GB632390A - Improvements in the processing of synthetic rubbers - Google Patents

Abstract

The stickiness during processing or milling of a synthetic rubber is reduced by adding from 0.01 to 0.10 per cent by weight of a liquid organopolysiloxane. The siloxanes may be prepared according to the methods described in Specifications 586,187, 586,188 and 586,189 and include:-(1) compositions consisting substantially of a mixture of silicones of the formula [(CH3)2SiO]x in which x is at least 10; (2) polysiloxanes of the general formula <FORM:0632390/IV (a)/1> where R is either H or a methyl radical and n is a positive integer, and (3) liquid methyl polysiloxanes in which all or substantially all of the silicon atoms are each connected to two methyl groups. The substituted groups in these compounds may be methyl, ethyl, propyl, amyl, heptyl, isopropyl, cyclopentyl, cyclohexyl, phenyl, anthracyl, tolyl, xylyl, mesityl, aralkyl such as benzyl, phenylethyl, and alkenyl such as allyl and methallyl, and heterocyclic radicals which may contain inorganic radicals such as halogens. The synthetic rubbers may be copolymers of butadiene with styrene, acrylonitrile, or isobutylene; polymers of chloroprene; or condensation products of dihalides with inorganic polysulphides. Specifications 548,911 and 548,912 also are referred to.ALSO:The stickiness during processing on milling of a synthetic rubber is reduced by adding from 0.01 to 0.10 per cent by weight of a liquid organopolysiloxane. The siloxanes may be prepared according to the methods described in Specifications 586,187, 586,188 and 586,189, [all in Group IV], and include:-(1) compositions comprising substantially of a mixture of silicones of the formula [(CH3)2 SiO] x in which x is at least 10. (2) Polysiloxanes of the general formula <FORM:0632390/V/1> Where R is either H or a methyl radical and n is a positive integer and (3) Liquid methyl polysiloxanes in which all or substantially all of the silicon atoms are each connected to two methyl groups. The substituted groups in these components may be methyl, ethyl, propyl, amyl, heptyl, isopropyl, cyclopentyl, cyclohexyl, phenyl, anthracyl, tolyl, xylyl, mesityl, aralkyl such as benzyl, phenylethyl and alkenyl such as allyl, and methallyl, and heterocyclic radicals which may contain inorganic radicals such as halogens. The synthetic rubbers may be copolymers of butadiene with styrene, acrylonitrile, or isobutylene; polymers of chloroprene; or condensation products of dihalides with inorganic polysulphides. Specifications 548,911 and 548,912, [both in Group IV(a)], also are referred to.