UV-curable silicone compositions for photoforming, cured products and curing methods

Abstract

A photopolymerizable silicone composition for photoforming is provided, comprising (A) an organopolysiloxane having two or more free radical polymerizable groups (excluding groups containing heteroatoms other than oxygen atoms) in one molecule, (B) hydrophobic silica particles with an average particle size of 10 nm to 1000 nm and a hydrophobicity of 60% or more obtained by methanol titration, and (C) a photopolymerization initiator. 2 After being irradiated with ultraviolet light with a wavelength of 405nm, the material was cured at 85℃ and 85%RH for 24 hours. The resulting cured material with a thickness of 2.0mm had a tensile strength of over 4.5MPa and an elongation at break of over 300%.

Description

Technical Field

[0001] This invention relates to a UV-curable silicone composition for photoforming, the cured product thereof, and a method for curing the UV-curable silicone composition for photoforming. Background Technology

[0002] In recent years, the development of shaping materials used in 3D printers has emerged, 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] 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 2). 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.

[0004] Therefore, in response to the surge in photoshaping in recent years, a new UV-curable silicone composition has been developed (Patent Documents 3, 4).

[0005] However, compared to the mechanical strength of thermosetting silicone compositions, they are sometimes brittle due to their low elongation. Furthermore, in recent years, even with higher viscosities than before, photoforming has become increasingly possible.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 5890990

[0009] Patent Document 2: Japanese Patent No. 6687111

[0010] Patent Document 3: Japanese Patent No. 6962290

[0011] Patent Document 4: Japanese Patent No. 7342910 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] The present invention was made in view of the above-mentioned actual situation, and aims to provide an ultraviolet-curable silicone composition and its cured product having a viscosity applicable to photoshaping methods such as laser and Digital Light Processing (DLP), capable of shaping even with a small amount of ultraviolet irradiation, and exhibiting excellent rubber properties through post-treatment.

[0014] Methods for solving problems

[0015] To achieve the above objectives, the inventors conducted in-depth research and discovered that by adding a photopolymerization initiator to an organopolysiloxane containing specific radical polymerizable groups formed by oxygen atoms directly bonded to silicon atoms, and hydrophobic silica particles with an average particle size in the range of 10 nm to 1000 nm and a hydrophobicity of 60% or more obtained by methanol titration, a UV-curable organosilicon composition that can also be applied to photoforming methods is obtained. This invention is completed by performing a second curing using condensation after a first curing with ultraviolet light irradiation, resulting in a cured product with good rubber-like properties.

[0016] That is, the present invention provides:

[0017] 1. A UV-curable silicone composition for photoforming, comprising:

[0018] (A) An organopolysiloxane having two or more radical polymerizable groups (excluding groups containing heteroatoms other than oxygen atoms) in one molecule, wherein the oxygen atoms are directly bonded to the silicon atom.

[0019] (B) Hydrophobic silica particles with an average particle size of 10 nm to 1000 nm and a hydrophobicity of over 60% obtained by methanol titration, and

[0020] (C) Photopolymerization initiator,

[0021] For this composition, at 25°C and 8000 mJ / cm 2 After being irradiated with ultraviolet light with a wavelength of 405nm, the material was cured at 85℃ and 85%RH for 24 hours. The resulting cured material with a thickness of 2.0mm had a tensile strength of over 4.5MPa and an elongation at break of over 300%.

[0022] 2. The UV-curable organosilicon composition for photoforming according to 1, wherein component (A) is an organopolysiloxane having 2 to 6 acryloyloxyalkoxy or methacryloyloxyalkoxy atoms bonded to silicon atoms in one molecule;

[0023] 3. The UV-curable silicone composition for photoforming according to 1, wherein component (A) is an organopolysiloxane represented by the following formula (1),

[0024] [Chemistry 1]

[0025]

[0026] In the formula, n is a number satisfying 1 ≤ n ≤ 1000, m is a number satisfying 1 ≤ m ≤ 1000, the order of the siloxane units with n and m is arbitrary, Ar is an aryl group with 6 to 20 carbon atoms, and R... 1 Each group consists of a monovalent hydrocarbon group having 1 to 20 carbon atoms, and A is a group represented by the following formula (2).

