| 摘要 |
PURPOSE:To obtain a molded body which is excellent in compression strength and small in heat resistant shrinkage factor by filling polypropylene-based expandable particles wherein the amount of heat of melting in an endothermic peak shown in the high temp. side is regulated to at least specified value into a mold so as to obtain the specified shrinkage factor and thereafter heating the said particles by steam and molding them. CONSTITUTION:In the polypropylene-based expandable particles, the amount of heat of melting in a high-temp. peak of the expandable particles having secondary forming capacity which is measured by a differential scanning calorimeter is regulated to at least 4cal/g. The said expandable particles are compressed and filled into a mold at 5-40% shrinkage factor and thereafter heated by steam and molded. As the polypropyrene-based resin, the crystalline polypropylene- based resin described hereunder is shown. In other words, a homopolymer of propylene, a propylene-ethylene random copolymer, a propylene-ethylene block copolymer a propylene-butene-1 random copolymer, a propylene-ethylene-butene-1 random copolymer or the like. Thereby the molded form can be obtained which is durable for utilization in the high moisture atmosphere. |
