| 摘要 |
PROBLEM TO BE SOLVED: To provide a foamed plastic that has excellent foaming properties, and maintains its mechanical strength when used as a foamed sheet in the field of packaging, civil engineering and construction, electronics and information, automobiles, etc., and to provide a method for manufacturing the plastic. SOLUTION: A gas that is gaseous at ordinary temperature and under normal pressure is dissolved into a plastic at a high temperature and under a high pressure. The plastic is exposed to a pressure that is lower than the pressure at the time when the gas has been dissolved into the plastic, and processed, during the exposure or thereafter, to form a sheet, wherein the two surfaces of the sheet are exposed, respectively, to atmospheres at temperatures that are different from each other, so that a plastic foamed in a gradient manner is manufactured. |
