| 摘要 |
The present invention inhibits retardation irregularities in an optical film and contributes to enabling larger liquid crystal display devices. A method for producing an optical film, comprising an extruding step in which a melt containing a thermoplastic resin is extruded from a casting die (12) into a film form and a cooling step for cooling the extruded melt film, includes, between the extruding step and cooling step, a heating step for heating the extruded melt film (31) using a heating device (51). In accordance with the heating step, on the basis of the thickness distribution in the width direction of the melt film (31), one of the following is performed: the portion that is relatively thin is heated; the portion that is relatively thin is heated at a higher temperature than the portion that is relatively thick; the portion that is relatively thin is heated for a longer period of time than the portion that is relatively thick; or the portion that is relatively thin is heated for a longer period of time and at a higher temperature than the portion that is relatively thick. |
