Vulcanization of rubber with phosphinothioyl amino sulfides

A process for vulcanizing rubber which comprises heating a sulfur-vulcanizable diene rubber composition containing sulfur-vulcanizing agent, an accelerating agent selected from the group consisting of thiazole acceleraor, dithiocarbamate accelerators, thioperoxydiphosphate accelerators, zinc phosphorodithioate accelerators, thiuram sulfide accelerators, aldehyde-amine accelerators, diaryl guanidine accelerators and mixtures thereof and, in an amount effective to enhance the vulcanization rate of the composition, a compound of the formula ##STR6## in which R and R.sub.1 independently are alkyl of 1 to 12 carbon atoms, cycloalkyl of 5-8 carbon atoms, alkaryl of 7 to 10 carbon atoms, phenyl or mono- or di-lower alkyl substituted phenyl.

A vulcanizable composition comprising diene rubber, sulfur-vulcanizing agent and, in an amount to enhance the vulcanization rate of the composition, a compound of the formula ##STR7## in which R and R.sub.1 independently are alkyl of 1 to 12 carbon atoms, cycloalkyl of 5-8 carbon atoms, alkaryl of 7 to 10 carbon atoms, phenyl or mono- or di-lower alkyl substituted phenyl.