PURPOSE: To keep moistureproof capacity stable even in a high temp. and high humidity atmosphere over a long period of time by protecting a film prepared by forming a silicon oxide membrane to a film composed of specific polyvinyl alcohol by other transparent plastic film having a silicon oxide membrane formed to the surface thereof.
CONSTITUTION: A transparent membrane 2 made of silicon oxide SiO is formed to the single surface of a PVA film 1 with a saponification degree of 99mol.% or more to form a transparent laminated film A. Next, a silicon oxide membrane 4 is formed to the single surface of a polyethylene terephthalate film 3 to form a transparent laminated film B. The B-layer has high rigidity of 15kg/mm or more in a rigidity index defined by formula I. At first, the SiO membrane of the film A and the non-SiO membrane of the film B are mutually bonded using a urethane adhesive (a) to form a two-layer laminated film. Next, a sealant film C is bonded to the film A using the adhesive (a) to obtain a transparent laminated film having a three-layer structure.
OHASHI SHINICHI
YOSHIDA SHIGENOBU
