Thermally conductive silicone composition

Abstract

The thermally conductive silicone composition comprises (A) an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule and a viscosity at 25°C of 10 to 10,000 Pa·S, (B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, (C) a specific adhesion promoter, (D) at least one thermally conductive filler, (E) at least one filler treating agent, and (F) a hydrosilylation reaction catalyst, with the proviso that the composition does not contain a condensation catalyst. The composition exhibits good self-adhesive properties to various substrates without losing its flowability even when cured at a relatively low temperature.

Description

[Technical Field]

[0001] The present invention relates to a thermally conductive silicone composition. [Background technology]

[0002] Thermally conductive silicone compositions that can be cured by a hydrosilylation reaction form thermally conductive materials that have excellent heat resistance, chemical resistance, flexibility, etc., and are therefore used in a variety of applications, such as encapsulants or potting materials in electrical / electronic devices where higher temperatures may be required.

[0003] For example, Patent Document 1 discloses a silicone composition as a hydrosilylation-curable silicone composition, which comprises an organopolysiloxane having at least two alkenyl groups per molecule, an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, a thermally conductive filler, an organosiloxane having silicon-bonded alkoxy groups as a filler treatment, and an adhesion promoter. According to Patent Document 1, this composition is easy to handle, even when it contains a large amount of thermally conductive filler to achieve higher thermal conductivity. However, when used as a potting material for pure aluminum substrates, this thermally conductive silicone exhibits very poor adhesive strength to the Al substrate.

[0004] Meanwhile, Patent Document 2 discloses that 1-(alkoxysilyl)ethyl-1,1,3,3-tetramethyldisiloxane is useful as a surface treatment agent for inorganic powders, a modifier for silicone fluids, etc., a starting material for silicone sealants, a silane coupling agent, etc. Patent Document 3 discloses a silicone composition containing an organopolysiloxane having at least two alkenyl groups per molecule, a trialkoxysilyl group-containing siloxane having at least one silicon-bonded hydrogen atom and at least one trialkoxysilyl group per molecule, a linear or cyclic organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, a linear organopolysiloxane having at least three silicon-bonded hydrogen atoms per molecule, a hydrosilylation reaction catalyst, a condensation reaction catalyst, and an adhesion promoter. Patent Document 3 also discloses that the silicone composition may further contain a thermally conductive filler to impart thermal conductivity to the cured product, and that the use of a condensation reaction catalyst in combination with a hydrosilylation reaction catalyst improves the curability of the composition at room temperature to 50°C and its adhesive properties to various substrates. However, when used as a potting material for pure aluminum substrates, this thermally conductive silicone also exhibits very insufficient adhesive strength to the Al substrate. [Prior art documents] [Patent documents]

[0005] Patent Document 1: U.S. Patent Application Publication No. 2004 / 0254275(A1) Patent Document 2: U.S. Patent Application Publication No. 2007 / 0037997(A1) Patent Document 3: U.S. Patent Application Publication No. 2020 / 0347229(A1) Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a thermally conductive silicone composition that exhibits good self-adhesive properties with respect to a variety of substrates without losing its fluidity, even when cured at relatively low temperatures. [Means for solving the problem]

[0007] The thermally conductive silicone composition of the present invention comprises: (A) an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule and having a viscosity at 25°C of 10 to 10,000 mPa·s as measured using a Brookfield viscometer in accordance with ASTM D 1084; (B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule in an amount sufficient to provide 0.5 to 5 moles of silicon-bonded hydrogen atoms per mole of alkenyl groups in component (A); (C) an adhesion promoter represented by the following general formula in an amount of 0.05 to 2% by weight of the composition: HR 1 2Si(OSiR 1 2) m -X-SiR 1 a (OR 2 ) (3-a) (In the formula, each R 1 are independently alkyl groups having 1 to 6 carbon atoms, and each R 2 are independently an alkyl group having 1 to 3 carbon atoms, X is an alkylene group having 2 to 6 carbon atoms, "a" is 0 or 1, and "m" is an integer from 1 to 10; (D) at least one thermally conductive filler in an amount of 70 to 95% by weight of the composition; (E) at least one filler treating agent in an amount of 0.1 to 2% by weight of the composition; and (F) a catalytic amount of a hydrosilylation reaction catalyst, However, the composition does not contain a condensation catalyst.

[0008] In various embodiments, component (C) is an adhesion promoter represented by the following formula: H(CH3)2SiOSi(CH3)2-CH2CH2-Si(OCH3)3.

[0009] In various embodiments, component (D) is a thermally conductive filler having an average particle size of 0.1 μm to 50 μm.

[0010] In various embodiments, component (E) is (E1) an organosiloxane represented by the following general formula (1): R 3 3SiO(SiR 3 2O) n SiR 3 b (OR 4 ) (4-b) (In the formula, each R 3 are independently an alkyl group having 1 to 3 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, and each R 4 are independently an alkyl group having 1 to 3 carbon atoms, "b" is 0 or 1, and "n" is an integer from 5 to 150; (E2) Alkoxysilanes represented by the following general formula (2): R 5 c R 6 d Si(OR 7 ) (4-c-d) (In the formula, each R 5 are independently alkyl groups having 1 to 3 carbon atoms, and each R 6 are independently alkyl groups having 6 to 12 carbon atoms, and each R 7 are independently alkyl groups having 1 to 3 carbon atoms, and if "c+d" is 1 or 2, then "c" is 0 or 1 and "d" is 0 or 1), and a mixture of components (E1) and (E2).

[0011] In various embodiments, the thermally conductive silicone composition further comprises (G) an inhibitor in an amount of 0.001 to 5 parts by weight per 100 parts by weight of component (A).

[0012] In various embodiments, the thermally conductive silicone composition is a two-part composition in which components (A), (B), and (F) are not present in the same part, and components (A), (C), and (F) are not present in the same part.

