JP2025019645A - Silicone resin composition, cured product of the silicone resin composition, and optical semiconductor device - Google Patents

Abstract

To provide an addition reaction-curable silicone resin cured product that increases a glass transition temperature Tg and offers high resistance to gas permeation.SOLUTION: A silicone resin composition comprises: (A) a branched-chain organopolysiloxane, represented by the following average formula, with aryl groups bound to silicon atoms making up 10% or more of the total number of substituents bound to silicon atoms, and with at least two silicon-bonded alkenyl groups being present in each molecule, (SiO4/2)a(R1SiO3/2)b(R2SiO3/2)c(R2R3SiO2/2)d, (B) a hydrosilyl group-containing organic silicon compound with two or more SiH groups in one molecule, in such an amount that the ratio of the number of hydrosilyl groups in component (B) to the number of alkenyl groups in component (A) is 0.1 to 4.0; and (C) a platinum group metal-based catalyst in a catalytic amount.SELECTED DRAWING: None

Description

The present invention relates to a silicone resin composition that gives a cured product with high gas permeability resistance, and an optical semiconductor device having the cured product.

Organopolysiloxanes have excellent heat resistance, cold resistance, electrical insulation, light resistance, weather resistance, light transparency, gas permeability, and chemical stability, and are used as excellent materials in a wide variety of fields, from the electrical and electronic fields to transportation equipment, office supplies, cosmetics, and the medical field. In particular, addition-curing silicone resin compositions (hereinafter referred to as silicone resin compositions), which have excellent transparency, are used as materials for optical semiconductors such as LEDs.

In recent years, optical semiconductor devices have been used as LED lighting for outdoor lighting or vehicle lighting. The encapsulant for such optical semiconductor devices generally uses a resin such as silicone resin that has high gas or moisture permeability. Therefore, in harsh environments such as outdoors, there is a problem that the silver plating layer used as the electrode or reflective layer of the optical semiconductor device corrodes due to sulfur-based gas or moisture, resulting in a significant decrease in brightness.

As a countermeasure, the introduction of aromatic substituents such as phenyl groups to increase the refractive index and improve gas permeability resistance has been investigated (Patent Document 1), but due to steric hindrance and other factors, there is a limit to the percentage of phenyl groups that can be contained in one silicone molecule. In addition, when phenyl silicone is normally used, the glass transition temperature Tg is about 50°C, and the elastic modulus drops sharply around that temperature, which causes a significant drop in gas permeability resistance in the medium to high temperature range.

In addition, known corrosion inhibitors for preventing metal corrosion include compounds of nitrogen-containing aromatic hydrocarbons such as benzotriazole and 5-methylbenzimidazole, and metal complexes of zinc and the like, and attempts to add these corrosion inhibitors are also being considered. However, there is a problem in that discoloration of the corrosion inhibitors and metal ligands significantly reduces the heat resistance of the resin (Patent Document 2).

Furthermore, resin compositions using polyorganosiloxanes containing thiazole compounds or triazine compounds in the siloxane skeleton have also been developed, but depending on the curing method of the silicone resin composition, there is a risk that curing may be inhibited, and in addition-curing resin compositions, they act on platinum and other metals, becoming a catalyst poison, making them difficult to use (Patent Document 3).

JP 2014-185293 A JP 2012-056251 A JP 2012-251058 A

The present invention was made in consideration of the above problems, and aims to provide an addition reaction curing type silicone resin cured product that has an increased glass transition temperature Tg and excellent gas permeability resistance.

As a result of intensive research aimed at solving the above problems, the present inventors have discovered that an addition reaction curable silicone resin composition containing a branched organopolysiloxane having a specific ratio of RSiO3 _/2 units (T units) and/or _{R2SiO2 /2} units (D units) having alkenyl groups and aryl groups can increase the glass transition temperature Tg of the cured product and provide a silicone resin cured product with excellent gas permeability resistance, thereby completing the present invention.

That is, the present invention provides
(A) a branched-chain organopolysiloxane represented by the following average formula, which has 10% or more aryl groups bonded to silicon atoms relative to the total number of substituents bonded to silicon atoms and has at least two silicon-bonded alkenyl groups per molecule:
(SiO _4/2 ) _a (R ¹ SiO _3/2 ) _b (R ² SiO _3/2 ) _c (R ² R ³ SiO _2/2 ) _d (1)
(In the above formula, R ¹ 's are each independently a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms other than an alkenyl group, or an aryl group having 6 to 10 carbon atoms; R ² 's are each independently an alkenyl group having 2 to 10 carbon atoms; R ³ 's are each independently a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms other than an alkenyl group, or an aryl group having 6 to 10 carbon atoms; and a, b, c, and d are numbers that satisfy a≧0, b>0, c≧0, and d≧0, with the proviso that c+d>0 and a+b+c+d=1.)
The present invention provides a silicone resin composition comprising: (B) a hydrosilyl group-containing organosilicon compound having two or more SiH groups per molecule, in an amount such that the ratio of the number of hydrosilyl groups in component (B) to the number of alkenyl groups in component (A) is 0.1 to 4.0; and (C) a catalytic amount of a platinum group metal catalyst.

The silicone resin composition of the present invention further comprises at least one of the components shown in [1] to [3] below.
[1] The silicone resin composition, wherein in the above formula (1), a is a number from 0 to 0.6, b is a number from 0.1 to 0.9, c is a number from 0 to 0.5, d is a number from 0 to 0.5, c+d>0, and a+b+c+d=1 is satisfied.
[2] The silicone resin composition, wherein the component (B) is an organosilicon compound selected from organohydrogen(poly)siloxanes, organo(poly)silphenylenes, and organo(poly)silphenylenesiloxanes, having 2 to 200 silicon atoms per molecule and having one or more silicon-bonded aryl groups per molecule.
[3] The silicone resin composition, wherein the component (A) has a weight average molecular weight of 1,000 to 50,000 as determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

The present invention also provides a cured product of the above silicone resin composition. The cured product further comprises at least one of the components shown in the following [1] and [2].
[1] The cured product, characterized in that the type D hardness of the cured product, measured by the method described in JIS K 6253-3, is in the range of 30 to 90.
[2] The cured product described above, characterized in that the refractive index at a wavelength of 589 nm, as measured by the method described in JIS K 0062, is in the range of 1.45 to 1.60.
The present invention further provides an optical semiconductor device comprising the cured product and an optical semiconductor element.

