Composite membrane for electrolysis

Abstract

The present invention addresses the problem of providing: a composite membrane for electrolysis, the composite membrane having more excellent ion permeability, gas barrier properties, and wear resistance; and a production method therefor. The present invention relates to a sheet-like composite membrane for electrolysis, the composite membrane having a first porous coating layer, a porous support, and a second porous coating layer, wherein the first porous coating layer has a first surface layer (B1) and a first intermediate layer (A1), the second porous coating layer has a second surface layer (B2) and a second intermediate layer (A2), the composite membrane has the first surface layer (B1), the first intermediate layer (A1), the porous support, the second intermediate layer (A2), and the second surface layer (B2) in this order, and, when the average pore diameter in the surface of the first surface layer (B1) is denoted as PB1, the average pore diameter in the surface of the second surface layer (B2) is denoted as PB2, and the average pore diameter in the first intermediate layer and the second intermediate layer is denoted as PA, PA, PB1, and PB2 satisfy PB1 < PA and PB2 < PA.

Description

Composite membrane for electrolysis

[0001] The present invention relates to an electrolytic composite film and a method for producing the same.

[0002] In recent years, technologies for producing, storing, and utilizing hydrogen gas using renewable energy sources such as wind power and solar power have been actively studied, and development aimed at practical application is progressing. One example of a hydrogen gas production method is alkaline water electrolysis, which can produce oxygen gas and hydrogen gas by electrolyzing water.

[0003] Similarly, carbon dioxide electrolysis is known as an example of a carbon dioxide reuse technology that utilizes renewable energy. This method involves electrolyzing carbon dioxide to convert it into valuable substances such as carbon monoxide, ethylene, and formic acid, while also considering efforts to reduce carbon dioxide emissions.

[0004] In these alkaline water electrolysis devices and carbon dioxide electrolysis devices, two electrode plates are placed in an electrolytic cell filled with an alkaline solution such as potassium hydroxide aqueous solution or potassium bicarbonate, or carbon dioxide gas, and a diaphragm is installed between the two electrode plates. The diaphragm separates the electrolytic cell into an anode side and a cathode side, and the diaphragm is made of a material that is permeable to hydroxide ions and bicarbonate ions, but not to gases.

[0005] It has been known for some time that porous membranes can be suitably used as diaphragms for such alkaline water electrolysis.

[0006] For example, Patent Document 1 describes a diaphragm for alkaline water electrolysis in which a single layer of porous microporous membrane containing an organic polymer resin is laminated on one or both sides of a sheet-like porous support.

[0007] For example, Patent Document 2 describes a diaphragm for alkaline water electrolysis comprising a sheet-like porous support and a porous membrane containing an organic polymer resin impregnated into the support from one surface of the support.

[0008] For example, Patent Document 3 describes an alkali hydrolysis-resistant separator comprising a porous support, a first porous polymer layer adjacent to one side of the support, and a second porous polymer layer adjacent to the opposite side of the support, characterized in that the maximum pore diameters of the outer surfaces of the first porous polymer layer and the second porous polymer layer are different from each other.

[0009] Furthermore, it has been known that porous membranes can be suitably used as diaphragms for such carbon dioxide electrolysis. For example, Patent Document 4 describes a carbon dioxide electrolytic cell equipped with a porous membrane as a diaphragm between a cathode to which carbon dioxide is supplied and an anode to which electrolyte is supplied.

[0010] Japanese Patent Publication No. 2014-129563, Japanese Patent Publication No. 2017-2389, Japanese Patent Publication No. 2020-527193, Japanese Patent Publication No. 2024-131154

[0011] In water electrolysis, improving the efficiency of water electrolysis is required to make efficient use of supplied electricity. Furthermore, reducing the risk of explosion due to hydrogen gas contamination in oxygen gas and improving gas purity are also necessary. Wind and solar power generation are prone to power fluctuations, and when the power supply to water electrolysis equipment is low, hydrogen gas contamination in oxygen gas tends to occur more easily, sometimes requiring a period of shutdown to reduce the risk of explosion. Further suppression of hydrogen gas contamination can shorten shutdown times and improve the operating efficiency of water electrolysis equipment.

[0012] In carbon dioxide electrolysis, as in water electrolysis, improving the efficiency of carbon dioxide electrolysis is required to efficiently utilize the supplied electricity. Furthermore, it is necessary to prevent or reduce the leakage of carbon dioxide gas and electrolytic product gases supplied to the cathode to the anode side. By suppressing the leakage of carbon dioxide gas and electrolytic product gases, it is possible to improve the utilization efficiency of carbon dioxide, the raw material, and the recovery efficiency of electrolytic product gases, which are valuable materials.

[0013] Based on the requirements described above, electrolytic composite membranes used as diaphragms are expected to have further improvements in ion permeability and gas barrier properties.

[0014] Furthermore, in composite films having a porous coating layer on a porous support as exemplified in Patent Documents 1 to 4, there is a problem in that a part of the composite film may detach due to friction between the composite film and the electrode or vibration caused by bubbles generated during operation, resulting in a decrease in gas barrier performance. Therefore, further improvement in wear resistance is desired.

[0015] Patent Document 1 proposes a microporous membrane provided on a porous support, in which the pore diameter inside the microporous membrane is smaller than the pore diameter on the membrane surface, thereby enabling the membrane to maintain gas barrier properties even if physical damage occurs to the membrane surface. However, this method results in a coarser surface structure of the microporous membrane, leading to insufficient physical strength, and sometimes causing parts of the membrane to detach. There is a concern that the detached parts of the membrane may accumulate in the electrolyte circulation path and have adverse effects. Furthermore, if the membrane surface is damaged, in-plane variations in ion permeability may occur, potentially affecting the durability of the membrane and electrodes.

[0016] Patent Document 2 describes a diaphragm for alkaline water electrolysis in which a porous membrane is impregnated from one surface of a sheet-like porous support. On one surface, the porous support and the porous membrane are arranged substantially in the same plane, so the porous membrane is thicker on one side and thinner on the opposite side. In such a design, the shrinkage during the formation of the porous membrane differs on each side, which can cause the composite membrane to curl. In addition, the side with a thicker porous membrane tends to have a weaker reinforcing effect from the porous support, which may reduce the abrasion resistance on that side.

[0017] Patent Document 3 describes a porous support with porous polymer layers on both sides, where the maximum pore diameter on the outer surface of the porous polymer layer differs between the front and back sides, with one side having a larger pore diameter and the other side having a smaller one. Similar to Patent Document 1, the side with the larger pore diameter has a coarser structure, and in some cases, parts of the porous polymer layer may detach. Also, the side with the larger pore diameter has lower gas barrier properties compared to the side with the smaller pore diameter, which can trap air bubbles and create ion permeability resistance.

[0018] Patent document 4 describes a carbon dioxide electrolytic cell using a porous membrane. Because this porous membrane does not have a porous support, the stress applied to the membrane tends to concentrate in a weak part of the porous structure, which reduces its mechanical strength. As a result, there was a risk of damage due to stress associated with the generation of electrolytic gas, friction between the porous membrane and the electrodes, gas leaks, and short circuits between the electrodes.

[0019] In view of the above-mentioned problems, the present invention aims to provide an electrolytic composite film and a method for manufacturing the same that are superior in ion permeability, gas barrier properties, and abrasion resistance.

[0020] The present invention, for solving the above problems, is an electrolytic composite membrane having a first porous coating layer, a porous support, and a second porous coating layer, wherein the first porous coating layer has a first surface layer (B1) and a first intermediate layer (A1), the second porous coating layer has a second surface layer (B2) and a second intermediate layer (A2), and the composite membrane has the first surface layer (B1), the first intermediate layer (A1), the porous support, the second intermediate layer (A2), and the second surface layer (B2) in that order, and when the average pore diameter on the surface of the first surface layer (B1) is PB1, the average pore diameter on the surface of the second surface layer (B2) is PB2, and the average pore diameters in the first intermediate layer and the second intermediate layer are PA, then PA, PB1, and PB2 satisfy PB1 < PA and PB2 < PA.

[0021] Specifically, the present invention has the following configuration.

[0022] [1] A sheet-like composite film having a first porous coating layer, a porous support, and a second porous coating layer, wherein the first porous coating layer has a first surface layer (B1) and a first intermediate layer (A1), the second porous coating layer has a second surface layer (B2) and a second intermediate layer (A2), and the composite film has the first surface layer (B1), the first intermediate layer (A1), the porous support, the second intermediate layer (A2), and the second surface layer (B2) in that order, and when the average pore diameter on the surface of the first surface layer (B1) is PB1, the average pore diameter on the surface of the second surface layer (B2) is PB2, and the average pore diameter in the first intermediate layer and the second intermediate layer is PA, PA, PB1, and PB2 satisfy PB1 < PA and PB2 < PA.

[0023] [2] The electrolytic composite film according to [1] above, wherein PB1 and PB2 satisfy 0.9 ≤ PB1 / PB2 ≤ 1.1.

[0024] [3] The electrolytic composite film according to [1] or [2] above, wherein the PA is 0.1 μm or more and 5 μm or less.

[0025] [4] The electrolytic composite membrane according to any one of [1] to [3] above, wherein PB1 and PB2 are 0.05 μm or more and 1 μm or less. [5] The electrolytic composite membrane according to any one of [1] to [4] above, wherein the porous support consists of one or more of the following: polysulfone, polyethersulfone, polyphenylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyetherketone, polyketone, polyetherimide, polystyrene, polyolefin, polyethylene terephthalate, polyamide, and polycarbonate.

[0026] [6] The electrolytic composite membrane according to any one of [1] to [5] above, wherein the porous support is a mesh or a nonwoven fabric.

[0027] [7] The porous support has a weight of 20 g / m² per unit area. ２ More than 400g / m ２ The following conditions apply, and the density is 0.1 g / cm³. ３ 0.9g / cm or more ３ The electrolytic composite film described in [6] above is as follows:

[0028] [8] The electrolytic composite film according to [6] or [7], wherein the average fiber diameter of the porous support is 5 μm or more and 180 μm or less.

