Thiol-acrylate elastomer for three-dimensional printing

Abstract

To provide a thiol-acrylate photo-polymerizable resin composition.SOLUTION: A resin composition may be used for additive manufacturing. One embodiment of the invention includes a photo-polymerizable resin for additive manufacturing, the resin comprises an acrylate oligomer, a methacrylate monomer, and a thiol, and the resin may be configured to react by exposure to light to form a cured material. The resin may further comprise one or more oligomeric additives, for example, polyether oligomeric additives such as poly-tetrahydrofuran.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Application No. 62 / 877,832, filed July 23, 2019, the entire contents of which are incorporated herein by reference. FIELD OF THE INVENTION The present invention relates generally to the field of additive manufacturing, and more particularly to three-dimensional (3D) printing materials, methods, and articles made therefrom. [Background technology]

[0002] background Additive manufacturing, or 3D printing, is a process that produces 3D objects through the selective layer-by-layer deposition of material under computer control. This process allows a digital file to be turned into a physical object through the layer-by-layer patterning of material. The process involves slicing the digital file into layers and printing each layer sequentially until the entire object is formed. Once complete, excess material, such as support structures, can be removed.

[0003] One category of additive manufacturing process is vat photopolymerization, which produces 3D objects from liquid photopolymerizable resins by sequentially applying and selectively curing the liquid photopolymerizable resins using light such as ultraviolet, visible, or infrared light.

[0004] Vat-based photopolymerization additive manufacturing methods include SLA (Stereolithography) and DLP (Digital Light Processing). Generally, SLA and DLP systems include a resin vat, a light source, and a build platform. Laser-based SLA uses a laser light source to cure the resin voxel by voxel. Digital Light Processing (DLP) uses a projector light source (such as an LED light source) to illuminate and cure an entire layer at once. The light source can be located above or below the resin vat.

[0005] Generally, SLA and DLA printing methods involve applying a layer of liquid resin onto a build platform. For example, the build platform is lowered into a vat of resin to apply the resin layer. The liquid resin layer is then selectively exposed to light from a light source to cure selected voxels within the resin layer. For example, the light source can be applied from below through a window in the bottom of the vat (bottom-up printing) or from above the vat (top-down printing). These steps are repeated to build subsequent layers until the 3D object is formed.

[0006] Liquid photopolymerizable resins for 3D printing cure or solidify upon exposure to light. Examples of such applications include liquid photocurable thiol-ene and thiol-epoxy resins. Thiol-ene resins polymerize through the reaction of mercapto compounds (-SH, "thiol") with C=C double bonds in "ene" compounds, such as (meth)acrylate, vinyl, allyl, and norbornene functional groups. In photoinitiated thiol-ene systems, the reaction occurs via the radical addition of a thiyl radical to an electron-rich or electron-poor double bond. The nature of the double bond influences the rate of the reaction. A thiyl radical is generated by the elimination of a hydrogen radical, which then reacts with the double bond, cleaving it and forming a radical intermediate at the β-carbon of the ene. This carbon radical then detaches a proton radical from the adjacent thiol via chain transfer, restarting the reaction until all reactants are consumed or trapped. In the case of di- and polyfunctional thiols and enes, polymer chains and networks are formed by a radical-driven stepwise growth mechanism. Thiol-ene polymerization can occur either by radical transfer from a photoinitiator or by direct spontaneous triggering by UV irradiation (nucleophilic Michael addition is also possible between unstabilized thiols and reactive enes).

[0007] For example, thiol-ene photopolymerizable resins, when cast and cured, result in polymers with high crosslink uniformity and narrow glass transition temperatures (Roper et al. 2004). These thiol-ene resins typically contain molar ratios of thiol to ene monomer components between 1:1, 1:1, and 20:80 (Hoyel et al. 2009). Furthermore, thiol-ene resins containing specific ratios of pentaerythritol tetrakis(3-mercaptopropionate) and polyethylene glycol, ranging from 1:1 to 2:1, have been used in 3D printing processes (Gillner et al. 2015).

[0008] Oxygen inhibition can be a problem in additive manufacturing using liquid photopolymerizable resins. Typically, in vat-photopolymerization additive manufacturing systems, the resin vat is opened and exposed to the ambient air during printing. This allows oxygen to dissolve and diffuse into the liquid resin. Oxygen molecules scavenge the radical species necessary for curing. Therefore, oxygen has an inhibitory effect, slowing the curing rate and increasing manufacturing time. Incomplete curing due to oxygen inhibition can result in 3D objects with very sticky and undesirable surface properties. Furthermore, in top-down printing systems, the outermost surface of the resin, where the oxygen concentration is highest, is also the interface where the next resin layer is applied. Oxygen generation at this interface inhibits polymerization between the polymer chains of adjacent resin layers, reducing the adhesion between the layers of the 3D printed object ("interlayer adhesion"). To mitigate the effects of oxygen, nitrogen blankets are used to prevent oxygen from diffusing to the exposed top surface of the resin, but this technique is expensive and adds complexity to the manufacturing system.

[0009] Another problem that can be encountered is the limited shelf-life stability of polymerizable resins due to, for example, free radical polymerization caused by ambient heat. To prevent undesired polymerization during storage, resin components are often refrigerated or mixed with stabilizers such as sulfur, triallyl phosphate, and aluminum salts of N-nitrosophenylhydroxylamine. However, the use of such stabilizers not only increases production costs, but also can lead to stabilizer contamination of the polymerized product.

[0010] Another issue is that some liquid polymerizable resins do not exhibit low viscosity. While suitable for some casting applications, these high viscosity resins can slow down 3D printing speeds and limit the production process.

[0011] Additionally, the thiols contained in resins can have an unpleasant odor. This limits the ability to use high-thiol-content resins in open-air applications such as 3D printing. Furthermore, compositions made from thiol-ene resins with high thiol content can retain these unpleasant odors upon partial or incomplete photocuring. To mitigate the effects of thiol odor, "masking agents" or low-odor thiols (i.e., high-molecular-weight thiols) have been used (Roper et al. 2004). However, incorporating such masking agents can be expensive in the manufacturing process and potentially cause unwanted contamination of the polymerized composition. Furthermore, low-odor, high-molecular-weight thiols are also expensive.

[0012] Additionally, compositions made from thiol-containing resins suffer from anisotropic effects, resulting in x- and y-axis broadening, which in 3D printing applications leads to loss of fidelity and blurred edges in printed articles.

[0013] Another problem is that 3D objects produced by additive manufacturing of liquid photopolymerizable resins exhibit undesirable mechanical properties (e.g., tensile modulation and strength, elongation performance and / or impact strength).

[0014] Elastomers can exhibit phase separation. The hard phase reinforces the elastomer and provides mechanical strength, while the soft phase provides elongation and elastic response. If the hard phase dominates, a plastic may form. If the soft phase dominates, the hard phases may not interact well, resulting in a soft and weak material. If the phases are not well separated, the material may become viscoelastic, with high energy absorption properties and slow recovery from mechanical deformation. The hard phase may be formed from filler particles, crystalline domains, or high glass transition segments. The soft domains may be amorphous, have low Tg segments, or have low crosslink density.

[0015] Polymers are characterized by their primary structure (monomers), secondary structure (the order in which the monomers are bonded), and tertiary structure. Tertiary structure is related to the interactions of polymer chains in the bulk phase. For example, hard and soft blocks are separated into geographically distinct domains (e.g., SBS rubber and TPU). The structure of a polymer (e.g., the presence of geographically separated hard and soft domains) can be related to the properties of the elastomer (e.g., the size and thermal transitions of the hard and soft domains).

[0016] Materials used in 3D printers may need to be able to form thin deposited layers that retain the pattern. Not all polymers or elastomers are suitable for additive manufacturing. For example, elastomeric materials may form too slowly, not retain a patterned shape, be too viscous, or not be reasonably patternable layer by layer. Summary of the Invention [Problem to be solved by the invention]

[0017] To solve the above problems, improvements are needed for resin materials for three-dimensional (3D) printing, and in particular for elastomer materials for three-dimensional (3D) printing. [Brief explanation of the drawings]

[0018] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] FIG. 1 shows the tensile stress-strain behavior at 20° C. of a thiol acrylate resin containing the components shown in Table 1.

[0019] [Figure 2] Figure 2 shows the tensile stress-strain behavior at 20°C of a thiol acrylate resin containing the components shown in Table 2.

[0020] [Figure 3]FIG. 3 shows the Tan Delta versus temperature profile obtained from the dynamic mechanical analysis of a thiol acrylate resin containing the components shown in Table 2.

[0021] [Figure 4] FIG. 4 shows the temperature and weight change during the decomposition reaction of a thiol acrylate resin containing the components shown in Table 2.

[0022] [Figure 5] Figure 5 shows the dynamic mechanical analysis of BF0601.

[0023] [Figure 6] FIG. 6 shows the results of differential scanning calorimetry of cast "BF0601."

[0024] [Figure 7] Figure 7 shows the relationship between viscosity and temperature for BF0601 resin.

[0025] [Figure 8] Figure 8 shows the tensile stress versus strain behavior of cast "BF0601".

[0026] [Figure 9] Figure 9 shows the tensile stress versus strain behavior of cast "BF0601".

[0027] [Figure 10] Figure 10 shows the tensile stress versus strain behavior of printed BF0601.

[0028] [Figure 11] Figure 11 shows the tensile stress versus strain behavior of printed BF0601.

[0029] [Figure 12] FIG. 12 shows the dynamic mechanical analysis of printed BF1307.

[0030] [Figure 13] Figure 13 shows the thermogravimetric analysis results of printed BF1307.

[0031] [Figure 14] FIG. 14 shows the differential scanning calorimetry results of printed BF1307.

[0032] [Figure 15] FIG. 15 shows the Fourier transform infrared spectroscopy (FTIR) results of printed BF1307.

[0033] [Figure 16] Figure 16 shows the tensile stress versus strain behavior of cast "BF1307".

[0034] [Figure 17] Figure 17 shows the tensile stress versus strain behavior of printed BF1307.

[0035] [Figure 18] Figure 18 shows the thermogravimetric analysis results of printed BG1002.

[0036] [Figure 19] FIG. 19 shows the differential scanning calorimetry results of printed BG1002.

[0037] [Figure 20] FIG. 20 shows the FTIR (Fourier Transform Infrared Spectroscopy) results of printed BG1002.

[0038] [Figure 21] FIG. 21 shows the tensile stress versus strain behavior of cast BG1002.

[0039] [Figure 22] Figure 22 shows the tensile stress versus strain behavior of printed BG1002.

[0040] [Figure 23] Figure 23 shows the thermogravimetric analysis results of printed BG2301.

[0041] [Figure 24] Figure 24 shows the differential scanning calorimetry results of printed BG2301.

[0042] [Figure 25] Figure 25 shows the tensile stress versus strain behavior of printed BG2301.

[0043] [Figure 26] Figure 26 is a dynamic mechanical analysis of printed BG0800.

[0044] [Figure 27] Figure 27 shows the thermogravimetric analysis results of printed BG0800.

