| 摘要 |
PROBLEM TO BE SOLVED: To provide a sealing material having a small difference between a degree of the swelling in a pure water and that in an electrolytic aqueous solution and having a small shrinkage after the swelling in an electrolytic aqueous solution and to provide a rubber composition of a raw material thereof. SOLUTION: The rubber composition, a crosslinked substance of which being used for a sealing material, comprises (A) a polyether-based polymer containing 70-99 mole % of an ethylene oxide unit and 1-30 mole % of a monomer unit of oxylane other than ethylene oxide and above all having a crosslinkable oxirane monomer content of 1-15 mole %, (B) an unsaturated rubber, and (C) a highly water-absorptive polymer; on the basis of the sum total of (A) the polyether-based polymer, (B) the unsaturated rubber and (C) the highly water- absorptive polymer, (A) the polyether-based polymer is 10-90 wt.%, (B) the unsaturated rubber is 9-89 wt.%, and (C) the highly water-absorptive polymer is 1-40 wt.%.
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