| 摘要 |
<P>PROBLEM TO BE SOLVED: To efficiently form a precoat in an aid filtration system. <P>SOLUTION: A filter aid is dispersed into a raw material dope 41, and it is filtered by a first filter 47 or a second filter 48. A filter aid is deposited on a filter medium support 60 within the filters 47, 48, and, using a filter medium 63 composed of the filter medium support 60 and a deposition layer, the raw material dope 41 is efficiently filtered. When the filtering pressure is made high, the filters 47, 48 are changed, a cleaning liquid is made to flow through the used filter, and it is cleaned. After the cleaning, a precoat liquid 61 is circulated, and a filter aid is uniformly deposited on the filter medium support 60, so as to form a precoat 62a having prescribed strength on the filter medium support 60. The raw material dope 41, a filter assist solution 56 and a solvent 70 for dilution are charged to a precoat liquid preparation tank 65, and a precoat liquid 61 is prepared. Since the raw material dope 41 is diluted, and the precoat liquid is formed, a suitable settling rate can be secured, and a filter medium in which thickness by the filter aid is uniform can be obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT |
