Ultraviolet-curable silicone composition for stereolithography and cured product thereof

Abstract

Provided is a UV-curable silicone composition for photoforming, comprising: (A) an organopolysiloxane having two groups represented by the following formula (1) in one molecule (where R... 1 R represents a monovalent hydrocarbon group. 2 R represents an oxygen atom or an alkylene group. 3 (a) represents acryloyloxyalkyl, methacryloyloxyalkyl, acryloyloxyalkoxy, methacryloyloxyalkoxy, (acryloyloxyalkyl)dimethylsilyloxy, or (methacryloyloxyalkyl)dimethylsilyloxy, where p represents a number satisfying 0≤p≤10 and a represents a number satisfying 1≤a≤3; (B) hydrophobic silica particles with an average particle size of 10–1000 nm and a hydrophobicity of 60% or more obtained by methanol titration; and (C) photopolymerization initiator.

Description

Technical Field

[0001] This invention relates to ultraviolet-curable silicone compositions for photoforming and their cured products. Background Technology

[0002] In recent years, the development of shaping materials used in 3D printers has been on the rise, with various materials used, ranging from metals to resins. In the field of resins, examples include acrylate-based photocurable resin compositions and urethane acrylate-based photocurable resin compositions. The cured products of these resin compositions are very hard and cannot be bent freely (Patent Document 1).

[0003] Depending on the application, the need for flexible silicone materials is gradually increasing, and silicone materials for 3D printers that are compatible with shaping methods have been developed. For example, as materials for photoforming methods, compositions containing alkenyl-containing organopolysiloxanes, mercapto-containing organopolysiloxanes, and MQ resins have been developed (Patent Document 2). In addition, for dispensing technologies, silicone compositions containing platinum catalysts activated by ultraviolet light have also been proposed (Patent Document 3). Furthermore, for 3D printers, thermosetting silicone compositions have also been proposed (Patent Document 4).

[0004] In addition, for 3D printers using inkjet printing, a low-viscosity silicone material that can be cured by ultraviolet light has been proposed (Patent Document 5). This material has the advantages of curing by short-term ultraviolet irradiation and excellent shaping accuracy, while conventional silicone materials have the disadvantages of lacking mechanical strength and heat resistance.

[0005] Therefore, in response to the rapidly increasing demand for photoshaping in recent years, a new UV-curable silicone composition has been developed (Patent Documents 6, 7).

[0006] However, compared to the mechanical strength of thermosetting silicone compositions, they are sometimes brittle due to their low elongation. Additionally, in recent years, even with higher viscosity than before, they have gradually become capable of photoforming.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent No. 5890990

[0010] Patent Document 2: Japanese Patent No. 4788863

[0011] Patent Document 3: Japanese Patent No. 5384656

[0012] Patent Document 4: Japanese Patent No. 6727290

[0013] Patent Document 5: Japanese Patent No. 6687111

[0014] Patent Document 6: Japanese Patent No. 6962290

[0015] Patent Document 7: Japanese Patent No. 7342910 Summary of the Invention

[0016] The problem that the invention aims to solve

[0017] The present invention was made in view of the above-mentioned actual situation, and its purpose is to provide an ultraviolet-curable silicone composition and its cured product having a viscosity applicable to photoforming methods such as laser and Digital Light Processing (DLP) methods, and exhibiting excellent rubber-like properties.

[0018] Methods for solving problems

[0019] In order to achieve the above objectives, the inventors conducted in-depth research and found that by adding a photopolymerization initiator to a specific organopolysiloxane containing (meth)acryloyloxy groups and hydrophobic silica particles with a specific average particle size and a specific degree of hydrophobicity, an ultraviolet-curable organosilicon composition that is also applicable to photoforming methods and provides a cured product with good rubber properties is obtained, thus completing the present invention.

[0020] That is, the present invention provides:

[0021] 1. A UV-curable silicone composition for photoforming, comprising:

[0022] (A) An organopolysiloxane having two groups represented by the following formula (1) in one molecule: 100 parts by mass,

[0023] [Chemistry 1]

[0024]

[0025] In the formula, R 1 The R groups, which independently represent monovalent hydrocarbon groups with 1 to 20 carbon atoms, are... 2 R represents an alkylene group having 1 to 20 oxygen atoms or carbon atoms. 3 The terms "acryloyloxyalkyl", "methacryloyloxyalkyl", "acryloyloxyalkoxy", "methacryloyloxyalkoxy", "(acryloyloxyalkyl)dimethylsilyloxy", or "(methacryloyloxyalkyl)dimethylsilyloxy" are mutually independent. "p" represents a number satisfying 0 ≤ p ≤ 10, and "a" represents a number satisfying 1 ≤ a ≤ 3. The dashed line represents a bonding terminal.

[0026] (B) Hydrophobic silica particles with an average particle size of 10–1000 nm and a hydrophobicity of 60% or higher obtained by methanol titration: 10–500 parts by mass, and

[0027] (C) Photopolymerization initiator: 0.01–20 parts by weight;

[0028] 2. The UV-curable silicone composition for photoforming according to claim 1, wherein the viscosity at 23°C is 500 Pa. Below s;

[0029] 3. The UV-curable silicone composition for photoforming according to 1 or 2, wherein, relative to 100 parts by weight of component (A), it further comprises 0.01 to 20 parts by weight of (D), a UV absorber having light absorption at a wavelength of 360 to 410 nm;

[0030] 4. The UV-curable silicone composition for photoforming according to any one of 1 to 3, wherein, relative to 100 parts by weight of component (A), it further comprises 0.01 to 20 parts by weight of colorant (E).

[0031] The cured product of the UV-curable silicone composition for photoforming as described in any one of 5.1 to 4.

[0032] 6. The cured product according to claim 5, wherein the elongation at break is 150% or more.

[0033] The effects of the invention

[0034] The UV-curable silicone composition for photoforming of the present invention has a viscosity applicable to photoforming methods such as laser and DLP, and the cured product exhibits good rubber properties. Detailed Implementation

[0035] The present invention will now be described in detail.

[0036] [1] UV-curable silicone composition for photoforming

[0037] The UV-curable silicone composition for photoforming involved in this invention contains the following components (A) to (C).

