Thermally Conductive Organosilicon Composition and Thermally Conductive Component

Abstract

The thermally conductive silicone composition of the present invention has at least the following components: (A) a polyorganosiloxane having an average of at least two alkenyl groups in one molecule; (B) an organohydrogenpolysiloxane having an average of at least two silicon atoms bonded to hydrogen atoms in one molecule; (C) a catalyst for hydrosilylation reaction; (D) a thermally conductive filler composed of the following components (D-1) to (D-3): (D-1) a thermally conductive powder other than aluminum nitride powder having an average particle diameter of 0.1 μm or more and less than 5 μm, (D-2) an aluminum nitride powder having an average particle diameter of 20 μm or more and less than 80 μm, (D-3) spherical alumina powder and / or spherical magnesia powder having an average particle diameter of 80 μm or more; and (E) a specific surface treatment agent or wetting agent. The composition has good operability and filling properties, and cures to form a thermally conductive member having high thermal conductivity and suppressing the generation of internal cracks at high temperatures.

Description

Technical Field

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

[0002] In order to efficiently transfer heat generated by an electronic device to a heat sink, a curable thermally conductive silicone composition containing a thermally conductive filler such as silica powder, alumina powder, boron nitride powder, aluminum nitride powder, and magnesium oxide powder is used. In recent years, a composition with high thermal conductivity has been required, and it is known to highly fill at least two thermally conductive fillers having 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 more, in which, relative to 100 parts by mass of the main component polyorganosiloxane, at least 1000 parts by mass of spherical alumina powder having an average particle size of 5 to 40 μm and spherical alumina powder having an average particle size of 0.1 to 3 μm are blended. Further, Patent Document 2 discloses a thermally conductive silicone composition having a thermal conductivity of 3.0 W / m·K or more, in which, relative to 100 parts by mass of the main component polyorganosiloxane, 1200 to 6500 parts by mass of amorphous alumina powder having an average particle size of 10 to 30 μm, spherical alumina powder having an average particle size of 30 to 85 μm, and aluminum hydroxide powder or alumina powder having an average particle size of 0.1 to 6 μm are blended.

[0004] However, it is known that there are the following problems. In order to obtain a thermally conductive silicone composition having a higher thermal conductivity, aluminum nitride powder having a higher thermal conductivity is highly filled, and as a result, the viscosity of the obtained composition significantly increases. Furthermore, cracks are generated inside the thermally conductive member obtained by curing it during curing at high temperature. Therefore, a thermally conductive silicone composition having high thermal conductivity and no problem of internal cracks at high temperature after curing is required.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-003831

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-147600 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] An object of the present invention is to provide a thermally conductive silicone composition having good workability and filling properties, which cures to form a thermally conductive member having high thermal conductivity, for example, a thermal conductivity of 7 W / m·K or more, and in which generation of internal cracks at high temperatures is suppressed. Another object of the present invention is to provide a thermally conductive member having high thermal conductivity, for example, a thermal conductivity of 7 W / m·K or more, and in which generation of internal cracks at high temperatures is suppressed.

[0011] Means for solving the problems

[0012] The thermally conductive silicone composition of the present invention is characterized in that the thermally conductive silicone composition has at least the following components:

[0013] (A) A polyorganosiloxane having an average of at least two alkenyl groups in one molecule and a viscosity at 25°C of 10 to 100,000 mPa·s;

[0014] (B) An organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms in one molecule: an amount of 0.2 to 5 moles of silicon-bonded hydrogen atoms in component (B) relative to 1 mole of alkenyl groups in component (A);

[0015] (C) A catalytic amount of a catalyst for hydrosilylation reaction;

[0016] (D) A thermally conductive filler composed of the following components (D-1) to (D-3):

[0017] (D-1) A thermally conductive powder other than aluminum nitride powder having an average particle diameter of 0.1 μm or more and less than 5 μm;

[0018] (D-2) Aluminum nitride powder having an average particle diameter of 20 μm or more and less than 80 μm;

[0019] (D-3) Spherical alumina powder and / or spherical magnesia powder having an average particle diameter of 80 μm or more:

[0020] The total content of components (D-1) to (D-3) is 70 to 90% by volume of the present composition, and the content of component (D-2) is 5 to 30% by volume of the present composition; and

[0021] (E) A surface treatment agent or wetting agent composed of the following components (E-1) and (E-2), and the mass ratio of component (E-1) to component (E-2) is 95:5 to 5:95:

[0022] (E-1) General formula:

[0023] R 1 (R 2 2 SiO) mSiR 2 2 -R 3 -SiR 2 a (OR 4 ) (3-a)

[0024] (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 is independently an alkyl group having 1 to 6 carbon atoms, R 3 is an oxygen atom or an alkylene group having 2 to 6 carbon atoms, 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.)

[0025] The polyorganosiloxane shown;

[0026] (E-2) General formula:

[0027] R 5 b R 2 c Si(OR 4 ) (4-b-c)

[0028] (In the formula, R 2 and R 4 are the same as the said R 2 and R 4 , 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.)

[0029] The alkoxysilane shown or its hydrolysis condensate:

[0030] The amount of the said (E) is 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the said component (D).

[0031] In this composition, preferably, the component (D-1) is a heat conductive powder selected from silver powder, aluminum powder, alumina powder, zinc oxide powder, and graphite powder. In addition, preferably, the component (D-1) is composed of the following component (D-1-1) and component (D-1-2), and the mass ratio of the component (D-1-1) to the component (D-1-2) is 95:5 to 5:95 heat conductive powder:

[0032] (D-1-1) A heat conductive powder other than aluminum nitride powder having an average particle diameter of 0.1 μm or more and less than 1 μm,

[0033] (D-1-2) A heat conductive powder having an average particle diameter of 1 μm or more and less than 5 μm and other than aluminum nitride powder.)

[0034] In the case of this composition, it may also contain 0.001 to 5% by mass of (F) hydrosilylation reaction inhibitor of this composition. In addition, it may also contain 0.01 to 5.0% by mass of (G) heat resistance imparting agent of this composition.

