Patent ID: 8241462
Filing Date: 2012-08-14
Classification: D21H

Abstract:
1. A papermaking internal sizing agent comprising as an effective ingredient an amphoteric copolymer having hydrophobic groups and cationic groups, at least a part of the cationic groups being quaternized, wherein the amphoteric copolymer is obtained by polymerizing monomer ingredients that essentially contain a hydrophobic monomer (A), a cationic monomer (B), and an anionic monomer (C) and that an anion equivalent of the monomer (C) is 0.1 to 90% of a cation equivalent of the monomer (B), in which a rate of quaternizing of the cationic groups is 40% to 90% by mole, and wherein the cationic monomer (B) is at least one kind selected from the group consisting of a tertiary amino group-containing (meth)acrylamide and a tertiary amino group-containing (meth)acrylate.