| 摘要 |
PCT No. PCT/JP93/01191 Sec. 371 Date Mar. 2, 1995 Sec. 102(e) Date Mar. 2, 1995 PCT Filed Aug. 25, 1993 PCT Pub. No. WO94/05717 PCT Pub. Date Mar. 17, 1994A block copolymer comprising a polymer block of an aromatic vinyl compound, a polymer block of butadiene and a polymer block of isoprene, having a weight average molecular weight of 10,000-500,000, containing 10-50 wt. % of a bound aromatic vinyl compound, 10-60 wt. % of bound butadiene, 10-60 wt. % of bound isoprene, at most 15 wt. % of 1,2-vinyl bonds in a butadiene segment and at most 10 wt. % of 3,4-vinyl bonds in an isoprene segment, and having a storage modulus (G') of 106-3x108 Pa in a viscoelasticity measurement in a temperature range of from 0 DEG C. to 50 DEG C. and only one peak on loss tangent (tan delta ) attributable to the butadiene polymer block and the isoprene polymer block in a temperature range of from -80 DEG C. to -50 DEG C. scarcely undergoes a change of melt viscosity with time. A pressure sensitive adhesive composition comprising the block copolymer and a tackifier is also provided.
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