Curable silicone composition, adhesive, and optical semiconductor device

Abstract

To provide a curable silicone composition that can form a cured product with excellent thermal stability even when it contains a large amount of a thermally conductive filler.SOLUTION: There is provided a curable silicone composition comprising: (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.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 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. [Background technology]

[0002] Curable silicone compositions are used in a wide range of industrial fields because they cure to form cured products that have excellent heat resistance, cold resistance, electrical insulation, weather resistance, water resistance, and transparency. In particular, the cured products are less likely to discolor than other organic materials, and the deterioration of physical properties such as durability is small, so they are widely used as silicone encapsulants for optical materials, especially for optical semiconductor devices such as light-emitting diodes (LEDs).

[0003] It is well known to add cerium-containing organopolysiloxanes to such curable silicone compositions for the purpose of improving the heat resistance and / or light resistance of the cured product.

[0004] For example, Patent Document 1 describes a compound comprising (A) a linear organopolysiloxane having at least two alkenyl groups in one molecule, (B) a polysiloxane having the following average unit formula: (R 1 SiO 3 / 2 ) a (R 1 2SiO 2 / 2 ) b (R 1 3SiO 1 / 2 ) c (SiO 4 / 2 ) d (XO 1 / 2 ) e (In the formula, R 1 are each 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 1represents the alkenyl group, X represents a hydrogen atom or an alkyl group, a represents a number from 0 to 0.3, b represents 0 or a positive number, c represents a positive number, d represents a positive number, e represents a number from 0 to 0.4, and a+b+c+d=1, c / d represents a number from 0 to 10, and b / d represents 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-bonded hydrogen atoms per molecule {an amount such that the number of silicon-bonded hydrogen atoms in this component is 0.1 to 10 moles per mole of alkenyl groups in components (A) and (B) combined}, (D) a cerium-containing organopolysiloxane {an amount such that the number of cerium atoms in component (D) is 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.

[0005] Furthermore, Patent Document 2 describes a composition comprising (A) an organopolysiloxane having at least two alkenyl groups in one molecule, (B) a cerium-containing organopolysiloxane, (C) a white pigment, and A curable white silicone composition is described that includes (D) a curing catalyst.

[0006] However, conventional curable silicone compositions that contain large amounts of thermally conductive fillers such as aluminum oxide suffer from the problem of reduced thermal stability and reduced strength after aging at high temperatures. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2016-513165 [Patent Document 2] Patent Publication No. 2021-88678 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a curable silicone composition that is capable of forming a cured product that exhibits excellent thermal stability, even when the composition contains a large amount of a thermally conductive filler.

[0009] 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]

[0010]

[0013] In order to solve the above problems, the present inventors carried out intensive research and surprisingly found that a curable silicone composition that includes a cerium-containing organopolysiloxane is capable of forming a cured product that exhibits excellent thermal stability, even when the composition contains a large amount of a thermally conductive filler, and thus arrived at the present invention.

[0011] Thus, the present invention provides (A) an alkenyl group-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) Curing catalyst The present invention relates to a curable silicone composition comprising:

[0012] The (A) alkenyl group-containing organopolysiloxane preferably contains an MQ resin.

[0013] The (C) thermally conductive filler is preferably a metal oxide.

[0014] The (C) thermally conductive filler preferably contains two types of thermally conductive fillers having different average particle sizes.

[0015] The cerium atoms in the (D) cerium-containing organopolysiloxane are preferably present in an amount of 1 to 100 ppm relative to the total mass of all organopolysiloxane components in the composition.

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

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

[0018] The curable silicone composition according to the present invention is capable of forming a cured product that exhibits excellent thermal stability, even when it contains a specified amount of thermally conductive filler. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] [Curable Silicone Composition] The curable silicone composition according to the present invention comprises: (A) an alkenyl group-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) Curing catalyst At least

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

[0021] (A) an alkenyl-containing organopolysiloxane having at least two alkenyl groups per molecule; Component (A) is a curable organopolysiloxane having at least two alkenyl groups in one molecule. The curable silicone composition according to the present invention may contain one type of (A) alkenyl-group-containing organopolysiloxane, or may contain two or more types of (A) alkenyl-group-containing organopolysiloxanes.

[0022] 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.