The cured product obtained by curing the silicone resin composition of the present invention preferably has a type D hardness in the range of 30 to 90, measured according to the method described in JIS K 6253-3. A cured product with such hardness has excellent resin strength and can be highly reliable.

The cured product obtained by curing the silicone resin composition of the present invention preferably has a refractive index in the range of 1.45 to 1.60 at a wavelength of 589 nm, measured by the method described in JIS K 0062. Silicone resin compositions that give cured products with such direct light transmittance can be particularly suitable for optical applications such as LED encapsulants.

The present invention is an addition reaction curable silicone resin composition containing a branched organopolysiloxane having a specific structure, and can provide a cured product with excellent gas permeability resistance and reliability. The silicone resin composition can provide a cured product with excellent mechanical properties, transparency, and sulfurization resistance. The addition reaction curable silicone resin composition of the present invention is also suitable for use as a lens material for light-emitting semiconductor devices, a protective coating agent, a molding agent, etc., and a semiconductor device including a cured product of the composition and a semiconductor element can ensure long-term reliability under high humidity conditions, and can provide a light-emitting semiconductor device with good moisture resistance and long-term color rendering properties.

The present invention will be described in detail below, but the present invention is not limited thereto.
[(A) Branched Organopolysiloxane]
The silicone resin composition of the present invention is characterized by containing a branched-chain organopolysiloxane of a specific structure, and thus exhibits high gas permeability resistance and provides a cured product that is stable under high temperature and high humidity conditions.More specifically, component (A) has aryl groups bonded to silicon atoms in an amount of 10% or more based on the total number of substituents bonded to silicon atoms.The silicone resin composition containing such a branched-chain organopolysiloxane provides a cured product with excellent gas permeability resistance.
More specifically, the component (A) of the present invention is a branched-chain organopolysiloxane represented by the following average composition formula (1).
(SiO _4/2 ) _a (R ¹ SiO _3/2 ) _b (R ² SiO _3/2 ) _c (R ² R ³ SiO _2/2 ) _d (1)
(In the above formula, R ¹ 's are each independently a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms other than an alkenyl group, or an aryl group having 6 to 10 carbon atoms; R ² is an alkenyl group having 2 to 10 carbon atoms; R ³ is each independently a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms other than an alkenyl group, or an aryl group having 6 to 10 carbon atoms; a, b, c, and d are numbers that satisfy a≧0, b>0, c≧0, and d≧0, with the proviso that c+d>0 and a+b+c+d=1.)

The (A) component is characterized in that it has 10% or more of aryl groups bonded to silicon atoms relative to the total number of substituents bonded to silicon atoms. More preferably, it has 10 to 90% of aryl groups bonded to silicon atoms relative to the total number of substituents bonded to silicon atoms. Even more preferably, it is 35% to 90%, and the lower limit is even more preferably 50% or more. By having aryl groups at or above the lower limit, the effect of increasing gas permeability resistance is obtained. Furthermore, if the upper limit is exceeded, there will be too many aromatic groups, resulting in a rigid structure, and the resulting resin composition may become brittle.

The above-mentioned (A) component is an organopolysiloxane having a resin structure. The organopolysiloxane is characterized by having a specific ratio of T units and/or D units having alkenyl groups and aryl groups. That is, it essentially contains R ¹ SiO _3/2 units (hereinafter referred to as T units), contains at least one of R ² R ³ SiO _2/2 units (hereinafter referred to as D units) and R ² SiO _3/2 units (hereinafter referred to as T units), and has optional SiO _4/2 units (hereinafter referred to as Q units). In the above-mentioned average composition formula (1), a, b, c, and d are numbers that satisfy a≧0, b>0, c≧0, and d≧0, respectively, with the proviso that c+d>0 and a+b+c+d=1 are satisfied. a, which indicates the ratio of the number of SiO _4/2 units when the total number of siloxane units is 1, is preferably 0 to 0.6, more preferably 0 to 0.5. b, which indicates the ratio of the number of R ¹ SiO _3/2 units when the total number of siloxane units is 1, is preferably 0.1 to 0.9, more preferably 0.3 to 0.8. It is also preferable that a+b is a number of 0.5 or more. c, which indicates the ratio of the number of R ² SiO _3/2 units when the total number of siloxane units is 1, and d, which indicates the ratio of the number of R ² R ³ SiO _2/2 units when the total number of siloxane units is 1, are each independently preferably 0 to 0.5, more preferably 0 to 0.3. c+d is a number greater than 1, preferably 0.01 to 0.7, more preferably 0.1 to 0.5. Component (A) of the present invention preferably does not have R ₃ SiO _1/2 units (hereinafter referred to as M units, where R is a monovalent hydrocarbon group), and in particular does not have M units having an alkenyl group.

In the above, R ¹ 's are each independently a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms; R ² is an alkenyl group having 2 to 10 carbon atoms; and R ³ is each independently a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. More specifically, R ¹ and R ³ include lower alkyl groups such as methyl, ethyl, propyl, and butyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl, tolyl, and xylyl; aralkyl groups such as benzyl, phenylethyl, and phenylpropyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine, bromine, and chlorine, or cyano groups, such as chloromethyl, cyanoethyl, and 3,3,3-trifluoropropyl. Of these, methyl and phenyl groups are preferred. As alkoxy groups, methoxy and ethoxy groups are preferred. As R ² , for example, alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl, hexenyl, cyclohexenyl, and octenyl are preferred. Of these, vinyl is preferred.

Component (A) has at least two silicon-bonded alkenyl groups per molecule. The amount of alkenyl groups contained in component (A) is preferably 0.01 to 0.5 mol/100g, more preferably 0.05 to 0.3 mol/100g, and even more preferably 0.10 to 0.25 mol/100g. If the amount of alkenyl groups bonded to silicon atoms is less than 0.01 mol/100g, there may be few crosslinking points and the composition may not harden. If it exceeds 0.5 mol/100g, the crosslink density may increase and toughness may be lost.

In component (A), the amount of hydroxyl groups bonded to silicon atoms is preferably 0.001 to 1.0 mol/100 g, more preferably 0.005 to 0.8 mol/100 g, and even more preferably 0.008 to 0.6 mol/100 g.

In the (A) component, the amount of alkoxy groups bonded to silicon atoms is preferably 1.0 mol/100g or less, more preferably 0.8 mol/100g or less, and even more preferably 0.5 mol/100g or less. The lower limit of the amount of alkoxy groups is not particularly limited, and the smaller the amount, the better. If the amount of alkoxy groups exceeds 1.0 mol/100g, alcohol gas as a by-product is generated during curing, and voids may remain in the cured product. In the present invention, the amount of hydroxyl groups and the amount of alkoxy groups bonded to silicon atoms refer to values measured by ¹ H-NMR and ²⁹ Si-NMR.

