Mfg. two-ply web from foam rubber base and solid top layer - by incompletely expanding and vulcanising foamable base, applying pure rubber top ply, and completing vulcanisation of blank laminate

摘要

Mfr. of a rubber web with foam rubber substrate comprises expanding a rubber compsn. contg. expanding agent, in presence of heat and pressure but interrupting this step before vulcanisation is complete. The resulting foam web is coated with unvulcanised rubber compsn., free of any expanding agent, to obtain a blank which is finally completely vulcanised. Method disposes with prior-art method of glueing a solid web over a foam web, where the resulting laminate may fail in use owing to the adhesion of the plies breaking down and the plies detaching themselves from each other. Also, there is no tendency of the foamed substrate to increase in vol. after release of the vulcanisation pressure, thus avoiding warping of edge-curling of the prod.