WO2025033285A1 - Curable silicone composition, adhesive, and optical semiconductor device - Google Patents

Abstract

This curable silicone composition comprises (A) an alkenyl group-containing organopolysiloxane having at least two alkenyl groups per molecule, (B) an organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms per molecule, (C) a thermally conductive filler constituting 5 mass% or more of the total mass of the composition, (D) a cerium-containing organopolysiloxane, and (E) a curing catalyst.

Description

CURABLE SILICONE COMPOSITION, ADHESIVE, AND OPTICAL SEMICONDUCTOR DEVICE

The present invention relates to a curable silicone composition, more specifically, to a curable silicone composition suitable for use as an adhesive for optical semiconductor devices. The present invention also relates to an optical semiconductor device provided with an adhesive made of a cured product of the curable silicone composition.
This application claims priority based on Japanese Patent Application No. 2023-127893, filed in Japan on August 4, 2023, the contents of which are incorporated herein by reference.

Curable silicone compositions are used in a wide range of industrial fields because they cure to form a cured product with excellent heat resistance, cold resistance, electrical insulation, weather resistance, water resistance, and transparency. In particular, the cured product is less likely to discolor than other organic materials, and there is little deterioration in physical properties such as durability, so it is widely used as a silicone encapsulant for optical materials, especially for optical semiconductor devices such as light-emitting diodes (LEDs).

It is well known that cerium-containing organopolysiloxanes are added to such curable silicone compositions to improve the heat resistance and/or light resistance of the cured product.

For example, Patent Document 1 describes a linear organopolysiloxane having (A) at least two alkenyl groups in one molecule, and (B) an organopolysiloxane having the following average unit formula: (R ¹ SiO _3/2 ) _a (R ¹ ₂ SiO _2/2 ) _b (R ¹ ₃ SiO _1/2 ) _c (SiO _4/2 ) _d (XO _1/2 ) _e (wherein R ¹ is independently an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a group in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms, provided that at least two R (A) is an organopolysiloxane represented by the formula (A) (wherein ¹ is the alkenyl group, X is a hydrogen atom or an alkyl group, a is a number from 0 to 0.3, b is 0 or a positive number, c is a positive number, d is a positive number, e is a number from 0 to 0.4, and a+b+c+d=1, c/d is a number from 0 to 10, and b/d is a number from 0 to 0.5), (an amount such that the mass ratio of component (A) to component (B) is 1/99 to 99/1), (C) an organopolysiloxane having at least two silicon atom bonds in one molecule, The document describes a curable silicone composition comprising at least an organopolysiloxane having combined hydrogen atoms (an amount such that in this component there are 0.1 to 10 moles of silicon-bonded hydrogen atoms per mole of alkenyl groups in components (A) and (B) combined), (D) a cerium-containing organopolysiloxane (an amount such that the cerium atoms in component (D) are in an amount of 20 to 2,000 ppm by mass, based on the total mass of the composition), and (E) a catalytic amount of a hydrosilylation reaction catalyst.

Furthermore, Patent Document 2 describes a curable white silicone composition comprising (A) an organopolysiloxane having at least two alkenyl groups in one molecule, (B) a cerium-containing organopolysiloxane, (C) a white pigment, and (D) a curing catalyst.

However, conventional curable silicone compositions have the problem that when they contain large amounts of thermally conductive fillers such as aluminum oxide, their thermal stability decreases, resulting in a decrease in strength after aging at high temperatures.

Japan Special Table No. 2016-513165 Japanese Patent Application Publication No. 2021-88678

The object of the present invention is to provide a curable silicone composition that can form a cured product that exhibits excellent thermal stability even when it contains a large amount of thermally conductive filler.

Another object of the present invention is to provide an encapsulant containing the curable silicone composition of the present invention. A further object of the present invention is to provide an optical semiconductor device encapsulated with the encapsulant of the present invention.

In order to solve the above problems, the inventors conducted extensive research and surprisingly discovered that a curable silicone composition containing a cerium-containing organopolysiloxane can form a cured product that exhibits excellent thermal stability, even when the composition contains a large amount of thermally conductive filler, and thus arrived at the present invention.

Thus, the present invention provides
(A) an alkenyl-containing organopolysiloxane having at least two alkenyl groups per molecule;
(B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule;
(C) 5% by mass or more of a thermally conductive filler based on the total mass of the composition;
The present invention relates to a curable silicone composition comprising: (D) a cerium-containing organopolysiloxane; and (E) a curing catalyst.

It is preferable that the (A) alkenyl group-containing organopolysiloxane contains an MQ resin.

The (C) thermally conductive filler is preferably a metal oxide.

It is preferable that the (C) thermally conductive filler contains two types of thermally conductive filler having different average particle sizes.

The amount of cerium atoms in the (D) cerium-containing organopolysiloxane is preferably 1 to 100 ppm relative to the total mass of all organopolysiloxane components in the composition.

The present invention also relates to an adhesive comprising the curable silicone composition of the present invention.

The present invention also relates to an optical semiconductor device equipped with the adhesive of the present invention.

The curable silicone composition of the present invention can form a cured product that exhibits excellent thermal stability, even when it contains a certain amount of thermally conductive filler.

[Curable Silicone Composition]
The curable silicone composition according to the present invention comprises:
(A) an alkenyl-containing organopolysiloxane having at least two alkenyl groups per molecule;
(B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule;
(C) 5% by mass or more of a thermally conductive filler based on the total mass of the composition;
(D) a cerium-containing organopolysiloxane; and (E) a curing catalyst.

The components of the curable silicone composition of the present invention are described in detail below.

(A) Alkenyl-Containing Organopolysiloxane Having at Least Two Alkenyl Groups Per Molecule Component (A) is a curable organopolysiloxane having at least two alkenyl groups per molecule. The curable silicone composition according to the present invention may contain one type of (A) alkenyl-containing organopolysiloxane, or may contain two or more types of (A) alkenyl-containing organopolysiloxanes.

Examples of the molecular structure of component (A) include linear, partially branched linear, branched, resinous, cyclic, and three-dimensional network structures. Component (A) may be one type of organopolysiloxane having these molecular structures, or a mixture of two or more types of organopolysiloxane having these molecular structures. In this specification, resinous means that the molecular structure has a branched or three-dimensional network structure.

