Amphoteric polyacrylamide was prepared first by the copolymerization of acrylamide with sodium acrylate and then through Mannich reaction.The copolymerization was carried out with a redox initiation system using the method of inverse emulsion polymerization.In this paper the reaction conditions and factors that affect emulsion stability were studied.Experiments show that a stable latex can be obtained under the following conditions:anionic degree is five percent,the ratio among acrylamide,formaldehyde and dimethylamine is 1∶1∶1.2,reaction temperature is 45 ℃,reaction time lasts four hours,and pH equals 5.0.The amphoteric copolymer has a higher molecular weight and cationic degree,so it is an ideal filler retention and drainage aid in paper making.
