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EP-3419092-B1 - ION-CONDUCTING MEMBRANE PRODUCTION METHOD AND PRODUCTION DEVICE

EP3419092B1EP 3419092 B1EP3419092 B1EP 3419092B1EP-3419092-B1

Inventors

  • FUKUDA, SEIJI
  • YABUUCHI, Yuko

Dates

Publication Date
20260506
Application Date
20170201

Claims (12)

  1. A method for producing an ion-conducting membrane containing a polymer having an ionic group, the method comprising: a plurality of times of liquid treatment steps of bringing a precursor membrane that contains a polymer containing a salt of the ionic group with an impurity ion into contact with an acid treatment solution or an alkali treatment solution, wherein in the plurality of times of liquid treatment steps, a liquid treatment time in each of second and subsequent liquid treatment steps is shorter than a liquid treatment time in a first liquid treatment step, the plurality of times of liquid treatment steps be performed continuously.
  2. The production method according to claim 1, wherein the liquid treatment time in each of the second and subsequent liquid treatment steps is two-thirds or less of the liquid treatment time in the first liquid treatment step.
  3. A device for producing an ion-conducting membrane containing a polymer having an ionic group, the device comprising: a plurality of liquid treatment tanks for bringing a long precursor membrane that contains a polymer having the ionic group capable of forming a salt with an impurity ion into contact with an acid treatment solution or an alkali treatment solution, wherein in the plurality of liquid treatment tanks, second and subsequent liquid treatment tanks are smaller than a first liquid treatment tank, wherein the device is capable of continuously conveying the precursor membrane, and wherein in the device, the plurality of liquid treatment tanks is arranged such that the precursor membrane is brought into contact with a treatment solution in the second and subsequent liquid treatment tanks after bringing into contact with a treatment solution in the first liquid treatment tank.
  4. The production device according to claim 3, wherein the second and subsequent liquid treatment tanks each have an internal volume that is two-thirds or less of an internal volume of the first liquid treatment tank.
  5. The production device according to claim 3 or 4, comprising a liquid treatment section for a precursor membrane including a liquid treatment tank and a liquid supply tank adjacent to the liquid treatment tank, the device having a mechanism for circulating a treatment solution sent from the liquid supply tank to the liquid treatment tank and overflowed from the liquid treatment tank to the liquid supply tank, and a mechanism for supplying a new treatment solution.
  6. The production device according to claim 5, wherein the liquid treatment section includes a plurality of liquid treatment tanks, and liquid supply tanks equal in number with the liquid treatment tanks.
  7. The production device according to claim 5 or 6, wherein a direction in which the treatment solution overflows from the liquid treatment tank is a direction parallel to a surface of the precursor membrane.
  8. The production device according to any one of claims 3 to 7, comprising, following the liquid treatment section, a washing section in which an ion-conducting membrane obtained by liquid treatment of the precursor membrane is washed, a drying section in which the washed ion-conducting membrane is dried, and a winding section in which the dried ion-conducting membrane is wound up.
  9. The production device according to claim 8, wherein the washing section has a mechanism for subjecting the ion-conducting membrane to immersion washing in deionized water in multiple stages, and a mechanism for subjecting the ion-conducting membrane to shower washing in multiple stages.
  10. The production device according to claim 8 or 9, wherein the drying section has a mechanism including a decompression device, and a suction conveyor roll of which at least a roll surface is made from a porous material and which is connected to the decompression device.
  11. The production device according to any one of claims 8 to 10, wherein the winding section has a mechanism for winding up the ion-conducting membrane with a winding tension being controlled to be constant.
  12. The production device according to claim 5, comprising a mechanism for individually controlling a liquid sending speed from the liquid supply tank to the liquid treatment tank.