[0029] [9] The porous support, 1 m ２ The fiber surface area per square meter is 1 m² ２ Over 100m ２ The electrolytic composite film described in any of the above [6] to [8], which is as follows:

[0030]

[10] The electrolytic composite film according to any one of [1] to [9] above, wherein the first porous coating layer and the second porous coating layer contain one or more inorganic particles selected from titanium oxide, zirconium oxide, cerium oxide, barium sulfate, aluminum oxide, silica, boehmite, and magnesium hydroxide.

[0031]

[11] The electrolytic composite film according to any one of [1] to

[10] above, wherein the first porous coating layer and the second porous coating layer contain one or more of polysulfone, polyethersulfone, and polyphenylsulfone.

[0032]

[12] The electrolytic composite film according to any one of [1] to

[11] above, wherein the first porous coating layer comprises inorganic particles and a polymer, the second porous coating layer comprises inorganic particles and a polymer, and the value RX of the weight of the inorganic particles / the weight of the polymer in the first porous coating layer and the second porous coating layer is in the range of 3.3 or more and 15 or less.

[0033]

[13] The electrolytic composite film according to any one of [1] to

[12] above, wherein the first intermediate layer (A1) comprises inorganic particles and a polymer, the second intermediate layer (A2) comprises inorganic particles and a polymer, and the value RY of the weight of the inorganic particles / the weight of the polymer in the first intermediate layer (A1) and the second intermediate layer (A2) is in the range of 3.3 or more and 15 or less.

[0034]

[14] The electrolytic composite film according to

[13] , wherein RX and RY satisfy the condition 0.8 ≤ RX / RY ≤ 1.2.

[0035]

[15] A method for manufacturing an electrolytic composite film, comprising the steps of: preparing a coating solution containing an organic solvent solution of a polymer and inorganic particles; coating both sides of a porous support with the coating solution to obtain a coated sheet; and contacting the coated sheet with the non-solvent of the coating solution to form a first surface layer (B1) and a second surface layer (B2), and a first intermediate layer (A1) and a second intermediate layer (A2).

[0036]

[16] A method for manufacturing an electrolytic composite film, comprising the steps of: preparing a coating solution containing an organic solvent solution of a polymer and inorganic particles; repeating the steps of coating both sides of a porous support with the coating solution to obtain a coated sheet twice; and then bringing the coated sheet into contact with the non-solvent of the coating solution to form a first surface layer (B1) and a second surface layer (B2), and a first intermediate layer (A1) and a second intermediate layer (A2), in this order.

[0037]

[17] A water electrolysis apparatus comprising an electrolytic composite membrane as described in any of [1] to

[14] above.

[0038]

[18] A hydrogen production facility including the water electrolysis apparatus described in

[17] above.

[0039]

[19] A carbon dioxide electrolytic apparatus comprising an electrolytic composite membrane as described in any of [1] to

[14] above.

[0040]

[20] A carbon dioxide electrolysis facility including the carbon dioxide electrolysis apparatus described in

[19] above.

[0041] According to the present invention, it is possible to provide an electrolytic composite film with superior ion permeability, gas barrier properties, and abrasion resistance, as well as a method for manufacturing the same.

[0042] <Electrolytic Composite Film> The electrolytic composite film of the present invention is a sheet-like composite film having a first porous coating layer, a porous support, and a second porous coating layer, wherein the first porous coating layer has a first surface layer (B1) and a first intermediate layer (A1), the second porous coating layer has a second surface layer (B2) and a second intermediate layer (A2), and the composite film has the first surface layer (B1), the first intermediate layer (A1), the porous support, the second intermediate layer (A2), and the second surface layer (B2) in that order, and when the average pore diameter on the surface of the first surface layer (B1) is PB1, the average pore diameter on the surface of the second surface layer (B2) is PB2, and the average pore diameters in the first intermediate layer and the second intermediate layer are PA, then PA, PB1, and PB2 satisfy PB1 < PA and PB2 < PA.

[0043] In the present invention, it is preferable that the porous support has a first intermediate layer (A1) on one side and a second intermediate layer (A2) on the other side.

[0044] In the present invention, it is preferable that the first surface layer (B1) is directly laminated onto the first intermediate layer (A1). Similarly, it is preferable that the second surface layer (B2) is directly laminated onto the second intermediate layer (A2).

[0045] In this specification, the first intermediate layer (A1) and the second intermediate layer (A2) may be collectively referred to as "intermediate layer (A)". Here, the material of the first intermediate layer and the material of the second intermediate layer may be the same. Also, the composition and structure of the first intermediate layer (A1) and the composition and structure of the second intermediate layer (A2) may be the same.

[0046] In this specification, the first surface layer (B1) and the second surface layer (B2) may be collectively referred to as "surface layer (B)".

[0047] In this specification, the "first porous coating layer" and the "second porous coating layer" may be collectively referred to as the "porous coating layer."

[0048] In this invention, the gas barrier properties can be improved by reducing the average pore size of the surface layer (B), and the abrasion resistance can be improved by densifying the film. In addition, the ion permeability can be improved by increasing the average pore size of the intermediate layer (A). Because the intermediate layer (A) has a large pore size, for example, if the intermediate layer (A) is directly exposed to the surface, the abrasion resistance of the surface of the intermediate layer (A) tends to be relatively lower than that of the surface of the surface layer (B). However, as in this invention, by further laminating the surface layer (B) on the intermediate layer (A), the brittle layer due to its coarse structure is concealed, and the abrasion resistance is improved.

[0049] Similarly, the intermediate layer (A) alone lacks sufficient mechanical strength and is prone to cracking and partial detachment due to bending, etc. However, by laminating the surface layer (B), the overall mechanical strength of the electrolytic composite film can be increased, preventing cracking.

[0050] In this specification, ion permeability can be evaluated by the method described in [Measurement Example 3] below, and the ion permeability resistance of an electrolytic composite film containing a predetermined electrolyte is measured. The lower the value of the ion permeability resistance, the higher the ion permeability, preferably 30 mΩ or less, more preferably 25 mΩ or less, and even more preferably 20 mΩ or less.

[0051] In this specification, abrasion resistance can be evaluated by the method described in [Measurement Example 2] mentioned later. A predetermined friction load is applied to the composite membrane for electrolysis, causing a part of the composite membrane for electrolysis to be damaged and fall off, and the weight loss rate is measured. The lower the weight loss rate, the higher the abrasion resistance. A weight loss rate of 1% by mass or less is preferable, 0.5% by mass or less is more preferable, and 0.2% by mass or less is even more preferable.

[0052] In this specification, gas barrier properties can be evaluated by the method described in [Measurement Example 4] mentioned later. An air chamber is provided on the opposite side of the composite membrane for electrolysis with one side immersed in liquid, and the minimum pressure required for gas permeation when the air chamber is pressurized is measured. The higher the pressure value, the higher the gas barrier properties. 2500 mmH ２ O or higher is preferable, 3000 mmH ２ O or higher is more preferable, and 3500 mmH ２ O or higher is even more preferable.

[0053] The composite membrane for electrolysis of the present invention preferably has a plane-symmetric structure with the porous support as the axis of symmetry. By coating both sides instead of one side, adverse effects such as curling caused by differences in shrinkage stress during formation of the porous coating layer can be suppressed.

[0054] As a known method, a method of forming a porous coating layer by solidifying a single coating layer through phase inversion is known. In such a method, generally, phase separation proceeds by diffusion of the non-solvent from the surface of the coating layer that has been brought into contact with the non-solvent toward the inside, so the pore diameter tends to change easily in the film thickness direction, resulting in different pore diameters between the surface and the inside. However, it may be difficult to control the size relationship with only a single coating layer.

[0055] Furthermore, reducing the thickness of the composite membrane for electrolysis is effective for reducing the resistance in a water electrolysis device. However, the thinner the membrane, the faster the diffusion of the non-solvent, so solidification proceeds faster, making it even more difficult to control the pore diameter difference between the inside and the surface of the composite membrane.

[0056] On the other hand, the present invention facilitates adjustment of the average pore diameter of each of the intermediate layer (A) and the surface layer (B) by separating them.

[0057] In the present invention, it is preferable that PB1 and PB2 satisfy the condition 0.9 ≤ PB1 / PB2 ≤ 1.1. That is, the average pore diameters on the surfaces of the first surface layer (B1) and the second surface layer (B2) are approximately the same, meaning that the film is symmetrical on both sides.

[0058] The average pore size PA in the intermediate layer (A) is preferably 0.1 μm or more and 5 μm or less. Setting PA to 0.1 μm or more can further enhance ion permeability, while setting it to 5 μm or less can further enhance the mechanical strength of the electrolytic composite film. From the viewpoint of further enhancing ion permeability, PA is more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. Furthermore, from the viewpoint of further enhancing mechanical strength and gas barrier properties, PA is more preferably 3 μm or less.

[0059] The average pore size PB1 on the surface of the first surface layer (B1) and the average pore size PB2 on the surface of the second surface layer (B2) are preferably 0.05 μm or more and 1 μm or less. Setting PB1 and PB2 to 0.05 μm or more can further improve ion permeability, and setting them to 1 μm or less can further improve gas barrier properties and abrasion resistance. From the viewpoint of further improving ion permeability, PB1 and PB2 are more preferably 0.08 μm or more. Furthermore, from the viewpoint of further improving gas barrier properties and abrasion resistance, PB1 and PB2 are more preferably 0.5 μm or less, and even more preferably 0.3 μm or less.

[0060] In this invention, PA, PB1, and PB2 are measured using a scanning electron microscope (SEM) in the following manner. The electrolytic composite film is dried in a vacuum dryer at a temperature of 60°C for 24 hours, and five randomly selected locations are cut into 5 mm square pieces to form test specimens. One side of the test specimen is designated as the first surface layer (B1), and the opposite side as the second surface layer (B2). For each of (B1) and (B2), the observation magnification is adjusted so that one hole fits within the observation field, and the arithmetic mean of the maximum and minimum lengths of the holes is calculated. The same measurement is performed for 20 randomly selected holes, and their arithmetic mean is calculated. This is done for five test specimens, and PB1 and PB2 are obtained by calculating the arithmetic mean of the five values. For PA, the aforementioned test specimens are cross-sectioned using ion milling, the cross-sections are analyzed with SEM, and the observation magnification is adjusted so that one pore in the intermediate layer (A), excluding the pores in contact with the porous support, fits within the observation field. The arithmetic mean of the maximum and minimum lengths of the pores is calculated, and the same measurement is performed on 20 randomly selected pores. This is measured and calculated for each of the five test specimens, and PA is determined by calculating the arithmetic mean of the five values. In this specification, a pore is defined as one that is continuously surrounded by resin or inorganic particles, and pores that do not fit within the measurement screen are excluded from measurement.

