| 摘要 |
A dope ( 36 ) containing TAC and plasticizer is produced. Foreign materials in the dope ( 36 ) are filtrated by a filtration device ( 57 ). In the filtration device ( 57 ), the dope ( 36 ) flows from an outer passage ( 58 a) to an inner passage ( 58 b) through a filter ( 59 ). The filter ( 59 ) has a first layer ( 59 a), a second layer ( 59 b), and a third layer ( 59 c), which are formed of sintered metal fibers. An average diameter of the sintered metal fibers of the first layer ( 59 a) is 8 mm, that of the second layer ( 59 b) is 4 mm, and that of the third layer ( 59 c) is 20 mm. The filter ( 59 ) is roasted 2 hours at 400° C. and reused. Breakages from the sintered metal fibers in the first and second layers ( 59 a , 59 b) are filtrated in the third layer ( 59 c).
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