The branched-chain organopolysiloxane preferably has a weight average molecular weight (Mw) of 1,000 to 50,000, more preferably 1,000 to 20,000, and even more preferably 2,000 to 15,000. If the molecular weight is less than the lower limit, the composition may become brittle, and if the molecular weight is more than the upper limit, the composition may become too viscous and not flow. The weight average molecular weight (Mw) in the present invention is the weight average molecular weight measured by gel permeation chromatography (GPC) using polystyrene as the standard, and may be measured under the following conditions.
[Measurement conditions]
Developing solvent: tetrahydrofuran (THF)
Flow rate: 0.6mL/min
Detector: Refractive index detector (RI)
Column: TSK Guardcolumn Super H-L
TSKgel SuperH4000 (6.0mm I.D. x 15cm x 1)
TSKgel SuperH3000 (6.0mm I.D. x 15cm x 1)
TSKgel SuperH2000 (6.0mm I.D. x 15cm x 2)
(Both manufactured by Tosoh Corporation)
Column temperature: 40°C
Sample injection volume: 20 μL (THF solution with a concentration of 0.5% by mass)

Examples of materials for obtaining SiO _4/2 units (Q units) include, but are not limited to, sodium silicate, tetraalkoxysilane, or condensation products thereof.

Examples of materials for obtaining the R ¹ SiO _3/2 units and R ² SiO _3/2 units (T units) include, but are not limited to, organosilicon compounds such as organotrichlorosilane and organotrialkoxysilane represented by the following structural formulas, or condensation products thereof.
(In the above formula, Me represents a methyl group.)

Examples of materials for obtaining R ² R ³ SiO _2/2 units (D units) include, but are not limited to, organosilicon compounds such as diorganodichlorosilane and diorganodialkoxysilane represented by the following structural formulas.

[(B) Hydrosilyl Group-Containing Organosilicon Compound]
Component (B) is a hydrosilyl group-containing organosilicon compound that has two or more hydrogen atoms bonded to silicon atoms in one molecule (hereinafter referred to as hydrosilyl groups), and reacts with component (A) to act as a crosslinking agent.

Component (B) is preferably an organosilicon compound having two or more hydrosilyl groups in one molecule and selected from organohydrogen(poly)siloxanes, organo(poly)silphenylenes, and organo(poly)silphenylenesiloxanes. Organosilicon compounds having 2 to 200 silicon atoms in one molecule and having one or more silicon-bonded aryl groups in one molecule are preferred.
The organohydrogen(poly)siloxane is, for example, represented by the following average composition formula (2): The organo(poly)silphenylene is, for example, represented by the following average composition formula (3): Alternatively, it may be an organohydrogen(poly)silphenylenesiloxane having in its molecule a siloxane structure represented by the average composition formula (2) and a silphenylene structure represented by the following average composition formula (3):
R ⁴ _h H _i SiO _(4-h-i)/2 (2)

R ⁴ _h H _i SiPh _(4-h-i)/2 (3)
In the formula, R ⁴ is, independently of each other, an unsubstituted or substituted alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms, and h and i are positive numbers satisfying 0.7≦h≦2.1, 0.001≦i≦1.0, and 0.8≦h+i≦3.0, preferably 1.0≦h≦2.0, 0.01≦i≦1.0, and 1.5≦h+i≦3.0. In the above formula (3), Ph is a divalent benzene ring (phenylene), more preferably a p-phenylene group.

Examples of ^R4 include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, cyclopentyl, and cyclohexyl, aryl groups such as phenyl, tolyl, xylyl, benzyl, phenylethyl, and phenylpropyl, and aralkyl groups such as these groups in which some or all of the hydrogen atoms bonded to carbon atoms are substituted with halogen atoms such as fluorine, bromine, and chlorine, halogenated hydrocarbon groups such as trifluoropropyl and chloropropyl, and epoxy groups such as allylglycidyl. Of these, alkyl groups having 1 to 5 carbon atoms such as methyl, ethyl, and propyl, and the phenyl group are preferred.

Component (B) preferably has one or more silicon-bonded aryl groups per molecule, and more preferably has 1 to 100 silicon-bonded aryl groups per molecule. More preferably, it has 1 to 70 silicon-bonded aryl groups per molecule.

Component (B) preferably has at least 2 and no more than 200 hydrosilyl groups per molecule. The lower limit is more preferably 3 or more. The upper limit is more preferably 100 or less, and even more preferably 80 or less.

The molecular structure of component (B) is not particularly limited, and any molecular structure, such as linear, cyclic, branched, or three-dimensional network (resin-like), can be used as component (B). When component (B) has a linear structure, the hydrosilyl group may be bonded to a silicon atom only at either the molecular chain terminal or the molecular chain side chain, or may be bonded to a silicon atom at both.

One embodiment of component (B) is an organohydrogen(poly)siloxane having a number of silicon atoms (or degree of polymerization) in one molecule of 2 to 200, preferably 3 to 100, more preferably 3 to 70, even more preferably 3 to 50, and still more preferably 3 to 30. Organohydrogen(poly)siloxanes that are liquid or solid at room temperature (25° C.) are preferred.
Another embodiment of component (B) is a compound having a silphenylene structure and having hydrogen atoms bonded to two or more silicon atoms in one molecule, preferably an organo(poly)silphenylene having a silphenylene structure and having hydrosilyl groups at both ends of the molecular chain, and the number (or degree of polymerization) of silicon atoms in one molecule is 2 to 50, more preferably 2 to 30, and even more preferably 2.
Another embodiment of component (B) may be an organohydrogen(poly)silphenylenesiloxane having a silphenylene structure, as described above. The number of silicon atoms (or degree of polymerization) in one molecule is usually 2 to 200, preferably 3 to 100, more preferably 3 to 70, even more preferably 3 to 50, and even more preferably 3 to 30, similar to organohydrogen(poly)siloxanes.

