Photocationically curable silicone composition, silicone cured product, and optical device

Abstract

To provide a silicone composition that has a high refractive index, that can be cured with ultraviolet irradiation, and that provides a cured product having excellent hardness and strength.SOLUTION: There is provided a photo-cationically curable silicone composition comprising: (A) an epoxy silicone represented by following general formula (1) (where Me is a methyl group, Ph is a phenyl group, RE is a monovalent substituent containing an epoxy group with 2-16 carbon atoms, R1 is a monovalent hydrocarbon group with 1-12 carbon atoms containing no aliphatic unsaturated bonds, R2 is a methyl or phenyl group, R3 is a divalent hydrocarbon group with 1-5 carbon atoms or oxygen atoms, h is an integer of 1 to 10, "i" is an integer of 0 to 10, j is an integer of 0 to 10, and k is an integer of 1 to 100); and (B) a photocationic polymerization initiator, wherein the content of phenyl groups bonded to silicon atoms in the component (A) is not less than 40 mol% with respect to the total number of monovalent substituents bonded to silicon atoms in the component (A).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a photocationically curable silicone composition, a cured product thereof, and an optical device using the same. [Background technology]

[0002] Light-emitting diode (LED) lamps, known as optical semiconductor devices, are constructed by encapsulating an LED mounted on a substrate with a transparent resin encapsulant. Addition-curable silicone compositions are widely used as encapsulants due to their excellent heat resistance.

[0003] In recent years, the miniaturization, thinning, and high functionality of electronic devices have led to higher performance demands for optical materials. For example, microlens materials, which are widely used in optical communications, require high hardness, high refractive index, and high strength to achieve efficient light collection and diffusion. Furthermore, to save energy, there is a growing need for photocurable resins that can be cured at low temperatures by irradiation with light such as ultraviolet light, in order to minimize the heating process required for curing materials.

[0004] Furthermore, in the display field, quantum dot displays, which utilize quantum dots with excellent wavelength conversion efficiency and feature low power consumption and high resolution, are being developed. However, these quantum dots contain sulfur, which acts as an addition catalyst poison, and this causes the problem of inhibiting the cure of conventional addition-curing silicones. In addition, quantum dots have low heat resistance and are not suitable for manufacturing processes that require heat curing.

[0005] To address these problems, a radically curable silicone composition that can be cured at low temperatures has been proposed (Patent Document 1), but its mechanical properties are insufficient for applications requiring high hardness and strength. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-1296 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a silicone composition that has a high refractive index, is curable by ultraviolet irradiation, and gives a cured product with excellent hardness and strength. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a cationically curable silicone composition, comprising: (A) an epoxysilicone represented by the following general formula (1): [ka] (wherein Me is a methyl group, Ph is a phenyl group, and R E are each independently a monovalent substituent containing an epoxy group having 2 to 16 carbon atoms, and R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms and no aliphatic unsaturated bond, and R 2 are each independently a methyl group or a phenyl group, and R 3 are each independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 5 carbon atoms or an oxygen atom, h is an integer of 1 to 10, i is an integer of 0 to 10, j is an integer of 0 to 10, and k is an integer of 1 to 100. The arrangement of the siloxane units in the parentheses followed by h and i is arbitrary.), and (B) Photocationic polymerization initiator and The present invention provides a photocationically curable silicone composition in which the content of phenyl groups bonded to silicon atoms in component (A) is 40 mol % or more relative to the total number of monovalent substituents bonded to silicon atoms in component (A).

[0009] The photocationically curable silicone composition of the present invention has a high refractive index, can be cured by ultraviolet irradiation, and gives a cured product with excellent hardness and strength.

[0010] In addition, in the general formula (1), R 2 is a phenyl group, and R 3 It is preferred that i is an alkylene group having 1 to 3 carbon atoms, i is 0, j is 1, and k is 1.

[0011] Such a photocationically curable silicone composition will give a cured product with a higher refractive index and superior hardness and strength.

