| 摘要 |
An ethylene/ alpha -olefin/unconjugated diene copolymer with an ethylene/ alpha -olefin wt. ratio of (73/27)-(40/60), an iodine number of 20-36, a Mooney viscosity (with 20 parts extender oil per 100 parts copolymer) of 100-180 and a Q value (Mw/Mn; by GPC) of 3-5 is used as an oil-extended copolymer for sponge rubber. Oil-extended copolymer (a) for sponge rubber containing (b) 10-90 parts by weight extender oil per 100 parts (a), in which (a) is a copolymer of ethylene, alpha -olefin and unconjugated diene, with (1) an ethylene/ alpha -olefin wt. ratio of (73/27)-(40/60), (2) an iodine number of 20-36 (representing the diene content), (3) a Mooney viscosity (ML 1 + 4 (121 deg C); JIS-K-6300) of 100-180, measured for a mixture obtained by adding 20 parts by weight (b) to 100 parts copolymer) and (4) a Q value (ratio of wt.-average to number-average mol. wt., measured by GPC) of 3-5.
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