Method of producing biaxially oriented film of thermoplastic resin
AssigneeIdemitsu Petrochemical Co., Ltd.
InventorsMasao Takashige, Hidenobu Takeichi, Takeo Hayashi
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Abstract
A method of biaxially stretching a tubular thermoplastic resin to provide a film, wherein air is blown against a starting point for heating and stretching the tube, from the upstream side of the starting point, at a predetermined angle relative to the feeding direction of the film. An apparatus for achieving this method includes: two pairs of nip rolls being different in circumferential speed between the pairs; a heating-stretching section interposed between the pairs of nip rolls, for heating the tube to a temperature where the tube can be stretched; and an air ring device for blowing air in the feeding direction of the film.
Claims15
In a method of producing a biaxially oriented film of thermoplastic resin wherein a tubular thermoplastic resin film is fed into a heating zone and simultaneously stretched in both its longitudinal and transversal directions by a tensile force in the feeding direction and an internal pressure, the improvement comprising said thermoplastic resin being selected from the group consisting of a polyamide and a saponified material of an ethylene vinyl acetate copolymer and said tubular thermoplastic resin film being contacted by blowing air at room temperature against and about a stretching starting point in said heating zone so that the temperature distribution of said film is stabilized at the stretching starting point, said blowing air being supplied from an upstream side of said stretching starting point at a predetermined air blowout angle relative to the longitudinal direction of said film.
Dependencies are inferred from the claim text.