Method and system for fabricating objects with vascular properties - Patents.com

Abstract

To provide a method of additive manufacturing of at least one tubular structure having properties of a blood vessel.SOLUTION: A method comprises: receiving, as input, image data describing a shape of a blood vessel; converting the image data into computer object data; receiving, as input, hardness levels along the blood vessel; accessing a computer readable medium storing a lookup table that has a plurality of entries each corresponding to a different range of hardness levels and being associated with at least one additive manufacturing parameter selected from the group consisting of a building material formulation, a combination of building material formulations, and a wall thickness; extracting additive manufacturing parameters from the lookup table on the basis of the input hardness levels; and operating an additive manufacturing system according to the extracted additive manufacturing parameter to form a plurality of layers in a configured pattern corresponding to the shape of the blood vessel.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] Related Applications This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 538015, filed July 28, 2017, which was filed concurrently with U.S. Provisional Patent Application Nos. 62 / 538003, 62 / 538018, 62 / 538006, and 62 / 538026.

[0002] The contents of the above applications are incorporated herein by reference in their entirety as if fully set forth in their entirety herein.

[0003] Technical Field The present invention, in some embodiments thereof, relates to additive manufacturing, and more particularly, but not exclusively, to methods and systems for additively manufacturing objects having vascular properties. [Background technology]

[0004] Additive manufacturing (AM) is a method in which three-dimensional (3D) objects are generally produced using a computer model of the object. Such methods are used in various fields such as design-related fields for visualization, demonstration and mechanical prototyping purposes, as well as rapid manufacturing (RM). The basic operation of any AM system consists of slicing a three-dimensional computer model into thin cross-sections, converting the results into two-dimensional positional data, and feeding the data to a controller that produces the three-dimensional structure layer by layer.

[0005] One type of AM is the three-dimensional inkjet printing process, in which a build material is ejected from an ejection head with a set of nozzles to deposit layers onto a support structure. Depending on the build material, the layers can then be cured or solidified using a suitable device.

[0006] A variety of three-dimensional inkjet printing techniques exist, such as those disclosed in U.S. Patent Nos. 6,259,962, 6,569,373, 6,658,314, 6,850,334, 7,183,335, 7,209,797, 7,225,045, 7,300,619, 7,479,510, 7,500,846, and 7,962,237, all of which are assigned to the same assignee and whose contents are incorporated herein by reference.

[0007] Some AM processes allow for additive formation of an object using more than one build material. For example, assignee's U.S. Pat. No. 9,031,680 discloses a system including a solid freeform fabrication apparatus having multiple dispensing heads, a build material supply configured to supply multiple build materials to the fabrication apparatus, and a control unit configured to control the fabrication apparatus and the supply. The system has several modes of operation. In one mode, all of the dispensing heads operate during a single build scan cycle of the fabrication apparatus. In another mode, one or more of the dispensing heads are not operated during or part of a single build scan cycle.

[0008] Build materials can include modeling materials and support materials, which form the object and a temporary support structure that supports the object as it is built.

[0009] Build material, which can include one or more materials in one or more formulations, is deposited to produce a desired object.

[0010] Support materials, also known in the art as "support materials" (which may include one or more materials), are used with or without build material elements to support certain areas of an object during build and to ensure proper vertical placement of subsequent object layers. For example, if an object contains overhanging features or shapes, such as curved geometry, negative angles, voids, etc., the object is typically built using adjacent support structures that are used during printing.

[0011] In all cases, a support material is deposited in close proximity to the build material, allowing for the formation of complex object geometries and the filling of object voids.

[0012] In all currently implemented techniques, the deposited support and build materials are typically cured upon exposure to curing conditions (e.g., curing energy) to form the required layer shape. After printing is complete, the support structures are removed to reveal the final shape of the fabricated 3D object.

[0013] When using current commercially available printheads such as inkjet printheads, the support material needs to have a relatively low viscosity (about 10-20 cP) at the operating temperature, i.e., the jetting temperature, so that it can be jetted. Furthermore, the support material needs to harden rapidly to allow the building of subsequent layers. In addition, the hardened support material needs to have sufficient mechanical strength to hold the build material in place and low distortion to avoid geometric defects.

[0014] Known methods for removing support material include mechanical impact (applied by a tool or a water jet) as well as chemical methods such as dissolving in a solvent with or without heating. Mechanical methods are labor intensive and often not suitable for small complex parts.

[0015] To dissolve the support material, the fabricated object is often immersed in water or a solvent capable of dissolving the support material. The solutions utilized to dissolve the support material are also referred to herein and in the industry as "cleaning solutions". However, the support removal process often involves special equipment requiring hazardous materials, manual labor, and / or trained personnel, protective clothing, and expensive waste disposal. In addition, the dissolution process is usually limited by diffusion kinetics and may take a very long time, especially if the support structure is large and bulky. Furthermore, post-processing may be required to remove traces of the "mixed layer" on the object surface. The term "mixed layer" refers to a residual layer of mixed and hardened build material and support material formed at the interface between the two materials on the surface of the object being fabricated due to the build material and support material intermixing with each other at their interface.

[0016] Additionally, due to the presence of temperature sensitive build materials, such as wax and certain flexible materials, methods that require high temperatures during support removal can be problematic. Both mechanical and dissolving methods for removing support materials are particularly problematic when used in an office environment where ease of use, cleanliness, and environmental safety are primary considerations.

[0017] Water-soluble materials for 3D building are described, for example, in U.S. Patent No. 6,228,923, where the water-soluble thermoplastic polymer poly(2-ethyl-2-oxazoline) is taught as a support material in a 3D building process that involves extruding strips of a selected material onto a plate at high temperature and pressure.

[0018] Hydrated support materials containing fusible crystalline hydrates are described in US Pat. No. 7,255,825.

[0019] Formulations suitable for forming hardened support materials in the construction of 3D objects are described in, for example, U.S. Patent Nos. 7,479,510, 7,183,335, and 6,569,373, all of the assignee of the present application. In general, the compositions disclosed in these patents include at least one UV-curable (reactive) component, such as an acrylic component, at least one non-UV-curable component, such as a polyol or glycol component, and a photoinitiator. After irradiation, these compositions provide semi-solid or gel-like materials that can dissolve or swell upon exposure to water, alkaline or acidic solutions, or aqueous detergent solutions.

[0020] In addition to swelling, another property of such support materials would be their ability to disintegrate during exposure to water, alkaline or acidic solutions, or aqueous detergent solutions, since the support materials are made of hydrophilic components. During the swelling process, internal forces cause the hardened support to fracture and break. In addition, the support material can contain substances that release gas bubbles when exposed to water, for example sodium bicarbonate, which converts to CO2 when in contact with an acidic solution. The gas bubbles aid in the process of removing the support from the model.

[0021] Multiple additive manufacturing processes allow for the additive formation of objects using more than one type of build material. For example, applicant's U.S. patent application having Publication No. 2010 / 0191360 discloses a system including a solid freeform fabrication device having multiple dispensing heads, a build material supply device configured to supply multiple build materials to the fabrication device, and a control unit configured to control the fabrication device and the supply device. The system has multiple modes of operation. In one mode, all of the dispensing heads are operative during a single build scan cycle of the fabrication device. In another mode, one or more of the dispensing heads are inoperative during a single build scan cycle or portions thereof.

[0022] In a 3D inkjet printing process, such as Polyjet™ (Stratasys Ltd., Israel), build material is selectively jetted from one or more printheads and deposited onto a build tray in successive layers according to a predetermined configuration as defined by a software file.

[0023] The applicant's U.S. Pat. No. 9,227,365 discloses a method and system for solid freeform fabrication of a sheathed object, the sheathed object being composed of a number of layers, a layered core constituting a core region, and a layered sheath constituting a surrounding region.

[0024] Additive manufacturing processes have been used to form rubber-like materials, such as those used in the PolyJet™ system as described herein. These materials have relatively low viscosities that allow for jetting, for example by inkjet, and have T values ​​below room temperature. g , for example at or below -10° C. The latter can be achieved by incorporating compounds with a relatively low degree of crosslinking and by using monomers and oligomers with inherently flexible molecular structures (e.g., acrylic elastomers).

[0025] An exemplary family of rubber-like materials usable in the PolyJet™ system (sold under the trade name "Tango™" family) provide a variety of elastomeric properties in the resulting cured material, including Shore A hardness, elongation at break, tear resistance, and tensile strength. The softest material in this family has a Shore A hardness of 27.

[0026] Another family of rubber-like materials usable in the PolyJet system (sold under the trade name "Agilus™" family) is described in commonly owned PCT International Application No. IL2017 / 050604 (published as WO2017 / 208238) and uses a curable elastomer compound that includes an elastomeric curable material and silica particles. Summary of the Invention

[0027] In an aspect of some embodiments of the invention there is provided a tubular structure fabricated by additive manufacturing from a non-biological build material compound, the tubular structure including an elongated core, a sheath encapsulating the core, and an intermediate sheath between the core and the sheath, wherein the core, sheath, and intermediate sheath are each made from different materials or different combinations of materials, and wherein the core and intermediate sheath are both sacrificial objects.

[0028] According to some of any of the embodiments of the present invention, the intermediate sheath is made from a hardened support material (eg, material S) and the core is made from a liquid or liquid-like material (eg, material L).

[0029] According to some embodiments of the present invention, the core is made from a hardened support material (eg, material S) and the intermediate sheath is made from a liquid or liquid-like material (eg, material L).

[0030] According to some of the embodiments of the present invention, the liquid or liquid-like material is characterized by at least one of a viscosity of 10,000 centipoise or less; a ratio of shear loss modulus to shear storage modulus greater than 1; a shear modulus of less than 20 kPa; flowability when exposed to a positive pressure of 1 bar or less; shear thinning and / or thixotropic behavior; and thermal thinning behavior.

[0031] According to some of the embodiments of the present invention, the tubular structure has the shape of a blood vessel.

[0032] According to some of the embodiments of the present invention, the sheath is embedded within the support structure.

[0033] According to some of the embodiments of the present invention, the support structure is a sacrificial object.

[0034] In an aspect of some embodiments of the present invention, there is provided an object made by additive manufacturing from a non-biological build material formulation, the object having a shape of an organ and comprising at least one structure having a shape of a blood vessel and at least one structure having a shape of a body structure other than a blood vessel, the structure having the shape of a blood vessel being a tubular structure as specified above and optionally and preferably further detailed herein above.

[0035] According to an aspect of some embodiments of the present invention there is provided an object fabricated by additive manufacturing from a non-biological build material formulation, the object comprising an interconnected network of elongated structures, each having the shape of a blood vessel, and being a tubular structure as set forth above and optionally and preferably further detailed herein above.

[0036] According to some of the embodiments of the present invention, the tubular structure includes a reinforcing element embedded within the sheath.

[0037] According to some of any of the embodiments of the present invention, the reinforcing elements are oriented to provide anisotropic mechanical properties of the sheath.

[0038] According to some of any of the embodiments of the present invention, the reinforcing element includes at least one elongated reinforcing element embedded within the sheath parallel to the longitudinal axis of the sheath.

[0039] According to some of any of the embodiments of the present invention, the reinforcing element includes at least one annular reinforcing element embedded within the sheath along an azimuthal direction that defines the sheath.

[0040] According to some of any of the embodiments of the present invention, the tubular structure includes a liner layer at least partially covering the inner surface of the sheath between the intermediate sheath and the inner surface, and the adhesion between the liner layer and the sheath is stronger than the adhesion between the intermediate sheath and the liner layer.

[0041] According to some of the embodiments of the present invention, the liner layer is harder than the sheath.

[0042] According to some of the embodiments of the present invention, the liner layer has mechanical properties of plaque tissue.

[0043] According to an aspect of some embodiments of the invention, there is provided a method for additively manufacturing at least one tubular structure having characteristics of a blood vessel, the method comprising: receiving as input image data describing a shape of the blood vessel, converting the image data into computer object data, receiving as input stiffness levels along the blood vessel, accessing a computer readable medium storing a look-up table having a plurality of entries, each entry corresponding to a different range of stiffness levels, the plurality of entries being associated with at least one additive manufacturing parameter selected from the group consisting of build material formulations, combinations of build material formulations, and wall thicknesses, extracting additive manufacturing parameters from the look-up table based on the input stiffness levels, and operating an additive manufacturing system according to the extracted additive manufacturing parameters to form a plurality of layers in a construction pattern corresponding to the shape of the blood vessel.

[0044] According to some of any of the embodiments of the present invention, operating an additive manufacturing system includes forming an elongated core, a sheath encapsulating the core and having the shape of a blood vessel, and an intermediate sheath between the core and the sheath, each of the core, sheath, and intermediate sheath being formed by dispensing a different build material formulation or different combinations of build material formulations, and both the core and intermediate sheath being sacrificial objects.

[0045] In an aspect of some embodiments of the invention there is provided a method for additive manufacturing at least one tubular structure having characteristics of a blood vessel, the blood vessel being described by computer object data, the method comprising dispensing a plurality of different build material formulations to form a plurality of layers in a construction pattern forming an elongated core, a sheath encapsulating the core and having a shape of the blood vessel, and an intermediate sheath between the core and the sheath, the core, the sheath, and the intermediate sheath each being formed by dispensing a different build material formulation or a different combination of build material formulations, and both the core and the intermediate sheath being sacrificial objects.

[0046] According to some of any of the embodiments of the present invention, the method includes, after dispensing, subjecting the layer to curing conditions, thereby obtaining a cured material that forms at least the sheath.

[0047] According to some of any of the embodiments of the present invention, the method includes removing the core and the intermediate sheath.

[0048] According to some of any of the embodiments of the present invention, one of the core and intermediate sheath is formed by dispensing a build material formulation that, when exposed to curing conditions, results in a liquid or liquid-like material characterized by at least one of the following: a viscosity of 10,000 centipoise or less; a ratio of shear loss modulus to shear storage modulus greater than 1; a shear modulus of less than 20 kPa; flowability when exposed to a positive pressure of 1 bar or less; shear thinning and / or thixotropic behavior; and thermal thinning behavior. The liquid or liquid-like material described herein is also referred to interchangeably herein as material L.

[0049] According to some of any of the embodiments of the present invention, one of the core and intermediate sheath is formed by dispensing a build material formulation including a non-curable material, which build material formulation results in a liquid or liquid-like material (e.g., material L). Such build formulations are also referred to herein interchangeably as "formulation L" or "liquid formulation."

[0050] According to some of the embodiments of the present invention, the non-curable material includes a poly(alkylene glycol) having a molecular weight of less than 2000 grams / mol.

[0051] According to some of the embodiments of the present invention, a build material formulation that includes a non-curable material (eg, Formulation L) also includes a curable material.

[0052] According to some of the embodiments of the present invention, the curable material includes a monofunctional curable material.

[0053] According to some of the embodiments of the present invention, the curable material is hydrophilic.

[0054] According to some of any of the embodiments of the present invention, the curable material, when cured, provides a shear thinning and / or thixotropic material.

[0055] In accordance with some of any of the embodiments of the present invention, the curable material, when cured, provides a shear thinning material.

[0056] According to some of any of the embodiments of the present invention, the hardenable material, when hardened, provides a water-soluble or water-immiscible material.

[0057] According to some of the embodiments of the present invention, the amount of hardenable material in the build material formulation (eg, Formulation L) ranges from 10 to 25%.

[0058] According to some of any of the embodiments of the present invention, one of the core and intermediate sheath is formed by dispensing a build material formulation that, when cured or exposed to curing conditions, results in a water-soluble or water-miscible material.

[0059] According to some of any of the embodiments of the present invention, one of the core and intermediate sheath is formed by extruding a build material formulation that, when cured or exposed to curing conditions, results in a material selected from a shear thinning material, a thixotropic material, or a thermally thinning material.

[0060] According to some of any of the embodiments of the present invention, the method includes removing the core and the intermediate sheath.

[0061] According to some embodiments of the invention, a method includes generating computer object data describing a cavity in a blood vessel, generating computer object data describing the cavity in a contracted shape, and combining the computer object data describing the blood vessel and the computer object data describing the cavity in a contracted shape to provide combined computer object data describing the blood vessel and a core that is enclosed by a hollow structure such that a gap exists between an inner surface of the blood vessel and an outermost surface of the core.

[0062] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs.Methods and materials similar or equivalent to those described herein can be used in the practice or testing of this invention, but exemplary methods and / or materials are described below.In case of conflict, this patent specification, including definitions, will take precedence.In addition, materials, methods and examples are only illustrative and are not intended to be limiting.

[0063] Implementing the method and / or system of the present invention may involve performing or completing selected tasks manually, automatically, or a combination thereof. Furthermore, the actual device or apparatus of the method and / or system of the present invention may perform any selected steps using hardware, software, or firmware, or a combination thereof using an operating system.

[0064] For example, hardware for performing selected tasks according to embodiments of the present invention can be implemented as a chip or circuit. As software, selected tasks according to embodiments of the present invention can be implemented as software, such as a number of software instructions executed by a computer using a suitable operating system. In an exemplary embodiment of the present invention, one or more tasks according to exemplary embodiments of the methods and / or systems described herein are performed on a data processor, such as a computing platform that executes a number of instructions. Optionally, the data processor includes a volatile memory for storing instructions and / or data, and / or a non-volatile storage device (e.g., a magnetic hard disk and / or a removable recording medium) for storing instructions and / or data. Optionally, a network connection is also further provided. A display and / or a user input device (e.g., a keyboard or mouse) are also optionally further provided. [Brief description of the drawings]

[0065] Certain embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Reference will now be made in particular detail to the drawings, stressing that the details shown are for the purpose of illustrating and discussing embodiments of the invention by way of example only, and in which the description given with reference to the drawings will make apparent to those skilled in the art how to practice the embodiments of the invention.

[0066] [Figure 1A] FIG. 1A is a schematic diagram of an additive manufacturing system according to some embodiments of the present invention. [Figure 1B-1C] 1B-1C are schematic diagrams of additive manufacturing systems according to some embodiments of the present invention. [Figure 1D] FIG. 1D is a schematic diagram of an additive manufacturing system according to some embodiments of the present invention.

[0067] [Figure 2A-2C]2A-2C are schematic diagrams of printheads according to some embodiments of the present invention.

[0068] [Figure 3A-3B] 3A and 3B are schematic diagrams demonstrating coordinate transformation according to some embodiments of the present invention.

[0069] [Figure 4] FIG. 4 is a schematic diagram of a tubular structure according to some embodiments of the present invention.

[0070] [Diagram 5] FIG. 5 is a schematic diagram defining parameters that can be used according to some embodiments of the present invention to characterize the diameter of the core and intermediate sheath according to some embodiments of the present invention.

[0071] [Figure 6] FIG. 6 is a schematic diagram of a tubular structure in an embodiment in which the sheath of the tubular structure is embedded within a support structure.

[0072] [Figure 7A-7C] 7A-C are schematic illustrations of tubular structures according to embodiments of the present invention, in which the tubular structure includes a reinforcing element embedded within its sheath.

[0073] [Figure 8] FIG. 8 is a schematic cutaway view of a tubular structure according to an embodiment of the present invention, in which the tubular structure includes a liner layer at least partially covering the inner surface of the sheath.

[0074] [Figure 9] FIG. 9 is an example of a system for printing 3D parts using GPU material assignment based on distance fields.

[0075] [Figure 10] FIG. 10 is a block diagram of an exemplary computer architecture for the computer of FIG.

[0076] [Figure 11] FIG. 11 is a flow diagram of a method for converting a 3D model into printing instructions to print a 3D part.

[0077] [Figure 12] FIG. 12 is a block diagram of elements used in the method of FIG.

[0078] [Figure 13] FIG. 13 is a perspective view of a portion of a texture and bump component.

[0079] [Figure 14] FIG. 14 is a perspective view of a building space with an orientation component.

[0080] [Figure 15] FIG. 15 shows a method for determining the distance field value.

[0081] [Figure 16] FIG. 16 is a top view of a slice of the construction space illustrating the determination of distance field values.

[0082] [Figure 17] FIG. 17 is a flow diagram of a method for performing the initial step of material selection.

[0083] [Figure 18] FIG. 18 provides a side view of the part showing the different support areas.

[0084] [Figure 19] FIG. 19 provides a method for selecting a material for a voxel when only one part is present.

[0085] [Figure 20] FIG. 20 provides a method for selecting a material for a voxel when there are multiple parts in the build space.

[0086] [Figure 21]FIG. 21 provides a cross-sectional view of parts being built through various embodiments, showing a single part in the build space.

[0087] [Figure 22] FIG. 22 provides a side view of two parts showing the elimination of interferences through the selection of material selection rules for a single part.

[0088] [Figure 23] FIG. 23 shows a combination area where two different modulation functions are combined into one.

[0089] [Figure 24] FIG. 24 shows a bond area where two different materials are bonded together.

[0090] [Diagram 25] FIG. 25 is a schematic diagram of an object additively fabricated from a non-biological build material formulation in accordance with some embodiments of the present invention.

[0091] [Figure 26] FIG. 26 is an image of an interconnected network of elongated structures additively fabricated from a non-biological build material compound according to some embodiments of the present invention.

[0092] [Figure 27] FIG. 27 is a flowchart of a method for additive manufacturing of at least one tubular structure having vascular properties, according to some embodiments of the present invention.

[0093] [Figure 28A] FIG. 28A is a flow chart describing an exemplary procedure that may be used according to some embodiments of the present invention to obtain computer object data. [Figure 28B] FIG. 28B is a flow chart describing an exemplary procedure that may be used according to some embodiments of the present invention to obtain computer object data.

[0094] [Figures 29A-29D] 29A-D show visualized computer object data (FIG. 29A) and images (FIG. 29B-D) of a tube array (FIG. 29A), printed tubes of various compositions (FIG. 29B), straight and curved tube geometries (FIG. 29C), and the Theresa aneurysm (FIG. 29D) obtained in experiments performed according to some embodiments of the present invention.

[0095] [Diagram 30] FIG. 30 shows the results of experiments conducted according to some embodiments of the present invention to investigate the effect of wall thickness on the properties of printed tubes.

[0096] [Diagram 31] FIG. 31 is a graph depicting stress versus strain curves obtained in experiments performed in accordance with some embodiments of the present invention.

[0097] [Fig. 32A-32B] 32A-32B show the results of experiments conducted according to some embodiments of the present invention to investigate the effect of reinforcement on the properties of printed tubes. [Figure 32C] FIG. 32C shows the results of experiments conducted according to some embodiments of the present invention to investigate the effect of reinforcement on the properties of printed tubes.

[0098] [Diagram 33] FIG. 33 is a schematic diagram of an oriented stiffening element used in experiments performed according to some embodiments of the present invention.

[0099] [Fig. 34A-34B] 34A and 34B are schematic diagrams of sample enclosures used in experiments performed according to some embodiments of the present invention.

[0100] [Diagram 35]FIG. 35 shows compliance test results as a function of tube inner diameter obtained in experiments performed according to some embodiments of the present invention.

[0101] [Diagram 36] FIG. 36 shows compliance test results as a function of wall thickness obtained in experiments performed according to some embodiments of the present invention.

[0102] [Figure 37] FIG. 37 shows compliance and time to rupture (TTR) measurements of various printed tubes obtained in experiments performed according to some embodiments of the present invention.

[0103] [Figure 38] FIG. 38 shows the results of experiments conducted according to some embodiments of the present invention to investigate the effect of digital materials used in the printing process on compliance.

[0104] [Figure 39A] FIG. 39A is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. [Figure 39B] FIG. 39B is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. [Figure 39C] FIG. 39C is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. [Figure 39D] FIG. 39D is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. [Figure 39E] FIG. 39E is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. [Figure 39F] FIG. 39F is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. [Figure 39G] FIG. 39G is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. [Fig. 39H] FIG. 39H is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. [Figure 39I] FIG. 39I is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. [Figure 39J] FIG. 39J is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. [Figure 39K] FIG. 39K is a schematic diagram describing an exemplary procedure suitable for generating computer object data describing a hollow object. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0105] The present invention, in some embodiments thereof, relates to additive manufacturing, and more particularly, but not exclusively, to methods and systems for additively manufacturing objects having vascular properties.

[0106] Before describing 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 assembly and construction of the components and / or methods set forth in the following description and / or illustrated in the drawings and / or examples, as the invention is capable of other embodiments or of being practiced or carried out in various ways.

[0107] Before describing 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 assembly and construction of the components and / or methods set forth in the following description and / or illustrated in the drawings and / or examples, as the invention is capable of other embodiments or of being practiced or carried out in various ways.

[0108] The method and system of the present embodiment fabricates a three-dimensional object layer-by-layer based on computer object data by forming multiple layers in a construction pattern corresponding to the shape of the object. The computer object data can be in any known format, including but not limited to Standard Tessellation Language (STL) or Stereo Lithography Contour (SLC) format, Virtual Reality Modeling Language (VRML), Additive Manufacturing File (AMF) format, Drawing Interchange Format (DXF), Polygon File Format (PLY), or any other format suitable for Computer Aided Design (CAD).

[0109] As used herein, the term "object" refers to an entire item or a portion thereof.

[0110] Each layer is formed by an additive manufacturing device that scans a two-dimensional surface to pattern it. During the scan, the device visits multiple target locations on the two-dimensional layer or surface and determines for each target location or group of target locations whether the target location or group of target locations should be occupied by a build material formulation and what type of build material formulation should be delivered thereto. The determination is made according to a computer image of the surface.

[0111] In preferred embodiments of the invention, AM comprises three-dimensional printing, more preferably three-dimensional inkjet printing. In these embodiments, the build material formulation is dispensed from a dispensing head having a set of nozzles, depositing the build material formulation in layers onto a support structure. The AM apparatus thus dispenses the build material formulation at target locations to be occupied and leaves other target locations empty. The apparatus typically includes multiple dispensing heads, each of which can be configured to dispense a different build material formulation. Thus, different target locations can be occupied by different build material formulations.

[0112] Throughout this specification, the phrase "uncured build material" collectively refers to materials dispensed during a fabrication process to form successive layers as described herein. This phrase encompasses uncured materials dispensed to form a printed object (also referred to herein as build material formulations), i.e., one or more uncured modeling material formulations, and uncured materials dispensed to form a support, i.e., an uncured support material formulation.

[0113] Types of build material formulations can be classified into two main categories: build material formulations and support material formulations. Support material formulations can act as a support matrix or structure to support an object or object portion during the fabrication process and / or for other purposes, such as providing a hollow or porous object. The support structure may further include build material formulation elements, such as for additional support strength. Build material formulations that result in a liquid or liquid-like material when exposed to curing conditions can also be classified as support material formulations in accordance with some embodiments of the present invention.

[0114] The phrases "hardened build material" and "solidified build material" or simply "build material", used interchangeably throughout this specification, refer to the portion of the build material that forms the built object after the dispensed build material hardens and the support material is removed, as defined herein. The hardened or solidified build material can be a single hardening material or a mixture of two or more hardening materials, depending on the build material formulation used in the methods described herein. Build material formulations that result in a liquid or liquid-like material when exposed to curing conditions can be classified as build material formulations, according to some embodiments of the present invention.

[0115] Throughout this specification, the expression "build material formulation" (which may also be interchangeably referred to as "build formulation") describes a portion of uncured build material that is dispensed to form a built object, as described herein. A build material formulation is (unless otherwise indicated) an uncured build formulation that forms a final object or portion thereof upon exposure to curing conditions.

[0116] The uncured build material can include one or more build compounds and can be dispensed such that different portions of the built object are made by curing different build compounds and thus are made from different cured build materials or different mixtures of cured build materials.

[0117] Throughout this specification, the phrase "hardened support material," also referred to interchangeably herein as "hardened support material" or simply "support material," refers to the portion of the build material intended to support the fabricated final object during the fabrication process, and which is removed once the process is completed and hardened modeling material is obtained.

[0118] Throughout this specification, the phrase "support material formulation," also referred to interchangeably herein as "support formulation" or simply "formulation," describes the portion of uncured build material that is dispensed to form the support material described herein. The support material formulation is an uncured formulation. If the support material formulation is a curable formulation, it forms a cured support material when exposed to curing conditions.

[0119] The support material, which can be either a liquid or liquid-like material or a hardened, typically gel or gel-like material, is also referred to herein as a sacrificial material, which can be removed after the layer has been jetted and exposed to curing energy to reveal the shape of the final object.

[0120] In this specification and in the industry, the term "gel" refers to a material, often also referred to as a semi-solid material, that generally comprises a three-dimensional solid network, which is generally made of a fibrous structure with chemical or physical connections between them, and a liquid phase engaged within this network. Gels are generally characterized by a solid (e.g., non-fluid) consistency, with a relatively low tensile strength, e.g., a relatively low shear modulus of less than 100 kPa, and a shear loss modulus to shear storage modulus (tan δ, G'' / G) of less than 1. Gels can be characterized as flowable when subjected to a positive pressure of at least 0.5 bar, preferably at least 1 bar, or as non-flowable when subjected to a pressure of less than 1 bar, or less than 0.5 bar, or less than 0.3 bar.

[0121] The gel-like material according to the present embodiments is a generally soft material, which can be a gel or a solid, that has the mechanical and flow properties of a gel.

