Method of manufacturing newsprint containing newsprint for rosin emulsion sizing agent

摘要

PROBLEM TO BE SOLVED: To obtain a rosin-based emulsion sizing agent affording good sizing effect in a small amount of addition even in a papermaking system for newsprint paper containing a large amount of calcium carbonate derived from deinked pulp.;SOLUTION: The rosin-based emulsion sizing agent for newsprint paper is obtained by dispersing a rosin-based resin in water by the use of a dispersant comprising a copolymer. In this sizing agent, the copolymer is made up of a (meth)acrylamide, a hydrophobic monomer, a sulfo(salt)-containing monomer and a carboxy-containing monomer as constituents, the (meth)acrylamide accounts for 20-70 wt.% of the total monomers, and the carboxy groups are not alkali-neutralized. For the newsprint paper, 80 wt.% or more of the total pulp ingredient is made from waste paper, or the like. In the papermaking system, since the interaction of the sizing agent with calcium carbonate and staple fibers derived from waste paper pulp is mitigated, the proportion of the sizing agent adsorbed to the staple fibers, or the like, and tending to escape into an effluent system is reduced, thus improving the yield of the sizing agent and accomplishing good sizing effect.;COPYRIGHT: (C)2005,JPO&NCIPI