PRODUCING METHOD OF FLAT MEMBRANE ELEMENT AND FLAT MEMBRANE ELEMENT

摘要

PROBLEM TO BE SOLVED: To provide a producing method of a flat membrane element and the flat membrane element with which a filter membrane may be developed in a tense state on a filter plate and welded thereon and the filter membrane may be weld on the filter plate in a state where peripheral edge of the filter membrane is smoothly extended.SOLUTION: A sheet-shaped filter membrane 22 is arranged on surface of a filter plate 21 composed of thermoplastic resin. A plurality of convex parts 521, 522 arranged on a heating plate 51 are pressed on the filter plate 21 from peripheral part of the filter membrane 22 at a different contacting timing of each of convex parts 521, 522 to the filter membrane 22 to form a plurality of recessed jointing part 231, 232 having a different depth on the filter plate 21. The filter membrane 22 is jointed on the filter plate 21 by welding with heat at each of the recessed jointing part 231, 232 to seal a gap between the filter membrane 22 and the filter plate 21 along with peripheral part of the filter membrane 22.