Ion exchange membrane, electrolytic cell, and hydrogen production method

Abstract

The invention comprises a sulfonic acid type membrane body containing a polymer having a sulfonic acid group, and a reinforcing material disposed within the sulfonic acid type membrane body, The surface roughness R1 of the first surface in the sulfonic acid type film body is 10 μm or more. An ion exchange membrane in which the surface roughness R2 of the second surface of the sulfonic acid type membrane body is 10 μm or more.

Description

[Technical Field]

[0001] This invention relates to an ion exchange membrane, an electrolytic cell, and a method for producing hydrogen. [Background technology]

[0002] In recent years, technologies such as wind power generation and solar power generation, which utilize renewable energy sources such as wind and solar power, have attracted attention as a way to solve problems such as global warming caused by greenhouse gases like carbon dioxide and the depletion of fossil fuel reserves.

[0003] Renewable energy sources have the characteristic of being highly variable in output because their output depends on climatic conditions. Therefore, it is not always possible to transport electricity generated from renewable energy sources (hereinafter also referred to as "variable power sources") to the general power grid, raising concerns about social impacts such as imbalances in electricity supply and demand and instability of the power grid. Furthermore, it is well known that imbalances between electricity generated from renewable energy and electricity demand occur not only within a single day but also seasonally.

[0004] Therefore, research is being conducted to convert electricity generated from renewable energy sources into a form that can be stored and transported, and then utilize it. As one example, it is being considered to generate hydrogen that can be stored and transported by electrolysis (hereinafter also called "electrolysis") using electricity generated from renewable energy sources, specifically by electrolysis of water (hereinafter also called "water electrolysis"), and to utilize the generated hydrogen as an energy source or raw material.

[0005] Hydrogen is widely used industrially in petroleum refining, chemical synthesis, metal refining, and other processes. In recent years, its potential applications have expanded to include hydrogen refueling stations for fuel cell vehicles (FCVs), smart communities, and hydrogen power plants. Therefore, there are high expectations for the development of technologies to obtain particularly high-purity hydrogen from renewable energy sources.

[0006] Methods for water electrolysis include polymer electrolyte water electrolysis, high-temperature steam electrolysis, and alkaline water electrolysis. Among these, alkaline water electrolysis is considered a particularly promising method due to its long history of industrialization, its ability to be implemented on a large scale, and its lower cost compared to other water electrolysis devices.

[0007] In such alkaline water electrolysis, water is electrolyzed by supplying current to the anode and cathode, respectively, in the presence of an alkaline electrolyte. During this process, hydrogen is generated from the cathode and oxygen from the anode. Alkaline water electrolysis equipment is equipped with a diaphragm between the cathode and anode to prevent mixing of hydrogen and oxygen. As a specific example of a diaphragm used in alkaline water electrolysis, Patent Document 1 describes an alkaline water electrolysis diaphragm containing a polymer having sulfonic acid-type functional groups. Specifically, it describes an ion exchange membrane containing a polymer having sulfonic acid-type functional groups but not a polymer having carboxylic acid-type functional groups, and a hydrophilic layer provided as the outermost layer of at least one side of the diaphragm. It states that by thinning the ion exchange membrane to 25-70 μm and adjusting the ion exchange capacity, the electrolysis voltage can be kept low even at high current densities, and delamination is less likely to occur.

[0008] Furthermore, in order to reduce the electrolysis voltage in alkaline water electrolysis and improve the power consumption per unit of hydrogen production, the introduction of a structure called a zero-gap structure, which substantially eliminates the gap between the diaphragm and the electrode, is being promoted (see, for example, Patent Documents 2 and 3). In the zero-gap structure, the generated gas is quickly released through the pores of the electrode to the side opposite the diaphragm of the electrode, thereby reducing the distance between the electrodes and minimizing the occurrence of gas accumulation near the electrodes, thereby reducing the electrolysis voltage. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 6981421 [Patent Document 2] U.S. Patent No. 4530743 [Patent Document 3] Japanese Patent Application Publication No. 59-173281 [Overview of the project] [Problems that the invention aims to solve]

[0010] When current flows through the electrodes, a pressure difference (differential pressure) can occur between the anode chamber and the cathode chamber. This differential pressure causes the diaphragm to press against one of the electrodes. In particular, when the supply of electricity from renewable energy sources fluctuates significantly, the power supplied to the water electrolysis device also fluctuates. In such power-fluctuation operation, the diaphragm may be damaged by the fluctuations in the differential pressure, potentially leading to a mixture of oxygen and hydrogen gases. Thus, the diaphragm is required to have resistance to differential pressure fluctuations (resistance to differential pressure fluctuations).

[0011] While it is possible to consider increasing the thickness of the diaphragm to ensure resistance to differential pressure fluctuations, thicker diaphragms tend to exacerbate voltage losses under a zero-gap structure, thus impairing electrolysis efficiency.

[0012] As mentioned above, in conventional technology, there is a trade-off relationship between differential pressure fluctuation resistance and electrolytic efficiency, and a diaphragm that possesses both high differential pressure fluctuation resistance and high electrolytic efficiency has not yet been obtained.

[0013] In view of the above, the present invention aims to provide an ion exchange membrane, etc., that can keep the electrolysis voltage low, has excellent stability in electrolysis operation, and in particular has excellent resistance to differential pressure fluctuations. [Means for solving the problem]

[0014] The inventors of this invention conducted extensive research to solve the above problems and, as a result, discovered that the above problems can be solved by an ion exchange membrane having a predetermined configuration, thus completing the present invention.

[0015] In other words, the present invention encompasses the following embodiments. [1] A sulfonic acid type membrane body containing a polymer having a sulfonic acid group, and a reinforcing material disposed in the sulfonic acid type membrane body. The surface roughness R1 of the first surface of the sulfonic acid type membrane body is 10 μm or more. An ion exchange membrane in which the surface roughness R2 of the second surface of the sulfonic acid type membrane body is 10 μm or more. [2] The reinforcing material includes reinforcing yarns. The ion exchange membrane according to [1], wherein the content of the reinforcing yarns in the reinforcing material is 90% or more. [3] The ion exchange membrane according to [1] or [2], wherein the surface roughness R1 is smaller than the surface roughness R2. [4] The ion exchange membrane has protrusions on the first surface, where the height H is 20 μm or more and 95 μm or less. The arrangement density of the protrusions on the first surface is 50 pieces / cm , , , , 2 , , , <​​​​​​​​​​​​​​​​​​​​​​​​​​An ion exchange membrane according to any one of [1] to [8], wherein the distance L1 between adjacent reinforcing members is 1 / 150 inch or more and 1 / 10 inch or less.

[10] An ion exchange membrane according to any one of [1] to [9], wherein the ion exchange capacity of the polymer is 0.90 milliequivalents / g or more and 2.00 milliequivalents / g or less.

[11] The ion exchange membrane according to any one of [1] to

[10] , wherein the polymer is a fluorine-containing polymer.

[12] The ion exchange membrane according to any one of [1] to

[11] , wherein the polymer comprises a polymer P1 having a unit represented by the following formula (1). -[CF2-CF(-O-CF2CF(CF3)-O-(CF2) m -SO3M)]- (1) (In equation (1), m is an integer between 1 and 6, and M is an alkali metal.)

[13] The ion exchange membrane according to any one of [5] to

[12] , wherein the reinforcing yarn comprises at least one selected from the group consisting of PTFE and PFA.

[14] The ion exchange membrane according to any one of [5] to

[13] , wherein the denier count of the reinforcing yarn is 20 to 150 denier.

[15] The ion exchange membrane according to any one of [1] to

[14] , further comprising a hydrophilic layer disposed on the first surface and / or the second surface.

[16] The ion exchange membrane according to

[15] , wherein the hydrophilic layer comprises inorganic particles.

[17] The ion exchange membrane according to

[15] or

[16] , wherein the inorganic particles include at least one selected from the group consisting of oxides, nitrides, and carbides of Group 4 or Group 14 elements.

[18] The ion exchange membrane according to

[16] or

[17] , wherein the inorganic particles include at least one selected from the group consisting of SiO2, SiC, ZrO2, and ZrC.

[19] An ion exchange membrane used for water electrolysis, as described in any of [1] to

[18] .

[20] An ion exchange membrane used in alkaline water electrolysis, as described in any of [1] to

[18] . [twenty one] Anode and, A cathode facing the anode, An ion exchange membrane according to any one of [1] to

[20] is disposed between the anode and the cathode, An electrolytic cell equipped with the following features. [twenty two] The electrolytic cell according to

[21] , wherein the first surface of the ion exchange membrane is located on the electrode surface side of the anode and the cathode that has higher rigidity. [twenty three] An electrolytic cell as described in

[21] or

[22] , used for alkaline water electrolysis. [twenty four] An electrolytic cell according to any one of

[21] to

[23] , having a zero-gap structure. [twenty five] A method for producing hydrogen using an electrolytic cell described in any of

[21] to

[24] , A method for producing hydrogen, comprising the step of supplying an electrolyte to the electrolytic cell and performing water electrolysis.

[26] The method for producing hydrogen according to

[25] , wherein the first surface of the ion exchange membrane is located on the electrode surface side of the anode and the cathode that has higher rigidity.

