PROBLEM TO BE SOLVED: To provide a method for efficiently producing vinyl resin particles having dimples on the particle surface without requiring any complicated process.SOLUTION: When polymerizing a vinyl monomer in a mixture solution, wherein droplets of the vinyl monomer containing a plasticizer are dispersed to be suspended/emulsified in an aqueous medium, inside a reactor, the inside of the reactor is pressurized by carbon dioxide while setting a polymerization rate of the vinyl monomer to 95% or less. In this way, the vinyl resin particles having dimples on the particle surface and having mean particle size of 1-200 &mum are produced.COPYRIGHT: (C)2010,JPO&INPIT【課題】粒子表面に窪みを有するビニル系樹脂粒子を、煩雑な工程を必要とせず効率よく製造する方法を提供する。【解決手段】可塑剤を含むビニル系単量体の液滴が水性媒体中に懸濁状態又は乳化状態で分散してなる混合液中の該ビニル系単量体を反応器内で重合する際に、該ビニル系単量体の重合転化率が95%以下の状態で、反応器内を二酸化炭素で加圧することにより、粒子表面に窪みを有する平均粒径が1~200μmのビニル系樹脂粒子を製造する方法である。【選択図】図2
