Method for producing skin-covered polyolefin resin foamed molded article

A method for producing a skin-covered polyolefin-based resin foamed molded article, comprising the steps of:

• extruding a melt comprising a polyolefin-based resin to form a parison in a softened state;
• blow-molding the parison into a skin defining a hollow interior space;
• filling multi-layered expanded beads comprising a polyolefin-based resin in the hollow interior space;
• forming holes for introducing steam into the hollow interior space through steam pins by inserting steam pins through the skin;
• and
• heating the multi-layered expanded beads filled in the hollow interior space to fuse-bond the multi-layered expanded beads to each other and to fuse-bond the multi-layered expanded beads to the skin by introducing steam into the hollow interior space through the steam pins inserted through the holes,
• wherein the multi-layered expanded beads fulfill the following requirements (a) to (e):
• (a) the multi-layered expanded beads have an apparent density of 0.03 to 0.2 g/cm3;
• (b) the multi-layered expanded beads have an average diameter of 1.5 to 3.0 mm and are formed by expanding multi-layer resin particles each having a weight of 0.2 to 0.7 mg;
• (c) the multi-layered expanded beads, when measured by heat-flux differential scanning calorimetry in which a sample thereof is heated from 23° C. to 220° C. at a heating rate of 10° C/min, gives a DSC curve which has an endothermic peak A intrinsic to the polyolefin-based resin of the multi-layered expanded beads and at least one endothermic peak B on a high temperature side of the endothermic peak A, and in which a ratio of the heat of fusion of the endothermic peak B to the total heat of fusion of the endothermic peaks is 0.15:1 to 0.25:1 and the endothermic peak B of the multi-layered expanded beads has a heat of fusion of 15 to 24 J/g;
• (d) the multi-layered expanded beads have a surface layer having a melting point lower than that of a region inside the surface layer;
• and
• (e) the polyolefin-based resin of which the multi-layered expanded beads are comprised is a polypropylene-based resin.