Vulcanization system, a rubber mixture containing this vulcanization system and a vulcanization process

A vulcanization system comprising

• (A) from 20 to 50 parts by weight of sulfur or a sulfur donor,
• (B) from 20 to 50 parts by weight of a mercapto or sulfenamide accelerator,
• (C) from 0 to 10 parts by weight of a conventional auxiliary accelerator and
• (D) from 20 to 50 parts by weight of a compound selected from the group consisting of ##STR6## wherein R.sub.1 taken separately is hydrogen, C.sub.1 -C.sub.10 alkyl or alkenyl, C.sub.5 -C.sub.7 cycloalkyl or cycloalkenyl, C.sub.6 -C.sub.10 aryl, or C.sub.6 -C.sub.10 aryl substituted at least once by alkyl having 1 to 4 carbon atoms;
• R.sub.2 taken separately is hydrogen, C.sub.1 -C.sub.10 alkyl or alkenyl, C.sub.5 -C.sub.7 cycloalkyl or cycloalkenyl, C.sub.6 -C.sub.10 aryl, C.sub.6 -C.sub.10 aryl substituted at least once by alkyl having 1 to 4 carbon atoms, a radical of the formula ##STR7## or a radical of the formula ##STR8## n is 2 or 3 n.sub.1, n.sub.2 and n.sub.3 are each a number from 2 to 10;
• R.sub.1 and R.sub.2 taken together form a 4- to 10-member carbocyclic ring or one of said rings containing N, O or S as a hetero atom;
• R.sub.3 to R.sub.7 are each hydrogen, halogen, nitro, cyano, --CF.sub.3, --CCl.sub.3, alkoxy carbonyl having 2 to 5 carbon atoms or C.sub.1 -C.sub.4 alkyl with the proviso that at least one of R.sub.3 -R.sub.7 is other than hydrogen;
• R.sub.8 is hydrogen or methyl and
• R.sub.9 is C.sub.4 -C.sub.12 cycloalkyl, C.sub.6 -C.sub.10 aryl, di-C.sub.4 -C.sub.12 cycloalkyl substituted C.sub.1 -C.sub.4 alkyl, tri-C.sub.4 -C.sub.12 cycloalkyl substituted C.sub.1 -C.sub.4 alkyl, di-C.sub.6 -C.sub.10 aryl substituted C.sub.1 -C.sub.4 alkyl or tri-C.sub.6 -C.sub.10 aryl substituted C.sub.1 -C.sub.4 alkyl.