[0122] Current practice of support materials typically comprises a mixture of curable and non-curable materials, also referred to herein as gel-like or gel support materials.

[0123] Support materials in current practice are typically water-miscible or water-dispersible or water-soluble.

[0124] Throughout this specification, the term "water-miscible" describes a material that is at least partially soluble or dispersible in water (i.e., at least 50% of the molecules transfer into water upon mixing). This term encompasses the terms "water-soluble" and "water-dispersible."

[0125] Throughout this specification, the term "water-soluble" describes a substance which, when mixed with an equal volume or weight of water, forms a homogeneous solution.

[0126] Throughout this specification, the term "water-dispersible" describes a material that forms a uniform dispersion when mixed with an equal volume or weight of water.

[0127] Throughout this specification, the phrase "dissolution rate" refers to the rate at which a substance dissolves in a liquid medium. Dissolution rate, in the context of the present embodiment, can be determined by the time it takes for a certain amount of support material to dissolve. The measured time is referred to herein as the "dissolution time."

[0128] Throughout this specification, when the phrase "weight percentage" is presented in the context of a formulation (e.g., a construction material formulation) embodiment, it means the weight percentage of the total weight of the respective formulation or formulation system described herein.

[0129] The phrase "weight percentage" is also referred to as "% by weight" or "% wt."

[0130] Throughout this specification, some embodiments of the present invention are described in the context of additive manufacturing being 3D inkjet printing, however, other additive manufacturing processes are contemplated, such as, but not limited to, SLA and DLP.

[0131] The uncured build material can include one or more modeling compounds and can be dispensed such that when cured, different portions of the object are made from different cured modeling compounds or different combinations thereof, and thus different cured modeling materials or different mixtures of cured modeling materials.

[0132] The formulations that form the build material (the modeling material formulation and optionally the support material formulation) include one or more hardenable materials that form a hardened (e.g., solidified, solidified) material when exposed to curing conditions (e.g., curing energy).

[0133] Throughout this specification, a "curable material" is a compound (typically a monomeric or oligomeric compound, but optionally a polymeric compound) that solidifies or hardens to form a hardened material when exposed to curing conditions (e.g., curing energy) as described herein. A curable material is generally a polymerizable material that undergoes polymerization and / or crosslinking when exposed to suitable curing conditions, typically an energy source.

[0134] The hardenable materials of this embodiment can harden or solidify (set) while exposed to a hardening condition, which can be a hardening energy and / or another hardening condition, such as contact with a chemical reagent or exposure to the environment.

[0135] As used herein, the terms "hardenable" and "settable" are used interchangeably.

[0136] According to some embodiments of the present invention, the hardenable materials described herein harden upon undergoing polymerization, and are also referred to herein as polymerizable materials.

[0137] Polymerization can be, for example, free radical, cationic, or anionic polymerization, each of which can be induced upon exposure to a curing energy, such as, for example, radiation, heat, or other curing conditions than a curing energy, as described herein.

[0138] In some of any of the embodiments described herein, the curable material is a photopolymerizable material, which polymerizes and / or undergoes crosslinking upon exposure to radiation as described herein, and in some embodiments, the curable material is a UV curable material, which polymerizes and / or undergoes crosslinking upon exposure to UV or UV-vis radiation as described herein.

[0139] In some embodiments, the hardenable materials as described herein are photopolymerizable materials that polymerize via photoinduced free radical polymerization. Alternatively, the hardenable materials are photopolymerizable materials that polymerize by photoinduced cationic polymerization.

[0140] In some of the embodiments described herein, the hardenable material can be a monomer, oligomer, or short chain polymer, each of which can be polymerized and / or crosslinked as described herein.

[0141] In some of any of the embodiments described herein, when the curable material is exposed to curing conditions (e.g., radiation), it hardens (solidifies, hardens) by any one or a combination of chain extension and crosslinking.

[0142] In some of the embodiments described herein, the curable material is a monomer or mixture of monomers that can undergo a polymerization reaction to form a polymerized material when exposed to curing conditions (e.g., curing energy) in which a polymerization reaction occurs. Such curable materials are also referred to herein as monomeric curable materials.

[0143] In some of the embodiments described herein, the curable material is an oligomer or mixture of oligomers that can undergo a polymerization reaction to form a polymerized material when exposed to curing conditions (e.g., curing energy) in which a polymerization reaction occurs. Such curable materials are also referred to herein as oligomeric curable materials.

[0144] In some of any of the embodiments described herein, the curable material, whether monomeric or oligomeric, can be a monofunctional curable material or a multifunctional curable material.

[0145] As used herein, a monofunctional curable material contains one functional group that can undergo polymerization upon exposure to curing conditions, such as curing energy (eg, radiation).

[0146] A multifunctional curable material comprises two or more, e.g., two, three, four or more, functional groups that can undergo polymerization when exposed to curing energy. A multifunctional curable material can be, for example, a difunctional, trifunctional, or tetrafunctional curable material, which comprises two, three, or four groups, respectively, that can undergo polymerization. The two or more functional groups in a multifunctional curable material are generally linked to each other by a linking moiety, as defined herein. When the linking moiety is an oligomeric or polymeric moiety, the multifunctional group is an oligomeric or polymeric multifunctional curable material. A multifunctional curable material can undergo polymerization when exposed to curing energy and / or can act as a crosslinker.

[0147] The final three-dimensional object is made from the build material formulation, or a combination or modification (e.g., after curing) of the build material formulation and the support material formulation, all of which are well known to those skilled in the art of solid freeform fabrication.

[0148] In some exemplary embodiments of the invention, an object is manufactured by dispensing two or more different build material formulations, each formulation being dispensed from a different dispensing head of the AM. The build material formulations are optionally and preferably deposited in layers during the same pass of the print head. The formulations and combinations of formulations within the layers are selected according to the desired properties of the object.

[0149] A representative, non-limiting example of a system 110 suitable for AM of an object 112, according to some embodiments of the present invention, is shown in Figure 1A. The system 110 comprises an additive manufacturing apparatus 114 having a dispensing unit 16 that includes multiple dispensing heads. Each head preferably includes an array of one or more nozzles 122 through which an uncured liquid build material formulation 124 is dispensed, as shown in Figures 2A-2C described below.

[0150] Preferably, but not necessarily, the device 114 is a three-dimensional printing device. In that case, the dispensing head is a print head and the build material formulation is dispensed by inkjet technology. This is not necessarily the case, as in some applications the additive manufacturing device may not need to employ three-dimensional printing technology. Representative examples of additive manufacturing devices envisioned in accordance with various exemplary embodiments of the present invention include, but are not limited to, fused deposition modeling devices and fused material formulation deposition devices.

[0151] Each dispensing head is optionally and preferably fed via a build material formulation reservoir, which may optionally include a temperature control unit (e.g., a temperature sensor and / or a heating device) and a material level sensor. To dispense the build material formulation, a voltage signal is applied to the dispensing head such that droplets of the material formulation are selectively deposited through the dispensing head nozzles, as in, for example, piezoelectric inkjet printing technology. The dispensing rate of each head depends on the number of nozzles, the type of nozzle, and the signal rate (frequency) of the applied voltage. Such dispensing heads are known to those skilled in the art of solid freeform fabrication.

[0152] The total number of discharge nozzles or nozzle arrays is preferably, but not necessarily, selected such that half of the discharge nozzles are designed to discharge the support material formulation and half of the discharge nozzles are designed to discharge the build material formulation, i.e., the number of nozzles that discharge the build material formulation is the same as the number of nozzles that discharge the support material formulation. Four discharge heads 16a, 16b, 16c, and 16d are shown in the representative embodiment of FIG. 1A. Each of the heads 16a, 16b, 16c, and 16d has a nozzle array. In this embodiment, the heads 16a and 16b can be designed for the build material formulation, and the heads 16c and 16d can be designed for the support material formulation. Thus, the head 16a can discharge a first build material formulation, the head 16b can discharge a second build material formulation, and both the heads 16c and 16d can discharge the support material formulation. Alternatively, the head 16b can discharge the support material formulation. In an alternative embodiment, for example, heads 16c and 16d may be combined into a single head having two nozzle arrays for dispensing the support material formulation.

[0153] Nonetheless, it is not intended to limit the scope of the invention, and it should be understood that the number of build material formulation dispensing heads (build heads) and the number of support material formulation dispensing heads (support heads) may vary. In general, the number of build heads, the number of support heads, and the number of nozzles in each head or head array are selected to provide a predetermined ratio α between the maximum dispensing rate of the support material formulation and the maximum dispensing rate of the build material formulation. The value of the predetermined ratio α is preferably selected to ensure that the height of the build material formulation in each layer formed is equal to the height of the support material formulation. Typical values ​​of α are about 0.6 to about 1.5.

[0154] For example, if α=1, then when all build and support heads are active, the total dispensing rate of the support material formulation is approximately the same as the total dispensing rate of the build material formulation.

[0155] In a preferred embodiment, there are M build heads, each with m arrays of p nozzles, and S support heads, each with s arrays of q nozzles, so M×m×p=S×s×q. Each of the M×m build arrays and the S×s support arrays can be manufactured as separate physical units that can be assembled into and disassembled from arrays. In this embodiment, each such array optionally and preferably includes its own temperature control unit and material formulation level sensor, and receives an individually controlled voltage for its operation.

[0156] The apparatus 114 can further include a solidification device 324, which can include any device configured to emit light, heat, etc., to harden the deposited material formulation. For example, the solidification device 324 can include one or more radiation sources, which can be, for example, ultraviolet or visible or infrared lamps, or other electromagnetic radiation sources, or electron beam sources, depending on the build material formulation used. In some embodiments of the invention, the solidification device 324 serves to harden or solidify the build material formulation.

[0157] In some embodiments of the invention, the device 114 includes a cooling system 134, such as one or more fans.

[0158] The dispensing head and the radiation source are preferably mounted on a frame or block 128 that preferably operates to reciprocate over a tray 360 that serves as a working surface. In some embodiments of the invention, the radiation source is mounted on the block such that it follows behind the dispensing head to at least partially harden or solidify the material formulation that has just been dispensed by the dispensing head. The tray 360 is positioned horizontally. According to common convention, an X-Y-Z Cartesian coordinate system is chosen such that the X-Y plane is parallel to the tray 360. The tray 360 is preferably configured to move vertically (along the Z direction), typically downwards. In various exemplary embodiments of the invention, the apparatus 114 further comprises one or more leveling devices 132, e.g., rollers 326. The leveling devices 326 serve to straighten, level and / or establish the thickness of the newly formed layer before the next layer is formed thereon. The leveling device 326 preferably includes a waste collection device 136 to collect excess material formulation generated during leveling. The waste collection system 136 may include any mechanism for delivering a material mix to a waste tank or waste cartridge. Waste collection is described in more detail below.

[0159] In use, the dispensing heads of the units 16 move in a scanning direction, referred to herein as the X-direction, to selectively dispense build material formulations in a predetermined configuration as they pass over the tray 360. The build material typically comprises one or more support material formulations and one or more build material formulations. The passage of the dispensing heads of the units 16 is followed by curing of the build material formulations by the radiation source 126. During a reverse pass of the head back to the starting point of the head for the just deposited layer, additional dispensing of the build material formulations may be performed according to a predetermined configuration. During a forward or reverse pass of the dispensing head, the layers thus formed are straightened by a leveling device 326, which preferably follows the path of the dispensing head during the forward and / or reverse movement of the leveling device. When the dispensing heads return to their starting points along the X-direction, they may move to another position along an indexing direction, referred to herein as the Y-direction, to continue building the same layer by a reciprocating motion along the X-direction. Alternatively, the dispensing head may move in the Y direction between the forward and reverse moves, or after two or more forward-reverse moves. The series of scans performed by the dispensing head to complete a single layer is referred to herein as a single scan cycle.

[0160] Once a layer is completed, the tray 360 is lowered in the Z direction to a predetermined Z level depending on the desired thickness of the next layer to be printed. This procedure is repeated as the three-dimensional object 112 is built layer by layer.

[0161] In another embodiment, the tray 360 may be displaced in the Z direction within the layer during the forward and reverse passes of the dispensing head of the unit 16. Such Z displacement is performed to allow the leveling device to contact the surface in one direction and prevent contact in the other direction.

[0162] The system 110 optionally and preferably includes a build material formulation supply system 330 that includes build material formulation containers or cartridges and supplies a plurality of build material formulations to the manufacturing device 114 .

[0163] The control unit 340 controls the manufacturing equipment 114 and optionally and preferably also the supply system 330. The control unit 340 typically includes electronic circuitry configured to perform control operations. The control unit 340 preferably communicates with the data processor 154, which transmits digital data regarding fabrication instructions based on computer object data, e.g., CAD configurations represented on a computer-readable medium in a form such as Standard Tessellation Language (STL) format. Typically, the control unit 340 controls the voltages applied to each ejection head or nozzle array, and the temperature of the build material formulation of each print head.

[0164] Once the manufacturing data is loaded into the control unit 340, the control unit can operate without user intervention. In some embodiments, the control unit 340 receives additional input from an operator, for example, using the data processor 154 or using a user interface 116 in communication with the unit 340. The user interface 116 can be of any type known in the art, for example, but not limited to, a keyboard, a touch screen, etc. For example, the control unit 340 can receive as additional input one or more build material formulation types and / or attributes, for example, but not limited to, color, characteristic distortion, and / or transition temperature, viscosity, electrical properties, magnetic properties, etc. Other attributes and groups of attributes are also contemplated.

[0165] Another representative, non-limiting example of a system 10 suitable for AM of an object according to some embodiments of the present invention is shown in Figures 1B-1D, which show a top view (Figure 1B), a side view (Figure 1C), and an isometric view (Figure 1D) of the system 10.

[0166] In this embodiment, system 10 includes a tray 12 and a number of inkjet printheads 16, each having a number of separate nozzles. Tray 12 may have the shape of a disk or may be annular. Non-circular shapes are contemplated, provided they can be rotated about a vertical axis.

[0167] The tray 12 and head 16 are optionally and preferably mounted to allow relative rotational movement between the tray 12 and head 16. This can be accomplished by (i) configuring the tray such that the tray 12 rotates about a vertical axis 14 relative to the head 16, (ii) configuring the head such that the head 16 rotates about a vertical axis 14 relative to the tray 12, or (iii) configuring both the tray 12 and head 16 to rotate about a vertical axis 14, but at different rotational speeds (e.g., in opposite directions). The following embodiments will be described with particular emphasis on configuration (i), in which the tray is a rotating tray configured to rotate about a vertical axis 14 relative to the head 16, but it should be understood that configurations (ii) and (iii) are also contemplated by the present application. Any of the embodiments described herein can be adapted to apply to either of configurations (ii) and (iii), and one of ordinary skill in the art will know how to make such an adjustment given the details described herein.

[0168] In the following description, the direction parallel to the tray 12 and outward from the axis 14 is referred to as the radial direction r, the direction parallel to the tray 12 and perpendicular to the radial direction r is referred to herein as the azimuthal direction φ, and the direction perpendicular to the tray 12 is referred to herein as the vertical direction z.

[0169] As used herein, the term "radial position" refers to a position on or above tray 12 that is a particular distance from axis 14. When the term is used in relation to a print head, the term refers to a position of the head that is a particular distance from axis 14. When the term is used in relation to a point on tray 12, the term corresponds to any point belonging to a locus of points whose radius is a particular distance from axis 14 and describes a circle whose center is on axis 14.

[0170] As used herein, the term "azimuth position" refers to a position on or above tray 12 that is at a particular azimuth angle relative to a given reference point. A radial position thus refers to any point belonging to a locus of points that describes a line that forms a particular azimuth angle relative to a reference point.

[0171] As used herein, the term "vertical position" refers to the position of the entire plane that intersects the vertical axis 14 at a particular point.

[0172] The tray 12 serves as a support structure for three-dimensional printing. The working area on which one or more objects are printed is typically, but not necessarily, smaller than the total area of ​​the tray 12. In some embodiments of the present invention, the working area is annular. The working area is indicated by the reference numeral 26. In some embodiments of the present invention, the tray 12 rotates continuously in the same direction throughout the formation of the object, and in some embodiments of the present invention, the tray reverses its direction of rotation (e.g., to oscillate) at least once during the formation of the object. The tray 12 is optionally and preferably removable. Removal of the tray 12 may be performed for maintenance of the system 10, or, if desired, to replace the tray before printing a new object. In some embodiments of the present invention, the system 10 is provided with one or more different replacement trays (e.g., a kit of replacement trays), where two or more trays are designed for different types of objects (e.g., different weights), different modes of operation (e.g., different rotation speeds), etc. Replacement of the tray 12 may be manual or automatic, as desired. When automated changing is employed, system 10 includes a tray changer 36 configured to remove tray 12 from its position beneath head 16 and replace it with a replacement tray (not shown). In the representative diagram of Figure 1B, tray changer 36 is shown as a drive 38 having a movable arm 40 configured to pull tray 12, although other types of tray changers are contemplated.

[0173] Exemplary embodiments of print head 16 are illustrated in Figures 2A-2C. These embodiments may be employed in any of the AM systems described above, including but not limited to system 110 and system 10.

[0174] 2A-2B show a print head 16 with one (FIG. 2A) and two (FIG. 2B) nozzle arrays 22. The nozzles in the arrays are preferably aligned linearly along a straight line. In embodiments where a particular print head has more than one linear nozzle array, the nozzle arrays can optionally and preferably be parallel to one another.

[0175] When a system similar to system 110 is used, all print heads 16 are optionally and preferably offset in their positions along the scan direction relative to one another and oriented along an index direction.

[0176] When a system similar to system 10 is used, all print heads 16 are optionally and preferably oriented radially (parallel to the radial direction) with their azimuthal positions offset from one another. Thus, in these embodiments, the nozzle arrays of the different print heads are not parallel to one another, but rather at an angle to one another, the angle being approximately equal to the azimuthal offset between the respective heads. For example, one head may be oriented radially and located at an azimuthal position φ1, and another head may be oriented radially and located at an azimuthal position φ2. In this example, the azimuthal offset between the two heads is φ1-φ2, and the angle between the linear nozzle arrays of the two heads is also φ1-φ2.

[0177] In some embodiments, two or more print heads can be assembled into a block of print heads, where the print heads in the block are generally parallel to one another. A block including several inkjet print heads 16a, 16b, 16c is shown in FIG. 2C.

[0178] In some embodiments, system 10 includes a support structure 30 that is positioned below head 16 such that tray 12 is between support structure 30 and head 16. Support structure 30 acts to prevent or reduce vibrations of tray 12 that may occur while inkjet print head 16 is operating. In configurations in which print head 16 rotates about axis 14, support structure 30 preferably also rotates (together with tray 12, between head 16 and tray 12) so that support structure 30 is always directly below head 16.

[0179] The tray 12 and / or print head 16 are optionally and preferably configured to move parallel to the vertical axis 14 along a vertical direction z such that the vertical distance between the tray 12 and print head 16 varies. In configurations in which the vertical distance is varied by moving the tray 12 along the vertical direction, the support structure 30 preferably also moves vertically with the tray 12. In configurations in which the vertical position of the tray 12 remains fixed and the vertical distance is varied along the vertical direction by the head 16, the support structure 30 is also maintained in a fixed vertical position.

[0180] The vertical movement can be established by a vertical drive 28. Once a layer is completed, the vertical distance between the tray 12 and the head 16 can be increased (e.g., by lowering the tray 12 relative to the head 16) by a predetermined vertical distance depending on the desired thickness of the next layer to be printed. This procedure is repeated as the three-dimensional object 112 is built layer by layer.

[0181] The orientation of inkjet print head 16, and optionally and preferably, the orientation of one or more other components of system 10, such as the orientation of movement of tray 12, are also controlled by controller 20. The controller can include electronic circuitry and a non-volatile storage medium readable by the circuitry that stores program instructions that, when read by the circuitry, cause the circuitry to perform control operations as described in further detail below.

[0182] The controller 20 can also communicate with a host computer 24 that transmits digital data relating to fabrication instructions based on computer object data in the form of, for example, Standard Tessellation Language (STL) or 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 format is typically structured according to a Cartesian coordinate system. In such a case, the computer 24 preferably performs a procedure for converting the coordinates of each slice in the computer object data from the Cartesian coordinate system to a polar coordinate system. The computer 24 optionally and preferably transmits the fabrication instructions in the transformed coordinate system. Alternatively, the computer 24 can transmit the fabrication instructions in the original coordinate system provided by the computer object data, in which case the conversion of the coordinates is performed by the circuitry of the controller 20.

[0183] The transformation of coordinates enables three-dimensional printing on a rotating tray. In conventional three-dimensional printing, the print head moves back and forth along a straight line over a stationary tray. In such conventional systems, the print resolution is the same at any point on the tray, assuming the head's discharge rate is uniform. Unlike conventional three-dimensional printing, not all nozzles of the head point cover the same distance across the tray 12 at the same time. The transformation of coordinates is optionally and preferably performed to ensure equal amounts of excess material compound at different radial positions. A representative example of the coordinate transformation according to some embodiments of the present invention is presented in Figures 3A-3B, which show three slices of an object (each slice corresponds to a fabrication instruction for a different layer of the object). Figure 3A shows the slices in a Cartesian coordinate system, and Figure 3B shows the same slices after a coordinate transformation procedure has been applied to each slice.

[0184] Generally, controller 20 controls the voltages applied to each component of system 10 based on manufacturing instructions and based on stored program instructions described below.

[0185] In general, controller 20 controls print head 16 to eject droplets of build material formulation in layers to print a three-dimensional object on tray 12 while tray 12 rotates.

[0186] System 10 optionally and preferably includes one or more radiation sources 18, which may be, for example, ultraviolet or visible or infrared lamps, or other electromagnetic radiation sources, or electron beam sources, depending on the build material formulation used. The radiation sources may include any type of radiation emitting element, including, but not limited to, light emitting diodes (LEDs), digital light processing (DLP) systems, resistive lamps, and the like. Radiation sources 18 serve to cure or solidify the build material formulation. In various exemplary embodiments of the invention, operation of radiation sources 18 is controlled by a controller 20, which may activate or deactivate radiation sources 18, and optionally control the amount of radiation generated by radiation sources 18.

[0187] In some embodiments of the present invention, the system 10 further comprises one or more leveling devices 32, which can be manufactured as rollers or blades. The leveling devices 32 serve to straighten a newly formed layer before the next layer is formed on it. In some embodiments, the leveling devices 32 have the shape of a conical roller, arranged such that its axis of symmetry 34 is inclined with respect to the surface of the tray 12 and its surface is parallel to the surface of the tray. This embodiment is shown in a side view of the system 10 (FIG. 1C).

[0188] The conical roller may have the shape of a cone or a frustum of a cone.

[0189] The opening angle of the conical roller is preferably selected so that the ratio of the radius of the cone at any location along its axis 34 to the distance between that location and the axis 14 is constant. This embodiment allows the roller 32 to efficiently level the layer, since as the roller rotates, any point p on the surface of the roller has a linear velocity proportional (e.g., the same) as the linear velocity of the tray at a point located vertically below point p. In some embodiments, the roller has a truncated cone shape with height h, radius R1 at the closest distance from the axis 14, and radius R2 at the furthest distance from the axis 14, where the parameters h, R1, and R2 satisfy the relationship R1 / R2=(Rh) / h, where R is the furthest distance of the roller from the axis 14 (e.g., R can be the radius of the tray 12).

[0190] The operation of the leveling device 32 is optionally and preferably controlled by the controller 20. The controller can activate and deactivate the leveling device 32, and optionally also control its position along the vertical direction (parallel to the axis 14) and / or along the radial direction (parallel to the tray 12, toward or away from the axis 14).

[0191] In some embodiments of the present invention, system 10 includes a cooling system (not shown, see FIG. 1A), such as one or more fans.

[0192] In some embodiments of the invention, print head 16 is configured to reciprocate relative to the tray along a radial direction r. These embodiments are useful when the length of nozzle array 22 of head 16 is less than the radial width of working area 26 on tray 12. Movement of head 16 along the radial direction is optionally and preferably controlled by controller 20.

[0193] Some embodiments contemplate fabricating an object by dispensing different build material formulations from different dispensing heads. These embodiments provide, among other things, the ability to select material formulations from a given number of material formulations and define the desired combination of selected material formulations and their properties. According to the present embodiment, the spatial location of deposition of each build material formulation in a layer is defined to achieve the occupation of different three-dimensional spatial locations by different build material formulations or the occupation of approximately the same three-dimensional location or adjacent three-dimensional locations by two or more different material formulations, allowing spatial combination after deposition of the material formulations in the layer, thereby forming a composite material formulation at each location(s).

[0194] Any post-deposition combination or mixing of build material formulations is contemplated. For example, after a particular build material formulation is dispensed, it may maintain its original properties. However, when dispensed simultaneously with another build material formulation or other dispensed material formulations at the same or nearby locations, a composite material formulation is formed that has different properties than the dispensed build material formulation.

[0195] The present embodiments thus enable the deposition of a wide range of material formulation combinations, and enable the fabrication of objects where different portions of the object may be constructed from multiple different material formulation combinations, depending on the properties desired to characterize each portion of the object.

[0196] Further details regarding the principles and operation of an AM system suitable for the present embodiment can be found in U.S. Published Application No. 20100191360, the contents of which are incorporated herein by reference.

[0197] 4 is a schematic diagram of a tubular structure 200 according to some embodiments of the present invention. The tubular structure 200 is preferably fabricated by AM (e.g., by operating one of the AM systems 10 and 110) from a non-biological build material compound. In various exemplary embodiments of the present invention, the tubular structure 200 has a shape of a blood vessel, and optionally and preferably also has mechanical properties of a blood vessel. The tubular structure 200 can include an elongated core 202 and a solid sheath 204 that encapsulates the core 202.

[0198] In some embodiments, the smallest diameter (e.g., outer diameter) of sheath 204 is from about 0.1 mm to about 5 cm, or from about 1 mm to about 3 cm. In some embodiments, the wall thickness of sheath 204 is from about 0.1 mm to about 5 mm, or from about 0.1 mm to about 3 mm.

[0199] Core 202 is optionally or preferably a sacrificial object. In some optional and preferred embodiments, tubular structure 200 also includes an intermediate sheath 206 between core 202 and sheath 204. The intermediate sheath is also optionally and preferably a sacrificial object. Core 202, sheath 204, and intermediate sheath 206 are each optionally and preferably made from different materials or different combinations of materials.

[0200] In some embodiments of the invention, the core 202 is made of a liquid or liquid-like material as defined herein (e.g. material L). When the core 202 is made of a liquid or liquid-like material and the tubular structure 200 also includes an intermediate sheath 206, the intermediate sheath 206 is preferably made of a gel or gel-like material as described herein (e.g. material S). The inventors have discovered that such an intermediate sheath 206 significantly reduces the likelihood of inward collapse. The intermediate sheath 206 acts as a buffer layer between the core 202 and the outer sheath 204, and optionally and preferably prevents contact between the liquid or liquid-like core and the solid sheath. The liquid or liquid-like core can be removed, for example, by applying pressure to the interior of the structure 200. The pressure is preferably 1 bar or less, or 0.5 bar or less, or 0.3 bar or less, and can be, for example, 0.1 bar, 0.2 bar, or 0.3 bar.

[0201] After removing the core 202, the intermediate sheath 206, if present, typically remains in the tubular structure 200. The intermediate sheath 206 can then be removed by circulating a solution capable of dissolving or dispersing the intermediate sheath 206 through the tubular structure 200. For example, the intermediate sheath 206 can be made from a hardened support material (e.g., material S) that is water-soluble or water-miscible, where the intermediate sheath 206 can be removed by contacting it with an aqueous solution in which it is soluble or dispersible (e.g., a cleaning solution; an aqueous solution containing an alkaline substance in an amount of about 1% to about 3% by weight of the solution). In some embodiments, the intermediate sheath 206 is removed upon application of physical means such as air or liquid jets at a pressure higher than 0.5 bar or higher than 1 bar. This pressure is optionally and preferably higher than the pressure used to remove the core 202.

[0202] The dimensions of the core 202 and intermediate sheath 206 are optionally and preferably selected based on the desired inner diameter of the sheath 204 of the tubular structure 200. Figure 5 illustrates parameters that may be used in accordance with some embodiments of the present invention to characterize the dimensions of the core 202 and intermediate sheath 206. Shown is the maximum core diameter parameter L MAX , the minimum thickness parameter of the intermediate layer c MIN , and two threshold diameter parameters D1 and D2.

[0203] L MAX is typically, but not necessarily, less than 10 mm; MIN is typically, but not necessarily, less than 20 mm and more than 0.4 mm, or less than 2 mm and more than 0.4 mm. The thresholds D1 and D2 are optionally and preferably MAX and c MIN and the geometry of the vessel. For example, D1 is calculated based on L MAX and c MIN As a linear combination of, for example, D1=L MAX +2*K1*c MINwhere K1 is greater than 1 and is typically about 2 to about 5. D2 is L max As a linear function of, for example, D2=L MAX *K2, where K2 is typically between 0.8 and about 1.2. In some embodiments of the invention, the ratio of coefficients K2 and K1 is 4c MIN Less than or equal to 3c MIN Less than or equal to 2c MIN is less than.

