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

Patent metadata

Field	Value
Publication number	US-2017313836-A1
Application number	US-201715654124-A
Country	US
Kind code	A1
Filing date	Jul 19, 2017
Priority date	Mar 3, 2015
Publication date	Nov 2, 2017
Grant date	—

Abstract

To provide an ion exchange membrane for alkali chloride electrolysis which has a low membrane resistance and which is capable of reducing the electrolysis voltage during the alkali chloride electrolysis, while increasing the membrane strength.
An ion exchange membrane 1 for alkali chloride electrolysis wherein a reinforcing material 20 obtained by weaving with reinforcing yarns 22 and sacrificial yarns 24 is embedded in a fluoropolymer having ion exchange groups, the ion exchange membrane 1 comprises elution holes ( 28 ) formed by eluting at least a portion of a material of the sacrificial yarns 24 , and in a cross section perpendicular to the length direction of the yarns, the total area (S) obtained by adding the cross-sectional area of an elution hole 28 and the cross-sectional area of a sacrificial yarn 24 remaining in the elution hole 28 is from 500 to 1,200 μm 2 , and the number (n) of elution holes 28 between adjacent reinforcing yarns 22 is at least 10.

First claim

What is claimed is:

1 . An ion exchange membrane for alkali chloride electrolysis comprising a fluoropolymer having ion exchange groups, a reinforcing material embedded in the fluoropolymer and formed of reinforcing yarns and optionally contained sacrificial yarns, and elution holes of the sacrificial yarns present between the reinforcing yarns, characterized in that
in a cross section perpendicular to the length direction of the reinforcing yarns forming the reinforcing material, the total area (S) obtained by adding the cross-sectional area of an elution hole and the cross-sectional area of a sacrificial yarn remaining in the elution hole is from 500 to 1,200 μm 2 , and the number (n) of elution holes between adjacent reinforcing yarns is at least 10.

2 . The ion exchange membrane for alkali chloride electrolysis according to claim 1 , wherein in a cross section perpendicular to the length direction of the reinforcing yarns forming the reinforcing material, the average distance (d1) from the center of a reinforcing yarn to the center of the adjacent reinforcing yarn is from 750 to 1,500 μm.

3 . The ion exchange membrane for alkali chloride electrolysis according to claim 1 , wherein a relationship is established to satisfy the following formula (1) in a cross section perpendicular to the length direction of the reinforcing yarns:
0.5≦{ d 2/ d 1×( n+ 1)}≦1.5  (1)

provided that the symbols in the formula (1) have the following meanings,
d1: the average distance from the center of a reinforcing yarn to the center of the adjacent reinforcing yarn,
d2: the average distance from the center of an elution hole to the center of the adjacent elution hole,
n: the number of elution holes between adjacent reinforcing yarns.

4 . The ion exchange membrane for alkali chloride electrolysis according to claim 3 , wherein a relationship is established to satisfy the following formula (1′) at all measurement points measured to determine the average distance (d1) and the average distance (d2) in a cross section perpendicular to the length direction of the reinforcing yarns:
0.5≦{ d 2′/ d 1×( n+ 1)}≦1.5  (1′)

provided that the symbols in the formula (1′) have the following meanings,
d2′: the distance from the center of an elution hole to the center of the adjacent elution hole,
d1 and n: the same as above.

5 . The ion exchange membrane for alkali chloride electrolysis according to claim 1 , wherein a relationship is established to satisfy the following formula (2) in a cross section perpendicular to the length direction of the reinforcing yarns:
1.0≦{ d 3/ d 1×( n+ 1)}≦2.0  (2)

provided that the symbols in the formula (2) have the following meanings,
d3: the average distance from the center of a reinforcing yarn to the center of the adjacent elution hole,
d1 and n: the same as above.

6 . The ion exchange membrane for alkali chloride electrolysis according to claim 5 , wherein a relationship is established to satisfy the following formula (2′) at all measurement points measured to determine the average distance (d1) and the average distance (d3) in a cross section perpendicular to the length direction of the reinforcing yarns:
1.0≦{ d 3′/ d 1×( n+ 1)}≦2.0  (2′)

provided that the symbols in the formula (2′) have the following meanings,
d3′: the distance from the center of an elution hole to the center of the adjacent elution hole,
d1 and n: the same as above.

