Silica filled multi-viscoelastic response rubber

A method for processing a rubber composition by a multi-stage mixing procedure comprising at least one non-productive stage and a productive stage:

• (A) wherein said non-productive stage is characterized by mixing a rubber composition at a rubber temperature in a range of from 140° C. to 190° C. for a mixing time of from 1 to 20 minutes, and said rubber composition comprises
• (1) 100 parts by weight of at least one sulfur vulcanizable elastomer wherein
• (a) from 40 to 100 parts by weight of said vulcanizable elastomer is a multi-viscoelastic response rubber;
• and
• (b) from zero to 60 parts by weight of said vulcanizable elastomer is a rubber containing olefinic unsaturation other than said multi-viscoelastic rubber;
• (2) from 0.1 to 25 phr of an organosilicon compound of the formula:
• Z-Alk-Sn-Alk-Z
• in which Z is selected from the group consisting of
• where R1 is an alkyl group of 1 to 4 carbon atoms, cyclohexyl or phenyl;
• R2 is alkoxy of 1 to 8 carbon atoms, or cycloalkoxy of 5 to 8 carbon atoms;
• Alk is a divalent hydrocarbon of 1 to 18 carbon atoms and n is from 2 to 8;
• (3) from 10 to 250 phr of a silica filler;
• and
• (4) the absence of zinc oxide to form a non-productive compound;
• (B) wherein said productive stage is characterized by mixing at a rubber temperature not to exceed 120° C., and the productive stage compound contains
• (1) said non-productive compound;
• (2) from 0.5 to 5 phr of a sulfur vulcanizing agent;
• and
• (3) from 1 to 8 phr of zinc oxide.