Ion exchange membrane, method for manufacturing an ion exchange membrane, membrane electrode assembly, and hydrogen production apparatus

Abstract

An ion exchange membrane having a short side and a long side of 80m or more, wherein the film thickness deviation rate A, ion exchange capacity deviation rate B, and ion exchange group remaining rate C, calculated by a predetermined method, are within a specific numerical range.

Description

[Technical Field]

[0001] This disclosure relates to an ion exchange membrane, a method for manufacturing an ion exchange membrane, a membrane electrode assembly, and a hydrogen production apparatus. [Background technology]

[0002] As a method for producing hydrogen, water electrolysis, which generates hydrogen and oxygen gases by electrolyzing water, is being researched. Hydrogen produced using the energy obtained through this method, which suppresses carbon dioxide emissions, is called CO2-free hydrogen or green hydrogen, and is expected to be a next-generation clean energy source that can replace fossil fuels.

[0003] Among water electrolysis methods, the AEM method, which uses an anion exchange membrane (AEM), is attracting attention because it does not require the use of expensive precious metals as catalysts. Against this backdrop, there is a need for AEMs that are more cost-effective and have better production efficiency as AEM-type water electrolysis devices become more widespread. For example, using a roll-shaped AEM simplifies the continuous production process of electrolysis devices, leading to a reduction in the cost of electrolysis devices. As an example of a roll-shaped AEM, Patent Document 1 discloses an AEM obtained by impregnating a porous support with a polymerizable composition, winding it once, and then heating the wound roll in an oven.

[0004] Furthermore, in order to reduce the manufacturing cost of AEMs, Patent Documents 2 and 3 disclose AEMs using photopolymerization as a method to shorten polymerization time and improve production efficiency. However, both of these relate to batch production of AEMs and do not take into account the production of long AEMs with high uniformity. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-225459 [Patent Document 2] International Publication No. 2016 / 027595 [Patent Document 3] Special Publication No. 2022-502522 [Overview of the project] [Problems that the invention aims to solve]

[0006] According to at least one aspect of this disclosure, it is possible to provide an ion exchange membrane that is manufactured efficiently with high uniformity. Furthermore, a method for manufacturing the ion exchange membrane, a membrane electrode assembly including the ion exchange membrane, and a hydrogen production apparatus can be provided. [Means for solving the problem]

[0007] The inventors have found that the above problems can be solved if the ion exchange membrane, the membrane electrode assembly including this ion effect membrane, and the hydrogen production apparatus are such that the film thickness deviation rate A, the ion exchange capacity deviation rate B, and the ion exchange group remaining rate C, calculated by a predetermined method, are within a specific numerical range.

[0008] According to this disclosure, the following ion exchange membranes, methods for manufacturing ion exchange membranes, membrane electrode assemblies, and hydrogen production apparatuses are provided.

[0009] Specifically, this disclosure relates to the following [1] to

[12] . [1] An ion exchange membrane, The ion exchange membrane has a short side and a long side, The length of the aforementioned long side is 80m or more, When multiple test pieces are taken from a predetermined region of the ion exchange membrane, and the film thickness is measured at multiple measurement points on each test piece, and the overall average of the film thickness obtained by calculating the arithmetic mean of the film thickness for each test piece is defined as T, and the maximum dissociation value S is defined as the value with the largest difference from T among the arithmetic mean of the film thickness for each test piece, the film thickness deviation rate A (%) expressed by the following formula (1) is less than 5.0%, Measure the ion exchange capacity in the plurality of test pieces, and set the arithmetic mean value of the ion exchange capacity measurement values in each test piece as the overall average value W of the ion exchange capacity. When the value with the largest difference from the W among the ion exchange capacity values for each of these test pieces is set as the maximum dissociation value V, the ion exchange capacity deviation rate B (%) represented by the following formula (2) is less than 10.0%, An ion exchange membrane having an ion exchange group residual rate C of 70% or more, obtained by measuring the ion exchange capacity before and after the alkali durability test of the ion exchange membrane; Membrane thickness deviation rate A (%) = |(T - S) / T × 100| ··· (1) Ion exchange capacity deviation rate B (%) = |(W - V) / W × 100| ··· (2). [2] The ion exchange membrane according to [1], wherein the W is 1.5 to 3.5 meq. / g. [3] The ion exchange membrane according to [1] or [2], comprising a porous support having voids and an ion exchange resin filled in the voids. [4] The ion exchange membrane according to [3], wherein the ion exchange resin is a hydrocarbon-based polymer. [5] The ion exchange membrane according to [3] or [4], wherein the ion exchange resin contains an anion exchange resin. [6] The ion exchange membrane according to any one of [3] to [5], wherein the porous support contains a polyolefin resin. [7] The ion exchange membrane according to any one of [3] to [6], wherein the ion exchange resin contains a cured product of a polymerizable composition having a viscosity change rate of less than 10% measured by the measurement of liquid viscosity of Japanese Industrial Standard (JIS) Z8803:2011. [8] The ion exchange membrane according to any one of [3] to [7], wherein the ion exchange resin contains a cured product of a polymerizable composition containing a cationic group-containing curable monomer, a crosslinkable monomer, and an alkylene glycol. [9] A method for producing the ion exchange membrane according to any one of [3] to [8], wherein The method is An impregnation step of impregnating the porous support with a polymerizable composition, A coating step of covering the porous support impregnated with the polymerizable composition with an upper film and a lower film, and An irradiation step of irradiating the coated porous support with ultraviolet light, A method for producing an ion exchange membrane, including [the specified element].

[10] The method for producing an ion exchange membrane according to [9], wherein the impregnation step, the coating step and the irradiation step are carried out continuously while transporting the porous support, and the transport speed in the irradiation step is 0.5 m / min or more and 5.0 m / min or less.

[11] A membrane electrode assembly comprising an ion exchange membrane and an electrode as described in any of [1] to [8].

[12] A hydrogen production apparatus comprising an ion exchange membrane according to any one of [1] to [8] or a membrane electrode assembly according to claim 11. [Effects of the Invention]

[0010] This disclosure provides an ion exchange membrane with high uniformity of thickness and ion exchange capacity and excellent alkali resistance, a membrane electrode assembly and a hydrogen production apparatus using the same, and a method for manufacturing an ion exchange membrane. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic diagram illustrating an example of an ion exchange membrane manufacturing apparatus. [Figure 2] A schematic cross-sectional view showing an example of a hydrogen production apparatus according to one embodiment of the present disclosure. [Figure 3] A schematic diagram illustrating the measurement points for the film thickness deviation rate of ion exchange membranes. [Figure 4] A schematic diagram illustrating the measurement points for the film thickness deviation rate of ion exchange membranes. [Modes for carrying out the invention]

[0012] In this disclosure, descriptions of numerical ranges such as "XX or greater and YY or less" or "XX to YY" mean a numerical range that includes the lower and upper limits, unless otherwise specified. When numerical ranges are described in steps, the upper and lower limits of each numerical range can be any combination. In addition, in this disclosure, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means any of the following: XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ.

[0013] An ion exchange membrane, which is one embodiment of this disclosure, will be described in detail below. [Ion exchange membrane] An ion exchange membrane according to one embodiment of this disclosure can be used in hydrogen production equipment, water electrolysis equipment, fuel cells, electrodialysis equipment, diffusion dialysis equipment, pure water production equipment, ion-exchanged water production equipment, etc., due to its excellent alkali resistance. The ion exchange membrane can be suitably used as an anion exchange membrane for AEM-type hydrogen production equipment, AEM-type water electrolysis equipment, or fuel cells.

[0014] An ion exchange membrane is a rectangular membrane with a short side and a long side. Typically, the short side is called the "width" and the long side is called the "length," and it can take the form of a roll wound in the length direction. The length L2 of the shorter side of the ion exchange membrane is, for example, 150 mm or more and 1200 mm or less, preferably 300 mm or more and 1200 mm or less. The length L1 of the long side of the ion exchange membrane is 80 m or more. The length L1 of the long side of the ion exchange membrane is, for example, 80 m or more and 600 m or less, preferably 100 m or more and 600 m or less. The ratio L1 / L2 of the length L2 of the short side of the ion exchange membrane to the length L1 of the long side is, for example, 60 or more and 4000 or less, preferably 90 or more and 2000 or less. Such a shape, in which the length is sufficiently long relative to the width, is also called a "long" shape. Generally, long ion exchange membranes may exhibit variations in properties along their length, but an ion exchange membrane according to one embodiment of this disclosure can suppress non-uniformity in the length direction.

