RUBBER COMPOSITION COMPRISING A POLYPHENYLENE ETHER RESIN

Abstract

A rubber composition is based on at least one predominant vinylaromatic diene elastomer, having a vinylaromatic content of less than 10%; from 3 to 50 phr of a thermoplastic resin, denoted PPE resin, comprising optionally substituted polyphenylene ether units, the resin having a number-average molecular weight (Mn) of less than 6000 g/mol; from 5 to 60 phr of silica as predominant reinforcing filler; and a crosslinking system. Also disclosed are rubber articles comprising such a composition and in particular tires.

Claims

1.-14. (canceled)

15. A rubber composition based on at least: a predominant vinylaromatic diene elastomer, having a vinylaromatic content of less than 10%; 3 to 50 phr of a thermoplastic PPE resin comprising optionally substituted polyphenylene ether units, the thermoplastic PPE resin having a number-average molecular weight (Mn) of less than 6000 g/mol; 5 to 60 phr of silica as predominant reinforcing filler; and a crosslinking system.

16. The rubber composition according to claim 15, wherein the vinylaromatic diene elastomer is selected from the group consisting of butadiene/styrene copolymers, isoprene/styrene copolymers and butadiene/isoprene/styrene copolymers and mixtures thereof.

17. The rubber composition according to claim 15, wherein the vinylaromatic diene elastomer present has a vinylaromatic content of between 0% and 5% by weight and a Tg within a range extending from −110° C. to −70° C.

18. The rubber composition according to claim 15, wherein a content of vinylaromatic diene elastomer is within a range extending from 70 to 100 phr, parts by weight per hundred parts of elastomer.

19. The rubber composition according to claim 15, wherein a content of vinylaromatic diene elastomer is 100 phr.

20. The rubber composition according to claim 15, wherein the thermoplastic PPE resin has a number-average molecular weight (Mn) of less than 3500 g/mol.

21. The rubber composition according to claim 15, wherein the thermoplastic PPE resin has a glass transition temperature (Tg), measured by DSC according to Standard ASTM D3418 of 1999, within a range extending from 0 to 170° C.

22. The rubber composition according to claim 15, wherein the thermoplastic PPE resin is a compound comprising predominantly polyphenylene units of general formula (I): ##STR00002## in which: R.sub.1, R.sub.2, R.sub.3 and R.sub.4 represent, independently of one another, identical or different groups selected from hydrogen, hydroxy, alkoxy, halogen, amino, alkylamino groups, dialkylamino groups and hydrocarbon-based groups comprising at least 1 carbon atom, optionally interrupted by heteroatoms and optionally substituted; R.sub.1 and R.sub.3 on the one hand, and R.sub.2 and R.sub.4 on the other, possibly forming, together with the carbon atoms to which they are attached, one or more rings fused to the benzene ring of the compound of formula (I), and n is an integer within a range extending from 3 to 300.

23. The rubber composition according to claim 22, wherein the thermoplastic PPE resin is a compound comprising predominantly polyphenylene units of general formula (I) in which R.sub.1, R.sub.2, R.sub.3 and R.sub.4 represent, independently of one another, identical or different groups selected from: hydrogen, hydroxyl groups, alkoxy groups comprising from 1 to 6 carbon atoms, halogen groups, amino groups, alkylamino groups comprising from 1 to 6 carbon atoms and dialkylamino groups comprising from 2 to 12 carbon atoms, linear, branched or cyclic alkyl groups, comprising from 1 to 12 carbon atoms, which are optionally interrupted by heteroatoms and optionally substituted by hydroxyl groups, alkoxy groups comprising from 1 to 6 carbon atoms, amino groups, alkylamino groups comprising from 1 to 6 carbon atoms, dialkylamino groups comprising from 2 to 12 carbon atoms, and halogen groups, and aryl groups comprising from 6 to 18 carbon atoms which are optionally substituted by hydroxyl groups, alkoxy groups comprising from 1 to 6 atoms, amino groups, alkylamino groups comprising from 1 to 6 atoms, dialkylamino groups comprising from 2 to 12 carbon atoms, alkyl groups comprising from 1 to 12 carbon atoms, and halogen groups.