[0204] In some embodiments of the present invention, in regions of the tubular structure 200 where the inner diameter of the outer sheath 204 is equal to or greater than the first threshold diameter D1, the diameter of the core 202 preferably has a substantially constant diameter, e.g., L MAX In some embodiments of the present invention, in regions of the tubular structure 200 where the inner diameter of the outer sheath 204 is equal to or smaller than the second threshold diameter D2, the thickness of the intermediate sheath 206 (along a radial direction perpendicular to the longitudinal axis of the tube) is preferably substantially constant, e.g., c MIN In some embodiments of the present invention, in the region of the tubular structure where the inner diameter of the outer sheath 204 is between the second threshold diameter D2 and the first threshold diameter D1, the diameter of the core 202 is L MAX and the thickness of the intermediate sheath 206 is c MIN In these regions, the diameter of the core 202 and the thickness of the intermediate sheath 206 are not necessarily constant along the tubular structure 200. For example, if the tubular structure includes regions in which the inner diameter of the outer sheath 204 varies, the diameter of the core 202 and the thickness of the intermediate sheath 206 may vary reciprocally, such that an increase in the diameter of the core 202 is simultaneously accompanied by a decrease in the thickness of the intermediate sheath 206. The changes in the diameter of the core and the thickness of the intermediate sheath are optionally and preferably monotonic, e.g., linear.

[0205] The present embodiments also contemplate configurations in which the core 202 is made from a gel or gel-like material as defined herein (e.g., material S) and the intermediate sheath 206 is made from a liquid or liquid-like material as defined herein (e.g., material L). An advantage of these embodiments is that the non-solid intermediate sheath 206 reduces friction between the core 202 and the sheath 204, thus facilitating easy removal of the core 202 from the tubular structure 202 and reducing or eliminating the need to circulate a solution for removal. Another advantage is that the gel or gel-like core can provide excellent support to prevent inward collapse.

[0206] The gel or gel-like material forming the core 202 (for embodiments in which the core 202 is a gel or gel-like material) or the intermediate sheath 206 (for embodiments in which the intermediate sheath 206 is a gel or gel-like material) can be any build material, preferably a support material, suitable for use in AM. For example, the gel or gel-like material can be a build material having an elastic modulus of about 0.05 MPa to about 0.5 MPa per ASTM D-575, or about 0.1 MPa to about 1 MPa per ASTM D-575, and / or characterized by any of the properties described herein for a gel or gel-like material, such as material S.

[0207] A gel or gel-like material may, in some embodiments of the present invention, be obtained by ejecting a hardenable support material formulation, or a combination of two or more hardenable support material formulations (e.g., to form a digital material as described herein), or a combination of at least one hardenable support material formulation and at least one hardenable modeling material formulation (e.g., to form a digital material as described herein).

[0208] Gels or gel-like materials can be obtained in some embodiments of the invention using any of the known curable formulations that, when exposed to the curing conditions described herein, result in a hardened support material that can be used in the context of these embodiments as is known in the art, typically formulations that, when hardened, are water-soluble or water-miscible or water-degradable and / or removable by physical means (e.g., a water jet) or chemical means (e.g., a cleaning solution).

[0209] According to embodiments, the curable support material formulation, when exposed to curing conditions, the ratio of shear loss modulus G'' to shear storage modulus G' (tan delta) less than 1; flowability and / or decomposition when exposed to a hydraulic pressure of greater than 0.5 bar or greater than 1 bar; and Water soluble or water immiscible as defined herein; The present invention provides a hardened gel or gel-like support material characterized by at least one of the following:

[0210] Such curable support materials are also referred to herein as Formulation S.

[0211] An exemplary curable support material formulation S includes one or more curable materials, preferably hydrophilic or amphiphilic curable materials, e.g., as described herein in Example 1, more preferably monofunctional curable materials, one or more non-curable materials, preferably hydrophilic or amphiphilic polymeric materials, e.g., as described herein in Example 1, and one or more initiators to promote curing of the curable materials.

[0212] Exemplary additional support material formulations include, but are not limited to, those commercially available as SUP705, SUP706, and SUP707. The hardened gels or gel-like materials obtained upon exposure of these formulations to curing conditions (typically UV radiation) can be removed using cleaning solutions and / or physical means recommended for these formulations.

[0213] A liquid or liquid-like material is a build material that has properties substantially the same as or similar to those that characterize a liquid.

[0214] Throughout this specification and in the art, the term "liquid" refers to a fluid that does not change its volume in response to stress. Liquid materials are characterized by fluidity, i.e., the ability to flow as molecules move past one another, viscosity, i.e., resistance to shear stress, a very low or zero shear modulus (G), and a ratio of shear loss modulus to shear storage modulus (G'' / G' or tan delta) greater than 1, and typically greater than 10.

[0215] As used herein, "liquid-like (liquid-like) material" refers to a gel-like or paste-like material characterized by properties similar to a liquid, for example by being characterized by a low shear modulus (e.g., less than 100 kPa, or less than 50 kPa, or less than 10 kPa), and / or a shear loss modulus to shear storage modulus ratio (tan δ) greater than 1, or shear thinning behavior, such that its flowability, viscosity, and mobility are similar to those of a liquid.

[0216] In some embodiments of the invention, liquid and liquid-like materials are characterized by one or more of the following properties. a viscosity of 10,000 centipoise or less; and / or a shear loss modulus to shear storage modulus ratio (tan delta) greater than 1; and / or Shear thinning and / or thixotropic behavior; and / or Thermal thinning behavior; and / or A shear storage modulus less than 20 kPa; and / or Flowable when exposed to positive pressures of less than 1 bar or less than 0.5 bar.

[0217] Such materials are collectively referred to herein as Material L.

[0218] The shear storage modulus G', also referred to interchangeably herein as the "storage shear modulus," reflects the elastic behavior of a material. Liquid materials are typically inelastic and therefore characterized by a low shear storage modulus.

[0219] The shear loss modulus G'', also referred to interchangeably herein as the "loss shear modulus", reflects the viscous behavior of the material.

[0220] The storage shear modulus and loss shear modulus can optionally be determined using a shear rheometer, such as a strain-controlled rotational rheometer, at a specified temperature and frequency (e.g., using procedures well known in the art).

[0221] The ratio of shear loss modulus to shear storage modulus G'' / G', also known as "tan delta", reflects the viscoelastic behavior of a material. For liquid or liquid-like materials, this ratio is higher than 1, since liquid materials are typically more viscous and inelastic. Gels are typically elastic, and therefore for gel or gel-like materials, this ratio is lower than 1.

[0222] Throughout this specification, the term "shear-thinning" refers to the property of a fluid compound or material that is reflected in a decrease in its viscosity (an increase in its fluidity) upon the application of a shear force (under shear strain). In some of the present embodiments, a shear-thinning material is one that exhibits a significant, e.g., at least 100%, decrease in its shear modulus upon an increase in shear strain of about 1% to greater than 50%.

[0223] Throughout this specification, the term "thixotropic" refers to the property of a fluid compound or material that is reflected in time-dependent shear thinning, i.e., its viscosity decreases as a function of the time that a shear force is applied, and returns to its original value when the application of the shear force is stopped. In some of the present embodiments, a thixotropic material is one that exhibits a significant, e.g., at least 100%, decrease in shear modulus under 50% strain.

[0224] Throughout this specification, the term "thermal-thinning" refers to the property of a fluid compound or material that is reflected in a decrease in its viscosity (an increase in its fluidity) when thermal energy is applied (when the temperature is increased). In some of the present embodiments, the thermal-thinning material is characterized by at least a 20%, or at least a 50%, or even a 100% decrease in viscosity or shear modulus when heated to a temperature of 40-95°C (including any intermediate values ​​and subranges therebetween).

[0225] Example 2 in the Examples section below describes an exemplary build material formulation that can be used to provide the liquid or liquid-like materials described herein. Such formulations are also referred to herein as "liquid formulations" or as "Formulation L."

[0226] The one or more molding material formulations include one or more hardenable materials, optionally in combination with one or more non-hardenable materials, and further optionally in combination with initiators, surfactants, impact modifiers, colorants, thickeners, etc., as described herein.

[0227] Preferably, one or more of the build material formulations include a hardenable material in an amount of at least 50% by weight of the total weight of the build material formulation.

[0228] In some embodiments, the curable material is a UV curable material and the formulation further comprises one or more photoinitiators.

[0229] In some embodiments, the UV curable material is an acrylate or methacrylate, and can include monomeric, oligomeric, or polymeric acrylates and / or methacrylates.

[0230] The build material formulation is one in which, upon exposure to curing conditions (eg, UV radiation), the curable material polymerizes to yield a hardened (solidified; solidified) material or materials (eg, digital material).

[0231] The components of the build material formulation and their distribution are determined by the desired characteristics of the final object.

[0232] The sheath 204 can be made from any build material or combination of build materials known in the art. The material forming the sheath 204, in some embodiments of the invention, can be obtained by dispensing a hardenable build material formulation, or a combination of two or more hardenable build material formulations (e.g., to form a digital material as described herein), or a combination of at least one hardenable support material formulation and at least one hardenable build material formulation (e.g., to form a digital material as described herein). In various exemplary embodiments of the invention, at least one of the materials forming the sheath 204 has a Shore A hardness of zero (0) or close to zero (e.g., 10 or less, or 5 or less), or a Shore 00 hardness of less than 30. Representative examples of such materials suitable for the sheath 204 are described in Example 1 below.

[0233] The material forming the sheath 204 can be a digital material that combines material formulation C1 and material formulation C2, where C1 can have a tensile strength of about 2 to about 4 MPa per ASTM D-412 and a Shore A hardness of about 25 MPa to about 35 MPa per ASTM D-224D, and C2 can have a tensile strength of about 20 MPa to about 40 MPa per ASTM D-638-03 and a modulus of elasticity of about 750 MPa to about 1500 MPa per ASTM D-638-04.

[0234] 6 is a schematic diagram of the tubular structure 200 in an embodiment in which the sheath 204 is embedded within a support structure 208. The support structure 208 can have any shape and is preferably encapsulated around the sheath 204, optionally and preferably leaving one or two stems 204a and 204b of the tubular structure 200 protruding out of the support structure 208. The advantage of having the support structure 208 is that it allows for easier handling and transportation. An additional advantage is that the encapsulation protects the sheath 204 during the process of removing the sacrificial core 202 and, if present, the sacrificial intermediate sheath 206. These embodiments are particularly useful when the sheath 204 is soft and made from a material, for example, as described in Example 1 below. These embodiments are also useful when the sheath 204 has a small wall thickness (e.g., a wall thickness of less than 0.5 mm) and a small outer diameter (e.g., less than 10 mm).

[0235] In various exemplary embodiments of the invention, the support structure 208 is sacrificial. For example, the support structure 208 can be made from a support material. In these embodiments, after removal of the core 204 and intermediate sheath 206, if present, and optionally after handling and / or transport of the tubular structure 200, the support structure 208 is removed, for example, using any known technique for removing AM support material.

[0236] 7A-C are schematic diagrams of tubular structure 200 of an embodiment of the invention, where tubular structure 200 includes reinforcing element 201 embedded within sheath 204. Reinforcing element 210 is optionally and preferably oriented to provide anisotropic mechanical properties of sheath 204. This is advantageous when mimicking blood vessels, where mechanical properties in response to radially applied pressure are known to be different from mechanical properties in response to longitudinally applied forces. FIG. 7A illustrates an embodiment where reinforcing element 210 includes elongated reinforcing elements embedded within sheath 204 parallel to the longitudinal axis 212 of the sheath, FIG. 7B illustrates an embodiment where reinforcing element 210 includes annular reinforcing elements embedded within sheath 204 along azimuthal directions 214 that define sheath 204, and FIG. 7C illustrates an embodiment where reinforcing element 210 includes both annular reinforcing elements along azimuthal directions 214 and elongated reinforcing elements parallel to longitudinal axis 212.

[0237] The reinforcing element 210 is optionally and preferably made from a material having a higher hardness level than the material of the sheath 204. Suitable materials for the reinforcing element 210 can have a tensile strength of about 2 to about 4 MPa according to ASTM D-412 and a Shore A hardness of about 25 MPa to about 35 MPa according to ASTM D-224D. For example, the reinforcing element 210 can be made from a rubber-like material usable in the PolyJet™ system, an elastomeric curable material, such as those commercially available under the trade name "Agilus™" family, optionally utilizing silica particles (e.g., Agilus™ 30). Exemplary such materials are described in commonly assigned PCT International Application No. IL2017 / 050604 (published as WO2017 / 208238), the contents of which are incorporated herein by reference. Further exemplary families of rubber-like materials that can be used with the PolyJet™ system include those commercially available under the trade names "Tango™" and "Tango+™" that provide a wide variety of elastomeric properties to the resulting cured materials, including Shore A hardness, elongation at break, tear resistance, and tensile strength. Exemplary curable elastomeric formulations that can be used to form such rubber-like materials are also described below in Example 3.

[0238] FIG. 8 is a schematic cutaway view of a tubular structure 200 of an embodiment of the invention, where the tubular structure 200 includes a liner layer 216 that at least partially covers the inner surface 218 of the sheath 204. The liner layer 216 is preferably between the intermediate sheath 206 and the inner surface 208, but for clarity of presentation, the intermediate sheath 206 is not shown in FIG. 8. The liner layer 216 can be made of any construction material suitable for AM. The liner layer 216 can be made of any construction material. In some embodiments of the invention, the liner layer 216 can be made of a material having a Shore A hardness of zero (0) or close to zero (e.g., 10 or less, or 5 or less), or a Shore 00 hardness of less than 40. Representative examples of such materials are provided below in Example 1. Alternatively, the liner layer 216 can be made from a support material, such as a material having a modulus of elasticity of about 10 kPa to about 100 kPa, or about 10 kPa to about 50 kPa, or about 0.1 MPa to about 1 MPa per ASTM D-575 (material S described herein is an exemplary support material), optionally and preferably coated with an elastomeric curable material, such as a material having a tensile strength of about 2 to about 4 MPa per ASTM D-412, and a Shore A hardness of about 25 MPa to about 35 MPa per ASTM D-224D. Representative examples of such suitable elastomeric curable materials are provided in Example 3 below. Further alternatively, the liner layer 216 can be a combination of two or more of these materials, such as a digital material combination, as described in more detail below.

[0239] In various exemplary embodiments of the invention, the adhesion between the liner layer 216 and the sheath 204 is stronger than the adhesion between the intermediate sheath 206 and the liner layer 216. These embodiments are useful when it is desired to remove the intermediate sheath 206 without removing the liner layer 216. If the intermediate sheath 206 is made of a gel or gel-like material (e.g., material S), the circulation of the solution within the tubular structure 200 to remove the intermediate sheath 206 is optionally and preferably performed at a flow rate low enough so as not to remove the liner layer 216. If the intermediate sheath 206 is made of a liquid or liquid-like material (e.g., material L), the extraction of the core 202 and the intermediate sheath 206 is optionally and preferably performed at a force low enough so as not to remove the liner layer 216. In some embodiments of the invention, the liner layer 216 is harder than the sheath 204. Optionally and preferably, the material and / or texture of the liner layer 216 is selected such that the liner layer 216 has the mechanical properties of plaque tissue.

[0240] 25 is a schematic diagram of an object 230 fabricated by additive manufacturing from a non-biological build material formulation according to some embodiments of the present invention. The object 230 has the shape of an organ and preferably includes one or more structures having the shape of a blood vessel, e.g., tubular structure 200, and one or more structures 232 having the shape of a body structure other than a blood vessel. For example, the structures 232 can have the shape of a brain, head, limbs, neck, heart, lungs, liver, pancreas, spleen, thymus, esophagus, stomach, intestines, kidneys, testes, ovaries, bones, breasts, uterus, bladder, spinal cord, eyes, ears, etc.

[0241] 26 is an image of an interconnected network of elongated structures 240 fabricated by additive manufacturing from a non-biological build material compound according to some embodiments of the present invention. Each elongated structure has the shape of a blood vessel, and may be, for example, a tubular structure 200. In some embodiments of the present invention, the interconnected network 240 includes one or more support fixtures 242 configured to maintain the interconnected network 240 in a three-dimensional array.

[0242] 27 is a flow chart of a method for additive manufacturing of at least one tubular structure characterized by vascular properties, according to some embodiments of the present invention. The method starts at 270 and optionally and preferably continues to 271, where computer object data in any of the formats mentioned above is obtained. Exemplary techniques for obtaining computer object data are described below with reference to FIGS. 28A and 28B.

[0243] The method may proceed to 272, where one or more build material formulations of the layer are dispensed. The build material formulations may be build material formulations and / or support material formulations and / or formulations that provide a liquid or liquid-like material upon exposure to curing conditions as described herein. In some embodiments of the invention, the method selectively dispenses build material formulations in one or more regions and support material formulations in one or more regions and / or formulations that provide a liquid or liquid-like material upon exposure to curing conditions as described herein for a particular layer. The build material formulations are preferably dispensed in a configuration pattern that corresponds to the shape of the object and according to computer object data. Other build material formulations are preferably dispensed according to computer object data, but do not necessarily follow the shape of the object features, since these build material formulations are typically sacrificial objects.

[0244] Optionally, prior to dispensing, the uncured build material or a portion thereof (e.g., one or more formulations of the build material) is heated prior to dispensing. These embodiments are particularly useful for uncured build material formulations that have a relatively high viscosity at the operating temperature of the working chamber of the 3D inkjet printing system. The heating of the formulations is preferably performed to a temperature that allows the respective formulations to be jetted from a nozzle of a print head of the 3D inkjet printing system. In some embodiments of the present invention, the heating is performed to a temperature at which the respective formulation exhibits a viscosity of X centipoise or less, where X is about 30 centipoise, preferably about 25 centipoise, more preferably about 20 centipoise, or 18 centipoise, or 16 centipoise, or 14 centipoise, or 12 centipoise, or 10 centipoise, or less.

[0245] Heating can be performed prior to loading the respective formulation into the print head of an AM (e.g., 3D inkjet printing) system, while the formulation is in the print head, or while the composition passes through the nozzles of the print head.

[0246] In some embodiments, heating is performed prior to loading each formulation into an ejection (e.g., inkjet printing) head to prevent the formulation from clogging the ejection (e.g., inkjet printing) head if the formulation is too viscous.

[0247] In some embodiments, the heating is performed by heating a dispensing (e.g., inkjet printing) head at least while the build material formulation passes through a nozzle of the dispensing (e.g., inkjet printing) head.

[0248] In some embodiments, during the dispensing of a material formulation (e.g., formulation L) that remains liquid or liquid-like in the final object, operation of the cooling system described below is temporarily stopped to maintain a still air environment.

[0249] As used herein, "still air environment" refers to an environment where there is no air flow or where the air flow has a speed of less than 3 m / s.

[0250] At 273, the newly dispensed layer is straightened, for example, using the leveling device 32 or 132, which is optionally and preferably rotatable. Since the newly dispensed layer comprises a material formulation (e.g., formulation L) that will remain liquid or liquid-like in the final object, the rotational speed of the leveling device is preferably changed, typically slowed, compared to its speed when straightening the other layers. Control of the rotational speed of the leveling device can be performed by a controller (e.g., controller 20 or controller 340).

[0251] The method optionally and preferably continues to 274 where the deposited layer is exposed to curing conditions (e.g., curing energy is applied), such as by a curing device, such as a radiation source as described herein. Preferably, curing occurs for each individual layer after deposition of that layer and before deposition of a subsequent layer. Optionally, the deposited (discharged) layer is exposed to curing conditions other than curing energy, such as, but not limited to, contact with a chemical reagent or exposure to the environment.

[0252] Operations 272-274, and in some embodiments 271 as well, are preferably repeated multiple times in succession to successively dispense and solidify multiple layers. This is illustrated in FIG. 27 as a loop-back arrow pointing from operation 274 to operations 271 and 272. The layers are dispensed to form a stack of build layers and a sacrificial structure made from the build material formulation, which are separable from one another in a manner that maintains the shape and size of the stack of build layers without deformation. In various exemplary embodiments of the invention, operations 272-274 are performed such that the layers form an elongated core (e.g., core 202) and a sheath (e.g., sheath 204) encapsulating the core and having the shape of a blood vessel, the core optionally and preferably being a sacrificial structure. In some embodiments of the invention, these operations are performed such that an intermediate sheath (e.g., intermediate sheath 206) is also formed between the core and the sheath. The core, sheath, and intermediate sheath (if formed) are each formed by dispensing a different combination of build material formulations. The core and intermediate sheath (if formed) are optionally and preferably formed by dispensing a build material that can be removed after the object is completed, and thus are sacrificial objects as described herein.

[0253] Typically, a liquid or liquid-like material (e.g., material L) is used to fill cavities less than 4 mm wide along the cavity's smallest dimension, and a gel or gel-like support (e.g., material S) or a combination of a liquid or liquid-like material and a gel or gel-like material is used to fill cavities more than 4 mm wide along the cavity's smallest dimension. Preferably, when the liquid or liquid-like material or gel or gel-like material is dispensed and straightened, the AM system ensures, for example by controller 20 or 340, that the newly dispensed layer is in a still air environment.

[0254] In some embodiments of the present invention, the method dispenses a digital material formulation for at least one of the layers.

[0255] The phrase "digital material blend" as used herein and in the industry describes the combination of two or more material blends at a microscopic scale or voxel level such that a printed area of ​​a particular material blend is at the level of a few voxels or at the level of one voxel. Such digital material blends can exhibit new properties that are influenced by the selection of the type of material blend and / or the ratio and relative spatial distribution of the two or more material blends.

[0256] In an exemplary digital material formulation, the modeling or support material formulation of each voxel or voxel block obtained upon curing is independent of the modeling or support material formulation of adjacent voxels or voxel blocks obtained upon curing, and thus each voxel or voxel block results in a different modeling or support material formulation, and the new properties of the entire part are the result of the spatial combination at the voxel level of multiple different modeling material formulations.

[0257] Throughout this specification, whenever the phrase "at the voxel level" is used in the context of different material formulations and / or properties, it is meant to include differences between voxel blocks as well as differences between multiple voxels or groups of a few voxels. In a preferred embodiment, the properties of the entire object are the result of the spatial combination at the voxel block level of multiple different build material formulations.

[0258] In various exemplary embodiments of the invention, operations 272-274 are performed to form voxel elements including different build material formulations at interlaced locations for at least a portion of the layer.

[0259] In some embodiments, at least one, or at least a few (e.g., at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 80, or more) of the layers are formed by ejecting droplets of two or more build material formulations at interlaced positions, each build material formulation from a different ejection (e.g., inkjet printing) head. These build material formulations can include (i) two or more build material formulations described herein in any of the respective embodiments, (ii) at least one build material formulation and at least one support material formulation (liquid, liquid-like, or curable material) described herein in any of the respective embodiments, or (iii) two or more support material formulations (liquid, liquid-like, or curable material) described herein in any of the respective embodiments.

[0260] The interlace locations are optionally and preferably selected to form 3D texture regions across the layers. The interlace locations are optionally and preferably selected according to a modulation function. The modulation function receives the locations of the candidate voxels and provides output values ​​that are then used to select a material formulation for the candidate voxels. Thus, one build material formulation is assigned to the candidate voxel if the output value is within one predetermined range of output values, another build material formulation is assigned to the candidate voxel if the output value is within another predetermined range of output values, and so on. Typically, there is at least one output value or range of output values ​​for which no material is assigned to the candidate voxel. The material assignment of the candidate voxel is output to an AM system that dispenses the assigned formulation to the location of the candidate voxel.

[0261] In some embodiments of the present invention, a distance field is used in combination with a modulation function. Typically, a voxel is selected from the 3D building space, and a distance field value for the 3D object in the building space is determined for the selected voxel. The distance field value can then be used as an input for the modulation function. Thus, in these embodiments, the modulation function receives the position and distance field value of a candidate voxel, and provides an output value, which is then used to select a build material formulation for the candidate voxel, as further detailed herein.

[0262] The present embodiment contemplates many types of modulation functions. For example, in some embodiments of the present invention, the modulation function comprises a noise function. Representative examples of noise functions suitable for inclusion in the modulation function include, but are not limited to, simplex noise function, open simplex noise function, Worley noise function, Perlin noise function, wavelet noise function, and value noise function. In some embodiments, the modulation function comprises a periodic function. Typically, but not necessarily, a periodic modulation function has a period of 2 mm or less. In some embodiments, the modulation function comprises a periodic function. Combinations of two or more of these functions or other functions are also contemplated. A more detailed description of the concept of modulation function and distance field is provided in the Examples section below (see Example 4).

[0263] In some embodiments, the method continues to 275, where the liquid or liquid-like material (e.g., material L) is removed from the printed object, thereby revealing the final object. Removal of the liquid or liquid-like material is optionally and preferably performed by applying pressure into the cavity or cavities filled with the liquid or liquid-like material. The pressure is optionally and preferably sufficient to cause the liquid or liquid-like material to flow out of the cavity without causing pressure-induced damage to the sheath or sheaths enclosing the cavity. Optionally and preferably, if the liquid or liquid-like material is characterized by thermal thinning behavior, the object is heated, for example to a temperature of about 40° C. to about 95° C., prior to removal of the liquid or liquid-like material.

[0264] Where removal of the liquid or liquid-like material is effected by application of pressure, the pressure may be, for example, air pressure, or liquid pressure, for example in the form of a jet of an aqueous solution (eg water).

[0265] The pressure is preferably less than or equal to 1 bar, or less than or equal to 0.5 bar, or less than or equal to 0.3 bar, and may for example be 0.1 bar, 0.2 bar, or 0.3 bar.

[0266] Alternatively, and optionally in addition to the above, particularly if the liquid or liquid-like material is not sufficiently flowable at ambient conditions, removal of the liquid or liquid-like material is achieved by applying conditions that render the liquid or liquid-like material flowable. Such conditions include, for example, application of shear forces (e.g., if the material to be removed is a shear-thinning material) and / or application of thermal energy (e.g., if the material to be removed is a thermally thinning material).

[0267] Optionally and preferably, the hardened support material structure formed by the hardenable support material formulation or the combination of the hardenable support material formulation with other hardenable build material formulations is also removed at 275. If the hardened support structure forms an intermediate sheath, its removal is optionally and preferably performed by circulating a solution capable of removing the hardened support structure through the cavity occupied by the intermediate sheath. For example, a gel or gel-like hardened support structure can be water-soluble or water-miscible, in which case it is removed by contacting it with an aqueous solution in which it is soluble or dispersible (e.g., a cleaning solution; an aqueous solution containing an alkaline solution in an amount of 1% to 3% by weight of the solution).

[0268] In some embodiments, the gel or gel-like support material is removed upon application of physical means such as air or liquid jets at a pressure higher than 0.5 bar or higher than 1 bar, which is optionally and preferably higher than the pressure used to remove the liquid or liquid-like material.

[0269] If the solid support structure forms a core, its removal can be accomplished by withdrawing it from the open end of the sheath, optionally and preferably without circulating the solution.

[0270] The method ends at 276.

[0271] 28A is a flow chart diagram of an exemplary method that can be used in accordance with some embodiments of the present invention to perform the above operation 271. The method is particularly useful for obtaining computer object data for use in the system 10 or the system 110. It should be understood that the operations described below can be performed simultaneously or sequentially in many implementation combinations or orders, unless otherwise specified. In particular, the order of the flow chart diagrams should not be considered as limiting. For example, two or more operations that appear in a flow chart diagram or in the following description in a particular order can be performed in a different order (e.g., in the reverse order) or substantially simultaneously. Furthermore, several operations described below are optional and may not be performed.

[0272] The method begins at 700 and optionally and preferably continues to 701 where data in a format suitable for Digital Imaging and Communications in Medicine (hereinafter DICOM data) is received.

[0273] The DICOM data may be received from acquisition consoles including, but not limited to, MRI systems, CT imaging systems, helical CT systems, positron emission tomography (PET) systems, 2D or 3D fluoroscopic imaging systems, 2D, 3D or 4D ultrasound imaging systems, endoscopy systems, bedside monitor systems, X-ray systems, and hybrid imaging systems of CT, MR, PET, ultrasound or other imaging techniques. The DICOM data preferably includes one or more digital image data describing one or more body structures including one or more tissue elements. In some embodiments of the present invention, the DICOM data preferably includes one or more digital image data describing one or more blood vessels, and in some embodiments of the present invention, the DICOM data preferably includes one or more digital image data describing one or more body structures including one or more tissue elements other than blood vessels, and in some embodiments of the present invention, the DICOM data includes one or more digital image data describing one or more blood vessels and one or more digital image data describing one or more body structures including one or more tissue elements other than blood vessels.

[0274] The method optionally and preferably continues to 702 where the DICOM data is converted to computer object data. For example, the computer object data can be in any known format, including but not limited to Standard Tessellation Language (STL) or Stereo Lithography Contour (SLC) formats, Virtual Reality Modeling Language (VRML), Additive Manufacturing File (AMF) format, Drawing Interchange Format (DXF), Polygon File Format (PLY), or any other format suitable for Computer Aided Design (CAD), e.g., Wavefront (OBJ). The conversion from the DICOM data to the computer object data optionally and preferably includes one or more segmentation techniques selected from the group consisting of thresholding, region forming, dynamic region forming, and the like.

