Patent ID: 6525128
Filing Date: 2003-02-25
Classification: B60C,C08K,C08L,Y10T

Abstract:
A rubber composition which comprises, based upon parts by weight of ingredient per 100 parts by weight elastomer(s), (phr):(A) 100 phr of elastomer comprised of (1) about 5 to about 100 phr of a halogenated copolymer of isobutylene and p-methyl styrene, wherein said halogen is selected from bromine or iodine, (2) from zero to about 95 phr of at least one diene-based elastomer and (B) about 10 to about 100 phr of particulate reinforcing filler comprised of (1) from zero to about 100 phr of synthetic amorphous silica aggregates and, correspondingly, (2) from zero to about 75 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 on their surface; and (C) 0.5 to 25 phr of an organo phosphite as a coupling agent selected from at least one of organo diphosphites selected from diisodecyl pentearythritol diphosphite, distearyl pentaerythritol diphosphite and pentearythritol diphosphite and organo monophosphites selected from the general formulas: ((OR)2â€”Pâ€”Oâ€”Râ€²)2â€”Râ€³â€ƒâ€ƒ(II) wherein each R radical is independently selected from alkyl radicals and phenyl radicals and alkyl substituted phenyl radicals; wherein said R alkyl radicals have from 1 to 18 carbon atoms, preferably from 1 through 4 or from 4 through 8, carbon atoms, and preferably selected from methyl, ethyl, propyl radicals, from propyl, butyl, octyl and ethylhexyl radicals or from phenyl radicals; wherein said alkyl radicals for said alkyl substituted phenyl radicals have from 3 to 9 carbon atoms, wherein Râ€² is a phenyl radical and wherein Râ€³ is selected from alkyl radicals having from 2 to 8 carbon atoms preferably selected from ethyl, propyl and butyl radicals; wherein said organo phosphite is provided by one or more of the following: (1) by mixing said organo phosphite with said elastomer(s) and said synthetic silica particulate reinforcement, (2) by pre-reacting said halogenated copolymer of isobutylene and p-methyl styrene with said organo phosphite prior to blending said reinforcing filler therewith, (3) by pre-reacting said organo phosphite with an aqueous dispersion of colloidal silica particles from which a precipitated silica is recovered to form an organo phosphite/silica composite thereof, (4) by mixing said organo phosphite with said elastomer(s) and said synthetic silica according to any of said steps (1), (2) or (3), wherein said synthetic silica includes at least one of said pre-hydrophobated silica aggregates which has been pre-hydrophobated prior to mixing with said elastomers, with an alkylsilane of the general formula (III): Xnâ€”Siâ€”R4-nâ€ƒâ€ƒ(III) 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, (5) by mixing said organo phosphite with said elastomer(s) and an alkylsilane of the said Formula (III) with said elastomer(s) and said synthetic silica, and (6) by pre-reacting said organo phosphite and said alkylsilane of Formula (III) with (a) said aggregates of synthetic precipitated silica or (b) an aqueous dispersion of colloidal silica particles from which a precipitated silica is recovered to form a silica composite thereof.