[0061] PA, PB1, and PB2 can be adjusted to the above preferred range by adjusting the phase separation rate. A slower phase separation rate tends to result in smaller pore sizes, while a faster phase separation rate tends to result in larger pore sizes. The phase separation rate can be adjusted by the concentration of the organic solvent in the coating solution, i.e., the viscosity of the coating solution, and the diffusion rate of the non-solvent to be brought into contact with it, i.e., the temperature, concentration, and viscosity of the non-solvent, as described later.

[0062] When the organic solvent concentration in the coating solution is low, the viscosity of the coating solution tends to increase, the phase separation rate slows down, and the pore size tends to decrease. Conversely, when the organic solvent concentration is high, the viscosity of the coating solution decreases, the phase separation rate increases, and the pore size tends to increase.

[0063] Furthermore, when the non-solvent temperature is high, the concentration is high, and the viscosity is low, the phase separation rate is fast, and the pore size tends to be larger. Conversely, when the non-solvent temperature is low, the concentration is low, and the viscosity is high, the phase separation rate is slow, and the pore size tends to be smaller.

[0064] The electrolytic composite film of the present invention preferably has a total film thickness of 30 μm or more and 800 μm or less. From the viewpoint of further increasing mechanical strength, 40 μm or more is more preferable, and 100 μm or more is even more preferable. From the viewpoint of not impairing ion permeability and further improving electrolytic efficiency, 700 μm or less is more preferable, and 600 μm or less is even more preferable.

[0065] <Porous Support> In the present invention, the porous support is used as a substrate to which the coating liquid for the porous coating layer is applied when manufacturing the electrolytic composite membrane of the present invention. Furthermore, the porous support can increase the mechanical strength of the electrolytic composite membrane and improve handling when setting it in an electrolytic cell.

[0066] The porous support preferably has durability against alkaline aqueous solutions at a liquid temperature of 80°C to 120°C. Specific examples of materials include, preferably, one or more of the following: polysulfone, polyethersulfone, polyphenylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyetherketone, polyketone, polyetherimide, polystyrene, polyolefin, polyethylene terephthalate, polyamide, and polycarbonate. From the viewpoint of superior durability, polysulfone, polyphenylsulfone, polytetrafluoroethylene, polyetherketone, or polyphenylene sulfide are more preferred, and polyphenylene sulfide is even more preferred. Two or more of the above materials may be used in combination.

[0067] The porous support is preferably shaped in a way that does not easily reduce ion permeability. Specifically, it is preferably woven, knitted, mesh, or nonwoven fabric. From the viewpoint of further improving ion permeability, mesh or nonwoven fabric is more preferable, and nonwoven fabric is even more preferable.

[0068] The thickness of the porous support is preferably 600 μm or less, and more preferably 500 μm or less. Furthermore, from the viewpoint of further improving mechanical strength, it is preferably 30 μm or more, and more preferably 40 μm or more.

[0069] The weight per unit area (fiber basis weight) of the porous support is set at 20 g / m² to further improve abrasion resistance. ２ The above is preferable, and 30 g / m ２ The above is more preferable. Also, from the viewpoint of not impairing ion permeability, 400 g / m² is preferable. ２ The following is preferable: 300 g / m ２ The following is more preferable: 200 g / m ２ The following are even more preferable.

[0070] The porosity of the porous support is preferably 40% or more, and more preferably 50% or more, from the viewpoint of further improving ion permeability. Furthermore, from the viewpoint of further improving abrasion resistance, it is preferably 90% or less.

[0071] In this specification, the porosity of the porous support was determined by the following method: The apparent volume V (in cm³) per unit area was calculated from the thickness (in cm³) of the porous support × 100 cm × 100 cm. ３ / m ２ ) calculate the weight per unit area (unit: g / m²) ２ ) the density of the material (unit: g / cm³) ３ Divide by () to get the net volume P of the porous support per unit area (unit: cm³). ３ / m ２ The formula used was calculated by dividing P by V, subtracting the result from 1, and rounding the result to the first decimal place.

[0072] The density of the porous support is set to 0.1 g / cm³ from the viewpoint of further improving abrasion resistance. ３ Preferably, it is 0.2 g / cm³ or more. ３ The above is more preferable. Also, from the viewpoint of not impairing ion permeability, 0.9 g / cm³ is preferable. ３ The following is preferable: 0.5 g / cm³ ３ The following are preferable.

[0073] In this specification, the density of a porous support can be determined by the following method: Five pieces of the porous support are cut into 5 cm squares and weighed. The arithmetic mean of the weights of the five pieces is taken as the average weight (in grams). The thickness of each porous support is also measured, and the arithmetic mean of the five pieces is taken as the average thickness (in centimeters). The average volume (in centimeters) is calculated from 5 cm × 5 cm × average thickness (in centimeters). ３ ) calculate the average weight (in grams) and the average volume (in cm³). ３ The value obtained by dividing by ) was rounded to the first decimal place by rounding to the second decimal place.

[0074] Furthermore, when measuring the density of a porous support from an electrolytic composite membrane, the porous coating layer can be removed using a solvent capable of dissolving the polymer in the porous coating layer, thoroughly washed to obtain only the porous support, and then the density of the porous support can be determined using the method described above. (Weight per unit area, 1 m²) ２ The same applies to the surface area of ​​the fibers and the porosity.

[0075] The average fiber diameter of the porous support is preferably 5 μm or more, and more preferably 10 μm or more, from the viewpoint of further improving abrasion resistance. Furthermore, from the viewpoint of reducing the volume occupied by the porous support and not impairing ion permeability, it is preferably 180 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less.

[0076] 1 m of porous support ２ The fiber surface area per square meter is set to increase the contact interface between the intermediate layer (A) and the porous support, thereby further improving abrasion resistance, from the viewpoint of 1 m ２ The above is preferable, 10m ２ The above is more preferable. Also, from the viewpoint of ensuring porosity and further improving ion permeability, 100 m ２ The following is preferable: 50m ２ The following are preferable.

[0077] In this specification, 1 m of porous support ２The fiber surface area per unit area can be determined by the following method: Divide the weight per unit area of ​​the porous support by the density of the material to obtain the volume per unit area, divide by the circular cross-sectional area with the average fiber diameter as the diameter to calculate the total fiber length per unit area, and product the circumference with the average fiber diameter as the diameter and the total fiber length per unit area of ​​the porous support. ２ This was defined as the surface area of ​​the fibers per unit area.

[0078] <Porous Coating Layer> In this invention, the porous coating layer is a functional layer responsible for ion permeability and gas barrier properties.

[0079] From the viewpoint of further improving ion permeability and gas barrier properties, the porous coating layer preferably has a hydrophilic surface. In this specification, having a hydrophilic surface means that the water contact angle is less than 90°, with 0° being the minimum value, and a lower value indicates higher hydrophilicity. The water contact angle on the surface of the electrolytic composite film of the present invention is preferably less than 90°, more preferably 70° or less, and even more preferably 60° or less.

[0080] To further enhance hydrophilicity, the porous coating layer preferably contains inorganic particles of metal oxides and / or metal hydroxides. Specific examples of metal oxides and / or metal hydroxides include titanium dioxide, zirconium oxide, cerium oxide, barium sulfate, aluminum oxide, silica, boehmite, and magnesium hydroxide, with the coating containing one or more inorganic particles. Of these, titanium dioxide or zirconium oxide is preferred, and zirconium oxide is more preferred, from the viewpoint of achieving both durability against alkaline aqueous solutions and a surface hydrophilic effect.

[0081] The shape of such inorganic particles may be spherical, rod-shaped, fibrous, or amorphous. Furthermore, from the viewpoint of not impairing ion permeability, the particle size of the inorganic particles is preferably 10 nm or larger, more preferably 20 nm or larger, and even more preferably 40 nm or larger. From the viewpoint of not impairing gas barrier properties, the particle size of the inorganic particles is preferably 1 μm or smaller, more preferably 800 nm or smaller, and even more preferably 500 nm or smaller.

[0082] The inorganic particles of the metal hydroxide may include layered double hydroxides.

[0083] In this specification, layered double hydroxides may be referred to as "LDHs." Here, LDHs is an abbreviation for Layered Double Hydroxides. Furthermore, LDHs in this specification may contain two or more metals, and also include inorganic compounds referred to as Layered Triple Hydroxides (LTHs), etc.

[0084] The above layered double hydroxide is, for example, the following general formula: (A １ α１ A ２ α２ …) ｘ (B １ β１ B ２ β２ …) １－ｘ (OH) ２ (X ｎ１－ γ１／ｎ１ Y ｎ２－ γ２／ｎ２ …) １－ｘ mH ２ O (A １ A ２ ... are divalent metal ions, and include one or more metals selected from Mg, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Ca, Sr, Ba, Yb, B １ , B ２ ... are trivalent metal ions, and include one or more metals selected from, for example, Al, V, Mn, Fe, Co, Ni, Ga, Y, Nb, Mo, In, La, Ce, Yb. n is a number between 1 and 3, and X ｎ１－ , Y ｎ２－ ... are anions with a valency of 1 to 3, for example, OH － , Cl － NO ３ － , HCO ３ － CO ３ ２－ SO ３ ２－ , HCOO －It contains one or more anions selected from the following. α, β, and γ are numbers greater than or equal to 0 that represent the composition of the layered double hydroxide and satisfy the following relationship: α1 + α2 + ... = β1 + β2 + ... = γ1 + γ2 + ... = 1 m is a number greater than or equal to 0. x is a number greater than 0 and less than 1.) It is a compound represented by the above general formula. Among the layered double hydroxides represented by the above general formula, A is preferably Mg, Ti, Fe, Co, Ni, Ca, Sr, more preferably Mg, Fe, Ca, Ni, and even more preferably Mg, Fe. For the same reason, B is preferably Al, Fe, Co, La, more preferably Al, Fe, and even more preferably Fe. For the same reason, X ｎ１－ , Y ｎ２－ ...is OH － , Cl － NO ３ － , HCO ３ － CO ３ ２－ Preferably, OH － , Cl － NO ３ － More preferably, Cl － That is even more preferable.

