GB490905A - Improvements in latex compositions - Google Patents

Abstract

A process for vulcanizing latex or latex compositions consists in incorporating, as an accelerator, in a vulcanizable latex or latex composition, an alkali-metal or ammonium salt of an N-aralkyl-substituted dithiocarbamic acid capable of having its accelerating action arrested by ammonia, deactivating the accelerator by ammonia and thereafter removing or neutralizing the ammonia to allow of vulcanization. The ammonia may be replaced by a volatile substituted ammonia in which one of the H atoms has been replaced by a hydrocarbon radical, preferably an alkyl radical, e.g. methylamine. The vulcanization of the rubber in the latex state can be checked at the desired stage by reintroducing ammonia or substituted ammonia. For example latex containing ammonia or a substituted ammonia, vulcanizing agents and accelerator, may have the ammonia or substituted ammonia content reduced to about ,1 per cent, by aeration or neutralization with formaldehyde, thereby allowing vulcanization to proceed at room temperature or higher, and then by reintroducing ammonia or substituted ammonia into the latex before the vulcanization of the rubber globules is completed, a partly vulcanized latex is obtained. The accelerators are of the general formula <FORM:0490905/V/1> where M is an alkali-metal or ammonium radical which in the case of ammonium may be substituted, for example dibenzylammonium-N-dibenzyl-dithiocarbamate. They may be used in combination with accelerators of the thiazole type, e.g. the zinc salt of mercaptobenzothiazole, the combination being similarly deactivated by ammonia or substituted ammonia. U.S.A. Specification 1,995,859 is referred to.