Production of foamed elastomers

A process for the production of foamed elastomers comprises reacting (a) a liquid copolymer of a conjugated diolefine and an aliphatic unsaturated carboxylic acid containing up to six carbon atoms in the molecule with (b) an organic polyisocyanate in the presence of a cross-linking agent. The amount of organic-polyisocyanate used is preferably in excess of that which is equivalent to the acid content of the copolymer. Suitable copolymers are those having a viscosity of 10 to 100 poises at 70 DEG . They can be prepared by emulsion polymerisation or by chemical modification of other polymers (see Group IV(a)). As cross-linking agents there are specified water, and a number of polybasic carboxylic acids, polyhydric alcohols, polyamines and aminoalcohols. In preparing the foamed elastomers a liquid or low melting point hydroxy group-terminated reaction product of a polyester or polyether with a polyisocyanate can be incorporated with the copolymer and polyisocyanate mixture, with further cross-linking agents if necessary. The rate of the reaction can be increased by adding such bases as diphenylamine, p-phenylenediamine, diphenylguanidine, guanidine, aniline, benzidine, o, o1-dichlorobenzidine, anisidine, aminopyridine, 2-2-dipyridylamine, p-phenylenediamine, 2-amino-4 : 6-dimethylpyridine, hexamethylenetetramine, hydrazine hydrate, calcium hydroxide and ammonium carbonate and retarded by the agents described in Specifications 790,543, 791,956, 831,301 and 831,302. In examples butadiene (90 parts) and methacrylic acid (10 parts) were copolymerised. The polymer was converted to foamed products by (1) reaction with 2 : 4-toluene diisocyanate, followed by the addition of further diisocyanate, water and pyridine; (2) and (3) addition of mixed 2 : 4- and 2; 6-toluene diisocyanates and (2) adipic acid; (3) succinic acid; (4) additions as in (2) together with pyridine.