| 摘要 |
The subject invention is based upon the unexpected discovery that tires having outstanding dry and wet traction characteristics, including wet skid resistance, can be made by incorporating certain blends of styrene-butadiene rubber (SBR) and isoprene-butadiene rubber (IBR) into the treads thereof without greatly sacrificing rolling resistance and tread wear characteristics. This invention more specifically discloses a tire tread rubber composition which is comprised of (a) about 50 phr to about 85 phr of a SBR and (b) about 15 phr to about 50 phr of an IBR, wherein the IBR is comprised of repeat units which are derived from about 20 weight percent to about 50 weight percent isoprene and from about 50 weight percent to about 80 weight percent 1,3-butadiene, wherein the repeat units derived from isoprene and 1,3-butadiene are in essentially random order, wherein from about 3 percent to about 10 percent of the repeat units in the IBR are 1,2-polybutadiene units, wherein from about 50 percent to about 70 percent of the repeat units in the IBR are 1,4-polybutadiene units, wherein from about 1 percent to about 4 percent of the repeat units in the IBR are 3,4-polyisoprene units, wherein from about 25 percent to about 40 percent of the repeat units in the IBR are 1,4-polyisoprene units, wherein the IBR has a glass transition temperature which is within the range of about -90° C. to about -75° C. and wherein the IBR has a Mooney viscosity which is within the range of about 55 to about 140.
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