Examples of organohydrogenpolysiloxanes represented by the above average composition formula (2) include tris(hydrogendimethylsiloxy)phenylsilane, a methylhydrogensiloxane-diphenylsiloxane copolymer capped at both ends with trimethylsiloxy groups, a methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer capped at both ends with trimethylsiloxy groups, a methylhydrogensiloxane-methylphenylsiloxane-dimethylsiloxane copolymer capped at both ends with trimethylsiloxy groups, a methylhydrogensiloxane-dimethylsiloxane-diphenylsiloxane copolymer capped at both ends with dimethylhydrogensiloxy groups, a methylhydrogensiloxane-dimethylsiloxane-methylphenylsiloxane copolymer capped at both ends with dimethylhydrogensiloxy groups, a (CH ₃ ) ₂ HSiO _1/2 unit, a SiO _4/2 unit, and a (C ₆ H ₅ ) ₃ SiO and copolymers consisting of _1/2 units.

More specifically, component (B) includes hydrosilyl group-containing organosilicon compounds represented by the following structures, but is not limited to these.
(p, q, and r are each an integer of 0 or more, and p+q+r is a number between 3 and 500.)

In the silicone resin composition of the present invention, the amount of component (B) is an amount such that the ratio of the number of hydrosilyl groups in component (B) to the number of alkenyl groups bonded to silicon atoms in component (A) is 0.1 to 4.0, preferably 0.5 to 3.0, and more preferably 0.8 to 2.0. If the amount of component (B) is less than the above lower limit, the curing reaction of the silicone resin composition does not proceed, making it difficult to obtain a cured product, and the crosslink density of the obtained cured product becomes too low, resulting in insufficient mechanical strength and poor heat resistance. On the other hand, if the amount of component (B) is more than the above upper limit, a large amount of unreacted hydrosilyl groups remain in the cured product, causing changes in physical properties over time and a decrease in the heat resistance of the cured product, and further causing foaming due to a dehydrogenation reaction in the cured product.

[(C) Platinum group metal catalyst]
The component (C) is a catalyst that promotes the hydrosilylation reaction of the components (A) and (B). Any conventionally known platinum group metal catalyst can be used as the catalyst. Considering the cost, platinum-based catalysts such as platinum, platinum black, and _{chloroplatinic} acid _are preferred. For example, _H2PtCl6.pH2O , _{K2PtCl6 , KHPtCl6.pH2O} , _K2PtCl4 , K2PtCl4.pH2O, _{PtO2.pH2O , PtCl4.pH2O , PtCl2} , _H2PtCl4.pH2O (where p is a positive integer), _and complexes of these with hydrocarbons such as olefins, _{alcohols ,} or vinyl group- _containing organopolysiloxanes _, and complexes _having photoactivity _such as trimethyl(methylcyclopentadienyl)platinum can be exemplified. These catalysts may be used either individually or in combination of two or more.

The amount of catalyst (C) used is a catalytic amount and is not particularly limited. It should be an effective amount for promoting the hydrosilylation reaction of components (A) and (B). Typically, the amount is 0.1 to 500 ppm by mass of platinum group metal relative to the total amount of components (A) and (B), and preferably 0.5 to 100 ppm by mass.

[(D) Solvent]
The component (D) is a solvent for improving the fluidity of the resin composition. Any conventionally known organic solvent can be used as the solvent. For example, hydrocarbons such as hexane, heptane, benzene, toluene, and xylene, esters such as ethyl acetate, n-butyl acetate, and propylene glycol methyl ether acetate, ketones such as methyl ethyl ketone, methyl amyl ketone, cyclohexanone, cyclopentanone, and methyl isobutyl ketone, ethers such as diethyl ether, diisopropyl ether, methyl-tert-butyl ether, and ethylcyclopentyl methyl ether, and chlorine-based solvents such as methylene chloride, chloroform, dichloroethane, and trichloroethylene can be exemplified. These solvents can be used alone or in combination of two or more. The amount of the solvent may be appropriately adjusted within a range that does not impair the effects of the present invention. It is preferably 50 parts by mass or less per 100 parts by mass of the total of the components (A) and (B), and more preferably 1 to 30 parts by mass.

[Other additives]
In addition to the above-mentioned components (A), (B), and (C), other additives may also be appropriately blended into the silicone resin composition of the present invention. Other additives include, for example, reinforcing inorganic fillers such as silica, glass fiber, and fumed silica; inorganic white pigments such as titanium dioxide, zinc oxide, zirconium oxide, calcium carbonate, magnesium oxide, aluminum hydroxide, barium carbonate, magnesium silicate, zinc sulfate, and barium sulfate; non-reinforcing inorganic fillers such as calcium silicate, carbon black, cerium fatty acid salts, barium fatty acid salts, cerium alkoxides, and barium alkoxides; silver (Ag), aluminum (Al), aluminum nitride (AlN), boron nitride (BN), silicon dioxide (silica: SiO ₂ ), aluminum oxide (alumina: Al ₂ O ₃ ), iron oxide (Fe ₂ O ₃ ), triiron tetroxide (Fe ₃ O ₄ ), lead oxide (PbO ₂ ), tin oxide (SnO ₂ ), cerium oxide (Ce ₂ O _{3 ,} CeO ₂ ), calcium oxide (CaO), and trimanganese tetroxide (Mn ₃ O _{4 )} . ), barium oxide (BaO), and other fillers are included. The amount of the additive may be appropriately adjusted within a range that does not impair the effects of the present invention. The amount of the additive is preferably 600 parts by mass or less, and more preferably 10 to 400 parts by mass, per 100 parts by mass of the total of components (A) and (B).

The silicone resin composition of the present invention can be applied to a substrate of a given type depending on the application, and then cured. As for the curing conditions, the composition can be sufficiently cured at room temperature (25°C), but may also be cured by heating if necessary. When heating, the composition can be cured at a temperature of, for example, 60 to 200°C.

The hardness of the cured product of the composition of the present invention, measured using a durometer type D hardness tester in accordance with JIS K 6253-3, is 30 to 90, preferably 35 to 85, and more preferably 40 to 80. If the hardness is less than 30, the strength is insufficient, and if it exceeds 90, the strength is excellent but the resin becomes rigid and is prone to cracking, peeling, and other deterioration in reliability.

The cured product of the composition of the present invention has a refractive index at a wavelength of 589 nm measured by the method described in JIS K 0062 of 1.45 to 1.60, preferably 1.47 to 1.60, and more preferably 1.50 to 1.60. If the refractive index is less than 1.45, the anti-reflection effect is small, and if it exceeds 1.60, the anti-reflection effect is excellent but the functions as an optical semiconductor device, such as light transmittance, are inferior.

