Patent ID: 7687587

Claim:
A silicone composition comprising: (A) an organopolysiloxane resin having an average of at least two silicon-bonded alkenyl groups per molecule, wherein the resin has the formula: (R 1 R 2 2 SiO 1/2 ) w (R 2 2 SiO 2/2 ) x (R 1 SiO 3/2 ) y (SiO 4/2 ) z , wherein R 1 is C 1 to C 10 hydrocarbyl or C 1 to C 10 halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, R 2 is R 1 or alkenyl, w is from 0 to 0.8, x is from 0 to 0.6, y is from 0 to 0.99, z is from 0 to 0.35, w+x+y+z=1, y+z/(w+x+y+z) is from 0.2 to 0.99, w+x/(w+x+y+z) is from 0.01 to 0.8, and at least 50 mol % of the groups R 2 are alkenyl; (B) an organohydrogensilane in an amount sufficient to cure the composition, the organohydrogensilane having the formula: wherein R 1 is a C 1 to C 10 hydrocarbyl or C 1 to C 10 halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, and R 3 is a hydrocarbylene group having a formula selected from: wherein g is from 1 to 6; (C) an effective amount of a reactive diluent comprising (i) an organosioxane having an avenge of at least two silicon-bonded alkenyl groups per molecule and a viscosity of from 0.001 to 2 Pa·s at 25° C., wherein the viscosity of (C)(i) is not greater than 20% of the viscosity of component (A) and the organosiloxane has the formula (R 1 R 2 2 SiO 1/2 ) m (R 2 2 SiO 2/2 ) n (R 1 SiO 3/2 ) p (SiO 4/2 ) q , wherein R 1 is C 1 to C 10 hydrocarbyl or C 1 to C 10 halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, R 2 is R 1 or alkenyl, m is 0 to 0.8, n=0 to 1, p=0 to 0.25, q=0 to 0.2, m+n+p+q=1, and m+n is not equal to 0, provided when p+q=0, n is not equal to 0 and the alkenyl groups are not all terminal, and (ii) an organohydrogensiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule and a viscosity of from 0.001 to 2 Pa·s at 25° C., in an amount sufficient to provide from 0.5 to 3 moles of silicon-bonded hydrogen atoms in (C)(ii) per mole of alkenyl groups in (C)(i), wherein the organohydrogensioxane has the formula (HR 1 2 SiO 1/2 ) s (R 1 SiO 3/2 ) t (SiO 4/2 ) v , wherein R 1 is C 1 to C 10 hydrocarbyl or C 1 to C 10 halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, s is from 0.25 to 0.8, t is from 0 to 0.5, v is from 0 to 0.3, s+t+v=1, and t+v is not equal to 0; and (D) a catalytic amount of a hydrosilylation catalyst.