[0013] In various embodiments, when the thermally conductive silicone composition further comprises component (G), the composition is a two-part composition in which components (A), (B), and (F) are not present in the same part; components (A), (C), and (F) are not present in the same part; and component (G) is present in a different part from component (F). [Effects of the Invention]

[0014] The thermally conductive silicone composition of the present invention exhibits good self-adhesive properties to a variety of substrates without losing its fluidity, even when cured at relatively low temperatures.

[0015] definition The terms "comprising" or "comprise" are used in the broadest sense herein to mean and encompass "including," "include," "consist(ing) essentially of," and "consist(ing) of." The use of "for example," "eg," "such as," and "including" to list examples does not limit the examples listed. Thus, "for example" or "such as" means "for example, but not limited to" or "such as, but not limited to," and encompasses other similar or equivalent examples. As used herein, the term "about" serves to reasonably encompass or account for slight variations in a numerical value as determined by instrumental analysis or as a result of sample handling. Such minor variations may be as little as ±0-25%, ±0-10%, ±0-5%, or ±0-2.5% of the numerical value. Furthermore, when referring to a range of values, the term "about" applies to both numerical values. Furthermore, the term "about" may apply to multiple numerical values, even if not expressly stated.

[0016] It should be understood that the appended claims are not limited to the specific compounds, compositions, or methods described therein for purposes of describing the Detailed Description of the Invention, and that variations may occur among specific embodiments within the scope of the appended claims. With respect to any Markush group relied upon herein to describe particular features or aspects of various embodiments, it should be understood that different, extraordinary, and / or unexpected results may be obtained from each element of the respective Markush group independently of all other Markush elements. Each element of a Markush group may be relied upon individually and / or in combination to provide sufficient support for specific embodiments within the scope of the appended claims.

[0017] Any ranges and subranges relied upon in describing various embodiments of the present invention should also be understood to be within the scope of the appended claims, both individually and inclusively, and to be understood to describe and contemplate all ranges, including integer and / or fractional values ​​therein, even if such values ​​are not expressly written herein. Those skilled in the art will readily recognize that the recited ranges and subranges fully describe and enable various embodiments of the present invention, and that such ranges and subranges may be further delineated into related halves, thirds, fourths, fifths, etc. As merely an example, a range "from 0.1 to 0.9" may be further delineated into a lower third, i.e., 0.1 to 0.3, a middle third, i.e., 0.4 to 0.6, and an upper third, i.e., 0.7 to 0.9, which are individually and inclusively within the scope of the appended claims, within which specific embodiments may be relied upon and provide sufficient support, individually and / or inclusively. Additionally, with respect to terms defining or modifying a range, such as "at least," "greater than," "less than," "less than or equal to," etc., such terms should be understood to include subranges and / or upper or lower limits. As another example, the range "at least 10" inherently includes subranges of at least 10 to 35, at least 10 to 25, 25 to 35, etc., each of which may be relied upon individually and / or collectively to provide sufficient support for specific embodiments within the appended claims. Finally, individual numbers within disclosed ranges may be relied upon to provide sufficient support for specific embodiments within the appended claims. For example, the range "from 1 to 9" includes various individual integers, such as 3, as well as individual numbers including decimal points (or fractions), such as 4.1, which may be relied upon to provide sufficient support for specific embodiments within the appended claims. DETAILED DESCRIPTION OF THE INVENTION

[0018] Component (A), the main component of the composition, is an organopolysiloxane containing at least two silicon-bonded alkenyl groups per molecule. Examples of the alkenyl groups include alkenyl groups having 2 to 12 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl, with vinyl being preferred. Examples of groups bonded to silicon atoms other than alkenyl groups in component (A) 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; aryl groups having 6 to 12 carbon atoms, such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups having 7 to 12 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. Furthermore, the silicon atoms in component (A) may contain small amounts of hydroxyl or alkoxy groups, such as methoxy or ethoxy groups, as long as the objectives of the present invention are not impaired.

[0019] Examples of the molecular structure of component (A) include a linear structure, a linear structure with some branching, a branched structure, a cyclic structure, and a three-dimensional network structure. Component (A) may be one of organopolysiloxanes having these molecular structures, or a mixture of two or more organopolysiloxanes having these molecular structures.

[0020] Examples of component (A) include dimethylpolysiloxanes capped at both ends with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both ends with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both ends with dimethylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane-methylvinylsiloxane copolymers capped at both ends with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers capped at both ends with silanol groups, and compounds of the formula (CH3)3SiO 1 / 2 Siloxane units represented by the formula (CH3)2(CH2=CH)SiO 1 / 2 Siloxane units represented by the formula CH3SiO 3 / 2 and siloxane units represented by the formula (CH)SiO 2 / 2 and combinations of two or more thereof.

[0021] Additionally, the viscosity of component (A) at 25°C is in the range of 10 to 10,000 mPa·s, preferably 10 to 5,000 mPa·s, alternatively 10 to 3,000 mPa·s, or alternatively 50 to 2,000 mPa·s. This is because when the viscosity of component (A) is at or above the lower limit of the aforementioned range, the mechanical properties of the thermally conductive material obtained by curing the silicone composition are improved, while when the viscosity of component (A) is at or below the upper limit of the aforementioned range, the handleability of the composition is improved. Note that, in this specification, the viscosity at 25°C is a value measured using a Brookfield viscometer in accordance with ASTM D 1084.

[0022] Component (B) is a crosslinker for component (A) in the composition and is an organopolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule. Examples of silicon-bonded groups other than hydrogen groups in component (B) 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; 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 in these groups have been substituted with halogen atoms, such as fluorine, chlorine, or bromine. Furthermore, the silicon atoms in component (B) may have a small amount of hydroxyl groups or alkoxy groups, such as methoxy groups or ethoxy groups, within the scope of the present invention.

[0023] Examples of the molecular structure of component (B) include a linear, a linear with some branching, a branched, cyclic, and a three-dimensional network structure, and preferably the molecular structure is a linear, a linear with some branching, a branched, or a three-dimensional network structure.