The curable silicone composition of the present invention preferably contains, as component (A), a resinous alkenyl group-containing organopolysiloxane. The curable silicone composition of the present invention preferably contains, as component (A), a linear alkenyl group-containing organopolysiloxane. The curable silicone composition of the present invention preferably contains, as component (A), both a resinous alkenyl group-containing organopolysiloxane and a linear alkenyl group-containing organopolysiloxane.

Examples of the alkenyl group contained in component (A) include alkenyl groups having 2 to 12 carbon atoms, such as vinyl groups, allyl groups, butenyl groups, pentenyl groups, hexenyl groups, heptenyl groups, octenyl groups, nonenyl groups, decenyl groups, undecenyl groups, and dodecenyl groups, with vinyl groups being preferred.

Groups bonded to silicon atoms other than alkenyl groups contained in component (A) include halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, such as 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; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, 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, chlorine, or bromine. The silicon atoms in component (A) may contain small amounts of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy, as long as the purpose of the present invention is not impaired. The groups bonded to silicon atoms other than the alkenyl groups of component (A) are preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly methyl groups.

In one embodiment of the present invention, component (A) may contain a resin-like alkenyl group-containing organopolysiloxane as component (A-1). The resin-like alkenyl group-containing organopolysiloxane (A-1) is preferably
Average unit formula (I-a): (R ¹ ₃ SiO _1/2 ) _a (R ¹ ₂ SiO _2/2 ) _b (R ¹ SiO _3/2 ) _c (SiO _4/2 ) _d (XO _1/2 ) _e
(In formula (I-a), R ¹ 's are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, with the proviso that in one molecule, at least two R ¹ 's are alkenyl groups, 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. e represents the number of (XO) groups when the total number of silicon atoms is 1 (the ratio of the number of (XO) groups to the total number of silicon atoms)).

Examples of the halogen-substituted or unsubstituted monovalent hydrocarbon group for R ¹ in the above formula (I-a) include alkyl groups having 1 to 12 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a cyclohexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, or a dodecyl group; and alkyl groups having 6 to 20 carbon atoms, such as a phenyl group, a tolyl group, a xylyl group, or a naphthyl group. Examples of the alkyl group include an aryl group, an aralkyl group having 7 to 20 carbon atoms, such as a benzyl group, a phenethyl group, or a phenylpropyl group, an alkenyl group having 2 to 12 carbon atoms, such as a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, or a dodecenyl group, and a group in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms, such as fluorine atoms, chlorine atoms, or bromine atoms. R ¹ may be a small amount of hydroxyl groups or alkoxy groups, such as a methoxy group or an ethoxy group, within the scope of the present invention. R ¹ is preferably selected from an alkyl group having 1 to 6 carbon atoms, particularly a methyl group, and an alkenyl group having 2 to 6 carbon atoms, particularly a vinyl group.

In the above formula (I-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 include a methyl group, an ethyl group, and a propyl group. X is preferably a hydrogen atom.

In the above formula (I-a), a is preferably in the range of 0.1≦a≦0.8, more preferably in the range of 0.2≦a≦0.7, and even more preferably in the range of 0.3≦a≦0.6. In the above formula (I-a), b is preferably in the range of 0≦b≦0.5, more preferably in the range of 0≦b≦0.3, and especially in the range of 0≦b≦0.1. In the above formula (I-a), c is preferably in the range of 0≦c<05, more preferably in the range of 0≦c≦0.3, and especially in the range of 0≦c≦0.1. In the above formula (I-a), d is preferably in the range of 0.1≦d≦0.8, more preferably in the range of 0.2≦d≦0.7, and even more preferably in the range of 0.3≦d≦0.6. In the above formula (I-a), e is preferably in the range of 0≦e≦0.15, more preferably in the range of 0≦e≦0.1, and especially in the range of 0≦e≦0.05.

In a preferred embodiment of the present invention, the resin-like alkenyl-group-containing organopolysiloxane of component (A-1) contains siloxane units (Q units) represented by SiO _4/2 in its structure. The resin-like alkenyl-group-containing organopolysiloxane of component (A-1) may or may not contain siloxane units (D units) represented by SiO _2/2 in its structure, but preferably does not. Furthermore, the resin-like alkenyl-group-containing organopolysiloxane of component (A-1) may or may not contain siloxane units (T units) represented by SiO _3/2 in its structure, but preferably does not contain them.

In a preferred embodiment of the present invention, the resin-like alkenyl-group-containing organopolysiloxane of component (A-1) contains alkenyl groups at the molecular terminals. The resin-like organopolysiloxane of component (A-1) preferably has alkenyl groups in the siloxane units (M units) represented by SiO _1/2 , and may or may not contain alkenyl groups in side chains on the molecular chain (i.e., siloxane units (D units) represented by SiO _2/2 and siloxane units (T units) represented by SiO _3/2 ), but preferably does not contain any alkenyl groups.

In a preferred embodiment of the present invention, the resinous alkenyl-containing organopolysiloxane of component (A-1) contains an MQ resin or consists solely of an MQ resin. MQ resin is an organopolysiloxane consisting solely of siloxane units (M units) represented by SiO _1/2 and siloxane units (Q units) represented by SiO _4/2 . The MQ resin of component (A-1) can preferably be represented by the following average unit formula (I-b):
Average unit formula (Ib): (R ¹ ₃ SiO _1/2 ) _s (SiO _4/2 ) _t (XO _1/2 ) _u
In the formula, R ¹ 's are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, provided that in one molecule, at least two R ¹ 's are alkenyl groups, 0<s<1, 0<t<1, 0≦u<0.4, and s+t=1.0, and u represents the number of (XO) groups when the total number of silicon atoms is 1 (the ratio of the number of (XO) groups to the total number of silicon atoms).

R ¹ in formula (II-b) is as described in formula (II-a).

In formula (II-b), s is preferably in the range of 0.2≦s≦0.8, more preferably in the range of 0.3≦s≦0.7, and even more preferably in the range of 0.4≦s≦0.6. In formula (II-b), t is preferably in the range of 0.2≦t≦0.8, more preferably in the range of 0.3≦t≦0.7, and especially in the range of 0.3≦t≦0.7. In formula (II-b), u is preferably in the range of 0≦u≦0.3, more preferably in the range of 0≦u≦0.2, and especially in the range of 0≦u≦0.1.