[0085] Furthermore, the metal ions A and B may be the same element but with different valencies, for example, Fe ２＋ and Fe ３＋ Examples include layered double hydroxides consisting of the following:

[0086] In the present invention, it is preferable that the layered double hydroxide contains two or more elements selected from the group consisting of magnesium, iron, cobalt, nickel, and aluminum. This improves the alkali resistance of the layered double hydroxide, allowing it to maintain hydrophilicity and high ion permeability over the long term. It is even more preferable that the layered double hydroxide contains two or more elements selected from the group consisting of magnesium, iron, and nickel, as this provides even higher alkali resistance.

[0087] The porous structure of the porous coating layer is preferably formed using a polymer material as a backbone, and the polymer material preferably contains one or more of polysulfone, polyethersulfone, and polyphenylsulfone. From the viewpoint of durability to alkaline aqueous solutions and ease of forming a porous structure, polysulfone or polyphenylsulfone is more preferred.

[0088] The polymer material is preferably soluble in the solvent described later.

[0089] The porous coating layer may contain a third additive such as a surfactant, antioxidant, viscosity modifier, or reinforcing filler.

[0090] In the present invention, the porous coating layer is divided into an intermediate layer (A) and a surface layer (B). From the viewpoint of minimizing the impairment of ion permeability, it is preferable that the thickness of the surface layer (B) is less than or equal to the thickness of the intermediate layer (A). Furthermore, from the viewpoint of further improving the adhesion between the porous support and the intermediate layer (A), it is preferable that the thickness of the intermediate layer (A) is greater than or equal to the thickness of the porous support.

[0091] In the present invention, the first porous coating layer contains inorganic particles and a polymer, and the second porous coating layer also contains inorganic particles and a polymer. Preferably, the ratio of the weight of inorganic particles to the weight of polymer, RX, in the first porous coating layer and the second porous coating layer is within the range of 3.3 to 15. The value of RX in B1 and the value of RX in B2 may be different.

[0092] RX is the ratio of the weight of inorganic particles to the weight of polymer, indicating the amount of binder polymer used to bind the inorganic particles. Under conditions where there are more inorganic particles than polymer, the inorganic particles are more easily exposed on the surface of the porous coating layer, making it easier to obtain excellent hydrophilicity. A hydrophilic surface contributes to further enhancing ionic conductivity. In addition, the electrolyte can more easily penetrate into the pores of the electrolytic composite film, suppressing the adhesion of air bubbles and thereby increasing resistance during operation and improving gas barrier performance. For example, if there is more polymer than inorganic particles, the inorganic particles tend to become embedded in the polymer, making it difficult to obtain a sufficient hydrophilic effect. From the viewpoint of further enhancing ionic conductivity and gas barrier performance, an RX of 3.3 or higher is preferable, and 5 or higher is more preferable.

[0093] On the other hand, if there is too little polymer relative to the inorganic particles, bonding tends to be insufficient, which can lead to a decrease in wear resistance. From the viewpoint of further improving the wear resistance of the coating layer, RX is preferably 15 or less, and more preferably 10 or less.

[0094] Similarly, in the present invention, the first intermediate layer (A1) contains inorganic particles and a polymer, and the second intermediate layer (A2) also contains inorganic particles and a polymer. In the first intermediate layer (A1) and the second intermediate layer (A2), the value RY, which is the ratio of the weight of inorganic particles to the weight of polymer, is preferably in the range of 3.3 to 15. The preferred range of RY and the reasons for it are the same as for RX, with RY preferably being 3.3 or higher, and more preferably 5 or higher. Furthermore, RY is preferably 15 or lower, and more preferably 10 or lower.

[0095] When PB1 and PB2 are small and PA is large, and RY is below 3.3, the penetration rate of the non-solvent slows down, which slows down the solidification rate of the intermediate layer (A), and tends to create large pores inside. In such cases, electrolyte may accumulate in the internal voids, and although this may not seem to have much effect on the ion permeation resistance, it does affect the actual ion permeation rate. For example, in carbon dioxide electrolysis, this is thought to have an effect such as a decrease in the ion supply rate, which reduces the CO generation selectivity.

[0096] It is preferable that RX and RY satisfy the condition 0.8 ≤ RX / RY ≤ 1.2. RX / RY represents the degree of difference in the composition ratio of each layer between the intermediate layer (A) and the surface layer (B). If the composition ratios of the intermediate layer (A) and the surface layer (B) are significantly different, an interface is more likely to form between the layers, raising concerns about delamination during manufacturing. Therefore, it is preferable to keep them within the above range.

[0097] In this specification, when analyzing RX and RY from a product, the surface layer (B) is considered to be the area from the surface to a depth of 1 / 10 of the total film thickness, and this is extracted as the sample for analyzing RX. In addition, the intermediate layer (A) is considered to be the area from the center in the film thickness direction of the porous support to a depth of 1 / 10 of the total film thickness in each surface direction, and this is extracted as the sample for analyzing RY.

[0098] Each sample for analysis is dissolved in a solvent capable of dissolving the polymer constituting the porous coating layer, and then filtered to separate the polymer components from the inorganic particles and porous support. After thoroughly washing the filtrate with the solvent, the porous support is removed, and the weight after vacuum drying is weighed to determine the weight of the inorganic particles. The filtrate and washing solution are then weighed after the solvent is removed and the mixture is vacuum dried to determine the weight of the polymer.

[0099] <Method for Manufacturing an Electrolytic Composite Film> [In the case of a single coating] One embodiment of the method for manufacturing an electrolytic composite film of the present invention is a method for manufacturing an electrolytic composite film, comprising, in this order: preparing a coating solution containing an organic solvent solution of a polymer and inorganic particles; coating both sides of a porous support with the coating solution to obtain a coated sheet; and contacting the coated sheet with the non-solvent of the coating solution to form a first surface layer (B1) and a second surface layer (B2), as well as a first intermediate layer (A1) and a second intermediate layer (A2).

[0100] As mentioned above, under conditions where the phase separation rate is slow, a dense layer with small pore sizes is formed near the surface during solidification, while a layer with large pore sizes tends to form in the interior. Under these conditions, the electrolytic composite film of the present invention can be obtained by solidifying a coating solution applied to both sides of a porous support.

[0101] [In the case of two-coating] Another aspect of the method for manufacturing an electrolytic composite film of the present invention includes, in this order, the steps of preparing a coating solution containing an organic solvent solution of a polymer and inorganic particles, and coating both sides of a porous support with the coating solution to obtain a coated sheet, and then bringing the coated sheet into contact with the non-solvent of the coating solution to form a first surface layer (B1) and a second surface layer (B2), as well as a first intermediate layer (A1) and a second intermediate layer (A2).

[0102] In this method, since the intermediate layer (A) is coated twice, the pore size of each layer can be easily controlled even under conditions where phase separation is rapid and the formation of a dense surface layer is difficult.

[0103] The manufacturing method of the present invention may be a single-sheet manufacturing method, or it may be a continuous manufacturing method such as a roll-to-roll method.

[0104] The following describes each step.

[0105] (Preparation of coating solution) The coating solution is a precursor of the porous coating layer of the present invention. The coating solution contains the polymer material described above, the inorganic particles described above, and an organic solvent.

[0106] The solvent for the coating solution is preferably one that can dissolve the aforementioned polymer material, such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N,N-dimethylacetamide (DMAc). These solvents are preferred because they are soluble in water and water can be used as a non-solvent for the polymer.

[0107] The concentration of the organic solvent in the coating solution is preferably 10% by weight or more and 90% by weight or less. A concentration of 10% by weight or more can further enhance ion permeability, while a concentration of 90% by weight or less can further enhance abrasion resistance and gas barrier properties. A lower concentration of the organic solvent tends to result in a smaller average pore size in the layer, leading to higher gas barrier properties and abrasion resistance. Conversely, a higher concentration of the organic solvent tends to result in a larger average pore size in the layer, leading to higher ion permeability. Therefore, it is preferable that the concentration of the organic solvent in the coating solution for the intermediate layer (A) is higher than the concentration of the organic solvent in the coating solution for the surface layer (B).

[0108] Known methods can be used to dissolve polymer materials in organic solvents, including methods that involve dissolving them using a mechanical stirrer or disperser while heating.

[0109] In preparing the coating solution, methods such as using an automatic mortar and pestle, a three-roll mill, a bead mill, a planetary ball mill, a homogenizer, a homodisperser, a homomixer, or a planetary mixer can be used to improve the dispersibility of inorganic particles.

[0110] The coating solution may contain a pore-forming agent to facilitate control of pore size. Suitable pore-forming agents include ethylene glycol, polyethylene glycol, glycerol, polyvinyl alcohol, and polyvinylpyrrolidone.

[0111] The coating solution may further contain additives such as antioxidants, anti-settling agents, and viscosity modifiers.

[0112] From the viewpoint of suppressing clumping of inorganic particles, a method is preferred in which an organic solvent dispersion of inorganic particles and an organic solvent solution of polymer material are prepared separately and then mixed.

[0113] The viscosity of the coating liquid is preferably between 1,000 mPa·s and 1,000,000 mPa·s in order to further improve coating properties.

[0114] The coating solution for the intermediate layer (A) and the coating solution for the surface layer (B) do not have to be the same. Also, the coating solutions for the first and second surfaces of the surface layer (B) may be different.

[0115] (Intermediate layer coating) Next, the coating liquid is coated onto both sides of the porous support to form a first intermediate layer (A1) and a second intermediate layer (A2). Known methods can be used for coating, including a method using two opposing slit dies, and a method in which the coating liquid is placed between two comma coaters and the porous support is passed between the comma coaters. From the viewpoint of good accuracy of coating film thickness, the method using slit dies is preferred, and from the viewpoint of increasing manufacturing speed, comma coaters are preferred.

