Photocurable composition

Abstract

The photocurable composition may include a photocurable resin and a photoinitiator. The photocurable composition is cured at 100° C. for 50 seconds. ‑1 The prepolymer may generally have a shear viscosity of less than 1 Pa·s at a shear rate of , and may generally include a first prepolymer, a second prepolymer, and a reactive diluent.

Description

Background Art

[0001] Photocurable resins based on multifunctional (meth)acrylate monomers are commonly used as thin films (e.g., protective coatings, printing inks) and are also used to make bulk objects such as dental fillings and 3D printed parts. Polyurethane (meth)acrylate (UA) prepolymers are particularly attractive for 3D printing applications due to their excellent flexibility, toughness, wear resistance, and weather resistance. Vinyl monomers are added to reduce resin viscosity, thereby improving processability and / or changing physical properties (e.g., heat resistance, weather resistance). Many factors affect the mechanical properties of cross-linked UA resin formulations, including, for example, (a) the ratio of hard segments to soft segments in the UA prepolymer, (b) the molecular weight of the prepolymer, (c) the concentration and nature of the reactive diluent, and (d) the curing process.

[0002] In many demanding applications of photocurable resins, it is highly desirable to increase polymer toughness while maintaining good thermal stability, which often requires the cured polymer to have a high glass transition temperature (Tg). Different approaches have been tried to achieve these properties, but have shown limited success. For example, photocurable resins can achieve high toughness (e.g., high tensile strength and high elongation at break), but lack thermal stability. Other photocurable resins can achieve high thermal stability, but suffer from low toughness (e.g., low tensile elongation at break). Summary of the invention

[0003] In one aspect, the present disclosure describes a photocurable composition, which may include a photocurable resin and a photoinitiator. The photocurable composition is cured at 100° C. for 50 s -1 The prepolymer may generally have a shear viscosity of less than 1 Pa·s at a shear rate of , and may generally include a first prepolymer, a second prepolymer, and a reactive diluent.

[0004] In another aspect, the present disclosure describes a crosslinked material comprising a cured photocurable composition.

[0005] In yet another aspect, the present disclosure describes a method of making a cross-linked material comprising exposing a photocurable composition to polymerizing electromagnetic radiation.

[0006] Thus, one or more features of the present invention have been outlined rather broadly so that the following detailed description may be better understood, and the contribution to the art may be better appreciated. Other features of the present invention will become more apparent from the following detailed description of the invention and the appended claims, or may be learned through practice of the invention. DETAILED DESCRIPTION

[0007] Although for the purpose of illustration, the following specific embodiments include many details, it will be understood by those of ordinary skill in the art that many changes and modifications can be made to the following details, and these changes and modifications are considered to be included herein. Therefore, the following embodiments are described without losing the generality of any claim set forth, and no limitation is imposed on any claim set forth. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments and are not intended to be restrictive. Unless otherwise defined, all technical and scientific terms used herein will have the same meaning as those of ordinary skill in the art to which the present disclosure belongs.

[0008] As used in this written description, the singular forms "a," "an," and "the" include explicit support for plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a polymer" or "the polymer" may include a plurality of such polymers.

[0009] In this application, "comprising", "including", "containing", and "having" and the like may have the meanings assigned to them in the U.S. patent law, and may mean "including", "comprising", and the like, and are generally interpreted as open terms. The term "consisting of" or "consisting of" is a closed term, and only includes the parts, structures, steps, etc. specifically listed in combination with these terms and the terms according to the U.S. patent law. "Substantially consisting of" or "substantially consisting of" has the meaning generally assigned to it by the U.S. patent law. In particular, such terms are generally closed terms, except that additional items, materials, components, steps, or elements that do not substantially affect the basic and novel characteristics or functions of one or more items used in combination with it are allowed to be included. For example, trace elements that are present in the composition but do not affect the properties or characteristics of the composition will be allowed if they are present in the language of "substantially consisting of", even if they are not explicitly listed in the list of items following such terms. When open terms such as "comprising" or "including" are used in this written description, it should be understood that this also gives direct support to the language of "substantially consisting of" and the language of "consisting of", as if explicitly stated, and vice versa.

[0010] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a particular order or chronological sequence. It should be understood that any terms so used are interchangeable where appropriate, such that the embodiments described herein are, for example, capable of operating in an order other than those indicated or otherwise described herein. Similarly, if a method is described herein as comprising a series of steps, the order of such steps presented herein is not necessarily the only order in which such steps may be performed, and it may be possible that certain steps mentioned may be omitted and / or it may be possible that certain other steps not described herein may be added to the method.

[0011] As used herein, the term "substantially" refers to the scope or degree of completion or near completion of an action, characteristic, property, state, structure, item or result. For example, an object that is "substantially" closed means that the object is either completely closed or close to being completely closed. In some cases, the exact degree of deviation from absolute completion that is allowed can depend on the specific context. However, in general, the proximity of completion will make it possible to have the same overall result as having obtained an absolute and complete completion. When used in a negative sense, the usage of "substantially" can be equally applicable to the lack of completion or near completion of an action, characteristic, property, state, structure, item or result. For example, a composition that is "substantially free of" particles will lack particles completely, or will be close to lacking particles completely, so that the effect is the same as if it lacks particles completely. In other words, a composition that is "substantially free of" ingredients or elements can actually still include such items, as long as there is no measurable effect therein.

[0012] As used herein, the term "about" is used to provide flexibility to numerical range endpoints by providing that a given value can be "slightly above" or "slightly below" the endpoint. Unless otherwise stated, the use of the term "about" in accordance with a specific number or numerical range should also be understood to provide support for such numerical terms or ranges without the term "about". For example, for the sake of convenience and brevity, a numerical range of "about 50 milligrams to about 80 milligrams" should also be understood to provide support for the range of "50 milligrams to 80 milligrams". In addition, it should be understood that in this specification, even when the term "about" is used with it, support for actual numerical values ​​is provided. For example, the description of "about" 30 should be interpreted as providing support not only for values ​​slightly above and slightly below 30, but also for the actual numerical value of 30. Unless otherwise stated, all numerical parameters should be understood to be preceded and modified by the term "about" in all cases, wherein the numerical parameters have the inherent variability characteristics of the underlying measurement technology used to determine the numerical value of the parameter.

[0013] As used herein, for convenience, multiple items, structural elements, constituent elements, and / or materials may be presented in a common list. However, these lists should be interpreted as if each member in the list is individually identified as a separate and unique member. Therefore, no individual member in such a list should be interpreted as being effectively an equivalent of any other member in the same list solely based on its presentation in a common group without an indication to the contrary.

[0014] Concentration, amount and other numerical data can be expressed or presented in range format herein.It should be understood that such range format is used only for convenience and simplicity, and should therefore be flexibly interpreted as not only including the numerical value clearly enumerated as range limit, but also including all independent numerical values ​​or subranges included in the range, as if each numerical value and subrange are clearly enumerated.As an illustration, the numerical range of "1 to 5" should be interpreted as not only including the value of 1 to 5 clearly enumerated, but also including independent values ​​and subranges in the indicated range.Therefore, included in the numerical range are independent values ​​such as 2,3 and 4, and subranges such as 1-3,2-4 and 3-5, and independent 1,2,3,4 and 5.

