| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a cellulose acylate film allowing production of a film with low color change and deterioration in mechanical strength, and manufacturing process thereof. <P>SOLUTION: A film manufacturing method employs a powdery cellulose acylate resin as a resin to be melted in an extruder 22; while the cellulose acylate resin supplied from a hopper 23a is melted in the extruder 22, discharged from the extruder 22 and delivered to a die 24. there the molten resin is extruded from the die 24 to form a film 12 by cooling and solidifying. The extruder 22 used is a twin-screw extruder with a complete-mating type screw 38 whose L/D is set in the range of 20 to 55, while the temperature of the molten resin is set at Tm+10°C to Tm+70°C wherein Tm is the melting point of the cellulose acylate resin. The average residence time, from supplying to and ejecting from the extruder 22, of the cellulose acylate resin is kept within 5 minutes, while keeping the degree of vacuum in the extruder 22 at 100 Torr or lower after the cellulose acylate resin is melted. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
