| 摘要 |
A block copolymer (hereinafter referred to as the block copolymer (I)), consisting essentially of a vinyl aromatic hydrocarbon and a conjugated diene and satisfying the following conditions (1) to (5): (1) the weight ratio of vinyl aromatic hydrocarbon units to conjugated diene units is from 60:40 to 90:10, (2) the number average molecular weight of the block copolymer is from 40,000 to 500,000, (3) the ratio of E'30/E'10, where E'30 is the storage modulus at a temperature of 30.degree.C and E'10 is the storage modulus at a temperature of 10.degree.C, is from 0.75 to 1, (4) the block proportion of a vinyl aromatic hydrocarbon polymer contained in the block copolymer is from 70 to 100%, provided the block proportion=W1/W0.times.100, where W1 is the weight of block polymer chains of the vinyl aromatic hydrocarbon in the block copolymer, and W0 is the total weight of the vinyl aromatic hydrocarbon units in the block copolymer, and (5) chains consisting of from 1 to 3 repeating units of the vinyl aromatic hydrocarbon contained in the block copolymer, are not more than 25%, based on the above W0.
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