[0275] The thresholding method exploits the density differences of different tissues to select image pixels (picture elements) having values ​​equal to or greater than a defined threshold. For example, a defined threshold of the thresholding method can be selected such that image pixels related to hard tissues pass the thresholding method while other image pixel related are filtered. The thresholding method can be applied multiple times, each time using a different threshold, to obtain separate data sets for different tissue types.

[0276] A region formation method is typically applied after thresholding to isolate regions having the same density range. The region formation method may examine neighboring pixels of the initial seed point to determine whether the neighboring pixels belong to the region. This method is optionally and preferably performed iteratively to segment the image. For example, seed points may be selected according to different tissue types, and the region formation segmentation technique may be performed iteratively to isolate image pixels that belong to one of these tissue types. In a dynamic region formation method, a region of image parameters are selected in addition to the seed point. These parameters are selected to allow for recognition of the same image pixel as the seed point.

[0277] Typically, but not necessarily, an initial background segmentation method is applied to remove from DICOM data elements that do not belong to any of the tissue types of interest. Subsequent segmentation methods can be applied for more refined segmentation of one or more refined regions of the target anatomy by using different segmentation techniques.

[0278] After segmentation, the conversion of the DICOM data to computer object data may also include smoothing, wrapping and / or hole filling to compensate for artifacts in the DICOM data. Format conversion methods can then be applied to the segmented DICOM data to provide computer object data in any of the formats mentioned above.

[0279] In some embodiments of the invention, the input data is received from a computer readable medium as computer object data, in which case there is no need to obtain and convert DICOM data. In these embodiments, it is not necessary to perform operations 701 and 702.

[0280] In any event, the computer object data preferably includes data relating to the shape of one or more body structures including one or more tissue elements as described in further detail above. Whether obtained by conversion of DICOM data or so received directly, the computer object data is optionally and preferably arranged into multiple files, each relating to a different body structure.

[0281] If the body structure includes a sheathed hollow object having a cavity, such as, but not limited to, a vessel or vascular structure, the procedure optionally and preferably continues to 752, where computer object data describing the cavity, but not the sheath, is generated. The procedure can then continue to 753, where computer object data describing the cavity in a contracted shape is generated. The cavities described by the data at 753 are contracted in the sense that their outermost surfaces enclose a reduced volume compared to the volume of the cavity received as input. In other words, the cavities described by the data at 753 have a total area of ​​their outermost surfaces that is smaller than the area of ​​the inner surfaces of the hollow object described by the input data. Representative examples of techniques suitable for performing at 753 are described below. From 753, the method optionally and preferably continues to 754, where computer object data describing the sheathed hollow object (e.g., computer object data obtained at 702 or computer object data received from a computer readable medium) is combined with the computer object data obtained at 753. This combination provides combined computer object data describing an outermost sheath that encapsulates the core such that there is a gap between the inner surface of the outermost sheath and the outermost surface of the core. A more detailed description of operations 752, 753, and 754 is provided in Example 6 below.

[0282] Alternatively, operations 752, 753 and 754 can be skipped.

[0283] At 703, the type of body structure (e.g., soft tissue, bone, muscle tissue, smooth tissue, bone tumor, cartilage, intervertebral disc, nerve / spinal cord, fluid duct (e.g., blood vessels)) to be mimicked by the additively manufactured object is determined for each data file. The determination can be made by extracting information present in the respective computer object data file, or the respective DICOM data file, or information associated with the respective data file.

[0284] At 704, a set of rules associated with each body structure is selected. The set of AM rules optionally and preferably includes the build material formulation to be dispensed, and dispense parameters and conditions (e.g., temperature, interlacing ratio, interlacing texture). The set of AM rules can be obtained from a look-up table having an input for each type of body structure, and a set of additive manufacturing parameters associated with each such input. The set of parameters optionally and preferably includes at least one of the build material formulation and combination of build material formulations. For body structures that are blood vessels, and optionally and preferably for other types of body structures as well, the set of parameters optionally and preferably also includes the wall thickness of the blood vessel.

[0285] In some embodiments of the invention, a subject profile is received. The subject profile typically includes weight, sex, age, ethnicity, ancestry, medical history, etc. In some embodiments of the invention, the subject profile also includes a genetic profile, which may include genes in the subject's entire genome, or it may include a specific subset of genes. The genetic profile may include a genomic profile, a proteomic profile, an epigenomic profile, and / or a transcriptomic profile. In embodiments in which a subject profile is received, the lookup table also includes entries for different profile parameters. In particular, the lookup table may include multiple entries for each type of body structure, one entry for each profile parameter. As a non-limiting representative example, the lookup table may include multiple entries for blood vessels, where one entry for each age group.

[0286] In some embodiments of the invention, the set of AM rules is selected by an operator, for example via a user interface (e.g., user interface 116). Embodiments in which both a lookup table and a user interface are used are also contemplated. For example, a lookup table can be used to reduce the number of choices presented to the operator, and a user interface can be used to select the final set of AM rules.

[0287] Additionally, embodiments are contemplated in which the set of rules is received along with the computer object data, for example, each computer object data file can include one or more AM rules or can be associated with an AM rule file that includes one or more AM rules, where an AM rule corresponds to a respective computer object data.

[0288] At 705, a slicing operation is applied, optionally and preferably separately, to each computer object data file. Slicing is typically performed by generating a set of image files for the computer object data files, each describing a 2D voxel map of a plane characterized by a different vertical coordinate (e.g., the z coordinate mentioned above), the plane corresponding to a layer of the object that mimics a respective body structure. The image files can be in any conventionally known 2D format, such as, but not limited to, bitmap file (BMP), portable network graphics (PNG), etc. A preferred slicing technique is given below with reference to FIG. 28B.

[0289] At 706, two or more sets of image files are combined into a single image file. For example, image files corresponding to objects that have the same vertical coordinates but mimic different body structures can be combined to provide an image file that, once printed, describes layers including sliced ​​sections of two or more objects, each mimicking two or more body structures. At 707, the image files are uploaded to an AM system, such as, but not limited to, system 10 or system 110, to fabricate a non-living object resembling a body structure.

[0290] The method ends at 708.

[0291] Figure 28B is a flow chart diagram of an exemplary slicing method according to some embodiments of the present invention. This method is particularly useful for implementing the slicing operation 705 of Figure 28A. The method begins at 720 and is optionally and preferably applied to each voxel in the computer object data.

[0292] At decision 721, a distance field value for the 3D object is determined for each voxel. The distance field value indicates whether the voxel is inside or outside the anatomical object being printed. For example, negative distance field values ​​can be assigned to voxels outside the anatomical object, positive distance field values ​​can be assigned to voxels inside the anatomical object, and zero distance field values ​​can be assigned to voxels on the outermost surface of the anatomical object. A representative example of a suitable technique for determining distance field values ​​is provided in Example 4 below.

[0293] When a voxel is inside or on the outermost surface of the body mimicking object (e.g., when the distance field value is positive), the method continues to 722 where a build material formulation is assigned for the respective voxel. The build material formulation can be a modeling material formulation, a support material formulation, or a liquid material formulation, and is optionally and preferably determined based on the location of the voxel in the 3D object and the AM rules obtained in 704 above. From 722, the method continues to 724 where the method selects a pixel value corresponding to the assigned build material formulation. The pixel value can be any value that uniquely represents the assigned build material formulation. For example, the pixel value can be a grayscale level or a color value (e.g., RGB value).

[0294] If the voxel is outside the anatomy mimicking object (e.g., the distance field value is negative), the method continues to decision 723 where the method determines whether the voxel should be occupied or left blank. If the voxel should be left blank, the method continues to 726 where the method selects a pixel value that uniquely represents a blank pixel. For example, the method may select a null value to represent a blank pixel. Alternatively, if the voxel is outside the anatomy mimicking object, the method continues from 723 to 728 where it ends. In that case, a pixel that has not been assigned any value should be considered as an instruction to leave the voxel blank.

[0295] If the voxel is occupied, the method continues to 725 where a build material formulation is assigned to the voxel, and then continues to 724 where the method selects a pixel value corresponding to the assigned build material formulation as described in further detail above.

[0296] From 724, 725 or 726, as the case may be, the method continues to 727 where the selected pixel value is assigned to a pixel in the 2D image, where the position of the pixel in the 2D image corresponds to the position of a voxel in the layer represented by the 2D image.

[0297] The method ends at 728.

[0298] Throughout this specification, the term "bodily" as used in the context of, for example, a structure, organ, tissue, or material, describes the indicated structure, organ, tissue, or material as being part of the body of a subject, preferably a living subject. The term encompasses biological systems, organs, tissues, cells, and materials.

[0299] As used herein, the term "subject" includes animals of any age, preferably mammals, and more preferably humans. The term includes individuals who are at risk of developing a disease or who are suffering from a disease.

[0300] The term "body structure" as described herein refers to a part of a subject's body, including systems, organs, tissues, cells, and any surrounding environment thereof. A body structure may include, for example, multiple organs that work together in a living organism, such as the gastrointestinal tract, the cardiovascular system, the respiratory tract, etc. In addition to the organs and tissues that form part of these systems, the structure may also include structures related to pathologies, such as tumor cells or tissues. A body structure may alternatively include, for example, the heart and its associated blood vessels. A body structure may alternatively include an organ, such as the arm or forearm, or leg, and may encompass associated bone and muscle tissue, vascular system, tumor tissue (if present), and / or surrounding skin tissue.

[0301] The term "tissue" describes a part of an organism that is composed of cells designed to perform a function or functions. Examples include, but are not limited to, brain tissue, retina, skin tissue, liver tissue, pancreatic tissue, bone, cartilage, connective tissue, vascular tissue, muscle tissue, cardiac tissue, vascular tissue, kidney tissue, lung tissue, gonadal tissue, and hematopoietic tissue.

[0302] According to some of any of the embodiments described herein, at least a portion, and preferably all, of the build material formulations usable in the context of the present embodiments are synthetic, non-biological formulations and consist essentially of synthetic materials.

[0303] As used herein, "synthetic material" describes organic material that is not native to living subjects. The term encompasses non-living organic material, organic material that does not occur in nature, and / or organic material that is synthetically produced.

[0304] In accordance with some of any of the embodiments described herein, at least a portion, and preferably all, of the build material formulation usable in the context of the present embodiments is devoid of biological materials.

[0305] "Biological material," as used herein, means organic material inherently present in living subjects, as defined herein, including, for example, cells and cellular components, proteins (including enzymes, hormones, receptor ligands, etc.), peptides, nucleic acids, and amino acids.

[0306] "Devoid of" means less than 1 wt.% or from 0.5 to 0.1 to 0.05 to 0.01 to 0.005 to 0.001 wt.%, inclusive, of the total weight of the formulation.

[0307] It should be understood that some of the present embodiments contemplate formulations containing water. In accordance with some of any of the embodiments described herein, at least some, and preferably all, of the build material formulations usable in the context of the present embodiments are acellular, i.e., devoid of biological cells or cellular components.

[0308] According to some of any of the embodiments described herein, the modeling material formulations described herein contain less than 10% by weight, or less than 8% by weight, or less than 5% by weight, or even less water, and are devoid of water as defined herein.

[0309] In some of any of the embodiments described herein, the curable materials and particularly the non-curable materials included in the build material formulation(s) and formulation systems described herein are non-toxic, environmentally harmless, and therefore safe for use and disposal.

[0310] It is anticipated that many related material formulations will be developed during the life of the patent that matures from this application, and the scope of the term "material formulation" is intended to encompass a priori all such new technologies to the extent that these material formulations exhibit the mechanical properties described herein.

[0311] As used herein, the term "about" refers to ±10% or ±5%.

[0312] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features from other embodiments.

[0313] The term "optional" is used herein to mean "present in some embodiments, but not in other embodiments." Any particular embodiment of the present invention may include multiple "optional" features, unless otherwise stated.

[0314] The terms "comprises, comprising, includes, including," "having," and their conjugations mean "including but not limited to."

[0315] The term "consisting of" means "including and limited to."

[0316] The phrase "consisting essentially of" means that the composition, method, or structure may include additional ingredients, steps, and / or moieties only if the additional ingredients, steps, and / or moieties do not materially alter the basic and novel characteristics of the claimed composition, method, or structure.

[0317] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. For example, the term "a compound" or "at least one compound" can include a plurality of compounds, including mixtures thereof.

[0318] Throughout this application, various aspects of the 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. Thus, the description of a range should be considered to have all possible subranges specifically disclosed, as well as individual numerical values ​​contained within that range. For example, the description of a range such as 1-6 should be considered to have specifically disclosed subranges (e.g., 1-3, 1-4, 1-5, 2-4, 2-6, 3-6, etc.), as well as individual numerical values ​​contained within that range (e.g., 1, 2, 3, 4, 5, and 6). This applies regardless of the breadth of the range.

[0319] Whenever a range of numerical values ​​is given herein, it is meant to include any recited numbers (fractional or integer) that are included in the given range. The phrases "ranging between" a first given number and a second given number, and "ranging from" a first given number to a second given number, are used interchangeably and are meant to include the first given number, the second given number, and all fractional and integer numbers therebetween.

[0320] As used herein, the terms "method or process" refer to manners, means, techniques, and procedures for accomplishing a given task, including, but not limited to, such manners, means, techniques, and procedures that are known to practitioners in the arts of chemistry, physics, and engineering or that are readily developed by practitioners in the arts of chemistry, physics, and engineering from known manners, means, techniques, and procedures.

[0321] Throughout this specification, the term "(meth)acrylic" encompasses acrylic and methacrylic compounds.

[0322] Throughout this specification, the phrase "linking moiety" or "linking group" describes a group that connects two or more moieties or groups in a compound. Linking moieties are generally derived from di- or trifunctional compounds and can be viewed as two or three radical moieties, with the two or three radicals being connected to two or three other moieties through their two or three atoms, respectively.

[0323] Exemplary linking moieties, as defined herein, include hydrocarbon moieties or chains, optionally interrupted by one or more heteroatoms, and / or any of the chemical groups listed below when defined as linking groups.

[0324] When a chemical group is referred to herein as an "terminal group," it is interrupted as a substituent, and the substituent is connected by one atom of it to another group.

[0325] Throughout this specification, the term "hydrocarbon" collectively describes a chemical group composed primarily of carbon and hydrogen atoms. The hydrocarbon may consist of alkyl, alkene, alkyne, aryl, and / or cycloalkyl, each of which may be substituted or unsubstituted and may be interrupted by one or more heteroatoms. The number of carbon atoms may range from 2 to 20, and preferably lower, for example, from 1 to 10, or 1 to 6, or 1 to 4. The hydrocarbon may be a linking group or a terminal group.

[0326] Bisphenol A is an example of a hydrocarbon composed of two aryl groups and one alkyl group.

[0327] As used herein, the term "amine" describes both the -NR'R" and -NR'- groups, where R' and R" are each independently hydrogen, alkyl, cycloalkyl, or aryl, as these terms are defined herein below.

[0328] Thus, the amine group can 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 R' and R" are each independently alkyl, cycloalkyl, or aryl).

[0329] 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, or hydrazine.

[0330] The term "amine" is used herein to represent the -NR'R" group, as defined hereinbelow, when the amine is a terminal group, and is used herein to represent the -NR'- group when the amine is part of a linking group or moiety.

[0331] The term "alkyl" describes saturated aliphatic hydrocarbons, including straight-chain and branched-chain groups. Preferably, the alkyl group has 1-3 or 1-20 carbon atoms. Whenever a numerical range, e.g., "1-20," is stated herein, it means that the group (in this case, the alkyl group) contains 1 carbon atom, 2 carbon atoms, 3 carbon atoms, etc., up to 20 carbon atoms. The alkyl group can be substituted or unsubstituted. A substituted alkyl can have one or more substituents, each of which can independently be, for example, a hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine, or hydrazine.

[0332] An alkyl group can be an end group (as this term is defined hereinabove) attached to a single adjacent atom, or a linking group (as this term is defined hereinabove) that links two or more moieties through at least two carbons in the chain. When an alkyl is a linking group, it is also referred to herein as an "alkylene" or an "alkylene chain."

[0333] As used herein, a C(1-4) alkyl substituted by a hydrophilic group, as defined herein, is included under the expression "hydrophilic group".

[0334] Alkenes and alkynes as used herein are alkyl, as defined herein, containing one or more double or triple bonds, respectively.

[0335] The term "cycloalkyl" describes an all-carbon monocyclic or fused ring (i.e., rings that share adjacent pairs of carbon atoms) group in which one or more of the rings do not have a completely conjugated pi-electron system. Examples include, but are not limited to, cyclohexane, adamantine, norbornyl, isobornyl, and the like. Cycloalkyl groups can be substituted or unsubstituted. A substituted cycloalkyl can have one or more substituents, each of which can be, independently, for example, a hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine, or hydrazine. A cycloalkyl group can be an end group (as this term is defined hereinabove) attached to a single adjacent atom, or a linking group (as this term is defined hereinabove) that links two or more moieties through at least two carbons in the chain.

[0336] Cycloalkyls of 1 to 6 carbon atoms that are substituted by two or more hydrophilic groups, as defined herein, are included under the expression "hydrophilic group" herein.

[0337] The term "heteroalicyclic" describes a monocyclic or fused ring group having one or more atoms in the ring(s), such as, for example, nitrogen, oxygen, and sulfur. The ring may also have one or more double bonds. However, the ring does not have a completely conjugated pi-electron system. Representative examples are piperidine, piperazine, tetrahydrofuran, tetrahydropyran, morpholino, and the like.

[0338] Heteroalicyclic rings can be substituted or unsubstituted. Substituted heteroalicyclic rings can have one or more substituents, each of which can be, independently, for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine, or hydrazine. Heteroalicyclic groups can be terminal groups (as this term is defined hereinabove) attached to a single adjacent atom, or linking groups (as this term is defined hereinabove) that link two or more moieties through at least two carbons in the chain.

[0339] Heteroalicyclic groups which contain one or more electron donor atoms such as nitrogen or oxygen and have a numerical ratio of carbon atoms to heteroatoms of 5:1 or lower are included herein under the expression "hydrophilic group".

[0340] The term "aryl" group describes an all-carbon monocyclic or fused polycyclic (i.e., rings that share adjacent pairs of carbon atoms) group having a completely conjugated pi-electron system. Aryl groups can be substituted or unsubstituted. Substituted aryls can have one or more substituents, each of which can independently be, for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine, or hydrazine. An aryl group can be a terminal group (as this term is defined hereinabove) attached to a single adjacent atom, or a linking group (as this term is defined hereinabove) that links two or more moieties through at least two carbons in the chain.

[0341] The term "heteroaryl" describes a monocyclic or fused ring (i.e., rings that share adjacent pairs of carbon atoms) group having one or more atoms, such as, for example, nitrogen, oxygen, and sulfur, in the ring(s) and further having a completely conjugated pi-electron system. Non-limiting examples of heteroaryl groups include pyrrole, furan, thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrimidine, quinoline, isoquinoline, and purine. Heteroaryl groups can be substituted or unsubstituted. Substituted heteroaryl can have one or more substituents, each of which can be, independently, for example, hydroxyalkyl, trihaloalkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic, amine, halide, sulfonate, sulfoxide, phosphonate, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, sulfonamide, C-carboxylate, O-carboxylate, N-thiocarbamate, O-thiocarbamate, urea, thiourea, N-carbamate, O-carbamate, C-amide, N-amide, guanyl, guanidine, or hydrazine. Heteroaryl groups can be terminal groups (as this term is defined hereinabove) attached to a single adjacent atom, or linking groups (as this term is defined hereinabove) that link two or more moieties through at least two carbons in the chain. Representative examples are pyridine, pyrrole, oxazole, indole, purine, and the like.

[0342] The terms "halide" and "halo" describe fluorine, chlorine, bromine, or iodine.

[0343] The term "haloalkyl" describes an alkyl group, as defined above, further substituted by one or more halide.

[0344] The term "sulfate" describes an -OS(=O)2-OR' terminal group or an -OS(=O)2-O- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0345] The term "thiosulfate" describes an -OS(=S)(=O)-OR' terminal group or an -OS(=S)(=O)-O- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0346] The term "sulfite" describes an -OS(=O)-O-R' end group or an -OS(=O)-O- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0347] The term "thiosulfite" describes an -OS(=S)-O-R' end group or an -OS(=S)-O- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0348] The term "sulfinate" describes an -S(=O)-OR' terminal group or an -S(=O)-O- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0349] The term "sulfoxide" or "sulfinyl" describes an -S(=O)R' terminal group or an -S(=O)- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0350] The term "sulfonate" describes an -S(=O)2-R' terminal group or an -S(=O)2- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0351] The term "S-sulfonamide" describes an -S(=O)2-NR'R" terminal group or an -S(=O)2-NR'- linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0352] The term "N-sulfonamide" describes an R'S(=O)2-NR" terminal group or an -S(=O)2-NR'- linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0353] The term "disulfide" describes an -S-SR' end group or an -SS- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0354] The term "phosphonate" refers to a -P(=O)(OR')(OR") end group or a -P(=O)(OR')(O)- linking group, with R' and R" as defined herein, as these terms are defined herein above.

[0355] The term "thiophosphonate" refers to a -P(=S)(OR')(OR") end group or a -P(=S)(OR')(O)- linking group, with R' and R" as defined herein, as these terms are defined herein above.

[0356] The term "phosphinyl" refers to a -PR'R" terminal group or a -PR'- linking group, with R' and R" as defined hereinabove, these representations being as defined hereinabove.

[0357] The term "phosphine oxide" refers to a -P(=O)(R')(R") end group or a -P(=O)(R')- linking group, with R' and R" as defined herein, as these expressions are defined herein above.

[0358] The term "phosphine sulfide" refers to a -P(=S)(R')(R") end group or a -P(=S)(R')- linking group, with R' and R" as defined herein, as these expressions are defined herein above.

[0359] The term "phosphite" refers to an -O-PR'(=O)(OR") end group or an -O-PH(=O)(O)- linking group, with R' and R" as defined herein, as these expressions are defined herein above.

[0360] The term "carbonyl" or "carbonate" as used herein refers to a -C(=O)-R' terminal group or a -C(=O)- linking group, with R' as defined herein, as these representations are defined herein above.

[0361] The term "thiocarbonyl," as used herein, represents a -C(=S)-R' terminal group or a -C(=S)- linking group, with R' as defined herein, as these expressions are defined herein above.

[0362] The term "oxo" as used herein represents a (=O) group in which an oxygen atom is connected by a double bond to an atom (eg, a carbon atom) at the indicated position.

[0363] The term "thioxo," as used herein, represents a (=S) group in which a sulfur atom is connected by a double bond to an atom (eg, a carbon atom) at the indicated position.

[0364] The term "oxime" describes a =N-OH terminal group or a =NO- linking group, as these terms are defined hereinabove.

[0365] The term "hydroxyl" describes an --OH group.

[0366] The term "alkoxy" describes both an --O-alkyl group, and an --O-cycloalkyl group, as defined herein.

[0367] The term "aryloxy" describes both an --O-aryl group, and an --O-heteroaryl group, as defined herein.

[0368] The term "thiohydroxy" describes a -SH group.

[0369] The term "thioalkoxy" describes both an --S-alkyl group, and an --S-cycloalkyl group, as defined herein.

[0370] The term "thioaryloxy" describes both an --S-aryl group, and an --S-heteroaryl group, as defined herein.

[0371] "Hydroxyalkyl," also referred to herein as "alcohol," describes an alkyl, as defined herein, substituted by a hydroxy group.

[0372] The term "cyano" describes a -C≡N group.

[0373] The term "isocyanate" describes the group --N.dbd.C.dbd.O.

[0374] The term "isothiocyanate" describes the group --N.dbd.C.dbd.S.

[0375] The term "nitro" describes a -NO2 group.

[0376] The term "acyl halide" describes a -(C=O)R"" group, where R"" is a halide as defined hereinabove.

[0377] The terms "azo" or "diazo" describe an -N=NR' terminal group or an -N=N- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0378] The term "peroxo" describes an -O-OR' end group or an -OO- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0379] The term "carboxylate" as used herein includes C-carboxylates and O-carboxylates.

[0380] The term "C-carboxylate" describes a -C(=O)-OR' terminal group or a -C(=O)-O- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0381] The term "O-carboxylate" describes an -OC(=O)R' terminal group or an -OC(=O)- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0382] Carboxylates can be linear or cyclic. When cyclic, R' and a carbon atom are linked together to form a ring in the C-carboxylate, which is also referred to as a lactone. Alternatively, R' and O are linked together to form a ring in the O-carboxylate. Cyclic carboxylates can function as linking groups, for example, when an atom in the ring formed is linked to another group.

[0383] The term "thiocarboxylate" as used herein includes C-thiocarboxylates and O-thiocarboxylates.

[0384] The term "C-thiocarboxylate" describes a -C(=S)OR' terminal group or a -C(=S)-O- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0385] The term "O-thiocarboxylate" describes an -OC(=S)R' terminal group or an -OC(=S)- linking group, as these terms are defined hereinabove, where R' is defined hereinabove.

[0386] Thiocarboxylates can be linear or cyclic. When cyclic, R' and a carbon atom are linked together to form a ring, in a C-thiocarboxylate, which group is also referred to as a thiolactone. Alternatively, R' and O are linked together to form a ring, in an O-thiocarboxylate. Cyclic thiocarboxylates can function as linking groups, for example, when an atom in the ring formed is linked to another group.

[0387] The term "carbamate" as used herein includes N-carbamates and O-carbamates.

[0388] The term "N-carbamate" describes an R"OC(=O)-NR'- terminal group or an -OC(=O)-NR'- linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0389] The term "O-carbamate" describes an -OC(=O)-NR'R" terminal group or an -OC(=O)-NR'- linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0390] Carbamates can be straight chain or cyclic. When cyclic, R' and a carbon atom are linked together to form a ring, in an O-carbamate. Alternatively, R' and O are linked together to form a ring, in an N-carbamate. Cyclic carbamates can function as linking groups, for example, when an atom in the ring formed is linked to another group.

[0391] The term "carbamate" as used herein includes N-carbamates and O-carbamates.

[0392] The term "thiocarbamate" as used herein includes N-thiocarbamates and O-thiocarbamates.

[0393] The term "O-thiocarbamate" describes an -OC(=S)-NR'R" terminal group or an -OC(=S)-NR'- linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0394] The term "N-thiocarbamate" describes an R"OC(=S)NR'- terminal group or an -OC(=S)NR'- linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0395] The thiocarbamates can be linear or cyclic, as described herein for carbamates.

[0396] The term "dithiocarbamate" as used herein includes S-dithiocarbamates and O-thiodithiocarbamates.

[0397] The term "S-dithiocarbamate" describes an -SC(=S)-NR'R" terminal group or an -SC(=S)NR'- linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0398] The term "N-dithiocarbamate" describes an R"SC(=S)NR'- terminal group or an -SC(=S)NR'- linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0399] The term "urea" (also referred to as "ureido") describes a -NR'C(=O)-NR"R"' terminal group or a -NR'C(=O)-NR"- linking group, as these terms are defined hereinabove, where R' and R" are as defined hereinabove for R' and R".

[0400] The term "thiourea" (also referred to as "thioureido") describes a -NR'C(=S)-NR"R"' terminal group or a -NR'-C(=S)-NR"- linking group, as these terms are defined hereinabove, where R', R" and R"' are defined hereinabove.

[0401] The term "amide" as used herein includes C-amide and N-amide.

[0402] The term "C-amide" describes a -C(=O)-NR'R" terminal group or a -C(=O)-NR'- linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0403] The term "N-amide" describes an R'C(=O)-NR"- terminal group or an R'C(=O)-N- linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0404] The amide can be linear or cyclic. When cyclic, R' and the carbon atom are linked together to form a ring at C-amide, which group is also referred to as a lactam. Cyclic amides can function as linking groups, for example, when an atom in the ring formed is linked to another group.

[0405] The term "guanyl" describes an R'R"NC(=N)-terminus or an -R'NC(=N)-linking group, as these terms are defined hereinabove, where R' and R" are defined hereinabove.

[0406] The term "guanidine" describes a -R'NC(=N)-NR"R"' terminal group or a -R'NC(=N)-NR"- linking group, as these terms are defined hereinabove, where R', R" and R"' are defined hereinabove.

[0407] The term "hydrazine" describes an -NR'-NR"R"' terminal group or an -NR'-NR"- linking group, as these terms are defined hereinabove, where R', R" and R"' are defined hereinabove.

[0408] As used herein, the term "hydrazide" refers to a -C(=O)-NR'-NR"R"' terminal group or a -C(=O)-NR'-NR"- linking group, where R', R" and R"' are as defined herein, as defined hereinabove.

