| 摘要 |
PROBLEM TO BE SOLVED: To provide a process for producing an ethylene-α-olefin-nonconjugated diene copolymer rubber having an excellent balance between the residual compression stress ratio as an index of shape retention properties and BIT as an index of kneadability. SOLUTION: The ethylene-α-olefin-nonconjugated diene copolymer rubber has a ratio Az/An of the Z-average molecular chain length (Az) to the number average molecular chain length (An) of 20-30, a ratio Aw/An of the weight average molecular chain length (Aw) to the An of more than 5, a unimodal or bimodal molecular weight distribution structure having a molecular chain component having a highest abundance ratio in the range of 3.8<Log Aw<4.5, and a viscosity measured by an ML viscometer of 60<ML<SB>1+4</SB>, 121°C<160. The process for producing this copolymer rubber uses a polymerization catalyst comprising a vanadium compound and an organometallic compound or a polymerization catalyst comprising a transition metal complex having a cyclopentadienyl skeleton. COPYRIGHT: (C)2004,JPO&NCIPI
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