[0045] [Figure 28] Figure 28 shows the differential scanning calorimetry results of printed BG0800.

[0046] [Figure 29] Figure 29 shows the differential scanning calorimetry results of printed BG0800.

[0047] [Figure 30] FIG. 30 shows the FTIR (Fourier Transform Infrared) results of printed BG0800.

[0048] [Figure 31] FIG. 31 shows the FTIR (Fourier Transform Infrared) results of printed BG0800.

[0049] [Figure 32] Figure 32 shows the tensile stress versus strain behavior of cast BG0800.

[0050] [Figure 33] Figure 33 shows the tensile stress versus strain behavior when printing BG0800.

[0051] [Figure 34] Figure 34 shows the tensile stress versus strain behavior when printing BG0800.

[0052] [Figure 35] Figure 35 shows the tensile stress versus strain behavior when printing BG0800. DETAILED DESCRIPTION OF THE INVENTION

[0053] overview The present disclosure relates to thiol-acrylate photopolymerizable resin compositions that may be used in additive manufacturing.

[0054] One embodiment of the present invention includes a photopolymerizable resin for additive manufacturing in an oxygen environment, the resin including a crosslinking component; at least one monomer and / or oligomer; and a chain transfer agent including at least one of a thiol, a secondary alcohol, and / or a tertiary amine, the resin optionally configured to react to form a cured product upon exposure to light.

[0055] In some embodiments, the chain transfer agent is configured to allow at least some bonding between the earlier-cured resin layer and the adjacent later-cured resin layer despite the presence of an oxygen-rich surface on the earlier-cured resin layer at the interface between the earlier-cured resin layer and the later-cured resin layer.

[0056] In some embodiments, the invention includes a photopolymerizable resin for additive manufacturing printing in an oxygen environment, the resin comprising: a photoinitiator configured to generate free radicals upon exposure to light; a crosslinking component; at least one monomer and / or oligomer; wherein the crosslinking component and the at least one monomer and / or oligomer are configured to react with the free radicals to provide growth of at least one polymer chain radical within the volume of the photopolymerizable resin, and the at least one polymer chain radical reacts with diffused oxygen to provide an oxygen radical; and a chain transfer agent comprising at least one of a thiol, a secondary alcohol, and / or a tertiary amine, wherein the chain transfer agent is configured to transfer the oxygen radical to initiate growth of at least one new polymer chain radical.

[0057] In some embodiments, the present invention includes a photopolymerizable resin comprising: a crosslinking component; at least one monomer and / or oligomer, wherein the crosslinking component and the at least one monomer and / or oligomer are configured to react to provide one or more polymer chains after exposure to light; and a chain transfer agent comprising at least one of a thiol, a secondary alcohol, and / or a tertiary amine, wherein the chain transfer agent is configured to transfer a free radical associated with one of the polymer chains to another of the polymer chains.

[0058] In some embodiments, the invention includes a storage-stable photopolymerizable resin mixture comprising at least one monomer and / or oligomer, the at least one monomer and / or oligomer comprising one or more acrylic monomers, the one or more acrylic monomers being at least about 50% by weight of the resin; and less than about 5% of a stabilizing thiol comprising one or more thiol functional groups, the stabilizing thiol being configured to inhibit nucleophilic substitution reactions between the one or more thiol functional groups and the one or more monomers or oligomers. The components of the resin mixture can be combined and stored in a single pot at room temperature for at least six months without the viscosity of the resin increasing by more than 2%, 5%, 10%, 25%, 50%, or 100%.

[0059] Another embodiment of the invention includes a photopolymerizable resin for additive manufacturing, the resin comprising a crosslinking component, at least one monomer and / or oligomer, and a photoinitiator, the photoinitiator configured to generate free radicals upon exposure to light, the free radicals initiating a chain reaction between the crosslinking component and the at least one monomer and / or oligomer to provide one or more polymer chains within the volume of the photopolymerizable resin; and a chain transfer agent comprising at least one of a thiol, a secondary alcohol, and / or a tertiary amine, the chain transfer agent configured to re-initiate the chain reaction to provide one or more new polymer chains within the volume of the photopolymerizable resin, wherein a layer of the resin about 100 μm thick is configured to form a cured product in 30 seconds or less, and the resin has a viscosity at room temperature of less than 1,000 centipoise.

[0060] Another embodiment of the invention includes a photopolymerizable resin for additive manufacturing, the resin comprising less than 5% thiol, at least about 50% of one or more monomers, and a photoinitiator, the photoinitiator configured to form free radicals upon exposure to light, the free radicals initiating growth of one or more polymer chains comprising at least difunctional and monofunctional monomers, the thiol configured to promote continued growth of the one or more polymer chains, the resin configured to react upon exposure to light to form a cured product, the cured product having a glass transition temperature in the range of about 5-30°C.

[0061] Another embodiment of the invention includes a photopolymerizable resin for additive manufacturing, the resin comprising less than about 5% thiol and at least about 50% one or more monomers, the resin configured to react to form a cured product, the cured product having a fluence of about 3-30 MJ / m 3 and a breaking strain in the range of about 30 to 300%.

[0062] Another embodiment of the invention includes a photopolymerizable resin for additive manufacturing, the resin comprising less than about 5% thiol and at least about 60% one or more monomers, the resin configured to react upon exposure to light to form a cured product, the cured product having a light output of about 3-100 MJ / m 3 and a breaking strain in the range of about 200 to 1000%.

[0063] Another embodiment of the invention includes a photopolymerizable resin for additive manufacturing, the resin comprising at least one monomer and / or oligomer and less than about 20% thiol, the resin configured to react upon exposure to light to provide a cured product, the cured product containing less than 1 part per billion thiol volatiles in an oxygen environment over 50 seconds at ambient temperature and pressure.

[0064] Another embodiment of the present invention includes a photopolymerizable resin for additive manufacturing, the resin comprising about 5-15 phr of a thiol, about 20-60% of a difunctional acrylic oligomer, and about 40-80% of one or more monofunctional acrylic monomers, the resin configured to react to form a cured product upon exposure to light.

[0065] Another embodiment of the present invention includes a photopolymerizable resin for three-dimensional printing, the resin comprising at least one of about 5-20 phr of a thiol, about 0-5 phr of a polydimethylsiloxane acrylate copolymer, about 20-100% of a difunctional acrylic oligomer, and about 0-80% of a monofunctional acrylic monomer, the resin configured to react to form a cured product upon exposure to light.

[0066] Another embodiment of the present invention includes a photopolymerizable resin for three-dimensional printing, the resin comprising about 5-10 phr of a thiol, about 0-20% trimethylolpropane triacrylate, about 30-50% at least one difunctional acrylic oligomer, about 50-86% isobornyl acrylate, and about 0-21% hydroxypropyl acrylate, the resin configured to react upon exposure to light to form a cured product.

[0067] Another embodiment of the present invention includes a photopolymerizable resin compatible with three-dimensional printing, the resin comprising about 4-6 phr pentaerythritol tetrakis(3-mercaptobutyrate), about 40-50% CN9167, and about 50-60% hydroxypropyl acrylate, the resin configured to react upon exposure to light to form a cured product.

[0068] Another embodiment of the present invention includes a photopolymerizable resin for additive manufacturing, the resin comprising less than about 5% thiol; at least about 50% of one or more acrylic monomers; and less than about 45% of one or more acrylic-functionalized oligomers, the resin configured to react upon exposure to light to form a cured product, the resin having a viscosity of less than 1,000 cP at room temperature, and wherein the components of the resin can be combined and stored in a single pot at room temperature for at least six months without the viscosity of the resin increasing by more than 2%, 5%, 10%, 25%, 50%, or 100%.

[0069] Another embodiment of the invention includes a photopolymerizable resin for additive manufacturing, the resin comprising less than about 5% stabilized thiol, at least 50% of one or more acrylic monomers, and less than about 45% of one or more acrylic-functionalized oligomers, wherein the resin is configured to react to form a cured product upon exposure to light, and wherein the components of the resin can be combined and stored in a single pot at room temperature for at least six months without the viscosity of the resin increasing by more than 2%, 5%, 10%, 25%, 50%, or 100%.

[0070] Another embodiment of the present invention includes a photopolymerizable resin for three-dimensional printing, the resin comprising about 4-6 phr pentaerythritol tetrakis(3-mercaptobutyrate), about 0%-5% trimethylolpropane triacrylate, about 25%-35% CN9004, and about 65%-75% isobornyl acrylate, the resin configured to react to form a cured product upon exposure to light.

[0071] Another embodiment of the present invention includes a photopolymerizable resin for additive manufacturing, the resin comprising about 4-6 phr pentaerythritol tetrakis(3-mercaptobutyrate), about 20-40% CN9004, and about 60-80% hydroxypropyl acrylate, the resin configured to react to form a cured product upon exposure to light.

[0072] Another embodiment of the invention includes a photopolymerizable resin for additive manufacturing, comprising less than about 5% stabilized thiol; and at least about 50% one or more monomers; the resin configured to react to form a cured product upon exposure to light, wherein a layer of the resin about 100 μm thick is configured to form a cured product in 30 seconds or less, and the cured product has a curing energy of about 3-100 MJ / m 3 and a breaking strain in the range of about 30-1000%.

[0073] Another embodiment of the present invention includes a photopolymerizable resin for three-dimensional printing, the resin comprising about 5-10 phr of a thiol, about 0-5% trimethylolpropane triacrylate, about 30-50% at least one difunctional acrylic oligomer, about 5-75% isobornyl acrylate, and about 0-80% hydroxypropyl acrylate, the resin configured to react upon exposure to light to form a cured product.

[0074] Another aspect of the present invention provides a photopolymerizable resin for three-dimensional printing, the resin comprising: about 3-10 phr of a thiol; about 30-45% of one or more methacrylate monomers; and about 55-70% of one or more acrylate oligomers, the resin configured to react upon exposure to light to form a cured product.

[0075] In another aspect of the present invention, an article is provided having a layer comprising in majority any of the photopolymerizable resins described in this disclosure.

[0076] Detailed Description One embodiment of the present invention includes a photopolymerizable resin for additive manufacturing in an oxygen environment, the resin including a crosslinking component; at least one monomer and / or oligomer; and a chain transfer agent including at least one of a thiol, a secondary alcohol, and / or a tertiary amine, the resin optionally configured to react to form a cured product upon exposure to light.

[0077] The crosslinking component may include any compound that reacts to form chemical or physical links (e.g., ionic, covalent, or physical entanglements) between resin components to form an interlocked polymer network. The crosslinking component may include two or more reactive groups capable of linking with other resin components. For example, the two or more reactive groups on the crosslinking component may be capable of chemically bonding with other resin components. The crosslinking component may include terminal reactive groups and / or side-chain reactive groups. The number and location of the reactive groups may affect, for example, the crosslink density and structure of the polymer network.

