Photocurable composition

Abstract

The photocurable composition may include a photocurable resin and a photoinitiator. The photocurable composition is typically heated at 100° C. for 50 s. -1 The polymerizable composition may have a shear viscosity of less than 1 Pa·s at a shear rate of 1000 .mu.m, and may typically comprise a first prepolymer, a second prepolymer, and a reactive diluent.

Description

[Background technology]

[0001] Photocurable resins based on multifunctional (meth)acrylate monomers are commonly applied as thin films (e.g., protective coatings, printing inks) and are also used to produce bulk objects such as dental fillings and 3D printed parts. Urethane (meth)acrylate (UA) prepolymers are particularly attractive for 3D printing applications due to their exceptional flexibility, toughness, abrasion resistance, and weather resistance. The addition of vinyl monomers reduces the viscosity of the resin, improves processability, and / or modifies the physical properties (e.g., heat resistance, weather resistance). Many factors affect the mechanical properties of crosslinked UA resin formulations, including, for example, (a) the ratio of hard and soft segments of 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 the toughness of the polymer while maintaining good thermal stability, which often requires increasing the glass transition temperature (Tg) of the cured polymer. Various approaches have been attempted to achieve these properties, but with 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 embodiment, the present disclosure describes a photocurable composition that may include a photocurable resin and a photoinitiator. The photocurable composition is typically heated at 100° C. for 50 s. -1 The polymerizable composition may have a shear viscosity of less than 1 Pa·s at a shear rate of 1000 .mu.m, and may typically comprise a first prepolymer, a second prepolymer, and a reactive diluent.

[0004] In another aspect, the present disclosure describes a crosslinked material that includes a photocurable composition after curing.

[0005] In yet another aspect, the present disclosure describes a method of producing a crosslinked 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 in order that the detailed description that follows may be better understood, and in order that the present contributions 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 when taken in conjunction with the appended claims, or may be learned by the practice of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Although the following detailed description contains many specifics for illustrative purposes, those skilled in the art will understand that many variations and modifications can be made to the following details and are considered to be included herein. Thus, the following embodiments are described without any loss of generality to, and without imposing limitations on, any claims set forth herein. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

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

[0009] In this application, the terms "comprises," "comprising," "containing," "having," and the like, may have the meanings given them in U.S. Patent Law and may mean "includes," "including," and the like, and are generally construed as open-ended terms. The terms "consisting of" or "consists of" are open-ended terms, as per U.S. Patent Law, and include only those components, structures, steps, and the like that are specifically recited in association with such term. "Consisting essentially of" or "consists essentially of" have the meanings generally given them by U.S. Patent Law. In particular, such terms, while generally open-ended terms, may include additional items, materials, components, steps, or elements that do not materially affect the basic novel characteristics or function of the item(s) with which they are used. For example, trace elements that are present in a composition but do not affect the properties or characteristics of the composition may be permitted under the phrase "consisting essentially of" even if they are not explicitly listed in the list of items following such terminology. When open-ended terms such as "comprising" or "including" are used herein, it is understood that direct support should be given to the phrase "consisting essentially of" as well as the phrase "consisting of" as if expressly stated, and vice versa.

[0010] As used herein and in the claims, the terms "first," "second," "third," "fourth," etc. are used to distinguish between similar elements and are not necessarily used to describe a particular sequence or chronological order. It should be understood that any terminology so used is interchangeable under appropriate circumstances, such that the embodiments described herein can operate in sequences other than those illustrated or otherwise described herein. Similarly, when a method is described herein as including a series of steps, the order of such steps presented herein is not necessarily the only order in which such steps can be performed, and certain of the specified steps may be omitted and / or certain other steps not described herein may be added to the method.

[0011] As used herein, the term "substantially" refers to the complete or nearly complete extent or degree of an action, attribute, property, state, structure, item, or result. For example, an object that is "substantially" surrounded would mean that the object is completely surrounded or nearly completely surrounded. The exact acceptable degree of deviation from absolute completeness may depend on the particular context. Generally speaking, however, closer to completeness would result in a similar overall result as would be obtained if absolute and total completeness were obtained. The use of "substantially" is equally applicable when used in a negative sense, referring to a complete or nearly complete absence of an action, attribute, property, state, structure, item, or result. For example, a composition that is "substantially free" of particles would either be completely devoid of particles or nearly completely devoid of particles to the extent that the effect is similar to that of a complete absence of particles. In other words, a composition that is "substantially free" of a component or element may still actually contain such an item, so long as there is no measurable effect thereof.

[0012] As used herein, the term "about" is used to provide flexibility to the endpoints of a numerical range by providing that a given value may be "a little above" or "a little below" the endpoint. Unless otherwise specified, the use of the term "about" in conjunction with a particular numerical value or numerical range should also be understood to support such numerical term or range without the term "about". For example, for convenience and simplicity, the numerical range "about 50 milligrams to about 80 milligrams" should also be understood to support the range "50 milligrams to 80 milligrams". Furthermore, in this specification, even when the term "about" is used in conjunction, it should be understood that the actual numerical value is supported. For example, a statement of "about" 30 should be interpreted as supporting not only a value slightly above 30 and a value slightly below 30, but also the actual numerical value of 30. Unless otherwise specified, all numerical parameters are to be understood in all instances to be preceded and modified by the term "about," taking into account the inherent variability of the underlying measuring technique being utilized to determine the numerical value of the parameter.

[0013] As used herein, for convenience, a plurality of items, structural elements, components, and / or materials may be presented in a common list. However, these lists should be construed as though each element of the list were individually identified as a separate and unique element. Thus, the individual elements of such lists should not be construed as being de facto equivalents to any other element of the same list solely based on their presentation in a common group, absent indication to the contrary.

[0014] Concentrations, amounts, and other numerical data may be expressed or presented in a range format herein. It is to be understood that such range formats are used merely for convenience and simplicity, and should be flexibly interpreted as if each numerical value and subrange were explicitly recited, to include not only the numerical values ​​explicitly recited as the limits of the range, but also all individual numerical values ​​or subranges contained within the range. By way of example, a numerical range of "1-5" should be interpreted to include not only the explicitly recited values ​​1-5, but also the individual values ​​and subranges within the indicated range. Thus, this numerical range includes individual values ​​such as 2, 3, and 4, and subranges such as 1-3, 2-4, and 3-5, as well as 1, 2, 3, 4, and 5 individually.

