GB309245A - Improvements in the treatment of rubber latex - Google Patents

Abstract

309,245. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.). Jan. 23, 1928. Latex, coagulating.-Latex is coagulated by the addition of an acid in the presence of an organic substance possessing soap-like properties which is not decomposed by acids into products insoluble in water, and which reduces the surface tension of the latex. Such substances comprise aromatic or hydroaromatic sulphonic acids which contain alkyl, cycloalkyl, aralkyl or aryl groups in the nucleus, or in other substituents such as amino or hyroxyl groups, true sulphonic acids of aliphatic tar or mineral oils, fatty acids, naphthenic acids and the like, fat splitters, suiphonic acids which have tanning properties, such as those obtained by treating sulphonic acids of naphthalene with formaldehyde, Turkey red oils, or salts of these acids. Coagulation is rapid and complete, and is independent of the concentration of the acid. If an acid or substance producing a hydrogen ion concentration pH>-2 and preferably #-1 is used with these substances, a bulky irreversible jelly is formed with a small amount of limpid serum. Vulcanizing agents, accelerators, fillers, &c. may be added at any stage. Several examples are given, of which the following are typical : (1) 1 litre of 12 per cent latex is treated with 60 ccm. of a 5 per cent solution of Turkey red oil, after elimination of ammonia, and 140 ccm. of 12 per cent acetic acid; rubber coagulates at once quantitatively. (2) 1 litre of latex is introduced into 7 per cent. hydrochloric acid with stirring, to obtain a pH value of 0.6-0.8; 15 ccm. of a 5 per cent solution of the sodium salt of isopropyl naphthalenesulphonic acid are added and a jelly forms.