To provide a method for producing an optical film, in which the optical film having such retardations sufficiently close to zero can be obtained even if the optical film is stretched that the in-plane direction retardation is 0-5 nm and the thickness direction retardation is -5 to 5 nm.
The method for producing the optical film comprises: a flow casting step of flow-casting a resin solution, which is obtained by dissolving a transparent resin and a compound having negative orientational birefringence in a solvent, on a traveling support to form a flow casting film; an exfoliation step of exfoliating the flow casting film from the support as a film; a drying step of drying the solvent in the exfoliated film; and a stretching step of stretching the film having ≤1 mass% residual solvent rate at the temperature higher than the glass transition temperature of the film by 30-100°C.
Masataka Otani
Satoshi Sakurai