Patent ID: 7655725

Claim:
A process for the preparation of a hydrogenated acrylonitrile-butadiene copolymer comprising the steps of: hydrogenation of at least one carbon-carbon double bond of an unsaturated acrylonitrile-butadiene copolymer in latex in the presence of hydrazine, an oxidizing compound and a catalyst, followed by separation of the hydrogenated acrylonitrile-butadiene copolymer from the latex wherein after the separation of the hydrogenated acrylonitrile-butadiene copolymer from the latex a mixing step is carried out in which the hydrogenated acrylonitrile-butadiene copolymer is first mixed with an amine group containing compound and next the hydrogenated acrylonitrile-butadiene copolymer is mixed with a compound that is capable of reacting with an amine, wherein the compound that is capable of reacting with an amine group is a compound selected from the group consisting of phthalic acid anhydride, maleic anhydride, acetic anhydride, stearic anhydride, tetrahydrophthalic acid anhydride, cyclohexanedicarboxylic acid anhydride, nadic anhydride and succinic anhydride.