[0012] Furthermore, (C) an epoxy silicone other than the component (A) may be contained.

[0013] By using such component (C), the physical properties of the resulting cured product can be easily adjusted.

[0014] The present invention also provides a cured silicone product, which is a cured product of the above-described photocationically curable silicone composition.

[0015] Furthermore, the present invention provides an optical device comprising the above-mentioned cured silicone product.

[0016] The silicone cured product of the present invention has excellent properties such as a high refractive index, high hardness, and high strength, making it suitable for optical device applications such as sealing materials, lens materials, and coating materials. [Effects of the Invention]

[0017] The photocationically curable silicone composition of the present invention can be cured by exposure to ultraviolet light, and the cured product has excellent properties such as a high refractive index, high hardness, and high strength, making it suitable for optical device applications such as encapsulants, lens materials, and coating materials. DETAILED DESCRIPTION OF THE INVENTION

[0018] As described above, there has been a need for the development of a silicone composition that has a high refractive index, is curable by ultraviolet irradiation, and gives a cured product with excellent hardness and strength.

[0019] As a result of extensive research into achieving the above object, the present inventors discovered that a silicone resin composition containing components (A) and (B) described below could solve the above problems, and thus completed the present invention.

[0020] That is, the present invention provides a cationically curable silicone composition, (A) an epoxysilicone represented by the following general formula (1): [ka] (wherein Me is a methyl group, Ph is a phenyl group, and R E are each independently a monovalent substituent containing an epoxy group having 2 to 16 carbon atoms, and R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms and no aliphatic unsaturated bond, and R 2 are each independently a methyl group or a phenyl group, and R 3 are each independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 5 carbon atoms or an oxygen atom, h is an integer of 1 to 10, i is an integer of 0 to 10, j is an integer of 0 to 10, and k is an integer of 1 to 100. The arrangement of the siloxane units in the parentheses followed by h and i is arbitrary.), and (B) Photocationic polymerization initiator and The photocationically curable silicone composition has a content of phenyl groups bonded to silicon atoms in component (A) of 40 mol % or more relative to the total number of monovalent substituents bonded to silicon atoms in component (A).

[0021] The present invention will be described in detail below, but the present invention is not limited thereto.

[0022] [Photocationic curable silicone composition] The photocationically curable silicone composition of the present invention contains the following components (A) and (B) as essential components. This composition may further contain optional components as needed in addition to the essential components. Each component is described in detail below.

[0023] [Component (A)] The component (A) is an epoxy silicone represented by the following general formula (1). [ka] (wherein Me is a methyl group, Ph is a phenyl group, and R E are each independently a monovalent substituent containing an epoxy group having 2 to 16 carbon atoms, and R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms and no aliphatic unsaturated bond, and R 2 are each independently a methyl group or a phenyl group, and R 3 are each independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 5 carbon atoms or an oxygen atom, h is an integer of 1 to 10, i is an integer of 0 to 10, j is an integer of 0 to 10, and k is an integer of 1 to 100. The arrangement of the siloxane units in the parentheses followed by h and i is arbitrary.

[0024] R E Specific examples of the monovalent substituent containing an epoxy group represented by the formula (1) include groups represented by the following formula (2) and the following formula (3), but are not limited thereto.

[0025] [ka] (In the formula, * represents a bond to an adjacent silicon atom.)

[0026] R 1Examples of the monovalent hydrocarbon group represented by the formula (I) include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-decyl, cyclopentyl, and cyclohexyl groups; aryl groups having 6 to 12 carbon atoms, such as phenyl and naphthyl groups; alkylaryl groups having 7 to 12 carbon atoms, such as tolyl, xylyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, and hexylphenyl groups; and aralkyl groups having 7 to 12 carbon atoms, such as benzyl and phenethyl groups, with a methyl group or a phenyl group being preferred.

[0027] R 3 Examples of the divalent hydrocarbon group represented by the formula (I) include methylene, ethylene, trimethylene, tetramethylene, and pentamethylene groups, with methylene, ethylene, and trimethylene being preferred. These divalent hydrocarbon groups may contain an oxygen atom (O), and may partially form an ether group, for example, -O-.