[0116] For the intermediate layers (A1) and (A2), coating solutions of the same composition may be used, or coating solutions of different compositions may be used.

[0117] After applying the intermediate layer coating solution once, an operation to reduce the fluidity of the coating film may be performed before applying the second coat. Performing such an operation can prevent the second coating solution from mixing with the first intermediate layer coating solution. Examples of such operations include hot air drying, steam spraying, and immersion in a solidification bath. For example, if the viscosity of the coating solution is high and it is difficult to mix the first coating film with the second surface coating solution, such an operation may not be necessary.

[0118] In the case of a single coating, the porous coating layer formation procedure described later can be performed after the application of the intermediate layer coating solution. In the case of a double coating, the second coating is performed in the same manner as the first intermediate layer coating. The coating method does not have to be the same as the first coating method. The second coating may use the same composition of coating solution as the first intermediate layer coating, or a coating solution with a different composition may be used. Furthermore, within the range that satisfies the condition 0.9 ≤ PB1 / PB2 ≤ 1.1, coating solutions with different compositions may be used for the surface layer (B1) and the surface layer (B2).

[0119] (Formation of a porous coating layer) Next, a non-solvent is brought into contact with the coating liquid to cause phase inversion and solidification, thereby forming a porous coating layer. As the non-solvent diffuses into the coating film, the polymer material in the coating liquid undergoes phase separation, and a porous structure is formed.

[0120] As the non-solvent, a solvent that is miscible with the aforementioned organic solvent and does not dissolve the polymer material is preferred. Suitable examples include water, methanol, ethanol, propanol, isopropanol, and acetone, and a mixture of two or more solvents may also be used. Furthermore, a mixture of these non-solvents and the aforementioned organic solvent may be used to adjust the phase separation rate and control the pore size. In addition, the solvent may contain water-soluble polymers, thickeners such as polysaccharides, and surfactants.

[0121] Methods for contacting the material with a non-solvent include immersion in a solidification bath and spraying. Immersion in a solidification bath is preferred from the viewpoint of being able to easily control the temperature at which the material comes into contact with the non-solvent.

[0122] When contacting the non-solvent, the temperature of the non-solvent is preferably between 20°C and 90°C. The higher the temperature, the faster the phase separation rate tends to be, and from the viewpoint of easier control, a temperature of 80°C or lower is more preferable. Also, at low temperatures, the phase separation rate is slow and requires a long contact time, so a temperature of 40°C or higher is more preferable.

[0123] Before bringing the non-solvent and the coating solution into contact, operations such as hot air drying or steam spraying may be performed.

[0124] After the porous coating layer is formed, it is preferable to perform washing to remove any residual organic solvents or precipitated particles. Alternatively, post-processing such as pressing may be included.

[0125] <Use of electrolytic composite membrane> The electrolytic composite membrane of the present invention can be preferably used in electrolytic devices, including alkaline water electrolytic devices and carbon dioxide electrolytic devices. Examples of electrolytic devices include those that include an anode, a cathode, and the electrolytic diaphragm of the present invention between them.

[0126] Suitable materials for the anode and cathode include stainless steel, titanium, nickel, or nickel alloys, and it is preferable that they have a highly permeable shape such as a mesh. Alternatively, carbon materials with both permeability and conductivity, such as catalyst-coated carbon paper or carbon felt, may be used as electrodes.

[0127] The alkaline water electrolysis apparatus equipped with the electrolytic diaphragm of the present invention can be used in a known manner. For example, it can be used by filling the alkaline water electrolysis apparatus equipped with the electrolytic diaphragm of the present invention with an aqueous potassium hydroxide solution or the like as the electrolyte, and applying an electric current to the anode and cathode. The concentration of potassium hydroxide or the like in the electrolyte is preferably 20% by weight or more from the viewpoint of further improving electrolysis efficiency. The temperature during water electrolysis is preferably 50°C or higher, and more preferably 80°C or higher, from the viewpoint of further improving electrolysis efficiency. On the other hand, it is preferably 120°C or lower from the viewpoint of safety and improving the durability of the components.

[0128] The performance of the alkaline water electrolysis apparatus equipped with the electrolytic diaphragm of the present invention can be evaluated by the method described in [Measurement Example 5] below, and the voltage values ​​when operated at a predetermined current density were compared. A lower voltage value indicates a lower resistance component derived from the electrolytic composite membrane. The voltage value is preferably 2.1V or less, more preferably 2.0V or less, and even more preferably 1.9V or less.

[0129] The carbon dioxide electrolytic apparatus equipped with the electrolytic diaphragm of the present invention can be used in a known manner. For example, the anode of the carbon dioxide electrolytic apparatus equipped with the electrolytic diaphragm of the present invention can be filled with an aqueous potassium bicarbonate solution or the like as the electrolyte, carbon dioxide can be circulated through the cathode as the reaction gas, and a voltage can be applied to the anode and cathode. The concentration of potassium bicarbonate or the like in the electrolyte is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and even more preferably 1% by weight or more, from the viewpoint of further increasing the electrolysis efficiency. The temperature during carbon dioxide electrolysis is preferably 30°C or higher from the viewpoint of further increasing the electrolysis rate. On the other hand, the temperature is preferably 90°C or lower from the viewpoint of increasing the reaction selectivity of carbon dioxide.

[0130] The performance of the carbon dioxide electrolytic apparatus equipped with the electrolytic diaphragm of the present invention can be evaluated by the method described in [Measurement Example 6] below, and the current density values ​​when operated at a predetermined voltage were compared. A higher current density indicates a lower resistance component originating from the electrolytic composite membrane. The current density value was 250 mA / cm². ２ The above is preferable, and 275 mA / cm². ２ The above is more preferable, with a current of 300 mA / cm².２ The above is even more preferable.

[0131] Furthermore, the carbon monoxide concentration at the gas outlet was measured, and the proportion of the current density value that contributes to CO generation was calculated and compared.

[0132] The electrolytic diaphragm of the present invention can be incorporated into a bipolar electrolytic cell, and by stacking multiple cells with the aforementioned electrolytic device as one cell, a large electrolytic cell can be formed, providing hydrogen production equipment and carbon dioxide electrolysis equipment suitable for industrial use. Such hydrogen production equipment and carbon dioxide electrolysis equipment may include, for example, an electrolytic device containing the electrolytic composite membrane of the present invention, and ancillary equipment such as a gas-liquid separation tank, a condenser, a mist separator, and a gas separator.

[0133] The present invention will be described below with reference to examples.

[0134] First, the evaluation methods for each example and comparative example will be explained.

[0135] [Measurement Example 1] Average pore size: The electrolytic composite films prepared in the examples and comparative examples were analyzed by the following method.

[0136] The electrolytic composite film was dried at 60°C for 24 hours using a vacuum dryer, and five randomly selected locations were cut into 5 mm square pieces to form test specimens. One side of each test specimen was designated as the first surface layer (B1), and the opposite side as the second surface layer (B2). Using a scanning electron microscope (SEM) S-5500 (manufactured by Hitachi High-Technologies Corporation), the observation magnification was adjusted so that one hole fit within the observation field for both (B1) and (B2), and the arithmetic mean of the maximum and minimum hole lengths was calculated. This measurement was performed similarly for 20 randomly selected holes, and the arithmetic mean was calculated to obtain the average pore diameter per test specimen. This process was repeated for five test specimens, and PB1 and PB2 were determined by calculating the arithmetic mean of the average pore diameters for the five test specimens.

[0137] For the average pore diameter PA in the intermediate layer (A), cross-sectioning is performed on the aforementioned test piece using ion milling, the cross-section is analyzed by SEM, and for the intermediate layer (A) excluding pores at the site in contact with the porous support, the observation magnification is adjusted so that one pore fits within the observation field. The arithmetic average of the maximum length and the minimum length of the pore is obtained, the same measurement is performed on 20 randomly selected pores, and the arithmetic average thereof is calculated to obtain the average pore diameter per test piece. This was repeated for 5 test pieces, and PA was obtained by calculating the arithmetic average of the average pore diameters of the 5 test pieces.

[0138] In the present specification, a pore is defined as a structure completely surrounded by resin or inorganic particles without interruption, and pores that do not fit within the measurement screen are excluded from the measurement targets.

[0139] [Measurement Example 2] Abrasion Resistance The composite membranes for electrolysis produced in the Examples and Comparative Examples were washed with distilled water to clean the surfaces, after wiping off excess moisture, they were immersed in liquid nitrogen to freeze, and after drying the composite membranes for electrolysis at a temperature of 60°C for 24 hours using a vacuum dryer, the composite membranes were cut into a size of 3 cm × 12 cm to obtain samples for abrasation resistance testing. The weight of the sample before testing was weighed and recorded. Using a Scott crepe-resistance tester CF-20NW (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), the sample was fixed to two gripping parts spaced 20 mm apart, the pressing load of both grips was set to 9.8 N, the friction speed was set to 120 times / min, and reciprocating friction was performed 1000 times over a distance of 40 mm. The weight of the sample after friction was weighed, the weight loss rate was calculated, the value was rounded to one decimal place and recorded. The weight loss rate was used as an index of abrasion resistance, and it was considered that the smaller the weight loss rate, the higher the abrasion resistance.

[0140] [Measurement Example 3] Ion Permeability Ion permeability was measured using a self-made jig. For this measurement, the composite membrane for electrolysis was used in a state after being immersed in a 30 wt% potassium hydroxide aqueous solution for 24 hours. In the center 4 cm ２An electrolytic composite film was sandwiched between two 2 mm thick PTFE spacers with openings. This was further sandwiched between two nickel mesh electrodes, and the mixture was immersed in a PTFE tank filled with a 30 wt% potassium hydroxide aqueous solution. The PTFE tank was heated in a water bath to adjust the temperature of the potassium hydroxide solution inside to 60°C. The electrodes were connected to a potentiostat, and the resistance value was determined from the smallest real axis intercept of the Nyquist plot obtained by sweeping the frequency in the range of 100 to 10 kHz with an AC voltage of amplitude 10 mV. This resistance value was used as an indicator of ion permeability; a lower resistance value indicated higher ion permeability.