[0078] The two or more reactive groups may include acrylic functional groups, such as methacylate, acrylate, or acrylamide functional groups. In some cases, the crosslinking component includes a difunctional acrylic oligomer. For example, the crosslinking component may include an aromatic urethane acrylate oligomer or an aliphatic urethane acrylate oligomer. Examples of crosslinking components include CN9167, CN9782, CN9004, poly(ethylene glycol) diacrylate, bisacrylamide, tricyclo[5.2.1.0]. 2,6 ] decanedimethanol diacrylate, and / or trimethylolpropane triacrylate. The size of the cross-linking component can affect, for example, the cross-link length of the polymer network.

[0079] The number and density of crosslinks can be selected to control the properties of the resulting polymer network. For example, polymer networks with fewer crosslinks may exhibit high extensibility, while those with more crosslinks may exhibit high stiffness. This is because the polymer chains between crosslinks can stretch during elongation. Chains with a low crosslink density may wind themselves together to pack more densely and satisfy entropic forces. Upon stretching, these chains may unwind and stretch before being pulled by the crosslinks, which may break before they can stretch. In highly crosslinked materials, the high number of crosslinked chains may result in few or immediate chain lengths that cannot be unwound.

[0080] The amount of crosslinking component can be selected to control the crosslink density and resulting properties of the polymer network. In some cases, the crosslinking component is 1-95% by weight of the resin. In other cases, the crosslinking component is 1% or more, 1.0-4.99%, 5-10%, or about 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% by weight of the resin.

[0081] In some cases, the resin comprises at least one monomer and / or oligomer. In some embodiments, the at least one monomer and / or oligomer comprises 1-95% by weight of the resin. In other aspects, the at least one monomer and / or oligomer comprises greater than 1%, 1.0-4.99%, 5-10%, or about 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% by weight of the resin. Monomers may include small molecules that combine with each other to form oligomers or polymers. Monomers may include difunctional monomers with two functional groups per molecule and / or multifunctional monomers with two or more functional groups per molecule. Oligomers may include molecules containing several monomer units. For example, in some cases, oligomers may be composed of two, three, or four monomers (i.e., dimers, trimers, or tetramers). The oligomer may include a difunctional oligomer, having two functional groups per molecule, and / or a multifunctional oligomer, having more than two functional groups per molecule.

[0082] At least one monomer and / or oligomer may be capable of reacting with other resin components to form a linked polymer network. For example, at least one monomer and / or oligomer may contain one or more functional groups capable of reacting with two or more reactive groups of the crosslinking component. At least one monomer and / or oligomer may contain an acrylic functional group, such as a methacylate, acrylate, or acrylamide functional group.

[0083] In some cases, the at least one monomer and / or oligomer comprises one or more monomers. For example, the one or more monomers may comprise about 1 to 95% by weight of the resin. Alternatively, the resin may comprise at least about 50% or at least about 60% of the one or more monomers. In other cases, the at least one monomer and / or oligomer comprises an acrylic monomer. The acrylic monomer may have a molecular weight of less than 200 Da, less than 500 Da, or less than 1,000 Da. The acrylic monomer may include at least one of 2-ethylhexyl acrylate, hydroxypropyl acrylate, cyclic trimethylolpropane formal acrylate, isobornyl acrylate, butyl acrylate, and / or N,N'-dimethylacrylamide.

[0084] Chain transfer agents may include compounds with at least one weak chemical bond that can react with a free radical site on a growing polymer chain and prevent chain growth. During free radical chain transfer, the radical may temporarily transfer to a chain transfer agent, which may then transfer the radical to another component of the resin, such as a growing polymer chain or monomer, to resume growth. Chain transfer agents can affect the rate and structure of polymer networks. For example, chain transfer agents can delay network formation. This delay in network formation may reduce stress in the polymer network, potentially resulting in better mechanical properties.

[0085] In some cases, the chain transfer agent may be configured to react with an oxygen radical to initiate growing at least one new polymer chain and / or to re-initiate growing polymer chains terminated by oxygen. For example, the chain transfer agent may include a weak chemical bond such that a radical is displaced from the oxygen radical and transferred to another polymer, oligomer, or monomer.

[0086] Additive manufacturing processes, such as 3D printing, may produce three-dimensional objects by sequentially curing layers of photopolymerizable resin. Thus, an article produced by additive manufacturing may contain a large number or multiple photocured layers. Additive manufacturing may be performed in an oxygen-containing environment, where oxygen can diffuse into the deposited layers of resin.

[0087] In some cases, diffused oxygen may react with growing polymer chains to form oxygen radicals. For example, oxygen may react with initiator radicals or polymer radicals at the surface of an oxygen-rich resin layer to form oxygen radicals. These oxygen radicals may be attached to polymer side chains. Oxygen radicals, such as peroxy radicals, can retard the curing of the resin. This retardation can result, for example, in the formation of a thin, sticky layer of uncured monomers and / or oligomers on the oxygen-rich surface of an earlier-cured resin layer, which can otherwise minimize adhesion to adjacent, later-cured resin layers.

[0088] At the interface between the previously cured and subsequently cured resin layers, at least some bonding may occur between the previously cured resin layer and the adjacent subsequently cured resin layer, despite the presence of an oxygen-rich surface on the previously cured resin layer, due at least in part to the presence of the chain transfer agent. In some cases, the bonding may be covalent. In some embodiments, the bonding may be ionic. In some embodiments, the bonding may be physical entanglement of polymer chains. Furthermore, in some cases, the chain transfer agent is 1 / 2-50% by weight of the resin. In some cases, the chain transfer agent is about 0.5-4.0%, 4.0-4.7%, 4.7-4.99%, 4.99-5%, or 5-50% by weight of the resin.

[0089] The thiol acrylate-based photopolymerizable resin material of the present invention can exhibit excellent interlayer strength when 3D printed in an air environment. Because 3D printing is constructed layer by layer, printing in air presents an opportunity for each resin layer to become oxygen-rich at the surface exposed to air (e.g., during patterning). With conventional resins, oxygen inhibits free radical polymerization at the oxygen-rich interface between layers, limiting chain growth and slowing the reaction, resulting in weak interlayer adhesion. However, thiol acrylate-based photopolymerizable resins, which contain chain transfer agents (e.g., secondary thiols), overcome this issue and can promote chemical and physical crosslinking between 3D printed layers, even in the presence of oxygen at the interface between layers.

[0090] Furthermore, thiol-acrylate photopolymerizable resin materials can exhibit low sensitivity to oxygen. In free-radical polymerization systems, oxygen reacts with primary initiating and propagating radicals to generate peroxy radicals. In conventional resins, these peroxy radicals tend to terminate the polymerization. However, in thiol-acrylate photopolymerizable resins, the thiol acts as a chain transfer agent, potentially further promoting the polymerization reaction. Furthermore, the low sensitivity to oxygen allows for outdoor production without the need for low-oxygen production techniques such as nitrogen or argon blankets.

[0091] Thiol acrylate photopolymerizable resins may undergo a chain transfer reaction during photocuring. Chain transfer is a reaction in which free radicals from a growing polymer chain are transferred to a chain transfer agent. The newly formed radicals then restart chain growth. This chain transfer reaction is believed to have effects such as reducing stress in materials formed from thiol acrylate photopolymerizable resins.

[0092] In some cases, the chain transfer agent may be configured to transfer radicals from a first polymer chain or chain branch in a previously cured resin layer to a second polymer chain or chain branch within the volume of the photopolymerizable resin. This may enable the formation of chemical or physical crosslinks between adjacent photocured layers, for example, in an article manufactured by additive manufacturing. In other cases, the chain transfer agent may be configured to promote the growth of at least one new polymer chain near an oxygen-rich surface present in a previously cured resin layer. This may also enable the formation of chemical or physical crosslinks between adjacent photocured layers, for example, in an article manufactured by additive manufacturing. Furthermore, the thiol acrylate-based photopolymerizable resin may include a monomer or oligomer having a side chain capable of cooperating with the chain transfer agent to affect the chain transfer mechanism.

[0093] The chain transfer agent may include at least one of a thiol, a secondary alcohol, and / or a tertiary amine. The secondary alcohol may include at least one of isopropyl alcohol and / or hydroxypropyl acrylate. In some cases, the thiol is present in an amount of about 0.5-4.0%, 4.0-4.7%, 4.7-4.99%, 4.99-5%, or 5-50% by weight of the resin. The thiol may include a secondary thiol. The secondary thiol may include at least one of pentaerythritol tetrakis(3-mercaptobutyrate); 1,4-bis(3-mercaptobutyryloxy)butane; and / or 1,3,5-tris(3-mercaptobutyryloxy)-1,3,5-triazine. The tertiary amine may include at least one of an aliphatic amine, an aromatic amine, and / or a reactive amine. The tertiary amine may include at least one of triethylamine, N,N'-dimethylaniline, and / or N,N'-dimethylacrylamide.

[0094] Any suitable additive compound can be optionally added to the resin. For example, the resin may further include poly(ethylene glycol). The resin may further include polybutadiene. The resin may further include polydimethylsiloxane acrylate. The resin may further include copolymer poly(styrene-co-maleic anhydride).

[0095] The resin may further include a photoinitiator, an inhibitor, a dye, and / or a filler. The photoinitiator may be any compound that absorbs light and undergoes a photoreaction to generate reactive free radicals. Thus, the photoinitiator can initiate or catalyze a chemical reaction, such as free radical polymerization. The photoinitiator may include at least one of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bisacylphosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and / or 2,2'-dimethoxy-2-phenylacetophenone. In some cases, the photoinitiator is present in an amount of 0.01 to 3% by weight of the resin.

[0096] The inhibitor may be any compound that reacts with free radicals to give products that may not be capable of inducing further polymerization, and may include at least one of hydroquinone, 2-methoxyhydroquinone, butylated hydroxytoluene, diallyl thiourea, and / or diallyl bisphenol A.

[0097] The dye may be any compound that alters the color or appearance of the resulting polymer. The dye may also serve to attenuate stray light within the printed area, reducing unwanted radical generation and sample overcure. The dye may include at least one of 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene, carbon black, and / or Disperse Red 1.

[0098] Fillers are any compounds added to polymer formulations that can occupy or replace space in other resin components. Fillers may include at least one of titanium dioxide, silica, calcium carbonate, clay, aluminosilicates, crystalline molecules, crystalline oligomers, semi-crystalline oligomers, and / or polymers, wherein the molecular weight of the polymer is between about 1,000 Da and about 20,000 Da.

[0099] Resin viscosity can be any value that facilitates additive manufacturing (e.g., 3D printing) of molded parts. High-viscosity resins flow well, while low-viscosity resins flow poorly. Resin viscosity can affect printability, print speed, or print quality, for example. For example, 3D printers may only be compatible with resins of a certain viscosity. Also, higher resin viscosity may mean that the resin does not sink as quickly, increasing the time required to smooth the surface of the deposited resin between printed layers.

[0100] Additionally, the thiol acrylate photopolymerizable resin of the disclosed materials may have a high cure rate and low viscosity. Additive manufacturing is achieved by building up materials layer by layer. Each layer is constructed by depositing liquid resin and curing it with light. Therefore, the viscosity and cure rate of the resin affect printing speed. A low-viscosity resin spreads into a flat layer quickly (e.g., 1-30 seconds) without the need for heat or mechanical manipulation. With mechanical manipulation, spreading is more rapid (e.g., 1-10 seconds). Furthermore, a low viscosity may allow for faster recoat blade movement. A faster cure rate allows subsequent layers to be built more quickly.