7 . The ion exchange membrane for alkali chloride electrolysis according to claim 1 , wherein the widths of said reinforcing yarns in a cross section perpendicular to the length direction of the reinforcing yarns are from 70 to 160 μm.

8 . The ion exchange membrane for alkali chloride electrolysis according to claim 1 , wherein the fluoropolymer having ion exchange groups includes a fluoropolymer having carboxylic acid functional groups and a fluoropolymer having sulfonic acid functional groups, and the reinforcing material is embedded in the fluoropolymer having sulfonic acid functional groups.

9 . An alkali chloride electrolysis apparatus comprising an electrolytic cell provided with a cathode and an anode, and an ion exchange membrane for alkali chloride electrolysis as defined in claim 1 partitioning a cathode chamber on the cathode side and an anode chamber on the anode side in the electrolytic cell.

10 . A method for producing an ion exchange membrane for alkali chloride electrolysis, which comprises obtaining a reinforcing precursor membrane having a reinforcing fabric composed of reinforcing yarns and sacrificial yarns, embedded in a precursor membrane comprising a fluoropolymer having groups convertible to ion exchange groups, and then contacting the reinforcing precursor membrane to an alkaline aqueous solution to convert the groups convertible to ion exchange groups, to ion exchange groups, and at the same time to elute at least a portion of the sacrificial yarns in the reinforcing fabric, thereby to obtain an ion exchange membrane comprising a fluoropolymer having ion exchange groups, a reinforcing material having at least a portion of the sacrificial yarns in the reinforcing fabric eluted, and elution holes, characterized in that
in a cross section perpendicular to the length direction of the reinforcing yarns forming the reinforcing material in the ion exchange membrane, the total area (S) obtained by adding the cross-sectional area of an elution hole and the cross-sectional area of a sacrificial yarn remaining in the elution hole, is from 500 to 1,200 μm 2 , and the number (n) of elution holes between adjacent reinforcing yarns is at least 10.

11 . The method for producing an ion exchange membrane for alkali chloride electrolysis according to claim 10 , wherein in a cross section perpendicular to the length direction of the reinforcing yarns forming the reinforcing material, the average distance (d1) from the center of a reinforcing yarn to the center of the adjacent reinforcing yarn is from 750 to 1,500 μm.

12 . The method for producing an ion exchange membrane for alkali chloride electrolysis according to claim 10 , wherein a relationship is established to satisfy the following formula (1) in a cross section perpendicular to the length direction of the reinforcing yarns:
0.5≦{ d 2/ d 1×( n+ 1)}≦1.5  (1)

provided that the symbols in the formula (1) have the following meanings,
d1: the average distance from the center of a reinforcing yarn to the center of the adjacent reinforcing yarn,
d2: the average distance from the center of an elution hole to the center of the adjacent elution hole,
n: the number of elution holes between adjacent reinforcing yarns.

13 . The method for producing an ion exchange membrane for alkali chloride electrolysis according to claim 12 , wherein a relationship is established to satisfy the following formula (1′) at all measurement points measured to determine the average distance (d2) in a cross section perpendicular to the length direction of the reinforcing yarns:
0.5≦{ d 2′/ d 1×( n+ 1)}≦1.5  (1′)

provided that the symbols in the formula (1′) have the following meanings,
d2′: the distance from the center of an elution hole to the center of the adjacent elution hole,
d1 and n: the same as above.

14 . The method for producing an ion exchange membrane for alkali chloride electrolysis according to claim 10 , wherein a relationship is established to satisfy the following formula (2) in a cross section perpendicular to the length direction of the reinforcing yarns:
1.0≦{ d 3/ d 1×( n+ 1)}≦2.0  (2)

provided that the symbols in

Assignees

• Asahi Glass Co Ltd

Inventors

• Kaneko Takayuki
• Kusano Hiromitsu
• Yamaki Yasushi
• Nishio Takuo

Classifications

• C08J2427/18

  Homopolymers or copolymers of tetrafluoroethylene · CPC title

• C08J5/2281 Primary

  fluorine containing heterogeneous membranes · CPC title

• C08J5/2237

  containing fluorine · CPC title

• B01J39/20

  obtained by reactions only involving unsaturated carbon-to-carbon bonds · CPC title

• C25B13/08

  based on organic materials · CPC title