GB808431A - Improved vulcanisation process for rubber - Google Patents

Abstract

In a process for vulcanizing natural or synthetic rubber there is incorporated in the rubber a vulcanizing agent, an accelerator and a substance of the formula R1[R2NSO2X]n wherein n is 1 or 2 and R1 is a hydrocarbon radical, optionally substituted, or either such radical or hydrogen when n is 1, R2 is hydrogen or a hydrocarbon radical, optionally substituted, and when n is 1, R1, R2 and the adjacent nitrogen atom may form part of a heterocyclic ring, and wherein X is an OM, OR1, or NR3R4 radical, wherein M is a metal or ammonium and R3 and R4 are each hydrogen or a hydrocarbon radical, optionally substituted, and may together with the adjacent nitrogen atom form part of a heterocyclic ring. The addition of the substance of the stated formula reduces the tendency to scorch during vulcanization particularly when the vulcanizable composition contains reinforcing type furnace black. As examples of the said substance are specified: sulphamic acid, 4:41-sulphonyldimorpholine, 1:4 bis-(dimethylsulphamyl) piperazine, zinc, sodium, calcium, magnesium and aluminium sulphamates, 2:4 dichlorophenyl and p-cyclohexylphenyl dimethylsulphamates, and cyclohexylsulphamic acid. The vulcanizing agent is preferably sulphur, and the accelerator is preferably of the delayed-action type such as N-tert.-butyl, N-tert.-octyl or N-cyclohexyl benzthiazyl sulphenamide, benzthiazyl sulphenmorpholide or sulphenpiperidide, 2:4-dinitrophenyl-2-benzthiazyl monosulphide, ethylbenzthiazyl or 2,21-dibenzthiazyl disulphide, and diphenyl or di-o-tolyl guanidine. The synthetic rubbers specified are polymers of butadiene 1,3,2-methylbutadiene 1-3, isobutene, and copolymers thereof with acrylonitrile, styrene, methyl methacrylate, and other polymerizable compounds.