[0101] The viscosity of the resin can be adjusted, for example, by adjusting the ratio of monomer to oligomer. For example, resins with a high monomer content may exhibit a low viscosity. This is believed to be because the low molecular weight monomer acts as a solvent for the oligomer, reducing oligomer-oligomer interactions and lowering the overall viscosity of the resin. The resin may have a viscosity of less than about 250 centipoise, less than about 500 centipoise, less than about 750 centipoise, or less than about 1,000 centipoise at room temperature or above. In some cases, the resin has a viscosity of less than about 1,000 centipoise, less than about 500 centipoise, or less than about 100 centipoise at temperatures between 0°C and 80°C.

[0102] Articles may be made from the resins described in any of the embodiments. Articles may be made by additive manufacturing processes such as cast polymerization or 3D printing. Articles may include footwear midsoles, shape memory foams, implantable medical devices, wearable articles, car seats, seals, gaskets, dampers, hoses, and / or fittings. Molded articles may have multiple layers comprising the resins described in any of the embodiments.

[0103] In some embodiments, an article made from a resin described in any embodiment may further include a surface coating. The surface coating may be applied to the article to potentially obtain a desired appearance or physical property of the article. The surface coating may include a thiol. The surface coating may include a secondary thiol. The surface coating may include an alkane. The surface coating may include a siloxane polymer. The surface coating may be comprised of at least one of a semifluorinated polyether and / or a perfluorinated polyether.

[0104] In some embodiments, the photoinitiator may be configured to generate free radicals after exposure to light. In some embodiments, the crosslinking component and at least one monomer and / or oligomer are configured to react with the free radicals to provide growth of at least one polymer chain radical within the volume of the photopolymerizable resin. In some embodiments, the at least one polymer chain radical reacts with diffused oxygen to provide an oxygen radical. In some embodiments, the chain transfer agent may be configured to transfer the oxygen radical to initiate growth of at least one new polymer chain radical.

[0105] In some embodiments, the cross-linking component and the at least one monomer and / or oligomer are configured to react to provide one or more polymer chains after exposure to light, and in some embodiments, the chain transfer agent can be configured to transfer a free radical associated with one of the polymer chains to another of the polymer chains.

[0106] In some embodiments, the photoinitiator may be configured to generate free radicals upon exposure to light, where the free radicals may initiate a chain reaction between the cross-linking component and the at least one monomer and / or oligomer to provide one or more polymer chains within the volume of the photopolymerizable resin. In some embodiments, the chain transfer agent may be configured to re-initiate the chain reaction to provide one or more new polymer chains within the volume of the photopolymerizable resin.

[0107] The cure rate of a resin layer may depend on the tendency of the resin components to polymerize via free radical reactions when cured with a light source (e.g., ultraviolet light). The resin may optionally contain a photoinitiator or inhibitor, which can be used to accelerate or slow the curing process. When provided in a thickness suitable for 3D printing or other additive manufacturing, a resin layer of the present disclosure may be photocured in the length of time desired for efficient manufacture of an article. For example, in some cases, a resin layer approximately 100 μm thick may be configured to form a cured material in 30 seconds or less, 20 seconds or less, 10 seconds or less, 3 seconds or less, 1 second or less, or 1 / 10th of a second or less. In other cases, a resin layer approximately 400 μm thick may be configured to form a cured material in 1 second or less. In other cases, a resin layer approximately 300 μm thick may be configured to form a cured material in 1 second or less. In other cases, a resin layer approximately 200 μm thick may be configured to form a cured material in 1 second or less. In other cases, a layer of resin about 1000 μm thick may be configured to form a cured material in 30 seconds or less, and in other cases, a layer of resin about 10 μm thick may be configured to form a cured material in 2 seconds or less, 1 second or less, ½ second or less, or ¼ second or less.

[0108] Another embodiment of the invention includes a photopolymerizable resin for additive manufacturing, the resin including at least one monomer and / or oligomer and less than about 5% thiol, the resin may be configured to react upon exposure to light to form a cured product, and in some cases, the resin may be configured to form a cured product in an aerobic environment.

[0109] Thiols have a foul odor, but thiol acrylate resins can be nearly odorless. This low odor is believed to be at least in part due to the use of substoichiometric amounts of high molecular weight thiols to reduce or eliminate the thiol odor. Furthermore, the thiols can be almost completely incorporated into the polymer network.

[0110] Thiol volatiles may be generated in the cured material or during manufacturing processes that use thiols. Thiol volatiles may be adjusted to be below the threshold detectable by human olfaction. This may be achieved, for example, by having the resin contain less than about 5% thiols. Thiol volatiles may be measured in samples using a gas chromatograph mass spectrometer (GC-MS). In some cases, the cured product contains less than 1 part per billion of thiol volatiles at ambient temperature and pressure for 50 seconds in an oxygen environment. In some cases, the cured product contains less than 1 part per billion of thiol volatiles at ambient temperature and pressure for 50 seconds in an oxygen environment. In some embodiments, the cured product contains less than 1 part per billion of thiol volatiles at ambient temperature and pressure for 50 seconds in an oxygen environment. In some embodiments, the cured product contains less than 1 part per billion of thiol volatiles at ambient temperature and pressure for 50 seconds in an oxygen environment.

[0111] The at least one monomer and / or oligomer and thiol used in additive manufacturing can be any monomer and / or oligomer or thiol compound as described for the resins of the present disclosure, for example, the at least one monomer and / or oligomer includes an alkene, an alkyne, an acrylate or acrylamide, a methacrylate, an epoxide, a maleimide, and / or an isocyanate.

[0112] In some cases, the thiol has a molecular weight of about 200 or greater, or about 500 or greater. In some embodiments, the thiol has a molecular weight greater than about 100 and includes a moiety that includes a hydrogen bond acceptor and / or a hydrogen bond donor, wherein the moiety undergoes hydrogen bonding.

[0113] In some cases, the resin comprises a thiol and at least one monomer and / or oligomer in approximately stoichiometric ratios, hi other embodiments, the thiol is less than about 20% by weight of the resin, less than about 10% by weight of the resin, or less than about 5% by weight of the resin.

[0114] In other aspects, the thiol comprises an ester-free thiol. In some embodiments, the thiol comprises a hydrolytically stable thiol. In some embodiments, the thiol comprises a tertiary thiol.

[0115] The cure rate may be such that a layer of photopolymerizable resin approximately 100 μm thick cures in 30 seconds or less. The material may have a strain at break of greater than 100% up to 1000%. The material may have a strain at break of approximately 30 MJ / m 3 to approximately 100MJ / m 3 It has a toughness between .

[0116] In some embodiments, the resin comprises at least about 50% of one or more acrylic monomers and about 0-45% of one or more acrylic-functionalized oligomers. The thiol-acrylate resin can be stored as a single-pot system at room temperature. In some cases, the resin components can be combined and stored in a single pot (e.g., a container suitable for storing chemicals) at room temperature for at least six months without the resin viscosity increasing by more than 10-20%. (See, e.g., Example 9.) In some cases, the resin mixture components can be combined and stored in a single pot at room temperature for at least six months without the resin viscosity increasing by more than 2%, 5%, 10%, 25%, 50%, or 100%.

[0117] The stabilized thiol may be any thiol that exhibits reduced ambient thermal reactivity (e.g., nucleophilic substitution with monomers or oligomers) compared to other thiols. In some cases, the stabilized thiol comprises a bulky side chain. Such bulky side chain may comprise at least one chemical group, such as a C1-C18 cyclic, branched, or linear alkyl, aryl, or heteroaryl group. In some cases, the stabilized thiol comprises a secondary thiol. In other aspects, the stabilized thiol comprises a multifunctional thiol. In some aspects, the stabilized thiol comprises at least one of a difunctional, trifunctional, and / or tetrafunctional thiol. In some embodiments, the stabilized thiol comprises at least one of pentaerythritol tetrakis(3-mercaptobutyrate); and / or 1,4-bis(3-mercaptobutyryloxy)butane.

[0118] Thiol-acrylate photopolymerizable resins may exhibit improved shelf life. Resin compositions containing thiols and non-thiol reactive species, such as enes or acrylates, may undergo dark reactions (i.e., room temperature free radical polymerization or Michael addition), reducing the shelf life of these compositions. Given the poor shelf life of these resins, they are either stored at low temperatures or as two-pot systems. In contrast, thiol-acrylate resins, such as the disclosed materials, may contain stabilized thiols (e.g., secondary thiols). Stabilized thiols may have reduced reactivity, potentially improving the shelf life of 3D printable resin compositions and allowing them to be stored as single-pot resin systems at room temperature. Furthermore, any resin remaining upon completion of 3D printing can be reused for subsequent printing.

[0119] In some embodiments, the resin viscosity does not increase by more than 10% when the resin mixture components are combined and stored in a single pot at room temperature for at least six months. The increased shelf life, pot life, and / or print life is believed to be at least partially attributable to the presence of stabilized thiols in the resin mixture. Resin compositions containing thiols and non-thiol reactive species, such as acrylates, can undergo dark reactions (i.e., ambient thermal free radical polymerization or nucleophilic Michael addition). However, stabilized thiols may exhibit reduced reactivity in dark reactions.

[0120] In some cases, the resin may be configured for two weeks of continuous use in 3D printing operations in an air environment without increasing in viscosity by more than 2%, 5%, 10%, 25%, 50%, or 100%. In some cases, the resin may be configured for four weeks of continuous use in 3D printing operations in an air environment without increasing in viscosity by more than 2%, 5%, 10%, 25%, 50%, or 100%. In some cases, the resin may be configured for ten weeks of continuous use in 3D printing operations in an air environment without increasing in viscosity by more than 2%, 5%, 10%, 25%, 50%, or 100%. In some cases, the resin may be configured for twenty-six weeks of continuous use in 3D printing operations in an air environment without increasing in viscosity by more than 2%, 5%, 10%, 25%, 50%, or 100%. In some cases, the resin may be configured for continuous use in 3D printing operations in an air environment for one year without increasing in viscosity by more than 2%, 5%, 10%, 25%, 50%, or 100%.

[0121] In other cases, at least one monomer and / or oligomer comprises one or more acrylic monomers. In some embodiments, the one or more acrylic monomers comprise at least about 50% by weight of the resin. In other aspects, the resin comprises less than about 5% stabilizing thiols comprising one or more thiol functional groups, and the stabilizing thiols may be configured to inhibit nucleophilic substitution reactions between the one or more thiol functional groups and one or more monomers or oligomers.

[0122] Other embodiments of the invention may include a photopolymerizable resin for additive manufacturing, the resin comprising less than about 5% thiol and at least about 50% one or more monomers, the resin may be configured to react upon exposure to light to form a cured product, the cured product having a curing rate of about 3-100 MJ / m 3 and a breaking strain in the range of about 30 to 1000%.