[0015] This same principle applies to ranges reciting only one numerical value as a minimum or maximum value, and such an interpretation should be applied regardless of the broadness of the range or characteristic being described.

[0016] References throughout this specification to "one example" mean that the particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment. Thus, the appearances of the phrase "in one example" in various places throughout this specification are not necessarily all referring to the same embodiment.

[0017] Embodiment Photocurable resin formulations can be used to manufacture complex objects, for example, by 3D printing. In the formulation, urethane (meth)acrylate (UA) prepolymers can contribute to the toughness (e.g., high tensile strength and elongation at break) of the photocured composition. Typically, UA prepolymers can be synthesized from multifunctional polyols, diisocyanates, and hydroxy-functional (meth)acrylates. Alternatively, UA prepolymers can be synthesized from multifunctional polyols and NCO-functional (meth)acrylates. Photocured UA prepolymers typically have a glass transition temperature (Tg) (e.g., lower than 50°C) that is related to the structure of the polyurethane soft segment. Combining reactive diluents (e.g., high Tg (meth)acrylate monomers) with UA prepolymers can provide tunable mechanical properties (e.g., modulus, elongation at break, etc.) and can adjust the working temperature to suit some demanding applications. One typical challenge with this approach is that when the reactive diluent content becomes the major component of the formulation (e.g., greater than 50 wt%), the toughness of the resin decreases rapidly due to a decrease in tensile elongation.

[0018] When UA prepolymers are synthesized using low molecular weight diols, the cured UA prepolymers often exhibit high Tg and high modulus, but insufficient tensile elongation at break. In some cases, this may be due to high crosslink density of polyurethane hard segments, 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 may lead to high viscosity that may be difficult to manage in many applications. Although this approach can strengthen compositions containing hard segment prepolymers, it often limits the improvement of resin toughness (e.g., tensile elongation at break).

[0019] In one embodiment, the present disclosure relates to a photocurable composition having a high Tg and manageable viscosity that can also provide good mechanical properties, and a method for making the same. The photocurable composition can include a blend of a first prepolymer having a high Tg after curing and a second prepolymer having a low Tg after curing, and the cured composition has a microphase separated structure. In some examples, the first prepolymer can have a melting point below 60°C. In some examples, the second prepolymer can have a Tg below -40°C. In some additional examples, the photocurable composition can further include a reactive diluent suitable as a solvent for both prepolymers.

[0020] Without wishing to be bound by theory, it is believed that the first prepolymer and reactive diluent can form a high Tg crosslinked network as the main continuous phase, which co-crosslinks with the low Tg rubber network formed by the second prepolymer and reactive diluent. The low Tg rubber network can microphase separate from the high Tg crosslinked network and affect the toughness of the cured photocurable composition without impacting the thermal stability of the main phase.

[0021] In contrast, when the high Tg network and the low Tg network are miscible in the cured state, the soft phase plasticizes the high Tg phase, resulting in good tensile strength and high transparency, but also a strong yield point and low tensile elongation at break. Conversely, when the high Tg network and the low Tg network are immiscible and macrophase separation occurs in the cured state, the cured composition may not have a yield point, but the mechanical properties and transparency may be impaired. Thus, the microphase-separated composition can achieve high modulus, yield point at strains of more than 5%, high tensile strength, and good transparency, while maintaining good thermal stability, due to the synergistic effect of the high Tg network and the low Tg network.

[0022] For example, in some cases, photocurable compositions having microphase-separated structures in the cured state can be obtained by polymerization-induced phase separation, which can be achieved by balancing the molecular weights of the first and second prepolymers to promote homogeneous mixing before curing, but the soft phase phase separates from the hard phase after curing due to the incompatibility of these phases in the polymerized prepolymer.

[0023] In addition, the miscibility between two polymer networks is typically temperature dependent, typically being more miscible at higher temperatures. Thus, considerations in the design of a suitable photocurable composition may include prepolymer structure, molecular weight, and equivalent miscibility at the intended photocuring temperature.

[0024] More specifically, in some examples, the photocurable composition can include a photocurable resin and a photoinitiator. The photocurable resin can typically include a first prepolymer, a second prepolymer, and a reactive diluent.

[0025] The first prepolymer can typically be present in the photocurable resin in an amount of 20% to 60% by weight, based on the total weight of the photocurable resin. In some additional examples, the first prepolymer can be present in the photocurable resin in an amount of 30% to 50% by weight, based on the total weight of the photocurable resin. In further additional examples, the first prepolymer can be present in the photocurable resin in an amount of 30% to 40% by weight, 35% to 45% by weight, or 40% to 50% by weight, based on the total weight of the photocurable resin.

[0026] The first prepolymer may typically have a number average molecular weight of 2000 g / mol or less as measured by gel permeation chromatography using a polystyrene retention time standard. Generally, gel permeation chromatography is used to determine all molecular weight values ​​disclosed herein, and in each example, a polystyrene retention time standard is used unless otherwise indicated. In some additional examples, the first prepolymer may have a number average molecular weight of 1800 g / mol or less. In yet further examples, the first prepolymer may have a number average molecular weight of 1500 g / mol or less. In some further examples, the first prepolymer may have a number average molecular weight of 1200 g / mol or less, 1100 g / mol or less, 1000 g / mol or less, or 900 g / mol or less.

[0027] The first prepolymer can typically be a reaction product of a first reaction mixture that includes a cycloaliphatic diisocyanate, an isocyanate-reactive component, and a hydroxy-functional (meth)acrylate. The first reaction mixture can include a variety of cycloaliphatic diisocyanates. Non-limiting examples of cycloaliphatic diisocyanates 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 cycloaliphatic diisocyanates of the first reaction mixture may include IPDI, HMDI, 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-hexahydrotoluylene diisocyanate, 2,6-hexahydrotoluylene diisocyanate, and the like, or combinations thereof. In some particular examples, the cycloaliphatic diisocyanate of the first reaction mixture may include IPDI, HMDI, 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-hexahydrotoluylene diisocyanate, 2,6-hexahydrotoluylene diisocyanate, and the like, or combinations thereof. 12In a further example, the cycloaliphatic diisocyanate of the first reaction mixture may include IPDI. In yet a further example, the cycloaliphatic diisocyanate of the first reaction mixture may include H 12 May include MDI.

