| 摘要 |
PROBLEM TO BE SOLVED: To obtain a particle type surface sizing agent capable of improving sizing performances of an acidic or a neutral paper and imparting the ink jet suitability by carrying out the emulsion copolymerization of a hydrophobic monomer with a cationic monomer using a specific emulsifying and dispersing agent. SOLUTION: This particle type surface sizing agent is obtained by copolymerizing at least 79 mol.%, preferably 99.8-80 mol.% (meth)acrylamide with 0.1-20 mol.% copolymerizable other vinyl monomers such as dimethylaminoethyl (meth)acrylate in the presence of a 6-22C alkyl mercaptan in an amount of 0.01-2 mol based on 100 mol sum total of the copolymerization component monomer, providing an acrylamide- or a methacrylamide-based copolymer and then carrying out the emulsion copolymerization of 90-99.9 wt.% hydrophobic monomer such as styrene with 10-0.1 wt.% cationic monomer such as dimethylaminopropyl (meth)acrylate using the resultant (meth)acrylamide- based copolymer as an emulsifying and dispersing agent. The prepared particle type surface sizing agent has 0.05-0.4μm average particle diameter.
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