Vulcanizates

Claim 1

An improved rubbery vulcanizate is provided by the vulcanization of a mixture comprising vulcanization active agents, at least two synthetic polymers and at least two fillers, said at least two fillers being one of silica or calcium silicate and the other being carbon black, said at least two synthetic polymers being (A) a C 4 -C 6 conjugated diolefin containing polymer which contains, per 100 grams of polymer, chemically bound in the polymer from about 1.5 to about 80 millimoles of hydroxy groups or from about 4 to about 60 millimoles of epoxy groups and selected from styrene-butadiene-hydroxyethyl acrylate, styrene-butadiene-hydroxyethyl methacrylate, styrene-butadiene-glycidyl acrylate, styrene-butadiene-glycidyl methacrylate and styrene-butadiene-methallyl glycidyl ether polymers, which polymer is mixed with said silica or calcium silicate and optionally other compounding ingredients, and (B) a C 4 -C 6 conjugated diolefin containing polymer which is mixed with said carbon black and optionally other compounding ingredients prior to being mixed with the polymer A-filler mixture, the mixture comprising, per 100 parts by weight of total polymers, from about 20 to about 80 parts by weight of polymer A, from about 20 to about 80 parts by weight of polymer B, from about 5 to about 100 parts by weight of silica or calcium silicate, from about 5 to about 100 parts by weight of carbon black to provide a weight ratio of silica or calcium silicate to carbon black of from about 20:80 to about 65:35 and optionally an additive selected from (i) 0.5 to 5 parts by weight of an amine of the formula R--NH.sub.2, R--NHR' or R--NR"R''' where R is a C 4 -C 30 linear or branched alkyl or alkylene group which may contain one NH 2 or NH group or a C 4 -C 30 cycloalkyl group or a C 7 -C 20 alkaryl group connected to the nitrogen atom through the alkyl component of the alkaryl group, R' is a C 1 -C 30 linear or branched alkyl or alkylene group and R" and R''', which may be the same or different, is a C 1 -C 10 alkyl group, or (ii) from about 1 to about 5 parts by weight of an organic acid or salt thereof selected from the C 15 -C 20 saturated or unsaturated fatty acids or the alkali metal, alkaline earth metal or ammonium salts thereof, or (iii) from about 1 to about 10 parts by weight of magnesium oxide, said silica or calcium silicate having been mixed with said polymer A and said additive under conditions of shear at a temperature of from about 100° C. to about 190° C. prior to being mixed with the polymer B-carbon black mixture.