GB766665A - Improvements in organopolysiloxane elastomers - Google Patents

Abstract

A silicone rubber is made by heating a mixture comprising (1) an organopolysiloxane convertible to the solid elastic state and in which the silicon-bonded organic radicals are the same or different monovalent hydrocarbon and/or halogenated hydrocarbon radicals, and (2) an organosilicon compound of the formula <FORM:0766665/IV(a)/1> where each R is an alkyl or halogenated alkyl group, and R1 is an alkyl, aryl, aralkyl, alkaryl, alkoxy or aryloxy group or a halogenated derivative thereof, or a liquid partial hydrolysate thereof, in amount of 0.01 to 8 per cent by weight of the siloxane. The organosilicon compound may be incorporated in the siloxane on compounding rolls simultaneously with a filler and curing agent, or after the filler has been added to the siloxane, or it may be mixed with the filled siloxane and the resulting mixture heated from 100 DEG to 175 DEG C. and cooled before adding the curing agent; or it may be mixed with the filler and heated from 125 DEG to 175 DEG C. and then mixed with the siloxane and curing agent. Solvents such as xylene, toluene and perchlorethylene may be added and the resulting dispersions may be used for coating purposes. Curing agents specified are benzoyl peroxide and t. - butylperbenzoate. Fillers specified are titania, lithopone, zinc oxide, zirconium silicates, silica aerogel, iron oxide, diatomaceous earth, calcium carbonate and fume silicas, and may be used in amount of 10 to 300 per cent by weight of the siloxane. Examples are given. Specifications 594,481, [Group IV], 618,453, 640,067 and 711,374, [Group III], are referred to.