CURABLE SILICONE COMPOSITION, ENCAPSULATING MATERIAL, AND OPTICAL SEMICONDUCTOR DEVICE

Abstract

To provide a curable silicone composition with which a cured product having excellent elongation characteristics can be formed.SOLUTION: The problem is solved by using a curable silicone composition including (A) a resinous alkenyl group-containing organopolysiloxane which contains less than two alkenyl groups per molecule on average and is represented by average unit formula (I): (R13SiO1 / 2)a(R12SiO2 / 2)b(R1SiO3 / 2)c(SiO4 / 2)d(XO1 / 2)e, in formula (I), each of R1 is mutually independently a univalent hydrocarbon group containing an alkenyl group, however, the number of alkenyl groups per molecule is less than two on average, X is a hydrogen atom or an alkyl group, 0≤a≤1, 0≤b≤1, 0≤c<0.9. 0≤d<0.5, and 0≤e<0.4, a+b+c+d=1.0, and c+d>0, (B) an organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to a silicon atom per molecule, and (C) a catalyst for curing reaction.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a curable silicone composition, more specifically, to a curable silicone composition suitable for use as an encapsulant for optical semiconductor devices. The present invention also relates to an encapsulant made of a cured product of the curable silicone composition, and an optical semiconductor device encapsulated with the encapsulant. [Background technology]

[0002] Curable silicone compositions are widely used as optical materials because they cure to form cured products that have excellent heat resistance, weather resistance, and transparency.

[0003] For example, Patent Document 1 describes (A) a linear organopolysiloxane having at least two silicon-bonded alkenyl groups and at least one silicon-bonded aryl group in one molecule, (B) a linear organopolysiloxane having at least one silicon-bonded alkenyl group and at least one silicon-bonded aryl group in one molecule, and having the general formula: RSiO 3 / 2 The document discloses a curable organopolysiloxane composition comprising a branched-chain organopolysiloxane having siloxane units represented by the formula: (wherein R is a substituted or unsubstituted monovalent hydrocarbon group) {an amount such that the ratio of the content of this component to the content of component (A) is 1 / 99 to 99 / 1 by weight}, (C) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule {1 to 200 parts by weight for every 100 parts by weight of components (A) and (B) combined}, and (D) a hydrosilylation catalyst (in an amount sufficient to promote curing of the composition).

[0004] In addition, Patent Document 2 discloses a compound having the following average composition formula (1): 1 SiO 3 / 2 ) a (R 2 R 3 SiO) b (R 4 R 5 R 6 SiO 1 / 2 ) c (SiO 4 / 2) d (1) (where R 1 ~R 6 each represents the same or different monovalent hydrocarbon group, 1 to 50 mol % of the total monovalent hydrocarbon groups are non-covalent double bond-containing groups, and a, b, c, and d are positive numbers indicating the molar ratios of each siloxane unit, a / (a+b+c+d)=0.40 to 0.95, b / (a+b+c+d)=0.05 to 0.60, c / (a+b+c+d)=0 to 0.05, d / (a+b+c+d)=0 to 0.10, and a+b+c+d=1.0. The document describes an addition-curable silicone resin composition that contains as essential components a polysiloxane and (C) a catalytic amount of a platinum-based catalyst, and is characterized in that the organopolysiloxanes of components (A) and (B) do not contain silanols.

[0005] Furthermore, Patent Document 3 describes a silicone resin lens for LEDs made of a silicone resin having a ratio of refractive indexes measured at 400 nm and 596 nm of 1.01 or more and a refractive index at 400 nm of 1.50 or more.

[0006] Furthermore, Patent Document 4 describes a silicone resin composition for molding lenses, which contains as essential components (A) an organopolysiloxane having two or more aliphatic unsaturated bonds per molecule and having a viscosity of 100 mPa s or more at 25°C, (B) an organohydrogenpolysiloxane having three or more silicon-bonded hydrogen atoms per molecule, and (C) a platinum group metal catalyst, and which produces a colorless and transparent cured product.

[0007] However, curable silicone compositions that contain conventional resin-like crosslinking agents that have three or more silicon-bonded hydrogen atoms per molecule have the problem that the elongation properties of the cured product are insufficient. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2004-143361 A [Patent Document 2] JP 2006-299099 A [Patent Document 3] JP 2006-324596 A [Patent Document 4] JP 2006-328102 A Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a curable silicone composition that is capable of forming a cured product with superior elongation properties.

[0010] Another object of the present invention is to provide an encapsulant containing the curable silicone composition of the present invention. Still another object of the present invention is to provide an optical semiconductor device encapsulated with the encapsulant of the present invention. [Means for solving the problem]

[0011]

[0013] In order to solve the above problems, the present inventors conducted extensive research and surprisingly discovered that a curable silicone composition that combines a resinous alkenyl-containing organopolysiloxane that contains, on average, less than two alkenyl groups per molecule, with an organohydrogenpolysiloxane that has at least two silicon-bonded hydrogen atoms per molecule, is capable of forming a silicone cured product with excellent elongation properties, thereby completing the present invention.

[0012] Thus, the present invention provides (A) Average unit formula (I): (R 1 3SiO 1 / 2 ) a (R 1 2SiO 2 / 2 ) b (R1 SiO 3 / 2 ) c (SiO 4 / 2 ) d (XO 1 / 2 ) e In formula (I), R 1 each independently represents a monovalent hydrocarbon group containing an alkenyl group, with the proviso that the number of alkenyl groups per molecule is on average less than 2; X is a hydrogen atom or an alkyl group; 0≦a≦1, 0≦b≦1, 0≦c<0.9, 0≦d<0.5, and 0≦e<0.4; a+b+c+d=1.0 and c+d>0; (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, and (C) a catalyst for a curing reaction, The present invention relates to a curable silicone composition comprising:

[0013] The organohydrogenpolysiloxane of component (B) preferably contains three or more silicon-bonded hydrogen atoms per molecule.

[0014] It is preferable that the curable silicone composition of the present invention further contains a linear organopolysiloxane as component (D) which is different from components (A) and (B).

[0015] In the organopolysiloxane component contained in the curable silicone composition of the present invention, the mass ratio of the resinous organopolysiloxane to the linear organopolysiloxane is preferably 9:1 to 1:9.

