PREPARATION OF POLYPROPYLONE RESIN FOREMED SHEE

摘要

According to a method of manufacturing a foamed polypropylene resin sheet (4) of this invention, a composition comprising as a resin component a mixture of 80 to 20 wt% of a crystalline propylene-ethylene block copolymer containing 20 wt% or less of ethylene and having a melt index (MI) of 2 or less and 20 to 80 wt% of a crystalline proplylene-ethylene block or random copolymer containing 5 wt% or less of ethylene and having an MI of 6 to 20 or a polypropylene homopolymer having an MI of 6 to 20 is used. A pair of molding roll dies (3) is horizontally arranged at a point separated from the center of an apex of an extrusion foaming die when a foamed sheet (4) is to be extrusion-molded. A distance between the center (10) of the roll (3) and the apex (7) of a base lip (2) is set to fall within a range of (R<2> + 25)<1/2> to (R<2> + 144)<1/2> where R is a radius of the molding roll die (3). The composition is extrusionmolded into a foamed sheet (4) without collapsing while a fluid is supplied to the interiors of the rolls (3) so that a surface temperature of the foamed sheet (4) passing between the molding rolls (3) is set at 105 DEG C or less. The extrusion-molded foamed sheet (4) is cooled thereafter.