Extrudable, curable polyorganosiloxane compositions

Claim 1

An extrudable, curable silicone elastomer composition exhibiting a viscosity of at least 100 Pa·s at 25° C. and comprising a product obtained by mixing (A) 100 parts by weight of a liquid triorganosiloxy-endblocked polydimethylsiloxane wherein the triorganosiloxy units are dimethylvinylsiloxy or methylphenylvinylsiloxy and the polydimethylsiloxane exhibits a viscosity of from 1 to 100 Pa·s at 25° C.; (B) from 10 to 85 parts by weight of a reinforcing silica filler having a surface area of at least 50 m 2 /g, said filler having been reacted with a liquid or solubilized treating agent wherein at least a portion of said treating agent is a liquid, hydroxyl endblocked polyorganosiloxane wherein at least 50% of the silicon atoms are bonded to a fluorine-substituted hydrocarbon radical; (C) a liquid methylhydrogensiloxane in an amount sufficient to provide from 1 to 3 silicon-bonded hydrogen atoms per vinyl radical present in said curable elastomer composition, said methylhydrogensiloxane having an average of at least three silicon-bonded hydrogen atoms per molecule and consisting essentially of units selected from the group consisting of methylhydrogensiloxane, dimethylsiloxane, dimethylhydrogensiloxy, trimethylsiloxy and SiO 4/2 units; and (D) a platinum-containing catalyst in sufficient amount to provide at least 0.1 part by weight of platinum per million parts by weight of said triorganosiloxy endblocked polydimethylsiloxane.