Curable organopolysiloxane compositions

Claim 1

In an organopolysiloxane composition comprising (A) a polyorganosiloxane having an average of at least two units per molecule of the general formula Q a Q'SiO.sub.(3-a)/2 with any remaining units having the general formula Q b SiO.sub.(4-b)/2 where Q contains no more than 8 carbon atoms and is selected from the group consisting of monovalent hydrocarbon and substituted monovalent hydrocarbon radicals, Q' represents an organic group having olefinic unsaturation, a has a value of 1 or 2 and b has a value of 0, 1, 2 or 3, and at least 80 percent of the Q groups are methyl; (B) an organohydrogensiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule, any remaining substituents on silicon being monovalent hydrocarbon radicals having no more than 8 carbon atoms; and (C) a catalyst selected from group VIII metals, compounds and complexes of said metals in an amount sufficient to catalyze a reaction between (A) and (B); the improvement consisting essentially of the presence in said composition of an adhesion promoting organosilicon compound corresponding to the general formula (RO).sub.C R.sub.3-C SiO(R.sub.2 SiO).sub.X (R'RSiO).sub.Y (R"RSiO).sub.Z SiR.sub.3-C (OR).sub.C where R is selected from the group consisting of monovalent hydrocarbon and substituted hydrocarbon radicals containing a maximum of 8 carbon atoms, alkoxyalkyl and substituted alkoxyalkyl; R' represents an olefinically unsaturated hydrocarbon radical containing at least 6 carbon atoms; R" represents a monovalent epoxy-substituted radical selected from the group consisting of hydrocarbon, hydrocarbonoxy, halogenated hydrocarbon, halogenated hydrocarbonoxy, hydroxyl-substituted hydrocarbon and hydroxyl-substituted hydrocarbonoxy; the value of c is 0, 1, 2, or 3, the values of x, y, and z are at least 1, with the proviso that z is at least 2 when c is 0.