Silica reinforced rubber composition which contains oleylammonium bromide and/or mercaptoimidazolium bromide coupling agents to enhance electrical conductivity and article of manufacture, including a tire, having at least one component comprised of such rubber composition

A rubber composition which comprises, based upon parts by weight per 100 parts by weight rubber (phr):

• (A) 100 parts by weight of at least one diene hydrocarbon based elastomer,
• (B) about 25 to about 90 phr of particulate reinforcing filler comprised of about 10 to about 70 phr of synthetic amorphous silica aggregates and, correspondingly, from zero to about 25 phr of at least one of carbon black and silica treated carbon black having domains of silica on its surface, wherein said silica aggregates and said silica domains on the surface of said treated carbon black contain hydroxyl groups (e.g. silanol groups) on their surface;
• and
• (C) about 0.5 to about 10 phr of a coupling agent selected from one of N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide, or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide;
• wherein said coupling agent is provided and mixed with said elastomer(s), according to one or more of the following:
• (1) mixing said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide with said elastomer(s) and said particulate reinforcement;
• (2) pre-reacting said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide with
• (a) precipitated silica aggregates, or
• (b) an aqueous dispersion of colloidal silica particles from which precipitated silica aggregates are recovered to form a silica composite thereof,
• (3) mixing said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide with said elastomer(s) and said particulate reinforcement according to any of said steps (1) or (2) wherein said particulate reinforcement includes at least one of said synthetic precipitated silica aggregates which has been pre-hydrophobated prior to mixing with said elastomers by reaction with an alkylsilane of the general formula (I):
• Xn—Si—R4−n (I)
• wherein X is a radical selected from alkoxy radicals having from 1 through 3 carbon atoms, preferably selected from methoxy and ethoxy radicals, and from halogen radicals selected from at least one of chlorine and bromine radicals, preferably a chlorine radical;
• R is an alkyl radical having from 1 to 18 carbon atoms, preferably from 1 through 4 carbon atoms and more preferably selected from methyl and ethyl groups;
• and n is an integer of 1 through 3,
• (4) mixing said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide with said elastomer(s) and particulate reinforcement and an alkylsilane of the said formula (I), and
• (5) mixing said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide and said alkylsilane of formula (I) with said elastomer(s) and said particulate reinforcement, wherein said N-3-(1,2-dihydroxypropyl)-N-oleylammonium bromide or N-3-(1,2-dihydroxypropyl)-N-methyl-2-mercaptoimidazolium bromide and said alkylsilane of formula (I) have all been pre-reacted with
• (a) synthetic precipitated silica aggregates or
• (b) an aqueous dispersion of colloidal silica particles from which precipitated silica aggregates are recovered to form a silica composite thereof.