| 摘要 |
PROBLEM TO BE SOLVED: To obtain a surface sizing agent with improved sizing effect and slight tackiness when remoistened, by emulsion copolymerization between each specific hydrophobic monomer and anionic monomer in the presence of a specific (meth)acrylamide-based copolymer. SOLUTION: This surface sizing agent is obtained by emulsion copolymerization between at least one kind of hydrophobic monomer (b1 ) selected from the group consisting of styrene compounds and alkyl (meth) acrylates (e.g. styrene) and at least one kind of anionic monomer (b2 ) selected from the group consisting ofα,β-unsaturated monocarboxylic acids andα,β-unsaturated dicarboxylic half esters (e.g. (meth)acrylic acid) in the molar ratio b1 /b2 of (40-80):(60-20) in the presence of a (meth)acrylamide-based copolymer prepared by copolymerization between 40-96 mol.% of (meth)acrylic acid amide, 3-30 mol.% of a hydrophobic monomer and 1-30 mol.% of a carboxylic acid group- contg. monomer at 0.25-5 wt.% based on the total weight of the above (b1 ) and (b2 ) components, followed by neutralization of the resulting copolymer with an alkali.
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