MANUFACTURE OF SHRINKABLE POLYPROPYLENE RESIN FOAMED SHEET AND LAMINATED SHEET

摘要

PURPOSE:To impart heat shrinkability to a polypropylene type resin foamed sheet without carrying out stretching operation by carrying out specific taking-up operation in the extrusion foaming of a polypropylene type resin. CONSTITUTION:The foamable resin composition emitted from a die 2 is blown up under foaming to be applied to a plug 3. The foamed sheet 1 comes into contact with the front stage of the plug 3 within which water is circulated at 0 deg.C to be cooled. Subsequently, the foamed sheet is applied to the rear stage of the plug 3 having a diameter 110% or less that of the front stage thereof to be taken up. Since the diameter of the rear stage of the plug is larger than that of the front stage thereof, the tension acting on the foamed sheet by taking-up is supported by the front of the rear stage of the plug. Therefore, no tension of a necessary degree or more acts on the foamed sheet in a molten state between the die and the plug and a polypropylene type resin composition low in taking-up strength at the time of melting becomes the continuous foamed sheet without being cut. Further, by controlling the heating condition in the rear stage of the plug, shrinkability is imparted to the foamed sheet in the taking-up process.