Thermally conductive silicone composition and thermally conductive member

Abstract

This thermally conductive silicone composition is constituted of at least: (A) an organopolysiloxane having an average of at least 2 alkenyl groups per molecule; (B) an organohydrogenpolysiloxane having an average of at least two silicon atom-bonded hydrogen atoms per molecule; (C) a hydrosilylation reaction catalyst; (D) a thermally conductive filler comprising (D-1) a thermally conductive powder other than an aluminum nitride powder, which has an average particle diameter of not less than 0.1 µm and less than 5 µm, (D-2) an aluminum nitride powder having an average particle diameter of not less than 20 µm and less than 80 µm, and (D-3) a spherical aluminum oxide powder and / or spherical magnesium oxide powder having an average particle diameter of not less than 80 µm; and (E) a specific surface treatment agent or wetting agent. This composition exhibits good handling properties and filling properties and, when cured, forms a thermally conductive member which exhibits high thermal conductivity and in which the occurrence of internal cracks at high temperatures is suppressed.

Description

[Technical Field]

[0001] The present invention relates to a thermally conductive silicone composition and a thermally conductive member obtained by curing the composition. [Background technology]

[0002] In order to efficiently transfer heat generated by electronic devices to heat dissipation components, curable thermally conductive silicone compositions containing thermally conductive fillers such as silica powder, aluminum oxide powder, boron nitride powder, aluminum nitride powder, magnesium oxide powder, etc. In recent years, there has been a demand for compositions with high thermal conductivity, and it has been known to highly fill these compositions with at least two types of thermally conductive fillers with different average particle sizes.

[0003] For example, Patent Document 1 discloses a thermally conductive silicone composition having a thermal conductivity of 5 W / m·K or higher, which contains at least 1,000 parts by mass of spherical aluminum oxide powder having an average particle size of 5 to 40 μm and spherical aluminum oxide powder having an average particle size of 0.1 to 3 μm, per 100 parts by mass of an organopolysiloxane as the main component. Patent Document 2 discloses a thermally conductive silicone composition having a thermal conductivity of 3.0 W / m·K or higher, which contains 1,200 to 6,500 parts by mass of amorphous aluminum oxide powder having an average particle size of 10 to 30 μm, spherical aluminum oxide powder having an average particle size of 30 to 85 μm, and aluminum hydroxide powder or aluminum oxide powder having an average particle size of 0.1 to 6 μm, per 100 parts by mass of an organopolysiloxane as the main component.

[0004] However, when a high loading of aluminum nitride powder, which has a relatively high thermal conductivity, was used to obtain a thermally conductive silicone composition with even higher thermal conductivity, it was found that the viscosity of the resulting composition increased significantly, and furthermore, the thermally conductive component obtained by curing the composition suffered from the problem of internal cracking during aging at high temperatures. Therefore, there was a need for a thermally conductive silicone composition that had high thermal conductivity and did not suffer from the problem of internal cracking at high temperatures after curing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-003831 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-147600 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 is easy to handle and fill, and that cures to form a thermally conductive component having high thermal conductivity, for example, a thermal conductivity of 7 W / m·K or greater, and that is inhibited from developing internal cracks at high temperatures. Another object of the present invention is to provide a thermally conductive component having high thermal conductivity, for example, a thermal conductivity of 7 W / m·K or greater, and that is inhibited from developing internal cracks at high temperatures. [Means for solving the problem]

[0007] The thermally conductive silicone composition of the present invention comprises: (A) an organopolysiloxane having an average of at least two alkenyl groups per molecule and a viscosity at 25°C of 10 to 100,000 mPa·s; (B) an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule, in an amount such that the number of silicon-bonded hydrogen atoms in component (B) is 0.2 to 5 moles per mole of alkenyl groups in component (A); (C) a catalytic amount of a hydrosilylation catalyst; (D) The following components (D-1) to (D-3): (D-1) A thermally conductive powder other than aluminum nitride powder, having an average particle size of 0.1 μm or more and less than 5 μm; (D-2) Aluminum nitride powder having an average particle size of 20 μm or more and less than 80 μm; (D-3) Spherical aluminum oxide powder and / or spherical magnesium oxide powder having an average particle size of 80 μm or more The total content of components (D-1) to (D-3) is 70 to 90% by volume of the composition, and the content of component (D-2) is 5 to 30% by volume of the composition. (E) The following components (E-1) and (E-2): (E-1) General formula: R 1 (R 2 2SiO) m SiR 2 2-R 3 -SiR 2 a (OR 4 ) (3-a) (In the formula, R 1 is an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, and each R 2 are independently alkyl groups having 1 to 6 carbon atoms, and R 3 is an oxygen atom or an alkylene group having 2 to 6 carbon atoms, and R 4 is an alkyl group having 1 to 3 carbon atoms, m is an integer of 1 to 200, and a is 0, 1, or 2. Organopolysiloxanes represented by the formula: (E-2) General formula: R 5 b R 2 c Si(OR 4 ) (4-b―c) (In the formula, R 2 and R 4 is the same as above, and R 5 is an alkyl group having 6 to 18 carbon atoms, b is 1 or 2, c is 0 or 1, and b+c is 1 or 2. or a hydrolysis condensate thereof represented by the formula: a surface treatment agent or wetter having a mass ratio of component (E-1) to component (E-2) of 95:5 to 5:95, in an amount of 0.1 to 5.0 parts by mass per 100 parts by mass of component (D), The present invention is characterized by comprising at least the following:

[0008] In the present composition, component (D-1) is preferably a thermally conductive powder selected from silver powder, aluminum powder, aluminum oxide powder, zinc oxide powder, and graphite powder, and further preferably comprises the following components (D-1-1) and (D-1-2): (D-1-1) A thermally conductive powder other than aluminum nitride powder, having an average particle size of 0.1 μm or more and less than 1 μm; (D-1-2) Thermally conductive powder other than aluminum nitride powder, with an average particle size of 1 μm or more and less than 5 μm and the mass ratio of component (D-1-1) to component (D-1-2) is preferably 95:5 to 5:95.