[0023] The curable silicone composition of the present invention preferably contains, as component (A), a resinous alkenyl group-containing organopolysiloxane. Also, the curable silicone composition of the present invention preferably contains, as component (A), a linear alkenyl group-containing organopolysiloxane. Also, 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.

[0024] 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.

[0025] Examples of 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 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. The silicon atoms in component (A) may contain small amounts of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy groups, as long as the object of the present invention is not impaired. The groups bonded to silicon atoms in component (A) other than alkenyl groups are preferably selected from alkyl groups having 1 to 6 carbon atoms, and particularly methyl groups.

[0026] In one embodiment of the present invention, component (A) may contain, as component (A-1), a resin-like alkenyl group-containing organopolysiloxane. (A-1) The resin-like alkenyl group-containing organopolysiloxane is preferably Average unit formula (Ia):(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 (Ia), R 1 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, provided that at least two R 1is an alkenyl 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. e can be expressed as the number of (XO) groups when the total number of silicon atoms is 1 (representing the ratio of the number of (XO) groups to the total number of silicon atoms).

[0027] R in the above formula (Ia) 1 Examples of halogen-substituted or unsubstituted monovalent hydrocarbon 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 of these groups have been substituted with halogen atoms, such as fluorine, chlorine, or bromine atoms. R 1 R may contain a small amount of hydroxyl groups or alkoxy groups such as methoxy groups and ethoxy groups, as long as the object of the present invention is not impaired. 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.

[0028] In the above formula (Ia), X is a hydrogen atom or an alkyl group. The alkyl group of X is preferably an alkyl group having 1 to 3 carbon atoms, specifically, methyl group, ethyl group, and propyl group are exemplified. X is preferably a hydrogen atom.

[0029] In the above formula (Ia), 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 (Ia), 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 (Ia), 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 (Ia), 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 (Ia), 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.

[0030] In a preferred embodiment of the present invention, the resin-like alkenyl group-containing organopolysiloxane of component (A-1) has no SiO 4 / 2 The resin-like alkenyl-containing organopolysiloxane of component (A-1) contains SiO 2 / 2 The resin-like alkenyl-containing organopolysiloxane of component (A-1) may or may not contain a siloxane unit (D unit) represented by the following formula: 3 / 2 It may or may not contain a siloxane unit (T unit) represented by the following formula: but preferably it does not contain one.

[0031] In a preferred embodiment of the present invention, the resin-like alkenyl-containing organopolysiloxane of component (A-1) contains an alkenyl group at the molecular terminal. The resin-like organopolysiloxane of component (A-1) is preferably SiO 1 / 2 The siloxane unit (M unit) represented by the formula: 2 / 2 Siloxane units (D units) represented by the formula: and SiO 3 / 2 The siloxane unit (T unit) represented by the following formula may or may not contain an alkenyl group, but preferably does not contain an alkenyl group.

[0032] In a preferred embodiment of the present invention, the resinous alkenyl group-containing organopolysiloxane of the component (A-1) contains an MQ resin or consists of only an MQ resin. The MQ resin is an organopolysiloxane composed of only siloxane units (M units) represented by SiO 1 / 2 and siloxane units (Q units) represented by SiO 4 / 2 . The MQ resin of the component (A-1) can preferably be represented by the following average unit formula (I-b). Average unit formula (I-b): (R 1 3SiO 1 / 2 ) s (SiO 4 / 2 ) t (XO 1 / 2 ) u In the formula, R 1 is the same or different halogen-substituted or unsubstituted monovalent hydrocarbon group, provided that at least two R 1 in one molecule 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 (the ratio of the number of (XO) groups to the total number of silicon atoms) when the total number of silicon atoms is 1.

[0033] R 1 in the formula (II-b) is as described in the formula (II-a).

[0034] In the 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 the above 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 particularly in the range of 0.3 ≤ t ≤ 0.7. In the 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 particularly in the range of 0 ≤ u ≤ 0.1.

[0035] The content of alkenyl groups in the total silicon-bonded organic groups of the resinous alkenyl-containing organopolysiloxane of component (A-1) is not particularly limited, but may be, for example, 3 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more of the total silicon-bonded organic groups, and 40 mol% or less, preferably 30 mol%, more preferably 20 mol% or less of the total silicon-bonded organic groups. The content of alkenyl groups can be determined, for example, by analytical methods such as Fourier transform infrared spectrophotometer (FT-IR) or nuclear magnetic resonance (NMR), or by the following titration method.

