Thermally conductive filler, thermally-conductive composite material, wire harness, and method for manufacturing thermally conductive filler
A thermally conductive filler can exhibit high thermal conductive properties with a reduced specific gravity, a thermally-conductive composite material and a wire harness contains such a thermally conductive filler, and a method manufactures a thermally conductive filler. A thermally conductive filler contains base particles and a coating layer coating the particles, the coating layer contains a gel-like substance that is bonded to the surfaces of the base particles through chemical bonding and coats the surfaces of the base particles, and a thermally-conductive substance that is dispersed in the layer of the gel-like substance and has a higher thermal conductivity and a larger specific gravity than the base particles and the gel-like substance. Also, a thermally-conductive composite material is obtained by dispersing the thermally conductive filler in a matrix material. Furthermore, a wire harness contains the thermally-conductive composite material.
1 . A thermally conductive filler comprising:
a base particle; and
a coating layer coating the base particle,
wherein the coating layer comprises:
a gelatinous substance which coats a surface of the base particle and bonded to the surface of the base particle through chemical bonding; and
a thermally-conductive substance that is dispersed inside the gelatinous substance and has a higher thermal conductivity and higher specific gravity than the base particle and the gelatinous substance.
2 . The thermally conductive filler according to claim 1 ,
wherein the base particle is hollow.
3 . The thermally conductive filler according to claim 2 ,
wherein the base particle is a hollow glass particle and has, on its surface, a functional group capable of forming a chemical bond with a functional group of the gelatinous substance.
4 . The thermally conductive filler according to claim 1 ,
wherein the gelatinous substance has a carbonyl group,
the base particle has a basic group on its surface, and
the gelatinous substance is bonded to the surface of the base particle through chemical bonding between the carbonyl group and the basic group.
5 . The thermally conductive filler according to claim 4 ,
wherein the gelatinous substance has an organic polymer having a carboxyl group as the carbonyl group.
6 . The thermally conductive filler according to claim 4 ,
wherein the base particle has, on its surface, a primary amino group as the basic group.
7 . The thermally conductive filler according to claim 1 ,
wherein the thermally-conductive substance is constituted as a particle having shape anisotropy.
8 . The thermally conductive filler according to claim 7 ,
wherein the thermally-conductive substance is a carbon fiber.
9 . The thermally conductive filler according to claim 1 , having a specific gravity of 1.8 or lower.
10 . A thermally-conductive composite material comprising:
the thermally conductive filler according to claim 1 ; and
a matrix material,
wherein the thermally conductive filler is dispersed in the matrix material.
11 . The thermally-conductive composite material according to claim 10 ,
wherein the matrix material comprises an organic polymer.
12 . The thermally-conductive composite material according to claim 10 , having a specific gravity of 1.4 or lower.
13 . The thermally-conductive composite material according to claim 10 , having a thermal conductivity of 0.9 W/(m·K) or higher at room temperature.
14 . A wire harness, comprising
the thermally-conductive composite material according to claim 10 .
15 . A method for manufacturing a thermally conductive filler capable of being used to manufacture the thermally conductive filler according to claim 1 , the method comprising:
a gel preparation step of preparing the gelatinous substance with the thermally-conductive substance dispersed therein; and
a coating step of bonding the gelatinous substance, which has been prepared such that the thermally-conductive substance is dispersed therein in the gel preparation step, to the surfaces of the base particles through chemical bonding.
16 . The thermally conductive filler according to claim 1 , wherein the base particle is a hollow glass particle and has, on its surface, a functional group which forms a chemical bond with a functional group of the gelatinous substance.
17 . The thermally conductive filler according to claim 1 , wherein the chemical bonding is an ionic bond, a hydrogen bond, or a covalent bond.
18 . The thermally conductive filler according to claim 1 , wherein the gelatinous substance has a network-type structure formed through a chemical bonding.