| 摘要 |
PURPOSE:To prevent a foamable raw liquid from flowing out to the exterior of a metallic mold through a degassing hole even when a foaming pressure is high, by closing the degassing hole by a semirigid polyurethane foam sheet piece from the inside of the metallic mold. CONSTITUTION:A semirigid polyurethane sheet having a hardness of now lower than 200kg/JIS200phi and elasticity is used. Since open cells and closed cells coexist in the polyurethane foam sheet, the gas permeability of the sheet is lower than that of a flexible polyurethane foam. Particularly, a polyurethane foam sheet having a gas permeability of not higher than 30cc/cm<2>/sec is preferably. A thickness of the sheet piece of about 2-5mm. is sufficient, and the thickness may be further increased in accordance with the size and the depth of the metallic mold.
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