Separator for alkaline-water electrolyses, alkaline-water electrolysis member, alkaline-water electrolysis cell, alkaline-water electrolysis device, and method for producing hydrogen

Abstract

A separator for alkaline-water electrolyses which comprises woven fabric and a porous material other than the woven fabric, the separator having a membrane thickness of 100-250 μm, wherein the woven fabric has a percentage of openings of 45.0-72.0%; an alkaline-water electrolysis member; an alkaline-water electrolysis cell; an alkaline-water electrolysis device; and a method for producing hydrogen.

Description

Separator for alkaline water electrolysis, alkaline water electrolysis member, alkaline water electrolysis cell, alkaline water electrolysis apparatus, and hydrogen production method

[0001] The present invention relates to a separator for alkaline water electrolysis, an alkaline water electrolysis member, an alkaline water electrolysis cell, an alkaline water electrolysis apparatus, and a hydrogen production method.

[0002] Hydrogen is a clean energy that does not emit carbon dioxide and is used as a fuel for, for example, fuel cell vehicles and household fuel cells. As a method for producing hydrogen, alkaline water electrolysis using a high-concentration alkaline aqueous solution as an electrolyte is known. If alkaline water electrolysis is performed using a power generation system that utilizes renewable energy as a power source, hydrogen can be produced without emitting carbon dioxide, so hydrogen is attracting increasing attention as a basic energy for a sustainable society.

[0003] In alkaline water electrolysis, in order to prevent the bubble-like hydrogen (2H ２ O + 2e － →H ２ + 2OH － ) generated at the cathode from moving to the anode side, and also to prevent the bubble-like oxygen (4OH － →O ２ + 2H ２ O + 4e － ) generated at the anode from moving to the cathode side, a separator (membrane) having gas barrier properties is disposed between the cathode and the anode. Also, in an alkaline water electrolysis apparatus, water is consumed on the cathode side and water is generated on the anode side, so as it is, the balance of the electrolytic solution changes across the separator. To suppress this, during alkaline water electrolysis, the flow rate of the electrolytic solution is adjusted for each of the electrodes of the cathode and the anode. At this time, if the liquid permeability of the separator is high, the effect of the above flow rate adjustment is diminished, so suppression of the permeation of the electrolytic solution (hereinafter referred to as "suppression of liquid permeability") is also required. Further, in addition to the gas barrier property and the suppression of liquid permeability of this separator, OH －Ionic conductivity that allows hydroxyl ions to pass through is also required. For this reason, porous membranes (microporous membranes) made of organic polymer materials are used as separators in alkaline water electrolysis. In other words, the above separator is required to achieve a balance between two conflicting properties: ensuring ionic conductivity by providing liquid permeability through the porous membrane, while suppressing liquid permeability.

[0004] It is known that porous separators for alkaline water electrolysis can be formed by a wet phase separation method. In wet phase separation, first, an organic polymer, which is a constituent material of the porous membrane, is dissolved in a solvent that dissolves the organic polymer (a good solvent) to prepare a film-forming solution, and a coating film of this film-forming solution is formed. Next, the coating film is immersed in a solvent (poor solvent, coagulation bath) that does not dissolve the organic polymer and is miscible with the good solvent. As the proportion of the good solvent in the coating film decreases due to this immersion, the organic polymer and the solvent undergo phase separation, and the organic polymer gels (coagulates), resulting in a porous membrane. To increase the mechanical strength of the porous separator, a porous support such as a nonwoven fabric or woven fabric is placed in the film-forming solution, and the phase separation is performed in the presence of the porous support. This creates a porous structure in the impregnated organic polymer in the film-forming solution, and a porous separator can be formed in which the porous support and the porous structure of the organic polymer are integrated. Furthermore, by incorporating hydrophilic inorganic particles into the separator, the gas barrier properties can be enhanced while efficiently allowing the alkaline aqueous solution to penetrate into the separator, thereby further improving ionic conductivity.

[0005] However, while the above-mentioned porous support can increase the mechanical strength of the porous separator, it also reduces the ionic conductivity of the separator. Therefore, technological development is underway to improve ionic conductivity and enhance the electrolysis efficiency of alkaline water electrolysis. For example, Patent Document 1 describes a water electrolysis separator comprising a porous support and a porous layer provided on the support, characterized in that the porous support is substantially removable from the separator. Patent Document 1 states that when placed in the electrolytic cell of an alkaline electrolytic cell, reinforcement of the separator by the porous support is no longer necessary, and in particular, in the so-called zero-gap type where the separator and each electrode are in contact, the separator does not vibrate by releasing air bubbles, and therefore does not suffer fatigue that could cause cracks or tears in the separator. That is, the water electrolysis separator described in Patent Document 1 is described as improving ionic conductivity while providing sufficient mechanical strength to the separator during the separator manufacturing process by dissolving and decomposing the porous support with an alkaline solution or electrolyte used in the electrolytic cell and removing the porous support. Furthermore, Patent Document 2 describes a doping solution applied to both sides of a porous support when a separator containing a porous support and a porous layer is manufactured by a wet phase separation method, with a shear rate of 100 s. －１ The invention describes a method for manufacturing an alkaline water electrolysis separator, characterized by using a doped solution having a viscosity of at least 20 Pa·s as measured at a temperature of 20°C. In the prior art, only methods for manufacturing separators with a porous support thickness exceeding 190 μm have been disclosed. However, according to the manufacturing method described in Patent Document 2, a separator can be obtained in which the porous support has a thickness of 150 μm or less and the separator thickness is less than 250 μm, exhibiting sufficient mechanical quality while having improved ion conductivity. In the example in Patent Document 2, it is described that a separator with a thickness of 220 μm, including a porous support with a thickness of 100 μm, can be obtained with sufficient flatness / undulation.

[0006] Japanese Patent Publication No. 2023-531556 Japanese Patent Publication No. 2023-531792

[0007] The present inventors have conducted extensive research on techniques to improve the ion conductivity of separators by thinning a porous support, and have found that separators containing a thinned porous support suffer from a problem where the liquid permeability of the separator increases over time when subjected to alkaline water electrolysis under high temperature (70°C or higher) and high alkali concentration (for example, alkaline water with a concentration of about 30% by mass). In the separator described in Patent Document 1, the porous support is removed from the separator, so the liquid permeability of the separator is considered to be high. Furthermore, the example in Patent Document 2 only evaluates the flatness / undulation of the obtained separator, and does not evaluate its use as a separator in alkaline water electrolysis under high temperature and high alkali concentration conditions. Therefore, it does not describe the problem of the liquid permeability of the separator increasing over time when used under high temperature and high alkali concentration conditions, nor does it describe how to solve this problem.

[0008] The present invention aims to provide an alkaline water electrolysis separator that has low ion resistance and does not easily cause an increase in liquid permeability under high temperature and high concentration alkaline conditions. Furthermore, the present invention aims to provide an alkaline water electrolysis component, an alkaline water electrolysis cell, an alkaline water electrolysis apparatus, and a hydrogen production method using the alkaline water electrolysis separator of the present invention.

[0009] The above problems of the present invention have been solved by the following means: [1] An alkaline water electrolysis separator comprising a woven fabric and a porous material other than the woven fabric, wherein the film thickness of the alkaline water electrolysis separator is 100 to 250 μm and the aperture ratio of the woven fabric is 45.0 to 72.0%. [2] The alkaline water electrolysis separator according to [1], wherein the film thickness of the separator is 110 to 200 μm and the aperture ratio of the woven fabric is 50.0 to 65.0%. [3] The alkaline water electrolysis separator according to [1] or [2], wherein the diameter of the fibers constituting the woven fabric is 20 to 60 μm. [4] The alkaline water electrolysis separator according to any one of [1] to [3], wherein the polymer constituting the woven fabric comprises at least one of polyphenylene sulfide and polyether ether ketone. [5] An alkaline water electrolysis separator according to any one of [1] to [4], wherein the porous material other than the woven fabric contains an organic polymer. [6] An alkaline water electrolysis separator according to any one of [1] to [5], wherein the alkaline water electrolysis separator is a structure in which the woven fabric is embedded in a porous material other than the woven fabric. [7] An alkaline water electrolysis component comprising the alkaline water electrolysis separator according to any one of [1] to [6]. [8] An alkaline water electrolysis cell comprising the alkaline water electrolysis separator according to any one of [1] to [6], or the alkaline water electrolysis component according to [7]. [9] An alkaline water electrolysis apparatus comprising the alkaline water electrolysis cell according to [8].