[0141] [Measurement Example 4] Using a gas barrier bubble point tester (Sartorius Stedim Japan, "Sartocheck Junior BP-Plus"), an electrolytic composite membrane cut to an 8 cm square was left to stand in pure water for 24 hours, then set in a measuring holder and measured. Under conditions of 25°C, the upper side separated by the electrolytic composite membrane was pressurized, and the nitrogen pressure at which bubbles were generated from the lower side at a rate of 150 mL / min was measured and defined as the bubble point. A higher bubble point value was considered to indicate higher gas barrier performance.

[0142] [Measurement Example 5] Alkaline Water Electrolysis Characteristics The alkaline water electrolysis characteristics were measured using a zero-gap cell (Dioxide Materials, "5cm"). ２Measurements were taken using an AEM Water Electrolyzer, nickel fiber electrodes (Dioxide Materials, "GDL-Ni Fiber Paper"), and a potentiometer / galvanostat (BioLogic, "HCP-803"). A 2.5 cm square nickel fiber electrode was cut for the cathode, a 3.0 cm square nickel fiber electrode for the anode, and a 3.5 cm square electrolytic composite film, impregnated in a 30 wt% potassium hydroxide aqueous solution for more than 2 hours, was cut to serve as a diaphragm. A 7.5 cm square PTFE gasket was prepared with equal thickness for each electrode and electrolytic composite film, and had an opening in the center with a side 0.2 cm longer than the sides of each electrode and electrolytic composite film. A zero-gap cell was constructed by stacking each layer in the following order: anode plate, 3.0 cm square nickel fiber electrode and gasket, composite membrane and gasket, 2.5 cm square nickel fiber electrode and gasket, and cathode plate, with each electrode and composite membrane positioned within the opening of the gasket, and fastening them with a torque pressure of 3.0 N·m. The counter electrode and reference electrode of the potentiometer-galvanostat were connected to the cathode plate, and the working electrode to the anode plate. Rubber heaters were attached to the outer surfaces of the cathode plate and anode plate and heated to 80°C. A 30% by weight potassium hydroxide aqueous solution at room temperature was flowed through the serpentine channels of the cathode plate and anode plate at a flow rate of 3.0 mL / min, supplying the solution to the nickel fiber electrode and composite membrane. After one hour, cyclic voltammetry (0.0–2.0 V (reference to counter electrode), 100 mV / s, 50 cycles) was performed using a potentiometer-galvanostat, followed by linear sweep voltammetry (0.05–2.0 V (reference to counter electrode), 10 mV / s, sweeping towards the anode). The current value of the obtained current-voltage curve was measured at the minimum electrode area of ​​6.25 cm². ２ By dividing by 300 mA / cm², a current density-voltage curve is created. ２ The cell voltage was evaluated.

[0143] [Measurement Example 6] Carbon Dioxide Electrolysis Characteristics The carbon dioxide electrolysis characteristics were measured using a zero-gap cell (Dioxide Materials, "5cm"). ２ CO ２Measurements were taken using an "Electrolyzer" (electron), a gas diffusion electrode with a cathode catalyst layer (Dioxide Materials, "Cathode electrode for carbon dioxide electrolyzer"), a gas diffusion electrode with an anode catalyst layer (Dioxide Materials, "Anode electrode for carbon dioxide electrolyzer"), and a potentiometer / galvanostat (BioLogic, "HCP-803"). A 2.5 cm square gas diffusion electrode with a cathode catalyst layer and a 3 cm square gas diffusion electrode with an anode catalyst layer were cut out, and a 3.5 cm square composite film impregnated in a 1% by weight potassium bicarbonate aqueous solution for more than 2 hours was cut out. A 7.5 cm square PTFE gasket was prepared with equal thickness for each electrode and composite film, and an opening in the center with a side 0.2 cm longer than the sides of each electrode and composite film. Each electrode and composite film was placed within the opening of the gasket, and the anode electrode plate, gas diffusion electrode with anode catalyst layer and gasket, composite film and gasket, gas diffusion electrode with cathode catalyst layer and gasket, and cathode electrode plate were stacked in that order and fastened with a torque pressure of 3.0 N·m to construct a zero-gap cell. Rubber heaters were attached to the outer surfaces of the cathode electrode plate and anode electrode plate and heated to 75°C. A 1% by weight aqueous solution of potassium bicarbonate was flowed through the anode electrode plate and the gas diffusion electrode with an anode catalyst layer at a flow rate of 3.0 mL / min, and carbon dioxide gas was flowed through the cathode electrode plate and the gas diffusion electrode with a cathode catalyst layer at a flow rate of 50 mL / min at 1.1 atm. Rubber heaters were attached to the cathode electrode plate and the anode electrode plate and heated to 75°C. After 1 hour, a cell voltage of 3.5 V was applied using a potentiometer-galvanostat. The current value of the potentiometer-galvanostat after 1 hour was measured over the cathode electrode area of ​​6.25 cm². ２ The current density of the entire electrolytic reaction was calculated by dividing by [the specified factor]. In addition, the carbon monoxide portion current density was calculated using the following formula from the carbon monoxide concentration of the outlet gas measured using a gas sampler (Gastec Co., Ltd., "GV-100") and gas detection tubes (Gastec Co., Ltd., "Carbon Monoxide 1HH", "Carbon Monoxide 1H", "Carbon Monoxide 1LM").

[0144] Partial current density of carbon monoxide [mA / cm ２ = Current density [mA / cm ２ × (carbon monoxide concentration [(mol / mol)%] × gas flow rate [L / s]) / ((current value [C / s] / Faraday constant [C / mol]) × molar volume [L / mol])).

[0145] The calculated partial current density of carbon monoxide is divided by the current density of the entire electrolytic reaction to obtain the ratio, and the result is rounded to one decimal place to calculate the CO selectivity (%).

[0146] [Porous Support] Details of the porous supports used in the Examples and Comparative Examples are as follows.

[0147] Herein, PPS: polyphenylene sulfide (density 1.35 g / cm ３ ), PTFE: polytetrafluoroethylene (density 2.17 g / cm ３ ), PP: polypropylene (density 0.9 g / cm ３ ).

[0148] PPS mesh 1: thickness 300 μm, weight per unit area 80 g / m ２ , density 0.27 (g / cm ３ ), average fiber diameter 190 μm, 1 m ２ fiber surface area per 1.2 m ２ , porosity 80% PPS mesh 2: thickness 40 μm, weight per unit area 11 g / m ２ , density 0.28 (g / cm ３ ), average fiber diameter 20 μm, 1 m ２ fiber surface area per 0.28 m ２ , porosity 80% PPS nonwoven fabric 1: thickness 400 μm, weight per unit area 100 g / m ２ , density 0.27 (g / cm ３ ), average fiber diameter 15 μm, 1 m ２ fiber surface area per 20 m ２ , porosity 81% PPS nonwoven fabric 2: thickness 220 μm, weight per unit area 55 g / m ２ , density 0.25 (g / cm ３ ), average fiber diameter 10 μm, 1 m ２ fiber surface area per 16 m ２PPS fabric with 81% porosity: 500 μm thick, weight per unit area: 460 g / m² ２ , density 0.92 (g / cm ３ ), average fiber diameter 9 μm, 1 m ２ Fiber surface area per square meter: 150 m² ２ 32% void ratio PTFE mesh: 240 μm thickness, weight per unit area 270 g / m ２ , density 1.12 (g / cm ３ ), average fiber diameter 120 μm, 1 m ２ Fiber surface area per square meter: 4.1 m² ２ 48% porosity PP nonwoven fabric: 250 μm thick, weight per unit area 30 g / m² ２ , density 0.12 (g / cm ３ ), average fiber diameter 20 μm, 1 m ２ Fiber surface area per square meter: 6.7 m² ２ , porosity 87% [Preparation Example 1] 71.5 g of N-methylpyrrolidone and 1 g of glycerol were weighed into a separable flask, sealed tightly, and heated to 90°C while stirring at a speed of 300 rpm using a mechanical stirrer. Then 13 g of BASF polysulfone pellets (product number S6010) were added, and the temperature was further increased to 120°C and stirred to dissolve. After confirming that the polysulfone was completely dissolved, 41 g of zirconia particles (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and after stirring at 2000 rpm for 30 minutes using a rotary-orbit mixer, degassing was performed at 2200 rpm for 2 minutes to prepare coating solution (1).

[0149] [Preparation Example 2] Coating solution (2) was prepared by adding 10 g of N-methylpyrrolidone to coating solution (1) and diluting it.

[0150] [Preparation Example 3] Coating solution (3) was prepared in the same manner as in Preparation Example 1, except that the N-methylpyrrolidone was changed to 48 g, glycerol to 6 g, polysulfone pellets to 10 g, and zirconia particles to 36 g.

[0151] [Preparation Example 4] Coating solution (4) was prepared in the same manner as in Preparation Example 1, except that the amount of N-methylpyrrolidone was changed to 36.3 g, glycerol to 4.5 g, polysulfone pellets to 3.3 g, and zirconia particles to 32.5 g.

[0152] [Preparation Example 5] Coating solution (5) was prepared in the same manner as in Preparation Example 1, except that the amount of N-methylpyrrolidone was changed to 40.9 g, glycerol to 3.3 g, polysulfone pellets to 4.67 g, and zirconia particles to 24.5 g.

[0153] [Preparation Example 6] A coating solution (6) was prepared in the same manner as in Preparation Example 1, except that 56 g of N-methylpyrrolidone, 5 g of glycerol, 3 g of BASF polyphenylsulfone pellets (product number P3010) instead of polysulfone pellets, and 36 g of zirconia particles were used.

[0154] [Preparation Example 7] Coating solution (7) was prepared in the same manner as in Preparation Example 6, except that the amount of N-methylpyrrolidone was changed to 57 g and the amount of polyphenylsulfone pellets to 2 g.

[0155] [Preparation Example 8] A coating solution (8) was prepared in the same manner as in Preparation Example 1, except that the N-methylpyrrolidone was changed to 48 g, glycerol to 2 g, polysulfone pellets to 5 g, and zirconia particles to 24 g.