[0015] This same principle applies to ranges that recite only one numerical value as a minimum or maximum. Furthermore, such an interpretation should apply regardless of the magnitude or character of the range being described.

[0016] References to "examples" throughout this specification indicate that a particular feature, structure, or characteristic described in conjunction with the example is included in at least one embodiment. Therefore, the phrases "in an example" appearing in various places throughout this specification do not necessarily all refer to the same embodiment.

[0017] Example Implementation

[0018] Photocurable resin formulations can be used to make complex objects, such as via 3D printing. Within the formulation, polyurethane (meth) acrylate (UA) prepolymers can contribute to the toughness (e.g., high tensile strength and elongation at break) of the photocurable composition. Typically, UA prepolymers can be synthesized from multifunctional polyols, diisocyanates, and hydroxyl-functional (meth) acrylates. Alternatively, UA prepolymers can be synthesized from multifunctional polyols and NCO-functional (meth) acrylates. Photocurable UA prepolymers typically have a glass transition temperature (Tg) (e.g., <50°C) associated with the structure of the polyurethane soft segment. Reactive diluents (e.g., high Tg (meth) acrylate monomers) can be combined with UA prepolymers to provide adjustable mechanical properties (e.g., modulus, elongation at break) and adjust the appropriate operating temperature for certain demanding applications. In this approach, a typical challenge is that when the reactive diluent content becomes the main component in the formulation (e.g., >50 wt%), the toughness of the resin decreases rapidly due to the decrease in tensile elongation.

[0019] When using low molecular weight diols to synthesize UA prepolymers, the cured UA prepolymers often show high Tg and high modulus, but poor tensile elongation at break. In some cases, this may be attributed to the high crosslink density of the polyurethane hard segment, such as when the molecular weight of the UA prepolymer is relatively low. In contrast, synthesizing UA prepolymers with higher molecular weights to improve mechanical properties can lead to high viscosity, which may be difficult to control for many applications. In this method, although it is possible to toughen the composition containing the hard segment prepolymer, the improvement of resin toughness (e.g., tensile elongation at break) is often limited.

[0020] In one aspect, the present disclosure relates to a photocurable composition having a controllable viscosity and also providing a high Tg and good mechanical properties, and a method for making the same. The photocurable composition may include a blend of a first prepolymer having a high Tg after curing and a second prepolymer having a low Tg after curing, wherein the cured composition has a microphase separation structure. In some examples, the first prepolymer may have a melting point of less than 60°C. In some examples, the second prepolymer may have a Tg of less than -40°C. In some other examples, the photocurable composition may also include a reactive diluent suitable as a solvent for the two prepolymers.

[0021] Without wishing to be bound by theory, it is believed that the first prepolymer and the reactive diluent can form a high Tg crosslinked network as the main continuous phase, which is co-crosslinked with the low Tg rubber network formed by the second prepolymer and the reactive diluent. The low Tg rubber network can be microphase separated from the high Tg crosslinked network, thereby affecting the toughness of the cured photocurable composition without strongly affecting the thermal stability of the main phase.

[0022] In contrast, when the high Tg network and the low Tg network are miscible in the cured state, the soft phase can plasticize the high Tg phase, resulting in good tensile strength and high clarity, but a high yield point and low tensile elongation at break. In contrast, when the high Tg network and the low Tg network are immiscible, resulting in macrophase separation in the cured state, the cured composition may have no yield point, but mechanical properties and clarity may be impaired. Therefore, the microphase-separated composition can obtain synergistic effects from the high Tg network and the low Tg network, thereby achieving high modulus, a yield point of >5% strain, high tensile strength and good clarity, while also maintaining good thermal stability.

[0023] For example, in some cases, a photocurable composition having a microphase-separated structure in the cured state can be obtained by polymerization-induced phase separation. This can be achieved by balancing the molecular weights of the first prepolymer and the second prepolymer to promote uniform mixing before curing, but at this time, since these phases are incompatible in the polymerized prepolymer, the soft phase and the hard phase are separated after curing.

[0024] Additionally, the miscibility between the two polymer networks is often temperature dependent, where they generally become more miscible at elevated temperatures. Thus, design considerations for suitable photocurable compositions may include prepolymer structure, molecular weight, and comparable miscibility at the expected photocuring temperature.

[0025] In more detail, in some examples, the photocurable composition may include a photocurable resin and a photoinitiator. The photocurable resin may generally include a first prepolymer, a second prepolymer, and a reactive diluent.

[0026] Based on the total weight of the photocurable resin, the first prepolymer can be present in the photocurable resin in an amount of 20 wt % to 60 wt %. In some other examples, based on the total weight of the photocurable resin, the first prepolymer can be present in the photocurable resin in an amount of 30 wt % to 50 wt %. In still other examples, based on the total weight of the photocurable resin, the first prepolymer can be present in the photocurable resin in an amount of 30 wt % to 40 wt %, 35 wt % to 45 wt %, or 40 wt % to 50 wt %.

[0027] The first prepolymer may generally have a number average molecular weight of ≤2000 g / mol, as measured by gel permeation chromatography using a polystyrene retention time standard. Typically, unless otherwise noted, gel permeation chromatography is used to determine all molecular weight values ​​disclosed herein, using a polystyrene retention time standard in each case. In some other examples, the first prepolymer may have a number average molecular weight of ≤1800 g / mol. In yet other examples, the first prepolymer may have a number average molecular weight of ≤1500 g / mol. In some further examples, the first prepolymer may have a number average molecular weight of ≤1200 g / mol, ≤1100 g / mol, ≤1000 g / mol, or ≤900 g / mol.

[0028] The first prepolymer can generally be the reaction product of the first reaction mixture comprising alicyclic diisocyanate, isocyanate reactive components and hydroxyl functional (meth) acrylate. A variety of alicyclic diisocyanates can be included in the first reaction mixture. Non-limiting examples of alicyclic diisocyanates can include cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyanato-2-isocyanatomethylcyclopentane, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isophorone diisocyanate or IPDI), bis-(4-isocyanatocyclohexyl)-methane (H 12 MDI), 1,3-bis(isocyanatomethyl)-cyclohexane, 1,4-bis(isocyanatomethyl)-cyclohexane, bis-(4-isocyanato-3-methyl-cyclohexyl)methane, 1-isocyanato-1-methyl-4(3)-isocyanatomethylcyclohexane, 2,4-hexahydrotolylene diisocyanate, 2,6-hexahydrotolylene diisocyanate, etc. or a combination thereof. In some specific examples, the alicyclic diisocyanate of the first reaction mixture may include IPDI, H 12 MDI or a combination thereof. In a further example, the alicyclic diisocyanate of the first reaction mixture may include IPDI. In a still further example, the alicyclic diisocyanate of the first reaction mixture may include H 12 MDI.

