Rubber composition, vulcanizate, and air intake hose

Abstract

A rubber composition, including α,β-ethylenically unsaturated nitrile-conjugated diene copolymer rubber (A) having number average molecular weight of 50,000 to 150,000, α,β-ethylenically unsaturated nitrile-conjugated diene copolymer rubber (B) having number average molecular weight of 1,000 to 20,000, ethylene-α-olefin copolymer rubber (C), and a graft copolymer (D); wherein said graft copolymer (D) is obtained by performing graft copolymerization on a mixture of an aromatic vinyl compound and an α,β-ethylenically unsaturated nitrile monomer with an ethylene-propylene-unconjugated copolymer, and a content of structure units of said ethylene-propylene-unconjugated copolymer is 20 to 70 wt %; a ratio of the graft copolymer (D) with respect to 100 parts by weight in total of said rubber (A), rubber (B) and rubber (C) is 1 to 30 parts by weight; and a composition ratio of the rubber (A), rubber (B) and rubber (C) is rubber (A): 20 to 79 wt %, rubber (B): 1 to 30 wt %, and rubber (C): 20 to 50 wt %, is subjected to vulcanization molding, consequently, vulcanizate of the rubber composition having excellently balanced ozone resistance, flexing fatigue resistance and oil resistance can be provided.

1 . A vulcanizate obtained by vulcanizing a rubber composition, including α,β-ethylenically unsaturated nitrile-conjugated diene copolymer rubber (A) having number average molecular weight of 50,000 to 150,000; 
 α,β-ethylenically unsaturated nitrile-conjugated diene copolymer rubber (B) having number average molecular weight of 1,000 to 20,000;    ethylene-α-olefin copolymer rubber (C);    a graft copolymer (D); and    a vulcanizing agent    wherein    said graft copolymer (D) is obtained by performing graft copolymerization on a mixture of an aromatic vinyl compound and an α,β-ethylenically unsaturated nitrile monomer with an ethylene-propylene-unconjugated copolymer, and a content of structure units of said ethylene-propylene-unconjugated copolymer is 20 to 70 wt %;    a ratio of the graft copolymer (D) with respect to 100 parts by weight in total of said rubber (A), rubber (B) and rubber (C) is 1 to 30 parts by weight; and    a composition ratio of the rubber (A), rubber (B) and rubber (C) is    rubber (A): 20 to 79 wt %,    rubber (B): 1 to 30 wt %, and    rubber (C): 20 to 50 wt %.    
   
   
       2 . Air intake hose composed of the vulcanizate as set forth in  claim 1.