[10] A method for producing hydrogen, comprising electrolyzing water using the alkaline water electrolysis apparatus according to [9].

[11] A method for producing hydrogen according to

[10] , comprising using an alkaline aqueous solution containing 10 to 35% by mass of a metal hydroxide as the electrolyte solution, and electrolyzing water at 70 to 95°C.

[0010] In the present invention, when describing physical properties and the like by indicating a numerical range, when separately explaining the upper limit value and the lower limit value of the numerical range, any upper limit value and lower limit value can be appropriately combined to form a specific numerical range. On the other hand, when explaining by setting a plurality of numerical ranges represented by "~", the upper limit value and the lower limit value forming the numerical range are not limited to the combination of the specific upper limit value and the specific lower limit value described before and after "~" as a specific numerical range, and can be a numerical range obtained by appropriately combining the upper limit value and the lower limit value of each numerical range. In the present invention, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0011] The separator for alkaline water electrolysis of the present invention has a low ionic resistance and is unlikely to cause an increase in liquid permeability under high-temperature and high-concentration alkaline conditions. Further, the alkaline water electrolysis member, the alkaline water electrolysis cell, and the alkaline water electrolysis apparatus of the present invention include the separator for alkaline water electrolysis of the present invention, and are excellent in alkaline water electrolysis efficiency and durability. Further, according to the hydrogen production method of the present invention, it is possible to continuously perform highly efficient hydrogen production by efficient alkaline water electrolysis.

[0012] FIG. 1 is a plan view schematically showing the aperture ratio of a woven fabric. FIG. 1(a) is a plan view showing one aperture composed of two warp threads and two weft threads, and FIG. 1(b) shows, in FIG. 1(a), the portion corresponding to the area of the aperture by oblique lines and the portion corresponding to the area of one mesh of warp and weft by a broken line. FIG. 2 is a drawing schematically showing an embodiment of an alkaline water electrolysis apparatus. FIG. 3 is a drawing schematically showing another embodiment of the alkaline water electrolysis apparatus. FIG. 4 is a drawing schematically showing yet another embodiment of the alkaline water electrolysis apparatus. FIG. 5 is a schematic cross-sectional view of an alkaline water permeation measuring apparatus used in the examples. In FIG. 5, the hatching indicating the cross-sectional view is omitted.

[0013] [Separator for Alkaline Water Electrolysis] The alkaline water electrolysis separator of the present invention (hereinafter also referred to as "the separator of the present invention") is an alkaline water electrolysis separator comprising a woven fabric and a porous material other than the woven fabric (hereinafter also simply referred to as "porous material"), wherein the film thickness of the separator is 100 to 250 μm and the aperture ratio of the woven fabric is 45.0 to 72.0%. Despite the separator having a thin film thickness of 100 to 250 μm, the separator of the present invention has low ion resistance and is less prone to increased liquid permeability under high temperature and high concentration alkaline conditions due to the aperture ratio of the woven fabric being 45.0 to 72.0%. The reason for this is not clear, but it is presumed to be as follows. In other words, if the separator film thickness is thin, between 100 and 250 μm, and the opening ratio of the woven fabric is less than 45.0%, the number of fibers constituting the woven fabric increases, which increases the contact area between the woven fabric and other porous materials (the contact area from a macroscopic perspective) throughout the entire woven fabric. Furthermore, if the separator film thickness is thin, between 100 and 250 μm, and the opening ratio of the woven fabric exceeds 72.0%, the woven fabric's function as a support becomes insufficient. As a result, the flexibility and mechanical strength of the separator decrease, defects such as cracks are more likely to occur in the porous material parts other than the woven fabric, and it is thought that the liquid permeability of the separator increases over time when used under high temperature and high concentration alkaline conditions. In contrast, the separator of the present invention suppresses ion resistance to a desired level by making the separator film thickness 100 to 250 μm, while setting the opening ratio of the woven fabric to 45.0 to 72.0%. This suppresses the occurrence of defects at the contact portion between the woven fabric and the porous material other than the woven fabric, as well as the occurrence of cracks in the porous material portion other than the woven fabric. Therefore, it is considered that the liquid permeability of the separator will not increase over time when used under high temperature and high concentration alkaline conditions.

[0014] (Separator film thickness) The film thickness of the separator of the present invention is 100 to 250 μm, preferably 100 to 210 μm, more preferably 110 to 200 μm, and even more preferably 130 to 180 μm. This film thickness is obtained by taking a cross-section cut out from the separator of the present invention with a razor at a magnification (for example, 400 times) at which the cross-section of the separator of the present invention fits within one field of view, obtaining a cross-section SEM (scanning electron microscope) image, and assuming that there are no pores in the obtained cross-section SEM image (assuming a state where the pores are filled with an organic polymer), measuring the film thickness at 20 equally spaced points, obtaining the arithmetic mean value of the 20 measured values obtained, and rounding off the first decimal place in μm notation.

[0015] (Open area ratio of woven fabric) The open area ratio of the woven fabric is 45.0 to 72.0%, preferably 50.0 to 65.0%, and more preferably 53.0 to 63.0%. The open area ratio of the woven fabric will be described using the plan view of the woven fabric shown in FIG. 1. FIG. 1(a) shows one opening OPA composed of two warp threads WA and two weft threads WE when the woven fabric is viewed flatly. As shown in FIG. 1(b), the open area ratio is the ratio of the area S ＭＣ of the opening to the area S ＯＰＡ of one mesh of warp and weft. Therefore, using the wire diameter (fiber diameter) D of the warp thread WA and the weft thread WE and the distance of the opening (distance between one fiber and the fiber adjacent to it) OP shown in FIG. 1(a), the open area ratio is a value calculated by the following formula. Open area ratio (%) = {(OP) ２ / (OP + D) ２} × 100% Here, OP means the distance between the openings (the distance between one fiber and the fiber located next to it), and is calculated using the following formula, with units of μm. OP = (25400 / MC) - D MC means the mesh count, which means the number of fibers per inch (25400 μm). D means the wire diameter (the diameter of the fiber), with units of μm. The mesh count (MC) and wire diameter (D) are determined by the following methods. Note that OP and D in Figure 1 are symbols used for explanatory purposes, and in reality, they are values ​​determined by the following methods. The number of fibers per inch (25400 μm) is measured at 20 different points on the woven fabric by microscopic observation, the arithmetic mean of the 20 measurements is calculated, and the value rounded to the first decimal place is taken as the mesh count (MC). Furthermore, the woven fabric is observed in a planar manner using a microscope or SEM, and the diameter of the fibers is measured at 20 different points on the fabric. The arithmetic mean of the 20 measurements is calculated and rounded to two decimal places to obtain the wire diameter (D). The opening ratio of the woven fabric in the separator can be measured and calculated using the method described above. This method involves removing the woven fabric from the separator using a solvent that dissolves porous materials other than the woven fabric but not the woven fabric itself, and then measuring the opening ratio of the removed woven fabric.

[0016] As a separator of the present invention, from the viewpoint of having lower ion resistance and being less prone to increased liquid permeability under high temperature and high concentration alkaline conditions, it is preferable that the film thickness of the separator is 110 to 200 μm and the opening ratio of the woven fabric is 50.0 to 65.0%, and more preferably that the film thickness of the separator is 110 to 200 μm, the opening ratio of the woven fabric is 50.0 to 65.0%, and the diameter of the fibers constituting the woven fabric, as described later, is 20 to 60 μm.

