Patent ID: 8920917

Claim:
An expansion-molded article comprising a polypropylene resin composition comprising a polyproylene resin which is an ethylene propylene copolymer; a polyethylene wax having a viscosity average molecular weight of 2400 to 3400 wherein the polyethylene wax is an ethylene butene copolymer or an ethylene propylene copolymer; and a chemical expanding agent wherein the expanding agent is a low density polyethylene with sodium hydrogen carbonate, wherein a compounding ratio of the polyethylene wax is 1 to 4 parts by weight relative to 100 parts by weight of the polypropylene resin, characterized in that the polypropylene resin composition has an expansion rate of 1.5 to 3 times; and wherein the total capacity occupied by a cavity part of expansion cells, which respectively have an opening area of a maximum cross section of not more than 0.1 mm 2 , included in an unit volume of a part other than a skin layer of the expansion-molded article is between 60% to 75%.