PAPERMAKING ADDITIVE COMPRISING A CATIONIC COPOLYMER AND A FILLER

摘要

To effectively impart sizing performance to paper, while reducing the amounts of an internal sizing agent and aluminum sulfate, the invention provides as a papermaking additive a mixture of a cationic copolymer having a hydrophobic group whose quarterization ratio is 40% by mole or more, or an amphoteric copolymer having a hydrophobic group which has the same quarterization ratio as above, and in which the ratio of the anion equivalent to the cation equivalent is 0.1 to 90%, and a filler (a pretreated filler). The pretreated filler is one in which suitable water repellency is imparted to the filler. Hence, by adding this to pulp slurry, followed by a wet papermaking, the pretreated filler is efficiently adsorbed onto pulp fibers having anionic property, so that effective sizing performance can be imparted to the paper by using a smaller amount thereof than the internal sizing agent, while reducing the amounts of the internal sizing agent and the aluminum sulfate.