Methods and systems for processing photopolymerizable compositions

Abstract

This disclosure provides a method comprising the steps of: obtaining an insert including a sieve defining openings, each opening having a diameter of 10 micrometers to 200 micrometers; placing a volume of fluid containing a photopolymerizable composition and a contaminant into the insert; and subjecting the volume of fluid to centrifugal force to separate the contaminant from at least a portion of the photopolymerizable composition by retaining the contaminant in the insert and allowing at least a portion of the photopolymerizable composition to pass through the sieve of the insert, thereby providing a separated photopolymerizable composition. A system is also provided, comprising additive manufacturing equipment, a centrifuge, and an insert configured to be inserted into said centrifuge. The method and system can advantageously facilitate the recovery of contaminated photopolymerizable compositions for reuse.

Description

Technical Field

[0001] This disclosure relates to processing photopolymerizable compositions to remove contaminants from the compositions, and systems for processing the compositions, such as those for use with additive manufacturing technologies. Background Technology

[0002] Photopolymerizable compositions have been used in many industries, including those employing additive manufacturing techniques. Smaller portions of the photopolymerizable composition can be polymerized to form articles, while the remaining portion typically contains one or more contaminants generated during the polymerization process. Summary of the Invention

[0003] Methods and systems for processing photopolymerizable compositions are provided.

[0004] In a first aspect, a method is provided. The method includes a) obtaining an insert comprising a sieve defining a plurality of openings, each opening having a diameter of 10 micrometers to 200 micrometers; b) placing a volume of fluid into the insert, wherein the fluid comprises a photopolymerizable composition and a contaminant; and c) subjecting the volume of fluid to centrifugal force to separate the contaminant from at least a portion of the photopolymerizable composition by retaining the contaminant in the insert and allowing at least a portion of the photopolymerizable composition to pass through the sieve of the insert, thereby providing a separated photopolymerizable composition.

[0005] In a second aspect, a system is provided. The system includes: a) additive manufacturing equipment; b) a centrifuge; and c) an insert configured to be inserted into the centrifuge, the insert including a sieve defining a plurality of openings, each opening having a diameter of 10 micrometers to 200 micrometers.

[0006] This method and system can be used to remove contaminants from photopolymerizable compositions to reduce the amount of photopolymerizable compositions that are discarded as waste or reused while containing contaminants, thereby resulting in lower quality three-dimensional objects.

[0007] The above description of the invention is not intended to describe every disclosed embodiment or every implementation of the invention. The following description illustrates exemplary embodiments in more detail. Guidance is provided throughout this application by a list of examples, which may be used in various combinations. In each case, the cited list is used only as a representative group and should not be construed as an exclusive list. Therefore, the scope of this disclosure should not be limited to the specific illustrative structures described herein, but should extend at least to the structures described by the language of the claims and their equivalents. Any element positively referenced as an alternative in this specification may be expressly included in or excluded from the claims in any combination as desired. While various theories and possible mechanisms may have been discussed herein, such discussion should in no way be used to limit the subject matter protected by the claims. Attached Figure Description

[0008] Figure 1 This is a flowchart of an exemplary method of this disclosure.

[0009] Figure 2A This is a schematic perspective view of additive manufacturing equipment.

[0010] Figure 2B This is a schematic perspective view of a centrifuge.

[0011] Figure 2C This is a schematic perspective view of an exemplary insert partially disposed in a container according to this disclosure.

[0012] Figure 2D yes Figure 2C A schematic perspective sectional view of the inserts and containers.

[0013] Figure 3A This is a schematic perspective view of an exemplary insert partially disposed in a container according to the present disclosure, wherein the insert holds a volume of fluid.

[0014] Figure 3B This is a schematic perspective view of an exemplary insert partially disposed in a container according to this disclosure.

[0015] Figure 4 This is a schematic top view of an exemplary sieve having multiple openings in a star shape according to the present disclosure.

[0016] Figure 5 This is a schematic exploded perspective view of an exemplary insert having two sieves according to the present disclosure.

[0017] Figure 6 This is a photograph of contaminants recovered from a photopolymerizable composition. Detailed Implementation

[0018] It has been discovered that contaminants can be removed from photopolymerizable compositions to enable their reuse. In at least some embodiments, the cleaned photopolymerizable composition is clean enough to be used in the same batch as a volume of unused (e.g., initial) photopolymerizable composition. Contaminants can be successfully removed from compositions even those with viscous and / or pasty consistency using methods or systems according to at least some embodiments of this disclosure.

[0019] For example, depending on the specific geometry of a three-dimensional object (e.g., a printed part), unintended undercutting in the printed geometry can cause tiny resin parts to cure without adequately adhering to the rest of the printed part, contaminating the remaining photopolymerizable composition. These tiny parts may have the size of one or more voxels. Another problem may be that, after reuse, one or more surfaces of the cylinder exhibit increased adhesion during printing, and entire parts or portions supporting the geometry may break off and contaminate the cylinder. Additional contamination can be, for example, lint from the surrounding air, but this can be minimized by using, for example, a laminar flow system used for applying cleanroom conditions. However, completely preventing contamination such as tiny broken parts and lint during the printing of multiple parts in a single cylinder is impractical.

[0020] Glossary

[0021] As used in this article, “photochemical radiation” encompasses UV radiation, electron beam radiation, visible radiation, infrared radiation, gamma radiation, and any combination thereof.

[0022] As used herein, a "monomer" is a single, unit molecule capable of combining with itself or other monomers to form an oligomer or polymer; an "oligomer" is a component having 2 to 9 repeating units; and a "polymer" refers to a component having 10 or more repeating units.

[0023] As used herein, "aliphatic group" refers to a saturated or unsaturated straight-chain, branched, or cyclic hydrocarbon group. For example, the term is used to cover alkyl groups, alkenyl groups, and alkynyl groups.

[0024] As used herein, "alkyl" refers to a straight-chain or branched, cyclic or acyclic monovalent hydrocarbon having one to thirty-two carbon atoms, such as methyl, ethyl, 1-propyl, 2-propyl, pentyl, etc.

[0025] As used in this article, "alkylene" refers to a straight-chain saturated divalent hydrocarbon having one to twelve carbon atoms or a branched saturated divalent hydrocarbon having two to twelve carbon atoms, such as methylene, ethylene, propylene, 2-methylpropylene, pentylene, hexylene, etc.

[0026] As used herein, "alkenyl" refers to a monovalent, straight-chain or branched, unsaturated aliphatic group having one or more carbon-carbon double bonds, such as a vinyl group. Unless otherwise specified, alkenyl groups typically contain two to twenty carbon atoms.

[0027] As used herein, "enediyl" refers to a straight-chain, branched, or cyclic divalent unsaturated aliphatic group, such as -CH=CH-, -CH=C(CH3)CH2-, -CH=CHCH2-, etc. Unless otherwise specified, an enediyl group typically contains two to twenty carbon atoms.

[0028] As used herein, the term "aryl" refers to a monovalent group in an aromatic carbocyclic compound. An aryl group has at least one aromatic carbocyclic ring and may have 1 to 5 optional rings attached to or fused to the aromatic carbocyclic ring. The additional rings may be aromatic, aliphatic, or a combination thereof. Aryl groups typically have 5 to 20 carbon atoms.

[0029] As used herein, the term "substituted aryl" refers to an aryl group that is substituted with at least one alkyl group, at least one alkoxy group, or at least one alkyl group plus at least one alkoxy group. A substituted aryl group contains 6 to 40 carbon atoms. A substituted aryl group often contains an aryl group having 5 to 20 carbon atoms and an alkyl group and / or an alkoxy group each having 1 to 20 carbon atoms.

