JP7273650B2 - Diaphragm for alkaline water electrolysis and method for producing the diaphragm - Google Patents

Description

TECHNICAL FIELD The present invention relates to a diaphragm for alkaline water electrolysis and a method for producing the diaphragm.

Electrolysis of water is known as one of the industrial production methods of hydrogen gas, which has been attracting attention as an energy source in recent years. Electrolysis of water is generally performed by applying a direct current to water to which sodium hydroxide, potassium hydroxide, or the like has been added as an electrolyte in order to increase conductivity. For such electrolysis of water, an electrolytic cell having an anode compartment and a cathode compartment separated by a diaphragm is used.

Electrolysis of water is performed by the transfer of electrons (or ions). Therefore, in order to perform electrolysis efficiently, the diaphragm is required to have high ion permeability. In addition, it is required to have gas barrier properties capable of blocking oxygen generated in the anode chamber and hydrogen generated in the cathode chamber. The electrolysis of water uses a highly concentrated alkaline aqueous solution of about 30% and is carried out at about 80 to 90°C. Therefore, a diaphragm for alkaline water electrolysis used for electrolysis of water is required to have high temperature resistance and alkali resistance. In addition, as a diaphragm for alkaline water electrolysis, there has been a demand for a diaphragm that achieves both higher membrane strength, higher ion conductivity, fewer defects due to macrovoids, and higher yield.

Various porous membranes produced by non-solvent induced phase separation (NIPS) have been proposed as diaphragms for alkaline water electrolysis.
Regarding film formation by a non-solvent-induced phase separation method, Non-Patent Document 1 describes the effect of adding an additive such as lithium chloride to a casting solution in the production of a polyvinylidene fluoride film by a non-solvent-induced phase separation method. It is described that the exchange of solvent and non-solvent during NIPS is controlled by suppressing the thermodynamic miscibility of .
However, in the diaphragm for alkaline water electrolysis in which a resin having alkali resistance and heat resistance and inorganic particles are used in combination, there has been little knowledge about the above additives.

Desalination 192 (2006) 190-197

An object of the present invention is to provide a diaphragm for alkaline water electrolysis that achieves both higher membrane strength, higher ion conductivity, and better yield, and a method for producing the diaphragm.

The present inventors have found that by adding lithium chloride to a diaphragm for alkaline water electrolysis containing an organic polymer and inorganic particles, the formation of macrovoids inside the membrane is suppressed, and the membrane strength and ionic conductivity are excellent. The inventors have found that it is possible to provide a diaphragm for alkaline water electrolysis which has a membrane structure and achieves both higher membrane strength, higher ion conductivity, and higher yield, and has completed the present invention.

That is, the diaphragm for alkaline water electrolysis of the present invention is a diaphragm for alkaline water electrolysis containing an organic polymer and inorganic particles; In a range separated by 0.4a or more with respect to the cross-sectional width a; the sum of the areas of macrovoids with a pore diameter of 10 μm or more with respect to the total area S _A from one surface of the membrane to the other surface S _MACRO ratio S _MACRO / _SA is 25% or less; only the total area _SR of the organic polymer and the contour line of the organic polymer in the range between the position 10 μm away from the surface of the film and the position 20 μm away in the depth direction The sum of the areas of the resin internal pores with a pore diameter of 0.08 μm to 1.20 μm S _MICRO and the sum of the areas of the resin internal pores S _R + _{S MICRO} The ratio S _MICRO /(S _R +S _MICRO ) is 5% or more. It is preferable that the inorganic particles are contained in an amount of 150% by volume or more with respect to the organic polymer.

Further, the method for producing a diaphragm for alkaline water electrolysis of the present invention includes a resin mixture preparation step of mixing an organic polymer resin (R), inorganic particles, and lithium chloride with a solvent to prepare a resin mixture; A film forming step of forming a film using the resin mixed solution is included.

INDUSTRIAL APPLICABILITY According to the present invention, a diaphragm for alkaline water electrolysis that achieves both higher membrane strength, higher ion conductivity and higher yield, and a method for producing the diaphragm can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically one form of the cross section of the diaphragm for alkaline water electrolysis of this invention. In the cross section perpendicular to the surface of the diaphragm for alkaline water electrolysis of the present invention, from both ends in the longitudinal direction toward the center, in a range separated by 0.4 a or more with respect to the width a of the cross section, from the surface of the membrane in the depth direction FIG. 10 is a diagram schematically showing a range between positions separated by 10 μm and positions separated by 20 μm. FIG. 4 is a diagram schematically showing pores closed only by outlines of the organic polymer in the diaphragm for alkaline water electrolysis of the present invention.

The present invention will be described in detail below. A combination of two or more of the individual preferred embodiments of the invention described below is also a preferred embodiment of the invention. Further, in this specification, the description of "A to B" means "A or more and B or less".

1. Diaphragm for alkaline water electrolysis The diaphragm for alkaline water electrolysis of the present invention is a diaphragm for alkaline water electrolysis containing an organic polymer and inorganic particles; and in a range separated by 0.4a or more with respect to the width _a of the cross section _; ratio S _MACRO /S _A is 25% _or less; The sum of the areas of the resin internal pores that _are pores closed only by the contour lines and have a pore diameter of 0.08 μm to _1.20 μm. The sum of the areas of the resin internal _pores . The S _MICRO ratio S _MICRO /( _SR + S _MICRO ) is 5% or more.

1-1 Organic Polymer The diaphragm for alkaline water electrolysis of the present invention contains an organic polymer. The organic polymer holds the inorganic particles. The organic polymer functions as a partition that holds the inorganic particles, and can suppress the inorganic particles from falling off from the partition in an alkaline solution while minimizing the decrease in the hydrophilic surface of the inorganic particles, which will be described later.

As the organic polymer, an organic polymer resin (R) capable of retaining inorganic particles, preferably without swelling in an alkaline solution, and exhibiting the effects of the present invention [hereinafter sometimes simply referred to as resin (R)]. is not particularly limited. Examples of the resin (R) include fluorine-based resins such as polyvinylidene fluoride and polytetrafluoroethylene; olefin-based resins such as polypropylene; and aromatic hydrocarbon-based resins such as polysulfone and polystyrene. These may be used individually by 1 type, and may be used in combination of 2 or more type. Among them, aromatic hydrocarbon-based resins are preferable in that they can be used as a diaphragm for alkaline water electrolysis with further excellent heat resistance and alkali resistance.

