| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a polypropylene molding having excellent transparency and further high homogeneity while securing rigidity and heat resistance.SOLUTION: The method for producing a polypropylene molding includes a first heat treatment step for heat treating a polypropylene preliminary molding having a melting peak temperature of Tm(°C), obtained by differential thermal analysis at a temperature raising rate of 20°C/min, by heating it to a temperature in the range of from Tm(°C) to Tm+6(°C), and a second heat treatment step for heat treating the polypropylene preliminary molding subjected to the heat treatment in the first heat treatment step by heating it at a temperature in the range of from Tm-11(°C) to Tm-1(°C) for 0.5 min or more. During the time of transition from the first heat treatment step to the second heat treatment step, the temperature lowering rate or the cooling rate is set to 300°C/min or more. |
