| 摘要 |
PURPOSE:To produce easily and stably expanded polymer particles having high content of closed cells and improved moldability, by using an inorganic gas containing molecular nitrogen as a foaming agent. CONSTITUTION:1pts.wt. polymer particles, preferably polyolefin based resin and >=1.5pts.wt. liquid dispersing agent, e.g. water or ethylene glycol, and preferably a fusion inhibitor, e.g. aluminum oxide, for the polymer particles, are put into a pressurized vessel under >=20atm, preferably >=30atm pressure, and mixed, and the resultant mixture is then heated at a softening temperature of the polymer particles or above. An inorganic gas containing molecular nitrogen, preferably nitrogen gas or air is brought into contact with the mixture at the above-mentioned temperature preferably in the presence of a volatile impregnation assistant, e.g. acetone, and the resultant polymer particles and the liquid dispersing agent are released to the outside of the pressurized vessel and expanded to afford the aimed expanded particles. In case the above-mentioned expanded particles are used as a preliminarily expanded particles for hot molding, the expansion ratio is preferably 5-50 times.
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