The content of alkenyl groups in all silicon-bonded organic groups in the resinous alkenyl-group-containing organopolysiloxane of component (A-1) is not particularly limited, but may be, for example, 3 mol% or more, preferably 5 mol% or more, and more preferably 10 mol% or more of the total silicon-bonded organic groups, and 40 mol% or less, preferably 30 mol% or more, and more preferably 20 mol% or less of the total silicon-bonded organic groups. The alkenyl group content 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.

The method of quantifying the amount of alkenyl groups in each component by titration is described below. The alkenyl group content in an organopolysiloxane component can be accurately quantified by a titration method commonly known as the Wyss method. The principle is as follows. First, an addition reaction is caused between the alkenyl groups in the organopolysiloxane raw material and iodine monochloride as shown in formula (1). Next, the 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) CH ₂ ═CH− + 2ICl → CH ₂ I−CHCl− + ICl (excess)
Formula (2) ICl + KI → I ₂ + 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.

The MQ resin of component (A-1) may be solid at room temperature (25°C).

When component (A) contains one or more types of resinous organopolysiloxane (A-1), the content is not particularly limited, but is preferably 1 mass% or more, more preferably 3 mass% or more, and even more preferably 5 mass% or more, based on the total mass of the curable silicone composition of the present invention. Also, the content of component (A-1) is preferably 70 mass% or less, more preferably 60 mass% or less, and even more preferably 50 mass% or less, based on the total mass of the curable silicone composition. In this specification, the upper and lower limits of the numerical ranges can be arbitrarily combined to set the numerical range.

The component (A) may contain a linear alkenyl group-containing organopolysiloxane as the component (A-2). The linear alkenyl group-containing organopolysiloxane of the component (A-2) is preferably
Average structural formula (I-c): R ¹ ₃ SiO (R ¹ ₂ SiO _2/2 ) _m SiR ² ₃
(In formula (I-c), R ¹ 's are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, with the proviso that in one molecule, at least two R ¹ 's are alkenyl groups, and m is 1 to 500.)

In the above formula (Ic), the halogen-substituted or unsubstituted monovalent hydrocarbon group for R ¹ can be the same as in the above formula (Ia).
In the above formula (Ic), m is preferably 2-300, more preferably 5-200, further preferably 10-100, and particularly preferably 15-50.

Such components (A-2) include dimethylpolysiloxanes blocked at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylpolysiloxanes blocked at both molecular chain terminals with diphenylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers blocked at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylsiloxane-diphenylsiloxane copolymers blocked at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers blocked at both molecular chain terminals with diphenylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers blocked at both molecular chain terminals with dimethylvinylsiloxy groups, Examples include dimethylsiloxane-methylphenylsiloxane-methylvinylsiloxane copolymers capped with dimethylvinylsiloxy groups, dimethylsiloxane-diphenylsiloxane-methylvinylsiloxane copolymers capped with dimethylvinylsiloxy groups at both molecular chain terminals, methylvinylpolysiloxane capped with trimethylsiloxy groups at both molecular chain terminals, methylvinylsiloxane-methylphenylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain terminals, methylvinylsiloxane-diphenylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain terminals, and dimethylsiloxane-methylvinylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain terminals.

In a preferred embodiment of the present invention, the linear alkenyl-containing organopolysiloxane of component (A-2) may be a linear organopolysiloxane capped with alkenyl groups at both molecular chain terminals, which contains alkenyl groups at both molecular chain terminals. The linear organopolysiloxane of component (A-2) may or may not contain alkenyl groups in the molecular chain side chains (i.e., D units), but preferably does not.

The content of alkenyl groups in the linear organopolysiloxane of component (A-2) (the mole percent of alkenyl groups in the total silicon-bonded organic groups in the linear organopolysiloxane) can be designed as desired, but is usually 1 mole percent or more, preferably 2 mole percent or more, and more preferably 3 mole percent or more, and may be 20 mole percent or less, preferably 15 mole percent or less, and more preferably 10 mole percent or less. The content of alkenyl groups can be determined, for example, by analysis using a Fourier transform infrared spectrophotometer (FT-IR), nuclear magnetic resonance (NMR), the titration method described above, or the like.

When component (A) contains linear organopolysiloxane (A-2), its content is not particularly limited, but is preferably 1 mass% or more, more preferably 2 mass% or more, and even more preferably 3 mass% or more, based on the total mass of the curable silicone composition of the present invention. Also, the content of component (A-2) is preferably 50 mass% or less, more preferably 40 mass% or less, and even more preferably 30 mass% or less, based on the total mass of the curable silicone composition of the present invention.

In one embodiment, component (A) contains a small amount of aryl groups in the silicon-bonded organic groups, or does not contain any aryl groups. Specifically, the amount of aryl groups in the entire silicon-bonded organic groups may be 10 mol% or less, 5 mol% or less, 3 mol% or less, or 1 mol% or less.

The viscosity of (A) the alkenyl group-containing organopolysiloxane is not particularly limited, but may be, for example, 5 mPa·s to 5,000 mPa·s at 25°C, and preferably 10 mPa·s to 500 mPa·s. In this specification, the viscosity of the organopolysiloxane component can be measured using a rotational viscometer conforming to JIS K7117-1.

The mass average molecular weight (Mw) of (A) the alkenyl group-containing organopolysiloxane is not particularly limited, but is, for example, in the range of 1,000 to 100,000, and preferably in the range of 1,500 to 15,000. In this specification, the mass average molecular weight can be measured by GPC.

The total content of component (A) is not particularly limited, but is preferably 3 mass% or more, preferably 5 mass% or more, and more preferably 10 mass% or less, based on the total mass of the curable silicone composition. Also, component (A) may be contained in an amount of 90 mass% or less, preferably 80 mass% or less, and more preferably 70 mass% or less, based on the total mass of the curable silicone composition.

(B) Organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule Component (B) acts as a crosslinking agent for the curable silicone composition by hydrosilylation curing reaction, and is an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule. The curable silicone composition according to the present invention may contain one type of organohydrogenpolysiloxane (B), or may contain two or more types of organohydrogenpolysiloxane (B).