[0409] As used herein, the term "thiohydrazide" refers to a -C(=S)-NR'-NR"R"' terminal group or a -C(=S)-NR'-NR"- linking group, where R', R", and R"' are as defined herein, as defined hereinabove.

[0410] As used herein, the term "alkylene glycol" refers to -O-[(CR'R") z -O] y -R"' end group or -O-[(CR'R") z -O] y-linking group, where R', R", and R"' are as defined herein, z is an integer from 1 to 10, preferably an integer from 2 to 6, more preferably an integer of 2 or 3, and y is an integer of 1 or greater. Preferably, R' and R" are both hydrogen. When z is 2 and y is 1, the group is ethylene glycol. When z is 3 and y is 1, the group is propylene glycol. When y is 2 to 4, the alkylene glycol is referred to herein as an oligo(alkylene glycol).

[0411] When y is greater than 4, the alkylene glycol is referred to herein as a poly(alkylene glycol). In some embodiments of the invention, a poly(alkylene glycol) group or moiety can have 1 to 20 repeating alkylene glycol units, such that z is 1 to 200, preferably 1 to 100, and more preferably 10 to 50.

[0412] The term "silanol" describes a -Si(OH)R'R" group or a -Si(OH)2R' group or a -Si(OH)3 group, where R' and R" are as defined herein.

[0413] The term "silyl" describes a -SiR'R"R"' group, where R', R", and R"' are as defined herein.

[0414] As used herein, the term “urethane” or “urethane moiety” or “urethane group” refers to a urethane group represented by R X -OC(=O)-NR'R" end group or -R X describes an —OC(═O)NR′ linking group, where R′ and R″ are as defined herein; X is alkyl, cycloalkyl, aryl, alkylene glycol, or any combination thereof. Preferably, R' and R" are both hydrogen.

[0415] The terms "polyurethane" or "oligourethane" describe moieties that contain at least one urethane group as described herein in a repeating backbone unit or that contain at least one urethane bond, --OC(.dbd.O)NR'--, in a repeating backbone unit.

[0416] It will be appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as otherwise suitable in other described embodiments of the invention. Certain features described in the context of various embodiments should not be construed as essential features of those embodiments, unless the embodiment is inoperable without those elements.

[0417] Each of the various embodiments and aspects of the present invention as delineated hereinabove and as claimed in the claims section below finds experimental support in the following examples. EXAMPLES

[0418] Reference is now made to the following examples, which together with the above descriptions illustrate the invention in a non-limiting fashion.

[0419] Example 1 Soft Material Compound: Build material formulations usable in the additive manufacturing methods described herein in any of their respective embodiments include, in some embodiments, at least one modeling material formulation that, when cured, has (is characterized by) a Shore A hardness of less than 10 or a Shore OO hardness of less than 40. Such formulations are also referred to herein as "soft material formulations" or "soft material modeling formulations" or "soft modeling formulations."

[0420] "Hardness" as used herein and in the industry describes resistance to permanent indentation when measured under specific conditions. For example, Shore A hardness, also referred to as hardness ShA or Shore A hardness, is determined according to the ASTM D2240 standard using a digital Shore A hardness durometer. For example, Shore OO hardness, also referred to as hardness ShOO or Shore OO hardness, is determined according to the ASTM D2240 standard using a digital Shore OO hardness durometer. D, A, and OO are common scales of hardness values, each measured using a respective durometer.

[0421] In some of the embodiments described herein, the soft material formulations described herein, when cured, have a Shore A hardness ranging from 0 to about 10, including any intermediate values ​​and subranges therebetween.

[0422] In some of any of the embodiments as described herein, the soft material formulations described herein, when cured, have a Shore OO hardness ranging from 0 to about 40, or from 0 to about 30, or from 0 to about 20, or such as from about 10 to about 20, or from about 10 to about 30, including any intermediate values ​​and subranges therebetween.

[0423] Another parameter indicative of the low hardness of the soft material obtained for the cured soft material formulation as described herein is the compression modulus.

[0424] As used herein, "compressive modulus" refers to the ratio of mechanical stress to strain in a material when the material is compressed. Compressive modulus can also be considered as the modulus of elasticity imparted to a material under compression. In some embodiments, the compressive modulus is determined according to ASTM D695. In some embodiments, the compressive modulus was determined for cylindrical uncoated objects (printed from the soft formulation itself tested) with a radius of 20 mm and a height of 15 mm printed using a Stratasys J750 3D printer. Tests were performed using a Lloyd instrumentation system, 100 N load cell, operated with the following parameters: direction=compression; preload / stress=0.5 N; preload / stress speed=50 mm / min; speed=50 mm / min; limit=8 mm. Stress versus strain data was extracted from the data obtained and the slope between strain values ​​of 0.001 and 0.01 was calculated. The data obtained in these tests can be expressed as compressive stress at 40% strain, or as the slope of the stress versus strain curve, when measured in the compressive mode, taken at strain values ​​between 0.001 and 0.01.

[0425] The same Lloyd system can be used for adhesion testing, operated with the following parameters: direction = tension; deceleration = 2 mm / min; acceleration = 5 mm / min; force drop = -5 N; hold time = 1 sec. Specimens where the soft formulation being tested was used as a coating were measured and the results are reported as the maximum load required to pull the platen off the coated specimen.

[0426] The compression modulus can alternatively be determined for a cylindrical Agilus30 coated object made from the tested soft compound, with a radius of 20 mm and a height of 15 mm, printed, for example, using a Stratasys J750 3D printer. Tests are performed using a Lloyd instrument system, 100 N load cell, operated with the following parameters: direction=compression; preload / stress=0.5 N; preload / stress speed=50 mm / min; speed=50 mm / min; limit=90 N. The compression modulus is determined for a maximum stress value of 90 N. Stress versus strain data can be extracted from the obtained data, and the slope between strain values ​​of 0.001 and 0.01 is calculated.

[0427] In some of any of the embodiments described herein, the soft material formulation as described herein, when cured, has a compressive modulus of at least 0.01 MPa.

[0428] In some embodiments, the soft material formulations as described herein, when cured, have a compressive modulus (as defined herein) of from about 0.01 to about 0.2 MPa, or from about 0.02 to about 0.2 MPa, or from about 0.01 to about 0.1 MPa, or from about 0.02 to about 0.1 MPa, or from about 0.03 to about 0.07 MPa, including any intermediate values ​​and subranges therebetween.

[0429] In some embodiments, a soft material formulation as described herein, when cured, in addition to its low hardness, possesses at least moderate tear resistance.

[0430] Tear resistance (TR) describes the force required to tear a material, the force acting substantially parallel to the major axis of the specimen. Tear resistance, as measured by the ASTM D412 method, can be used to measure resistance to tear formation (tear initiation) and resistance to tear propagation (tear propagation). Typically, a specimen is held between two holders and a uniform tensile force is applied until deformation occurs. Tear resistance is then calculated by dividing the applied force by the thickness of the material. Materials with low tear resistance tend to have poor resistance to abrasion.

[0431] In some embodiments, tear resistance (TR) is determined according to ASTM D624 for specimens described therein having a thickness of 2 mm. Values ​​are reported herein as load (N) at maximum load for 2 mm thick specimens. Time to failure can also be measured with this test. The reported values ​​can be converted to N / m tear resistance values ​​as described, then divided by 0.002. For example, a value of 0.3 N is equivalent to 150 N / m.

[0432] The load to failure can be determined for a cubic Agilus coated object made from the tested formulation, having dimensions of 50x50x50mm, printed using a Stratasys J750 3D printer. The test is performed using a Lloyd equipment system, 100N load cell, operated with the following parameters: direction=compression; preload / stress=0.5N; preload / stress speed=50mm / min; speed=50mm / min, and the load to failure is determined as the maximum load that the sample can hold before ultimate failure.

[0433] In some of any of the embodiments described herein, the soft material formulations described herein, when cured, have a tear resistance of at least 100 N / m as determined by ASTM D624 for specimens having a thickness of 2 mm.

[0434] In some embodiments, the soft material formulation as described herein, when cured, has a tear resistance of at least 150N as determined by ASTM D624 for specimens having a thickness of 2 mm, and in some embodiments, it has a tear resistance of 150N / m to 500N / m, or 150 to 400N / m, or 200N / m to 400N / m, or 200N / m to 350N / m, including any intermediate values ​​and subranges therebetween.

[0435] In some embodiments, tear resistance measurements are used to determine the time to failure of a specimen under an applied tensile force.

[0436] In some embodiments, the soft material formulation as described herein, when cured, has a time to failure of at least 9 seconds, e.g., 9 to 50, or 9 to 40, or 9 to 30, or 15 to 30 seconds, as measured by ASTM D624 for specimens having a thickness of 2 mm.

[0437] In some of any of the embodiments described herein, the soft molding formulations described herein are characterized by good reactivity, i.e., an ejected layer containing the formulation is cured when exposed to curing conditions within a time period of less than one second, and / or a cured layer made from the soft molding formulation exhibits good adhesion (e.g., as shown below).

[0438] In some embodiments, the soft modeling formulations as described herein are characterized by a transition from liquid to solid within 1 second upon exposure to curing conditions. In some of these embodiments, the curing conditions include UV irradiation, e.g., 1 W / cm 2 In some embodiments, the UV radiation is a UV mercury (Hg) arc lamp (medium pressure, metal halide). In some embodiments, the soft modeling formulations as described herein are cured under curing conditions (e.g., wavelengths of about 300 nm to about 450 nm and about 1 W / cm2). 2It is characterized by a transition from liquid to solid within one second when exposed to UV radiation (e.g., UV irradiation using a 250W mercury arc lamp at a power density of 1000 nm).

[0439] The time required for the transition from liquid to solid can be determined using conventional DSC measurements.

[0440] In some of any of the embodiments described herein, the soft build material formulation as described herein is characterized by good compatibility with the AM system, i.e., it meets the system operating conditions (e.g., with respect to viscosity and viscosity stability, thermal stability, etc., as described above).

[0441] In some of any of the embodiments described herein, the soft modeling material formulation as described herein is characterized by good compatibility with AM, which is 3D inkjet printing, i.e., it is jettable and compatible within an inkjet printhead, has a suitable viscosity for use with an inkjet printhead as described herein, and has a viscosity stability at 25-75°C for at least 24 hours, preferably at least 48 hours.

[0442] In some of any of the embodiments described herein, the soft modeling material formulations described herein are characterized by a stability (storage stability) of at least 1 month, or at least 2, 3, 4, 5 months, or even at least 6 months, i.e., the formulation has substantially the same properties (e.g., any of the properties described herein) upon storage for the indicated time.

[0443] In some of any of the embodiments described herein, the soft modeling material formulations as described herein are characterized by a stability (storage stability) of at least 1 month, or at least 2, 3, 4, 5 months, or even at least 6 months, i.e., the formulation has substantially the same appearance (e.g., color) upon storage (e.g., at room temperature) for the indicated time.

[0444] The stability can be determined for uncoated objects (printed from the soft formulation tested per se) or coated objects (printed with a 0.8 mm coating of an elastomeric curable material (e.g. Agilus family, e.g. Agilus 30®), all printed using a Stratasys J750™ 3D printer and having a cubic shape of 25 mm×25 mm×25 mm, weighing the obtained object once printed, storing the object at 50° C. for 7 days, reweighing using an analytical scale and giving the weight change in weight in % relative to the initial weight after printing.

[0445] Stability can also be measured on Agilus coated cubic objects printed from the tested formulations themselves using a Stratasys J750™ 3D printer with dimensions 50mm x 50mm x 50mm, weighing the resulting objects once printed, storing the objects at 50°C for 3 days and re-weighing using an analytical scale. Weight change is given in wt% with respect to the initial weight after printing.

[0446] Stability was also measured for color change over time by observing the color change after 4 weeks at room temperature.

[0447] Dimensional stability can be determined, for example, on a 60 x 24 x 18 mm coated ellipsoidal object coated with a 0.6 mm layer of an elastomeric curable material (e.g., Agilus family, e.g., Agilus 30 (trade name)), stored at 50°C for several days or at room temperature for one month, and observing the distortion in the object after storage.

[0448] Post-printing tack is determined quantitatively, for example for a printed object shaped as a cube, by applying tissue paper to the object and giving a rating on a scale of 0-3 as follows: 3 for when the tissue paper cannot be removed from the object, and 0 for when no fibers stick to the object once the tissue paper is removed.

[0449] In some of any of the embodiments described herein, the soft build material formulation as described herein is a curable formulation, and in some embodiments, the formulation is curable by including materials that are polymerizable when exposed to curing conditions (e.g., curing energy) as described herein. As described in more detail below, not all of the materials in a curable formulation should be curable to make the formulation curable. Thus, throughout this specification, with respect to any formulation described herein, the formulation is defined as being curable when at least one of the materials in the formulation is curable or polymerizable when exposed to curing conditions.

[0450] According to some of any of the embodiments described herein, the composition is a synthetic, non-living composition, consisting essentially of synthetic materials as defined herein.

[0451] According to some of any of the embodiments described herein, the formulation comprises water in an amount of less than 10% by weight, or less than 8% by weight, or less than 5% by weight, or even less than that, or is devoid of water as defined herein.

[0452] According to some of any of the embodiments described herein, the formulation is such that it does not form a hydrogel when exposed to curing conditions.

[0453] As used herein and in the industry, the term "hydrogel" describes a material that includes a three-dimensional fibrous network as a solid phase and further includes an aqueous solution trapped within the fibrous network.

[0454] Any formulation having a Shore hardness as indicated, preferably in combination with one or more, preferably all, of the other characteristics described herein, is contemplated in the additive manufacturing methods described herein.

[0455] According to some of any of the embodiments described herein, the soft build material includes a combination of a hardenable material and a non-hardenable polymeric material.

[0456] As used herein, "non-curable" with respect to a material in a soft formulation means that the material does not solidify when exposed to curing conditions that would cause a curable material to solidify. A non-curable material can be a material that lacks polymerizable and / or crosslinkable groups or that may contain polymerizable and / or crosslinkable groups but where polymerization and / or crosslinking is not effected when exposed to curing conditions that would cause a curable material to solidify.

[0457] In some embodiments, the non-curable material lacks polymerizable and / or crosslinkable groups.

[0458] Exemplary soft material formulations suitable for use in the present embodiments, meeting the process conditions, object conditions (e.g., having the hardness of soft body tissues described herein), and compatible with elastomeric curable formulations are provided below.

[0459] Such soft modeling formulations are obtained by manipulating the type and amount of non-curable material and the type and amount of curable material to impart properties such as printability, compatibility with other curable formulations, and mechanical properties of the printed object.

[0460] According to some of any of the embodiments described herein, the soft modeling material formulation includes a hardenable material and a non-hardenable material, and the total amount of the non-hardenable material ranges from about 10 to about 49% by weight, or from about 10 to about 30% by weight, of the total amount of the soft modeling formulation, including any intermediate values ​​and subranges therebetween.

[0461] In some embodiments, the total amount of non-hardenable polymeric material ranges from 20-40% by weight or 25-40% by weight of the total amount of the soft modeling compound, including any intermediate values ​​and subranges therebetween.

[0462] According to some of any of the embodiments described herein, the soft modeling material formulation includes a hardenable material and a non-hardenable material, and the ratio of the total amount of hardenable material to the total amount of non-hardenable material is in the range of 4:1 to 1.1:1, or 3:1 to 2:1, including any intermediate values ​​and subranges therebetween.

[0463] According to some of the embodiments described herein, the total amount of hardenable material is in the range of about 55 to about 70 weight percent of the total amount of the soft modeling compound, including any intermediate values ​​and subranges therebetween.

[0464] According to some of any of the embodiments described herein, the curable material includes at least one monofunctional curable material and at least one multifunctional curable material.

[0465] According to some of the embodiments described herein, the amount of monofunctional curable material ranges from about 50 to about 89 weight percent of the total amount of the soft material formulation, including any intermediate values ​​and subranges therebetween.

[0466] According to some of any of the embodiments described herein, the amount of multifunctional curable material ranges from about 1 to about 10 weight percent of the total soft material formulation, including any intermediate values ​​and subranges therebetween.

[0467] According to some of the any of the embodiments described herein, the soft build material formulations described herein include a monofunctional curable material, a multifunctional curable material, and a non-curable polymeric material.

[0468] In some of any of the embodiments described herein, the formulation comprises greater than 50% by weight of a curable material, i.e., the total amount of mono-functional and multi-functional curable materials is at least 51% by weight of the total amount of the formulation.

[0469] In some of any of the embodiments described herein, the total amount of mono- and multi-functional curable materials ranges from 51 to 90% or to 89% by weight of the total weight of the formulation, and in some embodiments, from 55 to 70% by weight, including any intermediate values ​​and subranges therebetween.

[0470] In some of any of the embodiments described herein, the total amount of monofunctional curable material ranges from 50 to 60 weight percent, or from 55 to 60 weight percent of the total amount of the formulation, including any intermediate values ​​and subranges therebetween.

[0471] In some of any of the embodiments described herein, the total amount of multifunctional curable material is in the range of 3-10% by weight, or 5-10% by weight, such as 7% by weight, of the total amount of the formulation, including any intermediate values ​​and subranges therebetween.

[0472] In some of any of the embodiments described herein, the total amount of non-curable materials ranges from 10 to 49% by weight, or 20 to 45% by weight, or 25 to 40% by weight of the total amount of the formulation, including any intermediate values ​​and subranges therebetween.

[0473] In some of the embodiments described herein, the formulation includes: a monofunctional curable material as described herein in any of the respective embodiments in an amount ranging from 50 to 89 weight percent of the total weight of the formulation, including any intermediate values ​​and subranges therebetween; a non-curable polymeric material as described herein in any of the respective embodiments in an amount ranging from 10 to 49 weight percent of the total weight of the formulation, including any intermediate values ​​and subranges therebetween; and A multifunctional curable material as described herein in any of the respective embodiments in an amount ranging from 1 to 10 weight percent of the total weight of the formulation, including any intermediate values ​​and subranges therebetween.

[0474] In some of any of the embodiments described herein, the ratio of the total amount of the monofunctional and the multifunctional curable materials to the non-curable polymeric material ranges from 4:1 to 1.1:1, or from 3:1 to 2:1, including any intermediate values ​​and subranges therebetween.

[0475] In some of the embodiments described herein, the curable and / or non-curable materials included in the formulation are selected as follows: (i) the non-curable polymeric material has a molecular weight of at least 1000, or at least 1500, or at least 2000 Daltons; and / or (ii) the non-curable polymeric material has a Tg of less than 0° C. or less than −10° C. or less than −20° C.; and / or (iii) at least 80 wt.% of the total amount of the monofunctional curable material and the multifunctional curable material comprises a curable material that, when cured, has a Tg of less than 0°C or less than -10°C or less than -20°C.

[0476] In some of the embodiments described herein, the curable and / or non-curable materials included in the formulation are selected as follows: the non-curable polymeric material has a molecular weight of at least 1000 or at least 1500 or at least 2000 Daltons, the non-curable polymeric material has a Tg of less than 0° C. or less than −10° C. or less than −20° C.; and / or At least 80 wt. % of the total amount of mono- and polyfunctional curable materials comprises a curable material that, when cured, has a Tg of less than 0°C or less than -10°C or less than -20°C.

[0477] In some of any of the embodiments described herein, the curable and / or non-curable materials included in the formulation are selected such that at least 80% by weight of the total amount of mono- and multi-functional curable materials comprises a curable material that, when cured, has a Tg of less than 0° C. or less than −10° C. or less than −20° C. In some such embodiments, at least 85% by weight, or at least 90% by weight, or at least 95% by weight, or 100% by weight of the total amount of mono- and multi-functional curable materials comprises a curable material that, when cured, has a Tg of less than 0° C. or less than −10° C. or less than −20° C.

[0478] In some of any of the embodiments described herein, the curable and / or non-curable materials included in the formulation are selected such that at least 80 wt.% of the total amount of mono- and multi-functional curable materials comprises a curable material that, when cured, has a Tg of less than -20°C.

[0479] In some of the embodiments described herein, the curable and / or non-curable materials included in the formulation are selected as follows:

[0480] The non-curable polymeric material, as described herein, has a molecular weight of at least 1000, or at least 1500, or at least 2000 Daltons, the non-curable polymeric material, as described herein, has a Tg of less than 0°C, or less than -10°C, or less than -20°C, and at least 80% by weight of the total mono- and multi-functional curable materials, when cured, as described herein, have a Tg of less than -20°C.

[0481] In some of the embodiments described herein, the curable and / or non-curable materials included in the formulation are selected as follows:

[0482] The non-curable polymeric material, as described herein, has a molecular weight of at least 2000 Daltons, the non-curable polymeric material, as described herein, has a Tg of less than -20°C, and at least 80 wt% of the total amount of mono- and poly-functional curable materials, as described herein, comprises a curable material that, when cured, has a Tg of less than 0°C, or less than -10°C, or less than -20°C.

[0483] Throughout this specification, "T g " denotes the glass transition temperature, defined as the location of the maximum in the E" curve, and E" is the loss modulus of the material as a function of temperature.

[0484] Roughly speaking, if the temperature is T g Upon increasing temperature within the range including the temperature, the state of the material, preferably a polymeric material, gradually changes from a glassy state to a rubbery state.

[0485] As used herein, "T g The range is defined as the range in which E" value is T as defined above. g A temperature range that is at least half that value (eg, can be less than or equal to that value).

[0486] Without wishing to be bound by any particular theory, it is believed that the state of the polymeric material is T g It is assumed that the glassy state gradually changes to the rubbery state within the range. g " means T as defined herein. g Any temperature within the range is indicated.

[0487] As used herein, the term "molecular weight," abbreviated as MW, when referring to a polymeric material, refers to the value known in the art as Mw, which describes the weight average molecular weight of a polymeric material.

[0488] Throughout this specification, whenever the term "wt %" or "weight percentage" or "% wt" is presented in the context of an embodiment of a molding compound, it means the weight percentage of the total weight of the respective uncured molding compound.

[0489] Non-curable polymeric materials: In some of any of the embodiments described herein, the non-curable material has a molecular weight of at least 500, or at least 1000, or at least 1500, or at least 2000 Daltons, for example a molecular weight in the range of 500-4000 or 900-1400, preferably 1000-4000 or 1500-4000, or more preferably 2000-4000 or 2500-4000 or 1500-3500 Daltons, including any intermediate values ​​and subranges therebetween.

[0490] In some of any of the embodiments described herein, the non-curable material has a Tg of less than 0° C. or less than −10° C. or less than −20° C., for example in the range of 0 to −40° C. or −20 to −40° C., including any intermediate values ​​and subranges therebetween.

[0491] In some of any of the embodiments described herein, the non-curable material has a molecular weight of at least 1000, or at least 1500, or at least 2000 Daltons, as described herein, and a Tg of less than 0° C., or less than −10° C., or less than −20° C., as described herein.

[0492] In some embodiments, the non-curable material has essentially the same properties (eg, molecular weight and / or Tg) in the build material formulation and in the resulting cured (soft) material upon curing.

[0493] As used herein, the term "polymeric" in reference to materials is inclusive of polymers and copolymers (including block copolymers).

[0494] As used herein, the term "block copolymer" describes a copolymer consisting of two or more different homopolymer blocks that differ in composition or structure, alternating in a regular or statistical manner. Each homopolymer block in a block copolymer represents one type of polymerized monomer.

[0495] Polymeric materials having the above-mentioned MW and / or Tg include, for example, polymers or block copolymers comprising one or more poly(alkylene glycols) as defined herein, including, for example, poly(ethylene glycol), poly(propylene glycol), and block copolymers thereof (e.g., pluronic® block copolymers).

[0496] In some of any of the embodiments described herein, the non-curable polymeric material includes polypropylene glycol.

[0497] In some embodiments, the non-curable polymeric material is poly(propylene glycol), which in some embodiments is polypropylene glycol having a MW of about 2000 Daltons or greater (e.g., 2000, 2200, 2400, 2500, 2600, 2800, or 3000 Daltons), including any intermediate values ​​and subranges therebetween.

[0498] In some embodiments, the non-curable polymeric material is a block copolymer comprising at least one polypropylene glycol block.

[0499] In some embodiments, the non-curable polymeric material is a block copolymer comprising one or more polypropylene glycol blocks and one or more polyethylene glycol blocks. Such a block copolymer can be, for example, PEG-PPG-PEG or PEG-PPG-PEG-PPG or PPG-PEG-PPG, or any other number of blocks in any combination and in any order.

[0500] In some of these embodiments, the total amount of poly(ethylene glycol) in the block copolymer is 10% by weight or less.

[0501] Thus, for example, in the exemplary block copolymers above, the length of the PEG blocks is such that the total amount of PEG is 10 wt% or less. As a representative, non-limiting example, a PEG-PPG-PEG block copolymer according to these embodiments comprises PEG(A wt%)-PPG(B wt%)-PEG(C wt%), where A+C≦10 and B≧90, e.g., A+C=10 and B=90, or A+C=7 and B=93, or A+C=5 and B=95. Similarly, a PPG-PEG-PPG block copolymer is PPG(A wt%)-PEG(B wt%)-PPG(C wt%), where A+C≧90 and B≦10, e.g., A+C=90 and B=10, or A+C=93 and B=7, or A+C=95 and B=5.

[0502] In some of any of the embodiments described herein, the block copolymer has a MW of at least 2000 Daltons.

[0503] In some of the embodiments described herein, the ratio of the number of polypropylene glycol blocks to the number of polyethylene glycol blocks is at least 1.2:1, or at least 1.5:1, or at least 2:1 for the PEG and PPG block copolymers. An exemplary such block copolymer is PPG-PEG-PPG. Another exemplary block copolymer is PPG-PEG-PPG-PEG-PPG.

[0504] Alternatively or additionally, in some of any of the embodiments described herein for PEG and PPG block copolymers, the ratio of the total number of polypropylene glycol backbone units to the total number of polyethylene glycol backbone units in the block copolymer is at least 2: 1, or at least 3: 1, or at least 4: 1, or at least 5: 1, or at least 6: 1. Exemplary such block copolymers are PEG-PPG-PEG copolymers or PEG-PPG-PEG-PPG or PEG-PPG-PEG-PPG-PEG having such ratios.

[0505] In some of any of the embodiments described herein, the non-curable material is characterized by having low solubility (e.g., 20% or less, or 10% or less, or less) or being insoluble in water.

[0506] In the context of these embodiments, the term "water solubility" describes the weight percent of a polymeric material that can be added to 100 grams of water before the solution becomes cloudy (opaque).

[0507] In some of any of the embodiments described herein, the non-curable material is characterized by having low miscibility (eg, less than 20% or less than 10% or less) or immiscibility in water.

[0508] Monofunctional polymer materials: In some of any of the embodiments described herein, the monofunctional curable material, when cured, has a Tg of less than -10°C or less than -20°C, for example in the range of 0 to -40°C or -20 to -40°C, including any intermediate values ​​and subranges therebetween.

[0509] In some of the embodiments described herein, monofunctional curable materials usable in the context of the present embodiments can be represented by the following formula: PR wherein P is a polymerizable group and R is a hydrocarbon, as described herein, which is substituted by one or more substituents, as described herein, and optionally interrupted by one or more heteroatoms.

[0510] In some of any of the embodiments described herein, P is a photopolymerizable group, and in some embodiments, it is a UV curable group, and thus the curable material is photopolymerizable or UV curable. In some embodiments, P is an acrylic polymerizable group, such as an acrylate, methacrylate, acrylamide, or methacrylamide, and such curable groups can be collectively represented by the following formula A: TIFF0007601964000001.tif37167 wherein at least one of R1 and R2 is and / or includes a hydrocarbon as defined herein.

[0511] The =CH2 group in formula I represents a polymerizable group, which according to some embodiments is a UV-curable group, and thus the monofunctional curable material is a UV-curable material.

[0512] In some embodiments, R1 is a carboxylate, R2 is hydrogen, and the compound is a monofunctional acrylate. In some embodiments, R1 is a carboxylate, R2 is methyl, and the compound is a monofunctional methacrylate. Curable materials in which R1 is a carboxylate and R2 is hydrogen or methyl are collectively referred to herein as "(meth)acrylates."

[0513] In some of these embodiments, the carboxylate group is -C(=O)-OR a It is expressed as R a is a hydrocarbon as described herein.

[0514] In some embodiments, R1 is amide, R2 is hydrogen, and the compound is a monofunctional acrylamide. In some embodiments, R1 is amide, R2 is methyl, and the compound is a monofunctional methacrylamide. Curable materials in which R1 is amide and R2 is hydrogen or methyl are collectively referred to herein as "(meth)acrylamides."

[0515] In some of any of these embodiments, the amide group is represented as -C(=O)-NRbRa, where each of Ra and Rb is independently selected from hydrogen and a hydrocarbon, and at least one is a hydrocarbon as described herein.

[0516] (Meth)acrylates and (meth)acrylamides are collectively referred to herein as (meth)acrylic materials.

[0517] When one or both of R1 and R2 include a polymeric or oligomeric moiety, the monofunctional curable compound of formula A is an exemplary polymeric or oligomeric monofunctional curable material, respectively. Otherwise, it is an exemplary monomeric monofunctional curable material.

