One-component RTV silicone rubber compositions with good self-bonding properties to acrylate plastics

Claim 1

A stable, one-package substantially anhydrous and substantially acid-free, room temperature vulcanizable organopolysiloxane composition stable under ambient conditions in the substantial absence of moisture over an extended period of time and convertible to a tack-free elastomer having superior adhesion to polyacrylate plastic comprising: (i) 100 parts by weight base alkoxy-terminated diorganopolysiloxane comprising up to 50 parts by weight monoalkoxy-terminated diorganopolysiloxane and at least 50 parts by weight polyalkoxy-terminated diorganopolysiloxane; and (ii) a pre-reacted catalyst mixture comprising the reaction product of (1) 0.001 to 10 parts by weight per 100 parts by weight of (i) of a tin condensation catalyst, (2) 0.5 to 10 parts by weight per 100 parts by weight of (i) of a scavenger for hydroxy functional groups which is a silicon-nitrogen compound selected from the group consisting of (A) a silicon-nitrogen compound having the formula ##STR26## where Y is selected from R"' and (R") 2 N and (B) a silicon-nitrogen polymer comprising (i) from 3 to 100 mole percent chemically combined structural units of the formula ##STR27## and (ii) from 0 to 97 mole percent chemically combined structural units represented by the formula (R"').sub.c SiO.sub.(4-c)/2 where the silicon atoms of said compound are joined to each other by a member selected from an SiOSi linkage and a SiNR"Si linkage, the free valences of said silicon atoms other than those joined to oxygen to form a siloxy unit or to nitrogen to form a silazy unit are joined to a member selected from an R"' radical and an (R") 2 N radical, where the ratio of the sum of said R"' radicals and said (R") 2 N radicals to the silicon atoms of said polymer has a value of 1.5 to 3 inclusive, R" and R"' are independently selected from the group consisting of hydrogen, monovalent hydrocarbon radicals and monovalent fluoroalkyl radicals, and c is a whole number equal to 0 to 3 inclusive, and (3) 0.1 to 10 parts by weight per 100 parts by weight of (i) of an adhesion promoter having the formula ##STR28## where R 10 and R 11 are C.sub.(1-8) monovalent hydrocarbon radicals, t varies from 0 to 2, R 12 is a C.sub.(2-12) divalent hydrocarbon radical, R 13 and R 14 are selected from the group consisting of hydrogen, amine radicals, C.sub.(1-8) aminofunctional alkyl radicals and C.sub.(1-8) monovalent hydrocarbon radicals, and mixtures thereof.