| 摘要 |
PROBLEM TO BE SOLVED: To obtain a film with a high retardation value in the thickness direction. SOLUTION: A cast film formed by casting a dope comprising cellulose acylate and a solvent on an endlessly running casting drum is peeled off from the casting drum to obtain a wet film 38. A tenter 13 is composed of first to third drying regions A1-A3 with different temperatures. A plurality of pins are inserted into both side end parts of the wet film 38 to hold the film, and while the film is conveyed in the tenter 13, drying is performed to obtain a film 20. The width of the wet film 38 is narrowed in the first drying region A1, kept in the second drying region A2, and expanded in the third drying region A3. In addition, the temperature of the second drying region A2 is made higher within a range of 30-100°C than that of the first drying region A1. A contracting force acts on the wet film 38 thereby, and as molecular orientation in the face direction and the thickness direction is controlled, a film 20 with a high retardation value in the thickness direction is obtained. COPYRIGHT: (C)2009,JPO&INPIT |
