| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rubber composition which is excellent in the balance among softness, mechanical properties, and molding/processing properties and has good gas/water vapor permeability and vibration-damping properties by compounding an isobutylene block copolymer with a specified amount of butyl rubber. SOLUTION: 100 pts.wt. 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 compounded with 5-230 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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