[0017] The separator of the present invention, which includes a woven fabric and a porous material other than the woven fabric, is not simply a laminated structure, but rather a structure in which the woven fabric and the porous material other than the woven fabric are inseparable (i.e., a composite). For example, as shown in the embodiments described later, the separator of the present invention is a composite (or a composite with a structure equivalent to the composite obtained by this method) formed by immersing the woven fabric in a film-forming solution constituting the porous material and subjecting it to wet phase separation while the woven fabric is encased. As described above, in the present invention, the structure of the composite formed by immersing the woven fabric in a film-forming solution constituting the porous material and subjecting it to wet phase separation while the woven fabric is encased is referred to as a "structure in which the woven fabric is enclosed within a porous material other than the woven fabric." It should be noted that the separator of the present invention is not limited to those manufactured by the method using the wet phase separation described above, but also includes those manufactured by other methods as long as they are a "structure in which the woven fabric is enclosed within a porous material other than the woven fabric." The specific configuration of the separator of the present invention is not particularly limited, as long as it is an alkaline water electrolysis separator comprising a woven fabric and a porous material other than the woven fabric, the film thickness of the separator is 100 to 250 μm, and the opening ratio of the woven fabric is 45.0 to 72.0%. For example, the separator of the present invention preferably has a configuration in which the woven fabric and the porous material other than the woven fabric are arranged on at least one of the outer surface and voids of the woven fabric. Furthermore, the porous material preferably contains an organic polymer, and it is also preferable that it further contains hydrophilic inorganic particles. Note that "outer surface of the woven fabric" means the surface of the film when the woven fabric is viewed from a macroscopic perspective as a single film with a thickness, and "voids of the woven fabric" means the gaps between the fibers that constitute the woven fabric. The structure in which the porous material is arranged on at least one of the outer surface and voids of the woven fabric can be adjusted as appropriate. For example, the porous material may be arranged only on the outer surface of the woven fabric. In this case, the porous material may be arranged only on one side of the woven fabric, or on both sides. Alternatively, the porous material may be arranged only in the voids of the woven fabric. Furthermore, the porous material may be arranged in a portion of the outer surface of the woven fabric and in a portion of the voids.In this invention, such forms are also included in structures in which a porous material is arranged on at least one of the outer surface and voids of the woven fabric. In particular, a structure in which the porous material is arranged on the entire outer surface and the entire voids of the woven fabric is preferred. The woven fabric, porous material, organic polymer and hydrophilic inorganic particles which are constituent materials of the porous material will be described in detail below.

[0018] (Woven Fabric) The woven fabric is applicable to separators for alkaline water electrolysis and is not particularly limited as long as the opening ratio of the woven fabric is 45.0 to 72.0%. The diameter of the fibers constituting the woven fabric (hereinafter also simply referred to as "fiber diameter") is not particularly limited, but can be 20 μm or more from the viewpoint of ensuring strength as a support in the separator, preferably 20 to 100 μm, more preferably 20 to 75 μm, and more preferably 20 to 60 μm from the viewpoint of further suppressing the increase in liquid permeability under high temperature and high concentration alkaline conditions. The fiber diameter is the value obtained by rounding the first decimal place of the arithmetic mean of 20 measurements obtained in the measurement and calculation method of the wire diameter (D) described in the section on opening ratio above.

[0019] The polymers constituting the woven fabric are not particularly limited, and examples include polypropylene, polyethylene, polysulfone, polyphenylene sulfide (PPS), polyamide, polyethersulfone, polyphenylsulfone, polyethylene terephthalate, polyetheretherketone (PEEK), sulfonated polyetheretherketone, monochlorotrifluoroethylene, copolymer of ethylene and tetrafluoroethylene or chlorotrifluoroethylene, polyimide, polyetherimide, and m-aramid. Among the above, it is preferable that the polymer constituting the woven fabric contains at least one of polypropylene, polyphenylene sulfide, and polyetheretherketone, and it is more preferable that it contains at least one of polyphenylene sulfide and polyetheretherketone.

[0020] The thickness of the woven fabric is preferably 30 to 150 μm, more preferably 30 to 100 μm, and even more preferably 30 to 75 μm. The thickness of the woven fabric is measured using a dot-type thickness gauge. The thickness of the woven fabric in the separator can be measured and calculated by removing the woven fabric from the separator using a solvent that dissolves the organic polymer contained in the porous material, and then measuring the thickness of the removed woven fabric using the method described above.

[0021] (Porous Material) The porous material is any porous material other than the woven fabric described above, which is applicable to a separator for alkaline water electrolysis, and has the function of blocking the permeation of gases (preferably hydrogen gas and oxygen gas) and allowing ions (preferably hydroxyl ions) to permeate. It can be used without any particular limitations. Specifically, the ion resistance of a 200 μm thick sample (a porous membrane sample that does not contain woven fabric) made using the materials constituting the porous material is 0.01 to 0.10 Ω·cm. ２ The permeability is 100 to 2000 L / (bar·m). ２ Porous materials with a density of hr (1 / 2) can preferably be used. Note that the ion resistance and water permeability are values ​​that are suppressed by the method described in the examples below, and the samples for measuring ion resistance and water permeability are prepared by the method described in the examples below.

[0022] The porous material preferably contains at least an organic polymer, and may further contain other components such as hydrophilic inorganic particles.

[0023] - Organic Polymers - Porous materials preferably contain organic polymers. Various organic polymers applicable to the wet phase separation described later can be used as organic polymers.

[0024] The organic polymer can be selected from, for example, fluororesins, olefin resins, polyester resins, aromatic hydrocarbon resins, etc. As the fluororesin, a resin selected from polyvinylidene fluoride and polytetrafluoroethylene is preferred. As the olefin resin, polypropylene resin is preferred. As the polyester resin, a resin selected from polyethylene terephthalate, polybutylene terephthalate, and polybutylene naphthalate is preferred. As the aromatic hydrocarbon resin, polystyrene resin is preferred.

[0025] Other preferred organic polymers include polysulfone (PS), polyethersulfone, polyphenylene sulfide, polyphenylsulfone, polyacrylate, polyetherimide, polyimide, and polyamideimide.

[0026] Organic polymers may be used individually or in combination of two or more types.

[0027] The organic polymer more preferably contains at least one of polyvinylidene fluoride, polysulfone, polyethersulfone, and polyphenylsulfone, and even more preferably contains at least one of polysulfone, polyethersulfone, and polyphenylsulfone.

[0028] The mass-average molecular weight (Mw) of the organic polymer is not particularly limited. Considering the handling properties of the film-forming solution described later and the mechanical strength of the resulting separator, it can be, for example, 10,000 to 500,000, and preferably 20,000 to 300,000. Mw can be determined under the following conditions. Instrument: HLC-8220GPC (Tosoh Corporation) Detector: Differential refractometer (RI (Refractive Index) detector) Pre-column: TSKGUARD COLUMN HXL-L 6mm x 40mm (Tosoh Corporation) Sample-side column: The following three columns are directly connected in order (all Tosoh Corporation): ・TSK-GEL GMHXL 7.8mm x 300mm ・TSK-GEL G4000HXL 7.8mm x 300mm ・TSK-GEL G2000HXL 7.8mm x 300mm Reference-side column: TSK-GEL G1000HXL 7.8mm x 300mm Oven temperature: 40℃ Mobile phase: THF (Tetrahydrofuran) Sample-side mobile phase flow rate: 1.0 mL / min Reference-side mobile phase flow rate: 1.0 mL / min Sample concentration: 0.1% by mass Sample injection volume: 100 μL Data acquisition time: 5 to 45 minutes after sample injection Sampling pitch: 300 milliseconds

[0029] The content of the organic polymer in the porous material can be 100% by mass. If the porous material contains other components in addition to the organic polymer, such as hydrophilic inorganic particles, the content of the organic polymer in the porous material is preferably, for example, 5 to 50% by mass, more preferably 5 to 40% by mass, even more preferably 7 to 30% by mass, and particularly preferably 9 to 25% by mass.

[0030] - Hydrophilic Inorganic Particles - Porous materials may contain hydrophilic inorganic particles. Hydrophilic inorganic particles are preferably selected from metal oxides and metal hydroxides.

[0031] The metal oxides mentioned above are preferably selected from zirconium oxide, titanium oxide, bismuth oxide, cerium oxide, and magnesium oxide.

[0032] The above metal hydroxide is preferably selected from zirconium hydroxide, titanium hydroxide, bismuth hydroxide, cerium hydroxide, and magnesium hydroxide.

