Polyorganosiloxane compositions useful for preparing unsupported extruded profiles

Claim 1

A pumpable organosiloxane composition having the consistency of petrolatum at 25° C. and the capability of being extruded as unsupported profiles that retain their initial shape during curing at temperatures of at least 70° C., said composition comprising the product obtained by blending (A) a triorganosiloxy-endblocked polydiorganosiloxane containing at least two vinyl radicals per molecule and exhibiting a viscosity of 0.1 to 100 Pa.s at 25° C., wherein at least 50% of the silicon-bonded hydrocarbon groups are methyl; (B) an organohydrogensiloxane containing at least two silicon-bonded hydrogen atoms per molecule, where said hydrogen atoms are bonded to different silicon atoms and the amount of (B) is sufficient to cure said composition, with the proviso that the sum of the average number of vinyl radicals per molecule of (A) and the average number of silicon-bonded hydrogen atoms per molecule of (B) is at least five; (C) a platinum-containing hydrosilation catalyst in an amount sufficient to promote curing of said composition; (D) optionally, an amount of catalyst inhibitor sufficient to render (C) inactive at temperatures up to 70° C.; (E) a finely divided silica filler in an amount sufficient to impart the consistency of petrolatum to said composition; and (F) a silica treating agent in an amount sufficient to inhibit crepe hardening of said composition, said composition being characterized by the presence of a silica treating agent wherein from 20 to 100 percent by weight of said treating agent is immiscible with said polydiorganosiloxane (A) at 25° C.