Organopolysiloxane compositions

Claim 1

A curable organopolysiloxane composition comprising: (A) from about 50 to about 75 % by weight of the total weight of (A), (B) and (C) of the composition of a resinous copolymer comprising units of: and where each R is a monovalent hydrocarbon radical having from 1 to about 6 carbon atoms, wherein the copolymer comprises from about 0.5 to about 5 % by weight, based on the total weight of the copolymer, of hydroxyl radicals, and the molar ratio of R 3 SiO l/2 units to Si0 4/2 units being between from about 0.6 to about 0.9; (B) a hydride-terminated organopolysiloxane wherein (B) has a viscosity of from about 10 to about 1000 centipoise at 25°C, and has the general formula: where each R 1 is independently an alkyl group having from 1 to about 10 carbon atoms or an aryl group, the sum of x and y is from about 1 to about 500, and y is from 0 to about 10. (C) an alkenyl silicone blend comprising (i) from 0 to 90 mole % of an alkenyl-terminated organopolysiloxane polymerwith a viscosity of from about 10 to about 500 centipoise at 25°C, and has the general formula: where R 2 is an alkenyl group having from 1 to about 10 carbon atoms, R 3 is an alkyl group having from 1 to about 10 carbon atoms or an aryl group, z is from 1 to about 300, and (ii) from 10 to 100 mole % of a silicon-bonded alkenyl crosslinkerwhich is based on the total available alkenyl groups in the blend allowing for more than 2 silicon-bonded alkenyl groups per chain or molecule; wherein (B) and (C) are present in amounts from about 25 to about 50 % by weight based on the total weight of (A), (B) and (C) and provide a total SiH/Sialkenyl ratio of about 1.1:1 to about 15:1; (D) an effective amount of a hydrosilation catalyst; and (E) from O to about 40% by weight of the composition of an organic solvent based on the total weight (A), (B), (C), (D) and (E).