[0029] In some examples, the first reaction mixture does not contain aromatic polyisocyanates or aliphatic polyisocyanates other than alicyclic diisocyanates. In other examples, the first reaction mixture contains 80 wt % to 100 wt %, 90 wt % to 100 wt %, or 95 wt % to 100 wt % of alicyclic diisocyanates based on the total weight of any polyisocyanates present in the first reaction mixture.

[0030] The first reaction mixture may also include a variety of isocyanate reactive components. As used herein, "isocyanate reactive components" refers to components comprising hydroxyl groups, amino groups, thiol groups or combinations thereof. Isocyanate reactive components may generally have a functionality of 2 or greater than or equal to 2. Therefore, isocyanate reactive components may be or may include a variety of components, and non-limiting examples thereof may include polyols (e.g., diols, triols, etc.), polyamines (e.g., diamines, triamines, etc.), polythiols (e.g., dithiols, trithiols, etc.), etc. or combinations thereof. In some instances, the isocyanate reactive components of the first reaction mixture may be or may include C2-C 12 In some further examples, the isocyanate reactive component of the first reaction mixture may be or may include a C2-C8 linear or branched aliphatic polyol, polyamine, polythiol or a combination thereof; a C4-C 10 Linear or branched aliphatic polyols, polyamines, polythiols or combinations thereof; C6-C 12 A linear or branched aliphatic polyol, a polyamine, a polythiol or a combination thereof; or a mixture of any of these components. In some specific examples, the isocyanate reactive component of the first reaction mixture may be or may include C2-C 12 In some further examples, the isocyanate-reactive component of the first reaction mixture may be or may include a C2-C8 linear or branched aliphatic polyol, a C4-C 10 Linear or branched aliphatic polyols, C6-C 12Linear or branched aliphatic polyols or combinations thereof. Non-limiting examples of isocyanate reactive components may include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 2-methyl-1,4-butylene glycol, 3-methyl-1,3-butylene glycol, 1,2,4-butylene triol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 3-methyl-2,4-pentanediol, 2-methyl -1,3-pentanediol, 2-methyl-1,5-pentanediol, 1,2,5-pentanetriol, 1,6-hexanediol, 1,2-hexanediol, 1,5-hexanediol, 2-methyl-1,6-hexanediol, 4-methyl-1,3-hexanediol, 5-methyl-2,4-hexanediol, 3-methyl-1,6-hexanediol, 1,2,6-hexanetriol, 1,7-heptanediol, 2,5-heptanediol, 4-methyl-1, 6-heptanediol, 3-methyl-2,4-heptanediol, 2-methyl-2,6-heptanediol, 5-methyl-2,4-heptanediol, 4-methyl-1,7-heptanediol, 1,2,7-heptanetriol, 1,8-octanediol, 2-methyl-1,8-octanediol, 7-methyl-1,7-octanediol, 6-methyl-1,7-octanediol, 3-methyl-1,4-octanediol, 1,2,8-octanediol, 1,9 -nonanediol, 8-methyl-1-8-nonanediol, 1,2,9-nonanetriol, 1,10-decanediol, 2-methyl-1,10-decanediol, 2-methyl-2,5-decanediol, 4,8-bis(hydroxymethyl)tricyclo[5.2.1.02,6]decane (DCPDM), 1,11-undecanediol, 1,12-dodecanediol, etc., or their corresponding polyamines, or their corresponding polythiol or combinations thereof. In some specific examples, the isocyanate reactive component may be or may include 3-methyl-1,5-pentanediol. In some other specific examples, the isocyanate reactive component may be or may include 1,4-butanediol. In some further specific examples, the isocyanate reactive component may be or may include DCPDM. In still other specific examples, the isocyanate reactive component may be or may include 1,9-nonanediol.

[0031] Alicyclic diisocyanate and isocyanate reactive components can be combined in the first reaction mixture with an NCO / OH index of 1.2 to 3.0. It should be noted that for the sake of brevity, the NCO / OH index is used throughout the present disclosure, but these statements are also intended to equally state the NCO / NH index or the NCO / SH index, when suitable for a specific situation. In some other examples, alicyclic diisocyanate and isocyanate reactive components can be combined in the first reaction mixture with an NCO / OH index of 1.3 to 2.3, 1.5 to 2.5 or 1.8 to 2.8. In some examples, alicyclic diisocyanate and isocyanate reactive components can be combined in the first reaction mixture before adding hydroxyl-functional (meth) acrylate to the first reaction mixture. In other examples, alicyclic diisocyanate, isocyanate reactive components and hydroxyl-functional (meth) acrylate can be added to the first reaction mixture simultaneously.

[0032] The first reaction mixture may include a variety of hydroxyl-functional (meth)acrylates. As used herein, the term "(meth)acrylate" refers to acrylates and / or corresponding methacrylates. In some examples, the hydroxyl-functional (meth)acrylate may be or may include C4-C 10 Hydroxyalkyl (meth) acrylates (i.e., hydroxyalkyl (meth) acrylates containing 4 to 10 total carbon atoms). In some specific examples, the hydroxyl functional (meth) acrylate can be or can include C4-C8 hydroxyalkyl (meth) acrylates and / or C6-C 10 Hydroxyalkyl (meth) acrylate. The non-limiting examples of hydroxyl-functional (meth) acrylate can include hydroxymethyl acrylate, hydroxymethyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxypentyl acrylate, hydroxypentyl methacrylate, hydroxyhexyl acrylate, hydroxyhexyl methacrylate, etc. or its combination. In some specific examples, the hydroxyl-functional (meth) acrylate of the first reaction mixture can be or can include hydroxyethyl acrylate and / or hydroxyethyl methacrylate. In some instances, the hydroxyl-functional (meth) acrylate of the first reaction mixture can be or can include hydroxyethyl acrylate. In some instances, the hydroxyl-functional (meth) acrylate of the first reaction mixture can be or can include hydroxyethyl methacrylate.

[0033] Based on the gross weight of the photocurable resin, the second prepolymer can be present in the photocurable resin with an amount of 15 wt % to 40 wt %. In some other examples, based on the gross weight of the photocurable resin, the second prepolymer can be present in the photocurable resin with an amount of 20 wt % to 35 wt % or 25 wt % to 30 wt %. In still other examples, based on the gross weight of the photocurable resin, the second prepolymer can be present in the photocurable resin with an amount of 15 wt % to 25 wt %, 20 wt % to 30 wt % or 25 wt % to 35 wt %.

[0034] The second prepolymer of photocurable resin can generally have a number average molecular weight of 2000g / mol to 10,000g / mol, as measured by gel permeation chromatography using a polystyrene retention time standard. In some other examples, the second prepolymer can have a number average molecular weight of 3000g / mol to 8000g / mol. In yet other examples, the second prepolymer can have a number average molecular weight of 2500g / mol to 5000g / mol. In some further examples, the second prepolymer can have a number average molecular weight of 2000g / mol to 4000g / mol, 2500g / mol to 3500g / mol or 3000g / mol to 6000g / mol.

