Kanegafuchi Kagaku Kogyo Kabushiki Kaisha

Junichi Nakada

Kyoichi Nakamura

Minoru Tada

Toshiaki Yamamoto

This invention provides a process for coloring expandable beads of polystyrene resins which comprises suspending expandable beads of a polystyrene resin and a dye in water in a closed vessel and heating this aqueous suspension at a temperature above the softening point of the expandable beads, wherein the closed vessel is filled up almost completely with the aqueous suspension and heating is conducted without further addition of any blowing agent, whereby the expandable beads are impregnated uniformly with the dye. According to this process, uniformly colored expandable beads of polystyrene resins are obtained at a high efficiency of dye impregnation without using any impregnation aid or the like, the expandable beads being capable of forming beautiful molded foams of uniform color.

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Kamisu, Japan

Junichi Nakada