Method for producing transparent plastic molded articles and thermoforming apparatus therefor
 This invention provides a simple and advantageous method for producing plastic moldings with good surface gloss, very excellent transparency and high stiffness from crystalline polypropylene sheets manufactured by a generally employed industrial method without adversely affecting mechanical strength, shape retention at high temperatures and other properties according to a thermoforming process. This invention, more specifically, concerns a method for producing transparent polypropylene molded articles, characterized by heating a polypropylene sheet at a temperature higher than the melting point thereof, stretching it by more than 5%, rapidly cooling it to a temperature of not more than 120.degree. C., and then subjecting the thus treated sheet to thermoforming at a temperature below the melting point of the sheet. 
Sumitomo Bakelite Company Limited
Y B B Y
Y10S B29C B29C Y10S
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Kyosuke Masahiro
Miki Takeuchi