[0030] As used herein, the term "aralkyl" refers to an alkyl group substituted with at least one aryl group. Aralkyl groups contain 6 to 40 carbon atoms. Aralkyl groups often comprise an alkyl group having 1 to 20 carbon atoms and an aryl group having 5 to 20 carbon atoms.

[0031] As used herein, the term "alkene unsaturation" refers to a double bond between two carbon atoms and includes functional groups such as vinyl (H2C=CH-), including vinyl ethers (H2C=CHO), vinyl esters (H2C=CHOCO), styrene (e.g., vinylbenzene), and alkenyl (H2C=CH(CH2)). n -), where n is typically in the range of 1 to 30, 1 to 20, or 1 to 10. Alkenyl unsaturated groups also include (meth)acryloyl groups, such as (meth)acrylamido groups (H2C=CHCONH- and H2C=CH(CH3)CONH-) and (meth)acrylate groups (CH2=CHCOO- and CH2=C(CH3)COO-).

[0032] As used herein, the term "(meth)acrylate" is an abbreviation for acrylate, methacrylate, or combinations thereof; "(meth)acrylic acid" is an abbreviation for acrylate, methacrylate, or combinations thereof; and "(meth)acryloyl" is an abbreviation for an acryloyl group and a methacryloyl group. "Acryloyl" refers to derivatives of acrylic acid, such as acrylates, methacrylates, acrylamides, and methacrylamides. "(meth)acryloyl" refers to a monomer or oligomer having at least one acryloyl or methacryloyl group and, if containing two or more groups, linked by an aliphatic segment. As used herein, "(meth)acrylate functional compound" is a compound that, among other things, includes a (meth)acrylate moiety. The term "(meth)acryloyl" refers to a compound of the formula CH2=CHR. b -(CO)- groups, where R b It can be hydrogen or methyl, and the group -(CO)- refers to a carbonyl group.

[0033] As used in this article, “diameter” refers to the length of the longest straight line that crosses a shape (two-dimensional or three-dimensional) and intersects the center of that shape.

[0034] As used herein, “fluid” means emulsions, dispersions, suspensions, solutions, and pure components having a continuous liquid phase, and excludes powders and particles in solid form.

[0035] As used in this article, "liquid" refers to a state of matter that is neither solid nor gaseous and has a definite volume but an indefinite shape.

[0036] As used herein, “curing” and “polymerization” each mean hardening or partially hardening a composition by any mechanism, such as heat, light, radiation, electron beams, microwaves, chemical reactions, or combinations thereof.

[0037] As used herein, “cured” means a material or composition that has been hardened or partially hardened by one or more curing mechanisms (e.g., polymerization or crosslinking).

[0038] As used herein, “photopolymerizable” refers to a composition containing at least one material that can be photocured or partially cured by radiation.

[0039] As used herein, “initial photopolymerizable composition” means a photopolymerizable composition in which no volume of it has been exposed to photochemical radiation, which contains the full amount of each component of the formulation and is free from any contaminants formed during curing.

[0040] As used herein, a “separated photopolymerizable composition” refers to a composition comprising at least one material that can be cured or partially cured by photochemical radiation, and comprising at least one component in a smaller amount than the total amount of the formulation. The separated photopolymerizable composition exposes a portion of its volume to photochemical radiation. The separated photopolymerizable composition also undergoes a process to separate at least one contaminant from the photopolymerizable composition.

[0041] As used herein, “contaminant” refers to a material disposed in a photopolymerizable composition, which is not intentionally included in the formulation of the composition. Contaminants may include at least one of the following: oligomers, polymers, dust particles, lint, a plurality of cured voxels formed by the photopolymerizable composition, or components formed by the polymerization products of the photopolymerizable composition.

[0042] The term "mass inertial force," as used in this article, can be specified as the force per unit mass, and therefore in m / s². 2 The units are specified. Furthermore, the inertial force can be represented by the force G, which is a factor of gravitational acceleration. For the purposes of this specification, gravitational acceleration is 9.81 m / s². 2 Therefore, for example, 9.81 m / s 2 The inertial force of mass can be expressed as 1G.

[0043] Similarly, all numerical values ​​herein are assumed to be modified by the term "approximately," and preferably by the term "precisely." As used herein, with respect to the quantity measured, the term "approximately" refers to a deviation in the quantity measured that is commensurate with the accuracy of the object being measured and the measuring equipment used, as a technician who would expect such a measurement to be performed with a certain degree of care. Furthermore, in this document, numerical ranges expressed by endpoints include all numbers contained within that range as well as endpoint values ​​(e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0044] As used herein, as a modifier of a characteristic or attribute, unless otherwise specifically defined, the term "approximately" means that the characteristic or attribute will be easily identifiable by a person skilled in the art without requiring absolute precision or a perfect match (e.g., within + / -20% for quantifiable characteristics). Unless otherwise specifically defined, the term "substantially" means a high degree of approximation (e.g., within + / -10% for quantifiable characteristics), but again, absolute precision or a perfect match is not required. Terms such as identical, equal, uniform, constant, and rigorous should be understood as being within ordinary tolerances or within measurement errors applicable to specific situations, rather than requiring absolute precision or a perfect match.

[0045] method

[0046] In the first aspect, a method is provided. This method includes:

[0047] a) Obtain an insert including a sieve that defines multiple openings, each opening having a diameter of 10 micrometers to 200 micrometers;

[0048] b) Placing a certain volume of fluid into the insert, wherein the fluid contains a photopolymerizable composition and contaminants; and

[0049] c) subjecting the fluid of that volume to centrifugal force to separate the contaminant from at least a portion of the photopolymerizable composition by retaining the contaminant in the insert and passing at least a portion of the photopolymerizable composition through the sieve of the insert, thereby providing a separated photopolymerizable composition.

[0050] See Figure 1 The method of the first aspect is provided in a flowchart. More specifically, the method includes step 110-a) obtaining an insert comprising a sieve defining a plurality of openings, each opening having a diameter of 10 micrometers to 200 micrometers; and step 120-b) placing a volume of fluid into the insert, wherein the fluid comprises a photopolymerizable composition and contaminants.

[0051] In some embodiments, the insert is placed in a centrifuge before fluid is deposited into it. In some embodiments, the insert is placed in a centrifuge after fluid is deposited into it. The configuration of the insert can be varied, as long as the insert includes a sieve and defines an open area to retain a volume of fluid. See also Figure 3A An exemplary insert 320 (attached to each of the container 330 and the stand 350) is shown placed on a laboratory balance 300. Weighing insert 320 after the addition of fluid 370 helps achieve proper mass balance during the application of centrifugal force when a fluid-containing weight or another insert will be subjected to centrifugal force simultaneously with insert 320. For example, Figure 2B An insert 220 containing fluid 270 and disposed in a cup 260 disposed in a centrifuge 290 is shown. A sieve 240 in the form of a nonwoven fabric is partially located within the insert 220, with the edge of the sieve 240 located outside the insert 220. Opposite to the insert 220, another cup 260 contains an object 280 that provides a balancing mass within the centrifuge 290. In some embodiments, the method further includes, before subjecting a volume of fluid to centrifugal force, placing that volume of fluid in a second insert within the centrifuge at a position opposite (e.g., the first) insert to balance the centrifuge.

[0052] In some embodiments, the centrifuge includes a sensor that measures imbalance and terminates centrifugation if the imbalance exceeds (e.g., a predetermined) threshold amount. Monitoring the balance of the centrifuge contents during the application of centrifugation can provide sensitive detection of two or more samples exhibiting different flow rates of photopolymerizable compositions through the sieve due to blockage of at least some sieve openings. When measuring such imbalance, any sieves with unacceptably high levels of blockage can be cleaned or replaced before further application of centrifugation. Alternatively, other measurement methods can be used to detect sieve blockage, such as measuring the fill level of the photopolymerizable composition in one or more inserts using ultrasonic or optical sensors.