[0024] Examples of such component (B) include methylhydrogenpolysiloxanes capped at both ends with trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers capped at both ends with trimethylsiloxy groups, dimethylpolysiloxanes capped at both ends with dimethylhydrogensiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymers capped at both ends with dimethylhydrogensiloxy groups, methylhydrogensiloxane-diphenylsiloxane copolymers capped at both ends with trimethylsiloxy groups, methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymers capped at both ends with trimethylsiloxy groups, and (CH3)2HSiO 1 / 2 Units and SiO 4 / 2Copolymer consisting of units, (CH3)2HSiO 1 / 2 Units, SiO 4 / 2 Units, and (C6H5)SiO 3 / 2 Copolymers of units, as well as mixtures of two or more of these.

[0025] The content of component (B) is an amount that provides 0.5 to 5 moles, preferably 0.5 to 3 moles, or alternatively 0.5 to 2 moles of silicon-bonded hydrogen atoms per mole of alkenyl groups in component (A). This is because when the content of component (B) is at or above the lower limit of the above range, the resulting composition cures sufficiently. On the other hand, when the content of component (B) is at or below the upper limit of the above range, the heat resistance of the resulting thermally conductive material is improved.

[0026] Component (C) is an adhesion promoter for the present composition and is represented by the following general formula: HR 1 2Si(OSiR 1 2) m -X-SiR 1 a (OR 2 ) (3-a) .

[0027] In the above formula, each R 1 are independently alkyl groups having 1 to 6 carbon atoms. 1 Examples of the alkyl group include 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, and a hexyl group, and among these, a methyl group is preferred.

[0028] In the above formula, each R 2 are independently alkyl groups having 1 to 3 carbon atoms. 2 Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group, with a methyl group being preferred.

[0029] In the above formula, X is an alkylene group having 2 to 6 carbon atoms. Examples of the alkylene group for X include an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group, with an ethylene group being preferred.

[0030] In the above formula, "a" is 0 or 1, preferably 0.

[0031] In the above formula, "m" is an integer from 1 to 10, preferably an integer from 1 to 5, alternatively an integer from 1 to 3, or alternatively 1 or 2.

[0032] Component (C) has a silicon-bonded hydrogen atom and at least one silicon-bonded alkoxy group, and therefore can react with component (A) and simultaneously interact with various substrates. Examples of component (C) include adhesion promoters represented by the following formula: H(CH3)2SiOSi(CH3)2-CH2CH2-Si(OCH3)3 H(CH3)2SiOSi(CH3)2-CH2CH2CH2-Si(OCH3)3 H(CH3)2SiOSi(CH3)2-CH2CH2-SiCH3(OCH3)2 H(CH3)2Si[OSi(CH3)2]5-CH2CH2-Si(OCH3)3

[0033] Among these, adhesion promoters represented by the following formula are preferred: H(CH3)2SiOSi(CH3)2-CH2CH2-Si(OCH3)3.

[0034] The content of component (C) is in the range of 0.05 to 2% by weight of the composition, preferably in the range of 0.05 to 1% by weight, or alternatively in the range of 0.1 to 1% by weight, because when the content of component (C) is equal to or greater than the lower limit of the range, the self-adhesive properties of the composition are good, whereas when the content of component (C) is equal to or less than the upper limit of the range, the storage stability of the composition is good.

[0035] Component (D) is at least one thermally conductive filler. For example, component (D) can be any one or any combination of more than one thermally conductive filler selected from the group consisting of metals, alloys, nonmetals, metal oxides, metal hydrates, or ceramics. Exemplary metals include, but are not limited to, aluminum, copper, silver, zinc, nickel, tin, indium, and lead. Exemplary nonmetals include, but are not limited to, carbon, graphite, diamond, carbon nanotubes, carbon fiber, graphene, silicon carbide, and silicon nitride. Exemplary metal oxides, metal hydroxides, and ceramics include, but are not limited to, alumina, aluminum hydroxide, aluminum nitride, boron nitride, zinc oxide, beryllium oxide, magnesium oxide, and tin oxide. Desirably, component (D) is any one or any combination of more than one selected from the group consisting of alumina, aluminum, zinc oxide, boron nitride, aluminum nitride, and aluminum oxide trihydrate.

[0036] Component (D) is preferably a thermally conductive filler having an average particle size of 0.1 μm to 50 μm. Even more preferably, component (D) is any one or combination of fillers selected from aluminum oxide particles having an average particle size of less than 5 μm, aluminum oxide particles having an average particle size of 5 μm or more, aluminum hydroxide particles having an average particle size of less than 5 μm, and aluminum hydroxide particles having an average particle size of 5 μm or more. The average particle size of the filler particles is determined as the median particle size (D50) using a laser diffraction particle size analyzer (CILAS 920 particle size distribution analyzer or Beckman Coulter LS 13 320 SW) according to the operating software.

[0037] The content of component (D) is in the range of 70 to 95% by weight of the composition, alternatively in the range of 75 to 95% by weight, or alternatively in the range of 80 to 95% by weight, because when the content of component (D) is equal to or less than the upper limit of the range, the thermal conductivity of the cured product is good.

[0038] Component (E) is at least one filler treating agent to aid in the dispersion of component (D) in component (A). Component (E) can include, but is not limited to: (E1) An organosiloxane represented by the following general formula (1): R 3 3SiO(SiR 3 2O) n SiR 3 b (OR 4 ) (4-b) (E2) Alkoxysilanes represented by the following general formula (2): R 5 c R 6 d Si(OR 7 ) (4-c-d) and a mixture of components (E1) and (E2).

[0039] In formula (1), each R 3 are independently an alkyl group having 1 to 3 carbon atoms or an alkenyl group having 2 to 6 carbon atoms. 3 Examples of the alkyl group of R include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferred. 3 Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, and a hexenyl group, and among these, a vinyl group is preferred.

[0040] In formula (1), each R 4 are independently alkyl groups having 1 to 3 carbon atoms. 4 Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group, with a methyl group being preferred.

[0041] In formula (1), "b" is 0 or 1, and is preferably 0.

