RUBBER COMPOSITION AND TIRE

Abstract

The present invention is directed to a rubber composition comprising 10 phr to 100 phr of at least one partially saturated elastomer comprising repeat units, wherein at most 15% of all repeat units of the elastomer comprise a double bond; 0 phr to 90 phr of at least one diene based elastomer; 40 phr to 200 phr of at least one filler; and at least 5 phr of aluminum hydroxide.

Claims

1. A sulfur vulcanizable rubber composition comprising: 10 phr to 100 phr of at least one partially saturated elastomer comprising repeat units, wherein at most 15% of all repeat units of the elastomer comprise a double bond; 0 phr to 90 phr of at least one diene based elastomer; 40 phr to 200 phr of at least one filler; and at least 5 phr of aluminum hydroxide.

2. The rubber composition according to claim 1 wherein at most 8% of all repeat units have a double bond.

3. The rubber composition according to claim 1 wherein at least 4% of the repeat units have a double bond.

4. The rubber composition according to claim 1 wherein said filler comprises one or more of: (i) from 35 phr to 190 phr of silica, (ii) predominantly silica, (iii) silica with a BET surface area within a range of 150 m.sup.2/g to 250 m.sup.2/g, and (iv) less than 10 phr carbon black.

5. The rubber composition according to claim 1 wherein the aluminum hydroxide has one or more of: (i) a D50 particle diameter within a range of 0.2 μm and 30 μm, and (ii) a BET surface area within a range of 1 m.sup.2/g to 20 m.sup.2/g.

6. The rubber composition according to claim 1 comprising from 30 phr to 80 phr of the aluminum hydroxide.

7. The rubber composition according to claim 1 wherein the partially saturated elastomer comprises repeat units formed by residues of monomers selected from ethylene, propylene, butadiene, isoprene, and styrene.

8. The rubber composition according to claim 1 wherein the partially saturated elastomer is a hydrogenated styrene butadiene rubber.

9. The rubber composition according to claim 1 further comprising from 3 phr to 20 phr of a polyoctenamer.

10. The rubber composition according to claim 9 wherein the polyoctenamer has one or more of: a glass transition temperature within a range of −50° C. to −80° C.; a molecular weight Mw within a range of 80,000 to 100,000 g/mol, determined by GPC; a melting point within a range of 45° C. to 55° C., measured by DSC in a second heating; and between 65% and 85% of trans double bonds.

11. The rubber composition according to claim 1, comprising 80 phr to 100 phr of the partially saturated elastomer, and 0 phr to 20 phr of one or more of polybutadiene and polyisoprene.

12. The rubber composition according to claim 11 wherein the rubber composition comprises from 80 phr to 95 phr of the partially saturated elastomer and from 5 phr to 20 phr of the polybutadiene, and wherein the polybutadiene has a glass transition temperature within a range of −90° C. to −115° C.

13. The rubber composition according to claim 11 wherein the rubber composition comprises from 80 phr to 95 phr of the partially saturated elastomer and from 5 phr to 20 phr of the polyisoprene.

14. The rubber composition according to claim 1, wherein the partially saturated elastomer has one or more of: a glass transition temperature within a range of −20° C. to −60° C.; and a molecular weight Mw within a range of 200,000 g/mol to 500,000 g/mol.

15. The rubber composition according to claim 1, wherein the partially saturated elastomer is a solution-polymerized styrene butadiene rubber having one or more of: (i) less than 5% of nonhydrogenated vinyl groups, based on the total number of vinyl groups of the hydrogenated styrene butadiene rubber; (ii) less than 20% of nonhydrogenated double bonds in cis-1,4 and trans-1,4 butadiene repeat units, based on the total number of cis-1,4 and trans-1,4 butadiene repeat units; (iii) from 80% to 99% of hydrogenated double bonds; (iv) a bound styrene content ranging from 5% to 40% and a butadiene content ranging from 50% to 95%, by weight; and (v) a molecular weight Mw within a range of 200,000 g/mol to 500,000 g/mol.

16. The rubber composition according to claim 1 wherein the rubber composition comprises: from 5 phr to 50 phr of at least one plasticizer chosen from one or more of at least one oil and at least one resin.

17. The rubber composition according to claim 1 wherein the rubber composition comprises at least 3 phr of at least one mercapto silane.

18. The rubber composition according to claim 1 wherein the rubber composition further comprises a resin selected from one or more of DCPD resins, CPD resins, terpene resins, C5 resins, C9 resins, coumarone indene resin, styrene-alphamethylstyrene or combinations of those.

