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

Patent metadata

Field	Value
Publication number	US-11020734-B2
Application number	US-201715491371-A
Country	US
Kind code	B2
Filing date	Apr 19, 2017
Priority date	Nov 10, 2014
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

To provide an ion exchange membrane for alkali chloride electrolysis which has high membrane strength and low membrane resistance, thereby capable of reducing the electrolysis voltage during alkali chloride electrolysis. In this ion exchange membrane (1) for alkali chloride electrolysis, a reinforcing material 20 formed by weaving reinforcing yarns 22 and sacrificial yarns 24 is disposed in a layer (S) 14, and layer (S) 14 has elution portions 28 formed by elution of at least portions of the sacrificial yarns 24. In a cross section perpendicular to reinforcing yarns of the warp, the average distance (d1) from the center of a reinforcing yarn 22 to the center of the adjacent reinforcing yarn 22, the total area (P) obtained by adding the cross-sectional area of an elution portion 28 and the cross-sectional area of a sacrificial yarn 24 remaining in the elution portion 28, the number (n) of elution portions between adjacent reinforcing yarns 22, and the ion exchange capacity of a layer (Sa) located on the most anode side in the layer (S) 14 during alkali chloride electrolysis, are controlled to be within specific ranges, respectively.

First claim

What is claimed is:

1. An ion exchange membrane for alkali chloride electrolysis comprising:
a layer (S) comprising a fluorinated polymer of a monomer of formula (4):
CF 2 ═CF—O—R f2 -A 2   (4),

wherein
R f2 is a perfluoroalkylene group having from 1 to 20 carbon atoms, which may contain an etheric oxygen atom and may be straight-chained or branched,
A 2 is a group convertible to a sulfonic acid functional group; and

a reinforcing material disposed in the layer (S) substantially in parallel to the layer (S), wherein:
the layer (S) is a laminate comprising a single layer (Sa), at least one layer (Sb), and the reinforcing material, wherein the reinforcing material is disposed between the layer (Sa) and the layer (Sb) or the reinforcing material is disposed in the layer (Sb);
the reinforcing material is a woven fabric comprising reinforcing yarns for the weft and warp and sacrificial yarns for the weft and warp;
in a cross section of the layer (S) perpendicular to the length direction of the reinforcing yarns, the average distance (d1) from the center of a reinforcing yarn to the center of the adjacent reinforcing yarn is from 750 to 1,000 μm;
in the layer (S), elution portions formed by elution of the sacrificial yarns are present;
the total area (P) of the cross-sectional area of an elution portion and the cross-sectional area of a sacrificial yarn remaining in the elution portion is from 500 to 5,000 μm 2 ; the average number of elution portions between adjacent reinforcing yarns is from 4 to 6; and
the ion exchange capacity of the layer (Sa) is from 1.15 meq/g to 2.0 meq/g dry resin.

2. The ion exchange membrane for alkali chloride electrolysis according to claim 1 , wherein the ion exchange capacity of the layer (Sb) is lower than the ion exchange capacity of the layer (Sa).

3. The ion exchange membrane for alkali chloride electrolysis according to claim 1 , wherein layer (S) further comprises at least one layer (C) comprising a fluorinated polymer having carboxylic acid functional groups, wherein layer (C) is disposed on the surface of layer (S) which is opposite of layer (Sa).

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

wherein:
d1 is the average distance from the center of a reinforcing yarn to the center of the adjacent reinforcing yarn;
d2 is the average distance from the center of an elution portion to the center of the adjacent elution portion; and
n is the average number of elution portions that exist between adjacent reinforcing yarns.

5. The ion exchange membrane for alkali chloride electrolysis according to claim 4 , wherein formula (1′) is satisfied 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′)

wherein:
d2′ is the distance from the center of an elution portion to the center of the adjacent elution portion at an optional measurement point; and
d1 and n are each as defined in the formula (1).

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

wherein
d1 is the average distance from the center of a reinforcing yarn to the center of the adjacent reinforcing yarn;
d3 is the average distance from the center of a reinforcing yarn to the center of the adjacent elution portion; and
n is the average number of elution portions that exist between adjacent reinforcing yarns.

7. The ion exchange membrane for alkali chloride electrolysis according to claim 6 , wherein formula (2′) is satisfied 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:
0.5≤{ d 3′/ d 1×( n+ 1)}≤1.5  (2′)

wherein:
d3′ is the distance from the center of a reinforcing yarn to the center of the adjacent elution portion at an optional measurement point; and
d1 and n are each as defined in formula (2).

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

9. An alkali chloride electrolysis apparatus comprising an electrolytic cell which comprises:
a cathode; an anode; and
the ion exchange membrane for alkali chloride electrolysis as defined in claim 1 , wherein the ion exchange membrane for alkali chloride electrolysis is installed between the anode and the cathode in the electrolytic cell substantially in parallel to the anode and the cathode, so as to partition inside of the electrolytic cell into a cathode chamber on the cathode side and an anode chamber on the anode side.

10. The ion exchange membrane for alkali chloride electrolysis according to claim 1 , wherein A 2 is selected from the group consisting of —SO 2 F, —SO 2 Cl, and —SO 2 Br.

11. The ion exchange membrane for alkali chloride electrolysis according to claim 1 , wherein the monomer of formula (4) is selected from the group consisting of:
CF 2 ═CF—O—(CF 2 ) a —SO 2 F, wherein a is an integer of from 1 to 8;
CF 2 ═CF—O—CF 2 CF(CF 3 )O(CF 2 ) a —SO 2 F, wherein a is an integer of from 1 to 8; and
CF 2 ═CF[OCF 2 CF(CF 3 )] a SO 2 F, wherein a is an integer of from 1 to 5.

Assignees

• Agc Inc

Inventors

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

Classifications

• C25B1/46 Primary

  in diaphragm cells · CPC title

• C08F216/1416

  Monomers containing oxygen in addition to the ether oxygen, e.g. allyl glycidyl ether · CPC title

• B01J39/05 Primary

  in the strongly acidic form · CPC title

• C08F216/1475

  Monomers containing sulfur and oxygen · CPC title

• C08J2327/18

  Homopolymers or copolymers of tetrafluoroethylene · CPC title