[0028] The content of phenyl groups bonded to silicon atoms in component (A) is 40 mol% or more, and preferably 50 mol% or more, relative to the total number of monovalent substituents bonded to silicon atoms in component (A). A phenyl group content of less than 40 mol% may result in a decrease in refractive index, hardness, strength, etc. On the other hand, there is no particular upper limit to the content of phenyl groups bonded to silicon atoms relative to the total number of monovalent substituents bonded to silicon atoms in component (A), but it can be, for example, less than 100 mol%, preferably 90 mol% or less, more preferably 80 mol% or less, even more preferably 70 mol% or less, and extremely preferably 60 mol% or less.

[0029] h is an integer from 1 to 10, preferably an integer from 1 to 5, and more preferably 3. i is an integer from 0 to 10, and preferably 0. j is an integer from 0 to 10, preferably an integer from 1 to 10, and more preferably 1. k is an integer from 1 to 100, preferably an integer from 1 to 10, and more preferably 1.

[0030] From the above, it can be seen that the component (A) is a compound represented by the general formula (1) where R 2 is a phenyl group, and R 3 It is preferred that i is an alkylene group having 1 to 3 carbon atoms, i is 0, j is 1, and k is 1.

[0031] Suitable examples of component (A) are shown below, but are not limited to these.

[0032] [ka]

[0033] The component (A) may be used alone or in combination of two or more types.

[0034] [(B) Component] The component (B) is a photocationic polymerization initiator that generates cationic species upon irradiation with ultraviolet light. Any compound having this function can be used without any particular limitation. For example, R 4 2I + Y - , R 4 3S + Y - , R 4 3Se + Y - , R 4 4P + Y - , R 4 N + Y - (R 4 represents an aryl group optionally substituted with an alkyl group; Y - is SbF6 - , AsF6 - , PF6 - , BF4 - , HSO4 - , ClO4 - Examples of the anions include diaryliodonium salts, triarylsulfonium salts, triarylselenonium salts, tetraarylphosphonium salts, and aryldiazonium salts represented by the formula (anions such as those shown below).

[0035] Among these, bis[4-n-alkylphenyl]iodonium hexafluoroantimonate represented by the following formula is preferred.

[0036] [ka]

[0037] The blending amount of component (B) is preferably 0.1 to 20.0 parts by mass, and more preferably 0.1 to 5.0 parts by mass, per 100 parts by mass of component (A). When the blending amount of component (B) is 0.1 part by mass or more, sufficient curability can be reliably obtained.

[0038] [(C) component] The photocationically curable silicone composition of the present invention may contain, as component (C), an epoxysilicone other than component (A).

[0039] Examples of such epoxysilicones include, but are not limited to, those represented by the following general formulas (4) to (6).

[0040] [ka] (In the formula, R E , R 1 , R 2 represents R in the general formula (1) listed in the component (A) above. E , R 1 , R 2 where p is an integer of 1 to 5, q is an integer of 3 to 7, r is an integer of 1 to 5, s is an integer of 4 to 82, and t is an integer of 1 to 40.

[0041] When component (C) is used, the blending amount is preferably 1 to 50 parts by mass per 100 parts by mass of component (A).

[0042] [Other ingredients] In addition to the above components (A) to (C), the photocationically curable silicone composition of the present invention may contain, as needed, an epoxy-based diluent, an organic solvent, a silicone, an antioxidant, a light stabilizer, an adhesion aid, a reinforcing filler, a dye, a pigment, or the like.

[0043] [Curing method and conditions] The photocationically curable silicone composition of the present invention can be cured by irradiation with light such as ultraviolet light.

