Nitrile copolymer rubber, metal salt of an ethylenically unsaturated carboxylic acid and organic peroxide and the rubber composition containing the vulcanizate thereof

摘要

A rubber composition comprising: (A) a nitrile copolymer rubber which comprises (a) 10 to 40 wt.% α,ß-ethylenically unsaturated nitrile monomer units, (b) 10 to 60 wt.% α,ß-ethylenically unsaturated carboxylic ester monomer units, (c) 0.01 to 56 wt.% conjugated diene monomer units, and (d) 14 to 69.99 wt.% saturated conjugated diene monomer units and in which the total content of the monomer units (c) and (d) is 20 to 70 wt.%, the content of the monomer units (d) is 70 wt.% or higher based on the sum of the monomer units (c) and (d), and the difference between the extrapolated glass transition initiation temperature (Tig) and the extrapolated glass transition ending temperature (Teg) in differential scanning calorimetry is 10°C or smaller; (B) a metal salt of an ethylenically unsaturated carboxylic acid; and (C) an organic peroxide. Also provided is a vulcanizate obtained by vulcanizing the rubber composition. The vulcanizate, which is obtained from the rubber composition, is excellent in cold resistance, oil resistance, and compression set.