Ion exchange membrane and method for producing dry ion exchange membrane

Patent metadata

Field	Value
Publication number	US-11958950-B2
Application number	US-202017063058-A
Country	US
Kind code	B2
Filing date	Oct 5, 2020
Priority date	Jun 15, 2018
Publication date	Apr 16, 2024
Grant date	Apr 16, 2024

Abstract

An ion exchange membrane containing a fluorinated polymer, wherein in a case where by Raman spectroscopy, polarized light orthogonal to the thickness direction of the ion exchange membrane is irradiated to obtain a spectrum chart, whereby the ratio of the peak area a2 of Raman shift 680 to 760 cm −1 to the peak area al of Raman shift 1,025 to 1,095 cm −1 is taken as A1, and by Raman spectroscopy, to a cross section in the thickness direction of the ion exchange membrane, polarized light parallel with the thickness direction is irradiated to obtain a spectrum chart, whereby the ratio of the peak area b2 of Raman shift 920 to 1,025 cm −1 to the peak area b1 of Raman shift 1,025 to 1,095 cm −1 is taken as B1, B1/A1 is at least 1.05.

First claim

What is claimed is:

1. An ion exchange membrane containing a fluorinated polymer having a group represented by —SO 3 M (M is a hydrogen atom, an alkali metal or a quaternary ammonium cation) and, in the main chain, a group represented by —CF 2 —, wherein
in a case where by Raman spectroscopy, to a cross section in the thickness direction of the ion exchange membrane, polarized light orthogonal to the thickness direction is irradiated to obtain a spectrum chart, whereby the ratio of the peak area a2 of Raman shift 680 to 760 cm −1 to the peak area a1 of Raman shift 1,025 to 1,095 cm −1 is taken as A1, and
by Raman spectroscopy, to a cross section in the thickness direction of the ion exchange membrane, polarized light parallel to the thickness direction is irradiated to obtain a spectrum chart, whereby the ratio of the peak area b2 of Raman shift 680 to 760 cm −1 to the peak area b1 of Raman shift 1,025 to 1,095 cm −1 is taken as B1,
the ratio of said B1 to said A1 is at least 1.05,
wherein the ion exchange capacity of the fluorinated polymer is 1.25 to 2.05 meq/g dry resin, and
wherein the fluorinated polymer further has an ether bond site in a side chain, and
in a case where by Raman spectroscopy, to a cross section in the thickness direction of the ion exchange membrane, polarized light orthogonal to the thickness direction is irradiated to obtain a spectrum chart, whereby the ratio of the height h2 of the highest peak within a range of Raman shift 920 to 1,025 cm −1 to the height h1 of the highest peak within a range of Raman shift 1,025 to 1.095 cm −1 is taken as H1, and
by Raman spectroscopy, to a cross section in the thickness direction of the ion exchange membrane, polarized light parallel to the thickness direction is irradiated to obtain a spectrum chart, whereby the ratio of the height h4 of the highest peak within a range of Raman shift 920 to 1,025 cm −1 to the height h3 of the highest peak within a range of Raman shift 1,025 to 1,095 cm −1 is taken as H2,
the ratio of said H2 to said H1 is at least 1.15.

2. The ion exchange membrane according to claim 1 , wherein the fluorinated polymer has a unit represented by the formula (1):
—[CF 2 —CF(-L-(SO 3 M) n )]-  Formula (1)

in the formula (1), L is an n+1-valent perfluorohydrocarbon group which may contain an oxygen atom, M is a hydrogen atom, an alkali metal or a quaternary ammonium cation, and n is 1 or 2.

3. The ion exchange membrane according to claim 2 , wherein the ether bond site of the side chain is a site contained in a unit obtained by polymerizing at least one type of monomer selected from the group consisting of the following monomers (A) to (E):

4. The ion exchange membrane according to claim 1 , wherein the ion exchange membrane contains a liquid medium, and the content of the liquid medium in the ion exchange membrane is at most 15 mass % to the total mass of the ion exchange membrane.

5. The ion exchange membrane according to claim 4 , wherein the liquid medium is at least one of water and a water-soluble organic solvent.

6. A method for producing a dry ion exchange membrane, comprising drying a wet ion exchange membrane having an ion exchange membrane containing a fluorinated polymer having a sulfonic acid type functional group wet with a liquid medium, to remove the liquid medium to obtain a dry ion exchange membrane, characterized in that the dimensional change of the dry ion exchange membrane from the wet ion exchange membrane during drying is at least −5% in each of the MD direction and the TD direction,
wherein the drying temperature is at least the softening point of the fluorinated polymer.

7. The method for producing a dry ion exchange membrane according to claim 6 , wherein the content of the liquid medium in the dry ion exchange membrane is at most 15 mass % to the total mass of the dry ion exchange membrane.

8. The method for producing a dry ion exchange membrane according to claim 6 , wherein the dimensional change of the dry ion exchange membrane from the wet ion exchange membrane during drying is at most 50% in each of the MD direction and the TD direction.

9. The method for producing a dry ion exchange membrane according to claim 6 , wherein the content of the liquid medium in the wet ion exchange membrane is at least 20 mass % to the total mass of the wet ion exchange membrane.

10. The method for producing a dry ion exchange membrane according to claim 6 , wherein the wet ion exchange membrane is obtained by contacting the ion exchange membrane containing the fluorinated polymer with the liquid medium at a temperature of at least 60° C.

11. The method for producing a dry ion exchange membrane according to claim 6 , wherein a reinforcing material is contained inside or at the surface of the wet ion exchange membrane.

Assignees

• Agc Inc

Inventors

• HAYABE Shintaro
• Homma Osamu
• Yamaki Yasushi
• Miyajima Tatsuya
• Nishio Takuo

Classifications

• C08J5/2225 Primary

  containing fluorine · CPC title

• H01M8/1039

  halogenated, e.g. sulfonated polyvinylidene fluorides · CPC title

• C08J2327/12

  containing fluorine atoms · CPC title

• C08J5/2237 Primary

  containing fluorine · CPC title

• C25B13/08

  based on organic materials · CPC title