INTERNAL SIZING AGENT FOR PAPERMAKING AND USE THEREOF

摘要

The invention aims at providing an internal sizing agent for papermaking which contains calcium carbonate as the loading material and which can efficiently impart sizing effect even in neutral papermaking wherein aluminum sulfate is not used or a reduced amount of aluminum sulfate is used; and paper and paperboard produced by using the sizing agent. The aim is attained by an internal sizing agent for papermaking which contains as the active principle an amphoteric copolymer which bears hydrophobic groups and whose cationic groups are at least partially quaternized, preferably one which is prepared by polymerizing a monomer component comprising as the essentials a hydrophobic monomer (A), a cationic monomer (B) and an anionic monomer (C) with the anion equivalent value due to the monomer (C) corresponding to 0.1 to 90% of the cation equivalent value due to the monomer (B) and which has a degree of quaternization of the cationic groups of 40% by mole or above; and paper or paperboard, containing the sizing agent.