[0035] The second prepolymer can be the reaction product of a second reaction mixture comprising a (meth)acrylate and a polyactive hydrogen compound. A variety of second prepolymers can be included in the photocurable resin. As non-limiting examples, the second prepolymer can be or can include a di(meth)acrylate functionalized polyactive hydrogen compound (e.g., HEMA-PTMG-HEMA, as an illustrative example); a reaction product of a second reaction mixture comprising an isocyanate-terminated (meth)acrylate and a polyactive hydrogen compound; a reaction product of a second reaction mixture comprising a diisocyanate, a hydroxyl-functional (meth)acrylate, and a polyactive hydrogen compound; etc.; or a combination thereof.

[0036] The second reaction mixture may include a variety of (meth)acrylates. In some examples, the (meth)acrylates of the second reaction mixture may be or may include isocyanate-terminated (meth)acrylates. In some other examples, the (meth)acrylates of the second reaction mixture may be hydroxyl-functional (meth)acrylates. In some examples, the (meth)acrylates of the second reaction mixture may be or may include C4-C 10 In some specific examples, the (meth)acrylate of the second reaction mixture may be or may include C4-C8 hydroxyalkyl (meth)acrylate and / or C6-C 10Hydroxyalkyl (meth) acrylate. The non-limiting examples of hydroxyl-functional (meth) acrylate can include hydroxymethyl acrylate, hydroxymethyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxypentyl acrylate, hydroxypentyl methacrylate, hydroxyhexyl acrylate, hydroxyhexyl methacrylate, etc. or its combination. In some specific examples, the hydroxyl-functional (meth) acrylate of the second reaction mixture can be or can include hydroxyethyl acrylate and / or hydroxyethyl methacrylate. In some instances, the hydroxyl-functional (meth) acrylate of the second reaction mixture can be or can include hydroxyethyl acrylate. In some instances, the hydroxyl-functional (meth) acrylate of the second reaction mixture can be or can include hydroxyethyl methacrylate.

[0037] The second reaction mixture may also include a plurality of polyactive hydrogen compounds. As used herein, "polyactive hydrogen compound" refers to any compound containing a plurality of Zerewitinoff active hydrogen atoms. "Zerewitinoff active hydrogen" herein refers to an acidic hydrogen atom or active hydrogen atom that can be identified using a known Zerewitinoff assay (e.g., by reactivity with a corresponding Grignard reagent). In some specific examples, the polyactive hydrogen compound may be or may include a polyol (e.g., a diol, a triol, etc.), a polyamine (e.g., a diamine, a triamine, etc.), a polythiol (e.g., a dithiol, a trithiol, etc.), or a combination thereof.

[0038] In some examples, the polyactive hydrogen compound may have a number average molecular weight of 1000 g / mol to 5000 g / mol, as measured by gel permeation chromatography using a polystyrene retention time standard. In some other examples, the polyactive hydrogen compound may have a number average molecular weight of 1200 g / mol to 4000 g / mol or 1400 g / mol to 3000 g / mol. In some specific examples, the polyactive hydrogen compound may have a number average molecular weight of 1000 g / mol to 1500 g / mol, 1200 g / mol to 2000 g / mol, 1500 g / mol to 2500 g / mol, 2000 g / mol to 3000 g / mol, or 2500 g / mol to 3500 g / mol.

[0039] In some examples, the poly-active hydrogen compound may have a δ < 18.9 MPa 1 / 2 In some other examples, the multi-active hydrogen compound may have a Hansen solubility parameter of δ>16 MPa 1 / 2 To δ<18.9MPa 1 / 2Hansen solubility parameters. Hansen described the overall solubility parameter δ as a combination of three components reflecting dispersion (δD), polarity (δP), and hydrogen bonding (δH) interactions: δ 2 =δ 2 TOT =δD 2 +δP 2 +δH 2 . The components δD, δP and δH are named Hansen solubility parameters HSP. Hansen also defined a 3D solubility diagram (δD, δP, δH) in which a solubility sphere with radius R0 can be defined for a macromolecule. Analysis of the HSP of a polymer can be determined based on solubility tests in solvents of known HSP, where a good solvent for the component is encompassed in the sphere space, as described in Appendix A of Hansen Solubility Parameters: A User's Manual (2007, CRC Press). For example, based on the solubility tests described, it has been determined that Desmophen 1200 has a solubility of 21.6 MPa 1 / 2 The total δ of PTMG is 17.6MPa 1 / 2 The total δ of PPG is 18.9MPa 1 / 2 The total δ.

[0040] In some other examples, the second reaction mixture may include a diisocyanate. When the second reaction mixture includes a diisocyanate, the diisocyanate may generally include an alicyclic diisocyanate, an aromatic diisocyanate, or a combination thereof. In some examples, the diisocyanate of the second reaction mixture may be or may include an alicyclic diisocyanate. In this case, the alicyclic diisocyanate may be or may include cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyanato-2-isocyanatomethylcyclopentane, IPDI, H 12 MDI, 1,3-bis(isocyanatomethyl)-cyclohexane, 1,4-bis(isocyanatomethyl)-cyclohexane, bis-(4-isocyanato-3-methyl-cyclohexyl)methane, 1-isocyanato-1-methyl-4(3)-isocyanatomethylcyclohexane, 2,4-hexahydrotolylene diisocyanate, 2,6-hexahydrotolylene diisocyanate, etc. or combinations thereof. In some specific examples, the alicyclic diisocyanate of the second reaction mixture may include IPDI, H 12 MDI or a combination thereof. In a further example, the alicyclic diisocyanate of the second reaction mixture may include IPDI. In a still further example, the alicyclic diisocyanate of the second reaction mixture may include H 12MDI. In other examples, the diisocyanate of the second reaction mixture may be or may include an aromatic diisocyanate. In this case, the aromatic diisocyanate of the second reaction mixture may be or may include methylene diphenyl diisocyanate (MDI) (e.g., 2,4'-MDI, 4,4'-MDI, or a mixture thereof), toluene diisocyanate (TDI) (e.g., 2,4-TDI, 2,6-TDI, or a mixture thereof), or a combination thereof. In some examples, the aromatic diisocyanate of the second reaction mixture may be or may include MDI.

[0041] When the second reaction mixture includes a diisocyanate, the diisocyanate and the polyactive hydrogen compound can generally be combined in the second reaction mixture at an NCO / OH index of 1.2 to 3.0. In some further examples, the diisocyanate and the polyactive hydrogen compound can be combined in the second reaction mixture at an NCO / OH index of 1.3 to 2.3, 1.5 to 2.5, or 1.8 to 2.8. In some specific examples, the diisocyanate and the polyactive hydrogen compound can be combined in the second reaction mixture at an NCO / OH index of 2.