[0027] [Chemistry 2]

[0028]

[0029] In the formula, R 1 Similar to the above, R 2 R is an alkylene group having 1 to 20 carbon atoms or an oxygen atom. 3 They are independently acryloyloxyalkoxy or methacryloyloxyalkoxy, where a is a number that satisfies 1 ≤ a ≤ 3, and the dashed line represents the bonding end;

[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 contains 10 to 500 parts by weight of component (B) and 0.01 to 20 parts by weight of component (C);

[0031] 5. The UV-curable silicone composition for photoforming according to any one of 1 to 4, wherein the viscosity at 23°C is 500 Pa•s or less;

[0032] 6. A cured product, which is a cured product of a UV-curable silicone composition for photoforming, said UV-curable silicone composition for photoforming containing:

[0033] (A) An organopolysiloxane having two or more radical polymerizable groups (excluding groups containing heteroatoms other than oxygen atoms) in one molecule, wherein the oxygen atoms are directly bonded to the silicon atom.

[0034] (B) Hydrophobic silica particles with an average particle size of 10 nm to 1000 nm and a hydrophobicity of over 60% obtained by methanol titration, and

[0035] (C) Photopolymerization initiator,

[0036] The tensile strength at a thickness of 2.0 mm is above 4.5 MPa, and the elongation at break is above 300%.

[0037] 7. A curing method, comprising the curing method of the UV-curable silicone composition for photoforming according to any one of 1 to 5, and including:

[0038] (i) A step of irradiating the photoforming UV-curable silicone composition according to any one of 1 to 5 with ultraviolet light to cause the composition to be free-radical cured, thereby obtaining a first cured product; and

[0039] (ii) The process of further condensing and curing the obtained first cured product to obtain a second cured product;

[0040] 8. The curing method according to 7, wherein the condensation curing in step (ii) is curing using moisture.

[0041] The effects of the invention

[0042] The UV-curable silicone composition for photoforming of the present invention can be applied to photoforming methods such as laser and DLP. The cured material after UV curing exhibits good rubber properties when moistened. Detailed Implementation

[0043] The present invention will now be described in detail.

[0044] [1] UV-curable silicone composition for photoforming

[0045] The UV-curable silicone composition for photoforming involved in this invention contains the following components (A) to (C).

[0046] (A) An organopolysiloxane having two or more radical polymerizable groups in one molecule, wherein an oxygen atom is directly bonded to a silicon atom.

[0047] (B) Hydrophobic silica particles with an average particle size in the range of 10 nm to 1000 nm and a hydrophobicity of over 60% obtained by methanol titration.

[0048] (C) Photopolymerization initiator

[0049] (A) Organopolysiloxane

[0050] The component (A) used in this invention is the crosslinking component of the composition, and is an organopolysiloxane having two or more groups containing free radical polymerizable groups bonded to silicon atoms in one molecule, preferably having 2 to 6, more preferably 2 to 4 of the above-mentioned groups containing free radical polymerizable groups in one molecule. However, the above-mentioned groups containing free radical polymerizable groups do not contain heteroatoms other than oxygen atoms.

[0051] By utilizing groups containing free radical polymerizable groups that are bonded to silicon atoms by oxygen atoms that are directly bonded to silicon atoms, the compositions of the present invention have free radical curing and condensation curing properties. In particular, by further post-treating the first cured product obtained by irradiating the composition of the present invention with ultraviolet light (free radical curing) with moisture (condensation curing), a second cured product with even better rubber properties can be obtained.

[0052] Specific examples of the groups containing free radical polymerizable groups mentioned above include acryloyloxyalkoxy or methacryloyloxyalkoxy, which are bonded to silicon atoms.

[0053] The improved rubber properties of the cured product due to post-treatment under humid conditions are believed to be caused by hydrolytic condensation at sites such as (meth)acryloyloxyalkoxy groups bonded to silicon atoms, resulting in chain-promoting reactions between the organopolysiloxanes of component (A) and cross-linking reactions between the organopolysiloxanes of component (A) and the silanol groups on the surface of the silica particles of component (B), described later. It should be noted that in this invention, (meth)acryloyloxyalkoxy represents acryloyloxyalkoxy or methacryloyloxyalkoxy.

[0054] The aforementioned groups containing free radical polymerizable groups can be located at the end (single end or double end) of the molecular chain, or in the middle of the molecular chain, or both. Preferably, they are located at the end (single end or double end) of the molecular chain, and more preferably at the double ends of the molecular chain.