Description

TECHNICAL FIELD The present invention relates to a method and a device for producing an ion-conducting membrane. BACKGROUND ART Ion-conducting membranes typified by ion-exchange membranes, polymer electrolyte membranes, and the like are functional membranes having ion conductivity and electron insulating properties. Ion-exchange membranes include cation-exchange membranes having cation conductivity and anion-exchange membranes having anion conductivity. Cation-exchange membranes and anion-exchange membranes are widely used in the field of electrolytic industries based on the combination of properties of both the membranes, and are also started to be used in applications requiring high-quality membranes, such as pharmaceutical manufacturing. Recently, use of polymer electrolyte membranes having hydrogen ion conductivity and hydroxide ion conductivity is also expected to expand. Polymer electrolyte membranes are used in polymer electrolyte fuel cells that convert hydrogen or hydrocarbons into electric energy, hydrogen production devices that produce hydrogen from water, electrochemical hydrogen compressing devices, and the like as a catalyst coated membrane including an electrolyte membrane and a catalyst applied or transferred to the electrolyte membrane, or a membrane electrode assembly including a catalyst coated membrane and electrodes attached to the catalyst coated membrane. For the promotion of diffusion of fuel cells and utilization of hydrogen energy, not only quality improvement of polymer electrolyte membranes but also a low-cost mass production method and a low-cost production device for polymer electrolyte membranes are desired. Ion-exchange membranes and polymer electrolyte membranes that are ion-conducting membranes usually contain a polymer having an ionic group. Methods for introducing an ionic group into a polymer are roughly divided into a method of polymerizing a polymer using a monomer having an ionic group, a method of introducing an ionic group into a polymer by a polymeric reaction, and a method of forming a membrane of a polymer and then introducing an ionic group into the membrane-shaped polymer likewise by a polymeric reaction. Since the ionic group is in a state of a salt (ion pair) with a counter ion such as a metal ion or a halogen ion in the course of the synthesis reaction, in any of the methods, it is necessary to finally convert an ion-conducting membrane capable of exhibiting its functions by exchanging a metal ion with a hydrogen ion by acid treatment or exchanging a halogen ion with a hydroxide ion by alkali treatment. Hereinafter, a membrane that contains a polymer containing a salt of the ionic group with an impurity ion and a counter ion and that is in a state before being converted into an ion-conducting membrane by liquid treatment with an acid solution or an alkali solution is referred to as a "precursor membrane". In the production of an ion-conducting membrane by the above-mentioned method, any metal ions or halogen ions remaining as impurities in the ion-conducting membrane cause deterioration of ion conductivity and electron insulating properties as well as deterioration of durability. In order to reduce the concentration of impurity ions such as metal ions and halogen ions in the ion-conducting membrane, however, it is necessary to use a large amount of treatment solution in the liquid treatment, which prevents to reduce its production cost. As a technique for reducing the amount of use of the treatment solution, Patent Document 1 discloses, as a method for producing a polymer electrolyte membrane including, in acid treatment, immersing a precursor membrane in an acidic solution a plurality of times, a liquid treatment method for a hydrocarbon polymer electrolyte membrane including cascade-conveying a film to a plurality of immersion tanks filled with an acidic solution, and continuously supplying the acidic solution while overflowing the acidic solution in a cascade method in a direction opposite to the film conveying direction. Patent Document 2 teaches a device for impregnating web-shaped material with thermosetting impregnating resin, comprising an impregnating trough in which the web-shaped material is brought into contact with the impregnating resin, a feed line leading to the impregnating trough through which the impregnating resin is introduced into the impregnating trough, and a heating device, which heats the impregnating resin. The heating device is assigned to the inlet line and heats the impregnating resin in the inlet line. Patent Document 3 relates to the manufacture a product which has only a small amount of a salt remaining in a polymer electrolyte membrane and is industrially uniform without generating a large amount of waste liquid in a step of converting a polymer electrolyte precursor membrane to the polymer electrolyte membrane having a protonic conductivity by exchanging an acid metal salt group in the precursor for protons in an acidic so