GB422157A - Improved process for the manufacture of articles of sponge rubber - Google Patents

Abstract

A paint for application to the inner surface of a sponge-rubber mould consists of a solution of the following composition (parts by weight) in benzol:--smoked rubber sheets 100, colophony 10, stearic acid 3, sulphur 3, zinc oxide 5, mercaptobenzothiazole 0,5.ALSO:A process for making sponge rubber in which rubber introduced into a mould swells during vulcanization by heat so as to conform to the shape and size of the mould is characterized by the provision within the mould of a heat insulating lining of pulverulent material or unwoven fibrous material. The pulverulent material may be kieselguhr, talc, magnesia, sawdust, powdered lignine, powdered leather or cork. The unwoven fibrous material may be cotton, hemp, flax, wool, silk or asbestos, and may be comminuted. The material may be applied by the aid of adhesive or may be shaped by hand or machine before placing in the mould. The surface of the material may be impressed with a relief pattern and may be coloured with substances which tinge the rubber on vulcanization or with coloured rubber solutions which form a film on the surface of the vulcanized article. The surface may be made up of fragments of cut material painted in various colours. In an example, to the inner surface of a hot mould is applied a solution of vulcanizable rubber in benzol. The solution dries instantaneously, and cotton or asbestos powder is spread and rolled thereon. The excess is removed and compressed air is blown thereon.