[0035] In the case of this composition, preferably, the composition is cured to form a heat conductive member having a thermal conductivity of 7 W / m·K or more.

[0036] The heat conductive member of the present invention is characterized in that the heat conductive member is formed by curing the above composition.

[0037] Advantages of the Invention

[0038] The heat conductive silicone composition of the present invention has the following characteristics: good operability and filling property, cured to form a heat conductive member having high thermal conductivity such as a thermal conductivity of 7 W / m·K or more, and suppressing the generation of internal cracks at high temperature. In addition, the heat conductive member of the present invention has the following characteristics: having high thermal conductivity such as a thermal conductivity of 7 W / m·K or more, and suppressing the generation of internal cracks at high temperature. Detailed Description of the Invention

[0039] <Definition of Terms>

[0040] In this specification, "average particle size" refers to the median particle size (d50) measured by the laser diffraction / scattering method.

[0041] <Heat Conductive Silicone Composition>

[0042] Component (A) is the main agent of this composition and is a polyorganosiloxane having an average of at least two alkenyl groups in one molecule. Examples of the alkenyl group in component (A) include alkenyl groups having 2 to 6 carbon atoms such as vinyl, allyl, butenyl, pentenyl, and hexenyl, and preferably vinyl. In addition, examples of the groups bonded to the silicon atom other than the alkenyl group in component (A) include 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 haloalkyl groups having 1 to 6 carbon atoms such as 3,3,3-trifluoropropyl, and preferably methyl and phenyl. Further, within the scope not damaging the object of the present invention, the silicon atom in component (A) may also be bonded to a small amount of hydroxyl groups or alkoxy groups such as methoxy and ethoxy.

[0043] The molecular structure of component (A) is not limited. For example, it can be linear, linear with some branched chains, branched, cyclic, three-dimensional network structure, or a combination of these molecular structures. Specifically, component (A) can be only a linear polyorganosiloxane, or it can be only a branched polyorganosiloxane, or it can be a mixture of a linear polyorganosiloxane and a branched polyorganosiloxane.

[0044] Examples of such component (A) include: dimethylvinylsilanyloxy-terminated dimethylpolysiloxane with both ends of the molecular chain, dimethylsiloxane / methylphenylsiloxane copolymer terminated with dimethylvinylsilanyloxy at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane copolymer terminated with trimethylsilanyloxy at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane / methylphenylsiloxane copolymer terminated with trimethylsilanyloxy at both ends of the molecular chain, dimethylsiloxane / methylvinylsiloxane copolymer terminated with silanol groups at both ends of the molecular chain, polymers obtained by substituting a part of the methyl groups of these polymers with alkyl groups other than methyl such as ethyl and propyl, halogenated alkyl groups such as 3,3,3-trifluoropropyl, polymers obtained by substituting the vinyl groups of these polymers with alkenyl groups other than vinyl such as allyl, butenyl, and hexenyl, and mixtures of two or more of these polymers.

[0045] The viscosity of component (A) at 25°C is in the range of 10 to 100,000 mPa·s, preferably in the range of 10 to 10,000 mPa·s, or in the range of 10 to 1,000 mPa·s. The reason is that if the viscosity of component (A) is above the lower limit of the above range, the physical properties of the obtained heat-conductive member are improved. On the other hand, if the viscosity of component (A) is below the upper limit of the above range, the operability and filling property of the present composition are improved. It should be noted that the viscosity of component (A) at 25°C can be measured by a rotational viscometer according to JIS K7117-1.

[0046] Component (B) is a crosslinking agent of the present composition and is an organohydrogenpolysiloxane having an average of at least two silicon atoms bonded to hydrogen atoms in one molecule. The upper limit of the number of silicon atoms bonded to hydrogen atoms in component (B) is not particularly limited, but from the aspect of forming a soft heat-conductive member, the number (average value) of silicon atoms bonded to hydrogen atoms in one molecule is preferably 8 or less. It should be noted that component (B) preferably contains at least an organohydrogenpolysiloxane having an average of 2 to 4 silicon atoms bonded to hydrogen atoms in one molecule. The reason is that such component (B) acts as a crosslinking extender when crosslinking component (A), slowly crosslinks the present composition, and forms a relatively soft cured product. In addition, examples of the group bonded to the silicon atom in component (B) include: monovalent hydrocarbon 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, which do not have aliphatic unsaturated bonds, and methyl and phenyl are preferred. Furthermore, within the range not impairing the object of the present invention, the silicon atoms in component (B) may also be bonded to a small amount of hydroxyl groups or alkoxy groups such as methoxy and ethoxy.

[0047] Examples of such component (B) include: methylhydrogenpolysiloxane endblocked with trimethylsilyloxy at both ends of the molecular chain, methylhydrogensiloxane / dimethylsiloxane copolymer endblocked with trimethylsilyloxy at both ends of the molecular chain, dimethylpolysiloxane endblocked with dimethylhydrogensilyloxy at both ends of the molecular chain, methylhydrogensiloxane / dimethylsiloxane copolymer endblocked with dimethylhydrogensilyloxy at both ends of the molecular chain, polymers obtained by substituting a part of the methyl groups of these polymers with alkyl groups other than methyl such as ethyl and propyl, halogenated alkyl groups such as 3,3,3-trifluoropropyl, and mixtures of two or more of these polymers.

[0048] The viscosity of component (B) at 25°C is not particularly limited, and is preferably in the range of 1 to 1000 mPa·s, in the range of 1 to 500 mPa·s, or in the range of 1 to 100 mPa·s. The reason is that if the viscosity of component (B) is above the lower limit of the above range, the physical properties of the obtained heat-conductive member are improved, and on the other hand, if the viscosity of component (B) is below the upper limit of the above range, the operability and filling property of the present composition are improved. It should be noted that the viscosity of component (B) at 25°C can be measured by a rotational viscometer according to JIS K7117-1.