[0015] The thickness of the ion exchange membrane is, for example, 10 μm to 200 μm. Using a thick ion exchange membrane tends to increase the membrane resistance. Using a thin ion exchange membrane tends to decrease the membrane resistance. The thickness of the ion exchange membrane is preferably 20 μm to 150 μm, and more preferably 20 μm to 100 μm. The thickness of the ion exchange membrane referred to here is the overall average value T of the film thickness obtained by the measurement method described later.

[0016] In one embodiment of this disclosure, the film thickness deviation rate A in the long-side direction of the ion exchange membrane is less than 5.0%. The film thickness deviation rate A of the ion exchange membrane in the long-side direction is a parameter that indicates the variation in film thickness in the long-side direction of the ion exchange membrane, calculated by the method described later. A small film thickness deviation rate A in the long-side direction means that the uniformity of the film thickness in the long-side direction of the ion exchange membrane is high. Using an ion exchange membrane with high uniformity of film thickness in the long-side direction makes it possible to produce an ion exchange membrane in a roll shape that is less prone to wrinkles during the winding operation of the ion exchange membrane after drying. In addition, the electrolysis performance of the AEM type water electrolysis apparatus is more easily stabilized. Furthermore, the handling of the ion exchange membrane is improved in the continuous production process of the AEM type water electrolysis apparatus, and the apparatus can be manufactured stably. The film thickness deviation ratio A is preferably 4.0% or less, and more preferably 3.5% or less. The lower limit of the film thickness deviation ratio A is not particularly limited, but in one example it is 1.0% or more, and in another example it is 2.0% or more. In other words, the film thickness deviation rate A can be, for example, 1.0% or more and less than 5.0%, 1.0% or more and 4.0% or less, 1.0% or more and 3.5% or less, 2.0% or more and less than 5.0%, 2.0% or more and 4.0% or less, or 2.0% or more and 3.5% or less.

[0017] The film thickness deviation ratio A can be controlled by the magnitude of the change in viscosity of the polymerizable composition used as a raw material for manufacturing the ion exchange membrane. When the viscosity change is large, the impregnation time and amount of accompanying material into the support fluctuate, resulting in an uneven thickness of the resulting ion exchange membrane and a large film thickness deviation ratio A. On the other hand, when the viscosity change is small, the impregnation time and amount of accompanying material into the support remain constant, resulting in a uniform thickness of the resulting ion exchange membrane and a small film thickness deviation ratio A. Furthermore, the change in viscosity of the polymerizable composition can be controlled by the solvent contained in the polymerizable composition. To minimize the change in viscosity, it is preferable that the polymerizable composition contains a high-boiling point solvent such as alkylene glycol. On the other hand, when low-boiling point solvents such as water or methanol are used, these solvents tend to volatilize easily, leading to a larger change in viscosity. Furthermore, as will be described later regarding the method for manufacturing ion exchange membranes, the viscosity change of the polymerizable composition can be suppressed and the film thickness deviation rate A can be controlled by continuously performing impregnation, winding, and curing in the manufacturing process, covering the impregnated support with a film, and controlling the transport speed within a predetermined range.

[0018] The film thickness deviation ratio A is obtained by taking multiple test pieces from a predetermined region of the ion exchange membrane, measuring the film thickness at multiple measurement points on each test piece, calculating the overall average film thickness T from the arithmetic mean of the film thicknesses for each test piece, defining the maximum dissociation value S as the value with the largest difference from T among the arithmetic mean film thicknesses for each test piece, and then taking the absolute value of the value obtained by subtracting S from T and dividing by T. In other words, the film thickness deviation ratio A is expressed by the following formula (1). Film thickness deviation A (%) = |(TS) / T × 100|···(1)

[0019] The method for measuring the film thickness deviation A will be explained in more detail. First, the ion exchange membrane is immersed in a 0.5 mol / L NaCl aqueous solution for more than 10 hours, then washed with deionized water, and air-dried at room temperature (25°C) for more than 12 hours to prepare a dry ion exchange membrane of the chloride ion type. A test specimen for measurement is obtained from this ion exchange membrane. Figures 3 and 4 illustrate the method for obtaining the test specimen to calculate the film thickness deviation rate A of the ion exchange membrane. As shown in Figure 3, the length of the long side 301 of the ion exchange membrane 109 is defined as L1, and the length of the short side 302 is defined as L2. The long side of the ion exchange membrane is divided equally into five sections, and four lines intersecting the long side 301 perpendicularly are drawn from these lines. The short side is divided equally into two sections, and one line intersecting the short side 302 perpendicularly is drawn from these lines. The four intersection points of these lines are designated as intersection points 303 (circled in Figure 3). With intersection points 303 as the geometric center, square test specimens with sides of 100 mm are taken from each intersection point 303, yielding a total of four test specimens 400. Then, as shown in Figure 4, the 16 intersection points 401 (marked with triangles in Figure 4), which are the intersections of the eight straight lines that divide the collected test piece 400 into 20 mm squares, are designated as measurement points for each test piece. For each test specimen, the film thickness of the ion exchange membrane is measured at 16 measurement points using a film thickness gauge, and the arithmetic mean is calculated for each specimen. The arithmetic mean values ​​obtained from the four test specimens are then summed, and the total is divided by 4 to obtain the overall average film thickness T of the ion exchange membrane. The value with the largest difference from T among the arithmetic mean values ​​for the four test specimens is defined as the maximum dissociation value S. From the obtained values ​​of T and S, the film thickness deviation rate A is calculated using the above formula (1).

[0020] The ion exchange capacity deviation rate B in the long-side direction of an ion exchange membrane according to one embodiment of this disclosure is less than 10.0%. The ion exchange capacity deviation rate B of an ion exchange membrane in the long-side direction is a parameter that indicates the variation in the ion exchange capacity in the long-side direction of the ion exchange membrane, and is calculated by the method described later. A small value of the ion exchange capacity deviation rate B means that the uniformity of the ion exchange capacity in the long-side direction of the ion exchange membrane is high. By using an ion exchange membrane with high uniformity of ion exchange capacity in the long-side direction, the electrolysis performance of an AEM-type water electrolysis apparatus can be stabilized. The ion exchange capacity deviation rate B is preferably less than 10.0%, more preferably 7.5% or less, and even more preferably 5.0% or less. The lower limit of the ion exchange capacity deviation rate B is not particularly limited, but in one example it is 1.0% or more, and in another example it is 3.0% or more. In other words, the ion exchange capacity deviation rate B can be, for example, 1.0% or more and less than 10.0%, 1.0% or more and 7.5% or less, 1.0% or more and 5.0%, 3.0% or more and less than 10.0%, 3.0% or more and 7.5% or less, or 3.0% or more and 5.0% or less.

[0021] The ion exchange capacity deviation rate B can be controlled, similar to the film thickness deviation rate A described above, by the magnitude of the change in viscosity of the polymerizable composition used as a raw material for manufacturing the ion exchange membrane.

[0022] The ion exchange capacity deviation rate B is obtained by measuring the ion exchange capacity at multiple measurement points on the test specimen used to measure the film thickness deviation rate A, taking the arithmetic mean of the ion exchange capacity for each test specimen as the overall average value of ion exchange capacity W, and taking the value with the largest difference from W among the ion exchange capacity values ​​for each test specimen as the maximum dissociation value V, and then taking the absolute value of the value obtained by subtracting V from W and dividing by W. In other words, the ion exchange capacity deviation rate B is expressed by the following formula (2). Ion exchange capacity deviation rate (%) = |(WV) / W × 100|···(2).

[0023] The method for measuring the ion exchange capacity deviation rate B will be explained in more detail. First, the test specimen 400 used to measure the film thickness deviation rate A is immersed in a 0.2 mol / L NaNO3 aqueous solution for 30 minutes. Then, the NaNO3 aqueous solution is replaced and the specimen is immersed for another 30 minutes. The replacement of the NaNO3 aqueous solution and immersion are repeated two more times, for a total of 2 hours of immersion. The 0.2 mol / L NaNO3 aqueous solution used is freshly prepared. This procedure yields a test specimen of an ion-exchange membrane in which the counterions have been replaced from chloride ions to nitrate ions.

[0024] For each test specimen, the amount of chloride ions liberated during the substitution with nitrate ions is measured using a potentiometric titrator with a silver nitrate aqueous solution. The obtained value is defined as the chloride ion content D (mol) of each test specimen. As a potentiometric titrator, for example, a COMTITE-900 manufactured by Hiranuma Sangyo Co., Ltd. is used.