[27] The method for producing hydrogen according to

[25] or

[26] , wherein the water electrolysis is alkaline water electrolysis. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an ion exchange membrane, etc., that can keep the electrolysis voltage low, has excellent stability in electrolysis operation, and in particular has excellent resistance to differential pressure fluctuations. [Brief explanation of the drawing]

[0017] [Figure 1]This is a schematic diagram showing an example of the ion exchange membrane of this embodiment viewed from above. [Figure 2] This is a schematic diagram showing the X-X' section of Figure 1. [Figure 3] This diagram, based on the example in Figure 2, illustrates the procedure for measuring the thickness h1 of the ion exchange membrane, the thickness h2 of the ion exchange membrane, and the distance L1 between adjacent reinforcing materials. [Figure 4] This is a conceptual diagram showing an example of an electrolytic cell according to this embodiment. [Figure 5] This is a side view showing an overall example of a bipolar electrolytic cell for alkaline water electrolysis according to this embodiment. [Figure 6] Figure 5 is a partially enlarged cross-sectional view showing the zero-gap structure of a bipolar electrolytic cell for alkaline water electrolysis, indicated by the dashed rectangle (A). [Modes for carrying out the invention]

[0018] The following describes in detail embodiments for carrying out the present invention (hereinafter referred to as "this embodiment"). The present invention is not limited to the following embodiments, and can be implemented in various modifications within the scope of its gist. In the drawings, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to those shown.

[0019] [Ion exchange membrane] The ion exchange membrane of this embodiment comprises a sulfonic acid type membrane body containing a polymer having sulfonic acid groups, and a reinforcing material disposed within the sulfonic acid type membrane body, wherein the surface roughness R1 of the first surface of the sulfonic acid type membrane body is 10 μm or more, and the surface roughness R2 of the second surface of the sulfonic acid type membrane body is 10 μm or more. Because the ion exchange membrane of this embodiment is configured as described above, the electrolysis voltage can be kept low, the stability of the electrolysis operation is excellent, and in particular, the resistance to differential pressure fluctuations is excellent.

[0020] Figure 1 is a schematic diagram showing an example of an ion exchange membrane of this embodiment viewed from above. In this embodiment, when the ion exchange membrane 10 is viewed from above, typically one surface of the sulfonic acid type membrane body 1 or any hydrophilic layer 3 that can be arranged on the sulfonic acid type membrane body 1 is visible. However, in the example of Figure 1, these are omitted for the sake of explanation. That is, in the example of Figure 1, a part of the sulfonic acid type membrane body 1 and the hydrophilic layer 3 are omitted, and the reinforcing material 2 arranged inside the sulfonic acid type membrane body 1 is made visible. In the example of Figure 1, only reinforcing yarn is arranged as the reinforcing material 2, but this is not limited to this, and both reinforcing yarn and sacrificial yarn, which will be described later, may be arranged. Also, in the example of Figure 1, reinforcing yarn is arranged at predetermined intervals as warp and weft threads, but this is not limited to this configuration, and for example, both reinforcing yarn and sacrificial yarn may be arranged at predetermined intervals as warp and weft threads.

[0021] Figure 2 is a schematic diagram showing the X-X' cross-section of Figure 1. In the example in Figure 2, in the sulfonic acid type film body 1 having a first surface 1a and a second surface 1b, the surface roughness R1 of the first surface 1a is smaller than the surface roughness R2 of the second surface 1b. Surface roughness R1 and surface roughness R2 are each 10 μm or more. In this embodiment, surfaces with a surface roughness of 10 μm or more are referred to as "rough surfaces," and surfaces with a surface roughness of less than 10 μm are referred to as "flat surfaces." That is, in this embodiment, both the first surface 1a and the second surface 1b are rough surfaces. In this embodiment, the surface roughness R1 and surface roughness R2 may be configured to be equal (not shown), or the surface roughness R1 may be configured to be smaller than the surface roughness R2 (see Figure 2). Also, if there is a magnitude relationship between the surface roughness measured for the two surfaces of the sulfonic acid type film body in this embodiment, the one with the smaller surface roughness is designated as the first surface. If the surface roughness measured for the two surfaces of the sulfonic acid type film body in this embodiment is equal, the first surface and the second surface can be identified based on the method described in the examples below.

[0022] As shown in Figure 2, a hydrophilic layer 3 is provided on the first surface 1a and the second surface 1b, respectively. In the example in Figure 2, the ion exchange membrane 10 is provided with a hydrophilic layer 3, but the ion exchange membrane 10 does not necessarily have to be provided with a hydrophilic layer 3. In the example in Figure 2, the surface 3a of the hydrophilic layer 3 is rough to correspond to the surface properties of the first surface 1a, and the surface 3b of the hydrophilic layer 3 is also rough to correspond to the surface properties of the second surface 1b. Thus, since the surface properties of the hydrophilic layer 3 tend to correspond to the surface properties of the sulfonic acid type membrane body 1, both surfaces of the ion exchange membrane 10 tend to be rough, regardless of the presence or absence of the hydrophilic layer 3.

[0023] As shown in Figure 2, a plurality of protruding portions δ1 are formed on the first surface 1a, and consequently, a plurality of protruding portions δ2 are also formed on the surface 3a of the hydrophilic layer 3. In the example in Figure 2, the ion exchange membrane 10 is provided with the hydrophilic layer 3, but the ion exchange membrane 10 does not necessarily have to be provided with the hydrophilic layer 3. If the ion exchange membrane 10 does not have the hydrophilic layer 3, the protruding portions δ1 are treated as protruding portions in this embodiment.

[0024] Assuming electrolytic operation, the rough surface of the ion exchange membrane in this embodiment contributes to securing a gap between the ion exchange membrane and the electrode. By securing such a gap, the gas (oxygen or hydrogen) generated by electrolysis is more easily dispersed from the vicinity of the electrode towards the offshore side, which in turn tends to further reduce the electrolysis voltage. Thus, since the ion exchange membrane in this embodiment is configured so that both sides are rough, it is possible to improve electrolysis performance while suppressing membrane damage, at least compared to a membrane with flat surfaces on both sides. In recent years, electrolysis has been carried out using electricity obtained from renewable energy sources in a considerable number of cases. When using such fluctuating power sources, it can be said that it differs from electrolysis using conventional power sources in the following respects. That is, as the amount of electricity fluctuates, the amount of hydrogen generated also changes over time, and as a result the differential pressure between the cathode chamber and the anode chamber fluctuates frequently. When the differential pressure fluctuates, the ion exchange membrane is pressed against the electrodes, so electrolysis using a fluctuating power source is prone to causing physical damage to the ion exchange membrane. As described above, the ion exchange membrane of this embodiment can not only reduce the electrolysis voltage but also contribute to suppressing membrane damage, and its performance is easily realized when applied to electrolysis using a fluctuating power supply. Thus, the ion exchange membrane of this embodiment can suppress membrane damage even when used in electrolysis using a fluctuating power supply, and can be said to have excellent resistance to differential pressure fluctuations. Therefore, the ion exchange membrane of this embodiment can be preferably used in water electrolysis, more preferably in alkaline water electrolysis, and particularly preferably in alkaline water electrolysis using a fluctuating power supply.

[0025] In this embodiment, from the viewpoint of resistance to differential pressure fluctuations, the surface roughness R1 is 10 μm or more, preferably 10 μm to 30 μm, and more preferably 10 μm to 20 μm. Furthermore, in this embodiment, from the viewpoint of resistance to differential pressure fluctuations, the surface roughness R2 is 10 μm or more, preferably 15 μm to 45 μm, and more preferably 20 μm to 40 μm. From the same viewpoint as above, the difference between surface roughness R2 and surface roughness R1 is preferably 0.5 μm or more, more preferably 1.0 μm or more, even more preferably 5 μm or more, and even more preferably 10 μm or more. Surface roughness R1 and surface roughness R2 can be measured based on the method described in the examples below. The surface roughness R1 and R2 can be adjusted to the above-mentioned ranges, for example, as follows. In the manufacturing process of the ion exchange membrane described later, after the precursor of polymer S is made into a film, a substrate having air permeability and heat resistance (for example, embossed release paper, etc.) is placed on one side of the film (the first surface 1a side of the sulfonic acid type membrane body 1), and the reinforcing material is heated and vacuum embedded using a heating source and a vacuum source placed on the release paper side, thereby adjusting them to the above-mentioned ranges. More specifically, for example, increasing the heating and vacuum temperature during embedding (embedding temperature) tends to decrease the surface roughness, while decreasing the embedding temperature tends to increase the surface roughness. Also, the surface roughness tends to increase as the number and size of the embossing increases.

[0026] In the cross-section of the ion exchange membrane of this embodiment, the thickness h1 of the ion exchange membrane at position P1 with reinforcing material and the thickness h2 of the ion exchange membrane at position P2 without reinforcing material preferably satisfy 1.3 ≤ h1 / h2 ≤ 10, more preferably 1.3 ≤ h1 / h2 ≤ 5, and even more preferably 1.5 ≤ h1 / h2 ≤ 2.5 from the viewpoint of electrolytic performance and differential pressure fluctuation resistance. In this embodiment, from the viewpoint of differential pressure fluctuation resistance, the lower limit of the thickness h2 is preferably 10 μm or more, more preferably 50 μm or more, and even more preferably 100 μm or more. On the other hand, from the viewpoint of low voltage, the upper limit of h2 is preferably 169 μm or less, more preferably 150 μm or less, and even more preferably 130 μm or less. In this embodiment, from the viewpoint of differential pressure fluctuation resistance, the lower limit of the thickness h1 is preferably 100 μm or more, more preferably 150 μm or more, and even more preferably 200 μm or more. Furthermore, from the viewpoint of low voltage, the upper limit of h1 is preferably 300 μm or less, more preferably 280 μm or less, and even more preferably 250 μm or less. These values ​​can be measured as follows. Figure 3 is an explanatory diagram showing the measurement procedure for the thickness h1 and thickness h2 of the ion exchange membrane 10, based on the example in Figure 2. In the example in Figure 3, the reinforcing material 2 is arranged along the planar direction D1 of the ion exchange membrane 10. As shown in Figure 3, the position P1 where the reinforcing material 2 is located is identified based on the width that the reinforcing material 2 occupies in the planar direction D1, and the position P2 where the reinforcing material 2 is not located is identified as the portion excluding position P1. Also, as shown in Figure 3, the thickness h1 is identified as the portion that gives the maximum value of the thickness of the ion exchange membrane (width in the direction perpendicular to the planar direction D1) as measured at position P1. The thickness h2 is identified as the portion that gives the minimum value of the thickness of the ion exchange membrane as measured at position P2. When measuring the maximum and minimum values, if the ion exchange membrane 10 has a hydrophilic layer 3, the measurement should be taken to obtain the total thickness including the hydrophilic layer 3, and if the ion exchange membrane 10 does not have a hydrophilic layer 3, the measurement should be taken to obtain the thickness of the sulfonic acid type membrane body 1 (and possibly the reinforcing material 2 depending on the location). Using this measurement procedure, 100 arbitrary points are measured for thickness h1, and the average value of these measurements is used to determine the value of thickness h1. Similarly, 100 arbitrary points are measured for thickness h2, and the average value of these measurements is used to determine the value of thickness h2. The thicknesses h1 and h2 can be measured more specifically based on the methods described in the examples below. The thicknesses h1 and h2 can be adjusted to the above-mentioned ranges, for example, by adjusting the method and temperature of embedding the reinforcing material in the manufacturing process of the ion exchange membrane.

