Patent ID: 6451944
Filing Date: 2002-09-17
Classification: C08F,Y02P

Abstract:
A continuous, solvent-free process for obtaining solvent-free, fine white powders of high molecular weight alternating copolymers of maleic anhydride and a C1-C4 alkyl vinyl ether, without odor or taste, having the molecular structure (Aâ€”B)n, where A is maleic anhydride, B is an alkyl vinyl ether and n is an integer indicative of the molecular weight of the copolymer, which comprises feeding alkyl vinyl ether as reactant and solvent in excess over the desired 1:1 mole ratio of A:B in the copolymer, molten maleic anhydride and a free radical initiator, continuously at a predetermined feeding rate into a reactor heated to a reaction temperature of about 50Â° to 100Â° C., charging the reactor and withdrawing reaction product, residual alkyl vinyl ether and initiator from the reactor at the same rate as the feed rate of reactants into the reactor, simultaneously, thereby maintaining a constant volume in the reactor, stripping residual alkyl vinyl ether from the reaction product, drying the copolymer there-obtained of any remaining traces of alkyl vinyl ether, and recycling recovered alkyl vinyl ether back into reactor as reactant and solvent, wherein the mole ratio of alkyl vinyl ether to molten maleic anhydride is about 25:1 to 5:1, wherein the initiator concentration is 0.01 to 0.2% based on copolymer, wherein the % copolymer solids in the reaction product removed from the polymerization reactor is about 10 to 40%.