| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a stretched cellulose acylate film of which the in-plane retardation Re is 100 nm or higher, and also, a relationship between the retardation Rth in the thickness direction and Re satisfies Rth<Re/2. SOLUTION: A non-stretched cellulose acylate film A is longitudinally stretched in the longitudinal direction by pulling it by a peripheral speed difference across a pair of rollers 14 and 16, and the stretched cellulose acylate film of which the in-plate retardation Re is 100 nm or higher, and of which the relationship between the retardation Rth in the thickness direction and Re satisfies Rth<Re/2 is manufactured by this manufacturing method. In the manufacturing method, the cellulose acylate film A is free-end-uniaxially stretched in such a manner that the longitudinal stretching magnification may become 1 to 2 times while heating the film at a stretching temperature in a range of the crystallization temperature Tc-10°C to Tc+70°C of the film in a heating furnace 18 which is installed between the pair of rollers 14 and 16, and also, in such a manner that the temperature difference in the film width direction may become 10°C or lower. COPYRIGHT: (C)2009,JPO&INPIT |