[0009] Furthermore, the present composition may contain (F) a hydrosilylation reaction inhibitor in an amount of 0.001 to 5 mass % of the present composition, and may also contain (G) a heat resistance imparting agent in an amount of 0.01 to 5.0 mass % of the present composition.

[0010] The present composition preferably cures to form a thermally conductive member having a thermal conductivity of 7 W / m·K or more.

[0011] The thermally conductive member of the present invention is characterized by being obtained by curing the above-described composition. [Effects of the Invention]

[0012] The thermally conductive silicone composition of the present invention is characterized by its easy handling and filling properties, and by its ability to cure to form a thermally conductive member having high thermal conductivity, for example, a thermal conductivity of 7 W / m K or greater, and in which the occurrence of internal cracking at high temperatures is suppressed. Furthermore, the thermally conductive member of the present invention is characterized by its high thermal conductivity, for example, a thermal conductivity of 7 W / m K or greater, and in which the occurrence of internal cracking at high temperatures is suppressed. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Terminology> In this specification, the term "average particle size" refers to the median diameter (d50) measured by a laser diffraction / scattering method.

[0014] <Thermal conductive silicone composition> Component (A) is the main component of the composition and is an organopolysiloxane containing an average of at least two alkenyl groups per molecule. Examples of alkenyl groups in component (A) include alkenyl groups with 2 to 6 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, and hexenyl, with vinyl being preferred. Examples of groups bonded to silicon atoms other than alkenyl groups in component (A) include alkyl groups with 1 to 6 carbon atoms, such as methyl, ethyl, and propyl; aryl groups with 6 to 12 carbon atoms, such as phenyl and tolyl; and halogenated alkyl groups with 1 to 6 carbon atoms, such as 3,3,3-trifluoropropyl, with methyl and phenyl being preferred. Furthermore, within the scope of the present invention, small amounts of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy, may be bonded to silicon atoms in component (A).

[0015] The molecular structure of component (A) is not limited, and examples thereof include linear, partially branched linear, branched, cyclic, three-dimensional network structures, and combinations of these molecular structures. Specifically, component (A) may consist solely of linear organopolysiloxane, or may consist solely of branched organopolysiloxane, or may even be a mixture of linear and branched organopolysiloxanes.

[0016] Examples of such component (A) include dimethylpolysiloxanes terminally capped with dimethylvinylsiloxy groups, dimethylsiloxane-methylphenylsiloxane copolymers terminally capped with dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymers terminally capped with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers terminally capped with trimethylsiloxy groups, dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers terminally capped with silanol groups, polymers in which some of the methyl groups have been substituted with alkyl groups other than methyl, such as ethyl or propyl, or halogenated alkyl groups such as 3,3,3-trifluoropropyl, polymers in which the vinyl groups have been substituted with alkenyl groups other than vinyl, such as allyl, butenyl, or hexenyl, and mixtures of two or more of these polymers.

[0017] The viscosity of component (A) at 25°C is in the range of 10 to 100,000 mPa·s, preferably 10 to 10,000 mPa·s or 10 to 1,000 mPa·s. When the viscosity of component (A) is at or above the lower limit of this range, the physical properties of the resulting thermally conductive member are improved, while when the viscosity is at or below the upper limit of this range, the handling and filling properties of the composition are improved. The viscosity of component (A) at 25°C can be measured using a rotational viscometer in accordance with JIS K7117-1.

[0018] Component (B) is the crosslinking agent for the composition and is an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule. While there is no particular upper limit on the number of silicon-bonded hydrogen atoms in component (B), the average number of silicon-bonded hydrogen atoms per molecule is preferably eight or less, since this allows for the formation of a flexible thermally conductive member. Component (B) preferably contains at least an organohydrogenpolysiloxane having an average of two to four silicon-bonded hydrogen atoms per molecule. This is because component (B) acts as a crosslink extender when crosslinking component (A), gently crosslinking the composition and forming a relatively flexible cured product. Examples of groups bonded to silicon atoms in component (B) include monovalent hydrocarbon groups free of aliphatic unsaturated bonds, such as alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, and propyl; aryl groups having 6 to 12 carbon atoms, such as phenyl and tolyl; and halogenated alkyl groups having 1 to 6 carbon atoms, such as 3,3,3-trifluoropropyl. Methyl and phenyl groups are preferred. Furthermore, within the scope of the present invention, small amounts of hydroxyl groups or alkoxy groups, such as methoxy and ethoxy groups, may be bonded to silicon atoms in component (B).

[0019] Examples of such component (B) include methylhydrogenpolysiloxanes terminally capped with trimethylsiloxy groups, methylhydrogensiloxane-dimethylsiloxane copolymers terminally capped with trimethylsiloxy groups, dimethylpolysiloxanes terminally capped with dimethylhydrogensiloxy groups, methylhydrogensiloxane-dimethylsiloxane copolymers terminally capped with dimethylhydrogensiloxy groups, polymers in which some of the methyl groups have been substituted with alkyl groups other than methyl groups, such as ethyl groups or propyl groups, or with halogenated alkyl groups such as 3,3,3-trifluoropropyl groups, and mixtures of two or more of these polymers.

[0020] The viscosity of component (B) at 25°C is not particularly limited, but is preferably in the range of 1 to 1,000 mPa·s, 1 to 500 mPa·s, or 1 to 100 mPa·s. When the viscosity of component (B) is at or above the lower limit of the above range, the physical properties of the resulting thermally conductive member are improved, while when the viscosity is at or below the upper limit of the above range, the handling and filling properties of the composition are improved. The viscosity of component (B) at 25°C can be measured using a rotational viscometer in accordance with JIS K7117-1.

[0021] The content of component (B) is an amount such that the number of silicon-bonded hydrogen atoms in this component is 0.2 to 5 moles, preferably 0.3 to 2.0 moles, or 0.4 to 1.0 moles, 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 composition is sufficiently cured, while, when the content is at or below the upper limit of the above range, the heat resistance of the resulting thermally conductive member is improved.

