Bicycle inner tubes prodn. - by dipping a former into butyl rubber latex, then into natural or synthetic rubber latex and covulcanising composite rubber layer formed

摘要

Prodn. of dipped rubber tubes which are impermeable to air, esp. inner tubes for racing bicycles, comprises (a) dipping a hollow cylindrical former of suitable dimensions into an artificial butyl rubber latex contg. polyisoprene molecule, opt. using the multilayer technique, to give a vulcanisable polyisobutylene tube 0.03-0.25mm (esp. 0.05-0.15mm) thick. Process further comprises (b) dipping the former, covered with the predried polyisobutylene tube, into a natural or synthetic rubber latex (opt. after first dipping the tube in a bath of coagulating agent if the latex is not thermosensitised) to give a composite tube with an external covering of natural or synthetic rubber 0.20-0.60 mm thick; (c) gelling the composite tube, e.g. by circulating hot water inside the tubular former; and (d) simultaneously vulcanising the two layers of rubber. Process allows industrial scale prodn. of air-impermeable tubes with a single vulcanisation of the two layers of rubber.