[0042] In formula (1), "n" is an integer of 5 to 150, preferably an integer of 10 to 120, alternatively, all R 3 is an alkyl group, an integer between 50 and 120, or alternatively at least one R 3 When is an alkenyl group, it is an integer of 10 to 50.

[0043] Examples of component (E1) include organopolysiloxanes represented by the following formula: (CH3)3SiO[Si(CH3)2O] 20 Si(OCH3)3 (CH3)3SiO[Si(CH3)2O] 50 Si(OCH3)3 (CH3)3SiO[Si(CH3)2O] 110 Si(OCH3)3 (CH2=CH)(CH3)2SiO[Si(CH3)2O] 10 Si(OCH3)3 (CH2=CH)(CH3)2SiO[Si(CH3)2O] 20 Si(OCH3)3

[0044] In formula (2), each R 5 are independently alkyl groups having 1 to 3 carbon atoms. 5 Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group, with a methyl group being preferred.

[0045] In formula (2), each R 6 are independently alkyl groups having 6 to 12 carbon atoms. 6 Examples of the alkyl group include a hexyl group, a cyclohexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group, and among these, an octyl group and a decyl group are preferred.

[0046] In formula (2), each R 7 are independently alkyl groups having 1 to 3 carbon atoms. 7Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group, with a methyl group being preferred.

[0047] In formula (2), if "c+d" is 1 or 2, then "c" is 0 or 1 and "d" is 0 or 1.

[0048] Examples of alkoxysilanes of component (E2) include methyltrimethoxysilane, hexyltrimethoxysilane, heptyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, dodecylmethyldimethoxysilane, dodecyltriethoxysilane, tetradecyltrimethoxysilane, octadecyltrimethoxysilane, octadecylmethyldimethoxysilane, octadecyltriethoxysilane, nonadecyltrimethoxysilane, or any combination of at least two thereof.

[0049] The content of component (E) is in the range of 0.1 to 2% by mass of the composition, preferably in the range of 0.1 to 1% by mass, or alternatively in the range of 0.5 to 1% by mass, because when the content of component (E) is equal to or greater than the lower limit of the above range, component (D) is sufficiently surface-treated before being filled into the composition, whereas when the content of component (E) is equal to or less than the upper limit of the above range, the storage stability of the composition is good.

[0050] Component (F) is a hydrosilylation catalyst for accelerating the curing of the present composition. Examples of component (F) include platinum group element catalysts and platinum group element compound catalysts, and specific examples include platinum-based catalysts, rhodium-based catalysts, palladium-based catalysts, and combinations of at least two of these. Platinum-based catalysts are particularly preferred because they can dramatically accelerate the curing of the present composition. Examples of these platinum catalysts include platinum fine powder; platinum black; chloroplatinic acid, alcohol-modified chloroplatinic acid; chloroplatinic acid / diolefin complex; platinum / olefin complex; platinum / carbonyl complex such as platinum bis(acetoacetate) and platinum bis(acetylacetonate); chloroplatinic acid / alkenylsiloxane complex such as chloroplatinic acid / divinyltetramethyldisiloxane complex and chloroplatinic acid / tetravinyltetramethylcyclotetrasiloxane complex; platinum / alkenylsiloxane complex such as platinum / divinyltetramethyldisiloxane complex and platinum / tetravinyltetramethylcyclotetrasiloxane complex; chloroplatinic acid and acetylene alcohol complex; and mixtures of two or more of these.In particular, platinum-alkenylsiloxane complex is preferred because it can accelerate the curing of the present composition.

[0051] Examples of alkenylsiloxanes used in platinum-alkenylsiloxane complexes include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, alkenylsiloxane oligomers in which some of the methyl groups of alkenylsiloxanes have been substituted with ethyl groups, phenyl groups, etc., and alkenylsiloxane oligomers in which the vinyl groups of alkenylsiloxanes have been substituted with allyl groups, hexenyl groups, etc. In particular, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is preferred because the resulting platinum-alkenylsiloxane complexes have good stability.

[0052] To improve the stability of the platinum-alkenylsiloxane complexes, it is preferable to dissolve these platinum-alkenylsiloxane complexes in an organosiloxane oligomer such as an alkenylsiloxane oligomer, such as 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3-diallyl-1,1,3,3-tetramethyldisiloxane, 1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane, 1,3-divinyl-1,1,3,3-tetraphenyldisiloxane, or 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, or a dimethylsiloxane oligomer, and it is particularly preferable to dissolve the complexes in an alkenylsiloxane oligomer.

[0053] The content of component (F) is a catalytic amount that accelerates the curing of the composition, preferably from about 0.01 to about 1,000 ppm of platinum group metal in this component, expressed by mass relative to the composition. Specifically, the content is preferably such that the platinum group metal content in component (F) is in the range of about 0.01 to about 500 ppm, alternatively about 0.1 to about 100 ppm, expressed by mass relative to the composition. This is because, when the content of component (F) is at or above the lower limit of the above range, the composition exhibits good curability, whereas, when the content of component (F) is at or below the upper limit of the above range, discoloration of the thermally conductive material is suppressed, the cost of the composition is reduced, and the curing rate of the composition can be controlled.

[0054] The composition may contain (G) an inhibitor to extend the working life at ambient temperature and improve storage stability. Examples of component (G) include acetylenic alcohols such as 1-ethynylcyclohexane-1-ol, 2-methyl-3-butyn-2-ol, 2-phenyl-3-butyn-2-ol, 2-ethynylisopropan-2-ol, 2-ethynylbutan-2-ol, and 3,5-dimethyl-1-hexyn-3-ol; silylated acetylenic alcohols such as trimethyl(3,5-dimethyl-1-hexyn-3-oxy)silane, dimethylbis(3-methyl-1-butyn-oxy)silane, methylvinylbis(3-methyl-1-butyn-3-oxy)silane, and ((1,1-dimethyl-2-propynyl)oxy)trimethylsilane; diallyl maleate, dimethyl maleate, diethyl fumarate, and the like. unsaturated carboxylic acid esters such as bis(2-methoxy-1-methylethyl)maleate, mono-octyl maleate, mono-isooctyl maleate, mono-allyl maleate, mono-methyl maleate, mono-ethyl fumarate, mono-allyl fumarate, and 2-methoxy-1-methylethyl maleate; ene-yne ​​compounds such as 2-isobutyl-1-buten-3-yne, 3,5-dimethyl-3-hexen-1-yne, 3-methyl-3-penten-1-yne, 3-methyl-3-hexen-1-yne, 1-ethynylcyclohexene, 3-ethyl-3-buten-1-yne, and 3-phenyl-3-buten-1-yne; and mixtures of two or more thereof.

