to siliconkautschuken vulkanisierbare, compounds the masses

摘要

1,219,752. Pelletized silicone-rubber-forming compositions. MIDLAND SILICONES Ltd. 20 May, 1968 [2 June, 1967], No. 25527/67. Heading C3T. A silicone rubber-forming composition comprising a vulcanizable diorganopolysiloxane and one or more fillers, and having a Williams plasticity of at least 200 (0À01 mm.), is formed into pellets having a minimum dimension of at least 0À1 inch. The maximum dimension of the pellets is preferably below 1 inch. Suitable standard organic groups in the polysiloxane and standard fillers and curing peroxides are listed (or cure may be by irradiation). The pellets may be prepared by cutting a preformed sheet, and dusting the pellets so formed. In examples, a dimethylpolysiloxane gum containing some methylvinylsiloxane units is mixed with a fume silica, and optionally diatomaceous earth, a low molecular weight hydroxy-terminated polydimethylsiloxane and 2:4-dichlorobenzoyl peroxide in a silicone oil; the mixture is sheeted, cut into pellets, and dusted with micronized mica or hydrated magnesium silicate.