PNEUMATIC TIRE COMPRISING A TREAD COMPRISING A THERMOPLASTIC ELASTOMER AND A CROSS-LINKING SYSTEM BASED ON AT LEAST ONE PEROXIDE

Abstract

A tire (1) comprises a tread (3), a crown with a crown reinforcement (2), two sidewalls (5), two beads (4), a carcass reinforcement (6) anchored to the two beads (4) and extending from one sidewall (5) to the other, the tread comprising (a) an elastomeric matrix which comprises predominantly one or more thermoplastic elastomers comprising at least one elastomer block and at least one thermoplastic block, and (b) a crosslinking system based on one or more peroxides. The invention also relates to a process for preparing the retire.

Claims

1.-19. (canceled)

20. A tire comprising a tread, a crown with a crown reinforcement, two sidewalls, two beads, a carcass reinforcement anchored to the two beads and extending from one sidewall to the other, wherein the tread comprises: (a) an elastomeric matrix comprising predominantly at least one thermoplastic elastomer comprising at least one elastomer block and at least one thermoplastic block; and (b) a crosslinking system based on at least one peroxide.

21. The tire according to claim 20, wherein the at least one thermoplastic elastomer has a glass transition temperature below or equal to 25 C.

22. The tire according to claim 21, wherein the at least one thermoplastic elastomer has a glass transition temperature below or equal to 10 C.

23. The tire according to claim 20, wherein the number-average molecular weight of the at least one thermoplastic elastomer is between 30,000 and 500,000 g/mol.

24. The tire according to claim 23, wherein the number-average molecular weight of the at least one thermoplastic elastomer is between 40,000 and 400,000 g/mol.

25. The tire according to claim 24, wherein the number-average molecular weight of the at least one thermoplastic elastomer is between 50,000 and 300,000 g/mol.

26. The tire according to claim 20, wherein the at least one elastomer block of the at least one thermoplastic elastomer is selected from the group consisting of ethylenic elastomers, polyethers, partially hydrogenated diene elastomers, completely hydrogenated diene elastomers, and mixtures thereof.

27. The tire according to claim 26, wherein the at least one elastomer block of the at least one thermoplastic elastomer is selected from the group consisting of polyisoprenes, polybutadienes, butadiene-isoprene copolymers, polyethers, ethylene-butylene copolymers, partially hydrogenated styrene-butadiene copolymers, completely hydrogenated styrene-butadiene copolymers, and mixtures thereof.

28. The tire according to claim 20, wherein the at least one thermoplastic block of the at least one thermoplastic elastomer 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.

29. The tire according to claim 20, wherein the at least one thermoplastic block of the at least one thermoplastic elastomer is selected from the group consisting of polystyrenes, polyesters, polyamides, polyurethanes, and mixtures thereof.

30. The tire according to claim 29, wherein the at least one thermoplastic block of the at least one thermoplastic elastomer is selected from the group consisting of polystyrenes, polyesters, polyamides, and mixtures thereof.

31. The tire according to claim 20, wherein the at least one thermoplastic elastomer is selected from the group consisting of styrene/ethylene/butylene/styrene (SEBS), polyether/polyester (COPE), polyether/polyamide (PEBA), styrene/butadiene/styrene (SBS), styrene/isoprene/styrene (SIS), styrene/butadiene/isoprene/styrene (SBIS), styrene/optionally hydrogenated butadiene-styrene copolymer/styrene (SOE), styrene/partially hydrogenated butadiene/styrene (SBBS) block copolymers, and mixtures thereof.

32. The tire according to claim 20, wherein the thermoplastic elastomer content of the elastomeric matrix of the tread varies from 65 to 100 phr.

33. The tire according to claim 32, wherein the thermoplastic elastomer content of the elastomeric matrix of the tread varies from 70 to 100 phr.

34. The tire according to claim 33, wherein the thermoplastic elastomer content of the elastomeric matrix of the tread varies from 75 to 100 phr.

35. The tire according to claim 34, wherein the thermoplastic elastomer content of the elastomeric matrix of the tread varies from 95 to 100 phr.

36. The tire according to claim 20, wherein the at least one thermoplastic elastomer is the only elastomer in the elastomeric matrix of the tread.

