| 摘要 |
PURPOSE:To produce thermoplastic resin tubular foam reduced in thickness irregularity, having excellent surface smoothness and uniform fine cells and foamed in high magnification. CONSTITUTION:In a method for extruding a thermoplastic resin containing a foaming agent from an extrusion mold in a tubular form to foam the same, the hanging bell-shaped passage 23 formed by outer and inner molds 21, 22 is provided to the leading end surface of an extrusion mold 10 and a coolable over-expansion suppressing jig 20 is provided thereto and the tubular foam extruded from the extrusion mold 10 to be foamed is cooled while passed through the hanging bell-shaped passage 23 to suppress the excessive expansion of the tubular foam from the inside and outside thereof to obtain the objective tubular foam 40. The cooling of the tubular foam is performed by passing a cooling medium such as cooling water or air through the interior 24 or 27 of at least one of the outer and inner molds 21, 22. |