More specifically, the aromatic hydrocarbon resins include, for example, polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, polystyrene, polysulfone, polyethersulfone, polyarylene sulfide resins such as polyphenylene sulfide, and polyphenylsulfone. , polyarylate, polyetherimide, polyimide, polyamideimide, and the like. Among them, at least one selected from the group consisting of polysulfone, polyethersulfone, and polyphenylsulfone is preferable in terms of being able to impart even better alkali resistance. Ethersulfone is more preferred.

By using at least one selected from the group consisting of polysulfone, polyethersulfone, and polyphenylsulfone, for example, when producing a diaphragm using a non-solvent-induced phase separation method or a vapor-induced phase separation method, When the sulfonyl group has an appropriate affinity with the inorganic particles described later, it becomes easy to adjust the phase separation conditions. In addition, since the alkali resistance is further increased, the stability of dimensions, mass and resistance value when used in an alkaline solution for a long time and the effect of suppressing the generation of new voids are excellent.

The content of the resin (R) is preferably 3 to 40% by mass based on 100% by mass of the diaphragm for alkaline water electrolysis. When the content of the resin (R) is within the above range, the ion permeability and toughness of the diaphragm for alkaline water electrolysis are good, but inorganic components are not eluted from the diaphragm for alkaline water electrolysis in an alkaline solution. It is even more suppressed. In addition, the diaphragm for alkaline water electrolysis exhibits high ion conductivity and is also excellent in ion permeability, gas barrier properties, heat resistance, and alkali resistance. The content of the resin (R) is more preferably 5 to 35% by mass, still more preferably 7 to 30% by mass, based on 100% by mass of the diaphragm for alkaline water electrolysis.

The content of the resin (R) is preferably 5 to 40% by mass based on 100% by mass of the diaphragm for alkaline water electrolysis when the diaphragm for alkaline water electrolysis of the present invention does not contain a porous support, which will be described later. , more preferably 10 to 35% by mass, more preferably 10 to 25% by mass. When the diaphragm for alkaline water electrolysis of the present invention contains a porous support described later as an organic polymer, the content of the resin (R) is preferably 3 to 20% by mass in 100% by mass of the diaphragm for alkaline water electrolysis, More preferably 5 to 18% by mass, still more preferably 7 to 15% by mass.

The diaphragm for alkaline water electrolysis of the present invention preferably contains 10 to 40 parts by mass, more preferably 12 to 35 parts by mass, more preferably 15 to 33 parts by mass of the resin (R) with respect to 100 parts by mass of the inorganic particles described later. It is more preferable to include parts by mass. When the content ratio of the inorganic particles and the resin (R) is within the range described above, the elution of inorganic components from the diaphragm for alkaline water electrolysis in an alkaline solution is further suppressed. In addition, the diaphragm for alkaline water electrolysis exhibits high ion conductivity and is also excellent in ion permeability, gas barrier properties, flexibility, heat resistance, and alkali resistance.

1-1-1 Porous Support The diaphragm for alkaline water electrolysis of the present invention comprises a membrane containing the above-described organic polymer and inorganic particles described below, and contains a porous support as the organic polymer. good too. The porous support is a porous organic polymer, and is a member that does not inhibit ion permeability and can serve as a support for a diaphragm for alkaline water electrolysis. The porous support is preferably a sheet-like member.

Examples of materials for the porous support include polyarylene sulfide resins such as polyethylene, polypropylene, polysulfone, polyethersulfone, polyphenylsulfone, and polyphenylene sulfide, and resin materials such as polyketone, polyimide, polyetherimide, and fluororesin. is mentioned. These may be used individually by 1 type, and may be used in combination of 2 or more type. Among them, it preferably contains at least one resin material selected from the group consisting of polypropylene, polyethylene, and polyphenylene sulfide in that it can exhibit excellent heat resistance and alkali resistance, and the group consisting of polypropylene and polyphenylene sulfide. More preferably, it contains at least one more selected resin material.

Examples of the form of the porous support include nonwoven fabric, woven fabric (fabric), knitted fabric, mesh, porous membrane, felt, and mixed fabric of nonwoven fabric and woven fabric. Nonwoven fabric and woven fabric are preferred. Examples include cloth, mesh, or felt, and more preferably non-woven fabric, woven fabric, and mesh.

As the porous support, nonwoven fabric, woven fabric, mesh, or felt containing at least one resin selected from the group consisting of polypropylene, polyethylene, and polyphenylene sulfide is preferred. Furthermore, non-woven fabrics, meshes, or felts containing polyphenylene sulfide are preferred as porous supports. The total content of polypropylene, polyethylene, and polyphenylene sulfide in the porous support is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

When the porous support is in the form of a sheet, the thickness of the porous support is not particularly limited as long as the diaphragm for alkaline water electrolysis of the present invention can exhibit the effects of the present invention. , more preferably 50 to 1000 μm, still more preferably 80 to 500 μm, and most preferably 80 to 250 μm.

1-2 Inorganic Particles The diaphragm for alkaline water electrolysis of the present invention contains inorganic particles. The diaphragm for alkaline water electrolysis of the present invention can exhibit ion permeability by filling the gaps between the inorganic particles or between the particles and the organic polymer with the electrolytic solution. In addition, by including inorganic particles, the diaphragm for alkaline water electrolysis becomes hydrophilic, and oxygen gas and hydrogen gas generated in the electrolysis of water can be prevented from adhering to the diaphragm and interfering with the electrolysis.

Examples of inorganic particles used in the present invention include hydroxides or oxides of magnesium, zirconium, titanium, zinc, aluminum and tantalum, sulfates of calcium, barium, lead, strontium and the like. Among them, magnesium hydroxide, zirconium hydroxide, titanium hydroxide, zirconium oxide, titanium oxide, calcium sulfate, and barium sulfate are preferable in terms of dispersibility of inorganic particles and stability in alkaline solutions. Magnesium oxide, zirconium oxide, titanium oxide and barium sulfate are more preferred. The inorganic particles may be used singly or in combination of two or more.

The inorganic particles may be natural or synthetic. In addition, the surface may be untreated, and in order to improve dispersion in the solvent, the surface is treated with a silane coupling agent, stearic acid, oleic acid, fatty acid, higher fatty acid, carboxylic acid ester, phosphate ester, etc. It may be processed. The shape of the inorganic particles is not particularly limited as long as it is particulate, and may be amorphous; spherical such as a perfect sphere or oblong sphere; plate-like such as flaky or hexagonal plate-like; or fibrous. However, it is preferably spherical, plate-shaped, or fibrous in terms of ease of dispersion in a solvent and ease of preparation of a resin composition. A plate-like shape is more preferable.

