Improvements in or relating to the manufacture of rubber compositions

摘要

Porous rubber compositions, are prepared by admixing granular, fibrous, or divided materials with aqueous dispersions of rubber and the like which have been or are thereafter converted into a frothy condition and the froth is caused to set to a permanent structure of irreversible solid material of sponge-like or cellular structure. The granular &c. materials comprise for example scrap rubber sponge, vulcanized rubber scrap, with or without fibre scrap, fibres such as cotton, paper pulp, leather trimmings, asbestos, abrasives and cork. The aqueous dispersions of rubber and the like comprise for example those described in Specifications 290,313 and 219,635, [both in Class 70, Indiarubber &c.]. The processes of forming frothy masses disclosed in Specifications 332,525 and 332,526, [both in Class 70, Indiarubber &c.], are particularly suitable. Preferably the granular &c. materials are of larger average size than the average size of the cells of the froth. In an example, 1000 grams of a rubber mix containing approximately 9 grams of sodium silicofluoride are whipped into a froth and 300 grams of vulcanized rubber sponge trimmings of approximately 0,5 inch diameter are added. The mixture is poured into a mould and heated in an air oven at 100 DEG C. for 3 hours to vulcanize.