Method for manufacturing alkaline water electrolysis diaphragm

Abstract

The present invention relates to a method for manufacturing an alkaline water electrolysis diaphragm, capable of optimizing ionic conductivity and mechanical strength of the diaphragm and minimizing gas crossover by means of optimizing a coating gradient during a manufacturing process of the diaphragm to improve coating uniformity.

Description

Method for manufacturing an alkaline water electrolysis membrane

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0177278 filed on December 3, 2024, and all contents disclosed in the literature of said Korean patent applications are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to a method for manufacturing an alkaline water electrolysis membrane.

[0005]

[0006] Water electrolysis technology for producing green hydrogen can be classified into alkaline water electrolysis, polymer electrolyte membrane water electrolysis, anion exchange membrane water electrolysis, and solid oxide water electrolysis depending on the mechanism and materials.

[0007] Alkaline water electrolysis is driven by a cell composed of an oxidation electrode, a reduction electrode, and a porous membrane. When electrical energy is applied under conditions of an alkaline electrolyte (e.g., KOH, NaOH, etc.), oxygen gas is generated at the oxidation electrode and hydrogen gas is generated at the reduction electrode. Alkaline water electrolysis has an economic advantage over polymer electrolyte membrane water electrolysis in that it can use non-precious metal catalysts such as nickel and cobalt.

[0008] The membranes used in alkaline water electrolysis primarily take the form of composite membranes in which a coating layer containing nanoparticles and a polymer binder is formed on a porous support. This coating layer enhances the ion conductivity of the membrane and serves to suppress gas crossover.

[0009] However, if the coating layer is not formed uniformly across the entire membrane, the conduction resistance may increase due to an imbalance in the ion conduction pathways, and the electrolysis efficiency may decrease. In addition, if the coating layer is thin or defective in certain sections, gas crossover may occur, which may reduce hydrogen purity and negatively affect the stability of the water electrolysis system.

[0010] Therefore, research is continuously being conducted to optimize the ion conductivity and mechanical strength of the separator and minimize gas crossover by uniformly forming a coating layer across the entire separator.

[0011]

[0012] The problem to be solved by the present invention is to improve coating uniformity by optimizing the coating gradient during the manufacturing process of an alkaline water electrolysis membrane, thereby increasing the ion conductivity and mechanical strength of the membrane produced and minimizing gas crossover.

[0013]

[0014] To solve the above-mentioned problem, the present invention provides a method for manufacturing an alkaline water electrolysis membrane.

[0015] More specifically, (1) the present invention comprises the steps of: transferring a polymer substrate to a coating portion (S1); and coating a slurry on both sides of the polymer substrate (S2); The present invention provides a method for manufacturing an alkaline water electrolysis membrane, comprising the step (S3) of immersing a slurry-coated polymer substrate in a non-solvent to form pores, wherein the coating portion includes a first impregnation head and a second impregnation head located on both sides of the polymer substrate passing through the coating portion, wherein the first impregnation head includes a first slot having a discharge portion for discharging a slurry, and a first slot die head and a first' slot die head having shapes symmetrical to each other with respect to the discharge direction of the slurry passing through the first slot, and the second impregnation head includes a second slot having a discharge portion for discharging a slurry, and a second slot die head and a second' slot die head having shapes symmetrical to each other with respect to the discharge direction of the slurry passing through the second slot, and wherein at least one of the discharge direction of the slurry passing through the first slot and the discharge direction of the slurry passing through the second slot has an inclination of 10˚ or more with respect to the direction perpendicular to the transport direction of the polymer substrate passing through the coating portion.

[0016] (2) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein the polymer substrate in (1) comprises one or more selected from the group consisting of polyphenylene sulfide, polypropylene, polyamide, polyether sulfone, polyphenyl sulfone, polyethylene terephthalate, polybutylene terephthalate and polyether-ether ketone.

[0017] (3) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein, in either (1) or (2), the slurry comprises inorganic particles, a polymer binder, and a solvent.

[0018] (4) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein, in (3) above, the inorganic particles include metal oxides and metal hydroxides.

[0019] (5) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein, in any one of (3) or (4), the metal oxide and metal hydroxide comprises one or more selected from the group consisting of zirconium oxide, zirconium hydroxide, magnesium oxide, magnesium hydroxide, titanium oxide, titanium hydroxide, barium sulfate, silica, hafnium oxide, hafnium hydroxide, and alumina.

