| 摘要 |
PROBLEM TO BE SOLVED: To obtain a TAC (cellulose triacetate) film suppressed in thickness irregularity. SOLUTION: A dope is prepared from TAC, a solvent and additives and cast in a rotary drum 31 from a casting die 30. The dope is formed into a cast film 39 on the surface 31a of the rotary drum 31 after a casting bead 38 is formed. The back 38a of the casting bead 38 is reduced in pressure by a vacuum chamber 36. The vacuum chamber 36 is constituted of four vacuum chambers 70-73 and, by providing a plurality of the vacuum chambers, it is suppressed that an accompanied wind impinges against the casting bead 38. The casting bead 38 is formed continuously, stably and uniformly and the thickness irregularity of the cast film 39 is suppressed by the stabilization of the casting bead 38. When the cast film 39 is dried, a film suppressed thickness irregularity can be obtained. COPYRIGHT: (C)2006,JPO&NCIPI |