[0055] In the organopolysiloxane molecule of component (A), the groups bonded to silicon atoms, other than the groups containing free radical polymerizable groups, can be listed as monovalent hydrocarbon groups with 1 to 20 carbon atoms, preferably monovalent hydrocarbon groups with 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, excluding aliphatic unsaturated groups. Furthermore, some or all of the hydrogen atoms bonded to the carbon atoms of the aforementioned monovalent hydrocarbon groups may be replaced by other substituents such as halogen atoms.

[0056] As the aforementioned monovalent hydrocarbon group, straight-chain, branched, and cyclic monovalent hydrocarbon groups are all acceptable. For ease of synthesis, alkyl, aryl, and haloalkyl groups can be listed. Specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-hexyl, cyclohexyl, n-octyl, 2-ethylhexyl, n-decyl; phenyl, tolyl, xylyl, naphthyl; chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, etc. Among these, alkyl and aryl groups with 1 to 3 carbon atoms are preferred, and methyl, ethyl, and phenyl groups are more preferred.

[0057] In addition, the molecular structure of component (A) is preferably a straight chain or a branched chain (including a straight chain with branches in a part of the main chain) composed of repeating diorganosiloxane units in the main chain, and is particularly preferred to be a straight chain diorganopolysiloxane with units having the above-mentioned free radical polymerizable groups at both ends of the molecular chain.

[0058] As component (A), a more preferred option is an organopolysiloxane represented by the following formula (1).

[0059] [Chemistry 3]

[0060]

[0061] 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, and more preferably monovalent hydrocarbon groups with 1 to 8 carbon atoms.

[0062] In equation (1), R is used as 1 The monovalent hydrocarbon group having 1 to 20 carbon atoms is preferred, and it can be a straight-chain, branched, or cyclic monovalent hydrocarbon group. Specific examples include straight-chain, branched, or cyclic alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-hexyl, cyclohexyl, n-octyl, 2-ethylhexyl, and n-decyl; and alkenyl groups such as vinyl, allyl (2-propenyl), 1-propenyl, isopropenyl, and butenyl.

[0063] 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.

[0064] Among these, as R 1 Preferably, it is an alkyl group with 1 to 3 carbon atoms, and more preferably methyl or ethyl.

[0065] In formula (1), Ar is an aryl group with 6 to 20 carbon atoms, preferably an aryl group with 6 to 10 carbon atoms. Specific examples include phenyl, biphenyl, naphthyl and other aromatic hydrocarbon groups and furanyl and other aromatic groups containing heteroatoms (O, S, N). Furthermore, the aromatic group may have substituents such as halogen atoms (e.g., chlorine atoms, bromine atoms, fluorine atoms). Among them, Ar is preferably an unsubstituted aryl group, and is particularly preferably phenyl.

[0066] In equation (1), n ​​is a number that satisfies 1 ≤ n ≤ 1000. If further improvement of the viscosity of the composition and the mechanical properties of the cured product is considered, it is preferably a number that satisfies 1 ≤ n ≤ 400, and more preferably a number that satisfies 1 ≤ n ≤ 200. If n is less than 1, it is easy to volatilize; if n is greater than 1000, the viscosity of the composition increases, and shaping becomes difficult.

[0067] In formula (1), m is a number that satisfies 1 ≤ m ≤ 1000. If further improvement of the viscosity of the composition and the mechanical properties of the cured product is considered, it is preferably a number that satisfies 1 ≤ m ≤ 400, and more preferably a number that satisfies 10 ≤ m ≤ 300. If m is less than 1, it is easy to volatilize; if m is greater than 1000, the viscosity of the composition increases, and shaping becomes difficult.

[0068] In formula (1), n+m preferably satisfies the condition 2≦n+m≦2000, more preferably 2≦n+m≦1000, and even more preferably 2≦n+m≦800. If n+m is less than 2, it may be prone to volatilization; if n+m is greater than 2000, the viscosity of the composition increases, and sometimes shaping becomes difficult.

[0069] It should be noted that the order of the siloxane units with n and m is arbitrary.

[0070] In formula (1), A is a group represented by the following formula (2).

[0071] [Chemistry 4]

[0072]

[0073] (In the formula, the dashed line represents the joint end.)

[0074] In equation (2), R 1 Same as above.

[0075] In addition, in equation (2), R 2 Alkylenes having 1 to 20 oxygen or carbon atoms, preferably 1 to 10, more preferably 1 to 5.

