Patent ID: 8063177
Filing Date: 2011-11-22
Classification: B29C,C08J

Abstract:
1. Pre-expanded polypropylene resin particles, characterized by being prepared by melt-kneading a polypropylene resin composition in an extruder, extruding the composition through nozzles of a die connected to the tip of the extruder into water, cutting the extruded resin composition in the water with a revolving cutter blade into polypropylene resin particles, placing the polypropylene resin particles, water, a dispersant, and an expanding agent to a pressure container to give a mixture, heating the mixture to a temperature not lower than the softening point of the polypropylene resin particles, impregnating the polypropylene resin particles with the expanding agent under pressure, and discharging the mixture out of the pressure container into low-pressure atmosphere, wherein the polypropylene resin composition contains 1 to 20 wt parts of a polyethylene resin having a melt viscosity of 10 to 2000 mPa·s at 140° C. with respect to 100 wt parts of the polypropylene resin, said polyethylene resin being at least one selected from a group consisting of polyethylenes such as high-density polyethylenes (HDPE), medium-density polyethylenes (MDPE), low-density polyethylenes (LDPE) and linear low-density polyethylenes (L-LDPE); ethylene-butene copolymers, and ethylene-vinyl acetate copolymers.