PRODUCTION OF NON-CROSSLINKED PROPYLENE TYPE RESIN FOAMED SHEET AND NON-CROSSLINKED PROPYLENE TYPE RESIN FOAMED SHEET

摘要

PROBLEM TO BE SOLVED: To provide a method of producing a non-crosslinked PP type resin foamed sheet containing fine air bubbles, good in appearance, excellent in productivity, extrusion stability and the productivity enhancing effect of a highly magnified thin article and capable of reducing the generation of wavy inferiority in a sheet end part, and the non-crosslinked PP type resin foamed sheet. SOLUTION: In a method for producing a non-crosslinked PP type resin foamed sheet, an extrusion foaming apparatus equipped with a gear pump connected between an extruder and a die by an adaptor is used and the inlet pressure (Pg) of the gear pump is within a range of Pc=Pg (atm)=Pc+90 and Pc=(x-1)/H wherein x is theoretical expansion ratio when an added foaming agent is held to 100% and H is the solubility coefficient [cm3 (STP)/ cm3.atm] of foaming gas into a resin at the resin temp. at the inlet of the gear pump] and the extruder is controlled so that Pg becomes constant.