to the present embodiments, compared to reference formulations or materials;

[0141] FIG. 9 is an image showing a representative example of a flaking phenomenon on an outer surface of a denture object as obtained in experiments performed according to some embodiments of the present invention;

[0142] FIGs. 10A-C are schematic illustrations of a three-dimensional assembly according to some embodiments of the present invention;

[0143] FIG. 11 is a flowchart diagram of a method suitable for additive manufacturing of three-dimensional assembly in layers, according to some embodiments of the present invention;

[0144] FIG. 12 is a schematic illustration showing a representative example of a hardened layer of a three-dimensional assembly according to some embodiments of the present invention;

[0145] FIG. 13 A and 13B are schematic illustrations of a slice of a combined computer object dataset used in experiments performed according to some embodiments of the present invention for fabricating a sacrificial structure, where FIG. 13B is a magnified view of the region marked by a thick black rectangle in FIG. 13 A; and

[0146] FIG. 14 is an image showing a representative example of an outer surface of a denture object which is substantially devoid of flaking as obtained in experiments performed according to some embodiments of the present invention.

[0147] DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

[0148] The present invention, in some embodiments thereof, relates to additive manufacturing, and more particularly, but not exclusively, to support material formulations usable in additive manufacturing of three-dimensional objects that feature, in at least a portion thereof, a hardened material that features high fracture toughness. The present invention, in some embodiments thereof, further relates to a three-dimensional assembly, and a method suitable for fabricating the three-dimensional assembly.

[0149] The present invention, in some embodiments thereof, relates to additive manufacturing and, more particularly, but not exclusively, to curable formulations which are usable in additive manufacturing of dental prostheses, including denture teeth, denture base and monolithic denture structures.

[0150] Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and / or methods set forth in the following description and / orillustrated in the drawings and / or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

[0151] Herein throughout, the term “object” describes a final product of the additive manufacturing. This term refers to the product obtained by a method as described herein, after removal of the support material, if such has been used as part of the uncured building material, and / or after post treatment (e.g., photobleaching such as described herein).

[0152] The term "object" as used herein throughout refers to a whole object or a part thereof. Herein throughout, the phrase “cured modeling material” which is also referred to herein as “hardened” or “solidified” modeling material describes the part of the building material that forms the object, as defined herein, upon exposing the dispensed building material to a curing condition (and optionally post-treatment), and, optionally, if a support material has been dispensed, upon removal of the cured support material, as described herein. The hardened modeling material can be a single hardened material or a mixture of two or more hardened materials, depending on the modeling material formulations used in the method, as described herein.

[0153] The phrases “cured modeling material”, “hardened modeling material”, “solidified modeling material” or “cured / hardened / solidified modeling material formulation” can be regarded as a cured building material wherein the building material consists only of a modeling material formulation (and not of a support material formulation). That is, this phrase refers to the portion of the building material, which is used to provide the final object.

[0154] Herein throughout, the phrase “modeling material formulation”, which is also referred to herein interchangeably as “modeling formulation”, “modeling material” “model material” or simply as “formulation”, describes a part or all of the uncured building material which is dispensed so as to form the object, as described herein. The modeling material formulation is an uncured modeling formulation (unless specifically indicated otherwise), which, upon exposure to a condition that effects curing, may form the object or a part thereof.

[0155] In some embodiments of the present invention, a modeling material formulation is formulated for use in three-dimensional inkjet printing and is able to form a three-dimensional object on its own,

[0156]

[0157] without having to be mixed or combined with any other substance.

[0158] An uncured building material can comprise one or more modeling material formulations, and can be dispensed such that different parts of the object are made, upon being hardened, of different cured modeling formulations, and hence are made of different hardened (e.g., cured) modeling materials or different mixtures or combinations of hardened (e.g., cured) modeling materials.The final three-dimensional object is made of the modeling material or a combination of modeling materials or a combination of modeling material / s and support material / s or modification thereof (e.g., following curing). All these operations are well-known to those skilled in the art of solid freeform fabrication.

[0159] In some exemplary embodiments of the invention, an object is manufactured by dispensing a building material (uncured) that comprises two or more different modeling material formulations, each modeling material formulation from a different dispensing head and / or nozzle of the inkjet printing apparatus. The modeling material formulations are optionally and preferably deposited in layers during the same pass of the printing heads. The modeling material formulations and / or combination of formulations within the layer are selected according to the desired properties of the object and according to the method parameters described herein.

[0160] An uncured building material, according to at least some of the present embodiments, further comprises one or more support material formulations.

[0161] Herein throughout, the phrase “support material formulation”, which is also referred to herein interchangeably as “support formulation”, describes a part of the uncured building material which is dispensed so as to form the support material, as described herein. The support material formulation is an uncured formulation. When a support material formulation is a curable formulation, it forms, upon exposure to a curing condition, a hardened support material.

[0162] Herein throughout, the phrase “hardened support material” is also referred to herein interchangeably as “cured support material” or simply as “support material” and describes the part of the building material that is intended to support the fabricated final object during the fabrication process, and which is at least partially removed once the process is completed and after a hardened modeling material is obtained.

[0163] Support materials, which can be either liquid materials or hardened, typically gel materials, are also referred to herein as sacrificial materials, which are removable after layers are dispensed and exposed to a curing energy, to thereby expose the shape of the final object.

[0164] Currently practiced support materials typically comprise a mixture of curable and non-curable materials.

[0165] Currently practiced support materials are typically water miscible, or water-dispersible or water-soluble.

[0166] Herein throughout, the term “water-miscible” describes a material which is at least partially dissolvable or dispersible in water, that is, at least 50 % of the molecules move into the water upon mixing at room temperature, e.g., when mixed with water in equal volumes or weights, at roomtemperature (e.g., of from 15 to 30 or from 15 to 25, or from 20 to 25, or from 20 to 30, °C). This term encompasses the terms “water-soluble” and “water dispersible”.

[0167] Herein throughout, the term “water-soluble” describes a material that when mixed with water in equal volumes or weights, at room temperature as described herein, a homogeneous solution is formed.

[0168] Herein throughout, the term “water-dispersible” describes a material that forms a homogeneous dispersion when mixed with water in equal volumes or weights, at room temperature as described herein.

[0169] Water solubility of a material can be found is publicly available databases or can be readily determined by simple methods known in the art (e.g., by determining the maximal amount of the material that dissolves in 1 liter of water).

[0170] According to some embodiments, the term “water solubility” as used herein reflects the Equivalent Concentration of Active Hydration (ECAH) of a compound or a material, which describes the effective concentration of a compound or a material when it interacts with water, considering the compound and the hydration and solvation effects that influence its solubility, and is presented herein as the number of grams of the compound or material that can be dissolved in one liter water at 20-25 °C (e.g., at room temperature).

[0171] Herein, the term “water solubility” in the context of ECAH is used to define oligomeric or polymeric materials, e.g., non-curable such materials as described herein (e.g., Component L3 and L4).

[0172] Herein throughout and in the art, the phrase “water absorption”, which is used herein and in the art interchangeably as “water absorbance”, whereby both these phrases are abbreviated as WA, describes an amount of water that a material is capable of absorbing, relative to its weight, when immersed in water at room temperature, for 24 hours.

[0173] The method and system of the present embodiments manufacture three-dimensional objects based on computer object data in a layer-wise manner by forming a plurality of layers in a configured pattern corresponding to the shape of the objects. The computer object data can be in any known format, including, without limitation, a Standard Tessellation Language (STL) or a StereoLithography Contour (SLC) format, Virtual Reality Modeling Language (VRML), Additive Manufacturing File (AMF) format, Drawing Exchange Format (DXF), Polygon File Format (PLY) or any other format suitable for Computer-Aided Design (CAD).

[0174] Each layer is formed by an additive manufacturing apparatus which scans a two-dimensional surface and patterns it. While scanning, the apparatus visits a plurality of target locations on the two-dimensional layer or surface, and decides, for each target location or a groupof target locations, whether or not the target location or group of target locations is to be occupied by building material formulation, and which type of building material formulation is to be delivered thereto. The decision is made according to a computer image of the surface.

[0175] In preferred embodiments of the present invention the AM comprises three-dimensional printing, more preferably three-dimensional inkjet printing. In these embodiments a building material formulation is dispensed from a dispensing head having a set of nozzles to deposit building material formulation in layers on a supporting structure. The AM apparatus thus dispenses building material formulation(s) in target locations which are to be occupied and leaves other target locations void. The apparatus typically includes a plurality of dispensing heads, each of which can be configured to dispense a different building material formulation. Thus, different target locations can be occupied by different building material formulations. The types of building material formulations can be categorized into two major categories: modeling material formulation and support material formulation. The support material formulation serves as a supporting matrix or construction for supporting the object or object parts during the fabrication process and / or other purposes, e.g., providing hollow or porous objects. Support constructions may additionally include modeling material formulation elements, e.g., for further support strength.

[0176] The final three-dimensional object is made of the modeling material or a combination of modeling materials or of modeling and support materials or modification thereof (e.g., following curing). All these operations are well-known to those skilled in the art of solid freeform fabrication.

[0177] In some exemplary embodiments of the invention an object is manufactured by dispensing one or more different modeling material formulations. When more than one modeling material formulation is used, each modeling material formulation is optionally and preferably dispensed from a different array of nozzles (belonging to the same or distinct dispensing heads) of the AM apparatus.

[0178] In some embodiments, the dispensing head of the AM apparatus is a multi-channel dispensing head, in which case different modeling material formulations can be dispensed from two or more arrays of nozzles that are located in the same multi-channels dispensing head. In some embodiments, arrays of nozzles that dispense different modeling material formulations are located in separate dispensing heads, for example, a first array of nozzles dispensing a first modeling material formulation is located in a first dispensing head, and a second array of nozzles dispensing a second modeling material formulation is located in a second dispensing head.

[0179] In some embodiments, an array of nozzles that dispense a modeling material formulation and an array of nozzles that dispense a support material formulation are both located in the same multi-channels dispensing head. In some embodiments, an array of nozzles that dispense amodeling material formulation and an array of nozzles that dispense a support material formulation are located in separate dispensing head heads.

[0180] The (uncured) building material formulations (e.g., one or more modeling material formulations and / or one or more support material formulations) are optionally and preferably deposited in layers during the same pass of the printing heads. The (uncured)building material formulations and combination(s) of building material formulations within the layer are selected according to the desired properties of the object.

[0181] As discussed herein, the present inventors have designed and successfully prepared and practiced novel building material formulations that can be employed in additive manufacturing of a denture structure. The newly designed formulations, and the newly designed combinations of different formulations, are usable, for example, in additive manufacturing a monolithic denture structure that comprises a denture base and artificial teeth, preferably by three-dimensional inkjet printing.

[0182] The present inventors have further designed new additive manufacturing processes that can be beneficially used in additive manufacturing of denture structures as described herein.

[0183] Embodiments of the present invention relate to newly designed support material formulations that can be efficiently used in combination with various modeling material formulations, including modeling material formulations that are usable in additive manufacturing (e.g., three-dimensional inkjet printing) of a denture structure. Embodiments of the present invention further relate to newly designed additive manufacturing processes that are usable in additive manufacturing of denture structures, and to denture structures formed thereby.

[0184] Herein and in the art, the phrase “denture structure” describes a dental prosthesis intended to replace a missing tooth or teeth. Denture structures encompass an artificial tooth or teeth, and a base structure to support the artificial tooth or teeth. Denture structures can be partial dentures, typically comprised of a denture base and one tooth or several teeth, or complete dentures, typically comprised of a denture base and a plurality of teeth of the mandibular arch or the maxillary arch. Typically, a combination of complete dentures of both the mandibular arch and the maxillary arch are required. Denture structures are typically removable.

[0185] Embodiments of the present invention encompass additive manufacturing of artificial teeth, a denture base structure, each alone, and preferably, a monolithic structure of a denture base and artificial tooth or teeth. In some embodiments, the monolithic denture structure is a complete structure that comprises a base structure and a set of artificial teeth of the mandibular arch and / or the maxillary arch.The manufacture of such a monolithic denture structure is enabled by the digital control of the color and mechanical properties of different parts of the structure, which in turn is enabled by the additive manufacturing method such as described herein and the respective newly designed curable formulations.

[0186] Method:

[0187] According to an aspect of some embodiments of the present invention there is provided a method of additive manufacturing of a three-dimensional object, as described herein. The method of the present embodiments is usable for manufacturing a denture structure, as defined herein.

[0188] The method is generally effected by sequentially forming a plurality of layers in a configured pattern corresponding to the shape of the object, such that formation of each of at least a few of said layers, or of each of said layers, comprises dispensing a building material (uncured) which comprises one or more modeling material formulation(s) and one or more support material formulation(s), and exposing the dispensed modeling material to a curing condition, preferably a curing energy (e.g., irradiation) to thereby form a hardened (e.g., cured) modeling material, a hardened (e.g., cured) support material, and preferably a mixed layer that comprises a hardened modeling material and a hardened support material (as described herein for “matte” mode), as described in further detail hereinafter.

[0189] According to these embodiments, the building material comprises, as a modeling material formulation, a Type B modeling material formulation as described herein in any of the respective embodiments and any combination thereof. According to some of these embodiments, the building material further comprises, as other one or more modeling material formulation(s), one or more Type A modeling material formulation(s) as described herein in any of the respective embodiments and any combination thereof. According to these embodiments, the building material comprises, as a modeling material formulation, a set of formulations as described herein in any of the respective embodiments and any combination thereof.

[0190] According to these embodiments, the building material comprises, as a modeling material formulation, a Type A modeling material formulation as described herein in any of the respective embodiments and any combination thereof. According to some of these embodiments, the building material further comprises, as other one or more modeling material formulation(s), one or more Type B modeling material formulation(s) as described herein in any of the respective embodiments and any combination thereof. According to these embodiments, the building material comprises, as a modeling material formulation, a set of formulations as described herein in any of the respective embodiments and any combination thereof.In some exemplary embodiments of the invention an object is manufactured by dispensing a building material (uncured) that comprises two or more different modeling material formulations, for example, as described hereinbelow. In some of these embodiments, each modeling material formulation is dispensed from a different array of nozzles belonging to the same or distinct dispensing heads of the inkjet printing apparatus, as described herein.

[0191] In some embodiments, two or more such arrays of nozzles that dispense different modeling material formulations are both located in the same printing head of the AM apparatus (i.e., multichannels printing head). In some embodiments, arrays of nozzles that dispense different modeling material formulations are located in separate printing heads, for example, a first array of nozzles dispensing a first modeling material formulation is located in a first printing head, and a second array of nozzles dispensing a second modeling material formulation is located in a second printing head.

[0192] In some embodiments, an array of nozzles that dispense a modeling material formulation and an array of nozzles that dispense a support material formulation are both located in the same printing head. In some embodiments, an array of nozzles that dispense a modeling material formulation and an array of nozzles that dispense a support material formulation are located in separate printing heads.

[0193] The modeling material formulations are optionally and preferably deposited in layers during the same pass of the printing heads. The modeling material formulations and / or combination of formulations within the layer are selected according to the desired properties of the object, and as further described in detail hereinbelow. Such a mode of operation is also referred to herein as “multi-material’ ’ .

[0194] The phrase “digital materials”, as used herein and in the art, describes a combination of two or more materials on a microscopic scale or voxel level such that the printed zones of a specific material are at the level of few voxels, or at a level of a voxel block. Such digital materials may exhibit new properties that are affected by the selection of types of materials and / or the ratio and relative spatial distribution of two or more materials.

[0195] In exemplary digital materials, the modeling material of each voxel or voxel block, obtained upon curing, is independent of the modeling material of a neighboring voxel or voxel block, obtained upon curing, such that each voxel or voxel block may result in a different model material and the new properties of the whole part are a result of a spatial combination, on the voxel level, of several different model materials.

[0196] The phrase “digital material formulations”, as used herein and in the art, describes a combination of two or more material formulations on a pixel level or voxel level such that pixelsor voxels of different material formulations are interlaced with one another over a region. Such digital material formulations may exhibit new properties that are affected by the selection of types of material formulations and / or the ratio and relative spatial distribution of two or more material formulations.

[0197] As used herein, a "voxel" of a layer refers to a physical three-dimensional elementary volume within the layer that corresponds to a single pixel of a bitmap describing the layer. The size of a voxel is approximately the size of a region that is formed by a building material, once the building material is dispensed at a location corresponding to the respective pixel, leveled, and solidified.

[0198] Herein throughout, whenever the expression “at the voxel level” is used in the context of a different material and / or properties, it is meant to include differences between voxel blocks, as well as differences between voxels or groups of few voxels. In preferred embodiments, the properties of the whole part are a result of a spatial combination, on the voxel block level, of several different model materials.

[0199] In some embodiments of any of the embodiments of the present invention, once a layer is dispensed as described herein, exposure to a curing condition (e.g., curing energy) as described herein is effected. In some embodiments, the curable materials are photocurable material, preferably UV-curable materials, and the curing condition is such that a radiation source emits UV radiation.

[0200] In some embodiments of any of the embodiments described herein, the UV irradiation is from a LED source, as described herein.

[0201] In some embodiments of any of the embodiments described herein, the curing condition comprises electromagnetic irradiation and the electromagnetic irradiation is from a LED source.

[0202] In some embodiments of any of the embodiments described herein, the curing condition comprises UV irradiation.

[0203] In some embodiments, where the building material comprises also support material formulation(s), the method proceeds to removing the hardened support material (e.g., thereby exposing the adjacent hardened modeling material or the adjacent hardened mixed layer that comprises a hardened modeling material and hardened support material). This can be performed by mechanical and / or chemical means, as would be recognized by any person skilled in the art. A portion of the support material may optionally remain upon removal, for example, within a hardened mixed layer, as described herein.

[0204] In some embodiments, removal of hardened support material reveals a hardened mixed layer, comprising a hardened mixture of support material and modeling material formulation. Sucha hardened mixture at a surface (e.g., an outer layer) of an object may optionally have a relatively non-reflective appearance, also referred to herein as “matte”; whereas surfaces lacking such a hardened mixture (e.g., wherein support material formulation was not applied thereon) are described as “glossy” in comparison.

[0205] In some embodiments of any of the embodiments described herein, the method further comprises exposing the hardened (cured) modeling material, either before or after (preferably after) removal of a hardened (cured) support material, if such has been included in the building material, to a post-treatment condition, which can comprise exposure to heat and / or irradiation, optionally when immersed in an organic solvent, preferably a polar organic solvent such as an alcohol, more preferably a biocompatible, polar, organic solvent such as glycerol.

[0206] According to some embodiments of any of the embodiments described herein, one or more, or all of the dispensed modeling material formulation(s) is / are a modeling material formulation as described herein in any of the respective embodiments and any combination thereof for a Type A formulation and / or a Type B formulation.

[0207] According to some embodiments of any of the embodiments described herein, the dispensing is of two or more modeling material formulations, each independently being a modeling material formulation as described herein in any of the respective embodiments and any combination thereof. In some of these embodiments, the dispensing is of digital materials as described herein.

[0208] In exemplary embodiments, two or more formulations of a Type A formulation as described herein in any of the respective embodiments are employed, and these formulations differ from one another by the presence and / or type of a coloring agent and allows manufacturing a single object (e.g., a monolithic denture structure as described herein) featuring a plurality of colors and hues.

[0209] According to some embodiments of any of the embodiments described herein, the dispensing is further of a support material formulation, for example, a support material formulation as described herein in any of the respective embodiments and any combination thereof.

[0210] According to some embodiments of any of the embodiments described herein, once the support material is removed, the object is subjected to a post-curing treatment, or post-treatment.

[0211] In an exemplary post-treatment procedure, a printed object is subjected to support material removal (e.g., using a water jet), and is then treated sequentially with a solution of a strong base (e.g., sodium hydroxide) (e.g., using a water jet); glycerol (preferably while heating and UV irradiating the object for 0.5-4 hours, or 1-4, or 2-4, or 2-3 hours; and optionally an alcohol (e.g.,isopropyl alcohol). The object can be washed with tap water between being contacted with each of these components. The object can then be oven-dried or air-dried for at least 2 hours.

[0212] According to some embodiments of any of the embodiments described herein, the additive manufacturing is three-dimensional inkjet printing.

[0213] According to some embodiments of any of the embodiments described herein, the denture structure is selected from denture base, an artificial tooth, artificial teeth and a monolithic structure of a denture base and artificial teeth.

[0214] According to some embodiments of any of the embodiments described herein, the denture structure is a monolithic structure of a denture base and artificial teeth.

[0215] As demonstrated in the Examples section that follows, the present inventors have designed additive manufacturing processes or methods that employ digital materials, and which results in denture structures as described herein which meet the requirements of the respective ISO standards. Such additive manufacturing processes or methods employ, in at least a portion of the layers, or when forming at least a part of the object, two or more modeling material formulations that are dispensed so as to form an object part having a core region enclosed by a plurality of encapsulating regions defining an onion-like structure (also referred to as a layered structure or a core-shell structure) for that object part.

[0216] As used herein, "onion-like structure" is defined as a structure which includes a core region and a plurality of encapsulating regions each encapsulating a different volume size, wherein each encapsulating region encapsulates the core region, and wherein for any pair of the encapsulating regions one of the encapsulating regions of the pair is encapsulated by another encapsulating region of that pair. Conveniently, the encapsulating regions can be viewed as a series in which the encapsulating regions are ordered according to the size of the encapsulation volumes that are encapsulated by them. With such a view, the zth encapsulating region of the series encapsulates a volume Vi that contains the core and all the z-1 encapsulating regions for which the encapsulation volume is smaller than Vz.

[0217] FIG. 6 illustrates a representative, non-limiting, example of an object part 800 in embodiment in which the object part has a core region 800a enclosed by three encapsulating regions 800b, 800c, 800d defining an onion-like structure. The structure of the four regions is onion-like because region 800b encapsulates core region 800a, region 800c encapsulates regions 800b and 800a, and region 800d encapsulates regions 800c, 800b and 800a.

[0218] It is to be noted that an object part can comprise only core region 800a and one encapsulating region (e.g., 800d), or a core region 800a and two encapsulating regions (e.g., 800cand 800d), or four or more encapsulating regions (e.g., further comprising encapsulating regions 800e, 800f, and so forth (not shown in FIG. 6).

[0219] Herein, the encapsulating regions (e.g., 800b, 800c, 800d in FIG. 6) are also referred to as “shells”, and the outermost encapsulating region shown as 800d in FIG. 6 is also referred to as outermost shell or coating.

[0220] According to an aspect of some embodiments of the present invention there is provided a method of additive manufacturing a denture object as described herein, in which for at least a few of the layers the dispensing is of at least two modeling material formulations, that is, a first modeling material formulation and a second modeling material formulation, and is such that forms a core region (e.g., 800a) and at least one encapsulating region (e.g., 800b, 800c, 800d in FIG. 6) at least partially enveloping or surrounding the core region, as described herein.

[0221] According to some of these embodiments, the object, or part thereof, that is formed of such layers and features an onion-like structure as described herein, comprises a core region 800a and a single encapsulating region, which is therefore the outermost encapsulating region or coating (that is, structure 800 would not include encapsulating regions 800b and 800c).

[0222] Alternatively, and preferably, the object, or part thereof, that is formed of such layers and features an onion-like structure as described herein, comprises a core region 800a, encapsulating region 800b, which is also referred to herein as an inner encapsulating region, or as shell 1, at least partially enveloping or surrounding core region 800a, encapsulating region 800c, which is also referred to herein as an intermediate encapsulating region, or shell 2, at least partially enveloping or surrounding the inner encapsulating region 800b, and at least partially surrounded or enveloped by the outermost encapsulating region (coating) 800d.

[0223] According to some embodiments of any of the embodiments described herein, a thickness of each of the inner encapsulating regions (e.g., 800b), if present, an intermediate encapsulating region (e.g., 800c), if present, and the outermost encapsulating region (e.g., 800d) independently ranges from 0.1 mm to 2 mm, or from 0.2 to 1.5 mm, or from 0.3 to 1 mm, including any intermediate values and subranges therebetween.

[0224] According to some embodiments of any of the embodiments described herein, a thickness of the outermost encapsulating region (e.g., 800d) ranges from about 0.4 to about 1, or from about 0.4 to about 0.8, or from about 0.4 to about 0.7, or from about 0.5 to about 0.8, or from about 0.5 to about 0.7 mm, including any intermediate values and subranges therebetween. In exemplary embodiments, it is about 0.6 mm.

[0225] According to some embodiments of any of the embodiments described herein, a thickness of the inner encapsulating region (e.g., 800b), if present, ranges from about 0.4 to about 1 mm, orfrom about 0.5 mm to about 1 mm, including any intermediate values and subranges therebetween. In exemplary embodiments, it is about 0.7 mm. In exemplary embodiments, it is about 1 mm.

[0226] According to some embodiments of any of the embodiments described herein, a thickness of the intermediate encapsulating region (e.g., 800c), if present, ranges from about 0.3 to about 0.6, or from about 0.3 to about 0.5 mm, including any intermediate values and subranges therebetween. In exemplary embodiments, it is about 0.4 mm.

