GB905394A - Organopolysiloxane compositions - Google Patents

Abstract

A silicone rubber-forming composition comprises (a) an essentially linear diorganopolysilioxane in which at least 50% of the organic radicals are methyl, the remaining radicals (other than terminal which may be H, OH, OR or R) being hydrocarbon or halogenated hydrocarbon (saturated, unsaturated or cyclo-aliphatic or aromatic), and (b) boron nitride, in amount, e.g. of 10 to 100 parts by weight per 100 parts of the siloxane. The compositions may contain fillers, e.g. TiO2, ZnO, SiO2 (aerogels, xerogels and fume), diatomaceous earth, C black, argillaceous earth, glass fibres and powder, clay, cork, iron oxide, P.T.F.E., polychlorotrifluoroethylene, organic resins and copper phthalocyanine, and conventional additives. Vulcanization can be effected in known manner, e.g. by heating with organic peroxides, by high energy radiation, or by an organic silicate or siloxane containing Si-H and a metal carboxylate as disclosed in Specification 841,825. In a typical Example (1) a hydroxy-terminated dimethylsiloxane gum, boron nitride and tertiary butyl perbenzoate were mixed in a three-roll mill, sheeted and press vulcanized at 150 DEG C. to yield a self-adhering rubber sheet. Uses: as self-adhering electrical insulation, joint sealants, packing rings and laminating materials; as an interlayer between conventional silicone rubber and metal; for repairing damaged silicone rubber. Specifications 782,320 and 859,284 also are referred to.