[0025] Next, the test specimen, in which the counterions have been replaced with nitrate ions, is immersed in a 0.5 mol / L NaCl aqueous solution for 30 minutes. Then, the NaCl aqueous solution is replaced and the specimen is immersed for another 30 minutes. The replacement of the NaCl aqueous solution and immersion are repeated two more times, for a total of 2 hours of immersion. In this procedure as well, the 0.5 mol / L NaCl aqueous solution used is freshly prepared. Subsequently, the test specimen is removed from the NaCl aqueous solution and thoroughly washed with deionized water. After washing, the surface moisture of the test specimen is wiped off and dried under reduced pressure at 50°C for 12 hours or more. The mass of the dried test specimen is measured and recorded as mass E (g). Based on the amount of free chloride ions (D) and the mass of the test specimen (E), the ion exchange capacity of each test specimen is calculated using the following formula.

[0026] Ion exchange capacity [meq. / g] = D × 1000 / E The ion exchange capacity measurements obtained from the four test specimens are summed up, and the total value is divided by 4 to obtain the overall average value W of the ion exchange capacity of the ion exchange membrane. The value with the largest dissociation from W among the ion exchange capacity values ​​of the four test specimens is defined as the maximum dissociation value V. From the obtained values ​​of W and V, the ion exchange capacity deviation rate B is calculated using the above formula (2).

[0027] The overall average value W of the ion exchange capacity of the ion exchange membrane is, for example, 1.5 meq. / g or more, in other examples, 2.0 meq. / g or more, and in yet another example, 2.5 meq. / g or more. An ion exchange membrane according to one embodiment of this disclosure can achieve a high ion exchange capacity because it can use a polymerizable composition with a high concentration of quaternary ammonium salt. The upper limit of W is not particularly limited, but in one example it is 3.5 meq. / g or less, and in another example it is 3.0 meq. / g or less. In other words, the overall average value W of the ion exchange capacity of the ion exchange membrane can be, for example, 1.5-3.5 meq. / g, 1.5-3.0 meq. / g, 2.0-3.5 meq. / g, 2.0-3.0 meq. / g, 2.5-3.5 meq. / g, or 2.5-3.0 meq. / g.

[0028] In an ion exchange membrane according to one embodiment of this disclosure, the ion exchange group retention rate C, obtained by measuring the ion exchange capacity before and after an alkali durability test, is 70% or more. A high retention rate of ion exchange groups means that the ion exchange membrane has high alkali durability. The ion exchange group retention rate C is preferably 80% or more, and more preferably 90% or more. The upper limit of this ion exchange group retention rate C is not particularly limited, but in one example it is 100%, and in another example it is 95% or less. In other words, the remaining ion exchange group percentages can be, for example, 70-100%, 80-100%, 90-100%, 70-95%, 80-95%, and 90-95%.

[0029] The ion exchange group retention rate C can be controlled by the alkali resistance of the curable monomer containing cationic groups in the polymerizable composition. When vinyl or allyl groups are used as polymerizable groups, the alkali resistance of the curable monomer increases, and the ion exchange group retention rate C increases. On the other hand, when acryloyl or methacryloyl groups are used as polymerizable groups, the alkali resistance of the curable monomer decreases, and the ion exchange group retention rate C decreases.

[0030] The ion exchange group retention rate C is measured by the following method. First, a 100 mm x 100 mm test specimen is taken from a different location than where the test specimen was taken when measuring the film thickness deviation rate A. This test specimen is immersed in 300 mL of 1 mass% potassium hydroxide aqueous solution and left standing in a 90°C oven for one week to perform a heating test. For the test specimen after the heating test, the ion exchange capacity X is calculated using the same method as described above. The ion exchange group retention rate C (%) is calculated by dividing the ion exchange capacity X after the heating test by the overall average value W of the ion exchange capacity as described above (X / W × 100).

[0031] The membrane resistance of an ion exchange membrane is, for example, 2.0 Ω·cm. 2 The following is the result, and according to other examples, 1.0 Ω·cm 2 The following applies. There is no specific lower limit for film resistance, but one example is 0.1 Ω·cm. 2That is all, and according to other examples, 0.2 Ω·cm 2 That's all. The membrane resistance of an ion exchange membrane is, for example, 0.1 to 2.0 Ω·cm. 2 , 0.1~1.0Ω·cm 2 , 0.2~2.0Ω·cm 2 , 0.2~1.0Ω·cm 2 These are some examples.

[0032] The water content of the ion exchange membrane is, for example, 20% or more, in other examples it is 30% or more, and in yet other examples it is 40% or more. From the standpoint of increasing the mechanical strength of the membrane, the water content of the ion exchange membrane is preferably 120% or less, and preferably 100% or less.

[0033] The ion exchange membrane may include, or be composed of, a porous support having voids and an ion exchange resin filling the voids of the porous support.

[0034] The porous support functions as a support for the ion exchange resin. Preferably, the porous support is a porous membrane. Examples of porous supports include porous films, woven fabrics, nonwoven fabrics, sponges, and films. When a porous membrane is used as the porous support, it is preferable that the pores of the porous support are filled with ion exchange resin. Using a porous support increases the strength of the ion exchange resin filling the pores. Among these, a porous film is particularly preferable from the viewpoint of strength and thickness uniformity.

[0035] The porous support is, for example, at least one selected from the group consisting of polyolefin resins, fluororesins, polyacrylonitrile, polyvinyl chloride, polyester, polyamide, polysulfone, polyethersulfone, polyphenylene sulfone, polyphenylene sulfide, polyimide, polyethermid, polyamideimide, polycarbonate, polyacrylate, cellulose acetate, polyetheretherketone, and copolymers thereof. The polyolefin resin is, for example, at least one selected from the group consisting of polyethylene, polypropylene, polybutadiene, polymethylpentene, polybutene, polypentene, polyhexene, polymethylheptene, and copolymers thereof. The fluororesin is, for example, at least one selected from the group consisting of polytetrafluoroethylene, poly(tetrafluoroethylene-hexafluoropropylene), polyvinylidene fluoride, polyhexafluoropropylene, polychlorotrifluoroethylene, and copolymers thereof. From the viewpoint of alkali resistance, the porous support preferably contains a polyolefin resin, and more preferably contains at least one of polyethylene and polypropylene.

[0036] The thickness of the porous support is, for example, 10 μm or more and 200 μm or less, preferably 20 μm or more and 150 μm or less, and more preferably 20 μm or more and 100 μm or less. While the porous membrane is not limited, it is preferable that the porous membrane has as uniform a film thickness as possible, and it is preferable that the film thickness deviation rate of the porous membrane, when measured by the same method as the film thickness deviation rate A described above, is less than 5.0%.

[0037] The porosity of the porous support is, for example, 25% to 80%, preferably 30% to 75%, and more preferably 35% to 70%.

[0038] The ion exchange resin is preferably a hydrocarbon polymer. Here, a hydrocarbon polymer is defined as a polymer that substantially does not contain carbon-fluorine bonds, and in which the majority of the bonds in the main chain and side chains constituting the polymer are composed of carbon-carbon bonds. More specifically, a hydrocarbon polymer is defined as a polymer in which the proportion of carbon and hydrogen among the elements constituting the polymer is 75% or more. That is, small amounts of other atoms such as oxygen, nitrogen, silicon, sulfur, boron, and phosphorus may be interposed between the carbon-carbon bonds constituting the main chain and side chains by ether bonds, ester bonds, amide bonds, siloxane bonds, etc.

[0039] The ion exchange resin preferably contains an anion exchange resin, and more preferably consists of an anion exchange resin. An anion exchange resin is a resin that has positively charged groups (cationic groups) as ion exchange groups, and is capable of adsorbing and exchanging anions as counterions.

[0040] The ion exchange resin contains at least one ion exchange group selected from the group consisting of, for example, a quaternary ammonium group, a quaternary phosphonium group, a quaternary imidazolium group, a quaternary pyridinium group, a quaternary pyrrolidinium group, and a quaternary piperidinium group. The ion exchange group is not particularly limited, but a quaternary ammonium group is preferred because it is easy to manufacture and has high alkali resistance. The counterion of the ion exchange resin can be at least one selected from the group consisting of, for example, a halide ion, a triflate, a bistrifluoromethanesulfonimide, a hydroxide ion, a carbonate ion, and a bicarbonate ion. The counterion is preferably at least one selected from the group consisting of a carbonate ion, a bicarbonate ion, and a halide ion. Ion exchange resins having these ions are suitable as anion exchange resins.

[0041] <Polymerizable composition> An ion exchange resin according to one embodiment of the present disclosure can be obtained by curing a polymerizable composition. In other words, an ion exchange resin according to one embodiment of the present disclosure may include a cured product of a polymerizable composition. Specifically, for example, by performing photopolymerization using a polymerizable composition with a low viscosity change rate via a roll-to-roll process, an ion exchange film can be obtained that has a low film thickness deviation rate A and a low ion exchange capacity deviation rate B, and a high ion exchange group retention rate C.