[0042] Photocurable resin can also include reactive diluent. Based on the gross weight of photocurable resin, reactive diluent can be present in photocurable resin with 20 wt % to 65 wt % amount usually. In some other examples, based on the gross weight of photocurable resin, reactive diluent can be present in photocurable resin with 30 wt % to 50 wt % or 40 wt % to 60 wt % amount. In still other examples, based on the gross weight of photocurable resin, reactive diluent can be present in photocurable resin with 25 wt % to 35 wt %, 35 wt % to 45 wt % or 40 wt % to 50 wt % amount.

[0043] The photocurable resin may include a variety of reactive diluents. In some examples, the reactive diluent may be or may include C 10 -C 18 (Meth)acrylate monomer. 10 -C 18Non-limiting examples of the (meth)acrylate monomers may include isobornyl acrylate, isobornyl methacrylate, cyclohexyl methacrylate, cis-4-tert-butyl-cyclohexyl methacrylate, 4-tert-butylcyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, 3,3,5-trimethylcyclohexyl methacrylate, dicyclopentanyl acrylate, dicyclopentanyl methacrylate, 3,5-dimethyl-1-adamantyl acrylate, 3,5-dimethyl-1-adamantyl methacrylate, tert-butyl methacrylate, 2-decalinyl methacrylate, 1-adamantyl acrylate, 1-adamantyl methacrylate, 2-ethylhexyl methacrylate, 3-tetracyclo[4.4.0.1.1]dodecyl methacrylate, tetrahydrofuranyl methacrylate, 2-phenoxyethyl methacrylate, N-vinyl pyrrolidone, carboxyethyl acrylate, acryloylmorpholine, and the like, or combinations thereof.

[0044] In addition to the photocurable resin, the photocurable composition may further include a photoinitiator. Various photoinitiators may be included in the photocurable composition. Non-limiting examples may include IRGACURE and DAROCUR from BASF, such as 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184), 2,2-dimethoxy-1,2-diphenylethane-1-one (IRGACURE 651), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (IRGACURE 819), 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1-one (IRGACURE 2959), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone (IRGACURE 369), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one (IRGACURE 907), oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone] (ESACURE ONE), 2-hydroxy-2-methyl-1-phenylpropane-1-one (DAROCUR 1173), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (IRGACURE TPO) and 2,4,6-trimethylbenzoylphenylphosphinate (IRGACURE TPO-L), etc. or a combination thereof. Additional non-limiting examples of photoinitiators may include benzyl dimethyl ketal, 2-methyl-2-hydroxypropiophenone, benzoin methyl ether, benzoin isopropyl ether, anisole methyl ether, aromatic sulfonyl chloride, photoactive oxime, etc. or a combination thereof.

[0045] The photocurable composition may optionally include various additives. Non-limiting examples of additives may include impact modifiers, colorants, thickeners, resins, defoamers, surfactants, UV absorbers, flame retardants, etc. or combinations thereof. In some specific examples, the photocurable composition may include colorants. The type of colorant is not particularly limited, and any suitable colorant (e.g., dye, pigment, etc. or combinations thereof) may be used in the photocurable composition. In some other specific examples, the photocurable composition may include impact modifiers. The type of impact modifier is not particularly limited, and any suitable impact modifier (e.g., liquid rubber, core-shell rubber particles, etc. or combinations thereof) may be used in the photocurable composition.

[0046] The photocurable composition can have a variety of viscosities, depending on the application. Typically, the photocurable composition is cured at 100°C for 50 seconds. -1 The photocurable composition may have a shear viscosity of less than 1 Pa·s at a shear rate of 1.5 %. In some other examples, the photocurable composition may have a shear viscosity of less than 1 Pa·s at a shear rate of 1.5 %. -1 The photocurable composition may have a shear viscosity of less than 1 Pa·s at a shear rate of 1.5 s. In yet another example, the photocurable composition may have a shear viscosity of less than 1 Pa·s at a shear rate of 1.5 s. -1 The material may have a shear viscosity of less than 1 Pa·s at a shear rate of .

[0047] The present disclosure also describes a method for making a photocurable composition. Generally, the method can include combining a photocurable resin as described herein with a photoinitiator as described herein. The photocurable resin can be prepared by combining a first prepolymer, a second prepolymer, and a reactive diluent.

[0048] The first prepolymer can be prepared in a variety of ways. In some instances, the first prepolymer can be prepared by combining alicyclic diisocyanates and isocyanate-reactive components to form a first product. Usually, the isocyanate-reactive component can be slowly added to the alicyclic diisocyanate to minimize heat release and reduce molecular weight distribution. The first product can be combined with a hydroxy-functional (meth) acrylate to form a first prepolymer. In other instances, the first prepolymer can be prepared by combining alicyclic diisocyanates with hydroxy-functional (meth) acrylate to form an isocyanate-terminated (meth) acrylate. Then the isocyanate-terminated (meth) acrylate can be combined with the isocyanate-reactive component to form the first prepolymer.

[0049] The second prepolymer can also be prepared in a variety of ways. In some examples, the second prepolymer can be prepared by combining (meth) acrylate and multi-active hydrogen compounds under conditions suitable for forming di(meth) acrylate functionalized multi-active hydrogen compounds (e.g., HEMA-PTMG-HEMA). In other examples, the second prepolymer can be prepared by combining diisocyanates with (meth) acrylate to form isocyanate-terminated (meth) acrylate. Isocyanate-terminated (meth) acrylate can be combined with multi-active hydrogen compounds to form the second prepolymer. In yet other examples, the second prepolymer can be formed by combining diisocyanates with multi-active hydrogen compounds to form a second product. Multi-active hydrogen compounds can usually be slowly added to diisocyanates to minimize heat release. The second product can be combined with (meth) acrylate to form a second prepolymer.

[0050] The first prepolymer and the second prepolymer can be uniformly mixed with a reactive diluent to form a photocurable resin. A photoinitiator can be added to the photocurable resin to form a photocurable composition. Before photocuring, the photocurable composition can be optionally heated to a temperature suitable for photocuring. In other examples, when photocuring is intended to be carried out at ambient temperature or below ambient temperature, heating may not be performed. In some examples, as the temperature increases, the prepolymer may become more miscible.

[0051] The present disclosure also describes a crosslinked material made by curing a photocurable composition and a method of making the same. In more detail, the photocurable composition can be exposed to suitable electromagnetic radiation to at least partially crosslink the photocurable composition to form at least a portion of the crosslinked material.

[0052] In some examples, the cross-linked material can have a transparent or translucent appearance. In some specific examples, based on ASTM D1003, using a film with a thickness of 0.3 mm, the cross-linked material can have a transparency or transmittance of greater than or equal to 75% transmittance at room temperature. In other examples, the cross-linked material can have a transparency or transmittance of greater than or equal to 80% transmittance at room temperature. In yet another example, the cross-linked material can have a transparency or transmittance of greater than or equal to 85% transmittance at room temperature.

[0053] The present disclosure also describes a method for making a cross-linked material. In some examples, the method may include applying (e.g., casting, coating, brushing, rolling, dipping, spraying, depositing, etc.) a photocurable composition as described herein on at least a portion of a substrate. Any suitable substrate may be used, such as wood, plastic, ceramic, metal, glass, etc. The photocurable composition may be cured (e.g., exposed to electromagnetic radiation sufficient to induce photopolymerization) to form a cross-linked material on the substrate, or in other words, a coated substrate comprising a coating of a cross-linked material.

