Abstract: A process for spiral membrane element production is disclosed which attains high productivity, eliminates the material “wrinkling” or “breakage” caused by material distortion or core tube distortion, and can increase the degree of tightening of the whole element. The process includes a step in which a multilayer structure including a feed-side passage material interposed between opposed membranes on their feed side and a permeation-side passage material interposed between opposed membranes on their permeation side is spirally wound on a perforated core tube, wherein the winding of the multilayer structure on the core tube is conducted by rotating the core tube 5 while pressing one or more rolls 15 against the periphery of the wound structure R1.

Abstract: A process for spiral membrane element production is disclosed in which creases are stably and sufficiently formed to thereby enable the later step of winding or the like to be smoothly conducted while eliminating the “wrinkling” or “breakage” caused by the distortion of creased parts. The process comprises the step of forming a multilayer structure S2 comprising a membrane 1 which has been folded, a feed-side passage material disposed on the feed side of the folded membrane 1, and a permeation-side passage material disposed on the permeation side of the folded membrane 1 and the step of spirally winding at least the multilayer structure S2 on a perforated core tube 5, wherein the folded membrane 1 is obtained by forming beforehand in a membrane a folding initiation part L2 reduced in bending resistance along each of folding lines L1 for the membrane, folding the membrane 1 at the folding initiation parts L2, and heating and pressing the membrane 1 during and/or after the folding.