| 摘要 |
PURPOSE:To obtain a polymer which generates only a small amount of fine powder and has a sharp particle diameter distribution, by starting the suspension polymerization of a vinyl monomer in an aqueous medium containing a specified salt and adding a nonionic surfactant to the reaction mixture in the latter half of the polymerization reaction. CONSTITUTION:A vinyl monomer (e.g., styrene) is suspension-polymerized in an aqueous medium in such a manner that the polymerization is started in the aqueous medium in the presence of a difficulty soluble inorganic salt (A) (e.g., calcium carbonate), an alkylnaphthalenesulfonate (B) (e.g., Na salt and a water-soluble metal salt (C) which is neutral in the aqueous medium (e.g., Na2SO4) and a nonionic surfactant (D) (e.g., polyoxyethylene alkyl ester) is added to the reaction system when the conversion is 55-75%. Agent A acts as a suspension stabilizer, agent B as an acid for the suspension stabilizer and agent C as an aid for accelerating the growth of the particle diameter after the addition of agent D as a growth agent. According to this process, vinyl polymer particles which generates only a small amount of fine powder and has a sharp particle diameter distribution can be produced.
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