[0038] (A) An organopolysiloxane having two groups represented by the following formula (1) in one molecule

[0039] (B) Hydrophobic silica particles with an average particle size of 10–1000 nm and a hydrophobicity of over 60% obtained by methanol titration.

[0040] (C) Photopolymerization initiator

[0041] (A) Organopolysiloxane

[0042] The component (A) used in this invention is one of the crosslinking components of the composition, and is an organopolysiloxane having two groups represented by the following formula (1) in one molecule, and whose main chain is essentially composed of repeating two organosiloxane units.

[0043] [Chemistry 2]

[0044]

[0045] (In the formula, the dashed line represents the joint end.)

[0046] In equation (1), R 1 The groups are monovalent hydrocarbon groups with 1 to 20 carbon atoms, which are independent of each other, preferably monovalent hydrocarbon groups with 1 to 10 carbon atoms, more preferably 1 to 8, excluding aliphatic unsaturated groups.

[0047] R 2 It is an alkylene group having 1 to 20 oxygen atoms or carbon atoms, preferably having 1 to 10 carbon atoms, more preferably having 1 to 5 carbon atoms.

[0048] R 3 They are independently acryloyloxyalkyl, methacryloyloxyalkyl, acryloyloxyalkoxy, methacryloyloxyalkoxy, (acryloyloxyalkyl)dimethylsilyloxy, or (methacryloyloxyalkyl)dimethylsilyloxy.

[0049] In equation (1), R 1 The monovalent hydrocarbon group with 1 to 20 carbon atoms can be any type, such as straight chain, branched, or cyclic. Examples include alkyl, alkenyl, aryl, and aralkyl groups.

[0050] Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-hexyl, cyclohexyl, n-octyl, 2-ethylhexyl, and n-decyl; alkenyl groups such as vinyl, allyl (2-propenyl), 1-propenyl, isopropenyl, and butenyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; and aralkyl groups such as benzyl, phenylethyl, and phenylpropyl.

[0051] In addition, some or all of the hydrogen atoms bonded to the carbon atom in these monovalent hydrocarbon groups can be replaced by halogen atoms such as chlorine, fluorine, and bromine, or by other substituents such as cyano groups. Specific examples include halogen-substituted hydrocarbon groups such as chloromethyl, bromoethyl, and trifluoropropyl, and cyano-substituted hydrocarbon groups such as cyanoethyl.

[0052] Among these, as R 1 Preferably, it is an alkyl or phenyl group with 1 to 5 carbon atoms, and more preferably methyl, ethyl, or phenyl.

[0053] R 2 The alkylene group having 1 to 20 carbon atoms can be straight-chain, branched, or cyclic. Specific examples include methylene, ethylene, propylene, trimethylene, tetramethylene, isobutylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, and decylene.

[0054] Among these, as R 2 Oxygen atoms, methylene, ethylene, and trimethylene are preferred, and oxygen atoms and ethylene are even more preferred.

[0055] As R 3 The number of carbon atoms in the alkyl (alkylene) group of acryloyloxyalkyl, methacryloyloxyalkyl, acryloyloxyalkoxy, methacryloyloxyalkoxy, (acryloyloxyalkyl)dimethylsilyloxy, or (methacryloyloxyalkyl)dimethylsilyloxy is not particularly limited, but is preferably 1 to 10, more preferably 1 to 5. Specific examples of these alkyl groups include R... 1 The groups shown in the examples have 1 to 10 carbon atoms.

[0056] As R 3 Specific examples can be listed by groups represented by the following formulas, but are not limited to these.

[0057] [Chemistry 3]

[0058]

[0059] (In the formula, the dashed line represents the joint end.)

[0060] In the above formula, b is a number that satisfies 1≤b≤4, preferably a number that satisfies 1≤b≤3.

[0061] R 4 It is an alkylene group having 1 to 10 carbon atoms, preferably an alkylene group having 1 to 5 carbon atoms. As R 4 Specific examples can be listed for R 2 The groups exemplified herein are groups having 1 to 10 carbon atoms, wherein methylene, ethylene, and trimethylene are preferred, and methylene and ethylene are more preferred.

[0062] In equation (1), p is a number that satisfies 0≤p≤10, preferably a number that satisfies 0≤p≤5, more preferably 0 or 1, and a is a number that satisfies 1≤a≤3, preferably 1 or 2.

[0063] (A) The binding position of the group represented by the above general formula (1) in the organopolysiloxane molecule can be at the end of the molecular chain (single end or two ends), or at a non-end of the molecular chain (i.e., in the middle of the molecular chain or on the side chain of the molecular chain), or both. In terms of the flexibility of the obtained cured product, it is preferred to be only at the end.

[0064] (A) In the organopolysiloxane molecule of component (A), groups other than those represented by the general formula (1) above that are bonded to silicon atoms can be listed as those related to the above R. 1 The same group is preferably a monovalent hydrocarbon group with 1 to 12 carbon atoms, more preferably 1 to 10, excluding aliphatic unsaturated groups.

[0065] As specific examples of these, examples related to the above R can be listed. 1 For ease of synthesis, the same groups exemplified herein are preferably alkyl, aryl, or haloalkyl, and more preferably methyl, phenyl, or trifluoropropyl.

[0066] In addition, the molecular structure of component (A) is a straight chain or a branched chain (including a straight chain with branches in part of the main chain) whose main chain is basically composed of repeating diorganosiloxane units. It is particularly preferred to be a straight chain diorganopolysiloxane whose molecular chain is capped at both ends with groups represented by the above general formula (1).

[0067] (A) The components may be homopolymers having these molecular structures, copolymers having these molecular structures, or mixtures of two or more of these polymers.

[0068] (A) The viscosity of the organopolysiloxane component at 25°C is preferably 10–10000 mPa, considering further improvements in the viscosity of the composition and the mechanical properties of the cured product. s, more preferably 50-5000 mPa This viscosity range, typically expressed as a number-average degree of polymerization in the case of linear organopolysiloxanes, is approximately 10 to 550, preferably around 50 to 450.

[0069] Furthermore, in this invention, the viscosity can be measured using a rotational viscometer (e.g., BL type, BH type, BS type, cone-plate type, rheometer, etc.) (the same applies below).