[0027] In this embodiment, multiple reinforcing materials exist along the planar direction of the ion exchange membrane, and the distance L1 between adjacent reinforcing materials is preferably 1 / 150 inch or more and 1 / 10 inch or less, more preferably 1 / 100 inch or more and 1 / 15 inch or less, and even more preferably 1 / 100 inch or more and 1 / 20 inch or less. The procedure for measuring the distance L1 will also be explained with reference to Figure 3. As shown in Figure 3, adjacent reinforcing materials 2 may be two reinforcing threads, a reinforcing thread and a sacrificial thread, or two sacrificial threads. In the example shown in Figure 3, the distance L1 can be measured as the distance between two adjacent reinforcing threads. In such a measurement, the distance is specified as the distance along the planar direction D1 from the position where the thickness h1 is measured to the adjacent position where the thickness h1 is measured. Using this measurement procedure, the distance L1 is measured at 100 arbitrary points, and the value of the distance L1 is determined as the average value. The distance L1 can be measured more specifically based on the method described in the examples below.

[0028] (Sulfonic acid type membrane body) The sulfonic acid type film body includes a polymer having sulfonic acid groups (hereinafter also referred to as "polymer S"). In this embodiment, the sulfonic acid type film body means one having sulfonic acid groups on the first surface and the second surface. Typically, a film body formed by laminating polymer layers made of polymer S, either a single layer or two or more layers, can be said to have sulfonic acid groups on the first surface and the second surface, and therefore corresponds to a sulfonic acid type film body. In contrast, for example, a composite film with a two-layer structure in which a polymer layer made of a polymer having carboxylic acid groups (hereinafter also referred to as "polymer C") and a polymer layer made of polymer S are laminated together can be said to not have sulfonic acid groups on at least one surface (the surface on the side of the polymer layer made of polymer C), and therefore does not correspond to a sulfonic acid type film body. In this embodiment, from the viewpoint of preventing delamination within the sulfonic acid type film body, it is preferable that the sulfonic acid type film body does not have a polymer layer made of polymer C.

[0029] Various polymers having sulfonic acid groups can be used as polymer S. Preferably, polymer S contains, for example, a fluorine atom, i.e., a fluorine-containing polymer. In this case, polymer S preferably contains at least one of polymer P1 having a unit represented by the following formula (1) and polymer P2 having a unit represented by the following formula (2), and more preferably contains polymer P1. -[CF2-CF(-O-CF2CF(CF3)-O-(CF2) m -SO3M)]- (1) -[CF2-CF(-O-(CF2) m -SO3M)]- (2) (In equations (1) and (2) above, m is an integer between 1 and 6, and M is an alkali metal.)

[0030] In this embodiment, from the viewpoint of ensuring electrolytic performance and preventing delamination within the sulfonic acid type film body, the total thickness of the polymer layers composed of polymer S is preferably 99.9% or more, more preferably 99.99% or more, and even more preferably 100%, when the thickness of the sulfonic acid type film body (excluding reinforcing material placed inside) (thickness in the direction perpendicular to the surface direction of the first surface) is set to 100%. From a similar viewpoint, the total thickness of the polymer layers composed of polymer C is preferably less than 0.1%, more preferably less than 0.01%, and even more preferably below the detection limit, when the thickness of the sulfonic acid type film body is set to 100%.

[0031] It is preferable that the ion exchange capacity of polymer S is 0.90 milliequivalents / g or more and 2.00 milliequivalents / g or less. When the above ion exchange capacity is 0.90 milliequivalents / g or more, the electrolysis voltage tends to decrease further. When the above ion exchange capacity is 2.00 milliequivalents / g or less, the strength of the sulfonic acid type membrane body tends to improve. From the above viewpoint, it is more preferable that the above ion exchange capacity is 0.95 milliequivalents / g or more and 1.50 milliequivalents / g or less, even more preferable that it is 0.97 milliequivalents / g or more and 1.25 milliequivalents / g or less, and even more preferable that it is 1.00 milliequivalents / g or more and 1.15 milliequivalents / g or less. The above ion exchange capacity can be measured based on the method described in the examples below.

[0032] (Reinforcement material) The reinforcing material is placed within the sulfonic acid type membrane body. In this specification, "placed within the sulfonic acid type membrane body" means that at least a portion of the reinforcing material is placed inside the sulfonic acid type membrane body, and also includes the configuration in which a portion of the reinforcing material penetrates from the inside to the outside of the sulfonic acid type membrane body. In this embodiment, the reinforcing material can function as at least one of reinforcing yarn and sacrificial yarn. That is, the reinforcing material may include reinforcing yarn and / or sacrificial yarn. Sacrificial yarn means yarn that has the property of dissolving in acid or alkali. Reinforcing yarn means yarn that can be used as reinforcing material but does not fall under the category of sacrificial yarn. Examples of reinforcing materials include, but are not limited to, woven fabrics made of reinforcing yarn and sacrificial yarn, or woven fabrics made of reinforcing yarn. By placing the reinforcing material within the sulfonic acid type membrane body, the expansion and contraction of the ion exchange membrane can be controlled to a desired range. Such an ion exchange membrane does not expand or contract excessively during electrolysis, etc., and can maintain excellent dimensional stability over a long period of time. In this embodiment, it is preferable that the reinforcing material includes reinforcing yarn. Furthermore, in this embodiment, from the viewpoint of gas barrier properties, the content of reinforcing yarn in the reinforcing material (hereinafter also referred to as "reinforcing yarn ratio") is preferably 90% or more, more preferably 99% or more, even more preferably 99.9% or more, and even more preferably 100%. The content of reinforcing yarn in the reinforcing material (reinforcing yarn ratio) can be measured based on the method described in the examples below.

[0033] The composition of the reinforcing material is not particularly limited; for example, it may be formed by spinning a yarn called a reinforcing yarn. The term "reinforcing yarn" here refers to a component of the reinforcing material that can impart desired dimensional stability and mechanical strength to the ion exchange membrane, and that can exist stably within the ion exchange membrane. By using a reinforcing material made by spinning such reinforcing yarn, even better dimensional stability and mechanical strength can be imparted to the ion exchange membrane.

[0034] The reinforcing yarn can be, but is not limited to, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), vinylidene fluoride polymer (PVDF), polyphenylene sulfide (PPS), nylon, etc. In this embodiment, from the viewpoint of heat resistance and chemical resistance, it is preferable that the reinforcing yarn includes at least one selected from the group consisting of PTFE and PFA.

[0035] The sacrificial yarn can be, but is not limited to, polyethylene terephthalate (PET), polyvinyl alcohol (PVA), rayon, cellulose, and polyamide. In this embodiment, from the viewpoint of stability during weaving and solubility in acids or alkalis, the sacrificial yarn is preferably PET.

[0036] The denier count (thread diameter) of the reinforcing yarn and the sacrificial yarn is not particularly limited, but it is preferably 20 to 150 denier, and more preferably 20 to 100 denier, for each independently. When a woven fabric made of reinforcing yarn and sacrificial yarn is used as a reinforcing material, the warp and weft threads of the reinforcing yarn and the sacrificial yarn may each have the aforementioned denier count. In this case, the weaving density (number of threads per unit length) is preferably 20 to 150 threads / inch. When the reinforcing material is a woven fabric, the thickness is preferably 50 μm to 150 μm. The form of the reinforcing material is not limited to woven fabric, but may also be nonwoven fabric, knitted fabric, etc.

[0037] Woven or knitted fabrics can be made from monofilament, multifilament, or yarns thereof, slit yarn, etc., and the weaving method can be various, such as plain weave, leno weave, knit weave, cord weave, shasakka, etc.

[0038] (hydrophilic layer) The ion exchange membrane may further include a hydrophilic layer disposed on the first and / or second surface of the sulfonic acid type membrane body. When the ion exchange membrane includes a hydrophilic layer, gas adhesion to the surface of the ion exchange membrane during electrolysis tends to be suppressed, and the electrolysis voltage tends to be further reduced.

[0039] The hydrophilic layer preferably contains inorganic particles, and from the viewpoint of hydrophilicity, the inorganic particles preferably contain at least one selected from the group consisting of oxides, nitrides, and carbides of Group 4 or Group 14 elements, and more preferably at least one selected from the group consisting of SiO2, SiC, ZrO2, and ZrC. The hydrophilic layer may contain a binder polymer. Examples of binder polymers include vinyl compounds having functional groups that can be converted into sulfone-type ion exchange groups, and materials similar to polymer S may be used.