[0049] The content of component (B) is in an amount such that the number of moles of hydrogen atoms bonded to silicon atoms in this component is 0.2 to 5 moles, preferably 0.3 to 2.0 moles, or 0.4 to 1.0 moles, relative to 1 mole of the alkenyl group in component (A). The reason is that if the content of component (B) is above the lower limit of the above range, the present composition is sufficiently cured. On the other hand, if the content of component (B) is below the upper limit of the above range, the heat resistance of the obtained heat conductive member is improved.

[0050] Component (C) is a catalyst for the hydrosilylation reaction for promoting the curing of the present composition, and examples thereof include: platinum-based catalysts, rhodium-based catalysts, palladium-based catalysts. From the aspect of being able to significantly promote the curing of the present composition, platinum-based catalysts are preferred. Examples of such platinum-based catalysts include: platinum fine powder, chloroplatinic acid, an alcoholic solution of chloroplatinic acid, a platinum-alkenylsiloxane complex, a platinum-olefin complex, a platinum-carbonyl complex, and a catalyst in which these platinum-based catalysts are dispersed or encapsulated by a thermoplastic resin such as an organosilicon resin, a polycarbonate resin, or an acrylic resin; (methylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)trimethylplatinum(IV), (1,2,3,4,5-pentamethylcyclopentadienyl)trimethylplatinum(IV), (cyclopentadienyl)dimethyl ethylplatinum(IV), (cyclopentadienyl)dimethyl acetylplatinum(IV), (trimethylsilylcyclopentadienyl)trimethylplatinum(IV), (methoxycarbonylcyclopentadienyl)trimethylplatinum(IV), (dimethylphenylsilylcyclopentadienyl)trimethylcyclopentadienylplatinum(IV), trimethyl(acetylacetone)platinum(IV), trimethyl(3,5-heptanedionate)platinum(IV), trimethyl(methylacetoacetate)platinum(IV), bis(2,4-pentanedionate)platinum(II), bis(2,4-hexanedionate)platinum(II), bis(2,4-heptanedionate)platinum(II), bis(3,5-heptanedionate)platinum(II), bis(1-phenyl-1,3-butanedionate)platinum(II), bis(1,3-diphenyl-1,3-propanedionate)platinum(II), bis(hexafluoroacetylacetone)platinum(II), etc., catalysts that show activity under the irradiation of high-energy rays, and platinum-alkenylsiloxane complexes are particularly preferred.

[0051] In the 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 a part of the methyl groups of these alkenylsiloxanes are replaced with ethyl, phenyl, etc., and alkenylsiloxanes in which the vinyl groups of these alkenylsiloxanes are replaced with allyl, hexenyl, etc. In particular, from the viewpoint of good stability of the platinum-alkenylsiloxane complex, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is preferred.

[0052] The content of component (C) is the catalytic amount for promoting the curing of the present composition. Preferably, the metal atom in component (C) is in an amount in the range of 0.01 to 500 ppm, in the range of 0.01 to 100 ppm, or in the range of 0.01 to 50 ppm in terms of mass unit with respect to component (A).

[0053] Component (D) is a thermal conductivity filler for imparting high thermal conductivity to the cured product of the present composition, and (D) is composed of the following components (D-1) to (D-3).

[0054] (D-1) A thermal conductivity powder other than aluminum nitride powder having an average particle size of 0.1 μm or more and less than 5 μm;

[0055] (D-2) Aluminum nitride powder having an average particle size of 20 μm or more and less than 80 μm;

[0056] (D-3) Spherical alumina powder and / or spherical magnesia powder having an average particle size of 80 μm or more:

[0057] Component (D-1) is a heat-conductive powder other than aluminum nitride powder with an average particle size of 0.1 μm or more and less than 5 μm. Specifically, examples thereof include: 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 composed 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 alumina, zinc oxide, silica, magnesia, beryllia, 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; metal silicide-based powders such as magnesium silicide, titanium silicide, zirconium silicide, tantalum silicide, niobium silicide, chromium silicide, tungsten silicide, and molybdenum silicide; carbon-based powders such as diamond, graphite, fullerene, carbon nanotube, 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. It is preferably a metal-based powder, a metal oxide-based powder, or a carbon powder, and more preferably a silver powder, an aluminum powder, an alumina powder, a zinc oxide powder, or a graphite powder. In addition, when electrical insulation is required in this composition, a metal oxide-based powder is preferred, and an alumina powder or a zinc oxide powder is particularly preferred.

[0058] The shape of component (D-1) is not particularly limited, and examples thereof include: spherical, needle-like, disc-like, rod-like, and irregular shapes, and spherical and irregular shapes are preferred. In addition, the average particle size of component (D-1) is 0.1 μm or more and less than 5 μm, and such component (D-1) is further preferably a heat-conductive powder composed of the following component (D-1-1) and component (D-1-2).

[0059] (D-1-1) A heat-conductive powder other than aluminum nitride powder with an average particle size of 0.1 μm or more and less than 1 μm;

[0060] (D-1-2) A heat-conductive powder other than aluminum nitride powder with an average particle size of 1 μm or more and less than 5 μm.

[0061] In component (D-1), the mass ratio of the above-mentioned component (D-1-1) to the above-mentioned component (D-1-2) is not particularly limited. Preferably, their mass ratio is in the range of 95:5 to 5:95. Such a component (D-1-1) can usually be obtained. For example, polyhedral spherical α-aluminum oxide powder (AA04 of Sumitomo Chemical), crushed aluminum oxide powder (AES-12 of Sumitomo Chemical), etc. can be used. In addition, such a component (D-1-2) can usually also be obtained. Spherical fused and solidified aluminum oxide powder (AZ2-75 of Micron), polyhedral spherical α-aluminum oxide powder (AA2 of Sumitomo Chemical), etc. can be used.

