| 摘要 |
PURPOSE:To obtain the titled molded product useful for heat shrinkable packaging material, excellent in the shrinking property and drawability at low temperature, having the specified molecular weight condition and weight ratio, being orientated from the copolymer having vinyl aromatic hydrocarbon block and conjugated diene block. CONSTITUTION:The copolymer containing (A) polymer block having at least 1 piece of vinyl aromatic hydrocarbon (for example, ethylene, etc.) as main material and (B) polymer block having at least 1 piece of conjugated diene (for example, butadiene, etc.) as main material, is polymerized and prepared by making n-butyl lithium, etc. as initiator in n-hexane. The block copolymer having the weight ratio of component A to component B of 60:40-95:5 is prepared within a range of 10,000-70,000 in number average molecular weight of component A and of under 1.25 in the ratio of weight average molecular weight to the number average molecular weight. The aimed molded product may be obtained by orientating the said block copolymer. |