[0040] [Method for manufacturing ion exchange membranes] The method for manufacturing the ion exchange membrane of this embodiment is not particularly limited as long as an ion exchange membrane with the above-described configuration can be obtained. A preferred method for manufacturing the ion exchange membrane of this embodiment includes, for example, a method having the following (1) to (4). (1) A step to obtain a precursor of polymer S, (2) A step of embedding the reinforcing material into a film using a precursor of polymer S to obtain a precursor of a sulfonic acid type film body in which the reinforcing material is arranged inside (integration step), (3) A step to obtain a sulfonic acid type membrane body containing polymer S by hydrolyzing the precursor of polymer S in the precursor of the sulfonic acid type membrane body (hydrolysis step), (4) Optionally, a step of forming a hydrophilic layer on at least one of the surfaces of the sulfonic acid type film body (hydrophilic layer formation step).

[0041] The following provides a more detailed explanation of each step.

[0042] The precursor of polymer S is not limited to the following, but can be produced, for example, by copolymerizing monomers from group 1 and group 2, or by homopolymerizing monomers from group 2.

[0043] Examples of monomers in the first group include, but are not limited to, vinyl fluoride compounds. Vinyl fluoride compounds represented by the following formula (3) are preferred. CF2 = CX1 x 2 ... (3) (In equation (3) above, X1 and X2 each independently represent F, Cl, H, or CF3.)

[0044] The vinyl fluoride compound represented by formula (3) above is not limited to the following, but examples include vinyl fluoride, tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, trifluoroethylene, and chlorotrifluoroethylene. In this embodiment, the vinyl fluoride compound is preferably a perfluoro monomer, and more preferably a perfluoro monomer selected from the group consisting of tetrafluoroethylene and hexafluoropropylene. Even more preferably, it is tetrafluoroethylene (TFE).

[0045] The monomers of the second group are not limited to the following, but include vinyl compounds having a functional group that can be converted into a sulfonic acid type ion exchange group. A vinyl compound having a functional group that can be converted into a sulfonic acid type ion exchange group is preferably represented by the following formula (4). CF2 = CFO - (CF2CYFO) a -(CF2) b -SO2F ···(4) (In equation (4) above, a is an integer between 0 and 2, b is an integer between 1 and 6, Y is F or CF3, and R is CH3, C2H5, or C3H7.)

[0046] Specific examples of these include monomers, etc., as shown below; CF2 = CFOCF2CF2SO2F, CF2=CFOCF2CF(CF3)OCF2CF2SO2F, CF2=CFOCF2CF(CF3)OCF2CF2CF2SO2F, CF2 = CF(CF2)2SO2F, CF2=CFO〔CF2CF(CF3)O〕2CF2CF2SO2F, CF2=CFOCF2CF(CF2OCF3)OCF2CF2SO2F. Among the above, CF2=CFOCF2CF(CF3)OCF2CF2CF2SO2F and CF2=CFOCF2CF(CF3)OCF2CF2SO2F are preferred, and CF2=CFOCF2CF(CF3)OCF2CF2SO2F is more preferred.

[0047] The types of monomer combinations constituting the precursor of polymer S, their ratios, and the degree of polymerization are not particularly limited. In other words, the types of monomer combinations constituting polymer S, their ratios, and the degree of polymerization are not particularly limited. Furthermore, the ion exchange membrane may contain polymer S alone or may contain two or more types of polymer S. The ion exchange capacity of polymer S can be adjusted to the aforementioned range by changing, for example, the ratio of monomers represented by formulas (3) and (4) above. More specifically, for example, copolymerization of the monomer represented by formula (3) and the monomer represented by formula (4) in a ratio of 3:1 to 7:1 can be performed.

[0048] (integration process) The precursor of polymer S can be formed into a film using an extruder or the like. The film may be a single layer or may have a structure of two or more layers. If a structure of two or more layers is used, for example, the films of the polymer S precursors constituting each layer may be formed separately and then subjected to the integration process described later.

[0049] The structure of the ion exchange membrane can be controlled by adjusting the shape and arrangement of reinforcing materials such as reinforcing threads and sacrificial threads. In this embodiment, from the viewpoint of gas barrier properties, it is preferable to reduce the amount of sacrificial yarn used. From the above viewpoint, the reinforcing yarn ratio is preferably 90% or more, more preferably 99% or more, and even more preferably 99.9% or more. In this embodiment, from the above viewpoint, it is even more preferable that the reinforcing yarn ratio is 100%, in other words, that only reinforcing yarn is used as the reinforcing material. In this embodiment, when the reinforcing yarn ratio to the reinforcing material is 100%, the ion exchange membrane does not contain sacrificial yarn, and gas barrier properties can be further improved. The reinforcing thread ratio can be adjusted to the range described above by, for example, adjusting the thickness of the reinforcing threads and sacrificial threads, or the amount of sacrificial threads used.

[0050] The method for integrating the polymer S precursor and reinforcing material is not limited to the following, but for example, on a flat plate or drum having a heating source and / or vacuum source inside and numerous pores on its surface, layers of polymer S precursor film, reinforcing material, and polymer S precursor film are stacked in that order via a permeable and heat-resistant substrate (e.g., embossed release paper), and the layers are integrated by removing the air between each layer under reduced pressure at the temperature at which the films melt. Specific examples, not limited to the following, include a method in which release paper, polymer S precursor film, reinforcing material, and polymer S precursor film are stacked on a drum in that order and integrated under reduced pressure (embedding the reinforcing material into the film). Alternatively, for example, when two types of polymer S precursors are each made into films, a method can be used in which release paper, polymer S precursor film, reinforcing material, and polymer S precursor (different type) film are stacked on a drum in that order and integrated under reduced pressure. During the heating and depressurization process described above, adjusting the heating and depressurization temperature (embedding temperature) makes it easier to obtain a sulfonic acid type film body with a rough surface. On the side opposite the release paper, i.e., the side facing the atmosphere, the parts without reinforcing material (parts consisting only of resin) tend to flow due to heating and depressurization relative to the parts with reinforcing material, resulting in the formation of a rough surface. The lower the embedding temperature at this time, the greater the surface roughness tends to be, and the higher the embedding temperature, the smaller the surface roughness tends to be. On the release paper side, a shape derived from the surface shape of the embossed release paper tends to be imparted to the sulfonic acid type membrane body. That is, by adjusting the embossing shape, the surface of the sulfonic acid type membrane body on the release paper side tends to be a rough surface.

[0051] In the present embodiment, from the viewpoints of the supply property of the electrolytic solution to the ion exchange membrane and the differential pressure fluctuation resistance, the ion exchange membrane has protrusions with a height H of 20 μm or more and 95 μm or less on the first surface, and the arrangement density P of the protrusions on the first surface is 50 pieces / cm 2 or more and 1200 pieces / cm 2 or less. From the above viewpoints, the height H is more preferably 30 μm or more and 80 μm or less, and still more preferably 40 μm or more and 70 μm or less. Also, from the above viewpoints, the arrangement density P is more preferably 100 pieces / cm 2 or more and 1000 pieces / cm 2 or less, and still more preferably 400 pieces / cm 2 or more and 700 pieces / cm 2 or less. The first surface referred to here means the first surface 1a of the sulfonic acid type membrane body 1 in the example of FIG. 2 when the ion exchange membrane does not have a hydrophilic layer, and means the surface 3a of the hydrophilic layer 3 in the example of FIG. 2 when the ion exchange membrane has a hydrophilic layer. In the present embodiment, the shape of the protrusions is not particularly limited, but the protrusions preferably have at least one shape selected from the group consisting of a conical shape, a polygonal pyramid shape, a truncated cone shape, a truncated polygonal pyramid shape, and a hemispherical shape. Here, the hemispherical shape includes shapes called dome shapes and the like. More specifically, the height H and the arrangement density P can be measured based on the method described in the examples described later. The height H and the arrangement density P can be adjusted to the above-described ranges, respectively, for example, by adjusting the embossing shape of the embossed release paper.

[0052] (Hydrolysis step) The precursor of polymer S is hydrolyzed, converting the precursor of the ion exchange group into the ion exchange group itself. In this way, a composite membrane of a sulfonic acid-type membrane body containing polymer S and a reinforcing material can be obtained. If sacrificial threads are included as the reinforcing material, the sacrificial threads can be dissolved and removed with an acid or alkali along with the introduction of the ion exchange group, thereby forming interconnected pores inside the sulfonic acid-type membrane body. Note that the sacrificial threads may not be completely dissolved and may remain in the interconnected pores. Furthermore, any sacrificial threads remaining in the interconnected pores may be dissolved and removed by the electrolyte during electrolysis.

[0053] The above-mentioned acid or alkali can be any substance that dissolves the sacrificial thread, and its type is not particularly limited. Examples of acids include, but are not limited to, hydrochloric acid, nitric acid, sulfuric acid, acetic acid, and fluorine-containing acetic acid. Examples of alkalis include, but are not limited to, potassium hydroxide and sodium hydroxide.

[0054] The conditions for hydrolysis are not particularly limited; for example, it can be carried out in an aqueous solution of 2.5-4.0 N potassium hydroxide (KOH) and 20-40% by mass of DMSO (Dimethyl sulfoxide) at 40-95°C for 10 minutes to 24 hours.

