Kanegafuchi Kagaku Kogyo Kabushiki Kaisha

Minoru Tada

Kyoichi Nakamura

Hitoshi Shiiki

Junichi Nakada

Toshiaki Yamamoto

The present invention provides polypropylene resin pre-expanded beads formed by shrinking polypropylene resin pre-expanded beads originally having a bulk density of not higher than 0.0930 g/cc to give them a bulk volume ratio of 10-75% at normal temperature and normal pressure, a manufacturing method thereof and an expansion-molding method with the aforementioned pre-expanded beads. According to this invention, it is possible to greatly reduce storing and transporting costs per unit weight of pre-expanded beads.

Polypropylene resin pre-expanded beads, manufacturing method thereof and

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.

Process for coloring expandable polystyrene beads

The present invention provides polypropylene resin pre-expanded beads formed by shrinking polypropylene resin pre-expanded beads originally having a bulk density of not higher than 0.0930 g/cc to give then a bulk volume ratio of 10-75% at the normal temperature and the normal pressure, a manufacturing method thereof and an expansion-molding method with the aforementioned pre-expanded beads. According to this invention, it is possible to greatly reduce storing and transporting costs per unit weight of pre-expanded beads.

Growing community of inventors

Kamisu, Japan

Minoru Tada