37. The tire according to claim 20, wherein the at least one peroxide is selected from the group consisting of dialkyl peroxides, diacyl peroxides, acetal peroxides, ester peroxides, hydroperoxides and mixtures thereof.

38. The tire according to claim 37, wherein the at least one peroxide is selected from the group consisting of dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and mixtures thereof.

39. The tire according to claim 20, wherein the peroxide content of the tread ranges from 0.1 to 10 phr.

40. The tire according to claim 39, wherein the peroxide content of the tread ranges from 0.2 to 6 phr.

41. The tire according to claim 40, wherein the peroxide content of the tread ranges from 0.5 to 5 phr.

42. The tire according to claim 20, wherein the tread additionally comprises at least one plasticizing agent.

43. The tire according to claim 42, wherein the at least one plasticizing agent is selected from the group consisting of plasticizing resins and plasticizing oils.

44. The tire according to claim 42, wherein the at least one plasticizing agent is a liquid paraffin.

45. The tire according to claim 20, wherein the tread contains less than 0.3 phr of molecular sulfur or a sulfur donor.

46. The tire according to claim 45, wherein the tread contains less than 0.1 phr of molecular sulfur or a sulfur donor.

47. The tire according to claim 20, wherein the tread does not contain molecular sulfur or a sulfur donor.

48. The tire according to claim 20, wherein the tread does not contain a vulcanization accelerator.

49. The tire according to claim 20, wherein the tread does not contain an antioxidant agent.

50. A process for preparing the tire according to claim 20 comprising the following steps: extruding the tread; then placing the extruded tread on the tire; and then curing the tire.

Description

EXAMPLES

Example 1: Tyre Based on an SIS Thermoplastic Elastomer (Kraton D1161)

[0217] A comparative tread composition AO and tread compositions that may be used in a tyre according to the invention A1 to A4 were prepared by blending in an internal mixer of the tread without the crosslinking system (peroxide) and then introduction into the external mixer of the crosslinking system, on the basis of table 1 below. The values are indicated in phr.

TABLE-US-00001 TABLE 1 Tread A0 A1 A2 A3 A4 SIS.sup.(1) 100 100 100 100 100 Dicumyl peroxide 1.7 3.4 5.1 2,5-dimethyl-2,5-di(t- 1.8 butylperoxy)hexane.sup.(2) .sup.(1)SIS thermoplastic elastomer, Kraton D1161, from Kaneka; .sup.(2)Luperox 101 from Arkema.

[0218] The G(T) moduli at 40 C. and 200 C. of the treads AO to A4 were measured.

[0219] The results are presented in Table 2 below.

TABLE-US-00002 TABLE 2 Ratio Ratio (G(200 C.)/G(40 C.)) (G(200 C.)/G(40 C.)) Tread 100 in % relative to A0 A0 8.8 100 A1 99.0 1126 A2 112.9 1284 A3 125.6 1429 A4 104.5 1189

[0220] It is found that all the formulations containing a peroxide show an improvement in the heat resistance.

Example 2: Tyre Based on an SIS Thermoplastic Elastomer (Hybrar 5125 from the Company Kuraray)

[0221] A comparative tread composition BO and tread compositions that may be used in a tyre according to the invention B1 to B4 were prepared by blending in an internal mixer the tread without the crosslinking system (peroxide) followed by introduction into the external mixer of the crosslinking system, on the basis of table 3 below. The values are indicated in phr.

TABLE-US-00003 TABLE 3 Tread B0 B1 B2 B3 SIS.sup.(1) 100 100 100 100 Dicumyl peroxide 1.6 3.2 2,5-Dimethyl-2,5-bis(t- 1.7 butylperoxy)hexane.sup.(2) .sup.(1)SIS thermoplastic elastomer Hybrar 5125 from the company Kuraray .sup.(2)Luperox 101 from the company Arkema

[0222] The moduli G(T) at 40 C. and 200 C. of the treads BO to B3 were measured.

[0223] The results are presented in table 4 below.

TABLE-US-00004 TABLE 4 Ratio Ratio (G(200 C.)/G(40 C.)) (G(200 C.)/G(40 C.)) in Tread 100 % relative to B0 B0 3.9 100 B1 21.7 552 B2 20.0 509 B3 21.3 542

[0224] It is found that all the formulations containing a peroxide show an improvement in the heat resistance.