[0062] In addition, component (D-2) is aluminum nitride powder with an average particle size of 20 μm or more and 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 nitridation method, reduction nitridation method, etc. In the case of aluminum nitride powder obtained by the direct nitridation method, it can also be made to be within the target average particle size range by further crushing, etc. Such a component (D-2) can usually be obtained. As the irregular shape, the TFZ series manufactured by Toyo Aluminium Co., Ltd., the AN series manufactured by Combustion Synthesis Co., Ltd., etc. can be used. In addition, as the spherical shape, the AIN series manufactured by Showa Denko K.K., the ANF series manufactured by MARUWA Co., Ltd., etc. can be used.

[0063] In addition, component (D-3) is spherical aluminum oxide powder and / or spherical magnesium oxide powder with an average particle size of 80 μm or more. Such a component (D-3) can usually be obtained. For example, spherical fused and solidified aluminum oxide powder (AY90-150 of Micron, DAM-90, DAM-120 of Denka) / spherical magnesium oxide powder (DMG-120 of Denka), etc. can be used.

[0064] The total content of the above components (D-1) to (D-3) is in an amount of 70 to 90% by volume of this composition, preferably in an amount of 75 to 85% by volume. On the other hand, the content of the above component (D-2) is in an amount of 5 to 30% by volume of this composition, preferably in an amount of 20 to 30% by volume. The reason is that if the total content of the above components (D-1) to (D-3) is above the lower limit of the above range, this composition can form a heat-conductive member with high thermal conductivity. On the other hand, if the total content of the above components (D-1) to (D-3) is below the upper limit of the above range, the operability and filling property of this composition are improved. In addition, the reason is that if the content of the above component (D-2) is above the lower limit of the above range, this composition forms a heat-conductive member with high thermal conductivity. On the other hand, if the content of the above component (D-2) is below the upper limit of the above range, the generation of internal cracks at high temperatures in the heat-conductive member obtained by curing this composition can be suppressed. It should be noted that the content of the above component (D-1) is not limited, but from the aspect of obtaining a thermally conductive silicone composition with better operability and filling property, it is preferably in an amount of 5 to 50% by volume of this composition, or in an amount of 10 to 30% by volume.

[0065] Component (E) is a component that functions as a surface treatment agent or wetting agent for the above component (D) in this composition, and it is composed of the following (E-1) and (E-2): (E-1) General formula:

[0066] R 1 (R 2 2 SiO) m SiR 2 2 -R 3 -SiR 2 a (OR 4 ) (3-a)

[0067] The shown polyorganosiloxane; and (E-2) General formula:

[0068] R 5 b R 2 c Si(OR 4 ) (4-b-c)

[0069] The shown alkoxysilane or its hydrolysis condensate.

[0070] In the above component (E-1), 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. As R 1The alkyl groups may be exemplified by: methyl, ethyl, propyl, butyl, pentyl, heptyl. In addition, as R 1 The alkenyl groups may be exemplified by: vinyl, allyl, butenyl, pentenyl, hexenyl.

[0071] In addition, in the formula, each R 2 is independently an alkyl group having 1 to 6 carbon atoms, and may be exemplified by the same alkyl groups as those of the aforementioned R 1 .

[0072] In addition, in the formula, R 3 is an oxygen atom or an alkylene group having 2 to 6 carbon atoms. As the alkylene group of R 3 , it may be exemplified by: ethylene, propylene, butylene, pentylene, heptylene.

[0073] In addition, in the formula, R 4 is an alkyl group having 1 to 3 carbon atoms, and may be exemplified by: methyl, ethyl, propyl.

[0074] In addition, in the formula, m is an integer of 1 to 200, 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.

[0075] In addition, in the formula, a is 0, 1 or 2, preferably 0 or 1.

[0076] As such a component (E-1), it may be exemplified by the formula:

[0077] (CH 3 ) 3 SiO[(CH 3 ) 2 SiO] 30 Si(OCH 3 ) 3

[0078] the polyorganosiloxane shown, the formula:

[0079] (CH 2 =CH)(CH 3 ) 2 SiO[(CH 3 ) 2 SiO] 25 Si(OCH 3 ) 3

[0080] the polyorganosiloxane shown, the formula:

[0081] (CH 3 ) 3 SiO[(CH 3 ) 2SiO 110 Si(OCH 3 ) 3

[0082] The polyorganosiloxane shown, and the formula:

[0083] (CH 3 ) 3 SiO[(CH 3 ) 2 SiO 25 Si(CH 3 ) 2 -C 2 H 4 -Si(OCH 3 ) 3

[0084] The polyorganosiloxane shown.

[0085] 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 groups similar to the said R 2 can be exemplified.

[0086] In addition, in the formula, R 4 is an alkyl group having 1 to 3 carbon atoms, and groups similar to the said R 4 can be exemplified.

[0087] In addition, in the formula, R 5 is an alkyl group having 6 to 18 carbon atoms, and examples thereof include: hexyl, octyl, dodecyl, tetradecyl, hexadecyl, octadecyl.

[0088] In addition, in the above formula, b is 1 or 2, c is 0 or 1, and b + c is 1 or 2.

[0089] Examples of such a component (E-2) include: hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, undecyltrimethoxysilane, dodecyltrimethoxysilane, tetradecyltriethoxysilane, and preferably decyltrimethoxysilane.

[0090] 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. The reason is that if components (E-1) and (E-2) are used within the above mass ratio range, even if a large amount of component (D) is incorporated, the workability and filling property of the present composition can be improved.

[0091] In this composition, with respect to 100 parts by mass of the component (D), the compounding amount of the above-mentioned component (E) is in the range of 0.1 to 5.0 parts by mass, preferably in the range of 0.1 to 4.5 parts by mass, or 0.2 to 4.0 parts by mass. The reason is that if the compounding amount of the component (E) is above the lower limit of the above range, the surface of the component (D) is sufficiently treated. On the other hand, if the compounding amount of the component (E) is below the upper limit of the above range, the mechanical properties of the heat-conductive member obtained by curing this composition are good.

