| 摘要 |
A casting dope 27 is cast onto a running belt 46 to form a casting film 69. Drying devices are disposed in both sides of the casting belt 46, so as to dry the casting film 69. The casting film 69 is conveyed through drying zones in which drying temperatures are respectively determined according to the content of remaining solvent in the casting film 69 on the basis of the graph of film production limit line that is different between the main compounds of the solvent. Then the drive conditions of each drying device were set, such that the drying of the casting film 69 might be made at the drying temperature. Thus the drying temperatures are previously determined adequately to the content of remaining solvent. Therefore, the drying of the casting film can be made without a large luck of supply with thermal energy and the like.
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