PURPOSE: To obtain a film, which is stabilized, has no thickness irregularity and is oriented uniformly, by heating a non-oriented raw-fabric film in a heating atmosphere containing steam, keeping the moisture content of the ethylene-vinyl acetate copolymer saponified substance (EVOH) of an outer layer within a specific range and orienting the film.
CONSTITUTION: A cylindrical film using EVOH as an outer layer and a polypropylene resin layer as an inner layer is extruded downward through a co-extrusion inflation molding system, and cooling water is brought into contact directly with the outside of the gradually extruded cylindrical film and the film is cooled, thus acquiring a non-oriented raw-fabric film. The non-oriented raw-fabric film obtained is heated at an orientation temperature, and a laminated biaxially oriented film is manufactured through tubular biaxial orientation. When the non-oriented raw-fabric film is heated, the moisture content of the EVOH of the outer layer is brought to 5-15wt.% by heating the non-oriented raw-fabric film in a heating atmos. phere containing steam, and the film is oriented. An EVOH layer is supplied with moisture even in a process in which the raw-fabric film is heated so as to reach an orientable temperature, thus stably manufacturing the uniformly oriented film having no thickness irregularity.
HAYASHI KATSUHIKO
SAKURAZAWA YOSHITERU
SHIMOFUSACHI TAKESHI
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