[0020] (6) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein, in any one of (3) to (5), the polymer binder comprises one or more selected from the group consisting of polysulfone, polyethersulfone, polyphenylsulfone, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose, starch, hydroxypropylcellulose, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer, sulfonated ethylene-propylene-diene polymer, styrene butadiene rubber and fluororubber.

[0021] (7) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein in any one of (3) to (6), the solvent comprises one or more selected from the group consisting of N-methylpyrrolidone, N-ethylpyrrolidone, N-butylpyrrolidone, N,N-dimethylformamide, formamide, dimethyl sulfoxide, N,N-dimethylacetamide and acetonitrile.

[0022] (8) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein, in any one of (3) to (7), the slurry comprises 35% by weight or more and 60% by weight or less of inorganic particles, and 5% by weight or more and 10% by weight or less of a polymer binder.

[0023] (9) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein in any one of (1) to (8), the total solid content of the slurry is 40% by weight or more and 70% by weight or less.

[0024] (10) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein, in any one of (1) to (9), the slurry coated on both sides of the membrane has a thickness deviation (%) calculated by the following formula 1 of less than 5%.

[0025] [Equation 1]

[0026]

[0027] (11) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein in any one of (1) to (10), the coating is performed while the polymer substrate passes through the coating section at a speed of 1 mm / s or more and 10 mm / s or less.

[0028] (12) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein in any one of (1) to (11), the discharge pressure of the slurry at the discharge section is 10 Pa or more and 100 Pa or less.

[0029] (13) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein, in any one of (1) to (12), a drying step (S20) is included after the S2 step.

[0030] (14) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein the drying is performed at a temperature of 50°C or higher and 150°C or lower in accordance with (13).

[0031] (15) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein, in either (13) or (14), the drying is performed for a time of 1 minute or more and 20 minutes or less.

[0032] (16) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein in any one of (1) to (15), the slope is 10° or more and 20° or less.

[0033] (17) The present invention provides a method for manufacturing an alkaline water electrolysis membrane, wherein, in any one of (1) to (16), the method for manufacturing the alkaline water electrolysis membrane is carried out by a roll-to-roll process.

[0034]

[0035] According to the method for manufacturing an alkaline water electrolysis membrane of the present invention, the coating gradient during the coating process is optimized to increase the coating uniformity on the polymer substrate, and accordingly, the ion conductivity and mechanical strength of the membrane manufactured can be optimized, and gas crossover can be reduced.

[0036]

[0037] Figure 1 is an image showing the shape of the coating portion of the present invention.

[0038] FIG. 2 is a flowchart illustrating the flow of a method for manufacturing an alkaline water electrolysis membrane by a roll-to-roll process according to one embodiment of the present invention.

[0039] FIGS. 3a to 3d are images showing the shapes of the coating process of Examples 1 to 3 and Comparative Example 1 of the present invention.

[0040] FIGS. 4a to 4c are graphs showing the stability of the coating process according to the moving speed of the substrate and the flow rate of the discharged slurry during the coating process of Examples 1 to 3 of the present invention.

[0041] Figure 5 is a graph showing the stability of the coating process according to the conditions of the moving speed of the substrate and the flow rate of the discharged slurry during the coating process of the comparative example of the present invention.

[0042]

[0043] The present invention will be described in more detail below.

[0044] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0045]

[0046] Method for manufacturing an alkaline water electrolysis membrane

[0047] The present invention comprises the step (S1) of transferring a polymer substrate to a coating portion; The method comprises the step (S2) of coating a slurry on both sides of the polymer substrate and the step (S3) of immersing the slurry-coated polymer substrate in a non-solvent to form pores, wherein the coating portion includes a first impregnation head and a second impregnation head located on both sides of the polymer substrate passing through the coating portion, wherein the first impregnation head includes a first slot (21) including a discharge portion for discharging a slurry, and a first slot die head (201) and a first' slot die head (201') having shapes symmetrical to each other with respect to the discharge direction of the slurry passing through the first slot (21), and the second impregnation head includes a second slot (22) including a discharge portion for discharging a slurry, and a second slot die head (202) and a second' slot die head (202') having shapes symmetrical to each other with respect to the discharge direction of the slurry passing through the second slot (22), and the discharge direction of the slurry passing through the first slot (21) and the A method for manufacturing an alkaline water electrolysis membrane is provided, wherein at least one of the discharge directions of the slurry passing through the second slot (22) has an inclination of 10° or more with respect to the direction perpendicular to the transport direction of the polymer substrate passing through the coating portion.