[0055] The content of component (G) is about 0.001 to 5 parts by mass, optionally about 0.001 to about 2 parts by mass, or optionally about 0.001 to about 1 part by mass per 100 parts by mass of component (A). This is because when the content of component (G) is at or above the lower limit of the above range, the handleability of the composition is good, whereas when the content of component (G) is at or below the upper limit of the above range, the curability of the composition at low temperatures is good.

[0056] The composition may further comprise a pigment (H) that maintains the desired physical characteristics of the thermally conductive silicone material, i.e., adequate flexibility and conformability. Examples of component (H) include red iron oxide, white titanium dioxide, carbon black, and phthalocyanine compounds. Among these, phthalocyanine compounds are preferred. Examples of phthalocyanine compounds include copper phthalocyanine and chlorinated copper phthalocyanine. Phthalocyanine compounds such as Stan-tone™ 40SP03 are commercially available from PolyOne Corporation, Avon Lake, Ohio, USA.

[0057] The content of component (H) is not limited, but is preferably in an amount such that, in terms of mass units, the pigment is in an amount in the range of 0.01 to 5 parts by mass, alternatively in the range of 0.05 to 5 parts by mass, or alternatively in the range of 0.05 to 1 part by mass, per 100 parts by mass of component (A).

[0058] The composition may contain reinforcing and / or non-reinforcing fillers. Examples of fillers include one or more of finely divided treated or untreated precipitated silica or fumed silica; precipitated or ground calcium carbonate, zinc carbonate; clay (e.g., finely divided kaolin, etc.); quartz powder; zirconium silicate; diatomaceous earth; wollastonite; pyrophyllite; and metal oxides (e.g., fumed or precipitated titanium dioxide, cerium oxide, magnesium oxide powder, zinc oxide, iron oxide, etc.). These may also include glass fiber, talc, aluminite, calcium sulfate (anhydrite), gypsum, calcium sulfate, magnesium carbonate, magnesium hydroxide (brucite), graphite, barite (a form of barium sulfate), copper carbonate (e.g., malachite), nickel carbonate (e.g., zarachite), barium carbonate (e.g., witherite), strontium carbonate (e.g., strontianite), or similar inorganic fillers.

[0059] To prevent solidification of component (D) in the composition, the composition may contain a reactive polymer, such as an organopolysiloxane having at least one silicon-bonded alkoxy group per molecule, except that the organopolysiloxane has neither alkenyl groups nor silicon-bonded hydrogen atoms. Examples of reactive polymers include dimethylpolysiloxane capped at both ends with trimethoxysiloxy groups, dimethylpolysiloxane capped at both ends with dimethoxymethylsiloxy groups, dimethylpolysiloxane capped at both ends with trimethoxysilylethyl groups, and dimethylpolysiloxane capped at both ends with triethoxysiloxy groups.

[0060] The composition can be prepared by mixing all of the components at ambient temperature. However, the composition does not contain a condensation catalyst to avoid impairing its fluidity. In this specification, a condensation catalyst is used as a catalyst for promoting the condensation reaction. Exemplary condensation catalysts include tin compounds such as dimethyltin dineodecanoate and stannous octoate; titanium compounds such as tetra(isopropoxy)titanium, tetra(n-butoxy)titanium, tetra(t-butoxy)titanium, di(isopropoxy)bis(ethylacetoacetate)titanium, di(isopropoxy)bis(methylacetoacetate)titanium, titanium tetraacetylacetonate, and di(isopropoxy)bis(acetylacetonate)titanium; aluminum trisacetylacetonate, aluminum trisacetiriacetate, and aluminum trisacetiriacetate. trisacetriacetate) and tris(sec-butoxy)aluminum; nickel compounds such as nickel bisacetylacetonate; cobalt compounds such as cobalt trisacetylacetonate; zinc compounds such as zinc bisacetylacetonate; and zirconium compounds such as zirconium tetra-n-propoxide, zirconium tetra-n-butoxide, zirconium tetraacetylacetonate, zirconium tributoxymonoacetylacetonate, zirconium monobutoxyacetylacetonate, zirconium dibutoxybis(ethylacetoacetate), zirconium tetraacetylacetonate, and zirconium tributoxymonostearate.

[0061] To avoid undesired reactions, the composition is preferably a two-part composition during storage. That is, in a two-part composition, components (A), (B), and (F) are not present in the same part, and components (A), (C), and (F) are not present in the same part. When the composition further contains component (G), components (A), (B), and (F) are not present in the same part. Components (A), (C), and (F) are not present in the same part, and component (G) is present in a part different from component (F).

[0062] To distinguish the two parts from each other, either part may contain pigments, such as carbon black; and dyes.

[0063] To produce a thermally conductive silicone cured product, the above two parts are combined and mixed together in a mixing device to prepare a single homogeneous composition, which is then applied to a suitable substrate and cured according to the intended application. Any of the mixing techniques and devices described in the prior art can be used for this purpose. The specific device used will depend on the viscosity of the components and the final composition. It may be desirable to cool the components during mixing to prevent premature curing.

[0064] The curing conditions for the composition are not particularly limited and vary depending on the composition and amount of the composition. The composition can be cured at room temperature or, if necessary, by heating. When heating is used, the curing temperature is typically relatively low, for example, in the range of 50 to 120°C, preferably in the range of 60 to 100°C. The relative proportions of each of the two parts that must be mixed together can be adjusted by varying the amount of component (A) in each part, with a 1:1 mass ratio typically providing excellent processability.

