Purification of vinyl lactam polymers

摘要

Vinylpyrrolidone and vinylcaprolactam residual monomers are removed from their respective crosslinked and non-crosslinked, vinyl lactam homopolymers, vinyl lactam copolymers and vinyl lactam terpolymers containing substantially contaminating amounts of residual vinylpyrrolidone or vinylcaprolactam monomer by a process which comprises (1) adjusting the pH of the vinyl lactam polymer slurry containing from about 1 to about 30 wt. % solids or a solution of the vinyl lactam polymer to a pH of less than 5 with an acid selected from the group of sulfuric, phosphoric, carbonic, formic and acetic acids and mixtures thereof; (2) reacting the acid with the residual vinyl lactam monomer at a temperature of from about 50 DEG to about 150 DEG C. for a period of from about 0.5 to about 10 hours until the residual monomer is reduced to less than 5 ppm and (3) drying said solids to a substantially pure vinyl lactam polymeric product in a free-flowing particulate state.