Examples of the molecular structure of component (B) include linear, partially branched linear, branched, resinous, cyclic, and three-dimensional network structures. Component (B) may be one type of organohydrogenpolysiloxane having these molecular structures, or a mixture of two or more types of organohydrogenpolysiloxane having these molecular structures. Preferably, the curable silicone composition of the present invention contains a linear organohydrogenpolysiloxane as component (B).

Groups bonded to silicon atoms other than silicon-bonded hydrogen atoms contained in component (B) include halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, such as 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; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, 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, chlorine, or bromine. The silicon atoms in component (B) may contain small amounts of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy, as long as the purpose of the present invention is not impaired. The groups bonded to silicon atoms other than silicon-bonded hydrogen atoms in component (B) are preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly methyl groups.

In one embodiment of the present invention, the component (B) may contain a linear organohydrogenpolysiloxane as the component (B-1). The linear organohydrogenpolysiloxane of the component (B-1) is preferably
Average structural formula (II): R ² ₃ SiO(R ² ₂ SiO _2/2 ) _n SiR ² ₃
(In formula (II), R ² is a hydrogen atom or the same or different halogen-substituted or unsubstituted monovalent hydrocarbon group other than an alkenyl group, with the proviso that in one molecule, at least two R ² are hydrogen atoms, and n is 1 to 200.)

In the above formula (II), examples of halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups for ^R2 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 of these groups have been substituted with halogen atoms, such as fluorine, chlorine, and bromine atoms. ^R2 may also contain a small amount of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy groups, within the scope of the present invention. ^R2 is preferably selected from a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, in particular a methyl group.

In the above formula (II), n is preferably 2 to 150, and more preferably 5 to 100.

In a preferred embodiment of the present invention, the linear organohydrogenpolysiloxane of component (B-1) contains silicon-bonded hydrogen atoms at both ends of the molecular chain. The linear organohydrogenpolysiloxane of component (B-1) has silicon-bonded hydrogen atoms in the M units, and the D units may or may not contain silicon-bonded hydrogen atoms, but preferably do not.

In one embodiment, component (B) contains a small amount of aryl groups in the silicon-bonded organic groups, or does not contain any aryl groups. Specifically, the amount of aryl groups in the entire silicon-bonded organic groups may be 10 mol % or less, 5 mol % or less, 3 mol % or less, or 1 mol % or less.

The amount of component (B) is not particularly limited, but is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, based on the total mass of the curable silicone composition. In a preferred embodiment, component (B) is contained in an amount of 30% by mass or less, preferably 20% by mass or less, and more preferably 15% by mass or less, based on the total mass of the curable silicone composition.

In one embodiment of the present invention, component (B) is contained in an amount such that the ratio (H/Ar) of silicon-bonded alkenyl groups to silicon-bonded hydrogen atoms contained in the organopolysiloxane component is 0.5 moles or more, preferably 0.7 moles or more, more preferably 1 mole or more, and especially 1.2 moles or more of silicon-bonded hydrogen atoms per mole of silicon-bonded alkenyl groups in the curable silicone composition; for example, component (B) can be contained in an amount such that the ratio of silicon-bonded hydrogen atoms per mole of silicon-bonded alkenyl groups in the curable silicone composition is 5 moles or less, preferably 3 moles or less, more preferably 2.5 moles or less, and even more preferably 2 moles or less.

(C) Thermally conductive filler The thermally conductive filler of component (C) is a component that imparts the desired thermal conductivity to the curable silicone composition of the present invention. The curable silicone composition of the present invention may contain one type of thermally conductive filler (C), or may contain two or more types of thermally conductive fillers (C).

Examples of component (C) may be selected from the group consisting of pure metals, alloys, metal oxides, metal hydroxides, metal nitrides, metal carbides, metal silicides, carbon, soft magnetic alloys, and ferrites. Component (C) is preferably at least one powder and/or fiber, preferably a metal powder, a metal oxide powder, a metal nitride powder, or a carbon powder.

Examples of pure metals include bismuth, lead, tin, antimony, indium, cadmium, zinc, silver, copper, nickel, aluminum, iron, and silicon metal. Examples of alloys include alloys of two or more metals selected from the group consisting of bismuth, lead, tin, antimony, indium, cadmium, zinc, silver, aluminum, iron, and silicon metal. Examples of metal oxides include aluminum oxide (alumina), zinc oxide, silica, magnesium oxide, beryllium oxide, chromium oxide, and titanium oxide. Examples of metal hydroxides include magnesium hydroxide, aluminum hydroxide, barium hydroxide, and calcium hydroxide. Examples of metal nitrides include boron nitride, aluminum nitride, and silicon nitride. Examples of metal carbides include silicon carbide, boron carbide, and titanium carbide. Examples of metal silicides include magnesium silicide, titanium silicide, zirconium silicide, tantalum silicide, niobium silicide, chromium silicide, tungsten silicide, and molybdenum silicide. Examples of carbon include diamond, graphite, fullerene, carbon nanotube, graphene, activated carbon, and amorphous carbon black. Examples of soft magnetic alloys include Fe-Si alloys, Fe-Al alloys, Fe-Si-Al alloys, Fe-Si-Cr alloys, Fe-Ni alloys, Fe-Ni-Co alloys, Fe-Ni-Mo alloys, Fe-Co alloys, Fe-Si-Al-Cr alloys, Fe-Si-B alloys, and Fe-Si-Co-B alloys. Examples of ferrite include Mn-Zn ferrite, Mn-Mg-Zn ferrite, Mg-Cu-Zn ferrite, Ni-Zn ferrite, Ni-Cu-Zn ferrite, and Cu-Zn ferrite.

Component (C) is preferably selected from metal oxides, and may in particular be selected from aluminum oxide (alumina), zinc oxide, silica, magnesium oxide, beryllium oxide, chromium oxide, and titanium oxide.

The shape of component (C) is not particularly limited, and examples include spherical, needle-like, disk-like, rod-like, and irregular shapes, with spherical being preferred.

The average particle size of the primary particles of component (C) is not particularly limited, but is preferably in the range of 0.01 to 50 μm, more preferably in the range of 0.01 to 20 μm, and even more preferably in the range of 0.1 to 5 μm. In this specification, the average particle size refers to the particle size at 50% cumulative value (D50) in the particle size distribution determined by the laser diffraction/scattering method.