[0028] In some examples, the first reaction mixture does not include any aromatic or aliphatic polyisocyanates other than the cycloaliphatic diisocyanate. In other examples, the first reaction mixture includes the cycloaliphatic diisocyanate in an amount of 80% to 100%, 90% to 100%, or 95% to 100% by weight, based on the total weight of all polyisocyanates present in the first reaction mixture.

[0029] The first reaction mixture can also include a variety of isocyanate-reactive components. As used herein, "isocyanate-reactive component" refers to a component that includes a hydroxyl group, an amino group, a thiol group, or a combination thereof. The isocyanate-reactive component can typically have a functionality of 2, or more than 2. Thus, the isocyanate-reactive component can be or include a variety of components, non-limiting examples of which include polyols (e.g., diols, triols, etc.), polyamines (e.g., diamines, triamines, etc.), polythiols (e.g., dithiols, trithiols, etc.), and the like, or combinations thereof. In some examples, the isocyanate-reactive component of the first reaction mixture can be a C2-C3 polyol, C4-C5 polyol, C6-C7 polyol, C7-C8 polyol, C8-C9 polyol, C9-C10 polyol, C11-C12 polyol, C12-C14 polyol, C13-C15 polyol, C14-C16 polyol, C15-C17 polyol, C16-C18 polyol, C17-C19 polyol, C18-C20 polyol, C19-C210 polyol, C19-C220 polyol, C19-C30 polyol, C19-C230 polyol, C19-C310 polyol, C19-C240 polyol, C19-C320 polyol, C19-C250 polyol, C19-C330 polyol, C19-C430 polyol, C19-C240 polyol, C19-C340 polyol, C19-C250 polyol, C19-C350 polyol, C20-C360 polyol, C20-C370 polyol, C20-C 12 In some further examples, the isocyanate-reactive component of the first reaction mixture may be or may include a linear or branched aliphatic polyol, polyamine, polythiol, or combination thereof; 10 Linear or branched aliphatic polyols, polyamines, polythiols, or combinations thereof; C6-C 12In some particular examples, the isocyanate-reactive component of the first reaction mixture may be or may include a linear or branched aliphatic polyol, a polyamine, a polythiol, or a combination thereof; or any mixture thereof. 12 In some further examples, the isocyanate-reactive component of the first reaction mixture may be or may include a linear or branched aliphatic polyol. 10 Linear or branched aliphatic polyols, C6-C 12The polyol may be or may include a linear or branched aliphatic polyol, or a combination thereof. Non-limiting examples of isocyanate-reactive components include ethylene glycol, 1,2-propanediol, 1,3-propanediol, glycerol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 2-methyl-1,4-butanediol, 3-methyl-1,3-butanediol, 1,2,4-butanetriol, 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 Tandiol, 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 polythiols, or combinations thereof. In some specific examples, the isocyanate-reactive component can be or can include 3-methyl-1,5-pentanediol.In some additional specific examples, the isocyanate-reactive component can be or include 1,4-butanediol. In some further specific examples, the isocyanate-reactive component can be or include DCPDM. And in some further specific examples, the isocyanate-reactive component can be or include 1,9-nonanediol.

[0030] The cycloaliphatic diisocyanate and the isocyanate-reactive component can generally be combined in the first reaction mixture at an NCO / OH value of 1.2 to 3.0. For simplicity, NCO / OH value is used throughout this disclosure, but it is noted that these descriptions are intended to equally describe NCO / NH or NCO / SH values, depending on the particular situation. In some additional examples, the cycloaliphatic diisocyanate and the isocyanate-reactive component can be combined in the first reaction mixture at an NCO / OH value of 1.3 to 2.3, 1.5 to 2.5, or 1.8 to 2.8. In some examples, the cycloaliphatic diisocyanate and the isocyanate-reactive component can be combined in the first reaction mixture before the hydroxy-functional (meth)acrylate is added to the first reaction mixture. In other examples, the cycloaliphatic diisocyanate, the isocyanate-reactive component, and the hydroxy-functional (meth)acrylate can be added simultaneously to the first reaction mixture.

[0031] The first reaction mixture can include a variety of hydroxy-functional (meth)acrylates. The term "(meth)acrylate" as used herein refers to an acrylate and / or the corresponding methacrylate. In some examples, the hydroxy-functional (meth)acrylates include those having a C4 to C6 hydroxyl group. 10 The hydroxy-functional (meth)acrylate may be or may include a hydroxyalkyl (meth)acrylate (i.e., a hydroxyalkyl (meth)acrylate containing a total of 4 to 10 carbon atoms). In some particular examples, the hydroxy-functional (meth)acrylate may be a C4 to C8 hydroxyalkyl (meth)acrylate and / or a C6 to C8 hydroxyalkyl (meth)acrylate. 10The hydroxy-functional (meth)acrylate may be or may include hydroxyalkyl (meth)acrylate. Non-limiting examples of hydroxy-functional (meth)acrylates may 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, and the like, or combinations thereof. In some specific examples, the hydroxy-functional (meth)acrylate of the first reaction mixture may be or may include hydroxyethyl acrylate and / or hydroxyethyl methacrylate. In some examples, the hydroxy-functional (meth)acrylate of the first reaction mixture may be or may include hydroxyethyl acrylate. In some examples, the hydroxy-functional (meth)acrylate of the first reaction mixture may be or may include hydroxyethyl methacrylate.

[0032] The second prepolymer can typically be present in the photocurable resin in an amount of 15% to 40% by weight, based on the total weight of the photocurable resin. In some additional examples, the second prepolymer can be present in the photocurable resin in an amount of 20% to 35% by weight, or 25% to 30% by weight, based on the total weight of the photocurable resin. In further additional examples, the second prepolymer can be present in the photocurable resin in an amount of 15% to 25% by weight, 20% to 30% by weight, or 25% to 35% by weight, based on the total weight of the photocurable resin.

