GB957108A - Organopolysiloxane elastomer-forming compositions and articles made therefrom - Google Patents

Abstract

A rubber-forming composition comprises, by weight, 100 pts. of an elastomer-forming organopolysiloxane having from 1.98 to 2.05 organic radicals per Si atom, at least a minor proportion of the radicals being unsaturated radicals, and of viscosity from 5X106 to 125X106 cs. at 20 DEG C., 25 to 100 pts. of a furnace black of particle size from 15 to 1000 m .m and of surface area from 1 to 200 m2/g, or an acetylene black of particle size from 40 to 55 m m and of surface area from 40 to 70 m2/g, 10 to 20 pts. of one or more other fillers, 0 to 10 pts. of a structure control additive and 0.25 to 10 pts. of an organic peroxide selected from di-t-butyl-, di-cumyl- and t-butylcumyl-peroxides, 2:5-bis(t-butyl-peroxy)-2:5 dimethylhexane and 2:5-bis(t-butyl-peroxy)-2:5-dimethylhexyne-3. Fillers specified are silica (aerogel, precipitated, fume and natural), alumina, lithopone, calcium carbonate and talc with or without surface treatment with silanes or siloxanes. Structure control additives specified are (tetramethylelthylenedioxy)- dimethylsilane, -diethyl-silane, -diphenylsilane and -methylphenyl-silane, pinacolmono- and pinacolbis-trimethyl-silylethers, diphenylsilanediol and diphenyldi-methoxy- and diphenyldiethoxy-silanes. The compositions may be shaped and heat cured, or dispersed in solvents and applied as coatings on to suitable fabrics (see Division B2). In a typical example (1) methylvinylsiloxane, furnace black, fume silica (tetramethylethylenedioxy) - dimethyl silane and dicumylperoxide blended with CaCO3, were compounded, pressed into a sheet and heat-cured under pressure. Uses: for making heating elements, e.g. in heating jackets for industrial or scientific equipment, electric blankets and heating panels.ALSO:In making heating elements, e.g. in heating jackets for industrial and scientific equipment, electric blankets and heating panels, a substrate, e.g. of glass cloth or cotton, is coated in known manner with a dispersion in an organic solvent of a composition comprising, by weight, 100 parts of an elastomer-forming siloxane of viscosity from 5 x 106 to 125 x 106 cs. at 20 DEG C., 25 to 100 parts of a furnace black of particle size from 15 to 1000m m and of surface area from 1 to 200 m.2/g., or an acetylene black of particle size from 40 to 55m m and of surface area from 40 to 70 m.2/g., 10 to 20 parts of one or more other fillers, 0 to 10 parts of a structure control additive and 0,25-10 parts of a certain organic peroxide (see Division C3). Examples 4 and 6 to 12 describe the coating of glass cloth with the above composition.