METHOD OF PREPARING NON SWELLING MULTILAYER FILM

摘要

A method for manufacturing a non-swelling laminated film is provided to prevent the swelling due to the absorption of moisture without the deterioration of air permeation and waterproofness. A method for manufacturing a non-swelling laminated film comprises the steps of mixing a hydrophilic polyurethane resin and 3~5 kinds of solvents having a different boiling point to form a hydrophilic polyurethane composition; casting the hydrophilic polyurethane composition on the surface of an air permeable waterproof film having a thickness of 20~40 micrometers whose film polymer structure itself is swollen by the contact with moisture, thereby forming a laminate; heat treating the laminate with the boiling point of the solvents contained in the hydrophilic polyurethane composition by the multi-stage heat treatment from the lowest boiling point to the highest boiling point in turn, thereby forming a laminated film on which a monolith membrane having the micropore having a diameter less than 0.1 micrometers is formed; and annealing the laminated film to a room temperature.