[0055] (Hydrophilic layer formation process) A hydrophilic layer may be formed on at least one surface of the sulfonic acid type membrane body. The material of the hydrophilic layer is not particularly limited, and the method of forming the hydrophilic layer on the sulfonic acid type membrane body is not particularly limited, and known methods can be used. For example, a method of applying a solution in which inorganic oxide particles are dispersed in a binder polymer solution by spraying is one example. The application conditions are not particularly limited, and for example, spraying can be used at 30 to 90°C. Other methods besides spraying include, for example, roll coating. The hydrophilic layer formation step is an optional step, and if the hydrophilic layer formation step is not performed, a composite membrane of the sulfonic acid type membrane body and reinforcing material obtained through the hydrolysis step described above can be used as the ion exchange membrane of this embodiment.

[0056] [Electrolytic cell] The ion exchange membrane of this embodiment can be used as a component of an electrolytic cell. That is, the electrolytic cell of this embodiment is equipped with the ion exchange membrane of this embodiment. The electrolytic cell of this embodiment typically comprises an anode, a cathode facing the anode, and the ion exchange membrane of this embodiment disposed between the anode and the cathode. Because the electrolytic cell of this embodiment is equipped with the ion exchange membrane of this embodiment, it can be preferably used as an electrolytic cell for water electrolysis, and more preferably as an electrolytic cell for alkaline water electrolysis. Furthermore, from the viewpoint of making the performance of the ion exchange membrane of this embodiment more apparent, it is preferable that the electrolytic cell of this embodiment has a zero-gap structure.

[0057] Figure 4 is a conceptual diagram showing an example of an electrolytic cell according to this embodiment. In Figure 4, the electrolytic cell 100 includes an anode 21, a cathode 31 facing the anode 21, and an ion exchange membrane 10 disposed between the anode 21 and the cathode 31. The electrolytic cell 100 is separated by the ion exchange membrane 10 into an anode chamber 20 containing the anode 21 and a cathode chamber 30 containing the cathode 31.

[0058] Surface 10a of the ion exchange membrane 10 may be located on either the anode 21 or the cathode 31 side. Similarly, surface 10b of the ion exchange membrane 10 may be located on either the anode 21 or the cathode 31 side. In this embodiment, in particular, if the surface roughness of surface 10a of the ion exchange membrane 10 is smaller than the surface roughness of surface 10b of the ion exchange membrane 10, it is preferable that surface 10a of the ion exchange membrane 10 be located on the electrode surface side of the anode 21 or cathode 31 that has higher rigidity. If the ion exchange membrane 10 has a hydrophilic layer 3, surface 10a of the ion exchange membrane 10 is surface 3a of the hydrophilic layer 3. If the ion exchange membrane 10 does not have a hydrophilic layer 3, surface 10a of the ion exchange membrane 10 is the first surface 1a of the sulfonic acid type membrane body 1. When the surface 10a of the ion exchange membrane 10, i.e., the surface with the lower surface roughness, is positioned on the electrode surface side of the anode 21 and cathode 31 that has higher rigidity, resistance to pressure from the electrodes on the ion exchange membrane is more likely to be exhibited, and membrane damage tends to be further suppressed.

[0059] Figure 4 shows an example where the anode 21 has higher rigidity than the cathode 31. That is, in the electrolytic cell 100, the ion exchange membrane 10 is arranged such that surface 10a of the ion exchange membrane 10 faces surface 21a of the anode 21, and surface 10b of the ion exchange membrane 10 faces surface 31b of the cathode 31. In Figure 4, for explanatory purposes, the anode 21, ion exchange membrane 10, and cathode 31 are shown spaced apart, but it is preferable that these components are arranged so that adjacent components are in contact with each other, i.e., that the electrolytic cell 100 has a zero-gap structure. In alkaline water electrolysis, oxygen is generated from the anode 21 and hydrogen is generated from the cathode 31. The amount of hydrogen generated at the cathode 31 tends to be greater than the amount of oxygen generated at the anode 21. Therefore, when surface 10b of the ion exchange membrane 10 (the side with the greater surface roughness) is in contact with surface 31b of the cathode 31, the effect of reducing the electrolysis voltage by dispersing the gas tends to become more pronounced.

[0060] In this embodiment, the other device configurations of the electrolytic cell are not particularly limited and may be the same as those of various known electrolytic cell configurations. Similarly, the operating conditions of the electrolytic cell are not particularly limited and may be the same as those of various known electrolytic cell operating conditions. For example, they may be the same as those described in Japanese Patent No. 6826243 and Japanese Patent No. 3696137.

[0061] (Bipolar electrolytic cell for alkaline water electrolysis) The electrolytic cell in this embodiment may be a bipolar electrolytic cell for alkaline water electrolysis. Figure 5 shows an overall side view of an example of a bipolar electrolytic cell for alkaline water electrolysis according to this embodiment. Figure 6 is a partially enlarged cross-sectional view showing the zero-gap structure of the bipolar electrolytic cell for alkaline water electrolysis in the dashed rectangle (A) of Figure 5. The bipolar electrolytic cell for alkaline water electrolysis of this embodiment may be a bipolar electrolytic cell 50 for alkaline water electrolysis in which a plurality of bipolar elements 60, each having an anode 42a, a cathode 42c, a partition wall 41 separating the anode 42a and the cathode 42c, and an outer frame 43 bordering the partition wall 41, are stacked on top of each other with a diaphragm 44 in between.

[0062] In the example shown in Figure 6, the bipolar electrolytic cell 50 for alkaline water electrolysis of this embodiment forms a zero-gap structure Z in which the diaphragm 44 is in contact with the anode 42a and the cathode 42c. When the ion exchange membrane 10 of this embodiment (see Figure 2) is used as the diaphragm 44, as described above, the effect of reducing the electrolysis voltage by dispersing the gas tends to become more pronounced when the surface 10b (the side with greater surface roughness) of the ion exchange membrane 10 is in contact with the surface of the cathode 42c.

[0063] In the bipolar electrolytic cell 50 for alkaline water electrolysis in this embodiment, an electrode chamber 45 through which the electrolyte passes is defined by a partition wall 41, an outer frame 43, and a diaphragm 44, and it is preferable that the electrode chamber 45 is provided with a plurality of rectifier plates 46 arranged parallel to a given direction D2 along the partition wall (see Figure 6).

[0064] (Bipolar element) As shown in Figure 6, a bipolar element 60 used in one example of a bipolar electrolytic cell 50 for alkaline water electrolysis includes a partition wall 41 that separates the anode 42a and the cathode 42c, and an outer frame 43 that frames the partition wall. More specifically, the partition wall 41 is conductive, and the outer frame 43 is provided to surround the partition wall 41 along its outer edge.

[0065] In this embodiment, the bipolar element 60 may be used such that a given direction D2 along the partition wall 41 is the vertical direction. Specifically, as shown in Figure 6, if the plan view shape of the partition wall 41 is rectangular, the element may be used such that a given direction D2 along the partition wall 41 is the same direction as one of the two pairs of opposite sides (see Figures 5 to 6). In this specification, the above vertical direction is also referred to as the electrolyte passage direction.

[0066] In this embodiment, as shown in Figure 5, the bipolar electrolytic cell 50 for alkaline water electrolysis is constructed by stacking a desired number of bipolar elements 60. In the example shown in Figure 5, the bipolar electrolytic cell 50 for alkaline water electrolysis has a fast head 51g, an insulating plate 51i, and an anode terminal element 51a arranged in that order from one end. Furthermore, the anode-side gasket 47 (anode-side gasket portion 47), diaphragm 44, cathode-side gasket 47 (cathode-side gasket portion 47), and bipolar element 60 are arranged in this order. At this time, the bipolar element 60 is positioned so that the cathode 42c faces the anode terminal element 51a. The anode-side gasket portion 47 to the bipolar element 60 are repeated as many times as required for the design production volume. After repeatedly arranging the anode-side gasket portion 47 to the bipolar element 60 a desired number of times, the anode-side gasket portion 47, diaphragm 44, and cathode-side gasket portion 47 are arranged again, and finally the cathode terminal element 51c, insulating plate 51i, and loose head 51g are arranged in this order. The bipolar electrolytic cell 50 for alkaline water electrolysis is integrated by fastening the entire assembly with a tie rod 51r (see Figure 5) or a hydraulic cylinder system or the like, thus becoming the bipolar electrolytic cell 50 for alkaline water electrolysis. The arrangement of the bipolar electrolytic cell 50 for alkaline water electrolysis can be arbitrarily selected from either the anode 42a side or the cathode 42c side, and is not limited to the order described above.

[0067] As shown in Figure 5, in the bipolar electrolytic cell 50 for alkaline water electrolysis, the bipolar element 60 is positioned between the anode terminal element 51a and the cathode terminal element 51c, and the diaphragm 44 is positioned between the anode terminal element 51a and the bipolar element 60, between adjacent bipolar elements 60, and between the bipolar element 60 and the cathode terminal element 51c.

[0068] Furthermore, in the bipolar electrolytic cell 50 for alkaline water electrolysis in this embodiment, as shown in Figure 6, the electrode chamber 45 through which the electrolyte passes is defined by a partition wall 41, an outer frame 43, and a diaphragm 44.

[0069] More specifically, the electrode chamber 45 has an electrolyte inlet for introducing electrolyte into the electrode chamber 45 and an electrolyte outlet for discharging electrolyte from the electrode chamber 45 at the boundary with the outer frame 43. More specifically, the anode chamber 45a is provided with an anode electrolyte inlet for introducing electrolyte into the anode chamber 45a and an anode electrolyte outlet for discharging electrolyte discharged from the anode chamber 45a, and the cathode chamber 45c is provided with a cathode electrolyte inlet for introducing electrolyte into the cathode chamber 45c and a cathode electrolyte outlet for discharging electrolyte discharged from the cathode chamber 45c.

