| 摘要 |
PURPOSE:To provide a sponge having excellent extrusion moldability, vulcanizability, rubber strength in the sponge-forming process, and surface smoothness, and suitable as a sealing material for bicycles, construction, building, etc., by vulcanizing and foaming a specific ethylene-alpha-olefin-polyene copolymer rubber. CONSTITUTION:(A) A copolymer of ethylene and an alpha-olefin at a molar ratio of 55/45-95/5 is copolymerized with (B) a copolymer of 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene at a molar ratio of about 1-20 to obtain an ethylene- alpha-olefin-polyene copolymer rubber having an intrinsic viscosity [eta] of 1.0- 6.0dl/g (135 deg.C, in decalin) and Q-value of preferably <=6 (representing the ratio of weight-average molecular weight to number-average molecular weight) and having copolymerized polyene content of 2-40 in terms of iodine value. The obtained rubber is vulcanized and foamed to obtain the objective sponge. |
