Patent ID: 8088835
Filing Date: 2012-01-03
Classification: B29C,C08J,C08L

Abstract:
1. A method for producing an expansion-molded polypropylene-based resin article, comprising: filling a mold with expanded polypropylene-based resin particles; heating and fusing the expanded particles by using water vapor; and then cooling the fused and heated expanded particles, wherein a polypropylene-based resin having a melt index (MI) of not less than 0.1 g/10 minutes and not more than 8 g/10 minutes is used as a base resin for the expanded polypropylene-based resin particles, a shape of the expanded polypropylene-based resin particles is a pillar shape with an L/D ratio of not less than 1.5 and not more than 3, wherein the pillar shape is a shape in which a maximum diameter (Dmax) and a minimum diameter (Dmin) on a cross section perpendicular to a length direction of the expanded polypropylene-based resin particle are substantially constant along the length direction, and the D in the L/D ratio refers to an average value calculated by a following formula: a cell size of the expanded polypropylene-based resin particles is not more than 150 μm, two melting peaks are present on a DSC curve of the expanded polypropylene-based resin particles obtained by differential scanning calorimetry, and β/(α+β) is not less than 0.35 and not more than 0.75 when taking a melting calorie at the lower temperature peak as α(J/g) and taking a melting calorie at the higher temperature peak as β(J/g), the mold is filled with the expanded polypropylene-based resin particles to which an internal pressure of not less than 0.2 kgf/cm a porosity of an obtained molded article is not less than 20% and not more than 50%, the obtained molded article has a peak sound absorption coefficient of no lower than 0.82, and continuous voids are formed in the obtained molded article.