Rubber, crosslinkable rubber composition, and crosslinked object

Abstract

A nitrile group-containing highly saturated copolymer rubber comprising (a) 10-40 wt. % of α,β-ethylenically unsaturated nitrile monomer units, (b) 10-60 wt. % of α,β-ethylenically unsaturated carboxylic acid ester monomer units, (c) 0.01-21 wt. % of conjugated diene monomer units, and (d) 14-69.99 wt. % of saturated conjugated diene monomer units, wherein the sum of monomer units (c) plus (d) is 20-70 wt. %, the ratio of monomer units (d)/[monomer units (c) plus (d)] is at least 70 wt. %, and the difference between the extrapolated glass transition-initiating temperature (Tig) and the extrapolated glass transition-ending temperature (Teg), as measured by DSC is not higher than 10° C. The copolymer rubber gives a crosslinked product having good cold resistance, oil resistance and dynamic properties.

Dependencies are inferred from the claim text.