| 摘要 |
PROBLEM TO BE SOLVED: To enable shortening of an aging time and a forming cycle without generation of a swell of a plastic foam-made box after removing the plastic foam-made box from a forming mold in an in-mold forming process and without prolongation of a cooling time before removing the plastic foam-made box from the forming mold in the in-mold forming process. SOLUTION: A foaming method comprises a preliminary foaming process of preliminarily foaming raw material beads impregnated with a foaming agent by heating them with steam, an aging process of aging the preliminarily foamed raw material beads and an in-mold foaming process of heating, softening and foaming the aged raw material beads to melt-bond them into a predetermined shape and then cooling the foamed item. The foaming method further includes a preliminary drying process of exposing the preliminarily foamed raw material beads to a warm wind heated to 40 to 70 deg.C before the aging process.
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