[0033] In addition to particles selected from metal oxides and metal hydroxides, barium sulfate particles can also be used as hydrophilic inorganic particles.

[0034] Hydrophilic inorganic particles may be used individually or in combination of two or more types.

[0035] The particle size of the hydrophilic inorganic particles is preferably 0.05 to 2.00 μm, more preferably 0.10 to 1.50 μm, even more preferably 0.15 to 1.00 μm, and even more preferably 0.20 to 1.00 μm. This particle size is the median diameter (D50), and is determined by measuring the particle size distribution using laser diffraction and scattering methods, representing the particle size at which the cumulative distribution reaches 50% when the total volume of the particles is considered 100%.

[0036] When the porous material contains hydrophilic inorganic particles, the content of hydrophilic inorganic particles in the porous material is preferably 50 to 95% by mass, more preferably 60 to 95% by mass, even more preferably 70 to 93% by mass, and particularly preferably 75 to 91% by mass.

[0037] When the porous material contains hydrophilic inorganic particles, the ratio of the content of hydrophilic inorganic particles to the content of organic polymer in the porous material (hydrophilic inorganic particles / organic polymer) is preferably 10 / 1 to 1 / 1 by mass, more preferably 9 / 1 to 2 / 1, even more preferably 8 / 1 to 3 / 1, even more preferably 7 / 1 to 4 / 1, and even more preferably 6.5 / 1 to 4 / 1.

[0038] When the separator of the present invention is manufactured by the method for manufacturing the separator of the present invention described later, a certain amount of the good solvent described in the film-forming solution described later inevitably remains in the porous material. As a result, the total content of the good solvent in the porous material is usually 0.01 to 5.00% by mass.

[0039] From the viewpoint of gas barrier properties required for alkaline water electrolysis separators, the separator of the present invention preferably has a bubble point exceeding 1 bar, and more preferably exceeding 2 bar. The bubble point is determined by measuring using a palm porometer based on the bubble point method described in ASMT (American Society for Testing and Materials) F316-86, and the pressure at which the first bubble is generated in the resulting wet curve is defined as the bubble point.

[0040] The porosity of the separator of the present invention is preferably 30 to 70%, more preferably 40 to 60%, from the viewpoint of exhibiting excellent ion permeability and excellent gas barrier properties. This porosity is the value of porosity calculated from the insertion curve by the mercury intrusion method.

[0041] The separator of the present invention has an ion resistance of 0.08 Ω·cm, from the viewpoint of ion permeability required for alkaline water electrolysis separators. ２ Preferably less than 0.07 Ω·cm ２ Less than 0.06 Ω·cm is more preferable. ２ Less than 0.05 Ω·cm is even more preferable. ２ A value less than 0.01 Ω·cm is particularly preferable. However, a practical lower limit is 0.01 Ω·cm. ２ The above is true, and a preferred range is 0.01 Ω·cm. ２ 0.08Ω・cm or more ２ Examples include values ​​less than the following. Ion resistance is a value measured by the AC impedance method at 30°C with the separator of the present invention, punched out in a circular shape, set in a cell. Details are as described in the examples below.

[0042] The separator of the present invention satisfies the requirements for alkaline water electrolysis separators, namely, suppressing electrolyte permeability (liquid permeability) and providing gas barrier properties, with a water permeability of 100 L / (bar·m). ２ ・hr) or more 1000L / (bar・m ２ Preferably less than 100 L / (bar·m) ２ ・hr) or more 500L / (bar・m ２- Less than hr is more preferable. The permeability is calculated by setting a circularly punched separator of the present invention in a filter holder, supplying a 30% by mass potassium hydroxide aqueous solution heated to 85°C under a pressurized condition of 50 mbar to the circular separator from above, and measuring the amount of electrolyte (mL) that permeates through in 8 minutes. Further details are as described in the examples below.

[0043] The separator of the present invention can be used as a separator in a method for producing hydrogen by electrolyzing an alkaline aqueous solution using an electrolytic cell. In particular, it can be suitably used as an alkaline water electrolysis separator in the alkaline water electrolysis apparatus described below.

[0044] The separator of the present invention may be in the form of a long sheet wound into a roll, or it may be pre-cut into a predetermined shape according to its intended use, equipment, etc. From the viewpoint of manufacturing efficiency, it is also preferable that the separator of the present invention is in the form of a long sheet and has a thickness distribution in at least one of the width and length directions in which the thickness in the center of the sheet is greater than the thickness at both ends of the sheet. Furthermore, the separator of the present invention may be stored by immersing it in a preservation solution such as pure water. Furthermore, the separator of the present invention may be stored as a dry film without being immersed in a preservation solution.

[0045] [Method for Manufacturing Separators] The method for manufacturing separators is not particularly limited, but separators are usually manufactured by a method that includes forming a porous material by wet phase separation. In this method of forming a porous material by wet phase separation, an organic polymer is included as a constituent material of the porous material. Through this wet phase separation step, the separator of the present invention is obtained, which is composed of a porous material containing an organic polymer and a woven fabric. The separator of the present invention can be obtained by performing vapor induction phase separation and / or liquid induction phase separation as the wet phase separation. Specifically, it is preferably manufactured by a method that includes impregnating a woven fabric with a film-forming solution containing the constituent materials of the porous material, performing water vapor induction phase separation on a laminate consisting of the obtained woven fabric and a coating film containing the constituent materials of the porous material, and / or immersing the laminate (the laminate after water vapor induction phase separation if the above water vapor induction phase separation is performed) in a condensation bath. Note that the above water vapor induction phase separation and / or liquid induction phase separation can also be performed using a film-forming support. The separator of the present invention can be obtained by casting a film-forming solution containing the constituent materials of the porous material onto a film-forming support to form a coating film, impregnating the coating film with a woven fabric, and then performing wet phase separation with the film-forming support attached or with the film-forming support removed.

[0046] (Film-forming solution) The film-forming solution can be any dissolution of an organic polymer that will be a constituent material of the porous material, and may contain the organic polymer and a solvent, and may also contain hydrophilic inorganic particles. The description of organic polymers in the separator described above can be applied to the organic polymer contained in the film-forming solution. The description of hydrophilic inorganic particles in the separator described above can also be applied to the hydrophilic inorganic particles that may be contained in the film-forming solution.

[0047] - Solvent - The film-forming solution in wet phase separation can be any solvent (good solvent) that can dissolve the above organic polymer, and is preferably miscible with water. The solvent is preferably selected from N-methyl-2-pyrrolidone (NMP), N-ethyl-pyrrolidone (NEP), N-butyl-pyrrolidone (NBP), N,N-dimethylformamide (DMF), formamide, dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAC), acetonitrile, γ-valerolactone, compound (2), compound (3) shown below, and mixtures thereof, with at least one of NMP, NBP, γ-valerolactone, compound (2), and compound (3) shown below being more preferred.

[0048] If the film-forming solution contains hydrophilic inorganic particles, the solvent content in the film-forming solution is preferably 10 to 85% by mass, more preferably 15 to 80% by mass, even more preferably 25 to 70% by mass, even more preferably 30 to 65% by mass, even more preferably 32 to 60% by mass, and even more preferably 35 to 50% by mass. If the film-forming solution does not contain hydrophilic inorganic particles, the solvent content in the film-forming solution is preferably 20 to 95% by mass, more preferably 25 to 90% by mass, even more preferably 30 to 80% by mass, even more preferably 40 to 80% by mass, even more preferably 45 to 75% by mass, and even more preferably 50 to 75% by mass.

[0049] - Organic Polymers - When the film-forming solution contains hydrophilic inorganic particles, the content of organic polymers in the film-forming solution is preferably 2 to 30% by mass, more preferably 4 to 20% by mass, even more preferably 5 to 15% by mass, and still more preferably 6 to 12% by mass. When the film-forming solution does not contain hydrophilic inorganic particles, the content of organic polymers in the film-forming solution is preferably 2 to 30% by mass, more preferably 4 to 30% by mass, even more preferably 6 to 25% by mass, and still more preferably 8 to 20% by mass.