[0036] 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.

[0037] The MQ resin of component (A-1) may be a solid at room temperature (25°C).

[0038] When the (A) component contains one or more (A-1) resin-like organopolysiloxanes, 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 the (A-1) component 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 range can be arbitrarily combined to set the numerical range.

[0039] 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 (Ic):R 1 3SiO(R 1 2SiO 2 / 2 ) m SiR 2 3 (In formula (Ic), R 1 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, provided that at least two R 1 is an alkenyl group, and m is 1 to 500.

[0040] In the above formula (Ic), R 1 The halogen-substituted or unsubstituted monovalent hydrocarbon group may be the same as that in formula (Ia) above. In the above formula (Ic), m is preferably 2-300, more preferably 5-200, further preferably 10-100, and particularly preferably 15-50.

[0041] Examples of such component (A-2) include dimethylpolysiloxanes capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylpolysiloxanes capped at both molecular chain terminals with diphenylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylsiloxane-diphenylsiloxane copolymers capped at both molecular chain terminals with dimethylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers capped at both molecular chain terminals with diphenylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with dimethylvinylsiloxy groups, and dimethylsiloxane-methylvinylsiloxane copolymers capped at both molecular chain terminals with dimethylvinylsiloxy groups. Examples of such compounds include dimethylsiloxane-methylphenylsiloxane-methylvinylsiloxane copolymers capped with dimethylvinylsiloxane-diphenylsiloxane-methylvinylsiloxane copolymers capped with dimethylvinylsiloxane-terminated at both molecular chain ends with dimethylvinylsiloxane-terminated at both molecular chain ends with trimethylsiloxy groups, methylvinylpolysiloxanes capped with trimethylsiloxy groups at both molecular chain ends with methylvinylsiloxane-methylphenylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain ends, methylvinylsiloxane-diphenylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain ends, and dimethylsiloxane-methylvinylsiloxane copolymers capped with trimethylsiloxy groups at both molecular chain ends.

[0042] 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 contain them.

[0043] The content of alkenyl groups in the linear organopolysiloxane of component (A-2) (mol % of alkenyl groups in the total silicon-bonded organic groups of the linear organopolysiloxane) can be designed as desired, but is usually 1 mol % or more, preferably 2 mol % or more, more preferably 3 mol % or more, and may be 20 mol % or less, preferably 15 mol % or less, more preferably 10 mol % 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, or the like.

[0044] 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.

[0045] In one embodiment, component (A) contains a small amount of aryl groups in the silicon-bonded organic groups, or contains no 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.

[0046] The viscosity of the (A) alkenyl group-containing organopolysiloxane is not particularly limited, but may be, for example, 5 mPa·s to 5,000 mPa·s and preferably 10 mPa·s to 500 mPa·s at 25° C. In this specification, the viscosity of the organopolysiloxane component can be measured with a rotational viscometer in accordance with JIS K7117-1.

[0047] The mass average molecular weight (Mw) of the (A) 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.

[0048] The total amount 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) is preferably 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.

[0049] (B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule; Component (B) acts as a crosslinking agent for the curable silicone composition through a 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).

[0050] 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 organohydrogenpolysiloxanes having these molecular structures. Preferably, the curable silicone composition of the present invention contains a linear organohydrogenpolysiloxane as component (B).

[0051] Examples of 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, and bromine atoms. 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 object of the present invention is not impaired. Groups bonded to silicon atoms in component (B) other than silicon-bonded hydrogen atoms are preferably selected from alkyl groups having 1 to 6 carbon atoms, particularly methyl groups.

[0052] 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 3SiO(R 2 2SiO 2 / 2 ) n SiR 2 3 (In formula (II), R 2 are hydrogen atoms or the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl groups, provided that at least two R 2 is a hydrogen atom, and n is 1 to 200).