[0033] The second prepolymer of the photocurable resin can typically have a number average molecular weight of 2000 g / mol to 10000 g / mol as determined by gel permeation chromatography using polystyrene retention time standards. In some additional examples, the second prepolymer can have a number average molecular weight of 3000 g / mol to 8000 g / mol. In yet further examples, the second prepolymer can have a number average molecular weight of 2500 g / mol to 5000 g / mol. In some further examples, the second prepolymer can have a number average molecular weight of 2000 g / mol to 4000 g / mol, 2500 g / mol to 3500 g / mol, or 3000 g / mol to 6000 g / mol.

[0034] The second prepolymer can be a reaction product of a second reaction mixture comprising a (meth)acrylate and a multi-active hydrogen compound. The photocurable resin can include a variety of second prepolymers. As non-limiting examples, the second prepolymer can be or include a di(meth)acrylate-functionalized multi-active hydrogen compound (e.g., illustratively HEMA-PTMG-HEMA); a reaction product of a second reaction mixture comprising an isocyanate-terminated (meth)acrylate and a multi-active hydrogen compound; a reaction product of a second reaction mixture comprising a diisocyanate, a hydroxy-functional (meth)acrylate, and a multi-active hydrogen compound; or a combination thereof.

[0035] The second reaction mixture can include a variety of (meth)acrylates. In some examples, the (meth)acrylates of the second reaction mixture can be or include isocyanate-terminated (meth)acrylates. In some additional examples, the (meth)acrylates of the second reaction mixture can be hydroxy-functional (meth)acrylates. In some examples, the (meth)acrylates of the second reaction mixture can be C4-C 10 In some particular examples, the (meth)acrylate of the second reaction mixture may be or may include a hydroxyalkyl (meth)acrylate. 10The hydroxy-functional (meth)acrylate may be or may include hydroxyalkyl (meth)acrylate. Non-limiting examples of hydroxy-functional (meth)acrylates may 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, and the like, or combinations thereof. In some specific examples, the hydroxy-functional (meth)acrylate of the second reaction mixture may be or may include hydroxyethyl acrylate and / or hydroxyethyl methacrylate. In some examples, the hydroxy-functional (meth)acrylate of the second reaction mixture may be or may include hydroxyethyl acrylate. In some examples, the hydroxy-functional (meth)acrylate of the second reaction mixture may be or may include hydroxyethyl methacrylate.

[0036] The second reaction mixture can also contain various multi-active hydrogen compounds. As used herein, "multi-active hydrogen compounds" refers to any compound that contains multiple Zerewitinoff active hydrogen atoms. "Zerwitinoff active hydrogen" is referred to herein as an acidic hydrogen atom or active hydrogen atom that can be identified using known Zerewitinoff measurements (e.g., by reactivity with the corresponding Grignard reagent). In some specific examples, the multi-active hydrogen compounds can be or include polyols (e.g., diols, triols, etc.), polyamines (e.g., diamines, triamines, etc.), polythiols (e.g., dithiols, trithiols, etc.), or combinations thereof.

[0037] In some examples, the multi-active hydrogen compound may have a number average molecular weight of 1000 g / mol to 5000 g / mol as determined by gel permeation chromatography using polystyrene retention time standards. In some additional examples, the multi-active 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 multi-active 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.

[0038] In some examples, the polyactive hydrogen compound has a viscosity of 18.9 MPa. 1 / 2 In some additional examples, the polyactive hydrogen compound may have a Hansen solubility parameter δ of less than 16 MPa. 1 / 2 Larger than 18.9MPa 1 / 2 Hansen describes the total 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 defines a 3D solubility diagram (δD, δP, δH) that can define a solubility sphere range with radius R0 for large molecules. Analysis of polymer HSP can be determined using a sphere that includes good solvents of the components in its space based on solubility testing in solvents of known HSP, as described in Appendix A of Hansen Solubility Parameters, A User Guidebook, 2007, CRC Press. For example, based on the solubility testing described, the total δ of Desmophen 1200 is 21.6 MPa. 1 / 2 and the total δ of PTMG is 17.6 MPa. 1 / 2and the total δ of the PPG is 18.9 MPa. 1 / 2 It was required that.

[0039] In some additional examples, the second reaction mixture can include a diisocyanate. When the second reaction mixture includes a diisocyanate, the diisocyanate can generally include a cycloaliphatic diisocyanate, an aromatic diisocyanate, or a combination thereof. In some examples, the diisocyanate of the second reaction mixture can be or can include a cycloaliphatic diisocyanate. In this case, the cycloaliphatic diisocyanate can be cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyanato-2-isocyanatomethylcyclopentane, IPDI, H 12 In some particular examples, the cycloaliphatic diisocyanate of the second reaction mixture may be or may include IPDI, 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-hexahydrotoluylene diisocyanate, 2,6-hexahydrotoluylene diisocyanate, and the like, or combinations thereof. 12 In a further example, the cycloaliphatic diisocyanate of the second reaction mixture may include IPDI. In yet a further example, the cycloaliphatic diisocyanate of the second reaction mixture may include H 12It may include MDI. 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 mixtures thereof, etc.), toluene diisocyanate (TDI) (e.g., 2,4-TDI, 2,6-TDI, or mixtures thereof, etc.), or combinations thereof. In some examples, the aromatic diisocyanate of the second reaction mixture may be or may include MDI.

[0040] When the second reaction mixture includes a diisocyanate, the diisocyanate and the multi-active hydrogen compound can generally be combined in the second reaction mixture at an NCO / OH value of 1.2 to 3.0. In some additional examples, the diisocyanate and the multi-active hydrogen compound can be combined in the second reaction mixture at an NCO / OH value 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 multi-active hydrogen compound can be combined in the second reaction mixture at an NCO / OH value of 2.

[0041] The photocurable resin may also include a reactive diluent. The reactive diluent may typically be present in the photocurable resin in an amount of 20% to 65% by weight based on the total weight of the photocurable resin. In some additional examples, the reactive diluent may be present in the photocurable resin in an amount of 30% to 50% by weight or 40% to 60% by weight based on the total weight of the photocurable resin. In further additional examples, the reactive diluent may be present in the photocurable resin in an amount of 25% to 35% by weight, 35% to 45% by weight, or 40% to 50% by weight based on the total weight of the photocurable resin.