[0092] It should be noted that the component (E-1) is different from the component (E-2) and is a polysiloxane structure having a hydrolyzable silyl group at a single end of the molecular chain. Therefore, by using it in combination with the component (E-2) to treat the component (D), or after the surface treatment of the component (D) with the component (E-2), performing the surface treatment achieved by the component (E-1), even if a large amount of the component (D) is compounded, the operability and filling property of this composition can be improved, and furthermore, the thixotropy and vertical holding property can be improved.

[0093] The surface treatment method using the component (E-1) and the component (E-2) is not particularly limited, and a direct treatment method for the component (D), an integral blend method, a dry separation method, etc. can be used. In the direct treatment method, there are a dry method, a slurry method, a spray method, etc. As the integral blend method, there are a direct method, a masterbatch method, etc. Among them, the dry method, the slurry method, and the direct method are commonly used. The following method is preferred: the total amount of the component (E-1) and the component (E-2) or in multiple times is pre-mixed using a known mixing device, and the surface of the component (D) is treated.

[0094] In the present invention, the surface treatment method using the component (E-1) and the component (E-2) preferably adopts the direct treatment method. In particular, the following heating surface treatment method can be most preferably exemplified: mixing the component (D) with the component (E-1) and the component (E-2) and heating (basic heating). At this time, the temperature conditions and the stirring time can be designed according to the amount of the sample, and preferably in the range of 120 to 180 °C and 0.25 to 10 hours. In the mixing at room temperature conditions rather than the heating and stirring treatment, the treatment of the component (D) can also be carried out, and this treatment can also be selected.

[0095] As the above-mentioned mixing device, there is no particular limitation, and examples thereof include: single-axis or double-axis continuous mixers, two-roll mixers, Ross mixers, Hobart mixers, dental mixers, planetary mixers, kneaders, Henschel mixers, etc.

[0096] In this composition, it is preferable to incorporate (F) a hydrosilylation reaction inhibitor for extending its pot life and improving workability. 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; cycloalkenyl siloxanes 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.

[0097] The blending amount of such component (F) is not limited, and it is preferably in the range of 0.001 to 5% by mass of this composition.

[0098] For the purpose of improving the heat resistance of the heat-conductive member obtained by curing this composition, (G) a heat resistance imparting agent may also be incorporated in this composition. Examples of such 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 silanol, cerium fatty acid salts, reaction products of polyorganosiloxane and carboxylate of cerium, etc., and metal phthalocyanine compounds such as copper phthalocyanine compounds disclosed in Japanese Patent Application Laid-Open No. 2014-503680 are particularly preferred. Examples of such copper phthalocyanine compound include 29H, 31H-phthalocyanine(2-)-N29,N30,N31,N32 copper. Such phthalocyanine compounds are commercially available, and for example, Stan-tone (trademark) 40SP03 of PolyOne Corporation (Avon Lake, Ohio, USA) can be obtained.

[0099] The blending amount of such component (G) is not particularly limited, and it is preferably in the range of 0.01 to 5.0% by mass, in the range of 0.05 to 0.2% by mass, or in the range of 0.07 to 0.1% by mass of this composition.

[0100] In the present composition, other optional components can be incorporated within the scope that does not impair the object of the present invention. Examples of such optional components include: inorganic fillers such as fumed silica, wet silica, ground quartz, titanium oxide, magnesium carbonate, zinc oxide, iron oxide, diatomaceous earth, carbon black; polyorganosiloxanes that do not have a silicon atom-bonded hydrogen atom and a silicon atom-bonded alkenyl group; in addition, cold resistance imparting agents, flame retardancy imparting agents, pigments, dyes. Further, in the present composition, a known adhesion imparting agent; one or more antistatic agents composed of a cationic surfactant, an anionic surfactant, or a nonionic surfactant, etc.; dielectric fillers; conductive fillers; mold release components; thixotropy imparting agents; mildew inhibitors; organic solvents, etc. can be incorporated according to the desire.

[0101] <Method for manufacturing a thermally conductive silicone composition>

[0102] The preparation method of the present composition is not particularly limited. For example, it can be prepared by the following method: after previously mixing component (D) and component (E-1), then mixing component (E-2), after treating the surface of component (D) with component (E-1) and then with component (E-2), mixing the remaining components (A) to (C), component (G), and other optional components. Or it can be prepared by the following method: mixing component (D) and component (E-1) in component (A), then mixing component (E-2), after treating the surface of (D) with component (E-1) and then with component (E-2), mixing the remaining components (B), component (C), component (F), and other optional components. Or it can be prepared by the following method: after mixing component (A), component (B), component (E-1), and component (E-2), then mixing component (D) for treatment, and then mixing the remaining components (C), component (F), and other optional components. Further, it can also be prepared by the following method: when previously mixing component (D) and component (E-1) and then mixing component (E-2), after mixing a part of component (D) with component (E-1), then mixing component (E-2) with the remaining part of component (D).

[0103] The mixing method of each component is not particularly limited, and a conventionally known method can be used. It is preferably mixed by a commonly used mixing device. Examples of such a mixing device include: single-shaft or double-shaft continuous mixers, two-roll mixers, Ross mixers, Hobart mixers, dental mixers, planetary mixers, kneaders, Henschel mixers.

[0104] The present composition can be made into a single-component type (including one-liquid type) composition, and if necessary, it can also be made into a multi-component type (multi-liquid type, especially two-liquid type) composition.

[0105] The present composition has good workability and filling property in the uncured state. The viscosity of the present composition at 25°C is not limited, and the viscosity at a strain rate of 1.0 (1 / s) measured using a rheometer or the like is preferably in the range of 50 to 600 Pa·s.

[0106] The present composition is cured by a hydrosilylation reaction to form a heat-conductive member having high thermal conductivity. The temperature conditions for curing the present composition are not particularly limited, and are generally in the range of 20°C to 150°C, more preferably in the range of 20°C to 80°C. In addition, depending on the situation, it can also be cured at a high temperature in a short time, and in addition, it can also be cured at a low temperature such as room temperature for a long time (for example, several hours to several days).

