| 摘要 |
A styrene-butadiene copolymer having excellent low hysteresis loss characteristic, wet skid resistance, fracture characteristics, and abrasion resistance and a rubber composition comprising the copolymer are disclosed. The styrene-butadiene copolymer has a total styrene content in the range of 33 to 42% by weight of the styrene-butadiene copolymer; a content of styrene sequences having 4 to 20 styrene units in the range of 40 to 65% by weight of the total styrene content, as obtained by measurements by NMR and GPC; a content of styrene sequences having more than 20 styrene units in the range of 5% by weight or less of the total styrene content, as obtained by measurement by GPC; a content of vinyl unit in the range of 30% by mol or less of a butadiene part of the styrene-butadiene copolymer; a sum of the total styrene value and ½ of the content of vinyl units in the range of 46 to 52%; and an inner or end structure having, for example tin-carbon bond. The copolymer and the rubber composition are used for tire treads and the like.
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