[0042] The polymerizable composition for forming the ion exchange resin preferably contains a curable monomer containing a cationic group and a crosslinkable monomer. The polymerizable composition may also contain a solvent, which may contain alkylene glycol. The ion exchange resin may include a cured product of the polymerizable composition containing a curable monomer containing a cationic group, a crosslinkable monomer, and alkylene glycol. In an environment of 23°C and 50% humidity, the viscosity change rate of the polymerizable composition is preferably less than 20%, more preferably less than 10%, and even more preferably less than 8%. A viscosity change rate of less than 10% allows for the production of long ion exchange membranes with small film thickness deviations A and ion exchange capacity deviations B, even when long ion exchange membranes are manufactured over a long period of time. A lower viscosity change rate results in the production of more uniform ion exchange membranes. Such polymerizable compositions can be obtained, for example, by using curable monomers, crosslinkable monomers, and solvents having cationic groups, as described later.

[0043] Viscosity measurement is performed in accordance with Japanese Industrial Standard (JIS) Z8803:2011. Let Y be the viscosity of the polymerizable composition 1 minute after preparation, and let Z be the viscosity of the polymerizable composition after standing for 1 hour at a temperature of 23°C and 50% humidity. The absolute value of the value obtained by dividing the difference between the viscosity Z after standing and the viscosity Y after preparation (ZY) by the viscosity Y after 1 minute after preparation is defined as the viscosity change rate. That is, the viscosity change rate is expressed by the following formula. Viscosity change rate (%) = |(ZY) / Y × 100|

[0044] As the viscometer, we will use the SV-1A tuning fork vibration viscometer manufactured by A&D Company, Limited.

[0045] <Curable monomers containing cationic groups> The curable monomer containing a cationic group includes, for example, a curable monomer containing at least one cationic group selected from the group consisting of a quaternary ammonium group, a quaternary phosphonium group, a quaternary imidazolium group, a quaternary pyridinium group, a quaternary pyrrolidinium group, and a quaternary piperidinium group. The curable monomer containing a cationic group also contains a radically polymerizable group. As the radically polymerizable group, a highly reactive functional group such as an acryloyl group or a methacryloyl group is preferable in the curing reaction. On the other hand, from the viewpoint of alkali durability, a vinyl group or an allyl group is preferable. Therefore, the curable monomer containing a cationic group preferably has at least one group selected from the group consisting of an acryloyl group, a methacryloyl group, an acrylamide group, a vinyl group, and an allyl group. In particular, the curable monomer preferably has a vinyl group or an allyl group, and is particularly preferably a quaternary ammonium represented by the following formula (I). The curable monomer containing a quaternary ammonium group represented by the formula (I) is easily available and has high alkali durability, so it is suitable as a monomer for water electrolysis.

[0046] [Chemical formula]

[0047] In the above formula (I), R 1 is an alkenyl group having 2 to 5 carbon atoms. R 1 is preferably a vinyl group or an allyl group, and more preferably a vinyl group.

[0048] R 2 is an alkylene group having 1 to 10 carbon atoms. R 2 is preferably an alkylene group having 1 to 5 carbon atoms, more preferably a methylene group or an ethylene group, and even more preferably a methylene group.

[0049] R 3 、R 4 、and R 5Each of these is independently a linear or branched alkyl group having 1 to 4 carbon atoms, or a linear or branched alkoxy group having 1 to 4 carbon atoms. 3 , R 4 , and R 5 Each of these is preferably a linear alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or an ethyl group.

[0050] X - This can be a monovalent anion or a divalent anion. - These are, for example, halide ions, tetrafluoroborates, bicarbonate ions, hydroxide ions, triflates, or bistrifluoromethanesulfonimides. Halide ions are, for example, fluoride ions, chloride ions, or bromide ions. - It is preferable that this is a chloride ion, triflate, or bistrifluoromethanesulfonimide. - If the ion is a chloride ion, an ion exchange resin with a large amount of ion exchange groups per unit mass can be obtained. - However, when triflate or bistrifluoromethanesulfonimide is used, the solubility of the composition increases, and it tends to be easier to increase the concentration of quaternary ammonium salts in the polymerizable composition. Using such a polymerizable composition, an ion exchange resin with a high molar amount of ion exchange groups per unit mass can be obtained.

[0051] The polymerizable composition may contain only one curable monomer, but it is preferable to contain two or more. The polymerizable composition more preferably contains two or more quaternary ammonium compounds selected from the group consisting of para-quaternary ammonium compounds, meta-quaternary ammonium compounds, and ortho-quaternary ammonium compounds, which are structural isomers of each other, as monomers represented by formula (I). Compositions containing structurally isomers of quaternary ammonium compounds tend to be less prone to crystallization and have higher solubility in solvents compared to compositions that do not contain structurally isomers of quaternary ammonium compounds.

[0052] Specific examples of curable monomers containing cationic groups include (vinylbenzyl)trimethylammonium chloride, (vinylbenzyl)trimethylammonium triflate, (vinylbenzyl)trimethylammonium bistrifluoromethanesulfonimide, (vinylbenzyl)dimethylethylammonium chloride, (vinylbenzyl)dimethylethylammonium triflate, (vinylbenzyl)dimethylethylammonium bistrifluoromethanesulfonimide, (vinylbenzyl)trimethylammonium tetrafluoroborate, (vinylbenzyl)trimethylammonium bicarbonate, and (vinylbenzyl)trimethylammonium hydroxylate.

[0053] Other examples of curable monomers containing cationic groups include 4-ethenyl-N,N-dimethylbenzeneethaneaminium chloride, 4-ethenyl-N,N-dimethylbenzeneethaneaminium triflate, 4-ethenyl-N,N-dimethylbenzeneethaneaminium bistrifluoromemethansulfonium, 4-ethenyl-N,N-dimethylbenzeneethaneaminium hydrohydrate, 4-ethenyl-N,N-dimethylbenzenepropaneaminium chloride, 4-ethenyl-N,N-dimethylbenzenepropaneaminium triflate, 4-ethenyl-N,N-dimethylbenzenepropaneaminium bistrifluoromemethansulfonium, and 4-ethenyl-N,N-dimethylbenzenepropaneaminium hydrohydrate.

[0054] As the curable monomer containing a cationic group, (vinylbenzyl)trimethylammonium salt is preferred, and more preferably, at least one salt selected from the group consisting of (vinylbenzyl)trimethylammonium chloride, (vinylbenzyl)trimethylammonium triflate, and (vinylbenzyl)trimethylammonium bistrifluoromethanesulfonylimide is preferred. Since (vinylbenzyl)trimethylammonium salt has high solubility, it tends to increase the concentration of the curable monomer containing a cationic group in the polymerizable composition.

[0055] In the polymerizable composition, the proportion of curable monomers containing cationic groups is, for example, 5% by mass or more and 95% by mass or less. This proportion is preferably 50% by mass or more, preferably 60% by mass or more, and more preferably 65% ​​by mass or more. A higher proportion yields an ion exchange resin with a large amount of ion exchange groups per unit mass. This proportion may be 92% by mass or less, 85% by mass or less, or 80% by mass or less. The proportion of curable monomers containing cationic groups in the polymerizable composition may be within the following ranges. 5-95 mass%, 50-95 mass%, 50-92 mass%, 50-85 mass%, 50-80 mass%, 60-95 mass%, 60-92 mass%, 60-85 mass%, 60-80 mass%, 65-95 mass%, 65-92 mass%, 65-85 mass%, 65-80 mass%.

[0056] The proportion of curable monomers containing cationic groups in a polymerizable composition can be measured, for example, by subtracting the mass of unreacted curable monomers containing cationic groups remaining after the polymerization reaction from the total mass of curable monomers containing cationic groups used as raw materials. Furthermore, each component in the polymerizable composition is 1 H-NMR and 13 This can be measured by analyzing it using known analytical methods such as 1C-NMR. The same applies to components other than curable monomers containing cationic groups.

[0057] In polymerizable compositions, the more preferred range of the proportion of curable monomers containing cationic groups may vary depending on their type. For example, the concentration of vinylbenzyltrimethylammonium chloride is 60% to 70% by mass. For example, the concentration of vinylbenzyltrimethylammonium triflate is 75% to 85% by mass. For example, the concentration of vinylbenzyltrimethylammonium bistrifolmethanesulfonimide is 85% to 95% by mass.

[0058] <Cross-linkable monomers> The crosslinkable monomer may be a comonomer that polymerizes with the curable monomer containing the cationic group described above. The crosslinkable monomer can crosslink curable monomers containing cationic groups with each other, thereby increasing the durability of the cured product.

[0059] The crosslinkable monomer may have one radical polymerizable group per molecule, or it may have two or more radical polymerizable groups per molecule. The radical polymerizable group can be at least one selected from the group consisting of vinyl, allyl, acryloyl, and methacryloyl groups. Among these, vinyl groups are preferred due to their high alkali resistance and reactivity.