[0054] In some other examples, the method of making the cross-linked material may be or may include an additive manufacturing method. An additive manufacturing method refers to a method of manufacturing a product based on a 3D object model (e.g., a CAD model) by adding materials together (such as by depositing materials, bonding materials, solidifying materials, or a combination thereof), usually in a layer-by-layer manner. In some specific examples, the additive manufacturing method may be or may include stereolithography, digital light processing, continuous liquid interface production, etc. Other suitable additive manufacturing methods may also be used. In addition, other suitable non-additive manufacturing methods may also be used to prepare the cross-linked material.

[0055] The photocurable composition is heated at 100°C for 50 seconds. -1 The photocurable composition may generally have a shear viscosity of less than 1 Pa·s at a shear rate of . Therefore, for coating and additive manufacturing methods using photopolymerization, the photocurable composition described herein can be applied as a film / coating or printed as a 2D or 3D object at a relatively low temperature. For example, in some cases, the photocurable composition may be applied or printed at a temperature of less than 100°C. In yet other examples, the photocurable composition may be applied or printed at a temperature of less than 90°C, less than 80°C, less than 70°C, less than 60°C, or less than 50°C. In some specific examples, the photocurable composition may be applied or printed at a temperature of 20°C to 100°C. In some other examples, the photocurable composition may be applied or printed at a temperature of 20°C to 60°C or 20°C to 40°C.

[0056] In addition, in some cases, curing (e.g., exposure to electromagnetic radiation sufficient to induce photopolymerization) can also be performed at relatively low temperatures. In some specific examples (e.g., in DLP printing), curing and printing can be performed in the same step. In other examples, application / printing and curing can be performed sequentially (e.g., applying a coating to a substrate and then curing the coating to form a coated substrate). In some examples, curing can be performed at a temperature of less than 100°C. In yet other examples, curing can be performed at a temperature of less than 90°C, less than 80°C, less than 70°C, less than 60°C, or less than 50°C. In some specific examples, curing can be performed at a temperature of 20°C to 100°C. In some other examples, curing can be performed at a temperature of 20°C to 60°C or 20°C to 40°C.

[0057] In some examples, the manufacturing method can include introducing a photocurable composition into a container. The container can be positioned to allow the photocurable composition to substantially contact or cover the substrate or build platform. The portion of the substrate or build platform that contacts or is covered by the photocurable composition can depend on the direction in which the photocurable composition will be exposed to polymerizing electromagnetic radiation.

[0058] As used herein, "polymerizing electromagnetic radiation" may include any type of electromagnetic radiation suitable for promoting or inducing photopolymerization of a photocurable composition. In some instances, the polymerizing electromagnetic radiation may be or may include ultraviolet electromagnetic radiation (e.g., electromagnetic radiation having a wavelength of 10 nm to 400 nm). In some instances, the polymerizing electromagnetic radiation may be or may include visible electromagnetic radiation (e.g., electromagnetic radiation having a wavelength of 380 nm to 750 nm). In some instances, the polymerizing electromagnetic radiation may be or may include infrared electromagnetic radiation (e.g., electromagnetic radiation having a wavelength of 700 nm to 1 mm).

[0059] The polymerizing electromagnetic radiation may be applied to the photocurable composition for an amount of time suitable for photopolymerizing the photocurable composition to form a crosslinked material. The amount of time may depend on the wavelength of the electromagnetic radiation, the intensity of the electromagnetic radiation, the thickness of the photocurable composition, etc. In some examples, the polymerizing electromagnetic radiation may be applied to the photocurable composition in multiple doses, such as in multiple doses to a single layer, or in one or more doses to each of multiple layers or segments, etc., or a combination thereof to form a crosslinked material.

[0060] When applying a photocurable composition via additive manufacturing, the photocurable composition can be printed based on the 3D object model to form a 3D crosslinked material. For example, based on a 3D object model of a crosslinked material, a photocurable composition can be applied to a build platform and selectively exposed to polymerized electromagnetic radiation to form a crosslinked interface layer bonded to the build platform. Based on the 3D object model, an additional photocurable composition can be applied to the interface layer (and / or an additional crosslinked layer) and selectively exposed to polymerized electromagnetic radiation to form one or more additional crosslinked layers until the 3D object is completed based on the 3D object model. In some instances, applying an additional photocurable composition to the interface layer and / or an additional crosslinked layer can include moving the build platform a distance of ≥1 μm to ≤2000 μm to apply an additional photocurable composition to the crosslinked interface layer and / or an additional crosslinked layer. In some instances, applying an additional photocurable composition to the interface layer and / or an additional crosslinked layer can include depositing a photocurable composition to the interface layer and / or an additional crosslinked layer with or without moving the build platform.

[0061] Curing the photocurable composition can form a cross-linked material, which includes a co-cross-linked polymer network, which includes a first polymer network having a first Tg and a second polymer network having a second Tg. The first polymer network may include a cross-linked first prepolymer and a reactive diluent. Based on dynamic mechanical analysis at a heating ramp rate of 3°C / min and a frequency of 1 Hz, the first Tg can generally be greater than 80°C as a loss modulus (E") peak. In yet other examples, based on dynamic mechanical analysis at a heating ramp rate of 3°C / min and a frequency of 1 Hz, the first Tg can be greater than 100°C or greater than 120°C as a loss modulus (E") peak.

[0062] The second polymer network may include a cross-linked second prepolymer and a reactive diluent. Based on dynamic mechanical analysis at a heating ramp rate of 3°C / min and a frequency of 1 Hz, the second Tg may generally be less than -40°C as a loss modulus (E") peak. In yet other examples, based on dynamic mechanical analysis at a heating ramp rate of 3°C / min and a frequency of 1 Hz, the second Tg may be less than -50°C or less than -60°C as a loss modulus (E") peak.

[0063] The cross-linked material can have a variety of mechanical properties. In some examples, the cross-linked material can have a yield strain greater than or equal to 5% based on tensile testing ASTM D638, Type 4 specimens, using a pulling speed of 50 mm / min under ambient conditions. In yet other examples, the cross-linked material can have a yield strain greater than or equal to 6% or 8% based on ASTM D638, Type 4 specimens, using a pulling speed of 50 mm / min under ambient conditions.

[0064] In some additional examples, the cross-linked material can have an elastic modulus greater than or equal to 900 MPa based on ASTM D638, Type 4 specimens, using a pull rate of 50 mm / min under ambient conditions. In still further examples, the cross-linked material can have an elastic modulus greater than or equal to 1000 MPa, greater than or equal to 1200 MPa, or greater than or equal to 1500 MPa based on ASTM D638, Type 4 specimens, using a pull rate of 50 mm / min under ambient conditions.