24. The rubber composition according to claim 22, wherein R.sub.1 and R.sub.2 represent an alkyl group and R.sub.3 and R.sub.4 represent hydrogen atoms.

25. The rubber composition according to claim 15, wherein the content of the thermoplastic PPE resin is within a range extending from 3 to 40 phr.

26. The rubber composition according to claim 15, wherein the content of silica is within a range extending from 10 to 50 phr.

27. A finished or semi-finished rubber item comprising the rubber composition according to claim 15.

28. A tire comprising the rubber composition according to claim 15.

Description

EXAMPLES OF IMPLEMENTATION OF THE INVENTION

A. Preparation of the Compositions

[0096] The compositions presented below were prepared according to the procedure described above, in two steps, non-productive step then productive step.

[0097] The profiled compositions were optimally crosslinked at a temperature of 160° C.

B. Tests

[0098] The rubber compositions can be characterized by their breaking properties, measured as indicated below, representative of the properties observed in tires, in particular for wear resistance and endurance.

[0099] The tensile tests make it possible to determine the moduli of elasticity and the properties at break and are based on Standard NF ISO 37 of December 2005.

[0100] The nominal secant modulus (or apparent stress, in MPa, relative to the strain, which is unitless) is measured at 23° C. in second elongation (i.e., after an accommodation cycle at the degree of extension provided for the measurement itself) at 10% elongation (denoted MA10).

[0101] The stress, in MPa, and the strain at break, in %, are measured at 23° C.

[0102] For better readability in the presentation of the results below and easier comparison, the results are given in base 100, the value 100 being set for the control. A result greater than 100 in stress at break or in strain at break indicates an increased value and therefore an improved performance in terms of stress at break or of strain at break, for the composition compared with the control.

C. Testing on Rubber Compositions

[0103] Control compositions T1 to T3 are compositions comprising an SBR with a styrene content greater than 10% and/or not comprising any PPE resin. Compositions of this type are known to those skilled in the art in the field of tires. The composition Cl is in accordance with the invention. The formulations (in phr or parts by weight per hundred parts by weight of elastomer) have been represented in Table 1 below.

TABLE-US-00001 TABLE 1 Composition T1 T2 T3 C1 SBR A (1) 100 100 — — SBR B (2) — — 100 100 Silica (3) 26.3 28 26.3 28 Silane (4) 2 2.3 2 2.3 PPE (5) — 6.8 — 6.8 Zinc oxide (6) 3 3 3 3 Stearic acid (7) 2.5 2.5 2.5 2.5 Accelerator (8) 2.5 2.5 2.5 2.5 Sulfur 1 1 1 1

[0104] SBR A with 15% of styrene units and 24% of 1,2-units for the butadiene part (Tg, measured by DSC according to Standard ASTM D3418, 1999, of −65° C.); SBR B with 3% of styrene units and 12% of 1,2-units for the butadiene part (Tg, measured by DSC according to Standard ASTM D3418, 1999, of −88° C.);

[0105] Z1165MP silica from Solvay;

[0106] TESPT SI69 silane coupling agent from Evonik;

[0107] PPE resin: Poly(2,6-dimethyl-1,4-phenylene ether): Noryl SA90 from Sabic, Mn=2350 g/mol; Zinc oxide (industrial grade—Umicore)

[0108] Stearin (Pristerene 4931 from Uniqema)

[0109] N-cyclohexylbenzothiazolesulfenamide (Santocure CBS from Flexsys).

[0110] The properties of the compositions are represented in Table 2 below.

TABLE-US-00002 TABLE 2 Composition T1 T2 T3 C1 stress at break 23° C. base 100 100 96 100 150 strain at break 23° C. base 100 100 74 100 131

[0111] It is noted that the composition Cl makes it possible to improve both the stress at break and the strain at break compared to the control T3, by virtue of the synergy of an SBR having a styrene content of less than 10% and of a PPE resin. This effect is not produced by the PPE resin in the presence of an SBR having a styrene content greater than 10% as shown by the comparison of T1 and T2. The invention therefore makes it possible to obtain improved tear resistance, better wear resistance and good endurance.