[0060] Examples of crosslinkable monomers include at least one selected from the group consisting of vinyl compounds having one vinyl group, divinyl compounds having two vinyl groups, allyl compounds having one allyl group, diallyl compounds having two allyl groups, and dienes. The crosslinkable monomer preferably has two polymerizable groups, and more preferably is a divinyl compound.

[0061] Specific examples of crosslinkable monomers include divinylbenzene, divinylbenzene derivatives, divinyl sulfone, butadiene, chloroprene, divinylphenyl, trivinylbenzenes, divinylnaphthalene, allylamine, diallylamine, divinylpyridine, methylstyrene, vinylbiphenyl, diallyl isocyanurate, 1,2-bis(4-vinylphenyl)ethane, trivinylbenzene, and 1,6-bis(4-vinylbenzyloxy)hexane.

[0062] As the crosslinkable monomer, it is preferable to use at least one styrene derivative selected from the group consisting of divinylbenzene, 1,2-bis(4-vinylphenyl)ethane, trivinylbenzene, and 1,6-bis(4-vinylbenzyloxy)hexane.

[0063] In the polymerizable composition, the proportion of crosslinkable monomers is, for example, 0.1% by mass or more and 50% by mass or less, preferably 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 10% by mass or less. A higher proportion tends to increase the durability of the cured product. If this proportion is excessively high, the performance of the ion exchange resin may decrease.

[0064] The ratio M1 / M2 of the mass M1 of the curable monomer containing a cationic group to the mass M2 of the crosslinkable monomer in the polymerizable composition is, for example, 1 to 100, preferably 3 to 50, and more preferably 5 to 25. A larger ratio tends to improve the performance of the ion exchange resin. A smaller ratio tends to improve the durability of the cured product.

[0065] <Solvent> The polymerizable composition may contain a solvent. To obtain an ion exchange membrane according to one embodiment of this disclosure, it is preferable to use a polymerizable composition in which the curable monomer containing cationic groups is sufficiently dissolved, and which does not undergo viscosity changes over the relatively long manufacturing time required to produce a long ion exchange membrane. The magnitude of the viscosity change of the polymerizable composition can greatly affect the uniformity of the ion exchange membrane produced. If the viscosity change is large, the impregnation time and amount of polymerized composition added to the porous support may fluctuate when impregnating the porous support with the polymerizable composition, which may result in an uneven thickness of the resulting ion exchange membrane. Furthermore, since viscosity changes are caused by the volatilization of the solvent, a large change in viscosity can alter the concentration of the curable monomer containing cationic groups within the polymerizable composition. As a result, the ion exchange capacity of the ion exchange membrane may become non-uniform. Conventionally, water is known as a solvent with high solubility for curable monomers having quaternary ammonium groups, but water is undesirable because it causes large changes in solution viscosity. However, unavoidable water may be present, and it is preferable that the proportion of water in the polymerizable composition be less than 1% by mass. To reduce the viscosity change rate of a polymerizable composition, it is preferable that the polymerizable composition contains a high-boiling point solvent as a solvent, and more preferably, at least one solvent selected from the group consisting of alkylene glycol, dimethyl sulfoxide, and dimethylformamide. Among these, it is most preferable that the polymerizable composition contains alkylene glycol from the viewpoint of solubility of curable monomers containing cationic groups. When using alkylene glycol, it is preferable to use two or more monomers that are structural isomers of each other, represented by the above formula (I), as curable monomers containing cationic groups. Because alkylene glycol has lower polarity compared to water, it has conventionally been difficult to increase the solubility of cationic monomers. However, as described above, solubility can be increased by using quaternary ammonium compounds consisting of structural isomers.

[0066] The number of carbon atoms in alkylene glycol is preferably 1 to 3, and more preferably 2. The boiling point of alkylene glycol is preferably 110°C or higher, and more preferably 120°C or higher. There is no particular upper limit to this boiling point, but one example is 300°C or lower.

[0067] The flash point of alkylene glycol is preferably 90°C or higher, and more preferably 110°C or higher. There is no particular lower limit to this flash point, but one example suggests it is 200°C or higher.

[0068] Specific examples of alkylene glycols include at least one selected from the group consisting of methylene glycol, ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, and tetramethylene glycol. Ethylene glycol is preferred as the alkylene glycol.

[0069] In the polymerizable composition, the proportion of alkylene glycol is, for example, 1% by mass or more and 50% by mass or less, preferably 5% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 35% by mass or less. A higher proportion tends to increase the compatibility of the polymerizable composition. If this proportion is excessively high, the performance of the ion exchange resin may decrease. This proportion can also be measured, for example, by analyzing the alkylene glycol remaining in the cured body after curing of the polymerizable composition and before washing, using a known method. The total mass of the solvent in the polymerizable composition when using a solvent other than alkylene glycol is also within the same range as described above.

[0070] The ratio M1 / M3 of the mass M1 of the curable monomer containing a cationic group to the mass M3 of the alkylene glycol in the polymerizable composition is, for example, 0.01 to 95, preferably 1 to 50, and more preferably 1.5 to 10. A larger ratio tends to improve the performance of the ion exchange resin. A smaller ratio tends to improve the compatibility of the polymerizable composition.

[0071] The ratio M2 / M3 of the mass of the crosslinkable monomer to the mass of the alkylene glycol in the polymerizable composition is, for example, 0.02 to 1, preferably 0.05 to 0.5, and more preferably 0.10 to 0.25. A larger ratio tends to increase the durability of the cured product. A smaller ratio tends to increase the compatibility of the polymerizable composition.

[0072] The polymerizable composition according to the embodiment may also contain other auxiliary solvents, polymerization initiators, and other additives.

[0073] The secondary solvent may be at least one selected from the group consisting of 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, N,N'-dimethylpropylene urea (DMPU), 1-methyl-2-pyrrolidone, N-methyl-2-piperidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylacetamide, N,N-diethylformamide, N,N-diethylacetamide, and tetramethylurea. The above secondary solvent can function as a stabilizer to suppress the separation of the polymerizable composition. The secondary solvent is preferably an alcohol having 6 to 10 carbon atoms, and specifically, at least one long-chain alcohol compound selected from the group consisting of 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, and 1-decanol is preferred. These can also function as surfactants. That is, polymerizable compositions containing these secondary solvents may have excellent wettability. Therefore, for example, this polymerizable composition can be rapidly impregnated into a porous support, thereby increasing the efficiency of ion exchange membrane production.

[0074] In the polymerizable composition, the proportion of the auxiliary solvent is, for example, 1% by mass or more and 15% by mass or less, preferably 1% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less. A higher proportion tends to increase the compatibility of the polymerizable composition. If this proportion is excessively high, the performance of the ion exchange resin may decrease.

[0075] In a preferred configuration, when M4 is the total mass ratio of curable monomers and crosslinkable monomers, M3 is the mass of the solvent, and M5 is the mass of the secondary solvent, the ratio of the sum of M3 and M5 to M4 (M4 / (M3+M5)) is preferably 1.3 to 2.5, and more preferably 1.5 to 2.0. Furthermore, the ratio of M5 to M3 (M5 / M3) is preferably 0.05 to 0.4, and more preferably 0.1 to 0.3.

[0076] The polymerization initiator may be either a photopolymerization initiator or a thermal polymerization initiator. Furthermore, both photopolymerization initiators and thermal polymerization initiators may be included. Two or more types of photopolymerization initiators and thermal polymerization initiators may be used. Examples of photopolymerization initiators include at least one selected from the group consisting of 1-phenyl-2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-benzyl-2-(N,N-dimethylamino)-1-(4-morpholinophenyl)butan-1-one, and 2-methyl-1-[4-(methylthio)phenyl]-2-2morpholinopropan-1-one. Examples of thermal polymerization initiators include at least one selected from the group consisting of benzoyl peroxide, p-chlorobenzoyl peroxide, decanoyl peroxide, lauroyl peroxide, acetyl peroxide, tert-butyl (2-ethylhexanoyl) peroxide hexanoate, and tert-butyl peroxyoctoate.

[0077] In the polymerizable composition, the proportion of the polymerization initiator is, for example, 0.1% by mass or more and 10% by mass or less, preferably 1% by mass or more and 5% by mass or less.

[0078] Other known additives that can be used include antioxidants, polymerization inhibitors, plasticizers, and surfactants.

[0079] As a polymerization inhibitor, for example, at least one selected from the group consisting of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4-OH-TEMPO), 4-tert-butylcatechol (TBC), cuperone, and benzoquinone can be used.

[0080] In the polymerizable composition, the proportion of the polymerization inhibitor is, for example, 0.0001% by mass or more and 2% by mass or less, preferably 0.001% by mass or more and 1.0% by mass or less, and more preferably 0.005% by mass or more and 0.1% by mass or less. This proportion can be measured, for example, by gas chromatography.