[0048]

[0049] The manufacturing method of the present invention will be described in detail below.

[0050] The polymer substrate transfer step (S1) of the present invention may be a step of preparing a polymer substrate and transferring it to a coating part.

[0051] The above polymer substrate may be a polymer substrate comprising one or more polymers selected from the group consisting of polyphenylene sulfide, polypropylene, polyamide, polyether sulfone, polyphenyl sulfone, polyethylene terephthalate, polybutylene terephthalate, and polyether-ether ketone. As a specific example, the above polymer substrate may be polyphenylene sulfide, which has excellent mechanical strength and excellent alkali resistance.

[0052] The thickness of the polymer substrate may be 50㎛ or more, 60㎛ or more, 70㎛ or more, 80㎛ or more, 90㎛ or more, 100㎛ or more, 110㎛ or more, 120㎛ or more, 130㎛ or more, 140㎛ or more, or 150㎛ or more, and may be 350㎛ or less, 340㎛ or less, 330㎛ or less, 320㎛ or less, 310㎛ or less, 300㎛ or less, 290㎛ or less, 280㎛ or less, 270㎛ or less, 260㎛ or less, or 250㎛ or less. Within the above range, the mechanical properties of the separation membrane can be improved.

[0053] The above coating portion is not significantly limited as long as it includes a first impregnation head and a second impregnation head to be described later, and the process is capable of applying a coating solution onto a polymer substrate.

[0054]

[0055] The coating step (S2) of the present invention may be a step of coating a slurry on both sides of a polymer substrate prepared in step S1.

[0056] The above slurry is intended to coat the surface of a polymer substrate and, at the same time, impregnate the polymer substrate to form a composite film from the solid components within the slurry, and the coating slurry may include inorganic particles, a polymer binder, and a solvent.

[0057] The above inorganic particles may be nanoparticles comprising one or more selected from the group consisting of metal oxides and metal hydroxides. The above inorganic particles may be hydrophilic nanoparticles that exhibit excellent chemical resistance in an alkaline environment, which is an alkaline water electrolysis operating environment, and simultaneously perform the role of improving OH- ion conductivity by improving the wettability of the membrane. As a specific example, the above metal oxides and metal hydroxides may be hydrophilic metal oxides and metal hydroxides, and as a specific example, may include one or more selected from the group consisting of zirconium oxide, zirconium hydroxide, magnesium oxide, magnesium hydroxide, titanium oxide, titanium hydroxide, barium sulfate, silica, hafnium oxide, hafnium hydroxide, and alumina.

[0058] The polymer binder above performs the role of stably binding the inorganic particles onto a polymer substrate to form a uniform coating layer, and may include one or more selected from the group consisting of polysulfone, polyethersulfone, polyphenylsulfone, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose, starch, hydroxypropylcellulose, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer, sulfonated ethylene-propylene-diene polymer, styrene butadiene rubber, and fluororubber. As a specific example, the polymer binder may be polysulfone, in which case the pore structure can be controlled more easily when forming pores by the solvent exchange method.

[0059] The above solvent is not significantly limited as long as it is a solvent that has excellent solubility for polymer binders and inorganic particles and can undergo phase inversion with a non-solvent aqueous solvent, but may include, for example, one or more selected from the group consisting of N-methylpyrrolidone, N-ethylpyrrolidone, N-butylpyrrolidone, N,N-dimethylformamide, formamide, dimethyl sulfoxide, N,N-dimethylacetamide, and acetonitrile. As a specific example, the solvent may be N-methylpyrrolidone.

[0060] The above slurry may further include an additive that promotes pore formation. Specifically, the additive may be introduced to control the pore size during subsequent pore formation, and may be included in an amount of 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, 0.6 wt% or more, 0.7 wt% or more, 0.8 wt% or more, 0.9 wt% or more, or 1.0 wt% or more with respect to the slurry, and 5 wt% or less, 4.9 wt% or less, 4.8 wt% or less, 4.7 wt% or less, 4.6 wt% or less, 4.5 wt% or less, 4.4 wt% or less, 4.3 wt% or less, 4.2 wt% or less, 4.1 wt% or less, or 4.0 wt% or less. Within the above range, the pore size can be effectively controlled.