[0076] In equation (2), R 2The 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.

[0077] Among these, as R 2 Oxygen atoms, methylene, ethylene, and trimethylene are preferred, with oxygen atoms or ethylene being more preferred.

[0078] R 3 They are independently acryloyloxyalkoxy or methacryloyloxyalkoxy.

[0079] As R 3 The number of carbon atoms in the alkyl (alkylene) group of acryloyloxyalkoxy or methacryloyloxyalkoxy 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 alkyl groups exemplified herein are alkyl groups having 1 to 10 carbon atoms.

[0080] As R 3 Specific examples can be listed by groups represented by the following formulas, but are not limited to these.

[0081] [Chemistry 5]

[0082]

[0083] (In the formula, the dashed line represents the joint end.)

[0084] In the above formula, 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, preferably methylene, ethylene, or trimethylene, and more preferably ethylene.

[0085] In equation (2), a is a number that satisfies 1≦a≦3, preferably 1 or 2.

[0086] (A) The components may be homopolymers having these molecular structures, copolymers having these molecular structures, or mixtures of two or more of these polymers.

[0087] Specific examples of organopolysiloxanes as components of (A) can be listed as those represented by the following formulas (3) and (4), but are not limited to these.

[0088] [Chemistry 6]

[0089]

[0090] (In the formula, Me represents methyl, and Ph represents phenyl. n and m have the same meaning as above, and the order of the siloxane units with n and m is arbitrary.)

[0091] Such organopolysiloxanes can be obtained, for example, by reacting a dimethylsiloxane-diphenylsiloxane-dimethylsiloxane-diphenylsiloxane copolymer with a hydrogenated silanized product of dichlorosilane or dichloromethylsilane and 2-hydroxyethyl acrylate.

[0092] (B) Hydrophobic silica particles

[0093] 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.

[0094] (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.

[0095] (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 cause poor flowability, and can improve the mechanical strength of the cured product.

[0096] The degree of hydrophobicity was determined by the methanol titration method shown below.

[0097] (1) Float the sample in a specified amount of ion-exchange water and add methanol dropwise while stirring.

[0098] (2) Read the total amount of the sample when it is suspended in ion-exchanged water.

[0099] (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.

[0100] The shape of component (B) used in this invention is not particularly limited, but spherical shape is preferred.

[0101] The amount of component (B) relative to 100 parts by mass of component (A) is preferably 10 to 500 parts by mass, more preferably 20 to 300 parts by mass, and even more preferably 30 to 200 parts by mass. If it is 10 parts by mass or more, the effect of improving the mechanical strength of the cured product is sufficiently obtained, and if it is 500 parts by mass or less, the viscosity of the composition does not increase excessively and the flowability is excellent.

[0102] 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.

[0103] 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.

[0104] [(B) Synthesis methods of components]

[0105] Specifically, component (B) used in this invention is preferably synthesized using a method comprising the following three steps.

[0106] Step (α): Synthesis steps of hydrophilic silica particles

[0107] Step (β): The step of surface hydrophobization treatment of hydrophilic silica particles to obtain the intermediate of component (B).

[0108] Step (γ): Further hydrophobic surface treatment of the intermediate of component (B) to obtain hydrophobic silica particles of component (B).

[0109] The following explains each step in turn.

[0110] • Step (α): Synthesis steps of hydrophilic silica particles

[0111] 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.

[0112] Si(OR) 5 4 (I)

[0113] [Chemistry 7]

[0114]

[0115] (where R) 5 These are monovalent hydrocarbon groups with 1 to 6 carbon atoms, which may be the same or different. (k is a number from 1 to 100.)

[0116] 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.

[0117] As a result of R 5 The 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... 5 Preferably, it is methyl, ethyl, n-propyl or n-butyl, more preferably methyl or ethyl.

[0118] In the above general formula (II), k is a number from 1 to 100, preferably a number from 1 to 50, and more preferably a number from 1 to 25.

[0119] 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.

[0120] In addition, specific examples of alkyl silicates represented by general formula (II) include methyl silicate, ethyl silicate, etc., among which methyl silicate is preferred.

[0121] These can be used individually or in combination of two or more.

[0122] Specific examples of the hydrophilic organic solvent used in step (α) are not particularly limited as long as they are a 4-functional silane compound represented by general formula (I), an alkyl silicate ester represented by general formula (II), or a solvent dissolved in 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. Alcohols and cellosols are preferred, and alcohols are more preferred.