The inorganic particles preferably have an aspect ratio of 1.0 to 8.0. When the aspect ratio is within the above range, the membrane can have even better ion permeability and excellent uniformity. The aspect ratio is more preferably 1.5 to 7.0, even more preferably 2.0 to 6.0.
In the present specification, the aspect ratio means the ratio (a/b) between the longest diameter a and the shortest diameter b, and powdery inorganic particles are observed with SEM, and any 10 particles of the obtained image are In the above, using analysis software or the like, the ratio (a/b) between the longest diameter a and the shortest diameter b of each particle is measured, and the simple average value of these ratios can be obtained as the aspect ratio of the particle. .

As the maximum diameter a, for example, when the shape of the particle is plate-like, the length of the plate surface of the particle is used, and when the particle is fibrous, the length of the fiber is used. The shortest diameter among the diameters passing through the midpoint of the longest diameter a and perpendicular to the longest diameter is defined as the shortest diameter b. As the shortest diameter b, for example, when the shape of the particles is plate-like, the thickness of the particles is used, and when the shape is fibrous, the thickness of the fibers is used. As the thickness of the particles and the thickness of the fibers, the thickness and thickness at the midpoint of the longest diameter a are employed, respectively.

The average particle diameter of the inorganic particles is preferably 0.01 to 2.0 μm, more preferably 0.05 to 1.0 μm, from the viewpoint of further improving the dispersibility of the inorganic particles. It is more preferably 0.08 to 0.7 μm. The average particle size is obtained from particle size distribution measurement by a laser diffraction/scattering method using an inorganic particle dispersion liquid that has been subjected to dispersion treatment using inorganic particles and a 0.2% by mass sodium hexametaphosphate aqueous solution. Average particle size (d50). When the average particle size of the inorganic particles is within the above range, the membrane can exhibit high ion conductivity, ion permeability, and gas barrier properties.

The specific surface area of the inorganic particles is preferably from 5 to 35 m ² /g, more preferably from 5.5 to 25 m ² /g, and more preferably from 6 to 20 m ² /g, in that the ion permeability of the diaphragm is further improved. is more preferable. The above specific surface area is a specific surface area measured by the BET method using liquid nitrogen for powdery inorganic particles. Since the ion path in the diaphragm for alkaline water electrolysis is formed by the highly hydrophilic surface of the inorganic particles, the specific surface area of the inorganic particles within the above range can provide a diaphragm with even better ion permeability.

The content of the inorganic particles is preferably 30 to 95% by mass based on 100% by mass of the diaphragm for alkaline water electrolysis. When the content of the inorganic particles is within the above range, the elution of the inorganic component in the alkaline solution is further suppressed, exhibiting high ion conductivity, ion permeability, gas barrier properties, heat resistance and alkali resistance. An excellent diaphragm can be obtained. The content of the inorganic particles is more preferably 32 to 92% by mass, still more preferably 35 to 90% by mass, based on 100% by mass of the diaphragm for alkaline water electrolysis.

When the diaphragm for alkaline water electrolysis of the present invention does not contain the porous support, the content of the inorganic particles is preferably 60 to 95% by mass in 100% by mass of the diaphragm for alkaline water electrolysis, more preferably. is 65 to 92% by mass, more preferably 75 to 90% by mass.
When the diaphragm for alkaline water electrolysis of the present invention contains the porous support, the content of the inorganic particles is preferably 30 to 50% by mass, more preferably 32 to 48%, based on 100% by mass of the diaphragm for alkaline water electrolysis. % by mass, more preferably 35 to 45% by mass.
Moreover, it is preferable that the inorganic particles are contained in an amount of 150% by volume or more (that is, a volume amount of 1.5 times the volume of the organic polymer or more) with respect to the organic polymer.

FIG. 1 schematically shows one embodiment of the diaphragm for alkaline water electrolysis of the present invention. A diaphragm 1 for alkaline water electrolysis includes a single membrane layer 2 and a support layer 3 . The single layer 2 is a layer containing the resin (R) and inorganic particles, and the support layer 3 is a layer containing the resin (R), inorganic particles and a porous support.

In the diaphragm for alkaline water electrolysis of the present invention, the single membrane layer 2 may be formed on one surface of the support layer 3 or may be formed on both surfaces.
Further, the diaphragm for alkaline water electrolysis of the present invention may not have the above-described single layer 2, and a composite as a support layer 3 in which the inorganic particles, the resin (R), and the porous support are integrated. It can be a body. By forming the above composite, the strength and toughness of the diaphragm for alkaline water electrolysis can be improved.

1-3 Membrane Internal Structure The diaphragm for alkaline water electrolysis of the present invention is a diaphragm for alkaline water electrolysis containing an organic polymer and inorganic particles; The sum of the areas S of macrovoids with a pore diameter of 10 μm or more with respect to the total area S _A The ratio S _MACRO / _SA of _MACRO is 25 _% or less; The _sum of the areas of the resin internal pores that are pores closed only by the outline _of the resin _and have a pore diameter of 0.08 μm to 1.20 μm. The ratio S _MICRO /(S _R +S _MICRO ) of the sum S MICRO is 5% _or more.

In the following, the ratio S _MACRO / _{S A} of the sum of the areas of macrovoids having a pore diameter of 10 μm or more with respect to the total area S _A from one surface to the other surface of the membrane is defined as the macrovoid existence ratio. There is a case. In addition, the ratio of the sum of the areas of the internal pores of the resin S MICRO to the sum of the total area of the organic polymer _{S R} and the sum of the areas of the internal pores S _MICRO of the _resin +S _MICRO S _MICRO /(S _R +S _MICRO )” is sometimes referred to as resin internal porosity.

1-3-1 Macrovoid existence rate As described above, the macrovoid existence rate is 0.4a or more apart from the width a of the cross section toward the center from both ends in the longitudinal direction in the cross section perpendicular to the surface of the film. In the above range, S _MACRO /S _A is the ratio of the sum of the areas S _MACRO of macrovoids with a pore diameter of 10 μm or more to the total area S _A from one surface of the membrane to the other surface. The macrovoid existence rate is 25% or less, preferably 10% or less, more preferably 5% or less, and further preferably free of the macrovoids.

Specifically, the method for determining the macrovoid existence rate is as follows: "In a cross section perpendicular to the surface of the film, a range separated by 0.4 a or more with respect to the width a of the cross section from both ends in the longitudinal direction toward the center , select the measurement area. The entire thickness direction (from one surface to the other surface) of the film is a measurement area, and the width direction is a measurement area of at least 300 μm, preferably 300 to 500 μm. Then, the ratio of the total area of macrovoids to the area of the measurement region is obtained. The above measurement is preferably carried out by observing the entire cross section of the membrane at a magnification of 100 to 500, particularly preferably 300. If it does not fit into one field of view in the thickness direction, a plurality of fields of view may be used.