[0227] According to some embodiments of any of the embodiments described herein, a thickness of the outermost encapsulating region (e.g., 800d) ranges from 0.5 to 0.7 mm, and is preferably 0.6 mm;

[0228] a thickness of the inner encapsulating region (e.g., 800b) ranges from 0.5 mm to 1 mm, and is preferably 0.7 mm; and

[0229] a thickness of the intermediate encapsulating region (e.g., 800c) ranges from 0.3 to 0.5 mm, and is preferably 0.4 mm.

[0230] According to some embodiments of any of the embodiments described herein, a thickness of the intermediate encapsulating region (e.g., 800c) is at least 50 %, for example, from 50 to 100 %, or from 50 to 80 %, or from 50 to 70 %, including any intermediate values and subranges therebetween, of the thickness of the outermost encapsulating region (e.g., 800d). Alternatively, or in addition, a ratio between a thickness of the intermediate encapsulating region (e.g., 800c) and a thickness of the outermost encapsulating region (e.g., 800d) is at least 1:1.5, and can be, for example, 1:1.5 or 1:1.6, or 1:1.7, or 1:1.8, or 1:1.0 or 1:2, or 1:2.5, or can range from about 1:1.5 to about 1:2.5, or from about 1:1.5 to about 1:2, including any intermediate values and subranges therebetween.

[0231] Herein, by “thickness” it is meant an average thickness of the encapsulating region.

[0232] According to some embodiments of any of these embodiments and any combination thereof, the core region (e.g., 800a) is formed of one modeling material formulation or from one combination of modeling material formulations, and the encapsulating region (e.g., 800d) is formed of another modeling material formulation or another combination of formulations, which is different from those forming the core region (e.g., 800a). If inner and / or intermediate encapsulating regions (e.g., 800b and optionally 800c) are formed, the composition (e.g., the modeling material formulation type or the combination of two or more modeling material formulations) of each region is different from the region it encapsulates and the region by which it is encapsulated.

[0233] According to exemplary embodiments, the dispensing is such that the core region (e.g., 800a) is formed of the second modeling material formulation or of a first combination of the firstand the second modeling material formulations, and the encapsulating region (e.g., outermost encapsulating region 800d) is formed of the first modeling material formulation or a second combination of the first and the second modeling material formulation, the second combination being different from the first combination.

[0234] When the object or object part is such that comprises also inner encapsulating region 800b and intermediate encapsulating region 800c, the inner encapsulating region is formed of the first formulation or the second combination of the first and the formulations, and the intermediate encapsulating region is formed of the second formulation or the first combination of the first and second formulations. Alternatively, the inner encapsulating region can be formed of a third formulation or a third combination of two or more formulations. Further alternatively, intermediate encapsulating region can be formed of a fourth formulation or a fourth combination of the first and second formulations.

[0235] According to some embodiments of any of these embodiments and any combination thereof, the first and second modeling material formulations, and optionally the third, fourth, and so forth formulations, if selected, which are used for forming the onion-like structure can be selected from any modeling material formulations that meet the biocompatibility requirements of denture structures, as described herein.

[0236] According to some embodiments of any of the embodiments described herein, the modeling material formulations or the combination thereof are selected so as to differ from one another by the mechanical properties of the hardened material formed thereby.

[0237] In some embodiments, the modeling material formulations or the combinations thereof differ from one another by an impact resistance, as defined herein, of the hardened material formed of each formulation or combination per se. In some of these embodiments, the impact resistance of one formulation or one combination that forms one region differs from an impact resistance of the other formulation or the other combination that form a region encapsulating or encapsulated by this region, by at least 2-folds, or at least 5-folds, or at least 10-folds, for example, by from 2-folds to 50-folds, or from 5-folds to 50-folds, or from 5-folds to 20-folds, or from 10-folds to 50-folds, or from 10-folds to 30-folds, or from 5-folds to 30-folds, or from 10-folds to 20-folds, including any intermediate values and subranges therebetween.

[0238] In some embodiments, the modeling material formulations or the combinations thereof differ from one another by the flexural modulus and / or the flexural strength, as defined herein, of the hardened material formed of each formulation or combination per se. In some of these embodiments, the flexural modulus and / or the flexural strength of one formulation or one combination that forms one region differs from flexural modulus and / or the flexural strength ofthe other formulation or the other combination that form a region encapsulating or encapsulated by this region, by at least 2-folds, or at least 5-folds, or at least 10-folds, for example, by from 2-folds to 50-folds, or from 5-folds to 50-folds, or from 5-folds to 20-folds, or from 10-folds to 50-folds, or from 10-folds to 30-folds, or from 5-folds to 30-folds, or from 10-folds to 20-folds, including any intermediate values and subranges therebetween.

[0239] In some embodiments, the modeling material formulations or the combinations thereof differ from one another by one or more, or two or more, or all of an impact resistance, the flexural modulus and / or the flexural strength, as defined herein, of the hardened material formed of each formulation or combination per se.

[0240] According to exemplary embodiments, the dispensing of the onion-like structure is of a first and a second modeling material formulations which are selected such that: the second formulation or the first combination, which form the core region (e.g., 800a) and optionally the intermediate encapsulating region (e.g., 800c), features, when hardened, impact resistance that is higher by at least 2-folds, or at least 5-folds, or at least 10-folds, as described herein, of an impact resistance of the first formulation or the second combination, which form that outermost encapsulating region (e.g., 800d) and optionally the inner encapsulating region (e.g., 800b).

[0241] According to exemplary embodiments, the dispensing of the onion-like structure is of a first and a second modeling material formulations which are selected such that: the second formulation or the first combination, which form the core region (e.g., 800a) and optionally the intermediate encapsulating region (e.g., 800c), features, when hardened, flexural modulus and / or flexural strength, that is higher by at least 2-folds, or at least 5-folds, or at least 10-folds, as described herein, of a flexural modulus and / or a flexural strength of the first formulation or the second combination, which form that outermost encapsulating region (e.g., 800d) and optionally the inner encapsulating region (e.g., 800b).

[0242] According to exemplary embodiments, the dispensing of the onion-like structure is of a first and a second modeling material formulations which are selected such that: the second formulation or the first combination, which form the core region (e.g., 800a) and optionally the intermediate encapsulating region (e.g., 800c), features, when hardened, impact resistance and flexural modulus that is higher by at least 2-folds, or at least 5-folds, or at least 10-folds, as described herein, of an impact resistance and a flexural strength of the first formulation or the second combination, which form that outermost encapsulating region (e.g., 800d) and optionally the inner encapsulating region (e.g., 800b).

[0243] When a combination of two or more modeling material formulations (e.g., of a first and a second modeling material formulations) is used to form a core region or one or more of theencapsulating regions, the combination is optionally and preferably embodied in a voxelated manner wherein some voxels that form the respective region are made of one of the modeling material formulations, other voxels are made of another one of the modeling material formulations, and so on. The voxelated combination can be according to any distribution by which voxels occupied by the first formulation are interlaced within voxels occupied by the second formulation, such as, but not limited to, a random distribution.

[0244] According to some embodiments of any of the embodiments described herein, a method as described herein is effected such that at least one of the first and second modeling material formulations as described herein is a Type B formulation as described herein in any of the respective embodiments and any combination thereof. According to some of these embodiments, at least another one of the first and second modeling material formulations is a Type B formulation as described herein in any of the respective embodiments and any combination thereof.

[0245] According to some embodiments of any of the embodiments described herein, the second formulation is a Type B formulation as described herein in any of the respective embodiments and any combination thereof and the first formulation is a Type A formulation as described herein in any of the respective embodiments and any combination thereof.

[0246] According to some embodiments, a method as described herein is effected such that for at least a few layers, the dispensing is of a Type A formulation as described herein and of a Type B formulation as described herein, so as to form a core region as described herein and at least one encapsulating regions as described herein, wherein each of the core region and the encapsulating region is formed of a Type A or Type B material formulation or a different combination of the Type A and Type B modeling material formulations.

[0247] According to some embodiments of any of the embodiments described herein, the core region (e.g., 800a) is formed of a Type B formulation as described herein in any of the respective embodiments and any combination thereof.

[0248] According to some embodiments of any of the embodiments described herein, the outermost encapsulating region (e.g., 800d) is formed of the Type A formulation as described herein in any of the respective embodiments and any combination thereof.

[0249] When further encapsulating regions are formed, as described herein in any of the respective embodiments for structure 800 for example, each of the core region and the inner encapsulating region, each of the inner encapsulating region and the intermediate encapsulating region, if present, or the outermost (coating) encapsulating region, and each of the intermediate encapsulating region, if present, and the outermost (coating) encapsulating region is formed of a Type A or Type B formulation, or of a different combination of the Type A and Type B formulations.According to exemplary embodiments, the core region (e.g., 800a) is formed of a Type B formulation, the inner encapsulating region (e.g., 800b) is formed of a Type A formulation or a combination of one or more Type A formulations, the intermediate encapsulating region (e.g., 800c) is formed of a Type B formulation and the outermost encapsulating region (e.g., 800d) is formed of a Type A formulation or a combination of one or more Type A formulations.

[0250] According to exemplary embodiments, the type A formulation described herein is optionally and preferably, but not necessarily, transparent or partially transparent. The type A formulation described herein is particularly useful for the fabrication of an outermost region of the object assembly. In some embodiments of the present invention the type A formulation described herein is used for the fabrication of an outermost region of an object assembly which is a monolithic structure comprising a denture base having a shape of a gingiva and artificial teeth.

[0251] According to exemplary embodiments, the type B formulation described herein is suitable for use as an opaque or partially opaque formulation, according to some embodiments of the present invention. The type B formulation described herein is optionally and preferably more opaque and less transparent than the type A formulation. The type B formulation described herein is particularly useful for the fabrication of one or more of the inner regions of the object assembly. In some embodiments of the present invention the type B formulation described herein is used for the fabrication of one or more of the inner regions of an object assembly which is a monolithic structure comprising a denture base having a shape of a gingiva and artificial teeth. Preferably, but not necessarily, the type B formulation described herein is used for the fabrication of one or more of the inner regions of the denture base of the monolithic structure.

[0252] In the fabrication of sacrificial structures serving for supporting external surfaces of three-dimensional object during additive manufacturing (e.g., by means of system 10 or 110, described below), it is oftentimes desired to reinforce the support structure using reinforcing elements. In these cases, the sacrificial structure comprises a bulk, which is typically fabricated from a support material formulation or a digital material including a hardened support material and one or more hardened modeling material(s), and reinforcing elements that are typically made of a hardened modeling material or a digital material including two or more hardened modeling materials, and that are embedded in the bulk. Following the hardening of the fabricated layers of the object and the support structure, the support structure, including the bulk and the embedded reinforcing elements, is removed to reveal the outer surface of the object which is supported by the support structure. The removal can be by applying a jet of liquid (e.g., aqueous liquid, such as, but not limited to, water), and / or by peeling the support structure off the outer surface of the object, or by breaking the support structure, depending on the nature and type of materials, and particularly, butnot necessarily exclusively, the type of the support material formulation, used for fabricating the support structure.

[0253] In some cases, the removal is preceded or otherwise accompanied by one or more other treatments, e.g., immersing in a solvent as described herein. For example, a jet of a liquid can be applied to remove part of the support structure, and then the object and the unremoved portion of the support structure can be immersed in a solvent for a predetermined time period, and then the jet of a liquid can be applied to remove the remaining part of the support structure. Alternatively, the jet of a liquid can be applied only once after the object and the entire support structure have been immersed in the solvent for a predetermined time period. Other types of treatments, in combination with any of the aforementioned removal techniques, are also contemplated.

[0254] While reducing to practice embodiments of the present invention it was unexpectedly found that when the reinforcing elements are made of certain modeling materials, it is more difficult to remove the support structure (for example, the reinforcing elements cause the structure to be less washable), than when the reinforcing elements are made of other modeling materials. It was also unexpectedly found that reinforcing elements that are made of those modeling materials that make the removal easier reduce the quality of the surface beneath the support structure. The reduction is manifested by appearance of a color or hue artifact due to interaction between building materials at the interface of the object and the support structure (e.g., mixing prior to hardening, or sticking after hardening). This discovered phenomenon is referred to herein as "flaking" since a color or hue artifact typically appears in the form of flakes on the outer surface of the object. An image showing a representative example of the flaking phenomenon on the outer surface of a denture object after the removal of a support structure which included reinforcing elements made fabricated using of a Type B formulation as defined herein is shown in FIG. 9.

[0255] The Inventors further found that the flaking phenomenon is suppressed or non-existent when the reinforcing elements are made of those modeling materials that make the removal more difficult. Thus, the Inventors found that the problem of making the support structure easier to be removed conflicts with the problem of flaking. In a search for a solution to these conflicting problems, the Inventors devised a support structure that enjoys the property of being removable without substantial difficulty, and at the same time does not impart the flaking phenomenon on the surface of the object it supports.

[0256] The solution is based on discoveries made by the Inventors. A first discovery is that reinforcing elements which are made of hardened modeling materials that are relatively tougher tend to impart on the supported surface of the object a higher extent of flaking than reinforcing elements which are made of less tough hardened modeling materials. A second discovery is thatthe removal of the support structure is easier when the reinforcing elements are made of the hardened modeling materials that are relatively tougher, than when the reinforcing elements are made of the hardened modeling materials that are less tough. A material is considered to be relatively tougher than another material if the material is characterized by at least one of: higher elongation at break value, lower flexural modulus, and higher impact resistance, than the other material.

[0257] Reference is now made to FIG. 10A which is a schematic illustration of a three-dimensional assembly 500 according to some embodiments of the present invention. Three-dimensional assembly 500 is fabricated by an additive manufacturing process, for example, by means of system 10 or system 110 as further detailed herein. Assembly 500 comprises a hardened object 502 and a hardened sacrificial structure 504 supporting at least one surface 506 of hardened object 502. In is to be understood that FIG. 10A illustrates partial views of object 502 and sacrificial structure 504 wherein object 502 and sacrificial structure 504 can extend along any of their dimensions. Further, while FIG. 10A illustrates an embodiment in which surface 506 is a side wall of object 502, it is to be understood that hardened sacrificial structure 504 can support any of the external surfaces of object 502, such as, but not limited to, the bottommost surface, or an overhang surface, or an inclined surface thereof.

[0258] Sacrificial structure 504 comprises a bulk 508 embedded with reinforcing elements 510, 512. The collection of all of the reinforcing elements that are embedded in bulk 508 is referred to herein as the "grid" of sacrificial structure 504. For clarity of presentation, the side walls of bulk 508 are shown fully transparent. Preferably, reinforcing elements 512 are mechanically tougher than reinforcing elements 510.

[0259] In some embodiments of the present invention reinforcing elements 512 are characterized by higher elongation at break value than reinforcing elements 510. For example, the elongation at break value of reinforcing elements 512 can be five times higher, or ten times higher, or twenty times higher than the elongation at break value of reinforcing elements 510, when the elongation at break values of both types of elements are measured by the same technique.

[0260] A technique suitable to verify the relation between the elongation at break value of reinforcing elements 510 and 512 is one of the ASTM D-638 tests (e.g., the ASTM D-638-03 revision). Typical elongation at break values for reinforcing elements 510, as measured using the ASTM D-638-03 test, are less than 5 % or less than 4 % or less than 3 %. Typical elongation at break values for reinforcing elements 512, as measured using the ASTM D-638-03 test, are at least 100 % or at least 110 % or at least 120 % or at least 130 % or at least 140 %, e.g., from about 100 % to about 150 %.In some embodiments of the present invention the flexural modulus of elements 510 is higher (e.g., at least two times higher, or at least three times higher, or at least four times higher, or at least five times higher) than the flexural modulus of elements 512, when the flexural moduli of both types of elements are measured by the same technique.

[0261] A technique suitable to verify the relation between the flexural modulus of reinforcing elements 510 and 512 is one of the ASTM D-790 tests (e.g., the ASTM D-790-04 revision). Typical flexural moduli for reinforcing elements 510, as measured using the ASTM D-790-04 test, are at least 3000 MPa or at least 3500 MPa or at least 4000 MPa. Typical flexural moduli for reinforcing elements 510, as measured using the ASTM D-790-04 test, are at less than 500 MPa or less than 400 MPa or less than 300 MPa.

[0262] In some embodiments of the present invention the impact resistance of elements 512 is higher (e.g., at least five times higher, or at least ten times higher, or at least twenty times higher) than the impact resistance of elements 510, when the impact resistances of both types of elements are measured by the same technique.

[0263] A technique suitable to verify the relation between the impact resistance of reinforcing elements 510 and 512 is the ASTM D256-06 standard Izod impact testing. Typical impact resistance for reinforcing elements 510, as measured using the ASTM D256-06 standard Izod impact testing is from about 15 J / m to about 20 J / m, and typical impact resistance for reinforcing elements 512, as measured using the ASTM D256-06 standard Izod impact testing is from about 200 J / m to about 500 J / m.

[0264] In some embodiments of the present invention reinforcing elements 510 are made of a modeling material, in some embodiments of the present invention reinforcing elements 512 are made of a modeling material, and in some embodiments of the present invention both reinforcing elements 510 and 512 are made of modeling materials, where the modeling material of elements 510 is different from the modeling material of elements 512. Also contemplated, are embodiments in which at least one of the reinforcing elements is made of a combination of two or more modeling materials, such as, but not limited to, a digital material.

[0265] Whenever an element or an object or a structure is referred to herein as being “made of’ a material, it is meant that it is formed while using a respective (support or modeling) material formulation or a respective combination of (support and / or modeling) material formulations, and hence comprises or consists of the hardened material.

[0266] Reinforcing elements 510 and 512 can have any shape and size provided that each reinforcing element is smaller in size than the overall size of support structure 504, allowing the embedding of the reinforcing elements in the bulk. Reinforcing elements 510 and 512 are arrangedin a first region 514 and a second region 516 within bulk 508, wherein second region 516 is farther from surface 506 than first region 514. For clarity of presentation regions 514 and 516 are spaced apart in FIG. 10A, but embodiments in which regions 514 and 516 are immediately adjacent to each other are also contemplated.

[0267] The arrangement of the reinforcing elements is lateral along a plane perpendicular to the build direction z, and may in some embodiments of the present invention also be both lateral and vertical. In the schematic illustration of FIG. 10A, which is not to be considered as limiting, reinforcing elements 510 are embedded in region 514 and reinforcing elements 512 are embedded in region 516, but this need not necessarily be the case, since, in some embodiments of the invention some of reinforcing elements 512 are embedded in region 514, and in some embodiments of the invention some of reinforcing elements 510 are embedded in region 516. Preferably, the majority of reinforcing elements within region 516 are mechanically tougher than the majority of reinforcing elements within region 514. For example, the majority of reinforcing elements within region 516 can be elements 512 and the majority of reinforcing elements within region 514 can be elements 510. In some embodiments of the present invention all the reinforcing elements within region 516 are mechanically tougher than all the reinforcing elements within region 514.

[0268] In some embodiments of the present invention the majority of reinforcing elements within region 514 are made of a hardened Type A formulation, as defined herein, and in some embodiments of the present invention the majority of reinforcing elements within region 516 are made of a hardened Type B formulation, as defined herein.

[0269] In some embodiments of the present invention reinforcing elements 510 are made of a hardened Type A formulation, as defined herein, and in some embodiments of the present invention reinforcing elements 512 are made of a hardened Type B formulation, as defined herein.

[0270] Bulk 508 can be made of any building material that can be separated from surface 506 of object 502 without substantially changing the structure, shape, or color of surface 506. In some embodiments of the present invention bulk 508 is washable off surface 506 e.g., by a jet of water, in some embodiments of the present invention bulk 506 is peelable off surface 506, and in some embodiments of the present invention bulk 506 is breakable. For example, bulk 508 can be made of a support material. In some embodiments of the present invention bulk 508 is made of a hardened support material obtained using the newly designed support material formulation as described herein in any of the respective embodiments.

[0271] The densities of the reinforcing elements need not be uniform across bulk 508. Preferably, the density of the reinforcing elements is higher in first region 514 than in second region 516. The density is preferably an area density, measured at a horizontal plane perpendicular to the builddirection z of assembly 500. The lateral distance between adjacent reinforcing elements in region 514 (e.g., between adjacent reinforcing elements 510 in region 514) is preferably from about 0.1 mm to about 0.3 mm. The lateral distance between adjacent reinforcing elements in region 516 (e.g., between adjacent reinforcing elements 512 in region 516) is preferably from about 0.2 mm to about 0.6 mm. In experiments performed according to some embodiments of the present invention the lateral distance between adjacent reinforcing elements 510 in region 514 was about 0.17 mm, and the lateral distance between adjacent reinforcing elements 512 in region 516 was about 0.4 mm.

[0272] In some embodiments of the present invention there is no contact between the reinforcing elements and surface 506. A typical minimal distance between surface 506 and the reinforcing elements of region 514 (which is closer to surface 506 than region 516) is from about 0.1 mm to about 0.3 mm. For example, the minimal distance can be the same as the inner reinforcing element distance in region 514. In experiments performed according to some embodiments of the present invention the minimal distance between surface 506 and reinforcing elements 510 in region 514 was about 0.17 mm.

[0273] In some embodiments of the present invention the majority of the reinforcing elements within region 516 (e.g., elements 512) are larger than the majority of the reinforcing elements within region 514 (e.g., elements 510), preferably both laterally (along a dimension perpendicular to the build direction z) and vertically (along a dimension parallel to the build direction z). For example, the lateral dimensions of the majority of the reinforcing elements within region 516 can be from about 150% to about 250 % larger than the lateral dimensions of the majority of the reinforcing elements within region 514, and the vertical dimension of the majority of the reinforcing elements within region 516 can be from about 10% to about 20 % larger than the vertical dimension of the majority of the reinforcing elements within region 514.

[0274] In some embodiments of the present invention the reinforcing elements are elongated along the build direction z of assembly 500. For example, the majority of the reinforcing elements within region 514 can have a largest lateral diameter of from about 0.08 mm to about 0.15 mm and a vertical height extending along at least 50 % or at least 60 % or at least 70 % or at least 80 % or at least 90 %, e.g., the entire height, of sacrificial structure 504. Alternatively, the majority of the reinforcing elements within region 514 can have a largest lateral diameter of from about 0.08 mm to about 0.15 mm and a vertical height of from about 0.2 mm to about 0.5 mm. The majority of the reinforcing elements within region 516 can have the lateral diameter of from about 0.3 mm to about 0.5 mm and a vertical height of from about 1 mm to about 3 mm.The present embodiments contemplate any elongated shape for the reinforcing elements. Representative examples include, without limitation, a pillar, a helix, a cylinder, a cone, an ellipsoid, a prism, a pyramid, a capsule, a fusiform, a prolate spheroid, a cuboid, a tube and the like. In some embodiments of the present invention reinforcing elements 510 are shaped as pillars, and in some embodiments of the present invention reinforcing elements 512 are shaped as helices. The reinforcing elements can have any cross-sectional shape along a horizontal plane, including, without limitation, a round shape (e.g., circle, ellipse), and a polygonal shape (triangle, square, rectangle, pentagon, etc.). In some embodiments of the present invention the cross-section of reinforcing elements 510 along the horizontal plane is square. For example, the cross-section of reinforcing elements 510 can be the cross section of a single voxel dispensed by the dispensing head, e.g., a 0.09 mm x 0.09 mm square.

[0275] Some of the reinforcing elements can be shorter in length than the height of bulk 508 along building direction z. When the height of bulk 508 is larger than two or more times the length of a particular reinforcing elements along the build direction, the respective reinforcing elements are optionally and preferably distributed both laterally and vertically within bulk 508. FIG. 10B is a schematic illustration of a side view of assembly 500 in embodiments in which the reinforcing elements 512 are distributed also vertically within bulk 508, and the reinforcing elements 510 extend along at least 90% of the height of structure 504, and FIG. 10C is a schematic illustration of a side view of assembly 500 in embodiments in which both reinforcing elements 510 and 512 are distributed also vertically within bulk 508. The vertical distance (along the build direction z) between adjacent reinforcing elements in region 516 (e.g., between adjacent reinforcing elements 512 in region 516) is preferably from about 0.1 mm to about 0.3 mm. In experiments performed according to some embodiments of the present invention elements 510 extended along at least 90% of the height of structure 504 and the vertical distance between adjacent reinforcing elements 512 in region 516 was about 0.2 mm. When the reinforcing elements in region 514 are distributed also vertically within bulk 508, the vertical distance between adjacent reinforcing elements in region 514 (e.g., between adjacent reinforcing elements 510 in region 514) is preferably from about 0.08 mm to about 0.3 mm.

[0276] FIG. 11 is a flowchart diagram of a method suitable for additive manufacturing of a three-dimensional assembly in layers, according to various exemplary embodiments of the present invention. It is to be understood that, unless otherwise defined, the operations described hereinbelow can be executed either contemporaneously or sequentially in many combinations or orders of execution. Specifically, the ordering of the flowchart diagrams is not to be considered as limiting. For example, two or more operations, appearing in the following description or in theflowchart diagrams in a particular order, can be executed in a different order (e.g., a reverse order) or substantially contemporaneously. Additionally, several operations described below are optional and may not be executed.

