Silicone rubber composition for formed-in-place gaskets

Claim 1

A silicone rubber composition, comprising (A) 100 parts by weight of a mixture comprising (a) 5 to 95 weight% of an alkoxy-substituted polyorganosiloxane having a viscosity at 25°C of 20 to 1,000,000 centipoise (mPa.s) and containing an average of at least two silicon-bonded alkoxy groups per molecule; and (b) 95 to 5 weight% of an alkenyl-substituted polyorganosiloxane having a viscosity at 25°C of 20 to 1,000,000 (mPa.s ) centipoise and containing an average of at least two silicon-bonded lower alkenyl groups per molecule; and (B) a polyorganosiloxane containing an average of least two silicon-bonded hydrogen atoms per molecule, in a quantity that affords a value of 0.3 to 10 for the molar ratio of silicon-bonded hydrogen atoms to silicon-bonded lower alkenyl groups in component (b), (C) 0.01 to 20 parts by weight of an organosilicon compound selected from the group consisting of alkoxysilanes having the general formula R 1 a Si(OR 2 ) 4-a and partial hydrolysis condensates thereof; wherein each R 1 is selected from the group consisting of monovalent hydrocarbon groups, epoxy-functional organic groups, and acrylic-functional organic groups, R 2 is alkyl or alkoxyalkyl, and a is 0, 1, or 2; (D) 0.01 to 20 parts by weight of a condensation reaction catalyst; and (E) a catalytic quantity of a platinum catalyst.