[0053] The method further includes: step 130-c) subjecting the volume of fluid to centrifugal force to separate the contaminant from at least a portion of the photopolymerizable composition by retaining the contaminant in the insert and passing at least a portion of the photopolymerizable composition through a sieve of the insert, thereby providing a separated photopolymerizable composition. The centrifugal force used may be greater than 1G, 1.5G or more, 2G, 2.5G, 3G, 3.5G, 4G, 5G, 6G, 7G, 8G, 9G, 10G, 11G, 12G, 13G, 14G, 15G, 16G, 17G, 18G, 19G, or 20G or more; and 100G or less, 90G, 85G, 80G, 75G, 70G, 65G, 60G, 55G, 50G, 45G, or 40G or less. Those skilled in the art can determine appropriate parameters based on the viscosity of a particular fluid, where more viscous fluids and / or fluids with a paste-like consistency typically require higher centrifugal forces to propel the fluid through the sieve openings. Conversely, very low-viscosity materials can pass through a sieve with minimal centrifugal force, and using high centrifugal forces may risk breaking the flaking component into smaller fragments during centrifugation, especially if the component is made of a brittle material.

[0054] Advantageously, centrifugal force is typically applied to the fluid under ambient pressure. This contrasts with methods for separating contaminants from photopolymerizable compositions, which require the use of negative pressure (e.g., vacuum) or positive pressure to drive the photopolymerizable composition through a filter to efficiently separate contaminants. The use of positive or negative pressure introduces undesirable additional complexity to the method or system. In some embodiments, the photopolymerizable compositions available for use with the methods described herein exhibit shear-thinning behavior. This behavior facilitates successful separation of contaminants from the photopolymerizable composition because centrifugal force imparts shear to the composition, and the composition becomes thinner, thereby reducing its viscosity and enhancing its ability to pass through a sieve and into a container. The methods disclosed herein are also applicable to fluids exhibiting Newtonian viscosity behavior. Furthermore, some methods have used centrifuges to remove uncured photopolymerizable compositions from three-dimensional objects; therefore, the same centrifuge can advantageously be used to remove contaminants from the fluid.

[0055] In some embodiments, the separated photopolymerizable composition further comprises particulate filler. It should be understood that any particulate filler present in the fluid will be small enough to pass through the openings of the sieve, and therefore have an effective diameter of less than 200 μm, 175 μm, 150 μm, 125 μm, 100 μm, 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20 μm, 10 μm, 8 μm, 6 μm, 4 μm, 2 μm, or less than 1 μm. In some embodiments, the particulate filler comprises nanoparticles, wherein at least one of the particulate filler particles has a size of less than 1 micrometer, such as 950 nanometers or smaller, 900 nanometers, 850 nanometers, 800 nanometers, 750 nanometers, 700 nanometers, 650 nanometers, 600 nanometers, 550 nanometers, 500 nanometers, 450 nanometers, 400 nanometers, 350 nanometers, or 300 nanometers or smaller; and 1 nanometer or larger, 2 nanometers, 5 nanometers, 7 nanometers, 10 nanometers, 12 nanometers, 15 nanometers, 18 nanometers, 20 nanometers, 25 nanometers, 30 nanometers, 35 nanometers, 40 nanometers, 45 nanometers, 50 nanometers, 55 nanometers, 60 nanometers, 65 nanometers, 70 nanometers, 75 nanometers, 80 nanometers, 85 nanometers, 90 nanometers, 95 nanometers, 100 nanometers, 125 nanometers, 150 nanometers, 175 nanometers, 200 nanometers, 225 nanometers, 250 nanometers, or 275 nanometers or larger. Suitable particulate fillers include, for example, but not limited to, oxides of yttrium, strontium, barium, zirconium, hafnium, niobium, tantalum, tungsten, bismuth, molybdenum, tin, zinc, lanthanides (i.e., elements having an atomic number in the range of 57 to 71 (inclusive)), cerium, and combinations thereof. Examples of non-agglomerated silica (silica) nanoparticles are commercially available from Nalco Chemical Co., Naperville, IL under the product name NALCO COLLOIDAL SILICAS, such as NALCO products #1040, 1042, 1050, 1060, 2327, and 2329; and silica nanoparticles described in US 6,899,948 (Zhang et al.) and US 6,572,693 (Wu et al.).

[0056] In some embodiments, at least a portion of the insert is disposed within a container configured to be assembled in a centrifuge, and a portion of the photopolymerizable composition passing through the sieve of the insert is collected in the container. See also Figure 2C and Figure 2DA schematic diagram of an exemplary insert 220 partially disposed within a container 230 is provided. In use, the insert 220 is positioned above a large portion of the volume of the container 230 to facilitate the transfer of the photopolymerizable composition from the insert 220 to the container 230 below, aided by centrifugal force and gravity. A sieve 240 is located within the insert 220. The sieve 240 may be integrally formed with the insert 220 or constructed as a separate item placed within the insert 220. The sieve 240 is typically positioned near or within the container 230.

[0057] exist Figure 2C and Figure 2D In the illustrated embodiment, container 230 is partially supported by a support 250, which includes at least two legs 252 supporting a body 254. The body 254 of the support 250 is configured to at least partially surround the insert 220. In some embodiments, the support 250 also includes a flange 256 configured to support the insert 220. The insert 220, container 230, sieve 240, and support 250 may advantageously (e.g., removably) be disposed together within cup 260. In a preferred embodiment, the support 250 is configured to minimize movement of the insert 220 and container 230 within cup 260 during centrifugal force application. Similarly, cup 260 may be sized to fit into a specific device (e.g., a centrifuge) that subjects a volume of fluid in insert 220 to centrifugal force.

[0058] Providing a support is optional. In embodiments without a support, for example, the insert may have a size and shape complementary to the inner surface of the cup, which is fitted in a device that applies centrifugal force (e.g., a centrifuge).

[0059] Figure 3B This is a schematic perspective view of another exemplary insert partially disposed within a container. In this embodiment, the external dimensions of the insert 320 are designed to fit within a cup 360, and the cup 360 also functions as a container to receive the separated photopolymerizable composition passing through the sieve 340 of the insert 320. Figure 3BThe embodiment shown is illustrated as an assembled form ready to withstand centrifugal force, including inserts 320 supported by a support 350, all of which are disposed within a container / cup 360. The upper portion of the insert 320 is positioned above the top of the container / cup 360. The support 350 of this embodiment includes an integral wall 355 surrounding at least some of the exterior of the insert 320 and providing stability to the insert 320 within the container / cup 360. The support 350 includes a plurality of legs 352 that support the support 350 within the container / cup 360 and will contact the separated photopolymerizable composition as it enters the container / cup 360 through a sieve 340. Other configurations providing inserts partially disposed within the container may be used.

[0060] See Figure 4 A schematic top view of an exemplary sieve 440 having a plurality of openings 442, each opening having a star shape, is provided. The shape of the sieve openings is not particularly limited and includes one or more of circular, elliptical, quadrilateral, triangular, or star shapes in some embodiments. In some embodiments, a suitable sieve is a woven material including quadrilateral (e.g., square or rectangular) openings. As described above, the sieve according to this disclosure defines a plurality of openings, each having a diameter of 10 micrometers to 200 micrometers. In some embodiments, the openings each have a diameter of 10 micrometers or larger, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 55 micrometers, 60 micrometers, 65 micrometers, 70 micrometers, or 75 micrometers or larger; and 200 micrometers or smaller, 190 micrometers, 180 micrometers, 170 micrometers, 160 micrometers, 150 micrometers, 140 micrometers, 130 micrometers, 120 micrometers, 110 micrometers, 100 micrometers, 95 micrometers, 90 micrometers, 85 micrometers, or 80 micrometers or smaller. The opening size can be selected based on a minimum opening size that will allow particulate packing material to pass through without becoming clogged before the separation of the photopolymerizable composition from the contaminants is completed.

