Acrylic rubber constituent and water swelling acrylic rubber

摘要

PURPOSE:To obtain acrylic rubber composition giving foamed molded product having excellent water absorption properties, form retention, oil-swelling, heat resistance, oil resistance and weatherability by mixing specific acrylic polymer with heat decomposable organic foaming agent and organic peroxide, etc. CONSTITUTION:A1: 99.99-90wt.% (meth)acrylate expressed by the formula [R1 is H or methyl; R2 is (substituted) lower alkyl, etc.] is copolymerized with A2: 0.01-10wt.% monomer having two or more aliphatic unsaturated bonds in a molecule (e.g. ethylidene norbornene) to obtain (A) an acrylic polymer. Then, 100 pts.wt. the polymer A is mixed with (B) 2-10 pts.wt. heat decomposable organic foaming agent (e.g. azodicarbonamide-based foaming agent), (C) 0.1-10 pts.wt. organic peroxide (e.g. benzoyl peroxide) and (D) 2-100 pts.wt. polyacrylic acid-based highly water-absorbing polymer to afford the aimed composition.