Rubber composition and a tire

Abstract

The present invention is directed to a sulfur vulcanizable rubber formulation comprising 10 phr to 100 phr of at least one partially saturated elastomer comprising repeat units, wherein at most 10% 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 5 phr to 70 phr of at least one hydrogenated plasticizer. This sulfur vulcanizable rubber formulation has been found to be useful in manufacturing tires.

Claims

1. A sulfur vulcanizable rubber composition comprising: at least one partially saturated elastomer comprising repeat units, wherein at most 15% of all repeat units of the elastomer comprise a double bond, wherein the partially saturated elastomer has a glass transition temperature which is within the range of ?52? C. to ?60? C.; wherein the rubber composition comprises from 80 phr to 95 phr of the partially saturated elastomer and from 2 phr to 8 phr of cis-1,4-polybutadiene rubber having a cis-microstructure content of at least 95%, and wherein the polybutadiene rubber has a glass transition temperature within a range of ?90? C. to ?115? C.; 40 phr to 200 phr of at least one filler; 5 phr to 70 phr of at least one hydrogenated plasticizer; and 3 phr to 20 phr of a polyoctenamer.

2. The sulfur vulcanizable rubber composition according to claim 1, wherein from 4% to 8% of all repeat units in the partially saturated elastomer have a double bond.

3. The sulfur vulcanizable rubber composition according to claim 1, wherein said filler comprises from 40 phr to 190 phr of silica.

4. The sulfur vulcanizable rubber composition according to claim 1, wherein the partially saturated elastomer consists of isoprene repeat units.

5. The sulfur vulcanizable rubber composition according to claim 1, wherein the partially saturated elastomer consists of butadiene repeat units.

6. The sulfur vulcanizable rubber composition according to claim 1, wherein the partially saturated elastomer has: a glass transition temperature within a range of ?55? C. to ?60? C.; and a molecular weight within a range of 200,000 g/mol to 500,000 g/mol.

7. The sulfur vulcanizable rubber composition according to claim 1, wherein the rubber composition further comprises an oil at a level of up to 25 phr; and wherein the ratio of the hydrogenated plasticizer to the oil is within a range of 4:1 to 1:2.

8. The sulfur vulcanizable 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.

9. The sulfur vulcanizable rubber composition of claim 1 wherein the hydrogenated plasticizer is a fully hydrogenated cyclopentadiene resin.

10. The sulfur vulcanizable rubber composition of claim 1 wherein the hydrogenated plasticizer is a partially hydrogenated cyclopentadiene resin.

11. The sulfur vulcanizable rubber composition according to claim 1, wherein the polyoctenamer has a glass transition temperature within a range of ?50? C. to ?80? C.

12. The sulfur vulcanizable rubber composition according to claim 11 wherein the polyoctenamer has a weight average molecular weight within a range of 80,000 to 100,000 g/mol as determined by GPC.

13. The sulfur vulcanizable rubber composition according to claim 11 wherein the polyoctenamer has a melting point within a range of 45? C. to 55? C. as measured by DSC in a second heating.

14. The sulfur vulcanizable rubber composition according to claim 11 wherein the polyoctenamer contains between 65% and 85% trans double bonds.

15. The sulfur vulcanizable rubber composition according to claim 1, wherein the partially saturated elastomer is a solution-polymerized styrene butadiene rubber.

16. The sulfur vulcanizable rubber composition according to claim 15 wherein the solution-polymerized styrene butadiene rubber has a bound styrene content which is with the range of 5% to 40%.

17. The sulfur vulcanizable rubber composition according to claim 15 wherein the solution-polymerized styrene butadiene rubber has a molecular weight within a range of 200,000 g/mol to 500,000 g/mol.

18. The sulfur vulcanizable rubber composition according to claim 15 wherein the solution-polymerized styrene butadiene rubber contains less than 5% non-hydrogenated vinyl groups, based on the total number of vinyl groups of the solution-polymerized styrene butadiene rubber.

19. A tire comprising the sulfur vulcanizable rubber composition of claim 1.

Description

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

(1) Below Table 1 shows different rubber compositions including a partially saturated elastomer in the form of a hydrogenated solution-polymerized styrene butadiene rubber. Examples 1 to 3 are comparative examples, whereas Inventive Examples 1 and 2 are in accordance with non-limiting embodiments of the present invention. Example 1 is essentially resin free whereas the remaining examples comprise 15 phr of resin. As Example 1 is resin free, the other examples comprise a different oil to adjust the compound glass transition temperature essentially to that of Example 1 and so as to improve the comparability of rubber compound properties. Types and amounts of waxes, stearic acid, silica, carbon black, silane, accelerators, processing aids, curing agents and antidegradants are the same or similar in the different Examples.

(2) Examples 2 and 3 comprise an aliphatic C5 resin which is not hydrogenated. In contrast, Inventive Examples 1 and 2 comprise a hydrogenated dicyclopentadiene (DCPD) resin as hydrogenated plasticizer. Examples 1 and 2 as well as Inventive Example 1 further comprise 5 phr of a polyoctenamer.

