RUBBER COMPOSITION AND A TIRE

Abstract

The present invention is directed to a rubber composition comprising 80 phr to 100 phr of at least one solution polymerized styrene-butadiene rubber, 0 phr to 20 phr of at least one polybutadiene, 55 phr to 200 phr of a filler, at least 15 phr of oil, wherein the filler to oil ratio by weight is between 3.5:1 and 8.0:1, and wherein the weight average molecular weight (Mw) of the at least one solution polymerized styrene-butadiene rubber is within a range of 400,000 to 1,000,000 g/mol. Moreover, the present invention is directed to a tire comprising such a rubber composition.

Claims

1. A rubber composition comprising: 80 phr to 100 phr of at least one solution polymerized styrene-butadiene rubber, 0 phr to 20 phr of at least one polybutadiene rubber, 55 phr to 200 phr of a filler, at least 15 phr of oil, wherein the filler to oil ratio by weight is between 3.5:1 and 8:1, and wherein the weight average molecular weight (Mw) of the at least one solution polymerized styrene-butadiene rubber is within a range of 400,000 to 1,000,000.

2. The rubber composition of claim 1 wherein the at least one solution polymerized styrene-butadiene rubber has a bound styrene content within a range of 20% to 50% and a vinyl microstructure content within a range of 10% to 50%.

3. The rubber composition of claim 1 wherein the rubber composition comprises between 15 phr and 45 phr of oil.

4. The rubber composition of claim 1 wherein the at least one solution polymerized styrene-butadiene rubber is end functionalized.

5. The rubber composition of claim 1 wherein the at least one solution polymerized styrene-butadiene rubber is end functionalized with an aminosilane group and/or an aminosiloxane group.

6. The rubber composition of claim 1 comprising at least two solution polymerized styrene-butadiene rubbers, wherein a first solution polymerized styrene-butadiene rubber has a glass transition temperature within a range of −20° C. to −85° C. and a second solution polymerized styrene-butadiene rubber has glass transition temperature within a range of −5° C. and −20° C.

7. The rubber composition of claim 1 wherein the rubber composition comprises from 5 phr to 15 phr of polybutadiene rubber.

8. The rubber composition of claim 7 wherein the polybutadiene rubber has a glass transition temperature within a range of −90° C. to −110° C.

9. The rubber composition of claim 1 wherein the rubber composition comprises at least 90 phr of silica.

10. The rubber composition of claim 1 wherein the at least one solution polymerized styrene-butadiene rubber is an oil-extended solution polymerized styrene-butadiene rubber and wherein said oil extension is at most 35 parts by weight per 100 parts by weight of the solution polymerized styrene-butadiene rubber.

11. The rubber composition of claim 10 wherein said oil extension is within a range of 5 to 35 parts by weight per 100 parts by weight of the solution polymerized styrene-butadiene rubber.

12. The rubber composition of claim 11 wherein said oil extension is one or more of at most 30 parts and at least 10 parts per 100 parts of the solution polymerized styrene-butadiene rubber.

13. The rubber composition of claim 1 wherein the at least one solution polymerized styrene-butadiene rubber is oil-extended and at least 70% of the oil in the rubber composition is extension oil of the solution polymerized styrene-butadiene rubber.

14. The rubber composition of claim 1 wherein at least 70% of the filler by weight is silica.

15. The rubber composition of claim 1 wherein the rubber composition is a sulfur-vulcanizable rubber composition.

16. The rubber composition of claim 1 further comprising from 10 phr to 50 phr of a resin.

17. The rubber composition of claim 16 wherein said resin is selected from at least one of styrene/δ-methylstyrene resin, coumarone-indene resin, petroleum hydrocarbon resin, terpene polymer, terpene phenol resin and rosin derived resin and copolymers thereof and hydrogenated rosin acid.

18. The rubber composition of claim 16 wherein a ratio by weight of the resin to the oil is within a range of 1:1 to 1:3.

19. A tire comprising a rubber composition which comprises: 80 phr to 100 phr of at least one solution polymerized styrene-butadiene rubber, 0 phr to 20 phr of at least one polybutadiene, 55 phr to 200 phr of a filler, at least 15 phr of oil, wherein the filler to oil ratio by weight is between 3.5:1 and 8:1, and wherein the weight average molecular weight (Mw) of the at least one solution polymerized styrene-butadiene rubber is within a range of 400,000 to 1,000,000 g/mol.

20. The tire of claim 19 wherein the tire comprises a tread and wherein the tread is comprised of the rubber composition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The structure, operation, and advantages of the invention will become more apparent upon contemplation of the following description taken in conjunction with the accompanying drawings.