[0061] The above slurry may contain inorganic particles in an amount of 35 wt% or more, 36 wt% or more, 37 wt% or more, 38 wt% or more, 39 wt% or more, or 40 wt% or more, and 60 wt% or less, 59 wt% or less, 58 wt% or less, 57 wt% or less, 56 wt% or less, 55 wt% or less, 54 wt% or less, 53 wt% or less, 52 wt% or less, 51 wt% or less, or 50 wt% or less, and may contain a polymer binder in an amount of 5 wt% or more, 5.1 wt% or more, 5.2 wt% or more, 5.3 wt% or more, 5.4 wt% or more, or 5.5 wt% or more, and 10 wt% or less, 9.9 wt% or less, 9.8 wt% or less, 9.7 wt% or less, 9.6 wt% or less, or 9.5 wt% or less. Within the above range, a uniform coating of the slurry can be induced, and accordingly, the performance of the separation membrane can be improved.

[0062] The total solid content of the above slurry may be 40 wt% or more, 41 wt% or more, 42 wt% or more, 43 wt% or more, 44 wt% or more, 45 wt% or more, 46 wt% or more, 47 wt% or more, 48 wt% or more, 49 wt% or more, or 50 wt% or more, and 70 wt% or less, 69 wt% or less, 68 wt% or less, 67 wt% or less, 66 wt% or less, 65 wt% or less, 64 wt% or less, 63 wt% or less, 62 wt% or less, 61 wt% or less, or 60 wt% or less. Within the above range, a uniform coating of the slurry can be induced, and accordingly, the performance of the separation membrane can be improved.

[0063] The coating portion comprises a first impregnation head and a second impregnation head located on both sides of a polymer substrate passing through the coating portion. The first impregnation head comprises a first slot (21) including a discharge portion for discharging a slurry, and a first slot die head (201) and a first' slot die head (201') having shapes symmetrical to each other with respect to the discharge direction of the slurry passing through the first slot (21). The second impregnation head may comprise a second slot (22) including a discharge portion for discharging a slurry, and a second slot die head (202) and a second' slot die head (202') having shapes symmetrical to each other with respect to the discharge direction of the slurry passing through the second slot (22). Specifically, the coating portion may be shown as in FIG. 1 of the present invention.

[0064] At this time, at least one of the discharge direction of the slurry passing through the first slot and the discharge direction of the slurry passing through the second slot may have a slope of 10° or more, 11° or more, 12° or more, 13° or more, 14° or more, 15° or more, 16° or more, 17° or more, 18° or more, or 19° or more with respect to the direction perpendicular to the conveying direction of the polymer substrate passing through the coating part, and may have a slope of 30° or less, 29° or less, 28° or less, 27° or less, 26° or less, 25° or less, 24° or less, 23° or less, 22° or less, 21° or less, or 20° or less. By maintaining the above-mentioned slope with respect to the direction perpendicular to the transport direction (TD) of the polymer substrate in the discharge direction of the slurry, defects such as bead break-up or leakage can occur during the coating process, and the coating can proceed uniformly and consistently, thereby minimizing variations in coating thickness. Accordingly, it becomes possible to manufacture a separator with a uniform coating layer, which can reduce differences in physical properties depending on the position of the separator, increase the mechanical strength and ion conductivity of the separator, and lead to a reduction in gas crossover. In particular, if the above-mentioned slope exceeds 20˚, it is difficult to implement in the actual process, and problems such as the substrate detaching during the coating process may occur.

[0065] The coating above can be performed as the polymer substrate passes through the coating section at a speed of 1 mm / s or more, 2 mm / s or more, 3 mm / s or more, or 4 mm / s or more, and 10 mm / s or less, 9 mm / s or less, 8 mm / s or less, or 7 mm / s or less. When the moving speed of the polymer substrate satisfies the above range, the coating slurry can be evenly distributed on the surface of the polymer substrate, making it possible to form a uniform coating layer, and increasing the stability and productivity of the coating process.