[0277] The method can be executed by an AM system (e.g., system 110 or system 10) operated by a controller (e.g., controller 152 or 20). The method begins at 600 and proceeds to 601 at which a combined computer object dataset is obtained. The combined computer object dataset describes at least a three-dimensional assembly (e.g., assembly 500), and is a combination of computer object data describing a three-dimensional object (e.g., object 502) and computer object data describing a sacrificial structure (e.g., structure 504) which is to provide support for at least one surface of the object. The combined computer object dataset can be in any of the aforementioned formats. Preferably, the combined computer object dataset is received in the form of a plurality of slices, each defined over a plurality of voxels, respectively corresponding to a plurality of layers that are to be stacked along the build direction z, where the stack of layers defines the three-dimensional assembly. Alternatively, the method can receive the combined computer object dataset, wherein the plurality of slices is generated by the method by executing a slicing operation using computer software known as a slicer. Still alternatively, the method can receive the computer object data that describe the object separately from the computer object data that describe the sacrificial structure, wherein the combination of these data into a combined dataset is executed by the method using appropriate computer software.

[0278] The method continues to 602, 603, and 604 at which building material formulations are dispensed, for example, using arrays of nozzles 122, on a receiving surface, to form a layer of the three-dimensional assembly. The receiving surface can be the working surface of the AM system (e.g., tray 12 or 360) or it can be a previously formed layer of the assembly. At each of operations 602, 603 and 604 different building material formulations or combinations of building material formulations are dispensed at a different set of locations within the assembly's layer, according to the combined dataset. Operations 602, 603 and 604 can be executed contemporaneously by selectively operating different nozzles of different arrays to simultaneously dispense different building material formulations at respective locations within the assembly's layer to be formed.

[0279] Operation 602 is executed based on a portion of the combined dataset that corresponds to the computer object data that describe the object, and operations 603 and 604 are executed based on the computer object data that describe the sacrificial structure. Specifically, at 602 building material formulation(s) are dispensed to form a layer of the object within the layer of the assembly, at 603 a building material formulation is dispensed to form a layer of a bulk (e.g., bulk 508) within the layer of the assembly, and at 604 building material formulations are dispensed to form a layerof reinforcing elements (e.g., reinforcing elements 510 and 512 ) within the layer of the assembly, where the locations at which the building material formulations are dispensed at 604 are selected to ensure the imbedding of the reinforcing elements within the bulk.

[0280] Typically, the building material formulation(s) that are dispensed at 602 are modeling material formulations, but may optionally also comprise one or more support material formulations. Typically, the building material formulation that is dispensed at 603 is a support material formulation, but the present embodiments also contemplate dispensing at 603 one or more modeling material formulations in addition to the support material formulation. Typically, the building material formulations that are dispensed at 604 are modeling material formulations, but may optionally also comprise one or more support material formulations (e.g., as described herein).

[0281] According to some embodiments, the building material formulation(s) that are dispensed at 602 are dispensed such that in at least a portion of an outer layer of the object, a support material formulation is dispensed on the modeling material formulation(s), so as to provide, upon hardening, a hardened mixture (mixed layer) of a hardened modeling material formulation and a hardened support material formulation (e.g., as described herein).

[0282] According to some of these embodiments, a thickness of said mixture ranges from 100 to 1000 micrometers or from 100 to 500, or from 200 to 500, micrometers.

[0283] Operation 604 is executed to ensure that the reinforcing elements are arranged in a first region (e.g., region 514) and a second region (e.g., region 516) within the bulk, wherein the second region is farther from the layer of the object than the first region. The building material formulations that are dispensed at 604 are optionally and preferably selected such that once they are hardened, at least a majority of the reinforcing elements within the second region are mechanically tougher than at least a majority of the reinforcing elements within the first region. In some embodiments of the present invention the building material formulations that are dispensed at 604 comprise a Type A formulation and a Type B formulation as described herein, wherein the Type A formulation is dispensed to form reinforcing elements 510 and the Type B formulation is dispensed to form reinforcing elements 512.

[0284] The method proceeds to 605 at which the building material formulations dispensed at 602, 603, 604 are hardened to form hardened building materials constituting a hardened layer of the three-dimensional assembly. A representative example of a hardened layer 620 of a three-dimensional assembly according to some embodiments of the present invention is illustrated in FIG. 12. As shown, hardened layer 620 comprises a hardened layer of object 502, and a hardened layer of sacrificial structure 504 which comprises a hardened layer of bulk 508 embedded with hardened layers of reinforcing elements 510, 512 arranged in a first region 514 and a second region516 within the hardened layer of bulk 508, where region 516 is farther from the layer of object 502 than region 514. While FIG. 12 illustrates the layer of sacrificial structure 504 at one side of the layer of object 502, this need not necessarily be the case, since, for some applications, it may be desired to dispense the material formulations in a manner that the layer of sacrificial structure 504 partially or completely surrounds the layer of object 502. A representative example of such a configuration is described in the Examples section below (see Example 3, FIG. 13A). Operation 605 can be executed by a solidifying device (e.g., solidifying device 324) and may include applying curing radiation to the dispensed material formulations. The type of radiation (e.g., electromagnetic, electron beam, etc.) is selected based on the building material formulations being used. For example, for UV polymerizable materials an ultraviolet electromagnetic radiation is preferred.

[0285] From 605 the method optionally and preferably loops back to one or more of 602, 602 and 603, to form an additional layer of the object. The loop can continue until all the layers of the assembly are formed. The method ends at 606.

[0286] Support Material formulation:

[0287] The present inventors have surprisingly uncovered that objects, or parts thereof, which feature improved toughness, particularly improved fracture toughness and improved durability is a drop test as described herein, can be obtained when manufactured in a matte mode as described herein (in which a mixed layer made of a modeling material and a support material is formed). During laborious studies, the present inventors have designed and successfully practiced support material formulations which provide such an improved performance. While these newly designed support material formulations can be employed in additive manufacturing of objects manufactured in a matte mode, for improving the toughness of the obtained objects, it is to be noted that such support material formulations can also be utilized in additive manufacturing of objects manufactured in a glossy mode, as described herein.

[0288] The fracture toughness of a sample made of a hardened material can be expressed in terms of its fracture mechanics parameters, including, without limitation, the Total Fracture Work, Wf, and the Maximum Strength intensity factor, Kmax, as defined herein.

[0289] A support material formulation of the present embodiments is a curable formulation, which hardens typically by undergoing polymerization and / or crosslinking, typically when exposed to a curing condition as described herein (e.g., radiation). The support material formulation is, in some embodiments, a photocurable formulation, for example, a UV-curable formulation, which hardens when exposed to UV irradiation.According to some embodiments, a support material formulation as described herein, is a curable formulation, which comprises one or more curable materials as described herein, and which is usable as a support material formulation in additive manufacturing of three-dimensional objects. According to some embodiments, the curable formulation is usable in any of the methods described herein in any of the respective embodiments and any combination thereof.

[0290] According to an aspect of some embodiments of the present invention there is provided a curable formulation, which is usable in additive manufacturing of three-dimensional object, preferably as a support material formulation, and more preferably, as a support material formulation that is dispensed on at least a portion of an outer layer of the object and forms a mixed layer, as described herein.

[0291] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation comprises at least one non-curable material (Component L) and a combination of one or more mono-functional curable material(s) and one or more multi-functional curable material(s).

[0292] According to some embodiments of any of the embodiments described herein, the non-curable material(s) Component L comprise(s) at least one material, which is polymeric or at least oligomeric material, that features, water solubility lower than 200, or lower than 100, or lower than 50, or lower than 10, grams / liter, for example, water solubility in a range of from 1 to 100, or from 1 to 80, or from 1 to 60, or from 1 to 50, or from 1 to 40, or from 1 to 30 or from 1 to 20 or from 1 to 10, or from 5 to 50, or from 5 to 40, or from 5 to 30 or from 5 to 20, or from 5 to 15, or from 5 to 10, grams / liter, including any intermediate values and subranges therebetween. Herein throughout, water solubility values refer to water solubility at room temperature, that is, at 15-25, or 20-25, °C, unless otherwise indicated.

[0293] According to some embodiments of any of the embodiments described herein, the non-curable material(s) Component L comprise(s) at least one material, which is polymeric or at least oligomeric material, and which is characterized by low water absorption at room temperature, that is at 15-25, or 20-25, °C, unless otherwise indicated, for example, water absorption lower than 50 %, preferably lower than 20 %, or lower than 10 %, or lower than 5 %, from example, of from 0.1 to 10, or from 0.1 to 5, or from 0.1 to 3, or from 0.5 to 5, or from 0.5, to 3, or from 1 to 3, %, including any intermediate values and subranges therebetween.

[0294] According to some embodiments of any of the embodiments described herein, the non-curable material(s) Component L comprise(s) at least one material, which is polymeric or at least oligomeric material, that features water solubility lower than 200, or lower than 100, or lower than 50, or lower than 10, grams / liter, for example, water solubility in a range of from 1 to 100, or from1 to 80, or from 1 to 60, or from 1 to 50, or from 1 to 40, or from 1 to 30 or from 1 to 20 or from 1 to 10, or from 5 to 50, or from 5 to 40, or from 5 to 30 or from 5 to 20, or from 5 to 15, or from 5 to 10, grams / liter, including any intermediate values and subranges therebetween, at room temperature, and features water absorption at room temperature, lower than 50 %, preferably lower than 20 %, or lower than 10 %, or lower than 5 %, for example, of from 0.1 to 10, or from 0.1 to 5, or from 0.1 to 3, or from 0.5 to 5, or from 0.5, to 3, or from 1 to 3, %, including any intermediate values and subranges therebetween.

[0295] According to some embodiments of any of the embodiments described herein, the non-curable material that features relatively low water- solubility (lower than 200 grams / liter as described herein) and / or low water absorption, as described herein, is also referred to herein as Component L3 or Component L4.

[0296] According to some embodiments of any of the embodiments described herein, the non-curable material Component L3 and / or Component L4, features low Tg, for example, Tg lower than 20, or lower than 0, or lower than -20, °C, for example, of from -100 to 0, or from -100 to -20, including any intermediate values and subranges therebetween.

[0297] Exemplary non-curable polymeric or oligomeric materials that feature water solubility and / or water absorption as described herein (Component L3 and / or L4) include, without limitation, polyTHF and other poly ethers which feature repeating backbone units of 3, 4, 5 or more carbon atoms, and polyesters.

[0298] Exemplary polyethers usable as Component L3 and / or L4 include, without limitation, polyTHF, poly(propylene glycol), poly(butylene glycol), poly(hexylene glycol) and Polytetramethylene Ether Glycol (PTMEG), particularly those having molecular weight higher than 200, or higher than 300, or higher than 400 grams / mol.

[0299] Exemplary polyesters usable as Component L3 and / or L4 include, without limitation, polyethylene terephthalate (PET), polybutylene terephthalate, poly trimethylene terephthalate, polycyclohexane dimethylene terephthalate, poly(lactic acid), and poly(caprolactones).

[0300] Component L3 and / or L4 can alternatively be or comprise a polycarbonate, for example, an aliphatic polycarbonate.

[0301] Herein throughout, a material that is composed of repeating units that form its backbone chain is referred to as “oligomeric” when it comprises up to 4 repeating backbone units, and as “polymeric” when it comprises 5 or more repeating backbone units. Alternatively, a material that is composed of repeating units that form its backbone chain and has an average molecular weight lower than 500 grams / mol is referred to herein as “oligomeric”, whereby such a material that has an average molecular weight higher than 500 grams / mol is referred to herein as “polymeric”. Forsimplicity, unless specifically indicated, all of the materials that are composed of repeating backbone units are referred to herein as polymeric materials.

[0302] The term “polymeric” also encompasses co-polymers and block-copolymers, which comprise two or more types of repeating backbone units.

[0303] It is to be noted that for any of the polymeric described herein, the water solubility and / or water absorption may depend on factors such as the average molecular weight, the crystallinity, etc., and that accordingly, embodiments of the present invention are intended to encompass those materials that feature such factors that result in the indicated water solubility and / or water absorption.

[0304] According to some embodiments of any of the embodiments described herein, Component L3 and / or L4 is or comprises a polyester.

[0305] According to some embodiments of any of the embodiments described herein, Component L3 and / or L4 is or comprises a poly(caprolactones) (PCL).

[0306] According to some embodiments of any of the embodiments described herein, the polymeric material that features low water solubility and / or low water absorption as described herein (Component L3 and / or L4), can have an average molecular weight (Mn) in a range of from 100 to 10,000, or from 100 to 8,000, or from 100 to 6,000, or from 100 to 5,000, or from 100 to 4,000, grams / mol, including any intermediate values and subranges therebetween.

[0307] According to some embodiments of any of the embodiments described herein, the polymeric material that features low water solubility and / or low water absorption as described herein, has an average molecular weight (Mn) lower than 1,000 or lower than 500 grams / mol, for example, in a range of from 200 to 1,000, or from 200 to 800, or from 200 to 600, or from 200 to 500, grams / mol, including any intermediate values and subranges therebetween. Such a material is also referred to herein as Component L3.

[0308] A polymeric material that features low water solubility and / or low water absorption as described herein, and has an average molecular weight (Mn) higher than 500, or higher than 1,000 grams / mol, is also referred to herein as Component L4.

[0309] According to some embodiments of any of the embodiments described herein, the non-curable polymeric material (Component L) comprises one or more non-curable polymeric materials that feature low water solubility and / or low water absorption as described herein, and have an average molecular weight (Mn) lower than 1,000 or lower than 500 grams / mol, for example, in a range of from 200 to 1,000, or from 200 to 800, or from 200 to 600, or from 200 to 500, grams / mol, including any intermediate values and subranges therebetween.According to some embodiments of any of the embodiments described herein, the non-curable polymeric material (Component L) comprises one or more of Component L3, as described herein.

[0310] According to some embodiments of any of the embodiments described herein, the non-curable polymeric material (Component L) comprises one or more polyester(s) that feature low water solubility and low water absorption as described herein, and have an average molecular weight (MW) lower than 1,000 or lower than 500 grams / mol (Component L3).

[0311] According to some embodiments of any of the embodiments described herein, the non-curable polymeric material (Component L) comprises one or more polycaprolactones(s) that feature low water solubility and low water absorption as described herein, and have an average molecular weight (MW) lower than 1,000 or lower than 500 grams / mol (Component L3).

[0312] According to some embodiments of any of the embodiments described herein, the non-curable material (Component L) further comprises one or more non-curable materials other than the Component L3 (and optionally Component L4).

[0313] According to some of these embodiments, the additional non-curable material comprises one or more polymeric or non-polymeric materials that are generally characterized as water-soluble or water-miscible, and / or as featuring higher water absorption. According to some of these embodiments, the additional non-curable material is or comprises a polymeric material featuring water solubility higher than 100, or higher than 200, or higher than 300, grams / liter, or even higher and / or water absorption higher than 20, or higher than 50, or higher than 80 %, and even of about 100, %, which is also referred to herein as Component L2.

[0314] Exemplary such materials include polyols, for example, polyether polyols, such as, but not limited to, poly(alkylene glycol)s featuring a short alkylene chain or low molecular weight (Mn), and other polyols such as, for example, polyol 3165. An exemplary Component L2 is poly(alkylene glycol) featuring average molecular weight (Mn) lower than 1,000 grams / mol.

[0315] According to some of these embodiments, the additional non-curable material is or comprises a non-polymeric polyol (e.g., diol) (Component LI). As exemplary component LI is propanediol. Other diols are also contemplated, as long as featuring high water solubility. According to some of these embodiments, the additional non-curable material is or comprises propylene carbonate.

[0316] According to some embodiments of any of the embodiments described herein, a total amount of the non-curable material(s) (Component L, including LI, L2, L3 and / or L4) is at least 40 % by weight of the total weight of the formulation.According to some embodiments of any of the embodiments described herein, a total amount of the non-curable material(s) (Component L, including LI, L2, L3 and / or L4) ranges from 20 to 60, or from 30 to 60, or from 40 to 60, or from 40 to 50, or from 45 to 55, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0317] According to some embodiments of any of the embodiments described herein, a total amount of Component L3 as described herein in any of the respective embodiments is at least 40 % by weight of the total weight of the formulation.

[0318] According to some embodiments of any of the embodiments described herein, a total amount of Component L3 as described herein in any of the respective embodiments ranges from 20 to 60, or from 30 to 60, or from 40 to 60, or from 40 to 50, or from 45 to 55, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0319] According to some embodiments of any of the embodiments described herein, the formulation further comprises, along with the non-curable material(s) (Component L, e.g., Component L3), one or more mono-functional (meth)acrylate featuring low Tg (Tg lower than 0, or lower than -20 °C). According to the present embodiments, this non-functional (meth)acrylate is selected as miscible in Component L3 (and / or in Component L4, if present), and is also referred to herein as Component M.

[0320] By “miscible” it is meant that Component M is at least partially dissolvable or dispersible in Component L3, that is, at least 50 % of the molecules of Component M move into Component L3 (and / or Component L4, if present) upon mixing at room temperature, e.g., when mixed with Component L3 in equal volumes or weights, at room temperature. By “miscible” it is also meant that a hardened material formed of Component M is at least partially dissolvable or dispersible in Component L3, that is, at least 50 % of the molecules of a hardened Component M move into Component L3 (and / or Component L4, if present) upon mixing at room temperature, e.g., when mixed with Component L3 in equal volumes or weights, at room temperature.

[0321] According to some embodiments, Component M is miscible, as defined herein, in Component L3, and / or a hardened material formed of Component M is miscible in Component L3.

[0322] According to some embodiments, Component M is miscible, as defined herein, in Component K, if present in the formulation, and / or a hardened material formed of Component M is miscible with a hardened Component K, if present in the formulation.

[0323] According to some embodiments, Component M is miscible, as defined herein, in Component L3 and Component K, if present in the formulation, and / or a hardened material formed of Component M is miscible with Component L3 and with a hardened Component K, if present in the formulation.According to some embodiments of any of the embodiments described herein, Component M comprises a curable group (a (meth) acrylate group) and an oligomeric or polymeric chain that renders it miscible with the non-curable polymeric material Component L3 (and / or Component L4, if present). According to some embodiments, the oligomeric or polymeric chain in Component M is miscible in Component L3, as described herein, that is, is derived from a material that is miscible with Component L3. According to some embodiments, such a material features water solubility and / or water absorption similar to that of Component L3. According to some embodiments, such a material features molecular weight similar to that of Component L3. According to some embodiments, such a material features water solubility and / or water absorption, and molecular weight, similar to that of Component L3. By “similar” it is meant ± 20 %.

[0324] According to some embodiments of any of the embodiments described herein, Component M and the non-curable material (e.g., Component L3 and / or Component L4) are selected chemically compatible with one another, such that, for example, Component M comprises an oligomeric or polymeric chain which is similar in its chemical composition to Component L3. For example, Component M comprises an oligomeric or polymeric chain that is derived from a material that has the same type of backbone units as does Component L3, or is otherwise structurally similar to Component L3. For example, if Component L3 is a poly ether as described in the context of the respective embodiments, Component M comprises an oligomeric or polymeric chain which is of a similar polyether (e.g., polybutadiene glycol). If Component L3 is a polyester as described in the context of the respective embodiments, Component M comprises an oligomeric or polymeric chain which is of a similar polyester (e.g., polycaprolactone). The oligomeric or polymeric chain of Component M can be the same as Component L3, or can differ, for example, by molecular weight According to some embodiments of any of the embodiments described herein, Component M has a molecular weight lower than 1,000, or lower than 600 or lower than 500 grams / mol, for example, in a range of from 100 to 1,000, or from 200 to 1,000, or from 300 to 1,000 or from 400 to 1,000, or from 100 to 800, or from 200 to 800, or from 300 to 800, or from 400 to 800, or from 100 to 600, or from 200 to 600, or from 300 to 600, or from 400 to 600, or from 100 to 500, or from 200 to 500, or from 300 to 500, or from 400 to 500, or from 200 to 400, or from 300 to 400, grams / mol, including any intermediate values and subranges therebetween.

[0325] According to exemplary embodiments, Component M comprises an oligomeric or polymeric polyester (e.g., polycaprolactone) chain and the non-curable polymeric material Component L is or comprises a polyester (e.g., polycaprolactone) as Component L3.

[0326] Accordingly, Component M can be a polyether, a polyester, or a polycarbonate, as these are described in the context of Component L3 and / or L4. According to some embodiments,Component M is a polycaprolactone (meth)acrylate, and in some embodiments, it is a polycaprolactone acrylate.

[0327] According to some embodiments of any of the embodiments described herein, an amount of Component M ranges from 5 to 15, or from 7 to 15, or from 8 to 15, preferably from 9 to 15, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0328] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation further comprises one or more multi-functional (meth)acrylate(s) featuring at least 10 ethoxylated groups and / or low Tg. Such a material is also referred to herein as Component D2.

[0329] According to some embodiments, Component D2 features, when hardened, Tg lower than 50, or lower than 20, preferably lower than 0, °C, for example, Tg of from -100 to 50, or from -100 to 0, or from -100 to -20, or from -20 to 0, °C, including any intermediate values and subranges therebetween and / or comprises at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10 to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties.

[0330] According to some embodiments of any of the embodiments described herein, Component D2 is a multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring, when hardened, Tg lower than 50 or lower than 0 °C, as described herein, and comprises at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10 to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties According to some embodiments of any of the embodiments described herein, Component D2 is a di-functional ethoxylated aromatic (meth) acrylate featuring, when hardened, Tg lower than 50 or lower than 0 °C, as described herein, and comprises at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10 to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties

[0331] According to some embodiments of any of the embodiments described herein, Component D2 is a multi-functional (e.g., di-functional) ethoxylated aromatic methacrylate featuring, when hardened, Tg lower than 50 or lower than 0 °C, as described herein, and comprises at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties According to some embodiments of any of the embodiments described herein, Component D2 is a di-functional ethoxylated aromatic methacrylate featuring, when hardened, Tg lower than 50 or lower than 0 °C, as described herein, and comprises at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10 to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties.

[0332] According to some embodiments of any of the embodiments described herein, Component D2 has a molecular weight of at least 1,000 grams / mol, for example, of from 1,000 to 5,000 or from 1,000 to 3,000, or from 1,000 to 2,000, grams / mol, including any intermediate values and subranges therebetween.

[0333] According to some embodiments of any of the embodiments described herein, Component D2 comprises a multi-functional ethoxylated aromatic methacrylate featuring at least 10 ethoxylated groups, features, when hardened, Tg lower than 0 °C, and has a molecular weight of at least 1,000 grams / mol, as described herein.

[0334] An exemplary Component D2 is, without limitation, such as marketed under the tradename SR9036A, yet, any other materials are contemplated.

[0335] According to some embodiments of any of the embodiments described herein, an amount of Component D2 ranges from 5 to 15, or from 10 to 15, or from 10 to 12, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0336] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation further comprises one or more additional mono-functional (meth)acrylate materials, which collectively referred to herein as Component E. These materials are typically selected so as to balance properties of the formulation, such as viscosity, Tg of the hardened material, hydrophobic / hydrophilic balance and / or reactivity.

[0337] According to some embodiments of any of the embodiments described herein, Component E comprises one or more mono-functional (meth) acrylate materials.

[0338] According to some embodiments of any of the embodiments described herein, Component E comprises two or more mono-functional (meth) acrylate materials.

[0339] According to some embodiments of any of the embodiments described herein, Component E comprises two or more mono-functional (meth)acrylate materials, and at least one, or each, of these materials is a hydrophilic and / or an amphiphilic material.As used herein throughout, the term “hydrophilic” describes a physical property of a material or a portion of a material (e.g., a chemical group in a compound) which accounts for transient formation of bond(s) with water molecules, typically through hydrogen bonding.

[0340] Hydrophilic materials dissolve more readily in water than in oil or other hydrophobic solvents. Hydrophilic materials can be determined, for example, as having LogP lower than 0.5, when LogP is determined in octanol and water phases at room temperature.

[0341] Hydrophilic materials can alternatively, or in addition, be determined as featuring a lipophilicity / hydrophilicity balance (HLB), according to the Davies method, of at least 10, or of at least 12.

[0342] As used herein throughout, the term “amphiphilic” describes a property of a material that combines both hydrophilicity, as described herein for hydrophilic materials, and hydrophobicity or lipophilicity, as defined herein for hydrophobic materials.

[0343] Amphiphilic materials typically comprise both hydrophilic groups as defined herein and hydrophobic groups, as defined herein, and are substantially soluble in both water and a water-immiscible solvent (oil).

[0344] Amphiphilic materials can be determined by, for example, as having LogP of 0.8 to 1.2, or of about 1, when LogP is determined in octanol and water phases at room temperature.

[0345] Amphiphilic materials can alternatively, or in addition, be determined as featuring a lipophilicity / hydrophilicity balance (HLB), according to the Davies method, of 3 to 12, or 3 to 9.