The silicone resin composition of the present invention can be used for a variety of applications, including, but not limited to, sealing materials, adhesives, electrical insulating materials, laminates, coatings, inks, paints, sealants, resists, composite materials, films, underfill materials, anti-reflective materials, light diffusing materials, and light reflecting materials. The present invention also provides an optical semiconductor device in which a semiconductor element is sealed with a cured product of the silicone resin composition of the present invention.

The present invention will be described in more detail below with examples and comparative examples, but the present invention is not limited to these. Note that parts indicate parts by mass, and the viscosity of each component indicates the absolute viscosity at 25°C measured with a rotational viscometer described in JIS K 7117-1:1999. The weight average molecular weight is the value measured by gel permeation chromatography using polystyrene as the standard substance as described above.

The evaluation test methods used in the following Examples and Comparative Examples are as follows.
(1) Appearance Each silicone resin composition was cured at 180° C. for 4 hours, and the color, transparency, and the presence or absence of voids of the cured product (1 mm) obtained were visually inspected.
(2) Properties The fluidity of each silicone resin composition before curing was confirmed. 50 g of the composition was added to a 100 ml glass bottle, and the glass bottle was turned on its side and left to stand at 25° C. for 10 minutes. If the resin flowed out during that time, it was determined to be in a liquid state.
(3) Viscosity The viscosity of each silicone resin composition at 25° C. before curing was measured according to the method described in JIS K 7117-1:1999.
(4) Refractive index
The refractive index of each silicone resin composition before curing was measured at 25° C. using a digital refractometer RX-9000α manufactured by ATAGO in accordance with the method described in JIS K 0062, at a wavelength of 589 nm.
(5) Hardness (Type D)
Each silicone resin composition was cured at 180° C. for 4 hours, and the hardness of the cured product (120 mm×110 mm×1 mm) was measured using a durometer type D hardness tester in accordance with JIS K 6253-3.
(6) Stress at Break and Flexural Modulus of Elasticity Each silicone resin composition was cured at 180° C. for 4 hours, and the stress at break and flexural modulus of elasticity of the cured product (120 mm × 110 mm × 1 mm) were measured using an Autograph AG-IS manufactured by Shimadzu Corporation in accordance with JIS K 7171:1994.
(7) Adhesion 0.25 g of each silicone resin composition was molded onto a copper plate with an area of 180 ^mm2 so that the bottom area was 45 ^mm2 , and cured at 180°C for 4 hours to prepare an adhesion test piece. The shear adhesive strength of the test piece was measured at 25 and 150°C using a bond tester DAGE-SERIES-4000PXY (manufactured by DAGE Corporation). The adhesive strength retention rate was calculated using the following formula.
Adhesion retention rate (%)=(adhesion strength at 150° C. [MPa])/(adhesion strength at 25° C. [MPa] [%])×100
(8) Heat Resistance Test Each silicone resin composition was cured at 180° C. for 4 hours to obtain a cured product (120 mm×110 mm×1 mm). The product was then left at 150° C. for 100 hours, and the change in color was visually confirmed.
(9) Water Vapor Permeability Measurement The water vapor permeability of the cured product (120 mm × 110 mm × 1 mm) obtained by curing each silicone resin composition at 180°C for 4 hours was measured using a Lyssy L80-5000 (manufactured by Systech Instruments) water vapor permeability meter, according to JIS Z 0208: 1976, at 40°C by the cup method. In addition, water vapor permeability of 0.1 g/ ^m2 /day or less, which is close to the lower measurement limit of the cup method, was measured by the remote method according to JIS K 7129B: 2019.
(10) Sulfuration Resistance A ¹ cm2 silver-plated plate was sealed with a silicone resin composition to a thickness of 0.6 mm and cured at 180°C for 4 hours to obtain a sample. The sample was placed in a sealed container together with 3 g of sulfur powder and left in a thermostatic chamber at 80°C for 50 hours, and then the initial light reflectance of the silver-plated plate at 450 nm was measured using X-rite 8200 manufactured by SDG Corporation. The initial reflectance was 90% in all cases.
The sulfurization resistance was calculated by the following formula and evaluated according to the following criteria.
Sulfuration resistance (%) = ((reflectance after sulfuration test [%]) / (initial reflectance [%])) x 100
(Judgment criteria)
○: Sulfidation resistance is 90% or more.
△: Sulfidation resistance is 80% or more but less than 90%.
×: Sulfurization resistance less than 80% (11) Surface Tackiness Each silicone resin composition was cured at 180° C. for 4 hours, and the presence or absence of dust on the surface of the resulting cured product (120 mm×110 mm×1 mm) was visually inspected.
(12) Glass Transition Temperature Each silicone resin composition was cured at 180° C. for 4 hours, and the glass transition temperature of the cured product (120 mm×110 mm×1 mm) was measured using a DMA-800 manufactured by TA Instruments.

[Synthesis Example 1]
Synthesis of branched chain organopolysiloxane (A-1) 495.7g (2.50mol) of phenyltrimethoxysilane (KBM-103, manufactured by Shin-Etsu Chemical Co., Ltd.), 190.1g (1.25mol) of tetramethoxysilane (KBM-04, manufactured by Shin-Etsu Chemical Co., Ltd.), 145.3g (1.25mol) of vinylmethyldimethoxysilane (KBM-1012, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed, 13.3g of methanesulfonic acid, 123.9g of pure water, and 1000g of xylene were added, and the mixture was stirred at 90°C for 4 hours. Thereafter, 25.0g of a 50wt% aqueous solution of potassium hydroxide was added, and the mixture was further stirred at 130°C for 16 hours. Acetic acid was added to neutralize the solution, and the mixture was washed with 10wt% aqueous sodium sulfate. The organic layer was subjected to azeotropic dehydration at 120° C. for 1 hour, filtered through a 0.45 μm filter paper, and then the solvent was removed by distillation under reduced pressure to prepare a branched organopolysiloxane (A-1).
The obtained branched organopolysiloxane (A-1) has an average structure of (SiO4 _/2 ) _0.25 (PhSiO3 _/2 ) _0.50 (( _CH2 =CH-)MeSiO2 _/2 ) _0.25 , is represented by _{Q0.25T0.5DVi0.25} , has ^Mw = ₇₇₀₀ , has _0.1 mol/100 g of hydroxyl groups bonded to silicon atoms, and has 0.2 mol/100 g of vinyl groups bonded to silicon atoms. The number of phenyl groups bonded to silicon atoms is 50% based on the total number of substituents bonded to silicon atoms.