[0107] <Heat-conductive member>

[0108] The heat-conductive member of the present invention is obtained by curing the above composition, is relatively soft, and preferably has a hardness that satisfies the range of 10 to 80 in an E-type hardness meter as specified in JIS K6249. The heat-conductive member having such a hardness can exhibit the characteristics of low elastic modulus and low stress, and can improve the adhesion and followability between the heat-generating member and the heat-dissipating member of the electronic component.

[0109] In addition, the present heat-conductive member has high thermal conductivity, for example, has a thermal conductivity of 7 W / mK or more. In order to cool the heat-generating component by heat conduction, such a present heat-conductive member is useful as a heat transfer material (heat-conductive member) interposed at the interface between the hot boundary surface of the heat-generating component and a heat-dissipating member such as a radiator or a circuit board, and a heat dissipation structure including it can be formed. Among them, the type, size, and detailed structure of the heat-generating component are not particularly limited. The present heat-conductive member has high thermal conductivity, excellent gap filling property for the member, high adhesion and followability to the heat-generating member having a fine uneven and narrow gap structure, and has flexibility, so it is suitable for the heat dissipation structure of electrical / electronic devices including unit secondary batteries.

[0110] Examples

[0111] The heat-conductive silicone composition and the heat-conductive member of the present invention will be described in detail by way of examples. It should be noted that the viscosity (mPa·s) in the examples is the value at 25°C measured using a rotational viscometer in accordance with JIS K7117-1. In addition, the appearance and viscosity of the heat-conductive silicone composition; and the thermal conductivity, hardness, and proportion of internal cracks of the heat-conductive member obtained by curing the composition were evaluated as follows.

[0112] <Appearance of heat-conductive silicone composition>

[0113] The state of the thermally conductive silicone composition at 25°C was observed visually.

[0114] <Viscosity of the thermally conductive silicone composition>

[0115] The viscosity (Pa·s) of the thermally conductive silicone composition at 25°C was measured using a RheoCompass MCR102 manufactured by Anton Paar. In terms of geometry, a flat plate with a diameter of 20 mm was used, the gap was set to 0.6 mm, and the shear rate was set to 1.0 (1 / s).

[0116] <Thermal conductivity of the thermally conductive member>

[0117] The thermally conductive silicone composition was filled into a mold with a height of 6 mm, a length of 50 mm, and a width of 30 mm, cured at 25°C for 1 day, and then taken out of the mold to produce a thermally conductive member. The thermal conductivity of this thermally conductive member was measured using a TPS-500 (hot disk method) manufactured by Kyoto Electronics Industry Co., Ltd.

[0118] <Hardness of the thermally conductive member>

[0119] The hardness of the thermally conductive member produced as described above was measured using an ASKER TYPE E hardness tester manufactured by ASKER.

[0120] <Ratio of internal cracks in the thermally conductive member>

[0121] The thermally conductive member produced as described above was treated in a hot air circulation oven at 150°C for 1 day. Then, it was taken out and cooled to room temperature. The thermally conductive member was cut horizontally at a height of 6 mm to confirm the internal state. The ratio of cracks observed in the cut surface was read in terms of area. The case where there were no cracks and the cut surface was uniform was set to 0%, and the case where cracks were observed throughout the entire cut surface was set to 100%.

[0122] <Preparation of the thermally conductive silicone composition>

[0123] The following components were uniformly mixed to obtain a thermally conductive silicone composition having the compositions shown in Tables 1 to 4. Note that a specific preparation method is described in Example 1. Note that the molar ratio of the silicon atom-bonded hydrogen atoms in component (B) to the alkenyl groups in component (A) in the thermally conductive silicone composition was set to 0.61.

[0124] The following components were used as component (A).

[0125] (a-1): Dimethylvinylsilanyloxy-terminated dimethylpolysiloxane with a viscosity of 60 mPa·s (vinyl content = 1.53 mass%).

[0126] The following components are used as component (B).

[0127] (b-1): Trimethylsilanyloxy-terminated methylhydrogensiloxane / dimethylsiloxane copolymer with a viscosity of 20 mPa·s and an average of two silicon-bonded hydrogen atoms in the molecule (content of silicon-bonded hydrogen atoms = 0.10 mass%).

[0128] (b-2): Trimethylsilanyloxy-terminated methylhydrogensiloxane / dimethylsiloxane copolymer with a viscosity of 5 mPa·s and an average of five silicon-bonded hydrogen atoms in the molecule (content of silicon-bonded hydrogen atoms = 0.75 mass%).

[0129] The following components are used as component (C).

[0130] (c-1): A 1,3-divinyltetramethyldisiloxane solution of a 1,3-divinyltetramethyldisiloxane complex of platinum with a platinum concentration of 0.6 mass%.

[0131] The following components are used as component (D-1) within component (D).

[0132] (d-1-1): Polyhedral spherical α-alumina powder with an average particle size of 0.5 μm (AA04 from Sumitomo Chemical).

[0133] (d-1-2): Crushed alumina powder with an average particle size of 0.4 μm (AES-12 from Sumitomo Chemical).

[0134] (d-1-3): Spherical fused and solidified alumina powder with an average particle size of 2.5 μm (AZ2-75 from Micron).

[0135] (d-1-4): Polyhedral spherical α-alumina powder with an average particle size of 2 μm (AA2 from Sumitomo Chemical).

[0136] The following components are used as component (D-2) within component (D).

[0137] (d-2-1): Amorphous aluminum nitride powder with an average particle size of 27 μm (TFZ-S30P from Toyo Aluminium).

[0138] (d-2-2): Amorphous aluminum nitride powder with an average particle size of 72 μm (AN-HF70LG-HTZ by combustion synthesis).

[0139] (d-2-3): Spherical aluminum nitride powder with an average particle size of 32 μm (AIN3001 of Showa Denko).