[0053] In the above formula (II), R 2Examples of halogen-substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl 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; 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. 2 R may contain a small amount of hydroxyl groups or alkoxy groups such as methoxy groups and ethoxy groups, as long as the object of the present invention is not impaired. 2 is preferably selected from a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, in particular a methyl group.

[0054] In the above formula (II), n is preferably 2-150, and more preferably 5-100.

[0055] In a preferred embodiment of the present invention, the linear organohydrogenpolysiloxane of component (B-1) contains silicon-bonded hydrogen atoms at both molecular chain terminals. 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.

[0056] In one embodiment, component (B) contains a small amount of aryl groups in the silicon-bonded organic groups, or contains no 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.

[0057] The content of component (B) 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. In a preferred embodiment, component (B) is contained in an amount of 30 mass % or less, preferably 20 mass % or less, and more preferably 15 mass % or less, based on the total mass of the curable silicone composition.

[0058] Furthermore, 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; and, for example, the amount of silicon-bonded hydrogen atoms can be contained in an amount such that 5 moles or less, preferably 3 moles or less, more preferably 2.5 moles or less, and even more preferably 2 moles or less of silicon-bonded hydrogen atoms per mole of silicon-bonded alkenyl groups in the curable silicone composition.

[0059] (C) Thermally conductive filler The thermally conductive filler (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).

[0060] 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, and is preferably a metal powder, a metal oxide powder, a metal nitride powder, or a carbon powder.

[0061] Examples of pure metals include bismuth, lead, tin, antimony, indium, cadmium, zinc, silver, copper, nickel, aluminum, iron, and metal silicon. 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 metal silicon. 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 alloy, Fe-Al alloy, Fe-Si-Al alloy, Fe-Si-Cr alloy, Fe-Ni alloy, Fe-Ni-Co alloy, Fe-Ni-Mo alloy, Fe-Co alloy, Fe-Si-Al-Cr alloy, Fe-Si-B alloy, and Fe-Si-Co-B alloy. Examples of ferrites include Mn-Zn ferrite, Mn-Mg-Zn ferrite, Mg-Cu-Zn ferrite, Ni-Zn ferrite, Ni-Cu-Zn ferrite, and Cu-Zn ferrite.

[0062] 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.

[0063] There are no particular limitations on the shape of component (C) and examples include spherical, needle-like, disk-like, rod-like, and irregular shapes, with spherical being preferred.

[0064] 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 0.01 to 20 μm, and even more preferably 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 a laser diffraction / scattering method.

[0065] In a preferred embodiment of the present invention, the component (C) contains two types of thermally conductive fillers with different average particle sizes. In this embodiment, the component (C) preferably contains a combination of a component (C-1) having an average particle size of 2 μm or less and a component (C-2) having an average particle size of more than 2 μm. The average particle size of the component (C-1) having the smaller average particle size is preferably in the range of 0.01 to 1.5 μm, more preferably 0.1 to 1 μm. The average particle size of the component (C-2) having the larger average particle size is preferably in the range of 2.5 to 20 μm, more preferably 3 to 5 μm.

[0066] The content of the thermally conductive filler of component (C) is 5% by mass or more based on the total mass of the curable silicone composition. The thermally conductive filler of component (C) is preferably 7% by mass or more, more preferably 10% by mass or more, based on the total mass of the curable silicone composition. In a preferred embodiment, the content of component (C) is 90% by mass or less, preferably 80% by mass or less, based on the total mass of the curable silicone composition.

[0067] 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, and preferably 80% by mass or less, based on the total mass of the curable silicone composition.

[0068] In the case where 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 the mass ratio of the (C-2) component:(C-1) component is usually within the range of 1:10 to 10:1, preferably within the range of 1:5 to 5:1, and more preferably within the range of 1:3 to 3:1. In a preferred embodiment, the (C-2) component is contained in an amount greater than that of the (C-1) component, and for example, the mass ratio of the (C-2) component:(C-1) component is within the range of 1 to 10:1, preferably within the range of 1.25 to 5:1, and more preferably within the range of 1.5 to 3:1.

[0069] (D) Cerium-containing organopolysiloxane The curable silicone composition according to the present invention contains a cerium-containing organopolysiloxane as component (D). The cerium-containing organopolysiloxane (D) 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" refers to a compound obtained by reacting a silanol group-containing organopolysiloxane with a cerium salt, in which the silanol group of the organopolysiloxane is chemically bonded to a cerium atom.