[0070] Furthermore, in this invention, the degree of polymerization (or molecular weight) can be obtained, for example, by using toluene or the like as the developing solvent, as the number-average degree of polymerization (or number-average molecular weight) converted from polystyrene in gel permeation chromatography (GPC) analysis.

[0071] Specific examples of organopolysiloxanes as components of (A) can be listed as those represented by the following formulas (2) to (5), but are not limited to these.

[0072] [Chemistry 4]

[0073]

[0074] (where R) 4 "b" has the same meaning as above, "Me" represents methyl, "Ph" represents phenyl, and "q" and "r" are numbers that make the viscosity of the above-mentioned organopolysiloxane reach the above values. "q" is preferably a number satisfying 1 ≤ q ≤ 400, more preferably 1 ≤ q ≤ 200, and even more preferably 1 ≤ q ≤ 100. "r" is preferably a number satisfying 1 ≤ r ≤ 400, and more preferably 10 ≤ r ≤ 300. The order of the siloxane units with "q" and "r" is arbitrary.

[0075] Such organopolysiloxanes can be manufactured using known methods. For example, the polysiloxane represented by the above formula (2) can be a dimethylsiloxane with two terminal dimethylvinylsiloxy groups. The product is obtained by reacting a diphenylsiloxane copolymer with a hydrogenated silanized product of dichlorodimethylsilane and 2-hydroxyethyl acrylate.

[0076] The organopolysiloxane represented by formula (3) above can serve as a dimethylvinylsiloxy-terminated dimethylsiloxane. The product was obtained by the hydrogenation and silylation of diphenylsiloxane copolymer with 3-(1,1,3,3-tetramethyldisiloxyl)propyl methacrylate (CAS No. 96474-12-3).

[0077] The organopolysiloxane represented by formula (4) above can make dimethylsiloxanes end-capped with dimethylvinylsiloxy groups. The product is obtained by reacting a diphenylsiloxane copolymer with a hydrogenated silanized product of dichloromethylsilane and 2-hydroxyethyl acrylate.

[0078] The organopolysiloxane represented by formula (5) above can make dimethylsiloxanes end-capped with dimethylvinylsiloxy groups. The product is obtained by reacting a diphenylsiloxane copolymer with a hydrogenated silanized product of dichloromethylsilane and (hydroxydimethylsilyl) methacrylate (CAS No. 118536-45-1).

[0079] (B) Hydrophobic silica particles

[0080] Component (B) consists of hydrophobic silica particles. By containing component (B), the mechanical strength of the cured product can be improved while maintaining the flowability of the composition.

[0081] (B) The average particle size of the component is 10–1000 nm, preferably 20–1000 nm, more preferably 20–500 nm, and even more preferably 30–200 nm. If the average particle size is smaller than 10 nm, agglomeration becomes intense, and fluidity is lost. Furthermore, if it is larger than 1000 nm, the effect on improving mechanical strength is small. It should be noted that the above-mentioned average particle size is the median diameter (D) used as a volume reference in particle size distribution determination using laser diffraction. 50 The measured value.

[0082] (B) The degree of hydrophobicity of the component obtained by methanol titration is 60% or more, preferably 64% or more. If the silica particles have a high degree of hydrophobicity, they will not agglomerate even with high filling in the composition, will not deteriorate the fluidity, and can improve the mechanical strength of the cured product.

[0083] The degree of hydrophobicity was determined by the methanol titration method shown below.

[0084] (1) Float the sample in a specified amount of ion-exchange water and add methanol dropwise while stirring.

[0085] (2) Read the total amount of the sample when it is suspended in ion-exchanged water.

[0086] (3) The value obtained by multiplying [{methanol drop volume (mL)} / {methanol drop volume (mL) + ion exchange water volume (mL)}] by 100 is the degree of hydrophobicity.

[0087] The shape of component (B) used in this invention is not particularly limited, but spherical shape is preferred.

[0088] The amount of component (B) relative to 100 parts by weight of component (A) is 10 to 500 parts by weight, preferably 20 to 300 parts by weight, and more preferably 30 to 200 parts by weight. If it is less than 10 parts by weight, the effect of improving the mechanical strength of the cured product is weak; if it exceeds 500 parts by weight, the viscosity of the composition increases excessively and the flowability is poor.

[0089] In addition, component (B) preferably has R on the surface of silica. 7 SiO 3 / 2 Unit (R) 7 A monovalent hydrocarbon group consisting of 1 to 20 carbon atoms, either substituted or unsubstituted. 9 3SiO 1 / 2 Unit (R) 9 These are monovalent hydrocarbon groups with 1 to 6 carbon atoms, either substituted or unsubstituted, and may be the same or different.

[0090] Such component (B) can be introduced into R, for example, by hydrolysis and condensation on the surface of hydrophilic silica particles obtained by hydrolysis and condensation of a 4-functional silane compound, an alkyl silicate, or a mixture thereof. 7 SiO 3 / 2 Unit, then import R 9 3SiO 1 / 2 The unit is thus obtained.

[0091] [(B) Synthesis methods of components]

[0092] Specifically, component (B) used in this invention is preferably synthesized using a method comprising the following three steps.

[0093] Step (α): Synthesis steps of hydrophilic silica particles

[0094] Step (β): The step of surface hydrophobization treatment of hydrophilic silica particles to obtain the intermediate of component (B).

[0095] Step (γ): Further hydrophobic surface treatment of the intermediate of component (B) to obtain hydrophobic silica particles of component (B).

[0096] The following explains each step in turn.

[0097] Step (α): Synthesis steps of hydrophilic silica particles

[0098] Step (α) is a step of hydrolyzing and condensing either or both of a 4-functional silane compound represented by the following general formula (I) and an alkyl silicate represented by the following general formula (II) in the presence of an alkaline substance in a mixture of a hydrophilic organic solvent and water to obtain a dispersion of hydrophilic silica particles.

[0099] Si(OR) 5 4 (I)

[0100] [Chemistry 5]

[0101]

[0102] (where R) 5 These are monovalent hydrocarbon groups with 1 to 6 carbon atoms, which may be the same or different. m is a number from 1 to 100.

[0103] In the above general formulas (I) and (II), R 5 The groups are monovalent hydrocarbon groups with the same or different carbon numbers of 1 to 6, preferably monovalent hydrocarbon groups with 1 to 4 carbon numbers, more preferably monovalent hydrocarbon groups with 1 or 2 carbon numbers.

[0104] As a result of R 5The monovalent hydrocarbon group can be straight-chain, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, and n-butyl; and aryl groups such as phenyl. R represents a monovalent hydrocarbon group. 5 Preferably, it is methyl, ethyl, n-propyl or n-butyl, more preferably methyl or ethyl.

[0105] In the above general formula (II), m is a number from 1 to 100, preferably a number from 1 to 50, and more preferably a number from 1 to 25.

[0106] Specific examples of 4-functional silane compounds represented by the above general formula (I) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane and other tetraalkoxysilanes; tetraphenoxysilane and other tetraaryloxysilanes, etc., wherein tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane and tetrabutoxysilane are preferred, and tetramethoxysilane and tetraethoxysilane are more preferred.

[0107] In addition, as specific examples of alkyl silicates represented by general formula (II), methyl silicate, ethyl silicate, etc. can be listed, among which methyl silicate is preferred.

[0108] These can be used individually or in combination of two or more.

[0109] As a specific example of the hydrophilic organic solvent used in step (α), there are no particular limitations as long as it is a 4-functional silane compound represented by general formula (I), an alkyl silicate ester represented by general formula (II), and water. Examples include alcohols; cellosols such as methyl cellosol, ethyl cellosol, butyl cellosol, and acetic acid cellosol; ketones such as acetone and methyl ethyl ketone; and ethers such as dioxane and tetrahydrofuran. Among these, alcohols and cellosols are preferred, and alcohols are more preferred.

[0110] As examples of this class of alcohols, alcohols represented by the following general formula (VI) can be listed.

[0111] R 6 OH (VI)

[0112] (where R) 6 It is a monovalent hydrocarbon group with 1 to 6 carbon atoms.

[0113] In the above general formula (VI), R 6 It is a monovalent hydrocarbon group having 1 to 6 carbon atoms, preferably having 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms. As a monovalent hydrocarbon group composed of R... 6 Specific examples of monovalent hydrocarbon groups can be listed, such as those derived from R. 5 The exemplified group is the same group, wherein R 6 Preferably, it is methyl, ethyl, n-propyl, or isopropyl, and more preferably methyl or ethyl.

[0114] Specific examples of alcohols represented by general formula (VI) include methanol, ethanol, propanol, isopropanol, butanol, etc., with methanol and ethanol being preferred. If the number of carbon atoms in the alcohol increases, the particle size of the resulting silica particles becomes larger. Therefore, methanol is preferred in order to obtain the desired small-sized silica particles.

[0115] The amount of water used in the above hydrolysis and condensation is preferably 0.5 to 5 moles, more preferably 0.6 to 2 moles, and even more preferably 0.7 to 1 mole, relative to the total hydroxyl groups of the 4-functional silane compound represented by general formula (I) and / or the alkyl silicate represented by general formula (II) of 1 mole. Furthermore, the ratio of water to hydrophilic organic solvent is preferably 10 to 200 parts by mass of hydrophilic organic solvent relative to 100 parts by mass of water.

[0116] Furthermore, specific examples of the alkaline substance used in step (α) include ammonia, dimethylamine, and diethylamine, among which ammonia and diethylamine are preferred, and ammonia is more preferred. After dissolving the required amount of these alkaline substances in water, the resulting aqueous solution (alkaline) can be mixed with a hydrophilic organic solvent.

[0117] The amount of alkaline substance used is preferably 0.01 to 2 moles, more preferably 0.02 to 0.5 moles, and even more preferably 0.04 to 0.12 moles, relative to the total amount of the hydroxyl groups of the tetrafunctional silane compound represented by general formula (I) and / or the alkyl silicate represented by general formula (II) per mole. In this case, the smaller the amount of alkaline substance, the more desirable the small-diameter silica particles become.

[0118] After the alkaline substance is added to a mixture of a hydrophilic organic solvent and water, it may be further added to the resulting mixture along with a 4-functional silane compound represented by general formula (I) and / or an alkyl silicate represented by general formula (II), or simultaneously added to a mixture of water and a hydrophilic organic solvent along with the addition of the 4-functional silane compound and / or the alkyl silicate and the hydrophilic organic solvent.

[0119] There are no particular limitations on the reaction conditions for step (α), and it can be carried out under previously known conditions, such as preferably around 10 to 80°C and around 1 to 10 hours.

[0120] The resulting mixed solvent dispersion containing hydrophilic silica particles can be used directly in step (β), but it is preferable to add water to the mixed solvent dispersion containing hydrophilic silica particles, then distill off the hydrophilic organic solvent to convert it into an aqueous dispersion, thereby hydrolyzing the remaining alkoxy groups and thus converting it into an aqueous dispersion containing hydrophilic silica particles.

[0121] When changing the dispersion medium of the silica particle mixed solvent dispersion to water, it can be done, for example, by adding water to the dispersion and distilling off the hydrophilic organic solvent (repeated as needed). The amount of water added is preferably 50 to 200 parts by mass, more preferably 80 to 150 parts by mass, relative to the total amount of the hydrophilic organic solvent and the alcohol generated in the synthesis step of the hydrophilic silica particles.

[0122] Step (β): Surface treatment steps for hydrophilic silica particles

[0123] Step (β) is to treat the surface of the hydrophilic silica particles by adding one or both of the trifunctional silane compound represented by the following general formula (III) and its (partial) hydrolytic condensate to the mixed solvent dispersion of the hydrophilic silica particles obtained in step (α), thereby obtaining a dispersion of silica particles (hydrophobic silica particle intermediate) intermediate of component (B).

[0124] R 7 Si(OR) 8 3 (III)

[0125] (where R) 7 R is a monovalent hydrocarbon group with 1 to 20 carbon atoms, either substituted or unsubstituted. 8 These are monovalent hydrocarbon groups with 1 to 6 carbon atoms, which may be the same or different.