[0346] As used herein throughout, the term “hydrophobic” describes a physical property of a material or a portion of a material (e.g., a chemical group in a compound) which does not form bond(s) with water molecules. Hydrophobic materials dissolve more readily in oil than in water. Hydrophobic materials can be determined, for example, as having LogP higher than 1, preferably higher than 2, when LogP is determined in octanol and water phases.

[0347] A hydrophilic material or portion of a material (e.g., a chemical group in a compound) is one that is typically charge-polarized and capable of hydrogen bonding.

[0348] Amphiphilic materials typically comprise one or more hydrophilic groups (e.g., a charge-polarized group), in addition to hydrophobic groups.

[0349] Hydrophilic materials or groups, and amphiphilic materials, typically include one or more electron-donating heteroatoms which form strong hydrogen bonds with water molecules. Such heteroatoms include, but are not limited to, oxygen and nitrogen. Preferably, a ratio of the number of carbon atoms to a number of heteroatoms in hydrophilic materials or groups is 10:1 or lower, and can be, for example, 8:1, more preferably 7:1, 6:1, 5:1 or 4:1, or lower. It is to be noted that hydrophilicity and amphiphilicity of materials and groups may result also from a ratio betweenhydrophobic and hydrophilic moieties in the material or chemical group, and does not depend solely on the above-indicated ratio.

[0350] A hydrophilic or amphiphilic material can have one or more hydrophilic groups or moieties. Hydrophilic groups are typically polar groups, comprising one or more electron-donating heteroatoms such as oxygen and nitrogen.

[0351] Exemplary hydrophilic groups include, but are not limited to, an electron-donating heteroatom, a carboxylate, a thiocarboxylate, oxo (=0), a linear amide, hydroxy, a (Cl-4)alkoxy, an (Cl-4)alcohol, a heteroalicyclic (e.g., having a ratio of carbon atoms to heteroatoms as defined herein), a cyclic carboxylate such as lactone, a cyclic amide such as lactam, a carbamate, a thiocarbamate, a cyanurate, an isocyanurate, a thiocyanurate, urea, thiourea, an alkylene glycol (e.g., ethylene glycol or propylene glycol), and a hydrophilic polymeric or oligomeric moiety, as these terms are defined hereinunder, and any combinations thereof (e.g., a hydrophilic group that comprises two or more of the indicated hydrophilic groups).

[0352] In some embodiments, the hydrophilic group is, or comprises, an electron donating heteroatom, a carboxylate, a heteroalicyclic, an alkylene glycol and / or a hydrophilic oligomeric moiety.

[0353] An amphiphilic moiety or group typically comprises one or more hydrophilic groups as described herein and one or more hydrophobic groups, or, can a heteroatom-containing group or moiety in which the ratio of number of carbon atoms to the number of heteroatoms accounts for amphiphilicity.

[0354] A hydrophilic or amphiphilic mono-functional curable material according to some embodiments of the present invention can be a hydrophilic acrylate represented by Formula Al:

[0355]

[0356] Formula Al

[0357] wherein Ri and R2 are as defined herein and at least one of Ri and R2 is and / or comprises a hydrophilic or amphiphilic moiety or group, as defined herein.

[0358] In some embodiments of any of these embodiments, the carboxylate group, -C(=O)-ORa, comprises Ra which is a hydrophilic or amphiphilic moiety or group, as defined herein. Exemplary Ra groups in the context of these embodiments include, but are not limited to, heteroalicyclic groups (having a ratio of 10:1 or 8:1 or 6:1 or 5:1 or lower of carbon atoms to electron-donatingheteroatoms, such as morpholine, tetrahydrofurane, oxalidine, and the likes), hydroxyl, C(l-4)alkoxy, thiol, alkylene glycol or a hydrophilic or amphiphilic polymeric or oligomeric moiety, as described herein.

[0359] Exemplary hydrophilic or amphiphilic oligomeric mono-functional curable materials include, but are not limited to, a mono-(meth)acrylated urethane oligomer derivative of polyethylene glycol, a mono-(meth)acrylated polyol oligomer, a mono-(meth)acrylated oligomer having hydrophilic substituents, a mono-(meth)acrylated polyethylene glycol (e.g., methoxypolyethylene glycol), and a mono urethane acrylate.

[0360] According to some embodiments of any of the embodiments described herein, Component E comprises one or more, preferably two or more, of Components El, E2 and E3, as these are described herein.

[0361] According to some embodiments of any of the embodiments described herein, Component El is a hydrophilic or amphiphilic mono-functional (meth)acrylate, preferably a hydrophilic or amphiphilic mono-functional methacrylate.

[0362] According to some embodiments of any of the embodiments described herein, Component E2 is a mono-functional acrylate, and in some embodiments, it is a mono-functional acrylate that has an alicyclic group as Ra in Formula Al. According to some embodiments, Component E2 features, when hardened, Tg lower than 100, or lower than 80, or lower than 50, °C, for example, in a range of from 0 to 80, or from 20 to 80, or from 0 to 50, °C, including any intermediate values and subranges therebetween.

[0363] Exemplary materials that are usable as Component El include, without limitation, methacrylates featuring hydroxyalkyl groups, such as, for example, marketed under the tradename BISOMEROHPMA.

[0364] Exemplary materials that are usable as Component E2 include, without limitation, acrylates featuring mono-cyclic or bi-cyclic hydrocarbon groups (cycloalkyl), such as, for example, marketed under the tradename Genomer 1120, SR-789 and SR-420.

[0365] Component E3 is or comprises a mono-functional acrylate that is hydrophilic or amphiphilic, and is preferably water-soluble as described herein, which can be aliphatic or alicyclic. In exemplary embodiments, Component E3 is a hydrophilic heteroalicyclic acrylate. According to some embodiments, Component E3 features, when hardened, Tg higher than 80, or higher than 100, °C, for example, in a range of from 50 to 150, or from 80 to 150, or from 100 to 150, °C, or even higher, including any intermediate values and subranges therebetween.

[0366] An exemplary hydrophilic monomeric mono-functional acrylate is acryloyl morpholine (ACMO).According to some embodiments of any of the embodiments described herein, each of the mono-functional materials (Components El, E2 and E3) has an average molecular weight lower than 1,000 grams / mol or lower than 500 grams / mol, for example, of from 100 to 500 grams / mol, or from 100 to 400, or from 100 to 300, grams / mol, including any intermediate values and subranges therebetween.

[0367] According to some embodiments of any of the embodiments described herein, Component E is included in the formulation, inter alia, for balancing properties such as reactivity and / or viscosity, and Components El, E2 and / or E3, and a ratio thereof, are selected accordingly.

[0368] According to some embodiments of any of the embodiments described herein, at least Components E2 and E3 are included in a formulation as described herein.

[0369] According to some embodiments of any of the embodiments described herein, Component E comprises at least one hydrophilic or amphiphilic (meth)acrylate, preferably at least one hydrophilic or amphiphilic acrylate (Component E3) that features Tg higher than 80, or higher than 100 °C.

[0370] According to some embodiments of any of the embodiments described herein, Component E comprises at least one alicyclic, optionally hydrophobic, (meth)acrylate, preferably at least one alicyclic, optionally hydrophobic acrylate (Component E2).

[0371] According to some embodiments of any of the embodiments described herein, Component E2 comprises at least one mono-functional (meth) acrylate that features Tg lower than 80, or lower than 50, °C.

[0372] According to some embodiments of any of the embodiments described herein, Component E comprises at least one alicyclic, optionally hydrophobic, (meth)acrylate, preferably at least one alicyclic, optionally hydrophobic acrylate (Component E2), that features Tg lower than 80, or lower than 50, or of from 20 to 60, or of from 20 to 50, °C.

[0373] According to some embodiments of any of the embodiments described herein, Component E comprises at least one hydrophilic or amphiphilic (meth)acrylate, preferably at least one hydrophilic or amphiphilic acrylate (Component E3) and at least one alicyclic, optionally hydrophobic, (meth)acrylate, preferably at least one alicyclic, optionally hydrophobic acrylate (Component E2).

[0374] According to some embodiments of any of the embodiments described herein, a weight ratio of the Component E2 and the Component E3 ranges from 2:1 to 1:1, or from 1.5:1 to 1:1, including any intermediate values and subranges therebetween.

[0375] According to some embodiments of any of the embodiments described herein, an amount of the Component E2 is at least 10 %, or ranges from 10 to 20, or from 10 to 15, or from 10 to 12,%, by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0376] According to some embodiments of any of the embodiments described herein, an amount of the Component E3 is no more than 10 %, or ranges from 5 to 15, or from 5 to 10, %, by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0377] According to some embodiments of any of the embodiments described herein, a total amount of the Component E ranges from 10 to 40, or from 15 to 40, or from 15 to 30, or from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0378] According to some embodiments of any of the embodiments described herein, a total amount of Component E2 and Component E3 ranges from 10 to 40, or from 15 to 40, or from 15 to 30, or from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0379] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation comprises Component L which is or comprises Component L3 as described herein in any of the respective embodiments, Component M as described herein in any of the respective embodiments, Component E which preferably comprises or consists of Component E2 and Component E3, as described herein in any of the respective embodiments, and Component D2, as described herein in any of the respective embodiments.

[0380] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation further comprises one or more reactive diluent(s), which are also referred to herein as Component K. A reactive diluent can be added to the formulation is order to improve its viscosity, and optionally its hydrophobic / hydrophilic balance. The reactive diluent can be a mono-functional or a di-functional curable material. Exemplary reactive diluents are typically vinyl ether-type compounds, for example, (alkylene glycol) vinyl compounds. In exemplary embodiments, Component K is or comprises a di-functional curable material.

[0381] In exemplary embodiments, Component K is or comprises a divinyl ether, for example, an alkylene glycol divinyl ether, or an oligo(alkylene glycol)divinyl ether, such as, for example DVE-3.

[0382] According to some embodiments, Component K has a molecular weight lower than 500, or lower than 300, grams / mol.According to some embodiments of any of the embodiments described herein, an amount of the Component K is lower than 10, or lower than 5, %, or ranges from 1 to 10, or from 1 to 8, or from 1 to 5, or from 3 to 8 or from 3 to 5, %, by weight, of the total weight of the formulation.

[0383] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation comprises Component L which is or comprises Component L3 as described herein in any of the respective embodiments, Component M as described herein in any of the respective embodiments, Component E which preferably comprises or consists of Component E2 and Component E3, as described herein in any of the respective embodiments, Component D2, as described herein in any of the respective embodiments, and Component K, as described herein in any of the respective embodiments.

[0384] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation further comprises an additional multi-functional (meth)acrylate, which is added mainly so as to improve the reactivity of the formulation. This material is also referred to herein as Component F.

[0385] According to some embodiments of any of the embodiments described herein, Component F is a tri-functional (meth)acrylate.

[0386] According to some embodiments of any of the embodiments described herein, Component F is a multi-functional (e.g., tri-functional) (meth) acrylate that features, when hardened, Tg higher than 150, or higher than 180, or higher than 200, °C.

[0387] According to some embodiments of any of the embodiments described herein, Component F is a multi-functional (e.g., tri-functional) cyclic (meth)acrylate, which comprises one or more cyclic moieties such as aryl and / or alicyclic, and is also referred to herein as Component Fl.

[0388] According to some embodiments of any of the embodiments described herein, Component Fl is a tri-functional cyclic (meth)acrylate, which comprises one or more cyclic moieties such as aryl and / or alicyclic.

[0389] According to some embodiments of any of the embodiments described herein, Component Fl is a tri-functional cyclic methacrylate, or cyclic trimethacrylate, which comprises one or more cyclic moieties such as aryl and / or alicyclic.

[0390] According to some embodiments of any of the embodiments described herein, Component F or Fl features, when hardened, high Tg, for example, Tg higher than 100, or higher than 150, or higher than 200, or even higher than 250, °C.

[0391] According to some embodiments of any of the embodiments described herein, Component Fl is a tri-functional cyclic methacrylate, or cyclic trimethacrylate, which comprises one or morecyclic moieties such as aryl and / or alicyclic, and features, when hardened, high Tg, for example, Tg higher than 100, or higher than 150, or higher than 200, or even higher than 250, °C.

[0392] In some embodiments of any of the embodiments of Component F or Fl, the cyclic moiety is a branching unit as defined herein.

[0393] In some embodiments of any of the embodiments of Component F or Fl, the cyclic moiety is or comprises a cyanurate or an isocyanurate.

[0394] In some embodiments of any of the embodiments of Component F or Fl, the cyclic moiety is or comprises a cyanurate or an isocyanurate and is a branching unit, from which moieties that comprise the (meth)acrylate groups extend. An exemplary such material is, without limitation, marketed under the tradename SR-368.

[0395] According to some embodiments of any of the embodiments described herein, an amount of the Component F (e.g., Component Fl) ranges from 1 to 5, or from 1 to 3, % by weight of the total weight of the formulation.

[0396] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation comprises Component L which is or comprises Component L3 as described herein in any of the respective embodiments, Component M as described herein in any of the respective embodiments, Component E which preferably comprises or consists of Component E2 and Component E3, as described herein in any of the respective embodiments, Component D2, as described herein in any of the respective embodiments, and Component Fl, as described herein in any of the respective embodiments.

[0397] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation comprises Component L which is or comprises Component L3 as described herein in any of the respective embodiments, Component M as described herein in any of the respective embodiments, Component E which preferably comprises or consists of Component E2 and Component E3, as described herein in any of the respective embodiments, Component D2, as described herein in any of the respective embodiments, Component Fl, as described herein in any of the respective embodiments, and Component K, as described herein in any of the respective embodiments.

[0398] According to some embodiments of any of the embodiments described herein, the modeling material formulation further comprises a dispersant (Component H).

[0399] According to some of these embodiments, the dispersant features curable groups, preferably (meth)acrylic groups, and is also referred to herein as Component Hl.According to some embodiments of any of the embodiments described herein, the dispersant (Component Hl) is a multi-functional (e.g., di-functional) aliphatic silicon (meth)acrylate.

[0400] According to some embodiments of any of the embodiments described herein, the dispersant (Component Hl) is a di-functional aliphatic silicon (meth) acrylate.

[0401] According to some embodiments of any of the embodiments described herein, the dispersant (Component Hl) is a multi-functional (e.g., di-functional) aliphatic silicon acrylate.

[0402] According to some embodiments of any of the embodiments described herein, the dispersant (Component Hl) is a di-functional aliphatic silicon acrylate.

[0403] According to some embodiments of any of the embodiments described herein, the dispersant (Component Hl) has an average MW of at least 1,000, or at least 2,000, or at least 3,000 grams / mol, and is considered as an oligomeric material.

[0404] According to some embodiments of any of the embodiments described herein, the dispersant (Component Hl) is a multi-functional (e.g., di-functional) aliphatic silicon (meth)acrylate, having an average MW of at least 1,000 grams / mol as described herein.

[0405] According to some embodiments of any of the embodiments described herein, the dispersant (Component Hl) is a di-functional aliphatic silicon (meth)acrylate, having an average MW of at least 1,000 grams / mol as described herein.

[0406] According to some embodiments of any of the embodiments described herein, the dispersant (Component Hl) is a multi-functional (e.g., di-functional) aliphatic silicon acrylate, having an average MW of at least 1,000 grams / mol as described herein.

[0407] According to some embodiments of any of the embodiments described herein, the dispersant (Component Hl) is a di-functional aliphatic silicon acrylate, having an average MW of at least 1,000 grams / mol as described herein.

[0408] According to some embodiments of any of the embodiments described herein, the dispersant (Component Hl) features, when hardened, low Tg, preferably lower than 0, or lower than -20, or lower than -50, °C.

[0409] According to some embodiments of any of the embodiments described herein, an amount of the dispersant ranges from 0.1 to 1 or from 0.1 0.5, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0410] According to some embodiments of any of the embodiments described herein, the dispersant is or comprises a non-curable dispersant (Component H2).

[0411] Exemplary such dispersants include poly ether- modified poly dimethylsiloxanes.According to some embodiments of any of the embodiments described herein, an amount of the dispersant Component H2 ranges from 0.01 to 1, or from 0.01 to 0.5, or from 0.05 to 0.5, or from 0.1 to 0.5, or from 0.1 to 0.3, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0412] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation comprises Component L which is or comprises Component L3 as described herein in any of the respective embodiments, Component M as described herein in any of the respective embodiments, Component E which preferably comprises or consists of Component E2 and Component E3, as described herein in any of the respective embodiments, Component D2, as described herein in any of the respective embodiments, and Component Hl, as described herein in any of the respective embodiments.

[0413] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation comprises Component L which is or comprises Component L3 as described herein in any of the respective embodiments, Component M as described herein in any of the respective embodiments, Component E which preferably comprises or consists of Component E2 and Component E3, as described herein in any of the respective embodiments, Component D2, as described herein in any of the respective embodiments, Component Fl, as described herein in any of the respective embodiments, and Component H2, as described herein in any of the respective embodiments.

[0414] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation comprises Component L which is or comprises Component L3 as described herein in any of the respective embodiments, Component M as described herein in any of the respective embodiments, Component E which preferably comprises or consists of Component E2 and Component E3, as described herein in any of the respective embodiments, Component D2, as described herein in any of the respective embodiments, Component Fl, as described herein in any of the respective embodiments, Component K as described herein in any of the respective embodiments, and Component H2, as described herein in any of the respective embodiments.

[0415] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation further comprises a polymerization inhibitor (Component I), as described herein, for example, a phenol-type inhibitor or any other inhibitor that is commonly used in medical devices or applications and / in food products.According to some embodiments of any of the embodiments described herein, an amount of the inhibitor ranges from 0.01 to 0.1, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0416] According to some embodiments of any of the embodiments described herein, the modeling material formulation further comprises at least one photoinitiator (Component J).

[0417] According to some embodiments of any of the embodiments described herein, an amount of the photoinitiator ranges from 1 to 5, or from 1 to 3, % (for example, is about 2 %) by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0418] According to some embodiments of any of the embodiments described herein, the photoinitiator(s) comprises, or consists essentially of, a phosphine oxide-type (e.g., mono-acrylated (MAPO) or bis-acrylated phosphine oxide-type (BAPO) photoinitiator.

[0419] Exemplary monoacyl and bisacyl phosphine oxides include, but are not limited to, 2,4,6-trimethylbenzoyldiphenyl phosphine oxide, bis(2,4,6-trimethylbenzoyl) phenylphosphine oxide, dibenzoylphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)phenyl phosphine oxide, tris(2,4-dimethylbenzoyl) phosphine oxide, tris(2-methoxybenzoyl)phosphine oxide, 2,6-dimethoxybenzoyldiphenyl phosphine oxide, 2,6-dichlorobenzoyldiphenyl phosphine oxide, 2,3,5,6-tetramethylbenzoyldiphenyl phosphine oxide, benzoyl-bis(2,6-dimethylphenyl) phosphonate, and 2,4,6-trimethylbenzoylethoxyphenyl phosphine oxide. Commercially available phosphine oxide photoinitiators capable of free-radical initiation when irradiated at wavelength ranges of greater than about 380 nm to about 450 nm include 2,4,6-trimethylbenzoyldiphenyl phosphine oxide (TPO), bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide (marketed as IRGACURE® 819), bis(2,6-dimethoxybenzoyl)-(2,4,4-trimethylpentyl) phosphine oxide (marketed as CGI 403), a 25:75 mixture, by weight, of bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide and 2-hydroxy-2-methyl-l-phenylpropan-l-one (marketed as IRGACURE® 1700), a 1:1 mixture, by weight, of bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide and 2-hydroxy-2-methyl-l -phenylpropane- 1 -one (marketed as DAROCUR® 4265), and ethyl 2,4,6-trimethylbenzylphenyl phosphinate (LUCIRIN LR8893X).

[0420] In an exemplary embodiment, the photoinitiator is or comprises bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide (marketed as IRGACURE® 819).

[0421] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation is a colorless formulation, which is devoid of a coloring agent.

[0422] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation further comprises one or more coloring agent(s) (Component P).

[0423] The coloring agent can be a pigment or a dye and is preferably a pigment.The pigments can be organic and / or inorganic and / or metallic pigments, and in some embodiments the pigments are nanoscale pigments, which include nanoparticles.

[0424] Exemplary inorganic pigments include nanoparticles of titanium oxide, and / or of zinc oxide and / or of silica. Exemplary organic pigments include nano-sized carbon black.

[0425] In some embodiments, combinations of white and color pigments are used to prepare colored cured materials.

[0426] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a pigment and at least one (meth)acrylic material, such that the pigment is introduced to the formulation within this mixture.

[0427] According to some embodiments of any of the embodiments described herein, the pigment is a white pigment and the formulation provides a white hardened material.

[0428] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a white pigment and one or more curable materials such as (meth)acrylic materials, such that the pigment is introduced to the formulation within this mixture.

[0429] According to some of these embodiments, an amount of the white pigment in the mixture ranges from 20 to 50 % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

[0430] According to some of these embodiments, an amount of the coloring agent, which is a mixture of a white pigment and at least one (meth)acrylic material ranges from 1 to 5 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0431] According to some embodiments of any of the embodiments described herein, the coloring agent further comprises a pigment dispersant (Component Dp). Preferred pigment dispersants are such that have a plurality of groups that feature an affinity to the pigment.

[0432] According to some embodiments of any of the embodiments described herein, the curable (support material) formulation comprises Components H, I, and J, as described herein in any of the respective embodiments. An exemplary such a formulation is a colorless formulation, which is devoid of a coloring agent (devoid of Component P as described herein).

[0433] Modeling Material Formulations:

[0434] A support material formulation as described herein can be used in combination with any commercially available or previously described modeling material formulation, for example, modeling material formulations that provide materials that exhibit relatively high toughness (e.g., those marketed under the tradename Vero™).According to some embodiments of any of the embodiments described herein, the support material formulation is usable in combination with modeling material formulations designed to manufacture a denture structure as described herein, for example, with one or more of the modeling material formulations which are referred to herein as Type A and Type B formulations.

[0435] According to some embodiments of any of the embodiments described herein, a Type A or Type B modeling material formulation comprises two or more, three or more, four or more, five or more, and preferably all, of the following components:

[0436] a multi-functional (e.g., di-functional) urethane (meth)acrylate featuring, when hardened, high Tg (Component A);

[0437] a multi-functional (e.g., di-functional) non-aromatic (meth) acrylate featuring, when hardened, high Tg (Component B);

[0438] a filler in a form of particles, preferably sub-micron- sized particles (Component C); a multi-functional (e.g., di-functional) ethoxylated aromatic (meth)acrylate (Component D);

[0439] a mono-functional (meth)acrylate (Component E);

[0440] a multi-functional (e.g., tri-functional) (meth)acrylate (Component F); and

[0441] a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, low Tg (Component G).

[0442] According to some embodiments of any of the embodiments described herein, Component A is a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, Tg higher than 100 °C.

[0443] According to some embodiments of any of the embodiments described herein, Component B is a multi-functional (e.g., di-functional) non-aromatic (meth)acrylate featuring, when hardened, Tg higher than 100 °C.

[0444] According to some embodiments of any of the embodiments described herein, Component C comprises micron-sized filler particles functionalized by curable groups, as described herein.

[0445] According to some embodiments of any of the embodiments described herein, Component D is a multi-functional (e.g., di-functional) ethoxylated aromatic (meth)acrylate featuring less than 10 ethoxylated groups and / or featuring, when hardened, Tg that ranges from 50 to 150 °C (Component DI) or a multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and / or featuring, when hardened, Tg lower than 50 or lower than 0, °C (Component D2).

[0446] According to some embodiments of any of the embodiments described herein, Component E comprises at least one or at least two mono-functional (meth)acrylate(s).According to some embodiments of any of the embodiments described herein, Component F is a multi-functional (e.g., tri-functional) cyclic (meth)acrylate.

[0447] According to some embodiments of any of the embodiments described herein, Component G is a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, low Tg, e.g., Tg lower than 100 °C.

[0448] According to some embodiments of any of the embodiments described herein, an amount of the filler (Component C) is no more than 20, or no more than 15, % by weight of the total weight of the formulation.

[0449] According to some embodiments of any of the embodiments described herein, Component A is a multi-functional (e.g., di-functional) urethane (meth) acrylate featuring, when hardened, Tg higher than 100 °C.

[0450] According to some embodiments of any of the embodiments described herein, Component A is a multi-functional (e.g., di-functional) aliphatic urethane (meth)acrylate.

[0451] According to some embodiments of any of the embodiments described herein, Component A is a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, Tg higher than 100 °C, as described herein.

[0452] According to some embodiments of any of the embodiments described herein, Component A is a di-functional urethane (meth) acrylate featuring, when hardened, Tg higher than 100 °C, as described herein.

[0453] According to some embodiments of any of the embodiments described herein, Component A is a di-functional aliphatic urethane (meth)acrylate.

[0454] According to some embodiments of any of the embodiments described herein, Component A is a di-functional aliphatic urethane (meth) acrylate featuring, when hardened, Tg higher than 100 °C, as described herein.

[0455] According to some embodiments of any of the embodiments described herein, Component A is a di-functional urethane methacrylate featuring, when hardened, Tg higher than 100 °C, as described herein.

[0456] According to some embodiments of any of the embodiments described herein, Component A is a di-functional aliphatic urethane methacrylate.