FIG. 2 schematically shows the cross section 10 of the diaphragm for alkaline water electrolysis 1. In the cross section 10 perpendicular to the surface 11 of the diaphragm for alkaline water electrolysis 1, the width of the cross section 10 increases from both ends in the longitudinal direction toward the center. In the range of 0.4a or more away from a, the entire thickness direction of the film (from one surface to the other surface) is the measurement area, and the width direction is at least 300 μm, preferably 300 to 500 μm. , for example, to obtain a cross-sectional observation image at a magnification of 100 to 300 (preferably, the entire film occupies 80% or more of the visual field area). The range indicated by 12 in FIG. 2 is used for the measurement of the resin internal porosity, which will be described later. Regarding the macrovoid existence rate, as described above, the measurement area is the entire thickness direction of the film from one surface to the other surface.

This cross-sectional observation image is divided into a bright portion, a semi-bright portion, and a dark portion using analysis software. Here, the bright areas are inorganic particles, the semi-bright areas are organic polymers, and the dark areas are pores and voids. When a closed perimeter is extracted for a gap, two points on the perimeter of the gap are connected and an average value of diameters passing through the center of gravity is calculated as the pore diameter. Subsequently, macrovoids with a pore diameter of 10 μm or more are extracted, and the sum of their areas, _{S_MACRO} , is obtained. Then, the macrovoid existence ratio S _MACRO /S _A with respect to the total area S _A from one surface of the film to the other surface is obtained.

1-3-2 Resin internal porosity As described above, the resin internal porosity is 0.4a with respect to the width a of the cross section from both ends in the longitudinal direction toward the center in the cross section perpendicular to the surface of the membrane. The sum of the total area S _R of the organic polymer and the area S of the internal pores of the resin in the range separated by more than 10 μm and in the range between the position separated by 20 μm in the depth direction from the surface of the membrane. It is the ratio S _MICRO /(S _R +S _MICRO ) of the sum S _MICRO of the _area of the resin internal pores to the sum S _R +S _MICRO with MICRO. The resin internal porosity is 5% or more, more preferably 10% or more. The upper limit of the resin internal porosity is 20%. When the resin internal porosity in the inside of the membrane is within the above range, a diaphragm for alkaline water electrolysis that achieves both higher membrane strength, higher ion conductivity, and better yield is obtained.

To specifically explain the method for determining the internal porosity of the resin, in a cross section 10 perpendicular to the surface 11 of the diaphragm 1 for alkaline water electrolysis shown in FIG. A cross-sectional observation image is obtained by FE-SEM measurement in a range 12 between a position 10 μm and a position 20 μm apart in the depth direction S from the surface 11 in a range 0.4a or more away from a. The cross-sectional observation image is divided into a bright portion, a semi-bright portion, and a dark portion using analysis software. Here, the bright areas are inorganic particles, the semi-bright areas are organic polymers, and the dark areas are pores and voids.

FIG. 3 schematically shows the obtained cross-sectional observation image, where 21 is inorganic particles and 22 is an organic polymer. The organic polymer 22 may constitute a resin partition. 23 are pores closed only by the contour lines of the organic polymer and have a pore diameter of 0.08 μm to 1.20 μm, and 24 are voids.

For the pores extracted in the cross-sectional observation image, an average value of diameters passing through the center of gravity and connecting two points on the outer circumference of the pores is calculated, and is defined as the diameter of each of the pores. Subsequently, resin internal pores having a pore diameter of 0.08 μm to 1.20 μm, which are closed only by the outline of the organic polymer, are extracted, and the sum of their areas is obtained. On the other hand, the sum of the areas of the organic polymer is obtained from the sum of the areas of the semi-bright portions, and the internal porosity of the resin is obtained from these values.

The measurement area for determining the internal porosity of the resin is "a range that is 0.4a or more away from the width a of the cross section from both ends in the longitudinal direction toward the center in the cross section perpendicular to the surface of the membrane". , from the range between 10 μm and 20 μm in the depth direction from the surface of the membrane. Preferably, 10 rectangular measurement areas of 4.4 μm in thickness direction and 6.2 μm in width direction are selected in an image observed at 20,000 magnifications by FE-SEM. _{Ratio S MICRO / ( _} S _R +S _MICRO ) is determined at 10 locations, and the average value is determined.

The surface of the diaphragm for alkaline water electrolysis is not particularly limited, and may be, for example, the surface on the single membrane layer 2 side of the diaphragm 1 for alkaline water electrolysis in FIG. 1 or the surface on the support layer 3 side. As a method for determining the resin internal porosity, it is preferable to evaluate and determine the image observed by FE-SEM in the above range 12. Although the observation magnification is not particularly limited, it is usually 20,000 magnification or more, preferably 20,000 magnification, and if necessary, the magnification can be further increased. It is also preferred to determine

In the diaphragm for alkaline water electrolysis of the present invention, if the macrovoid existence ratio determined in this way is 25% or less and the resin internal porosity is 5% or more, higher membrane strength, higher ionic conductivity and It is possible to obtain a diaphragm that achieves both excellent yield and can be suitably used for electrolysis of alkaline water. The macrovoid existence rate and the resin internal porosity are included in the scope of the present invention as long as the above-described predetermined values are obtained in at least one arbitrarily selected field of view. The minimum size of the area for obtaining the macrovoid abundance and the resin internal porosity is an area of 2.8 μm×4.2 μm.

1-4 Porosity The membrane for alkaline water electrolysis of the present invention preferably has a porosity of 25 to 80%, more preferably 30 to 75%, even more preferably 35 to 70%. When the porosity of the membrane as a whole is within the above range, the pores in the diaphragm are more continuously filled with the electrolytic solution, so that the membrane exhibits higher ionic conductivity, more excellent ion permeability, and more excellent gas barrier properties. It can be used as a film.

The porosity of the membrane as a whole is the calculated density value of the diaphragm calculated using the measured density value of the diaphragm measured by the method shown below, and the density value (true density) and composition ratio of each component constituting the diaphragm. It can be calculated from the following formula.
Porosity (%) = [1 - (measured density value) / (calculated density value)] × 100
The measured density value can be calculated by measuring the mass and volume of a test piece cut from an arbitrary location of the obtained diaphragm and dividing the mass by the volume. The volume can be calculated by measuring the vertical and horizontal lengths of the test piece using calipers, and measuring the film thickness based on the film thickness measurement method described above. Also, the mass of the test piece can be measured using a precision balance with four digits below the decimal point for the test piece whose volume has been measured.

