PURPOSE: To obtain the subject paper with high yield of filler, ultra-fine fiber, sizing agent, etc., excellent in dry strength and useful for newspaper, etc., by adding a specific amphoteric copolymer to pulp slurry containing high-yield pulp and making the pulp slurry into paper.
CONSTITUTION: Pulp slurry containing ≥30wt.% (based on total dry weight of pulp) high-yield pulp is prepared and an amphoteric copolymer composed of (A) 98-50mol% (meth)acrylamide, (B) 1-20mol% carboxylic acid based compound selected from a group consisting of α,β-unsaturated monocarboxylic acid such as acrylic acid and α,β-unsaturated dicarboxylic acid such as maleic acid and these salts and (C) 1-30mol% diallylamine based monomer expressed by the formula (R1 and R2 are H or methyl; HX is acid) is added to the pulp slurry, preferably in a slurry amount of 0.05-3wt.% (based on dry weight of pulp) and the mixture is made into paper to provide the objective paper.
KONDO NORIO
MAKINO SHIGETO
TANIKAWA AKIRA