[0022] Component (C) is a hydrosilylation catalyst that accelerates the curing of the composition. Examples of such catalysts include platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts. Platinum-based catalysts are preferred because they significantly accelerate the curing of the composition. Examples of the platinum catalyst include platinum fine powder, chloroplatinic acid, an alcohol solution of chloroplatinic acid, a platinum-alkenylsiloxane complex, a platinum-olefin complex, a platinum-carbonyl complex, and catalysts in which these platinum catalysts are dispersed or encapsulated in a thermoplastic resin such as a silicone resin, a polycarbonate resin, or an acrylic resin; (methylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)trimethylplatinum(IV), (1,2,3,4,5-pentamethylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)dimethylethylplatinum(IV), (cyclopentadienyl)dimethylacetylplatinum(IV), (trimethylsilylcyclopentadienyl)trimethylplatinum(IV), (methoxycarbonylcyclopentadienyl)trimethylplatinum(IV), Examples of catalysts that exhibit activity when irradiated with high-energy rays include (dimethylphenylsilylcyclopentadienyl)trimethylcyclopentadienyl platinum(IV), trimethyl(acetylacetonato)platinum(IV), trimethyl(3,5-heptanedionato)platinum(IV), trimethyl(methylacetoacetate)platinum(IV), bis(2,4-pentanedionato)platinum(II), bis(2,4-hexanedionato)platinum(II), bis(2,4-heptanedionato)platinum(II), bis(3,5-heptanedionato)platinum(II), bis(1-phenyl-1,3-butanedionato)platinum(II), bis(1,3-diphenyl-1,3-propanedionato)platinum(II), and bis(hexafluoroacetylacetonato)platinum(II). Platinum-alkenylsiloxane complexes are particularly preferred.

[0023] In this platinum-alkenylsiloxane complex, examples of the alkenylsiloxane include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, alkenylsiloxanes in which some of the methyl groups of these alkenylsiloxanes have been substituted with ethyl groups, phenyl groups, etc., and alkenylsiloxanes in which the vinyl groups of these alkenylsiloxanes have been substituted with allyl groups, hexenyl groups, etc. In particular, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is preferred because the stability of this platinum-alkenylsiloxane complex is good.

[0024] The content of component (C) is a catalytic amount for accelerating the curing of the composition, and is preferably an amount such that the metal atoms in component (C) are in the range of 0.01 to 500 ppm, 0.01 to 100 ppm, or 0.01 to 50 ppm by mass relative to component (A).

[0025] Component (D) is a thermally conductive filler that imparts high thermal conductivity to the cured product of the composition, and (D) consists of the following components (D-1) to (D-3). (D-1) A thermally conductive powder other than aluminum nitride powder, having an average particle size of 0.1 μm or more and less than 5 μm; (D-2) Aluminum nitride powder having an average particle size of 20 μm or more and less than 80 μm; (D-3) Spherical aluminum oxide powder and / or spherical magnesium oxide powder having an average particle size of 80 μm or more

[0026] Component (D-1) is a thermally conductive powder other than aluminum nitride powder, having an average particle size of 0.1 μm or more and less than 5 μm. Specifically, metal-based powders such as bismuth, lead, tin, antimony, indium, cadmium, zinc, silver, copper, nickel, aluminum, iron, and metallic silicon; alloy-based powders such as alloys of two or more metals selected from the group consisting of bismuth, lead, tin, antimony, indium, cadmium, zinc, silver, aluminum, iron, and metallic silicon; metal oxide-based powders such as aluminum oxide, zinc oxide, silicon oxide, magnesium oxide, beryllium oxide, chromium oxide, and titanium oxide; metal hydroxide-based powders such as magnesium hydroxide, aluminum hydroxide, barium hydroxide, and calcium hydroxide; metal nitride-based powders other than aluminum nitride powder, such as boron nitride and silicon nitride; metal carbide-based powders such as silicon carbide, boron carbide, and titanium carbide; magnesium silicide, titanium silicide, zirconium silicide, tantalum silicide, niobium silicide, chromium silicide, tungsten silicide, and and molybdenum silicide; carbon-based powders such as diamond, graphite, fullerene, carbon nanotubes, graphene, activated carbon, and amorphous carbon black; soft magnetic alloy-based powders such as 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; and ferrite-based powders such as Mn-Zn ferrite, Mn-Mg-Zn ferrite, Mg-Cu-Zn ferrite, Ni-Zn ferrite, Ni-Cu-Zn ferrite, and Cu-Zn ferrite. Preferred are metal-based powders, metal oxide-based powders, and carbon powders, and more preferred are silver powder, aluminum powder, aluminum oxide powder, zinc oxide powder, and graphite powder. Furthermore, when electrical insulation properties are required for the present composition, metal oxide powders are preferred, and aluminum oxide powder or zinc oxide powder is particularly preferred.

[0027] The shape of component (D-1) is not particularly limited, but examples include spherical, needle-like, disc-like, rod-like, and irregular shapes, with spherical and irregular shapes being preferred. Furthermore, component (D-1) has an average particle size of 0.1 μm or more and less than 5 μm, and such component (D-1) is preferably a thermally conductive powder further comprising the following components (D-1-1) and (D-1-2). (D-1-1) A thermally conductive powder other than aluminum nitride powder, having an average particle size of 0.1 μm or more and less than 1 μm; (D-1-2) Thermally conductive powder other than aluminum nitride powder, with an average particle size of 1 μm or more and less than 5 μm

[0028] In component (D-1), the mass ratio of component (D-1-1) to component (D-1-2) is not particularly limited, but preferably ranges from 95:5 to 5:95. Such component (D-1-1) is generally available, and examples thereof include polyhedral spherical α-aluminum oxide powder (Sumitomo Chemical's AA04) and pulverized aluminum oxide powder (Sumitomo Chemical's AES-12). Similarly, such component (D-1-2) is generally available, and examples thereof include spherical fused-solidified aluminum oxide powder (Micron's AZ2-75) and polyhedral spherical α-aluminum oxide powder (Sumitomo Chemical's AA2).