1-5 Ionic Conductivity The ionic conductivity of the diaphragm for alkaline water electrolysis of the present invention can be calculated by the method described in Examples. The ion conductivity of the diaphragm for alkaline water electrolysis of the present invention is preferably more than 100 mS/cm. In this case, the electrolysis efficiency in alkaline water electrolysis can be made higher.

1-6 Thickness The thickness of the diaphragm for alkaline water electrolysis of the present invention is not particularly limited, and may be appropriately selected according to the size of the equipment to be used, handleability, etc. 50 to 2000 μm is preferable, 100 to 1000 μm is more preferable, 100 to 500 μm is still more preferable, and 150 to 350 μm is most preferable from the viewpoint of ion permeability and strength.
Further, when the porous support described above is included, the thickness of the diaphragm for alkaline water electrolysis of the present invention is preferably 50 to 2000 μm, more preferably 100 to 1000 μm, still more preferably 100 to 500 μm, most preferably 150 to 300 μm. is.

2. Method for Producing Diaphragm for Alkaline Water Electrolysis The method for producing a diaphragm for alkaline water electrolysis of the present invention comprises preparing a resin mixed solution by mixing an organic polymer resin (R), inorganic particles, and lithium chloride with a solvent. and a film forming step of forming a film using the resin mixture. It is preferable to include a dispersion liquid preparation step before the resin mixed liquid preparation step.
Each step will be described below.

2-1 Dispersion liquid preparation step In the above production method, when inorganic particles are mixed with the resin (R), a dispersion liquid in which the inorganic particles are dispersed in a solvent is prepared in advance and then mixed with the resin (R). is preferred. A dispersant may be added to the above dispersion.

Examples of the dispersant include cationic surfactants; anionic surfactants; and conventionally known pigment dispersants having a hydrophilic functional group such as a carboxy group, a phosphoric acid group, and a sulfonic acid group.
As the cationic surfactant, a cationic surfactant having a hydrocarbon chain with 5 or more carbon atoms in the molecule is more preferable.
As the anionic surfactant, an anionic surfactant having a hydrocarbon chain with 5 or more carbon atoms in the molecule is more preferable.
The polymer pigment dispersant is not particularly limited as long as it is a polymer having a hydrophilic functional group, but it is preferably a polymer having a hydrocarbon chain having 5 or more carbon atoms in the main chain or side chain, and furthermore, a structural unit ( A polymer containing a hydrocarbon chain having 5 or more carbon atoms as a repeating unit) is more preferable, and a polymer containing a polyester or polyether having 5 or more carbon atoms as a structural unit is more preferable.

As such a polymer, even a polymer containing only a structural unit containing a hydrocarbon chain having 5 or more carbon atoms as a repeating unit, a structural unit other than a structural unit containing a hydrocarbon chain having 5 or more carbon atoms may be used. It may be further included as a repeating unit.
In the latter case, even if the polymer consists of a block containing only a structural unit containing a hydrocarbon chain having 5 or more carbon atoms as a repeating unit and a block composed of other structural units, carbon atoms in the molecule It may be a polymer having a structure in which structural units containing hydrocarbon chains of 5 or more and other structural units are randomly connected.
The amount of the dispersant used is preferably 1 to 10 parts by mass, more preferably 1.2 to 8.0 parts by mass, and even more preferably 1.5 to 5.0 parts by mass or less with respect to 100 parts by mass of the solvent. . By doing so, the dispersion stability of the inorganic particles can be improved more effectively.

The content of inorganic particles in the dispersion liquid is preferably 20 to 70% by mass, more preferably 30 to 65% by mass, and still more preferably 50 to 65% by mass.

The solvent for dispersing the inorganic particles is not particularly limited as long as it has the property of dissolving the resin (R) to be mixed later. Examples include N-methyl-2-pyrrolidone and N,N-dimethyl. Acetamide, N,N-dimethylformamide, dimethylsulfoxide, methyl ethyl ketone, toluene and the like. These solvents may be used singly or in combination of two or more. Among them, N-methyl-2-pyrrolidone is preferable in terms of good dispersibility of the inorganic particles. The amount of the solvent used relative to the inorganic particles in the dispersion is preferably 50 to 100 parts by mass, more preferably 50 to 90 parts by mass, and even more preferably 50 to 80 parts by mass with respect to 100 parts by mass of the inorganic particles.

The method for dispersing the inorganic particles in the solvent is not particularly limited, and known mixing and dispersing means such as a method using a mixer, ball mill, jet mill, disper, sand mill, roll mill, pot mill, bead mill, paint shaker, etc. are applied. be able to.

The average particle size of the inorganic particles in the dispersion liquid is preferably 0.1 to 1.0 μm, more preferably 0.15 to 0.8 μm, still more preferably 0.15 to 0.5 μm. The average particle size of the inorganic particles in the dispersion can be determined by particle size distribution measurement using a dynamic light scattering method, and can be specifically measured by the method described in Examples.

2-2 Resin Mixture Preparation Step In the resin mixture preparation step, preferably, the dispersion prepared in the dispersion preparation step is mixed with the organic polymer resin (R) and lithium chloride to prepare a resin mixture. . By adding lithium chloride, pores are formed inside the above resin (R), which is preferably the organic polymer constituting the partition walls, and a macrovoid-free film that exhibits flexibility can be produced. The amount of lithium chloride added is preferably 1.0% by mass or more with respect to 100% by mass of the inorganic particles. As an upper limit, it is 10 mass %, for example.

An organic hydrophilic additive may be added to the resin mixture. Examples of the organic hydrophilic additives include water-soluble polymers such as polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, polyethyleneimine, polyacrylic acid and dextran; surfactants; glycerin; sugars and the like. The amount of the hydrophilic additive used is preferably 0.1 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the inorganic particles in the dispersion.

The method for mixing the resin (R) with the dispersion liquid prepared in the dispersion liquid preparation step is not particularly limited as long as it is a method capable of sufficiently mixing the dispersion liquid and the resin (R). The resin (R) may be mixed with the dispersion as it is, or a resin solution may be prepared by dissolving the resin (R) in a solvent in advance, and the resin solution and the dispersion may be mixed. good. Among them, a method of preparing the resin solution and mixing the resin solution and the dispersion to obtain a resin mixed solution is preferred because the inorganic particles and the resin (R) can be more uniformly dispersed and mixed. preferable.