[0070] Examples of the cerium salts of the above carboxylic acids include cerium 2-ethylhexanoate, cerium naphthenate, cerium oleate, cerium laurate, and cerium stearate. Examples of the cerium chloride include cerium trichloride.

[0071] Examples of the alkali metal salt of the silanol group-containing organopolysiloxane 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 groups, ethyl groups, propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, tert-butyl groups, n-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.

[0072] 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 or low boiling point components from the resulting reaction product, or to filter the precipitate, as necessary. In order to promote this reaction, dialkylformamide, hexaalkylphosphoamide, and the like may be added. The content of cerium atoms in the cerium-containing organopolysiloxane thus prepared is preferably within the range of 0.1 to 15% by mass.

[0073] 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 an amount within the range of 2 to 50 ppm, relative to the total mass of all organopolysiloxane components in the composition.

[0074] (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 solution of chloroplatinic acid, complex of platinum and olefin, complex of platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, and powder carrying platinum; palladium-based catalysts such as tetrakis(triphenylphosphine)palladium, palladium black, and mixture with triphenylphosphine; and rhodium-based catalysts, and particularly, platinum-based catalysts are preferred.

[0075] The amount of component (E) is a catalytic amount; more specifically, when a platinum-based catalyst is used as component (E), the amount of platinum atoms, relative to the total mass of the curable silicone composition of the present invention, is preferably at least 0.01 ppm, more preferably at least 0.1 ppm, and even more preferably at least 1 ppm; and the amount of platinum atoms, relative to the total mass of the curable silicone composition of the present invention, is preferably no more than 20 ppm, more preferably no more than 15 ppm, even more preferably no more than 10 ppm, and particularly preferably no more than 5 ppm.

[0076] (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 the 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.

[0077] The molecular structure of the epoxy group-containing organopolysiloxane may be, for example, a linear structure, a linear structure having some branches, a branched structure, a resin structure, a cyclic structure, or a three-dimensional network structure, and preferably a resin structure of the epoxy group-containing organopolysiloxane. The curable silicone composition according to the present invention may contain one type of epoxy group-containing organopolysiloxane, or may contain a combination of two or more types of epoxy group-containing organopolysiloxanes.

[0078] 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.

[0079] Examples of the groups bonded to the silicon atoms other than the alkenyl group and the epoxy group-containing organic group of the epoxy group-containing organopolysiloxane include halogen-substituted or unsubstituted monovalent hydrocarbon groups other than the alkenyl group and the epoxy group-containing organic group. For example, alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group; aryl groups having 6 to 20 carbon atoms such as phenyl group, tolyl group, xylyl group, naphthyl group; aralkyl groups having 7 to 20 carbon atoms such as benzyl group, phenethyl group, phenylpropyl group; and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine atom, chlorine atom, bromine atom. Preferably, they are alkyl groups having 1 to 12 carbon atoms, particularly methyl group.

[0080] The resinous epoxy group-containing organopolysiloxane preferably has the following average unit formula (III): (R 3 3SiO 1 / 2 ) f (R 3 2SiO 2 / 2 ) g (R 3 SiO 3 / 2 ) h (SiO 4 / 2 ) i (XO 1 / 2 ) j {In formula (III), each R 3 is independently a halogen-substituted or unsubstituted monovalent hydrocarbon group, provided that at least two R 3 are alkenyl groups, and at least one R 3 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, and f + g + h + i = 1.0, h + i > 0. j represents the number of (XO) groups (the ratio of the number of (XO) groups to the total number of silicon atoms) when the total number of silicon atoms is 1}.

[0081] In the above formula (III), R 3 The halogen-substituted or unsubstituted monovalent hydrocarbon group includes the above-mentioned alkenyl group, epoxy group-containing organic group, and other monovalent hydrocarbon groups. X in the 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.

[0082] 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.

[0083] In a preferred embodiment of the present invention, the resin-like epoxy group-containing organopolysiloxane is a resin-like epoxy group-containing organopolysiloxane represented by the above formula (III), in which h is greater than 0, i.e., SiO 3 / 2 The epoxy group-containing resin-like organopolysiloxane contains a siloxane unit (T unit) represented by SiO 4 / 2 The epoxy group-containing resin-like organopolysiloxane may or may not contain a siloxane unit (Q unit) represented by the following formula: 1 / 2 It may or may not contain a siloxane unit (M unit) represented by the following formula: but preferably it does not contain one.

