METHOD FOR PRODUCING OPTICAL FILM

摘要

PROBLEM TO BE SOLVED: To provide a method for producing an optical film containing a cellulose acetate resin having a low substitution degree in which a casted membrane 12 is easily peeled off while elongation of the casted membrane 12 is depressed upon peel-off and which is easily adaptable to conveyance of the casted membrane 12 at a high speed so as to inhibit break of the casted membrane 12.SOLUTION: A dope containing a cellulose acetate resin having a low substitution degree and solvent is casted on a support medium to form a casted membrane in a casting step. The casted membrane is peeled off from the support medium at a central part in a width direction and both edge parts in the width direction simultaneously and is conveyed to a take-up roll in a peel-off and conveyance step. The casted membrane is taken up with the take-up roll in a take-up step. The casted membrane is tensed in a conveyance direction at both edge parts in the width direction with tension-applying rolls arranged in a high residual solvent content conveyance region where the casted membrane has a residual solvent content of 45 mass% or more within a conveyance region from the peeling-off position of the casted membrane to the take-up roll in the peel-off and conveyance step described above.