[0016] The present invention also relates to an encapsulant comprising the curable silicone composition according to the present invention.

[0017] The present invention also relates to an optical semiconductor device comprising the encapsulant according to the present invention. Effect of the Invention

[0018] The curable silicone composition according to the present invention can form a cured product having excellent elongation characteristics. The encapsulant according to the present invention contains the curable silicone composition according to the present invention, so that an optical semiconductor can be encapsulated with a cured product having excellent elongation characteristics. The optical semiconductor device according to the present invention is encapsulated with an encapsulant having excellent elongation characteristics, so that it has excellent reliability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] [Curable Silicone Composition] The curable silicone composition according to the present invention comprises: (A) Average unit formula (I): (R 1 3SiO 1 / 2 ) a (R 1 2SiO 2 / 2 ) b (R 1 SiO 3 / 2 ) c (SiO 4 / 2 ) d (XO 1 / 2 ) e In formula (I), R 1 each independently represents a monovalent hydrocarbon group containing an alkenyl group, with the proviso that the number of alkenyl groups per molecule is on average less than 2; X is a hydrogen atom or an alkyl group; 0≦a≦1, 0≦b≦1, 0≦c<0.9, 0≦d<0.5, and 0≦e<0.4; a+b+c+d=1.0 and c+d>0; (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, and (C) a catalyst for a curing reaction, Includes.

[0020] Each component of the curable silicone composition of the present invention will now be described in detail.

[0021] (A) Resin-like alkenyl-containing organopolysiloxane Component (A) is a resinous alkenyl-containing organopolysiloxane containing, on average, less than two alkenyl groups per molecule and is represented by the following average unit formula (I): Average unit formula (I):(R 1 3SiO 1 / 2 ) a (R 1 2SiO 2 / 2 ) b (R 1 SiO 3 / 2 ) c (SiO 4 / 2 ) d (XO 1 / 2 ) e (In formula (I), R 1 are each independently a monovalent hydrocarbon group containing an alkenyl group, with the provision that the number of alkenyl groups per molecule is on average less than 2, X is a hydrogen atom or an alkyl group, 0≦a≦1, 0≦b≦1, 0≦c≦0.95, 0≦d<0.5, and 0≦e<0.4, a+b+c+d=1.0, and c+d>0.) The curable silicone composition according to the present invention may contain one type of (A) resinous alkenyl-group-containing organopolysiloxane that contains on average less than 2 alkenyl groups per molecule, or may contain two or more types of (A) resinous alkenyl-group-containing organopolysiloxanes that contain on average less than 2 alkenyl groups per molecule.

[0022] In this specification, the resin-like organopolysiloxane refers to an organopolysiloxane having a branched or three-dimensional network structure in its molecular structure. In one embodiment, the resin-like alkenyl group-containing organopolysiloxane of component (A) has at least one RSiO group in its molecular structure. 3 / 2 Siloxane units (T units) represented by the formula: and / or SiO 4 / 2 In one embodiment, the resinous alkenyl group-containing organopolysiloxane of component (A) contains T units in its molecular structure, and may or may not contain Q units, but preferably does not contain them.

[0023] The alkenyl group-containing resinous organopolysiloxane of component (A) represented by formula (I) which contains an average of less than two alkenyl groups per molecule preferably contains alkenyl groups at the molecular chain terminals, but may also contain alkenyl groups on the D units and / or T units.

[0024] In the above formula (I) of the component (A), R 1 Examples of the monovalent hydrocarbon group include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl groups; alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups; and groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms, such as fluorine, chlorine, and bromine atoms. 1 is preferably selected from an alkyl group having 1 to 6 carbon atoms, preferably a methyl group, an aryl group having 6 to 10 carbon atoms, preferably a phenyl group, and an alkenyl group having 2 to 6 carbon atoms, preferably a vinyl group.

[0025] In the above formula (I) of the component (A), X is a hydrogen atom or an alkyl group. The alkyl group for X is preferably an alkyl group having 1 to 3 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, and a propyl group.

[0026] In the above formula (I) of component (A), a is preferably in the range of 0.05≦a≦0.8, more preferably in the range of 0.1≦a≦0.6, and even more preferably in the range of 0.15≦a≦0.4. In the above formula (I) of component (A), b is preferably in the range of 0≦b≦0.9, more preferably in the range of 0≦b≦0.7, and especially in the range of 0≦b≦0.5. In the above formula (I) of component (A), c is preferably in the range of 0.1≦c≦0.9, more preferably in the range of 0.3≦c≦0.85, and especially in the range of 0.5≦c≦0.8. In the above formula (I) of component (A), d is preferably in the range of 0≦d≦0.5, more preferably in the range of 0≦d≦0.3, and even more preferably in the range of 0≦d≦0.1. In the above formula (I), e is preferably in the range of 0≦e≦0.15, more preferably in the range of 0≦e≦0.1, and particularly preferably in the range of 0≦e≦0.05.

[0027] The resin-like alkenyl-containing organopolysiloxane of component (A) represented by formula (I) has an average of less than two alkenyl groups per molecule, preferably an average of 1.9 or less alkenyl groups per molecule, and more preferably an average of 1.8 or less alkenyl groups per molecule. The resin-like alkenyl-containing organopolysiloxane of component (A) usually has an average of one or more alkenyl groups per molecule, preferably an average of 1.1 or more alkenyl groups per molecule, and more preferably an average of 1.2 or more alkenyl groups per molecule.

[0028] The average number of alkenyl groups contained in the resin-like alkenyl-containing organopolysiloxane of component (A) is the number of alkenyl groups per molecule contained in the resin-like alkenyl-containing organopolysiloxane represented by formula (I) averaged over the total number of molecules. The number of alkenyl groups can be determined, for example, by analytical methods such as Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR), or by the titration method described below.

[0029] This section explains how to quantify the amount of alkenyl groups in each component by titration. The alkenyl group content in organopolysiloxane components can be accurately quantified by a titration method commonly known as the Wyss method. The principle is as follows. First, alkenyl groups in the organopolysiloxane raw material are subjected to an addition reaction with iodine monochloride as shown in formula (1). Next, excess iodine monochloride is reacted with potassium iodide and liberated as iodine by the reaction shown in formula (2). The liberated iodine is then titrated with a sodium thiosulfate solution. Equation (1) CH2=CH- + 2ICl → CH2I-CHCl- + ICl (excess) Formula (2) ICl+KI → I2+ KCl The amount of alkenyl groups in the component can be quantified from the difference between the amount of sodium thiosulfate required for titration and the amount of a separately prepared blank solution.

