| 摘要 |
PROBLEM TO BE SOLVED: To obtain a thermoplastic resin composition which is excellent in softness, balance among mechanical properties, and gas/water vapor permeability and is completely free from bleed out of a softener by compounding an isobutylene block copolymer with a polyolefin resin and butyl rubber. SOLUTION: A block copolymer comprising polymer blocks formed mainly from isobutylene and polymer blocks formed from a monomer component which does not contain isobutylene as the main monomer is used. Preferably, 100 pts.wt. block copolymer is compounded with 1-400 pts.wt. polyolefin resin and 5-500 pts.wt. butyl rubber. The monomer component which does not contain isobutylene as the main monomer is preferably an aromatic vinyl monomer, preferable examples being styrene,α-methylstyrene, p-methylstyrene, and indene. The wt. ratio of polymer blocks formed mainly from isobutylene to polymer blocks formed from a monomer component which does not contain isobutylene as the main monomer is preferably (98/2)-(40/60).
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