| 摘要 |
PROBLEM TO BE SOLVED: To obtain a TAC film suppressed in the occurrence of optical irregularity and lateral stepped irregularity. SOLUTION: A dope is prepared from TAC, a solvent and an additive to be cast on a rotary drum 31 at a discharge speed of 20 m/min from a casting die 30. The dope is formed into a cast bead 38 to become a cast film 39 on the rotary drum 31. The gas concentration of the vicinal region A of the back 38a of the cast bead 38 is set to 30% and the vacuum degree of the back 38a of the cast bead 38 is set to atmospheric pressure-500 Pa by a vacuum chamber 36. The cast film 39 is brought to a self-supporting film on the rotary drum 31 before peeled to obtain the TAC film. COPYRIGHT: (C)2007,JPO&INPIT |