[0156] The porous supports used in each example and comparative example are shown in Table 1, and the combinations of coating solutions used in each example and comparative example are shown in Table 2.

[0157]

[0158]

[0159] [Example 1] (First Coat) The PPS mesh 1 described above was cut into 15 cm squares to form a porous support. Two metal materials were prepared, each having a trapezoidal cross-section with a depth, where the short side and long side are parallel, and the short side and width, and the long side and width, are perpendicular to each other. These were placed with a 500 μm gap between them, with the surfaces formed by the short side and depth facing each other. The part corresponding to the hypotenuse of the trapezoidal cross-section formed a tapered liquid receiver, and the space between the surfaces formed by the short side and depth of the two metal materials was made into a slit. The coating liquid (2) described above was placed in the liquid receiver. The porous support was passed through the slit at a speed of 0.5 m / min to coat both sides. Steam at a temperature of 60°C was sprayed onto the coated surface to solidify the surface and obtain a porous support having an intermediate layer (A).

[0160] (Second coating) Next, the coating liquid (1) described above was placed in slits spaced 900 μm apart. The material was passed through the slits at a speed of 1 m / min to coat both sides.

[0161] (Formation of the coating layer) The film was then immediately immersed in pure water at 20°C and left to stand for 30 minutes to completely solidify the coating layer, thereby obtaining an electrolytic composite film.

[0162] (Washing) The obtained electrolytic composite membrane was rinsed three times with pure water and then immersed in pure water and stored under refrigeration.

[0163] Measurements 1 to 6 were performed on the obtained electrolytic composite films, and the results are shown in Table 3.

[0164] Compared to Example 2, RX and RY fell slightly outside the preferred range, resulting in a slight decrease in wear resistance, ion permeability, and gas barrier properties.

[0165] Furthermore, the CO selectivity in carbon dioxide electrolysis decreased compared to Example 2. It is possible that the large internal pore size and slightly reduced ion permeability led to ions accumulating in the internal voids, slightly decreasing the ion supply rate, which resulted in the reduced CO selectivity.

[0166] [Example 2] An electrolytic composite film was prepared in the same manner as in Example 1, except that the coating solution used in the first coat of Example 1 was changed to coating solution (3), and the coating solution used in the second coat was also changed to coating solution (3). Measurements 1 to 6 were performed on the obtained electrolytic composite film, and the results are shown in Table 3. Compared to Example 1, the abrasion resistance, ion permeability, and gas barrier properties were improved as RX and RY fell within the preferred range.

[0167] [Example 3] (Double-sided coating) The PPS mesh 2 described above was cut into 15 cm squares to form a porous support. The spacing of the slits used in Example 1 was changed to 100 μm, and the coating liquid (3) was placed in the liquid receiver. The porous support was passed through the slits at a speed of 0.5 m / min to coat both sides.

[0168] (Formation of the coating layer) The film was then immediately immersed in pure water at 20°C and left to stand for 30 minutes to completely solidify the coating layer, thereby obtaining an electrolytic composite film.

[0169] (Washing) The obtained electrolytic composite membrane was rinsed three times with pure water and then immersed in pure water and stored under refrigeration.

[0170] Measurements 1 to 6 were performed on the obtained electrolytic composite membrane, and the results are shown in Table 3. Compared to Example 2, the ion permeability was improved by thinning the porous support, resulting in improved properties for alkaline water electrolysis and carbon dioxide electrolysis.

[0171] [Example 4] An electrolytic composite film was prepared in the same manner as in Example 3, except that the porous support was changed to a PTFE mesh and the slit spacing was changed to 500 μm in the double-sided coating of Example 3. Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. Compared to Example 3, the void ratio and other properties decreased due to the change in the porous support to a PTFE mesh, resulting in a slight decrease in ion permeability, but sufficiently practical performance was obtained.

[0172] [Example 5] An electrolytic composite film was prepared in the same manner as in Example 3, except that the porous support was changed to PPS nonwoven fabric 1, the slit spacing was changed to 500 μm, and the coating solution was changed to coating solution (4). Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. Compared with Examples 1 to 4, the coating solution composition was changed to improve the coating properties on the PPS nonwoven fabric. The porous support with a fine thread diameter and the coating layer were firmly bonded, resulting in high abrasion resistance, and the ion permeability and gas barrier properties were greatly improved, resulting in excellent alkaline water electrolysis properties and carbon dioxide electrolysis properties.

[0173] [Example 6] An electrolytic composite film was prepared in the same manner as in Example 3, except that the porous support was changed to PPS nonwoven fabric 2, the slit spacing was changed to 250 μm, and the coating solution was changed to coating solution (5). Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. Compared to Example 5, the porous support was changed to a thinner one, and the ion permeability was further improved, resulting in high performance. Although the gas barrier performance decreased slightly due to the reduction in film thickness, sufficiently practical performance was obtained.

[0174] [Example 7] An electrolytic composite film was prepared in the same manner as in Example 3, except that the porous support was changed to PP nonwoven fabric, the slit spacing was changed to 300 μm, and the coating solution was changed to coating solution (5). Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. Compared with Example 6, high performance was obtained even when the porous support was changed to PP nonwoven fabric.

[0175] [Example 8] An electrolytic composite film was prepared in the same manner as in Example 3, except that the porous support was changed to a PPS fabric, the slit spacing was changed to 600 μm, and the coating solution was changed to coating solution (5). Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. Compared with Examples 6 and 7, changing the porous support to a PPS fabric resulted in a slight decrease in ion permeability due to the effects of increased thickness and decreased porosity, but sufficient abrasion resistance and gas barrier properties were obtained.

[0176] [Example 9] (Double-sided coating) The above PPS nonwoven fabric 1 was cut into 15 cm squares to form a porous support. The spacing of the slits used in Example 1 was changed to 500 μm, and the coating liquid (4) was placed in the liquid receiver. The porous support was passed through the slits at a speed of 0.5 m / min to coat both sides.

[0177] (Formation of the coating layer) A porous support coated on both sides was placed 15 cm from the surface of pure water heated to 60°C, exposed to steam for 5 seconds, and then immediately immersed in pure water at 0°C. After standing for 30 minutes, the coating layer was completely solidified to obtain an electrolytic composite film.

[0178] (Washing) The obtained electrolytic composite membrane was rinsed three times with pure water and then immersed in pure water and stored under refrigeration.

[0179] Measurements were performed on the obtained electrolytic composite film according to Measurement Examples 1 to 6, and the results are shown in Table 3. Compared to Example 5, the average pore size was reduced by adjusting the solidification conditions, but sufficient performance was obtained.

[0180] [Example 10] An electrolytic composite film was prepared in the same manner as in Example 9, except that the contact time with steam was changed to 10 seconds during the formation of the coating layer. Measurements 1 to 6 were performed, and the results are shown in Table 3. Compared to Example 9, the average pore size was slightly increased by adjusting the solidification conditions, but sufficient performance was obtained.

[0181] [Example 11] An electrolytic composite film was prepared in the same manner as in Example 9, except that the contact time with steam was changed to 20 seconds during the formation of the coating layer. Measurements 1 to 6 were performed, and the results are shown in Table 3. Compared to Example 10, the average pore size was slightly increased by adjusting the solidification conditions, but sufficient performance was obtained.

[0182] [Example 12] (Double-sided coating) The above PPS nonwoven fabric 1 was cut into 15 cm squares to form a porous support. The spacing of the slits used in Example 1 was changed to 500 μm, and the coating liquid (5) was placed in the liquid receiver. The porous support was passed through the slits at a speed of 0.5 m / min to coat both sides.

[0183] (Formation of the coating layer) The film was then immediately immersed in pure water at 40°C and left to stand for 30 minutes to completely solidify the coating layer, thereby obtaining an electrolytic composite film.

[0184] (Washing) The obtained electrolytic composite membrane was rinsed three times with pure water and then immersed in pure water and stored under refrigeration.

[0185] Measurements were performed on the obtained electrolytic composite film in Measurement Examples 1 to 6, and the results are shown in Table 3. Compared to Example 5, the average pore size was increased by adjusting the solidification conditions, but sufficient performance was obtained.

[0186] [Example 13] An electrolytic composite film was prepared in the same manner as in Example 12, except that the temperature of the pure water used for immersion was changed to 60°C during the formation of the coating layer. Measurements 1 to 6 were performed, and the results are shown in Table 3. Compared to Example 12, the average pore size was further increased by adjusting the solidification conditions, but sufficient performance was obtained.

[0187] [Example 14] An electrolytic composite film was prepared in the same manner as in Example 12, except that the temperature of the pure water used for immersion was changed to 80°C during the formation of the coating layer. Measurements 1 to 6 were performed, and the results are shown in Table 3.

[0188] [Example 15] (Double-sided coating) The above PPS nonwoven fabric 1 was cut into 15 cm squares to form a porous support. The spacing of the slits used in Example 1 was changed to 500 μm, and the coating liquid (5) was placed in the liquid receiver. The porous support was passed through the slits at a speed of 0.5 m / min to coat both sides.

[0189] (Formation of the coating layer) Steam at a temperature of 60°C was sprayed onto only one side of a porous support coated on both sides to solidify one surface, and then it was immediately immersed in pure water at a temperature of 40°C and left to stand for 30 minutes to completely solidify the coating layer, thereby obtaining an electrolytic composite film.

[0190] (Washing) The obtained electrolytic composite membrane was rinsed three times with pure water and then immersed in pure water and stored under refrigeration.

[0191] Measurements were performed on the obtained electrolytic composite films according to Measurement Examples 1 to 6, and the results are shown in Table 3. Compared to Example 5, when PB1 / PB2 was not between 0.9 and 1.1, i.e., when the pore size was asymmetrical between the front and back surfaces, the abrasion resistance, ion permeability, and gas barrier properties were slightly reduced.

[0192] [Example 16] (First Coat) The above PPS nonwoven fabric 1 was cut into 15 cm squares to form a porous support. Two applicators were placed opposite each other with a 400 μm gap between them to form a slit, and the coating liquid (4) was placed between them. The porous support was passed through the slit at a speed of 0.5 m / min to coat both sides. Steam at a temperature of 60°C was sprayed onto the coated surface to solidify the surface, and then excess moisture was removed with an air blower to obtain a porous support having an intermediate layer (A).