[0030] Furthermore, when the average unit formula of the organopolysiloxane is known from its design, the amount of alkenyl in the organopolysiloxane component can also be calculated from this average unit formula.

[0031] Here we explain how to calculate the average number of alkenyl groups per molecule. The number of alkenyl groups per molecule can be calculated by regarding the alkenyl groups as vinyl groups. When the average unit formula in the design of the organopolysiloxane is known, it can be calculated from the theoretical value of the vinyl group equivalent calculated from the average unit formula and the actual value of the number average molecular weight (Mn) obtained by GPC measurement. Number of alkenyl groups (vinyl groups) per molecule = number average molecular weight (actual value) / vinyl group equivalent of designed structure

[0032] Furthermore, when the designed average unit formula of the organopolysiloxane is unknown, it can be calculated from the amount of alkenyl contained in a certain amount determined by the above measurement method and the actual measured value of the number average molecular weight (Mn) obtained by GPC measurement.

[0033] The molecular weight of the organopolysiloxane of component (A) is not particularly limited, but for example, the number average molecular weight (Mn) calculated based on standard polystyrene is at least 500, preferably at least 1000, and is preferably at most 100,000, more preferably at most 10,000, and even more preferably at most 5,000. The number average molecular weight (Mn) can be measured, for example, by GPC.

[0034] In one embodiment, the resinous alkenyl-containing organopolysiloxane represented by formula (I) of component (A) contains silicon atom-bonded functional groups R 1 The silicon-bonded functional group R of the organopolysiloxane of component (A) contains an aryl group. 1 The amount of aryl groups in the total is not particularly limited, but is, for example, 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more, even more preferably 20 mol% or more, and particularly preferably 25 mol% or more. In addition, the silicon atom-bonded functional group R of the organopolysiloxane of component (A) 1 The amount of aryl groups in the total is, for example, 65 mol % or less, preferably 60 mol % or less, and more preferably 55 mol % or less. The amount of aryl groups in the total silicon-bonded functional groups can be determined by, for example, analysis using a Fourier transform infrared spectrophotometer (FT-IR) or nuclear magnetic resonance (NMR).

[0035] The resin-like alkenyl-containing organopolysiloxane represented by formula (I) of component (A) contains silicon-bonded functional groups R 1 When the aryl group is contained in the aryl group, the aryl group is preferably SiO 3 / 2 The M unit and / or the D unit may or may not contain an aryl group, but preferably does not contain an aryl group.

[0036] The amount of the resin-like alkenyl-containing organopolysiloxane represented by formula (I) of component (A) is not particularly limited, but is preferably 10% by mass or more, more preferably 12% by mass or more, even more preferably 14% by mass or more, preferentially 16% by mass or more, and particularly preferably 18% by mass or more, based on the total mass of all organopolysiloxane components. Also, the resin-like alkenyl-containing organopolysiloxane represented by formula (I) of component (A) is, for example, contained in an amount of 90% by mass or less, preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, based on the total mass of all organopolysiloxane components.

[0037] (B) Organohydrogenpolysiloxane The curable silicone composition of the present invention contains, as a crosslinking agent, an organohydrogenpolysiloxane having two or more silicon-bonded hydrogen atoms per molecule of component (B). Component (B) may consist of only one type of organohydrogenpolysiloxane, or two or more types of organohydrogenpolysiloxanes may be used in combination.

[0038] The molecular structure of the organohydrogenpolysiloxane of component (B) may be, for example, a linear structure, a linear structure having some branches, a resin structure, or a cyclic structure. Preferably, the molecular structure of the organohydrogenpolysiloxane of component (B) is a linear structure or a branched structure, more preferably a branched structure. Preferably, the organohydrogenpolysiloxane of component (B) has at least one RSiO in its molecular structure. 3 / 2 Siloxane units (T units) represented by the formula: and / or SiO 4 / 2In one embodiment, the organohydrogenpolysiloxane of component (B) contains T units in its molecular structure, and may or may not contain Q units, but preferably does not contain them. The component (B) may be an organohydrogenpolysiloxane having only one type of structure, or may be a combination of organohydrogenpolysiloxanes having two or more types of structures.

[0039] The silicon-bonded hydrogen atoms in component (B) may be present at both ends of the molecular chain or in a side chain other than both ends of the molecular chain. Examples of groups bonded to silicon atoms other than hydrogen atoms in component (B) include monovalent hydrocarbon groups other than alkenyl groups, and specific examples include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl groups; and groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms, such as fluorine, chlorine, and bromine atoms. Furthermore, silicon atoms in component (B) may contain small amounts of hydroxyl groups or alkoxy groups such as methoxy groups and ethoxy groups, provided this does not impair the object of the present invention.

[0040] The organohydrogenpolysiloxane of component (B) preferably contains silicon-bonded hydrogen atoms at the molecular chain terminals. 1 / 2 The siloxane units (M units) represented by the following formula (I) have silicon-bonded hydrogen atoms, and the D units and / or T units may or may not contain silicon-bonded hydrogen atoms, but preferably do not contain them.

[0041] Examples of such component (B) include dimethylpolysiloxanes terminated at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers terminated at both molecular chain ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers terminated at both molecular chain ends with dimethylhydrogensiloxy groups, methylhydrogenpolysiloxanes terminated at both molecular chain ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers terminated at both molecular chain ends with trimethylsiloxy groups, and H(CH3)2SiO 1 / 2 Units and SiO 4 / 2 Organopolysiloxanes consisting of units, and H(CH3)2SiO 1 / 2 Unit: (CH3)3SiO 1 / 2 Units and SiO 4 / 2 An example of such an organopolysiloxane is one comprising the units:

[0042] In a preferred embodiment of the present invention, the organohydrogenpolysiloxane of component (B) contains an average of 3 or more silicon-bonded hydrogen atoms per molecule, more preferably 3.5 or more silicon-bonded hydrogen atoms per molecule, and even more preferably 4 or more silicon-bonded hydrogen atoms per molecule. Examples of such component (B) include tris(dimethylhydrogensiloxy)methylsilane, tris(dimethylhydrogensiloxy)phenylsilane, H(CH3)2SiO 1 / 2 Units and SiO 4 / 2 A copolymer consisting of H(CH3)2SiO units. 1 / 2 Units and SiO 4 / 2 Units and (C6H5)SiO 3 / 2 A copolymer consisting of H(CH3)2SiO units. 1 / 2 Units and (C6H5)SiO 3 / 2 and copolymers consisting of units.