[0029] Component (D-2) is an aluminum nitride powder having an average particle size of 20 μm or more but less than 80 μm. The shape of component (D-2) is not particularly limited and can be spherical, irregular, single crystal, polycrystalline, or a mixture thereof. Component (D-2) can be synthesized, for example, by the so-called direct nitriding method or reduction nitriding method. Aluminum nitride powder prepared by the direct nitriding method can be further pulverized to have a desired average particle size. Such component (D-2) is generally available. For irregular-shaped components, the TFZ series manufactured by Toyo Aluminum Co., Ltd. and the AN series manufactured by Combustion Synthesis Co., Ltd. can be used. For spherical components, the AIN series manufactured by Showa Denko K.K. and the ANF series manufactured by MARUWA Corporation can be used.

[0030] Component (D-3) is a spherical aluminum oxide powder and / or spherical magnesium oxide powder having an average particle size of 80 μm or more. Such component (D-3) is generally available, and examples thereof include spherical fused and solidified aluminum oxide powder (Micron's AY90-150, Denka's DAM-90, DAM-120) and spherical magnesium oxide powder (Denka's DMG-120).

[0031] The total content of the components (D-1) to (D-3) is 70 to 90% by volume, preferably 75 to 85% by volume, of the composition. The content of the component (D-2) is 5 to 30% by volume, preferably 20 to 30% by volume, of the composition. This is because, when the total content of the components (D-1) to (D-3) is equal to or greater than the lower limit of the above range, the composition can form a thermally conductive member with high thermal conductivity. On the other hand, when the total content of the components (D-1) to (D-3) is equal to or less than the upper limit of the above range, the composition is easy to handle and pack. Furthermore, when the content of the component (D-2) is equal to or greater than the lower limit of the above range, the composition can form a thermally conductive member with high thermal conductivity. On the other hand, when the content of the component (D-2) is equal to or less than the upper limit of the above range, the composition can be cured to prevent internal cracks from occurring at high temperatures. There are no limitations on the amount of component (D-1) contained, but an amount that represents 5 to 50% by volume, or 10 to 30% by volume, of the composition is preferred, as this will result in a thermally conductive silicone composition that is easier to handle and fill.

[0032] Component (E) is a component that acts as a surface treatment agent or wetter for component (D) in the present composition, and is represented by the general formula (E-1): R 1 (R 2 2SiO) m SiR 2 2-R 3 -SiR 2 a (OR 4 ) (3-a) and (E-2) an organopolysiloxane represented by the general formula: R 5 b R 2 c Si(OR 4 ) (4-b―c) The alkoxysilane is represented by the following formula: or a hydrolysis condensation product thereof.

[0033] In the above component (E-1), in the formula, R 1 R is an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms. 1 Examples of the alkyl group of R include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a heptyl group. 1 Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, and a hexenyl group.

[0034] In addition, in the formula, each R 2 are independently alkyl groups having 1 to 6 carbon atoms, and the R 1 Examples of alkyl groups include the same alkyl groups as those shown in the above.

[0035] Also, in the formula, R 3 is an oxygen atom or an alkylene group having 2 to 6 carbon atoms. 3 Examples of the alkylene group include an ethylene group, a propylene group, a butylene group, a pentylene group, and a heptylene group.

[0036] Also, in the formula, R 4 is an alkyl group having 1 to 3 carbon atoms, and examples thereof include a methyl group, an ethyl group, and a propyl group.

[0037] In the formula, m is an integer of 1 to 200, and preferably an integer of 5 to 200, an integer of 10 to 200, an integer of 100 to 200, or an integer of 110 to 200.

[0038] In the formula, a is 0, 1, or 2, and preferably 0 or 1.

[0039] Such component (E-1) includes compounds of the formula: (CH3)3SiO[(CH3)2SiO] 30 Si(OCH3)3 Organopolysiloxanes represented by the formula: (CH2=CH)(CH3)2SiO[(CH3)2SiO] 25 Si(OCH3)3 Organopolysiloxanes represented by the formula: (CH3)3SiO[(CH3)2SiO] 110 Si(OCH3)3 and organopolysiloxanes represented by the formula: (CH3)3SiO[(CH3)2SiO] 25 Si(CH3)2-C2H4-Si(OCH3)3 Examples of organopolysiloxanes include those represented by the following formula:

[0040] On the other hand, in the above component (E-2), in the formula, R 2 is an alkyl group having 1 to 6 carbon atoms, and examples thereof include the same groups as those mentioned above.

[0041] Also, in the formula, R 4 is an alkyl group having 1 to 3 carbon atoms, and examples thereof include the same groups as those mentioned above.

[0042] Also, in the formula, R 5 is an alkyl group having 6 to 18 carbon atoms, and examples thereof include a hexyl group, an octyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, and an octadecyl group.

[0043] In the above formula, b is 1 or 2, c is 0 or 1, and b+c is 1 or 2.

[0044] Examples of such component (E-2) include hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, undecyltrimethoxysilane, dodecyltrimethoxysilane, and tetradecyltriethoxysilane, with decyltrimethoxysilane being preferred.

[0045] In the above component (E), the mass ratio of component (E-1) to component (E-2) is in the range of 95:5 to 5:95, preferably in the range of 90:10 to 10:90, 85:15 to 30:70, or 85:15 to 60:40. This is because, when components (E-1) and (E-2) are used in the above mass ratio range, the handling and filling properties of the composition can be improved even when a large amount of component (D) is blended.

[0046] In the present composition, the amount of component (E) blended is 0.1 to 5.0 parts by mass, preferably 0.1 to 4.5 parts by mass, or 0.2 to 4.0 parts by mass, per 100 parts by mass of component (D). This is because, when the amount of component (E) blended is equal to or greater than the lower limit of the above range, the surface of component (D) is sufficiently treated, while, when the amount is equal to or less than the upper limit of the above range, the mechanical properties of the thermally conductive member obtained by curing the present composition are improved.