[0081] [Method for manufacturing ion exchange membranes] A method for producing an ion exchange membrane according to one embodiment of the present disclosure may include obtaining a first structure by impregnating a porous support with a polymerizable composition, and obtaining a second structure by irradiating the first structure with ultraviolet light. Preferably, a method for manufacturing an ion exchange membrane according to one embodiment of the present disclosure includes an impregnation step of impregnating a porous support with a polymerizable composition, a coating step of covering the porous support impregnated with the polymerizable composition with an upper film and a lower film, and an irradiation step of irradiating the covered porous support with ultraviolet light. A method for manufacturing an ion exchange membrane may include the steps of impregnating a porous support with a polymerization composition, transporting an upper film, the impregnated porous film, and a lower film to a nip roll to cover the impregnated porous film, and irradiating the impregnated porous film covered by the upper film and the lower film with ultraviolet light. Preferred embodiments of the porous support and polymerizable composition are as described above.

[0082] In a method for producing an ion exchange membrane according to one embodiment of the present disclosure, it is preferable to use a curable monomer containing a cationic group (ion exchange group) in the polymerizable composition. This eliminates the need to introduce ion exchange groups into the polymerized resin, compared to the case where a polymerizable composition consisting only of compounds without ion exchange groups is used. Furthermore, since part or all of the polymerizable composition is polymerized by ultraviolet irradiation, ion exchange membranes can be manufactured in a shorter time compared to thermal polymerization methods. Therefore, polymerization can be carried out in a so-called roll-to-roll manner, which offers advantages in terms of manufacturing costs. In thermal polymerization, long polymerization times are required. Therefore, to obtain long ion exchange membrane rolls in manufacturing, it was necessary to impregnate a porous support with a polymerizable composition, wind it up once, and then heat the wound roll in an oven. In this process, a tension difference occurs between the inside and outside of the roll, which tends to result in uneven distribution of the polymerizable composition on the porous support, leading to large variations in the thickness of the resulting ion exchange membrane. By performing roll-to-roll polymerization using ultraviolet irradiation, the polymerizable composition can be cured while maintaining a constant amount of polymerizable composition, thus enabling the production of ion exchange membranes with uniform properties such as thickness.

[0083] A manufacturing method according to one embodiment of this disclosure will be described in detail below with reference to Figure 1, but the following method is an example and is not limited thereto. Figure 1 is a schematic diagram illustrating an example of an ion exchange membrane manufacturing apparatus.

[0084] The method for impregnating the porous support with the polymerizable composition is not particularly limited. The polymerizable composition may be applied to the porous support by coating, spraying, or dropping. Alternatively, the porous support may be immersed in the polymerizable composition. The impregnation process is preferable because it involves immersing the porous support 101 in a liquid tank 103 containing a polymerizable composition 102, as shown in Figure 1, due to its simple equipment specifications and low cost. In particular, to suppress changes in the viscosity of the polymerizable composition due to humidity, it is preferable that the liquid tank 103 be closed except for the inlet into which the porous support 101 is introduced and the outlet from which the impregnated porous support is discharged. Furthermore, the porous support is not limited to a single layer, but may be a laminated film of two, three, or more layers.

[0085] In the coating process, the porous support 104 impregnated with the polymerizable composition is preferably coated with a film 106 using a nip roll 105. By coating both surfaces of the porous support 104 with the film 106 while applying constant pressure with the nip roll, the surface smoothness of the ion exchange membrane is increased, and an ion exchange membrane with a more uniform thickness can be obtained. Furthermore, since contact with air can be prevented by coating both sides with film, changes in viscosity of the polymerizable composition can be suppressed, and polymerization cessation due to oxygen can also be prevented. The film covering the upper surface of the porous support 104 is also called the upper film, and the film covering the lower surface is also called the lower film. The film 106 is preferably a resin film, and the material of the resin film may be at least one selected from the group consisting of polyethylene terephthalate, polyester, perfluoroethylene propene copolymer, and tetrafluoroethylene-hexaethylene propylene copolymer.

[0086] In the irradiation process, an ion exchange film 109 is obtained by polymerizing and curing a polymerizable composition by irradiating a porous support 107 covered with film 106 with ultraviolet light from an ultraviolet irradiator 108. When irradiating with ultraviolet light, the irradiation wavelength is preferably, for example, 300 nm to 400 nm, and more preferably 330 nm to 380 nm. UV intensity is, for example, 1 mW / cm². 2 More than 10000mW / cm 2 The following is preferable, and more preferably, 50 mW / cm². 2More than 8000mW / cm 2 The following applies: The irradiation time is not particularly limited as long as it is sufficient to cure the polymerizable composition without changing its thickness, but for example, it is 0.5 seconds to 30 minutes, preferably 1 second to 3 minutes, and more preferably 40 seconds to 3 minutes. As the irradiation source, for example, an ultraviolet light-emitting diode (LED), halogen lamp, xenon lamp, tungsten lamp, mercury lamp, etc., can be used. LEDs are preferred in terms of ease of controlling the irradiation wavelength and low heat generation.

[0087] It is preferable to carry out the impregnation process, coating process, and irradiation process continuously while transporting the porous support. This eliminates the need to wind up the porous support after impregnation, resulting in superior manufacturing efficiency. The transport speed of the porous support in the impregnation and irradiation steps is not particularly limited as long as sufficient irradiation time can be ensured, but for example, it is 0.5 m / min or more and 5 m / min or less, preferably 0.5 m / min or more and 2.5 m / min or less, and more preferably 0.5 m / min or more and 1.5 m / min or less. If the transport speed is 5 m / min or less, the time required for manufacturing is shortened and changes in the viscosity of the polymerizable composition are less likely to occur, so a high-quality ion exchange film with small variations in film thickness and ion exchange capacity can be obtained. On the other hand, if the transport speed is 0.5 m / min or more, the reaction time for the photopolymerization reaction is sufficient and the polymerizable composition is sufficiently cured. In a method for manufacturing an ion exchange membrane according to one embodiment of the present disclosure, changes in viscosity of the polymerizable composition due to humidity can be suppressed, so that the impregnation process and the irradiation process can be carried out under atmospheric conditions. However, from the viewpoint of avoiding contact with moisture in the atmosphere as much as possible, a sealed container can be used during impregnation, or impregnation can be carried out under a nitrogen atmosphere.

[0088] After obtaining an ion exchange membrane polymerized with the polymerizable composition, the ion exchange membrane may be heat-treated. Alternatively, a portion of the polymerizable composition may be polymerized by ultraviolet irradiation, and then the polymerizable composition may be completely polymerized by thermal polymerization. During heat treatment, the heating temperature is, for example, 50°C to 150°C, preferably 80°C to 130°C. The heating time is, for example, 1 minute to 12 hours, preferably 3 minutes to 6 hours. The heating method can be a hot plate, oven, infrared heater, heating furnace, etc.

[0089] After light irradiation, heating, or after both light irradiation and heating, the ion exchange membrane obtained may be washed with water, an organic solvent (ethanol, acetone, chloroform, dichloromethane, etc.), or a mixture thereof to wash away solvents such as ethylene glycol, 1-hexanol, and 1-heptanol contained in the polymerizable composition. When using water, the counterion substitution treatment described below may also be performed.

[0090] The ion exchange membrane obtained by the above method may be subjected to a drying treatment. During the drying treatment, the drying temperature may be set to, for example, 20 to 90°C, and the drying time may be set to, for example, 1 minute to 1 hour.

[0091] The ion exchange membrane obtained by the above method may be subjected to a counterion substitution treatment. This allows the counterion of the ion exchange resin to be replaced with another type of counterion. For example, if the counterion is triflate or bistrifluoromethanesulfonimide, the anion can be replaced with a halide ion by immersing the ion exchange membrane in an aqueous solution containing a halogen compound, such as a hydrogen chloride solution or a hydrogen bromide solution, for a certain period of time. If the counterion is a halide ion, the counterion can be replaced with a hydroxide ion by immersing the ion exchange membrane in an alkali metal hydroxide solution, such as a sodium hydroxide solution, for a certain period of time. If the counterion is a hydroxide ion, the counterion can be replaced with a carbonate ion or a bicarbonate ion by immersing the ion exchange membrane in a carbonate solution, such as a potassium carbonate solution or a sodium bicarbonate solution, for a certain period of time. Alternatively, the anion can be replaced with a carbonate ion or a bicarbonate ion by exposing an ion exchange membrane with a hydroxide ion counterion to the atmosphere for a certain period of time.