[0043] In one embodiment, the organohydrogenpolysiloxane of component (B) contains an aryl group in the silicon-bonded functional group. The amount of aryl groups in the total silicon-bonded functional groups of the organohydrogenpolysiloxane of component (B) is not particularly limited, but is, for example, 2 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more. The amount of aryl groups in the total silicon-bonded functional groups of the organohydrogenpolysiloxane of component (B) is, for example, 40 mol% or less, preferably 30 mol% or less, and even more preferably 25 mol% or less.

[0044] When the organohydrogenpolysiloxane of component (B) contains an aryl group in the silicon-bonded functional group, the aryl group is preferably SiO 3 / 2 The M unit and / or the D unit may or may not contain an aryl group, but preferably does not contain an aryl group.

[0045] The content of component (B) is not particularly limited, but may be, for example, an amount such that the amount of silicon-bonded hydrogen atoms in this component is 0.1 to 10 moles, preferably 0.5 to 5 moles, and particularly 0.8 to 2.0 moles, per mole of silicon-bonded alkenyl groups in the curable silicone composition. The content of silicon-bonded hydrogen atoms in component (B) can be determined, for example, by analysis using a Fourier transform infrared spectrophotometer (FT-IR) or nuclear magnetic resonance (NMR), etc.

[0046] Furthermore, when the average unit formula of the organopolysiloxane design is known, the average number of silicon-bonded hydrogen atoms contained per molecule can also be calculated from this average unit formula. Here, we explain how to calculate the average number of silicon-bonded hydrogen atoms per molecule. When the average unit formula of the organopolysiloxane design is known, the number of silicon-bonded hydrogen atoms per molecule can be calculated from the theoretical value of the silicon-bonded hydrogen group equivalent calculated from the average unit formula and the actual value of the number average molecular weight (Mn) obtained by GPC measurement. Number of silicon-bonded hydrogen atoms per molecule = number average molecular weight (actual value) / silicon-bonded hydrogen atom equivalent of designed structure

[0047] Furthermore, when the design average unit formula of the organopolysiloxane is unknown, it can be calculated from the amount of silicon-bonded hydrogen atoms contained in a certain amount determined by analysis such as Fourier transform infrared spectroscopy (FT-IR) or nuclear magnetic resonance (NMR) and the actual measured value of the number average molecular weight (Mn) obtained by GPC measurement.

[0048] In another embodiment, the content of component (B) is preferably 1 mass% or more, more preferably 5 mass% or more, even more preferably 8 mass% or more, and particularly preferably 10 mass% or more, based on the total mass of all organopolysiloxane components. The organohydrogenpolysiloxane of component (B) is, for example, contained in an amount of 50 mass% or less, preferably 40 mass% or less, more preferably 35 mass% or less, and even more preferably 30 mass% or less, based on the total mass of all organopolysiloxane components.

[0049] (C) Catalyst for curing reaction The curable silicone composition of the present invention contains a curing reaction catalyst (C) for curing the organopolysiloxane component. The curable silicone composition of the present invention may contain one type of curing reaction catalyst (C) or may contain two or more types of curing reaction catalysts (C).

[0050] The curing catalyst of component (C) is a hydrosilylation reaction catalyst for promoting the curing of the silicone composition of hydrosilylation reaction curing type. Such component (C) can be, for example, platinum-based catalysts such as chloroplatinic acid, alcohol solution of chloroplatinic acid, complex of platinum and olefin, complex of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, powder carrying platinum, palladium-based catalysts such as tetrakis(triphenylphosphine)palladium, palladium black, mixture with triphenylphosphine, and further, rhodium-based catalysts, and particularly, platinum-based catalysts are preferred.

[0051] The amount of component (C) blended is the amount of catalyst required to cure the curable silicone composition of the present invention, and is not particularly limited, but for example, when a platinum-based catalyst is used, it is practically preferable for the amount of platinum metal contained in this platinum-based catalyst to be in the silicone composition in an amount within the range of 0.01 to 1000 ppm by weight, and it is particularly preferable for the amount to be within the range of 0.1 to 500 ppm.

[0052] (D) Other organopolysiloxane components The curable silicone composition according to the present invention may contain, as component (D), an organopolysiloxane component other than the above components (A) and (B). Examples of the molecular structure of the organopolysiloxane of component (D) include linear, partially branched linear, branched, cyclic, resinous, and three-dimensional network structures. Component (D) may be one type of organopolysiloxane having such a molecular structure, or a mixture of two or more types of organopolysiloxane having such a molecular structure.

[0053] In one embodiment, the component (D) of the present invention is represented by the general formula (II): R 1 3SiO(R 1 2SiO) m SiR 1 3 (In the formula, R 1are each independently a monovalent hydrocarbon group, and m is an integer of 5 to 1,000.

[0054] In the above formula (II), R 1 The monovalent hydrocarbon group of the formula (I) is R 1 Examples of the alkyl groups include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl groups; alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups; and groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms, such as fluorine, chlorine, and bromine atoms. 1 is preferably selected from an alkyl group having 1 to 6 carbon atoms, preferably a methyl group, and an alkenyl group having 2 to 6 carbon atoms, preferably a vinyl group.

[0055] In the above formula (II), m is preferably an integer of 5 to 500, more preferably an integer of 10 to 300, and even more preferably an integer of 15 to 150.

[0056] In one embodiment, in the linear organopolysiloxane of component (D) represented by formula (II), at least two R 1 may be an alkenyl group. In a preferred embodiment, the linear organopolysiloxane of component (D) represented by formula (II) may be a linear organopolysiloxane capped with alkenyl groups at both molecular chain terminals, that is, containing alkenyl groups at both molecular chain terminals. Preferably, the linear organopolysiloxane of component (D) represented by formula (II) is SiO2 / 2 The siloxane unit (D unit) represented by the following formula may or may not contain an alkenyl group, but preferably does not contain an alkenyl group.