[0457] According to some embodiments of any of the embodiments described herein, Component A is a di-functional aliphatic urethane methacrylate featuring, when hardened, Tg higher than 100 °C, as described herein.According to some embodiments of any of the embodiments described herein, Component A features, when hardened, Tg that ranges from 100 to 200, or from 120 to 200, or from 100 to 150, or from 120 to 150, °C, including any intermediate values and subranges therebetween.

[0458] According to some embodiments of any of the embodiments described herein, an average molecular weight of Component A is lower than 1,000 grams / mol.

[0459] Any multi-functional (e.g., di-functional) aliphatic urethane (meth)acrylate is contemplated, and preferably such materials that are acceptable for inclusion in medical devices, such as devices for long term contact in a mucosal cavity and / or in edible (e.g., food-grade) products, and / or are characterized by a toxicity profile that is considered safe for long term contact with a mucosal cavity.

[0460] An exemplary, non-limiting, material is marketed under the tradename Genomer 4297. Other urethane (meth)acrylates according to these embodiments are contemplated.

[0461] According to some embodiments of any of the embodiments described herein, Component B is a multi-functional (e.g., di-functional) non-aromatic (meth)acrylate featuring, when hardened, high Tg, for example, Tg higher than 100 °C, as described herein.

[0462] By “non-aromatic” it is meant a material that is devoid of aryl or heteroaryl groups or moieties, as these are defined herein.

[0463] Non-aromatic materials can be, for example, aliphatic or alicyclic.

[0464] According to some embodiments of any of the embodiments described herein, Component B is a multi-functional (e.g., di-functional) alicyclic (meth) acrylate featuring, when hardened, high Tg, for example, Tg higher than 100, and is referred to herein as Component Bl.

[0465] According to some embodiments of any of the embodiments described herein, Component B 1 is a di-functional alicyclic (meth) acrylate featuring, when hardened, high Tg, for example, Tg higher than 100 °C, as described herein.

[0466] According to some embodiments of any of the embodiments described herein, Component B 1 is a di-functional alicyclic acrylate, or an alicyclic diacrylate, featuring, when hardened, high Tg, for example, Tg higher than 100 °C, as described herein.

[0467] According to some embodiments of any of the embodiments described herein, Component B 1 comprises an alicyclic moiety of at least 6, 7, 8, 9, 10 or more carbon atoms.

[0468] According to some embodiments of any of the embodiments described herein, Component Bl comprises an alicyclic moiety which comprises 2, 3 or more fused rings.

[0469] According to some embodiments of any of the embodiments described herein, Component B or B 1 features, when hardened, Tg that ranges from 100 to 300, or from 150 to 300, or from 100 to 200, or from 150 to 200, °C, including any intermediate values and subranges therebetween.According to some embodiments of any of the embodiments described herein, Component B is a multi-functional (e.g., di-functional) aromatic (meth) acrylate featuring, when hardened, high Tg, for example, Tg higher than 200 °C, and is referred to herein as Component B2.

[0470] According to some embodiments of any of the embodiments described herein, Component B2 is a di-functional aromatic (meth) acrylate featuring, when hardened, high Tg, for example, Tg higher than 200 °C, as described herein.

[0471] According to embodiments of the present invention, Component C is a filler in a particulate form, comprising a plurality of particles, preferably sub-micron-sized particles.

[0472] The term “filler” as used herein describes an inert material that modifies the properties of a polymeric material and / or adjusts a quality of the end products.

[0473] Fillers (reinforcing materials) usable in additive manufacturing are typically inorganic particles of, for example, silica, calcium carbonate, clay, carbon black, and others.

[0474] In some embodiments of any of the embodiments described herein, the filler is or comprises silica particles.

[0475] In some embodiments of any of the embodiments described herein, the average diameter of the filler particles (sub-micron particles) is less than 1 micron, preferably less than 500 nm, preferably less than 200 nm and preferably less than 100 nm.

[0476] In some embodiments of any of the embodiments described herein, the filler is or comprises silica particles featuring an average diameter which is less than 1 micron, preferably less than 500 nm, preferably less than 200 nm and preferably less than 100 nm. Such silica particles are referred to also as silica nanoparticles.

[0477] In some embodiments of any of the embodiments described herein, the average diameter of the particles ranges from 10 nm to 100 nm, or from 20 nm to 100 nm, or from 20 nm to 80 nm, or from 10 nm to 50 nm, including any intermediate values and subranges therebetween.

[0478] Tn some embodiments of any of the embodiments described herein, at least a portion of such particles may aggregate, upon being introduced to the formulation. In some of these embodiments, the aggregate has an average size of no more than a few micrometers (microns).

[0479] Any commercially available formulation of sub-micron silica particles is usable in the context of the present embodiments, including fumed silica, colloidal silica, precipitated silica, layered silica (e.g., montmorillonite), and aerosol assisted self-assembly of silica particles.

[0480] The silica particles can be such that feature a hydrophobic or hydrophilic surface. The hydrophobic or hydrophilic nature of the particles’ surface is determined by the nature of the surface groups on the particles.In a preferred embodiment, at least a portion, or all, of the silica particles are functionalized by curable functional groups (particles featuring curable groups on their surface).

[0481] The curable functional groups can be any polymerizable groups as described herein. In some embodiments, the curable functional groups are polymerizable by the same polymerization reaction as the curable monomers in the formulation, and / or when exposed to the same curing condition as the curable monomers. In some embodiments, the curable groups are photocurable (e.g., UV-curable) groups. In some embodiments, the curable groups are (meth)acrylic (acrylic or methacrylic) groups, as defined herein, preferably (meth)acrylate groups.

[0482] By “at least a portion”, as used in the context of the present embodiments, it is meant at least 10 %, or at least 20 %, or at least 30 %, or at least 40 %, or at least 50 %, or at least 60 %, or at least 70 %, or at least 80 %, or at least 90 %, or at least 95 %, or at least 98 %, of the particles.

[0483] In some embodiments, the silica particles comprise silica nanoparticles featuring acrylate and / or methacrylate groups on their surface.

[0484] According to some embodiments of any of the embodiments described herein, Component B, as described herein in any of the respective embodiments and any combination thereof, preferably Component B 1 as described herein, and Component C as described herein in any of the respective embodiments, are included in the formulation as a pre-mixed composition (e.g., a dispersion of the Component C filler particles in Component B).

[0485] According to some of these embodiments, a weight ratio of Component B and Component C in the pre-mixed composition (and in a formulation comprising same) is about 1:1.

[0486] According to some embodiments of any of the embodiments described herein, a total amount of Component B (e.g., Component Bl) and Component C ranges from about 15 to about 30, or from about 15 to about 25, or from about 2- to about 25, or from about 20 to about 30, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0487] According to some embodiments of any of the embodiments described herein, Component D is a multi-functional ethoxylated (meth)acrylate.

[0488] According to some embodiments of any of the embodiments described herein, Component D is multi-functional (e.g., di-functional) ethoxylated aromatic (meth)acrylate, which comprises one or more aromatic (aryl or heteroaryl) moieties.

[0489] According to some embodiments of any of the embodiments described herein, Component D comprises a Bisphenol A moiety as a branching unit from which two or three ethoxylated moieties that terminate by (meth)acrylate groups extend.According to some embodiments of any of the embodiments described herein, Component D is a di-functional ethoxylated aromatic (meth)acrylate.

[0490] According to some embodiments of any of the embodiments described herein, Component D is multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring, when hardened, Tg lower than 200 °C.

[0491] According to some embodiments of any of the embodiments described herein, Component D is multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween.

[0492] According to some embodiments of any of the embodiments described herein, Component D is a di-functional ethoxylated aromatic (meth) acrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween.

[0493] According to some embodiments of any of the embodiments described herein, Component D is a multi-functional (e.g., di-functional) ethoxylated aromatic methacrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween.

[0494] According to some embodiments of any of the embodiments described herein, Component D is a di-functional ethoxylated aromatic methacrylate (ethoxylated aromatic dimethacrylate) featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween.

[0495] According to some embodiments of any of the embodiments described herein, Component D comprises less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties.

[0496] According to some embodiments of any of the embodiments described herein, Component D comprises a total of 4 ethoxylated moieties.

[0497] According to some embodiments of any of the embodiments described herein, Component D is a multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween and / or comprising less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties, for example, 4 ethoxylated moieties. Such a component is referred to herein as Component DI.

[0498] According to some embodiments of any of the embodiments described herein, Component DI is a multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subrangestherebetween and comprises less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties, for example, 4 ethoxylated moieties.

[0499] According to some embodiments of any of the embodiments described herein, Component DI is a di-functional ethoxylated aromatic (meth) acrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween and comprises less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties, for example, 4 ethoxylated moieties.

[0500] According to some embodiments of any of the embodiments described herein, Component DI is a multi-functional (e.g., di-functional) ethoxylated aromatic methacrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween and comprises less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties, for example, 4 ethoxylated moieties.

[0501] According to some embodiments of any of the embodiments described herein, Component DI is a di-functional ethoxylated aromatic methacrylate featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween and comprises less than 10 ethoxylated moieties, or less than 8, or less than 6 or less than 5, ethoxylated moieties, for example, 4 ethoxylated moieties.

[0502] An exemplary Component DI is, without limitation, such as marketed under the tradename SR-540, yet, any other materials are contemplated.

[0503] According to some embodiments of any of the embodiments described herein, Component D is a multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring, when hardened, lower Tg, for example, Tg lower than 50, lower than 20, or lower than 0, °C, for example, Tg of from -100 to 50, or from -100 to 0, or from -100 to -20, or from -20 to 0, °C, including any intermediate values and subranges therebetween and / or comprising at least 10, or at least 15, or at least 20, or at least 25, or at least 30, ethoxylated moieties, for example, from 10 to 50, or from 20 to 50, or from 20 to 40, or from 25, to 35, ethoxylated moieties, including any intermediate values and subranges therebetween, for example about 30 ethoxylated moieties. Such a component is referred to herein as Component D2, and is as described herein in any of the respective embodiments and any combination thereof.

[0504] According to some embodiments of any of the embodiments described herein, Component E comprises one or more mono-functional (meth) acrylate materials.

[0505] According to some embodiments of any of the embodiments described herein, Component E comprises two or more mono-functional (meth) acrylate materials.According to some embodiments of any of the embodiments described herein, Component E comprises two or more mono-functional (meth)acrylate materials, at least one is a monofunctional methacrylate, also referred to herein as Component El, and at least one is a monofunctional acrylate, also referred to herein as Component E2 or E3. Optionally, Component E2 is or comprises a mono-functional alicyclic acrylate, which comprises one or more alicyclic moieties that are attached directly or indirectly to the acrylate moiety. Component E2 can be amphiphilic, hydrophilic or hydrophobic, as these are described herein, and is preferably amphiphilic or hydrophobic.

[0506] According to some embodiments of any of the embodiments described herein, at least one, or each, of Components El, E2 and E3, is a hydrophilic and / or an amphiphilic material.

[0507] According to some embodiments of any of the embodiments described herein, Component El is a hydrophilic or amphiphilic mono-functional methacrylate.

[0508] According to some embodiments of any of the embodiments described herein, Component E2 is a mono-functional acrylate, and in some embodiments, it is a mono-functional acrylate that has an alicyclic group as Ra in Formula Al, as described herein in any of the respective embodiments.

[0509] According to some embodiments of any of the embodiments described herein, Component El is a hydrophilic or amphiphilic mono-functional methacrylate and Component E2 is a monofunctional acrylate, and in some embodiments, it is a mono-functional acrylate that has an alicyclic group as Ra in Formula Al.

[0510] Exemplary materials that are usable as Component El include, without limitation, methacrylates featuring hydroxyalkyl groups, such as, for example, marketed under the tradename BISOMEROHPMA.

[0511] Component E3 is or comprises a mono-functional acrylate that is hydrophilic or amphiphilic, and is preferably water-soluble as described herein, which can be aliphatic or alicyclic, as described herein in any of the respective embodiments.

[0512] According to some embodiments of any of the embodiments described herein, each of the mono-functional materials (Components El, E2 and E3) has an average molecular weight lower than 1,000 grams / mol or lower than 500 grams / mol, for example, of from 100 to 500 grams / mol, or from 100 to 400, or from 100 to 300, grams / mol, including any intermediate values and subranges therebetween.

[0513] According to some embodiments of any of the embodiments described herein, Component E is included in the formulation, inter alia, for balancing properties such as reactivity and / or viscosity, and Components El, E2 and / or E3, and a ratio thereof, are selected accordingly.According to some embodiments of any of the embodiments described herein, when two or more of Components El, E2 and E3 are included in a formulation as described herein, a weight ratio between each two components can range, for example, from 1:5 to 5:1, or from 3:1 to 1:3, or from 2:1 to 1:2, including any intermediate values and subranges therebetween.

[0514] According to some embodiments of any of the embodiments described herein, at least Components El and E2 are included in a formulation as described herein.

[0515] According to some embodiments of any of the embodiments described herein, a weight ratio of the mono-functional methacrylate (Component El) and the mono-functional acrylate (Component E2), when both are included in a formulation as described herein, ranges from 2:1 to 1:2.

[0516] According to some embodiments of any of the embodiments described herein, at least one or all of the mono-functional alicyclic acrylate (Component E2), the mono-functional methacrylate (Component El), and the hydrophilic or amphiphilic mono-functional acrylate (Component E3), features, when hardened, Tg lower than 100 °C or lower than 80 °C.

[0517] According to some embodiments of any of the embodiments described herein, Component F is a tri-functional (meth)acrylate.

[0518] According to some embodiments of any of the embodiments described herein, Component F is a multi-functional (e.g., tri-functional) (meth) acrylate that features, when hardened, Tg higher than 150, or higher than 180, or higher than 200, °C.

[0519] According to some embodiments of any of the embodiments described herein, Component F is a multi-functional (e.g., tri-functional) cyclic (meth)acrylate, which comprises one or more cyclic moieties such as aryl and / or alicyclic, is also referred to herein as Component Fl, and is as described herein in any of the respective embodiments.

[0520] According to some embodiments of any of the embodiments described herein, Component G is a multi-functional (e.g., di-functional) aliphatic urethane (meth)acrylate, featuring low Tg and, optionally and preferably, having an average MW of at least 1,000 grams / mol, for example, of from 1,000 to 10,000 grams / mol, including any intermediate values and subranges therebetween. Such a component is also referred to herein as an oligomeric curable material.

[0521] According to some embodiments of any of the embodiments described herein, Component G is a di-functional aliphatic urethane (meth)acrylate, having an average MW of at least 1,000 grams / mol, for example, of from 1,000 to 10,000 grams / mol, including any intermediate values and subranges therebetween. According to some of any of the embodiments described herein, Component G (including Component G1 and Component G2) is an oligomeric di-functional aliphatic urethane (meth) acrylate.According to some embodiments of any of the embodiments described herein, Component G is a multi-functional (e.g., di-functional) aliphatic urethane methacrylate, having an average MW of at least 1,000 grams / mol, for example, of from 1,000 to 10,000 grams / mol, including any intermediate values and subranges therebetween.

[0522] According to some embodiments of any of the embodiments described herein, Component G is a di-functional aliphatic urethane methacrylate, having an average MW of at least 1,000 grams / mol.

[0523] According to some embodiments of any of the embodiments described herein, Component G is a di-functional aliphatic urethane acrylate, having an average MW of at least 1,000 grams / mol.

[0524] According to some embodiments of any of the embodiments described herein, Component G features, when hardened, low Tg.

[0525] According to some embodiments of any of the embodiments described herein, Component G features, when hardened, Tg lower than 100 °C or lower than 80 °C.

[0526] According to some embodiments of any of the embodiments described herein, Component G is a non-polar (e.g., non-hydrophilic or hydrophobic) multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate as described herein.

[0527] According to some embodiments of any of the embodiments described herein, Component G is a multi-functional (e.g., di-functional) aliphatic urethane (meth)acrylate, featuring Tg lower than 0 °C, for example, of from -100 to 0, or from -100 to 20 °C, , including any intermediate values and subranges therebetween, and, optionally and preferably, having an average MW of at least 1,000 grams / mol, for example, of from 1,000 to 10,000 grams / mol, including any intermediate values and subranges therebetween. Such a component is also referred to herein as Component Gl.

[0528] According to some embodiments of any of the embodiments described herein, Component Gl is a di-functional aliphatic urethane (meth)acrylate, featuring Tg lower than 0 °C, for example, of from -100 to 0, or from -100 to -20 °C, including any intermediate values and subranges therebetween, and having an average MW of at least 1,000 grams / mol, for example, of from 1,000 to 10,000 grams / mol, including any intermediate values and subranges therebetween.

[0529] According to some embodiments of any of the embodiments described herein, Component Gl is a multi-functional (e.g., di-functional) aliphatic urethane acrylate, featuring Tg lower than 0 °C, for example, of from -100 to 0, or from -100 to -20 °C, including any intermediate values and subranges therebetween, and having an average MW of at least 1,000 grams / mol, for example, of from 1,000 to 10,000 grams / mol, including any intermediate values and subranges therebetween.

[0530] According to some embodiments of any of the embodiments described herein, Component Gl is a di-functional aliphatic urethane acrylate, featuring Tg lower than 0 °C, for example, of from-100 to 0, or from -100 to -20 °C, including any intermediate values and subranges therebetween, having an average MW of at least 1,000 grams / mol, or at least 2,000 grams / mol, or at least 3,000 grams / mol, for example, of from 3,000 to 10,000 or from 3,000 to 8,000, grams / mol, including any intermediate values and subranges therebetween.

[0531] An exemplary Component G1 is marketed under the tradename CN9002, yet, any other materials are contemplated.

[0532] According to some embodiments of any of the embodiments described herein, Component G is a multi-functional (e.g., di-functional) aliphatic urethane (meth)acrylate, featuring Tg lower than 100 °C, for example, of from 0 to 100, or from 0 to 50, or from 0 to 20, or from -20 to 50, or from -20 to 20, °C, including any intermediate values and subranges therebetween, and, optionally and preferably, having an average MW of at least 1,000 grams / mol, for example, of from 1,000 to 10,000 grams / mol, including any intermediate values and subranges therebetween. Such a component is also referred to herein as Component G2.

[0533] According to some embodiments of any of the embodiments described herein, Component G2 is a di-functional aliphatic urethane (meth)acrylate, featuring Tg lower than 100 °C, for example, of from 0 to 100, or from 0 to 50, or from 0 to 20, or from -20 to 50, or from -20 to 20, °C, including any intermediate values and subranges therebetween, and having an average MW of at least 1,000 grams / mol, for example, of from 1,000 to 10,000 grams / mol, including any intermediate values and subranges therebetween.

[0534] According to some embodiments of any of the embodiments described herein, Component G2 is a multi-functional (e.g., di-functional) aliphatic urethane methacrylate, featuring Tg lower than 100 °C, for example, of from 0 to 100, or from 0 to 50, or from 0 to 20, or from -20 to 50, or from -20 to 20, °C, including any intermediate values and subranges therebetween, having an average MW of at least 1,000 grams / mol, for example, of from 1,000 to 10,000 grams / mol, including any intermediate values and subranges therebetween.

[0535] According to some embodiments of any of the embodiments described herein, Component G2 is a di-functional aliphatic urethane methacrylate, featuring Tg lower than 100 °C, for example, of from 0 to 100, or from 0 to 50, or from 0 to 20, or from -20 to 50, or from -20 to 20, °C, including any intermediate values and subranges therebetween, having an average MW of at least 1,000 grams / mol, for example, of from 1,000 to 5,000 or from 1,000 to 3,000, grams / mol, including any intermediate values and subranges therebetween.

[0536] An exemplary Component G2 is marketed under the tradename CN1970EU, yet, any other materials are contemplated.According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation further comprises a dispersant (Component H).

[0537] According to some of these embodiments, the dispersant features curable groups (Component Hl), preferably (meth)acrylic groups, and is as described herein in any of the respective embodiments.

[0538] According to some embodiments of any of the embodiments described herein, the dispersant Component Hl has an average MW of at least 1,000, or at least 2,000, or at least 3,000 grams / mol, and is considered as an oligomeric material.

[0539] According to some embodiments of any of the embodiments described herein, the dispersant Component Hl is a multi-functional (e.g., di-functional) aliphatic silicon (meth)acrylate, having an average MW of at least 1,000 grams / mol as described herein.

[0540] According to some embodiments of any of the embodiments described herein, the dispersant Component Hl is a di-functional aliphatic silicon (meth)acrylate, having an average MW of at least 1,000 grams / mol as described herein.

[0541] According to some embodiments of any of the embodiments described herein, the dispersant Component Hl is a multi-functional (e.g., di-functional) aliphatic silicon acrylate, having an average MW of at least 1,000 grams / mol as described herein.

[0542] According to some embodiments of any of the embodiments described herein, the dispersant Component Hl is a di-functional aliphatic silicon acrylate, having an average MW of at least 1,000 grams / mol as described herein.

[0543] According to some embodiments of any of the embodiments described herein, the dispersant Component Hl features, when hardened, low Tg, preferably lower than 0, or lower than -20, or lower than -50, °C.

[0544] According to some embodiments of any of the embodiments described herein, an amount of the dispersant Component Hl ranges from 0.1 to 1 or from 0.1 0.5, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0545] According to some embodiments of any of the embodiments described herein, the modeling material formulation further comprises a polymerization inhibitor (Component I), as described herein, for example, a phenol-type inhibitor or any other inhibitor that is commonly used in medical devices or applications and / in food products.

[0546] According to some embodiments of any of the embodiments described herein, an amount of the inhibitor ranges from 0.001 to 0.010, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.According to some embodiments of any of the embodiments described herein, the modeling material formulation further comprises at least one photoinitiator (Component J).

[0547] According to some embodiments of any of the embodiments described herein, an amount of the photoinitiator ranges from 1 to 5, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0548] According to some embodiments of any of the embodiments described herein, the photoinitiator(s) comprises, or consists essentially of, a phosphine oxide-type (e.g., mono-acrylated (MAPO) or bis-acrylated phosphine oxide-type (BAPO) photoinitiator, as described herein in any of the respective embodiments.

[0549] In an exemplary embodiment, the photoinitiator is or comprises bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide (marketed as IRGACURE® 819).

[0550] In an exemplary embodiment, the photoinitiator is devoid of 2,4,6-trimethylbenzoyldiphenyl phosphine oxide (marketed as TPO) and / or bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide (marketed as IRGACURE® 819).

[0551] According to some embodiments of any of the embodiments described herein, the modeling material formulation is a clear (e.g., transparent), colorless formulation, which is devoid of a coloring agent.

[0552] According to some embodiments of any of the embodiments described herein, the modeling material formulation further comprises one or more coloring agent(s) (Component P).

[0553] The coloring agent can be a pigment or a dye and is preferably a pigment.

[0554] The pigments can be organic and / or inorganic and / or metallic pigments, and in some embodiments the pigments are nanoscale pigments, which include nanoparticles.

[0555] Exemplary inorganic pigments include nanoparticles of titanium oxide, and / or of zinc oxide and / or of silica. Exemplary organic pigments include nano-sized carbon black.

[0556] In some embodiments, combinations of white and color pigments are used to prepare colored cured materials.

[0557] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a pigment and at least one (meth)acrylic material, such that the pigment is introduced to the formulation within this mixture.

[0558] According to some embodiments of any of the embodiments described herein, the pigment is a white pigment and the formulation provides a white hardened material.

[0559] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a white pigment and one or more curable materials such as (meth)acrylic materials, such that the pigment is introduced to the formulation within this mixture.According to some of these embodiments, an amount of the white pigment in the mixture ranges from 20 to 50 % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

[0560] According to some of these embodiments, an amount of the coloring agent, which is a mixture of a white pigment and at least one (meth)acrylic material ranges from 1 to 5 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0561] According to some embodiments of any of the embodiments described herein, the pigment is a cyan pigment and the formulation provides a cyan hardened material.

[0562] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a cyan pigment and one or more curable materials such as (meth)acrylic materials, such that the cyan pigment is introduced to the formulation within this mixture.

[0563] According to some of these embodiments, an amount of the cyan pigment in the mixture ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture.

[0564] According to some of these embodiments, an amount of the coloring agent, which is a mixture of a cyan pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0565] According to some embodiments of any of the embodiments described herein, the pigment is a yellow pigment and the formulation provides a yellow hardened material.

[0566] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a yellow pigment and one or more curable materials such as (meth)acrylic materials, such that the yellow pigment is introduced to the formulation within this mixture.

[0567] According to some of these embodiments, an amount of the yellow pigment in the mixture ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

[0568] According to some of these embodiments, an amount of the coloring agent, which is a mixture of a yellow pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.According to some embodiments of any of the embodiments described herein, the pigment is a magenta pigment and the formulation provides a magenta hardened material.

[0569] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a magenta pigment and one or more curable materials such as (meth)acrylic materials, such that the magenta pigment is introduced to the formulation within this mixture.