(3) TABLE-US-00001 TABLE 1 Sample (amounts in phr) Ingredient Ex. 1 Ex. 2 Ex. 3 Inv. Ex. 1 Inv. Ex. 2 Hydrogenated 100 100 100 100 100 SSBR.sup.1 Resin 1.sup.2 0 0 0 15 15 Resin 2.sup.3 0 15 15 0 0 Wax 1.5 1.5 1.5 1.5 1.5 Antidegradants 3 3 3 3 3 Polyoctenamer.sup.4 5 5 0 5 0 Oil 1.sup.5 0 15 15 15 15 Oil 2.sup.6 15 0 0 0 0 Stearic Acid 3 3 3 3 3 Silica.sup.7 80 80 80 80 80 Silane.sup.8 8 8 8 8 8 Fatty acid soap 1 1 1 1 1 TBzTD.sup.9 0.5 0.7 0.7 0.7 0.7 Zinc Oxide 2.5 2.5 2.5 2.5 2.5 Sulfur 1.1 1.4 1.4 1.4 1.4 MBT.sup.10 0.2 0.2 0.2 0.2 0.2 CBS.sup.11 2.5 2.5 2.5 2.5 2.5 DPG.sup.12 2.9 2.9 2.9 2.9 2.9 Carbon Black 2 2 2 2 2 .sup.1Hydrogenated solution-polymerized styrene butadiene rubber having a glass transition temperature of about ?30? C. .sup.2Hydrogenated dicyclopentadiene resin as Oppera? PR-140 from Exxonmobil .sup.3C5 resin as Wingtack? 98 from Cray Valley .sup.4Vestenamer? 8012 of the company Evonik .sup.5Naphtenic oil having a glass transition temperature of ?77? C. .sup.6TDAE oil having a glass transition temperature of ?50? C. .sup.7HDS Silica having a BET surface area of 215 m.sup.2/g .sup.8Bis-triethoxysilylpropyl-disulfide as SI 266? of the company Evonik .sup.9Vulcanizing accelerator tetrabenzylthiuram disulfide .sup.10Vulcanizing agent mercaptobenzothiazole .sup.11Vulcanizing accelerator N-cyclohexyl-benzothiazolesulfenamide .sup.12Vulcanizing accelerator diphenylguanidine

(4) Measurements of physical properties have been carried out for Examples 1 to 3 as well as for Inventive Examples 1 and 2. Corresponding results are summarized in Table 2 hereinbelow. Remarkably, the use of the hydrogenated hydrocarbon resin of Inventive Examples 1 and 2 improves significantly the rolling resistance indicator Tangent Delta at 30? C. In particular, comparing Example 3 with Inventive Example 2 shows an improvement in the order of 5%. Similarly, comparing versions comprising the polyoctenamer, i.e. Example 2 and Inventive Example, 1 shows an improvement which is even larger (in the order of 10%). While the Tangent Delta Value of Example 1 is even lower than that of Inventive Example 2, it is noted that Example 1 (which is resin free) is significantly worse with regard to the wet traction indicator provided by the rebound resilience measurement at 0? C. which is about 50% worse than the value according to Inventive Example 2. Abrasion values for Example 3 and Inventive Example 2 are at a similar level. The same applies to the two versions with polyoctenamer according to Examples 2 and Inventive Example 1, wherein their abrasion is significantly smaller than that of Example 3 and Inventive Example 2. The tear strength is for all samples of Table 2 at a preferable level which is caused, according to a non-binding theory of the inventors, by the partially saturated elastomer, here included as hydrogenated SSBR. In addition, it is noted that the Inventive Examples 1 and 2 provide an increased stiffness over the compositions of Examples 2 and 3. Although the stiffness of Example 1 is even higher, its rebound at 0? C. is at a level which is less favorable than that of all other examples and indicates inferior wet performance as already mentioned herein above. Thus, the compromise or balance of properties of Examples 2 and 3 is better than that of Example 1. Moreover, the balance of properties of Inventive Examples 1 and 2 is better than for Examples 1 to 3.

(5) TABLE-US-00002 TABLE 2 Test/Property Ex. 1 Ex. 2 Ex. 3 Inv. Ex. 1 Inv. Ex. 2 G 30? C. (MPA).sup.a 5.39 3.18 3.54 3.69 4.18 Tan Delta 30? C..sup.b 0.180 0.175 0.195 0.155 0.185 Rebound 0? C. (%).sup.c 15.5 12.8 10.7 13.0 10.6 Abrasion (mm.sup.3).sup.d 109 120 130 123 128 Tear Strength (N/mm).sup.e 16.7 14.2 17.1 16.6 15.3 .sup.aG has been obtained by a Metravib? instrument at 30? C., 6% strain and 7.8 Hz based on DIN 53513, or equivalent. .sup.bTangent Delta has been obtained by a Metravib? instrument at 30? C., 6% strain and 7.8 Hz based on DIN 53513, or equivalent. .sup.cRebound measured on a Zwick Roell 5109 rebound resilience tester according to DIN 53512 at given temperature. .sup.dRotary drum abrasion test according to ASTM D5963 or equivalent .sup.eStrebler tear strength test according to DIN 53539 or equivalent.

(6) 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.