[0123] As examples of this class of alcohols, alcohols represented by the following general formula (VI) can be listed.

[0124] R 6 OH (VI)

[0125] (where R) 6 It is a monovalent hydrocarbon group with 1 to 6 carbon atoms.

[0126] 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.

[0127] 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.

[0128] 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 1 mole of the hydroxyl group of the tetrafunctional silane compound represented by general formula (I) and / or the alkyl silicate represented by general formula (II). 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.

[0129] 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. These alkaline substances are dissolved in water in the required amount, and the resulting aqueous solution (alkaline) is then mixed with a hydrophilic organic solvent.

[0130] 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.

[0131] After the alkaline substance is added to the mixture of hydrophilic organic solvent and water, it may be further added to the resulting mixture together with a 4-functional silane compound represented by general formula (I) and / or an alkyl silicate represented by general formula (II), or it may be added to the mixture of water and hydrophilic organic solvent simultaneously with the addition of the 4-functional silane compound and / or the alkyl silicate and the hydrophilic organic solvent.

[0132] 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.

[0133] The resulting mixed solvent dispersion containing hydrophilic silica particles can be used directly in step (β). After adding water to the mixed solvent dispersion containing hydrophilic silica particles, the hydrophilic organic solvent is distilled off to convert it into an aqueous dispersion, thereby hydrolyzing the remaining alkoxy groups. Therefore, it is preferable to convert it into an aqueous dispersion containing hydrophilic silica particles.

[0134] To change the dispersion medium of the silica particle mixed solvent dispersion to water, for example, water can be added to the dispersion and the hydrophilic organic solvent can be distilled off (this operation can be 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.

[0135] • Step (β): Surface treatment steps for hydrophilic silica particles

[0136] 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).

[0137] R 7 Si(OR) 8 3 (III)

[0138] (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.

[0139] In the above general formula (III), R 7The 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.

[0140] 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 8 Preferably, it is methyl, ethyl, or n-propyl, more preferably methyl or ethyl.

[0141] 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.

[0142] The amount of the trifunctional silane compound represented by general formula (III) added is preferably 0.001 to 1 mole, more preferably 0.01 to 0.4 moles, and even more preferably 0.01 to 0.2 moles, relative to 1 mole of Si atoms in the hydrophilic silica particles obtained in step (α). 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.

[0143] 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.

[0144] •Step (γ): (B) Surface treatment steps for component intermediates

[0145] 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 general formula (IV) and a monofunctional silane compound represented by general formula (V) are added to this ketone solvent dispersion. The surface of the intermediate (B) component, i.e., the silica particles, is then treated to obtain hydrophobic silica particles of component (B). Using this step, R is obtained by triorganosilylation of the silanol groups remaining on the surface of the hydrophobic silica particle intermediate. 9 3SiO 1 / 2 The unit is imported into this surface.

[0146] R 9 3SiNHSiR 9 3 (IV)

[0147] R 9 3SiX (V)

[0148] (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.)

[0149] 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 Preferably, it is methyl, ethyl, or n-propyl, more preferably methyl or ethyl. In addition, some or all of the hydrogen atoms of these monovalent hydrocarbon groups may be replaced by halogen atoms such as fluorine, chlorine, or bromine atoms, preferably fluorinated alkyl groups.

[0150] 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.

[0151] Specific examples of silazane compounds represented by general formula (IV) include hexamethyldisilazane, hexaethyldisilazane, tetramethyldivinyldisilazane, etc., with hexamethyldisilazane being preferred.

[0152] 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.

[0153] These can be used individually or in combination.

[0154] 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.

[0155] To change the dispersion medium of the mixed solvent dispersion of the hydrophobic silica particle intermediate obtained in step (β) 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] (C) Photopolymerization initiator

[0160] (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.

[0161] 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, and liquid ethyl phenyl(2,4,6-trimethylbenzoyl)phosphine oxide (Omnirad TPO-L) is more preferred.

[0162] 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 more than 0.01 parts by weight, the surface curing is sufficient, and if it is less than 20 parts by weight, there is no concern about the deterioration of deep curing.

[0163] (D) Ultraviolet absorbers that absorb light in the 360–410 nm range

[0164] 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.

[0165] 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.