[0140] The following components were used for comparison of component (D-2) within component (D).

[0141] (d-2-4): Amorphous aluminum nitride powder with an average particle size of 19 μm (TFZ-S20P of Toyo Aluminium).

[0142] (d-2-5): Amorphous aluminum nitride powder with an average particle size of 1.4 μm (TFZ-N01P of Toyo Aluminium).

[0143] The following components were used as component (D-3) within component (D).

[0144] (d-3-1): Spherical fused and solidified alumina powder with an average particle size of 83 μm (AY90-150 of Micron).

[0145] (d-3-2): Spherical fused and solidified alumina powder with an average particle size of 95 μm (DAM-90 of Denka).

[0146] (d-3-3): Spherical fused and solidified alumina powder with an average particle size of 121 μm (DAM-120 of Denka).

[0147] (d-3-4): Spherical magnesia powder with an average particle size of 96 μm (DMG-120 of Denka).

[0148] The following components were used for comparison of component (D-3) within component (D).

[0149] (d-3-5): Spherical fused and solidified alumina powder with an average particle size of 37 μm (AL35-125 of Micron).

[0150] The following components were used as component (E).

[0151] (e-1): Formula:

[0152] (CH 3 ) 3 SiO[(CH 3 ) 2 SiO] 30 Si(OCH 3 ) 3

[0153] The shown polyorganosiloxane.

[0154] (e-2): Decyltrimethoxysilane.

[0155] The following components were used as component (F).

[0156] (f-1): 2-Phenyl-3-butyn-2-ol.

[0157] Use the following components as component (G).

[0158] (g-1): 29H, 31H-Phthalocyanine(2-)-N29,N30,N31,N32 copper.

[0159] <Example 1>

[0160] Put 100 parts by mass of component (a-1), 30.4 parts by mass of component (b-1), 45.7 parts by mass of component (e-1), 7.1 parts by mass of component (e-2), 5.36 parts by mass of component (g-1), 518 parts by mass of component (d-1-1), and 714 parts by mass of component (d-1-3) into a 300 ml plastic container, and mix them for 1 minute at a rotational speed of 1200 rpm using a THINKY Planetary Vacuum Mixer. Then, put 893 parts by mass of component (d-2-1), mix for 1 minute at a rotational speed of 1200 rpm, and further put 1250 parts by mass of component (d-3-1), and mix for 1 minute at a rotational speed of 1200 rpm. Then, put 0.022 parts by mass of component (f-1) and 0.54 parts by mass of component (b-2), and mix for 30 seconds at a rotational speed of 1200 rpm. Then, cool to room temperature, put 2.68 parts by mass of component (c-1), and mix with a spatula for 3 minutes to prepare a thermally conductive silicone composition.

[0161] Measure the viscosity at 25°C of the thermally conductive silicone composition just after preparation. Then, cure it at 25°C for 1 day, and measure the thermal conductivity and hardness of the obtained thermally conductive member. Then, after treating the thermally conductive member in a hot air circulation oven at 150°C for 1 day, measure the proportion of internal cracks, and show the results in Table 1.

[0162] <Example 2>

[0163] In Example 1, 1250 parts by mass of component (d-3-2) was added instead of component (d-3-1), and a thermally conductive silicone composition was prepared in the same manner as in Example 1. The 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.

[0164] <Example 3>

[0165] In Example 1, 1250 parts by mass of the compounding ingredient (d-3-3) was used to replace the ingredient (d-3-1). Other than this, a thermally conductive silicone composition was prepared in the same manner as in Example 1. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0166] <Example 4>

[0167] In Example 1, the compounding amount of the ingredient (e-1) was set to 56.4 parts by mass, and 1239 parts by mass of the compounding ingredient (d-3-4) was used to replace the ingredient (d-3-1). Other than this, a thermally conductive silicone composition was prepared in the same manner as in Example 1. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0168] <Example 5>

[0169] In Example 4, 893 parts by mass of the compounding ingredient (d-2-2) was used to replace the ingredient (d-2-1). Other than this, a thermally conductive silicone composition was prepared in the same manner as in Example 4. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0170] [Table 1]

[0171]

[0172]

[0173] <Example 6>

[0174] In Example 2, 518 parts by mass of the compounding ingredient (d-1-2) was used to replace the ingredient (d-1-1). Other than this, a thermally conductive silicone composition was prepared in the same manner as in Example 2. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0175] <Example 7>

[0176] In Example 2, 714 parts by mass of the compounding ingredient (d-1-4) was used to replace the ingredient (d-1-3). Other than this, a thermally conductive silicone composition was prepared in the same manner as in Example 2. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0177] <Example 8>

[0178] In Example 7, the compounding quantity of component (d-2-1) was set to 357 parts by mass, and the compounding quantity of component (d-3-2) was set to 1786 parts by mass. Except for this, a thermally conductive silicone composition was obtained in the same manner as in Example 7. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0179] <Example 9>

[0180] In Example 7, the compounding quantity of component (d-2-1) was set to 179 parts by mass, and the compounding quantity of component (d-3-2) was set to 1964 parts by mass. Except for this, a thermally conductive silicone composition was prepared in the same manner as in Example 7. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0181] <Example 10>

[0182] In Example 7, 893 parts by mass of component (d-2-3) was compounded in place of component (d-2-1). Except for this, a thermally conductive silicone composition was prepared in the same manner as in Example 7. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[0183] [Table 2]

[0184]

[0185]

[0186] <Comparative Example 1>

[0187] In Example 2, 893 parts by mass of component (d-2-4) was compounded in place of component (d-2-1). Except for this, a thermally conductive silicone composition was prepared in the same manner as in Example 2. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0188] <Comparative Example 2>

[0189] In Example 2, the compounding quantity of component (d-2-1) was set to 1250 parts by mass, and the compounding quantity of component (d-3-2) was set to 893 parts by mass. Except for this, a thermally conductive silicone composition was prepared in the same manner as in Example 2. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0190] <Comparative Example 3>