[0050] - Hydrophilic inorganic particles - Hydrophilic inorganic particles are particles that exist dispersed in the film-forming solution without dissolving, but in this invention, such a dispersion state is also referred to as the film-forming solution. In other words, the "solution" in the film-forming solution refers to the state in which the organic polymer is dissolved in the solvent. When the above film-forming solution contains hydrophilic inorganic particles, the content of hydrophilic inorganic particles in the film-forming solution is preferably 10 to 85% by mass, more preferably 15 to 80% by mass, even more preferably 20 to 70% by mass, and particularly preferably 25 to 60% by mass.

[0051] - Other Components - The above film-forming solution may contain components other than those described above (solvent, organic polymer, and hydrophilic inorganic particles). For example, in order to control pore formation in wet phase separation, it may contain polyethylene glycol, polyethylene oxide, polypropylene glycol, ethylene glycol, tripropylene glycol, glycerol, polyhydric alcohol, dibutyl phthalate, diethyl phthalate, diundecyl phthalate, isononanoic acid, neodecanoic acid, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl acetate, polyethyleneimine, polyacrylic acid, methylcellulose, dextran, calcium chloride, magnesium chloride, and lithium chloride. If the above film-forming solution contains other components and hydrophilic inorganic particles, the total content of the other components in the above film-forming solution is preferably 0.1 to 15% by mass, more preferably 0.2 to 10% by mass, and even more preferably 0.5 to 5% by mass. If the above film-forming solution contains other components and does not contain hydrophilic inorganic particles, the total content of the other components in the above film-forming solution is preferably 1 to 25% by mass, more preferably 5 to 25% by mass, and even more preferably 7 to 20% by mass.

[0052] <Formation of porous material by wet phase separation> (Water vapor induced phase separation) In a preferred method for manufacturing the separator of the present invention, water vapor induced phase separation may be performed on the coated surface (hereinafter also simply referred to as "the coated surface of the laminate") of a laminate comprising a film-forming support, a coating film containing the constituent materials of the separator of the present invention formed on the film-forming support, and a woven fabric impregnated in the coating film. The laminate can be formed, for example, by casting a film-forming solution obtained by dissolving the organic polymer onto a film-forming support, immersing a woven fabric in the film obtained by casting, impregnating the woven fabric with the film-forming solution, and appropriately drying the surface to form a coating film.

[0053] In water vapor induction phase separation, it is preferable to use high-temperature, high-humidity water vapor as the poor solvent vapor in the water vapor induction phase separation. The relative humidity in the region where water vapor induction phase separation is performed can be, for example, 50 to 99%, more preferably 60 to 99%, and even more preferably 70 to 99%. The temperature in the region where water vapor induction phase separation is performed is, for example, preferably 55 to 85°C, more preferably 60 to 80°C, and even more preferably 60 to 75°C. The time for performing water vapor induction phase separation is, for example, preferably 1 to 35 seconds, more preferably 1 to 30 seconds, and even more preferably 1 to 25 seconds. The space in which water vapor induction phase separation is performed is not particularly limited in terms of specific adjustment methods, equipment, etc., as long as it can be a space in which the predetermined temperature and humidity are maintained. It is preferable that the space is provided so as to be continuous with the solidification bath in which liquid induction phase separation is performed after water vapor induction phase separation.

[0054] (Liquid Induction Phase Separation) In a preferred method for manufacturing the separator of the present invention, the separator of the present invention can be manufactured by impregnating the laminate that has undergone the above-mentioned water vapor induction phase separation into a solidification bath with the film-forming support still attached, or with the film-forming support removed, and performing liquid induction phase separation. Alternatively, the separator of the present invention can be manufactured by impregnating the laminate described in the above-mentioned water vapor induction phase separation (the laminate before the above-mentioned water vapor induction phase separation) into a solidification bath with the film-forming support still attached, or with the film-forming support removed, and performing liquid induction phase separation. For liquid induction phase separation, the laminate that has undergone the above-mentioned water vapor induction phase separation, or the laminate described in the above-mentioned water vapor induction phase separation, is immersed in a solvent (poor solvent, solidification bath) that does not dissolve the organic polymer and is miscible with the above-mentioned good solvent. This immersion further reduces the proportion of good solvent in the coating film of the film-forming solution, causing the organic polymer and solvent to undergo phase separation (liquid-induced phase separation), resulting in gelation (coagulation) of the organic polymer, forming a porous material, and thus obtaining the separator of the present invention.

[0055] As a poor solvent, for example, water, or a mixed solvent of water and a hydrophilic organic solvent (an organic solvent miscible with water) or a water-soluble polymer can be used. Examples of hydrophilic organic solvents include aprotic solvents such as N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and dimethylacetamide (DMAC), and alcoholic solvents such as ethanol, propanol, or isopropanol. Examples of water-soluble polymers include water-soluble polymers such as polyvinylpyrrolidone (PVP) or polyvinyl alcohol (PVA). Among the above, water is preferred as the poor solvent.

[0056] The temperature of the solidification bath is preferably 5 to 90°C, more preferably 20 to 90°C, and even more preferably 40 to 70°C. The duration of the solidification bath is preferably 1 to 15 minutes, more preferably 1 to 12 minutes, and even more preferably 3 to 10 minutes, from the viewpoint of controlling the pore size of the coating film on the film-forming support side.

[0057] In the above liquid derivative phase separation, after immersing the membrane in the poor solvent to form a porous material (separator), immersion in glycols such as ethylene glycol and diethylene glycol, and water, or washing with the glycols and water may be performed. This step can remove any remaining solvent in the membrane.

[0058] In the separator obtained by the above-described method for manufacturing separators, a certain amount of good solvent from the film-forming solution used in its manufacture inevitably remains. As a result, a separator is provided in which the total content of good solvent in the porous material is 0.01 to 5.00% by mass. In addition, a certain amount of other components described in the above-described film-forming solution may remain in the porous material. For example, a separator is provided in which the total amount of other components remaining in the porous material is, for example, 0.01 to 10% by mass. The amount of residual solvent and the amount of residual other components are determined by gas chromatography or after pre-drying the separator at 40°C for 12 hours. １ The amount can be quantified as a mass percentage of 100% by mass of the dried separator using 1H-NMR (nuclear magnetic resonance) measurement.

[0059] [Alkaline Water Electrolysis] The separator of the present invention is used in alkaline water electrolysis by being placed between the cathode and the anode. Preferred embodiments of an alkaline water electrolysis apparatus to which the separator of the present invention is applied (also referred to as "the alkaline water electrolysis apparatus of the present invention") will be described, but the alkaline water electrolysis of the present invention is not limited to these embodiments.

[0060] Figure 2 schematically shows a preferred embodiment of the alkaline water electrolysis apparatus of the present invention. In the alkaline water electrolysis apparatus (10) shown in Figure 2, a cathode electrode (12) is arranged on one side of the separator (11) of the present invention, and an anode electrode (13) is arranged on the other side. The separator (11) and each electrode (12, 13) are immersed in a high-concentration alkaline aqueous solution (14, preferably a potassium hydroxide aqueous solution or a sodium hydroxide aqueous solution). When an electric current flows between the electrodes, electrons are supplied to the cathode side, and bubble-like hydrogen (H) is produced from the water. ２ ) occurs (2H ２ O + 2e － →H ２+2OH － ). Along with the generation of hydrogen, a hydroxyl ion (OH) is produced. － ) passes through the separator (11) and moves to the anode side, where electrons are removed and bubble-shaped oxygen (O ２ ) occurs (4OH － →O ２ +2H ２ O+4e － ). The cathode electrode (12) and anode electrode (13) described above are preferably composed of an electrode substrate (conductive material) and a catalyst layer on the electrode substrate. When a catalyst layer is included, the catalyst species may be the same or different between the cathode electrode (12) and the anode electrode (13). In the alkaline water electrolysis apparatus (10) shown in Figure 2, the separator (11) and each electrode (12, 13) are far apart, so the distance traveled by hydroxyl ions is long, which limits the improvement of ion conduction efficiency.