19. The rubber composition according to claim 1 further comprising 0.3 phr to 3 phr of a vulcanization accelerator selected from one or more of dithiocarbamate accelerators and thiuram accelerators.

20. A tire comprising the rubber composition of claim 1.

Description

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0084] Below Table 1 shows multiple rubber compositions including a partially saturated elastomer in the form of a hydrogenated solution-polymerized styrene butadiene rubber. Examples 1, 3, 4, 5 which are not in accordance with the present invention are based on a SSBR and natural rubber polymer matrix. Example 2 (also not in accordance with the present invention) comprises 100 phr of a hydrogenated SSBR. The Inventive Examples 1, 2, 3 are also based on a 100 phr hydrogenated SSBR rubber matrix. According to embodiments of the present invention, all Inventive Examples include aluminum hydroxide in relatively high amounts. For comparison, Examples 3, 4 and 5 comprise the same amounts of aluminum hydroxide as the respective Inventive Examples 1, 2, and 3. The total oil amounts are at 16 phr in each composition. Different oils are utilized to adjust the rubber composition Tg to the same or similar level for a better comparison of the different rubber compositions under review. Some rubber compositions with higher aluminum hydroxide load comprise less silica than rubber compositions with lower aluminum hydroxide load, in particular preferably in order to keep a balanced filler to polymer ratio. The rubber compositions comprising the hydrogenated SSBR have an additional fast accelerator in the form of tetrabenzylthiuram disulfide in view of the limited amount of available double bonds for the sulfur cure.

TABLE-US-00001 TABLE 1 Sample (amounts in phr) Ingredient Ex. 1 Ex. 2 Ex. 3 Inv. Ex. 1 Ex. 4 Inv. Ex. 2 Ex. 5 Inv Ex. 3 Hydrogenated SSBR.sup.1 0 100 0 100 0 100 0 100 SSBR.sup.2 80 0 80 0 80 0 80 0 Polyisoprene.sup.3 20 0 20 0 20 0 20 0 Al(OH).sub.3.sup.4 0 0 20 20 40 40 60 60 Oil 1.sup.5 0 5 0 5 0 5 0 5 Oil 2.sup.6 16 11 16 11 16 11 16 11 Stearic Acid 2 2 2 2 2 2 2 2 Silica.sup.7 80 80 80 80 60 60 40 40 Silane.sup.8 8 8 8 8 6 6 4 4 Zinc Oxide 3 3 3 3 3 3 3 3 Sulfur 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Waxes 2 2 2 2 2 2 2 2 Antidegradants.sup.9 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 Accelerator.sup.10 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 TBzTD.sup.11 0 0.5 0 0.5 0 0.5 0 0.5 Carbon Black 3 3 3 3 3 3 3 3 hydrogenated solution-polymerized styrene butadiene rubber having a glass transition temperature of about −30° C. .sup.2as SLR4602 from Trinseo with a glass transition temperature of about −27° C. .sup.3natural rubber .sup.4aluminum hydroxide having a BET surface area of 15 m.sup.2/g and d50 of 0.4 μm, d95 of 0.8 μm and d10 of 0.3 μm .sup.5sunflower oil .sup.6TDAE oil .sup.7HDS Silica having a BET surface area of 215 m.sup.2/g .sup.83-(octanoylthio)-1-propyltriethoxysilane as NXT ™ from Momentive .sup.9dihydroquinolines and phenylene diamines .sup.10 N-Tert-Butyl-2-benzothiazolesulfenamide .sup.11 tetrabenzylthiuram disulfide

[0085] Table 2 provides further Examples not in accordance with the invention (i.e. Examples 6 to 10) and further Inventive Examples 4 to 6. In contrast to the rubber compositions shown in Table 1, Examples 6 to 10 are based on a polymer matrix comprising the same SSBR but a low-Tg polybutadiene. Moreover, a traction resin is used instead of oil in all compositions listed in Table 2.