[0166] When using a UV absorber, its addition amount 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 0.01 parts by weight or more, the effect of the UV absorber is sufficiently obtained, and if it is 20 parts by weight or less, there is no concern about deterioration of deep curing properties.

[0167] (E) Pigment

[0168] In the compositions of the present invention, various colorants can be added for the purpose of adjusting the curability and coloring the composition.

[0169] 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.

[0170] When using a colorant, the amount added is preferably 0.01 to 20 parts by weight relative to 100 parts by weight of component (A). If it is 0.01 parts by weight or more, the effect of the colorant is fully obtained, and if it is 20 parts by weight or less, there is no concern about deterioration of deep curing properties.

[0171] 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.

[0172] In addition, the compositions of the present invention can also be used by properly mixing with other resin compositions.

[0173] [2] Method for manufacturing organosilicon compositions

[0174] 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.

[0175] The method for manufacturing the organosilicon composition of the present invention particularly preferably includes the following steps (1) and (2).

[0176] Process (1): A process for manufacturing component (B) using a method comprising the following steps (α), (β), and (γ).

[0177] Step (2): The process of mixing components (A) to (C) and other components as needed.

[0178] • Process (1): The process of manufacturing component (B).

[0179] Process (1) is a process of manufacturing component (B) by means of the following steps (α), (β) and (γ).

[0180] 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.

[0181] Si(OR) 5 4 (I)

[0182] [Chemistry 8]

[0183]

[0184] (where R) 5 (and k represent the same meaning as above.)

[0185] 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.

[0186] R 7 Si(OR) 8 3 (III)

[0187] (where R) 7 and R 8 This indicates the same meaning as above.

[0188] 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).

[0189] R 9 3SiNHSiR 9 3 (IV)

[0190] R 9 3SiX (V)

[0191] (where R) 9 (And X represents the same meaning as above.)

[0192] The detailed manufacturing method for component (B) is as described above.

[0193] • Process (2): The process of mixing components (A) to (C).

[0194] 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.

[0195] The organosilicon composition of the present invention can be in the form of a single-liquid or a two-liquid composition. For example, a single-liquid composition can be obtained 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. A mixture can also be obtained by cooling the resulting mixture, adding component (C), and mixing at room temperature for 30 minutes.

[0196] 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•s or less, more preferably 400 Pa•s or less, and even more preferably 100 Pa•s or less. If it exceeds 500 Pa•s, the photoforming properties deteriorate, and sometimes the desired shape cannot be obtained correctly. Furthermore, there is no particular limitation on the lower limit value, but 1 Pa•s or more is preferred, and 2 Pa•s or more is more preferred.

[0197] It should be noted that in this invention, 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).

[0198] [3]Cured product

[0199] The UV-curable silicone composition for photoforming of the present invention can form a cured product with excellent rubber properties through the following process.

[0200] (i) The step of irradiating the photoforming UV-curable silicone composition of the present invention with ultraviolet light to cause the composition to be free-radical cured to obtain a first cured product; and

[0201] (ii) The process of further condensing and curing the first cured product to obtain the second cured product.

[0202] • Process (i): The process that yields the first cured product

[0203] Step (i) is the step of irradiating the UV-curable silicone composition for photoforming of the present invention with ultraviolet light to cure the composition by free radicals and obtain the first cured product.

[0204] In process (i), the light source for the ultraviolet light irradiation can be, for example, a UV-LED lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a carbon arc lamp, a xenon lamp, etc.

[0205] 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.

[0206] When using ultraviolet light irradiation to form the first cured product, for example, for molding the composition of the present invention into a sheet with a thickness of about 2.0 mm, the cumulative light intensity is preferably 1 to 10,000 mJ / cm. 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.

[0207] The tensile strength of the first cured product obtained in step (i) 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 (the same applies below).

[0208] • Process (ii): The process of obtaining the second cured product

[0209] Process (ii) is a process of further condensing and curing the obtained first cured material to obtain a second cured material.

[0210] In the condensation curing of step (ii), the method of applying moisture can promote the hydrolysis and condensation of the above-mentioned components (A) and / or (B). Specifically, it is preferable to allow the condensation curing to proceed for 12 to 36 hours, particularly 18 to 24 hours, in an environment of 50%RH to 85%RH and 20°C to 85°C.

[0211] The tensile strength of the second cured product obtained in step (ii) is 4.5 MPa or more, preferably 5.0 MPa or more. The elongation at break is 250% or more, preferably 300% or more.