[0061] Figure 3 schematically shows another preferred embodiment of the alkaline water electrolysis apparatus of the present invention. The alkaline water electrolysis apparatus (20) shown in Figure 3 is a zero-gap type in which the separator (11) and each electrode (12, 13) are arranged in contact with each other in the alkaline water electrolysis apparatus (10) shown in Figure 2. Because the separator (11) and each electrode (12, 13) are in contact in the alkaline water electrolysis apparatus (20) shown in Figure 3, the distance traveled by hydroxyl ions is short, which is advantageous in terms of ion conduction efficiency. In addition, from the viewpoint of imparting suitability for renewable energy, pressurized alkaline water electrolysis apparatuses that are operated under a pressure of 10 bar or more relative to atmospheric pressure (approximately 1 bar) are also known. As an example of such a pressurized alkaline water electrolysis apparatus, an example is the alkaline water electrolysis apparatus shown in Figure 3, in which the configuration, components, etc. of the alkaline water electrolysis apparatus have been appropriately adjusted to accommodate pressurized operation (for example, operation under pressurized conditions of 10 bar or more).

[0062] Figure 4 schematically shows yet another preferred embodiment of the alkaline water electrolysis apparatus of the present invention. The alkaline water electrolysis apparatus (30) shown in Figure 4 includes a membrane electrode assembly. That is, a cathode catalyst layer (32) is arranged on one side of the separator (31) of the present invention, and an anode catalyst layer (33) is arranged on the other side. These catalyst layers are composed of a catalyst and its binder. Furthermore, a gas diffusion layer (34) is formed on the outer surface of these catalyst layers (the surface opposite to the side on which the separator (33) is arranged) to constitute a membrane electrode assembly. In Figure 4, a bipolar plate (35) is formed further outside the membrane electrode assembly. When an alkaline aqueous solution is supplied to the cathode catalyst layer (32) and the anode catalyst layer (33) of this membrane electrode assembly, and the cathode catalyst layer (32) and the anode catalyst layer (33) are electrically connected and current is passed, bubble-like hydrogen is generated from the cathode catalyst layer (32) and bubble-like oxygen is generated from the anode catalyst layer (33).

[0063] In the above-described alkaline water electrolysis apparatus, the components other than the separator, such as the cathode electrode, cathode catalyst layer, anode electrode, and anode catalyst layer, are not particularly limited, and ordinary components used in alkaline water electrolysis apparatuses can be appropriately applied.

[0064] Thus, in one embodiment, the present invention provides an alkaline water electrolysis apparatus in which the separator of the present invention is incorporated as a separator in the alkaline water electrolysis apparatus. Furthermore, in one embodiment, the present invention provides a method for manufacturing an alkaline water electrolysis apparatus, which includes incorporating the separator of the present invention as a separator in the alkaline water electrolysis apparatus.

[0065] [Alkaline Water Electrolysis Member] The alkaline water electrolysis member of the present invention includes the separator of the present invention. Specifically, the alkaline water electrolysis member of the present invention includes the separator of the present invention and at least one of a catalyst, an anode electrode, and a cathode electrode. The form including the separator of the present invention, an anode electrode, and a cathode electrode will be classified as the alkaline water electrolysis cell of the present invention, as described later. Forms in which the alkaline water electrolysis member of the present invention does not include an electrode but includes a catalyst include a form in which the catalyst is located on only one side of the separator of the present invention, and a form in which the catalyst is located on both sides of the separator of the present invention. Forms in which the alkaline water electrolysis member of the present invention does not include a cathode electrode but includes an anode electrode include a form in which the anode electrode is located on one side of the separator of the present invention. In this form, the catalyst may or may not be present. If a catalyst is present, the catalyst may be located on only one side of the separator of the present invention, or the catalyst may be located on both sides of the separator of the present invention. In the present invention, an alkaline water electrolytic member does not include an anode electrode but includes a cathode electrode. This configuration includes having a cathode electrode on one side of the separator. In this configuration, a catalyst may or may not be present. If a catalyst is present, the catalyst may be present on only one side of the separator, or on both sides of the separator.

[0066] [Alkaline Water Electrolysis Cell] The alkaline water electrolysis cell of the present invention includes the separator of the present invention or the alkaline water electrolysis component of the present invention. The "alkaline water electrolysis cell" includes the separator and two electrodes separated by the separator (anode electrode and cathode electrode). In this embodiment, an alkaline aqueous solution may be present as an electrolyte between both electrodes (including the separator of the present invention), and the anode electrode and cathode electrode may each further contain a catalyst. For example, if the alkaline water electrolysis cell of the present invention includes the separator of the present invention, the alkaline water electrolysis cell of the present invention can be made by combining the separator of the present invention with the anode electrode and cathode electrode. In this case, the anode electrode and cathode electrode may each independently contain a catalyst. Also, if the alkaline water electrolysis cell of the present invention does not include electrodes and includes the separator and catalyst of the present invention, the alkaline water electrolysis cell of the present invention can be made by combining them with the anode electrode and cathode electrode. In this case, the catalyst may be included in the alkaline water electrolytic member of the present invention, or it may be included separately in combination with the alkaline water electrolytic member of the present invention, similar to the anode electrode or cathode electrode. In the alkaline water electrolytic cell of the present invention, the catalyst may be included on at least one side of the separator of the present invention, or it may be included on both sides. Furthermore, if the alkaline water electrolytic cell of the present invention does not include a cathode electrode but includes the separator and anode electrode of the present invention, it can be made into the alkaline water electrolytic cell of the present invention by combining it with a cathode electrode. In this case, the anode electrode and cathode electrode may each independently contain the catalyst. Furthermore, the catalyst may be included in the alkaline water electrolytic member of the present invention, or it may be included separately in combination with the alkaline water electrolytic member of the present invention, similar to the cathode electrode. Furthermore, if the alkaline water electrolytic cell of the present invention does not include an anode electrode but includes the separator and cathode electrode of the present invention, it can be made into the alkaline water electrolytic cell of the present invention by combining it with an anode electrode. In this case, the anode electrode and cathode electrode may each independently contain the catalyst.Furthermore, the catalyst may be included in the alkaline water electrolytic member of the present invention, or it may be included separately in combination with the alkaline water electrolytic member of the present invention, similar to the anode electrode.

[0067] [Alkaline Water Electrolysis Apparatus] The alkaline water electrolysis apparatus of the present invention includes the alkaline water electrolysis cell of the present invention. The alkaline water electrolysis apparatus of the present invention can produce hydrogen as described above by supplementing necessary components, components, etc., according to the configuration of the alkaline water electrolysis cell of the present invention.

[0068] [Method for Producing Hydrogen] The method for producing hydrogen according to the present invention is the same as a conventional method for producing hydrogen (water electrolysis), except that it includes electrolysis of water using the alkaline water electrolysis apparatus of the present invention. In particular, a preferred method for producing hydrogen according to the present invention is one which includes using an alkaline aqueous solution containing 10 to 35% by mass of a metal hydroxide as the electrolyte solution and electrolyzing water at 70 to 95°C. Examples of metal hydroxides include sodium hydroxide and potassium hydroxide, and potassium hydroxide is preferred from the viewpoint of having a higher specific conductivity of the aqueous solution of the metal hydroxide. The content of the metal hydroxide (electrolyte) in the alkaline aqueous solution is 10 to 35% by mass, preferably 25 to 35% by mass, and more preferably 28 to 32% by mass. The temperature of the alkaline aqueous solution used when operating the alkaline water electrolysis apparatus and producing hydrogen by electrolyzing water is 70 to 95°C, preferably 70 to 90°C. This temperature may also be 75 to 85°C or 78 to 82°C. Thus, the separator of the present invention can be suitably used in the method for producing hydrogen according to the present invention that uses a high-temperature, high-concentration alkaline aqueous solution.

[0069] The present invention will be described in more detail below based on examples, but the present invention is not intended to be limited thereto. The water used is deionized water. hr means time. The opening ratio and fiber diameter of the woven fabric are values ​​measured by the method described above.