The solvent used for preparing the resin mixture is not particularly limited as long as it has the property of dissolving the resin (R). Examples include N-methyl-2-pyrrolidone and N,N-dimethyl. Acetamide, N,N-dimethylformamide, dimethylsulfoxide, methyl ethyl ketone, toluene and the like. Among them, the same solvent as the solvent used for preparing the dispersion liquid is preferable in that the inorganic particles and the resin (R) can be dispersed and mixed more uniformly.

The content of the resin (R) in the resin solution is preferably 5 to 50% by mass, more preferably 10 to 45% by mass, even more preferably 15 to 40% by mass.
Examples of the mixing method include the same means as the mixing and dispersing means described in the dispersion liquid preparation step.

The dispersion liquid and the resin (R) are preferably 10 to 40 parts by mass, more preferably 12 to 35 parts by mass, still more preferably 15 to 33 parts by mass, based on 100 parts by mass of the inorganic particles. It is preferable to mix so that it becomes a mass part. Moreover, it is preferable that the inorganic particles are contained in an amount of 150% by volume or more with respect to the resin (R) as the organic polymer. When the content ratio of the inorganic particles and the resin (R) is within the range described above, the elution of inorganic components in the resulting diaphragm for alkaline water electrolysis in an alkaline solution is further suppressed, and higher ion conductivity is exhibited. In addition, it is possible to produce a diaphragm for alkaline water electrolysis that is more excellent in ion permeability, gas barrier properties, heat resistance and alkali resistance.

When the dispersion of the inorganic particles and the solution of the resin (R) are mixed, the total content of the solvent in the dispersion of the inorganic particles and the solvent in the solution of the resin (R) is the dispersion of the inorganic particles. It is preferably 30 to 75% by mass with respect to 100% by mass of the total mass of the liquid and the solution of the resin (R). More preferably 35 to 70% by mass, still more preferably 40 to 65% by mass. In order to adjust the porosity of the diaphragm for alkaline water electrolysis to a preferable range, it is preferable to use the solvent in such a ratio.

2-3 Film Formation Step In the film formation step, a film is formed using the resin mixture obtained in the resin mixture preparation step.
As a method for forming the above membrane, the following steps (a) and (b) are preferred in that a diaphragm for alkaline water electrolysis in which the elution of inorganic components in an alkaline solution is further suppressed can be easily produced. is preferably included.
(a) forming a coating film of the resin mixture, and
(b) contacting the coating film with a non-solvent to solidify the coating film to obtain a porous film;

(a) Step of forming a coating film of the resin mixed solution Examples of the method of forming a coating film of the resin mixed solution include a method of applying the resin mixed solution obtained above on a substrate, and a method of applying the resin mixed solution A method of obtaining a base material impregnated with the above-mentioned mixed resin liquid by immersing the base material in the liquid can be used. Among them, the method of applying the above-mentioned resin mixed solution onto a base material is preferable in that a coating film can be easily formed.

The method of applying the resin mixture onto the substrate is not particularly limited, and known coating means such as methods using die coating, spin coating, gravure coating, curtain coating, spray, applicator, bar coater, etc. are applied. can do.

The substrate is not particularly limited as long as it can be coated with the resin mixture to form a coating film. Examples include polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene, polyvinyl chloride, and polyvinyl. A film or sheet made of a resin such as acetal, polymethyl methacrylate, polycarbonate, or the like, a glass plate, or the like can be used. Among them, polyethylene terephthalate is preferable because it is easy to handle and the material cost can be reduced.
Moreover, when manufacturing the diaphragm for alkaline water electrolysis containing the porous support mentioned above, you may use the said porous support as said base material.

In the case of producing a diaphragm for alkaline water electrolysis, which is a composite in which a membrane containing inorganic particles, the resin (R), and a porous support are integrated, the resin mixed solution is applied onto the base material. Then, the porous support may be placed on the coating liquid to impregnate the porous support with the coating liquid.

The amount of the resin mixed solution to be applied is not particularly limited, and may be appropriately set so that the diaphragm has a thickness capable of exhibiting the above-described effects.

(b) a step of solidifying the coating film by contacting the coating film with a non-solvent, thereby causing the non-solvent to diffuse in the coating film and not dissolving in the non-solvent; Resin (R) solidifies. On the other hand, the solvent in the coating film that is soluble in the non-solvent is eluted from the coating film. Due to the occurrence of phase separation in this manner, the resin (R) (and the inorganic particles) is solidified to form a porous film.

Examples of the method of bringing the coating film into contact with the non-solvent include a method of immersing the coating film in the non-solvent (coagulation bath), and a method of exposing the coating film to the non-solvent vapor atmosphere. Alternatively, after the coating film is exposed to the non-solvent vapor atmosphere, it may be subsequently immersed in the non-solvent. In this case, the exposure time to the non-solvent vapor atmosphere can be about 3 to 60 seconds, and the time to be immersed in the non-solvent can be about 1 to 15 minutes.

The temperature of the non-solvent in which the coating film is immersed is preferably 10°C or higher, more preferably 15°C or higher, and even more preferably 20°C or higher. Moreover, 55 degrees C or less is preferable, 50 degrees C or less is more preferable, and 45 degrees C or less is more preferable. By setting such a temperature, more ion paths can be formed in the manufactured diaphragm, and a diaphragm for alkaline water electrolysis that exhibits high ionic conductivity, higher gas barrier properties, and higher durability can be more easily manufactured. can.

The non-solvent is not particularly limited as long as it has a property of not substantially dissolving the resin (R). A mixed solvent or the like can be preferably used. Ion-exchanged water is preferable from the viewpoint of economy and waste liquid treatment. In addition to the components described above, the non-solvent may contain a small amount of the same solvent as the solvent contained in the coating film.

The amount of the non-solvent used is preferably 50 to 10,000 parts by mass with respect to 100 parts by mass of the coating film, ie, 100 parts by mass of the solid content of the resin mixture used for forming the coating film. It is more preferably 100 to 5000 parts by mass, still more preferably 200 to 1000 parts by mass. It is preferable to use the non-solvent in such a ratio in order to adjust the porosity of the membrane to be obtained within a preferable range and to completely extract the solvent in the coating film into the non-solvent.

Furthermore, in order to remove the non-solvent, the coating film solidified in the above step may be dried to obtain the diaphragm.
The drying temperature for the coating film is preferably 60 to 120°C.
The drying time is preferably 0.5 to 120 minutes, more preferably 1 to 60 minutes, even more preferably 1 to 30 minutes.

