POLYPROPYLENE RESIN FOAMED SHEET FOR THERMOFORMING AND PROCESS FOR PRODUCING THE SAME

摘要

A polypropylene resin foamed sheet for thermoforming having compounded therein an inorganic fine powder is disclosed. The sheet contains 10 to 50% by weight of the inorganic fine powder, has a density of 0.2 to 1.2 g/cm and a thickness of 0.2 to 3 mm and having a percent shrinkage of 5 to 30% in each of the longitudinal and crosswise directions on heating at 190.degree.C for 30 minutes, with the ratio of a residual rate in the longitudinal direction to that in the crosswise direction being from 1:07 to 1:1.1. The sheet is produced by extruding and foaming a compounded resin from a ring die of an extruder, and taking off the extruded tubular foamed sheet along a cylindrical plug whose diameter is 2.0 to 3.0 times that of said ring die.