Kaneka Corporation

Kanegafuchi Kagaku Kogyo Kabushiki Kaisha

Tadayuki Ichimura

Kenichi Senda

Minori Yamaguchi

Kyoichi Nakamura

Hirofumi Maeda

Masao Ando

A pre-expanded particle made of a blend of 10 to 90% by weight of a polypropylene resin having a melt index of 6 to 10 g/10 minutes and 90 to 10% by weight of a polypropylene resin having a melt index of 0.5 to 3 g/10 minutes. The melt index of the blend being within the range of 2 to 5 g/10 minutes. The pre-expanded particles can be molded by an in-mold foaming method in a short time without causing sink to give polypropylene resin cellular molded articles having good surface property and good melt adhesion of the particles.

Pre-expanded particles of polypropylene resin, process for producing the

Resin particles made from a resin mixture of 30 to 70 wt % of a linear low-density polyethylene I having a resin density of 0.930 to 0.935 g/cm.sup.3 and an MI of 1 g/10 minutes or higher and 70 to 30 wt % of a linear low-density polyethylene II having a resin density of 0.915 to 0.925 g/cm.sup.3 and an MI of 2 g/10 minutes or higher are impregnated under pressurization with a volatile expansion agent, and released into a low-pressure atmosphere to yield non-crosslinked linear low density polyethylene preexpanded particles, which, when subjected to expansion molding inside a mold, exhibit good moldability, and yield molded articles that have an attractive external appearance and exhibit outstanding cushioning properties.

Non-crosslinked linear low density polyethylene preexpanded particles

A process for preparing pre-expanded particles of a thermoplastic resin, which comprises heating an aqueous dispersion of thermoplastic resin particles containing a volatile blowing agent to a high temperature under pressure in a pressure vessel, and releasing the dispersion into an atmosphere maintained at a lower pressure than the pressure in the pressure vessel and at a temperature of not lower than 40.degree. C. According to the process of the present invention, there can be obtained pre-expanded thermoplastic resin particles with a large average diameter of cells. By molding the pre-expanded particles obtained by the present invention, molded articles which are small in dimensional shrinkage and excellent in surface appearance can be obtained without imparting expandability to the particles or aging the particles under pressure prior to molding.

Growing community of inventors

Settsu, Japan

Tadayuki Ichimura