[0570] According to some of these embodiments, an amount of the magenta pigment in the mixture ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

[0571] According to some of these embodiments, an amount of the coloring agent, which is a mixture of a magenta pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0572] According to some embodiments of any of the embodiments described herein, the formulation comprises one or more of a white, magenta, cyan, and yellow coloring agents, and in some of these embodiments, each pigment is introduced to the formulation in a mixture with curable materials as described herein.

[0573] According to some embodiments of any of the embodiments described herein, the coloring agent further comprises a pigment dispersant (Component Dp). Preferred pigment dispersants are such that have a plurality of groups that feature an affinity to the pigment.

[0574] According to some embodiments of any of the embodiments described herein, the modeling material formulation comprises Components H, I, and J, as described herein in any of the respective embodiments. An exemplary such a formulation is a clear colorless formulation, which is devoid of a coloring agent (devoid of Component P as described herein).

[0575] According to some embodiments of any of the embodiments described herein, the modeling material formulation comprises Components H, I, J and P, as described herein in any of the respective embodiments. An exemplary such a formulation is a white formulation that comprises a white pigment as described herein.

[0576] According to some embodiments of any of the embodiments described herein, the modeling material formulation comprises Components H, I, J, P and Dp, as described herein in any of the respective embodiments. Exemplary such formulations are the cyan, magenta and yellow formulations as described herein.Type B modeling material formulation:

[0577] According to some embodiments of any of the embodiments described herein, a Type B formulation comprises multi-functional (meth)acrylate materials that feature relatively high MW (e.g., higher than 1,000 grams / mol; oligomeric materials) and relatively low Tg (e.g., lower than 100 °C), such as, for example, Components D2, G1 and G2 as described herein, combined with mono-functional materials such Component E (e.g., Component El, E2 and / or E3), and optionally and preferably Component H, as described herein in any of the respective embodiments.

[0578] According to some embodiments of any of the embodiments described herein, the Type B formulation comprises Component D2, Component G, preferably Component G2, and a mixture of two or more of Components El, E2 and E3.

[0579] According to some embodiments of any of the embodiments described herein, a Type B formulation comprises:

[0580] at least one multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and / or Tg lower than 0 °C (Component D2);

[0581] at least one multi-functional (e.g., di-functional) urethane (meth)acrylate featuring Tg lower than 100 °C (Component G);

[0582] at least one mono-functional alicyclic (meth)acrylate, preferably a mono-functional alicyclic acrylate (Component E2);

[0583] optionally at least one mono-functional acrylate (Component E3), preferably hydrophilic or amphiphilic; and

[0584] at least one dispersant (preferably Component Hl).

[0585] According to some embodiments, the formulation comprises at least one multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and / or Tg lower than 0 °C (Component D2); and at least one multi-functional (e.g., di-functional) urethane (meth) acrylate featuring Tg lower than 100 °C (Component G), preferably Component G2 as described herein, in a total amount (of Component D2 and Component G) of from 20 to 50, or from 30 to 50, or from 35 to 45, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0586] According to some embodiments of any of the embodiments described herein, the formulation further comprises a mixture of two or more of Components E2 and E3, and in some of these embodiments, this mixture is in a total amount of from 40 to 60, or from 45 to 60, or from 50 to 60, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0587] According to some embodiments, the formulation comprises:at least one multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and / or Tg lower than 0 °C (e.g., Component D2);

[0588] at least one multi-functional (e.g., di-functional) urethane (meth)acrylate featuring Tg lower than 100 °C (e.g., Component G);

[0589] at least one mono-functional alicyclic (meth)acrylate (e.g., Component E2), preferably a mono-functional alicyclic acrylate;

[0590] at least one mono-functional acrylate (e.g., Component E3), preferably hydrophilic or amphiphilic; and

[0591] at least one dispersant (e.g., Component Hl).

[0592] According to some embodiments of any of the embodiments described herein, the formulation comprises:

[0593] at least one multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and / or Tg lower than 0 °C, (e.g., Component D2) in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0594] at least one multi-functional (e.g., di-functional) urethane (meth)acrylate featuring Tg lower than 100 °C (e.g., Component G), in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0595] at least one mono-functional alicyclic (meth)acrylate, preferably a mono-functional alicyclic acrylate (e.g., Component E2), in a total amount of at least 40, or at least 45, or of from 45 to 55, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0596] at least one mono-functional acrylate, preferably hydrophilic or amphiphilic (e.g., Component E3), in a total amount of from 3 to 10, or from 5 to 10, or from 3 to 8, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; and

[0597] at least one dispersant (e.g., Component Hl), as described herein in any of the respective embodiments.

[0598] According to some embodiments of any of the embodiments described herein, the formulation comprises:

[0599] at least one multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring at least 10 ethoxylated groups and / or Tg lower than 0 °C (Component D2), in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween;at least one multi-functional (e.g., di-functional) urethane (meth)acrylate featuring Tg lower than 100 °C (Component G), in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0600] at least one mono-functional alicyclic (meth)acrylate, preferably a mono-functional alicyclic acrylate (Component E2), in a total amount of at least 40, or at least 45, or of from 45 to 55, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0601] at least one mono-functional acrylate (Component E3), preferably hydrophilic or amphiphilic, in a total amount of from 3 to 10, or from 5 to 10, or from 3 to 8, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; and at least one dispersant (Component Hl).

[0602] According to some embodiments of any of the embodiments described herein for Type B formulation, the formulation comprises:

[0603] Component D2, as described herein in any of the respective embodiment and any combination thereof, in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0604] Component G, preferably Component G2, as described herein in any of the respective embodiment and any combination thereof, in a total amount of from 15 to 25 % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0605] at least one, or at least two of Component E2, as described herein in any of the respective embodiment and any combination thereof, in a total amount of at least 40, or at least 45, or of from 45 to 55, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0606] at least one Component E3, as described herein in any of the respective embodiment and any combination thereof, in a total amount of from 3 to 10, or from 5 to 10, or from 3 to 8, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween; and

[0607] at least one dispersant (e.g., Component Hl), as described herein in any of the respective embodiment and any combination thereof, preferably in a total amount of from 0.1 to 1 or from 0.1 to 0.5, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0608] According to some embodiments of any of the embodiments described herein for the Type B formulation, Component D2 comprises a multi-functional (e.g., di-functional) ethoxylatedaromatic (meth) acrylate featuring at least 10 ethoxylated groups and Tg lower than 0 °C features, when hardened, Tg lower than 0 °C.

[0609] According to some embodiments of any of the embodiments described herein for the Type B formulation, Component D2 has a molecular weight of at least 1,000 grams / mol.

[0610] According to some embodiments of any of the embodiments described herein for the Type B formulation, Component D2 is a multi-functional (e.g., di-functional) ethoxylated aromatic methacrylate featuring at least 10 ethoxylated groups.

[0611] According to some embodiments of any of the embodiments described herein for the Type B formulation, Component D2 comprises a multi-functional (e.g., di-functional) ethoxylated aromatic methacrylate featuring at least 10 ethoxylated groups, features, when hardened, Tg lower than 0 °C, and has a molecular weight of at least 1,000 grams / mol.

[0612] According to some embodiments of any of the embodiments described herein for the Type B formulation, Component G comprises or consists of a multi-functional (e.g., di-functional) urethane (meth) acrylate having a molecular weight of at least 1,000 grams / mol.

[0613] According to some embodiments of any of the embodiments described herein for the Type B formulation, Component G features Tg lower than 100 °C, preferably Tg that ranges from 0 to 100, or from 50 to 100, °C, including any intermediate values and subranges therebetween and is or comprises Component G2, as described herein.

[0614] According to some embodiments of any of the embodiments described herein for the Type B formulation, Component G comprises a multi-functional (e.g., di-functional) urethane methacrylate.

[0615] According to some embodiments of any of the embodiments described herein for the Type B formulation, Component D2 comprises a multi-functional (e.g., di-functional) ethoxylated aromatic methacrylate featuring at least 10 ethoxylated groups, features, when hardened, Tg lower than 0 °C, and has a molecular weight of at least 1,000 grams / mol.

[0616] Component G comprises a Component G2 which is a multi-functional (e.g., di-functional) urethane (meth)acrylate featuring, when hardened, Tg that ranges from 0 to 100, or from 50 to 100, °C, including any intermediate values and subranges therebetween, and having a molecular weight of at least 1,000 grams / mol.

[0617] According to some embodiments of any of the embodiments described herein for the Type B formulation, a total amount of the at least one Component D2 and the at least one Component G (e.g., Component G2) ranges from about 30 to about 50, or from about 40 to about 50, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.According to some embodiments of any of the embodiments described herein for the Type B formulation, the at least one Component E2 has a molecular weight (MW) of no more than 500 (e.g., of from 100 to 500) grams / mol.

[0618] According to some embodiments of any of the embodiments described herein for the Type B formulation, each of the one or more of Component E2 independently features, when hardened, Tg lower than 100 °C, or lower than 50 °C (e.g., of from 20 to 60, or from 20 to 50 °C, including any intermediate values and subranges therebetween).

[0619] According to some embodiments of any of the embodiments described herein for the Type B formulation, the one or more Components E2 comprises a mono-functional alicyclic, preferably hydrophobic, acrylate having a molecular weight (MW) of no more than 500 (e.g., of from 100 to 500) grams / mol and featuring, when hardened, Tg lower than 100 °C, or lower than 50 °C (e.g., of from 20 to 60, or from 20 to 50 °C, including any intermediate values and subranges therebetween).

[0620] According to some embodiments of any of the embodiments described herein for the Type B formulation, Component E3 comprises a mono -functional hydrophilic or amphiphilic acrylate having a molecular weight (MW) of no more than 500 (e.g., of from 100 to 500) grams / mol.

[0621] According to some embodiments of any of the embodiments described herein for the Type B formulation, Component E3 comprises a mono -functional hydrophilic or amphiphilic acrylate featuring, when hardened, Tg higher than 50 °C, or higher than 80 °C (e.g., of from 50 to 150 °C, including any intermediate values and subranges therebetween).

[0622] According to some embodiments of any of the embodiments described herein for the Type B formulation, an amount of the Component H is at least 0.1, or from 0.1 to 1, or from 0.1 to 0.5, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0623] According to some embodiments of any of the embodiments described herein for the Type B formulation, the Component D2 comprises a multi-functional (e.g., di-functional) ethoxylated aromatic methacrylate featuring at least 10 ethoxylated groups, having a molecular weight of at least 1,000 grams / mol as described herein, which features, when hardened, Tg lower than 0 °C, and has a molecular weight of at least 1,000 grams / mol; the Component G comprises a Component G2 which is a multi-functional (e.g., di-functional) urethane (meth) acrylate , featuring, when hardened, Tg that ranges from 0 to 100, or from 50 to 100, °C, including any intermediate values and subranges therebetween, and having a molecular weight of at least 1,000 grams / mol as described herein; a total amount of the at least one Component D2 and the at least one Component G2 is at least 35, or at least 40, or ranges from 35 to 50, or from about 40 to 50, % by weight of the total weight of the formulation; the at least one Component E2 comprises a mono-functionalalicyclic, preferably hydrophobic, acrylate having a molecular weight (MW) of no more than 500 (c.g., of from 100 to 500) grams / mol and featuring, when hardened, Tg lower than 100 °C, or lower than 50 °C (e.g., of from 20 to 60, or from 20 to 50 °C, including any intermediate values and subranges therebetween); the at least one Component E3 comprises a mono-functional hydrophilic or amphiphilic acrylate having a molecular weight (MW) of no more than 500 (e.g., of from 100 to 500) grams / mol and featuring, when hardened, Tg higher than 50 °C, or higher than 80 °C (e.g., of from 50 to 150 °C, including any intermediate values and subranges therebetween); and an amount of the Component H is at least 0.1 or ranges from 0.1 to 1 or from 0.1 to 0.5, % by weight of the total weight of the formulation.

[0624] According to some embodiments of any of the embodiments described herein for the Type B formulation, the formulation further comprises an inhibitor (Component I) and / or a photoinitiator (Component J), as these are described herein in any of the respective embodiments.

[0625] According to some embodiments of any of the embodiments described herein for the Type B formulation, the formulation further comprises a coloring agent (Component P), as described herein, which preferably comprises a mixture of a pigment and at least one (meth)acrylic material.

[0626] In exemplary embodiments, the pigment is a white pigment.

[0627] In exemplary embodiments, the Type B formulation is devoid of a pigment or a coloring agent Component P, and is, for example, a transparent or clear formulation.

[0628] Type A modeling material formulation:

[0629] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation comprises two or more, three or more, four or more, five or more, or all, of the components described herein as Components A, B, C, D, E, F and G, and in some of these embodiments, it further comprises one or more of the components H, I, J, P and Dp.

[0630] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation comprises two or more, three or more, four or more, five or more, and preferably all, of the following components:

[0631] a multi-functional (e.g., di-functional) urethane (meth)acrylate featuring, when hardened, high Tg (Component A);

[0632] a multi-functional (e.g., di-functional) non-aromatic (meth) acrylate featuring, when hardened, high Tg (Component B);

[0633] a filler in a form of micron-sized particles (Component C);

[0634] a multi-functional (e.g., di-functional) ethoxylated aromatic (meth)acrylate (Component D);a mono-functional (meth)acrylate (Component E);

[0635] a multi-functional (e.g., tri-functional) (meth)acrylate (Component F); and

[0636] a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, low Tg (Component G).

[0637] According to some embodiments of any of the embodiments described herein, Component A is a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, Tg higher than 100 °C.

[0638] According to some embodiments of any of the embodiments described herein, Component B is a multi-functional (e.g., di-functional) non-aromatic (meth)acrylate featuring, when hardened, Tg higher than 100 °C.

[0639] According to some embodiments of any of the embodiments described herein, Component C comprises filler particles functionalized by curable groups, as described herein, and having an average diameter of less than 1 micron (sub-micron-sized particles or nanoparticles).

[0640] According to some embodiments of any of the embodiments described herein, Component D is a multi-functional (e.g., di-functional) ethoxylated aromatic (meth)acrylate featuring less than 10 ethoxylated groups and / or featuring, when hardened, Tg that ranges from 50 to 150 °C, including any intermediate values and subranges therebetween.

[0641] According to some embodiments of any of the embodiments described herein, Component E comprises at least one or at least two mono-functional (meth)acrylate(s).

[0642] According to some embodiments of any of the embodiments described herein, Component F is a multi-functional (e.g., tri-functional) cyclic (meth)acrylate.

[0643] According to some embodiments of any of the embodiments described herein, Component G is a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, Tg lower than 100 °C.

[0644] According to some embodiments of any of the embodiments described herein, an amount of the filler (Component C) is no more than 20, or no more than 15, % by weight of the total weight of the formulation.

[0645] According to some embodiments of any of the embodiments as described herein, an amount of the Component D is no more than 20, or no more than 15, % by weight of the total weight of the formulation.

[0646] According to some embodiments of any of the embodiments described herein, an amount of the filler is no more than 20, or no more than 15, % by weight of the total weight of the formulation; and an amount of the Component D is no more than 20, or no more than 15, % by weight of the total weight of the formulation.According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation comprises:

[0647] a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, Tg higher than 100 °C (Component A);

[0648] a multi-functional (e.g., di-functional) non-aromatic (meth) acrylate featuring, when hardened, Tg higher than 100 °C (Component B);

[0649] a filler in a form of micron-sized particles (Component C);

[0650] a multi-functional (e.g., di-functional) ethoxylated aromatic (meth) acrylate featuring less than 10 ethoxylated groups and / or featuring, when hardened, Tg that ranges from 50 to 150 °C (Component D);

[0651] a mono-functional (meth)acrylate (Component E);

[0652] a multi-functional (e.g., tri-functional) cyclic (meth)acrylate (Component F); and a multi-functional (e.g., di-functional) aliphatic urethane (meth) acrylate featuring, when hardened, Tg lower than 100 °C (Component G),

[0653] wherein:

[0654] an amount of the filler (Component C) is no more than 20, or no more than 15, % by weight of the total weight of the formulation; and

[0655] an amount of the Component D is no more than 20, or no more than 15, % by weight of the total weight of the formulation.

[0656] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation comprises Component A as defined herein, Component Bl as defined herein, Component C as defined herein, Component DI as defined herein, Components El and E2 as defined herein, Component Fl as defined herein, and Component G, as defined herein (for example, Component G2).

[0657] According to some embodiments of any of the embodiments described herein, an amount of Component A, as described herein in any of the respective embodiments and any combination thereof, ranges from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0658] According to some embodiments of any of the embodiments described herein, an amount of each of Components B and C, as described herein in any of the respective embodiments and any combination thereof, is no more than 20, or no more than 15, % by weight of the total weight of the formulation, and, for example, ranges from about 5 to about 20, or preferably from about 5 to about 15, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.According to some embodiments of any of the embodiments described herein, an amount of Component D, as described herein in any of the respective embodiments and any combination thereof, is no more than 20, or no more than 15, % by weight of the total weight of the formulation, and preferably ranges from about 5 to about 20, or preferably from about 5 to about 15, % by weight, including any intermediate values and subranges therebetween.

[0659] According to some embodiments of any of the embodiments described herein, a total amount of Component E, as described herein in any of the respective embodiments and any combination thereof, ranges 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0660] According to some embodiments of any of the embodiments described herein, an amount of Component F, as described herein in any of the respective embodiments and any combination thereof, ranges from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0661] According to some embodiments of any of the embodiments described herein, an amount of Component G, as described herein in any of the respective embodiments and any combination thereof, ranges from about 5 to about 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0662] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation comprises:

[0663] Component A, as described herein in any of the respective embodiments and any combination thereof, in an amount that ranges from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0664] Components B and C, as described herein in any of the respective embodiments and any combination thereof, each independently in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0665] Component D, as described herein in any of the respective embodiments and any combination thereof, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0666] Component E, as described herein in any of the respective embodiments and any combination thereof, in an amount of from 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0667] Component F, as described herein in any of the respective embodiments and any combination thereof, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; andComponent G, as described herein in any of the respective embodiments and any combination thereof, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0668] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation comprises:

[0669] Component A, as described herein in any of the respective embodiments and any combination thereof, in an amount that ranges from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0670] Component B, as described herein in any of the respective embodiments and any combination thereof, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0671] Component C, as described herein in any of the respective embodiments and any combination thereof, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0672] Component D, as described herein in any of the respective embodiments and any combination thereof, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0673] Components El and E2, as described herein in any of the respective embodiments and any combination thereof, in a total amount of from 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0674] Component Fl, as described herein in any of the respective embodiments and any combination thereof, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; and Component G, as described herein in any of the respective embodiments and any combination thereof, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0675] According to some embodiments of any of the embodiments described herein, Component El is a hydrophilic or amphiphilic mono-functional methacrylate and Component E2 is a monofunctional acrylate, and in some embodiments, it is a mono-functional acrylate that has an alicyclic group as Ra in Formula Al.

[0676] According to some embodiments of any of the embodiments described herein, a weight ratio of the mono-functional methacrylate (El) and the mono-functional acrylate (E2) ranges from 2:1 to 1:2, or is about 1:1.According to some embodiments of any of the embodiments described herein, an amount of each of the mono-functional acrylate (E2) and the mono-functional methacrylate (El) independently ranges from 10 to 20, or from 15 to 20, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0677] According to some embodiments of any of the embodiments described herein, a total amount of the one or more mono-functional (meth)acrylate(s) (e.g., Components El and E2) ranges from 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0678] According to some embodiments of any of the embodiments described herein, at least one or both of the mono-functional acrylate (Component E2) and the mono-functional methacrylate (Component El) features, when hardened, Tg lower than 100 °C or lower than 80 °C.

[0679] According to exemplary embodiments, the Type A modeling material formulation comprises:

[0680] Component A as described herein in any of the respective embodiments and any combination thereof in an amount that ranges from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0681] Component B as described herein in any of the respective embodiments and any combination thereof, preferably Component B 1, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0682] Component C as described herein in any of the respective embodiments and any combination thereof, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0683] Component D as described herein in any of the respective embodiments and any combination thereof, preferably Component DI, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0684] Component E as described herein in any of the respective embodiments and any combination thereof, preferably a mixture of Components El and E2, in a total amount of from 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0685] Component F as described herein in any of the respective embodiments and any combination thereof, preferably Component Fl, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; andComponent G as described herein in any of the respective embodiments and any combination thereof, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0686] According to exemplary embodiments, the Type A modeling material formulation comprises:

[0687] as Component A - a di-functional aliphatic urethane methacrylate featuring, when hardened, Tg higher than 100 °C, such as described herein;

[0688] as Component B - Component B 1 which is a di-functional alicyclic acrylate featuring, when hardened, Tg higher than 100 °C, such as described herein;

[0689] as Component C comprises silica particles having curable groups attached thereto, such as described herein;

[0690] as Component D - Component DI which is a di-functional ethoxylated aromatic methacrylate featuring less than 5 ethoxylated groups and, when hardened, Tg that ranges from 50 to 150 °C, such as described herein;

[0691] as Component E - a mono-functional acrylate (Component E2) and a mono-functional methacrylate (Component El), each independently in an amount of from 10 to 20, or from 15 to 20, % by weight, of the total weight of the formulation;

[0692] as Component F - Component Fl which is a tri-functional isocyanurate triacrylate; and as Component G - a di-functional aliphatic urethane dimethacrylate featuring, when hardened, Tg lower than 100 °C and an average MW of at least 1,000 grams / mol, such as described herein.

[0693] According to exemplary embodiments, the Type A modeling material formulation comprises:

[0694] as Component A - a di-functional aliphatic urethane methacrylate featuring, when hardened, Tg higher than 100 °C, such as described herein, in an amount that ranges from 15 to 25, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0695] as Component B - Component B 1 which is a di-functional alicyclic acrylate featuring, when hardened, Tg higher than 100 °C, such as described herein, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0696] as Component C - comprises silica particles having curable groups attached thereto, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0697] as Component D - Component DI which is a di-functional ethoxylated aromatic methacrylate featuring less than 5 ethoxylated groups and, when hardened, Tg that ranges from 50to 150 °C, including any intermediate values and subranges therebetween, such as described herein, in an amount of no more than 20, or no more than 15, % by weight of the total weight of the formulation;

[0698] as Component E - a mono-functional acrylate (Component E2) and a mono-functional methacrylate (Component El), each independently in an amount of from 10 to 20, or from 15 to 20, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween, in a total amount of from 30 to 40 % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween;

[0699] as Component F - Component Fl which is a tri-functional isocyanurate triacrylate, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween; and

[0700] as Component G - a di-functional aliphatic urethane dimethacrylate featuring, when hardened, Tg lower than 100 °C and an average MW of at least 1,000 grams / mol, such as described herein, in an amount of from 5 to 10, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0701] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation comprises, as Component G, Component G1 as described herein in any of the respective embodiments.

[0702] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation is devoid of methyl methacrylate and / or methyl acrylate, and / or is such that the hardened modeling material is devoid of poly (methyl methacrylate) (PMMA).

[0703] Herein throughout, by “devoid of’ it is meant less than 1 %, or less than 0.1 %, or less than 0.01 %, or less than 0.001 %, or null.

[0704] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation further comprises a dispersant (e.g., Component Hl), as described herein in any of the respective embodiments.

[0705] According to some embodiments of any of the embodiments described herein, an amount of the dispersant ranges from 0.1 to 0.5, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0706] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation further comprises a polymerization inhibitor (Component I), as described herein, for example, a phenol-type inhibitor or any other inhibitor that is commonly used in medical devices or applications and / in food products.According to some embodiments of any of the embodiments described herein, an amount of the inhibitor ranges from 0.001 to 0.010, % by weight, of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0707] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation further comprises at least one photoinitiator (Component J).

[0708] According to some embodiments of any of the embodiments described herein, an amount of the photoinitiator ranges from 1 to 5, % by weight of the total weight of the formulation, including any intermediate values and subranges therebetween.

[0709] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation further comprises one or more coloring agent(s) (Component P).

[0710] The coloring agent can be a pigment or a dye and is preferably a pigment.

[0711] The pigments can be organic and / or inorganic and / or metallic pigments, and in some embodiments the pigments are nanoscale pigments, which include nanoparticles.

[0712] Exemplary inorganic pigments include nanoparticles of titanium oxide, and / or of zinc oxide and / or of silica. Exemplary organic pigments include nano-sized carbon black.

[0713] In some embodiments, combinations of white and color pigments are used to prepare colored cured materials.

[0714] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a pigment and at least one (meth)acrylic material, such that the pigment is introduced to the formulation within this mixture.

[0715] According to some embodiments of any of the embodiments described herein, the pigment is a white pigment and the formulation provides a white hardened material.

[0716] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a white pigment and one or more curable materials such as (meth)acrylic materials, such that the pigment is introduced to the formulation within this mixture.

[0717] According to some of these embodiments, an amount of the white pigment in the mixture with the one or more curable materials ranges from 20 to 50 % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

[0718] According to some of these embodiments, an amount of the coloring agent, which is a mixture of a white pigment and at least one (meth)acrylic material ranges from 1 to 5 % by weight of the total weight of the (e.g., Type A) formulation, including any intermediate values and subranges therebetween.

