Rubber composition comprising nitrile copolymer rubber, metal salt of ethylenically unsaturated carboxylic acid, and organic peroxide, and vulcanizate thereof

摘要

A rubber composition comprising (A) a nitrile group-containing copolymer rubber, (B) a metal salt of an ethylenically unsaturated carboxylic acid and (C) an organic peroxide, wherein the rubber (A) comprises 10-40 wt. % of (a) alpha, beta-ethylenically unsaturated nitrile monomer units, 10-60 wt. % of (b) alpha, beta-ethylenically unsaturated carboxylic acid ester monomer units, 0.01-56 wt. % of (c) conjugated diene monomer units, and 14-69.99 wt. % of (d) saturated conjugated diene monomer units; the sum of monomer units (c) and monomer units (d) is 20-70 wt. %, and the ratio of monomer units (d) to the sum of monomer units (c) and monomer units (d) is at least 70 wt. %; the difference between the extrapolated glass transition initiation temperature (Tig) and the extrapolated glass transition ending temperature (Teg) as measured on rubber (A) by differential scanning calorimetry is not larger than 10° C. The rubber composition gives a vulcanizate having excellent cold resistance and oil resistance, and reduced compression set.