[0044] Examples of ultraviolet light sources include UV LED lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, carbon arc lamps, and xenon lamps. The irradiation dose (integrated light amount) of ultraviolet light is preferably 100 to 18,000 mJ / cm for a sheet formed from the composition of the present invention to a thickness of about 2.0 mm. 2 and more preferably 3000 to 18000 mJ / cm 2 That is, the illuminance is 100mW / cm 2 When ultraviolet light is used, the composition can be cured by irradiating the composition with ultraviolet light for about 1 to 180 seconds.

[0045] Furthermore, curing may be accelerated by heating at 40°C to 200°C after irradiation with light such as ultraviolet light.

[0046] [Cured silicone products and optical devices] The present invention also provides a silicone cured product that is a cured product of the above-mentioned photocationically curable silicone composition, and an optical device that includes the silicone cured product.

[0047] The photocationically curable silicone composition of the present invention can be cured by exposure to ultraviolet light, and the cured product has excellent properties such as a high refractive index, high hardness, and high strength, making it suitable for optical device applications such as encapsulants, lens materials, and coating materials. [Example]

[0048] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. The viscosity values ​​are measured at 25°C using a B-type rotational viscometer.

[0049] [Synthesis Example 1] 400 g of the organohydrogentrisiloxane represented by structural formula (7) below and 450 g of toluene were placed in a four-neck flask equipped with a stirrer, condenser, reflux condenser, dropping funnel, and thermometer, and the mixture was heated to 85°C using an oil bath.

[0050] To this was added 0.57 g of a toluene solution of platinum hexachloride 1,3-divinyltetramethyldisiloxane complex (platinum concentration 0.5% by mass), and while stirring, a solution of 545.5 g of organopolysiloxane represented by formula (8) below and 450 g of toluene was added dropwise over 1 hour. After the addition was complete, the mixture was stirred at 90°C for 2.5 hours. The toluene was distilled off under reduced pressure, yielding 926 g of a colorless, transparent, oily organohydrogenpolysiloxane represented by formula (9) below (viscosity at 25°C: 11,820 mPa s).

[0051] [ka]

[0052] A four-neck flask equipped with a stirrer, a condenser, a reflux condenser, a dropping funnel, and a thermometer was charged with 37.6 g of 1,2-epoxy-4-vinylcyclohexane (trade name: CEL2000, manufactured by Daicel Corporation), 70 g of toluene, 70 g of isopropyl alcohol, 0.115 g of a toluene solution of platinum hexachloride 1,3-divinyltetramethyldisiloxane complex (platinum concentration: 0.5% by mass), and 0.201 g of acetonitrile, and the mixture was heated to 80°C using an oil bath.

[0053] To this was added dropwise over 1 hour a solution of 250 g of organohydrogenpolysiloxane represented by formula (9) above and 130 g of toluene. After the addition was complete, the mixture was stirred at 80°C for 2 hours. The toluene was removed by distillation under reduced pressure to obtain 281 g of epoxy silicone (A-1) as a colorless, transparent oil (viscosity at 25°C: 16,040 mPa s). In epoxy silicone (A-1), the content of phenyl groups bonded to silicon atoms was 50 mol% relative to the total number of monovalent substituents bonded to silicon atoms.

[0054] [ka]

[0055] [Synthesis Example 2] Into a four-neck flask equipped with a stirrer, a condenser, a reflux condenser, a dropping funnel, and a thermometer, 34.6 g of 1-allyloxy-2,3-epoxypropane (trade name: allyl glycidyl ether, manufactured by Tokyo Chemical Industry Co., Ltd.) and 140 g of toluene were placed and heated to 85°C.

[0056] To this was added 0.171 g of a toluene solution of platinum hexachloride 1,3-divinyltetramethyldisiloxane complex (platinum concentration 0.5% by mass), and while stirring, a solution of 250 g of organohydrogenpolysiloxane represented by formula (9) above and 130 g of toluene was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was stirred at 85°C for 2 hours. The toluene was distilled off under reduced pressure to yield 266 g of epoxy silicone (A-2) as a colorless, transparent oil (viscosity at 25°C: 7,960 mPa·s). The content of phenyl groups bonded to silicon atoms in epoxy silicone (A-2) was 50 mol% relative to the total number of monovalent substituents bonded to silicon atoms.

