To provide a rubber composition that designs a weight saving, improves permanent strain, besides dispersion in charge during extrusion and shape preserving property, does not reduce characteristics of elongation and stress, etc. and has excellent durability.
This rubber composition is produced by foaming and crosslinking an uncrosslinked rubber composition composed of an ethylene-propylene-nonconjugated polyene copolymer that meets the relationship: Y≤1.1(0.48T-13.19), wherein Y represents a polymer structural index and T (wt%) represents an ethylene content. The foamed and crosslinked rubber composition has hardness of 55(A) or more, is produced by blending the ethylene-propylene-nonconjugated polyene copolymer of Y=20-25 (A) with the ethylene-propylene-nonconjugated polyene copolymer of Y=10-15 (B) in the ratio of (A)/(B)=1-40/99-60 (by wt%), preferably (A)/(B)=1-35/99-65, and has a specific gravity of ≤1.1.
TATSUTA HIROSHI
Hiromichi Kobayashi
Tomioka Kiyoshi
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