MANUFACTURING METHOD OF BIAXIALLY STRETCHED POLYESTER FILM

摘要

PROBLEM TO BE SOLVED: To provide a manufacturing method of a biaxially stretched polyester film having good heat sealability and good peelability and especially suitably usable as a lid material of a tray, a cup or the like comprising CPET or APET/CPET.

SOLUTION: This manufacturing method of the biaxially stretched polyester film composed of a base layer B and a heat-sealable outer layer A is composed of a process (a) for obtaining a non-stretched polyester film having at least the base layer B by an extrusion method, a first stretching process (b) for stretching the obtained non-stretched polyester film unidirectionally, a second stretching process (c) for performing stretching in the direction right angled to the first stretching direction, a process (d) for thermally fixing the obtained biaxially stretched film and a process (e) for laminating the heat-sealable outer layer formed in a separate process on the base layer B. The lamination process (e) is performed before the first stretching process (b) or between the first and second stretching processes (b) and (c).

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