[0092] [Method for manufacturing a membrane electrode assembly] A membrane electrode assembly according to one embodiment of the present disclosure includes an ion exchange membrane according to one embodiment and an electrode. In the membrane electrode assembly (MEA), the ion exchange membrane and the electrode are integrated. The electrode may include a first electrode which is a cathode and a second electrode which is an anode. The membrane electrode assembly may have an ion exchange membrane interposed between the first electrode and the second electrode.

[0093] The membrane electrode assembly can be used in hydrogen production equipment, water electrolysis equipment, fuel cells, and the like.

[0094] The electrode may include a metal catalyst and optionally an ion conductor, a conductive agent, and a binder. The proportions of the metal catalyst, ion conductor, conductive agent, and binder in the electrode are, for example, 50% to 99% by mass, 0.1% to 30% by mass, 0.1% to 30% by mass, and 0.1% to 30% by mass, respectively.

[0095] Metal catalysts promote oxidation or reduction reactions. Metal catalysts are typically in the form of particles. Examples of metal catalysts include platinum, gold, silver, palladium, iridium, rhodium, ruthenium, tin, iron, cobalt, nickel, manganese, molybdenum, tungsten, vanadium, chromium, tantalum, zirconium, aluminum, zinc, oxides or hydroxides thereof, or alloys thereof. The metal catalyst for the anode preferably contains nickel. The metal catalyst for the cathode preferably contains platinum, gold, silver, palladium, iridium, rhodium, ruthenium, tin, iron, cobalt, nickel, manganese, or alloys thereof.

[0096] Ion conductive agents enhance the ionic conductivity of electrodes. Examples of ion conductive agents include perfluorocarbon polymers having basic functional groups, aromatic polyether ether ketones, polysulfones, polyfluorenes, and polystyrenes. Ion exchange resins may also be used as ion conductive agents. The ion exchange resin may be an ion exchange resin according to one embodiment of this disclosure, or other ion exchange resins may be used. Examples of other ion exchange resins include ion exchange resins having imidazole groups.

[0097] Conductive agents enhance the electronic conductivity of electrodes. Conductive agents may also be used as supports for metal catalysts. Examples of conductive agents include carbon black, activated carbon, graphite, fullerenes, carbon nanotubes, or mixtures thereof.

[0098] The binder increases the rigidity of the electrode. Possible binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorinated rubber, polyacrylic acid compounds, imide compounds, or mixtures thereof.

[0099] The membrane electrode assembly is manufactured, for example, by the following method.

[0100] First, an ion exchange membrane according to one embodiment of this disclosure is prepared using the method described above. The ion exchange membrane may be in a wet state, but it is preferable that it be in a dry state.

[0101] Next, a metal catalyst is mixed with an ion conductor, a conductive agent, a binder, and an organic solvent to prepare a first electrode-forming composition. This first electrode-forming composition is applied, for example, to release paper to obtain a first coating film. This first coating film is dried. After drying, the first coating film is peeled off the release paper and laminated onto one main surface of the ion exchange membrane. An ion conductor may be applied to one main surface of the ion exchange membrane. Alternatively, the first electrode-forming composition may be applied directly to one main surface of the ion exchange membrane to form the first coating film.

[0102] Next, a metal catalyst is mixed with an ion conductor, a conductive agent, a binder, and an organic solvent to prepare a second electrode forming composition. This second electrode forming composition is applied, for example, to release paper to obtain a second coating film. This second coating film is dried. After drying, the second coating film is peeled off the release paper and laminated onto the other main surface of the ion exchange membrane. An ion conductor may be applied to the other main surface of the ion exchange membrane. Alternatively, the first electrode forming composition may be directly applied to the other main surface of the ion exchange membrane to form the second coating film. Furthermore, the first coating film may be formed after the second coating film has been formed.

[0103] The resulting laminate is subjected to heating, pressurization, or both of these processes to integrate the first coating film, the second coating film, and the ion exchange membrane. In this way, a membrane electrode assembly is obtained in which the first electrode, the ion exchange membrane, and the second electrode are laminated in this order. Note that the first or second electrode may be omitted.

[0104] [Structure of a hydrogen production device] A hydrogen production apparatus according to one embodiment of this disclosure includes an ion exchange membrane according to one embodiment of this disclosure. The hydrogen production apparatus may also include a membrane electrode assembly according to one embodiment of this disclosure.

[0105] Since the hydrogen production apparatus includes an ion exchange membrane according to one embodiment of this disclosure, it exhibits excellent uniformity of the ion exchange membrane and can efficiently decompose water.

[0106] Hereinafter, a hydrogen production apparatus including a membrane electrode assembly according to one embodiment of this disclosure will be described in detail with reference to Figure 2.

[0107] Figure 2 is a schematic cross-sectional view showing an example of a hydrogen production apparatus according to one embodiment of the present disclosure. The hydrogen production apparatus 1 shown in Figure 1 comprises a membrane electrode assembly 4 and a first electrode chamber 2 and a second electrode chamber 3 separated by the membrane electrode assembly 4.

[0108] The membrane electrode assembly 4 includes an anion exchange membrane 5, a first electrode 6 supported on one main surface of the anion exchange membrane 5, and a second electrode 7 supported on the other main surface of the anion exchange membrane. The first electrode 6 and the second electrode 7 are connected to a power source via wires (not shown). A gas diffusion layer may be provided on the surfaces of the first electrode and the second electrode. Examples of gas diffusion layers include carbon paper, carbon cloth, nickel foam, titanium foam, and porous graphite.

[0109] The first electrode chamber 2 is equipped with a first electrode 6 and connected to a hydrogen discharge pipe 8. The hydrogen discharge pipe 8 is connected to a hydrogen tank (not shown). The first electrode chamber 2 may be provided with a first partition wall (not shown). The first partition wall is provided with a plurality of grooves connected to the first electrode chamber 2 and a hydrogen discharge passage connected to these grooves and the hydrogen discharge pipe 8. The first partition wall is preferably made of an electronically conductive material. For example, a metal plate can be used for the first partition wall. The first partition wall may be in contact with the gas diffusion layer described above.

[0110] The second electrode chamber 3 is equipped with a second electrode 7, and an oxygen discharge pipe 9 and a water supply pipe 10 are connected to it. The oxygen discharge pipe 9 is connected to an oxygen tank (not shown). The water supply pipe 10 is connected to a water supply device (not shown). The second electrode chamber 3 may be provided with a second partition wall (not shown). The second partition wall is provided with a plurality of grooves connected to the second electrode chamber 3, and oxygen discharge passages connected to these grooves, the oxygen discharge pipe 9, and the water supply pipe 10. The second partition wall is preferably made of an electronically conductive material. For example, a metal plate can be used for the second partition wall. The second partition wall may be in contact with the gas diffusion layer described above.

[0111] Next, we will explain in detail the hydrogen production method using a hydrogen production apparatus, referring to Figure 2.

[0112] First, the liquid to be treated is supplied to the second electrode chamber 3 via the water supply pipe 10. The liquid to be treated may be water or an alkaline aqueous solution. An alkaline aqueous solution is, for example, an aqueous solution of an alkali metal hydroxide, carbonate, or bicarbonate. The pH of the alkaline aqueous solution is, for example, 10 to 14. The concentration of the alkaline aqueous solution is, for example, 0.1% by mass to 30% by mass.

[0113] The liquid to be processed that comes into contact with the membrane electrode assembly 4 is held in the anion exchange membrane 5. The liquid to be processed is supplied to the first electrode chamber 2 via the anion exchange membrane 5.

[0114] Next, power is supplied to the first electrode 6 and the second electrode 7 from a power source (not shown). As a result, water (H2O) is decomposed in the first electrode 6 as shown in equation (A) below, producing hydrogen (H2) and hydroxide ions (OH). - ) is generated. The generated hydroxide ions are supplied to the second electrode 7 via the anion exchange membrane 5. At the second electrode 7, the supplied hydroxide ions are decomposed and synthesized into oxygen (O2) and water (H2O) as shown in formula (B) below.

[0115] 2H2O + 2e - → H2 + 2OH -(A) 2OH - → 1 / 2O2 + H2O + 2e - (B) The hydrogen gas generated in the first electrode chamber 2 is supplied to the hydrogen tank via the hydrogen discharge pipe 8. The oxygen gas generated in the second electrode chamber 3 is supplied to the oxygen tank via the oxygen discharge pipe 9. [Examples]

[0116] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited by these examples.

[0117] The properties of the porous membranes used in the examples and comparative examples of this disclosure, and the properties of the ion exchange membranes using these porous membranes, were evaluated by the following methods. Unless otherwise specified, measurements were performed at room temperature (25°C). For the evaluation of the ion exchange membranes, unless otherwise specified, a chloride ion type dried membrane was used, which was obtained by immersing the ion exchange membrane in a 0.5 mol / L NaCl aqueous solution for 10 hours or more, washing it with ion-exchanged water, and air-drying it at room temperature (25°C) for 12 hours or more.

