Optical film, method for producing the same and polarizing plate using the same

摘要

A method for producing an optical film comprising the steps of: (i) melt casting a cellulose ester resin or a cycloolefin resin by extruding melt of the cellulose ester resin or the cycloolefin resin from a die onto a roll-shaped cooling drum; (ii) cooling and solidifying the extruded melt to form a film; (iii) stretching the film in a lateral direction of the film; and (iv) winding the film in a roll, wherein the cooling drum has plural regions divided predeterminedly in an axis direction of the cooling drum, a temperature of each region being independently controlled.