[0123] Cured thiol acrylate resins may also exhibit time-temperature superposition, so their properties change with temperature and frequency. At temperatures below the glass transition point, they become brittle glassy materials. However, at temperatures above the glass transition point, they become viscoelastic and tough materials up to the glass transition point. Thiol acrylate resins may have a glass transition temperature close to the operating temperature. For example, this resin may have a T around 20°C. g may have an onset of

[0124] T g At temperatures above the onset of 3000 MJ / m, thiol acrylate resins can be tough materials with high strain. Specifically, the cured thiol acrylate resins can be hardened at temperatures between 3 and 100 MJ / m. 3 and strain at break of 30 to 800%.

[0125] The cured products of the present disclosure provide mechanical properties of toughness and flexibility (e.g., as measured by percent strain at break) and may be suitable for use in manufactured articles where these properties are desired (e.g., shoe midsoles, insoles, outsoles). In this manner, articles comprising these cured materials may be produced in additive manufacturing processes at reduced cost, with greater potential efficiency and customization of the article's design and mechanical properties. For example, the cured resin materials disclosed in Examples 1-8 may demonstrate customizable toughness and flexibility.

[0126] The material properties of thiol acrylate resins allow for a variety of applications for 3D printed products. Specific applications include household items such as mattresses and game pieces, as well as body-worn, body-worn, and ear-worn items. The resins are also suitable for shape and fit prototyping. For example, the resins may be used to produce low-cost shoe soles (midsoles, insoles, and outsoles) for pilot manufacturing. In another embodiment, the resins can achieve a thermal energy output of 3-100 MJ / m over a wide temperature range (e.g., 0°C to 80°C). 3 It has a toughness of 100% and a breaking strain of 200-1000%. 3D printed products made from this resin can be used in a variety of applications, including seals, gaskets, hoses, dampers, midsoles, automotive and aerospace components, and more. It is also suitable for prototyping form, fit, and function. For example, it can be used in the full-scale production of low-density shoe soles (midsoles, insoles, and outsoles).

[0127] Specifically, toughness can be customized by controlling the ratio and type of monomer, and possibly combining them with oligomers, fillers, and additives. By controlling these parameters, it is possible to specifically engineer the material's ability to stretch (strain) and the force (stress) at which this stretching occurs. In some cases, the cured material can reach approximately 3 MJ / m3 (See, e.g., Examples 7 and 8). In some cases, the cured material has a toughness of about 5 MJ / m 3 (See, e.g., Examples 5 and 6.) In some cases, the cured material has a toughness of about 10 MJ / m 3 (See, e.g., Examples 1 and 5). In some cases, the cured material has a toughness of about 15-25 MJ / m 3 (See, e.g., Example 6). In some cases, the cured material has a toughness of about 30-100 MJ / m 3 (See, for example, Examples 6 and 8).

[0128] Additionally, by controlling the proportion and type of monomer, optionally combined with oligomers, fillers, and additives, the strain at break can be customized. By controlling the underlying network morphology, the density of crosslinks, and the material's tear strength (enabled by the filler and its interaction with the matrix), the elongation (strain) of the material can be controlled. In some cases, the cured material has a strain at break of approximately 100%. In other cases, the cured material may have a strain at break of approximately 200%. In other cases, the cured material may have a strain at break of approximately 300%. In other cases, the cured product has a strain at break of approximately 400%. In other cases, the cured product has a strain at break of approximately 500%. In other cases, the cured product has a strain at break of approximately 600%. In other cases, the cured product has a strain at break of approximately 700%. In other cases, the cured product has a strain at break of approximately 800%.

[0129] Specifically, the cured product has a viscosity of approximately 3 to 30 MJ / m 3 and strain at break in the range of about 30-300%. In other cases, the cured products have a yield strength of about 8-15 MJ / m 3 In some cases, the cured product has a toughness in the range of about 1 MJ / m 3In some cases, the cured material has a breaking strain in the range of about 50-250%. In some cases, the cured material has a glass transition temperature in the range of about 10-30°C. In other cases, the resin has a yield strength of about 3-100 MJ / m 3 and strain at break in the range of about 200-1000%. In some cases, the cured products have a yield of about 3-8 MJ / m 3 In some cases, the cured product has a strain at break in the range of about 350-500%. In some cases, the cured product has a strain at break in the range of about 3-30 MJ / m at about 20°C. 3 In another embodiment, the cured product has a toughness in the range of about 10 MJ / m at about 20°C. 3 In some embodiments, the cured product has a strain at break in the range of about 30-100% at about 20°C. In some embodiments, the cured product has a glass transition temperature in the range of about 10-30°C. In some cases, the cured product has a Shore A hardness of about 95 at about 20°C. In some cases, the cured product has a Shore A hardness of about 1-5 MJ / m at about 20°C. 3 In a specific example, the cured product has a toughness in the range of about 3 MJ / m at about 20°C. 3 It has a toughness of .

[0130] In a specific example, the cured product has a viscosity of about 20 to 40 MJ / m at about 20°C. 3 In other cases, the hardened material has a toughness in the range of about 40 MJ / m 3 at about 0° C. In another embodiment, the cured product has a toughness of about 30 MJ / m at about 20° C. 3 In another embodiment, the cured material has a toughness of about 20 MJ / m at about 40° C. 3 In another embodiment, the cured material has a toughness of about 1 MJ / m at about 80°C. 3 It has a toughness of .

[0131] In some embodiments, the cured product has a break strain in the range of about 250-300% at about 0°C. In some embodiments, the cured product has a break strain in the range of about 400-500% at about 20°C. In some embodiments, the cured product has a break strain in the range of about 400-500% at about 40°C. In some embodiments, the cured product has a break strain in the range of about 275-375% at about 80°C. In some embodiments, the cured material has a glass transition temperature in the range of about 35-55°C.

[0132] The cure rate of the resin layer may depend on the tendency of the resin components to polymerize via free radical reactions when cured with a light source (e.g., ultraviolet light). The resin may optionally contain a photoinitiator or inhibitor, which can be used to accelerate or slow the curing process. When provided in a thickness suitable for 3D printing or other additive manufacturing, a layer of resin of the present disclosure may be photocured in the amount of time desired for efficient manufacture of an article. The cure rate may be configured such that a layer of photopolymerizable resin approximately 100 μm thick cures in 30 seconds or less. For example, in some cases, a layer of resin approximately 100 μm thick may be configured to form a cured material in 30 seconds or less, 20 seconds or less, 10 seconds or less, 3 seconds or less, 1 second or less, or 1 / 10th of a second or less. In other cases, a layer of resin approximately 400 μm thick may be configured to form a cured material in 1 second or less. In other cases, a layer of resin approximately 300 μm thick may be configured to form a cured material in 1 second or less. In other cases, a layer of resin about 200 μm thick may be configured to form a cured material in 1 second or less, in other cases, a layer of resin about 1000 μm thick may be configured to form a cured material in 30 seconds or less, and in other cases, a layer of resin about 10 μm thick may be configured to form a cured material in 2 seconds or less, 1 second or less, ½ second or less, or ¼ second or less.

[0133] The cured product may also have a desired hardness suitable for the manufactured article. In some cases, the cured product has a Shore A hardness of about 30 at about 20° C. In some cases, the cured product has a Shore A hardness of about 90 at about 20° C.

[0134] Glass transition temperature (T g ) is the temperature at which a polymer transitions from an amorphous, hard state to a more flexible state. The glass transition temperature of a cured product can be customized by controlling the proportion and type of monomer, the proportion and type of oligomer, fillers, plasticizers, and curing additives (e.g., dyes, initiators, inhibitors). In some embodiments, the cured product has a glass transition temperature in the range of about 10°C to about -30°C. In some embodiments, the cured product has a glass transition temperature with a full width half-life of 20°C or greater, 30°C or greater, 40°C or greater, or 50°C or greater. In certain cases, the cured product has a glass transition temperature with a full width half-life of 50°C or greater.

[0135] Furthermore, the cured product is in a glassy state below the glass transition temperature, and the cured product is in a tough state above the glass transition temperature. In some cases, the tough state occurs in the range of about 5-50°C. In some cases, the tough state occurs in the range of about 20-40°C. In some cases, the resin has a glass transition temperature in the range of about 20-25°C.

[0136] The material may have a strain at break of greater than 100% up to 1000%. The material has a strain at break of about 30 MJ / m 3 to approximately 100MJ / m 3 In particular cases, the cured material has a breaking strain in the range of about 400-500% at about 20°C. In some cases, the cured product has a glass transition temperature in the range of about 10-30°C. In some cases, the cured product has a Shore A hardness of about 30 at about 20°C. In some cases, the cured product has a Shore A hardness of about 19 at about 20°C. In some embodiments, the cured product in a tough state has a hardness of about 3-30 MJ / m 3In some embodiments, the tough cured product has a toughness in the range of about 30 to 100 MJ / m 3 In some embodiments, the cured product in the glassy state has an elastic modulus of less than 5 GPa, 2 GPa or more, or 1 GPa or more. In some cases, the cured product in the glassy state has an elastic modulus of 2 to 5 GPa.

[0137] Further embodiments of the present invention may include a photopolymerizable resin for additive manufacturing, the resin comprising: less than about 5% thiol; at least about 50% one or more monomers; and a photoinitiator, wherein the photoinitiator may be configured to form free radicals upon exposure to light, wherein the free radicals may be configured to initiate growth of one or more polymer chains comprising at least difunctional and monofunctional monomers, the resin may be configured to react upon exposure to light to form a cured product, wherein the cured product has a glass transition temperature in the range of about 5-30°C.

[0138] In certain cases, the resin further comprises a difunctional oligomer. In some embodiments, the difunctional oligomer is less than about 45% by weight of the resin. In some embodiments, the thiol is about 1 / 2 to 5% by weight of the resin. In some cases, the one or more monomers are about 1 to 95% by weight of the resin. In some cases, the photoinitiator is 0.01 to 3% by weight of the resin.

[0139] The resin may further include a trifunctional monomer. In some cases, the trifunctional monomer includes trimethylolpropane triacrylate.

[0140] In another embodiment of the present invention, a photopolymerizable resin for additive manufacturing is provided, the resin comprising about 5-15 parts per hundred parts rubber ("phr") thiol, about 20-60% difunctional acrylic oligomer, and about 40-80% one or more monofunctional acrylic monomers, optionally configured to react upon exposure to light to form a cured product.

[0141] A further embodiment of the present invention provides a photopolymerizable resin for additive manufacturing, the resin comprising about 4-6 phr pentaerythritol tetrakis(3-mercaptobutyrate), about 40-50% CN9167, and about 50-60% hydroxypropyl acrylate, and the resin may be configured to react to form a cured product upon exposure to light.

[0142] Another embodiment of the present invention provides a photopolymerizable resin for three-dimensional printing, the resin comprising at least one of: about 5-20 phr of a thiol; about 0-5 phr of a polydimethylsiloxane acrylate copolymer; about 20-100% of a difunctional acrylic oligomer; and about 0-80% of a monofunctional acrylic monomer, and the resin may be configured to react upon exposure to light to form a cured product.

