TIRE PROVIDED WITH AN OUTER SIDEWALL COMPRISING A THERMOPLASTIC ELASTOMER COMPRISING AT LEAST ONE SATURATED ELASTOMER BLOCK

Abstract

A tire has an outer sidewall, said outer sidewall comprising at least one composition comprising an elastomeric matrix which predominantly comprises by weight one or more thermoplastic elastomers comprising at least one elastomer block and at least one thermoplastic block, the elastomer block(s) being saturated.

Claims

1.-15. (canceled)

16. A tire comprising an outer sidewall, wherein the outer sidewall comprises at least one composition comprising an elastomeric matrix which predominantly comprises by weight at least one thermoplastic elastomer comprising at least one elastomer block and at least one thermoplastic block, the at least one elastomer block being saturated.

17. The tire according to claim 16, wherein the at least one thermoplastic elastomer has a glass transition temperature of less than or equal to 25 C.

18. The tire according to claim 16, wherein a number-average molecular weight of the at least one thermoplastic elastomer is between 30,000 and 500,000 g/mol.

19. The tire according to claim 16, wherein the at least one elastomer block is selected from the group consisting of ethylenic elastomers, polyethers and mixtures thereof.

20. The tire according to claim 19, wherein the at least one elastomer block is selected from the group consisting of polyethers, ethylene/propylene copolymers, ethylene/butylene copolymers, and mixtures thereof.

21. The tire according to claim 16, wherein the at least one thermoplastic block is selected from the group consisting of polyolefins, polyurethanes, polyamides, polyesters, polyacetals, polyethers, polyphenylene sulfides, polyfluorinated compounds, polystyrenes, polycarbonates, polysulfones, polymethyl methacrylate, polyetherimide, thermoplastic copolymers, and mixtures thereof.

22. The tire according to claim 21, wherein the at least one thermoplastic block is selected from the group consisting of polystyrenes, polyesters, polyamides, polyurethanes, and mixtures thereof.

23. The tire according to claim 22, wherein the at least one thermoplastic block is selected from the group consisting of polystyrenes, polyesters, polyamides, and mixtures thereof.

24. The tire according to claim 16, wherein the at least one thermoplastic elastomer is selected from the group consisting of the following linear or star-branched diblock or triblock copolymers: styrene/ethylene/butylene (SEB), styrene/ethylene/propylene (SEP), styrene/ethylene/ethylene/propylene (SEEP), styrene/ethylene/butylene/styrene (SEBS), styrene/ethylene/propylene/styrene (SEPS), styrene/ethylene/ethylene/propylene/styrene (SEEPS), styrene/isobutylene (SIB), styrene/isobutylene/styrene (SIBS), and mixtures thereof.

25. The tire according to claim 16, wherein a weight content of styrene in the at least one thermoplastic block is less than or equal to 15%.

26. The tire according to claim 16, wherein a content of the at least one thermoplastic elastomer ranges from 65 to 100 phr.

27. The tire according to claim 16, wherein the at least one thermoplastic elastomer is the only elastomer of the elastomeric matrix.

28. The tire according to claim 16, wherein the at least one composition comprises at least one reinforcing filler.

29. The tire according to claim 28, wherein the at least one reinforcing filler is carbon black, silica, or a combination of carbon black and silica.

30. The tire according to claim 16, wherein the at least one composition does not contain a crosslinking system.

Description

EXAMPLES

[0162] 1) Preparation of the Compositions

[0163] A composition that can be used in the tyre according to the invention (composition B) and a composition that can be used in a comparative tyre (composition A) were prepared using the ingredients and the contents in Table I below. The contents are expressed in phr.

TABLE-US-00001 TABLE I Ingredients A (Comp.) B (Inv.) Butadiene rubber.sup.(1) 65 Natural rubber 35 SEBS.sup.(2) 100 Carbon black.sup.(3) 50 Plasticizer.sup.(4) 15 Antioxidant 1.sup.(5) 1.5 Ozone wax 1 Stearic acid 1 Zinc oxide 2.4 Sulfur 1.4 Vulcanization 1.4 accelerator.sup.(6) .sup.(1)BR ND ML63, .sup.(2)Block copolymer comprising 13% by weight of styrene of the Tuftec H1221 series from the company Asahi Kase, .sup.(3)Carbon black of the N550 series from the company Cabot, .sup.(4)Catenex SNR MES oil from the company Shell, .sup.(5)Santoflex 6PPD antioxidant from the company Solutia, .sup.(6)Santocure CBS accelerator from the company Solutia.

[0164] 2) Preparation of the Tyres

[0165] Composition A was prepared in appropriate mixers, using two successive phases of preparation according to a general procedure well known to those skilled in the art: a first phase of thermomechanical working or kneading (sometimes referred to as non-productive phase) at high temperature, up to a maximum temperature of 140 C., followed by a second phase of mechanical working (sometimes referred to as productive phase) at a lower temperature of 60 C., during which finishing phase the crosslinking system is incorporated.

[0166] In this instance, the processing of the elastomeric composition is carried out by means of an external mixer.

[0167] The composition is then extruded by means of a twin-screw or single-screw extruder. An outer sidewall comprising composition A was obtained. Said outer sidewall is then mounted on a tyre.

[0168] Composition B is prepared by extrusion blow-moulding or injection-moulding from a raw material available in the form of balls or granules, in this case by means of a twin-screw extruder at the minimum temperature of 160 C. An outer sidewall comprising composition B was obtained. Said outer sidewall is then mounted on a tyre.

[0169] Thus, the tyre provided with an outer sidewall comprising composition A is called tyre A. The tyre provided with the outer sidewall comprising composition B is called tyre B.

[0170] 3) Tests

[0171] Statistical Ozone Test

[0172] The two tyres A and B are mounted and inflated, then subjected to load and placed in a cell under an ozone atmosphere for 15 days. The ozone concentration in the cell is maintained at 40 ppm and the temperature is 40 C.

[0173] The tyres are arrowed at 20% deformation for the sidewall portion.

[0174] Rolling Resistance

[0175] The rolling resistance of the tyres is measured on a flywheel, according to method ISO 87-67 (1992).

[0176] 4) Results

[0177] The results of the two tests are collated in Table II below.

TABLE-US-00002 TABLE II Tyre A (comparative) B (invention) Ozone test Numerous cracks No crack Rolling resistance 8.15 7.98 (kg/t)

[0178] It can be noted that tyre B according to the invention has an improved ozone resistance compared with the reference tyre. In addition, tyre B according to the invention has an improved rolling resistance compared with the reference tyre.