Patent ID: 6894110

Claim:
A method of preparing a dispersion in an aqueous salt solution of discrete particles of a water-soluble polymer having pendant amine groups comprising a) polymerizing under free radical forming conditions one or more monomers including a vinylamide monomer of formula H 2 C═CR 2 NRC(O)R 1 wherein R, R 1 and R 2 are independently selected from hydrogen, C 1 -C 20 alkyl groups, aryl groups and alkylaryl groups in an aqueous solution of an anionic salt in the presence of one or more water-soluble stabilizer polymers selected from the group consisting of poly(vinyl alcohol), partially hydrolyzed poly(vinyl acetate), hydrolyzed poly(vinyl acetate/N-vinyl formamide), poly(vinyl alcohol/acrylamide), poly(diallyldimethyl ammonium chloride), poly(dimethylaminoethyl acrylate methyl chloride quaternary salt), poly(dimethylaminoethyl methacrylate methyl chloride quaternary salt), poly(dimethylaminoethyl acrylate benzyl chloride quaternary salt), poly (dimethylaminoethyl methacrylate benzyl chloride quaternary salt), poly(diallyldimethyl ammonium chloride/dimethyaminoethyl acrylate methyl chloride quaternary salt), poly(diallyldimethylammonium chloride/dimethylaminoethyl methacrylate methyl chloride quaternary salt), poly(diallyldimethylammonium chloride/dimethylaminoethyl acrylate benzyl chloride quaternary salt), and poly(diallyldimethyl ammonium chloride/dimethylaminoethyl methacrylate benzyl chloride quaternary salt) to form a dispersion in an aqueous salt solution of discrete particles of a water-soluble polymer having pendant amide groups; b) stirring and heating the dispersion of step a) to a temperature of about 50° C. to about 90° C.; and c) bubbling HCl gas or ammonia gas through the stirred and heated dispersion to effect the desired amount of hydrolysis of pendant amide groups to pendant amine groups.