[0070] (Separator preparation) 8.5 g of polysulfone (product name: Udel P-3500 LCD MB7, Mw: approximately 80,000, manufactured by Solvay) was added to 41.3 g of N-methyl-2-pyrrolidone (also known as N-methylpyrrolidone, manufactured by Merck), and stirred at 60°C for 5 hours until completely dissolved. Next, 2.4 g of PVP K90 (product name: polyvinylpyrrolidone, manufactured by Merck) was added, and stirred at 60°C for 1 hour, after which ZrO ２ 47.9 g of particles (product name: E101, manufactured by Luxfer) were added and stirred for a further 3 hours to obtain coating solution A. The obtained coating solution A was cast onto a glass plate using a 400 μm thick applicator. A woven fabric was placed on top of the cast coating solution A, and the fabric was completely impregnated with coating solution A. Subsequently, it was gently immersed in a condensation bath (pure water) cooled to 10°C to form a porous polysulfone structure (referred to as "PS porous structure") (phase separation step in the condensation bath). Further washing with water at 50°C for 10 minutes removed the woven fabric and PS porous structure from the glass plate as a single unit. Subsequently, washing with water at 90°C for 1 hour obtained separators No. 101-114 and c11-c24. The woven fabrics used are as described in Tables 1-1 to 1-3 below (hereinafter collectively referred to as "Table 1"). No. Nos. 101 to 114 are separators of the present invention, and Nos. c11 to c24 are separators for comparison.

[0071] (Physical properties of the porous structure) Using coating solution A used in the preparation of the separator described above, a 200 μm thick sample for physical property measurement (a porous membrane sample that does not contain woven fabric) was prepared, and the ion resistance and water permeability were measured as described below. The result showed that the ion resistance was 0.05 Ω·cm. ２ The permeability is 500 L / (bar·m). ２The result was hr). The above-mentioned 200 μm thick sample for physical property measurement was prepared as follows: The coating solution A prepared above was cast onto a PET (polyethylene terephthalate) substrate using a 400 μm thick applicator. Subsequently, it was gently immersed in a condensation bath (pure water) cooled to 10°C to form a porous polysulfone structure (phase separation step in the condensation bath). Further, it was washed with water at 50°C for 10 minutes and peeled off from the PET substrate. Subsequently, it was washed with water at 90°C for 1 hour to prepare a 200 μm thick sample for physical property measurement.

[0072] [Evaluation of Separators] The following measurements and evaluations were performed on each separator fabricated as described above. The results are shown in Table 1. Unless otherwise specified, the separators used for each evaluation were those that had been cut to the desired shape for the evaluation described later.

[0073] (Film Thickness) A cross-section cut from the separator with a razor blade was scanned using a cross-sectional SEM (scanning electron microscope) at a magnification (e.g., 200x) that allowed the entire separator cross-section to fit in a single field of view. Assuming that no pores exist in the obtained cross-sectional SEM image (assuming that the pores are filled with organic polymer), the film thickness was measured at 20 equally spaced points. The arithmetic mean of the 20 measurements was calculated and rounded to the first decimal place in μm, and this value was defined as the film thickness of the separator. The following equipment was used for cross-sectional SEM observation: Conductive processing device: Meiwa Forsis Co., Ltd., Model: HPC-1SW osmium coater / Source: Os / Film thickness: 5 nm CIS device: JEOL Ltd., Model: IB-09060CIS / Acceleration voltage: 4 kV / Processing temperature: -130°C / As a pretreatment, the sample cut with a razor blade was attached to a Si wafer (100 μm thick) with epoxy resin and fixed in place. FE-SEM (Field Emission Scanning Electron Microscope) observation system: Carl Zeiss, model: Ultra5, measurement conditions: secondary / backscattered electron image, acceleration voltage 2kV, aperture 30μm, working distance 3.0mm (cross-section)

[0074] (Ionic Resistance) A two-chamber cell, having nickel electrodes at the current control terminal and a Lugin tube filled with 3M-KCl at the voltage control terminal, was subjected to a 30% potassium hydroxide aqueous solution as the electrolyte, and maintained at 30°C. In galvanostat mode, the current density was 10 mA / cm². ２ The ion resistance was measured under the conditions described above to obtain a blank value for measurement. Next, each separator prepared above was punched out into a circular shape with a diameter of 10 mm, and a 30% potassium hydroxide aqueous solution was filled in the same way as the blank value measurement, and the ion resistance was measured under the same conditions as the blank value measurement. The difference between the resistance value of each separator obtained and the blank value (i.e., the value calculated by [separator resistance value] - [blank value]) was taken as the ion resistance value of that separator, and the ion resistance was evaluated according to the following evaluation criteria. - Evaluation Criteria - A: Ion resistance value of 0.05 Ω・cm ２ It is less than . B: Ionic resistance is 0.05 Ω·cm ２ 0.06Ω・cm or more ２ It is less than . C: Ionic resistance is 0.06 Ω·cm ２ 0.07Ω・cm or more ２ It is less than . D: Ionic resistance is 0.07 Ω·cm ２ 0.08Ω・cm or more ２ It is less than . E: Ionic resistance is 0.08 Ω·cm ２ That's all.

[0075] (Durability: Evaluated by the rate of increase in water permeability in durability tests) First, the sample was immersed in a 30% by mass KOH aqueous solution at 120°C, and the pressure was increased to 35 bar. ２A durability test was conducted by leaving the sample standing for two months under bubbling conditions, and a sample was obtained after the durability test. Each sample, both before and after the durability test, was cut into a circular shape with a diameter of 47 mm and set in the alkaline water permeability measuring device as shown in the schematic cross-sectional view in Figure 5. Specifically, the stainless steel mesh support 5 and the sample 4 (sample before or after the durability test) were placed on the lower part 2 of the sample holder in this order, and the upper part 1 of the sample holder was placed on top of the rubber O-ring packing 3, with the lower part 2 and upper part 1 of the sample holder securing the sample 4. A 30% by mass potassium hydroxide aqueous solution heated to 85°C was supplied from above the sample (indicated by the arrow in Figure 5), and a pressure of 50 mbar was applied. The point at which droplets were visually confirmed to be coming out from the bottom of the sample was defined as 0 minutes, and the pressure was maintained for 8 minutes. The amount of 30% by mass potassium hydroxide aqueous solution that permeated the sample (dropped from the bottom of the sample) in 8 minutes was quantified, and the permeability (W) of the sample before the durability test was determined by unit conversion. Ｂ ) and the water permeability (W) of the sample after the durability test. Ａ The values ​​were calculated for each of the following: The unit of permeability is L / (bar·m). ２ ・hr) is the rate of increase in water permeability due to durability testing (i.e., {(W Ａ -W Ｂ ) / W Ｂ Durability was evaluated by applying the following evaluation criteria to the value of} × 100%). - Evaluation Criteria - S: The increase rate of water permeability due to the durability test is less than 10%. A: The increase rate of water permeability due to the durability test is 10% or more and less than 50%. B: The increase rate of water permeability due to the durability test is 50% or more and less than 100%. C: The increase rate of water permeability due to the durability test is 100% or more and less than 200%. D: The increase rate of water permeability due to the durability test is 200% or more.

[0076]

[0077] (Woven Fabric) PPS-1: Manufactured by NBC Meshtec, PPSP225 (product name) PPS-2: Manufactured by Kureba, PPS mesh described as having a thread diameter of 34 and a mesh opening ratio of 57.1 on Kureba's product website https: / / www.nippon-clever.co.jp / item / resin-mesh / pps-mesh PPS-3: Manufactured by NBC Meshtec, PPS119 / 60 (product name) PPS-4: Manufactured by NBC Meshtec, PPS177 / 70 (product name) PPS-5: Manufactured by Kureba, PPS mesh described as having a thread diameter of 55 and a mesh opening ratio of 62 on Kureba's product website https: / / www.nippon-clever.co.jp / item / resin-mesh / pps-mesh PPS-6: NBC Meshtec Co., Ltd., PPSP150 (product name) PPS-7: NBC Meshtec Co., Ltd., PPSP60 (product name) PPS-8: NBC Meshtec Co., Ltd., LCP145 / 74 (product name) PEEK-1: Kureba Co., Ltd. PEEK mesh described on Kureba's product website https: / / www.nippon-clever.co.jp / item / resin-mesh / peek-mesh as having a thread diameter of 71 and a mesh opening ratio of 56.

