PROCESS FOR PRODUCTION OF MULTILAYER FILMS, MULTILAYER FILMS, AND MULTILAYER FILM OPTICAL ELEMENTS

摘要

The invention provides a process for the production of multilayer films by subjecting a laminated film obtained by arranging two kinds of transparent thermoplastic resin films different in refractive index alternately in the thickness direction between two protective layers to pressing or rolling, more specifically, a process for the production of multilayer films which comprises arranging a laminated film obtained by laminating two kinds of transparent thermoplastic resin films different in refractive index alternately in the thickness direction between two protective layers made of a transparent thermoplastic resin to form a laminate, (i) compression-prebonding the laminate by applying such a thicknesswise pressure that the laminated film does not cause distortion or interlaminar deviation to both outside surfaces of the laminate under such temperature conditions that the laminate does not undergo thermocompression bonding to remove gas remaining in the laminate, (ii) unifying the resulting laminate through thermocompression bonding by preheating the laminate to such a temperature as to attain thermocompression bonding and applying a thicknesswise pressure within the same range as employed in the above compression prebonding to both outside surfaces of the laminate, and (iii) subjecting the obtained laminate to pressing or rolling to form a thin film.