[0126] In the above general formula (III), R 7 The group is a monovalent hydrocarbon group with 1 to 20 carbon atoms, either substituted or unsubstituted, preferably with 1 to 10 carbon atoms, more preferably with 1 to 3 carbon atoms, and even more preferably with 1 or 2 carbon atoms. Regarding R... 7 For monovalent hydrocarbon groups, straight-chain, branched, and cyclic forms are all possible. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, n-hexyl, and n-decyl. Among these, R... 7 Preferably, the hydrocarbon group consists of methyl, ethyl, n-propyl, or isopropyl, with methyl or ethyl being more preferred. Furthermore, some or all of the hydrogen atoms in these monovalent hydrocarbon groups may be substituted with halogen atoms such as fluorine, chlorine, or bromine atoms, with fluorinated alkyl groups being preferred.

[0127] In the above general formula (III), R 8 The groups are monovalent hydrocarbon groups with 1 to 6 carbon atoms, either the same or different, preferably monovalent hydrocarbon groups with 1 to 3 carbon atoms, more preferably monovalent hydrocarbon groups with 1 or 2 carbon atoms. As R 8 Specific examples can be listed related to R. 5 The same group as the group illustrated in the example, wherein R 8Preferably, it is methyl, ethyl, or n-propyl, more preferably methyl or ethyl.

[0128] Specific examples of trifunctional silane compounds represented by general formula (III) include unsubstituted or halogen-substituted trialkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, trifluoropropyltrimethoxysilane, and heptadecafluorodecyltrimethoxysilane. Among these, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane are preferred, and methyltrimethoxysilane and methyltriethoxysilane are more preferred.

[0129] The amount of the trifunctional silane compound represented by general formula (III) added is preferably 0.001 to 1 mole relative to 1 mole of Si atoms in the hydrophilic silica particles obtained in step (α), more preferably 0.01 to 0.4 moles, and even more preferably 0.01 to 0.2 moles. If the amount added is 0.001 moles or more, the hydrophobicity of the obtained component (B) is improved, thus exhibiting excellent dispersibility; if it is 1 mole or less, the possibility of aggregation of component (B) can be suppressed.

[0130] There are no particular limitations on the processing conditions for step (β), but it is preferred to be around 10 to 80°C for about 1 to 10 hours.

[0131] Step (γ): (B) Surface treatment steps for component intermediates

[0132] Step (γ) is as follows: The dispersion medium of the mixed solvent dispersion of the intermediate (B) component, i.e., silica particles, obtained in step (β) is changed to, for example, a ketone solvent. After obtaining a ketone solvent dispersion of the hydrophobic silica particle intermediate, either or both of a silazane compound represented by the following general formula (IV) and a monofunctional silane compound represented by the following general formula (V) are added to the ketone solvent dispersion. The surface of the intermediate (B) component, i.e., the silica particles, is then treated to obtain the hydrophobic silica particles of component (B). Using this step, the silanol-based triorganosilylated residues on the surface of the hydrophobic silica particle intermediate are alkylated, thereby transforming R... 9 3SiO 1 / 2 The unit is imported into this surface.

[0133] R 9 3SiNHSiR 9 3 (IV)

[0134] R 9 3SiX (V)

[0135] (where R) 9 (The groups are monovalent hydrocarbon groups with 1 to 6 carbon atoms, which may be the same or different substituted or unsubstituted groups, and X is an OH group or a hydrolyzable group.)

[0136] In the above general formulas (IV) and (V), R 9 The group is a monovalent hydrocarbon group with 1 to 6 carbon atoms, either substituted or unsubstituted, and preferably has 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms. As R 9 Specific examples can be listed, such as those related to R. 5 The same group as the group illustrated in the example, wherein R 9 Methyl, ethyl, or n-propyl are preferred, with methyl or ethyl being more preferred. Furthermore, some or all of the hydrogen atoms in these monovalent hydrocarbon groups may be replaced by halogen atoms such as fluorine, chlorine, or bromine atoms, with fluorinated alkyl groups being preferred.

[0137] X is an OH group or a hydrolyzable group. Examples of hydrolyzable groups include chlorine atoms; alkoxy groups such as methoxy and ethoxy; amino, N-methylamino, N,N'-dimethylamino, N-ethylamino, N,N'-diethylamino; acyloxy groups such as acetoxy, etc., wherein alkoxy or amino is preferred, alkoxy is more preferred, and methoxy or ethoxy is even more preferred.

[0138] Specific examples of silazane compounds represented by general formula (IV) include hexamethyldisilazane, hexaethyldisilazane, tetramethyldivinyldisilazane, etc., with hexamethyldisilazane being preferred.

[0139] Specific examples of 1-functional silane compounds represented by general formula (V) include monosilanol compounds such as trimethylsilanol and triethylsilanol; monochlorosilanes such as trimethylchlorosilane and triethylchlorosilane; monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane; monoaminosilanes such as trimethylsilyldimethylamine and trimethylsilyldiethylamine; and monoacyloxysilanes such as trimethylacetoxysilane. Among these, trimethylsilanol, trimethylmethoxysilane, or trimethylsilyldiethylamine are preferred, and trimethylsilanol or trimethylmethoxysilane is more preferred.

[0140] These can be used individually or in combination.

[0141] The amount of the silazane compound represented by general formula (IV) and / or the monofunctional silane compound represented by general formula (V) used relative to 1 mole of Si atoms in the hydrophobic silica particle intermediate obtained in step (β) is preferably 0.1 to 0.5 moles, more preferably 0.2 to 0.4 moles, and even more preferably 0.25 to 0.35 moles. If the amount used is 0.1 moles or more, the hydrophobicity of the obtained hydrophobic silica particles increases and the dispersibility becomes excellent; if cost and other factors are taken into account, an amount of 0.5 moles or less is sufficient.

[0142] When the dispersion medium of the mixed solvent dispersion of the hydrophobic silica particle intermediate obtained in step (β) is changed from a mixture of water or a hydrophilic organic solvent and an alcohol produced during hydrolysis to a ketone solvent, this can be achieved by adding a ketone solvent to the mixed solvent dispersion of the hydrophobic silica particle intermediate and distilling off the mixture of water or a hydrophilic organic solvent and alcohol (repeated as needed). The preferred conditions are approximately 10–150°C and approximately 1–20 hours.