[0518] Generally, the chemical composition of the hydrocarbon (R1, if present in formula A, is a PR formula, or Ra / Rb) determines whether the curable material and the cured materials formed therefrom are hydrophilic, hydrophobic, or amphiphilic.

[0519] The term "hydrophilic" as used throughout this specification describes the physical property of a material or a portion of a material (e.g., a chemical group in a compound) that is responsible for the temporary formation of bonds with water molecules, generally by hydrogen bonding.

[0520] A hydrophilic material dissolves more readily in water than in oil or other hydrophobic solvents. A hydrophilic material can be determined, for example, as having a LogP of less than 0.5 when the LogP is determined in octanol and water phases.

[0521] A hydrophilic material may alternatively or additionally be determined as having a lipophilic / hydrophilic balance (HLB) of at least 10, or at least 12, according to the Davies method.

[0522] The term "amphiphilic" as used throughout this specification describes the property of a material that combines both hydrophilic properties, as defined herein for hydrophilic materials, and hydrophobic or lipophilic properties, as defined herein for hydrophobic materials.

[0523] Amphiphilic materials generally contain both hydrophilic groups, as defined herein, and hydrophobic groups, as defined herein, and are substantially soluble in both water and water-immiscible solvents (oils).

[0524] Amphiphilic materials can be determined as having a LogP of 0.8 to 1.2, or about 1, when the LogP is determined in octanol and aqueous phases.

[0525] Amphiphilic materials may alternatively or additionally be determined as having a lipophilic / hydrophilic balance (HLB) of 3-12, or 3-9, according to the Davies method.

[0526] A hydrophilic material or portion of a material (eg, a chemical group in a chemical compound) is generally one that is charge polarized and capable of hydrogen bonding.

[0527] Amphiphilic materials generally contain one or more hydrophilic groups (eg, charge polarizable groups) in addition to a hydrophobic group.

[0528] Hydrophilic materials or groups, and amphiphilic materials generally contain one or more electron-donating heteroatoms that form strong hydrogen bonds with water molecules. Such heteroatoms include, but are not limited to, hydrogen and nitrogen. Preferably, the ratio of the number of carbon atoms to the number of heteroatoms in the hydrophilic material or group is 10:1 or less, such as 8:1, more preferably 7:1, 6:1, 5:1 or 4:1 or less. It should be noted that the hydrophilicity and amphiphilicity of materials and groups also result from the ratio between the hydrophobic and hydrophilic moieties in the material or chemical group, and do not depend only on the ratios shown above.

[0529] A hydrophilic or amphiphilic material can have one or more hydrophilic groups or moieties. Hydrophilic groups are generally polar groups that contain one or more electron-donating heteroatoms such as hydrogen and nitrogen.

[0530] Exemplary hydrophilic groups include, but are not limited to, electron donating heteroatoms, carboxylates, thiocarboxylates, oxo (=O), linear amides, hydroxy, (C1-4)alkoxy, (C1-4)alcohols, heteroalicyclics (e.g., having a ratio of carbon atoms to heteroatoms as defined herein), cyclic carboxylates such as lactones, cyclic amides such as lactams, carbamates, thiocarbamates, cyanurates, isocyanurates, thiocyanurates, ureas, thioureas, alkylene glycols (e.g., ethylene glycol or propylene glycol), and hydrophilic polymeric or oligomeric moieties (these terms are defined below), and combinations thereof (e.g., hydrophilic groups comprising two or more of the indicated hydrophilic groups).

[0531] In some embodiments, the hydrophilic group is or includes an electron donating heteroatom, a carboxylate, a heteroalicyclic, an alkylene glycol, and / or a hydrophilic oligomeric moiety.

[0532] Amphiphilic moieties or groups generally contain one or more hydrophilic groups and one or more hydrophobic groups as described herein, or can be heteroatom-containing groups or moieties where the ratio of the number of carbon atoms to the number of heteroatoms is responsible for the amphiphilic nature.

[0533] The hydrophilic or amphiphilic monofunctional curable material according to some embodiments of the present invention can be a hydrophilic acrylate represented by the following formula A1: TIFF0007601964000002.tif42166, wherein R1 and R2 are as defined herein and at least one of R1 and R2 is and / or includes a hydrophilic or amphiphilic moiety or group as defined herein.

[0534] In some of these embodiments, the carboxylate group -C(=O)-ORa includes a hydrophilic or amphiphilic moiety or group, as defined herein. Exemplary R groups in the context of these embodiments include, but are not limited to, heteroalicyclic groups (having a carbon atom to electron donating heteroatom ratio of 10:1 or 8:1 or 6:1 or 5:1 or lower, such as morpholine, tetrahydrofuran, oxalidine, etc.), hydroxyl, (C1-4)alkoxy, thiol, alkylene glycol, or a hydrophilic or amphiphilic polymer or oligomer moiety, as described herein. An exemplary hydrophilic monofunctional acrylate is acryloylmorpholine (ACMO).

[0535] Exemplary hydrophilic or amphiphilic oligomeric monofunctional curable materials include, but are not limited to, mono(meth)acrylated urethane oligomer derivatives of polyethylene glycol, mono(meth)acrylated polyol oligomers, mono(meth)acrylated oligomers with hydrophilic substituents, mono(meth)acrylated polyethylene glycols (e.g., methoxypolyethylene glycols), and mono-urethane acrylates.

[0536] In some embodiments, R a in formula A1 is or includes a poly(alkylene glycol), as defined herein.

[0537] In some embodiments, R in Formula A1 comprises both amphiphilic groups or moieties and hydrophobic groups or moieties as defined herein, such materials being referred to herein as amphiphilic curable materials comprising hydrophobic groups or moieties.

[0538] The term "hydrophobic" as used throughout this specification describes the physical property of a material or a portion of a material (e.g., a chemical group or moiety in a compound) due to its temporary lack of forming bonds with water molecules and thus its immiscibility in water, but which is miscible or soluble in hydrocarbons.

[0539] A hydrophobic material or portion thereof (eg, a chemical group or moiety in a chemical compound) is one that is generally not charged or charge polarized and does not have a tendency to form hydrogen bonds.

[0540] The hydrophobic material or group generally comprises one or more of alkyl, cycloalkyl, aryl, alkaryl, alkene, alkynyl, etc., which is unsubstituted or which, when substituted, is substituted with one or more of alkyl, cycloalkyl, aryl, alkaryl, alkenyl, alkynyl, etc., or other substituents, such as electron donor atom-containing substituents, but the ratio of the number of carbon atoms to the number of heteroatoms in the hydrophobic material or group is at least 10:1, such as 12:1, and more preferably 15:1, 16:1, 18:1 or 20:1 or higher.

[0541] A hydrophobic material dissolves more readily in oil than in water or other hydrophilic solvents. A hydrophobic material can be determined, for example, as having a LogP greater than 1 when the LogP is determined in octanol and water phases.

[0542] A hydrophobic material may alternatively or additionally be determined as having a lipophilic / hydrophilic balance (HLB) of less than 9, preferably less than 6, according to the Davies method.

[0543] A hydrophobic material can have one or more hydrophobic groups or moieties that render the material hydrophobic. Such groups or moieties are generally non-polar groups or moieties as described above.

[0544] In some embodiments, the hydrophobic group or moiety is or includes a hydrocarbon as defined herein, preferably of at least 6 atoms, such as an alkylene chain of at least 6 carbon atoms in length. When the hydrocarbon is substituted or interrupted by a heteroatom or heteroatom-containing group, the ratio of the number of carbon atoms to the number of heteroatoms given above applies.

[0545] The hydrophobic monofunctional curable material according to some embodiments of the present invention can be a hydrophobic group acrylate represented by formula A2 below. TIFF0007601964000003.tif42163, wherein R1 and R2 are as defined herein and at least one of R1 and R2 is and / or includes a hydrophobic group or moiety as defined herein.

[0546] In some of any of these embodiments, the carboxylate group -C(=O)-ORa comprises a hydrophobic group Ra as defined herein. Exemplary hydrophobic monofunctional acrylates are isodecyl acrylate, lauryl acrylate, stearyl acrylate, linolenyl acrylate, bisphenyl acrylate, and the like.

[0547] In some embodiments, R a in formula A2 is or includes an alkylene chain, preferably unsubstituted, of at least 6 carbon atoms in length.

[0548] In some of any of the embodiments described herein, the monofunctional curable material includes a hydrophobic monofunctional curable material.

[0549] In some of these embodiments, the hydrophobic monofunctional curable material is a hydrophobic monofunctional acrylate, which is also referred to herein as a "monofunctional acrylate Type II."

[0550] In some of any of the embodiments described herein, the monofunctional curable material includes a hydrophilic or amphiphilic monofunctional curable material.

[0551] In some of any of the embodiments described herein, the monofunctional curable material includes an amphiphilic monofunctional curable material.

[0552] In some of these embodiments, the amphiphilic monofunctional curable material is an amphiphilic monofunctional acrylate that does not contain a hydrophobic group as described herein, which is also referred to herein as "monofunctional acrylate Type I."

[0553] In some of any of the embodiments described herein, the monofunctional curable material comprises an amphiphilic monofunctional curable material that includes a hydrophobic moiety or group as described herein, which is also referred to herein as a "monofunctional acrylate Type II."

[0554] In some of any of the embodiments described herein, the monofunctional curable material includes a combination of an amphiphilic monofunctional curable material and a hydrophobic monofunctional curable material (e.g., a combination of a monofunctional acrylate type I and a monofunctional acrylate type II).

[0555] In some of these embodiments, the weight ratio of the amphiphilic monofunctional curable material to the hydrophobic monofunctional curable material ranges from 2:1 to 1:2, preferably from 2:1 to 1:1 or from 1.5:1 to 1:1 or from 1.5:1 to 1.1:1, including any intermediate values ​​and subranges therebetween.

[0556] In some of any of the embodiments described herein, the monofunctional curable material includes a combination of a hydrophobic monofunctional acrylate and an amphiphilic monofunctional acrylate that includes a hydrophobic group as described herein (e.g., a combination of two monofunctional acrylates of Type II).

[0557] In some of these embodiments, the weight ratio of the amphiphilic monofunctional curable material to the hydrophobic monofunctional curable material ranges from 2:1 to 1:2, preferably from 2:1 to 1:1 or from 1.5:1 to 1:1 or from 1.5:1 to 1.1:1, including any intermediate values ​​and subranges therebetween.

[0558] In some of any of the embodiments described herein, the monofunctional curable material comprises an amphiphilic monofunctional acrylate (e.g., a Type II monofunctional acrylate) that includes a hydrophobic group as described herein.

[0559] In some of any of the embodiments described herein, the monofunctional curable material is such that when cured, it has a Tg of less than 0° C., preferably less than −10° C. or less than or equal to −20° C. (e.g., in the range of −20 to −70° C.) When the monofunctional curable material comprises a combination of two or more materials, at least one of those materials when cured has a low Tg as described herein, and optionally and preferably all of the materials have such a Tg.

[0560] Further embodiments of monofunctional curable materials are described below.

[0561] Multifunctional curable material As described herein, a multifunctional curable material is a monomeric, oligomeric, or polymeric curable material that has two or more polymerizable groups. Such materials are also referred to herein as crosslinkers.

[0562] According to some of the embodiments described herein, the multifunctional curable material is a difunctional curable material, which provides a low degree of crosslinking and thereby a low hardness of the cured material.

[0563] According to some of any of the embodiments described herein, the multifunctional curable material, when cured, can have a Tg of less than -10°C or less than -20°C, for example, in the range of -10 to -70°C.

[0564] Exemplary multi-functional curable materials according to some embodiments of the present invention can be represented by Formula B: TIFF0007601964000004.tif47166 wherein each of R3, R4 and R5 is independently hydrogen or C(1-4)alkyl; L1 is a linking moiety, a branching unit or moiety (when n is greater than 1), or absent; L2 is a linking moiety, a branching unit or moiety (when k is other than 0), or absent; L3 is a linking moiety, a branching unit or moiety (when m is greater than 1), or absent; Each of P1 and P2 is independently a hydrocarbon or oligomeric or polymeric group or moiety, as these terms are defined herein, or absent; Each of X1, X2, and X3 is independently a carboxylate, an amide, or absent; Each of n, m, and k is 0, 1, 2, 3, or 4; However, n+m+k is at least 2.

[0565] A multifunctional curable material of formula II where one, two or all of X1, X2 and X3 (when present) are carboxylates is a multifunctional acrylate. When one or more of R3, R4 and R5 (when present) are methyl, the curable material is a multifunctional methacrylate.

[0566] Multifunctional curable materials in which one, two or all of X1, X2 and X3 (when present) are carboxylates can contain a combination of acrylate and methacrylate functional moieties.

[0567] In some embodiments, the acrylate or methacrylate multifunctional curable material is a monomer, and thus neither P1 nor P2 is a polymeric or oligomeric moiety. In some of these embodiments, one or both of P1 and P2 is a hydrophilic or amphiphilic group as described herein, such as an alkylene group or any other hydrophilic or amphiphilic linking group, or a short chain (e.g., having 1 to 6 carbon atoms), substituted or unsubstituted hydrocarbon moiety as defined herein.

[0568] In some embodiments, one or both of P1 and P2 are polymeric or oligomeric moieties as defined herein, and the curable compound is an oligomeric multifunctional curable material, such as an oligomeric multifunctional acrylate or methacrylate, as described herein for X1, X2, and / or X3. If both P1 and P2 are present, L2 can be a linking moiety, such as a hydrocarbon, including, for example, alkyl, cycloalkyl, aryl, and any combination thereof. Exemplary such curable materials include ethoxylated or methoxylated polyethylene glycol diacrylate, and ethoxylated bisphenol A diacrylate.

[0569] Other non-limiting examples include polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol-polyethylene glycol urethane diacrylate, acrylated oligourethane, and partially acrylated polyol oligomers.

[0570] In some embodiments, one or more of P1 and P2 is or includes a poly(alkylene glycol) moiety, as defined herein.

[0571] Exemplary multifunctional acrylates are described in the Examples section below.

[0572] In some of any of the embodiments described herein, the monofunctional curable material and the multifunctional curable material are curable when exposed to the same curing conditions.

[0573] In some embodiments, the monofunctional curable material and the multifunctional curable material are both photopolymerizable, and in some embodiments, both are UV curable.

[0574] In some embodiments, the monofunctional curable material and the multifunctional curable material are both acrylic compounds, and in some embodiments, both (meth)acrylates or both acrylates.

[0575] Initiator: In some of any of the embodiments described herein, the soft build material formulation further comprises one or more agents that promote polymerization of the hardenable material, referred to herein as initiators.

[0576] In some of the embodiments described herein, the curable material and the initiator as described herein together form a curable system, which may further include an inhibitor as described below.

[0577] It should be noted that compounds / agents that form part of a hardenable system, even if they are not themselves hardenable, should not be considered herein as non-hardenable materials, much less as non-hardenable polymeric materials as described herein.

[0578] In some of any of the embodiments described herein, a "curable system" includes one or more curable materials, and optionally one or more initiators and / or catalysts for initiating the curing of the curable materials, and further optionally one or more conditions for inducing curing (also referred to herein as cure conditions) as described herein.

[0579] One or more initiators are selected according to the selected hardenable material. Typically, the initiator is also selected according to the polymerization type of the hardenable material. For example, a free radical initiator is selected to initiate free radical polymerization (such as in the case of an acrylic hardenable material), a cationic initiator is selected to initiate cationic polymerization, etc. Additionally, a photoinitiator is used when one or more of the hardenable materials are photopolymerizable.

[0580] In some of any of the embodiments described herein, the hardenable system is a photohardenable system and the initiator is a photoinitiator.

[0581] In some embodiments, the hardenable system includes an acrylic compound and the photoinitiator is a free radical photoinitiator.

[0582] A free radical photoinitiator can be any compound that generates free radicals when exposed to radiation, such as ultraviolet or visible radiation, thereby initiating a polymerization reaction. Non-limiting examples of suitable photoinitiators include benzophenones (aromatic ketones), such as benzophenone, methylbenzophenone, Michler's ketone, and xanthone; acylphosphine oxide type photoinitiators, such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TMPO), 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide (TEPO), and bisacylphosphine oxide (BAPO); benzoin and benzoin alkyl ethers, such as benzoin, benzoin methyl ether, and benzoin isopropyl ether, and the like. Examples of photoinitiators are alpha-aminoketones, and bisacylphosphine oxides (BAPO). Further examples include the Irgacure® family of photoinitiators.

[0583] Free radical photoinitiators can be used alone or in combination with coinitiators. Coinitiators are used with initiators that require a second molecule to generate radicals that are active in photocurable free radical systems. Benzophenone is an example of a photoinitiator that requires a second molecule, such as an amine, to generate free radicals. After absorbing radiation, benzophenone reacts with tertiary amines by hydrogen abstraction to generate alpha-amino radicals that start the polymerization of acrylates. Non-limiting examples of coinitiators are alkanolamines such as triethylamine, methyldiethanolamine, and triethanolamine.

[0584] In some of any of the embodiments described herein, the modeling material formulation includes a free radical curable system and further includes a radical inhibitor to prevent or slow down polymerization and / or hardening prior to exposure to curing conditions.

[0585] In some of any of the embodiments described herein, the hardenable systems are polymerizable or hardened by cationic polymerization, and are referred to herein as cationically polymerizable or cationically hardenable systems.

[0586] In some embodiments, the cationically polymerizable material is photopolymerizable or curable by exposure to radiation. Systems including such materials can be referred to as photopolymerizable cationic systems, or photoactivatable cationic systems.

[0587] In some embodiments, the cationically curable system further comprises a cationic initiator, which generates cations to initiate polymerization and / or curing.

[0588] In some embodiments, the initiator is a cationic photoinitiator, which generates cations upon exposure to radiation.

[0589] Suitable cationic photoinitiators include, for example, compounds that form aprotic or Bronsted acids upon exposure to sufficient ultraviolet and / or visible light to initiate polymerization. The photoinitiator used can be a single compound, a mixture of two or more active compounds, or a combination of two or more different compounds, i.e., coinitiators. Non-limiting examples of suitable cationic photoinitiators include aryl diazonium salts, diaryliodonium salts, triaryl sulfonium salts, triaryl selenonium salts, and the like. An exemplary cationic photoinitiator is a mixture of triarylsorphonium hexafluoroantimonate salts.

[0590] Non-limiting examples of suitable cationic photoinitiators include P-(octyloxyphenyl)phenyl iodonium hexafluoroantimonate (UVACURE 1600 from Cytec Company, USA), iodonium (4-methylphenyl)(4-(2-methylpropyl)phenyl)-hexafluorophosphate known as Irgacure 250 or Irgacure 270 available from Ciba Speciality Chemicals, Switzerland, mixed arylsulfonium hexafluoroantimonate salts known as UVI 6976 and 6992 available from Lambson Fine Chemicals, UK, diaryl iodonium hexafluoroantimonate known as PC 2506 available from Polyset Company, USA, (tolylcumyl) iodonium tetrakis(pentafluorophenyl)borate known as Rhodorsil photoinitiator 2074 available from Bluestar Silicones, USA, Tego Photoinitiator 2074 from Evonik Industries AG, Germany, and the like. Includes iodonium bis(4-dodecylphenyl)-(OC-6-11)-hexafluoroantimonate, known as PC1466.

[0591] In some of any of the embodiments described herein, the amount of initiator (e.g., free radical photoinitiator) ranges from 1 to 5 wt.% or 1 to 3 wt.%, including any intermediate values ​​and subranges therebetween. In exemplary embodiments, two or more initiators (e.g., photoinitiators) are used, each in an amount ranging from 1 to 3 wt.%.

[0592] Additional Ingredients: According to some of any of the embodiments described herein, the soft build material further comprises additional non-hardening components, such as inhibitors, surfactants, dispersants, colorants, and stabilizers. Commonly used surfactants, dispersants, colorants, and stabilizers are contemplated. Exemplary concentrations of each component (if present) range from about 0.01% to about 1% by weight, or from about 0.01% to about 0.5% by weight, or from about 0.01% to about 0.1% by weight of the total weight of the formulation containing it. Exemplary components are described below.

[0593] In some of any of the embodiments described herein, the formulation includes a cure inhibitor, i.e., an agent that inhibits or reduces the amount of cure in the absence of curing conditions. In some embodiments, the inhibitor is a free radical polymerization inhibitor. In some embodiments, the amount of inhibitor (e.g., free radical inhibitor) is in the range of 0.01-2, or 1-2, or 0.05-0.15 wt%, or 0.1 wt%, including any intermediate values ​​and subranges therebetween, depending on the type of inhibitor used. Commonly used inhibitors, such as radical inhibitors, are contemplated.

[0594] In exemplary embodiments, a free radical inhibitor such as NPAL, or its equivalent, is used in an amount ranging from 0.01 to 1, or 0.05 to 2, or 0.05 to 0.15 wt %, or 0.1 wt %.

[0595] In an alternative embodiment, a free radical inhibitor lacking a nitro or nitroso group is used. Exemplary such inhibitors are those of the Genorad™ family (e.g., Genorad 18).

[0596] In exemplary embodiments, such free radical inhibitors are used in amounts of 0.1-3, or 0.1-2, or 0.5-2, or 1-1.5 wt %, including any intermediate values ​​and subranges therebetween.

[0597] In an exemplary embodiment, the soft build material formulation includes a surfactant. An exemplary surfactant is sold as BYK Interfacial Additive. In some embodiments, the surfactant is a curable material, preferably curable upon exposure to the same curing conditions as the curable material in the formulation. In some embodiments, the surfactant is a UV curable surfactant, and in some embodiments, the surfactant is a UV curable BYK surfactant (e.g., BYK UV-3150 or BYK UV-3500).

[0598] In some embodiments, the amount of surfactant in the formulation ranges from 0.1 to 1% by weight, as described herein.

[0599] Exemplary soft molding compounds: In some of any of the embodiments described herein, the soft modeling material formulation includes a non-curable polymeric material as described herein and an acrylic curable system including a monofunctional acrylate (e.g., a combination of an amphiphilic and a hydrophobic monofunctional acrylate), a free radical photoinitiator, and optionally a free radical inhibitor.

[0600] In some embodiments, the formulation further comprises one or more additional ingredients as described herein.

[0601] In some embodiments, the formulation further comprises a colorant as described herein, for example, to impart a red, fleshy color to the formulation, or to impart a skin or skin pigment color to the formulation and to an object or portion thereof made therefrom. Exemplary fleshy colors suitable for use in acrylic materials include, but are not limited to, those manufactured by Prosthetic Research Specialists, Inc. and sold by Kingsley Mfg. Co. under the term "Flesh color system."

[0602] In some embodiments, the concentration of the tint depends on the intended use of the formulation and the desired visual properties of the object, and ranges from 0.01 to 5, or 0.01 to 1, or 0.1 to 1 weight percent, including any intermediate values ​​and subranges therebetween.

[0603] In some of the embodiments described herein, the soft build material formulation comprises: a monofunctional amphiphilic acrylate as described herein in any of the respective embodiments in an amount of 25 to 35 wt.%; a monofunctional hydrophobic acrylate as described herein in any of the respective embodiments in an amount of 25 to 30 wt.%; a monofunctional acrylate as described herein in any of the respective embodiments in an amount of 5 to 10 wt. %; and A non-curable polymeric material as described herein in any of the respective embodiments in an amount of 30-35% by weight, having a molecular weight of at least 1000, or at least 1500, or at least 2000 Daltons, and a Tg of less than 0° C., or less than −10° C., or less than −20° C.

[0604] In some of these embodiments, the non-curable polymeric material comprises polypropylene glycol and / or a block copolymer comprising at least one polypropylene glycol block, each having a molecular weight of at least 2000 Daltons, as described herein in any of the respective embodiments.

[0605] In some of these embodiments, the monofunctional acrylate is a difunctional acrylate, and in some embodiments it is a urethane diacrylate.

[0606] In some of these embodiments, the monofunctional amphiphilic acrylate comprises a hydrocarbon chain of at least 6 carbon atoms and at least two alkylene glycol groups.

[0607] In some of these embodiments, the monofunctional hydrophobic acrylate comprises a hydrocarbon chain of at least 8 carbon atoms.

[0608] Exemplary formulations are given below.

[0609] According to some of any of the embodiments described herein, the uncured build material comprises two or more soft modeling material formulations as described herein, each comprising a different combination of curable and non-curable materials according to the present embodiments, and optionally each having a different Shore A hardness value in the range of 1-10 and / or a different Shore OO hardness value in the range of 0-40 when cured.

[0610] In some embodiments, the two or more build material formulations represent a formulation system of soft molding formulations.

[0611] Table 1.1 below provides an exemplary formulation according to the present embodiments, which exhibits a Shore scale A hardness of 0 and a Shore OO hardness of 0 to about 40, as described herein.

[0612] The expression "monofunctional acrylate type I" used in Table 1.1 includes monofunctional hydrophilic or hydrophilic amphiphilic acrylates, particularly one or more monomeric, oligomeric, or polymeric curable materials having an acrylate group as a polymerizable group and one or more heteroatoms (e.g., O, N, or both) or heteroatom-containing groups (e.g., carboxylates, amides, alkylene glycols, and combinations thereof) that impart hydrophilic or amphiphilic properties. See also Formula A1, where R1 is C(=O)-O-Ra, where Ra is a hydrophilic or amphiphilic moiety that does not include a hydrophobic group or moiety as described herein. Exemplary materials include alkoxy-terminated poly(ethylene glycol) acrylates (e.g., sold as AM130); urethane acrylates (e.g., sold as Genomer®, e.g., Genomer 1122); acryloyl morpholine, and any of the other respective curable materials described herein.

[0613] The expression "monofunctional acrylate type II" encompasses one or more monomeric, oligomeric or polymeric, preferably monomeric, hydrophobic or hydrophobic amphiphilic curable materials comprising an acrylate group as a polymerizable group and at least one hydrophobic moiety or group (e.g. a hydrocarbon of at least 6 carbon atoms in length as defined herein). See also formula A2, where R1 is C(=O)-O-Ra, where Ra is or comprises a hydrophobic moiety or group.

[0614] Exemplary such materials include compounds of formula A1 as described herein having as Ra groups nonyl, phenyl, isodecyl, and / or lauryl groups, optionally in combination with alkylene glycol groups, such as those sold by Sartomer as SR395; SR504D, SR335, SR7095, etc.

[0615] The expression "non-curable polymeric material" as used in the Examples section of this specification includes one or more polymeric materials, preferably amphiphilic, that lack polymerizable acrylate groups or any other polymerizable groups that contribute to polymerization when exposed to conditions that initiate acrylate polymerization (e.g., lack photopolymerizable groups or groups that polymerize when exposed to radiation of wavelengths that induce acrylate polymerization).Preferably, the non-curable polymeric material comprises one or more block copolymers of PEG and PPG, also known under the trade name "Pluronic®", with various Tg values ​​when cured, and in any order and number of blocks at any MW. Preferably, the non-curable polymeric material comprises one or more block copolymers of PEG and PPG, such as PEG-PPG-PEG and PPG-PEG-PPG, which comprise 10% by weight or less PEG and a PEG / PPG ratio as described herein, have a MW of at least 500, preferably at least 900, more preferably at least 2000 Daltons, and / or when cured, have a Tg of less than 20° C., preferably less than 0° C., more preferably less than −20° C., as described herein. Preferably, these materials are characterized by low solubility (e.g. less than 20% or less than 10% or less) or insolubility in water.

[0616] The expression "multifunctional acrylate" as used in the Examples section of this specification includes one or more monomeric, oligomeric or polymeric curable materials having two or more polymerizable acrylate groups. Such materials are also referred to herein as crosslinkers. Exemplary such materials include, but are not limited to, urethane diacrylates, such as those sold as Ebecryl 230; aliphatic di-, tri-, or tetraacrylates, such as trimethylolpropane triacrylate, optionally ethoxylated (e.g., Photomer 4072, Photomer 4158, Photomer 4149, Photomer 4006, Miramer M360, SR499), glyceryl triacrylate, pentaerythritol tetraacrylate, optionally ethoxylated (e.g., sold as Photomer 4172), hexanediol diacrylate, PEGDA, and also epoxy diacrylates, such as those sold as Photomer 3005, Photomer 3015, Photomer 3016, Photomer 3316. Preferably, the multifunctional acrylate, when cured, has a Tg of less than 20° C. or less than 0° C. or less.

[0617] The term "polysiloxane" encompasses non-curable organic and inorganic materials containing a polysiloxane backbone, including, by way of non-limiting example, PDMS and its derivatives and block copolymers containing same.

[0618] The terms "photoinitiator" and "inhibitor" are as defined herein.

[0619] All of the formulations given in Table 1.1 contain one or more photoinitiators in amounts ranging from 1 to 5 wt % (e.g., 3 wt %).

[0620] Exemplary photoinitiators include those from the Irgacure® family, such as I819, I184, and combinations thereof.

[0621] All formulations given in Table 1.1 include one or more inhibitors (free radical polymerization inhibitors) in amounts ranging from 0.01 to 1 wt %, e.g., 0.1 wt %. Exemplary inhibitors include tris(N-nitroso-N-phenylhydroxylamine) aluminum salts (NPAL) and the Genorad family of inhibitors, e.g., G18.

