Addition-curable silicone adhesive compositions and bis (trialkoxysilyalkylene) urea adhesion promoters

Claim 1

An addition-curable composition, comprising by weight, (A) 100 parts of a vinyl-containing polydiorganosiloxane composition comprising: (1) about 50 to about 100 parts of an essentially cyclic-free vinyl-terminated polydiorganosiloxane having the general formula, (R).sub.2 V.sub.i SiO[(R).sub.2 SiO].sub.m [RV.sub.i SiO].sub.n S.sub.i (R).sub.2 V.sub.i, where Vi is a vinyl radical, R is selected from the class consisting of alkyl radicals having 1 to 8 carbon atoms, phenyl radicals, fluoroalkyl radicals having 3 to 10 carbon atoms and mixtures thereof, "m+n" has a value sufficient to provide a polydiorganosiloxane viscosity of 100 to about 100,000 centipoise at 25° C., and a polydiorganosiloxane vinyl content of from about 0.02 to about 2.0 weight %, and (2) from about 0 to about 50 parts of a solid, benzene-soluble vinyl-containing resin copolymer comprising, (R.sup.1).sub.3 SiO.sub.1/2 units and SiO.sub.4/2 units, where R 1 is a vinyl radical, or a monovalent hydrocarbon radical free of aliphatic unsaturation and containing no more than six carbon atoms, the ratio of (R 1 ) 3 SiO 1/2 units to SiO 4/2 units being from about 0.5:1 to about 1.5:1, and the resin having a vinyl content of from about 1.5 to about 3.5% by weight, (B) from about 1 to about 20 parts of a hydrogen-containing polysiloxane having an average unit formula, R.sup.2.sub.a H.sub.b SiO.sub.(4-a-b)/2, where R 2 is a monovalent hydrocarbon radical, or halogenated monovalent hydrocarbon radical having from 1 to about 10 carbon atoms and free of aliphatic unsaturation, "a" has a value of from about 0 to about 3, "b" has a value of from about 0 to about 3, and the sum of "a"+"b" has a value of from 0 to 3, (C) a catalytic amount of a hydrosilylation catalyst, (D) an effective amount of a bis[trialkyloxysilylalkylene]urea adhesion promoter having the formula, [(R.sup.3 O).sub.3 S.sub.i R.sup.4 ].sub.2 Q where R 3 is a C.sub.(1-4) alkyl radical, R 4 is a C.sub.(2-8) alkylene radical, Q is a divalent urea radical having the formula ##STR4## and R 6 is selected from R 3 radicals, (E) from about 0 to about 200 parts of an extending filler, and (F) from about 0 to about 50 parts of a reinforcing filler, and in the absence of (A) (2), an amount effective for reinforcement.