[0057] [ka]

[0058] [Synthesis Example 3] 191 g of organohydrogendisiloxane represented by the following structural formula (10) and 145 g of toluene were placed in a four-neck flask equipped with a stirrer, a condenser, a reflux condenser, a dropping funnel, and a thermometer, and the mixture was heated to 85°C using an oil bath.

[0059] To this was added 0.084 g of a toluene solution of platinum hexachloride 1,3-divinyltetramethyldisiloxane complex (platinum concentration 0.5% by mass), and 88.2 g of 1,2-epoxy-4-vinylcyclohexane (trade name: CEL2000, manufactured by Daicel Corporation) was added dropwise over 1 hour with stirring. After completion of the dropwise addition, the mixture was stirred at 85°C for 3 hours. The toluene was distilled off under reduced pressure to yield 174 g of organohydrogendisiloxane represented by the following structural formula (11).

[0060] [ka]

[0061] 12.5 g of the organohydrogendisiloxane represented by structural formula (11) above and 260 g of toluene were placed in a four-neck flask equipped with a stirrer, a condenser, a reflux condenser, a dropping funnel, and a thermometer, and the mixture was heated to 85°C using an oil bath.

[0062] To this was added 0.158 g of a toluene solution of platinum hexachloride 1,3-divinyltetramethyldisiloxane complex (platinum concentration 0.5% by mass), and while stirring, a solution of 250 g of organopolysiloxane represented by formula (12) below and 100 g of toluene was added dropwise over 1 hour. After completion of the dropwise addition, the mixture was stirred at 85°C for 3 hours. The toluene was distilled off under reduced pressure to yield 253 g of epoxy silicone (C-1) as a colorless, transparent oil (viscosity at 25°C: 10,690 mPa s). The content of phenyl groups bonded to silicon atoms in epoxy silicone (C-1) was 28 mol% relative to the total number of monovalent substituents bonded to silicon atoms.

[0063] [ka] (In the formula, the order of the siloxane units in parentheses is not specified.)

[0064] [Synthesis Example 4] 28.3 g of 1,2-epoxy-4-vinylcyclohexane (trade name: CEL2000, manufactured by Daicel Corporation), 160 g of toluene, 28 g of isopropyl alcohol, 0.112 g of a toluene solution of platinum hexachloride 1,3-divinyltetramethyldisiloxane complex (platinum concentration: 0.5% by mass), and 0.112 g of acetonitrile were placed in a four-neck flask equipped with a stirrer, a condenser, a reflux condenser, a dropping funnel, and a thermometer, and the mixture was heated to 80°C using an oil bath.

[0065] To this was added dropwise 100 g of organohydrogenpolysiloxane represented by the following formula (13) over a period of 2 hours. After the addition was complete, the mixture was stirred at 80°C for 3 hours. The toluene was removed by distillation under reduced pressure, yielding 169 g of a colorless, transparent, oily epoxysilicone (C-2) (viscosity at 25°C: 330 mPa s).

[0066] [ka]

[0067] [Synthesis Example 5] A four-neck flask equipped with a stirrer, a condenser, a reflux condenser, a dropping funnel, and a thermometer was charged with 82.0 g of 1,2-epoxy-4-vinylcyclohexane (trade name: CEL2000, manufactured by Daicel Corporation), 127 g of toluene, 39 g of isopropyl alcohol, 0.072 g of a toluene solution of platinum hexachloride 1,3-divinyltetramethyldisiloxane complex (platinum concentration: 0.5% by mass), and 0.126 g of acetonitrile, and the mixture was heated to 80°C using an oil bath.

[0068] To this was added dropwise 100 g of the organohydrogensiloxane represented by formula (7) over a period of 2 hours. After the addition was complete, the mixture was stirred at 80°C for 3 hours. The toluene was removed by distillation under reduced pressure, yielding 169 g of a colorless, transparent, oily epoxysilicone (C-3) (viscosity at 25°C: 330 mPa s).