In the method for producing a diaphragm for alkaline water electrolysis of the present invention, it is believed that the addition of lithium chloride increases the hydrophilicity of the resin mixed solution, making it easier for the resin (R) to aggregate. For this reason, it is believed that the internal structure of the membrane is formed by forming pores in the aggregated resin (R), and a membrane that can achieve both higher membrane strength, higher ionic conductivity, and better yield is produced. As described above, the diaphragm for alkaline water electrolysis of the present invention can be easily produced by the steps described above.

3. Applications The diaphragm for alkaline water electrolysis of the present invention can achieve both higher membrane strength, higher ion conductivity, and higher yield. Therefore, the diaphragm for alkaline water electrolysis of the present invention can be suitably used as a diaphragm for water electrolysis using an alkaline aqueous solution as an electrolyte. In addition to the diaphragm for alkaline water electrolysis described above, it can also be used for battery separators such as alkaline fuel cell separators, primary battery separators, secondary battery separators, and salt electrolysis separators.

4. Alkaline Water Electrolysis Apparatus The diaphragm for alkaline water electrolysis of the present invention is used as a member of an alkaline water electrolysis apparatus. Examples of the alkaline water electrolysis apparatus include those including an anode, a cathode, and the diaphragm for alkaline water electrolysis arranged between the anode and the cathode. More specifically, the alkaline water electrolysis apparatus has an anode chamber in which an anode exists and a cathode chamber in which a cathode exists, which are separated by the diaphragm for alkaline water electrolysis.
The anode and cathode include known electrodes such as conductive substrates containing nickel, nickel alloys, and the like.

5. Electrolyzing Method The method of electrolyzing water using the alkaline water electrolysis apparatus provided with the diaphragm for alkaline water electrolysis of the present invention is not particularly limited, and a known method can be used. For example, it can be carried out by filling an electrolytic solution into an alkaline water electrolysis apparatus provided with the above-described diaphragm for alkaline water electrolysis of the present invention and applying an electric current in the electrolytic solution.
As the electrolytic solution, an alkaline aqueous solution in which an electrolyte such as potassium hydroxide or sodium hydroxide is dissolved is used. Although the concentration of the electrolyte in the electrolytic solution is not particularly limited, it is preferably 20 to 40% by mass from the viewpoint of further improving the electrolysis efficiency.
The temperature for electrolysis is preferably 50 to 120° C., more preferably 80 to 90° C., since the ion conductivity of the electrolytic solution can be further improved and the electrolysis efficiency can be further improved. Current application conditions can be performed by known conditions and methods.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited only to these examples. Unless otherwise specified, "part" means "mass part" and "%" means "mass %".

<Example 1>
(1. Preparation of magnesium hydroxide dispersion)
Magnesium hydroxide (average particle size 0.20 μm) and N-methyl-2-pyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed at a mass ratio of 1:1, and the mixture was placed in a pot mill containing zirconia media balls. A magnesium hydroxide dispersion was prepared by carrying out a dispersion treatment at room temperature for 6 hours.

(2. Preparation of polysulfone resin solution)
Polysulfone resin (manufactured by BASF, product number Ultrason S3010) was thermally dissolved in N-methyl-2-pyrrolidone (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) at a concentration of 30% by mass at 80 to 100°C.

(3. Preparation of coating liquid)
Weigh the magnesium hydroxide dispersion and the polysulfone resin solution obtained above so that the solid content is 40% by mass and the polysulfone resin (PSU) is 33 parts by mass with respect to 100 parts by mass of magnesium hydroxide, Furthermore, 5% by mass of lithium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) is added to 100% by mass of magnesium hydroxide, and the rotation and revolution mixer (manufactured by Thinky, product number Awatori Mixer ARE-500) is used at room temperature at 1000 rpm. and mixed for about 10 minutes. The resulting mixed liquid was filtered through SUS 200 mesh to obtain a coating liquid.

(4. Formation of coating film)
A polyphenylene sulfide nonwoven fabric (Torcon Paper #100, manufactured by Toray Industries, Inc.) was coated with the solution so that the thickness of the membrane after drying was 250 μm in total, and the nonwoven fabric was completely impregnated with the coating solution. Thereafter, the nonwoven fabric impregnated with the coating liquid was subjected to a water bath at room temperature for 10 minutes to solidify the coating liquid and form a film. After the water bath, the obtained membrane was dried in a dryer at 80° C. for 30 minutes to obtain a diaphragm for alkaline water electrolysis comprising a composite of a nonwoven fabric, a membrane containing magnesium hydroxide and a polysulfone resin.

(5. Film thickness measurement method)
The thickness of the obtained diaphragm for alkaline water electrolysis was measured using a digimatic micrometer (manufactured by Mitutoyo Corporation). Ten arbitrary points were measured, and the average value was used as the film thickness. The film thickness was 250 μm.

(6. Measurement and calculation method of macrovoid existence ratio and resin internal porosity in the membrane)
With respect to the cross section perpendicular to the surface of the obtained diaphragm for alkaline water electrolysis, from both ends in the longitudinal direction toward the center, the distance is 10 μm from the surface of the membrane in a range of 0.4 a or more with respect to the width a of the cross section. A cross-sectional observation image (magnification: 30,000 times) was obtained by FE-SEM (manufactured by JEOL Ltd., model number: JSM-7600F) measurement in the range between the position and the position 20 μm away.
Analysis software (Image-Pro Premier) is used for the obtained cross-sectional observation image to divide the image into a bright portion, a semi-bright portion, and a dark portion by median processing, and the area of the semi-bright portion corresponding to the polysulfone resin is calculated. The total value, the total value of the area of pores with a pore diameter of 10 μm or more, and the dark area of the pores that are closed only by the outline of the organic polymer and have a pore diameter of 0.08 μm to 1.20 μm The total value of the area of was calculated. Then, from these values, the macrovoid existence ratio and the resin internal porosity were obtained. As a result, the macrovoid existence ratio was 0%, and the resin internal porosity was 12.6%.

(7. Measurement of bubble point value)
The bubble point value of the obtained diaphragm for alkaline water electrolysis was measured using a liquid porosimeter (manufactured by Porous Materials). Specifically, a diaphragm of 2.5 cmφ was immersed in deionized water at room temperature for 1 hour to be sufficiently wet, and then the diaphragm was filled with Galwick (manufactured by Porous Materials), which is a fluorine-based solvent. The gas pressure against the diaphragm was increased, and the gas pressure at the time when the liquid film of water was broken, Galwick permeated the film, and the weight was observed with a balance was taken as the bubble point value. The bubble point value of the diaphragm was 1000 kPa or more, which is the upper limit of measurement.

