| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To obtain a thin cellulose ester film having excellent strength and preferable optical characteristics. <P>SOLUTION: A dope 12 is prepared by dissolving solid content such as a cellulose ester, additives or the like in a mixed solvent. The dope is cast on a casting drum 17 with a temperature of -5°C from a casting die 16 so that a film thickness after drying becomes 40μm and the cast film is peeled off as a gel film 20 by a roller 21. A tension of 60 kg/m is applied to the gel film 20 by a tenter 22 when the solvent in the gel film 20 is 100-200% by weight of the solid content and a temperature is set to 120°C to obtain a film 23. In the IR spectrum of the film 23, a peak showing a crystallized polymer is observed at 520-480 cm<SP>-1</SP>. The tear strength of the film is 12g, Rth thereof is 42 nm and Re thereof is 1.2 nm. Since the polymer is crystallized even in the thin film 23, the film has sufficient strength and optical characteristics. <P>COPYRIGHT: (C)2004,JPO</p> |