[0143] The amount of ketone solvent added at this time is preferably 50 to 500 parts by mass relative to 100 parts by mass of the obtained hydrophobic silica particle intermediate, more preferably 100 to 300 parts by mass. Specific examples of ketone solvents used herein include methyl ethyl ketone, methyl butyl ketone, acetylacetone, etc., among which methyl isobutyl ketone is preferred.

[0144] In addition, there are no particular limitations on the surface treatment conditions for step (γ), but it is preferred to be around 10 to 150°C for about 1 to 20 hours.

[0145] The (B) component obtained as described above can be obtained as a powder by conventional methods such as atmospheric pressure drying or vacuum drying at room temperature or under heating.

[0146] (C) Photopolymerization initiator

[0147] (C) is a photopolymerization initiator. Specific examples of photopolymerization initiators that can be used in this invention include 2,2-diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one (Omnirad 651), 1-hydroxy-cyclohexyl-phenyl-one (Omnirad 184), 2-hydroxy-2-methyl-1-phenyl-propane-1-one (Omnirad 1173), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propanoyl)-benzyl]-phenyl}-2-methyl-propane-1-one (Omnirad 127), methyl phenylglyoxylate (Omnirad MBF), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one (Omnirad 907), and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone (Omnirad 907). 369), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Omnirad 819), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Omnirad TPO), ethyl phenyl(2,4,6-trimethylbenzoyl)phosphine oxide (Omnirad TPO-L), etc. (all of which are manufactured by IGM Resins BV). These can be used alone or in combination of two or more.

[0148] From the viewpoint of compatibility with components (A) and (B), 2,2-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one (Omnirad 1173), bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Omnirad 819), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Omnirad TPO H), and ethyl phenyl(2,4,6-trimethylbenzoyl)phosphine oxide (Omnirad TPO-L) are preferred.

[0149] The amount of photopolymerization initiator added relative to 100 parts by weight of component (A) is 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight. If it is less than 0.01 parts by weight, the curing property is insufficient, and if it is more than 20 parts by weight, the deep curing property deteriorates.

[0150] (D) Ultraviolet absorbers that absorb light in the 360–410 nm range

[0151] In the composition of the present invention, in order to adjust the curing properties during light shaping generated by the 3D printer, an ultraviolet absorber with light absorption at wavelengths of 360 to 410 nm can be added.

[0152] Specific examples of ultraviolet absorbers that can be used in this invention include 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (Tinuvin 571, manufactured by BASF), 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy C7-9 side-chain and straight-chain alkyl esters of phenylpropionic acid (Tinuvin 384-2, manufactured by BASF), 2-(5-chloro-2-benzotriazolyl)-6-tert-butyl-p-cresol (Tinuvin 326, manufactured by BASF), and the product of the reaction of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl with [(C10-C16, mainly C12-C13 alkoxy)methyl]ethylene oxide (Tinuvin). 400 (manufactured by BASF), thioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, benzophenone, camphorquinone, 1-phenyl-1,2-propanedione, hexyl diethylaminohydroxybenzoylbenzoate (Uvinul A Plus, manufactured by BASF), 1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione, 2-ethylhexyl 4-methoxycinnamic acid, etc. These can be used alone or in combination of two or more.

[0153] When using a UV absorber, the amount added relative to 100 parts by weight of component (A) is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight. If it is less than 0.01 parts by weight, the effect of the UV absorber may not be fully manifested, and if it is more than 20 parts by weight, the deep curing properties may deteriorate.

[0154] (E) Pigment

[0155] In the compositions of the present invention, various colorants can be added for the purpose of adjusting the curability and coloring the composition.

[0156] As colorants, common pigments (iron oxide, titanium oxide, zinc oxide, etc.), dyes, carbon black, etc. can be used. These can be used alone or in combination of two or more.

[0157] When using pigments, the amount added is preferably 0.01 to 20 parts by weight relative to 100 parts by weight of component (A). If it is less than 0.01 parts by weight, the effect of the pigment may not be fully manifested, and if it is more than 20 parts by weight, the deep curing properties may deteriorate.

[0158] Furthermore, in the composition of the present invention, additives such as silane coupling agents, adhesive aids, polymerization inhibitors, antioxidants, ultraviolet absorbers as light stabilizers, and light stabilizers can be incorporated without impairing the effects of the present invention.

[0159] In addition, the compositions of the present invention can also be used by properly mixing with other resin compositions.

[0160] [2] Method for manufacturing organosilicon compositions

[0161] There are no particular limitations on the method for manufacturing the organosilicon composition of the present invention, and conventionally known methods can be used. That is, the organosilicon composition of the present invention is obtained by mixing components (A) to (C) and other components used as needed.

[0162] The method for manufacturing the organosilicon composition of the present invention particularly preferably includes the following steps (1) and (2).

[0163] Process (1): A process for manufacturing component (B) using a method comprising the following steps (α), (β), and (γ).

[0164] Step (2): The process of mixing components (A) to (C) and other components as needed.

[0165] Process (1): Process for manufacturing component (B)

[0166] Process (1) is a process of manufacturing component (B) by means of the following steps (α), (β) and (γ).

[0167] Step (α): A dispersion of hydrophilic silica particles is obtained by hydrolyzing and condensing either or both of a 4-functional silane compound represented by general formula (I) and an alkyl silicate represented by general formula (II) in the presence of an alkaline substance in a mixture of a hydrophilic organic solvent and water.

[0168] Si(OR) 5 4 (I)

[0169] [Chemistry 6]

[0170]

[0171] (where R) 5 (and m represent the same meaning as above.)

[0172] Step (β): Adding either or both of a trifunctional silane compound represented by the following general formula (III) and its (partial) hydrolytic condensate to the mixed solvent dispersion of hydrophilic silica particles obtained in step (α), thereby treating the surface of the hydrophilic silica particles to obtain the intermediate of component (B), namely, the dispersion of silica particles.

[0173] R 7 Si(OR) 83 (III)

[0174] (where R) 7 and R 8 This indicates the same meaning as above.

[0175] Step (γ): Add either or both of a silazane compound represented by general formula (IV) and a monofunctional silane compound represented by general formula (V) to the dispersion of the intermediate (B) particles obtained in step (β), thereby treating the surface of the intermediate (B) particles to obtain hydrophobic silica particles of component (B).

