Patent ID: 7160499
Filing Date: 2007-01-09
Classification: B29C,B29K,B29L

Abstract:
1. A method for making an inflation film by an air quenching inflation molding comprising: extruding a raw resin in a molten state through a circular die to form a tubular film, expanding said tubular film by the pressure of a gaseous medium introduced into an inner space of the tubular film, while the tubular film is being cooled to be solidified by blowing a cooling gas to the outer surface of the tubular film from a cooling ring disposed at a location between the circular die and guide members and opposing the outer surface of the tubular film, and drawing the film while being progressively flattened by guide members, wherein the temperature Tf (° C.) of the solidified tubular film at the time it contacts the guide member for the first time is measured by a temperature sensor and the measured temperature Tf(° C.) is so adjusted as not to be higher than Tr (5); wherein Tr (5) represents the temperature at which a thermal deformation ratio of the solidified tubular film becomes 5% when it is measured, being loaded with a stress of a value equal to the frictional force received from the guide members under the conditions of manufacture of the film.