(8. Method for measuring ionic conductivity)
The ionic conductivity of the obtained diaphragm for alkaline water electrolysis was measured by the following measuring method. As a result, it was 225 mS/cm.
(Measuring method)
Prepare two diaphragm samples for measurement.
Using each diaphragm sample, a cell formed with the following cell configuration was allowed to stand in a constant temperature bath at 25° C. for 30 minutes, and then AC impedance was measured under the following measurement conditions. The ionic conductivity is measured by the following formula using the intercept component (Rb) in the absence of a measurement sample and the film thickness value obtained by the film thickness measurement method described above.
The above measurement is performed on two membrane samples, and the average value of the obtained measured values (two points) is calculated and taken as the ionic conductivity of the membrane.
[Ionic conductivity (mS / cm)] = [film thickness (cm)] ÷ [(Ra-Rb) × 1000 × 1.77]
(Measurement condition)
・Cell configuration Working electrode: Ni plate Counter electrode: Ni plate Electrolyte solution: 30% by mass potassium hydroxide aqueous solution Sample pretreatment: immersed overnight in the above electrolyte solution Effective area for measurement: 1.77 cm ²
- AC impedance measurement conditions Applied voltage: 10 mV vs. Open circuit voltage Frequency range: 100kHz to 100Hz

(9. Method for evaluating film strength)
The membrane strength of the obtained diaphragm for alkaline water electrolysis was evaluated by the following bending test and tensile strength test.

(Bending test)
Using a bending tester (manufactured by Yasuda Seiki Seisakusho, Model No. 514), the support of the test piece of the electrochemical device separator cut into 2 × 5 cm is placed between the test receiving plate and the mandrel so that the support is on the inside. It was pinched and bent at 180° C. for 2 seconds, and then examined for cracks on the surface of the coating film using a laser microscope (manufactured by Keyence Corporation, model number VK-9700) at a magnification of 10. No cracks were found.

(Tensile strength test)
After leaving the test piece of the electrochemical element separator cut to 3 × 10 cm at 23 ° C. and 50% constant temperature and humidity for 1 hour, a tensile tester (manufactured by Shimadzu Corporation, model number Autograph AG-1kN XPlus ) at a distance of 5 cm between jigs and a speed of 10 cm/min in the MD direction (longitudinal direction of the nonwoven fabric and the coating direction of the coating liquid), and the strength at break was measured to be 330 N/30 mm.

<Example 2>
A diaphragm for alkaline water electrolysis was obtained in the same manner as in Example 1, except that the amount of lithium chloride used was changed to 2% by mass with respect to 100% by mass of magnesium hydroxide. The film thickness was 270 μm, the macrovoid existence ratio was 23%, the resin internal porosity was 5.7%, and the bubble point value was 455 kPa.
As a result of measuring the ionic conductivity of the obtained diaphragm for alkaline water electrolysis in the same manner as in Example 1, it was 198 mS/cm. No cracks occurred in the bending test, and the tensile strength was 310 N/30 mm.

<Comparative Example 1>
A diaphragm for alkaline water electrolysis was obtained in the same manner as in Example 1, except that lithium chloride was not used. The film thickness was 261 μm, the macrovoid existence ratio was 28%, the resin internal porosity was 0%, and the bubble point value was 1000 kPa or more, which is the upper limit of measurement.
As a result of measuring the ionic conductivity of the obtained diaphragm for alkaline water electrolysis in the same manner as in Example 1, it was 149 mS/cm. Although no cracks occurred in the bending test, the tensile strength was 260 N/30 mm.

<Comparative Example 2>
Alkali was prepared in the same manner as in Example 1, except that lithium chloride was not used and isopropyl alcohol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as a non-solvent in (4. Formation of coating film) instead of water. A diaphragm for water electrolysis was obtained. The film thickness was 243 μm, the macrovoid existence rate was 0%, the resin internal porosity was 0%, and the bubble point value was 1000 kPa or more, which is the upper limit of measurement.
As a result of measuring the ionic conductivity of the obtained diaphragm for alkaline water electrolysis in the same manner as in Example 1, it was 149 mS/cm. Cracks were observed in the bending test, and the tensile strength was 340 N/30 mm.

1 Diaphragm for alkaline water electrolysis 2 Single membrane layer 3 Support layer 10 Cross section of diaphragm for alkaline water electrolysis 11 Surface of diaphragm for alkaline water electrolysis 12 Measurement range a Width of cross section perpendicular to surface of diaphragm for alkaline water electrolysis S Alkaline water Depth direction from the surface of the diaphragm for electrolysis 21 Inorganic particles 22 Organic polymer 23 Resin internal pores 24 which are pores closed only by the outline of the organic polymer and have a pore diameter of 0.08 μm to 1.20 μm Voids

Claims (3)

A diaphragm for alkaline water electrolysis comprising an organic polymer, inorganic particles and a porous support ,
a single film layer containing the organic polymer and the inorganic particles and not containing the porous support;
a support layer containing the organic polymer, the inorganic particles, and the porous support;
The monolayer is formed only on one side of the support layer,
In a cross section perpendicular to the surface of the diaphragm for alkaline water electrolysis , in a range that is 0.4a or more away from the width a of the cross section from both ends in the longitudinal direction toward the center,
The ratio S _MACRO /S _A of the sum of the areas of macrovoids having a pore diameter of 10 μm or more with respect to the total area S _A from one surface to _the other surface of the diaphragm for alkaline water electrolysis is 25% or less. ,
In the range between a position 10 μm away from the surface of the diaphragm for alkaline water electrolysis and a position 20 μm away in the depth direction, pores closed only by the total area _SR of the organic polymer and the contour line of the organic polymer The ratio of the sum of the areas of the resin internal pores S _MICRO to the sum of the areas S _MICRO of the resin _{internal pores having a pore diameter of 0.08 μm to 1.20 μm S MICRO / (} S _R + S _MICRO ) is 5% or more,
Diaphragm for alkaline water electrolysis. 2. The diaphragm for alkaline water electrolysis according to claim 1, which contains 150% by volume or more of said inorganic particles with respect to said organic polymer. comprising an organic polymer, inorganic particles and a porous support;
a single film layer containing the organic polymer and the inorganic particles and not containing the porous support;
a support layer containing the organic polymer, the inorganic particles, and the porous support;
The monolayer is formed only on one side of the support layer,
A method for producing a diaphragm for alkaline water electrolysis, comprising:
A resin mixture preparation step of preparing a resin mixture by mixing the organic polymer , the inorganic particles, and lithium chloride with a solvent;
A method for producing a diaphragm for alkaline water electrolysis, comprising a film-forming step of forming a film using the resin mixture.

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