Claims
- 1. A tire tread rubber composition which is comprised of (1) from about 20 phr to about 60 phr of an asymmetrically tin-coupled polybutadiene rubber, (2) from about 20 phr to about 60 phr of a rubber selected from the group consisting of natural rubber and synthetic polyisoprene and (3) from about 5 phr to about 40 phr of high vinyl polybutadiene rubber having a vinyl content of at least about 70 percent, wherein the high vinyl polybutadiene rubber is a high vinyl polybutadiene rubber other than said asymmetrically tin-coupled polybutadiene rubber.
- 2. A tire tread rubber composition as specified in claim 1 wherein said asymmetrically tin-coupled polybutadiene rubber has a Mooney ML 1+4 viscosity at 100.degree. C. which is within the range of about 60 to about 120.
- 3. A tire tread rubber composition as specified in claim 2 wherein said high vinyl polybutadiene rubber has a vinyl content of at least 75 percent.
- 4. A tire tread rubber composition as specified in claim 2 wherein said high vinyl polybutadiene rubber has a glass transition temperature which is within the range of about -40.degree. C. to about 40.degree. C., wherein the glass transition temperature is deemed to be the onset of the glass transition heat absorption peak as measured by differential scanning calorimetry at a heating rate of 10.degree. C. per minute.
- 5. A tire tread rubber composition as specified in claim 4 wherein said high vinyl polybutadiene rubber has a Mooney ML 1+4 viscosity at 100.degree. C. which is within the range of about 30 to about 100.
- 6. A tire tread rubber composition as specified in claim 5 wherein said member selected from the group consisting of natural rubber and synthetic polyisoprene is natural rubber.
- 7. A tire tread rubber composition as specified in claim 5 wherein said member selected from the group consisting of natural rubber and synthetic polyisoprene is synthetic polyisoprene rubber.
- 8. A tire tread rubber composition as specified in claim 5 wherein the tire tread rubber composition contains from about 25 phr to about 55 phr of the asymmetrically tin-coupled polybutadiene rubber, from about 25 phr to about 55 phr of the rubber selected from the group consisting of natural rubber and synthetic polyisoprene and from about 10 phr to about 30 phr of the high vinyl polybutadiene rubber.
- 9. A tire tread rubber composition as specified in claim 5 wherein the tire tread rubber composition contains from about 30 phr to about 50 phr of the asymmetrically tin-coupled polybutadiene rubber, from about 30 phr to about 50 phr of the rubber selected from the group consisting of natural rubber and synthetic polyisoprene and from about 15 phr to about 25 phr of the high vinyl polybutadiene rubber.
- 10. A tire tread rubber composition as specified in claim 9 wherein the high vinyl polybutadiene rubber has a glass transition temperature which is within the range of about -35.degree. C. to 0.degree. C., wherein the glass transition temperature is deemed to be the onset of the glass transition heat absorption peak as measured by differential scanning calorimetry at a heating rate of 10.degree. C. per minute and a Mooney ML 1+4 viscosity at 100.degree. C. which is within the range of about 40 to about 90.
- 11. A tire tread rubber composition as specified in claim 9 wherein the high vinyl polybutadiene rubber has a glass transition temperature which is within the range of about -30.degree. C. to -20.degree. C., wherein the glass transition temperature is deemed to be the onset of the glass transition heat absorption peak as measured by differential scanning calorimetry at a heating rate of 10.degree. C. per minute and a Mooney viscosity which is within the range of about 60 to about 80.
- 12. A tire tread rubber composition as specified in claim 11 wherein said asymmetrically tin-coupled polybutadiene rubber has a Mooney ML 1+4 viscosity at 100.degree. C. which is within the range of about 75 to about 110.
- 13. A tire tread rubber composition as specified in claim 11 wherein said asymmetrically tin-coupled polybutadiene rubber has a Mooney ML 1+4 viscosity at 100.degree. C. which is within the range of about 80 to about 100.
- 14. A tire tread rubber composition as specified in claim 1 wherein said asymmetrically tin-coupled polybutadiene is of the structural formula: ##STR5## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 can be the same or different and are selected from the group consisting of alkyl groups and polybutadiene arms, with the proviso that at least three members selected from the group consisting of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are polybutadiene arms, with the proviso that at least one member selected from the group consisting of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is a low molecular weight polybutadiene arm having a number average molecular weight of less than about 40,000, with the proviso that at least one member selected from the group consisting of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is a high molecular weight polybutadiene arm having a number average molecular weight of greater than about 80,000 and with the proviso that the ratio of the weight average molecular weight to the number average molecular weight of the asymmetrical tin-coupled polybutadiene rubber is within the range of about 2 to about 2.5.
- 15. A tire tread rubber composition as specified in claim 14 wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are all polybutadiene arms.
- 16. A tire tread rubber composition as specified in claim 14 wherein the low molecular weight polybutadiene arm has a number average molecular weight of less than about 30,000.
- 17. A tire tread rubber composition as specified in claim 14 wherein the high molecular weight polybutadiene arm has a number average molecular weight of greater than about 90,000.
- 18. A tire tread rubber composition as specified in claim 1 wherein said composition is further comprised of about 70 phr to about 250 phr of silica.
- 19. A tire tread rubber composition as specified in claim 18 wherein said silica has a dibutylphthalate absorption value which is within the range of about 100 to about 400, and wherein said silica has an average particle size which is within the range of 0.01 microns to 0.05 microns as determined with an electron microscope.
Parent Case Info
This is a continuation-in-part application of U.S. patent application Ser. No. 08/935,172, filed on Sep. 22, 1997 (now pending).
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4482678 |
Furukawa et al. |
Nov 1984 |
|
4647614 |
Takao et al. |
Mar 1987 |
|
5512626 |
Matsuo et al. |
Apr 1996 |
|
Foreign Referenced Citations (1)
Number |
Date |
Country |
0647675 |
Apr 1995 |
EPX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
935172 |
Sep 1997 |
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