[0143] Another embodiment of the present invention provides a photopolymerizable resin for three-dimensional printing, the resin comprising about 4-6 phr pentaerythritol tetrakis(3-mercaptobutyrate), about 20-40% CN9004, and about 60-80% hydroxypropyl acrylate, and the resin may be configured to react and form a cured product upon exposure to light.

[0144] In another aspect of the present invention, a photopolymerizable resin for three-dimensional printing is provided, the resin comprising about 5-10 phr of a thiol, about 0-20% trimethylolpropane triacrylate, about 30-50% at least one difunctional acrylic oligomer, about 50-86% isobornyl acrylate, and about 0-21% hydroxypropyl acrylate, and the resin may be configured to react upon exposure to light to form a cured product.

[0145] In another aspect of the present invention, a photopolymerizable resin for three-dimensional printing is provided, the resin comprising about 4-6 phr pentaerythritol tetrakis(3-mercaptobutyrate), about 0%-5% trimethylolpropane triacrylate, about 25%-35% CN9004, and about 65%-75% isobornyl acrylate, and the resin may be configured to react and form a cured product upon exposure to light.

[0146] Another embodiment of the present invention provides a photopolymerizable resin for three-dimensional printing, the resin comprising about 5-10 phr of a thiol, about 0-5% trimethylolpropane triacrylate, about 30-50% at least one difunctional acrylic oligomer, about 5-75% isobornyl acrylate, and about 0-80% hydroxypropyl acrylate, and the resin may be configured to react to form a cured product upon exposure to light.

[0147] Another embodiment of the present invention provides a photopolymerizable resin for three-dimensional printing, the resin comprising approximately 3-10 phr of a thiol; approximately 30-45% of one or more methacrylate monomers; and approximately 55-70% of one or more acrylate oligomers, configured to react to form a cured product upon exposure to light. The acrylic oligomer may comprise CN9004, and the methacrylate monomer may comprise 2-hydroxyethyl methacrylate. The described composition comprising a thiol, one or more methacrylate monomers, and one or more acrylate oligomers may be used to prepare highly elastic elastomeric materials.

[0148] Another embodiment of the present invention provides a photopolymerizable resin for three-dimensional printing, comprising approximately 3-10 phr of a thiol; approximately 30-45% of one or more methacrylate monomers; approximately 55-70% of one or more acrylate oligomers; and approximately 0-50 phr of one or more oligomeric additives, configured to react and form a cured product upon exposure to light. The acrylic oligomer may include CN9004, and the methacrylate monomer may include 2-hydroxyethyl methacrylate. The addition of one or more oligomeric additives can reduce viscosity and adjust Shore A hardness without sacrificing tear strength.

[0149] Another embodiment of the present invention provides a photopolymerizable resin for three-dimensional printing, the resin comprising about 3-10 phr of a thiol; about 30-45% 2-hydroxyethyl methacrylate; about 55-70% CN9004; and about 0.30 phr of polytetrahydrofuran, the resin configured to react upon exposure to light to form a cured product.

[0150] In some cases, the thiol concentration is between about 3 and 5 phr. The thiol may include a secondary thiol. The secondary thiol may include at least one of pentaerythritol tetrakis(3-mercaptobutyrate); 1,4-bis(3-mercaptobutyryloxy)butane; and / or 1,3,5-tris(3-mercaptobutyryloxy)-1,3,5-triazine. The tertiary amine may include at least one of aliphatic amines, aromatic amines, and / or reactive amines. The tertiary amine may include at least one of triethylamine, N,N'-dimethylaniline, and / or N,N'-dimethylacrylamide. Removal of thiols from the system may result in plastic or viscoelastic materials. Altering the type and amount of thiol may affect properties (e.g., Shore A and elongation), but the material may maintain elasticity and toughness.

[0151] In some cases, the resin contains about 10, 15, 20, 25, or 30 phr of one or more oligomeric additives. The one or more oligomeric additives may include a polyether oligomeric additive. For example, the one or more oligomeric additives may include polytetrahydrofuran. Other oligomeric additives include triethylene glycol monomethyl ether, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), and / or white mineral oil.

[0152] The resin may further include a photoinitiator, an inhibitor, a dye, and / or a filler. The photoinitiator may be any compound that absorbs light and undergoes a photoreaction to generate reactive free radicals. Thus, the photoinitiator can initiate or catalyze a chemical reaction, such as free radical polymerization. The photoinitiator may include at least one of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bisacylphosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and / or 2,2'-dimethoxy-2-phenylacetophenone. In some cases, the photoinitiator is present in an amount of 0.01 to 3% by weight of the resin.

[0153] The inhibitor may be any compound that reacts with free radicals to give products that may not be capable of inducing further polymerization, and may include at least one of hydroquinone, 2-methoxyhydroquinone, butylated hydroxytoluene, diallyl thiourea, and / or diallyl bisphenol A.

[0154] The dye may be any compound that alters the color or appearance of the resulting polymer. The dye may also serve to attenuate stray light within the printed area, reducing unwanted radical generation and sample overcure. The dye may include at least one of 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene, carbon black, and / or Disperse Red 1.

[0155] Fillers are any compounds added to polymer formulations that can occupy or replace space in other resin components. Fillers may include at least one of titanium dioxide, silica, calcium carbonate, clay, aluminosilicates, crystalline molecules, crystalline oligomers, semi-crystalline oligomers, and / or polymers, wherein the molecular weight of the polymer is between about 1,000 Da and about 20,000 Da.

[0156] The viscosity of the resin may be any value that is amenable to use in additive manufacturing (e.g., 3D printing) of articles. For example, the resin may have a viscosity of less than about 2000, 1500, 1000, or 10,000 centipoise at or above room temperature.

[0157] Articles may be made from the resins described in any of the embodiments. The articles may be made by additive manufacturing processes such as cast polymerization or 3D printing. The articles may include footwear midsoles, memory foams, implantable medical devices, wearable articles, car seats, seals, gaskets, dampers, hoses, fittings, and / or firearm parts. Firearms may include, for example, rifles, pistols, or handguns. Firearm parts may include recoil pads. Articles may also be manufactured having a majority of layers comprising the resins described in any of the embodiments.

[0158] The cured product may have a Shore A hardness of about 60-100 at about 20°C. In some cases, the cured material has a Shore A hardness of about 80, 85, 90, or 95 at about 20°C. In some cases, the cured product has a tear strength in the range of about 20-40 kN / m. In specific cases, the cured product has a tear strength of about 25, 30, or 35 kN / m. In some cases, the cured product has a strain at break in the range of about 100%-300%. In specific cases, the cured product has a tear strength of about 200%.

[0159] Resin additive manufacturing The photopolymerizable resin for layered manufacturing of the present invention can be prepared by the following procedure.

[0160] Resin can be printed in open or ambient conditions using a top-down DLP printer (e.g., Octave Light R1). The print tub is filled with Z-liquid (typically 70-95% of the total volume), and the printing resin is added on top (approximately 5-30%). Printing parameters, including exposure time (typically 0.1-20 seconds), layer height (typically 10-300 μm), and recoat time between each layer (0.25-10 seconds), are entered into the control software. A computer-aided design ("CAD") file is loaded into the software, oriented and supported as needed, and printing begins. The print cycle involves the build table lowering to apply resin to the surface, then rising to a layer height (also known as the Z-axis resolution) below the resin surface. The recoater blade smooths the resin surface, and the optical engine illuminates the mask (a cross-sectional image of the printed area at the current height) to gel the liquid resin. This process is repeated layer by layer until printing is complete. In some embodiments, the 3D printed resin part is post-treated by curing under 350-400 nm UV irradiation for 0-5 hours at temperatures between 0-100 °C.

[0161] Experimental method The photopolymerizable resin for layered manufacturing of the present invention can be characterized using the following method.

[0162] Tensile test

[0163] Uniaxial tensile tests were performed using a Lloyd Instruments LR5K Plus universal testing machine equipped with a LaserScan 200 laser extensometer. Cured specimens were prepared according to ASTM D638 Type V specifications and placed in the grips of the testing machine. The distance between the two ends of the grip faces was recorded. After setting the appropriate test speed, the testing machine was started. The load-elongation curve of the specimen was recorded. The load and elongation at the moment of break were recorded. Testing and measurements were performed in accordance with the guidelines of ASTM D638.

[0164] toughness

[0165] Toughness was measured using the ASTM D638 standard tensile test as described above. The dimensions of the Type V dogbone specimens are as follows: [Width of narrow part (W) = 3.18 ± 0.03 mm, Length of narrow part (L) = 9.53 ± 0.08 mm, Gauge length (G) = 7.62 ± 0.02 mm, Fillet radius (R) = 12.7 ± 0.08 mm. The tensile tests were carried out at a test speed of 100 mm / min. In each test, the energy required for fracture was calculated from the area under the load mark up to the point where fracture occurred (sudden drop in load). This energy was calculated to obtain the toughness value (MJ / m 3 ) was sought.

[0166] Strain at break

[0167] Strain at break was measured using the ASTM D638 standard tensile test as described above. The dimensions of the Type V dogbone specimens were as follows: [Width of narrow part (W) = 3.18 ± 0.03 mm, Length of narrow part (L) = 9.53 ± 0.08 mm, Gauge length (G) = 7.62 ± 0.02 mm, Fillet radius (R) = 12.7 ± 0.08 mm.

[0168] Tensile tests were performed at a test speed of 100 mm / min. For each test, the elongation at break was divided by the original grip separation (i.e., the distance between the edges of the grip faces) and multiplied by 100.

[0169] Differential scanning calorimetry

[0170] Differential scanning calorimetry (DSC) was performed using a Mettler-Toledo DSC-1. 3–10 mg test pieces of the cured material were placed in a sample holder. The test was performed in a nitrogen purge gas atmosphere at 40 mL / min, with three heating-cooling cycles at a temperature change rate of 10°C / min. The glass transition temperature (Tg) was determined by fitting a straight line between the midpoints of the onset and offset of the glass transition slope. DSC testing was performed in accordance with ASTM E1356 guidelines.

[0171] Dynamic mechanical analysis (DMA)

[0172] Dynamic mechanical analysis (DMA) measurements were performed using a Mettler-Toledo DMA-861. Cured specimens were used, measuring 12 mm in length, 3 mm in width, and 0.025–1.0 mm in thickness. A tensile force of 10 N at 1 Hz with a maximum amplitude of 15 μm was applied to the specimens. The glass transition temperature (Tg) was measured as the peak value of Tan Delta (the ratio of loss modulus to storage modulus). DMA testing was performed according to ASTM D4065 guidelines.

[0173] Curing rate

[0174] Place a resin sample (approximately 1 g to 10 g) in a container. Place this container under an optical engine tuned to the initiator contained in the resin (a 385 nm light source for resins containing initiators such as TPO (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide)) so that the resin is centered in the projection area. Project a sample image (e.g., a 1 cm x 1 cm square) onto the resin for a predetermined time (usually 0.1 to 20 seconds). Determine the initial exposure time. Observe the surface of the resin sample to see if a gel has formed. Remove it from the resin vat with forceps. If a manipulable gel that can be arranged into a sheet of a consistent shape (e.g., a square) has not formed, create a new sample with a longer exposure time and repeat the test until a gel is successfully formed with a single exposure to approximately the gel point. The recorded DOC (depth of cure) is the exposure time required for gelation.

