| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing medium quality paper, comprising compounding a paper raw material consisting mainly of waste paper or mechanical pulp, by which the medium quality paper is obtained in an improved yield without causing the staining of the paper, such as a pitch trouble. SOLUTION: This method for producing the medium quality paper, characterized by treating one or more non-added paper raw materials with (A) a cationic water-soluble polymer, respectively, mixing the treated raw materials with the other paper raw materials, adding (B) a cationic water-soluble polymer and an anionic water-soluble polymer comprising to the paper raw material mixture, and then making the paper from the mixture, wherein the anionic water-soluble polymer comprises a dispersion which has a particle diameter of <=100μm and is produced by subjecting a monomer mixture comprising 5 to 100 mol.% of (meth)acrylic acid and 0 to 95 mol.% of acrylamide to a dispersion polymerization method in an aqueous salt solution in the coexistence of a polymer dispersant soluble in the aqueous salt solution.
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