GB897305A - Silicone rubber-forming compositions - Google Patents

Abstract

A filler for silicone rubber is prepared by treating a natural or manufactured silica, titania, an iron oxide, calcium carbonate or carbon black with a mono-, di- or tri-alkenyl silicon halide or alkoxide or with a partial hydrolysis product thereof in the vapour or liquid phase. In Example (1) fume silica is contacted with gaseous vinylmethyldichlorosilane. Other silanes specified are vinyltrichloro-, diallylchlorofluoro-, vinylallyldifluoro-, vinyltrimethoxy-, heptenytriethoxy-and vinyldimethylchloro-silanes. Specification 791,711 is referred to.ALSO:A rubber-forming composition comprises (A) a siloxane of the average general formula <FORM:0897305/IV (a)/1> wherein each R is a monovalent hydrocarbon or halogenated hydrocarbon radical, 0,05 to 1,0 mol. per cent of the radicals being vinyl radicals, and n has an average value of 1,9 to 2,1, and (B) a filler made by treating silica, titania, an iron oxide, calcium carbonate or carbon black with a mono-, di- or tri-alkenyl silicon halide or alkoxide or with a partial hydrolysis product thereof in the vapour or liquid phase, or a filler made by hydrolyzing and condensing a vinyl or allyl trihalogenosilane. The composition may also contain pigments, oxidation inhibitors and additional fillers such as untreated silica, and may be cured by heating with organoperoxy compounds or with high energy radiation. In examples a dimethylsiloxane-methylvinylsiloxane copolymer was mixed with fume silica, which had been pretreated by contact with gaseous vinylmethyldichlorosilane, and cured by (1) heating with di-t-butyl peroxide, or (2) ionizing radiation; (3) the copolymer of (1) was mixed with fume silica, vinyl silicic acid, obtained by hydrolysis and condensation of vinyltrichlorosilane, and 2:4-dichlorobenzoylperoxide paste and vulcanized under pressure. Uses:-for making baby bottle nipples, seals, gaskets and electrical insulation. Specification 791,711 is referred to.