GB497652A - Improvements in and relating to the production of porous and/or spongy masses or articles of rubber and rubber-like material - Google Patents

Abstract

Porous masses are obtained by frothing positively charged, i.e acid, aqueous dispersions of rubber or rubber-like materials such as thiokol or neoprene by the generation or liberation of gas therein and setting the resulting froth, if desired after rendering the froth alkaline. The dispersion may be prefrothed, e.g. by beating prior to the main frothing operation and this prefrothing may be effected with negatively or positively charged dispersions. The frothing may be effected by chemical means, e.g. by the decomposition of salts such as carbonates, bicarbonates, sulphides, or sulphites which liberate gas under the action of acid, or by physical means, e.g. by the volatilization under heat and/or by pressure reduction of a volatile solid or a volatile liquid or gas adsorbed on a solid adsorbent. Thickening agents such as alginates, casein or glue may be added to the dispersion prior to frothing. The froth may be incorporated with fibrous material, e.g. as described in Specification 489,031. The frothing may be effected in a mould having means for automatically closing the container when it is full of froth as described in Specification 484,798. Specification 489,031 also is referred to.