| 摘要 |
A dope containing Tac is cast onto a belt. When having self-supporting properties, the dope is peeled as a wet film from the belt, and transported to a tenter dryer. In an entrance section, a preheating is made and in an stretching section a stretching is made at a stretch speed Y(%/min). In a relaxation section, the width of the film was becomes shorter, and in the exit section, the width was kept to be uniform and transported toward the tenter dryer. A difference of a content of the remaining solvent between the stretching starting point and a relaxation end position is X. In this case, the following formula is satisfied to reduce the generation of bowing phenomena. Thus the axial diffractive of a slow axis can be reduced.
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