| 摘要 |
PROBLEM TO BE SOLVED: To obtain a sizing agent for papermaking having excellent sizing effect, hard water-diluting stability and stability with time in the papermaking range of pH 5.5-9. SOLUTION: This sizing agent consists of a rosin-based material, an emulsifier and water and the rosin-based material consists of a mixture or a rosin ester (A) obtained by thermal reaction of rosin (a) and a polyhydric alcohol (b) and a fortified rosin (B) or a fortified rosin ester (C) obtained by thermal reaction of rosin (a), a polyhydric alcohol (b) and anα,β-unsaturated carboxylic acid (c) and the emulsifier consists of an anionic copolymer obtained by copolymerization of 21-29 mol.% carboxyl group-containing monomer and/or its salt (1), 48-68 mol.% (meth)acrylamide (2), 3-10 mol.% sulfo group-containing monomer (3) and 8-13 mol.% hydrophobic monomer (4).
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