Curable organopolysiloxane compositions with improved adhesion

Claim 1

An organopolysiloxane composition comprising (A) a polyorganosiloxane having per molecule on average at least two units of the general formula Q a Q'SiO 3-a/2 any remaining units having the general formula Q b SiO 4-b/2 wherein Q is selected from the group consisting of a monovalent hydrocarbon and a monovalent substituted hydrocarbon group having no more than 8 carbon atoms, Q' denotes an organic group having olefinic unsaturation, a has a value of from 1 to 2 and b has a value of from 0 to 3, and at least 80% of the Q groups are methyl groups, (B) an organohydrogen polysiloxane having on average at least two silicon-bonded hydrogen atoms per molecule, any remaining substituents of the silicon atoms being a monovalent hydrocarbon group having no more than 8 carbon atoms, at least 50% of said remaining substituents being methyl groups, (C) a catalyst selected from, the group consisting of metals from group VIII of the Periodic Table and compounds of said metals between (A) and (B), and (D) an organosilane having the general formula ##STR8## where R is a monovalent hydrocarbon group, having no more than 8 carbon atoms and which may contain ether oxygen atoms, R' is chosen from the group consisting of a hydrocarbon and hydrocarbonoxy groups containing from 2 to 5 carbon atoms and aliphatic unsaturation, and R" represents an epoxy-substituted group selected from monovalent hydrocarbon groups, hydrocarbonoxy groups, halogenated hydrocarbonoxy groups, hydrocarbon groups containing oxygen in the form of a hydroxyl group, a hydrocarbonoxy group containing oxygen in the form of an ether linkage or hydrocarbonoxy groups containing oxygen in the form of a hydroxyl group.