[0070] In the example shown in Figures 5 and 6, the rectangular partition wall 41 and the rectangular membrane 44 are arranged in parallel, and the inner surface of the rectangular parallelepiped outer frame 43 provided at the edge of the partition wall 41 is perpendicular to the partition wall 41, so the shape of the electrode chamber 45 is a rectangular parallelepiped.

[0071] A bipolar electrolytic cell 50 for alkaline water electrolysis is typically fitted with headers, which are tubes for distributing or collecting electrolyte. The lower part of the outer frame 43 at the edge of the partition wall 41 is equipped with an anode inlet header for supplying electrolyte to the anode chamber 45a and a cathode inlet header for supplying electrolyte to the cathode chamber 45c. Similarly, the upper part of the outer frame 43 at the edge of the partition wall 41 is equipped with an anode outlet header for discharging electrode solution from the anode chamber 45a and a cathode outlet header for discharging electrolyte from the cathode chamber 45c. In addition, while there are typically two types of header configurations for the bipolar electrolytic cell 50 for alkaline water electrolysis shown in Figures 5 and 6, namely internal header type and external header type, either type may be used in this embodiment, and there are no particular limitations.

[0072] In the bipolar electrolytic cell 50 for alkaline water electrolysis of this embodiment, the electrolyte distributed by the anode inlet header is introduced into the anode chamber 45a through the anode electrolyte inlet, passes through the anode chamber 45a, is discharged from the anode chamber 45a through the anode electrolyte outlet, and is collected by the anode outlet header.

[0073] As shown in Figure 6, the electrode chamber in this embodiment includes a plurality of rectifier plates 46 arranged parallel to a given direction D2 along the partition wall 41.

[0074] The rectifier plate 46 reduces convection generated in the electrode chamber 45 due to turbulence in the gas-liquid flow within the electrode chamber 45, thereby suppressing a localized rise in the electrolyte temperature.

[0075] In particular, in the example shown in Figures 5 and 6, multiple rectifier plates 46 are provided at regular intervals (pitch) in a direction perpendicular to a given direction D2 (in the illustrated example, the direction of electrolyte passage) along the partition wall 41.

[0076] In addition, in one example of a bipolar electrolytic cell 50 for alkaline water electrolysis, the rectifier plate 46 has a length approximately the same as the height of the electrode chamber 45, is installed perpendicular to the partition wall 41, and has through holes at a predetermined pitch along the partition wall 41 in a given direction D2 (in the illustrated example, the direction of electrolyte passage).

[0077] In this embodiment, the shape of the electrode chamber 45 is not limited to the rectangular parallelepiped shape shown in Figures 5 and 6, but may be appropriately modified by the plan view shape of the partition wall 41 and the diaphragm 44, the angle between the inner surface of the outer frame 43 on the partition wall 41 side and the partition wall 41, etc.

[0078] Furthermore, in this embodiment, the arrangement of the rectifier plate 46 in the electrode chamber 45 is not limited to the examples shown in Figures 5 and 6. In this embodiment, the number of rectifier plates 46 and the constant spacing (pitch) of the rectifier plates 46 in a direction perpendicular to a given direction D2 along the partition wall 41 may be determined as appropriate. Here, the spacing of the rectifier plates 46 does not have to be constant. Furthermore, in this embodiment, the length of the rectifier plate 46, the angle between the rectifier plate 46 and the partition wall 41, the number of through holes, and the constant spacing (pitch) of the through holes along the partition wall 41 in a given direction D2 may be determined as appropriate. Here, the spacing of the through holes does not have to be constant.

[0079] In the examples shown in Figures 5 and 6, the partition wall 41, anode 42a, and cathode 42c are all plate-like in shape with a predetermined thickness. However, the invention is not limited to these shapes, and the cross-section may be entirely or partially zigzag or wavy, or the ends may be rounded.

[0080] [Hydrogen production method] When the electrolytic cell of this embodiment is used as an electrolytic cell for water electrolysis, hydrogen can be obtained as described above. That is, the hydrogen production method of this embodiment is a hydrogen production method using an electrolytic cell comprising an anode, a cathode facing the anode, and an ion exchange membrane of this embodiment disposed between the anode and the cathode, and includes the step of supplying an electrolyte to the electrolytic cell and performing water electrolysis. From the viewpoint of making the performance of the ion exchange membrane of this embodiment more apparent, the water electrolysis described above is preferably alkaline water electrolysis. The conditions of the above step are not particularly limited and may be the same as the operating conditions of various known electrolytic cells. For example, they may be the same as those in Japanese Patent No. 7353494, Japanese Patent No. 7136580, Japanese Patent No. 6826243, and Japanese Patent No. 3696137, etc.

[0081] In this embodiment, the first surface of the ion exchange membrane may be located on the electrode surface side of the anode and cathode that has higher rigidity. As described above, when the surface 10a of the ion exchange membrane 10, i.e., the surface with lower surface roughness, is located on the electrode surface side of the anode 21 and cathode 31 that has higher rigidity, resistance to pressure from the electrodes on the ion exchange membrane is more easily exhibited, and membrane damage tends to be further suppressed. [Examples]

[0082] The embodiment will be described in detail below with reference to examples. However, this embodiment is not limited to the following examples.

[0083] [Surface roughness] In the examples and comparative examples described later, if the ion exchange membrane obtained was in a wet state, a 500g weight was placed on each of the four edges of a 10cm x 10cm wet ion exchange membrane to prevent the center from drying out and becoming warped. The ion exchange membrane was then dried by placing it in a dryer (YAMATO forced-air constant-temperature dryer DKM400) heated to 50°C for 5 hours (drying step). In the examples and comparative examples described later, if the ion exchange membrane obtained was in a dry state, the above drying step was omitted. A dry ion-exchange membrane was placed in a laser microscope (KEYENCE shape analysis laser microscope). Laser measurement was performed at a magnification of 50x, with a grid of 12 x 7 squares (each square measuring 282 μm x 211 μm). Subsequently, basic measurements were taken at a pitch of 0.12 μm. The measurement results were analyzed using the KEYENCE multi-file analysis application (version 2.2.0.93) in the following procedure to calculate surface roughness. First, the waviness of the membrane itself was removed using the waviness removal (correction strength 5) function in the shape correction of the image processing tool. Then, the entire area was selected using the surface roughness analysis tool, and the surface roughness R was calculated. This was measured for both the cathode-facing and anode-facing surfaces of the composite membrane, and R1 and R2 were calculated. Furthermore, if there is a relative relationship between the surface roughness of the cathode-facing surface and the surface roughness of the anode-facing surface, the surface with the larger value is designated as R2 and identified as the second surface, and the surface with the smaller value is designated as R1 and identified as the first surface. If there is no such relative relationship, the surface facing the drum during the integration process in the ion exchange membrane fabrication described later is identified as the first surface (surface roughness R1).

[0084] [Thickness h1 and h2] A dry ion-exchange membrane was cut perpendicular to the first surface 1a to obtain a sample with a long side of 6 mm or more and a short side of 100 μm. The cross-section of this sample was fixed so that it faced upwards, and the cross-section was observed using an optical microscope. Within the field of view, the position P1 containing reinforcing material was identified as the portion containing reinforcing threads (see P1 in Figure 3). Similarly, the position P2 without reinforcing material in the observation field of view was identified as the portion not containing reinforcing threads (see P2 in Figure 3). In cases where both reinforcing threads and sacrificial threads were used as reinforcing material, position P1 was identified as the portion containing at least one of the reinforcing threads and sacrificial threads, and position P2 was identified as the portion not containing either the reinforcing threads or sacrificial threads. Within the observation field of view of one cross-section, the largest and second largest measured values ​​of the film thickness at position P1 were recorded. This measurement was performed on 50 cross-sections, and the average value of the 100 points was identified as h1. Furthermore, within the observation field of each cross-section, the smallest and second smallest measured values ​​of film thickness at position P2 were recorded. This measurement was performed on 50 cross-sections, and the average value of the 100 measurement results was identified as h2.

[0085] [Distance L1 between reinforcing materials] A dry ion-exchange membrane was cut perpendicular to the first surface 1a to obtain a sample with a long side of 6 mm or more and a short side of 100 μm. The cross-section of this sample was fixed so that it faced upwards, and the cross-section was observed using an optical microscope. Within the field of view, the position P1 where the reinforcing material was located was identified in the same way as for [thickness h1 and h2] described above. In all examples, as shown in Figure 3, it was observed that multiple reinforcing materials 2 existed along the planar direction D1 of the ion-exchange membrane 10. That is, it was confirmed that there were multiple positions P1 within this observation field of view. For each of the multiple positions P1, the portion Pmax that gave the largest measured value of the film thickness was identified. Next, the distance between two adjacent Pmax points was recorded. The above measurement was performed for all reinforcing materials within the observation field of view of one cross-section (as in the example in Figure 3, two measured values ​​of L1 are obtained). This was repeated, and the average value of a total of 100 measurement results was identified as L1.