[0047] Unlike component (E-2), component (E-1) has a polysiloxane structure having a hydrolyzable silyl group at one end of the molecular chain. Therefore, by treating the composition with component (D) in combination with component (E-2), or by surface treating the composition with component (E-2) followed by surface treatment with component (E-1), the handleability and fillability of the composition can be improved, even when a large amount of component (D) is blended, and further, the thixotropy and vertical retention can be improved.

[0048] The surface treatment method using component (E-1) and component (E-2) is not particularly limited, and examples thereof include direct treatment of component (D), integral blending, and dry concentrate methods. Direct treatment methods include dry methods, slurry methods, and spray methods, and integral blending methods include direct methods and masterbatch methods, with the dry methods, slurry methods, and direct methods being more commonly used. Preferably, component (D) may be premixed with component (E-1) and component (E-2) in their entirety or in multiple stages using a known mixer, and the surface of the resulting mixture may then be treated.

[0049] In the present invention, the surface treatment method using component (E-1) and component (E-2) is preferably a direct treatment method, and in particular, a thermal surface treatment method in which component (D), component (E-1), and component (E-2) are mixed and heated (base heat) is the most suitable example. In this case, the temperature conditions and stirring time can be designed depending on the amount of sample, but are preferably in the range of 120 to 180°C and 0.25 to 10 hours. Component (D) can also be treated by mixing at room temperature rather than by heating and stirring, and this treatment can also be selected.

[0050] The mixing device is not particularly limited, and examples thereof include a single-screw or twin-screw continuous mixer, a two-roll mill, a Ross mixer, a Hobart mixer, a dental mixer, a planetary mixer, a kneader mixer, and a Henschel mixer.

[0051] The present composition preferably contains (F) a hydrosilylation reaction inhibitor to extend its pot life and improve its handling. Examples of such component (F) include acetylene compounds such as 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, and 2-phenyl-3-butyn-2-ol; enyne compounds such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; cycloalkenylsiloxanes such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; and triazole compounds such as benzotriazole.

[0052] The amount of component (F) added is not limited, but is preferably within the range of 0.001 to 5% by mass of the composition.

[0053] The composition may further contain a heat resistance additive (G) to improve the heat resistance of the thermally conductive member obtained by curing the composition. Examples of this component (G) include metal oxides such as iron oxide, titanium oxide, cerium oxide, magnesium oxide, aluminum oxide, and zinc oxide; metal hydroxides such as cerium hydroxide; phthalocyanine compounds, carbon black, cerium silanolates, cerium fatty acid salts, and reaction products of organopolysiloxanes and cerium carboxylates. Metal phthalocyanine compounds, such as the copper phthalocyanine compound disclosed in JP-A-2014-503680, are particularly preferred. An example of this copper phthalocyanine compound is 29H,31H-phthalocyaninato(2-)-N29,N30,N31,N32 copper. Such phthalocyanine compounds are commercially available, such as Stan-tone™ 40SP03 from PolyOne Corporation (Avon Lake, Ohio, USA).

[0054] The amount of such component (G) to be added is not particularly limited, but is preferably within the range of 0.01 to 5.0 mass %, 0.05 to 0.2 mass %, or 0.07 to 0.1 mass % of the present composition.

[0055] The composition may contain other optional components as long as they do not impair the objectives of the present invention. Examples of such optional components include inorganic fillers such as fumed silica, wet silica, crushed quartz, titanium oxide, magnesium carbonate, zinc oxide, iron oxide, diatomaceous earth, and carbon black; organopolysiloxanes that do not contain silicon-bonded hydrogen atoms or silicon-bonded alkenyl groups; and additives that impart cold resistance, flame retardancy, pigments, and dyes. The composition may also contain, if desired, known adhesion promoters; one or more antistatic agents, such as cationic surfactants, anionic surfactants, or nonionic surfactants; dielectric fillers; electrically conductive fillers; release components; thixotropic agents; antifungal agents; organic solvents, etc.

[0056] <Method for producing thermally conductive silicone composition> The method for preparing this composition is not particularly limited, but it can be prepared, for example, by first mixing component (D) and component (E-1), then mixing component (E-2), treating the surface of component (D) with component (E-1) and then component (E-2), and then mixing the remaining components (A) to (C), component (G), and any other optional components. Alternatively, it can be prepared by mixing component (D) and component (E-1) in component (A), then mixing component (E-2), treating the surface with component (E-1) and then component (E-2), and then mixing the remaining components (B), (C), (F), and any other optional components. Alternatively, it can be prepared by mixing components (A), (B), (E-1), and (E-2), then mixing and treating component (D), and then mixing the remaining components (C), (F), and any other optional components. Alternatively, the composition can be prepared by mixing component (D) and component (E-1) in advance, and then mixing component (E-2) with a portion of component (D) and component (E-1), and then mixing component (E-2) with the remainder of component (D).

[0057] The method for mixing the components is not particularly limited, and any conventionally known method can be used, but mixing is preferably carried out using a commonly used mixing device, such as a single-screw or twin-screw continuous mixer, a two-roll mill, a Ross mixer, a Hobart mixer, a dental mixer, a planetary mixer, a kneader mixer, or a Henschel mixer.

[0058] The composition may be a one-component composition (including a one-liquid type), but may also be a multi-component composition (multi-liquid type, particularly a two-liquid type) if necessary.

[0059] This composition has good handling and filling properties in the uncured state. There are no limitations on the viscosity of this composition at 25°C, but it is preferable that the viscosity at a strain rate of 1.0 (1 / s) measured using a rheometer or the like is in the range of 50 to 600 Pa s.

