Heat-curable silicone rubber composition and cured product thereof

Abstract

The present invention provides a heat-curable silicone rubber composition to be cured by hydrosilation reactions and having outstanding physical properties, especially a high tear strength, said composition comprising (A) a polydiorganosiloxane having at least two unsaturated aliphatic hydrocarbon groups and represented by the general formula (1): R.sub.a.sup.1 SiO.sub.(4-a)/2 ( 1) wherein R.sup.1 represents a substituted or unsubstituted monovalent hydrocarbon group containing 0.01 to 15 mole % of an unsaturated aliphatic hydrocarbon group, a is a positive number of from 1.95 to 2.05. (B) a polyorganohydrogensiloxane having at least three hydrogen atoms directly bonded to silicon atom in a molecule, (C) silica filler having a specific surface area of at least 50 m.sup.2 /g, and (D) an addition reaction catalyst, (E) water, and preferably (F) an organosilane represented by the general formula: R.sub.m.sup.2 Si(OR).sub.4-m wherein R.sup.2 represents a substituted or unsubstituted monovalent hydrocarbon group, R represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and m is 0, 1 or 2, or a polysiloxane having a polymerization degree of 100 or less obtained by hydrolysis thereof.

Dependencies are inferred from the claim text.