Rubber composition for a tire tread

• US 20050209413A1
• Filed: 01/31/2005
• Published: 09/22/2005
• Est. Priority Date: 07/29/2002
• Status: Active Grant

• Current Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Original Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Inventors: Mathieu, Samuel, Labauze, Gerard
• Granted Patent: US 7,084,228 B2
• Time in Patent Office: Days
• US Class Current: 525/333.300
• CPC Class Codes: C08K 5/0016 Plasticisers
• CPC Class Codes: C08L 21/00 Compositions of unspecified rubbers
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 2666/26 Natural polymers, natural resins or derivatives thereof according to C08L1/00 - C08L5/00, C08L89/00, C08L93/00, C08L97/00 or C08L99/00
• CPC Class Codes: C08L 45/00 Compositions of homopolymers or copolymers of compounds having no unsaturated aliphatic radicals in side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic or in a heterocyclic ring system; Compositions of derivatives of such polymers of cyclic anhydrides or imides C08L35/00; of cyclic esters of polyfunctional acids C08L31/00
• CPC Class Codes: C08L 47/00 Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds; Compositions of derivatives of such polymers C08L45/00 takes precedence; of conjugated diene rubbers C08L9/00 - C08L21/00
• CPC Class Codes: C08L 91/00 Compositions of oils, fats or waxes; Compositions of derivatives thereof
• CPC Class Codes: C08L 93/00 Compositions of natural resins; Compositions of derivatives thereof of polysaccharides C08L1/00 - C08L5/00; of natural rubber C08L7/00
• CPC Class Codes: Y10S 152/905 Tread composition

Abstract

A cross-linkable or cross-linked rubber composition usable to constitute a tire tread having improved wear resistance, to such a tread and to a tire incorporating this tread. The composition is particularly applicable to tires of passenger-vehicle type. The rubber composition includes a plasticizing resin of number-average molecular weight of from 400 to 2000 g/mol, the resin having units resulting from the polymerization of a monocyclic or bicyclic unsaturated terpene, in a mass fraction of from 70% to 100%, and having a glass transition temperature greater than 50° C. and less than 120° C.

Claims

1. A cross-linkable or cross-linked rubber composition comprising a plasticizing resin of number-average molecular weight of from 400 to 2000 g/mol, wherein said resin comprises units resulting from the polymerization of a monocyclic or bicyclic unsaturated terpene in a mass fraction of from 70% to 100%, and said resin has a glass transition temperature greater than 50°

C. and less than 120°

C.

2. The rubber composition according to claim 1, wherein said resin has a glass transition temperature of from 60°

C. to 100°

C.

3. The rubber composition according to claim 1, wherein said resin has a number-average molecular weight of from 500 to 1000 g/mol.

4. The rubber composition according to claim 1, wherein said resin has a polymolecularity index of less than 2.

5. The rubber composition according to claim 1, wherein said resin comprises units resulting from the polymerization of a monocyclic or bicyclic unsaturated terpene in a mass fraction of from 90 to 100%.

6. The rubber composition according to claim 1, wherein said unsaturated terpene is a monocyclic unsaturated terpene.

7. The rubber composition according to claim 6, wherein the monocyclic unsaturated terpene is limonene.

8. The rubber composition according to claim 6, wherein said resin has a glass transition temperature of from 60°

C. to 80°

C.

9. The rubber composition according to claim 6, wherein said resin further comprises at least one unit resulting from at least one comonomer which is not a monocyclic unsaturated terpene.

10. The rubber composition according to claim 9, wherein said at least one comonomer(s) is a bicyclic unsaturated terpene.

11. The rubber composition according to claim 9, wherein said at least one comonomer(s) is a monocyclic or polycyclic aromatic hydrocarbon.

12. The rubber composition according to claim 9, wherein said at least one comonomer is a cyclic diene.

13. The rubber composition according to claim 6, wherein said resin is formed wholly of said units resulting from the polymerization of said monocyclic unsaturated terpene.