[0069] [ka]

[0070] [Synthesis Example 6] A four-neck flask equipped with a stirrer, a condenser, a reflux condenser, a dropping funnel, and a thermometer was charged with 219.3 g of 1,2-epoxy-4-vinylcyclohexane (trade name: CEL2000, manufactured by Daicel Corporation), 307 g of toluene, 44 g of isopropyl alcohol, 0.219 g of a toluene solution of platinum hexachloride 1,3-divinyltetramethyldisiloxane complex (platinum concentration: 0.5% by mass), and 0.219 g of acetonitrile, and the mixture was heated to 80°C using an oil bath.

[0071] To this was added dropwise 160 g of organohydrogensiloxane represented by the following formula (14) over 1 hour. After the addition was complete, the mixture was stirred at 75°C for 15 hours. The toluene was removed by distillation under reduced pressure, yielding 356 g of epoxysilicone (C-4) as a colorless, transparent oil (viscosity at 25°C: 54 mPa s).

[0072] [ka]

[0073] [Synthesis Example 7] Into a four-neck flask equipped with a stirrer, a condenser, a reflux condenser, a dropping funnel, and a thermometer, 190.1 g of 1,2-epoxy-4-vinylcyclohexane (trade name: CEL2000, manufactured by Daicel Corporation) and 340 g of toluene were placed, and the mixture was heated to 85°C using an oil bath.

[0074] To this was added 0.204 g of a toluene solution of platinum hexachloride 1,3-divinyltetramethyldisiloxane complex (platinum concentration 0.5% by mass), and while stirring, 150 g of organohydrogenpolysiloxane represented by formula (15) below was added dropwise over 1 hour. After the addition was complete, the mixture was stirred at 85°C for 5 hours. The toluene was distilled off under reduced pressure, yielding 304 g of epoxysilicone (C-5) as a colorless, transparent oil (viscosity at 25°C: 16,640 mPa s).

[0075] [ka]

[0076] [Examples 1 to 5 and Comparative Examples 1 and 2] The components shown below were mixed in the proportions (parts by mass) shown in Table 1 to prepare photocationically curable silicone compositions.

[0077] (A) Component: (A-1) Epoxysilicone obtained in Synthesis Example 1 [ka]

[0078] (A-2) Epoxysilicone obtained in Synthesis Example 2 [ka]

[0079] (B) Ingredients: (B-1) A mixture of 92% by mass of bis[4-n-alkylphenyl]iodonium hexafluoroantimonate represented by the following formula and 8% by mass of acetonitrile [ka]

[0080] (C) Component (C-1) Epoxysilicone obtained in Synthesis Example 3 [ka] (In the formula, the order of the siloxane units in parentheses is not specified.)

[0081] (C-2) Epoxysilicone obtained in Synthesis Example 4 [ka]

[0082] (C-3) Epoxysilicone obtained in Synthesis Example 5 [ka]

[0083] (C-4) Epoxysilicone obtained in Synthesis Example 6 [ka]

[0084] (C-5) Epoxysilicone obtained in Synthesis Example 7 [ka]

[0085] [Table 1]

[0086] The photocationically curable silicone compositions obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were evaluated by the following methods, and the results are shown in Table 2.

[0087] [Refractive Index] The refractive index (nD25) of the photocationically curable silicone composition was measured at 25°C using a digital refractometer (model RX-9000i) manufactured by Atago Co., Ltd., using sodium D line as a light source.

[0088] [Hardness] The photocationic curing silicone composition was exposed to ultraviolet light with a wavelength of 365 nm at an irradiation dose of 18,000 mJ / cm using an Eye UV electronic control device (model UBX0601-01) manufactured by Eye Graphics Co., Ltd. 2 The composition was irradiated with ultraviolet light at 25°C in the atmosphere so as to obtain a cured product having a thickness of 2 mm. The hardness of the cured product was measured in accordance with JIS K6253 as Type A hardness.