[0042] Various reactive diluents can be included in the photocurable resin. In some examples, the reactive diluent is 10 ~C 18 It may be or may include a (meth)acrylate monomer.10 ~C 18 Non-limiting examples of (meth)acrylate monomers 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-decahydronaphthyl methacrylate, 1-adamantyl acrylate, 1-adamantyl methacrylate, 2-ethylhexyl methacrylate, 3-tricyclo[4.4.0.1.1]dodecyl methacrylate, tetrahydrofurfuryl methacrylate, 2-phenoxyethyl methacrylate, N-vinylpyrrolidone, carboxyethyl acrylate, acryloylmorpholine, and the like, or combinations thereof.

[0043] In addition to the photocurable resin, the photocurable composition may also include a photoinitiator. The photocurable composition may include a variety of photoinitiators. Non-limiting examples include BASF's IRGACURE and DAROCUR, such as 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184), 2,2-dimethoxy-1,2-diphenylethan-1-one (IRGACURE 651), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (IRGACURE 819), 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one (IRGACURE 2959), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone (IRGACURE 369), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (IRGACURE 370), and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (IRGACURE 372). 907), oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propane] (ESACURE ONE), 2-hydroxy-2-methyl-1-phenylpropan-1-one (DAROCUR 1173), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (IRGACURE TPO), and 2,4,6-trimethylbenzoylphenylphosphinate (IRGACURE TPO-L), or the like, or combinations thereof. Additional non-limiting examples of photoinitiators include benzil dimethyl ketal, 2-methyl-2-hydroxypropiophenone, benzoin methyl ether, benzoin isopropyl ether, anisoin methyl ether, aromatic sulfonyl chlorides, photoactive oximes, or the like, or combinations thereof.

[0044] 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, and the like, or combinations thereof. In some specific examples, the photocurable composition may include a colorant. The type of colorant is not particularly limited, and any suitable colorant (e.g., dyes, pigments, and the like, or combinations thereof) may be used in the photocurable composition. In some additional specific examples, the photocurable composition may include an impact modifier. The type of impact modifier is not particularly limited, and any suitable impact modifier (e.g., liquid rubber, core-shell rubber particles, and the like, or combinations thereof) may be used in the photocurable composition.

[0045] The photocurable composition may have various viscosities depending on the application. Typically, the photocurable composition is heated at 100° C. for 50 s. -1 In some additional examples, the photocurable composition may have a shear viscosity of less than 1 Pa·s at a shear rate of 80° C., 50 s -1 In yet an additional example, the photocurable composition may have a shear viscosity of less than 1 Pa·s at a shear rate of 70° C., 50 s -1 The shear viscosity may be less than 1 Pa·s at a shear rate of

[0046] The present disclosure also describes a method for preparing 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.

[0047] The first prepolymer can be prepared in a variety of ways. In some examples, the first prepolymer can be prepared by combining a cycloaliphatic diisocyanate and an isocyanate-reactive component to form a first product. Typically, the isocyanate-reactive component can be added gradually to the cycloaliphatic diisocyanate to minimize exotherm and narrow the molecular weight distribution. The first product can be combined with a hydroxy-functional (meth)acrylate to form the first prepolymer. In other examples, the first prepolymer can be prepared by combining a cycloaliphatic diisocyanate with a hydroxy-functional (meth)acrylate to form an isocyanate-terminated (meth)acrylate. The isocyanate-terminated (meth)acrylate can then be combined with the isocyanate-reactive component to form the first prepolymer.

[0048] The second prepolymer can also be prepared in a variety of ways. In some examples, the second prepolymer can be prepared by combining a (meth)acrylate and a multi-active hydrogen compound under conditions suitable to form a di(meth)acrylate-functionalized multi-active hydrogen compound (e.g., HEMA-PTMG-HEMA, etc.). In other examples, the second prepolymer can be prepared by combining a diisocyanate with a (meth)acrylate to form an isocyanate-terminated (meth)acrylate. The isocyanate-terminated (meth)acrylate can be combined with a multi-active hydrogen compound to form the second prepolymer. In yet further examples, the second prepolymer can be formed by combining a diisocyanate with a multi-active hydrogen compound to form a second product. Typically, the multi-active hydrogen compound can be added slowly to the diisocyanate to minimize exotherms. The second product can be combined with a (meth)acrylate to form the second prepolymer.

[0049] The first prepolymer and the second prepolymer can typically be intimately mixed with a reactive diluent to form a photocurable resin. A photoinitiator can be added to the photocurable resin to form a photocurable composition. Prior to photocuring, the photocurable composition can be optionally heated to a temperature suitable for photocuring. In other examples where photocuring is intended to occur at or below ambient temperature, heating may not be required. In some examples, the prepolymers may become more miscible as the temperature increases.

[0050] The present disclosure also describes crosslinked materials prepared by curing the photocurable compositions and methods of making the same. More specifically, the photocurable compositions can be exposed to suitable electromagnetic radiation to at least partially crosslink the photocurable compositions to form at least a portion of the crosslinked material.

[0051] In some examples, the crosslinked material may have a transparent or translucent appearance. In some specific examples, the crosslinked material may have a transparency or percent transmittance of 75% or greater at room temperature based on ASTM D1003 using a film having a thickness of 0.3 mm. In other examples, the crosslinked material may have a transparency or percent transmittance of 80% or greater at room temperature. In yet additional examples, the crosslinked material may have a transparency or percent transmittance of 85% or greater at room temperature.

[0052] The present disclosure also describes a method for producing a crosslinked material. In some examples, the method may include applying (e.g., casting, coating, painting, rolling, dipping, spraying, depositing, etc.) the photocurable composition described herein onto 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 crosslinked material on the substrate, or in other words, a coated substrate including a coating of the crosslinked material.

[0053] In some additional examples, the method of producing the crosslinked material may be or include an additive manufacturing method. Additive manufacturing refers to a method of producing a product based on a 3D object model (e.g., a CAD model, etc.) by adding materials together, typically layer by layer, for example, by depositing materials, bonding materials, solidifying materials, or a combination thereof. In some specific examples, the additive manufacturing method may be or include stereolithography, digital light processing, continuous liquid interface manufacturing, etc. Other suitable additive manufacturing methods may also be used. In addition, other suitable non-additive manufacturing methods may be used to prepare the crosslinked material.