[Synthesis Example 2]
Synthesis of branched linear organopolysiloxane (A-2) 743.6g (3.75mol) of phenyltrimethoxysilane (KBM-103, manufactured by Shin-Etsu Chemical Co., Ltd.) and 145.3g (1.25mol) of vinylmethyldimethoxysilane (KBM-1012, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed, 13.3g of methanesulfonic acid, 123.9g of pure water and 1000g of xylene were added, and the mixture was stirred at 90°C for 4 hours. Then, 25.0g of a 50wt% aqueous solution of potassium hydroxide was added, and the mixture was further stirred at 130°C for 16 hours. Acetic acid was added to neutralize the solution, and the mixture was washed with 10wt% aqueous sodium sulfate. The organic layer was subjected to azeotropic dehydration at 120°C for 1 hour, filtered with a 0.45μm filter paper, and the solvent was removed by distillation under reduced pressure to prepare branched organopolysiloxane (A-2).
The obtained branched organopolysiloxane (A-1) has an average structure of (PhSiO3 _/2 ) _0.75 (( _CH2 = ^CH- )MeSiO2 _/2 ) _0.25 , is represented by _T0.75DVi0.25 , has Mw= _3,400 , has 0.1 mol/100 g of hydroxyl groups bonded to silicon atoms, and has 0.2 mol/100 g of vinyl groups bonded to silicon atoms. The number of phenyl groups bonded to silicon atoms is 60% based on the total number of substituents bonded to silicon atoms.

[Synthesis Example 3]
Synthesis of branched linear organopolysiloxane (A-3) 743.6 g (3.75 mol) of phenyltrimethoxysilane (KBM-103, manufactured by Shin-Etsu Chemical Co., Ltd.) and 243.0 g (1.25 mol) of vinylphenyldimethoxysilane (KBM-1102, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed, and 15.0 g of methanesulfonic acid, 123.9 g of pure water, and 1000 g of xylene were added, followed by stirring at 90°C for 4 hours. Thereafter, 25.0 g of a 50 wt% aqueous solution of potassium hydroxide was added, followed by further stirring at 130°C for 16 hours. Acetic acid was added to neutralize the solution, and the solution was washed with 10 wt% aqueous sodium sulfate. The organic layer was subjected to azeotropic dehydration at 120°C for 1 hour, filtered with 0.45 μm filter paper, and the solvent was removed by distillation under reduced pressure to prepare branched organopolysiloxane (A-3).
The obtained branched organopolysiloxane (A-3) has an average structure of (PhSiO _3/2 ) _0.75 ((CH ₂ ═CH—)PhSiO _2/2 ) _0.25 , is represented by T _0.75 D ^Vi _0.25 , and has Mw=2000. The amount of hydroxyl groups bonded to silicon atoms is 0.1 mol/100 g, and the amount of vinyl groups bonded to silicon atoms is 0.2 mol/100 g. The amount of phenyl groups bonded to silicon atoms is 80% of the total number of substituents bonded to silicon atoms.

[Synthesis Example 4]
Synthesis of branched chain organopolysiloxane (A-4) 743.6 g (3.75 mol) of phenyltrimethoxysilane (KBM-103, manufactured by Shin-Etsu Chemical Co., Ltd.) and 290.2 g (1.25 mol) of trimethoxy(7-octen-1-yl)silane (KBM-1083, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed, and 13.9 g of methanesulfonic acid, 123.9 g of pure water, and 1000 g of xylene were added, followed by stirring at 90° C. for 4 hours. Thereafter, 25.0 g of a 50 wt % aqueous solution of potassium hydroxide was added, followed by further stirring at 130° C. for 16 hours. Acetic acid was added to neutralize the solution, and the solution was washed with 10 wt % aqueous sodium sulfate. The organic layer was subjected to azeotropic dehydration at 120° C. for 1 hour, filtered through a 0.45 μm filter paper, and then the solvent was removed by distillation under reduced pressure to prepare a branched organopolysiloxane (A-4).
The obtained branched organopolysiloxane (A-4) has an average structure of (PhSiO _3/2 ) _0.75 ((CH ₂ ═CH(CH ₂ ) ₆ —)SiO _3/2 ) _0.25 , is represented by T _0.75 T ^Vi _0.25 , and has Mw=7000. The amount of hydroxyl groups bonded to silicon atoms is 0.1 mol/100 g, and the amount of vinyl groups bonded to silicon atoms is 0.2 mol/100 g. The amount of phenyl groups bonded to silicon atoms is 60% of the total number of substituents bonded to silicon atoms.

[Synthesis Example 5]
Synthesis of branched linear organopolysiloxane (A-5) 743.6g (3.75mol) of phenyltrimethoxysilane (KBM-103, manufactured by Shin-Etsu Chemical Co., Ltd.) and 185.1g (1.25mol) of vinyltrimethoxysilane (KBM-1003, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed, 13.9g of methanesulfonic acid, 123.9g of pure water and 1000g of xylene were added, and the mixture was stirred at 90°C for 4 hours. Then, 25.0g of a 50wt% aqueous solution of potassium hydroxide was added, and the mixture was further stirred at 130°C for 16 hours. Acetic acid was added to neutralize the solution, and the mixture was washed with 10wt% aqueous sodium sulfate. The organic layer was subjected to azeotropic dehydration at 120°C for 1 hour, filtered with 0.45μm filter paper, and the solvent was removed by distillation under reduced pressure to prepare branched organopolysiloxane (A-5).
The obtained branched organopolysiloxane (A-5) has an average structure of (PhSiO _3/2 ) _0.75 ((CH ₂ ═CH—)SiO _3/2 ) _0.25 , is represented by T _0.75 T ^Vi _0.25 , and has Mw=11,200. The amount of hydroxyl groups bonded to silicon atoms is 0.1 mol/100 g, and the amount of vinyl groups bonded to silicon atoms is 0.2 mol/100 g. The amount of phenyl groups bonded to silicon atoms is 75% of the total number of substituents bonded to silicon atoms.

The hydrosilyl group-containing organosilicon compounds used in the examples are as follows:
(B-1) The following formula (4):
(the amount of hydrogen atoms bonded to silicon atoms is 0.6 mol/100 g, and the organohydrogensiloxane is liquid at room temperature (25° C.))
(B-2) The following formula (5):
(amount of hydrogen atoms bonded to silicon atoms: 1.04 mol/100 g)

[Example 1]
A silicone resin composition was prepared by adding 100 parts of the branched organopolysiloxane (A-1) obtained in Synthesis Example 1 as component (A), organohydrogensiloxane (B-1) represented by formula (4) above as component (B) in an amount such that the ratio of the total number of silicon-bonded hydrogen atoms in component (B) to the total number of vinyl groups in component (A) (SiH/SiVi) was 1.2, and 0.1 parts of an octyl alcohol-modified solution of chloroplatinic acid (platinum element content: 1% by mass) as component (C) and stirring thoroughly.
This composition was heated and molded at 180° C. for 4 hours to form a cured product (120 mm×110 mm×1 mm), and the above-mentioned physical properties were measured. The results are shown in Tables 1-1 and 1-2.