Example 3: Tyre Based on an S-SBR(Hydrogenated)-S Thermoplastic Elastomer

[0225] A comparative tread composition C0 and tread compositions that may be used in a tyre according to the invention C1 to C4 were prepared by blending in an internal mixer the tread without the crosslinking system (peroxide) followed by introduction into the external mixer of the crosslinking system, on the basis of table 5 below. The values are indicated in phr.

TABLE-US-00005 TABLE 5 Tread C0 C1 C2 C3 C4 S-SBS-S.sup.(1) 100 100 100 100 100 Dicumyl peroxide 1 2 3 2,5-Dimethyl-2,5-bis(t- 1.1 butylperoxy)hexane.sup.(2) .sup.(1)S-SBS(hydrogenated)-S thermoplastic elastomer SOE L606 from the company Asahi Kasei .sup.(2)Luperox 101 from the company Arkema

[0226] The moduli G(T) at 40 C. and 200 C. of the treads C0 to C4 were measured.

[0227] The results are presented in table 6 below.

TABLE-US-00006 TABLE 6 Ratio Ratio (G(200 C.)/G(40 C.)) (G(200 C.)/G(40 C.)) in Tread 100 % relative to C0 C0 9.4 100 C1 18.0 191 C2 26.1 277 C3 42.2 447 C4 18.7 198

[0228] It is found that all the formulations containing a peroxide show an improvement in the heat resistance.

Example 4: Tyre Based on an SEBS Thermoplastic Elastomer

[0229] A comparative tread composition DO and tread compositions that may be used in a tyre according to the invention D1 to D4 were prepared by blending in an internal mixer the tread without the crosslinking system (peroxide) followed by introduction into the external mixer of the crosslinking system, on the basis of table 7 below. The values are indicated in phr.

TABLE-US-00007 TABLE 7 Tread D0 D1 D2 D3 D4 SEBS.sup.(1) 100 100 100 100 100 Dicumyl peroxide 1.4 2.8 4.2 2,5-Dimethyl-2,5-bis(t- 1.5 butylperoxy)hexane.sup.(2) .sup.(1)SEBS thermoplastic elastomer Septon 8076 from the company Kuraray .sup.(2)Luperox 101 from the company Arkema

[0230] The moduli G(T) at 40 C. and 200 C. of the treads DO to D4 were measured.

[0231] The results are presented in table 8 below.

TABLE-US-00008 TABLE 8 Ratio Ratio (G(200 C.)/G(40 C.)) (G(200 C.)/G(40 C.)) in Tread 100 % relative to D0 D0 0.7 100 D1 2.0 281 D2 6.1 877 D3 10.6 1515 D4 2.8 397

[0232] It is found that all the formulations containing a peroxide show an improvement in the heat resistance.

Example 5: Tyre Based on an SEBS Thermoplastic Elastomer

[0233] A comparative tread composition E0 and tread compositions that may be used in a tyre according to the invention E1 to E4 were prepared by blending in an internal mixer the tread without the crosslinking system (peroxide) followed by introduction into the external mixer of the crosslinking system, on the basis of table 9 below. The values are indicated in phr.

TABLE-US-00009 TABLE 9 Tread E0 E1 E2 E3 E4 SEBS.sup.(1) 100 100 100 100 100 Dicumyl peroxide 1.4 2.8 4.2 2,5-Dimethyl-2,5-bis(t- 1.5 butylperoxy)hexane.sup.(2) .sup.(1)SEBS thermoplastic elastomer Septon V9827 from the company Kuraray .sup.(2)Luperox 101 from the company Arkema

[0234] The moduli G(T) at 40 C. and 200 C. of the treads E0 to E4 were measured.

[0235] The results are presented in table 10 below.

TABLE-US-00010 TABLE 10 Ratio Ratio (G(200 C.)/G(40 C.)) (G(200 C.)/G(40 C.)) in Tread 100 % relative to E0 E0 3.6 100 E1 11.2 307 E2 19.4 534 E3 31.4 863 E4 14.8 407

[0236] It is found that all the formulations containing a peroxide show an improvement in the heat resistance.

[0237] Thus, these results for five types of thermoplastic elastomers reveal much less flow at high temperature for the treads comprising a peroxide relative to a comparative tread not comprising any.

[0238] Thus, it is found that the treads comprising a peroxide show an improvement in the heat resistance relative to treads not comprising any.