[0622] Some of the formulations given in Table 1.1 further include additional non-reactive ingredients (additives) as described herein.

[0623] In the exemplary formulation (BM219), a UV curable surfactant (BYK UV-3500 - a polyether modified acryl functional polydimethylsiloxane) is used.

[0624] TIFF0007601964000005.tif227166TIFF0007601964000006.tif184166

[0625] Additional exemplary formulations were made that contained a multifunctional acrylate other than a urethane diacrylate in an amount of 1-3 wt % and / or contained a polysiloxane compound in an amount of 5-10 wt %, all having a Shore A hardness of 0.

[0626] Example 2 liquid material formulation Build material formulations that result in a liquid or liquid-like material upon exposure to curing conditions are also referred to herein as liquid build material formulations or liquid material formulations or liquid formulations or formulations L. In some embodiments, such formulations are intended to remain liquid or to form a liquid-like material upon ejection and exposure to curing conditions.

[0627] According to an embodiment of the present invention, formulation L is such as to provide a liquid or liquid-like material, as defined herein.

[0628] The liquid build material formulation can include one or more formulations, each formulation including one or more non-curable materials in an amount of at least 50% by weight, preferably at least 60% by weight, or at least 70% by weight, or at least 80% by weight, or at least 90% by weight, or 100% by weight of the total weight of the second build material formulation.

[0629] Because a liquid material formulation is primarily composed of non-hardenable materials, when it is exposed to hardening conditions it undergoes minimal or essentially no hardening (e.g., 20% or less by weight of the material hardens, e.g., polymerizes), and thus maintains essentially the same fluidity or viscosity as the jetted formulation, such that the resulting material upon exposure to hardening conditions is a liquid or liquid-like material as defined herein.

[0630] In some of any of the embodiments described herein, one or more of the components in the liquid material build formulation are such that, when exposed to curing conditions, they result in a liquid or liquid-like material having a viscosity of 10,000 centipoise or less, or 1,000 centipoise or less, or 100 centipoise or less, for example, 10 to 50 centipoise.

[0631] In some of any of the embodiments described herein, the liquid build material formulation (Formulation L) has a viscosity that differs from the viscosity of the liquid or liquid-like material (Material L) by no more than 20%, preferably no more than 10%. Thus, there is minimal (e.g., no more than 10%) or no change in viscosity or flowability of the liquid build material formulation when exposed to curing conditions.

[0632] In the case of liquid build material formulations, in some of any of the embodiments described herein, the non-curable material is or includes a polymeric material, and in some embodiments, the polymeric material is or includes one or more amphiphilic and / or hydrophilic polymers.

[0633] In the case of liquid build material formulations, in some of any of the embodiments described herein, the non-curable material is or includes a poly(alkylene glycol) as defined herein. The non-curable material can be a poly(alkylene glycol) itself or can include one or more poly(alkylene glycol) chains or blocks.

[0634] In some of any of the embodiments described herein, the non-curable material comprises a poly(alkylene glycol) having a molecular weight of less than 2000 grams / mole, and in some embodiments, the poly(alkylene glycol) is a polymer having a molecular weight of 200-2000, or 200-1000, or 200-800, or 200-600, or 400 grams / mole.

[0635] In some of the embodiments described herein, the poly(alkylene glycol) is poly(ethylene glycol). Alternatively, it is poly(propylene glycol).

[0636] Other non-curable materials suitable for inclusion in the liquid build material formulation instead of, or in addition to, the poly(alkylene glycols) described herein include, but are not limited to, block copolymers containing one or more poly(alkylene glycol) blocks, such as block copolymers of poly(ethylene glycol) and poly(propylene glycol), such as those commercially available under the trade name Pluronic®, diols (e.g., propane diol), glycerol, and polyols, such as higher polyols.

[0637] Additional non-curing materials suitable for inclusion in the liquid formulation, Formulation L, include one or more oils, such as, but not limited to, one or more of vegetable oils, synthetic oils, hydrocarbon oils, silicone oils, fatty acids, mineral oils, and paraffin oils. In some embodiments, the oil has any of the properties or viscosities described herein as characterizing Material L.

[0638] In some of any of the embodiments described herein, the liquid construction formulation further comprises water.

[0639] In some of the embodiments described herein, the liquid build formulations include a curable material, optionally in combination with a non-curable material, but lack a catalyst or initiator that promotes the curing (e.g., polymerization) of the curable material. In such embodiments, there is minimal or no curing of the liquid build formulation when exposed to curing conditions, and the liquid or liquid-like material formed has flow properties similar to those of the liquid build formulations described herein.

[0640] In some of the embodiments described herein, the liquid material (material L) is characterized by a shear modulus of less than 20 kPa, or less than 15 kPa, or less than 10 kPa, or less than 5 kPa, and thus has the consistency of a very soft, flowable gel. Formulations resulting in such materials are also referred to herein as formulations resulting in liquid-like materials.

[0641] In some of these embodiments, the liquid build material formulation includes a curable material, optionally and preferably in combination with a non-curable material as described herein in any of the respective embodiments.

[0642] According to some of these embodiments, the hardenable material is or includes a monofunctional hardenable material as defined herein.

[0643] Preferably, the curable material is in an amount of 50% by weight or less of the total weight of the liquid material formulation, preferably 40% by weight or less, or 30% by weight or less, or 20% by weight or less, and even 15% by weight, 10% by weight or less, hi some embodiments, the amount of curable material in the liquid build material formulation ranges from 10 to 25 percent by weight.

[0644] According to some of the embodiments described herein, the curable material is amphiphilic or hydrophilic (eg, as described in Example 1 herein).

[0645] In accordance with some of any of the embodiments described herein, the hardenable material is one that upon hardening provides a water-soluble or water-miscible material as defined herein.

[0646] According to some of the embodiments described herein, the curable material is such that upon curing, it results in a shear thinning material and / or a thixotropic material and / or a thermally thinning material as defined herein.

[0647] Exemplary liquid build material formulations include those comprising a poly(alkylene glycol) as described herein in an amount of at least 50% by weight and up to 100% by weight, optionally in combination with a total of 10-25% by weight of one or more curable materials as described herein, and further optionally in combination with additional components as described herein.

[0648] Exemplary liquid formulations L include formulations comprising one or more oils described herein in an amount of at least 50% by weight and up to 100% by weight, optionally in combination with a total of 10-25% by weight of one or more hardenable materials described herein, and further optionally in combination with additional components described herein.

[0649] Generally, in some embodiments, the liquid build material formulation is selected such that the liquid or liquid-like material is water-soluble or water-miscible as defined herein.

[0650] In some embodiments, the liquid material is water-miscible and the liquid-like material is water-soluble.

[0651] Generally, in some embodiments, the liquid build material formulation is selected such that the liquid or liquid-like material (material L) is a shear-thinning material as defined herein.

[0652] Generally, in some embodiments, the liquid build material formulation is selected such that the liquid or liquid-like material (material L) is a thixotropic material as defined herein.

[0653] Generally, in some embodiments, the liquid build material formulation is selected such that the liquid or liquid-like material (material L) is a thermally thinning material as defined herein.

[0654] In some of any of the embodiments described herein, the uncured build material comprises two or more liquid build material formulations described herein, e.g., one or more formulations that provide a liquid material having about the same viscosity as the uncured formulations described herein and that include a non-curable material, and one or more formulations that provide a liquid-like material having a shear stress of 20 kPa or less as described herein and that include a curable material and a non-curable material as described herein.

[0655] In some of these embodiments, the ejection is performed such that small hollow structures, characterized by at least one dimension on the millimeter scale as defined herein, are filled with a formulation that results in a liquid material, and larger hollow structures are filled with a formulation that results in a liquid-like material.

[0656] As the liquid build material formulation described in this example is dispensed and reformulated, the AM system optionally and preferably ensures, e.g., by a controller, that the newly dispensed layer is in a still air environment.

[0657] As used herein, "still air environment" refers to an environment in which there is no air flow or where the air is flowing at a speed of less than 3 m / s.

[0658] Example 3 Elastomer Curable Materials Throughout this specification, the term "elastomeric curable formulation," also referred to herein as an "elastomeric molding material formulation," an "elastomeric molding formulation," or simply an "elastomeric formulation," describes a formulation that, when cured, possesses the properties of a rubber or rubber-like material, which is also referred to herein and in the industry as an elastomer.

[0659] Elastomers or rubbers are flexible materials characterized by a low Tg below room temperature, preferably below 10°C, below 0°C, or even below -10°C.

[0660] Exemplary such formulations are those sold under the Tango™, Tango+™, and Agilus™ families (eg, Agilus™ 30).

[0661] Exemplary such formulations are described in WO2017 / 208238, which is incorporated by reference as if fully set forth herein.

[0662] Whenever "Agilus" or "Agilus formulation" is mentioned, it means a formulation of the Agilus® family (e.g. the formulations described in WO2017 / 208238), optionally and preferably Agilus® 30.

[0663] According to some of the any of the embodiments described herein, the elastomerically curable modeling formulation includes at least one elastomerically curable material.

[0664] The phrase "elastomeric curable material" describes a curable material as defined herein that upon exposure to curing energy provides a cured material that has the properties of an elastomer (rubber, or rubber-like material).

[0665] Elastomeric curable materials generally include one or more polymerizable (curable) groups that undergo polymerization upon exposure to suitable curing conditions (e.g., curing energy) linked to moieties that impart elasticity to the polymerized and / or crosslinked material. Such moieties generally include alkyl, alkylene chains, hydrocarbon, alkylene glycol groups or chains (e.g., oligo- or poly(alkylene glycols)), as defined herein, urethane, oligourethane, or polyurethane moieties, as defined herein, and the like, and further including combinations of any of the foregoing, and are referred to herein as "elastomeric moieties."

[0666] The elastomeric curable material can be a monofunctional or multifunctional material, or a combination thereof.

[0667] Elastomeric monofunctional curable materials according to some embodiments of the present invention can be vinyl-containing compounds represented by Formula I below: At least one of R1 and R2 in Formula I is and / or includes an elastomeric moiety as defined herein.

[0668] The =CH2 group in formula I represents a polymerizable group, which according to some embodiments is a UV curable group, and thus the elastomeric curable material is a UV curable material.

[0669] For example, R1 in formula I is or includes an elastomeric moiety as defined herein, and R2 is, for example, hydrogen, C(1-4) alkyl, C(1-4) alkoxy, or any other substituent, so long as it does not interfere with the elastomeric properties of the cured material.

[0670] In some embodiments, R1 in formula I is a carboxylate as described herein, R2 is hydrogen, and the compound is a monofunctional acrylate monomer. In some embodiments, R1 in formula I is a carboxylate as described herein, R2 is methyl, and the compound is a monofunctional methacrylate monomer. Curable materials in which R1 is a carboxylate and R2 is hydrogen or methyl are collectively referred to herein as "(meth)acrylates."

[0671] In some of these embodiments, the carboxylate group is -C(=O)-OR c and R c is an elastomeric portion as described herein.

[0672] In some embodiments, R1 in formula I is an amide as described herein, R2 is hydrogen, and the compound is a monofunctional acrylamide monomer. In some embodiments, R1 in formula I is an amide as described herein, R2 is methyl, and the compound is a monofunctional methacrylamide monomer. Curable materials in which R1 is an amide and R2 is hydrogen or methyl are collectively referred to herein as "(meth)acrylamides."

[0673] (Meth)acrylates and (meth)acrylamides are collectively referred to herein as (meth)acrylic materials.

[0674] In some embodiments, the amide is represented by -C(=O)-NRdRe, where Rd and Re are selected from hydrogen and an elastomeric moiety, with at least one being an elastomeric moiety as defined herein. When one or both of R1 and R2 in formula I include a polymeric or oligomeric moiety, the monofunctional curable compound of formula I is an exemplary polymeric or oligomeric monofunctional curable material. Otherwise, it is an exemplary monomeric monofunctional curable material.

[0675] In a multifunctional elastomeric material, two or more polymerizable groups are linked to each other by an elastomeric moiety as described herein.

[0676] In some embodiments, the multifunctional elastomeric material can be represented by Formula I as described herein, where R1 comprises an elastomeric material terminated by a polymerizable group as described herein.

[0677] For example, a difunctional elastomeric curable material may be represented by the following formula I: * can be represented by: TIFF0007601964000008.tif47166 where E is an elastomeric linking moiety as described herein and R'2 is as defined herein for R2 in formula I.

[0678] In another example, a trifunctional elastomeric curable material can be represented by Formula II below: TIFF0007601964000009.tif73166 wherein E is an elastomeric linking moiety as described herein, and R′2 and R″2 are each independently as defined herein for R2 in formula I.

[0679] In some embodiments, multifunctional (e.g., difunctional, trifunctional, or higher functional) elastomeric curable materials can be collectively represented by Formula III: TIFF0007601964000010.tif49166, wherein R2 and R'2 are as defined herein; B is a di- or trifunctional branching unit as defined herein (depending on the nature of X1); X2 and X3 are each independently absent, an elastomeric moiety as described herein, or selected from an alkyl, a hydrocarbon, an alkylene chain, a cycloalkyl, an aryl, an alkylene glycol, a urethane moiety, and any combination thereof; X1 is absent or selected from alkyl, hydrocarbon, alkylene chain, cycloalkyl, aryl, alkylene glycol, urethane moiety, and elastomeric moiety (each optionally substituted (e.g., terminated) with a meth(acrylate) moiety (OC(=O)CR"2=CH2), and any combination thereof, or X1 is: TIFF0007601964000011.tif43166 where the curved lines represent the attachment points; B' is a branching unit, which is the same as or different from B; X'2 and X'3 are each independently as defined herein for X2 and X3; R″2 and R″'2 are as defined herein for R2 and R′2; provided that at least one of X1, X2, and X3 is or includes an elastomeric moiety as described herein.

[0680] The term "branched unit" as used herein describes a linking moiety that is multiple radical, preferably aliphatic or alicyclic. By "multiple radical", it is meant that the linking moiety has two or more points of attachment and thus connects between two or more atoms and / or groups or moieties.

[0681] That is, a branching unit is a chemical moiety that, when attached to a single position, group, or atom of a substance, creates two or more functional groups attached to that single position, group, or atom, thus "branching" a single functionality into two or more functions.

[0682] In some embodiments, the branching unit is derived from a chemical moiety having two, three or more functional groups, hi some embodiments, the branching unit is a branched alkyl or a branched linking moiety as described herein.

[0683] Multifunctional elastomeric curable materials having four or more polymerizable groups are also contemplated and can have a structure similar to that given in Formula III (but, for example, including a branching unit B having greater branching or including an X1 moiety having two (meth)acrylate moieties as defined herein) or a structure similar to that given in Formula II (but, for example, including another (meth)acrylate moiety bonded to the elastomeric moiety).

[0684] In some embodiments, the elastomeric moiety (e.g., R c or Formula I * , the moiety shown as E in II and III) is or comprises an alkyl, which may be linear or branched, and which is preferably three or more, or four or more carbon atoms; an alkylene chain, preferably three or more, or four or more carbon atoms in length; an alkylene glycol, as defined herein, an oligo(alkylene glycol), or a poly(alkylene glycol), as defined herein, preferably four or more atoms in length, a urethane, oligourethane, or polyurethane, as defined herein, preferably four or more carbon atoms in length, and combinations thereof.

[0685] In some of any of the embodiments described herein, the elastomeric curable material is a (meth)acrylic curable material as described herein, and in some embodiments, it is an acrylate.

[0686] In some of the embodiments described herein, the elastomerically curable material is or includes a monofunctional elastomerically curable material, and in some embodiments, the monofunctional elastomerically curable material is represented by Formula I, where R is -C(=O)-OR a and R ais an alkylene chain (e.g., 4 or more, preferably 6 or more, preferably 8 or more carbon atoms in length), or a poly(alkylene glycol) chain, as defined herein.

[0687] In some embodiments, the elastomer curable material is or includes a multifunctional elastomer curable material, and in some embodiments, the multifunctional elastomer curable material is represented by Formula I * where E is an alkylene chain (e.g., 4 or more, or 6 or more carbon atoms in length) and / or a poly(alkylene glycol) chain, as defined herein.

[0688] In some embodiments, the elastomeric curable material is or includes a multifunctional elastomeric curable material, in some embodiments, the multifunctional elastomeric curable material is represented by Formula II, where E is a branched alkyl (e.g., 3 or more, or 4 or more, or 5 or more carbon atoms in length).

[0689] In some of the embodiments described herein, the elastomeric curable material may be, for example, any of the following formulae I, I * , II or III, and in some embodiments the acrylate or methacrylate is an elastomeric elastomer (also referred to as an acrylic or methacrylic elastomer) that, when cured, provides a polymeric material with a T below 0° C. or below −10° C. g The arithmetic unit is selected to comprise:

[0690] Exemplary elastomeric acrylate and methacrylate curing materials include, but are not limited to, 2-propanoic acid, 2-[[(butylamino)carbonyl]oxy]ethyl ester (an exemplary urethane acrylate), and compounds sold under the trade names SR335 (lauryl acrylate) and SR395 (isodecyl acrylate) (by Sartomer). Other examples include compounds sold under the trade names SR350D (trifunctional trimethylolpropane trimethacrylate (TMPTMA)), SR256 (2-(2-ethoxyethoxy)ethyl acrylate), SR252 (polyethylene glycol (600) dimethacrylate), SR561 (alkoxylated hexanediol diacrylate) (by Sartomer).

[0691] It should be noted that other acrylic materials, for example those having one or more acrylamide groups instead of one or more acrylate or methacrylate groups, are also contemplated.

[0692] In some of the embodiments described herein, the elastomeric curable material may be any of the embodiments described herein, including one or more monofunctional elastomeric curable materials (e.g., monofunctional elastomeric acrylates as represented by Formula I) and one or more multifunctional (e.g., difunctional) elastomeric curable materials (e.g., polyfunctional elastomeric acrylates as represented by Formula I). * , II, or III).

[0693] In some of any of the embodiments described herein, the total amount of elastomeric curable material is at least 40%, or at least 50%, or at least 60%, and can be up to 70%, or even up to 80%, of the total amount of the elastomeric modeling material formulation as described herein.

[0694] In some of any of the embodiments described herein, the elastomer curable modeling formulation further comprises silica particles.

[0695] In some of the embodiments described herein, the silica particles have an average particle size of less than 1 micron, i.e., the silica particles are submicron particles. In some embodiments, the silica particles are nano-sized or nano-particles having an average particle size ranging from 0.1 nm to 900 nm, or from 0.1 nm to 700 nm, or from 1 nm to 700 nm, or from 1 nm to 500 nm, or from 1 nm to 200 nm, including any intermediate values ​​and subranges therebetween.

[0696] In some embodiments, at least a portion of such particles may aggregate when introduced into the formulation, and in some of these embodiments, the aggregates have an average size of 3 microns or less, or 1.5 microns or less.

[0697] Any commercially available formulation of submicron silica particles can be used 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.

[0698] The silica particles can be such that they have a hydrophobic or hydrophilic surface. The hydrophobicity or hydrophilicity of the surface of the particle is determined by the nature of the surface groups on the particle.

[0699] When the silica is untreated, i.e., composed essentially of Si and O atoms, the particles generally have silanol (Si-OH) surface groups and are therefore hydrophilic. Untreated (uncoated) colloidal silica, fumed silica, precipitated silica, and layered silica all have hydrophilic surfaces and are considered hydrophilic silicas.

[0700] Layered silicas can be treated to provide quaternary ammonium and / or ammonium terminated long chain hydrocarbons as surface groups, with the surface properties being determined by the length of the hydrocarbon chain. Hydrophobic silica is a form of silica in which hydrophobic groups are attached to the surface of the particle, and is also referred to as treated silica or functionalized silica (silica reacted with hydrophobic groups).

[0701] As defined herein, silica particles having hydrophobic surface groups such as, but not limited to, alkyl, preferably 2 or more carbon atoms in length, preferably 4 or more, or 6 or more carbon atoms in length, medium to large alkyl, cycloalkyl, aryl, and other hydrocarbons, or hydrophobic polymers (e.g., polydimethylsiloxane), are hydrophobic silica particles.

[0702] Silica particles as described herein can therefore be untreated (non-functionalized) and are therefore hydrophilic particles.

[0703] Alternatively, silica particles as described herein can be treated or functionalized by reacting with moieties on their surface to form bonds.

[0704] When said moieties are hydrophilic moieties, the functionalized silica particles are hydrophilic.

[0705] Silica particles having hydrophilic surface groups, such as, but not limited to, hydroxy, amine, ammonium, carboxy, silanol, oxo, and the like, are hydrophilic silica particles.

[0706] When the moieties are hydrophobic moieties as described herein, the functionalized silica particles are hydrophobic.

[0707] In some of any of the embodiments described herein, at least some or all of the silica particles have a hydrophilic surface (i.e., they are hydrophilic silica particles, e.g., untreated silica such as colloidal silica).

[0708] In some of any of the embodiments described herein, at least some or all of the silica particles have a hydrophobic surface (ie, are hydrophobic silica particles).

[0709] In some embodiments, the hydrophobic silica particles are functionalized silica particles, ie, particles of silica that have been treated with one or more hydrophobic moieties.

[0710] In some of any of the embodiments described herein, at least some or all of the silica particles are hydrophobic silica particles functionalized with hardenable functional groups (particles having hardenable groups on their surfaces).

[0711] The curable functional group can be any polymerizable group as described herein. In some embodiments, the curable functional group is polymerizable by the same polymerization reaction as the curable monomer in the formulation and / or when exposed to the same curing conditions as the curable monomer. In some embodiments, the curable group is a (meth)acrylic (acrylic or methacrylic) group, as defined herein.

[0712] The hydrophilic and hydrophobic, functionalized and untreated silica particles as described herein can be commercially available materials or can be manufactured using methods well known in the industry.

[0713] "At least a portion" as used in the context of these embodiments means 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.

[0714] The silica particles can also be a mixture of two or more types of silica particles, such as a mixture of two or more types of any of the silica particles described herein.

[0715] In some of the embodiments described herein, the amount of silica particles in the modeling material formulation ranges from about 1% to about 20% by weight, or from about 1% to about 15% by weight, or from about 1% to about 10% by weight of the total weight of the modeling material formulation.

[0716] In some of any of the embodiments described herein, the amount of silica particles in the formulation system as described herein ranges from about 1 wt % to about 20 wt %, or from about 1 wt % to about 15 wt %, or from about 1 wt % to about 10 wt % of the total weight of the formulation system.

[0717] In some embodiments, the formulation system includes one formulation, hi some embodiments, the formulation system includes two or more formulations, and the silica particles are included in one, two, or all of the formulations.

[0718] The amount of silica particles can be manipulated as desired to control the mechanical properties of the hardened build material and / or object or portion thereof comprising the same, for example, increasing the amount of silica particles can increase the elastic modulus of the hardened build material and / or object or portion thereof comprising the same.

[0719] In some of any of the embodiments described herein, the amount of silica particles is such that the weight ratio of elastomeric curable material to silica particles in one or more modeling material formulations is in the range of about 50:1 to about 4:1, or about 30:1 to about 4:1, or about 20:1 to about 2:1 (including any intermediate values ​​and subranges therebetween).

[0720] According to some of any of the embodiments described herein, the elastomeric modeling material formulation further includes one or more additional curable materials.

[0721] The additional curable materials can be monofunctional curable materials, multifunctional curable materials, or mixtures thereof, and each material can be monomeric, oligomeric, or polymeric, or combinations thereof.

[0722] Preferably, but not necessarily, the additional curable material is polymerizable when exposed to the same curing energy that the curable elastomeric material is polymerizable upon exposure to, for example, photoirradiation (eg, UV radiation).

[0723] In some embodiments, the additional curable material, when cured, provides that the polymerized material has a T g Higher T g For example, T higher than 0° C. g , or T higher than 5°C g , or T higher than 10°C g It is as if it has the following features.

[0724] In some embodiments, the additional curable material, when cured, may have a different modulus and / or T that is representative of the elastomeric material. g The non-elastomeric curable material has

[0725] In some embodiments, the additional curable material is a monofunctional acrylate or methacrylate ((meth)acrylate). Non-limiting examples include isobornyl acrylate (IBOA), isobornyl methacrylate, acryloyl morpholine (ACMO), phenoxyethyl acrylate sold by Sartomer Company (USA) under the trade name SR-339, urethane acrylate oligomers such as those sold under the trade name CN131B, and any other acrylates and methacrylates usable in AM methodologies.

[0726] In some embodiments, the additional curable material is a multifunctional acrylate or methacrylate ((meth)acrylate). Non-limiting examples of multifunctional (meth)acrylates include propoxylated (2) neopentyl glycol diacrylate, ditrimethylolpropane tetraacrylate (DiTMPTTA), pentaerythritol tetraacrylate (TETTA), and dipentaerythritol pentaacrylate (DiPEP), sold by Sartomer Company (USA) under the trade name SR-9003, and aliphatic urethane diacrylates, such as those sold as Ebecryl 230. Non-limiting examples of multifunctional (meth)acrylate oligomers include ethoxylated or methoxylated polyethylene glycol diacrylates or dimethacrylates, ethoxylated bisphenol A diacrylates, polyethylene glycol-polyethylene glycol urethane diacrylates, partially acrylated polyol oligomers, and polyester-based urethane diacrylates, such as those sold as CNN91.

[0727] T as defined herein g Any other hardenable material, preferably a hardenable material comprising the formula:

[0728] In some of any of the embodiments described herein, the elastomeric modeling material formulation further includes an initiator for initiating polymerization of the curable material.

[0729] When all of the curable materials (elastomer and additives, if present) are photopolymerizable, a photoinitiator can be used in these embodiments.

[0730] When all of the curable materials (elastomers and addenda, if present) are acrylic compounds or are otherwise photopolymerizable by free radical polymerization, free radical photoinitiators as described herein can be used in these embodiments.

[0731] The concentration of the photoinitiator in the curable elastomeric formulation containing it can range from about 0.1% to about 0.5% by weight, or from about 1% to about 5% by weight, including all intermediate values ​​and subranges therebetween.

[0732] According to some of any of the embodiments described herein, the elastomeric molding material formulation further comprises one or more additional non-curable materials, such as one or more colorants, dispersants, surfactants, stabilizers, and inhibitors, as described herein for the soft molding material formulations.

[0733] In some of any of the embodiments described herein, the elastomeric curable material is a UV curable material, which in some embodiments is an elastomeric (meth)acrylate, such as an elastomeric acrylate.

[0734] In some of any of the embodiments described herein, an additional curable component is included in the elastomeric modeling material formulation, and in some embodiments, this component is a UV-curable acrylate or methacrylate.

[0735] In some of any of the embodiments described herein, the silica particles are (meth)acrylate-functionalized silica particles.

[0736] In some of any of the embodiments described herein, the elastomeric modeling material formulation includes one or more monofunctional elastomeric acrylates, one or more multifunctional elastomeric acrylates, one or more monofunctional acrylates or methacrylates, and one or more multifunctional acrylates or methacrylates.

[0737] In some of these embodiments, the elastomeric modeling material formulation further comprises one or more photoinitiators, for example, from the Irgacure® family.

[0738] In some of any of the embodiments described herein, all of the hardenable materials and silica particles are included in a single material formulation.

[0739] In some of the embodiments described herein, the elastomeric molding formulation comprises two or more molding material formulations to form an elastomeric formulation system that includes an elastomeric curable formulation as described herein.

[0740] In some of these embodiments, one type of build material formulation (e.g., a first formulation or part A) includes an elastomeric curable material (e.g., an elastomeric acrylate) and another type of build material formulation (e.g., a second formulation or part B) includes an additional curable material.

[0741] Alternatively, each of the two build material formulations includes an elastomeric curable material, and one of the formulations further includes an additional curable material.

[0742] Alternatively, each of the two build material formulations in the elastomeric formulation system includes an elastomeric curable material, but the elastomeric material is different in each formulation. For example, one formulation includes a monofunctional elastomeric curable material and another formulation includes a multifunctional elastomeric material. Alternatively, one formulation includes a mixture of monofunctional and multifunctional elastomeric curable materials in a ratio W and another formulation includes a mixture of monofunctional and multifunctional elastomeric curable materials in a ratio Q, where W and Q are different.

[0743] Whenever each of the build material formulations includes an elastomeric material as described herein, one or more of the build material formulations in an elastomeric formulation system can further include an additional curable material. In an exemplary embodiment, one formulation includes a monofunctional additional material and another type of formulation includes a multifunctional additional material. In a further exemplary embodiment, one formulation includes an oligomeric curable material and another type of formulation includes a monomeric curable material.

[0744] Any combination of elastomeric curable materials and additional curable materials as described herein are contemplated for inclusion in two or more build material formulations forming an elastomeric compound system. The composition of the build material formulations and the selection of printing modes allow for the fabrication of objects with different properties in a controllable manner, as described in more detail below.

[0745] In some embodiments, one or more of the molding material formulations in the elastomeric compound system are selected such that the ratio of elastomeric curable material to additional curable material provides a rubbery material as described herein.