[Example 2]
A silicone resin composition was obtained by repeating the procedure of Example 1, except that, as the component (A), 100 parts of the branched organopolysiloxane (A-2) obtained in Synthesis Example 2 was used in place of the branched organopolysiloxane (A-1) used in Example 1.
This composition was heated and molded at 180° C. for 4 hours to form a cured product (120 mm×110 mm×1 mm), and the above-mentioned physical properties were measured. The results are shown in Tables 1-1 and 1-2.

[Example 3]
A silicone resin composition was obtained by repeating the procedure of Example 1, except that, as the component (A), 100 parts of the branched organopolysiloxane (A-3) obtained in Synthesis Example 3 was used instead of the branched organopolysiloxane (A-1) used in Example 1.
This composition was heated and molded at 180° C. for 4 hours to form a cured product (120 mm×110 mm×1 mm), and the above-mentioned physical properties were measured. The results are shown in Tables 1-1 and 1-2.

[Example 4]
A silicone resin composition was obtained by repeating the procedure of Example 1, except that 100 parts of the branched organopolysiloxane (A-4) obtained in Synthesis Example 4 was used instead of the branched organopolysiloxane (A-1) used in Example 1 as the component (A).
This composition was heated and molded at 180° C. for 4 hours to form a cured product (120 mm×110 mm×1 mm), and the above-mentioned physical properties were measured. The results are shown in Tables 1-1 and 1-2.

[Example 5]
A silicone resin composition was prepared by adding 100 parts of the branched organopolysiloxane (A-5) obtained in Synthesis Example 5 as component (A), organohydrogensiloxane (B-1) represented by formula (4) above as component (B) in an amount such that the ratio of the total number of silicon-bonded hydrogen atoms in component (B) to the total number of vinyl groups in component (A) (SiH/SiVi) was 1.2, 0.1 parts of an octyl alcohol-modified solution of chloroplatinic acid (platinum element content: 1 mass%) as component (C), and 8 parts of cyclopentanone as component (D) and stirring thoroughly.
This composition was heated and molded at 180° C. for 4 hours to form a cured product (120 mm×110 mm×1 mm), and the above-mentioned physical properties were measured. The results are shown in Tables 1-1 and 1-2.

[Examples 6 to 9]
A cured silicone resin composition was obtained by repeating the procedures of Examples 1 to 4, except that the hydrosilyl compound (B-1) was changed to the organosylphenylene compound (B-2) represented by the above formula (5) and the (B-2) component was blended in an amount such that the SiH/SiVi ratio was 1.2.
This composition was heated and molded at 180° C. for 4 hours to form a cured product (120 mm×110 mm×1 mm), and the above-mentioned physical properties were measured. The results are shown in Tables 1-1 and 1-2.

[Example 10]
A silicone resin composition was prepared by adding 100 parts of the branched organopolysiloxane (A-5) obtained in Synthesis Example 5 as component (A), organosylphenylene compound (B-2) represented by formula (5) above as component (B) in an amount such that the ratio of the total number of silicon-bonded hydrogen atoms in component (B) to the total number of vinyl groups in component (A) (SiH/SiVi) was 1.2, 0.1 parts of an octyl alcohol-modified solution of chloroplatinic acid (platinum element content: 1 mass %) as component (C), and 15 parts of cyclopentanone as component (D) and stirring thoroughly.
This composition was heated and molded at 180° C. for 4 hours to form a cured product (120 mm×110 mm×1 mm), and the above-mentioned physical properties were measured. The results are shown in Tables 1-1 and 1-2.

[Comparative Synthesis Example 1]
Phenyltrimethoxysilane (KBM-103, Shin-Etsu Chemical Co., Ltd.) 743.7 g (3.75 mol), divinyltetramethyldisiloxane (Shin-Etsu Chemical Co., Ltd.) 116.3 g (0.65 mol) were mixed, methanesulfonic acid 13.0 g, pure water 107.0 g, and xylene 1000 g were added, and the mixture was stirred at 90 ° C. for 4 hours. Then, potassium hydroxide 50 wt % aqueous solution 25.0 g was added, and the mixture was further stirred at 130 ° C. for 16 hours. Acetic acid was added to neutralize the solution, and the mixture was washed with 10 wt % sodium sulfate water. The organic layer was azeotropically dehydrated at 120 ° C. for 1 hour, filtered with 0.45 μm filter paper, and the solvent was removed by distillation under reduced pressure to prepare branched organopolysiloxane (A-6).
The obtained branched organopolysiloxane (A-6) has an average structure of (PhSiO _3/2 ) _0.75 ((CH ₂ ═CH—)Me ₂ SiO _1/2 ) _0.25 , is represented by T _0.75 M ^Vi _0.25 , and has Mw=1,400. The amount of hydroxyl groups bonded to silicon atoms is 0.1 mol/100 g, and the amount of vinyl groups bonded to silicon atoms is 0.2 mol/100 g. The amount of phenyl groups bonded to silicon atoms is 50% of the total number of substituents bonded to silicon atoms.

[Comparative Synthesis Example 2]
Phenyltrimethoxysilane (KBM-103, Shin-Etsu Chemical Co., Ltd.) 743.7 g (3.75 mol), divinyldimethyldiphenyldisiloxane (Shin-Etsu Chemical Co., Ltd.) 193.9 g (0.65 mol) were mixed, methanesulfonic acid 14.1 g, pure water 107.0 g, and xylene 1000 g were added, and the mixture was stirred at 90 ° C. for 4 hours. Then, potassium hydroxide 50 wt % aqueous solution 25.0 g was added, and the mixture was further stirred at 130 ° C. for 16 hours. Acetic acid was added to neutralize the solution, and the mixture was washed with 10 wt % sodium sulfate water. The organic layer was azeotropically dehydrated at 120 ° C. for 1 hour, filtered with 0.45 μm filter paper, and the solvent was removed by distillation under reduced pressure to prepare branched organopolysiloxane (A-7).
The obtained branched organopolysiloxane (A-7) has an average structure of (PhSiO _3/2 ) _0.75 ((CH ₂ ═CH—)PhMeSiO _1/2 ) _0.25 , is represented by T _0.75 M ^Vi _0.25 , and has Mw=1,400. The amount of hydroxyl groups bonded to silicon atoms is 0.1 mol/100 g, and the amount of vinyl groups bonded to silicon atoms is 0.2 mol/100 g. The number of phenyl groups bonded to silicon atoms is 60% based on the total number of substituents bonded to silicon atoms.