[0054] Photocurable compositions are typically cured at 100°C for 50s. -1 The photocurable composition may have a shear viscosity of less than 1 Pa·s at a shear rate of 100° C. Thus, for coatings and additive manufacturing methods using photopolymerization, the photocurable compositions described herein can be applied as films / coatings or printed as 2D or 3D objects at relatively low temperatures. For example, in some cases, the photocurable composition can be applied or printed at a temperature of less than 100° C. In further additional examples, the photocurable composition can 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 can be applied or printed at a temperature of 20° C. to 100° C. In some additional examples, the photocurable composition can be applied or printed at a temperature of 20° C. to 60° C. or 20° C. to 40° C.

[0055] Additionally, in some cases, curing (e.g., exposure to electromagnetic radiation sufficient to induce photopolymerization) can also occur at relatively low temperatures. In some specific examples (e.g., in DLP printing, etc.), curing and printing can occur in the same step. In other examples, coating / printing and curing can occur sequentially (e.g., applying a coating to a substrate and then curing the coating to form a coated substrate). In some examples, curing can occur at a temperature below 100°C. In further additional examples, curing can occur at a temperature below 90°C, below 80°C, below 70°C, below 60°C, or below 50°C. In some specific examples, curing can occur at a temperature between 20°C and 100°C. In some additional examples, curing can occur at a temperature between 20°C and 60°C or between 20°C and 40°C.

[0056] In some examples, the manufacturing method can include introducing the photocurable composition into a container. The container can be positioned such that the photocurable composition can fully contact or cover a substrate or build platform. The portion of the substrate or build platform that is contacted or covered by the photocurable composition can depend on the direction(s) from which the photocurable composition is exposed to polymerizing electromagnetic radiation.

[0057] As used herein, "electromagnetic radiation for polymerization" can include any type of electromagnetic radiation suitable for promoting or inducing photopolymerization of a photocurable composition. In some examples, the electromagnetic radiation for polymerization can be or include ultraviolet electromagnetic radiation (e.g., electromagnetic radiation having a wavelength of 10 nm to 400 nm). In some examples, the electromagnetic radiation for polymerization can be or include visible electromagnetic radiation (e.g., electromagnetic radiation having a wavelength of 380 nm to 750 nm). In some examples, the electromagnetic radiation for polymerization can be or include infrared electromagnetic radiation (e.g., electromagnetic radiation having a wavelength of 700 nm to 1 mm).

[0058] The polymerizing electromagnetic radiation can be applied to the photocurable composition for a suitable amount of time to photopolymerize the photocurable composition to form a crosslinked material, the amount of time can 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 can be applied to the photocurable composition multiple times, such as multiple times for a single layer, or one or more times for each of multiple layers or segments, or a combination thereof, to form a crosslinked material.

[0059] When applying the photocurable composition by additive manufacturing, the photocurable composition can be printed based on a 3D object model to form a 3D crosslinked material. For example, based on a 3D object model for a crosslinked material, the photocurable composition can be applied to a build platform and selectively exposed to electromagnetic radiation for polymerization to form a crosslinked interface layer that connects with the build platform. Based on the 3D object model, additional photocurable composition can be applied to the interface layer (and / or additional crosslinked layer) and selectively exposed to electromagnetic radiation for polymerization to form one or more additional crosslinked layers until the 3D object is completed based on the 3D object model. In some examples, applying additional photocurable composition to the interface layer and / or additional crosslinked layer(s) can include moving the build platform a distance of 1 μm to 2000 μm to apply additional photocurable composition to the crosslinked interface layer and / or additional crosslinked layer(s). In some examples, applying the additional photocurable composition to the interface layer and / or the additional crosslinked layer(s) can include depositing the photocurable composition onto the interface layer and / or the additional crosslinked layer(s) with or without moving the build platform.

[0060] The photocurable composition can be cured to form a crosslinked material comprising a co-crosslinked polymer network comprising a first polymer network having a first Tg and a second polymer network having a second Tg. The first polymer network can comprise a crosslinked first prepolymer and a reactive diluent. The first Tg can typically be greater than 80° C. based on dynamic mechanical analysis with a heating ramp of 3° C. / min and a frequency of 1 Hz as the loss modulus (E″) peak. In yet additional examples, the first Tg can be greater than 100° C. or greater than 120° C. based on dynamic mechanical analysis with a heating ramp of 3° C. / min and a frequency of 1 Hz as the loss modulus (E″) peak.

[0061] The second polymer network can include a crosslinked second prepolymer and a reactive diluent. The second Tg can typically be less than -40°C based on dynamic mechanical analysis with a 3°C / min heat ramp and 1 Hz frequency for the loss modulus (E'') peak. In yet additional examples, the second Tg can be less than -50°C or less than -60°C based on dynamic mechanical analysis with a 3°C / min heat ramp and 1 Hz frequency for the loss modulus (E'') peak.

[0062] The cross-linked material may have a variety of mechanical properties. In some examples, the cross-linked material may have a yield strain of 5% or greater based on tensile testing ASTM D638, Type 4 specimens using a tensile speed of 50 mm / min under ambient conditions. In further additional examples, the cross-linked material may have a yield strain of 6% or greater or 8% or greater based on tensile testing ASTM D638, Type 4 specimens using a tensile speed of 50 mm / min under ambient conditions.

[0063] In some additional examples, the crosslinked material can have an elastic modulus of 900 MPa or greater based on ASTM D638, Type 4 specimens using a tensile speed of 50 mm / min under ambient conditions. In still additional examples, the crosslinked material can have an elastic modulus of 1000 MPa or greater, 1200 MPa or greater, or 1500 MPa or greater based on ASTM D638, Type 4 specimens using a tensile speed of 50 mm / min under ambient conditions.

[0064] In some further examples, the crosslinked material may have a tensile stress at break of 30 MPa or greater based on ASTM D638, Type 4 specimens using a tensile speed of 50 mm / min under ambient conditions. In still further examples, the crosslinked material may have a tensile stress at break of 35 MPa or greater or 40 MPa or greater based on ASTM D638, Type 4 specimens using a tensile speed of 50 mm / min under ambient conditions.