[0746] In some embodiments, silica particles, one or more photoinitiators, and optionally other ingredients are included in one or both build material formulations.

[0747] In an exemplary build material formulation according to some of the embodiments described herein, all of the curable materials are (meth)acrylates.

[0748] In any of the exemplary modeling material formulations described herein, the concentration of the photoinitiator ranges from about 1% to about 5% by weight, or from about 2% to about 5% by weight, or from about 3% to about 5% by weight, or from about 3% to about 4% by weight (e.g., 3, 3.1, 3.2, 3.25, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.85, 3.9% by weight, including any intermediate values ​​therebetween) of the total weight of the formulation or formulation system containing it.

[0749] In any of the exemplary molding material formulations described herein, the concentration of the inhibitor is from 0 wt % to about 2 wt %, or from 0 wt % to about 1 wt %, for example, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or about 1 wt %, of the total weight of the formulation or formulation system containing it, including any intermediate values ​​therebetween.

[0750] In any of the exemplary molding material formulations described herein, the concentration of the surfactant is from 0 wt % to about 1 wt % of the total weight of the formulation or formulation system in which it is included, for example, 0, 0.01, 0.05, 0.1, 0.5 or about 1 wt %, including any intermediate values ​​therebetween.

[0751] In any of the exemplary molding material formulations described herein, the concentration of the dispersant is from 0% to about 2% by weight of the total weight of the formulation or formulation system in which it is included, for example, 0, 0.1, 0.5, 0.7, 1, 1.2, 1.3, 1.35, 1.4, 1.5, 1.7, 1.8 or about 2% by weight, including any intermediate values ​​therebetween.

[0752] In exemplary molding material formulations according to some of the embodiments described herein, the total concentration of the elastomeric curable material ranges from about 30% to about 90% by weight, or from about 40% to about 90% by weight, or from about 40% to about 85% by weight.

[0753] "Total concentration" throughout this specification means the total weight of all of the elastomeric modeling material formulation(s) or elastomeric formulation systems as described herein.

[0754] In some embodiments, elastomeric curable materials include monofunctional elastomeric curable materials and multifunctional elastomeric curable materials.

[0755] In some embodiments, the total concentration of the monofunctional elastomeric curable material ranges from about 20% to about 70% by weight, or from about 30% to about 50% by weight, including any intermediate values ​​and subranges therebetween. In exemplary embodiments, the total concentration of the monofunctional elastomeric curable material ranges from about 50% to about 70% by weight, or from about 55% to about 65% by weight, or from about 55% to about 60% by weight (e.g., 58% by weight), including any intermediate values ​​and subranges therebetween. In exemplary embodiments, the total concentration of the monofunctional elastomeric curable material ranges from about 30% to about 50% by weight, or from about 35% to about 50% by weight, or from about 40% to about 45% by weight (e.g., 42% by weight), including any intermediate values ​​and subranges therebetween.

[0756] In some embodiments, the total concentration of the multifunctional elastomeric curable material ranges from about 10% to about 30% by weight. In exemplary embodiments, the total concentration of the monofunctional elastomeric curable material ranges from about 10% to about 20% by weight, or from about 10% to about 15% by weight (e.g., 12% by weight). In exemplary embodiments, the total concentration of the monofunctional elastomeric curable material ranges from about 10% to about 30% by weight, or from about 10% to about 20% by weight, or from about 15% to about 20% by weight (e.g., 16% by weight).

[0757] In exemplary molding material formulations according to some of the embodiments described herein, the total concentration of additional hardenable material ranges from about 10% to about 40% by weight, or from about 15% to about 35% by weight, including any intermediate values ​​and subranges therebetween.

[0758] In some embodiments, the additional curable material comprises a monofunctional curable material.

[0759] In some embodiments, the total concentration of the monofunctional additional curable material ranges from about 15% to about 25% by weight, or from about 20% to about 25% by weight (e.g., 21% by weight), including any intermediate values ​​and subranges therebetween. In exemplary embodiments, the concentration of the monofunctional elastomeric curable material ranges from about 20% to about 30% by weight, or from about 25% to about 30% by weight (e.g., 28% by weight), including any intermediate values ​​and subranges therebetween.

[0760] In an exemplary elastomeric modeling material formulation or formulation system according to any of the embodiments described herein, the elastomer curable material includes a monofunctional elastomeric curable material and a multifunctional elastomeric curable material, the total concentration of the monofunctional elastomeric curable material ranges from about 30% to about 50% by weight (e.g., from about 40% to about 45% by weight), or from about 50% to about 70% by weight (e.g., from about 55% to about 60% by weight), the total concentration of the multifunctional elastomeric curable material ranges from about 10% to about 20% by weight, and one or more of the formulations further includes an additional monofunctional curable material at a total concentration in the range of about 20% to about 30% by weight.

[0761] According to some of any of the embodiments described herein, the one or more molding compounds include at least one elastomeric monofunctional curable material, at least one elastomeric multifunctional curable material, and at least one additional monofunctional curable material.

[0762] According to some of any of the embodiments described herein, the total concentration of the curable monofunctional material ranges from 10% to 30% by weight of the total weight of the one or more modeling formulations.

[0763] According to some of the embodiments described herein, the total concentration of the elastomeric monofunctional curable material ranges from 50% to 70% by weight of the total weight of the one or more molding formulations.

[0764] According to some of the embodiments described herein, the total concentration of the elastomeric multifunctional curable material ranges from 10% to 20% by weight of the total weight of the one or more molding formulations.

[0765] According to some of any of the embodiments described herein, the total concentration of the curable monofunctional materials is in the range of 10% to 30% by weight of the total weight of the one or more molding formulations, the total concentration of the elastomeric monofunctional curable materials is in the range of 50% to 70% by weight of the total weight of the one or more molding formulations, and the total concentration of the elastomeric multifunctional curable materials is in the range of 10% to 20% by weight of the total weight of the one or more molding formulations.

[0766] According to some of any of the embodiments described herein, the total concentration of the curable monofunctional material ranges from 20% to 30% by weight of the total weight of the one or more modeling formulations.

[0767] According to some of any of the embodiments described herein, the total concentration of the elastomeric monofunctional curable material ranges from 30% to 50% by weight of the total weight of the one or more modeling formulations.

[0768] According to some of the embodiments described herein, the total concentration of the elastomeric multifunctional curable material ranges from 10% to 30% by weight of the total weight of the one or more molding formulations.

[0769] According to some of any of the embodiments described herein, the total concentration of the curable monofunctional materials is in the range of 20% to 30% by weight of the total weight of the one or more molding formulations, the total concentration of the elastomeric monofunctional curable materials is in the range of 30% to 50% by weight of the total weight of the one or more molding formulations, and the total concentration of the elastomeric multifunctional curable materials is in the range of 10% to 30% by weight of the total weight of the one or more molding formulations.

[0770] In the exemplary modeling material formulations described herein, the concentration of each component is given as its concentration when one modeling material formulation is used, or as its total concentration when two or more modeling material formulations are used.

[0771] In some embodiments, the elastomeric build material formulation (or two or more build material formulations) as described herein, when cured, is characterized by a tear resistance of at least 4000 N / m, or at least 4500 N / m, or at least 5000 N / m, as determined according to ASTM D624.

[0772] In some embodiments, an elastomeric molding material formulation (or two or more molding material formulations) as described herein, when cured, is characterized by a tear resistance that is at least 500 N / m, or at least 700 N / m, or at least 800 N / m higher than the tear resistance of the same cured molding material formulation without the silica particles.

[0773] In some embodiments, the elastomeric build material formulation (or two or more build material formulations) as described herein, when cured, is characterized by a tensile strength of at least 2 MPa.

[0774] In some embodiments, the elastomeric molding material formulation (or two or more molding material formulations) described herein is such that an object made of the cured molding material and having two O-rings and a tube connecting the rings is characterized by tear resistance under constant elongation for at least one hour or at least one day.

[0775] According to some of any of the embodiments described herein, the elastomer curable material is selected from a monofunctional elastomer curable monomer, a monofunctional elastomer curable oligomer, a multifunctional elastomer curable monomer, a multifunctional elastomer curable oligomer, and any combination thereof, as described herein for the elastomer curable material in any of the respective embodiments and any combination thereof.

[0776] In some embodiments, the elastomeric curable material is represented by Formula I, II, III, or IV as described herein in any of the individual embodiments and any combination thereof. * , II and III.

[0777] According to some of any of the embodiments described herein, the elastomer curable material and the silica particles are in the same formulation.

[0778] According to some of any of the embodiments described herein, the elastomer curable compound system further comprises at least one additional curable material.

[0779] According to some of any of the embodiments described herein, the additional curable material is selected from a monofunctional curable monomer, a monofunctional curable oligomer, a multifunctional curable monomer, a multifunctional curable oligomer, and any combination thereof, as described herein for the additional curable material in any of the respective embodiments and any combination thereof.

[0780] According to some of any of the embodiments described herein, the elastomeric curable material, the silica particles, and the additional curable material are in the same formulation.

[0781] According to some of the any of the embodiments described herein, the elastomeric curable material is a UV curable elastomeric material.

[0782] According to some of the any of the embodiments described herein, the elastomeric curable material is an acrylic elastomer.

[0783] Example 4 Distance Fields and Modulation Functions This example describes a method that includes selecting voxels from a three-dimensional construction space and determining, for the selected voxels, distance field values ​​for a three-dimensional part in the three-dimensional construction space. The method can be used to generate computer object data for use in systems 110 and 10 according to some embodiments of the present invention. At least a portion of the following description is also described in International Patent Application No. PCT / US2017 / 019340, filed February 24, 2017, the contents of which are incorporated herein by reference.

[0784] The distance field value can be used to select at least one material selection rule, where the at least one material selection rule is applied to the characteristics of the voxel to identify a material assignment for the voxel. If the material selection rule does not identify a material for the voxel, the material assignment indicates that no material is placed in the voxel, and if the at least one material selection rule identifies at least one material for the voxel, the material assignment indicates that at least one material is placed in the voxel. The material assignment for the voxel is then output for use in building the three-dimensional part using an additive manufacturing system.

[0785] In some embodiments of the invention, the method includes selecting a voxel in a three-dimensional build space, determining a first distance field value of the voxel to a boundary of a first three-dimensional part located in the three-dimensional build space, and determining a second distance field value of the voxel to a boundary of a second three-dimensional part located in the three-dimensional build space, The first distance field value and the second distance field value are then used to set a material assignment for the voxel.

[0786] To build a part using additive manufacturing, instructions must be provided to the printer to tell it what material, if any, to place at each available location on each print layer. In the past, these instructions were generated by identifying the exterior boundary of each part at each slice using a boundary representation. A part material was then specified for each location placed along the part boundary. If the part was to be solid, a material set for the part was also specified for each location within the part boundary. In such a system, all material transitions from one material to another, or from a material to free space, had to be described by a boundary representation.

[0787] The inventors have discovered that relying on such boundary representations to control the transition between materials creates several problems. First, performing rounding, lofting, and offset modeling operations in which the boundary representations are shifted inward or outward to generate print instructions can lead to errors or unexpected results due to interference between the shifting boundary representations. This typically occurs when the topology of the part is complex. Second, if the boundary representations of the parts do not define a closed body, Boolean operations such as subtraction or union, which are performed between two different parts when generating print instructions, can fail. If the part has any openings, the Boolean operations will be limited to the boundary representation itself, rather than the full volume of the part. Third, it is extremely difficult to define a grid using boundary representations, as the grid requires a huge number of meshes, resulting in a large amount of data. Fourth, it is not possible to form material gradients where the material mixture varies over more or less dimensions of the part.

[0788] In the embodiments described below, the problems associated with boundary representations are overcome by using a distance field. In one embodiment, the distance field is generated by dividing a three-dimensional build space containing the part to be manufactured into a three-dimensional matrix of voxels. The shortest distance from each voxel to the part boundary is then determined such that if the voxel is within the part, the distance is set to a positive value, if the voxel is outside the part, the distance is set to a negative value, and if the voxel is on the part boundary, the distance is zero. This generates a three-dimensional matrix of distance field values. Each part has its own associated distance field. As a result, if there are multiple parts in the build space, each voxel has multiple different distance field values, each associated with a separate part.

[0789] Once the distance fields are determined, they are used to select at least one material selection rule for each voxel. Each material selection rule uses at least one feature of the voxel, such as the voxel's distance field value and its position in the construction space, to identify a material assignment for the voxel. In some embodiments, the material selection rule includes a periodic function that is a function of the distance field value and / or the position in the construction space, such that one range of output values ​​generated by the periodic function is associated with no material being assigned to the voxel, and another range of output values ​​generated by the periodic function is associated with a material being assigned to the voxel. Such a periodic function allows a grid to be defined in the construction space.

[0790] Figure 9 shows an example of a simple system for assigning materials to voxels and manufacturing a part using the assigned materials. In Figure 9, a computer 9066 serves as a host computer for an additive manufacturing system 9068 and communicates with the system 9068 via one or more communication lines 9070. In some embodiments, the computer 9066 is internal to the system 9068, e.g., is part of an internal controller assembly for the system 9068. In other embodiments, the computer 9066 is external to the additive manufacturing system 9068.

[0791] 10 illustrates a block diagram of an exemplary architecture of a computer 9066. As illustrated, the computer 9066 includes suitable computer-based hardware, such as a user interface 9082, a memory controller 9084, a processor 9086, a graphics processing unit 9087, a storage medium 9088, an input / output (I / O) controller 9090, and a communications adapter 9092. The computer 9066 may also include various additional components included in a conventional computer, server, media device, signal processor, and / or printer controller.

[0792] The user interface 9082 is one or more user-operated interfaces (e.g., keyboards, touchpads, touchscreen displays, display monitors, and other eye-, voice-, motion-, or hand-operated controls) configured to operate the computer 9066. The memory controller 9084 is one or more circuit assemblies that interface components of the computer 9066 with one or more volatile random access memory (RAM) modules of the storage medium 9088. The processor 9086 is one or more computer processing units configured to operate the computer 9066, optionally including the memory controller 9084, and preferably including associated processing circuitry (e.g., programmable gate arrays, digital and analog components, etc.). For example, the processor 9086 may include one or more microprocessor-based and / or microcontroller-based units, one or more central processing units, and / or one or more front-end processing units.

[0793] The graphics processing unit 9087 contains a large number of transistors arranged to perform fast and efficient calculations related to 3D computer graphics, including texture mapping and rendering of polygons representing 3D objects.

[0794] Storage medium 9088 is one or more internal and / or external data storage or computer storage media for computer 9066, such as volatile RAM modules, read-only memory modules, optical media, magnetic media (e.g., hard disk drives), solid-state media (e.g., flash memory and solid-state drives), analog media, etc. Storage medium 9088 may hold one or more pre-processing and / or post-processing programs (not shown), which are discussed further below.

[0795] The I / O controller 9090 is one or more circuit assemblies that interface the memory controller 9084, the processor 9086, and the storage medium 9088 with various input and output components of the computer 9066, including the user interface 9082 and the communications adapter 9092. The communications adapter 9092 is one or more wired and / or wireless transmitter / receiver adapters configured to communicate over the communications line 9070.

[0796] Commands from the computer 9066 to the components of the system 9068 may be executed by one or more of a user interface 9082, a memory controller 9084, a processor 9086, a storage medium 9088, an input / output (I / O) controller 9090, a communications adapter 9092, and / or other suitable hardware and software implementations, as would be understood by one of skill in the art.

[0797] Figure 11 provides a flow diagram of a method for generating printing instructions from a part model using a distance field. Figure 12 provides a block diagram of a system 9200 that may be used to implement the method of Figure 11. According to one embodiment, the system 9200 is implemented on a computer 9066.

[0798] In step 9100, part data is received including mesh 9202, texture map 9204, bump map 9206, gloss map 9208, point features 9209, and part resolution, which are stored in storage medium 9088. Mesh 9202 describes the planar boundary of the part and can be defined as interconnected triangles or interconnected quadrangles. Texture map 9204 describes the location and geometry of the surface texture to be applied to the outside of each of the surfaces described by mesh 9202. Bump map 9206 provides a description of larger surface features present on a particular surface of mesh 9202. FIG. 13 provides an example of a portion of a part showing two surfaces 9300 and 9302 with a texture characterized by a raised square 9304, and a surface bump 9306 represented by a large raised square. The small square 9304 is described in the texture map 9204, while the surface bump 9306 is described in the bump map 9206. The gloss map 9208 indicates the desired level of gloss for various surfaces of the part.

[0799] Point features 9209 describe a set of material selection rules to be used for portions of a part that have a particular feature. Examples of part features that can be used as the basis for assigning a set of material selection rules include body or mesh identifiers, surface texture coordinates, and surface normal ranges. Thus, in some embodiments, different portions of a part have different sets of material selection rules, such that, for the same distance field value, different materials are used for different areas around the part. The use of such point features is described in more detail below.

[0800] The mesh 9202, texture map 9204, and bump map 9206 are provided to a slice calculation process 9210 performed by the graphics processing unit 9087 which performs steps 9101-9116, 9120, 9122, and 9124 of FIG. 11, which are described further below.

[0801] In step 9101, a slice computation process 9210 defines a three-dimensional construction space and orients the part described by the mesh 9202, texture map 9204, and bump map 9206 in the three-dimensional construction space to form an oriented digital model 9091. According to one embodiment, the construction space is defined by first orienting the digital part and then defining a bounding box around the oriented part to provide a support structure envelope around the part.

[0802] Figure 14 provides a three-dimensional view of a three-dimensional part model 402 oriented in a three-dimensional build space 400. In Figure 14, there is a -Z direction 406, a +Z direction 408, an X direction 410, and a Y direction 412. A slice 400 of the build space 400 is shown as including a collection of voxels, such as voxel 414. Although only a single slice is shown in Figure 14, there are multiple slices within the build space 400 such that the voxels fill the entirety of the build space 400. The dimensions of the voxels are based on the resolution set for the part.

[0803] In step 9102, the slice calculation process 9210 sets a Z-buffer 9095 value for each slice in the construction space 400. The Z-buffer for a slice contains a value for each voxel in the slice, and the magnitude of the Z-buffer value represents the magnitude of the vertical distance between the voxel and the most used STL boundary of the part. The STL boundary of a part is constructed from a combination of one or more meshes 9202, texture maps 9204 applied to those meshes, and bump maps 9206 applied to those meshes. In step 9102, this distance is determined by looking in the -Z direction 406 from the voxel, and therefore the Z-buffer is referred to as the -Z buffer. The sign of the Z-buffer value indicates whether the voxel is inside or outside the part, with a negative value indicating the voxel is outside the part and a positive value indicating the voxel is inside the part. Initially, the -Z buffer values ​​for the slice are all set to the maximum negative value, indicating that no part of the part is visible in the -Z direction 406 from any of the voxels.

[0804] A rendering operation is then performed by the GPU 9087 using the mesh 9202, texture map 9204, and bump map 9206 to construct a description of the STL boundary of the part in the three-dimensional build space 400 and project the description onto the slice. In particular, each surface in the mesh 9202 is rendered one at a time, the texture map 9204 and bump map 9206 are applied to the rendered surface to generate an STL boundary for that surface, and the resulting STL boundary for that surface is projected onto the slice by identifying a voxel that is directly above the STL boundary in the three-dimensional build space. For each voxel that is directly above the STL boundary of the surface, the distance between the STL boundary and the voxel is compared to the current distance stored in the -Z buffer for that voxel. If the distance to the currently projected surface has a smaller magnitude than the value stored in the -Z buffer, then the current surface is considered to be closer to the voxel than the previously rendered surface of the part, and the -Z buffer is updated to the distance to the current STL boundary. The sign of the distance value stored in the -Z buffer is set to indicate whether the voxel is inside or outside the part. This can be determined based on the angle between the outward normal of the current surface and the +Z direction 408. According to one embodiment, the identity of the current surface is also stored in an additional buffer of the slice. If the distance between the current STL boundary and the voxel is greater than the magnitude of the Z buffer value of the voxel, the Z buffer value remains unchanged. This occurs when the current surface is obscured from the voxel by another surface of the part that is closer to the voxel. Thus, after all surfaces of the part below the current slice have been rendered and projected onto the slice, the Z buffer contains a value indicating the shortest distance in the Z direction between the voxel and the STL boundary of the part, and a further buffer indicates the identity of these closest surfaces. This is repeated for each slice in the construction space 400.

[0805] It is common for a graphical processing unit to load a Z-buffer when rendering a 3D computer model of an object onto a 2D plane, but it is not known to use such a graphical processing unit to load a Z-buffer associated with a voxel as part of constructing a three-dimensional part.

[0806] After the -Z buffers have been created for all of the slices in the construction space 400, the lowest slice in the construction space 400 is selected in step 9104. In step 9106, a rendering operation is performed in the +Z direction to load the +Z buffer of the selected slice. This rendering is the same as the rendering performed in the -Z direction except that the view changes to the +Z direction 408. After step 9106, the selected slice has a Z buffer value for each voxel and a -Z buffer value for each voxel, where the +Z buffer value provides the shortest vertical distance between the voxel and the part in the +Z direction 408 and the -Z buffer value provides the shortest distance between the voxel and the part in the -Z direction 406.

[0807] Although steps 9102 and 9106 are described above with respect to one part in the construction space 400, in other embodiments, there are multiple parts in the construction space 400. When there are multiple parts in the construction space 400, a separate -Z buffer and a separate +Z buffer are created for each part in each slice in the construction space 400.

[0808] At step 9108, a silhouette boundary for the selected slice is determined from the +Z buffer. In particular, the +Z buffer values ​​for pairs of voxels are examined to identify a transition from a negative value to the most negative possible value. Such a transition represents the boundary between when a portion of the part is above the voxel and when no portion of the part is above the voxel's adjacent locations. An example of such a boundary can be seen in FIG. 14, where voxels 420 and 422 lie along such a boundary. Voxel 420 is below part 402 and has a +Z buffer value of −4. Voxel 422, adjacent to voxel 420, is not below any portion of the part and therefore has the most negative possible value in the +Z buffer, e.g., −10000. Repeating this pairwise comparison for each pair produces a silhouette boundary, such as silhouette boundary 424, where voxels within the boundary are considered to be below a portion of the part and voxels outside the silhouette are not below any portion of the part. Note that if multiple parts are present in the build space 400 , then step 9108 is repeated for each + buffer in the slice selected in step 9104 .

[0809] In step 9110, slice calculation process 9210 determines the intersection of the STL boundary with the current slice. In FIG. 14, the intersection of the STL boundary with slice 400 is shown as boundary 430 and is shown with a dotted line. The intersection of the STL boundary with the slice can be found by examining the +Z and -Z buffers to identify adjacent pixels where the Z buffer value changes from a negative value to a zero value or from a negative value to a positive value. Such a change in Z buffer value indicates a transition from outside the part to inside the part. Step 9110 is performed for the Z buffer of each part.

[0810] In step 9112, a single voxel in the current slice is selected. In step 9114, a distance field value to the STL boundary of the part is determined for that voxel. This distance field value is the shortest distance between the voxel and any portion of the STL boundary of the part. In step 9116, if the current voxel is outside the part, then the distance to the silhouette boundary is determined for the current voxel.

[0811] According to one embodiment, steps 9114 and 9116 are performed together using a sampling algorithm. An example of such a sampling algorithm is shown in the flow diagram of Figure 15, which is described in relation to Figure 16. In Figure 16, a top view of a slice 620 is shown along with a matrix of voxels including the current voxel 600. The STL boundary 612 that intersects with the slice 600 is shown as a solid line, and the silhouette boundary 610 is shown as a dotted line.

[0812] In step 500 of Figure 15, the current voxel, voxel 600 in Figure 16, is examined to determine whether it is on an STL boundary in the current slice. For example, in Figure 16, voxel 650 is considered to be on STL boundary 612 because STL boundary 612 intersects with voxel 650. If in step 500 the current voxel is on an STL boundary, then in step 502 the distance field value for the current voxel is set to 0.

[0813] If in step 500 the current voxel is not in an STL boundary, as shown by current voxel 600 in Figure 16, then step 504 in Figure 15 is performed, where the distance field value of current voxel 600 is set to the smaller of the two Z buffer values ​​for the current voxel. In particular, the magnitudes of the Z distance values ​​in the +Z buffer and -Z buffer are compared, and the smaller magnitude is set as the distance field value for the current voxel. In addition, the sign of the distance field value is set based on whether the voxel is inside or outside the part. If the voxel is inside the part, the distance field value is set as a positive value, and if the voxel is outside the part, the distance field value is set as a negative value.

[0814] At step 506, a ring of voxels around the current voxel in the current slice is identified. For example, in FIG. 16, a first ring 602, shown by dotted shading, surrounds the current voxel 600. At step 508, a voxel in the identified ring is selected. At step 510, if the selected ring voxel is on the STL boundary, the distance b...

Claims

1. 1. A method for additive manufacturing at least one tubular structure having characteristics of a blood vessel, the method comprising: receiving as input image data describing a shape of a blood vessel; converting the image data into computer object data; receiving as input stiffness levels along the blood vessel; accessing a computer readable medium storing a lookup table having a plurality of entries, each entry corresponding to a different range of stiffness levels, the plurality of entries being associated with at least one additive manufacturing parameter selected from the group consisting of build material formulations, combinations of build material formulations, and wall thicknesses; and operating an additive manufacturing system in accordance with the extracted additive manufacturing parameters to form a plurality of layers in a construction pattern corresponding to a shape of the blood vessel, wherein operating the additive manufacturing system includes ejecting droplets of different build material formulations to form an elongated core, a sheath encapsulating the core and having the shape of the blood vessel, and an intermediate sheath between the core and the sheath, each of the core, sheath, and intermediate sheath being formed from a different build material formulation or a different combination of build material formulations, and both the core and the intermediate sheath being sacrificial objects.

2. The method of claim 1, comprising dispensing at least one liquid build material formulation to form a reinforcing element embedded within the sheath, the reinforcing element having a higher hardness level than the sheath.

3. 1. A method for additive manufacturing of at least one tubular structure having characteristics of a blood vessel, the blood vessel being described by computer object data, the method comprising ejecting droplets of a plurality of different build material formulations to form a plurality of layers in a configuration pattern forming an elongated core, a sheath encapsulating the core and having the shape of the blood vessel, and an intermediate sheath between the core and the sheath, each of the core, sheath, and intermediate sheath being formed by ejecting droplets of different build material formulations or different combinations of build material formulations, and both the core and the intermediate sheath being sacrificial objects.

4. 4. The method of claim 2 or 3, comprising exposing said layer to curing conditions after said dispensing, thereby obtaining a cured material that forms at least said sheath.

5. The method of any one of claims 2 to 4, comprising removing the core and the intermediate sheath.

6. 6. The method of any of claims 2 to 5, wherein one of the core and the intermediate sheath is formed by dispensing a build material formulation that, when exposed to curing conditions, results in a liquid or liquid-like material characterized by at least one of the following: a viscosity of 10,000 centipoise or less; a ratio of shear loss modulus to shear storage modulus greater than 1; a shear modulus of less than 20 kPa; flowability when exposed to a positive pressure of 1 bar or less; shear thinning and / or thixotropic behavior; and thermal thinning behavior.

7. The method of any of claims 2 to 6, wherein one of the core and the intermediate sheath is formed by expelling a build material formulation including a non-hardenable material, the build material formulation resulting in a liquid or liquid-like material.

8. The method of claim 7 , wherein the non-curable material comprises a poly(alkylene glycol) having a molecular weight of less than 2000 grams / mol.

9. The method of claim 7 or 8, wherein the build material formulation that includes the non-curable material also includes a curable material.

10. The method of claim 9 , wherein the curable material comprises a monofunctional curable material.

11. 11. The method of claim 9 or 10, wherein the curable material is hydrophilic.

12. The method of any of claims 9 to 11, wherein the curable material, when cured, results in a shear thinning and / or thixotropic material.

13. A method according to any of claims 9 to 12, wherein the curable material, when cured, provides a shear thinning material.

14. The method of any of claims 9 to 13, wherein the curable material, when cured, results in a water-soluble or water-immiscible material.

15. The method according to any of claims 9 to 14, wherein the amount of the curable material in the build material formulation is in the range of 10 to 25%.

16. The method of any of claims 2 to 15, wherein one of the core and the intermediate sheath is formed by dispensing a build material formulation that, when cured or exposed to curing conditions, results in a water soluble or water miscible material.

17. 17. The method of any of claims 2 to 16, wherein one of the core and the intermediate sheath is formed by extruding a build material formulation that when cured or exposed to curing conditions results in a material selected from a shear thinning material, a thixotropic material, or a thermal thinning material.

18. The method of any of claims 2 to 17, further comprising removing the core and the intermediate sheath.

19. 18. The method of any of claims 1 to 17, further comprising generating computer object data describing a cavity within the blood vessel, generating computer object data describing the cavity in a contracted shape, and combining the computer object data describing the blood vessel and the computer object data describing the cavity in the contracted shape to provide combined computer object data describing the blood vessel and the core enclosed by a hollow structure such that a gap exists between an inner surface of the blood vessel and an outermost surface of the core.

Images