[0089] [Tensile strength] For a 2 mm thick cured product prepared under the same conditions as in the hardness test, the maximum breaking strength in the tensile direction was measured at 23°C using a Strograph (model VG1-E) manufactured by Toyo Seiki Co., Ltd.

[0090] [Table 2]

[0091] As shown in Table 2, in Examples 1 to 5, which used the photocationically curable silicone composition of the present invention, the cured products obtained had a high refractive index and excellent hardness and strength. On the other hand, in Comparative Example 1, in which component (A) was changed to a long-chain epoxy silicone (C-1) with a low phenyl group content, the hardness and tensile strength were poor. Furthermore, in Comparative Example 2, in which component (A) was changed to an epoxy silicone (C-2) without phenyl groups, the tensile strength was poor.

[0092] This specification includes the following inventions.

[0093] [1]: A photocationic curable silicone composition, comprising: (A) an epoxysilicone represented by the following general formula (1): [ka] (wherein Me is a methyl group, Ph is a phenyl group, and R E are each independently a monovalent substituent containing an epoxy group having 2 to 16 carbon atoms, and R 1 are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms and no aliphatic unsaturated bond, and R2 are each independently a methyl group or a phenyl group, and R 3 are each independently a substituted or unsubstituted divalent hydrocarbon group of 1 to 5 carbon atoms or an oxygen atom, h is an integer from 1 to 10, i is an integer from 0 to 10, j is an integer from 0 to 10, and k is an integer from 1 to 100. The siloxane units in the parentheses followed by h and i may be arranged in any order.), and (B) a cationic photopolymerization initiator, wherein the content of phenyl groups bonded to silicon atoms in component (A) is 40 mol % or more, relative to the total number of monovalent substituents bonded to silicon atoms in component (A).

[0094] [2]: In the general formula (1), R 2 is a phenyl group, and R 3 is an alkylene group having 1 to 3 carbon atoms, i is 0, j is 1, and k is 1.

[0095] [3]: The photocationically curable silicone composition according to [1] or [2] above, further comprising (C) an epoxysilicone other than the component (A).

[0096] [4]: A silicone cured product characterized by being a cured product of the photocationically curable silicone composition described in [1], [2], or [3] above.

[0097] [5]: An optical device comprising the silicone cured product according to [4] above.

[0098] The present invention is not limited to the above-described embodiments, which are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that provides similar effects is included within the technical scope of the present invention.

Claims

1. A photocationically curable silicone composition, comprising: (A) an epoxysilicone represented by the following general formula (1): 【Chemistry 1】 (wherein Me is a methyl group, Ph is a phenyl group, and R Ｅ are each independently a monovalent substituent containing an epoxy group having 2 to 16 carbon atoms, and R １ are each independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms and no aliphatic unsaturated bond, and R ２ are each independently a methyl group or a phenyl group, and R ３ are each independently a substituted or unsubstituted divalent hydrocarbon group having 1 to 5 carbon atoms, h is an integer of 1 to 10, i is an integer of 0 to 10, j is an integer of 1 to 10, and k is an integer of 1 to 100. The arrangement of the siloxane units in the parentheses followed by h and i is arbitrary.), and (B) Photocationic polymerization initiator and A photocationically curable silicone composition, characterized in that the content of phenyl groups bonded to silicon atoms in component (A) is 40 mol % or more, based on the total number of monovalent substituents bonded to silicon atoms in component (A).

2. In the general formula (1), R ２ is a phenyl group, and R ３ 2. The photocationically curable silicone composition according to claim 1, wherein: is an alkylene group having 1 to 3 carbon atoms; i is 0; j is 1; and k is 1.

3. 2. The photocationically curable silicone composition according to claim 1, further comprising (C) an epoxysilicone other than component (A).

4. A silicone cured product, which is a cured product of the photocationically curable silicone composition according to any one of claims 1 to 3.

5. An optical device comprising the silicone cured product according to claim 4.

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