[0065] In some further examples, the cross-linked material can have a tensile stress at break of greater than or equal to 30 MPa based on ASTM D638, Type 4 specimens, using a pull rate of 50 mm / min at ambient conditions. In still further examples, the cross-linked material can have a tensile stress at break of greater than or equal to 35 MPa or greater than or equal to 40 MPa based on ASTM D638, Type 4 specimens, using a pull rate of 50 mm / min at ambient conditions.

[0066] In some additional examples, the cross-linked material can have an elongation at break of greater than or equal to 15% based on ASTM D638, Type 4 specimens, using a pulling speed of 50 mm / min under ambient conditions. In still other examples, the cross-linked material can have an elongation at break of greater than or equal to 20%, greater than or equal to 25%, or greater than or equal to 30% based on ASTM D638, Type 4 specimens, using a pulling speed of 50 mm / min under ambient conditions.

[0067] In some specific examples, the cross-linked material can be a 3D printed object. The 3D printed object can be formed by a variety of 3D printing methods. In some specific examples, the 3D printing method can be or can include digital light processing (DLP).

[0068] In some further examples, the 3D printed object may form at least a portion of a medical device. Non-limiting examples of medical devices may include orthodontic devices (e.g., dental braces, dental retainers, surgical guides, etc.), hearing devices (e.g., hearing aids, cochlear implants, etc.), orthopedic devices (e.g., stents, casts, cranial plates, prostheses, etc.). In some specific examples, the 3D printed object may be or may include a dental brace, a surgical guide, a hearing aid, or a cochlear implant.

[0069] Example

[0070] Materials used in the examples:

[0071] Diol A 3-Methyl-1,5-pentanediol (1,5-MPD)

[0072] Diol B 1,4-Butanediol (1,4-BDO)

[0073] Diol C 4,8-bis(hydroxymethyl)tricyclo[5.2.1.02,6]decane (DCPDM)

[0074] Diol D 1,9-nonanediol

[0075] Diol E DESMOPHEN C2202, commercially available from COVESTRO

[0076] Diol F DESMOPHEN PE225B, commercially available from COVESTRO

[0077] Diol G DESMOPHEN C1200, commercially available from COVESTRO

[0078] Diol H ARCOL PPG 2000, commercially available from COVESTRO

[0079] Diol I VELVETOL H2000, commercially available from ALLESSA

[0080] Diol J Poly(tetramethylene glycol) (PTMG) 1000

[0081] Diol K PTMG 2000

[0082] Diol L PTMG 2900

[0083] Acrylate A Hydroxyethyl Methacrylate (HEMA)

[0084] Acrylate B Hydroxyethyl acrylate (HEA)

[0085] Acrylate C PLACCEL FM1, commercially available from DAICEL

[0086] Acrylate D Isobornyl Methacrylate (IBOMA)

[0087] Acrylates E Isobornyl acrylate (IBOA)

[0088] Acrylate F Cyclohexyl Methacrylate (CHMA)

[0089] Acrylate G 4-tert-Butylcyclohexyl methacrylate (t-BuCHMA)

[0090] Isocyanate A Isophorone diisocyanate (IPDI)

[0091] Isocyanate B 4,4'-diisocyanatodicyclohexylmethane (H12 MDI)

[0092] Example 1 –Synthesis of UA prepolymer

[0093] Solid diol samples were heated in an oven at 60°C overnight before use. 10 wt% catalyst (e.g., dibutyltin dilaurate) ethyl acetate solution, 10 wt% phenothiazine ethyl acetate solution, and 5 wt% butylated hydroxytoluene (BHT) ethyl acetate solution were prepared for use in prepolymer synthesis. At room temperature, diols were mixed in ethyl acetate in a three-neck reactor equipped with a reflux condenser, a thermocouple, and a mechanical stirrer until a uniform solution was obtained. Catalyst (100 ppm) solution was added to the mixture. The stirring rate was set at 500 rpm and the reaction was covered with nitrogen. After raising the temperature to 60°C, diisocyanate was added dropwise to the reactor in about 15 minutes. The reactor was cooled using a dry ice bath to maintain a solution temperature below 70°C. After 1 hour, the NCO content was titrated compared to the NCO target. If the target was not reached, the reaction was continued for another 30 minutes until the target was reached. Then, phenothiazine (50 ppm) and additional catalyst (400 ppm) were added to the reactor. The hydroxy-functional (meth)acrylate is added to the solution over 15 minutes. The NCO content is titrated after 60 minutes and the reaction is stopped as soon as the NCO content reaches less than 0.2% by weight. The reaction is cooled to room temperature. Finally the NCO is titrated and BHT (100 ppm) is added to the solution. In the synthesis, the solvent can be replaced by a reactive diluent.

[0094] Table 1 - Soft segment prepolymers

[0095]

[0096] Table 2 - Hard Segment Prepolymers

[0097]

[0098] Example 2 -Membrane preparation and evaluation

[0099] All prepolymers were synthesized in 75 wt% ethyl acetate. The prepolymers were then mixed with reactive diluents in the amounts presented in Tables 3, 5, 7 and 9 using a high-speed mixer, and further mixed with a photoinitiator (3 wt% based on prepolymer solids) to prepare photocurable compositions. Each of these photocurable compositions was heated at 100°C for 50 s. -1The photocurable composition was cast into a 400 micron wet film and cured using a Liberty conveyor belt UV oven. UV curing conditions were 200 W / in 105 amps: 14 fpm (1530 mJ / cm 2 ) Double pass; post heat cure after drying under ambient conditions: 80, 100 and 125°C for 30 minutes each to remove residual volatiles.

[0100] The film samples were then cut into 4-type dog-bone samples using a die cutter. The tensile test was measured at 23°C and 50% RH based on ASTM D638. An Instron 5900R and a 10 kN load cell were used. The pulling speed was 50 mm / min.

[0101] As can be seen in Table 3, the hard segment prepolymer and reactive diluent were kept constant. Various types and / or amounts of soft segment prepolymers were combined with the hard segment prepolymers and reactive diluents to determine the effect on the mechanical properties of the crosslinked material. The results of the mechanical testing are seen in Table 4.

[0102] The soft segment prepolymers of the films 1-5 of the present invention are based on low Tg polyols with Mn>2000. These polyols are relatively hydrophobic (Hansen solubility parameter <18.9 MPa 1 / 2 Using the same hard segment prepolymer, the low Tg soft segment prepolymer exhibits the desired tensile properties (modulus > 900 MPa, tensile stress at break > 30 MPa, elongation at break > 15%, strain at yield > 5%).

[0103] Comparative films 1-5 contained less hydrophobic (Hansen solubility parameter > 18.9 MPa) 1 / 2 ) or a soft segment prepolymer with Mn < 2000 g / mol or Tg greater than -40°C. In addition, the cured films showed much lower tensile elongation at break and a yield point of < 5%, despite showing high modulus and tensile stress. In general, Comparative Films 1-5 were also more brittle. In Comparative Film 6, the prepolymer was synthesized using a mixture of two polyols, and the resulting film showed a yield point of < 5%, despite having good mechanical properties.

