GB755198A - Organosiloxane co-polymers - Google Patents

Abstract

Organosiloxane copolymers, consisting of 20 to 75 mol. per cent of phenylvinylsiloxane, 25 to 80 mol. per cent of methylphenylsiloxane and 0 to 5 mol. per cent of R3SiO0.5 units, where each R is a methyl, phenyl or vinyl radical, e.g. trimethyl -, vinyldimethyl -, phenyldimethyl-, vinyldiphenyl- and triphenyl-siloxane units, may be made by cohydrolysis and cocondensation of organolsilane mixtures or by co-condensation of mixtures of organosiloxanes, the silanes and siloxanes containing the desired silicon-bonded hydrocarbon radicals. In examples, liquid copolymers are obtained by (1,2) copolymerizing phenylvinyl- and methylphenylsiloxane cyclic tetramers and divinyltetramethyldisiloxane in the presence of C6H5(CH3), SiOK; and (3, 4) hydrolysing a mixture of phenylvinyl- and methylphenyldichlorosilanes at 80 DEG C. in a mixture of toluene and water. The liquid copolymers were then cured by heating at above 100 DEG C. with tertiary butyl perbenzoate. Other peroxides, e.g. ditertiary butyl and benzoyl peroxides, may also be used. The compounds are useful as solventless impregnating resins for electrical coils in generators and for component parts in electronic equipment. Specification 668,192 is referred to.