[0212] In particular, this invention enables the application of 8000 mJ / cm at 25°C. 2 The tensile strength and elongation at break of the cured material with a thickness of 2.0 mm obtained by irradiating it with ultraviolet light of wavelength 405 nm and then curing it at 85°C and 85%RH for 24 hours are within the above range.

[0213] Example

[0214] The following examples of synthesis, comparative synthesis, embodiments, and comparative examples are provided to illustrate the present invention in more detail. However, the present invention is not limited to these embodiments.

[0215] Furthermore, the compounds used in the examples are described below. In the following formulas, Me represents methyl and Ph represents phenyl.

[0216] [1] Compounding components

[0217] (A) Ingredients

[0218] [Chemistry 9]

[0219]

[0220] (In the formula, the order of the siloxane units in parentheses is arbitrary.)

[0221] (B) Components

[0222] (B-1) Hydrophobic silica particles obtained in Synthesis Example 1

[0223] (B-2) Hydrophobic silica particles obtained in Synthesis Example 2

[0224] (B-3) Hydrophobic silica particles obtained in Synthesis Example 3

[0225] (B-1 ratio) Compare the hydrophobic silica particles obtained in Synthesis Example 1.

[0226] (C) Components

[0227] (C-1) Phenyl (2,4,6-trimethylbenzoyl) ethyl phosphonate (Omnirad TPO-L, manufactured by IGM Resins B.V.)

[0228] [2] Synthesis of hydrophobic silica microparticles

[0229] [Synthesis example 1]

[0230] • Step (α): Synthesis steps of hydrophilic silica particles

[0231] 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.

[0232] • Step (β): Surface treatment steps for hydrophilic silica particles

[0233] 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).

[0234] •Step (γ): (B) Surface treatment steps for component intermediates

[0235] 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).

[0236] [Synthesis example 2]

[0237] Except for replacing 1163.7g of tetramethoxysilane with 901.9g of methyl silicate (Methyl silicate 51 manufactured by Koulcot Co., Ltd.) in step (α) of Synthesis Example 1, the same operation was performed to obtain 470g of hydrophobic silica particles (B-2).

[0238] [Synthesis example 3]

[0239] 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), the same operation was performed to obtain 360 g of hydrophobic silica particles (B-3).

[0240] [Comparative Synthesis Example 1]

[0241] In a 3-liter glass reactor equipped with a stirrer, dropping funnel, and thermometer, 60 g of isopropanol and 100 g of SNOWTEX 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.

[0242] 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 under heating using an evaporator to obtain hydrophobic silica particles (B-1 ratio).

[0243] [Determination Method]

[0244] The obtained hydrophobic silica particles were measured according to methods 1 and 2 described below. The results are shown in Table 1.

[0245] 1. Particle size determination of hydrophobic silica particles

[0246] (1) Take 0.1g of the sample into a glass bottle, add 20g of methanol, and stir.

[0247] (2) Disperse the sample for 10 minutes using an ultrasonic dispersion device to prepare the test sample.

[0248] (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 taken as the particle size.

[0249] 2. Determination of the hydrophobicity of hydrophobic silica particles (methanol titration method)

[0250] (1) Weigh 0.2 mg of the sample into a 500 mL Erlenmeyer flask.

[0251] (2) Add 50 mL of ion-exchanged water to (1) and stir with a stirrer.

[0252] (3) While stirring, add methanol dropwise using a burette and read the total amount of the sample when suspended in ion-exchange water.

[0253] (4) The degree of hydrophobicity was calculated using the following formula.

[0254] Hydrophobicity (%) = [{Methanol added (mL)} / {Methanol added (mL) + Ion exchange water added (mL)}] × 100

[0255] [Table 1]

[0256]

[0257] [3] Manufacturing and evaluation of organosilicon compositions, manufacturing and evaluation of cured products

[0258] [Examples 1-5 and Comparative Examples 1 and 2]

[0259] The above components (A) to (C) were mixed according to the compositions listed in Table 2 to prepare an organosilicon composition. It should be noted that the viscosities of the compositions in Table 2 are values ​​measured using a rotational viscometer at 23°C.

[0260] 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, resulting in the first cured product.

[0261] Then, the first cured product was treated at 85℃ and 85%RH for 24 hours to obtain the second cured product.