[0084] 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 is preferably SiO 3 / 2 The siloxane unit (T unit) represented by the following formula (I) has an epoxy group-containing organic group.

[0085] In a preferred embodiment, the amount of alkenyl groups in all of the 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.

[0086] 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, 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), nuclear magnetic resonance (NMR), etc.

[0087] The mass average molecular weight (Mw) of the epoxy group-containing organopolysiloxane is not particularly limited, but may be within the range of 1,000 to 10,000. In this specification, the mass average molecular weight can be measured by GPC.

[0088] 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.

[0089] As another organopolysiloxane component, the curable silicone composition may also contain a cyclic organopolysiloxane having at least two alkenyl groups per molecule as a silicone reactive diluent. Such a cyclic organopolysiloxane is preferably Average structural formula (IV):(R 4 2SiO) n (In formula (IV), R 4 are the same or different halogen-substituted or unsubstituted monovalent hydrocarbon groups, provided that at least two R 4 is an alkenyl group, and n is 4 to 15, preferably 4 to 10, and more preferably 4 to 8.

[0090] In the above formula (IV), R 4 The halogen-substituted or unsubstituted monovalent hydrocarbon group of R 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. 4 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.

[0091] The content of cyclic 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.

[0092] (Other ingredients) 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. Examples of the 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.

[0093] Among the inorganic fillers, examples of silica include fumed silica, dry silica, wet silica, crystalline silica, precipitated silica, etc. In addition, the silica may 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.

[0094] Hydrosilylation reaction inhibitor is a component for suppressing the hydrosilylation reaction of curable silicone composition.As such curing reaction inhibitor, for example, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 2-phenyl-3-butyn-2-ol, 1-ethynyl-1-cyclohexanol, 1-ethynyl-2-cyclohexanol and other alkyne alcohols; 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne and other enyne compounds; tetramethyltetravinylcyclotetrasiloxane, tetramethyltetrahexenylcyclotetrasiloxane and other alkenyl group-containing low molecular weight siloxanes; methyl-tris(1,1-dimethylpropynyloxy)silane, vinyl-tris(1,1-dimethylpropynyloxy)silane, methyl-tris(3-methyl-1-butyn-3-oxy)silane and other alkynyloxysilanes. The hydrosilylation reaction inhibitor is preferably selected from the group consisting of alkyne alcohols, and particularly preferably 1-ethynyl-1-cyclohexanol. The amount of the reaction inhibitor added is usually 0.001 to 5% by mass of the entire composition.

[0095] In one embodiment of the present invention, the curable silicone composition comprises two or more different curing reaction inhibitors. In a preferred embodiment, the curable silicone composition comprises at least one alkyne alcohol and at least one alkynyloxysilane in combination as the curing reaction inhibitors.

[0096] The surface treatment agent is a surface treatment agent for fillers, particularly the thermally conductive filler of component (C), and the type thereof is not particularly limited, and examples thereof 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.

[0097] The alkoxysilylalkyl group-containing organopolysiloxane used as the surface treatment agent is, for example, an organopolysiloxane represented by the following formula: (R a O)3Si-(CH2) p -(R b 2SiO) q -R c (In the formula, R a and R b are each independently 1~4 R is an alkyl group, particularly a methyl group; c is C 1~10 Alkyl groups, preferably C 2~6 is an alkyl group, p is 3 to 12, preferably 4 to 10, and q is 50 to 150, preferably 75 to 95).

[0098] The content of the surface treatment agent is not particularly limited, but is usually at least 0.01 mass %, more preferably at least 0.05 mass %, based on the total mass of the curable silicone composition of the present invention, and may be at most 10 mass %, more preferably at most 5 mass %, based on the total mass of the curable silicone composition of the present invention.

[0099] 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, more preferably 1.0 (W / (m·K)) or more. The upper limit of the thermal conductivity is not particularly limited, but is usually less than 3.0 (W / (m·K)). The thermal conductivity can be measured, for example, using a hot disk.

