| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rubber composition excellent in mold release and fogging resistance by mixing a rubber selected among natural rubbers and synthetic rubbers with a betaine having a specified structure or its derivative and to obtain a vulcanized rubber comprising the same. SOLUTION: The rubber which can be desirably used is exemplified by an ethylene/α-olefin copolymer rubber, an ethylene/α-olefin/nonconjugated polyene copolymer rubber, NBR, IIR, SBR or a silicone rubber. The betaine or its derivative is represented by the formula (wherein R<1> to R<3> are each H, an aliphatic hydrocarbon group, an aromatic hydrocarbon group or the like; and Y is C(=O) or C(OH)HCH2 SO3 ) and has a molecular weight of 200-1,500. It is exemplified by an alkyldimethylaminoacetic acid betaine or an alkylamidealkylbetaine. Its amount of use is 0.1-20 pts.wt. per 100 pts.wt. rubber. The rubber composition can be used as such, but it is usually used in the form of a vulcanized rubber prepared by vulcanization with a sulfur compound or an organic peroxide.
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