[0065] The composition comprises: mixing the two parts together to form a single homogeneous composition; applying the composition to an electrical / electronic device; and curing the composition on the electrical / electronic device.

[0066] For encapsulation or potting applications, the composition must be highly fluid so that it can flow completely across the fine features of electronic devices. For improved fluidity, the composition's viscosity should be less than 15,000 mPa·s, and its thixotropy ratio should be less than 2.0. The composition's fluidity, measured by the inclined plane method described below, should exceed 10 mm. To efficiently remove heat generated by electronic devices, the potting material's thermal conductivity should exceed 0.7 W / mK. The potting material should also have good adhesion to the device's metal housing. The lap shear strength after low- and high-temperature cure should exceed 45 psi, and the failure mode should be non-adhesive (cohesive) failure. [Example]

[0067] The thermally conductive silicone composition of the present invention will be described in detail below using examples and comparative examples. However, the present invention is not limited to the following examples.

[0068] <Lap shear strength (1)> Lap shear strength test (1) was performed according to ASTM D1002. Al Q-panels were used as the substrate. Two Al panels were firmly bonded together using a thermally conductive silicone composition. After the thermally conductive silicone composition was fully cured at 70°C for 0.5 hours, a load was applied to the fixture, and the bonded joint was pulled at a constant rate of 5 mm / min using a pull-off tester until the cured plug separated from the substrate surface. Five replicate specimens were used for each test, and the average value was reported.

[0069] <Lap shear strength (2)> Lap shear strength test (2) was carried out in the same manner as the above lap shear strength test (1), except that the thermally conductive silicone composition was cured at 120°C for 0.5 hours.

[0070] <Liquidity> The flowability test can be performed by using the inclined plane method. A rigid Tefflon™ plate is held at a 30° incline. 1 mL of the composition is placed on top of the inclined plane, and the flow distance after 5 minutes is reported in mm of flow. The longer the flow distance, the better the sample's flowability.

[0071] <Viscosity> The viscosity at 25°C was measured in accordance with ASTM D 1084 "Standard Test Methods for Viscosity of Adhesives" using a Brookfield HA Type Rotational Viscometer at 1 s. -1 and 10s -1 The measurement was carried out by using

[0072] <Thixotropy index> Thixotropy index is 10s -1 1s for viscosity measured at 25°C -1 The viscosity was calculated as the ratio of the viscosity at 25°C measured at 100°C to the viscosity at 25°C measured at 100°C.

[0073] <Thermal conductivity> Thermal conductivity (W / m·K) was measured using a Hot Disk thermal constant analyzer (Hot Disk TPS 2500S).

[0074] [Examples 1 to 7 and Comparative Examples 1 to 10] Two-part thermally conductive silicone compositions consisting of Part A and Part B shown in Tables 1 to 5 were prepared using the components shown below. Equal amounts of the Part A and Part B compositions were mixed uniformly to produce the thermally conductive silicone compositions. In addition, in each table, the "SiH / Vi molar ratio" represents the number of moles of silicon-bonded hydrogen atoms in component (B) per mole of vinyl groups in component (A) in the thermally conductive silicone composition.

[0075] The following components were used as component (A): V-P1: Dimethylpolysiloxane with a viscosity of approximately 78 mPa·s, a vinyl group content of 1.25% by mass, and end-blocked dimethylvinylsiloxy groups at both ends of the molecular chain. V-P2: Dimethylpolysiloxane with a viscosity of approximately 2,000 mPa·s, a vinyl group content of 0.24% by mass, and end-blocked dimethylvinylsiloxy groups at both ends of the molecular chain.

[0076] The following components were used as component (B): XL1: A dimethylsiloxane-methylhydrogensiloxane copolymer having a viscosity of approximately 19 mPa·s, a silicon-bonded hydrogen atom content of 0.114 mol %, and end-capped with trimethylsiloxy groups on both ends of the molecular chain. XL2: A dimethylsiloxane-methylhydrogensiloxane copolymer having a viscosity of approximately 14 mPa·s, a silicon-bonded hydrogen atom content of 0.36 mol %, and end-capped with trimethylsiloxy groups on both ends of the molecular chain. XL3: A dimethylpolysiloxane having a silicon-bonded hydrogen atom content of 0.147 mole % and end-capped with dimethylhydrogensiloxy groups. XL4: A dimethylsiloxane-methylhydrogensiloxane copolymer having a silicon-bonded hydrogen atom content of 0.776 mole % and end-capped with trimethylsiloxy groups on both chain ends.

[0077] The following components were used as component (C): AP1: 1-(2-(trimethoxysilyl)ethyl)-1,1,3,3-tetramethyldisiloxane represented by the following formula: H(CH3)2SiOSi(CH3)2-C2H4-Si(OCH3)3

[0078] The following components were used as comparative adhesion promoters for component (C): AP2: 3-glycidoxypropyltrimethoxysilane AP3: 3-methacryloxypropyltrimethoxysilane

[0079] The following component was used as component (D): Filler-1: Alumina powder with an average particle size of about 9 μm (product name A-CF-6 from ZhengZhou Light Metals Research Institute of CHIALCO). Filler-2: Alumina powder with an average particle size of about 2 μm (product name A-CF-2 from ZhengZhou Light Metals Research Institute of CHIALCO). Filler-3: Alumina powder with an average particle size of about 4 μm (product name Y-4 from Ginet). Filler-4: Aluminum hydroxide powder with an average particle size of approximately 60 μm (product name AH33-4 from CHIALCO) Filler-5: Alumina powder having an average particle size of about 40 μm, product name DAM40K from DENKA Co., Ltd.

