| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method of producing a cast film, especially an optical film, by solution casting which prevents occurrence of wind ripples and achieves good surface quality.SOLUTION: In a method of producing a cast film by solution casting which comprises applying a resin solution onto a support to form a flow casting film and evaporating the solvent in a drier, the wind speed in the horizontal direction within the drier and at a position separated upward in the vertical direction by 4 cm from the casting film is kept in a state of 0.5 m/s or lower until the casting film becomes tack-free under the condition of no control of the temperature of the support. The time of determining the tack-free is preferably the time when the temperature rising rate of the casting film becomes 0.5°C/min. or lower in the course where, after application of the resin solution onto the support, the temperature of the casting film decreases and then rises.</p> |