[0060] The composition cures via a hydrosilylation reaction to form a thermally conductive member having high thermal conductivity. The temperature conditions for curing the composition are not particularly limited, but are typically within the range of 20°C to 150°C, and more preferably within the range of 20°C to 80°C. Depending on the circumstances, the composition may be cured at a high temperature for a short period of time, or at a low temperature such as room temperature for a long period of time (for example, several hours to several days).

[0061] <Thermal conductive material> The thermally conductive member of the present invention is obtained by curing the above-mentioned composition and is relatively flexible, preferably having a hardness, for example, satisfying the range of 10 to 80 on the Type E hardness scale specified in JIS K 6249. A thermally conductive member having such hardness exhibits the properties of low elastic modulus and low stress, and can improve the adhesion and conformability between the heat-generating and heat-dissipating members of electronic components.

[0062] Furthermore, the thermally conductive member has high thermal conductivity, for example, 7 W / mK or higher. Such a thermally conductive member is useful as a heat transfer material (thermally conductive member) to be interposed at the interface between the thermal boundary surface of a heat-generating component and a heat dissipating component such as a heat sink or circuit board for cooling the heat-generating component by thermal conduction, and a heat dissipation structure can be formed using the thermally conductive member. While the type, size, and detailed structure of the heat-generating component are not particularly limited, the thermally conductive member has high thermal conductivity, excellent gap-filling properties, high adhesion and conformability even to heat-generating components with fine irregularities or narrow gap structures, and flexibility, making it suitable for heat dissipation structures in electrical and electronic devices, including cell-type secondary batteries. [Example]

[0063] The thermally conductive silicone composition and thermally conductive member of the present invention are described in more detail using examples. The viscosity (mPa·s) in the examples is the value measured at 25°C using a rotational viscometer conforming to JIS K7117-1. The appearance and viscosity of the thermally conductive silicone composition, as well as the thermal conductivity, hardness, and percentage of internal cracks of the thermally conductive member obtained by curing the composition, were evaluated as follows.

[0064] <Appearance of the thermally conductive silicone composition> The condition of the thermally conductive silicone composition at 25°C was visually observed.

[0065] <Viscosity of the Thermally Conductive Silicone Composition> The viscosity (Pa·s) of the thermally conductive silicone composition at 25°C was measured using an Anton Paar Rheocompass MCR102. The geometry was set to a 20 mm diameter plate, a 0.6 mm gap, and a 1.0 (1 / s) shear rate.

[0066] <Thermal conductivity of thermally conductive materials> The thermally conductive silicone composition was filled into a mold measuring 6 mm in height, 50 mm in length, and 30 mm in width, and after curing at 25°C for one day, it was removed from the mold to produce a thermally conductive member. The thermal conductivity of this thermally conductive member was measured using a TPS-500 (hot disc method) manufactured by Kyoto Electronics Manufacturing Co., Ltd.

[0067] <Hardness of thermal conductive material> The hardness of the thermally conductive member prepared as described above was measured using an ASKER TYPE E hardness tester manufactured by ASKER Corporation.

[0068] <Percentage of internal cracks in thermal conductive materials> The thermally conductive member prepared as described above was treated in a hot air circulating oven at 150°C for one day. It was then removed and cooled to room temperature. The thermally conductive member was cut horizontally at a height of 6 mm to check the internal condition. The percentage of cracks observed on the cut surface was read relative to the area, with a score of 0% indicating a uniform cut surface with no cracks and 100% indicating cracks observed across the entire cut surface.

[0069] <Preparation of Thermally Conductive Silicone Composition> Thermally conductive silicone compositions were prepared by uniformly mixing the following components to obtain the compositions shown in Tables 1 to 4. The specific preparation method is described in Example 1. The molar ratio of silicon-bonded hydrogen atoms in component (B) to alkenyl groups in component (A) in the thermally conductive silicone composition was 0.61.

[0070] The following components were used as component (A): (a-1): Dimethylpolysiloxane with a viscosity of 60 mPa·s and terminated at both ends with dimethylvinylsiloxy groups (vinyl group content = 1.53% by mass)

[0071] The following components were used as component (B): (b-1): Methylhydrogensiloxane-dimethylsiloxane copolymer capped at both ends with trimethylsiloxy groups, having an average of two silicon-bonded hydrogen atoms per molecule and a viscosity of 20 mPa·s (content of silicon-bonded hydrogen atoms = 0.10% by mass). (b-2): Methylhydrogensiloxane-dimethylsiloxane copolymer capped at both ends with trimethylsiloxy groups, having an average of five silicon-bonded hydrogen atoms per molecule and a viscosity of 5 mPa·s (silicon-bonded hydrogen atom content = 0.75% by mass).

[0072] The following components were used as component (C): (c-1): A 1,3-divinyltetramethyldisiloxane solution of a platinum 1,3-divinyltetramethyldisiloxane complex having a platinum concentration of 0.6% by mass.

[0073] Of the components (D), the following component was used as component (D-1). (d-1-1): Polyhedral spherical α-type aluminum oxide powder with an average particle size of 0.5 μm (AA04 from Sumitomo Chemical) (d-1-2): Crushed aluminum oxide powder with an average particle size of 0.4 μm (Sumitomo Chemical AES-12) (d-1-3): Spherical fused and solidified aluminum oxide powder with an average particle size of 2.5 μm (Micron AZ2-75) (d-1-4): Polyhedral spherical α-type aluminum oxide powder with an average particle size of 2 μm (AA2 from Sumitomo Chemical)

[0074] Of the components (D), the following component was used as component (D-2). (d-2-1): Irregular shaped aluminum nitride powder with an average particle size of 27 μm (Toyo Aluminum's TFZ-S30P) (d-2-2): Irregular shaped aluminum nitride powder with an average particle size of 72 μm (combustion synthesized AN-HF70LG-HTZ) (d-2-3): Spherical aluminum nitride powder with an average particle size of 32 μm (AIN3001 from Showa Denko)

