Kanegafuchi Kagaku Kogyo Kabushiki Kaisha

Masakichi Kishi

Kiyoshi Mori

Toshiaki Sugita

Yoshiyuki Hashiguchi

The present invention provides a method for producing expandable thermoplastic polymer particles which comprises conducting polymerization by adding a polymerizable monomer either continuously or intermittently to thermoplastic polymer particles having a uniform particle size suspended in water, the improvement wherein an amide compound is added when the added amount of the polymerizable monomer is not more than one half of the total amount to be added in the course of polymerization and resulting polymer particles are impregnated with an easily volatile blowing agent after completion of addition of the amide compound and the polymerizable monomer. According to the present invention, expandable thermoplastic particles which are capable of giving cells, fine and uniform in size, are obtainable even by expanding immediately after production without any aging period.

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Himeji, Japan

Masakichi Kishi