[0065] In some additional examples, the crosslinked material can have an elongation at break of 15% or greater based on ASTM D638, Type 4 specimens using a tensile speed of 50 mm / min under ambient conditions. In still further examples, the crosslinked material can have an elongation at break of 20% or greater, 25% or greater, or 30% or greater based on ASTM D638, Type 4 specimens using a tensile speed of 50 mm / min under ambient conditions.

[0066] 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).

[0067] In some further examples, the 3D printed object can form at least a portion of a medical device. Non-limiting examples of medical devices can include orthodontic appliances (e.g., dental aligners, dental retainers, surgical guides, etc.), hearing appliances (e.g., hearing aids, cochlear implants, etc.), orthopedic appliances (e.g., braces, casts, skull plates, prosthetic devices, etc.). In some specific examples, the 3D printed object can be or can include a dental aligner, a surgical guide, a hearing aid, or a cochlear implant. EXAMPLES

[0068] Materials used in the examples: Diol A 3-Methyl-1,5-pentanediol (1,5-MPD) Diol B 1,4-butanediol (1,4-BDO) Diol C 4,8-bis(hydroxymethyl)tricyclo[5.2.1.02,6]decane (DCPDM) Diol D 1,9-nonanediol DESMOPHEN C2202 commercially available from Diol E COVESTRO Diol F DESMOPHEN PE225B available from COVESTRO Diol G DESMOPHEN C1200 available from COVESTRO Diol H ARCOL PPG 2000 commercially available from COVESTRO VELVETOL H2000 available from Diol I ALLESSA Diol J Poly(tetrahydrofuran) (PTMG) 1000 Diol K PTMG 2000 Diol L PTMG 2900 Acrylate A Hydroxyethyl Methacrylate (HEMA) Acrylate B Hydroxyethyl acrylate (HEA) Acrylate C PLACCEL FM1 available from DAICEL Acrylate D Isobornyl methacrylate (IBOMA) Acrylate E Isobornyl acrylate (IBOA) Acrylate F Cyclohexyl methacrylate (CHMA) Acrylate G 4-tert-Butylcyclohexyl methacrylate (t-BuCHMA) Isocyanate A Isophorone diisocyanate (IPDI) Isocyanate B 4,4'-Diisocyanatodicyclohexylmethane (H 12 MDI)

[0069] Example 1 - Synthesis of UA Prepolymer Solid diol samples were heated overnight in a 60°C oven before use. A 10 wt% catalyst (e.g., dibutyltin dilaurate) solution in ethyl acetate, a 10 wt% phenothiozine solution in ethyl acetate, and a 5 wt% butylated hydroxytoluene (BHT) solution in ethyl acetate were prepared for use in prepolymer synthesis, respectively. At room temperature, the diol was mixed in ethyl acetate in a three-neck reactor equipped with a reflux condenser, thermocouple, and mechanical stirrer until a homogenous solution was achieved. The catalyst (100 ppm) solution was added to the mixture. The stirring speed was set at 500 rpm, and the reaction was gassed with nitrogen. After the temperature was increased to 60°C, the diisocyanate was added dropwise into the reactor within approximately 15 minutes. A dry ice bath was used to cool the reactor and maintain the solution temperature below 70°C. After 1 hour, the NCO content was titrated against the NCO target. If the target was not achieved, the reaction was continued for an additional 30 minutes until the target was reached. Then, phenothiozine (50 ppm) and additional catalyst (400 ppm) were added into the reactor. Hydroxy-functional (meth)acrylate was added into the solution within 15 minutes. After 60 minutes, the NCO content was titrated and the reaction was stopped when the NCO content reached less than 0.2 wt%. The reaction was cooled to room temperature. Finally, the NCO was titrated and BHT (100 ppm) was added into the solution. In the synthesis, the solvent can be replaced by a reactive diluent.

[0070] TIFF2024546263000001.tif109170

[0071] TIFF2024546263000002.tif64170

[0072] Example 2 - Film preparation and evaluation All prepolymers were synthesized at 75 wt% in ethyl acetate. The prepolymers were then mixed with reactive diluents in the amounts shown in Tables 3, 5, 7, and 9, and further mixed with photoinitiator (3 wt% based on prepolymer solids) using a speed mixer to prepare the photocurable compositions. The photocurable compositions were each heated at 100°C for 50 s. -1 The photocurable composition was cast into a 400 micron wet film and cured using a Liberty conveyor UV oven. The UV cure conditions were 200 W at 105 amps: 14 fpm (1530 mJ / cm2). 2 ) Double pass, post heat curing after drying for 30 minutes each under ambient conditions: 80°C, 100°C and 125°C to remove residual volatiles.

[0073] The film samples were then cut into type 4 dog-bone specimens using a die cutter. Tensile tests were performed according to ASTM D638 at 23°C and 50% RH. An Instron 5900R with a 10 kN load cell was used. The tensile speed was 50 mm / min.

[0074] The hard segment prepolymer and reactive diluent were held constant, as can be seen in Table 3. Varying types and / or amounts of soft segment prepolymers were combined with the hard segment prepolymer and reactive diluent to determine the effect on the mechanical properties of the crosslinked material. The results of the mechanical testing can be seen in Table 4.

[0075] The soft segment prepolymers of the inventive films 1-5 are based on low Tg polyols with Mn >2000. These polyols are relatively hydrophobic (Hansen solubility parameters of 18.9 MPa 1 / 2 When the same hard segment prepolymer is used, the low Tg soft segment prepolymer exhibits desirable tensile properties (modulus greater than 900 MPa, tensile stress at break greater than 30 MPa, elongation at break greater than 15%, and yield strain greater than 5%).

[0076] Comparative films 1 to 5 have low hydrophobicity (Hansen solubility parameter of 18.9 MPa 1 / 2 The cured films contain soft segment prepolymers with a Mn of greater than 2000 g / mol or a Tg of greater than -40°C. In addition, the cured films exhibit fairly low tensile elongation at break and a yield point of less than 5%, despite exhibiting high modulus and tensile stress. In general, Comparative Films 1-5 are also more brittle. For Comparative Film 6, a mixture of two polyols was used to synthesize the prepolymer, and the resulting film exhibits a yield point of less than 5%, despite good mechanical properties.

