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Continuous Polymeric Tubular Film Shrinking Technique

IP.com Disclosure Number: IPCOM000096034D
Original Publication Date: 1964-Nov-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Haines, RS: AUTHOR

Abstract

Oriented polymeric tubular films, such as polyethylene terephthalate, can be continuously shrunk to size on a gaseous column. A continuous tubular film 1, which has the characteristic of shrinking in size when its internal stresses are relieved by heat, solvent or similar processes, is passed through oven 2 by gravity feed. Film 1 is heated to the appropriate temperature at which shrinking takes place in oven 2.

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Continuous Polymeric Tubular Film Shrinking Technique

Oriented polymeric tubular films, such as polyethylene terephthalate, can be continuously shrunk to size on a gaseous column. A continuous tubular film 1, which has the characteristic of shrinking in size when its internal stresses are relieved by heat, solvent or similar processes, is passed through oven 2 by gravity feed. Film 1 is heated to the appropriate temperature at which shrinking takes place in oven 2.

Alternately, film 1 can be passed through a solvent zone or a combined heat and solvent vapor zone to relieve the stresses in the film. Inside film 1 is air or another gas maintained at a pressure sufficient in magnitude to control the finally shrunk diameter of the film. The gas is supplied to the tube by air jet 3 and maintained in it at the correct pressure by magnetic valves 4.

Valves 4 include permanent magnets 5 external to film 1 and soft iron spheres 6 within the tubular film. Spheres 6 are preferably coated with a glass or polytetrafluoroethylene film to prevent the damaging of the tubular film. The magnetic field produced by magnets 5 is such that spheres 6 float within film 1 and thus act to maintain the gas pressure within the film. Film 1 is air cooled when it leaves the oven and cut into desired lengths by cutters 7.

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