[0086] [Reinforced yarn rate] A dry ion-exchange membrane was cut perpendicular to the first surface 1a to obtain a sample with a long side of 6 mm or more and a short side of 100 μm. Using a microscope (OLYMPUS), cross-sectional images including the reinforcing material, as shown in Figure 2, were taken. One reinforcing thread and one adjacent reinforcing thread (either left or right) were selected from the taken image. The total cross-sectional area X of the two reinforcing threads was calculated. Next, the total cross-sectional area Y of the sacrificial threads between the two reinforcing threads was calculated. In addition, if there were elution pores formed by the elution of the sacrificial threads, their total cross-sectional area Z was calculated. Using this, the reinforcing thread ratio was calculated from the following formula. Reinforced thread ratio K i ={(Total cross-sectional area of ​​reinforcing threads X)÷(Total cross-sectional area of ​​reinforcing threads X + Total cross-sectional area of ​​sacrificial threads Y + Total cross-sectional area of ​​elution pores of sacrificial threads Z)}×100 This process was repeated, and the average value of 100 measurements taken for any given reinforcing thread was defined as the reinforcing thread ratio K. The results of evaluating the reinforcing thread ratio K according to the following criteria are shown in Table 1. (Evaluation Criteria) A: Over 99% B: 90% or more, less than 99% C: Less than 90%

[0087] [Method for measuring the height and arrangement density of protruding parts] The height and density of the protrusions were confirmed using the following method. First, the point with the lowest height on the surface of the ion-exchange membrane within a 1000 μm square area was used as the reference point. Protrusions were defined as areas with a height of 20 μm or more from this reference point. The height was measured using a KEYENCE "Color 3D Laser Microscope (VK-9710)". Specifically, a 10 cm x 10 cm section was cut from a dry ion-exchange membrane, and the second surface 1b side of the ion-exchange membrane was fixed to a smooth plate with double-sided tape. The first surface 1a side of the ion-exchange membrane was then placed on the measurement stage facing the measurement lens. For each 10 cm x 10 cm section of membrane, the shape on the surface of the ion-exchange membrane was observed within a 1000 μm square measurement area. The height H of the protrusions was determined by measuring the height from the point with the lowest height, which was used as the reference point. Furthermore, to determine the arrangement density P of the protrusions, three 10cm x 10cm sections of the ion exchange membrane were arbitrarily cut out, and the arrangement density P was calculated by averaging the values ​​measured at nine locations within a 1000 μm square measurement area in each of these 10cm x 10cm sections.

[0088] [Ion exchange capacity] Approximately 1 g each of polymers S-1 and C-1 (fluorine-containing polymers having precursors for ion exchange groups), described later, were sampled and press-molded at a temperature approximately 30°C higher than the pseudo-melting point of the polymer to obtain polymer films. Each obtained film was subjected to transmission infrared spectroscopy. The proportions of the obtained infrared peaks CF2, CF, CH3, OH, and SO2F were calculated. These were used as the proportions of structural units having sulfonic acid / carboxylic acid functional groups obtained by hydrolysis of each polymer, and the ion exchange capacity was determined using a calibration curve with samples whose ion exchange capacity was known, as calculated by titration.

[0089] [Delamination resistance evaluation] The electrolytic cell used for electrolysis had a structure in which an ion exchange membrane was placed between the anode and cathode, and consisted of three pairs of forced-circulation zero-gap electrolytic cells arranged in series. As the cathode, a plain weave mesh electrode made of 0.15 mm diameter nickel wires woven with 40 mesh, coated with platinum and palladium as catalysts, was placed. Ni expanded metal was used as the anode. In addition, a conductive cushion mat made of 0.15 mm nickel wire was placed on the cathode side as an elastic material. Here, the first surface of the ion exchange membrane was positioned on the anode side. Using the above electrolytic cell, a 26 wt% sodium hydroxide aqueous solution was supplied to both the anode and cathode sides. The temperature of the electrolytic cell was set to 70°C, and the current was 10 kA / m 2 The current was applied at this current density for a total of six days. Table 1 shows the difference compared to the initial voltage loss of the film in question. Specifically, it shows the value calculated from the following formula, and the difference will be positive if delamination occurs. The difference in voltage loss before and after delamination resistance evaluation is ΔV = (voltage loss after delamination resistance evaluation) [mV] - (voltage loss before delamination resistance evaluation) [mV]. In Table 1, if the difference in voltage loss ΔV before and after the delamination resistance evaluation was negative to 0, there was no delamination and it was evaluated as A. If ΔV was positive, there was delamination and it was evaluated as B. In addition to checking for changes in voltage, we also confirmed the presence or absence of delamination by observing the extracted film with a microscope.

[0090] [Initial voltage loss evaluation] The electrolytic cell used for electrolysis had a structure in which an ion exchange membrane was placed between the anode and cathode, and consisted of three pairs of forced-circulation zero-gap electrolytic cells arranged in series. As the cathode, a plain weave mesh electrode made of 0.15 mm diameter nickel wire coated with platinum and palladium as catalysts was placed. Ni expanded metal was used as the anode. In addition, a conductive cushion mat made of 0.15 mm nickel wire was placed on the cathode side as an elastic material. Here, the first surface of the ion exchange membrane was positioned on the anode side. Using the above electrolytic cell, a 20 wt% sodium hydroxide aqueous solution was supplied to the anode and cathode sides. The temperature of the electrolytic cell was set to 90°C, and the current was 6 kA / m 2 The current density was maintained for a total of 10 hours. After 10 hours, the impedance was measured. For each of the three cells arranged in series, the resistance of the film was calculated, and the average value was determined as the voltage loss. Table 1 shows the difference in initial voltage loss compared to Comparative Example 1. Specifically, it shows the value calculated from the following formula, where - indicates a reduction in film voltage loss compared to Comparative Example 1, and + indicates an increase. Initial film voltage loss (difference relative to Comparative Example 1) ΔV = (film voltage loss of Comparative Example and Example) [mV] - (film voltage loss of Comparative Example 1) [mV]

[0091] [Differential pressure fluctuation resistance] To accelerate the evaluation of the effect of the differential pressure between the anode and cathode chambers on the ion exchange membrane, as observed during electrolytic cell operation (when current flows through the electrodes), the following accelerated test was conducted. First, an anode and cathode measuring 65 mm x 69 mm were prepared, and the ion exchange membranes for each example were placed between them to fabricate a zero-gap electrolytic cell with an anode chamber and a cathode chamber. Here, as the anode, an expanded metal made of nickel with a center-to-center distance of 3 mm in the short mesh direction and a center-to-center distance of 4.5 mm in the long mesh direction was used. As the cathode, a plain weave mesh electrode made of 0.15 mm diameter nickel wires woven with 40 mesh, coated with platinum and palladium as catalysts, was placed. In addition, a conductive cushion mat made of 0.15 mm nickel wire was placed on the cathode side as an elastic material. Here, the first surface of the ion exchange membrane was positioned on the anode side. In this electrolytic cell, the cell was filled with water, and a pressure swing was performed by controlling the gas pressure to create a pressure difference between the anode chamber and the cathode chamber. Specifically, a pressure swing from 0 kPa to 80 kPa was repeated approximately 100 times per hour. In each pressure swing, the pressure was first increased to 80 kPa over 15 seconds, held at 80 kPa for 3 seconds, then decreased to 0 kPa over 15 seconds, held at 0 kPa for 3 seconds, and this series of operations constituted one pressure swing. During the pressure swing, it was observed that the ion exchange membrane fixed in the zero-gap electrolytic cell tended to be more strongly affected by the pressure, especially in areas that were prone to becoming free. Specifically, it was observed that pressure was more easily applied to the ion exchange membrane near the frame that fixes the ion exchange membrane in the electrolytic cell (fixing the outer edge of the ion exchange membrane in the electrolytic cell) (the gap between the anode and the frame), and near the opening of the anode (expanded metal). After repeating the above pressure swing a predetermined number of times, the appearance of the ion exchange membrane was visually inspected to check for damage. This procedure was repeated until damage was visible or until the predetermined number of times was reached. The above test was performed on each example of ion exchange membrane, and its resistance to differential pressure fluctuations was evaluated according to the following criteria. (Evaluation Criteria) A: No damage occurred even after more than 10,000 pressure swings. B: Damage was observed at 7000-9999 pressure swings. C: Damage was observed during 2500-6999 pressure swings. D: Damage was observed after 1-2500 pressure swings.

[0092] [Gas permeability] The hydrogen gas permeability of an ion exchange membrane, moistened with water, was measured in accordance with "Annex B (Normative) Test method by gas chromatography" described in JIS K 7126-2:2006 "Plastics - Films and sheets - Test methods for gas permeability - Part 2: Isobaric method" (corresponding international standard: ISO 15105-2:2003). A gas permeability analyzer (GTR-1 00XFAG, manufactured by GTR Tech Co., Ltd.) was used as the measuring device. The measurement conditions were 90°C and 85%RH with double-sided humidification. Table 1 shows the difference in gas permeability between Comparative Example 2 and the other example. Specifically, it shows the value calculated from the following formula. Gas permeability (difference from Comparative Example 2) ΔGTR = (gas permeability of Comparative Example and Example) [10 -3 ×mol / m 2 ·hr·kPa]- (Gas permeability of Comparative Example 2)[10 -3 ×mol / m 2 ·hr·kPa]

[0093] [polymer] As polymer S-1, a monomer represented by the following formula (5) and a monomer represented by the following formula (6) were copolymerized to obtain a polymer with an ion exchange capacity of 1.05 milliequivalents / g. CF2 = CF2...(5) CF2=CFO-CF2CF(CF3)O-(CF2)2-SO2F ···(6)

[0094] As polymer C-1, the monomer represented by formula (5) above and the monomer represented by formula (7) below were copolymerized to obtain a polymer with an ion exchange capacity of 0.7 milliequivalents / g. CF2=CFO-CF2CF(CF3)O-(CF2)2-COOCH3...(7)

[0095] [Reinforcement material] A 100-denier polytetrafluoroethylene (PTFE) monofilament yarn was prepared as a reinforcing yarn. The reinforcing yarn was woven in a plain weave with a weaving density of 25 threads / inch. The resulting fabric was compressed on a roll at 125°C to obtain reinforcing material A.