[0057] The linear organopolysiloxane of component (D) represented by formula (II) contains silicon atom-bonded functional groups R 1 When the component (D) contains an alkenyl group, the amount of alkenyl groups in all silicon-bonded functional groups is not particularly limited, but is, for example, 0.3 mol% or more, preferably 0.5 mol% or more, more preferably 0.8 mol% or more, and even more preferably 1 mol% or more. The amount of alkenyl groups in all silicon-bonded functional groups in the linear organopolysiloxane of component (D) represented by formula (II) is, for example, 20 mol% or less, preferably 15 mol% or less, and even more preferably 10 mol% or less.

[0058] In another embodiment, the linear organopolysiloxane of component (D) represented by formula (II) has a silicon atom-bonded functional group R 1 The silicon-bonded functional group R of the linear organopolysiloxane of component (D) represented by formula (II) contains an aryl group. 1 The amount of aryl groups in the total is not particularly limited, but is, for example, 2 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more. The amount of aryl groups in the total silicon-bonded functional groups of the linear organopolysiloxane of component (D) represented by formula (II) is, for example, 55 mol% or less, preferably 50 mol% or less, and even more preferably 45 mol% or less.

[0059] When the linear organopolysiloxane of component (D) represented by formula (II) contains an aryl group in the silicon atom-bonded functional group, the aryl group is preferably SiO 2 / 2 The M unit may or may not contain an aryl group, but preferably does not contain an aryl group.

[0060] The amount of the linear organopolysiloxane of the component (D) represented by formula (II) is not particularly limited, but is preferably contained in an amount of 5 mass% or more, more preferably 10 mass% or more, even more preferably 15 mass% or more, and particularly preferably 20 mass% or more, based on the total mass of all organopolysiloxane components. The linear organopolysiloxane of the component (D) represented by formula (II) is contained, for example, in an amount of 80 mass% or less, preferably 75 mass% or less, and more preferably 70 mass% or less, based on the total mass of all organopolysiloxane components.

[0061] In one embodiment, the component (D) of the present invention is represented by the general formula (III): (R 1 2SiO) n (In the formula, R 1 are each independently a monovalent hydrocarbon group, and n is an integer of 3 to 50.

[0062] In the above formula (III), R 1 The monovalent hydrocarbon group of the formula (I) is R 1 Examples of the alkyl groups include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl groups; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, and phenylpropyl groups; alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups; and groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms, such as fluorine, chlorine, and bromine atoms. 1is preferably selected from an alkyl group having 1 to 6 carbon atoms, preferably a methyl group, and an alkenyl group having 2 to 6 carbon atoms, preferably a vinyl group.

[0063] In the above formula (III), n is preferably an integer of 3-40, and more preferably an integer of 4-20.

[0064] In one embodiment, in the cyclic organopolysiloxane of component (D) represented by formula (III), at least two R 1 The cyclic organopolysiloxane of component (D) represented by formula (III) has a silicon atom-bonded functional group R 1 When the component (D) contains an alkenyl group, the amount of alkenyl groups in all silicon-bonded functional groups is not particularly limited, but is, for example, 10 mol% or more, preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more. The amount of alkenyl groups in all silicon-bonded functional groups in the cyclic organopolysiloxane of component (D) represented by formula (III) is, for example, 80 mol% or less, preferably 70 mol% or less, and even more preferably 60 mol% or less.

[0065] The amount of the cyclic organopolysiloxane of the component (D) represented by formula (III) is not particularly limited, but is preferably 0.3 mass% or more, more preferably 0.5 mass% or more, even more preferably 0.8 mass% or more, and particularly preferably 1 mass% or more, based on the total mass of all organopolysiloxane components.Furthermore, the cyclic organopolysiloxane of the component (D) represented by formula (III) is, for example, contained in an amount of 20 mass% or less, preferably 10 mass% or less, more preferably 5 mass% or less, based on the total mass of all organopolysiloxane components.

[0066] In yet another embodiment, the (D) component of the present invention has the average unit formula (IV): (R 2 3SiO 1 / 2 ) a(R 2 2SiO 2 / 2 ) b (R 2 SiO 3 / 2 ) c (SiO 4 / 2 ) d (XO 1 / 2 ) e (In the formula, R 2 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups or epoxy-containing organic groups, provided that at least one R 2 is an epoxy group-containing organic group, X is a hydrogen atom or an alkyl group, 0≦a≦1, 0≦b≦1, 0≦c<0.9, 0≦d<0.5, and 0≦e<0.4, a+b+c+d=1.0, and c+d>0.

[0067] In the above (IV), R 2is preferably selected from alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl groups; alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl groups; groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms, such as fluorine, chlorine, and bromine atoms, and epoxy group-containing organic groups. Examples of epoxy group-containing groups include glycidoxyalkyl groups such as a 2-glycidoxyethyl group, a 3-glycidoxypropyl group, and a 4-glycidoxybutyl group; epoxycycloalkylalkyl groups such as a 2-(3,4-epoxycyclohexyl)-ethyl group and a 3-(3,4-epoxycyclohexyl)-propyl group; and epoxyalkyl groups such as a 3,4-epoxybutyl group and a 7,8-epoxyoctyl group. Of these, preferred is a glycidoxyalkyl group, and particularly preferred is a 3-glycidoxypropyl group.

[0068] In a preferred embodiment, the epoxy group-containing resinous organopolysiloxane of formula (IV) is R 2 and more preferably (R 2 3SiO 1 / 2 ) units of R 2 The amount of alkenyl groups in all silicon-bonded functional groups in the epoxy group-containing resinous organopolysiloxane of component (D) is not particularly limited, but is preferably 0.1 mol % or more, more preferably 1 mol % or more, and even more preferably 2 mol % or more, and is, for example, 25 mol % or less, preferably 20 mol % or less, and more preferably 15 mol % or less.