[0074] FIG. 1 is a schematic cross section of a tire comprising a rubber component with the rubber composition in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0075] FIG. 1 is a schematic cross-section of a tire 1 according to an embodiment of the invention. The tire 1 has a plurality of tire components such as a tread 10, an innerliner 13, a belt comprising four belt plies 11, a carcass ply 9, two sidewalls 2, and two bead regions 3, bead filler apexes 5 and beads 4. The example tire 1 is suitable, for example, for mounting on a rim of a vehicle, e.g. a truck or a passenger car. As shown in FIG. 1, the belt plies 11 may be covered by an overlay ply 12 and/or may include one or more breaker plies. The carcass ply 9 includes a pair of axially opposite end portions 6, each of which is associated with one of the beads 4. Each axial end portion 6 of the carcass ply 9 may be turned up and around the respective bead 4 to a position to anchor each axial end portion 6. The turned-up portions 6 of the carcass ply 9 may engage the axial outer surfaces of two flippers 8 and axial inner surfaces of two chippers 7 which are also considered as tire components. As shown in FIG. 1, the example tread 10 may have circumferential grooves 20, each groove 20 essentially defining a U-shaped opening in the tread 10. The main portion of the tread 10 may be formed of one or more tread compounds. Moreover, the grooves 20, in particular the bottoms and/or sidewalls of the grooves 20 could be reinforced by a rubber compound having a higher hardness and/or stiffness than the remaining tread compound. Such reinforcement may be referred to herein as “a groove reinforcement.”

[0076] While the embodiment of FIG. 1 suggests a plurality of tire components including for instance apexes 5, chippers 7, flippers 8 and overlay 12, such and further components are not mandatory for the invention. Also, the turned-up end of the carcass ply 9 is not necessary for the invention or may pass on the opposite side of the bead area 3 and end on the axially inner side of the bead 4 instead of the axially outer side of the bead 4. The tire could also have, for instance, a different number of grooves 20, e.g. less than four grooves.

[0077] For instance, the tread 10 of the tire may comprise a rubber composition in accordance with an embodiment of the invention. Table 1 shows in the Inventive Example a rubber composition in accordance with such an embodiment of the invention. It is compared with a Control Sample, which comprises a different SSBR with larger oil extension and higher molecular weight. Moreover, the Control Sample comprises larger amounts of silica and silane. The remaining ingredients of both compositions are essentially the same.

TABLE-US-00001 TABLE 1 Parts by weight (phr) Control Inventive Material Sample Example SSBR.sup.1 103.2 0 SSBR.sup.2 0 93.75 Polybutadiene.sup.3 25 25 Silica.sup.4 112 105 Silane.sup.5 11 10.5 Oil.sup.6 5 5 Antidegradants.sup.7 3.5 3.5 Waxes 2 2 Resin.sup.8 5 5 Resin.sup.9 12 12 Fatty acid soap 1 1 Stearic Acid 2.5 2.5 Carbon black 1 1 Rosin 3 3 Zinc Oxide 2.5 2.5 Accelerators.sup.10 5 5 Sulfur 1.5 1.5 .sup.1oil-extended, solution polymerized styrene-butadiene rubber, extended by 37.5 phr oil per 100 parts of solution polymerized styrene-butadiene rubber; with a Tg of −14° C.; with a styrene microstructure content of 34% and a vinyl microstructure content of 38% (RHC) and a weight average molecular weight Mw of 1,200,000 g/mol as Tufdene ™ E680 from the company Asahi; .sup.2oil-extended, solution polymerized styrene-butadiene rubber, extended by 25 phr oil per 100 parts of solution polymerized styrene-butadiene rubber; with a Tg of −14° C.; with a styrene microstructure content of 34% and a vinyl microstructure content of 38% (RHC) and a weight average molecular weight Mw of 940,000 g/mol, end-chain amino silane functionalized; .sup.3cis-1,4 polybutadienes as Budene ™ 1223 from Goodyear Chemical; .sup.4as Zeosil Premium ™ 200 MP silica from the company Solvay; .sup.5as SI266 ™ from the company Evonik; .sup.6TDAE Oil; .sup.7phenylene-diamines and 2,2,4-trimethyl-1,2-dihydroquinoline .sup.8octylphenol formaldehyde resin as SP-1068 from SI Group .sup.9alpha-methyl styrene resin as Novares Pure 85 AS, Ruetgers .sup.10including n-tert-butyl-2-benzothiazolesulfenamde, diphenylguanidine, 1,6-bis-(n,n dibenzylthiocarbamoyldithio) hexane

[0078] Below Table 2 shows measurements of physical properties of the compositions provided in Table 1 above after curing. The Inventive Example has a significantly lower tangent delta value than the Control Sample. The rebound value of the Inventive Example is higher than the rebound value of the Control Sample. Both these indicators suggest that the rolling resistance of the composition will be reduced significantly. The measured abrasion value has also been reduced in the Inventive Example compared to the Control Sample. In summary, tangent delta (tan 6), rebound and abrasion values have been improved in the Inventive Example over the Control composition.

TABLE-US-00002 TABLE 2 Property Control Sample Inventive Example Tangent Delta.sup.a 0.35 0.33 Rebound [%].sup.b 40.1 42.6 Abrasion [mm.sup.3].sup.c 171 162 .sup.atan delta was measured at 12% strain, frequency 7.8 Hz, and 30° C. on a METRAVIB ™ analyzer .sup.brebound values have been measured on a Zwick Roell ™ 5109 rebound resilience tester according to DIN 53512 at a temperature of 60° C. .sup.crotary drum abrasion test according to ASTM D5963 or equivalent providing a relative volume loss

[0079] 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.