[0175] hardness

[0176] Hardness was measured using a Shore A durometer (1-100 HA ± 0.5 HA) according to the guidelines of ASTM D2240.

[0177] viscosity

[0178] Viscosity (mPa·s) was obtained using a Brookfield LV-1 viscometer. Viscosity measurements were performed according to the guidelines of ASTM D2196.

[0179] example The invention will now be further described with reference to the accompanying examples.

[0180] Preparation of resin A photopolymerizable resin for additive manufacturing was prepared by the following procedure.

[0181] Monomers (e.g., mono- and polyfunctional acrylates), solids (e.g., initiators, inhibitors, dyes), and thiols were added to an amber bottle (1000 mL, HDPE) and mixed in an ultrasonic bath (Bransonic CPX2800H, Branson Ultrasonic Corporation, CT) at 25°C for 30 minutes to form a clear solution. The oligomer was heated to 80°C in an oven (OV-12, Jeio Tech, Korea) and then added to the amber bottle. The bottle was placed in the ultrasonic bath and the chemicals were mixed at 25°C for 30 minutes. The bottle was then removed from the ultrasonic bath and shaken by hand for 5 minutes. The bottle was then placed in the ultrasonic bath again and stirred at 25°C for 30 minutes to produce a clear resin.

[0182] Preparation of test cast samples A test cast sample of the photopolymerizable resin for additive manufacturing was created using the following procedure.

[0183] The resin was filled into a mold (glass, silicone, etc.) and cured in a UV curing oven (UVP CL-1000L, broad UV range with a peak at 365 nm) for approximately 20-30 minutes. The cured material was then removed from the mold. The properties of the cast samples of the cured material obtained in this way were evaluated using experimental methods.

[0184] Example 1: Composition F13 Thiol acrylate resins containing the components shown in Table 1 were prepared. [Table 1]

[0185] The resin had a viscosity of 58 cP at 20°C.

[0186] The resin was photocured to prepare cast samples for testing, and physical and mechanical properties were tested.

[0187] Composition F13 reaches a glass transition temperature of 20° C. The resin behaves as a viscoelastic, tough material at temperatures between 15° C. and 40° C. At this temperature, the toughness of composition F13 is 9.58 MJ / m 3 The strain at break was 66.1%. Furthermore, the resin had a hardness of 96 Shore A.

[0188] Example 2: Composition H6 Thiol acrylate resins containing the components shown in Table 2 were prepared. [Table 2]

[0189] The resin had a viscosity of 504 cP at 20° C. The resin was light cured to produce cast samples for testing, which were then tested for physical and mechanical properties.

[0190] The toughness of this resin is 30.05MJ / m 3 The breaking strain at 20°C was 447%. At temperatures between -30°C and 85°C, the resin behaved as a viscoelastic, tough material. The hardness of the resin was 75 Shore A (see Figure 2).

[0191] Example 3: Composition D8 Thiol acrylate resins containing the components shown in Table 3 were prepared. [Table 3]

[0192] Specifically, HPA (663.3 g), TPO (4.7 g), BBOT (0.24 g), and PE1 (47.4 g) were added to an amber bottle and mixed in an ultrasonic bath at 25 °C for 30 minutes to form a clear solution. CN9004 (284.3 g) was heated in an oven to 80 °C and then added to the amber bottle. The bottle was placed in an ultrasonic bath and the chemicals were mixed for 30 minutes at 25 °C. The bottle was then removed from the ultrasonic bath and shaken by hand for 5 minutes. The bottle was then placed in the ultrasonic bath again and mixed for 30 minutes at 25 °C to form a clear resin.

[0193] This resin was photocured to prepare a cast sample for testing. This sample was used to test the physical and mechanical properties. The resin had a glass transition temperature onset of approximately -15°C, a midpoint of approximately 15°C, and an offset of over 60°C. The toughness at room temperature (20°C) was approximately 3 MJ / m 3 The strain at break was 400-500%. This resin behaves as a tough, viscoelastic material at temperatures between -10°C and 40°C. Furthermore, this resin is an ultra-soft material, with an instantaneous hardness of 30 Shore A, which relaxes to 19 Shore A after a few seconds.

[0194] Example 4 The resins shown in Table 4 were prepared as described above. [Table 4] JPEG2025133741000005.jpg230169 JPEG2025133741000006.jpg15257

[0195] Each resin was photocured to produce cast samples for testing. Hardness was measured. Mechanical properties were also measured using uniaxial extension tests. Depth of cure (DOC) was also measured using the method described above. The results are shown in Table 5. [Table 5]

[0196] Example 5 The resins shown in Table 6 were prepared as described above. [Table 6]

[0197] Each resin was photocured to produce cast samples for testing. Hardness was measured. Mechanical properties were also measured using uniaxial extension testing. Depth of cure (DOC) was also measured using the method described above. The results are shown in Table 7. [Table 7]

[0198] Example 6 The resins shown in Table 8 were prepared as described above. [Table 8]

[0199] Each resin was photocured to produce cast samples for testing. Hardness was measured. Mechanical properties were also measured using uniaxial tensile tests. The results are shown in Table 9. [Table 9]

[0200] Example 7 The resins shown in Table 10 were prepared as described above. [Table 10]

[0201] Each resin was photocured to produce cast samples for testing. Hardness was measured. Mechanical properties were also measured using uniaxial extension testing. DOC (depth of cure) was also measured using the method described above. The results are shown in Table 9. [Table 11]

[0202] Example 8 The resins shown in Table 12 were prepared as described above. [Table 12]

[0203] Each resin was photocured to produce cast samples for testing. Hardness was measured. Additionally, mechanical properties were measured using uniaxial extension tests. Thermal analysis measurements were performed using DMA (Dynamic Mechanical Analysis) and DSC (Differential Scanning Calorimetry) to determine Tg and Tan Delta values. The results are shown in Table 13. [Table 13]

[0204] Example 9 The resins shown in Table 14 were prepared as described above. The original viscosity and the viscosity of the resins after at least six months were measured to determine the percent viscosity change. [Table 14]

[0205] Example 10 The resins shown in Table 15 were prepared as described above. Depth of cure (DOC) was measured as described above. [Table 15]

[0206] Example 11 The resins shown in Table 16 were prepared as described above. Depth of cure (DOC) was measured as described above. [Table 16]

[0207] Example 12 The resins shown in Table 16 were prepared as described above. Depth of cure (DOC) was measured as described above. [Table 17]

[0208] Example 13 The resins shown in Table 18 were prepared as described above. [Table 18] JPEG2025133741000021.jpg204170 JPEG2025133741000022.jpg10640

[0209] Example 14 The resins shown in Table 19 were prepared as described above. [Table 19]

[0210] Example 15 The resins shown in Table 20 were prepared as described above. [Table 20] JPEG2025133741000025.jpg235160 JPEG2025133741000026.jpg65115

[0211] Example 16 The resins shown in Table 21 were prepared as described above. [Table 21] JPEG2025133741000028.jpg185164 JPEG2025133741000029.jpg187147

[0212] Example 17 The resins shown in Table 22 were prepared as described above. [Table 22] JPEG2025133741000031.jpg149115 JPEG2025133741000032.jpg10145

[0213] Each resin was photocured to produce cast samples for testing. Hardness was measured. Additionally, mechanical properties were measured using uniaxial tensile testing. The results are shown in Table 23. [Table 23]

[0214] Examples of Elastomer Thiol Acrylates By using specific thiols in combination with methacrylate monomers and acrylate oligomers, we were able to achieve a mechanically robust 3D printing material (BF 0601) with a durometer value >88 Shore A, elongation >200%, and tear strength >30 kN / m.

[0215] If this same material is formulated with different monomers (e.g., IBoA replaced with 2-HEMA) or oligomers (e.g., 9004 replaced with 9028), it becomes viscoelastic. Using acrylate monomers (e.g., IboA) and methacrylate oligomers (e.g., Chemence 291, 305, and 405 methacrylate oligomers) results in plastic and viscoelastic materials. Combining methacrylate monomers and methacrylate oligomers results in elastic materials, but with poor elongation and tear strength. Removing the thiol from the system results in plastic and viscoelastic materials. Varying the type of thiol (e.g., from PE1 to BD1 to NR1) and the amount added (5 to 3 phr) affects properties (primarily Shore A and elongation), but the general trend (stretchy, tough materials) remains the same.

[0216] By adding a specific molecular oligomer agent, the viscosity of the system can be effectively reduced (based on BF0601) and the Shore A hardness of the system can be adjusted without reducing the tear strength.

[0217] The results showed that the addition of oligomers (TEGDME, polyTHF (1,100 Da), or PEG-PPG-PEG (2,000 Da)) to acrylates (Sartomer CN9004 and CN9028) or metallates (Chemence 291, 305, or 405) resulted in elastomeric materials with various durometer values, all of which had very low tear strength.

[0218] In the BF0601 system (and its close relatives), the addition of 30 phr of oligomeric THF reduced the viscosity from over 7000 cps to 1200 cps (BG0800) at room temperature, reduced the durometer to 60 Shore A, and increased the tear strength to over 26 kN / m. The addition of 5 phr of TEGDME resulted in a dramatic increase in tear strength (up to 42 kN / m) along with a reduction in durometer (~80 Shore A). Thus, good evidence was provided for tailoring the material (BF0601) using oligomeric additives.

[0219] ETR resin formulation and casting process

[0220] For the samples tested in Examples 18-21, the resin formulation and casting procedures were as follows:

[0221] General resin preparation procedure for 1 gram to 1 liter of material.

[0222] The resin was prepared by dissolving solid components, such as photoinitiators, dyes, and inhibitors, in low-viscosity monomers. The components were weighed using a Mettler Toledo analytical balance. The components were mixed in a suitable container and then cleaned in a Branson 2800 ultrasonic cleaner for 35 minutes. The remaining components (thiols, polyols, etc.), except for the urethane diacrylate oligomer, were then added to the container and mixed using a Fisher Scientific fixed-speed vortex mixer and manual shaking. The oligomer was then heated to 60°C in an OV-12 vacuum oven and added to the container. The mixture was then mixed again and ultrasonicated for an additional 35 minutes to further mix and remove bubbles.

[0223] Preparation of test cast sheets

[0224] For material testing and inspection, the resin was polymerized in an Analytik Jena UVP ultraviolet curing oven to create cast sheets of material. The finished resin was poured into a glass mold made from two 6-inch x 6-inch, 1-mm-thick glass plates and a 1-mm-thick glass spacer. The glass mold was coated with Rain-x Original Glass Treatment (polysiloxane) as a mold release for the finished polymer. These filled molds were then placed in a UV curing agent for 30 minutes. The polymerized thermoset resin was removed from the glass mold for material testing.

[0225] Experimental method

[0226] In Examples 18-21, the compositions were characterized using the following techniques.