[0719] According to some embodiments of any of the embodiments described herein, the pigment is a cyan pigment and the formulation provides a cyan hardened material.According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a cyan pigment and one or more curable materials such as (meth)acrylic materials, such that the cyan pigment is introduced to the formulation within this mixture.

[0720] According to some of these embodiments, an amount of the cyan pigment in the mixture with the one or more curable materials ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

[0721] According to some of these embodiments, an amount of the coloring agent, which is a mixture of a cyan pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the (e.g., Type A) formulation, including any intermediate values and subranges therebetween.

[0722] According to some embodiments of any of the embodiments described herein, the pigment is a yellow pigment and the formulation provides a yellow hardened material.

[0723] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a yellow pigment and one or more curable materials such as (meth)acrylic materials, such that the yellow pigment is introduced to the formulation within this mixture.

[0724] According to some of these embodiments, an amount of the yellow pigment in the mixture with the one or more curable materials ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to 0.2, % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

[0725] According to some of these embodiments, an amount of the coloring agent, which is a mixture of a yellow pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the (e.g., Type A) formulation, including any intermediate values and subranges therebetween.

[0726] According to some embodiments of any of the embodiments described herein, the pigment is a magenta pigment and the formulation provides a magenta hardened material.

[0727] According to some embodiments of any of the embodiments described herein, the coloring agent comprises a mixture of a magenta pigment and one or more curable materials such as (meth)acrylic materials, such that the magenta pigment is introduced to the formulation within this mixture.

[0728] According to some of these embodiments, an amount of the magenta pigment in the mixture with the one or more curable materials ranges from 0.01 to 1, or from 0.05 to 0.5, or from 0.1 to0.2, % by weight of the total weight of the mixture, including any intermediate values and subranges therebetween.

[0729] According to some of these embodiments, an amount of the coloring agent, which is a mixture of a magenta pigment and at least one (meth)acrylic material ranges from 0.1 to 1 % by weight of the total weight of the (e.g., Type A) formulation, including any intermediate values and subranges therebetween.

[0730] According to some embodiments of any of the embodiments described herein, the formulation comprises one or more of a white, magenta, cyan, and yellow coloring agents, and in some of these embodiments, each pigment is introduced to the formulation in a mixture with curable materials as described herein.

[0731] According to some embodiments of any of the embodiments described herein, the coloring agent further comprises a pigment dispersant (Component Dp). Preferred pigment dispersants are such that has a plurality of groups that feature an affinity to the pigment.

[0732] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation comprises Components H, I, and J, as described herein in any of the respective embodiments. An exemplary such a formulation is a clear colorless formulation, which is devoid of a coloring agent.

[0733] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation comprises Components H, I, J and P, as described herein in any of the respective embodiments. An exemplary such a formulation is a white formulation that comprises a white pigment as described herein.

[0734] According to some embodiments of any of the embodiments described herein, the Type A modeling material formulation comprises Components H, I, J, P and Dp, as described herein in any of the respective embodiments. Exemplary such formulations are the cyan, magenta and yellow formulation as described herein.

[0735] Kits:

[0736] In some embodiments of any of the embodiments described herein there is provided a kit comprising the curable support material formulation as described herein in any of the respective embodiments, and optionally one or more modeling material formulations, for example Type A and / or Type B formulations as described herein in any of the respective embodiments and any combination thereof.

[0737] In some of these embodiments, each formulation is packaged individually in the kit.

[0738] In some embodiments of any of the embodiments described herein the kit comprises, in addition to the support material formulation, one or more, or two or more Type B modelingmaterial formulations, as described herein in any of the respective embodiments and any combination thereof.

[0739] In exemplary embodiments, the kit comprises a combination of two or more Type B formulations that differ from one another by the presence and / or type of the coloring agent or pigment.

[0740] In exemplary embodiments, the kit comprises two or more of a clear, white, cyan, magenta, and yellow Type B formulations as described herein in any of the respective embodiments.

[0741] In some embodiments of any of the embodiments described herein, the kit comprises, in addition to the support material formulation, one or more, or two or more of Type A modeling material formulations as described herein in any of the respective embodiments and any combination thereof.

[0742] In exemplary embodiments, the kit comprises a combination of two or more Type A formulations that differ from one another by the presence and / or type of the coloring agent or pigment.

[0743] In exemplary embodiments, the kit comprises two or more of a clear, white, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.

[0744] In some embodiments of any of the embodiments described herein, the kit comprises, in addition to the support material formulation, one or more, or two or more of Type A modeling material formulations as described herein in any of the respective embodiments and any combination thereof, and one or more, or two or more of Type B modeling material formulations as described herein in any of the respective embodiments and any combination thereof

[0745] In exemplary embodiments, the kit comprises a clear (transparent) Type B formulation and / or a white Type B formulation, and can optionally further comprise one or more of clear, white, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.

[0746] In exemplary embodiments, the kit comprises a clear (transparent) Type B formulation, and one or more of clear, white, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.

[0747] In exemplary embodiments, the kit comprises a clear (transparent) Type B formulation, and white, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.

[0748] In exemplary embodiments, the kit comprises a white Type B formulation, and one or more of clear, white, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.In exemplary embodiments, the kit comprises a white Type B formulation, and clear, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.

[0749] A kit as described herein is usable for additive manufacturing of a denture structure as described herein, particularly a monolithic denture structure as described herein.

[0750] In some embodiments, each formulation is individually packaged in the kit.

[0751] In exemplary embodiments, the formulations are packaged within the kit in a suitable packaging material, preferably, an impermeable material (e.g., water- and gas-impermeable material), and further preferably an opaque material. In some embodiments, the kit further comprises instructions for use of the formulations in an additive manufacturing process, preferably a 3D inkjet printing process as described herein. The kit may further comprise instructions to use the formulations in the process in accordance with the method as described herein.

[0752] According to some embodiments of the present embodiments, there is provided a set of formulations, which comprises one or more modeling material formulations of Type B and / or one or more modeling material formulations of Type A, and a support material formulation as described herein in any of the respective embodiments. The set of formulations can be packaged within a kit as described herein. The set of formulations is usable in additive manufacturing of a denture structure as described herein in any of the respective embodiments.

[0753] In exemplary embodiments, the set of formulations comprises a combination of two or more Type B formulations that differ from one another by the presence and / or type of the coloring agent or pigment.

[0754] In exemplary embodiments, the set of formulations comprises two or more of a clear, white, cyan, magenta, and yellow Type B formulations as described herein in any of the respective embodiments.

[0755] In some embodiments of any of the embodiments described herein, the set of formulations comprises one or more, or two or more of Type A modeling material formulations as described herein in any of the respective embodiments and any combination thereof.

[0756] In exemplary embodiments, the set of formulations comprises a combination of two or more Type A formulations that differ from one another by the presence and / or type of the coloring agent or pigment.

[0757] In exemplary embodiments, the set of formulations comprises two or more of a clear, white, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.In exemplary embodiments, the set of formulations comprises a clear (transparent) Type B formulation and / or a white Type B formulation, and can optionally further comprise one or more of clear, white, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.

[0758] In exemplary embodiments, the set of formulations comprises a clear (transparent) Type B formulation, and one or more of clear, white, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.

[0759] In exemplary embodiments, the set of formulations comprises a clear (transparent) Type B formulation, and white, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.

[0760] In exemplary embodiments, the set of formulations comprises a white Type B formulation, and one or more of clear, white, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.

[0761] In exemplary embodiments, the set of formulations comprises a white Type B formulation, and clear, cyan, magenta, and yellow Type A formulations as described herein in any of the respective embodiments.

[0762] Object:

[0763] According to an aspect of some embodiments of the present invention, there is provided a three-dimensional object obtained by additive manufacturing as described herein.

[0764] According to some embodiments, the object is a denture structure, as described herein. According to as aspect of some embodiments of the present invention, there is provided a denture structure, as described herein, obtained by additive manufacturing as described herein.

[0765] According to some embodiments, the denture structure is a monolithic structure of a denture base and artificial teeth.

[0766] According to an aspect of some embodiments of the present invention there is provided a three-dimensional printed object which is a monolithic structure of a denture base and artificial teeth.

[0767] According to some embodiments of any of the embodiments described herein, the denture structure features mechanical and physical properties in accordance with the requirements of ISO 20795-1 and ISO 10477 and biocompatibility properties in accordance with the requirements of ISO 10993-1, as is known in the art and as described herein in any of the respective embodiments.

[0768] According to some embodiments of any of the embodiments described herein, the object comprises, in at least a portion thereof, a mixed layer that comprises a hardened support materialand a hardened modeling material, as described herein in any of the respective embodiments. According to some embodiments, the mixed layer comprises a hardened support material formed of a support material formulation as described herein in any of the respective embodiments.

[0769] According to some embodiments, the object comprises, in at least a portion thereof, a hardened model material that is formed of at least one of a Type A formulation and a Type B formulation, as described herein in any of the respective embodiments.

[0770] According to some embodiments of any of the embodiments described herein, the three-dimensional object features in at least portion thereof at least one of:

[0771] Izod impact resistance of at least 100 or at least 120 J / mol;

[0772] Durability in a drop test as described herein of about 100% in the first drop, at least 80 % in the second drop and at least 60 % in the third drop; and

[0773] Mechanical and physical properties in accordance with the requirements of ISO 20795-1.

[0774] System:

[0775] A representative and non-limiting example of a system 110 suitable for AM of an object 112 according to some embodiments of the present invention is illustrated in FIG. 1A. System 110 comprises an additive manufacturing apparatus 114 having a dispensing unit 16 which comprises a plurality of printing heads. Each head preferably comprises one or more arrays of nozzles 122, typically mounted on an orifice plate 121, as illustrated in FIGs. 2A-C described below, through which a liquid building material formulation 124 is dispensed.

[0776] Preferably, but not obligatorily, apparatus 114 is a three-dimensional printing apparatus, in which case the printing heads are printing heads, and the building material formulation is dispensed via inkjet technology. This need not necessarily be the case, since, for some applications, it may not be necessary for the additive manufacturing apparatus to employ three-dimensional printing techniques. Representative examples of additive manufacturing apparatus contemplated according to various exemplary embodiments of the present invention include, without limitation, fused deposition modeling apparatus and fused material formulation deposition apparatus.

[0777] Each printing head is optionally and preferably fed via one or more building material formulation reservoirs which may optionally include a temperature control unit (e.g. , a temperature sensor and / or a heating device), and a material formulation level sensor. To dispense the building material formulation, a voltage signal is applied to the printing heads to selectively deposit droplets of material formulation via the printing head nozzles, for example, as in piezoelectric inkjet printing technology. Another example includes thermal inkjet printing heads. In these types of heads, there are heater elements in thermal contact with the building material formulation, for heating the building material formulation to form gas bubbles therein, upon activation of the heaterelements by a voltage signal. The gas bubbles generate pressures in the building material formulation, causing droplets of building material formulation to be ejected through the nozzles. Piezoelectric and thermal printing heads are known to those skilled in the art of solid freeform fabrication. For any types of inkjet printing heads, the dispensing rate of the head depends on the number of nozzles, the type of nozzles and the applied voltage signal rate (frequency).

[0778] Optionally, the overall number of dispensing nozzles or nozzle arrays is selected such that half of the dispensing nozzles are designated to dispense support material formulation and half of the dispensing nozzles are designated to dispense modeling material formulation, i.e., the number of nozzles jetting modeling material formulations is the same as the number of nozzles jetting support material formulation. In the representative example of FIG. 1A, four printing heads 16a, 16b, 16c and 16d are illustrated. Each of heads 16a, 16b, 16c and 16d has a nozzle array. In this Example, heads 16a and 16b can be designated for modeling material formulation / s and heads 16c and 16d can be designated for support material formulation. Thus, head 16a can dispense one modeling material formulation, head 16b can dispense another modeling material formulation and heads 16c and 16d can both dispense support material formulation. In an alternative embodiment, heads 16c and 16d, for example, may be combined in a single head having two nozzle arrays for depositing support material formulation. In a further alternative embodiment, any one or more of the printing heads may have more than one nozzle arrays for depositing more than one material formulation, e.g., two nozzle arrays for depositing two different modeling material formulations or a modeling material formulation and a support material formulation, each formulation via a different array or number of nozzles.

[0779] Yet it is to be understood that it is not intended to limit the scope of the present invention and that the number of modeling material formulation printing heads (modeling heads) and the number of support material formulation printing heads (support heads) may differ. Generally, the number of arrays of nozzles that dispense modeling material formulation, the number of arrays of nozzles that dispense support material formulation, and the number of nozzles in each respective array are selected such as to provide a predetermined ratio, a, between the maximal dispensing rate of the support material formulation and the maximal dispensing rate of modeling material formulation. The value of the predetermined ratio, a, is preferably selected to ensure that in each formed layer, the height of modeling material formulation equals the height of support material formulation. Typical values for a are from about 0.6 to about 1.5.

[0780] As used herein throughout the term “about” refers to ± 10 %.For example, for a = 1, the overall dispensing rate of support material formulation is generally the same as the overall dispensing rate of the modeling material formulation when all the arrays of nozzles operate.

[0781] Apparatus 114 can comprise, for example, M modeling heads each having m arrays of p nozzles, and S support heads each having s arrays of q nozzles such that Mxmxp = Sxsxq. Each of the Mxm modeling arrays and Sxs support arrays can be manufactured as a separate physical unit, which can be assembled and disassembled from the group of arrays. In this embodiment, each such array optionally and preferably comprises a temperature control unit and a material formulation level sensor of its own, and receives an individually controlled voltage for its operation.

[0782] Apparatus 114 can further comprise a solidifying device 324 which can include any device configured to emit light, heat or the like that may cause the deposited material formulation to harden. For example, solidifying device 324 can comprise one or more radiation sources, which can be, for example, an ultraviolet or visible or infrared lamp, or other sources of electromagnetic radiation, or electron beam source, depending on the modeling material formulation being used. In some embodiments of the present invention, solidifying device 324 serves for curing or solidifying the modeling material formulation.

[0783] In addition to solidifying device 324, apparatus 114 optionally and preferably comprises an additional radiation source 328 for solvent evaporation. Radiation source 328 optionally and preferably generates infrared radiation. In various exemplary embodiments of the invention solidifying device 324 comprises a radiation source generating ultraviolet radiation, and radiation source 328 generates infrared radiation.

[0784] In some embodiments of the present invention apparatus 114 comprises cooling system 134 such as one or more fans or the like

[0785] The printing head(s) and radiation source are preferably mounted in a frame or block 128 which is preferably operative to reciprocally move over a tray 360, which serves as the working surface. In some embodiments of the present invention the radiation sources are mounted in the block such that they follow in the wake of the printing heads to at least partially cure or solidify the material formulations just dispensed by the printing heads. Tray 360 is positioned horizontally. According to the common conventions an X-Y-Z Cartesian coordinate system is selected such that the X-Y plane is parallel to tray 360. Tray 360 is preferably configured to move vertically (along the Z direction), typically downward. In various exemplary embodiments of the invention, apparatus 114 further comprises one or more leveling devices 132, e.g., a roller 326. Leveling device 326 serves to straighten, level and / or establish a thickness of the newly formed layer priorto the formation of the successive layer thereon. Leveling device 326 preferably comprises a waste collection device 136 for collecting the excess material formulation generated during leveling. Waste collection device 136 may comprise any mechanism that delivers the material formulation to a waste tank or waste cartridge.

[0786] In use, the printing heads of unit 16 move in a scanning direction, which is referred to herein as the X direction, and selectively dispense building material formulation in a predetermined configuration in the course of their passage over tray 360. The building material formulation typically comprises one or more types of support material formulation and one or more types of modeling material formulation. The passage of the printing heads of unit 16 is followed by the curing of the modeling material formulation(s) by radiation source 126. In the reverse passage of the heads, back to their starting point for the layer just deposited, an additional dispensing of building material formulation may be carried out, according to predetermined configuration. In the forward and / or reverse passages of the printing heads, the layer thus formed may be straightened by leveling device 326, which preferably follows the path of the printing heads in their forward and / or reverse movement. Once the printing heads return to their starting point along the X direction, they may move to another position along an indexing direction, referred to herein as the Y direction, and continue to build the same layer by reciprocal movement along the X direction. Alternately, the printing heads may move in the Y direction between forward and reverse movements or after more than one forward-reverse movement. The series of scans performed by the printing heads to complete a single layer is referred to herein as a single scan cycle.

[0787] Once the layer is completed, tray 360 is lowered in the Z direction to a predetermined Z level, according to the desired thickness of the layer subsequently to be printed. The procedure is repeated to form three-dimensional object 112 in a layer-wise manner.

[0788] In another embodiment, tray 360 may be displaced in the Z direction between forward and reverse passages of the printing head of unit 16, within the layer. Such Z displacement is carried out in order to cause contact of the leveling device with the surface in one direction and prevent contact in the other direction.

[0789] System 110 optionally and preferably comprises a building material formulation supply system 330 which comprises the building material formulation containers or cartridges and supplies a plurality of building material formulations to fabrication apparatus 114.

[0790] A control unit 152 controls fabrication apparatus 114 and optionally and preferably also supply system 330. Control unit 152 typically includes an electronic circuit configured to perform the controlling operations. Control unit 152 preferably communicates with a data processor 154 which transmits digital data pertaining to fabrication instructions based on computer object data,e.g., a CAD configuration represented on a computer readable medium in a form of a Standard Tessellation Language (STL) format or the like. Typically, control unit 152 controls the voltage applied to each printing head or each nozzle array and the temperature of the building material formulation in the respective printing head or respective nozzle array.

[0791] Once the manufacturing data is loaded to control unit 152 it can operate without user intervention. In some embodiments, control unit 152 receives additional input from the operator, e.g., using data processor 154 or using a user interface 116 communicating with unit 152. User interface 116 can be of any type known in the art, such as, but not limited to, a keyboard, a touch screen and the like. For example, control unit 152 can receive, as additional input, one or more building material formulation types and / or attributes, such as, but not limited to, color, characteristic distortion and / or transition temperature, viscosity, electrical property, magnetic property. Other attributes and groups of attributes are also contemplated.

[0792] Another representative and non-limiting example of a system 10 suitable for AM of an object according to some embodiments of the present invention is illustrated in FIGs. 1B-D. FIGs.

[0793] 1B-D illustrate a top view (FIG. IB), a side view (FIG. 1C) and an isometric view (FIG. ID) of system 10.

[0794] In the present embodiments, system 10 comprises a tray 12 and a plurality of inkjet printing heads 16, each having one or more arrays of nozzles with respective one or more pluralities of separated nozzles. The material used for the three-dimensional printing is supplied to heads 16 by a building material supply system 42. Tray 12 can have a shape of a disk or it can be annular. Nonround shapes are also contemplated, provided they can be rotated about a vertical axis.

[0795] Tray 12 and heads 16 are optionally and preferably mounted such as to allow a relative rotary motion between tray 12 and heads 16. This can be achieved by (i) configuring tray 12 to rotate about a vertical axis 14 relative to heads 16, (ii) configuring heads 16 to rotate about vertical axis 14 relative to tray 12, or (iii) configuring both tray 12 and heads 16 to rotate about vertical axis 14 but at different rotation velocities (e.g., rotation at opposite direction). While some embodiments of system 10 are described below with a particular emphasis to configuration (i) wherein the tray is a rotary tray that is configured to rotate about vertical axis 14 relative to heads 16, it is to be understood that the present application contemplates also configurations (ii) and (iii) for system 10. Any one of the embodiments of system 10 described herein can be adjusted to be applicable to any of configurations (ii) and (iii), and one of ordinary skills in the art, provided with the details described herein, would know how to make such adjustment.

[0796] In the following description, a direction parallel to tray 12 and pointing outwardly from axis 14 is referred to as the radial direction r, a direction parallel to tray 12 and perpendicular tothe radial direction r is referred to herein as the azimuthal direction cp, and a direction perpendicular to tray 12 is referred to herein is the vertical direction z.

[0797] The radial direction r in system 10 enacts the indexing direction y in system 110, and the azimuthal direction cp enacts the scanning direction x in system 110. Therefore, the radial direction is interchangeably referred to herein as the indexing direction, and the azimuthal direction is interchangeably referred to herein as the scanning direction.

[0798] The term “radial position,” as used herein, refers to a position on or above tray 12 at a specific distance from axis 14. When the term is used in connection to a printing head, the term refers to a position of the head which is at specific distance from axis 14. When the term is used in connection to a point on tray 12, the term corresponds to any point that belongs to a locus of points that is a circle whose radius is the specific distance from axis 14 and whose center is at axis 14.

[0799] The term “azimuthal position,” as used herein, refers to a position on or above tray 12 at a specific azimuthal angle relative to a predetermined reference point. Thus, radial position refers to any point that belongs to a locus of points that is a straight line forming the specific azimuthal angle relative to the reference point.

[0800] The term “vertical position,” as used herein, refers to a position over a plane that intersect the vertical axis 14 at a specific point.

[0801] Tray 12 serves as a building platform for three-dimensional printing. The working area on which one or objects are printed is typically, but not necessarily, smaller than the total area of tray 12. In some embodiments of the present invention the working area is annular. The working area is shown at 26. In some embodiments of the present invention tray 12 rotates continuously in the same direction throughout the formation of object, and in some embodiments of the present invention tray reverses the direction of rotation at least once (e.g., in an oscillatory manner) during the formation of the object. Tray 12 is optionally and preferably removable. Removing tray 12 can be for maintenance of system 10, or, if desired, for replacing the tray before printing a new object. In some embodiments of the present invention system 10 is provided with one or more different replacement trays (e.g., a kit of replacement trays), wherein two or more trays are designated for different types of objects (e.g., different weights) different operation modes (e.g., different rotation speeds), etc. The replacement of tray 12 can be manual or automatic, as desired. When automatic replacement is employed, system 10 comprises a tray replacement device 36 configured for removing tray 12 from its position below heads 16 and replacing it by a replacement tray (not shown). In the representative illustration of FIG. IB tray replacement device 36 is illustrated as a drive 38 with a movable arm 40 configured to pull tray 12, but other types of tray replacement devices are also contemplated.Exemplified embodiments for the printing head 16 are illustrated in FIGs. 2A-2C. These embodiments can be employed for any of the AM systems described above, including, without limitation, system 110 and system 10.

[0802] FIGs. 2A-B illustrate a printing head 16 with one (FIG. 2A) and two (FIG. 2B) nozzle arrays 22. The nozzles in the array are preferably aligned linearly, along a straight line. In embodiments in which a particular printing head has two or more linear nozzle arrays, the nozzle arrays are optionally and preferably can be parallel to each other. When a printing head has two or more arrays of nozzles (e.g., FIG. 2B) all arrays of the head can be fed with the same building material formulation, or at least two arrays of the same head can be fed with different building material formulations.

[0803] When a system similar to system 110 is employed, all printing heads 16 are optionally and preferably oriented along the indexing direction with their positions along the scanning direction being offset to one another.

[0804] When a system similar to system 10 is employed, all printing heads 16 are optionally and preferably oriented radially (parallel to the radial direction) with their azimuthal positions being offset to one another. Thus, in these embodiments, the nozzle arrays of different printing heads are not parallel to each other but are rather at an angle to each other, which angle being approximately equal to the azimuthal offset between the respective heads. For example, one head can be oriented radially and positioned at azimuthal position <pi, and another head can be oriented radially and positioned at azimuthal position 92. In this example, the azimuthal offset between the two heads is 91-92, and the angle between the linear nozzle arrays of the two heads is also 91-92.

[0805] In some embodiments, two or more printing heads can be assembled to a block of printing heads, in which case the printing heads of the block are typically parallel to each other. A block including several inkjet printing heads 16a, 16b, 16c is illustrated in FIG. 2C.

[0806] In some embodiments, system 10 comprises a stabilizing structure 30 positioned below heads 16 such that tray 12 is between stabilizing structure 30 and heads 16. Stabilizing structure 30 may serve for preventing or reducing vibrations of tray 12 that may occur while inkjet printing heads 16 operate. In configurations in which printing heads 16 rotate about axis 14, stabilizing structure 30 preferably also rotates such that stabilizing structure 30 is always directly below heads 16 (with tray 12 between heads 16 and tray 12).

[0807] Tray 12 and / or printing heads 16 is optionally and preferably configured to move along the vertical direction z, parallel to vertical axis 14 so as to vary the vertical distance between tray 12 and printing heads 16. In configurations in which the vertical distance is varied by moving tray 12 along the vertical direction, stabilizing structure 30 preferably also moves vertically together withtray 12. In configurations in which the vertical distance is varied by heads 16 along the vertical direction, while maintaining the vertical position of tray 12 fixed, stabilizing structure 30 is also maintained at a fixed vertical position.

[0808] The vertical motion can be established by a vertical drive 28. Once a layer is completed, the vertical distance between tray 12 and heads 16 can be increased (e.g., tray 12 is lowered relative to heads 16) by a predetermined vertical step, according to the desired thickness of the layer subsequently to be printed. The procedure is repeated to form a three-dimensional object in a layerwise manner.

