Process and apparatus for forming a plastic film
AssigneeUnion Carbide Corporation
InventorsShigeo Fujitani, Youichi Matsuda
Life of this patent
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Abstract
A plastic film is formed by annealing a molten tubular film in a first enclosed space and immediately thereafter directing cold air perpendicular to the axis thereof and expanding and solidifying the film in a second enclosed space while in contact with cold air flowing parallel to film travel.
Claims6
In a process for forming a plastic film from a thermoplastic resin by blow-film extrusion, the improvement which comprises subjecting the molten tubular film extruded from a die to annealing in a first enclosed space, immediately thereafter blowing cold air for rapid cooling to the outer surface of said tubular film in the direction perpendicular to the axis thereof, and permitting said tubular film to expand and solidify in a second enclosed space, while it is in contact with cold air flowing in the same direction as said tubular film travel.
An apparatus for forming a plastic film which comprises a molten resin extrusion die having a circular die lip and an air port, an annealing chamber of cylindrical body installed concentrically outside said die lip, an air ring which is installed in contact with said annealing chamber and is provided with a blow-off slit which opens horizontally at the end of a circular air passage and with apertures of slits and/or holes formed on the upper plate ring thereof, and an air flow rectifying cylindrical body installed outside said apertures on said upper plate ring.
Dependencies are inferred from the claim text.