[0227] UTM Device information UTM:Lloyd Instruments LR5K Plus Extensometer: Lloyd Instruments LaserScan 200 Press: Carver Press 3851-0 Die: ASTM D638 Type V Dogbone Follow ASTM D638 guidelines regarding sample size, test parameters, and calculations.

[0228] Uniaxial tensile tests were performed using a Lloyd Instruments LR5K Plus universal testing machine and a Lasercan 200 laser extensometer. The test method followed the guidelines of ASTM D638. ASTM standard D638 Type V dogbone samples were taken. Sample size, test parameters, and calculations were performed according to the guidelines of ASTM D638. Toughness was measured as the area under the stress-strain curve from the origin to the point of failure.

[0229] DMA Device information DMA: Mettler Toledo DMA-861 Laser cutter: Gravograph LS 100 Sample size: length 12mm, width 3mm, thickness 0.025~1.000mm Test parameters: Tensile test at 1Hz with a maximum amplitude of 10N and a maximum displacement of 15um Follow ASTM D4065 temperature range and calculation guidelines.

[0230] Dynamic mechanical analysis (DMA) was performed using a Mettler-Toledo DMA 861. Cured resin samples were cut into rectangular bars approximately 12 mm long, 3 mm wide, and 0.025–1.0 mm thick. The force was 10 N, and the deformation was limited to 15 μm. The deformation frequency was 1 Hz. The temperature range and calculations were based on the guidelines of ASTM D638.

[0231] DSC Device information Mettler Toledo DSC-1 Sample size: 2-9 mg Sample holder: Aluminum standard 40 ul Test parameters: 40ml / min N2 purge gas, typical 10℃ / min heating rate, typical 3 heating / cooling cycles Follow the temperature range and calculation method guidelines of ASTM E1356.

[0232] Differential scanning calorimetry (DSC) was performed using a Mettler-Toledo DSC-1 with a 40 μL aluminum crucible. To measure the glass transition temperature (Tg), the samples were subjected to three cycles of cooling and heating. The heating and cooling rates were all fixed at 10 °C / min. All tests were performed in a nitrogen purge gas atmosphere at 40 ml / min. Tg was taken as the midpoint of the transition. The temperature range and calculations were performed according to ASTM E1356 guidelines.

[0233] viscosity Device information Brookfield LVT Dial-Reading Viscometer Sample size: 500mL of resin Complies with ASTM D2196 "Guidelines for sample preparation and calculations" The apparent viscosity of the resin was measured with a Brookfield LVT Dial Reading.

[0234] The viscometer was placed in a 600 mL low-form Griffin beaker. Viscosity measurements were performed using various speed and spindle combinations to obtain torque values ​​between 10 and 100%. Readings were taken after the torque values ​​stabilized. Calculations were performed according to ASTM D2196 guidelines.

[0235] Example 18 The resins shown in Table 24 were prepared as described above. [Table 24] JPEG2025133741000035.jpg252167

[0236] Each resin was photocured to produce cast samples for testing. Hardness was measured. Mechanical properties were also measured using uniaxial extension testing. Depth of cure (DOC) was also measured as described above. The results are shown in Table 25. [Table 25]

[0237] Example 19 The resins shown in Table 26 were prepared as described above. [Table 26] JPEG2025133741000038.jpg173110 JPEG2025133741000039.jpg11367

[0238] Each resin was photocured to produce cast samples for testing. Hardness was measured. Additionally, mechanical properties were measured using uniaxial extension testing. Depth of cure (DOC) was measured as described above. The results are shown in Table 27. Data related to BF2602 are provided in the analytical data reports in Appendix 2 and 3. [Table 27] JPEG2025133741000041.jpg102149

[0239] Example 20 The resins shown in Table 28 were prepared as described above. [Table 28] JPEG2025133741000043.jpg175115 JPEG2025133741000044.jpg175111 JPEG2025133741000045.jpg12450

[0240] Each resin was photocured to produce cast samples for testing. Hardness was measured. Additionally, mechanical properties were measured using uniaxial extension testing. Depth of cure (DOC) was measured as described above. The results are shown in Table 29. Additional data for Resin BF0601 are provided in the Analytical Data Report in Appendix 1. [Table 29] JPEG2025133741000047.jpg237139 JPEG2025133741000048.jpg38143

[0241] Example 21 The resins shown in Table 30 were prepared as described above. [Table 30]

[0242] Each resin was photocured to prepare cast samples for testing. Hardness was measured. Mechanical properties were also measured using uniaxial tensile tests. The results are shown in Table 31. [Table 31]

[0243] Table 32 below lists additional data related to resins encompassed within the disclosed embodiments of the present disclosure. [Table 32]

[0244]

[0245] Attachments 1 to 3 JPEG2025133741000052.jpg225167 JPEG2025133741000053.jpg219168 JPEG2025133741000054.jpg221168 JPEG2025133741000055.jpg220168 JPEG2025133741000056.jpg220168 JPEG2025133741000057.jpg222168 JPEG2025133741000058.jpg221168 JPEG2025133741000059.jpg220168 JPEG2025133741000060.jpg226162 JPEG2025133741000061.jpg221168 JPEG2025133741000062.jpg221168 JPEG2025133741000063.jpg220168 JPEG2025133741000064.jpg221168 JPEG2025133741000065.jpg220168 JPEG2025133741000066.jpg219168 JPEG2025133741000067.jpg220168 JPEG2025133741000068.jpg226162 JPEG2025133741000069.jpg221168 JPEG2025133741000070.jpg221168 JPEG2025133741000071.jpg221168 JPEG2025133741000072.jpg221168 JPEG2025133741000073.jpg220168 JPEG2025133741000074.jpg218168 JPEG2025133741000075.jpg218168

Claims

1. 1. A photopolymerizable resin for three dimensional printing, the resin comprising: about 3 to 10 phr thiol; about 30-45% of one or more methacrylate monomers; about 55-70% of one or more acrylate oligomers; Moreover, the resin is configured to react with light irradiation to form a cured product.

2. The photopolymerizable resin of claim 1 , wherein the thiol comprises a secondary thiol.

3. 3. The photopolymerizable resin of claim 2, wherein the secondary thiol comprises at least one of pentaerythritol tetrakis(3-mercaptobutyrate); 1,4-bis(3-mercaptobutyryloxy)butane; and / or 1,3,5-tris(3-mercaptobutyryloxy)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione.

4. The photopolymerizable resin of claim 1 , wherein the one or more acrylic oligomers comprise CN9004.

5. 10. The photopolymerizable resin of claim 1, wherein the one or more methacrylate monomers include at least one 2-hydroxyethyl methacrylate.

6. The photopolymerizable resin of claim 1 further comprising about 0 to 50 phr of one or more oligomeric additives.

7. 7. The photopolymerizable resin of claim 6, further comprising about 5, 10, 15, 20, 25, or 30 phr of one or more oligomeric additives.

8. The photopolymerizable resin of claim 6 , wherein the one or more oligomeric additives comprise at least one polyether.

9. 7. The photopolymerizable resin of claim 6, wherein the one or more oligomeric additives comprise at least one of polytetrahydrofuran, triethylene glycol monomethyl ether, poly(ethylene glycol) block-poly(propylene glycol) block-poly(ethylene glycol), and / or white mineral oil.

10. The photopolymerizable resin of claim 6 , wherein the one or more oligomeric additives comprise polytetrahydrofuran.

11. 10. The photopolymerizable resin of claim 1 further comprising about 30 phr polytetrahydrofuran.

12. The photopolymerizable resin of claim 1 further comprising at least one of a photoinitiator, an inhibitor, a dye, and / or a filler.

13. The photopolymerizable resin of claim 12, wherein the photoinitiator is about 0.01 to 3% by weight of the resin.

14. 13. The photopolymerizable resin of claim 12, wherein the photopolymerization initiator comprises at least one of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bisacylphosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and / or 2,2'-dimethoxy-2-phenylacetophenone.

15. 13. The photopolymerizable resin of claim 12, wherein the inhibitor comprises at least one of hydroquinone, 2-methoxyhydroquinone, butylated hydroxytoluene, diallyl thiourea, and / or diallyl bisphenol A.

16. 13. The photopolymerizable resin of claim 12, wherein the dye comprises at least one of 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene, carbon black, and / or Disperse Red 1.

17. 13. The photopolymerizable resin of claim 12, wherein the filler comprises at least one of boric acid, titanium dioxide, silica, calcium carbonate, clay, aluminosilicate, crystalline molecules, crystalline oligomers, semi-crystalline oligomers, and / or polymers, and the molecular weight of the polymers is from about 1,000 Da to about 20,000 Da.

18. 10. The photopolymerizable resin of claim 1, wherein the photopolymerizable resin has a viscosity of less than about 2000 centipoise at or above room temperature.

19. 10. The photopolymerizable resin of claim 1, wherein the photopolymerizable resin has a viscosity of less than about 1500 centipoise at or above room temperature.

20. 10. The photopolymerizable resin of claim 1, wherein the photopolymerizable resin has a viscosity of less than about 1000 centipoise at or above room temperature.

21. 10. The photopolymerizable resin of claim 1, wherein the photopolymerizable resin has a viscosity of less than about 10,000 centipoise at or above room temperature.

22. An article having a majority of a layer comprising the photopolymerizable resin of claim 1.

23. 10. A footwear midsole, shape memory foam, implantable medical device, wearable article, automobile seat, seal, gasket, damper, hose, fitting, or firearm part made from the photopolymerizable resin of claim 1.

24. 10. An article made from the photopolymerizable resin of claim 1 further comprising a surface coating comprising a thiol.

25. 10. An article made from the photopolymerizable resin of claim 1 further comprising a surface coating comprising an alkane.

26. 10. An article made from the photopolymerizable resin of claim 1 further comprising a surface coating comprising at least one of a semifluorinated polyether and / or a perfluorinated polyether.

27. 10. An article made from the photopolymerizable resin of claim 1 further comprising a surface coating comprising a siloxane polymer.

28. 2. The photopolymerizable resin according to claim 1, wherein the cured product has a Shore A hardness of about 60 to 100.

29. 29. The photopolymerizable resin of claim 28, wherein the cured product has a Shore A hardness of about 80.

30. 29. The photopolymerizable resin of claim 28, wherein the cured product has a Shore A hardness of about 85.

31. 29. The photopolymerizable resin of claim 28, wherein the cured product has a Shore A hardness of about 90.

32. 29. The photopolymerizable resin of claim 28, wherein the cured product has a Shore A hardness of about 95.

33. 2. The photopolymerizable resin according to claim 1, wherein the cured product has a tear strength of about 20 to 40 kN / m.

34. 34. The photopolymerizable resin according to claim 33, wherein the cured product has a tear strength of about 25 kN / m.

35. 34. The photopolymerizable resin according to claim 33, wherein the cured product has a tear strength of about 30 kN / m.

36. 34. The photopolymerizable resin according to claim 33, wherein the cured product has a tear strength of about 35 kN / m.

37. 2. The photopolymerizable resin according to claim 1, wherein the cured product has a breaking strain of about 100% to 300%.

38. 38. The photopolymerizable resin of claim 37, wherein the cured product has a breaking strain of about 200%.

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