| 摘要 |
PURPOSE:To obtain pre-expanded particles having high expansion, by dispersing polymer particles impregnated with a specific expandable composition into a dispersion medium in a closed container, heating them at >= the softening temperature of the particles, releasing them from the closed container to a low-pressure atmosphere. CONSTITUTION:Polymer particles (preferably consisting of crystalline polyolefin resin, 100pts.wt. particles are impregnated with 5-30pts.wt. expandable composition) impregnated with a volatile blowing agent composition consisting of carbon dioxide and a volatile blowing agent (e.g., propane, etc.) [preferably 100pts.wt. carbon dioxide is blended with 30-600pts.wt. volatile blowing agent] are dispersed into a dispersion medium (preferably water) in a closed container, heated at temperature >= the softening temperature of the particles, the closed container is partially opened, and the particles and the dispersion medium are released from the closed container to a low-pressure atmosphere.
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