[0104] Table 3 - Variation of soft segment prepolymer

[0105]

[0106] Table 4 - Results of Varying the Soft Segment Prepolymer

[0107]

[0108]

[0109] As can be seen in Table 5, the inventive films 6-9 each comprise a different type of hard segment prepolymer and the same type of soft segment prepolymer. As can be seen in Table 6, the inventive films 6-9 exhibit similar tensile properties (modulus>1000 MPa, tensile stress>30 MPa, tensile elongation at break>15%, yield strain>5%).

[0110] In Comparative Films 7-8, a high Tg dimethacrylate crosslinker without urethane groups was used. Comparative Films 7-8 did not show the desired tensile properties. These examples clearly demonstrate the benefit of using a hard segment UA prepolymer.

[0111] Table 5 - Variation of Hard Segment Prepolymer

[0112]

[0113]

[0114] *PEAM 645 is a polyester acrylate / methacrylate from Design Molecules Inc

[0115] **DCP is tricyclodecane dimethanol dimethacrylate from Kowa

[0116] Table 6 - Results of Varying Hard Segment Prepolymers

[0117]

[0118] As can be seen in Table 7, various reactive diluents were combined with various hard segment prepolymers and soft segment prepolymers to determine the effect of the reactive diluent on mechanical properties. The results of the mechanical testing are seen in Table 8. From these results, it can be seen that although different high Tg reactive diluents were used in the formulation, the inventive films 10-12 exhibited similar desirable tensile properties.

[0119] Table 7 - Changing Reactive Diluents

[0120]

[0121] Table 8 - Results of varying reactive diluents

[0122]

[0123] Table 9 presents formulations of photocurable resins with various molecular weights to determine the effect of molecular weight on the mechanical properties of the crosslinked material. The results of the mechanical testing are presented in Table 10. As can be seen from these results, the inventive films 13-17 and 6 used hard segment and soft segment prepolymer structures, but these examples showed the desired tensile properties.

[0124] Table 9 - Changing Molecular Weight

[0125]

[0126] Table 10 - Results of varying molecular weight

[0127]

[0128]

[0129] Dynamic mechanical analysis (DMA) was performed on the films 6 and 13 of the present invention and comparative films 3, 4 and 6 at a heating ramp rate of 3°C / min and a frequency of 1 Hz to determine the Tg of the cured hard segment prepolymer network and the cured soft segment prepolymer network after curing the corresponding photocurable composition. Based on the loss modulus (E") peak in the DMA analysis, each of the films of the present invention showed two obvious Tg points of <-40°C and >100°C, respectively. Comparative films 3 and 4 generally showed higher soft segment and lower hard segment Tg. Comparative film 6 did not show obvious soft segment Tg and lower hard segment Tg, which may be attributed to more phase mixing in the cured resin when combining the two polyols in the synthesis.

[0130] Table 11 - DMA analysis

[0131] membrane Tg(soft segment) (℃) Tg(hard segment)(℃) Film 6 of the present invention -58 148 Film 13 of the present invention -50 133 Contrast 3 33 124 Contrast 4 -21 134 Contrast 6 NA 124

[0132] It should be understood that the above examples are only illustrative of some embodiments of the present invention. Without departing from the spirit and scope of the present invention, those skilled in the art may devise many modifications and alternative arrangements, and the appended claims are intended to cover such modifications and arrangements. Therefore, although the present invention has been specifically and in detail described above in conjunction with those currently considered to be the most practical and preferred embodiments of the present invention, it is apparent to those of ordinary skill in the art that changes may be made without departing from the principles and concepts set forth herein.

Claims

1. A photocurable composition, comprising: A photocurable resin, the photocurable resin comprising: A first prepolymer having a number average molecular weight of ≤2000 g / mol, the first prepolymer being the reaction product of a first reaction mixture, the first reaction mixture comprising: Cycloaliphatic diisocyanates, Hydroxy-functional (meth)acrylates, and an isocyanate-reactive component, and a second prepolymer having a number average molecular weight of 2000 g / mol to 10,000 g / mol and a Tg of less than -40°C, the second prepolymer being the reaction product of a second reaction mixture comprising: (Meth)acrylates, and With δ<18.9MPa 1 / 2 The Hansen solubility parameters of poly-active hydrogen compounds, and a reactive diluent comprising a (meth)acrylate monomer and / or a (meth)acrylate prepolymer; and Photoinitiator, The photocurable composition is subjected to a temperature of 100° C. for 50 seconds. -1 The shear viscosity is less than 1 Pa·s at a shear rate of . 2 . The photocurable composition of claim 1 , wherein the alicyclic diisocyanate of the first reaction mixture comprises isophorone diisocyanate.

3. The photocurable composition of claim 1, wherein the hydroxyl-functional (meth)acrylate of the first reaction mixture comprises a C4-C 10 Hydroxyalkyl (meth)acrylate.

4. The photocurable composition according to claim 1, wherein the isocyanate reactive component of the first reaction mixture comprises a C2-C 12 Aliphatic diols.

5. The photocurable composition according to claim 1, wherein the (meth)acrylate of the second reaction mixture comprises C4-C 10 Hydroxyalkyl (meth)acrylate.

6. The photocurable composition of claim 1, wherein the second reaction mixture further comprises a diisocyanate.

7. The photocurable composition according to claim 6, wherein the diisocyanate comprises an alicyclic diisocyanate.

8. The photocurable composition according to claim 1, wherein the reactive diluent comprises C 10 -C 18 (Meth)acrylate monomers. 9 . The photocurable composition of claim 1 , wherein the photocurable resin comprises 30 wt % to 50 wt % of the first prepolymer based on the total weight of the photocurable resin. 10 . The photocurable composition of claim 1 , wherein the photocurable resin comprises 25 to 30 wt % of the second prepolymer based on the total weight of the photocurable resin. 11 . The photocurable composition according to claim 1 , wherein the photocurable resin comprises 30 wt % to 40 wt % of the reactive diluent based on the total weight of the photocurable resin.

12. A cross-linked material, comprising: the photocurable composition according to claim 1, which forms a co-cross-linked polymer network after curing, wherein the co-cross-linked polymer network comprises a first polymer network having a first Tg and a second polymer network having a second Tg.

13. The cross-linked material of claim 12, wherein the first Tg is greater than 80°C.

14. The cross-linked material of claim 12, wherein the second Tg is less than -50°C.

15. The cross-linked material according to claim 12, wherein the cross-linked material has a transmittance % greater than or equal to 75% at room temperature using a film having a thickness of 0.3 mm based on ASTM D1003.

16. The cross-linked material of claim 12, wherein the cross-linked material is a 3D printed article.

17. The cross-linked material of claim 16, wherein the 3D printed article forms at least a portion of a medical device.

18. The cross-linked material of claim 17, wherein the medical device comprises an orthodontic device, a hearing device, or an orthopedic device.

19. A method for making a cross-linked material, the method comprising: The photocurable composition according to claim 1 is exposed to polymerizing electromagnetic radiation to form the crosslinked material.

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