[0075] Of the components (D), the following components were used for comparison with component (D-2). (d-2-4): Irregular shaped aluminum nitride powder with an average particle size of 19 μm (Toyo Aluminum's TFZ-S20P) (d-2-5): Irregular shaped aluminum nitride powder with an average particle size of 1.4 μm (Toyo Aluminum's TFZ-N01P)

[0076] Of the components (D), the following component was used as component (D-3). (d-3-1): Spherical fused and solidified aluminum oxide powder with an average particle size of 83 μm (Micron AY90-150) (d-3-2): Spherical fused and solidified aluminum oxide powder with an average particle size of 95 μm (Denka's DAM-90) (d-3-3): Spherical fused and solidified aluminum oxide powder with an average particle size of 121 μm (Denka DAM-120) (d-3-4): Spherical magnesium oxide powder with an average particle size of 96 μm (Denka's DMG-120)

[0077] Of the (D) components, the following components were used for comparison with component (D-3). (d-3-5): Spherical fused and solidified aluminum oxide powder with an average particle size of 37 μm (Micron AL35-125)

[0078] The following components were used as component (E): (e-1):Formula: (CH3)3SiO[(CH3)2SiO] 30 Si(OCH3)3 Organopolysiloxane represented by (e-2): Decyltrimethoxysilane

[0079] The following components were used as component (F): (f-1): 2-phenyl-3-butyn-2-ol

[0080] The following components were used as component (G): (g-1): 29H,31H-phthalocyaninato(2-)-N29, N30, N31, N32 copper

[0081] Example 1 100 parts by weight of component (a-1), 30.4 parts by weight of component (b-1), 45.7 parts by weight of component (e-1), 7.1 parts by weight of component (e-2), 5.36 parts by weight of component (g-1), 518 parts by weight of component (d-1-1), and 714 parts by weight of component (d-1-3) were added to a 300 ml plastic container and mixed at 1200 rpm for 1 minute using a THINKY Planetary Vacuum Mixer. Next, 893 parts by weight of component (d-2-1) were added and mixed at 1200 rpm for 1 minute, and then 1250 parts by weight of component (d-3-1) were added and mixed at 1200 rpm for 1 minute. Next, 0.022 parts by weight of component (f-1) and 0.54 parts by weight of component (b-2) were added and mixed at 1200 rpm for 30 seconds. The mixture was then cooled to room temperature, and 2.68 parts by mass of component (c-1) was added and mixed with a spatula for 3 minutes to prepare a thermally conductive silicone composition.

[0082] The viscosity of this thermally conductive silicone composition was measured at 25°C immediately after preparation. It was then cured at 25°C for one day, and the thermal conductivity and hardness of the resulting thermally conductive member were measured. This thermally conductive member was then treated in a hot air circulating oven at 150°C for one day, after which the proportion of internal cracks was measured. The results are shown in Table 1.

[0083] <Example 2> A thermally conductive silicone composition was prepared in the same manner as in Example 1, except that 1,250 parts by mass of component (d-3-2) was added instead of component (d-3-1) in Example 1. This thermally conductive silicone composition and the thermally conductive member obtained by curing it were measured and evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0084] Example 3 A thermally conductive silicone composition was prepared in the same manner as in Example 1, except that 1,250 parts by mass of component (d-3-3) was added instead of component (d-3-1) in Example 1. This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0085] Example 4 A thermally conductive silicone composition was prepared in the same manner as in Example 1, except that the amount of component (e-1) was changed to 56.4 parts by mass and 1,239 parts by mass of component (d-3-4) was added instead of component (d-3-1). This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0086] <Example 5> A thermally conductive silicone composition was prepared in the same manner as in Example 4, except that 893 parts by mass of component (d-2-2) was added instead of component (d-2-1) in Example 4. This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0087] [Table 1]

[0088] Example 6 A thermally conductive silicone composition was prepared in the same manner as in Example 2, except that 518 parts by mass of component (d-1-2) was added instead of component (d-1-1) in Example 2. This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0089] Example 7 A thermally conductive silicone composition was prepared in the same manner as in Example 2, except that 714 parts by mass of component (d-1-4) was added instead of component (d-1-3) in Example 2. This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0090] Example 8 A thermally conductive silicone composition was obtained in the same manner as in Example 7, except that the amount of component (d-2-1) was 357 parts by mass and the amount of component (d-3-2) was 1786 parts by mass. This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0091] Example 9 A thermally conductive silicone composition was prepared in the same manner as in Example 7, except that the amount of component (d-2-1) was changed to 179 parts by mass and the amount of component (d-3-2) was changed to 1964 parts by mass. This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0092] Example 10 A thermally conductive silicone composition was prepared in the same manner as in Example 7, except that 893 parts by mass of component (d-2-3) was added instead of component (d-2-1) in Example 7. This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0093] [Table 2]

[0094] <Comparative Example 1> A thermally conductive silicone composition was prepared in the same manner as in Example 2, except that 893 parts by mass of component (d-2-4) was added instead of component (d-2-1) in Example 2. This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0095] <Comparative Example 2> A thermally conductive silicone composition was prepared in the same manner as in Example 2, except that the amount of component (d-2-1) was 1,250 parts by mass and the amount of component (d-3-2) was 893 parts by mass. This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0096] <Comparative Example 3> A thermally conductive silicone composition was prepared in the same manner as in Example 1, except that the amount of component (d-2-1) was changed to 714 parts by mass, and 1071 parts by mass of component (d-2-2) was added instead of component (d-3-1). This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0097] <Comparative Example 4> A thermally conductive silicone composition was prepared in the same manner as in Example 1, except that 1,250 parts by mass of component (d-2-2) was added instead of component (d-3-1). This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0098] <Comparative Example 5> A thermally conductive silicone composition was prepared in the same manner as in Example 2, except that 714 parts by mass of component (d-2-5) was added instead of component (d-1-3). This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0099] [Table 3]

[0100] <Comparative Example 6> An attempt was made to prepare a thermally conductive silicone composition in the same manner as in Example 2, except that, instead of blending components (d-1-1) and (d-1-3), 536 parts by mass of component (d-2-5) was blended, and the blending amount of component (d-2-1) was changed to 1071 parts by mass; however, the resulting thermally conductive silicone composition was in powder form.

