Patent ID: 6465544
Filing Date: 2002-10-15
Classification: B60C,C08K,C08L,Y02T

Abstract:
A process for delaying the scorching and/or improving the hysteretic properties of a rubber composition including a diene elastomer, silica as a reinforcing filler, and a crosslinking system, which process includes adding and incorporating into the rubber composition comprising a diene elastomer and silica by thermomechanical working a reinforcing additive comprising a mixture and/or product of in situ reaction of(i) at least one functionalized polyorganosiloxane compound containing, per molecule, at least one functional siloxy unit capable of bonding chemically and/or physically with the surface hydroxyl sites of the silica particles and (ii) at least one functionalized organosilane compound, per molecule, at least one functionalized group capable of bonding chemically and/or physically with the polyorganosiloxane and/or hydroxyl sites of the silica particles and at least one other functional group capable of bonding chemically and/or physically to the chains of the diene elastomer, â€ƒwherein the diene elastomer is selected from the group consisting of butadiene-styrene copolymer, butadiene-styrene-isoprene copolymer, polybutadiene, polyisoprene, natural rubber, and a blend of two or more of these diene elastomers, â€ƒwherein the functionalized polyorganosiloxane compound is chosen from the following compounds: (A) the compounds comprising, per molecule, a functional unit selected from the group consisting of: &agr;-at least one functional siloxy unit of the following formula (I): (R)a Y Si(O)(3âˆ’a)/2â€ƒâ€ƒ(I) â€ƒin which: a=0, 1 or 2; R is a monovalent hydrocarbon radical chosen from linear or branched alkyls containing from 1 to 6 carbon atoms or from aryls, the radicals R being identical or different when a=2; and Y is a C1-C15 linear or branched alkoxy radical; &bgr;-at least one functional siloxy unit of the following formula (II): (R)b W Si(O)(3âˆ’b)/2â€ƒâ€ƒ(II) â€ƒin which: b=0, 1 or 2; R corresponds to the same definition as that given above for the substituent R of formula (I) and may be identical with or different from the latter; and W is a monovalent hydrocarbon radical containing from 2 to 30 carbon atoms and constituting a functional residue bonded to silicon by an Siâ€”C bond, this residue being chosen from the following groups: â€ƒ(i) a linear or branched alkyl group containing at least 7 carbon atoms; â€ƒ(ii) a linear or branched C2-C20 alkenyl group containing one or more double bonds in and/or at the end(s) of the chain(s); or â€ƒ(iii) a saturated or unsaturated aliphatic mono- or polycyclic group containing 5 to 20 carbon atoms and one or more ethylenic double bonds in the ring(s); and &ggr;-at least one siloxy unit of the following formula (III): (R)c (H)d Si(O)(4âˆ’(c+d))/2â€ƒâ€ƒ(III) â€ƒin which: c=0, 1, 2 or 3, d=1 and c+d&lE;3; and the substituent R being as defined above in formula (I) and (II); (B) the compounds of formula (IV): â€ƒin which: R is a monovalent hydrocarbon radical chosen from linear or branched alkyls containing from 1 to 6 carbon atoms or from aryls or a linear or branched C2-C20 alkenyl group containing one or more double bonds; the various exemplars of R may be identical with or different from each other; x=0 to 500; and F and Fâ€² are monovalent radicals chosen from hydrogen, the halogens, those corresponding to the definition of R, hydroxyl, alkoxy, enoxy, acyloxy, acetoxy, oxime and amine functional groups; F and Fâ€² may be different or identical, but in the latter case it must not be the radical R; and (C) polyorganosiloxane resins containing monovalent radicals and/or reactive functional groups F and Fâ€², these symbols having the same definition as that given above to formula (IV).