| 摘要 |
PURPOSE: To curtail a cooling time before treatment by a method in which the inner wall of a formed hollow body is treated directly by a reactive gas in a line to increase impermeability, and the inner wall of the hollow body is surfacewise by gas introduced at a specified temperature or below. CONSTITUTION: A hollow body like a gasoline tank is produced from a thermoplastic substance by extrusion blow molding. The inner wall of the molded hollow body is treated directly by a reactive gas in a line to increase its impermeability. In order to treat by the reactive gas, the inner wall of the hollow body is cooled surfacewise by gas introduced at -50 deg.C or below. In general, the temperature of the gas to be introduced into a tank is preferably -60 to -150 deg.C. The considerably low temperature gas to be introduced into the tank cools only the thin surface membrane of the inner wall uniformly, quickly, and completely, and the temperature of the residual part of the tank wall is left substantially unchanged. |