14. The rubber composition according to claim 1, wherein said unsaturated terpene is a bicyclic unsaturated terpene.

15. The rubber composition according to claim 14, wherein said resin has a glass transition temperature of from 80°

C. to 100°

C.

16. The rubber composition according to claim 14, wherein said resin further comprises at least one unit resulting from at least one comonomer which is not a bicyclic unsaturated terpene.

17. The rubber composition according to claim 16, wherein said at least one comonomer(s) is a monocyclic unsaturated terpene.

18. The rubber composition according to claim 17, wherein said monocyclic unsaturated terpene is limonene.

19. The rubber composition according to claim 16, wherein said at least one comonomer(s) is a monocyclic or polycyclic aromatic hydrocarbon.

20. The rubber composition according to claim 14, wherein said resin is wholly formed of said units resulting from the polymerization of said bicyclic unsaturated terpene.

21. The rubber composition according to claim 1, based on at least one diene elastomer, said elastomer resulting from the polymerization of at least one conjugated diene monomer having a molar ratio of units resulting from conjugated dienes which is greater than 50%, wherein said resin is in a mass fraction of from 5 to 45 phr (phr:

parts by weight per hundred parts of elastomer(s)).

22. The rubber composition according to claim 21, wherein said resin is present in a quantity of from 15 to 30 phr.

23. The rubber composition according to claim 1, which further comprises, in a quantity of from 0 phr to 30 phr, at least one plasticizing oil extracted from petroleum of a paraffinic, aromatic or naphthenic nature.

24. The rubber composition according to claim 23, wherein the plasticizing oil(s) extracted from petroleum is present in a quantity of from 0 phr to 15 phr.

25. The rubber composition according to claim 24, which is totally devoid of plasticizing oil extracted from petroleum.

26. The rubber composition according to claim 1, said composition further comprising a reinforcing filler, wherein said reinforcing filler comprises a reinforcing inorganic filler in a mass fraction greater than 50%.

27. The rubber composition according to claim 26, wherein said reinforcing filler comprises a blend of said reinforcing inorganic filler with carbon black.

28. The rubber composition according to claim 1, which further comprises, in a quantity of from 10 phr to 40 phr, at least one plasticizing compound not extracted from petroleum of synthetic or natural origin, comprising at least one glycerol fatty acid triester, such that the whole constituted by said fatty acid comprises oleic acid in a mass fraction equal to or greater than 60%.

29. The rubber composition according to claim 1, wherein said composition comprises:

in a quantity greater than 40 phr and up to 100 phr, at least one diene elastomer having a glass transition temperature of between −

65°

C. and −

10°

C., and

in a quantity less than 60 phr and down to 0 phr, at least one diene elastomer having a glass transition temperature of between −

10°

C. and −

80°

C.

30. The rubber composition according to claim 29, wherein:

said diene elastomer(s) having a glass transition temperature of between −

65°

C. and −

10°

C. is selected from the group consisting of copolymers of styrene and butadiene prepared in solution, copolymers of styrene and butadiene prepared in solution, copolymers of styrene and butadiene prepared in emulsion, natural polyisoprenes, synthetic polyisoprenes having a cis-1,4 linkage content greater than 95%, copolymers of butadiene and isoprene, copolymers of styrene and isoprene, terpolymers of styrene, butadiene and isoprene and of a mixture of these elastomers, and

said diene elastomer(s) having a glass transition temperature of between −

110°

C. and −

80°

C. comprise polybutadienes having cis-1,4 linkage contents greater than 90%.

31. The rubber composition according to claim 30, which comprises a blend of a polybutadiene having a cis-1,4 linkage content greater than 90% as the diene elastomer having a glass transition temperature of between −

110°

C. and −

80°

C., and a copolymer of styrene and butadiene prepared in solution, as the diene elastomer having a glass transition temperature of between −

65°

C. and −

10°

C.

32. A tire tread, which comprises the cross-linkable or cross-linked rubber composition according to claim 1.

33. A tire, which comprises the tread according to claim 32.