In a preferred embodiment of the present invention, component (C) contains two types of thermally conductive fillers with different average particle sizes. In this embodiment, component (C) preferably contains a combination of component (C-1) with an average particle size of 2 μm or less and component (C-2) with an average particle size of more than 2 μm. The average particle size range of component (C-1) with the smaller average particle size is preferably 0.01 to 1.5 μm, more preferably 0.1 to 1 μm. Additionally, the average particle size range of component (C-2) with the larger average particle size is preferably 2.5 to 20 μm, more preferably 3 to 5 μm.

The content of the thermally conductive filler of component (C) is 5 mass% or more based on the total mass of the curable silicone composition. The thermally conductive filler of component (C) is preferably contained in an amount of 7 mass% or more, and more preferably 10 mass% or more, based on the total mass of the curable silicone composition. In a preferred embodiment, the content of component (C) is 90 mass% or less, and preferably 80 mass% or less, based on the total mass of the curable silicone composition.

In another embodiment, the content of the thermally conductive filler in component (C) may be 20% by mass or more, 30% by mass or more to 40% by mass or more, 50% by mass or more, 60% by mass or more, or 70% by mass or more based on the total mass of the curable silicone composition. Component (C) may be contained in an amount of 90% by mass or less, preferably 80% by mass or less, based on the total mass of the curable silicone composition.

In addition, when the (C) component contains the (C-1) component and the (C-2) component, which have different particle sizes, the content ratio of the components is not particularly limited, but typically the mass ratio of the (C-2) component:(C-1) component is in the range of 1:10 to 10:1, preferably in the range of 1:5 to 5:1, and more preferably in the range of 1:3 to 3:1. In a preferred embodiment, the (C-2) component is contained in a larger amount than the (C-1) component, and for example, the mass ratio of the (C-2) component:(C-1) component is in the range of 1 to 10:1, preferably in the range of 1.25 to 5:1, and more preferably in the range of 1.5 to 3:1.

(D) Cerium-containing organopolysiloxane The curable silicone composition of the present invention comprises a cerium-containing organopolysiloxane as component (D).(D) Cerium-containing organopolysiloxane can be prepared, for example, by reacting cerium chloride or a cerium salt of a carboxylic acid with an alkali metal salt of a silanol group-containing organopolysiloxane.Therefore, in this specification, the term "cerium-containing organopolysiloxane" can mean a material obtained by reacting a silanol group-containing organopolysiloxane with a cerium salt, and in which the silanol group of the organopolysiloxane and the cerium atom are chemically bonded.

Examples of the cerium salts of the above carboxylic acids include cerium 2-ethylhexanoate, cerium naphthenate, cerium oleate, cerium laurate, and cerium stearate. An example of the cerium chloride is cerium trichloride.

Furthermore, examples of the alkali metal salts of the above-mentioned silanol group-containing organopolysiloxanes include potassium salts of diorganopolysiloxanes having both molecular chain ends blocked with silanol groups, sodium salts of diorganopolysiloxanes having both molecular chain ends blocked with silanol groups, potassium salts of diorganopolysiloxanes having one molecular chain end blocked with a silanol group and the other molecular chain end blocked with a triorganosiloxy group, and sodium salts of diorganopolysiloxanes having one molecular chain end blocked with a silanol group and the other molecular chain end blocked with a triorganosiloxy group. Examples of groups bonded to silicon atoms in this organopolysiloxane include alkyl groups having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, undecyl, and dodecyl; aryl groups having 6 to 20 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, phenethyl, 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, chlorine, or bromine.

The above reaction is carried out at room temperature or by heating in an organic solvent such as alcohols such as methanol, ethanol, isopropanol, and butanol; aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane and heptane; mineral split, ligroin, and petroleum ether. It is also preferable to distill off the organic solvent and low boiling point components from the resulting reaction product, and to filter any precipitates, as necessary. Dialkylformamide, hexaalkylphosphoamide, and the like may also be added to promote this reaction. The cerium atom content in the cerium-containing organopolysiloxane thus prepared is preferably within the range of 0.1 to 15% by mass.

The content of component (D) is not particularly limited, but is preferably an amount such that the content of cerium atoms in the cerium-containing organopolysiloxane (D) is within the range of 1 to 100 ppm, and more preferably within the range of 2 to 50 ppm, relative to the total mass of all organopolysiloxane components in the composition.

(E) Curing Catalyst The curing catalyst of component (E) is a curing catalyst for hydrosilylation reaction, and is a catalyst for promoting the curing of the curable silicone composition of the present invention. Examples of such component (E) include platinum-based catalysts such as chloroplatinic acid, alcohol solutions of chloroplatinic acid, complexes of platinum and olefins, complexes of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, and platinum-supported powder; palladium-based catalysts such as tetrakis(triphenylphosphine)palladium, palladium black, and mixtures with triphenylphosphine; and rhodium-based catalysts, with platinum-based catalysts being particularly preferred.

The amount of component (E) is a catalytic amount, and more specifically, when a platinum-based catalyst is used as component (E), the amount of platinum atoms is preferably 0.01 ppm or more, more preferably 0.1 ppm or more, and even more preferably 1 ppm or more, relative to the total mass of the curable silicone composition of the present invention; the amount of platinum atoms is preferably 20 ppm or less, more preferably 15 ppm or less, even more preferably 10 ppm or less, and particularly preferably 5 ppm or less, relative to the total mass of the curable silicone composition of the present invention.

(Other Organopolysiloxane Components)
The curable silicone composition component according to the present invention may contain an epoxy group-containing organopolysiloxane as an organopolysiloxane component other than components (A) and (B). Preferably, the epoxy group-containing organopolysiloxane is an organopolysiloxane containing at least one epoxy group and at least two alkenyl groups per molecule. The epoxy group-containing organopolysiloxane can act as an adhesion promoter.

The molecular structure of the epoxy group-containing organopolysiloxane can be, for example, linear, partially branched linear, branched, resinous, cyclic, or three-dimensional network structure, with resinous epoxy group-containing organopolysiloxane being preferred. The curable silicone composition according to the present invention may contain one type of epoxy group-containing organopolysiloxane or a combination of two or more types of epoxy group-containing organopolysiloxanes.