[0061] Figure 4 Line 443 is shown, indicating the location where the diameter of a star-shaped opening 442 is measured. In this case, the star-shaped opening 442 has points of equal size, so the diameter 443 can be determined by measuring the length of a straight line starting from any point, passing through the center of the star, and extending to the opposite edge of the star-shaped opening 442. The positions of a point 444 and a center 445 are indicated on another star-shaped opening 442 (for clarity). If the points of the star are not all identical, the diameter 443 will be determined by measuring from the point furthest from the center of the star-shaped opening 442.

[0062] See Figure 5A schematic exploded perspective view of another exemplary insert 520 partially disposed within container 530 is provided. In this embodiment, insert 520 is integrally formed with support 550, and the support is sized to fit within cup 560. For example, the lower portion of the wall 522 of the insert may be configured to nest within the upper portion of the wall 532 of container 530. Other configurations providing inserts partially disposed within containers may be used. When the components are assembled, the upper portion of insert 520 will be positioned above the top of cup 560. The support 550 of this embodiment includes a plurality of (e.g., four) legs 552 to support insert 520 within cup 560. In this embodiment, sieve 540 is a first sieve, and insert 520 further includes a second sieve 546 disposed adjacent to the first sieve 540, wherein the second sieve 546 defines a plurality of openings, each opening having a diameter smaller than the plurality of openings of the first sieve 540. Using a first screen with a larger opening can retain larger contaminants (with less clogging compared to using only a second screen), while the second screen can retain smaller contaminants than the first screen. Figure 5 The embodiment shown also includes a removable screen stabilizer 529 that, when in place in the upper portion of the insert 520, tends to hold one or more screens 540, 546 in place, particularly when the screens (e.g., 546) comprise nonwoven fabric. In this embodiment, the removable screen stabilizer 529 has a cylindrical shape, but other shapes may also be useful. The removable screen stabilizer 529, the integral insert 520 and support 550, the screens 540 and 546, and the container 530 may be advantageously (e.g., detachably) arranged together within the cup 560.

[0063] Examples of typical contaminant materials that may be present in photopolymerizable compositions include, but are not limited to, one or more of oligomers, polymers, dust particles, lint, components formed from the polymer products of the photopolymerizable composition, or multiple cured voxels (e.g., very small components) formed from the photopolymerizable composition. Figure 6 These are photographs of contaminants recovered from a photopolymerizable composition, including components 602a and 602b formed from the polymerization products of the photopolymerizable composition, lint 604a and 604b, and multiple cured voxels 606. Component 602a has an irregular shape and may break off from a larger component. Component 602b has a rectangular prism shape. As used herein, the term "lint" includes fine fibers, which may exist alone, together with one or more other fine fibers, or as an accumulation of many fine fibers. Dust may also be present in or on the lint. Figure 6 In the image, two strands of cotton fibers 604a are visible on component 602b, as well as a single clump of cotton fibers 604b. Multiple solidified voxels 606 have a length of approximately 200 micrometers.

[0064] Optionally, the method according to this disclosure further includes step d) subjecting the separated photopolymerizable composition to homogenization. Homogenization can be used to ensure that any particulate filler present is generally uniformly suspended throughout the separated photopolymerizable composition. Homogenization can be performed using a kneader, manual mixer, high-speed mixer, ultrasonic mixer, mill, etc. In selected embodiments, a kneader or mixer is preferably used for homogenization. Homogenization can be performed under vacuum. Advantageously, when using a kneader, a vacuum can be applied during homogenization to remove dissolved gases and bubbles from the photopolymerizable composition. In some embodiments, a container compatible with the homogenization equipment for receiving the separated photopolymerizable composition can be selected, thus eliminating the need to transfer the separated photopolymerizable composition to a different container for homogenization. It should be noted that the centrifugal force applied to the fluid also tends to remove some bubbles from the photopolymerizable composition as it separates from contaminants. Similarly, in some embodiments, the method according to this disclosure further includes step e) subjecting the separated photopolymerizable composition to additional centrifugation to remove at least a portion of the dissolved gas or bubbles from the photopolymerizable composition.

[0065] In some embodiments, the method according to this disclosure further includes, prior to step a), f) selectively curing the initial photopolymerizable composition using photochemical radiation to provide a three-dimensional object and a fluid comprising the photopolymerizable composition and contaminants. As mentioned above, the initial photopolymerizable composition has not yet been subjected to photochemical radiation. The selective curing process used to form the three-dimensional object (e.g., additive manufacturing) also generates one or more contaminants in the fluid. There are no particular limitations on suitable photopolymerizable compositions to be selectively cured. One composition that can be used in the method according to this disclosure is as described in commonly owned International Application Publication No. WO 2018 / 231583 (Hermann et al.). For example, such a photopolymerizable composition may comprise:

[0066] The resin matrix comprises:

[0067] Polymerizable (meth)acrylates that do not contain a carbamate portion

[0068] Polymerizable urethane (meth)acrylates,

[0069] The amount of polymerizable (meth)acrylate excluding the carbamate portion exceeds that of the polymerizable carbamate (meth)acrylate.

[0070] The filler matrix comprises:

[0071] Nanoclusters,

[0072] Optional geothermal silica, preferably in an amount of less than 8% by weight.

[0073] The filler matrix is ​​preferably present in an amount of 5% to 45% by weight.

[0074] Initiator system, the initiator system comprising:

[0075] One or more photoinitiators,

[0076] Organic dyes,

[0077] The curable composition does not contain more than 5% by weight of a softener.

[0078] This is relative to the weight of the entire composition.

[0079] The curable composition can be cured at 23°C and 1 second. -1 It has a viscosity of less than 150 Pa*s at a shear rate.

[0080] Further details regarding such photopolymerizable (e.g., curable) compositions are described in WO 2018 / 231583 (Hermann et al.).

[0081] Selective curing of (initial or isolated) photopolymerizable compositions can advantageously be carried out via additive manufacturing, such as using stereolithography (e.g., compatibilized polymerization). Suitable additive manufacturing methods are discussed in more detail below with respect to the second aspect (i.e., the system).

[0082] In some embodiments, the method according to this disclosure further includes step g) moving the three-dimensional object, thereby generating a mass inertial force in the uncured photopolymerizable composition disposed on the three-dimensional object, thereby forming a coating of the uncured photopolymerizable composition on the three-dimensional object, wherein a centrifuge, shaker, or mixer spinning along one or more axes is used to generate the mass inertial force. In some embodiments, the coating of the uncured photopolymerizable composition on the three-dimensional object (after the application of the mass inertial force) has a thickness of 20 micrometers or greater, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, or 50 micrometers or greater; and 200 micrometers or less. In other embodiments, the mass inertial force is used to remove as much of the uncured photopolymerizable composition as possible from at least one surface of the three-dimensional object (e.g., thereby cleaning the uncured photopolymerizable composition from the three-dimensional object). Suitable methods for generating mass inertial forces are described, for example, in jointly owned international applications Publication No. WO 2019 / 102304 (Kirchner et al.) and No. WO 2020 / 157598 (Chakraborty et al.), the entire contents of which are incorporated herein by reference. For example, a centrifuge, shaker, or mixer that spins along one or more axes can be used to generate mass inertial forces. In some embodiments, the movement of the object is either rotation or spin. Therefore, the mass inertial force can be a centrifugal force. A suitable mixer that spins along more than one axis is a biaxial asymmetric centrifugal mixer, such as the DAC 400FVZ purchased from Flacktek, Landrum, SC, South Carolina. The biaxial asymmetric centrifugal mixer provides simultaneous biaxial spin, which automatically reorients the object during spin, tending to pull the uncured composition away from the concave features of the three-dimensional object within a short time period (e.g., 20 seconds, 15 seconds, or 10 seconds or less).

