| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for preventing stains due to pitch derived from waste paper or mechanical pulp. SOLUTION: This method comprises the following process: prior to sheet formation, a paper manufacturing stock consisting mainly of mechanical pulp is incorporated with a copolymer of a quaternary ammonium salt group- containing monomer and a nonionic monomer, preferably a copolymer in the form of a dispersion of microparticles <=100μm in size produced by dispersion polymerization method in an aqueous salt solution in the presence of a polymeric dispersant soluble to the aqueous salt solution, followed by making a papermaking operation.
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