[0069] In a preferred embodiment, the epoxy group-containing resinous organopolysiloxane of formula (IV) is 22SiO 2 / 2 ) units of R 2 The amount of epoxy-containing organic groups in the total silicon-bonded functional groups in the epoxy-containing resin-like organopolysiloxane of component (D) represented by formula (IV) is not particularly limited, but is preferably 0.1 mol% or more, more preferably 1 mol% or more, and even more preferably 5 mol% or more, for example, 50 mol% or less, preferably 40 mol% or less, and more preferably 30 mol% or less. The amount of epoxy-containing organic groups can be determined by analysis such as a Fourier transform infrared spectrophotometer (FT-IR) or nuclear magnetic resonance (NMR).

[0070] In another embodiment, the epoxy group-containing resinous organopolysiloxane of component (D) represented by formula (IV) contains silicon atom-bonded functional groups R 2 contains an aryl group, preferably (R 2 SiO 3 / 2 ) units of R 2 The silicon atom-bonded functional group R of the epoxy group-containing resinous organopolysiloxane of component (D) represented by formula (IV) may contain an aryl group. 2 The amount of aryl groups in the total is not particularly limited, but is, for example, 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more. The amount of aryl groups in the total silicon-bonded functional groups of the epoxy-containing resin-like organopolysiloxane of component (D) represented by formula (IV) is, for example, 60 mol% or less, preferably 50 mol% or less, and even more preferably 40 mol% or less.

[0071] In the above formula (IV), a is preferably in the range of 0≦a≦0.8, more preferably in the range of 0.05≦a≦0.6, and particularly in the range of 0.1≦a≦0.4. In the formula (X), b is preferably in the range of 0≦b≦0.9, more preferably in the range of 0.1≦b≦0.7, and particularly in the range of 0.2≦b≦0.5. In the formula (X), c is preferably in the range of 0.1≦c<0.9, more preferably in the range of 0.2≦c≦0.8, and particularly in the range of 0.3≦c≦0.7. In the formula (X), d is preferably in the range of 0≦d<0.5, more preferably in the range of 0≦d≦0.4, and even more preferably in the range of 0≦d≦0.3. In the formula (X), e is preferably in the range of 0≦e≦0.3, more preferably in the range of 0≦e≦0.2, and particularly in the range of 0≦e≦0.1.

[0072] The amount of the epoxy-containing resin-like organopolysiloxane of component (D) represented by formula (IV) is not particularly limited, but is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 1.5% by mass or more, and particularly preferably 2% by mass or more, based on the total mass of all organopolysiloxane components. Also, the epoxy-containing resin-like organopolysiloxane of component (D) represented by formula (IV) is, for example, contained in an amount of 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, based on the total mass of all organopolysiloxane components.

[0073] In a specific embodiment of the present invention, the curable silicone composition according to the present invention can contain a resinous organopolysiloxane and a linear organopolysiloxane in a mass ratio of, for example, 1:9 to 9:1, preferably a mass ratio of 1:7 to 7:1, and more preferably a mass ratio of 1:5 to 5:1. In another specific embodiment of the present invention, the curable silicone composition according to the present invention can contain a resinous alkenyl group-containing organopolysiloxane and a linear alkenyl group-containing organopolysiloxane in a mass ratio of, for example, 1:9 to 9:1, preferably a mass ratio of 1:7 to 7:1, and more preferably a mass ratio of 1:5 to 5:1.

[0074] The curable silicone composition of the present invention can be blended with optional components within the scope of the present invention without impairing the object of the present invention.The optional components include, for example, acetylene compounds, organic phosphorus compounds, vinyl group-containing siloxane compounds, hydrosilylation reaction inhibitors, cure retarders, pigments, inorganic fillers, or inorganic fillers whose surfaces are hydrophobically treated with organic silicon compounds, powder surface treatment agents or surfactants, organopolysiloxanes that do not contain silicon-bonded hydrogen atoms and silicon-bonded alkenyl groups, tackifiers, release agents, metal soaps, heat resistance agents, cold resistance agents, thermally conductive fillers, flame retardant agents, thixotropy agents, phosphors, solvents, etc.

[0075] The hydrosilylation reaction inhibitor is a component for inhibiting the hydrosilylation reaction of the silicone composition, and specific examples include reaction inhibitors based on acetylenes such as ethynylcyclohexanol, amines, carboxylates, phosphites, etc. The amount of reaction inhibitor added is usually 0.001 to 5% by mass of the entire composition.

[0076] Examples of the curing retarder include alkyne alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 2-phenyl-3-butyn-2-ol, and 1-ethynyl-1-cyclohexanol; enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; alkenyl-containing low molecular weight siloxanes such as tetramethyltetravinylcyclotetrasiloxane and tetramethyltetrahexenylcyclotetrasiloxane; and alkynyloxysilanes such as methyl-tris(1,1-dimethylpropynyloxy)silane and vinyl-tris(1,1-dimethylpropynyloxy)silane. The content of this curing retarder is not limited, but is preferably within the range of 10 to 10,000 ppm by mass with respect to the present composition.

[0077] Examples of pigments include metal oxides such as silica, titanium oxide, aluminum oxide, zinc oxide, zirconium oxide, and magnesium oxide; hollow fillers such as glass balloons and glass beads; and other pigments such as barium sulfate, zinc sulfate, barium titanate, aluminum nitride, boron nitride, and antimony oxide. Examples of black pigments include iron oxide, aniline black, activated carbon, graphite, carbon nanotubes, and carbon black.

[0078] Examples of inorganic fillers include metal oxide particles such as fumed silica, crystalline silica, precipitated silica, silsesquioxane, magnesium oxide, iron oxide, talc, mica, diatomaceous earth, and glass beads; inorganic fillers such as aluminum hydroxide, magnesium carbonate, calcium carbonate, and zinc carbonate; fibrous fillers such as glass fiber; and fillers obtained by subjecting these fillers to surface hydrophobic treatment with organosilicon compounds such as organoalkoxysilane compounds, organochlorosilane compounds, organosilazane compounds, and low molecular weight siloxane compounds. Silicone rubber powder, silicone resin powder, and the like may also be blended. However, the blending amount of inorganic fillers may be 40% by mass or less, 30% by mass or less, 20% by mass or less, or 10% by mass or less of the present composition.