[0118] In the examples and comparative examples, the thickness of the ion exchange membrane (overall average value T of film thickness), the film thickness deviation rate A, the ion exchange capacity of the ion exchange membrane (overall average value W of ion exchange capacity), the ion exchange capacity deviation rate B, and the ion exchange group retention rate C were measured by the method described above in this specification.

[0119] (Example 1) <Preparation of polymerizable compositions> A polymerizable composition was obtained by mixing 100 g of a curable monomer salt containing a cationic group (vinylbenzyltrimethylammonium chloride), 9.2 g of divinylbenzene, a solvent (ethylene glycol) in an amount that resulted in a concentration of vinylbenzyltrimethylammonium chloride of 10 mol / L, 5.5 g of 1-heptanol, 1.55 g of a photopolymerization initiator, 0.82 g of a thermal polymerization initiator, and 0.049 g of a polymerization inhibitor in a nitrogen atmosphere at room temperature and pressure. 1-phenyl-2-hydroxy-2-methylpropan-1-one was used as the photopolymerization initiator. Tert-butyl peroxyoctoate was used as the thermal polymerization initiator. 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl was used as the polymerization inhibitor. The properties of the obtained polymerizable composition are shown in Table 1.

[0120] <Manufacturing of ion exchange membranes> First, a porous support was prepared. As shown in Table 1, a porous polyethylene film with a film thickness of 25 μm and a porosity of 42% or a film thickness of 20 μm and a porosity of 70% was used as the porous support.

[0121] The porous support was immersed in a polymerizable composition and then withdrawn from the polymerizable composition. In this way, a first structure was obtained in which the polymerizable composition was supported on the porous support. Both main surfaces of this first structure were covered with PET film. A second structure was obtained by irradiating one of the main surfaces of the first structure with ultraviolet light using an LED. The irradiation wavelength was 365 nm and the irradiation intensity was 400 mW / cm². 2 The irradiation time was as shown in Table 2. During the impregnation, coating, and irradiation processes, the porous support, the first structure, and the second structure were transported continuously at a transport speed of 1 m / min.

[0122] Next, the second structure was placed in a heat dryer and subjected to heat treatment. The heating temperature was set to 120°C for 15 minutes so that the surface temperature of the film would reach approximately 110°C. After heating, the PET film was peeled off the second structure to obtain an ion exchange membrane. The obtained ion exchange membrane was washed with a 58% by mass ethanol aqueous solution and then dried at 40°C for 10 minutes. In this way, an ion exchange membrane with a length of 100 m was obtained.

[0123] The characteristics of the obtained ion exchange membrane are shown in Table 2.

[0124] (Examples 2-7, Reference Example 8, Comparative Examples 1-3) An ion exchange membrane was obtained using the same method as in Example 1, except that the curable monomer containing a cationic group and the solvent used to obtain the polymerizable composition, as well as the concentration of the curable monomer containing a cationic group in the polymerizable composition, the photopolymerization time, the transport speed, the winding length, and the porosity of the porous support were changed as shown in Table 1.

[0125] (Comparative Example 4) A polymerizable composition was obtained by mixing 100 g of chloromethylstyrene, 5.5 g of divinylbenzene, and 5 g of tert-butyl peroxyoctoate at room temperature and pressure. A porous support was immersed in the polymerizable composition and then withdrawn from the polymerizable composition. In this way, a first structure was obtained in which the polymerizable composition was supported on the porous support. Both main surfaces of this first structure were covered with PET film. The impregnation and coating steps were carried out at a transport speed of 5 m / min. Subsequently, thermal polymerization was performed at 80°C for 5 hours under a nitrogen pressure of 0.3 MPa to obtain a second structure. The PET film was peeled off this second structure and immersed in a 30% trimethylamine aqueous solution for 16 hours to obtain an ion exchange membrane. The obtained ion exchange membrane was dried at 40°C for 10 minutes to obtain an ion exchange membrane with a length of 100 m.

[0126] (Evaluation of Reference Example 8) In Reference Example 8, in the evaluation of the overall average value W of ion exchange capacity, the ion exchange capacity deviation rate B, the film thickness deviation rate A, and the ion exchange group retention rate C, evaluation was performed on a single test specimen taken from one end in the long side direction, instead of four test specimens. That is, in each test, the arithmetic mean values ​​at 16 measurement points on the single test specimen were treated as the overall average values ​​T and W, and S and V were calculated from the measured values ​​at each measurement point instead of the arithmetic mean values ​​for each test specimen, and each evaluation was performed. A comparison of the evaluation results of Example 1 and Reference Example 8 shows that the ion exchange membrane according to this example is more uniform when viewed in units shorter than the total roll length after cutting, compared to the entire roll.

[0127] [Table 1]

[0128] [Table 2] [Explanation of Symbols]

[0129] 101: Porous support, 102: Polymerizable composition, 103: Liquid tank, 104: Porous support impregnated with polymerizable composition, 105: Nip roll, 106: Film, 107: Porous support covered with film, 108: UV irradiation unit, 109: Ion exchange membrane 1: Hydrogen production device, 2: First electrode chamber, 3: Second electrode chamber, 4: Membrane electrode assembly, 5: Anion exchange membrane 5, 6: First electrode, 7: Second electrode, 8: Hydrogen discharge pipe, 9: Oxygen discharge pipe, 10: Water supply pipe 301: Long side, 302: Short side, 303: Intersection, 400: Test piece, 401: Intersection

Claims

1. An ion exchange membrane, The ion exchange membrane has a short side and a long side, The length of the aforementioned long side is 80m or more, When multiple test pieces are taken from a predetermined region of the ion exchange membrane, and the film thickness is measured at multiple measurement points on each test piece, and the overall average of the film thickness obtained by calculating the arithmetic mean of the film thickness for each test piece is defined as T, and the maximum dissociation value S is defined as the value with the largest difference from T among the arithmetic mean of the film thickness for each test piece, the film thickness deviation rate A (%) expressed by the following formula (1) is less than 5.0%, When the ion exchange capacity of the aforementioned multiple test specimens is measured, and the arithmetic mean of the ion exchange capacity measurements for each test specimen is taken as the overall average value of ion exchange capacity W, and the value with the largest difference from W among the ion exchange capacity values ​​for each test specimen is taken as the maximum dissociation value V, the ion exchange capacity deviation rate B (%) expressed by the following formula (2) is less than 10.0%, An ion exchange membrane having an ion exchange group retention rate C of 70% or more, obtained by measuring the ion exchange capacity of the ion exchange membrane before and after an alkali durability test; Film thickness deviation A (%) = |(T - S) / T × 100| ... (1) Ion exchange capacity deviation rate B (%) = |(W - V) / W × 100| ... (2).

2. The ion exchange membrane according to claim 1, wherein the amount of W is 1.5 to 3.5 meq. / g.

3. The ion exchange membrane according to claim 1, comprising a porous support having voids and an ion exchange resin filled in the voids.

4. The ion exchange membrane according to claim 3, wherein the ion exchange resin is a hydrocarbon polymer.

5. The ion exchange membrane according to claim 3, wherein the ion exchange resin comprises an anion exchange resin.

6. The ion exchange membrane according to claim 3, wherein the porous support comprises a polyolefin resin.

7. The ion exchange membrane according to claim 3, wherein the ion exchange resin comprises a cured body of a polymerizable composition whose viscosity change rate, as measured by liquid viscosity measurement according to Japanese Industrial Standard (JIS) Z8803:2011, is less than 10%.

8. The ion exchange membrane according to claim 3, wherein the ion exchange resin comprises a cured product of a polymerizable composition containing a cationic group-containing curable monomer, a crosslinkable monomer, and an alkylene glycol.

9. A method for producing an ion exchange membrane according to any one of claims 3 to 8, The method described above is An impregnation step of impregnating the porous support with a polymerizable composition, A coating step of covering the porous support impregnated with the polymerizable composition with an upper film and a lower film, and An irradiation step of irradiating the coated porous support with ultraviolet light, A method for producing an ion exchange membrane, including [the specified element].

10. A method for manufacturing an ion exchange membrane according to claim 9, wherein the impregnation step, the coating step, and the irradiation step are performed continuously while transporting the porous support, and the transport speed in the irradiation step is 0.5 m / min or more and 5.0 m / min or less.

11. A membrane electrode assembly comprising an ion exchange membrane and an electrode according to any one of claims 1 to 8.

12. A hydrogen production apparatus comprising an ion exchange membrane according to any one of claims 1 to 8.

13. A hydrogen production apparatus comprising the membrane electrode assembly described in Claim 11.

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