Rubber-based composition modifier, and vulcanized product and molded article of rubber composition to which the modifier is added

摘要

Provided are a rubber-based composition modifier that provides a vulcanizate having excellent heat resistance and ozone resistance, and a vulcanizate and a molded product of a rubber composition to which the modifier is added. 10 to 60 parts by mass of magnesium oxide with respect to 100 parts by mass of a mixed rubber component consisting of chloroprene rubber and at least one selected from ethylene / α-olefin copolymer and ethylene / α-olefin / non-conjugated polyene copolymer Rubber composition modifier containing 3 parts by weight, 3-30 parts by weight of a softener, and 30-120 parts by weight of acetylene black. However, the mixed rubber component has a Mooney viscosity at 100 ° C. measured by a method defined in JIS K6300 of 60 to 180, and the magnesium oxide has a BET specific surface area measured by a one-point method defined in JIS Z8830. 20 to 150 m ² / g, and the softener comprises a fatty acid ester plasticizer and an unsaturated fatty acid having 10 to 24 carbon atoms having an ester bond and / or a hydroxyl group as a part of the structure, The acetylene black has a nitrogen adsorption specific surface area (N ₂ SA) measured by the method defined in JIS K6217-2 of 50 to 160 m ² / g.