[0083] In selected embodiments, when subjected to centrifugal force in step c) of the method according to this disclosure, mass inertial forces can advantageously be applied to the three-dimensional object within the same insert. Further optionally, the same centrifugal force can be used to separate contaminants from the photopolymerizable composition and remove uncured photopolymerizable composition from the three-dimensional object, for example, typically simultaneously. In some embodiments, the uncured photopolymerizable composition can be collected in, for example, an automated platform changer with a cylinder, and in a container during the application of mass inertial forces (e.g., spin cleaning), the cylinder collecting dripped uncured photopolymerizable composition after the three-dimensional object has been removed from its bulk. Additional cleaning can also be performed to remove the uncured photopolymerizable composition from one or more outer or inner surfaces of the three-dimensional object, for example using solvents (e.g., water, alcohols and / or blends), compressed gases, or both.

[0084] When fluids are collected in a cleanroom atmosphere after the fabrication of a 3D object, further contamination of the collection source can be advantageously avoided. Furthermore, in cases where the bulk of the uncured photopolymerizable composition (e.g., retained in an additive manufacturing cylinder) contains part fragments, optionally, the entire remaining contents of the cylinder can be subjected to centrifugal force to separate at least the part fragments from the photopolymerizable composition, enabling continuous production of 3D objects from the photopolymerizable composition. Bulk recycling of the photopolymerizable composition would be useful in scenarios including, for example, when a print job fails and broken parts are present in the photopolymerizable composition, or after the (e.g., continuous) printing of many parts.

[0085] Optional post-processing of the formed 3D object may be performed, including, for example, post-curing, cleaning, or both. In some embodiments, the 3D object contains unreacted photopolymerizable components, and the method further includes: h) subjecting the 3D object to at least one of photochemical radiation or heat to cure the unreacted photopolymerizable components. Photochemical radiation treatment can be achieved using any convenient radiation source (typically UV radiation, visible light radiation, and / or electron beam radiation) for a duration ranging from about 1 to more than 60 minutes. Heating is typically performed in an inert atmosphere at a temperature ranging from about 50°C to 250°C for a duration ranging from about 10 minutes to more than 60 minutes. So-called post-curing ovens, which combine UV radiation and heat, are particularly suitable for use in the post-curing process. Generally, post-curing improves the mechanical properties and stability of the 3D object compared to the same uncured object.

[0086] In some embodiments, the method according to this disclosure further includes step i) analyzing at least one of the homogeneity or photoinitiator content of the separated photopolymerizable composition. In some embodiments, homogeneity is analyzed by measuring at least one of density, color, or filler content of multiple samples of the separated photopolymerizable composition. In some embodiments, homogeneity is analyzed by preparing a three-dimensional object from multiple samples of the separated photopolymerizable composition, subsequently testing mechanical properties (e.g., tensile strength), and measuring physical dimensions. Typically, samples of the separated photopolymerizable composition are formed by additive manufacturing or by using a mold and casting samples of the separated photopolymerizable composition to create test bars with shapes (e.g., dog-bone shapes) according to standard mechanical property testing methods. Testing mechanical properties can indicate whether the photoinitiator concentration has decreased from the initial photopolymerizable composition or whether homogeneity is lacking. If the physical dimensions of the object are smaller or larger than the design dimensions, the separated photopolymerizable composition may be under-cured or over-cured, respectively, and does not meet homogeneity requirements. Typically, for additive manufacturing suitability, photopolymerizable compositions must be stable to prevent significant separation of their components, at least within the time frame required to complete a printing job. Optionally, the photopolymerizable composition can be solvent-extracted to measure its particulate filler content, and preferably, several sections of the photopolymerizable composition are tested to determine whether the particulate filler content remains substantially the same throughout, indicating the homogeneity of the photopolymerizable composition. Suitable methods for analyzing photoinitiator content include each of infrared (IR) spectroscopy and high-performance liquid chromatography (HPLC).

[0087] In some embodiments, the method according to this disclosure further includes: step j) placing at least a portion of the separated photopolymerizable composition in an additive manufacturing apparatus; and k) selectively curing the separated photopolymerizable composition in the additive manufacturing apparatus using photochemical radiation to form a three-dimensional object. Additionally, in some embodiments, the method according to this disclosure further includes, prior to step j) or k), step l) blending at least a portion of the separated photopolymerizable composition with a volume of initial photopolymerizable composition. In at least some embodiments, the separated photopolymerizable composition has sufficient cleanliness to be used alone in place of unused (e.g., initial) photopolymerizable composition, or to be used in the same batch as unused (e.g., initial) photopolymerizable composition. Advantageously, such processes can be used in medical product processes by enabling recycling within a single batch and reusing the recycled photopolymerizable composition without actual batch mixing of materials. Furthermore, in practice, the photopolymerizable composition may only be in direct contact with a few simply shaped manufacturing parts, thereby allowing the photopolymerizable composition to be easily recycled by separating it from the parts and any contaminants.

[0088] In some embodiments, the method according to this disclosure further includes step m) cleaning the screen or replacing at least one of the screens once multiple openings become clogged with contaminants. After at least one use, the screen tends to become clogged with one or more contaminants, requiring washing or replacement with a clean screen. Furthermore, changing to a screen with a different opening size may be useful. In selected embodiments, when the screen is made of nylon, isopropanol is a suitable cleaning solvent for the screen. Optionally, disposable screens discarded after use may be employed.

[0089] system

[0090] In a second aspect, a system is provided. The system includes:

[0091] a) Additive manufacturing equipment;

[0092] b) Centrifuge; and

[0093] c) An insert configured to be inserted into a centrifuge, the insert comprising a sieve defining a plurality of openings, each opening having a diameter of 10 micrometers to 200 micrometers.

[0094] The method for printing three-dimensional objects described herein may include forming an article from multiple layers of the photopolymerizable composition described herein in a layer-by-layer manner. Furthermore, layers of the building material composition may be deposited in a computer-readable format based on an image of the three-dimensional object. In some or all embodiments, the photopolymerizable composition is deposited according to pre-selected computer-aided design (CAD) parameters (e.g., a data file).

[0095] Furthermore, it should be understood that the methods for manufacturing three-dimensional objects described herein may include so-called "stereopolymerization / compressive polymerization" 3D printing methods. Other 3D manufacturing techniques are known and may be suitably adapted for use in the applications described herein. More generally, 3D manufacturing techniques continue to be available. All such techniques are suitable for use with the photopolymerizable compositions described herein, provided they provide compatible manufacturing viscosity and resolution for the specified article properties. Manufacturing can be performed using data representing the 3D object, employing any of the manufacturing techniques described herein (alone or in combination), which may be reformatted or otherwise adapted as needed for specific printing or other manufacturing techniques.