[0100] 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 for example, it can be prepared by mixing using a mixing device. There is no particular limit to such a mixing device, and examples of such a mixing device include a single-screw or double-screw continuous mixer, a double roll, a Ross mixer, a Hobart mixer, a dental mixer, a planetary mixer, a kneader mixer, and a Henschel mixer.

[0101] [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.

[0102] [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 photodetectors for photocouplers, and light emitting diodes (LEDs) are particularly preferred.

[0103] 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 are preferably 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 resins, BT resins, polyimide resins, and silicone resins; and ceramics such as alumina and alumina nitride.

[0104] 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; (D) a cerium-containing organopolysiloxane, and (E) Curing catalyst 1. A curable silicone composition comprising: Aspect 2: The curable silicone composition of 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 (C) thermally conductive filler 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, relative to the total mass of all organopolysiloxane components in the composition. Embodiment 6: An adhesive comprising the curable silicone composition according to any one of embodiments 1 to 5. Embodiment 7: An optical semiconductor device comprising the adhesive according to embodiment 6. EXAMPLES

[0105] The curable silicone composition of the present invention will be described in more detail below with reference to the following examples and comparative examples.

[0106] 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 structures of the organopolysiloxane components are shown in a simplified form in the table, with the organic groups other than Me in the M, D, or T units shown in parentheses. Furthermore, H / Vi represents the molar ratio of silicon-bonded hydrogen atoms (H) to vinyl groups (Vi) in the organopolysiloxane component. In the present specification, (SiO x / 2 ) (x is an integer from 1 to 4) is shown as a "unit formula", and a "structural formula" is a chemical formula that does not include such a siloxane unit. Also, the content of component d in the table indicates the content (ppm) of cerium atoms in component d in the total organopolysiloxane components.

[0107] Component a-1: Average unit formula (Me3SiO 1 / 2 ) 40.9 (ViMe2SiO 1 / 2 ) 7.1 (SiO 4 / 2 ) 52 (OH) 4.9 Resin-like alkenyl-containing organopolysiloxane represented by the formula (solid at 25°C, mass average molecular weight (Mw): 5,100) Component a-2: Average structural formula ViMe2SiO(M2SiO) 46 Linear alkenyl-containing organopolysiloxane represented by SiMe2Vi Component b: Average structural formula Me3SiO(MeHSiO) 50 Linear organohydrogenpolysiloxane represented by SiMe3 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: A complex of platinum and divinyltetramethyldisiloxane having a platinum concentration of 3.0 mass% Component f-1: 1-ethynyl-2-cyclohexanol Component f-2: Methyl-tris-(3-methyl-1-butyn-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 capped with silanol groups at both ends of the molecule 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

[0108] [Die shear strength] A 25mm x 75mm alumina plate was used as the substrate, and five 5mm x 5mm x 1mm alumina chips were used as the bonding chips. 0.0080g ± 0.0005g 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: 0.120mm / 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.

[0109] [Table 1]

[0110] [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, yielding a cylindrical cured sample with 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.

[0111] [Table 2]

[0112] [Weight loss] The curable silicone composition was cured by holding it at 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 x 100

[0113] [Table 3]

[0114] As can be seen from the results in Table 1, the curable silicone composition containing the thermally conductive filler of the present invention was able to maintain excellent strength and exhibited excellent thermal stability even after aging at high temperatures. Also, 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 showed a small weight loss of about 1% even after aging at high temperatures for 1000 hours, demonstrating that the chemical structure can be maintained even after aging.

Claims

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; (D) a cerium-containing organopolysiloxane, and (E) Curing catalyst 1. A curable silicone composition comprising:

2. 2. The curable silicone composition according to claim 1, wherein the alkenyl-containing organopolysiloxane (A) comprises an MQ resin.

3. 3. The curable silicone composition according to claim 1, wherein the thermally conductive filler (C) is a metal oxide.

4. 2. The curable silicone composition according to claim 1, wherein the thermally conductive filler (C) comprises two types of thermally conductive fillers having different average particle sizes.

5. 2. 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.

6. An adhesive comprising the curable silicone composition according to any one of claims 1 to 5.

7. An optical semiconductor device comprising the adhesive according to claim 6 .

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