[0809] The operation of inkjet printing heads 16 and optionally and preferably also of one or more other components of system 10, e.g., the motion of tray 12, are controlled by a controller 20. The controller can have an electronic circuit and a non-volatile memory medium readable by the circuit, wherein the memory medium stores program instructions which, when read by the circuit, cause the circuit to perform control operations as further detailed below.

[0810] Controller 20 can also communicate with a host computer 24 which transmits digital data pertaining to fabrication instructions based on computer object data, e.g., in a form of a Standard Tessellation Language (STL) or a StereoLithography Contour (SLC) format, Virtual Reality Modeling Language (VRML), Additive Manufacturing File (AMF) format, Drawing Exchange Format (DXF), Polygon File Format (PLY) or any other format suitable for Computer-Aided Design (CAD). The object data formats are typically structured according to a Cartesian system of coordinates. In these cases, computer 24 preferably executes a procedure for transforming the coordinates of each slice in the computer object data from a Cartesian system of coordinates into a polar system of coordinates. Computer 24 optionally and preferably transmits the fabrication instructions in terms of the transformed system of coordinates. Alternatively, computer 24 can transmit the fabrication instructions in terms of the original system of coordinates as provided by the computer object data, in which case the transformation of coordinates is executed by the circuit of controller 20.

[0811] The transformation of coordinates allows three-dimensional printing over a rotating tray. In non-rotary systems with a stationary tray with the printing heads typically reciprocally move above the stationary tray along straight lines. In such systems, the printing resolution is the same at any point over the tray, provided the dispensing rates of the heads are uniform. In system 10, unlike non-rotary systems, not all the nozzles of the head points cover the same distance over tray 12 during at the same time. The transformation of coordinates is optionally and preferably executed so as to ensure equal amounts of excess material formulation at different radial positions. Representative examples of coordinate transformations according to some embodiments of thepresent invention are provided in FIGs. 3A-B, showing three slices of an object (each slice corresponds to fabrication instructions of a different layer of the objects), where FIG. 3A illustrates a slice in a Cartesian system of coordinates and FIG. 3B illustrates the same slice following an application of a transformation of coordinates procedure to the respective slice.

[0812] Typically, controller 20 controls the voltage applied to the respective component of the system 10 based on the fabrication instructions and based on the stored program instructions as described below.

[0813] Generally, controller 20 controls printing heads 16 to dispense, during the rotation of tray 12, droplets of building material formulation in layers, such as to print a three-dimensional object on tray 12.

[0814] System 10 optionally and preferably comprises one or more radiation sources 18, which can be, for example, an ultraviolet or visible or infrared lamp, or other sources of electromagnetic radiation, or electron beam source, depending on the modeling material formulation being used. Radiation source can include any type of radiation emitting device, including, without limitation, light emitting diode (LED), digital light processing (DLP) system, resistive lamp and the like. Radiation source 18 serves for curing or solidifying the modeling material formulation. In various exemplary embodiments of the invention the operation of radiation source 18 is controlled by controller 20 which may activate and deactivate radiation source 18 and may optionally also control the amount of radiation generated by radiation source 18.

[0815] In some embodiments of the invention, system 10 further comprises one or more leveling devices 32 which can be manufactured as a roller or a blade. Leveling device 32 serves to straighten the newly formed layer prior to the formation of the successive layer thereon. In some embodiments, leveling device 32 has the shape of a conical roller positioned such that its symmetry axis 34 is tilted relative to the surface of tray 12 and its surface is parallel to the surface of the tray. This embodiment is illustrated in the side view of system 10 (FIG. 1C).

[0816] The conical roller can have the shape of a cone or a conical frustum.

[0817] The opening angle of the conical roller is preferably selected such that there is a constant ratio between the radius of the cone at any location along its axis 34 and the distance between that location and axis 14. This embodiment allows roller 32 to efficiently level the layers, since while the roller rotates, any point p on the surface of the roller has a linear velocity which is proportional (e.g., the same) to the linear velocity of the tray at a point vertically beneath point p. In some embodiments, the roller has a shape of a conical frustum having a height h, a radius Ri at its closest distance from axis 14, and a radius R2 at its farthest distance from axis 14, wherein the parametersh, R\ and Rz satisfy the relation R IRz= R-h)lh and wherein R is the farthest distance of the roller from axis 14 (for example, R can be the radius of tray 12).

[0818] The operation of leveling device 32 is optionally and preferably controlled by controller 20 which may activate and deactivate leveling device 32 and may optionally also control its position along a vertical direction (parallel to axis 14) and / or a radial direction (parallel to tray 12 and pointing toward or away from axis 14.

[0819] In some embodiments of the present invention printing heads 16 are configured to reciprocally move relative to tray along the radial direction r. These embodiments are useful when the lengths of the nozzle arrays 22 of heads 16 are shorter than the width along the radial direction of the working area 26 on tray 12. The motion of heads 16 along the radial direction is optionally and preferably controlled by controller 20.

[0820] As used herein the term “about” refers to ± 10 % or ± 5 %.

[0821] The terms "comprises", "comprising", "includes", "including", “having” and their conjugates mean "including but not limited to".

[0822] The term “consisting of’ means “including and limited to”.

[0823] The term "consisting essentially of" means that the composition, method or structure may include additional ingredients, steps and / or parts, but only if the additional ingredients, steps and / or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

[0824] As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

[0825] Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0826] Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging / ranges between” a firstindicate number and a second indicate number and “ranging / ranges from” a first indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween.

[0827] Herein the terms "method" and “process” are used interchangeably and refer to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the chemical, pharmacological, biological, biochemical and medical arts.

[0828] Herein throughout, whenever the phrase “weight percent”, or “% by weight” or “% wt”, is indicated in the context of embodiments of a formulation (e.g., a modeling formulation), it is meant weight percent of the total weight of the respective uncured formulation.

[0829] Herein throughout, an acrylic material is used to collectively describe material featuring one or more acrylate, methacrylate, acrylamide and / or methacrylamide group(s).

[0830] Similarly, an acrylic group is used to collectively describe curable groups which are acrylate, methacrylate, acrylamide and / or methacrylamide group(s), preferably acrylate or methacrylate groups (referred to herein also as (meth)acrylate groups).

[0831] Herein throughout, the term “(meth) acrylic” encompasses acrylic and methacrylic materials.

[0832] Herein throughout, the phrase “linking moiety” or “linking group” describes a group that connects two or more moieties or groups in a compound. A linking moiety is typically derived from a bi- or tri-functional compound, and can be regarded as a bi- or tri-radical moiety, which is connected to two or three other moieties, via two or three atoms thereof, respectively.

[0833] Exemplary linking moieties include a hydrocarbon moiety or chain, optionally interrupted by one or more heteroatoms, as defined herein, and / or any of the chemical groups listed below, when defined as linking groups.

[0834] When a chemical group is referred to herein as “end group” it is to be interpreted as a substituent, which is connected to another group via one atom thereof.

[0835] Herein throughout, the term “hydrocarbon” collectively describes a chemical group composed mainly of carbon and hydrogen atoms. A hydrocarbon can be comprised of alkyl, alkene, alkyne, aryl, and / or cycloalkyl, each can be substituted or unsubstituted, and can be interrupted by one or more heteroatoms. The number of carbon atoms can range from 2 to 30, and is preferably lower, e.g., from 1 to 10, or from 1 to 6, or from 1 to 4. A hydrocarbon can be a linking group or an end group.Bisphenol A is an example of a hydrocarbon comprised of 2 aryl groups and one alkyl group. Dimethylenecyclohexane is an example of a hydrocarbon comprised of 2 alkyl groups and one cycloalkyl group.

[0836] As used herein, the term “amine” describes both a -NR’R” group and a -NR'- group, wherein R’ and R" are each independently hydrogen, alkyl, cycloalkyl, aryl, as these terms are defined hereinbelow.

[0837] The amine group can therefore be a primary amine, where both R’ and R” are hydrogen, a secondary amine, where R’ is hydrogen and R” is alkyl, cycloalkyl or aryl, or a tertiary amine, where each of R’ and R” is independently alkyl, cycloalkyl or aryl.

[0838] Alternatively, R' and R" can each independently be hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, carbonyl, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine and hydrazine.

[0839] The term “amine” is used herein to describe a -NR'R" group in cases where the amine is an end group, as defined hereinunder, and is used herein to describe a -NR'- group in cases where the...

Claims

1. WHAT IS CLAIMED IS:

1. A curable formulation usable in additive manufacturing of a three-dimensional object, the curable formulation comprising:at least one non-curable material (Component L) which comprises at least one polymeric material featuring water solubility (e.g., ECAH) lower than 200, or lower than 100 or lower than 50, or lower than 10, grams / liter (Component L3 and / or L4);at least one mono-functional (meth) acrylate featuring low Tg (Tg lower than 0, or lower than -20 °C) and miscibility in said at least one Component L3 and / or L4 (Component M);at least one multi-functional (meth)acrylate featuring at least 10 ethoxylated groups and / or Tg lower than 0 °C (e.g., Component D2);at least one mono-functional (meth)acrylate (Component E); andoptionally, at least one reactive diluent (Component K).

2. The curable formulation of claim 1, wherein said at least one polymeric material featuring water solubility lower than 200 grams / liter (Component L3 and / or L4) is selected from a polyether and a polyester.

3. The curable formulation of claim 1, wherein said at least one polymeric material featuring water solubility lower than 200 grams / liter (Component L3 and / or L4) is or comprises a polyester.

4. The curable formulation of claim 1, wherein said at least one polymeric material featuring water solubility lower than 200 grams / liter (Component L3 and / or L4) is or comprises a polycaprolactone.

5. The curable formulation of any one of claims 1 to 4, wherein said at least one polymeric material featuring water solubility lower than 200 grams / liter has an average molecular weight (Mn) lower than 1,000 or lower than 500 grams / mol (Component L3).

6. The curable formulation of any one of claims 1 to 5, wherein said at least one polymeric material featuring water solubility lower than 200 grams / liter features low Tg.

7. The curable formulation of any one of claims 1 to 6, wherein a total amount of said at least one non-curable material (Component L) is at least 40 % by weight of the total weight of the formulation.

8. The curable formulation of any one of claims 1 to 6, wherein a total amount of said at least one non-curable material (Component L) ranges from 20 to 60, or from 30 to 60, or from 40 to 60, or from 40 to 50, or from 45 to 55, % by weight of the total weight of the formulation.

9. The curable formulation of any one of claims 1 to 8, wherein said at least one non-curable material (Component L) further comprises at least one of a polymeric material featuring water solubility higher than 200 grams / liter (Component L2) and a non-polymeric polyol (Component LI).

10. The curable formulation of any one of claims 1 to 9, wherein said Component M comprises an oligomeric or polymeric chain that renders it miscible with said non-curable polymeric material Component L3 and / or L4.

11. The curable formulation of any one of claims 1 to 10, wherein said Component M has a molecular weight lower than 1,000, or lower than 600 or lower than 500 grams / mol.

12. The curable formulation of any one of claims 1 to 11, wherein said Component M and said non-curable material (Component L3 and / or Component L4) are selected chemically compatible with one another (e.g., said Component M comprises an oligomeric or polymeric chain featuring repeating backbone units which are the same or are structurally similar).

13. The curable formulation of any one of claims 1 to 12, wherein said Component M comprises an oligomeric or polymeric polyester chain and said non-curable polymeric material is or comprises a polyester.

14. The curable formulation of any one of claims 1 to 13, wherein said Component M is an acrylate featuring said oligomeric or polymeric chain that renders it miscible with said non-curable polymeric material Component L3 and / or L4.

15. The curable formulation of any one of claims 1 to 14, wherein an amount of said Component M ranges from 5 to 15, preferably from 9 to 15, % by weight, of the total weight of the formulation.

16. The curable formulation of any one of claims 1 to 15, wherein said Component E comprises at least one mono-functional acrylate (Component E2 and / or Component E3).

17. The curable formulation of any one of claims 1 to 16, wherein each of said at least one mono-functional (meth)acrylate, preferably at least one mono-functional acrylate, in Component E has a molecular weight of no more than 500, or of from 100 to 500 grams / mol.

18. The curable formulation of any one of claims 1 to 17, wherein said Component E comprises at least one hydrophilic or amphiphilic (meth)acrylate, preferably at least one hydrophilic or amphiphilic acrylate (Component E3).

19. The curable formulation of any one of claims 1 to 18, wherein said Component E comprises at least one mono-functional (meth)acrylate that features Tg higher than 80, or higher than 100 °C.

20. The curable formulation of any one of claims 1 to 19, wherein said Component E comprises at least one alicyclic, optionally hydrophobic, (meth)acrylate, preferably at least one alicyclic, optionally hydrophobic acrylate (Component E2).

21. The curable formulation of any one of claims 1 to 20, wherein said Component E comprises at least one mono-functional (meth) acrylate that features Tg lower than 80, or lower than 50, °C.

22. The curable formulation of any one of claims 1 to 21, wherein said Component E comprises at least one hydrophilic or amphiphilic (meth)acrylate, preferably at least one hydrophilic or amphiphilic acrylate (Component E3) and at least one alicyclic, optionally hydrophobic, (meth)acrylate, preferably at least one alicyclic, optionally hydrophobic acrylate (Component E2).

23. The curable formulation of claim 22, wherein a weight ratio of said Component E2 and said Component E3 ranges from 2:1 to 1:1, or from 1.5:1 to 1:1.

24. The curable formulation of any one of claims 20 to 23, wherein an amount of said Component E2 is at least 10 %, or ranges from 10 to 20, or from 10 to 15, or from 10 to 12, %, by weight of the total weight of the formulation.

25. The curable formulation of any one of claims 18 to 24, wherein an amount of said Component E3 is no more than 10 %, or ranges from 5 to 15, or from 5 to 10, %, by weight of the total weight of the formulation.

26. The curable formulation of any one of claims 1 to 25, wherein a total amount of said Component E ranges from 10 to 40, or from 15 to 40, or from 15 to 30, or from 15 to 25, % by weight of the total weight of the formulation.

27. The curable formulation of any one of claims 1 to 26, wherein said Component D2 comprises a multi-functional ethoxylated aromatic methacrylate featuring at least 10 ethoxylated groups, features, when hardened, Tg lower than 0 °C, and has a molecular weight of at least 1,000 grams / mol.

28. The curable formulation of any one of claims 1 to 27, wherein an amount of said Component D2 ranges from 5 to 15, or from 10 to 15, or from 10 to 12, % by weight of the total weight of the formulation.

29. The curable formulation of any one of claims 1 to 28, further comprising said reactive diluent (Component K).

30. The curable formulation of any one of claims 1 to 29, wherein said Component K comprises a di-functional curable material.

31. The curable formulation of any one of claims 1 to 30, wherein said Component K is or comprises a divinyl ether.

32. The curable formulation of any one of claims 1 to 31, wherein said Component K has a molecular weight lower than 500, or lower than 300, grams / mol.

33. The curable formulation of any one of claims 29 to 32, wherein an amount of said Component K is lower than 10, or lower than 5, %, or ranges from 1 to 10, or from 1 to 8, or from 1 to 5, or from 3 to 8 or from 3 to 5, 5, by weight, of the total weight of the formulation.

34. The curable formulation of any one of claims 1 to 33, further comprising a multifunctional (e.g., tri-functional) (meth)acrylate (Component F).

35. The curable formulation of claim 34, wherein said Component F is or comprises a multi-functional (e.g., tri-functional) acrylate.

36. The curable formulation of claim 34 or 35, wherein said Component F is or comprises a multi-functional (e.g., tri-functional) hydrophilic (meth) acrylate.

37. The curable formulation of any one of claims 34 to 36, wherein said Component F comprises a multi-functional (e.g., tri-functional) cyclic (meth) acrylate (e.g., cyanurate) (Component Fl).

38. The curable formulation of any one of claims 34 to 37, wherein an amount of said Component F (e.g., Component Fl) ranges from 1 to 5, or from 1 to 3, % by weight of the total weight of the formulation.

39. The curable formulation of any one of claims 1 to 38, further comprising a dispersant.

40. The curable formulation of any one of claims 1 to 39, further comprising a photoinitiator.

41. The curable formulation of claim 40, wherein an amount of said photoinitiator ranges from 1 to 3, % by weight of the total weight of the formulation.

42. The curable formulation of any one of claims 1 to 41, usable as a support material formulation in the additive manufacturing of the three-dimensional object.

43. The curable formulation of any one of claims 1 to 42, wherein said three-dimensional object is or comprises a denture structure.

44. The curable formulation of any one of claims 1 to 43, wherein the additive manufacturing of the object is configured to form a hardened mixed layer that comprises a hardened support material formed of the support material formulation and a hardened modeling material formed of at least one modeling material formulation.

45. The curable formulation of any one of claims 1 to 44, wherein the three-dimensional object features in at least portion thereof at least one of:Izod impact resistance of at least 100 or at least 120 J / mol;Durability in a drop test as described herein of about 100% in the first drop, at least 80 % in the second drop and at least 60 % in the third drop; andmechanical and physical properties in accordance with the requirements of ISO 20795-1.

46. A method of additive manufacturing a three-dimensional object, the method comprising dispensing a plurality of layers in a configured pattern corresponding to the shape of the denture object, thereby forming the object,wherein the formation of each of at least a few of said layers comprises dispensing at least one modeling material formulation and at least one support material formulation, and exposing the dispensed formulation to a curing condition to thereby form a hardened modeling material and a hardened support material,wherein said at least one support material formulation is the curable formulation as defined in any one of claims 1 to 45.

47. The method of claim 46, wherein said dispensing is such that at least a portion of an outer layer of the object comprises a hardened mixture of a hardened modeling material formulation and a hardened support material formulation.

48. The method of claim 47, wherein a thickness of said outer layer ranges from 100 to 1000 micrometers or from 100 to 500, or from 200 to 500, micrometers.

49. The method of any one of claims 46 to 48, wherein said dispensing is of a set of at least two modeling material formulations.

50. The method of claim 49, wherein for at least a few of said layers said dispensing is such that forms a core region and at least one outermost encapsulating region at least partially enveloping or surrounding said core region, wherein each of said core region and said encapsulating region is formed of a different modeling material formulation or a different combination of said at least two modeling material formulations.

51. The method of claim 50, wherein for at least a few of said layers said dispensing is such that further forms an inner encapsulating region, at least partially enveloping or surrounding said core region, and optionally one or more intermediate encapsulating regions, at least partially enveloping or surrounding said inner encapsulating region, wherein said outermost encapsulating region at least partially surrounds said the outermost intermediate encapsulating region, wherein each of said core region and said inner encapsulating region, each of said inner encapsulating region and said intermediate encapsulating region, if present, or said outermost encapsulating region, and each of said intermediate encapsulating region, if present, and said outermost encapsulating region is formed of a different modeling material formulation or a different combination of said at least two modeling material formulations.

52. The method of claim 51 , wherein said core region is formed of a Type B formulation as described herein, said inner encapsulating region is formed of a Type A formulation as described herein, said intermediate encapsulating region is formed of said Type B formulation and said outermost encapsulating region is formed of said Type A formulation.

53. The method of any one of claims 49 to 52, wherein the formation of each of at least a few of said layers comprises dispensing at least a first modeling material formulation and a second modeling material formulation, and exposing the dispensed formulations to a curing condition to thereby form a cured modeling material,and is such that forms a core region and at least one outermost encapsulating region at least partially enveloping or surrounding said core region, wherein said core region of formed of said second modeling material formulation or a first combination of said first and said second modeling material formulations, and said encapsulating region is formed of said first modeling materialformulation or a second combination of said first and said second modeling material formulation, said second combination being different from said first combination,wherein said first and said second modeling material formulations are such that:said second formulation or said first combination features, when hardened, impact resistance that is higher by at least 2-folds, or at least 5-folds, or at least 10-folds of an impact resistance of said first formulation or said second combination; and / orsaid first formulation or said second combination features, when hardened, flexural modulus that is higher by at least 2-folds, or at least 5-folds, or at least 10-folds of a flexural modulus of said second formulation or said first combination.

54. The method of any one of claims 46 to 53, wherein said dispensing is such that a hardened support structure is formed, wherein said hardened support structure comprises a hardened bulk embedded with hardened reinforcing elements.

55. A three-dimensional assembly fabricated by an additive manufacturing process, the assembly comprising a hardened object and a hardened sacrificial structure supporting at least one surface of said hardened object, said hardened sacrificial structure comprising a bulk embedded with reinforcing elements arranged in a first region and a second region within said bulk, wherein said second region is farther from said at least one surface than said first region, and wherein at least a majority of reinforcing elements within said second region are mechanically tougher than at least a majority of reinforcing elements within said first region.

56. The assembly according to claim 55, wherein said bulk is washable off said at least one surface by a jet of water.

57. The assembly according to claim 55 or 56, wherein said bulk is peelable off said at least one surface.

58. The assembly according to any one of claims 55 to 57, wherein said bulk is made of a support material and said reinforcing elements are made of modeling materials.

59. The assembly according to any one of claims 55 to 58, wherein a density of said reinforcing elements is higher in said first region than in said second region.

60. The assembly according to any one of claims 55 to 59, wherein said majority of reinforcing elements within said second region are characterized by:a higher elongation at break value than said majority of reinforcing elements within said first region; and / ora higher flexural modulus than said majority of reinforcing elements within said second region; and / ora higher impact resistance than said majority of reinforcing elements within said first region.

61. The assembly according to any one of claims 55 to 60, wherein said majority of reinforcing elements within said second region are larger that said majority of reinforcing elements within said first region, both laterally and vertically.

62. The assembly according to any one of claims 55 to 61, wherein said reinforcing elements are elongated along a building direction of the assembly.

63. The assembly according to claim 62, wherein a length of said reinforcing elements is shorter than a height of said bulk along said building direction.

64. The assembly according to claim 62 or 63, wherein said majority of reinforcing elements within said first region are shaped as pillars and / or as helices.

65. A method of additive manufacturing a three-dimensional assembly, the method comprising forming a plurality of layers, each responding to a pattern of a slice of computer object data describing the assembly, by dispensing and hardening a plurality of building material formulations, wherein for at least one layer of the assembly said forming comprises:forming within said layer of the assembly a layer of an object; andforming within said layer of the assembly a layer of a sacrificial structure at least partially surrounding said layer of said object by dispensing and hardening building material formulations to form a bulk embedded with reinforcing elements arranged in a first region and a second region within said bulk, wherein said second region is farther from said layer of said object than said first region, and wherein said building material formulations for said reinforcing elements are selected such that once said reinforcing elements are hardened, at least a majority of reinforcing elementswithin said second region are mechanically tougher than at least a majority of reinforcing elements within said first region.

66. The method according to claim 65, wherein said building material formulations for said bulk are selected such that once said bulk is hardened said bulk is washable off said at least one surface by a jet of water and / or is peelable off said at least one surface.

67. The method according to any one of claims 65 to 66 wherein said bulk is made of a support material and said reinforcing elements are made of modeling materials.

68. The method according to any one of claims 65 to 67, wherein a density of said reinforcing elements is higher in said first region than in said second region.

69. The method according to any one of claims 65 to 68, wherein said building material formulations for said reinforcing elements are selected such that once said reinforcing elements are hardened, said majority of reinforcing elements within said second region are characterized by:a higher elongation at break value than said majority of reinforcing elements within said first region; and / ora higher flexural modulus than said majority of reinforcing elements within said second region; and / ora higher impact resistance than said majority of reinforcing elements within said first region.

70. The method according to any one of claims 65 to 69, wherein said majority of reinforcing elements within said second region are larger that said majority of reinforcing elements within said first region, both laterally and vertically.

71. The method according to any one of claims 65 to 70, wherein said reinforcing elements are elongated along a building direction of the assembly.

72. The method according to claim 71, wherein a length of said reinforcing elements is shorter than a height of said bulk along said building direction.

73. The method according to claim 71 or 72, wherein said majority of reinforcing elements within said first region are shaped as pillars.

74. The method according to any one of claims 71 to 73, wherein said majority of reinforcing elements within said second region are shaped as helices.

75. A computerized controller for an additive manufacturing system, the computerized controller comprising a circuit configured for operating the additive manufacturing system to execute the method according to any one of claims 65 to 74.

76. An additive manufacturing system comprising a plurality of arrays of nozzles configured to dispense a plurality of building material formulations, a hardening system for hardening said building material formulations once dispensed, and the computerized controller of claim 75.

77. The method or assembly of any one of claims 46 to 76, wherein said object is or comprises a denture structure.

78. The method or assembly of claim 77, wherein said denture structure is selected from a denture base, an artificial tooth, artificial teeth and a monolithic structure of a denture base and artificial teeth.

79. A denture structure obtained by the method of any one of claims 46 to 54 and 65 to 74.

80. The denture structure of claim 79, being a monolithic structure of a denture base and artificial teeth.

81. The denture structure of claim 79 or 80, featuring mechanical and physical properties in accordance with the requirements of ISO 20795-1 and biocompatibility properties in accordance with the requirements of ISO 10993-1.

82. The denture structure of any one of claims 79 to 81, featuring flexural modulus, Flexural strength, Kmax and Wf in accordance with the requirements of ISO 20795-1 and durability in a drop test as described herein.

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