[0193] (Second coating) Next, the coating liquid (6) described above was placed between slits spaced 600 μm apart. The material was passed through the slits at a speed of 0.5 m / min to coat both sides.

[0194] (Formation of the coating layer) The film was then immediately immersed in pure water at 20°C and left to stand for 30 minutes to completely solidify the coating layer, thereby obtaining an electrolytic composite film.

[0195] (Washing) The obtained electrolytic composite membrane was rinsed three times with pure water and then immersed in pure water and stored under refrigeration.

[0196] Measurements were performed on the obtained electrolytic composite film in Measurement Examples 1 to 6, and the results are shown in Table 3. Compared to Example 5, by setting the RX of the surface layer (B) to a higher condition, the compositional difference with the intermediate layer (A) increased, resulting in a slight decrease in abrasion resistance, but high gas barrier performance was obtained.

[0197] [Example 17] An electrolytic composite film was prepared in the same manner as in Example 16, except that the coating liquid was changed to coating liquid (7) in the second coating of Example 16. Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. Compared to Example 16, the wear resistance decreased slightly by further increasing the RX condition, but high gas barrier performance was obtained.

[0198] [Example 18] An electrolytic composite film was prepared in the same manner as in Example 16, except that the coating solution was changed to coating solution (6) in the first coat and to coating solution (4) in the second coat. Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. The RY was set to a higher condition compared to Example 5. Although the abrasion resistance was better than in Example 16 because the surface layer maintained abrasion resistance, the ion permeability decreased slightly because the intermediate layer became denser. On the other hand, high gas barrier performance was obtained.

[0199] [Example 19] An electrolytic composite film was prepared in the same manner as in Example 16, except that the coating solution was changed to coating solution (7) in the first coat and to coating solution (4) in the second coat. Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. Compared to Example 18, the RY was set to an even higher condition, but the abrasion resistance decreased due to the larger difference in composition between the surface layer and the intermediate layer, and the ion permeability decreased due to the more dense intermediate layer, but high gas barrier performance was obtained.

[0200] [Example 20] An electrolytic composite film was prepared in the same manner as in Example 16, except that the coating solution was changed to coating solution (5) in the first coat and to coating solution (6) in the second coat. Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. Although RX and RY were within a preferred range, the composition ratio was slightly different, that is, the condition was not such that RX / RY was between 0.8 and 1.2, resulting in intermediate and practical performance compared to Examples 15 to 19.

[0201] [Example 21] An electrolytic composite film was prepared in the same manner as in Example 16, except that the coating solution was changed to coating solution (5) in the first coat and to coating solution (8) in the second coat. Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. Compared with Example 6, an electrolytic composite film with similarly excellent performance was obtained even when using a two-coating method instead of a one-coating method.

[0202] [Comparative Example 1] An electrolytic composite film was prepared in the same manner as in Example 1, except that the process described in (second coat) was omitted. Therefore, the electrolytic composite film of Comparative Example 1 had only an intermediate layer (A) and no surface layer (B). Measurements 1 to 6 were performed on the obtained electrolytic composite film, and the results are shown in Table 3. Compared to Example 1, the abrasion resistance was lower and sufficient gas barrier performance could not be obtained due to the absence of a surface layer (B).

[0203] [Comparative Example 2] Without using a PPS mesh, the above coating liquid (2) was applied to a PET film, and it was immediately immersed in pure water at a temperature of 20°C and left to stand for 30 minutes to completely solidify the coating layer, thereby obtaining an electrolytic composite film. The obtained electrolytic composite film was rinsed three times with pure water, immersed in pure water and stored under refrigeration, and measurements were taken for Measurement Examples 1 to 6, and the results are shown in Table 3. The electrolytic composite film of Comparative Example 2 had only an intermediate layer (A) without a porous support. Because it did not have a porous support, the electrolytic composite film crumbled and broke in the abrasion resistance test.

[0204] [Comparative Example 3] The electrolytic composite film prepared in Comparative Example 2 was cleaned by washing with distilled water to remove excess moisture, then immersed in liquid nitrogen to freeze, and dried in a vacuum dryer at a temperature of 60°C for 24 hours.

[0205] (Second Coat) Next, the above coating solution (1) was placed in slits spaced 900 μm apart. The dried electrolytic composite film was passed through the slits at a speed of 1 m / min to coat both sides. Then, it was immediately immersed in pure water at a temperature of 20°C and left to stand for 30 minutes to completely solidify the coating layer, thereby obtaining an electrolytic composite film. The obtained electrolytic composite film was rinsed three times with pure water, immersed in pure water and stored under refrigeration, and measurements were taken for Measurement Examples 1 to 6, with the results shown in Table 3. The electrolytic composite film of Comparative Example 3 has an intermediate layer (A) and a surface layer (B) without a porous support. Because it does not have a porous support, the electrolytic composite film crumbled and broke in the abrasion resistance test.

[0206] [Comparative Example 4] An electrolytic composite film was prepared in the same manner as in Example 1, except that coating solution (1) was used instead of coating solution (2) in the (first coat) of Example 1, and coating solution (7) was used instead of coating solution (1) in the (second coat). Measurements for Measurement Examples 1 to 6 were performed, and the results are shown in Table 3. The electrolytic composite film of Comparative Example 4 does not satisfy the conditions PB1 < PA and PB2 < PA. Compared to Example 1, the average pore sizes PB1 and PB2 on the surface were larger, resulting in lower wear resistance, and the average pore size PA of the intermediate layer was smaller, resulting in lower ion permeability.

[0207]

Claims

1. A sheet-like composite film having a first porous coating layer, a porous support, and a second porous coating layer, wherein the first porous coating layer has a first surface layer (B1) and a first intermediate layer (A1), the second porous coating layer has a second surface layer (B2) and a second intermediate layer (A2), and the composite film has the first surface layer (B1), the first intermediate layer (A1), the porous support, the second intermediate layer (A2), and the second surface layer (B2) in that order, and when the average pore size on the surface of the first surface layer (B1) is PB1, the average pore size on the surface of the second surface layer (B2) is PB2, and the average pore size in the first intermediate layer and the second intermediate layer is PA, PA, PB1, and PB2 satisfy PB1 < PA and PB2 < PA.

2. The electrolytic composite film according to claim 1, wherein PB1 and PB2 satisfy 0.9 ≤ PB1 / PB2 ≤ 1.

1.

3. The electrolytic composite film according to claim 1, wherein the PA is 0.1 μm or more and 5 μm or less.

4. The electrolytic composite film according to claim 1, wherein PB1 and PB2 are 0.05 μm or more and 1 μm or less.

5. The electrolytic composite membrane according to claim 1, wherein the porous support is made of one or more selected from the group consisting of polysulfone, polyethersulfone, polyphenylsulfone, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyetherketone, polyketone, polyetherimide, polystyrene, polyolefin, polyethylene terephthalate, polyamide, and polycarbonate.

6. The electrolytic composite membrane according to claim 5, wherein the porous support is a mesh or a nonwoven fabric.

7. The porous support has a weight of 20 g / m² per unit area. ２ More than 400g / m ２ The following conditions apply, and the density is 0.1 g / cm³. ３ 0.9g / cm or more ３ The electrolytic composite film according to claim 6, which is as follows:

8. The electrolytic composite film according to claim 6, wherein the average fiber diameter of the porous support is 5 μm or more and 180 μm or less.

9. The porous support, 1 m ２ The fiber surface area per square meter is 1 m² ２ Over 100m ２ The electrolytic composite film according to claim 6, which is as follows:

10. The electrolytic composite film according to claim 1, wherein the first porous coating layer and the second porous coating layer contain one or more inorganic particles selected from the group consisting of titanium dioxide, zirconium oxide, cerium oxide, barium sulfate, aluminum oxide, silica, boehmite, and magnesium hydroxide.

11. The electrolytic composite film according to claim 1, wherein the first porous coating layer and the second porous coating layer contain one or more of polysulfone, polyethersulfone, and polyphenylsulfone.

12. The electrolytic composite film according to claim 1, wherein the first porous coating layer comprises inorganic particles and a polymer, the second porous coating layer comprises inorganic particles and a polymer, and the value RX, which is the ratio of the weight of the inorganic particles to the weight of the polymer in the first porous coating layer and the second porous coating layer, is in the range of 3.3 or more and 15 or less.

13. The electrolytic composite film according to claim 12, wherein the first intermediate layer (A1) comprises inorganic particles and a polymer, the second intermediate layer (A2) comprises inorganic particles and a polymer, and the value RY of the weight of the inorganic particles / the weight of the polymer in the first intermediate layer (A1) and the second intermediate layer (A2) is in the range of 3.3 or more and 15 or less.

14. The electrolytic composite film according to claim 13, wherein RX and RY satisfy the condition 0.8 ≤ RX / RY ≤ 1.

2.

15. A method for producing an electrolytic composite film, comprising the steps of: preparing a coating solution containing an organic solvent solution of a polymer and inorganic particles; coating both sides of a porous support with the coating solution to obtain a coated sheet; and contacting the coated sheet with the non-solvent of the coating solution to form a first surface layer (B1) and a second surface layer (B2), as well as a first intermediate layer (A1) and a second intermediate layer (A2).

16. A method for manufacturing an electrolytic composite film, comprising the steps of: preparing a coating solution containing an organic solvent solution of a polymer and inorganic particles; repeating the steps of coating both sides of a porous support with the coating solution to obtain a coated sheet twice; and then bringing the coated sheet into contact with the non-solvent of the coating solution to form a first surface layer (B1) and a second surface layer (B2), and a first intermediate layer (A1) and a second intermediate layer (A2), in this order.

17. A water electrolysis apparatus comprising an electrolytic composite membrane according to any one of claims 1 to 14.

18. A hydrogen production facility including the water electrolysis apparatus described in claim 17.

19. A carbon dioxide electrolytic apparatus comprising an electrolytic composite membrane according to any one of claims 1 to 14.

20. A carbon dioxide electrolysis apparatus including the carbon dioxide electrolysis apparatus described in claim 19.

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