The epoxy group-containing organopolysiloxane preferably contains, as the alkenyl group, an alkenyl group having 2 to 12 carbon atoms, such as a vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, or dodecenyl group, preferably a vinyl group, and, as the epoxy group-containing organic group, for example, a glycidoxyalkyl group such as a 2-glycidoxyethyl group, a 3-glycidoxypropyl group, or a 4-glycidoxybutyl group; an epoxycycloalkylalkyl group such as a 2-(3,4-epoxycyclohexyl)-ethyl group or a 3-(3,4-epoxycyclohexyl)-propyl group; or an epoxyalkyl group such as a 3,4-epoxybutyl group or a 7,8-epoxyoctyl group, preferably a glycidoxyalkyl group, and particularly preferably a 3-glycidoxypropyl group.

Groups bonded to silicon atoms other than alkenyl groups and epoxy-containing organic groups of epoxy-containing organopolysiloxanes include halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups and epoxy-containing organic groups, such as alkyl groups having 1 to 12 carbon atoms, such as methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tert-butyl groups, pentyl groups, neopentyl groups, hexyl groups, cyclohexyl groups, heptyl groups, octyl groups, nonyl groups, decyl groups, undecyl groups, and dodecyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl groups, tolyl groups, xylyl groups, and naphthyl groups; aralkyl groups having 7 to 20 carbon atoms, such as benzyl groups, phenethyl groups, and phenylpropyl groups; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine atoms, chlorine atoms, and bromine atoms, with 1 to 12 alkyl groups being preferred, particularly methyl groups.

The resinous epoxy group-containing organopolysiloxane preferably has the following average unit formula (III): (R ³ ₃ SiO _1/2 ) _f (R ³ ₂ SiO _2/2 ) _g (R ³ SiO _3/2 ) _h (SiO _4/2 ) _i (XO _1/2 ) _j
{In formula (III), each ^R3 is independently a halogen-substituted or unsubstituted monovalent hydrocarbon group, with the proviso that at least two ^R3s are alkenyl groups and at least one ^R3 is an epoxy group-containing organic group, X is a hydrogen atom or an alkyl group, 0≦f<1, 0<g<1, 0≦h<0.9, 0≦i<0.5, and 0≦j<0.4, f+g+h+i=1.0, h+i>0, and j represents the number of (XO) groups when the total number of silicon atoms is 1 (the ratio of the number of (XO) groups to the total number of silicon atoms)}.

In the above formula (III), examples of the halogen-substituted or unsubstituted monovalent hydrocarbon group of ^R3 include the above-mentioned alkenyl group, epoxy group-containing organic group, and other monovalent hydrocarbon groups. Furthermore, X in the above formula (III) is a hydrogen atom or an alkyl group. The alkyl group of 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.

In the above formula (III), f is preferably in the range of 0≦f≦0.5, more preferably in the range of 0≦f≦0.3, and even more preferably in the range of 0≦f≦0.1. In the above formula (III), g is preferably in the range of 0.1≦g≦0.7, more preferably in the range of 0.2≦g≦0.6, and particularly in the range of 0.3≦g≦0.5. In the above formula (III), h is preferably in the range of 0.2≦h≦0.8, more preferably in the range of 0.3≦h≦0.7, and particularly in the range of 0.4≦h≦0.65. In the above formula (III), i is preferably in the range of 0≦i≦0.4, more preferably in the range of 0≦i≦0.25, and particularly in the range of 0≦i≦0.1. In the above formula (III), j is preferably in the range of 0≦j≦0.3, more preferably in the range of 0≦j≦0.2, and particularly in the range of 0≦j≦0.1.

In a preferred embodiment of the present invention, the resin-like epoxy-containing organopolysiloxane has formula (III) where h is greater than 0, i.e., contains siloxane units (T units) represented by SiO _{3/2. The epoxy-containing resin-like organopolysiloxane may or may not contain siloxane units (Q units) represented by SiO 4/2 ,} but preferably does not. The epoxy-containing resin-like organopolysiloxane may or may not contain siloxane units (M units) represented by SiO _1/2 , but preferably does not contain them.

In a preferred embodiment of the present invention, the epoxy group-containing organopolysiloxane has an epoxy group-containing organic group as a pendant group on a molecular side chain. The epoxy group-containing organopolysiloxane preferably has an epoxy group-containing organic group in a siloxane unit (T unit) represented by SiO3 _/2 .

In a preferred embodiment, the amount of alkenyl groups in all silicon-bonded organic groups in the epoxy group-containing organopolysiloxane is not particularly limited, but is preferably 1 mol% or more, more preferably 3 mol% or more, and even more preferably 5 mol% or more, and may be, for example, 30 mol% or less, preferably 20 mol% or less, and more preferably 15 mol% or less.

The amount of epoxy-containing organic groups in the total silicon-bonded organic groups in the epoxy-containing organopolysiloxane is not particularly limited, but is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, and is, for example, 60 mol% or less, preferably 50 mol% or less. The amount of epoxy-containing organic groups can be determined, for example, by analysis using a Fourier transform infrared spectrophotometer (FT-IR) or nuclear magnetic resonance (NMR), etc.

The mass average molecular weight (Mw) of the epoxy group-containing organopolysiloxane is not particularly limited, but may be in the range of 1,000 to 10,000. In this specification, the mass average molecular weight can be measured by GPC.

The content of the epoxy group-containing organopolysiloxane is not particularly limited, but is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and even more preferably 0.5 mass% or more, based on the total mass of the curable silicone composition of the present invention, and may be 20 mass% or less, more preferably 10 mass% or less, and even more preferably 5 mass% or less, based on the total mass of the curable silicone composition of the present invention.

As another organopolysiloxane component, the curable silicone composition may also contain, as a silicone reactive diluent, a cyclic organopolysiloxane having at least two alkenyl groups per molecule. Such a cyclic organopolysiloxane is preferably
Average structural formula (IV): (R ⁴ ₂ SiO) _n
(In formula (IV), R ⁴ is the same or different, a halogen-substituted or unsubstituted monovalent hydrocarbon group, with the proviso that in one molecule, at least two R ⁴ 's are alkenyl groups, and n is 4 to 15, preferably 4 to 10, and more preferably 4 to 8.)

In the above formula (IV), the halogen-substituted or unsubstituted monovalent hydrocarbon group of R ⁴ is 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; and 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. ^R4 is preferably selected from alkyl groups having 1 to 6 carbon atoms, in particular a methyl group, and alkenyl groups having 2 to 6 carbon atoms, in particular a vinyl group.

