| abstract |
Rubber-based composition modifier, comprising 100 parts by mass of a mixed rubber component containing a chloroprene rubber and at least one copolymer selected from ethylene / α-olefin copolymers and ethylene / α-olefin / copolymers. unconjugated polyene, 10 to 60 parts by mass of magnesium oxide, 3 to 30 parts by mass of a softener, and 30 to 120 parts by mass of acetylene black, in which: the mixed rubber component has a Mooney viscosity, as determined by the method specified in JIS K6300, 60-180-100 ° C; magnesium oxide has a BET specific surface area, as determined by the one point method specified in JIS Z8830, of 20 to 150 m2 / g; the softener contains a fatty acid ester based plasticizer and an unsaturated fatty acid having a carbon number of 10 to 24 and containing an ester bond, a hydroxyl group, or both in part of the structure; and acetylene black has a nitrogen adsorption specific surface area (N2SA), as determined by the method specified in JIS K6217-2, of 50 to 160 m2 / g. |