[0080] The following components were used as component (E): TA1: A dimethylpolysiloxane represented by the following average formula: (CH3)3SiO[(CH3)2SiO] 110 Si(OCH3)3 TA2: n-decyltrimethoxysilane TA3: Methyltrimethoxysilane

[0081] The following components were used as component (F): PT1: Platinum complex of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane (platinum content = 0.4% by mass)

[0082] The following component was used as component (G): Inhibitor: Methyl-tris(1,1-dimethyl-2-propynyloxy)silane

[0083] The following ingredients were used as pigments: Pigment: A pigment masterbatch of 50% by mass of carbon black and 50% by mass of dimethylpolysiloxane, having a viscosity of about 2,000 mPa·s, a vinyl group content of 0.24% by mass, and the molecular chain ends blocked with dimethylvinylsiloxy groups.

[0084] The following components were used as the reactive polymer. TM-PS1: Dimethylpolysiloxane having a viscosity of about 5,000 mPa·s and the molecular chain ends blocked with dimethylvinylsiloxy groups

[0085] The following components were used as the condensation catalyst. Ti 1: Diisopropoxytitanium bis(ethylacetoacetate)

[0086] <Part A Composition> Each Part A composition shown in Tables 1 to 5 was produced by the following steps. (i) Filling a 10-liter Turello mixer vessel with component (A) and a part of component (E). (ii) Mixing at 20 revolutions per minute (RPM) for 5 minutes under a nitrogen flow of 0.4 m 3 / h. (iii) Adding component (D) and continuing stirring for 15 minutes. (iv) Heating the mixture to 120°C for 1 hour under vacuum (about 0.1 MPa). (v) Then cooling the mixture to 22°C, adding component (F), and mixing at 750 RPM for 15 minutes under a nitrogen purge. (vi) For CE4 and CE9, a condensation catalyst was added. (vii) For IE4, IE5, IE7, and CE10, a reactive polymer was further added.

[0087] <Part B Composition> Each Part B composition shown in Tables 1 to 5 was produced by the following steps. (i) Filling another 10-liter Turello mixer vessel with component (A), component (E), and the pigment, and 0.4 m 3Mix for 5 minutes at 20 RPM under a nitrogen flow of 1 / hr. (ii) Add component (D) and continue stirring for 15 minutes. (iii) Heating the mixture to 120°C under vacuum (approximately 0.1 MPa) for 1 hour. (iv) Cooling the mixture to 22°C and adding components (G), (B), and (C) and mixing at 750 RPM for 15 minutes under a nitrogen purge. (v) For IE4, IE5, and CE10, a reactive polymer was further added.

[0088] [Table 1]

[0089] As shown in Table 1, the present composition IE1 exhibited good flowability, low thixotropy, and good self-adhesion when cured at both low and high temperatures. The comparative compositions CE1, CE2, and CE3 exhibited good flowability and low thixotropy, but exhibited poor self-adhesion when cured at low temperatures. On the other hand, the comparative composition CE4 exhibited good self-adhesion when cured at low temperatures, but exhibited poor flowability and high thixotropy for use as an encapsulant or potting material. The results in Table 1 indicate that component (C) provides good self-adhesion without impairing the flowability of the composition, even when cured at low temperatures. The results in Table 1 also indicate that a condensation catalyst provides good self-adhesion, even when cured at low temperatures, but the addition of a condensation catalyst increases viscosity and reduces flowability.

[0090] [Table 2]

[0091] As shown in Table 2, the present composition of IE2, which was obtained by further loading the composition of IE1 with component (B), exhibited good flowability and low thixotropy, as well as good self-adhesion when cured at both low and high temperatures. On the other hand, the comparative compositions of CE4 and CE5 exhibited good flowability and low thixotropy, but they exhibited poor self-adhesion when cured at low temperatures. The results in Table 2 also show that component (C) provides good self-adhesion without impairing the flowability of the composition, even when cured at low temperatures.

[0092] [Table 3]

[0093] As shown in Table 3, the composition IE3, which was obtained by further adding component (B) to the composition IE1, exhibited good fluidity and low thixotropy, as well as good self-adhesion when cured at both low and high temperatures. The comparative compositions CE7 and CE8 exhibited good fluidity and low thixotropy, but exhibited poor self-adhesion when cured at low temperatures. On the other hand, the comparative composition CE9 exhibited good self-adhesion when cured at low temperatures, but exhibited poor fluidity and high thixotropy for use as a sealant or potting material. The results in Table 3 also show that component (C) provides good self-adhesion without impairing the fluidity of the composition, even when cured at low temperatures. The results in Table 3 also show that the addition of a condensation catalyst provides good self-adhesion, even when cured at low temperatures, but the addition of a condensation catalyst increases viscosity and reduces fluidity.

[0094] [Table 4]

[0095] As shown in Table 4, when other thermally conductive fillers were added to the present composition IE4, it exhibited good flowability, low thixotropy, and good self-adhesion when cured at both low and high temperatures. On the other hand, the comparative composition CE10 exhibited good flowability and low thixotropy, but poor self-adhesion when cured at both low and high temperatures. The results in Table 4 also demonstrate that component (C) provides good self-adhesion without impairing the flowability of the composition, even when filled with other thermally conductive fillers.

[0096] [Table 5]

[0097] As shown in Table 5, even when the thermally conductive filler content in compositions IE5, IE6, and IE7 was varied, they exhibited good flowability, low thixotropy, and good self-adhesion when cured at both low and high temperatures. The results in Table 5 also show that component (C) provides good self-adhesion without compromising the flowability of the composition, even when the thermally conductive filler content was varied. [Industrial Applicability]