The amount of cyclic organopolysiloxane contained is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, based on the total mass of the curable silicone composition of the present invention, and may be 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, based on the total mass of the curable silicone composition of the present invention.

(Other ingredients)
The curable silicone composition of the present invention may contain optional components within the scope of the present invention. Examples of optional components include acetylene compounds, organic phosphorus compounds, vinyl group-containing siloxane compounds, inorganic fillers other than component (C), such as inorganic fillers such as crushed quartz, silica, magnesium carbonate, and diatomaceous earth, inorganic fillers obtained by hydrophobizing the surface of such inorganic fillers with an organic silicon compound, surface treatment agents, hydrosilylation reaction inhibitors, tackifiers, heat resistance agents, cold resistance agents, flame retardants, thixotropy agents, phosphors, and solvents. The amount of such optional components added is usually 0.001 to 20% by mass of the entire composition.

Among the inorganic fillers, examples of silica include fumed silica, dry silica, wet silica, crystalline silica, and precipitated silica. The silica may also be surface-hydrophobized with an organosilicon compound such as an organoalkoxysilane compound, an organochlorosilane compound, an organosilazane compound, or a low-molecular-weight siloxane compound, or a silane coupling agent, a titanate coupling agent, or the like.

The hydrosilylation reaction inhibitor is a component for inhibiting the hydrosilylation reaction of the curable silicone composition. Examples of such curing reaction inhibitors include alkyne alcohols such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 2-phenyl-3-butyn-2-ol, 1-ethynyl-1-cyclohexanol, and 1-ethynyl-2-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, vinyl-tris(1,1-dimethylpropynyloxy)silane, and methyl-tris(3-methyl-1-butyn-3-oxy)silane. Preferably, the hydrosilylation reaction inhibitor is selected from the group consisting of alkyne alcohols, and 1-ethynyl-1-cyclohexanol is particularly preferred. The amount of reaction inhibitor added is usually 0.001 to 5% by mass of the entire composition.

In one embodiment of the present invention, the curable silicone composition contains two or more different types of curing reaction inhibitors. In a preferred embodiment, the curable silicone composition contains a combination of at least one alkyne alcohol and at least one alkynyloxysilane as the curing reaction inhibitors.

The surface treatment agent is a surface treatment agent for the filler, particularly the thermally conductive filler of component (C), and the type is not particularly limited, but examples include organosilazanes, organocyclosiloxanes, organochlorosilanes, organoalkoxysilanes, alkoxysilylalkyl group-containing organopolysiloxanes, low molecular weight linear siloxanes, and organic compounds. 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.

The alkoxysilylalkyl group-containing organopolysiloxane used as the surface treatment agent is, for example, represented by the following formula: (R ^a O) ₃ Si-(CH ₂ ) _p -(R ^b ₂ SiO) _q -R ^c
(wherein R ^a and R ^b are each independently a C _1-4 alkyl group, particularly a methyl group; R ^c is a C _1-10 alkyl group, preferably a C _2-6 alkyl group; p is 3 to 12, preferably 4 to 10; and q is 50 to 150, preferably 75 to 95).

The amount of the surface treatment agent is not particularly limited, but is usually 0.01% by mass or more, more preferably 0.05% by mass or more, based on the total mass of the curable silicone composition of the present invention, and may be 10% by mass or less, more preferably 5% by mass or less, based on the total mass of the curable silicone composition of the present invention.

In a preferred embodiment of the present invention, the curable silicone composition can be cured to form a cured product having excellent thermal conductivity. For example, in a preferred embodiment, the thermal conductivity of the cured product of the curable silicone composition is 0.5 (W/(m·K)) or more, and more preferably 1.0 (W/(m·K)) or more. There is no particular upper limit to the thermal conductivity, but it is usually less than 3.0 (W/(m·K)). The thermal conductivity can be measured, for example, using a hot disk.

The curable silicone composition of the present invention can be prepared by mixing the components. The method for mixing the components can be any conventional method known in the art and is not particularly limited, but for example, the composition can be prepared by mixing using a mixing device. There are no particular limitations on such mixing devices, and examples of such devices include single- or double-screw continuous mixers, twin roll mixers, Ross mixers, Hobart mixers, dental mixers, planetary mixers, kneader mixers, and Henschel mixers.

[glue]
The present invention also relates to an adhesive comprising the curable silicone composition of the present invention. Preferably, the adhesive of the present invention can be used as a thermally conductive adhesive. Preferably, the adhesive of the present invention can be used as a die bonding adhesive for optical semiconductor elements and the like. The shape of the adhesive of the present invention is not particularly limited, but is preferably a sheet shape. The semiconductor bonded by the adhesive of the present invention is not particularly limited, and examples thereof include semiconductors such as SiC and GaN, particularly optical semiconductors such as power semiconductors or light-emitting diodes.

[Optical semiconductor device]
The present invention also relates to an optical semiconductor device comprising the adhesive of the present invention. Examples of optical semiconductor elements contained in the optical semiconductor device include light emitting diodes (LEDs), semiconductor lasers, photodiodes, phototransistors, solid-state imaging devices, and light emitters and light receivers for photocouplers, and light emitting diodes (LEDs) are particularly preferred.

Since light emitting diodes (LEDs) emit light from above, below, 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 it is preferable that they are made of materials with high light transmittance or high reflectance. Therefore, it is preferable that the substrate on which the optical semiconductor element is mounted is also made of materials 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 resin, BT resin, polyimide resin, and silicone resin; and ceramics such as alumina and alumina nitride.

Specific embodiments of the present invention will be described below.
Aspect 1: (A) an alkenyl-containing organopolysiloxane having at least two alkenyl groups per molecule;
(B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule;
(C) 5% by mass or more of a thermally conductive filler based on the total mass of the composition;
A curable silicone composition comprising: (D) a cerium-containing organopolysiloxane; and (E) a curing catalyst.
Aspect 2: The curable silicone composition according to aspect 1, wherein the (A) alkenyl group-containing organopolysiloxane comprises an MQ resin.
Aspect 3: The curable silicone composition according to Aspect 1 or 2, wherein the thermally conductive filler (C) is a metal oxide.
Aspect 4: The curable silicone composition according to any one of claims 1 to 3, wherein the thermally conductive filler (C) comprises two types of thermally conductive fillers having different average particle sizes.
Aspect 5: The curable silicone composition according to any one of aspects 1 to 4, wherein the cerium atoms in the (D) cerium-containing organopolysiloxane are present in an amount of 1 to 100 ppm, based on the total mass of all organopolysiloxane components in the composition.
Aspect 6: An adhesive comprising the curable silicone composition according to any one of aspects 1 to 5.
Aspect 7: An optical semiconductor device comprising the adhesive according to aspect 6.

