AMPHOTERIC POLYACRYLAMIDES AS DRY STRENGTH ADDITIVES FOR PAPER

摘要

This invention relates to a process for making paper comprising: a) providing an aqueous pulp slurry; b) adding to the aqueous pulp slurry cationic polymer selected from the group consisting of cationic starch and cationic wet strength resin, and water-soluble amphoteric polymer made from monomers comprising: i) nonionic monomer selected from the group consisting of acrylamide and methacrylamide; ii) anionic monomer; and iii) cationic monomer, wherein the amount of anionic monomer plus cationic monomer is less than 9 mole percent of the total of anionic, cationic and nonionic monomer in the amphoteric polymer. The invention also relates to paper with improved dry strength made by said process.