[0096] It is entirely possible to form three-dimensional objects from the photopolymerizable compositions described herein using compatibilized polymerization (e.g., stereolithography). For example, in some cases, a method of printing a three-dimensional object includes retaining the photopolymerizable composition described herein in a fluid state in a container and selectively applying energy to the photopolymerizable composition in the container to solidify at least a portion of the fluid layer of the photopolymerizable composition, thereby forming a hardened layer defining a cross-section of the three-dimensional object. Alternatively, the method described herein may also include raising or lowering the hardened layer of the photopolymerizable composition to provide a new or second fluid layer of uncured photopolymerizable composition at the surface of the fluid in the container, and then selectively applying energy again to the photopolymerizable composition in the container to solidify at least a portion of the new or second fluid layer of the photopolymerizable composition to form a second cured layer defining a second cross-section of the three-dimensional object. Furthermore, the first and second cross-sections of the three-dimensional object can be bonded or adhered to each other in the z-direction (or the construction direction corresponding to the raised or lowered direction described above) by applying energy for solidifying the photopolymerizable composition. Furthermore, selectively applying energy to the photopolymerizable composition in the container may include applying photochemical radiation with sufficient energy, such as UV radiation, visible light radiation, or electron beam radiation, to cure the photopolymerizable composition. The method may also include planarization by raising or lowering a new layer of fluid photopolymerizable composition provided by a lifting platform. Such planarization may, in some cases, be performed using a wiper, roller, or recoater. Planarization corrects the thickness of one or more layers prior to curing by removing excess material by smoothing the dispersed material and creating a uniform, smooth, exposed, or flat-faced surface on the printer's support platform.

[0097] It should also be understood that the aforementioned process can be repeated a selected number of times to provide a three-dimensional object. For example, in some cases, this process can be repeated "n" times. Furthermore, it should be understood that one or more steps in the methods described herein, such as the step of selectively applying energy to the photopolymerizable composition layer, can be performed based on an image of a three-dimensional object in a computer-readable format. Suitable stereolithography printers include the Viper Pro SLA, purchased from 3D Systems, Rock Hill, SC, South Carolina, and the Asiga PICO PLUS 39, purchased from Asiga USA, Anaheim Hills, CA.

[0098] See Figures 2A to 2D Together, they illustrate an exemplary system that includes additive manufacturing equipment ( Figure 2A Centrifuge Figure 2B ) and inserts configured to be inserted into centrifuges ( Figures 2C to 2DThe insert includes a sieve defining multiple openings, each opening having a diameter of 10 micrometers to 200 micrometers. The above describes this in detail. Figure 2B , Figure 2C and Figure 2D Inserts for additive manufacturing equipment, centrifuges, and systems can be used in combination, for example, as discussed above with respect to the first aspect.

[0099] Figure 2A A stereolithography apparatus (“SLA”) is shown that can be used in a system with, for example, the photopolymerizable compositions and methods described herein. Generally, apparatus 200 may include a laser 202, optics 204, a steering mirror or lens 206, a lift 208, and a platform 210 within a cylinder 214 filled with a photopolymerizable composition 219. In operation, the laser 202 is directed through the wall 220 (e.g., the base plate) of the cylinder 214 and into the photocurable composition to cure a cross-section of the photocurable composition 219, thereby forming an article 217, after which the lift 208 slightly raises the platform 210 and another cross-section is cured. Suitable stereolithography printers include the NextDent 5100 and... Figure 4 Both were purchased from 3D Systems, Rock Hill, SC, South Carolina, and the Asiga PICO PLUS 39 was purchased from Asiga USA, Anaheim Hills, CA.

[0100] In some embodiments, compatibilizing polymerization involving digital light processing (“DLP”) employs a container of a curable polymer (e.g., a photopolymerizable composition). In a DLP-based system, a two-dimensional cross-section is projected onto the curable material to cure the desired portion transverse to the entire plane of the projected beam in a single pass. A suitable device for use with photopolymerizable compositions is the Rapid Shape D40 II DLP 3D printer (Rapid Shape GmbH, Heimsheim, Germany). All such curable polymer systems suitable for use with the photopolymerizable compositions described herein are intended to fall within the scope of “compensating polymerization” or “stereopolymerization” as used herein. In some embodiments, devices suitable for continuous operation can be employed, such as those commercially available from Carbon 3D, Inc. (Redwood City, CA), as described in, for example, U.S. Patents 9,205,601 and 9,360,757 (both granted to DeSimone et al.).

[0101] The insert, container, and one or more sieves are all as described above in detail with respect to the first aspect.

[0102] Various embodiments of methods and systems for removing contaminants from photopolymerizable compositions are provided.

[0103] In a first embodiment, this disclosure provides a method. The method includes: a) obtaining an insert comprising a sieve defining a plurality of openings, each opening having a diameter of 10 micrometers to 200 micrometers; b) placing a volume of fluid comprising a photopolymerizable composition and a contaminant into the insert; and c) subjecting the volume of fluid to centrifugal force to separate the contaminant from at least a portion of the photopolymerizable composition by retaining the contaminant in the insert and allowing at least a portion of the photopolymerizable composition to pass through the sieve of the insert, thereby providing a separated photopolymerizable composition.

[0104] In a second embodiment, this disclosure provides a method according to a first embodiment, the method further comprising: placing the insert in a centrifuge before or after placing the volume of fluid into the insert.

[0105] In a third embodiment, this disclosure provides a method according to a first embodiment, wherein at least a portion of the insert is disposed in a container configured to be assembled in a centrifuge, and a portion of the photopolymerizable composition passing through a sieve of the insert is collected in the container.

[0106] In a fourth embodiment, this disclosure provides a method according to a third embodiment, the method further comprising, prior to step c), placing a volume of fluid in a second insert in a centrifuge at a position opposite to the insert in step b) to balance the centrifuge.

[0107] In a fifth embodiment, this disclosure provides a method according to any one of the first to third embodiments, wherein the contaminant includes at least one of the following: oligomers, polymers, dust particles, lint, a plurality of cured voxels formed from a photopolymerizable composition, or a component formed from a polymer product of a photopolymerizable composition.

[0108] In a sixth embodiment, this disclosure provides a method according to any one of the first to fifth embodiments, wherein the photopolymerizable composition exhibits shear-thinning behavior.

[0109] In a seventh embodiment, this disclosure provides a method according to any one of the first to sixth embodiments, wherein the separated photopolymerizable composition further comprises particulate filler.

[0110] In an eighth embodiment, this disclosure provides a method according to a seventh embodiment, the method further comprising: d) subjecting the separated photopolymerizable composition to homogenization.

[0111] In the ninth embodiment, this disclosure provides the method according to the eighth embodiment, wherein homogenization is performed under vacuum.

[0112] In a tenth embodiment, this disclosure provides a method according to any one of the first to ninth embodiments, the method comprising subjecting a separated photopolymerizable composition to homogenization using a kneader or mixer.

[0113] In the eleventh embodiment, this disclosure provides a method according to any one of the first to tenth embodiments, wherein step c) is performed under environmental pressure.

[0114] In the twelfth embodiment, this disclosure provides a method according to any one of the first to eleventh embodiments, wherein the plurality of openings of the sieve include circular, elliptical, quadrilateral, triangular, or star-shaped shapes.

[0115] In the thirteenth embodiment, this disclosure provides a method according to any one of the first to twelfth embodiments, wherein a plurality of openings of the sieve each have a diameter of 20 micrometers or greater, 30 micrometers or greater, 40 micrometers or greater, 50 micrometers or greater, or 60 micrometers or greater; and a diameter of 100 micrometers or less, 90 micrometers or less, or 80 micrometers or less.

[0116] In the fourteenth embodiment, this disclosure provides a method according to any one of the first to thirteenth embodiments, wherein the sieve is a first sieve, and the insert further includes a second sieve disposed adjacent to the first sieve, wherein the second sieve defines a plurality of openings, each opening having a diameter smaller than that of the plurality of openings of the first sieve.

[0117] In the fifteenth embodiment, this disclosure provides a method according to any one of the first to fourteenth embodiments, wherein in step c), the fluid is subjected to a centrifugal force greater than 1G.

