Patent ID: 6127469
Filing Date: 2000-10-03
Classification: C08F,C08K

Abstract:
A process for preparing a high clarity water-sensitive carboxylated nitrile rubber composition which comprises the steps of (1) free radical polymerizing from about 30 weight percent to about 73 weight percent 1,3-butadiene, from about 20 weight percent to about 50 weight percent acrylonitrile and from about 7 weight percent to about 20 weight percent methacrylic acid in an aqueous polymerization medium in the presence of at least one emulsifier to produce a carboxylated nitrile rubber latex; (2) adjusting the pH of the carboxylated nitrile rubber latex to above 4 by the addition of a base to produce a pH-adjusted carboxylated nitrile rubber latex; (3) distributing at least one saponified oligomerized fatty acid throughout the pH-adjusted carboxylated nitrile rubber latex to produce a saponified oligomerized fatty acid containing pH-adjusted carboxylated nitrile rubber latex; (4) coagulating the saponified oligomerized fatty acid containing pH-adjusted carboxylated nitrile rubber latex by the addition of a combination of coagulating agents which consists essentially of at least one strong inorganic acid, calcium chloride and citric acid, to separate wet carboxylated nitrile rubber composition from an aqueous phase; and (5) drying the wet carboxylated nitrile rubber composition to produce said high clarity water-sensitive carboxylated nitrile rubber composition.