| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a multilayer membrane device having reduced performance variations and to provide a method for reducing performance variations of such a device. <P>SOLUTION: In the filtration device equipped with a housing having an entrance and an exit arranged apart from the entrance, and a plurality of membranes containing at least one upstream membrane and at least one downstream membrane, each membrane has almost the same grade, the upstream membrane has a first predetermined performance feature wherein the feature is selected so that the filtration device has a second predetermined feature notwithstanding the performance feature of the downstream membrane. The performance variation is reduced so that the whole performance of the device is controlled by combining two or more of membranes having a similar pore size and selecting the upstream membrane carefully based on the performance grade. The selective layer formation reduces the volume range of the device in comparison with the random layer formation and the average volume is larger than the average value of the whole of the device group. The range of fluidity can be reduced and the average value is close to the average value of the whole of the device group. The LRV range also can be reduced and the average LRV is close to the average value of the whole of the device group or higher than the average value. <P>COPYRIGHT: (C)2010,JPO&INPIT |
