| 摘要 |
PROBLEM TO BE SOLVED: To provide a cellulose ester film suitable for a phase difference film, surely suppressing an incidence of foreign substances caused by bubble failure at a dope filtration process, producing no foreign substance, and excellent in productivity. SOLUTION: In the method of manufacturing a cellulose ester film by a solution casting film forming method, an ultrafiltration device 2 connected to a main filtrating device 1 with piping is provided together. When dope is initially filled into the main filtrating device 1, the dope whose viscosity is lowered by diluting an ordinary dope is injected initially into the main filtrating device 1 so as to expel air in the main filtrating device 1 and bubbles in the inside of a filtrating material. The low viscous dope discharged from the main filtrating device 1 is introduced to the ultrafiltration device 2, and a solvent is separated and removed to concentrate the dope. The high viscous dope discharged from the ultrafiltration device 2 is recycled to the main filtrating device 1, and thereafter the casting film forming is carried out with a dope having a predetermined viscosity for casting using the main filtrating device 1 with which the initial filling has been finished. COPYRIGHT: (C)2008,JPO&INPIT
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