| 摘要 |
A co-casting of plural dopes is made to form a casting film (80) of a multi-layer structure having a base layer and at least one outer layer overlapping to the base layer. A viscosity of the dope forming the outer layer is at most 35 Pa.s. Just after the formation of the casting film (80), a drying air is fed out almost in parallel to the belt 73 from an outlet 82a directed in the running direction of the belt (73), while a temperature of the drying air is controlled in the range of 70° C. to 130° C. A heater 84 heats the casting film (83) from a rear side of the belt 73 such that the temperature of a rear surface of the casting film (83) may be controlled in the range of 40° C. to 80° C. Thus the production speed can be increased and the produced film is excellent in planarity.
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