[Comparative Example 1]
A silicone resin composition was obtained by repeating the procedure of Example 1, except that the branched organopolysiloxane (A-1) in Example 1 was replaced with the branched organopolysiloxane (A-6) obtained in Comparative Synthesis Example 1. This composition was molded by heating at 180°C for 4 hours to form a cured product (120 mm x 110 mm x 1 mm), and the physical properties described above were measured. The results are shown in Table 2.

[Comparative Example 2]
A silicone resin composition was obtained by repeating the procedure of Example 1, except that the branched organopolysiloxane (A-1) of Example 1 was replaced with the branched organopolysiloxane (A-7) obtained in Comparative Synthesis Example 2. This composition was heat molded at 180°C for 4 hours to form a cured product (120 mm x 110 mm x 1 mm), and the above-mentioned physical properties were measured. The results are shown in Table 2.

[Comparative Example 3]
As the component (A), instead of the branched organopolysiloxane (A-1) used in Example 1,
(Wherein, m=9, n=19)
A silicone resin composition was obtained by repeating the procedure of Example 1, except that a linear organopolysiloxane (A-8) represented by the following formula was used. This composition was heat molded at 180° C. for 4 hours to form a cured product (120 mm×110 mm×1 mm), and the above-mentioned physical properties were measured. The results are shown in Table 2.

[Comparative Example 4]
A silicone resin composition was obtained by repeating the procedure of Example 6, except that as component (A), the branched organopolysiloxane (A-1) of Example 6 was replaced with the branched organopolysiloxane (A-6) obtained in Comparative Synthesis Example 1. This composition was molded by heating at 180°C for 4 hours to form a cured product (120 mm x 110 mm x 1 mm), and the physical properties described above were measured. The results are shown in Table 2.

[Comparative Example 5]
A silicone resin composition was obtained by repeating the procedure of Example 7, except that as component (A), the branched organopolysiloxane (A-2) used in Example 7 was replaced with the branched organopolysiloxane (A-7) obtained in Comparative Synthesis Example 2. This composition was molded by heating at 180°C for 4 hours to form a cured product (120 mm x 110 mm x 1 mm), and the physical properties described above were measured. The results are shown in Table 2.

The compositions and physical property evaluation results of each silicone resin composition and its cured product obtained in the above examples and comparative examples are shown in Tables 1-1 and 1-2, and Table 2 below.

As shown in Table 2, the silicone resin compositions of Comparative Examples 1, 2, 4, and 5, which contained a branched-chain organopolysiloxane having an alkenyl group in the M unit and no alkenyl-group-containing T unit or D unit, gave cured products that were inferior in adhesion and sulfurization resistance. Also, the cured product of the silicone resin composition of Comparative Example 3, which contained a linear alkenyl-group-containing organopolysiloxane, was inferior in hardness, adhesion, and sulfurization resistance.
On the other hand, the silicone resin compositions of Examples 1 to 10 in which the branched-chain organopolysiloxane contained alkenyl group-containing T units or D units gave cured products that were excellent in sufficient viscosity, appearance, refractive index, hardness, adhesive strength, and sulfurization resistance, as shown in Table 1. This is because the cured products obtained due to the branched-chain organopolysiloxane had a rigid structure and maintained a high elastic modulus even at high temperatures.

The silicone resin composition of the present invention can give cured products that have excellent gas permeability resistance and are suitable for use as lens materials for light-emitting semiconductor devices, protective coating agents, molding agents, etc.

The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included within the technical scope of the present invention.

Claims (8)

(A) a branched-chain organopolysiloxane represented by the following average formula, which has 10% or more aryl groups bonded to silicon atoms relative to the total number of substituents bonded to silicon atoms and has at least two silicon-bonded alkenyl groups per molecule:
(SiO _4/2 ) _a (R ¹ SiO _3/2 ) _b (R ² SiO _3/2 ) _c (R ² R ³ SiO _2/2 ) _d (1)
(In the above formula, R ¹ 's are each independently a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms other than an alkenyl group, or an aryl group having 6 to 10 carbon atoms; R ² 's are each independently an alkenyl group having 2 to 10 carbon atoms; R ³ 's are each independently a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms other than an alkenyl group, or an aryl group having 6 to 10 carbon atoms; and a, b, c, and d are numbers that satisfy a≧0, b>0, c≧0, and d≧0, with the proviso that c+d>0 and a+b+c+d=1.)
The silicone resin composition comprises: (B) a hydrosilyl group-containing organosilicon compound having two or more SiH groups per molecule, in an amount such that the ratio of the number of hydrosilyl groups in component (B) to the number of alkenyl groups in component (A) is 0.1 to 4.0; and (C) a catalytic amount of a platinum group metal catalyst. The silicone resin composition according to claim 1, wherein in formula (1), a is a number between 0 and 0.6, b is a number between 0.1 and 0.9, c is a number between 0 and 0.5, d is a number between 0 and 0.5, c+d>0, and a+b+c+d=1 is satisfied. The silicone resin composition according to claim 1, wherein the component (B) is an organosilicon compound selected from organohydrogen(poly)siloxanes, organo(poly)silphenylenes, and organo(poly)silphenylenesiloxanes, having 2 to 200 silicon atoms in one molecule and having one or more silicon-bonded aryl groups in one molecule. The silicone resin composition according to claim 1, wherein the (A) component has a weight average molecular weight of 1,000 to 50,000 as determined by gel permeation chromatography using polystyrene as the standard substance. A cured product of the silicone resin composition according to any one of claims 1 to 4. The cured product according to claim 5, characterized in that the type D hardness of the cured product measured by the method described in JIS K 6253-3 is in the range of 30 to 90. The cured product according to claim 5, characterized in that the refractive index of the cured product at a wavelength of 589 nm measured by the method described in JIS K 0062 is in the range of 1.45 to 1.60. An optical semiconductor device comprising the cured product according to any one of claims 5 to 7 and an optical semiconductor element.