PRODUCTION METHOD OF OPTICAL FILM

摘要

PROBLEM TO BE SOLVED: To provide an optical film for imparting desired retardation to transmitted light by aligning a liquid crystal by a photo-alignment film, in which the liquid crystal relating to a retardation layer can be aligned into a desired direction with high accuracy.SOLUTION: A production method of an optical film is provided to produce an optical film that imparts desired retardation to transmitted light by drawing a transparent film substrate from a roll and successively treating the film while conveying the film. The method includes: an application step of applying a coating liquid of a photo-alignment layer on the substrate drawn from the roll; a baking step of heating the substrate coated with the coating liquid in the application step so as to scatter a solvent component of the coating liquid applied on the substrate and to form a photo-alignment film material layer; an exposure step of irradiating the photo-alignment film material layer with linearly polarized UV rays to produce a photo-alignment film; and a production step of a retardation layer for applying a coating liquid of the retardation layer on the photo-alignment film and then drying and curing the coating liquid to produce the retardation layer. The heating temperature in the baking step is varied based on the measurement result of an alignment direction of the retardation layer in the retardation layer.