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

The components were mixed in the composition (parts by mass) shown in the table to prepare a curable silicone composition. In the following, Me represents a methyl group, Vi represents a vinyl group, and Ep represents a 3-glycidoxypropyl group. In addition, the structure of the organopolysiloxane component is shown in a simplified form in the table, and the organic group other than Me in the M, D, or T unit is shown in parentheses. In addition, H/Vi indicates the molar ratio of silicon-bonded hydrogen atoms (H) to vinyl groups (Vi) in the organopolysiloxane component. In this specification, a chemical formula containing a siloxane unit represented by (SiO _x/2 ) (x is an integer of 1 to 4) is shown as a "unit formula", and a "structural formula" indicates a chemical formula not containing such a siloxane unit. In addition, the content of component d in the table indicates the content (ppm) of cerium atoms in component d in the total organopolysiloxane component.

Component a-1: a resin-like alkenyl group-containing organopolysiloxane represented by the average unit formula ( _Me3SiO1 / ₂ ) _40.9 ( _ViMe2SiO1 / ₂ ) _7.1 (SiO4 _/2 ) ₅₂ (OH) _4.9 (solid at 25°C, mass average molecular weight (Mw): 5,100)
Component a-2: linear alkenyl group-containing organopolysiloxane represented by the average structural formula ViMe ₂ SiO(M ₂ SiO) ₄₆ SiMe ₂ Vi Component b: linear organohydrogenpolysiloxane represented by the average structural formula Me ₃ SiO(MeHSiO) ₅₀ SiMe ₃ Component c-1: aluminum oxide (average particle size: 3.4 μm)
Component c-2: Aluminum oxide (average particle size: 0.5 μm)
Component d: cerium-containing dimethylpolysiloxane having a cerium content of 1.4% by mass Component e: platinum and divinyltetramethyldisiloxane complex having a platinum concentration of 3.0% by mass Component f-1: 1-ethynyl-2-cyclohexanol Component f-2: methyl-tris-(3-methyl-1-butyne-3-oxy)silane Component g: cyclic alkenyl group-containing organopolysiloxane represented by the average structural formula (ViMeSiO) ₄ Component h: condensation reaction product of methylvinylsiloxane oligomer blocked at both molecular terminals with silanol groups and 3-glycidoxypropyltrimethoxysilane (mass average molecular weight (Mw): 1280, viscosity at 25°C: 22.5 mm ² /s)
Component i: Fumed silica (surface treated with hexamethyldisilazane and trimethylsilane)
Component j: A surface treatment agent which is an organopolysiloxane containing an alkoxysilylalkyl group

[Die shear strength]
A 25 mm x 75 mm alumina plate was used as the substrate, and five 5 mm x 5 mm x 1 mm alumina chips were used as the bonding chips. 0.0080 g ± 0.0005 g of a curable silicone composition was applied to each chip, and the chip was placed on the composition, and then cured at 150 ° C for 2 hours to bond each chip to the substrate. The die shear strength was measured using a bond tester (model number: SS-30WD, test mode: PH50 push, speed: 0.120 mm / sec). In addition, the test sample was aged at 200 ° C for 1000 hours, and the die shear strength was measured in the same manner. The results of the die shear strength before and after aging are shown below.

[Thermal conductivity]
The curable silicone composition was cured at a temperature of 150°C under a pressure of 20 MPa for 15 minutes and at atmospheric pressure for 105 minutes to obtain a cylindrical cured sample having a height of 1 cm and a diameter of 2.1 cm. The thermal conductivity (W/(m·K)) of this sample was measured using a hot disk (Kyoto Electronics Co., Ltd., model number: TPS 500s). The results are shown in the table below.

[Weight reduction]
The curable silicone composition was cured by holding it at a temperature of 150°C under a pressure of 20 MPa for 15 minutes and at atmospheric pressure for 105 minutes to obtain a plate-shaped cured product sample of 1 cm x 5 cm x 2 mm. This sample was aged at 200°C, and the weight was measured after 500 hours and 1000 hours, and the weight loss (%) was calculated using the following formula.
(initial weight-weight after aging)/initial weight×100

As can be seen from the results in Table 1, the curable silicone composition of the present invention containing the thermally conductive filler was able to maintain excellent strength and exhibited excellent thermal stability even after aging at high temperatures. Furthermore, as can be seen from the results in Table 2, the curable silicone composition of the present invention containing a high content of thermally conductive filler was able to exhibit high thermal conductivity. Furthermore, as can be seen from the results in Table 3, the curable silicone composition of the present invention experienced only a small weight loss of about 1% even after aging at high temperatures for 1000 hours, demonstrating that the composition was able to maintain its chemical structure even after aging.

The above describes preferred embodiments of the present invention, but the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the attached claims.

Claims (7)

(A) an alkenyl-containing organopolysiloxane having at least two alkenyl groups per molecule;
(B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule;
(C) 5% by mass or more of a thermally conductive filler based on the total mass of the composition;
A curable silicone composition comprising: (D) a cerium-containing organopolysiloxane; and (E) a curing catalyst. The curable silicone composition according to claim 1, wherein the (A) alkenyl group-containing organopolysiloxane contains an MQ resin. The curable silicone composition according to claim 1 or 2, wherein the thermally conductive filler (C) is a metal oxide. The curable silicone composition according to claim 1, wherein the thermally conductive filler (C) contains two types of thermally conductive filler having different average particle sizes. The curable silicone composition according to claim 1, wherein the cerium atom content of the cerium-containing organopolysiloxane (D) is 1 to 100 ppm relative to the total mass of all organopolysiloxane components in the composition. An adhesive comprising the curable silicone composition according to any one of claims 1 to 5. An optical semiconductor device comprising the adhesive according to claim 6.