Diaphragm for alkaline water electrolysis, alkaline water electrolysis device, method for producing hydrogen, and method for producing diaphragm for alkaline water electrolysis

Patent metadata

Field	Value
Publication number	US-2018073155-A1
Application number	US-201615558861-A
Country	US
Kind code	A1
Filing date	Mar 18, 2016
Priority date	Mar 18, 2015
Publication date	Mar 15, 2018
Grant date	—

Abstract

The diaphragm for alkaline water electrolysis according to the present invention comprises a porous polymer membrane, the porous polymer membrane comprising a polymer resin and hydrophilic inorganic particles. A porosity of the porous polymer membrane is 30% or more and 60% or less, average pore sizes at both surfaces of the porous polymer membrane is 0.5 μm or more and 2.0 μm or less, and a ratio of a mode particle size of the hydrophilic inorganic particles to the average pore size of the porous polymer membrane (mode particle size/average pore size) is 2.0 or more.

First claim

1 . A diaphragm for alkaline water electrolysis, comprising a porous polymer membrane, the porous polymer membrane comprising a polymer resin and hydrophilic inorganic particles, wherein
a porosity of the porous polymer membrane is 30% or more and 60% or less, average pore sizes at both surfaces of the porous polymer membrane are 0.5 μm or more and 2.0 μm or less, and a ratio of a mode particle size of the hydrophilic inorganic particles to the average pore size of the porous polymer membrane (mode particle size/average pore size) is 2.0 or more.

2 . A diaphragm for alkaline water electrolysis, comprising a porous polymer membrane, the porous polymer membrane comprising a polymer resin and hydrophilic inorganic particles, wherein
a porosity of the porous polymer membrane is 30% or more and 60% or less, and bubble points of the porous polymer membrane before and after a cavitation test employing ultrasonic cleaning at a frequency of 40 kHz and a sound pressure of 190 db for 60 minutes as measured at 90° C. are 100 kPa or more.

3 . The diaphragm for alkaline water electrolysis according to claim 2 , wherein
average pore sizes at both surfaces of the porous polymer membrane are 0.5 μm or more and 2.0 μm or less, and a ratio of a mode particle size of the hydrophilic inorganic particles to the average pore size of the porous polymer membrane (mode particle size/average pore size) is 2.0 or more.

4 . The diaphragm for alkaline water electrolysis according to claim 2 or 3 , wherein abundances of the hydrophilic inorganic particles as calculated by particle analysis are 10% or more at both surfaces of the porous polymer membrane before and after the cavitation test.

5 . The diaphragm for alkaline water electrolysis according to claim 2 or 3 , wherein abundances of the hydrophilic inorganic particles as calculated by particle analysis are 10% or more at a cross-section of the porous polymer membrane before and after the cavitation test.

6 . The diaphragm for alkaline water electrolysis according to claim 4 , wherein a ratio of decrease, caused by the cavitation test, in the abundances of the hydrophilic inorganic particles at both surfaces or a cross-section of the porous polymer membrane is less than 0.20.

7 . The diaphragm for alkaline water electrolysis according to claim 1 or 2 , wherein the polymer resin comprises at least one selected from the group consisting of polysulfone, polyethersulfone, and polyphenylsulfone.

8 . The diaphragm for alkaline water electrolysis according to claim 1 or 2 , wherein a thickness of the porous polymer membrane is 300 μm or more and 600 μm or less.

9 . The diaphragm for alkaline water electrolysis according to claim 1 or 2 , wherein the hydrophilic inorganic particles comprise zirconium oxide.

10 . The diaphragm for alkaline water electrolysis according to claim 1 or 2 , further comprising a porous support.

11 . The diaphragm for alkaline water electrolysis according to claim 10 , wherein the porous support is any one selected from the group consisting of a mesh, a non-woven fabric, a woven fabric, and a composite fabric comprising a non-woven fabric and a woven fabric enclosed in the non-woven fabric.

12 . The diaphragm for alkaline water electrolysis according to claim 11 , wherein the porous support comprises polyphenylene sulfide.

13 . An alkaline water electrolysis device comprising:
an anode; a cathode; and the diaphragm for alkaline water electrolysis according to claim 1 or 2 , the diaphragm being placed between the anode and the cathode.

14 . A method for producing hydrogen, comprising the step of electrolyzing alkaline water by applying a voltage to the alkaline water electrolysis device according to claim 13 using a variable power supply.

15 . A method for producing the diaphragm for alkaline water electrolysis according to claim 1 or 2 , comprising the steps of:
(A) preparing a solution containing the polymer resin, a solvent capable of dissolving the polymer resin, and the hydrophilic inorganic particles;
(B) applying the solution to a substrate to form a coating on the substrate;
(C) exposing a surface of the coating, said surface being located opposite from the substrate, to a gas containing vapor of a poor solvent for the polymer resin; and
(D) immersing the coating on the substrate in a coagulation bath containing a poor solvent for the polymer resin to form a porous polymer membrane.

16 . The method for producing the diaphragm for alkaline water electrolysis according to claim 15 , wherein the poor solvent in the coagulation bath further comprises the solvent.

17 . The method for producing the diaphragm for alkaline water electrolysis according to claim 16 , wherein a concentration of the solvent in the coagulation bath is from 30 to 70 mass %.

18 . The method for producing the diaphragm for alkaline water electrolysis according to claim 17 , wherein the solvent comprises N-methyl-2-pyrrolidone.

19 . A method for producing the diaphragm for alkaline water electrolysis according to claim 1 or 2 , comprising the steps of:
(E) mixing the polymer resin, a solvent capable of dissolving the polymer resin, and the hydrophilic inorganic particles to obtain a homogeneous dispersion, at a temperature higher than a phase separation temperature of the dispersion to be obtained;
(F) extruding the dispersion at a temperature higher than the phase separation temperature of the dispersion to obtain an extrudate;
(G) cooling the extrudate obtained in the step (F) to a temperature equal to or lower than the phase separation temperature of the dispersion to coagulate the extrudate; and
(H) extracting the solvent from the extrudate obtained in the step (G) to obtain a porous polymer membrane.

20 . The method for producing the diaphragm for alkaline water electrolysis according to claim 19 , further comprising a stretching step.

21 . A method for producing the diaphragm for alkaline water electrolysis according to claim 1 or 2 , comprising the steps of:
(I) paste-extruding a mixture containing a polymer resin and hydrophilic inorganic particles;
(J) rolling the extruded paste to obtain a sheet-shaped porous membrane; and
(K) stretching the obtained sheet-shaped porous membrane in a longitudinal direction and/or a transverse direction.

Assignees

• Asahi Chemical Ind

Inventors

• Suzuki Yusuke
• Nakagawa Kenji
• Takami Hidefumi
• Fujimoto Norikazu

Classifications

• B29K2105/16

  Fillers · CPC title

• B29C48/911

  Cooling · CPC title

• C25B13/08 Primary

  based on organic materials · CPC title

• B29C48/0011

  combined with compression moulding · CPC title

• B29B7/90

  Fillers or reinforcements {, e.g. fibres} · CPC title