COPOLYMER RUBBER, RUBBER COMPOSITIONS AND RUBBER MOLDINGS

摘要

The invention provides a copolymer rubber excellent in processability in kneading and processability in extrusion; rubber compositions containing the rubber; and crosslinked moldings of the compositions excellent in sealing properties and shape retention. A random copolymer rubber of ethylene (A), a C<SUB>3-20</SUB> a-olefin (B) and a nonconjugated polyene (C) which satisfies the following requirements (1) to (5): (1) the structural units (A) and (B) are contained at an (A)/(B) molar ratio of 40/60 to 95/5, (2) the structural unit (C) content is 0.01 to 5 % by mole, (3) the limiting viscosity [?] is 1.0 to 5.0dl/g as determined in decalin at 135ºC, (4) the Mw/Mn is 1 to 8, and (5) the P value is 0.46 to 1.00 as defined by formula (1): P = Ln (limiting viscosity [?]) - 5.0 x 10<SUP>-5</SUP> x ?*(10) (1) (wherein Ln is a natural logarithm; and ?*(10) is a viscosity (Pa·sec) as determined at 190ºC and at 10rad/sec).