[0079] The surface treatment agent for the powder is not particularly limited, but examples thereof include organosilazanes, organocyclosiloxanes, organochlorosilanes, organoalkoxysilanes, low molecular weight linear siloxanes, organic compounds, and the like. Examples of the organic compounds include polyhydric alcohols, alkanolamines or derivatives thereof, organosilicon compounds such as organosiloxanes, higher fatty acids or metal salts thereof, organometallic compounds, organometallic complexes, fluorine-based organic compounds, anionic surfactants, cationic surfactants, and nonionic surfactants.

[0080] As the adhesion promoter, an organic silicon compound having at least one alkoxy group bonded to a silicon atom in one molecule is preferred. Examples of this alkoxy group include methoxy, ethoxy, propoxy, butoxy, and methoxyethoxy groups, and particularly preferred is methoxy. Examples of groups bonded to silicon atoms other than the alkoxy group in the organic silicon compound include halogen-substituted or unsubstituted monovalent hydrocarbon groups such as alkyl groups, alkenyl groups, aryl groups, aralkyl groups, and halogenated alkyl groups; glycidoxyalkyl groups such as 3-glycidoxypropyl and 4-glycidoxybutyl groups; epoxycyclohexylalkyl groups such as 2-(3,4-epoxycyclohexyl)ethyl and 3-(3,4-epoxycyclohexyl)propyl groups; epoxyalkyl groups such as 3,4-epoxybutyl and 7,8-epoxyoctyl groups; acrylic group-containing monovalent organic groups such as 3-methacryloxypropyl groups; and hydrogen atoms. The organosilicon compound preferably has a group capable of reacting with the alkenyl group or silicon-bonded hydrogen atom in the composition, and more specifically, preferably has a silicon-bonded hydrogen atom or an alkenyl group.In addition, since it can provide good adhesion to various substrates, the organosilicon compound preferably has at least one epoxy-containing monovalent organic group in one molecule.Examples of such organosilicon compounds include organosilane compounds, organosiloxane oligomers, and alkyl silicates.Examples of the molecular structure of the organosiloxane oligomer or alkyl silicate include linear, partially branched linear, branched, cyclic, and net-like, and in particular, linear, branched, and net-like are preferred.Examples of the organosilicon compound include silane compounds such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-methacryloxypropyltrimethoxysilane; siloxane compounds having at least one silicon-bonded alkenyl group or silicon-bonded hydrogen atom, and at least one silicon-bonded alkoxy group in one molecule; a mixture of a silane compound or siloxane compound having at least one silicon-bonded alkoxy group and a siloxane compound having at least one silicon-bonded hydroxy group and at least one silicon-bonded alkenyl group in one molecule; methyl polysilicate, ethyl polysilicate, and epoxy group-containing ethyl polysilicate. The adhesion promoter is preferably a low-viscosity liquid, and although there are no limitations on its viscosity, it is preferably within the range of 1 to 500 mPa·s at 25°C. Furthermore, the content of this adhesion promoter is not limited, but is preferably within the range of 0.01 to 10 parts by mass per 100 parts by mass of the total of the present composition.

[0081] The release agent is not particularly limited, and examples thereof include carboxylic acid-based release agents, ester-based release agents, ether-based release agents, ketone-based release agents, and alcohol-based release agents. These may be used alone or in combination of two or more. The release agent may be one that does not contain silicon atoms, one that contains silicon atoms, or a mixture thereof. More specifically, examples of the release agent include carnauba wax, montan wax, calcium stearate, calcium montanate, magnesium stearate, magnesium montanate, zinc stearate, zinc montanate, ester wax, and olefin wax.

[0082] The curable silicone composition of the present invention can be prepared by mixing each component. The method of mixing each component can be a conventionally known method and is not particularly limited, but usually a homogeneous mixture can be obtained by simple stirring. In addition, when a solid component such as an inorganic filler is included as an optional component, mixing using a mixing device is more preferable. Such a mixing device is not particularly limited, and examples thereof include a single-shaft or double-shaft continuous mixer, a two-roll mixer, a Ross mixer, a Hobart mixer, a dental mixer, a planetary mixer, a kneader mixer, and a Henschel mixer.

[0083] [Sealing material] The present invention also relates to an encapsulant containing the curable silicone composition of the present invention. The encapsulant of the present invention is an encapsulant for optical semiconductors. The shape of the encapsulant of the present invention is not particularly limited, but is preferably a film or sheet. Therefore, the present invention also relates to a film obtained by solidifying the curable silicone composition of the present invention. The film of the present invention can be preferably used as a film-shaped encapsulant for encapsulating semiconductor elements. The semiconductor encapsulated by the encapsulant or film of the present invention is not particularly limited, and examples thereof include semiconductors such as SiC and GaN, or optical semiconductors such as light-emitting diodes.

[0084] The encapsulant or film of the present invention contains the curable silicone composition of the present invention, and therefore is able to encapsulate the optical semiconductor with a cured product that has excellent elongation properties, thereby providing a highly reliable optical semiconductor device.

[0085] [Optical semiconductor device] The optical semiconductor device of the present invention is an optical semiconductor element encapsulated with the encapsulant of the present invention. In other words, the optical semiconductor element is encapsulated, covered, or adhered with the cured product of the curable silicone composition of the present invention. Examples of the optical semiconductor element include light-emitting diodes (LEDs), semiconductor lasers, photodiodes, phototransistors, solid-state imaging devices, and light emitters and receivers for photocouplers, and light-emitting diodes (LEDs) are particularly preferred.

[0086] Since light emitting diodes (LEDs) emit light from the top, bottom, left and right of the optical semiconductor element, it is preferable that the components constituting the light emitting diode (LED) are not light absorbing, and that materials with high light transmittance or high reflectance are preferred. Therefore, it is preferable that the substrate on which the optical semiconductor element is mounted is also made of a material with high light transmittance or high reflectance. Examples of substrates on which such optical semiconductor elements are mounted include conductive metals such as silver, gold, and copper; non-conductive metals such as aluminum and nickel; thermoplastic resins mixed with white pigments such as PPA and LCP; thermosetting resins containing white pigments such as epoxy resins, BT resins, polyimide resins, and silicone resins; and ceramics such as alumina and alumina nitride.

[0087] The optical semiconductor device of the present invention is highly reliable since it is encapsulated with the encapsulant of the present invention, which has excellent elongation characteristics. EXAMPLES

[0088] The curable silicone composition of the present invention will be described in more detail below with reference to the following examples and comparative examples.

