Free-flowing, sulphur-contg. rubber powder - obtd. by mixing aq. sulphur suspension with rubber latex or emulsion, adding pptn. agent, adding more sulphur of filler and working up

摘要

A process for the prodn. of free-flowing, sulphur-contg. rubber powder (I) involves mixing a rubber latex or an aq. emulsion of a rubber soln. with an aq. suspension of sulphur, adding a precipitating agent (II), opt. adjusting the pH, adding more sulphur or filler while opt. distilling off any solvent, washing until the ppte. is neutral, separating the ppte. and drying it at below 70 deg.C with constant agitation. Pref., at least 90% of the sulphur is insol. in CS2. Pref., latex is based on SBR with 15-30 wt.% styrene and the emulsions are prepd. from solns. of rubber (polybutadiene, SB copolymer, EPM, EPDM, etc.) in hydrocarbon solvents; pref. sulphur is, e.g. Crystex N (RTM); filler is carbon black, SiO2, kaolin, MgO, etc., and pref. (II) is Al sulphate. USE/ADVANTAGE - (I) is useful as a crosslinker in rubber vulcanisation; the invention provides sulphur for vulcanisation in the same easily-workable form as powdered rubber-filler mixts.