PROCEDIMIENTO PARA LA OBTENCION DE ELASTOMEROS.

摘要

A composition which may be converted to a silicone rubber with moisture at temperatures <50 DEG C. comprises: (1) an organopolysiloxane of formula in which n is an integer >1, R is H, an alkyl, alkenyl or aryl radical and at least half of the R1s are Me, and (2) a crosslinking agent either of formula X4- aSiYa or an organosiloxane of units, in which each X is H or an inertly substituted or unsubstituted alkyl or aryl radical, a is 3 or 4, m is an integer from 1 to 3 and b is integer from 1 to m. The number of structural units is such that there are at least 3 radicals Y in each molecule. Y is a Si-N bonded carboxylic acid amide radical of formula in which R11 is an inertly substituted or unsubstituted alkyl or aryl radical, R111 is H or an inertly substituted or unsubstituted alkyl or aryl radical and RIV is an inertly substituted or unsubstituted alkylene or arylene radical. The polysiloxane (1) may also contain up to 10 mole per cent of units of formula RSiO 3/2 . The cross-linking agent (2) may be diluted with an inert organic solvent and the composition may contain a filler, e.g. chalk, talc, kielselguhr, silica, silica gel, quartz powder, TiO2, an iron oxide, zirconium silicate, CaSo4, Al2O3, MgO, carbon black, graphite or a silica modified by surface alkylation. The composition may also contain up to 10% of the weight of the base siloxane of an a ,o -bis-(trimethyl-siloxy)-poly-dimethyl siloxane having a viscosity of 100 to 200,000 centistokes at 20 DEG C. It may also contain a methyl polysiloxane consisting of (CH3)3SiO 1/2 units and SiO2 units in a molar ratio of from 1:1 to 1:2 and in an amount up to 50% based on the siloxane (1). In general not more than 60% by weight of crosslinking agent is used based on the polysiloxane (1). The following compounds are specifically claimed as crosslinking agents