AQUEOUS SOLUTION OF CATIONIC COPOLYMERS DERIVED FROM ACRYLAMIDE, PREPARATION METHOD AND USE

摘要

The present invention relates to a method for preparing an aqueous polymer solution containing at least one cationic or amphoteric (co)polymer, said method comprising the following steps: carrying out a degradation reaction, referred to as a Hofmann reaction, on a (co)polymer based on at least one non-ionic monomer selected from the group comprising acrylamide, methylacrylamide, N,N-dimethylacrylamide and acrylonitrile; post-treating the obtained aqueous polymer solution having viscosity V1; characterised in that the post-treatment comprises the following consecutive steps: obtaining an aqueous polymer solution containing at least one cationic or amphoteric (co)polymer from the Hofmann degradation reaction; post-treating said aqueous polymer solution; characterised in that the post-treatment comprises the following consecutive steps: a) adjusting the pH of the aqueous polymer solution to a value no lower than 5.5; b) lowering the pH of the aqueous polymer solution to a value of 2 to 5. The invention also relates to the use of said polymer solution as a flocculation, retention and/or drainage agent and a dry strength agent in the paper industry.