Ion exchange membrane for alkali chloride electrolysis, and alkali chloride electrolysis apparatus

A method for producing an ion exchange membrane for alkali chloride electrolysis, the method comprising:

• obtaining a reinforcing precursor membrane comprising a reinforcing fabric composed of reinforcing yarns and sacrificial yarns, embedded in a precursor membrane comprising a fluoropolymer having at least one group convertible to an ion exchange group, and
• then contacting the reinforcing precursor membrane with an alkaline aqueous solution to convert the at least one group convertible to an ion exchange group, to the ion exchange group, and at the same time to elute at least a portion of the sacrificial yarn in the reinforcing fabric, thereby obtaining an ion exchange membrane comprising a fluoropolymer having at least one ion exchange group,
• wherein a reinforcing material has at least a portion of the sacrificial yarns in an eluted reinforcing fabric and elution holes,
• wherein in a cross section perpendicular to a length direction of the reinforcing yarns in the ion exchange membrane, a total area (S) obtained by adding a cross-sectional area of an elution hole and a cross-sectional area of a sacrificial yarn remaining in the elution hole, is from 500 μm2 to 5000 μm2 per elution hole, and the number n of elution holes between adjacent reinforcing yarns is from 4 to 6, and
• wherein in a cross section perpendicular to a length direction of the reinforcing yarns of the reinforcing material, an average distance (d1) from the center of a reinforcing yarn to the center of an adjacent reinforcing yarn is from 800 μm to 1,000 μm.