[0176] R 9 3SiNHSiR 9 3 (IV)

[0177] R 9 3SiX (V)

[0178] (where R) 9 (And X represents the same meaning as above.)

[0179] The detailed manufacturing method for component (B) is as described above.

[0180] Process (2): The process of mixing components (A) to (C).

[0181] There are no particular limitations on the process of mixing components (A) to (C). The UV-curable silicone composition for photoforming of the present invention can be obtained by mixing the above-mentioned components (A) to (C) and other components used as needed in any order, followed by stirring, etc. There are no particular limitations on the apparatus used for stirring or other operations; a pounder, a three-roll mill, a ball mill, a planetary mixer, etc., can be used. In addition, these apparatuses can be appropriately combined.

[0182] The organosilicon composition of the present invention can be in either a single-liquid or two-liquid form. A single-liquid composition can be obtained, for example, by adding components (A) to (C) and other components as needed to a gantry mixer (manufactured by Inoue Manufacturing Co., Ltd., trade name: Planetary Mixer) and mixing. Alternatively, components (A) and (B) can be added to the gantry mixer and mixed under reduced pressure at room temperature for 1 hour. The resulting mixture can be cooled, and then component (C) can be added and mixed at room temperature for 30 minutes to obtain the final product.

[0183] From the viewpoint of photoforming properties, the viscosity of the UV-curable silicone composition for photoforming of the present invention at 23°C is preferably 500 Pa. Below s, more preferably 400 Pa Below s, 100 Pa is further preferred. Below 500 Pa. If it exceeds 500 Pa... If the value is lower than s, the shape retention deteriorates, and sometimes the desired shape cannot be obtained correctly. Furthermore, there is no particular restriction on the lower limit value; 1 Pa is preferred. s or more, preferably 2Pa s or more.

[0184] [3]Cured product

[0185] The UV-curable silicone composition for photoforming of the present invention is rapidly cured by irradiation with ultraviolet light.

[0186] In this case, the light sources for irradiating ultraviolet light can include, for example, UV-LED lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, carbon arc lamps, and xenon lamps.

[0187] Regarding ultraviolet irradiation, it is preferable to carry out the process at room temperature (25°C) in an atmosphere of inactive gases such as nitrogen or argon.

[0188] The amount of ultraviolet radiation (cumulative light intensity) is preferably 1 to 10,000 mJ / cm² when curing is performed using only ultraviolet radiation, for example, for molding the composition of the present invention into a sheet with a thickness of about 2.0 mm. 2 More preferably 10–8000 mJ / cm 2 That is, when using an illuminance of 100mW / cm² 2 In the presence of ultraviolet radiation, irradiation with ultraviolet radiation for about 0.01 to 100 seconds is sufficient.

[0189] In order for the cured product obtained from the UV-curable silicone composition for photoforming of the present invention to exhibit excellent rubber properties, the tensile strength is preferably 2.0 MPa or more, more preferably 3.0 MPa or more. Furthermore, the elongation at break is preferably 150% or more, more preferably 200% or more. It should be noted that these values ​​are measured according to JIS-K6249.

[0190] Example

[0191] The following examples of synthesis, comparative synthesis, embodiments, and comparative examples are provided to illustrate the present invention in more detail, but the present invention is not limited to these embodiments.

[0192] Furthermore, the compounds used in the examples are described below. In the following formulas, Me represents methyl and Ph represents phenyl.

[0193] [1] Compounding components

[0194] (A) Ingredients

[0195] [Chemistry 7]

[0196]

[0197] (In the formula, the order of the siloxane units in parentheses is arbitrary.)

[0198] (B) Components

[0199] (B-1) Hydrophobic silica particles obtained in Synthesis Example 1

[0200] (B-2) Hydrophobic silica particles obtained in Synthesis Example 2

[0201] (B-3) Hydrophobic silica particles obtained in Synthesis Example 3

[0202] (B-1 ratio) Compare the hydrophobic silica particles obtained in Synthesis Example 1.

[0203] (C) Components

[0204] (C-1) 2-Hydroxy-2-methyl-1-phenyl-propane-1-one (Omnirad 1173, manufactured by IGM Resins BV)

[0205] (C-2) Phenyl(2,4,6-trimethylbenzoyl)phosphinic acid ethyl ester (Omnirad TPO-L, manufactured by IGM Resins B.V.)

[0206] [2] Synthesis of hydrophobic silica microparticles

[0207] [Synthesis example 1]

[0208] Step (α): Synthesis steps of hydrophilic silica particles

[0209] In a 3-liter glass reactor equipped with a stirrer, dropping funnel, and thermometer, 623.7 g of methanol, 41.4 g of water, and 49.8 g of 28% (w / w) ammonia were added and mixed. The solution was adjusted to 35°C, and while stirring, 1163.7 g of tetramethoxysilane and 418.4 g of 5.4% (w / w) ammonia were added dropwise over 5 hours. After the addition was completed, stirring was continued for another 0.5 hours to carry out hydrolysis, resulting in a suspension of hydrophilic spherical silica particles. An ester adapter and condenser were installed in the glass reactor, and the mixture was heated to 60–70°C. 649 g of methanol was distilled off, and 1600 g of water was added. The mixture was then further heated to 70–90°C, and 160 g of methanol was distilled off, yielding an aqueous suspension of hydrophilic silica particles.

[0210] Step (β): Surface treatment steps for hydrophilic silica particles

[0211] 115.8 g of methyltrimethoxysilane (0.1 equivalents relative to SiO2) and 46.6 g of 5.4% ammonia were added dropwise to the aqueous suspension at 25°C for 0.5 hours. After the addition, the mixture was heated to 50°C and allowed to mature for 1 hour. After the reaction was completed, the mixture was cooled to 25°C and the surface of the hydrophilic silica particles was treated to obtain a dispersion of hydrophobic silica particle intermediates, which served as the intermediate for component (B).

