A two-agent curable heat conductive grease composition including a first agent and a second agent, wherein the first agent contains 100 parts by weight of a liquid resin (A-1), 140 parts by weight to 560 parts by weight of metal aluminum (B-1) having an average particle size of 15 to 100 μm, one or more heat conductive fillers (C-1) selected from the group consisting of aluminum oxide, aluminum nitride, and boron nitride and having an average particle size within a range of 0.3 to 10 μm, and a hydrosilylation reaction catalyst (D-1); the second agent contains 100 parts by weight of a liquid resin (A-2), 140 parts by weight to 560 parts by weight of metal aluminum (B-2) having an average particle size of 15 to 100 μm, and one or more heat conductive fillers (C-2) selected from the group consisting of aluminum oxide, aluminum nitride, and boron nitride and having an average particle size within a range of 0.3 to 10 μm, and at least one of the heat conductive filler (C-1) or the heat conductive filler (C-2) includes a first heat conductive filler (C-1-1) or a first heat conductive filler (C-2-1) being at least one or more selected from the group consisting of aluminum oxide, aluminum nitride, and boron nitride and having an average particle size of 0.3 to 1.5 μm.

A thermally conductive polysiloxane composition includes (A) a thermally conductive filler, (B) a polyorganosiloxane resin including at least one polysiloxane having one curable functional group in the molecule thereof, and (C) a siloxane compound having an alkoxysilyl group and a linear siloxane structure.

A thermally conductive sheet having a binder resin, a first thermally conductive filler, and a second thermally conductive filler, wherein the first thermally conductive filler and the second thermally conductive filler are dispersed in the binder resin, and the specific permittivity and the thermal conductivity are different in the thickness direction B and the surface direction A of the thermally conductive sheet. A thermally conductive sheet includes step A of preparing a resin composition for forming a thermally conductive sheet by dispersing a first thermally conductive filler and a second thermally conductive filler in a binder resin, step B of forming a molded block from the resin composition for forming a thermally conductive sheet, and step C of slicing the molded block into a sheet and obtaining a thermally conductive sheet having different relative permittivity and thermal conductivity in the thickness direction and the surface direction.

An aluminum nitride particle including at least a first truncated six-sided pyramid (1-a) and a second truncated six-sided pyramid (1-b), the aluminum nitride particle having a shape such that a lower base (3) of the first truncated six-sided pyramid (1-a) and a lower base (3) of the second truncated six-sided pyramid (1-b) face each other, the first truncated six-sided pyramid (1-a) and the second truncated six-sided pyramid (1-b) each having an upper base (2) with an area Si of not less than 60 μm.sup.2 and not more than 4800 μm.sup.2, and each having a ratio (S1/S2) of the area Si to an area S2 of the lower base (3) being not less than 0.5 and less than 1, the first truncated six-sided pyramid (1-a) and the second truncated six-sided pyramid (1-b) respectively having a height h1 and a height h2 each being not less than 5 μm and not more than 20 μm.

A thermally conductive composition contains a base polymer, an adhesive polymer, and thermally conductive particles. A thermal conductivity of the thermally conductive composition is 0.3 W/m.Math.K or more. The thermally conductive particles include inorganic particles (a) with a specific surface area of 1 m.sup.2/g or less. The inorganic particles (a) are coated with the adhesive polymer. The production method includes a first mixing process of mixing the adhesive polymer and the inorganic particles (a) with a specific surface area of 1 m.sup.2/g or less so that the inorganic particles (a) are coated with the adhesive polymer, a second mixing process of adding and mixing the base polymer; and a curing process. Thus, the present invention provides a thermally conductive composition that has high thermal conductive properties, a high compression repulsive force, and less interfacial debonding resulting from stress, and a method for producing the thermally conductive composition.

An aluminum nitride particle including: a plurality of planes randomly arranged in a surface of the particle, the plurality of planes forming an obtuse ridge part or an obtuse valley part in the surface of the particle, the plurality of planes being observable in a scanning electron micrograph with 500 times magnification; wherein the particle has a longer diameter L of 20 to 200 μm; a ratio L/D of the longer diameter L (unit: μm) to a shorter diameter D (unit: μm) of the particle is 1 to 1.25; and the plurality of planes comprise a first plane, wherein an area S (unit: μm.sup.2) of the first plane satisfies S/L≥1.0 μm.

A non-curable thermal-conductive silicone composition contains essential components of: (A) an organopolysiloxane having a kinematic viscosity at 25° C. of 1,000,000 mm.sup.2/s or more in an amount of 5 to 20 mass % relative to a sum of the component (A) and a component (B); (B) a hydrolysable organopolysiloxane compound shown by the following general formula (1) in an amount of 80 to 95 mass % relative to the sum of the components (A) and (B); and (C) a heat conductive filler in an amount of 10 to 95 mass % relative to a total amount of the composition. A mixture of the components (A) and (B) has a molecular weight distribution Mw/Mn of 10 or more. R.sup.1 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms optionally having a substituent. “m” represents an integer of 5 to 100.

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A non-curable thermal-conductive silicone composition contains essential components of: (A) an organopolysiloxane having a kinematic viscosity at 25° C. of 1,000,000 mm.sup.2/s or more in an amount of 5 to 20 mass % relative to a sum of the component (A) and a component (B); (B) a hydrolysable organopolysiloxane compound shown by the following general formula (1) in an amount of 80 to 95 mass % relative to the sum of the components (A) and (B); and (C) a heat conductive filler in an amount of 10 to 95 mass % relative to a total amount of the composition. A mixture of the components (A) and (B) has a molecular weight distribution Mw/Mn of 10 or more. R.sup.1 represents a monovalent hydrocarbon group having 1 to 10 carbon atoms optionally having a substituent. “m” represents an integer of 5 to 100.

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Provided is a resin composition that has a low viscosity when in the state of a composition, and provides a cured product having a high thermal conductivity, a high resin strength and a high adhesive force. The composition is a thermally conductive resin composition containing: (A) 100 parts by mass of a heat-curable resin containing at least one kind selected from an epoxy resin, a cyclic imide compound and a cyanate ester resin; and (B) a thermally conductive filler that has a thermal conductivity of not smaller than 10 W/m.Math.K, and is in an amount of 100 to 3,000 parts by mass per 100 parts by mass of the component (A), wherein the component (B) contains therein 40 to 85% by mass of a thermally conductive filler (B1) that has an average particle size of 35 to 200 μm and a specific surface area of not larger than 0.3 mm.sup.2/g.

An insulating filler composed of a mixed powder in which a hydrophobic fumed oxide powder having an average primary particle size D.sub.1, which is smaller than an average primary particle size D.sub.2, is adhered to the surface of a magnesium oxide powder and/or a nitride-based inorganic powder having the average primary particle size D.sub.2, wherein: the ratio D.sub.1/D.sub.2 of the average primary particle size D.sub.1 to the average primary particle size D.sub.2 is 6×10.sup.−5 to 3×10.sup.−3; the volume resistivity of the mixed powder is 1×10.sup.11 Ω.Math.m or more; and the content ratio of the hydrophobic fumed oxide powder in the mixed powder is 5-30 mass %. Also provided is an insulating material in which the above-mentioned insulating filler is contained in a resin molded body.