[0078] The polymer refers to the type of polymer that makes up the fabric; PPS indicates polyphenylene sulfide, and PEEK indicates polyether ether ketone. The fiber diameter refers to the diameter of the fibers that make up the fabric, and the unit is μm. The opening ratio is the value calculated by the measurement and calculation method described above, and the unit is %. The separator film thickness is the value measured and calculated by the method described above, and the unit is μm.

[0079] From Table 1 above, the following can be seen: Separators No. c13, c17, c19, and c21 are not separators of the present invention, at least in that their separator film thickness is less than 100 μm. These separators No. c13, c17, c19, and c21 were inferior, with a large increase in water permeability of 200% or more when exposed to high temperature and high concentration alkaline conditions, regardless of whether the opening ratio of the woven fabric was within the range defined in the present invention. Separator No. c12 is not a separator of the present invention because its separator film thickness is thick at 500 μm. This separator No. c12 has an ion resistance of 0.08 Ω·cm. ２ The above values ​​were high and inferior. Furthermore, separator No. c16 is not a separator of the present invention because its film thickness exceeds 250 μm and its aperture ratio is less than 45.0%. This separator No. c16 has an ion resistance of 0.08 Ω·cm. ２ The permeability was significantly higher than the stated value, and the increase in permeability when exposed to high temperature and high concentration alkaline conditions was over 100%, indicating inferiority. Separator No. c24 is not a separator of the present invention because its film thickness exceeds 250 μm and its aperture ratio exceeds 72.0%. Separator No. c24 was inferior because its increase in permeability when exposed to high temperature and high concentration alkaline conditions was over 100%. Separators No. c18 and c20 are not separators of the present invention because their film thickness exceeds 250 μm. These separators No. c18 and c20 have an ion resistance of 0.08 Ω·cm. ２ The above results were high and inferior. Separators No. c11, c14, and c15 are not separators of the present invention because, although the separator film thickness is within the range of 100 to 250 μm specified in the present invention, the opening ratio of the woven fabric is less than 45.0%. These separators No. c11, c14, and c15 are inferior because the increase in water permeability when exposed to high temperature and high concentration alkaline conditions is at least 100% or more, and separators No. c11 and c15 have an ion resistance value of 0.08 Ω・cm ２Even in the above-mentioned high points, they were inferior. Furthermore, separators No. c22 and c23, although the separator film thickness is within the range of 100 to 250 μm specified in the present invention, are not separators of the present invention because the opening ratio of the woven fabric exceeds 72.0%. These separators No. c22 and c23 were inferior because the increase in water permeability when exposed to high temperature and high concentration alkaline conditions was large, exceeding 100%. Also, considering from the viewpoint of opening ratio, separators No. c11, c13 to c16 are not separators of the present invention because the opening ratio of the woven fabric is less than 45.0%. Although the ion resistance of these separators No. c11, c13 to c16 can be suppressed to the desired level by thinning the separator film thickness, they were inferior because the increase in water permeability when exposed to high temperature and high concentration alkaline conditions was large, exceeding 100%, regardless of the separator film thickness. Separators c21 to c24 are not the separators of the present invention because the opening ratio of the woven fabric exceeds 72.0%. Although the ion resistance of these separators No. c21 to c24 can be suppressed to a desired level by reducing the thickness of the separator film, regardless of the thickness of the separator film, the increase in water permeability when exposed to high temperature and high concentration alkaline conditions is large, exceeding 100%, and they are inferior. In contrast, separators No. 101 to 114 that satisfy the provisions of the present invention all have ion resistance suppressed to a desired level, and the increase in liquid permeability is also suppressed when exposed to high temperature and high concentration alkaline conditions. Furthermore, separators No. 101 to 114 have a thickness of 110 to 200 μm and an opening ratio of 50.0 to 65.0%. In separators 105, 108, 113, and 114, ion resistance was suppressed to a lower level, and the increase in liquid permeability under high temperature and high concentration alkaline conditions was also more suppressed (ion resistance rated "B" or higher, and durability rated "A" or higher). Furthermore, when the diameter of the fibers constituting the woven fabric is 60 μm or less, a comparison between separator No. 114 and separator No. 105 shows that the increase in liquid permeability under high temperature and high concentration alkaline conditions can be further suppressed while suppressing ion resistance to the desired level.Specifically, while separator No. 114, with a fiber diameter of 71 μm, received a durability rating of "A," separator No. 105, which had the same opening ratio of the woven fabric and the same separator film thickness as separator No. 114, but with a fiber diameter of 34 μm, received a durability rating of "S," indicating superior durability. A similar trend was observed in separators No. 101-104 and 106-113, where exceeding a fiber diameter of 60 μm in the woven fabric resulted in inferior durability (suppression of increased liquid permeability under high temperature and high concentration alkaline conditions) for each separator. Furthermore, in the case of No. 105 and No. 114, the polymer constituting the woven fabric has a similar affinity to PS constituting the porous material other than the woven fabric, and is composed of PPS or PEEK, which exhibits similarly excellent alkali durability. The type of polymer constituting the fabric had little influence on the evaluation result of 114, and it is thought that the difference in evaluation was due to the difference in the diameter of the fibers constituting the fabric.

[0080] Although we have described the present invention along with its embodiments, we do not intend to limit our invention in any detail of the description unless specifically designated, and we believe that it should be interpreted broadly without contradicting the spirit and scope of the invention as set forth in the appended claims.

[0081] This application claims priority based on Japanese Patent Application No. 2024-227684, filed in Japan on 24 December 2024, the contents of which are incorporated herein by reference as part of this specification.

[0082] 1. Sample holder top 2. Sample holder bottom 3. Rubber O-ring packing 4. Sample 5. Stainless steel mesh support 10. Alkaline water electrolysis device 11. Separator 12. Cathode electrode 13. Anode electrode 14. High-concentration alkaline aqueous solution 20. Alkaline water electrolysis device 30. Alkaline water electrolysis device 31. Separator 32. Cathode catalyst layer 33. Anode catalyst layer 34. Gas diffusion layer 35. Bipolar plate O ２ Bubble-shaped oxygen H ２Bubble-shaped hydrogen OH － Hydroxy ion e － Electron D: Wire diameter (diameter of the fiber) OP: Aperture distance (distance between one fiber and the adjacent fiber) OPA: Aperture S ＭＣ Area of ​​one mesh (s) ＯＰＡ Opening area WA Warp WE Weft

Claims

1. An alkaline water electrolysis separator comprising a woven fabric and a porous material other than the woven fabric, wherein the film thickness of the alkaline water electrolysis separator is 100 to 250 μm, and the opening ratio of the woven fabric is 45.0 to 72.0%.

2. The separator for alkaline water electrolysis according to claim 1, wherein the film thickness of the separator is 110 to 200 μm and the opening ratio of the woven fabric is 50.0 to 65.0%.

3. The alkaline water electrolysis separator according to claim 1, wherein the diameter of the fibers constituting the woven fabric is 20 to 60 μm.

4. The alkaline water electrolysis separator according to claim 1, wherein the polymer constituting the woven fabric comprises at least one of polyphenylene sulfide and polyether ether ketone.

5. The alkaline water electrolysis separator according to claim 1, wherein the porous material other than the woven fabric contains an organic polymer.

6. The alkaline water electrolysis separator according to claim 1, wherein the alkaline water electrolysis separator is a structure in which the woven fabric is enclosed within a porous material other than the woven fabric.

7. An alkaline water electrolysis component comprising the alkaline water electrolysis separator described in claim 1.

8. An alkaline water electrolysis cell comprising an alkaline water electrolysis separator according to any one of claims 1 to 6, or an alkaline water electrolysis component according to claim 7.

9. An alkaline water electrolysis apparatus comprising the alkaline water electrolysis cell described in claim 8.

10. A method for producing hydrogen, comprising electrolyzing water using the alkaline water electrolysis apparatus described in claim 9.

11. A method for producing hydrogen according to claim 10, comprising using an alkaline aqueous solution containing 10 to 35% by mass of a metal hydroxide as an electrolyte solution, and electrolyzing water at 70 to 95°C.

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