[0212] Step (γ): (B) Surface treatment steps for component intermediates

[0213] After adding 1000g of methyl isobutyl ketone to the resulting dispersion, the dispersion was heated to 80–115°C under conditions of intense interfacial fluctuation for 11 hours, and 1336g of a methanol-water mixture was distilled off. Then, 357.4g of hexamethyldisilazane was added to the resulting dispersion at 25°C, and the dispersion was heated to 120°C and reacted for 3 hours to trimethylsilylate the silica particles, yielding hydrophobic silica particles. Finally, the solvent was distilled off using an evaporator under heating to obtain 477g of hydrophobic silica particles (B-1).

[0214] [Synthesis example 2]

[0215] Except for step (α) of synthesis example 1, in which 1163.7g of tetramethoxysilane was replaced with 901.9g of methyl silicate (Methyl Silicate 51 manufactured by Koulco), 470g of hydrophobic silica particles (B-2) were also obtained.

[0216] [Synthesis example 3]

[0217] Except that the amount of methyltrimethoxysilane used in step (β) of Synthesis Example 1 was changed to 11.6 g (0.01 equivalents relative to SiO2), 360 g of hydrophobic silica particles (B-3) were also obtained.

[0218] [Comparative Synthesis Example 1]

[0219] In a 3-liter glass reactor equipped with a stirrer, dropping funnel, and thermometer, 60 g of isopropanol and 100 g of SNOTEX OL (manufactured by Nissan Chemical Industries, Ltd., with an average particle size of 50 nm, dispersed in water, and a solid content concentration of 20% by mass), a type of colloidal silica particle, were added and mixed. 0.48 g of methyltrimethoxysilane was then added dropwise to the solution over 0.5 hours. After the addition, the mixture was heated to 50°C and allowed to mature for 1 hour. After the reaction was completed, the mixture was cooled to 25°C, and the surface of the silica particles was treated.

[0220] Next, 0.78 g of hexamethyldisilazane was added, and the dispersion was heated to 105 °C and reacted for 2 hours. Finally, 2.6 g of 35% hydrochloric acid aqueous solution was added to precipitate the silica particles. Then, the solvent was removed by distillation using an evaporator under heating to obtain hydrophobic silica particles (B-1 ratio).

[0221] [Determination Method]

[0222] The obtained hydrophobic silica particles were measured according to methods 1 and 2 described below. The results are shown in Table 1.

[0223] 1. Determination of the average particle size of hydrophobic silica particles

[0224] (1) Take 0.1g of the sample into a glass bottle, add 20g of methanol, and stir.

[0225] (2) Disperse the sample for 10 minutes using an ultrasonic dispersion device to prepare the test sample.

[0226] (3) The sample in (2) was measured using a laser analytical scattering particle size distribution measuring device (Nikkiso Corporation, Nanotrac 150), and the median diameter of the volume reference (equivalent to the cumulative 50% of the particle size when the particle size distribution is expressed as a cumulative distribution) was used as the average particle size.

[0227] 2. Determination of the hydrophobicity of hydrophobic silica particles (methanol titration method)

[0228] (1) Weigh 0.2 mg of the sample into a 500 mL Erlenmeyer flask.

[0229] (2) Add 50 mL of ion-exchanged water to (1) and stir with a stirrer.

[0230] (3) While stirring, add methanol dropwise using a burette and read the total amount of the sample when suspended in ion-exchange water.

[0231] (4) The degree of hydrophobicity was calculated using the following formula.

[0232] Hydrophobicity (%) = [{Methanol added (mL)} / {Methanol added (mL) + Ion exchange water added (mL)}] × 100

[0233] [Table 1]

[0234]

[0235] [3] Manufacturing and evaluation of organosilicon compositions, manufacturing and evaluation of cured products

[0236] [Examples 1-7 and Comparative Example 1]

[0237] The components (A) to (C) above were mixed according to the compositions in Table 2 to prepare the organosilicon compositions listed in Table 2. Furthermore, the viscosities of the compositions in Table 2 are values ​​measured using a rotational viscometer at 23°C.

[0238] The prepared organosilicon composition was cured using a UV curing apparatus manufactured by CCS Corporation at room temperature (25°C) under a nitrogen atmosphere with an irradiation dose of 8000 mJ / cm² of ultraviolet light at a wavelength of 405 nm. 2 The material was cured by irradiating it with ultraviolet light. The sheet thickness was then set to 2.0 mm. The hardness, elongation at break, and tensile strength of the cured material were determined according to JIS K 6249:2003.

[0239] [Table 2]

[0240]

[0241] As shown in Table 2, the UV-curable silicone compositions prepared in Examples 1 to 7 have low viscosity that can be applied to photoforming methods, and thus, their cured products have good mechanical properties.

Claims

1. A UV-curable silicone composition for photoforming, comprising: (A) An organopolysiloxane having two groups represented by the following formula (1) in one molecule: 100 parts by mass, [Chemistry 1] In the formula, R 1 The R groups, which independently represent monovalent hydrocarbon groups with 1 to 20 carbon atoms, are... 2 R represents an alkylene group having 1 to 20 oxygen atoms or carbon atoms. 3 The terms "acryloyloxyalkyl", "methacryloyloxyalkyl", "acryloyloxyalkoxy", "methacryloyloxyalkoxy", "(acryloyloxyalkyl)dimethylsilyloxy", or "(methacryloyloxyalkyl)dimethylsilyloxy" are mutually independent. "p" represents a number satisfying 0 ≤ p ≤ 10, and "a" represents a number satisfying 1 ≤ a ≤ 3. The dashed line represents a bonding terminal. (B) Hydrophobic silica particles with an average particle size of 10–1000 nm and a hydrophobicity of 60% or higher obtained by methanol titration: 30–500 parts by mass, and (C) Photopolymerization initiator: 0.01–20 parts by weight, in, The viscosity at 23℃ is 100 Pa. Below s.

2. The UV-curable silicone composition for photoforming according to claim 1, wherein, In addition to 100 parts by mass of component (A), it also contains 0.01 to 20 parts by mass of (D), an ultraviolet absorber that has light absorption at wavelengths of 360 to 410 nm.

3. The UV-curable silicone composition for photoforming according to claim 1, wherein, In addition to 100 parts by weight of component (A), it also contains 0.01 to 20 parts by weight of colorant (E).

4. The cured product of the UV-curable silicone composition for photoforming according to any one of claims 1 to 3.

5. The cured product according to claim 4, wherein, The elongation at break is over 150%.

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