Acrylic elastomer and its composition

Abstract

A butenedioic acid monoalkyl ester-copolymerized acrylic elastomer containing 0.1-30% by mole of unreacted butenedioic acid monoalkyl ester on the basis of carboxyl groups copolymerized in the acrylic elastomer or its cross-linkable composition. The cross-linkable composition can give cross-linking products having distinguished vulcanization characteristics and stably showing good compression set characteristics.

What is claimed is:  
     
         1 . A butenedioic acid monoalkyl ester-copolymerized acrylic elastomer, which contains 0.1-30% by mole of unreacted butenedioic acid monoalkyl ester on the basis of carboxyl groups copolymerized in the acrylic elastomer.  
     
     
         2 . A butenedioic acid monoalkyl ester-copolymerized acrylic elastomer according to    claim 1   , wherein the butenedioic acid monoalkyl ester is an monoalkyl maleate.  
     
     
         3 . An acrylic elastomer composition, which comprises a butenedioic acid monoalkyl ester-copolymerized acrylic elastomer of    claim 1   , and a cross-linking agent.  
     
     
         4 . An acrylic elastomer composition according to    claim 3   , wherein the cross-linking agent is a polyamine compound, and a guanidine compound, a sulphonamide compound or a tertiary amine is used as a vulcanization accelerator at the same time.  
     
     
         5 . An acrylic elastomer composition according to    claim 3   , wherein the cross-linking agent is a polyfunctional isocyanate compound or blocked isocyanate, and an alkali metal salt of inorganic or organic acid, an alkali metal hydroxide, a quaternary onium salt, a guanidine compound, a tertiary phosphine, a tertiary amine or a sulphenamide compound is used as a vulcanization accelerator at the same time.