[0089] In the following examples and comparative examples, the following raw material components were used, where Me represents a methyl group, Vi represents a vinyl group, Ph represents a phenyl group, and Ep represents a 3-glycidoxypropyl group.

[0090] Component (a): Resinous alkenyl-containing organopolysiloxane Component a-1: A compound having a number average molecular weight of 1600 and an average unit formula (MeSiO 1 / 2 ) 0.13 (ViMe2SiO 1 / 2 ) 0.09 (MeSiO 3 / 2 ) 0.39 (PhSiO 3 / 2 ) 0.39 Resin-like alkenyl-containing organopolysiloxane represented by the formula: Average number of vinyl groups per molecule: 1.5 Component a-2: A compound having a number average molecular weight of 1700 and an average unit formula (MeSiO 1 / 2 ) 0.15(ViMe2SiO 1 / 2 ) 0.07 (MeSiO 3 / 2 ) 0.39 (PhSiO 3 / 2 ) 0.39 Resin-like alkenyl-containing organopolysiloxane represented by the formula: Average number of vinyl groups per molecule: 1.3 Component a-3: A compound having a number average molecular weight of 1200 and an average unit formula (MeSiO 1 / 2 ) 0.07 (ViMe2SiO 1 / 2 ) 0.18 (PhSiO 3 / 2 ) 0.75 Resin-like alkenyl-containing organopolysiloxane represented by the formula: Average number of vinyl groups per molecule: 1.8 Component a-4: A compound having a number average molecular weight of 1400 and an average unit formula (MeSiO 1 / 2 ) 0.13 (ViMe2SiO 1 / 2 ) 0.09 (MeSiO 3 / 2 ) 0.39 (PhSiO 3 / 2 ) 0.39 Resin-like alkenyl-containing organopolysiloxane represented by the formula: Average number of Vi groups per molecule: 1.3 Component a'-1: Average unit formula (Me3SiO 1 / 2 ) 0.05 (ViMe2SiO 1 / 2 ) 0.17 (MeSiO 3 / 2 ) 0.39 (PhSiO 3 / 2 ) 0.39 Resin-like alkenyl-containing organopolysiloxane represented by the formula: Average number of vinyl groups per molecule: 3.0 Component a'-2: Average unit formula (ViMe2SiO 1 / 2 ) 0.25 (PhSiO 3 / 2 ) 0.75 Resin-like alkenyl-containing organopolysiloxane represented by the formula: Average number of vinyl groups per molecule: 2.5 Component b-1: Average unit formula (HMe2SiO 3 / 2 ) 60 (PhSiO 3 / 2 ) 40Organohydrogenpolysiloxane: Average number of silicon-bonded hydrogen atoms per molecule: 4.6 Component c: A complex of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane having a platinum concentration of 4.0% by mass: 5,000 ppm (catalytic amount) per 100 parts by mass of the total organopolysiloxane components. Component d-1: General formula ViMe2SiO(MePhSiO) 20 Linear organopolysiloxane with both ends capped with alkenyl groups, represented by SiViMe2 Component d-2: General formula ViMe2SiO(Me2SiO) 60 (Ph2SiO) 30 Linear organopolysiloxane with both ends capped with alkenyl groups, represented by SiViMe2 Component d-3: Alkenyl-containing cyclic organopolysiloxane represented by the general formula (ViMeSiO)4 Component d-4: Average unit formula (ViMe2SiO 1 / 2 ) 0.18 (EpMeSiO 2 / 2 ) 0.29 (PhSiO 3 / 2 ) 0.53 An epoxy group-containing resin-like organopolysiloxane represented by the formula:

[0091] [Examples 1 to 4 and Comparative Examples 1 to 3] The components were mixed in the compositions (mass %) shown in Tables 1 and 2 to prepare curable silicone compositions.

[0092] [evaluation] For each composition of the Examples and Comparative Examples, the elongation of the cured product was measured as follows, and the results are shown in Table 1.

[0093] The curable silicone composition was applied in a sheet form and heated at 150°C for 1 hour to produce a 1 mm thick sheet of cured material. This was then punched out into a No. 3 dumbbell shape as specified in JIS K6251-1993 "Tensile test method for vulcanized rubber", and the elongation at break (%) was measured using a Shimadzu autograph.

[0094] [Table 1]

[0095] [Table 2]

[0096] As can be seen from the above results, the cured products obtained by curing the curable silicone compositions of Examples 1 and 2 of the present invention exhibited excellent elongation properties. [Industrial Applicability]

[0097] The curable silicone composition of the present invention is particularly useful as an encapsulant for optical semiconductors such as light emitting diodes (LEDs), semiconductor lasers, photodiodes, phototransistors, solid-state imaging devices, and light emitters and photoreceptors for photocouplers.

Claims

1. (A) Average unit formula (I): (R １ ３ SiO １／２ ) ａ (R １ ２ SiO ２／２ ) ｂ (R １ SiO ３／２ ) ｃ (SiO ４／２ ) ｄ (X.O. １／２ ) ｅ In formula (I), R １ each independently represents a monovalent hydrocarbon group containing an alkenyl group, with the proviso that the number of alkenyl groups per molecule is on average less than 2, X is a hydrogen atom or an alkyl group, 0.1≦a≦1, 0≦b≦0.5, 0<c<0.9, d=0, and 0≦e<0.4, and a+b+c+d=1.0; (B) an organohydrogenpolysiloxane containing two or more silicon-bonded hydrogen atoms per molecule, and (C) a catalyst for the curing reaction; 1. A curable silicone composition comprising:

2. 2. The curable silicone composition according to claim 1, wherein the organohydrogenpolysiloxane of component (B) contains three or more silicon-bonded hydrogen atoms per molecule.

3. 3. The curable silicone composition according to claim 1, further comprising (D) a linear organopolysiloxane that is different from components (A) and (B).

4. 4. The curable silicone composition according to claim 3, wherein the mass ratio of the resinous organopolysiloxane to the linear organopolysiloxane is from 9:1 to 1:

9.

5. An encapsulant comprising the curable silicone composition according to any one of claims 1 to 4.

6. An optical semiconductor device comprising the encapsulant according to claim 5 .

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