[0118] In a sixteenth embodiment, this disclosure provides a method according to any one of the first to fifteenth embodiments, the method further comprising: e) subjecting the separated photopolymerizable composition to additional centrifugation to remove at least a portion of the dissolved gas or bubbles from the photopolymerizable composition.

[0119] In the seventeenth embodiment, this disclosure provides a method according to any one of the first to sixteenth embodiments, the method further comprising, prior to step a),: f) selectively curing an initial photopolymerizable composition using photochemical radiation to provide a three-dimensional object and a fluid comprising the photopolymerizable composition and a contaminant.

[0120] In the eighteenth embodiment, this disclosure provides a method according to the seventeenth embodiment, the method further comprising: g) moving a three-dimensional object and thereby generating a mass inertial force in a portion of the fluid arrangement on the three-dimensional object, wherein the mass inertial force is generated using a centrifuge, shaker, or mixer that spins along one or more axes.

[0121] In a nineteenth embodiment, this disclosure provides a method according to an eighteenth embodiment, wherein a coating of an uncured photopolymerizable composition is formed on a three-dimensional object by generating a mass inertial force, the coating having a thickness of 20 micrometers or greater, 30 micrometers or greater, 40 micrometers or greater, or 50 micrometers or greater.

[0122] In the twentieth embodiment, this disclosure provides a method according to any one of the seventeenth to nineteenth embodiments, wherein the three-dimensional object comprises an unreacted photopolymerizable component, and wherein the method further comprises: h) subjecting the three-dimensional object to at least one of photochemical radiation or heat to cure the unreacted photopolymerizable component.

[0123] In the twenty-first embodiment, this disclosure provides a method according to any one of the first to twenty-twentieth embodiments, the method further comprising: i) analyzing at least one of the homogeneity or photoinitiator content of the separated photopolymerizable composition.

[0124] In a twenty-second embodiment, this disclosure provides a method according to a twenty-first embodiment, wherein homogeneity is analyzed by measuring at least one of density, color, mechanical properties and / or physical dimensions of a three-dimensional object formed from a separated photopolymerizable composition, or filler content of a plurality of samples of the separated photopolymerizable composition.

[0125] In the twenty-third embodiment, this disclosure provides a method according to the twenty-first or twenty-second embodiment, wherein the photoinitiator content is analyzed by at least one of infrared (IR) spectroscopy or high-performance liquid chromatography (HPLC).

[0126] In the twenty-fourth embodiment, this disclosure provides a method according to any one of the first to twenty-third embodiments, the method further comprising: j) placing at least a portion of the separated photopolymerizable composition in an additive manufacturing apparatus; and k) selectively curing the separated photopolymerizable composition in the additive manufacturing apparatus using photochemical radiation to form a three-dimensional object.

[0127] In the twenty-fifth embodiment, this disclosure provides a method according to the twenty-fourth embodiment, the method further comprising, prior to step j) or k),: l) blending at least a portion of the separated photopolymerizable composition with a volume of the initial photopolymerizable composition.

[0128] In the twenty-sixth embodiment, this disclosure provides a method according to any one of the first to twenty-fifth embodiments, the method further comprising: m) cleaning the screen or replacing at least one of the screens once the plurality of openings of the screen are blocked by contaminants.

[0129] In a twenty-seventh embodiment, this disclosure provides a system. The system includes: a) additive manufacturing equipment; b) a centrifuge; and c) an insert configured to be inserted into the centrifuge. The insert includes a sieve defining a plurality of openings, each opening having a diameter of 10 micrometers to 200 micrometers.

[0130] In the twenty-eighth embodiment, this disclosure provides a system according to the twenty-seventh embodiment, the system further comprising a container configured to be inserted into a centrifuge, wherein at least a portion of the insert is sized to fit within the container.

[0131] In the twenty-ninth embodiment, this disclosure provides a system according to the twenty-eighth embodiment, wherein the volume of the container is larger than the size of the insert and is designed to be assembled in at least a portion of the volume of the container.

[0132] In the thirtieth embodiment, this disclosure provides a system according to any one of the twenty-seventh to twenty-nine embodiments, wherein the plurality of openings of the sieve include circular, elliptical, quadrilateral, triangular, or star-shaped shapes.

[0133] In the thirty-first embodiment, this disclosure provides a system according to any one of the twenty-seventh to thirtyth embodiments, wherein the plurality of openings of the sieve each have a diameter of 20 micrometers or greater, 30 micrometers or greater, 40 micrometers or greater, 50 micrometers or greater, or 60 micrometers or greater; and a diameter of 100 micrometers or less, 90 micrometers or less, or 80 micrometers or less.

[0134] In the thirty-second embodiment, this disclosure provides a system according to any one of the twenty-seventh to thirty-first embodiments, wherein the sieve is a first sieve, and the insert further includes a second sieve disposed adjacent to the first sieve, wherein the second sieve defines a plurality of openings, each opening having a diameter smaller than that of the plurality of openings of the first sieve.

[0135] In the thirty-third embodiment, this disclosure provides a system according to any one of the twenty-seventh to thirty-second embodiments, the system further comprising a removable screen stabilizer.

[0136] In the thirty-fourth embodiment, this disclosure provides a system according to any one of the twenty-seventh to thirty-third embodiments, wherein the centrifuge includes a sensor that measures imbalance and terminates centrifugal force if the imbalance exceeds a threshold amount.

[0137] The following examples are shown to illustrate additional features and embodiments of the invention. Unless otherwise specified, all parts are by weight.

[0138] Example

[0139] The following examples further illustrate the objects and advantages of the invention, but the specific materials and quantities listed in these examples, as well as other conditions and details, should not be construed as undue limitation of the invention. These examples are for illustrative purposes only and are not intended to limit the scope of the appended claims. Unless otherwise specified or readily apparent from the context, all parts, percentages, ratios, etc., in the examples and the remainder of the specification are by weight.

[0140] Table 1: Materials

[0141]

[0142] Test methods

[0143] Viscosity

[0144] Viscosity was measured using a Physica Rheometer MCR 301 apparatus with a plate / plate system (15 mm in diameter) and a 0.2 mm slit. The pre-shearing step was performed by applying a 100-second pressure. -1 A constant shear rate of 120 seconds was applied, followed by an application of shears from 100 seconds. -1 up to 0.001s -1 The decreasing shear rate was determined (in 60 exponential decreasing steps). Finally, the viscosity value (Pas) at 23°C was recorded for each shear rate (from 0.001 s⁻¹). -1 Start to 1.000s -1(In 60 exponentially increasing steps). For each shear rate, a 5-second delay is typically used before data acquisition. The measurement method mentioned above is essentially in accordance with DIN 53018-1.

[0145] Insert manufacturing

[0146] Inserts are designed using computer-aided design (CAD), and components (excluding the screen fabric) are 3D printed from polylactic acid (PLA) using a fused deposition modeling (FDM) printer (Anycubic Predator).

[0147] Preparation of initial photopolymerizable compositions

[0148] Example 1

[0149] Compositions having the formulations in Table 2 were prepared. This corresponds to Example 6 in International Patent Application WO 2018 / 231583 (Herrmann et al.). The amounts of the components are given as weight percentages (%):

[0150] Table 2 .

[0151] <![CDATA[ [weight%] ]]> LUCIRIN TPO 0.8050 LUMILUX Blau LZ 0.0020 IONOL 0.0407 D-Zethacrylate 59.5779 DESMA 6.5223 HDK H-2000 2.5341 SG-YBF 100 3.3879 Zr / Si nanoclusters 27.1301

[0152] Based on the viscosity testing method described above, the viscosity measurement of the initial photopolymerizable composition in Example 1 yielded the following results:

[0153] Table 3 .

