Patent ID: 6887935
Filing Date: 2005-05-03
Classification: C08F

Abstract:
1. Improved method for preparing a cross-linked water soluble cationic (meth) acrylamide/quaternary ammonium salt copolymer that is useful as a flocculant, said method comprising 1) initiating polymerization of an aqueous reaction mixture comprising (meth) acrylamide monomers and quaternary ammonium salt monomers to convert said monomers into a copolymer containing reaction mixture comprising cationic poly (meth) acrylamide/quaternary ammonium salt copolymer; and 2) cross-linking said copolymer by addition of a cross-linking agent to said copolymer containing reaction mixture; wherein said step of 2) cross-linking comprises waiting until about 50% or more of said monomers have been converted into said copolymer and then continuously adding between about 1 ppm to about 500 ppm of said cross-linking agent to said copolymer containing reaction mixture based on the total amount of said reaction mixture in the absence of concurrent addition of any chain transfer agent to said copolymer containing reaction mixture.