[0096] A 90-denier polytetrafluoroethylene (PTFE) monofilament yarn was prepared as the reinforcing yarn. A multifilament yarn was prepared by twisting together six 6.7-denier polyethylene terephthalate (PET) strands as the sacrificial yarn. The reinforcing yarn was woven in a plain weave with a weaving density of 24 threads / inch, and two sacrificial yarns were placed between adjacent reinforcing yarns. The resulting fabric was compressed on a roll at 125°C to obtain reinforcing material B.

[0097] [Example 1] (Integration of each material) Two films A were obtained from polymer S-1 using the T-die method (total film thickness of the two films was 110 μm). A drum was prepared that had a heating source and a vacuum source inside and had micropores on its surface. On this drum, embossed release paper, film A, reinforcing material A, and film A were laminated in that order, and the materials were integrated under heating and reduced pressure (-650 mmHg) at 220°C while removing air between each material to obtain a composite film (a film containing the precursor of the sulfonic acid type film body and the reinforcing material). The embossed release paper had an average height of 150 μm and 500 protrusions / cm². 2 The materials used were created by processing release paper with a metal roll heated to 40°C and a resin pressure roll. When the film on the embossed release paper side was heated and depressurized, a rough surface corresponding to the embossing was formed. On the other hand, on the atmospheric side, a rough surface was formed as the resin-only portion flowed due to heating and depressurization in the portion with reinforcing material.

[0098] (Hydrolysis) The obtained composite film was hydrolyzed in a hydrolysis step by immersing it in an aqueous solution containing 30% by mass of DMSO and 15% by mass of potassium hydroxide (KOH) at 90°C for 1 hour, after which it was washed with water and dried. In this way, a composite film containing a sulfonic acid type film body and a reinforcing material was obtained.

[0099] (Formation of a hydrophilic layer) Furthermore, a suspension was prepared by adding 20% ​​by mass of zirconium oxide with a primary particle size of 1 μm to a 5% by mass ethanol solution of the acid-type polymer S-1 and dispersing it. This suspension was sprayed onto both sides of the composite film that had undergone the above hydrolysis by spraying method and dried, resulting in a concentration of 0.5 mg / cm². 2 An ion exchange membrane was obtained by forming a hydrophilic layer on the surface of the composite membrane.

[0100] Table 1 shows the results of various measurements and evaluations performed on the ion exchange membrane obtained as described above.

[0101] [Example 2] Film B and Film C were obtained from polymer S-1 using the T-die method (the total film thickness of Film B and Film C was 110 μm). The ion exchange membrane of Example 2 was obtained using the same method as in Example 1, except that the layers were stacked in the order of embossed release paper, Film B, Reinforcement B, and Film C.

[0102] [Comparative Example 1] Film D was obtained from polymer S-1 and film E from polymer C-1 using the T-die method (the total film thickness of films D and E was 110 μm). In the composite film fabrication in Example 1, the layers were stacked in the following order: unembossed release paper, reinforcing material B, film D, film E, and unembossed release paper, and then heat-pressed. Except for the above, the ion exchange film of Comparative Example 1 was obtained using the same method as in Example 1.

[0103] [Comparative Example 2] In the composite film fabrication in Example 1, the layers were laminated in the following order: unembossed release paper, reinforcing material B, film D, and film E. Except for the above point, the ion exchange film of Comparative Example 2 was obtained using the same manufacturing method as in Example 1.

[0104] [Comparative Example 3] A film F (thickness 110 μm) was obtained from polymer S-1 using the T-die method. In the fabrication of the composite film in Comparative Example 1, the layers were stacked in the following order: unembossed release paper, reinforcing material B, film F, and unembossed release paper, and then heat-pressed. Except for the above point, the ion exchange film of Comparative Example 3 was obtained using the same method as in Comparative Example 1.

[0105] [Table 1]

[0106] From the examples and comparative examples, it was shown that the presence of a sulfonic acid type membrane (without a carboxylic acid type layer) and the presence of a rough surface in such a membrane allow for a lower electrolysis voltage, resulting in excellent stability during electrolysis operation, and particularly excellent resistance to differential pressure fluctuations. The reason why the ion exchange membrane in the examples exhibits excellent resistance to differential pressure fluctuations is not entirely clear, and this is not intended to limit the reasons, but it can be inferred as follows: That is, the presence of a rough surface in the sulfonic acid type membrane has the effect of releasing the pressure at the contact point between the rough surface and the electrode to the non-electrode contact portion of the rough surface when pressure is applied while in contact with the electrode. [Explanation of Symbols]

[0107] 1...Sulfonic acid type membrane body, 1a...First surface, 1b...Second surface, 2...Reinforcement material, 3...Hydrophilic layer, δ1...Protrusion, δ2...Protrusion, 10...Ion exchange membrane, 20...Anode chamber, 21...Anode, 30...Cathode chamber, 31...Cathode, 41...Partition wall, 42...Electrode, 42a...Anode, 42c...Cathode, 42e...Conductive elastic body, 42r...Current collector, 43...Outer frame, 44...Partition, 45...Electrode chamber, 45a...Anode chamber, 45c...Cathode Chamber, 46...Rectifier plate (rib), 47...Gasket, 50...Bipolar electrolytic cell for alkaline water electrolysis, 51g...Fast head (loose head), 51i...Insulating plate, 51a...Anode terminal element, 51c...Cathode terminal element, 51r...Tie rod, 60...Bipolar element, 65...Electrolytic cell, 100...Electrolytic cell, D1...Surface direction, D2...Given direction along the partition wall (direction of electrolyte passage), Z...Zero gap structure

Claims

1. The invention comprises a sulfonic acid type membrane body containing a polymer having a sulfonic acid group, and a reinforcing material disposed within the sulfonic acid type membrane body, The surface roughness R1 of the first surface in the sulfonic acid type film body is 10 μm or more. The surface roughness R2 of the second surface in the sulfonic acid type film body is 10 μm or more. An ion exchange membrane in which the surface roughness R1 is smaller than the surface roughness R2.

2. The reinforcing material includes reinforcing threads, The ion exchange membrane according to claim 1, wherein the content of the reinforcing yarn in the reinforcing material is 90% or more.

3. The ion exchange membrane has a protrusion on the first surface having a height H of 20 μm or more and 95 μm or less. The arrangement density of the protrusions on the first surface is 50 pieces / cm². 2 More than 1200 pieces / cm 2 The ion exchange membrane according to claim 1, which is as follows:

4. The reinforcing material includes reinforcing threads, The ion exchange membrane according to claim 1, wherein the weaving density of the reinforcing yarn is 20 to 150 threads / inch.

5. The ion exchange membrane according to claim 1, wherein in a cross-section of the ion exchange membrane, the thickness h1 of the ion exchange membrane at position P1 where the reinforcing material is present and the thickness h2 of the ion exchange membrane at position P2 where the reinforcing material is absent satisfy 1.3 ≤ h1 / h2 ≤ 10.

6. The ion exchange membrane according to claim 5, wherein the thickness h2 is 10 μm or more and 169 μm or less.

7. The ion exchange membrane according to claim 5, wherein the thickness h1 is 100 μm or more and 300 μm or less.

8. Multiple reinforcing materials are present along the planar direction of the ion exchange membrane, The ion exchange membrane according to claim 4, wherein the distance L1 between adjacent reinforcing members is 1 / 150 inch or more and 1 / 10 inch or less.

9. The ion exchange membrane according to claim 1, wherein the ion exchange capacity of the polymer is 0.90 milliequivalents / g or more and 2.00 milliequivalents / g or less.

10. The ion exchange membrane according to claim 1, wherein the polymer is a fluorine-containing polymer.

11. The ion exchange membrane according to claim 1, wherein the polymer comprises a polymer P1 having a unit represented by the following formula (1). -[CF 2 -CF(-O-CF 2 CF(CF 3 )-O-(CF 2 ) m -SO 3 M)]- (1) (In equation (1), m is an integer between 1 and 6, and M is an alkali metal.)

12. The ion exchange membrane according to claim 4, wherein the reinforcing yarn comprises at least one selected from the group consisting of PTFE and PFA.

13. The ion exchange membrane according to claim 4, wherein the denier count of the reinforcing yarn is 20 to 150 denier.

14. The ion exchange membrane according to claim 1, further comprising a hydrophilic layer disposed on the first surface and / or the second surface.

15. The ion exchange membrane according to claim 14, wherein the hydrophilic layer contains inorganic particles.

16. The ion exchange membrane according to claim 15, wherein the inorganic particles include at least one selected from the group consisting of oxides, nitrides, and carbides of Group 4 or Group 14 elements.

17. The inorganic particles include at least one selected from the group consisting of SiO 2 , SiC, ZrO 2 and ZrC, and the ion exchange membrane according to claim 15.

18. An ion exchange membrane used for water electrolysis, according to any one of claims 1 to 17.

19. An ion exchange membrane used in alkaline water electrolysis, according to any one of claims 1 to 17.

20. Anode and, A cathode facing the anode, An ion exchange membrane according to any one of claims 1 to 17 is disposed between the anode and the cathode, An electrolytic cell equipped with the following features.

21. The electrolytic cell according to claim 20, wherein the first surface of the ion exchange membrane is located on the electrode surface side of the anode and the cathode that has higher rigidity.

22. An electrolytic cell according to claim 20, used for alkaline water electrolysis.

23. The electrolytic cell according to claim 20, having a zero-gap structure.

24. A method for producing hydrogen using the electrolytic cell described in claim 20, A method for producing hydrogen, comprising the step of supplying an electrolyte to the electrolytic cell and performing water electrolysis.

25. The method for producing hydrogen according to claim 24, wherein the first surface of the ion exchange membrane is arranged on the electrode surface side of the anode and the cathode that has higher rigidity.

26. The method for producing hydrogen according to claim 24, wherein the water electrolysis is alkaline water electrolysis.