[0262] The hardness, elongation at break and tensile strength of the first and second cured sheets (2.0 mm thick) were determined according to JIS K 6249:2003.

[0263] [Table 2]

[0264]

[0265] As shown in Table 2, the UV-curable silicone compositions prepared in Examples 1 to 5 have low viscosity that can be applied to photoforming methods, and the cured products obtained by UV irradiation and moisture treatment have good mechanical properties.

[0266] On the other hand, in Comparative Example 1, in which the radical polymerizable group in component (A) was changed to a group consisting of an oxygen atom directly bonded to a silicon atom and a dimethylsilyl group bonded to a silicon atom, the condensation reactivity of moisture was low, resulting in poor physical properties of the second cured product. In addition, in Comparative Example 2, in which silica particles with insufficient hydrophobicity were used, the viscosity of the composition increased significantly, and the curing properties were also insufficient.

Claims

1. A UV-curable silicone composition for photoforming, comprising: (A) An organopolysiloxane having two or more radical polymerizable groups in one molecule, wherein an oxygen atom is directly bonded to a silicon atom and bonded to that silicon atom, wherein, The groups containing free radical polymerizable groups do not include groups containing heteroatoms other than oxygen atoms. (B) Hydrophobic silica particles with an average particle size of 10 nm to 1000 nm and a hydrophobicity of over 60% obtained by methanol titration, and (C) Photopolymerization initiator, For this composition, at 25°C and 8000 mJ / cm 2 After being irradiated with ultraviolet light of wavelength 405nm, the material was cured at 85℃ and 85%RH for 24 hours. The resulting cured material with a thickness of 2.0mm had a tensile strength of over 4.5MPa and an elongation at break of over 300%.

2. The UV-curable silicone composition for photoforming according to claim 1, wherein, (A) is an organopolysiloxane having 2 to 6 acryloyloxyalkoxy or methacryloyloxyalkoxy atoms bonded to silicon atoms in one molecule.

3. The UV-curable silicone composition for photoforming according to claim 1, wherein, (A) The component is an organopolysiloxane represented by the following formula (1), [Chemistry 1] In the formula, n is a number satisfying 1 ≤ n ≤ 1000, m is a number satisfying 1 ≤ m ≤ 1000, the order of the siloxane units with n and m is arbitrary, Ar is an aryl group with 6 to 20 carbon atoms, and R... 1 Each group consists of a monovalent hydrocarbon group having 1 to 20 carbon atoms, and A is a group represented by the following formula (2). [Chemistry 2] In the formula, R 1 Similar to the above, R 2 R is an alkylene group having 1 to 20 carbon atoms or an oxygen atom. 3 They are independently acryloyloxyalkoxy or methacryloyloxyalkoxy, where a is a number that satisfies 1 ≤ a ≤ 3, and the dashed line represents the bonding end.

4. The UV-curable silicone composition for photoforming according to any one of claims 1 to 3, wherein, Relative to 100 parts by mass of component (A), it contains 10 to 500 parts by mass of component (B) and 0.01 to 20 parts by mass of component (C).

5. The UV-curable silicone composition for photoforming according to any one of claims 1 to 4, wherein, The viscosity at 23°C is below 500 Pa•s.

6. A cured product, which is a cured product of a UV-curable silicone composition for photoforming, said UV-curable silicone composition for photoforming containing: (A) An organopolysiloxane having two or more radical polymerizable groups in one molecule, wherein an oxygen atom is directly bonded to a silicon atom and bonded to that silicon atom, wherein, The groups containing free radical polymerizable groups do not include groups containing heteroatoms other than oxygen atoms. (B) Hydrophobic silica particles with an average particle size of 10 nm to 1000 nm and a hydrophobicity of over 60% obtained by methanol titration, and (C) Photopolymerization initiator, The cured material has a tensile strength of 4.5 MPa or more at a thickness of 2.0 mm and an elongation at break of 300% or more.

7. A curing method, which is a curing method for the UV-curable silicone composition for photoforming according to any one of claims 1 to 5, comprising: (i) The step of irradiating the photoforming UV-curable silicone composition according to any one of claims 1 to 5 with ultraviolet light to cause the composition to undergo free radical curing, thereby obtaining a first cured product; and (ii) The process of further condensing and curing the obtained first cured product to obtain a second cured product.

8. The curing method according to claim 7, wherein, The condensation curing in process (ii) is a curing process that utilizes moisture.

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