Heat conductive elastomer composition
The object of the present invention is to provide a heat conductive elastomer composite useful as the heat radiating member of electric parts or electronic parts, or the like. In the present invention, an aluminum hydroxide having a surface covered with an organic coupling agent and/or an inactivated magnesium oxide, being a magnesia clinker having a surface covered with an inorganic substance and/or an organic substance, is (are) combined as heat conductive filler(s) in an elastomer composite mainly composed of a styrenic elastomer.
1. A heat conductive elastomer composite comprising 100 volume parts of a mixture containing 100 parts by mass of a hydrogenated thermoplastic styrenic elastomer (E), 100 to 600 parts by mass of a softener for rubber having a kinematic viscosity of between 50 and 500 centistokes (cSt) at 40° C., and 1 to 100 parts by mass of an olefinic resin, with 40 to 400 volume parts of a covered magnesium oxide as a heat conductive filler being added thereto, wherein said hydrogenated thermoplastic styrenic elastomer (E) is a hydrogenated product of block copolymer (Z) consisting of block unit(s) (S) of a polymer of styrenic monomer and block unit(s) (B) of a polymer of a conjugative diene compound, said elastomer (E) having a weight-average molecular weight in the range of between 150,000 and 500,000, and a styrenic monomer content in the range of between 20 and 50% by mass, said covered magnesium oxide being a magnesia clinker having a surface covered with an inorganic substance and/or an organic substance, with said magnesia clinker being an inactivated magnesium oxide.
2. A heat conductive elastomer composite in accordance with claim 1 , wherein said magnesium oxide being a magnesia clinker covered with an inorganic substance and/or an organic substance have (has) a water-absorption rate by a humidity test of below 1.5% by mass, and a new Mohs hardness of below 10.
3. A heat conductive elastomer composite in accordance with claim 1 , wherein the deflection temperature under load of said olefinic resin is in the range of between 80 and 140° C.
4. A heat conductive elastomer composite in accordance with claim 2 , wherein the deflection temperature under load of said olefinic resin is in the range of between 80 and 140° C.