[0101] <Comparative Example 7> A thermally conductive silicone composition was prepared in the same manner as in Example 1, except that 893 parts by mass of component (d-3-5) was added instead of component (d-2-1). This thermally conductive silicone composition and the thermally conductive member obtained by curing it were evaluated in the same manner as in Example 1, and the results are shown in Table 4.

[0102] [Table 4]

[0103] The results of Examples 1 to 10 showed that when aluminum nitride powder with an average particle size of 20 μm or more and less than 80 μm was in the range of 5 to 30% by volume of the thermally conductive silicone composition, the composition exhibited a high thermal conductivity of 7 W / m·K or more, was in the form of a uniform paste before curing, and the thermally conductive component obtained after curing had internal cracks reduced to less than 20% of the total, even at temperatures as high as 150°C.

[0104] On the other hand, in Comparative Example 1, aluminum nitride powder with an average particle size of less than 20 μm was blended, and it was found that the resulting thermally conductive member had internal cracks of 50% or more at 150°C. Furthermore, in Comparative Examples 2 to 5, when the aluminum nitride powder was 30% or more by volume of the entire thermally conductive silicone composition, it was also found that the resulting thermally conductive member had internal cracks of 50% or more when heated to 150°C. Furthermore, in Comparative Example 6, aluminum nitride powder with an average particle size of less than 20 μm was blended, and no thermally conductive powder other than aluminum nitride powder with an average particle size of 0.1 μm or more and less than 5 μm was blended, but it was found that a uniform paste could not be obtained. Furthermore, in Comparative Example 7, aluminum nitride powder with an average particle size of 20 μm or more and less than 80 μm was not blended, and therefore the thermal conductivity of the resulting thermally conductive member did not reach 7 W / m·K or more. [Industrial Applicability]

[0105] The thermally conductive silicone composition of the present invention cures to form a thermally conductive member that has high thermal conductivity, for example, a thermal conductivity of 7 W / m K or higher, and is resistant to internal cracking at high temperatures, making it useful as a heat transfer material (thermally conductive member) for efficiently transferring heat from heat-generating electronic components to heat-dissipating members. Furthermore, the thermally conductive member of the present invention is flexible, has excellent gap-filling properties, and exhibits high adhesion and conformability even to heat-generating members with fine irregularities or narrow gap structures, making it suitable as a thermally conductive member for electrical and electronic devices, including secondary batteries.

Claims

1. (A) an organopolysiloxane having an average of at least two alkenyl groups per molecule and a viscosity at 25°C of 10 to 100,000 mPa·s; (B) an organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule, in an amount such that the number of silicon-bonded hydrogen atoms in component (B) is 0.2 to 5 moles per mole of alkenyl groups in component (A); (C) a catalytic amount of a hydrosilylation catalyst; (D) The following components (D-1) to (D-3): (D-1) A thermally conductive powder other than aluminum nitride powder, having an average particle size of 0.1 μm or more and less than 5 μm; (D-2) Aluminum nitride powder having an average particle size of 20 μm or more and less than 80 μm; (D-3) Spherical aluminum oxide powder and / or spherical magnesium oxide powder having an average particle size of 80 μm or more The total content of components (D-1) to (D-3) is 70 to 90% by volume of the composition, and the content of component (D-2) is 5 to 30% by volume of the composition. (E) The following components (E-1) and (E-2): (E-1) General formula: R １ (R ２ ２ SiO) ｍ SiR ２ ２ -R ３ -SiR ２ ａ (OR ４ ) (３－ａ) (In the formula, R １ is an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, and each R ２ are independently alkyl groups having 1 to 6 carbon atoms, and R ３ is an oxygen atom or an alkylene group having 2 to 6 carbon atoms, and R ４ is an alkyl group having 1 to 3 carbon atoms, m is an integer from 1 to 200, and a is 0, 1, or 2. Organopolysiloxanes represented by the formula: (E-2) General formula: R ５ ｂ R ２ ｃ Si(OR ４ )(4-b―c) (In the formula, R ２ and R ４ is the same as above, and R ５ is an alkyl group having 6 to 18 carbon atoms, b is 1 or 2, c is 0 or 1, and b+c is 1 or 2. or a hydrolysis condensate thereof represented by the formula: a surface treatment agent or wetter having a mass ratio of component (E-1) to component (E-2) of 95:5 to 5:95, in an amount of 0.1 to 5.0 parts by mass per 100 parts by mass of component (D); A thermally conductive silicone composition comprising at least

2. 2. The thermally conductive silicone composition according to claim 1, wherein component (D-1) is a thermally conductive powder selected from the group consisting of silver powder, aluminum powder, aluminum oxide powder, zinc oxide powder, and graphite powder.

3. Component (D-1) is the following component (D-1-1) and component (D-1-2): (D-1-1) A thermally conductive powder other than aluminum nitride powder, having an average particle size of 0.1 μm or more and less than 1 μm; (D-1-2) Thermally conductive powder other than aluminum nitride powder, having an average particle size of 1 μm or more and less than 5 μm 2. The thermally conductive silicone composition according to claim 1, wherein the mass ratio of component (D-1-1) to component (D-1-2) is 95:5 to 5:

95.

4. 2. The thermally conductive silicone composition according to claim 1, further comprising (F) a hydrosilylation reaction inhibitor in an amount of 0.001 to 5 mass % of the composition.

5. 2. The thermally conductive silicone composition according to claim 1, further comprising (G) a heat resistance imparting agent in an amount of 0.01 to 5.0% by mass of the composition.

6. 5. The thermally conductive silicone composition according to claim 1, which upon curing forms a thermally conductive component having a thermal conductivity of at least 7 W / m·K.

7. A thermally conductive member obtained by curing the thermally conductive silicone composition according to any one of claims 1 to 6.

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