TABLE-US-00002 TABLE 2 Sample (amounts in phr) Ingredient Ex. 6 Ex. 7 Ex. 8 Inv. Ex. 4 Ex. 9 Inv. Ex. 5 Ex. 10 Inv Ex. 6 Hydrogenated SSBR.sup.1 0 100 0 100 0 100 0 100 SSBR.sup.2 80 0 80 0 80 0 80 0 Polybutadiene.sup.12 20 0 20 0 20 0 20 0 Al(OH).sub.3.sup.4 0 0 20 20 40 40 60 60 Resin.sup.13 16 11 16 11 16 11 16 11 Stearic Acid 2 2 2 2 2 2 2 2 Silica.sup.7 80 80 80 80 60 60 40 40 Silane.sup.8 8 8 8 8 6 6 4 4 Zinc Oxide 3 3 3 3 3 3 3 3 Sulfur 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Waxes 2 2 2 2 2 2 2 2 Antidegradants.sup.9 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 Accelerator.sup.10 2.2 2.2 2.2 2.2 2.2 2.2 2.2 2.2 TBzTD.sup.11 0 0.5 0 0.5 0 0.5 0 0.5 Carbon Black 3 3 3 3 3 3 3 3 .sup.12 high cis-1,4 polybutadiene having a Tg of −110° C. .sup.13 alpha pinene terpene based resin having a Tg of 70° C. as Dercolyte ™ A115 from DRT

[0086] Measurements of physical properties/tire tests have been carried out for the compositions listed in Tables 1 and 2 and are shown in below Tables 3 and 4, respectively.

TABLE-US-00003 TABLE 3 Sample (values in %) Test/Property* Ex. 1 Ex. 2 Ex. 3 Inv. Ex. 1 Ex. 4 Inv. Ex. 2 Ex. 5 Inv Ex. 3 Rolling resistance 100 102 99.0 101 103 103 100 104 Wet traction 100 90 103 95 102 102 109 104 Tensile strength 100 154 94 136 86 143 94 138 Treadwear 100 106 84 90 46 78 50 78 *For determination of rolling resistance, rolling resistance indicator tangent delta has been determined at 30° C. by means of dynamic mechanical analysis (DMA) and results have been normalized with respect to Example 1 at 100% rolling resistance, wherein higher values are better; for the determination of wet traction, a transmittable friction force was determined with a linear friction tester and the results have been normalized with respect to Example 1 at 100% wet traction, wherein higher values are better; for the determination of tensile strength, true tensile strength was determined according to ASTM D412 with a ring sample and the results have been normalized with respect to Example 1 at 100% tensile strength, wherein higher values are better; for the determination of treadwear, abrasion has been determined according to ASTM D5963 and the results have been normalized with respect to Example 1 at 100% treadwear, wherein higher values are better.

[0087] As shown by the test results of Table 3, rolling resistance has been improved in Examples 2, 4 and Inventive Examples 1, 2 and 3. However, Example 2 has a limited wet traction. In particular, wet traction has been improved over Example 1 in Examples 3, 4, 5 and Inventive Examples 2 and 3. With regards to tensile strength, improvements are visible for all compositions comprising the hydrogenated SSBR, whereas the other compositions lost tensile strength, apparently upon addition of aluminum hydroxide. Finally, treadwear is kept at an acceptable level for the Inventive Examples. Overall, the balance of the Inventive Examples is better than the balance of the Examples not in accordance with the invention, in particular when taking into account at least 3 of the above mentioned properties.

TABLE-US-00004 TABLE 4 Sample (values in %) Test/Property* Ex. 6 Ex. 7 Ex. 8 Inv. Ex. 4 Ex. 9 Inv. Ex. 5 Ex. 10 Inv Ex. 6 Rolling resistance 100 103 98 101 99 103 102 104 Wet traction 100 100 111 108 118 113 118 114 Tensile strength 100 142 94 117 95 126 90 122 Treadwear 100 106 89 93 68 84 74 75 *The determination of the properties was carried out as shown for Table 3 but the results have been normalized with respect to Example 6 in present Table 4.

[0088] With respect to the results shown in Table 4, Examples 7 to 9 and Inventive Examples 4 to 6 have been normalized to the respective results of Example 6. The use of the hydrogenated polymer in Example 7 has significantly improved the tensile strength in an order of 40%. The addition of aluminum hydroxide in Example 8 has impaired rolling resistance, tensile strength and treadwear, whereas wet traction has been significantly improved. Inventive Example 4 shows an advanced balance of the measured properties. Example 9 has particular weaknesses in treadwear and tensile strength. Example 10 loses even more tensile strength compared to Examples 6 and 9. Inventive Example 5 has very good rolling resistance, wet traction and tensile strength, with a slight tradeoff in treadwear. While Inventive Example 6 has the best rolling resistance and wet traction of the compounds measured in accordance with Table 4, and as well a good tensile strength, tread wear is at 75% of Example 6 but still higher than that of Examples 9 and 10.

[0089] Overall, also the results of Table 4 demonstrate that the embodiments of the invention can achieve an improved balance of the determined properties or performances.

[0090] While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention.