| 摘要 |
PROBLEM TO BE SOLVED: To provide a membrane separation element having excellent durability in use constituted of a separation membrane of remarkably improved durability including strength and resistance to bending in the vicinity of its fixed part without sacrificing its excellent characteristics such as its excellent separation function. SOLUTION: The membrane separation element is constituted of a pair of flat separation membranes 1 each disposed on either side of a holder 7 with each of the flat separation membranes 1 attached to the holder 7 on its outer peripheral edge. A composite separation membrane constituted of a base layer 2 and a porous layer 4 having a separation function is employed in the above flat separation membranes 1. The base layer 2 of the composite separation membrane is comprised of a peripheral thick-walled part 2A having a thickness 1.1 to 3 times greater than that of its central part with the peripheral thick-walled part 2A disposed in the vicinity of and attached to the outer peripheral edge of the holder 7 and the ratio of the surface area of the peripheral thick-walled part 2A of the base layer 2 relative to the permeation surface area of the separation membrane 1 being not lower than 1% and not higher than 30%. COPYRIGHT: (C)2008,JPO&INPIT
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