| 摘要 |
An apparatus for the production of a tubular thermoplastic film, and more particularly, a water bath film cooling apparatus for the rapid quenching of an extruded tubular thermoplastic film so as to enhance the speed of cooling thereof, and increase the strength of the film material. Also disclosed is a method of rapidly cooling a thermoplastic film material through the intermediary of a water bath, utilizing the inventive cooling apparatus. A predetermined internal pressure is maintained within the tube by a gaseous medium, such as air, which is slightly higher than the external pressure imparted to the film tube by the water bath, so as to enhance the speed of cooling of the film materials and increase the strength of the film by minimizing the premature crystallinity thereof upon extrusion of the film and passage through the cooling apparatus. The pressure differential between the interior and exterior of the film tube is maintained by an external liquid or water column acting on the pressurized gas or air being introduced into the thermoplastic film tube, and herein the height of the water column is correlated with the height of the external water bath surrounding the film tube so as to provide for the maintenance of a predetermined pressure differential between the inside and outside of the extruded film tube during its passage through the water bath.
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