METHOD OF FABRICATING MULTILAYER FILM CORRECTED AT CURL

摘要

PURPOSE:To obtain a multilayer film corrected at its curl useful for packaging food or the like and fabricated by vinyl alcohol polymer layer and other thermoplastic resin layer by heating it under tension and cooling then it to thereby correct the curl of the film. CONSTITUTION:A multilayer film having curl and fabricated by vinyl alcohol polymer layer capable of melting and molding one or more layers (A) and thermoplastic resin layer except for the one or more layers (B) is moved through a heating zone under tension to heat so that the film surface temperature at the outlet of the zone becomes 80 deg. to the melting point of (A). The film is then supplied to a cooling zone to retain the ratio lomega/lalpha of the peripheral speed lomega to the peripheral speed lalpha at the final roll at the initial cooling roll is at 1.0-1.1. The cooling zone is so cooled that when the film is moved the film surface temperature becomes lower than the glass transition temperature (A) within 10 sec at heating zone passing time.