[0191] In Example 1, the compounding amount of component (d-2-1) was set to 714 parts by mass, component (d-3-1) was not compounded, and 1071 parts by mass of component (d-2-2) was compounded instead. Except for this, a thermally conductive silicone composition was prepared in the same manner as in Example 1. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0192] <Comparative Example 4>

[0193] In Example 1, component (d-3-1) was not compounded, and 1250 parts by mass of component (d-2-2) was compounded instead. Except for this, a thermally conductive silicone composition was prepared in the same manner as in Example 1. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0194] <Comparative Example 5>

[0195] In Example 2, component (d-1-3) was not compounded, and 714 parts by mass of component (d-2-5) was compounded instead. Except for this, a thermally conductive silicone composition was prepared in the same manner as in Example 2. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0196] [Table 3]

[0197]

[0198] <Comparative Example 6>

[0199] In Example 2, components (d-1-1) and (d-1-3) were not compounded, and 536 parts by mass of component (d-2-5) was compounded instead. The compounding amount of component (d-2-1) was set to 1071 parts by mass. Except for this, an attempt was made to prepare a thermally conductive silicone composition in the same manner as in Example 2, but the obtained thermally conductive silicone composition was in powder form.

[0200] <Comparative Example 7>

[0201] In Example 1, component (d-2-1) was not compounded, and 893 parts by mass of component (d-3-5) was compounded instead. Except for this, a thermally conductive silicone composition was prepared in the same manner as in Example 1. The thermally conductive silicone composition and the thermally conductive member obtained by curing the same were evaluated in the same manner as in Example 1, and the results are shown in Table 4.

[0202] [Table 4]

[0203]

[0204]

[0205] From the results of Examples 1 to 10, it can be seen that when aluminum nitride powder with an average particle size of 20 μm or more and less than 80 μm is in the range of 5 to 30% by volume of the thermally conductive silicone composition, the present composition exhibits a high thermal conductivity of 7 W / m·K or more, and the thermally conductive member obtained by curing the uniform paste before curing has the generation of internal cracks suppressed to 20% or less of the whole even under high temperature conditions of 150°C.

[0206] On the other hand, in Comparative Example 1, it can be seen that aluminum nitride powder with an average particle size less than 20 μm was incorporated, so that the obtained thermally conductive member had more than 50% internal cracks at 150°C. In addition, in Comparative Examples 2 to 5, it can be seen that when the aluminum nitride powder was 30% by volume or more of the whole thermally conductive silicone composition, the obtained thermally conductive member had more than 50% internal cracks by heating at 150°C. In addition, in Comparative Example 6, it can be seen that when aluminum nitride powder with an average particle size less than 20 μm was incorporated 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 incorporated, a uniform paste could not be obtained. Moreover, in Comparative Example 7, it can be seen that when aluminum nitride powder with an average particle size of 20 μm or more and less than 80 μm was not incorporated, the thermal conductivity of the obtained thermally conductive member could not be 7 W / m·K or more.

[0207] Industrial applicability

[0208] The thermally conductive silicone composition of the present invention is cured to form a thermally conductive member having high thermal conductivity, for example, a thermal conductivity of 7 W / m·K or more, and suppressing the generation of internal cracks at high temperatures. Therefore, it is useful as a heat transfer material (thermally conductive member) for efficiently transferring heat from a heat-generating electronic component to a heat sink. In addition, the thermally conductive member of the present invention has flexibility, excellent gap filling properties, and high adhesion and followability to a heat-generating member having a fine uneven and narrow gap structure. Therefore, it is suitable as a thermally conductive member for an electric / electronic device including secondary batteries.

Claims

1. A thermally conductive silicone composition, the thermally conductive silicone composition having at least the following composition: (A) A polyorganosiloxane having an average of at least two alkenyl groups in one molecule and a viscosity of 10 to 100,000 mPa·s at 25°C; (B) An organohydrogenpolysiloxane having an average of at least two silicon-bonded hydrogen atoms in one molecule: an amount of 0.2 to 5 moles of silicon-bonded hydrogen atoms in component (B) relative to 1 mole of alkenyl groups in component (A); (C) A catalytic amount of a catalyst for hydrosilylation reaction; (D) A thermally conductive filler composed 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 alumina powder and / or spherical magnesia 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 this composition, and the content of component (D-2) is 5 to 30% by volume of this composition; and (E) A surface treatment agent or wetting agent composed of the following components (E-1) and (E-2), with a mass ratio of component (E-1) to component (E-2) of 95:5 to 5:95: (E-1) General formula: R 1 (R 2 2 SiO) m SiR 2 2 -R 3 -SiR 2 a (OR 4 ) (3-a) The polyorganosiloxane shown, wherein 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 is independently an alkyl group having 1 to 6 carbon atoms, R 3 is an oxygen atom or an alkylene group having 2 to 6 carbon atoms, 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; (E-2) General formula: R 5 b R 2 c Si(OR 4 ) (4-b-c) The alkoxysilane or its hydrolytic condensate shown, in the formula, R 2 and R 4 are the same as the said R 2 and R 4 , R 5 is an alkyl group with 6 to 18 carbon atoms, b is 1 or 2, c is 0 or 1, and b + c is 1 or 2: The amount of (E) is 0.1 to 5.0 parts by mass relative to 100 parts by mass of component (D).

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

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

4. The thermally conductive silicone composition according to claim 1, wherein, It further contains 0.001 to 5% by mass of (F) a hydrosilylation reaction inhibitor of this composition.

5. The thermally conductive silicone composition according to claim 1, wherein, It further contains 0.01 to 5.0% by mass of (G) a heat resistance imparting agent of this composition.

6. The thermally conductive silicone composition according to any one of claims 1 to 4, wherein, The thermally conductive silicone composition is cured to form a thermally conductive member having a thermal conductivity of 7 W / m·K or more.

7. A thermally conductive member, which is formed by curing the thermally conductive silicone composition according to any one of claims 1 to 6.

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