| 摘要 |
PROBLEM TO BE SOLVED: To obtain a diene copolymer latex which can attain excellent blister resistance and excellent staining resistance of a packing roll by adding a monomer composition containing acrylonitrile to the reaction mixture in the last stage of multistage polymerization, effecting the emulsion polymerization of the entire mixture, and adding potassium hydroxide to the mixture. SOLUTION: A copolymer latex is obtained by effecting the multistage emulsion polymerization of a monomer composition containing 20-70 pts.wt. conjugated diene monomer such as butadiene, 0.5-78 pts.wt. aromatic vinyl monomer such as styrene, 0.5-78 pts.wt. aromatic vinyl monomer such as styrene, 0.5-10 pts.wt. etylenically unsaturated carboxylic acid such as acrylic acid, 0.5-50 pts.wt. vinyl cyanide monomer containing acrylonitrile, and 0.1-50 pts.wt. other vinyl monomers, adding 1-20 pts.wt. monomer mixture containing acrylonitrile to the mixture in the last stage of the multistage polymerization, emulsion-polymerizing the monomer mixture, and adding 0.05-2 pts.wt. potassium hydroxide to the mixture and in which there is a difference of 1.0-4.5 between the solubility parameters of the copolymer obtained from the monomer composition added in the stage preceding to the last stage and the copolymer obtained from the monomer composition added in the last stage of the multistage polymerization.
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