[0098] The thermally conductive silicone composition of the present invention exhibits good self-adhesive properties to various substrates without compromising its flowability, making it useful as an encapsulant or potting material in electrical / electronic devices. The present specification includes the following aspects. Section 1. A thermally conductive silicone composition comprising: (A) an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule and having a viscosity at 25°C of 10 to 10,000 mPa·s as measured using a Brookfield viscometer in accordance with ASTM D 1084; (B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule in an amount sufficient to provide 0.5 to 5 moles of silicon-bonded hydrogen atoms per mole of alkenyl groups in component (A); (C) an adhesion promoter represented by the following general formula in an amount of 0.05 to 2% by weight of the composition: HR 1 2Si(OSiR 1 2) m -X-SiR 1 a (OR 2 ) (3-a) (In the formula, each R 1 are independently alkyl groups having 1 to 6 carbon atoms, and each R 2 are independently an alkyl group having 1 to 3 carbon atoms, X is an alkylene group having 2 to 6 carbon atoms, "a" is 0 or 1, and "m" is an integer from 1 to 10; (D) at least one thermally conductive filler in an amount of 70 to 95% by weight of the composition; (E) at least one filler treating agent in an amount of 0.1 to 2% by weight of the composition; and (F) a catalytic amount of a hydrosilylation reaction catalyst, However, the thermally conductive silicone composition does not contain a condensation catalyst. Section 2. Item 1. The thermally conductive silicone composition according to Item 1, wherein component (C) is an adhesion promoter represented by the following formula: H(CH3)2SiOSi(CH3)2-CH2CH2-Si(OCH3)3. Section 3. Item 2. The thermally conductive silicone composition according to Item 1, wherein component (D) is a thermally conductive filler having an average particle size of 0.1 μm to 50 μm. Section 4. Component (E) is (E1) an organosiloxane represented by the following general formula (1): R 3 3SiO(SiR 3 2O) n SiR 3 b(OR 4 ) (4-b) (In the formula, each R 3 are independently an alkyl group having 1 to 3 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, and each R 4 are independently an alkyl group having 1 to 3 carbon atoms, "b" is 0 or 1, and "n" is an integer from 5 to 150; (E2) Alkoxysilanes represented by the following general formula (2): R 5 c R 6 d Si(OR 7 ) (4-c-d) (In the formula, each R 5 are independently alkyl groups having 1 to 3 carbon atoms, and each R 6 are independently alkyl groups having 6 to 12 carbon atoms, and each R 7 are independently an alkyl group having 1 to 3 carbon atoms, and if "c+d" is 1 or 2, then "c" is 0 or 1 and "d" is 0 or 1), and Item 2. The thermally conductive silicone composition according to Item 1, wherein the filler treating agent is selected from the group consisting of components (E1) and (E2). Section 5. Item 1. The thermally conductive silicone composition according to Item 1, further comprising (G) an inhibitor in an amount of 0.001 to 5 parts by mass per 100 parts by mass of component (A). Section 6. Item 2. The thermally conductive silicone composition according to Item 1, which is a two-component composition in which component (A), component (B), and component (F) are not present in the same part, and component (A), component (C), and component (F) are not present in the same part. Section 7. Item 6. The thermally conductive silicone composition according to Item 5, which is a two-component composition in which components (A), (B), and (F) are not present in the same part, components (A), (C), and (F) are not present in the same part, and component (G) is present in a part different from component (F).

Claims

1. A thermally conductive silicone composition comprising: (A) an organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule and having a viscosity at 25°C of 10 to 10,000 mPa·s as measured using a Brookfield viscometer in accordance with ASTM D 1084; (B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule in an amount sufficient to provide from 0.5 to 5 moles of silicon-bonded hydrogen atoms per mole of alkenyl groups in component (A); (C) an adhesion promoter represented by the following general formula in an amount of 0.05 to 2% by weight of the composition: HR １ ２ Si(OSiR １ ２ ) ｍ -X-SiR １ ａ (OR ２ ) （３－ａ） (In the formula, each R １ are independently alkyl groups having 1 to 6 carbon atoms, and each R ２ are independently an alkyl group having 1 to 3 carbon atoms, X is an alkylene group having 2 to 6 carbon atoms, "a" is 0 or 1, and "m" is 1 or 2); (D) at least one thermally conductive filler in an amount of 70 to 95% by weight of the composition; and (E) at least one filler treating agent in an amount of 0.1 to 2% by weight of the composition; and (F) a catalytic amount of a hydrosilylation reaction catalyst, However, the thermally conductive silicone composition does not contain a condensation catalyst.

2. 2. The thermally conductive silicone composition of claim 1, wherein component (C) is an adhesion promoter represented by the following formula: H(CH ３ ) ２ H.E. ３ ) ２ -CH ２ CH ２ -Si(OCH ３ ) ３ 。

3. 2. The thermally conductive silicone composition according to claim 1, wherein component (D) is a thermally conductive filler having an average particle size of 0.1 μm to 50 μm.

4. Component (E) is (E1) an organosiloxane represented by the following general formula (1): R ３ ３ SiO(SiR ３ ２ O) ｎ SiR ３ ｂ (OR ４ ) （４－ｂ） (In the formula, each R ３ are independently an alkyl group having 1 to 3 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, and each R ４ are independently an alkyl group having 1 to 3 carbon atoms, "b" is 0 or 1, and "n" is an integer from 5 to 150), (E2) Alkoxysilanes represented by the following general formula (2): R ５ ｃ R ６ ｄ Si(OR ７ ) （４－ｃ－ｄ） (In the formula, each R ５ are independently alkyl groups having 1 to 3 carbon atoms, and each R ６ are independently alkyl groups having 6 to 12 carbon atoms, and each R ７ are independently alkyl groups having 1 to 3 carbon atoms, and if "c+d" is 1 or 2, then "c" is 0 or 1 and "d" is 0 or 1), and 10. The thermally conductive silicone composition of claim 1, wherein the filler treating agent is selected from the group consisting of components (E1) and (E2).

5. 2. The thermally conductive silicone composition of claim 1, further comprising (G) an inhibitor in an amount of 0.001 to 5 parts by weight per 100 parts by weight of component (A).

6. 2. The thermally conductive silicone composition according to claim 1, which is a two-part composition in which components (A), (B), and (F) are not present in the same part, and in which components (A), (C), and (F) are not present in the same part.

7. 6. The thermally conductive silicone composition according to claim 5, which is a two-part composition, in which components (A), (B), and (F) are not present in the same part, components (A), (C), and (F) are not present in the same part, and component (G) is present in a part different from component (F).

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