[0077] TIFF2024546263000003.tif88170

[0078] TIFF2024546263000004.tif95170

[0079] As can be seen in Table 5, inventive films 6-9 each contain a different type of hard segment prepolymer in combination with the same type of soft segment prepolymer. As can be seen in Table 6, inventive films 6-9 exhibit similar tensile properties (modulus of elasticity greater than 1000 MPa, tensile stress greater than 30 MPa, tensile elongation at break greater than 15%, and yield strain greater than 5%).

[0080] Comparative Films 7 and 8 used a high Tg dimethacrylate crosslinker that does not contain urethane groups. Comparative Films 7 and 8 do not exhibit the desired tensile properties. These examples clearly show the advantage of using a hard segment UA prepolymer.

[0081] TIFF2024546263000005.tif83170

[0082] TIFF2024546263000006.tif52170

[0083] Various reactive diluents were combined with various hard segment and soft segment prepolymers to determine the effect of the reactive diluents on mechanical properties, as seen in Table 7. The results of the mechanical testing can be seen in Table 8. As can be seen from the results, inventive films 10-12 exhibited similar desirable tensile properties when different high Tg reactive diluents were used in the formulation.

[0084] TIFF2024546263000007.tif47170

[0085] TIFF2024546263000008.tif33170

[0086] Table 9 shows the formulation 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 mechanical testing are shown in Table 10. As can be seen from the results, inventive films 13-17 and 6 used various hard and soft segment prepolymer structures, yet these examples exhibited desirable tensile properties.

[0087] TIFF2024546263000009.tif74170

[0088] TIFF2024546263000010.tif55170

[0089] Dynamic mechanical analysis (DMA) was performed on inventive films 6 and 13 and comparative films 3, 4 and 6 at a heat ramp 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 each photocurable composition. Each of the inventive films shows two distinct Tg points, below −40° C. and above 100° C., respectively, based on the loss modulus (E″) peak in the DMA analysis. Comparative films 3 and 4 generally showed higher soft segment Tg and lower hard segment Tg. Comparative film 6 does not show distinct soft segment Tg and lower hard segment Tg, likely due to more phase mixing in the cured resin when two polyols are combined in the synthesis.

[0090] TIFF2024546263000011.tif41170

[0091] It should be understood that the above examples are merely illustrative of some embodiments of the present invention. Those skilled in the art may devise numerous modifications and alternative configurations without departing from the spirit and scope of the present invention, and the appended claims are intended to cover such modifications and configurations. Thus, while the present invention has been described with specificity and detail in connection with what are presently considered to be the most practical and preferred embodiments of the present invention, it will be apparent to those skilled in the art that changes can be made without departing from the principles and concepts set forth herein.

Claims

1. 1. A photocurable composition comprising: A photocurable resin, A first prepolymer having a number average molecular weight of 2000 g / mol or less, an alicyclic diisocyanate; a hydroxy-functional (meth)acrylate; an isocyanate-reactive component; a first prepolymer which is the reaction product of a first reaction mixture comprising: a second prepolymer having a number average molecular weight of 2000 g / mol to 10000 g / mol, (meth)acrylate, A polyactive hydrogen compound; wherein the polyactive hydrogen compound of the second reaction mixture is a reaction product of the second reaction mixture comprising １／２ a second prepolymer having a Hansen solubility parameter δ less than a reactive diluent comprising a (meth)acrylate monomer and / or a (meth)acrylate prepolymer; A photocurable resin comprising: A photoinitiator; Including, 100°C, 50s －１ The photocurable composition has a shear viscosity of less than 1 Pa·s at a shear rate of 100° C.

2. 2. The photocurable composition of claim 1, wherein the cycloaliphatic diisocyanate of the first reaction mixture comprises isophorone diisocyanate.

3. The hydroxy-functional (meth)acrylate of the first reaction mixture is ４ ~C １０ The photocurable composition of claim 1 comprising a hydroxyalkyl (meth)acrylate.

4. The isocyanate-reactive component of the first reaction mixture is ２ ~C １２ The photocurable composition of claim 1 comprising an aliphatic diol.

5. The (meth)acrylate of the second reaction mixture is ４ ~C １０ The photocurable composition of claim 1 comprising a hydroxyalkyl (meth)acrylate.

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

7. The photocurable composition of claim 6 , wherein the diisocyanate comprises a cycloaliphatic diisocyanate.

8. The polyactive hydrogen compound of the second reaction mixture is heated to 16 MPa １／２ Larger than 18.9MPa １／２ 2. The photocurable composition of claim 1 having a smaller Hansen solubility parameter δ.

9. The reactive diluent is C １０ ~C １８ The photocurable composition of claim 1 comprising a (meth)acrylate monomer.

10. 2. The photocurable composition of claim 1, wherein the photocurable resin comprises 30% to 50% by weight of the first prepolymer, based on the total weight of the photocurable resin.

11. 2. The photocurable composition of claim 1, wherein the photocurable resin comprises 25% to 30% by weight of the second prepolymer, based on the total weight of the photocurable resin.

12. 2. The photocurable composition of claim 1, wherein the photocurable resin comprises 30% to 40% by weight of the reactive diluent, based on the total weight of the photocurable resin.

13. 10. A crosslinked material comprising the photocurable composition of claim 1 that upon curing forms a co-crosslinked polymer network comprising a first polymer network having a first Tg and a second polymer network having a second Tg.

14. 14. The crosslinked material of claim 13, wherein the first Tg is greater than 80°C.

15. 14. The crosslinked material of claim 13, wherein said second Tg is less than -40°C.

16. 14. The crosslinked material of claim 13, having a % transmittance of 75% or greater at room temperature based on ASTM D1003 using a 0.3 mm thick film.

17. 14. The crosslinked material of claim 13, which is a 3D printed article.

18. 20. The crosslinked material of claim 17, wherein the 3D printed article forms at least a portion of a medical device.

19. 20. The crosslinked material of claim 18, wherein the medical device is an orthodontic appliance, a hearing appliance, or an orthopedic appliance.

20. 13. A method for producing a crosslinked material comprising the step of exposing the photocurable composition of claim 1 to polymerizing electromagnetic radiation to form a crosslinked material.

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