[0154] Shear rate Example 1 <![CDATA[0.1s -1 ]]> <![CDATA[1s -1 ]]> <![CDATA[10s -1 ]]> <![CDATA[100s -1 ]]> average value 67.9 Pa s 20.1 Pa s 8.0 Pa s 5.0 Pa s

[0155] Print

[0156] Using a Rapid Shape D90 Triple Fine SLA printer with an automatic platform changer (Rapid Shape GmbH, Heimsheim, Germany), 1920 dental crowns with supporting structures were produced using the initial photopolymerizable composition of Example 1 specified above. The printing parameters were as follows: light energy 100 W / m². 2 35-micron pixel size, 50-micron layer height, 1-second exposure time.

[0157] Fluid collection

[0158] Each of the eight platform changer slots on the Rapid Shape D90 Triple Fine SLA printer has a coating paper (3M ESPE mixing pad, 3M Oral Care, Seefeld, Germany) to collect uncured photopolymerized composition that drips from the build plate after printing. After the print job, the dripping material in the platform changer is collected from the coating paper in a collection container using a silicone doctor blade.

[0159] Insert component

[0160] Cut a piece of sieve cloth (63 micron mesh, approximately 120 × 120 mm) from the roll / block using a pair of scissors. Place the first sieve cloth holder in the insert body. Next, place the sieve cloth on top of the sieve cloth holder. Place the second sieve cloth holder on the sieve. Attach the upper portion of the insert (e.g., a removable sieve stabilizer) to the top of the second sieve cloth holder. Next, attach a container for collecting the separated photopolymerizable composition (e.g., recycled material) to the bottom side of the insert body. Then, provide 100 g of fluid (e.g., contaminated material) to the upper portion of the insert. Weigh the entire assembly, including the fluid, using a laboratory balance. Prepare the second insert in the same manner as described above. To avoid imbalance during centrifugation, add fluid to the second insert until both components have the same weight. Then insert the components into centrifuge cups and place them in the centrifuge, diametrically opposed to each other.

[0161] Centrifugation

[0162] A Sigma 6-15 laboratory centrifuge (SigmaLaborzentrifugen GmbH, Osterode, Germany) was used for the centrifugation step. The equilibration unit in the centrifuge was used to centrifuge at 350 rpm for 2 minutes. After centrifugation, due to centrifugal force, the photopolymerizable composition from the upper portion of the insert is forced through a sieve and into a container (e.g., a rapid mixer cup) for separation of the photopolymerizable composition (e.g., recycled material). The container with the separated photopolymerizable composition was then capped and labeled.

[0163] Preparation for the next centrifugation run

[0164] Will Figure 5 All parts of the assembly described herein are disassembled and cleaned with alcohol. Used screen cloth containing filter cake can be discarded or washed with ethanol and reused.

[0165] Evaluation of filter cake

[0166] To inspect the filter cake, the screen cloth, including the filter cake cloth, was immersed in isopropyl alcohol (IPA) to wash away residual resin. After drying the filter cake in a fume hood, its solids content was examined under a microscope. Typical contents were observed in the filter cake, namely tiny broken parts (e.g., fragments supporting the geometry), semi-solidified residues, and lint, as described above relative to... Figure 6 As stated above.

[0167] All patents, patent documents, and publications cited herein are incorporated herein by reference in their entirety as if each document were cited individually. In the event of any conflict or contradiction between the disclosures in this written specification and any documents incorporated herein by reference, the written specification shall prevail. Various modifications and alterations to this disclosure will become apparent to those skilled in the art without departing from its scope and spirit. It should be understood that this disclosure is not intended to be unduly limited to the exemplary embodiments and examples shown herein, and such embodiments and examples are presented by way of example only. The scope of this disclosure is intended to be limited only by the claims shown herein.

Claims

1. A method for processing a photopolymerizable composition, the method comprising: a) Obtaining an insert comprising a sieve defining a plurality of openings, each opening having a diameter of 10 micrometers to 200 micrometers, wherein at least a portion of the insert is disposed in a container configured to be assembled in a centrifuge. b) A certain volume of fluid is placed in the insert, wherein the fluid contains an uncured photopolymerizable composition and contaminants; as well as c) subjecting the fluid of a given volume to centrifugal force to separate the contaminant from at least a portion of the photopolymerizable composition by retaining the contaminant in the insert and passing at least a portion of the photopolymerizable composition through the sieve of the insert and being collected in the container, thereby providing a separated photopolymerizable composition.

2. The method according to claim 1, wherein the contaminant comprises at least one of the following: oligomers, polymers, dust particles, lint, a plurality of cured voxels formed from the photopolymerizable composition, or a component formed from the polymerization product of the photopolymerizable composition.

3. The method according to claim 1, wherein the photopolymerizable composition exhibits shear-thinning behavior.

4. The method of claim 1, wherein the separated photopolymerizable composition further comprises particulate filler, and the method further comprises: d) subject the separated photopolymerizable composition to homogenization.

5. The method of claim 4, wherein the homogenization is performed under vacuum.

6. The method of claim 1, wherein step c) is performed under environmental pressure.

7. The method of claim 1, wherein the sieve is a first sieve, and the insert further comprises a second sieve disposed adjacent to the first sieve, wherein the second sieve defines a plurality of openings, each opening having a diameter smaller than that of the plurality of openings of the first sieve.

8. The method according to claim 1, further comprising: e) subject the separated photopolymerizable composition to additional centrifugation to remove at least a portion of the dissolved gas or bubbles from the photopolymerizable composition.

9. The method according to claim 1, further comprising, before step a): f) Selectively curing an initial photopolymerizable composition using photochemical radiation to provide a three-dimensional object and the fluid comprising the photopolymerizable composition and the contaminant.

10. The method according to claim 9, further comprising: g) Move the three-dimensional object and thereby generate a mass inertial force in the fluid disposed on the three-dimensional object, wherein the mass inertial force is generated using a centrifuge, shaker or mixer that spins along one or more axes.

11. The method according to claim 1, further comprising: i) Analyze at least one of the homogeneity or photoinitiator content of the separated photopolymerizable composition.

12. The method according to claim 1, further comprising: j) Placing at least a portion of the separated photopolymerizable composition in an additive manufacturing apparatus; and k) selectively curing the separated photopolymerizable composition using photochemical radiation in the additive manufacturing apparatus to form a three-dimensional object.

13. The method according to claim 12, further comprising, before step j) or step k): l) Blend at least a portion of the separated photopolymerizable composition with a certain volume of the initial photopolymerizable composition.

14. A system for processing photopolymerizable compositions, the system comprising: a) Additive manufacturing equipment; b) Centrifuge; c) An insert configured to be inserted into the centrifuge, the insert comprising a sieve defining a plurality of openings, each opening having a diameter of 10 micrometers to 200 micrometers; as well as d) A container configured to be assembled in the centrifuge, wherein at least a portion of the insert is disposed in the container, wherein the insert and the container are configured to receive a volume of fluid containing an uncured photopolymerizable composition and contaminants, and during centrifugation, the contaminants are retained in the insert while the photopolymerizable composition passes through the sieve into the container.

15. The system of claim 14, wherein the volume of the container is greater than the volume of the at least portion in which the insert is designed to be assembled.

16. The system of claim 14, wherein the sieve is a first sieve, and the insert further comprises a second sieve disposed adjacent to the first sieve, wherein the second sieve defines a plurality of openings, each opening having a diameter smaller than that of the plurality of openings of the first sieve.

17. The system of claim 14, wherein the centrifuge includes a sensor that measures imbalance and terminates centrifugal force if the imbalance exceeds a threshold amount, or measures the fill level in the insert.

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