[0066] The discharge pressure of the slurry at the discharge section above may be 5 Pa or more, 6 Pa or more, 7 Pa or more, 8 Pa or more, 9 Pa or more, or 10 Pa or more, and 100 Pa or less, 99 Pa or less, 98 Pa or less, 97 Pa or less, 96 Pa or less, 95 Pa or less, 94 Pa or less, 93 Pa or less, 92 Pa or less, 91 Pa or less, or 90 Pa or less. When the discharge pressure of the slurry is maintained within the above range, the slurry can be applied stably and consistently, making it possible to form a uniform coating layer and prevent damage to the polymer substrate caused by high pressure.

[0067] In the present invention, the thickness deviation (%) calculated by the following formula 1 after the coating may be less than 5%, and preferably may be 4.9% or less, 4.8% or less, 4.7% or less, 4.6% or less, 4.5% or less, 4.4% or less, 4.3% or less, 4.2% or less, 4.1% or less, or 4.0% or less.

[0068] [Equation 1]

[0069]

[0070] If the thickness variation is maintained within the above range, consistent performance can be maintained depending on the position of the separator.

[0071]

[0072] The pore formation step (S3) of the present invention may be a process of forming pores within a separation membrane by immersing a polymer substrate in a non-solvent. Specifically, this step may be a step of forming pores within a separation membrane by performing a phase transformation by a solvent exchange method. Accordingly, the slurry-coated polymer substrate undergoes solvent substitution by a non-solvent, i.e., a phase transformation by a solvent exchange method, through an extraction unit, and pores may be formed therefrom.

[0073] The above nonsolvent may be an aqueous solvent and may include all hydrophilic solvents such as water or alcohol, and as a specific example, it may be water.

[0074]

[0075] The present invention may additionally include a drying step (S20) after the above S2 step, and if the drying step (S20) is included, the drying step may be a step for controlling the solid content in the slurry after the slurry coating of the S2 step.

[0076] When the above drying step is included, it may be carried out such that the solid content in the polymer substrate after drying is 50 wt% or more, 51 wt% or more, 52 wt% or more, 53 wt% or more, 54 wt% or more, 55 wt% or more, 56 wt% or more, 57 wt% or more, 58 wt% or more, 59 wt% or more, or 60 wt% or more, and is 100 wt% or less, 99 wt% or less, 98 wt% or less, 97 wt% or less, 96 wt% or less, 95 wt% or less, 94 wt% or less, 93 wt% or less, 92 wt% or less, 91 wt% or less, or 90 wt% or less. By controlling the solid content in the polymer substrate after partial drying in this way, inorganic particles are prevented from being eluted together during the subsequent solvent substitution process by a non-solvent, and cracks are prevented from occurring in the membrane, thereby further improving the performance of the membrane.

[0077] The drying temperature and drying time of the above step (S20) can be individually adjusted so that the solid content in the polymer substrate after drying becomes the above content.

[0078] As a specific example, the drying may be performed at a temperature of 50°C or higher, 55°C or higher, 60°C or higher, 65°C or higher, or 70°C or higher, and 150°C or lower, 145°C or lower, 140°C or lower, 135°C or lower, or 130°C or lower. Additionally, the drying may be performed for a time of 1 minute or more, 2 minutes or more, 3 minutes or more, 4 minutes or more, 5 minutes or more, or 6 minutes or more, and 20 minutes or less, 19 minutes or less, 18 minutes or less, 17 minutes or less, 16 minutes or less, or 15 minutes or less.

[0079] When the drying temperature and time conditions are controlled within the above range, the increase in process time due to drying time can be minimized while preventing cracking of the membrane caused by drying. In addition, the pores within the membrane can be optimized through subsequent processes, thereby reducing gas crossover.

[0080]

[0081] The method for manufacturing an alkaline water electrolysis membrane of the present invention can be carried out using a roll-to-roll process. Below, a method for carrying out each of the steps described above is explained when applying the above method for manufacturing an alkaline water electrolysis membrane to a roll-to-roll process.

[0082] The above step (S1) of the present invention may be a step of unwinding a polymer support and transferring it to a coating section (20, 20'), and the above step (S2) may be performed by passing the polymer support through the coating section (20, 20') and simultaneously coating a coating slurry (CS, CS') discharged from the coating section (20, 20') onto both sides of a polymer substrate. At this time, the coating sections (20, 20') may be positioned to face each other as shown in FIG. 1.

[0083] When the method for manufacturing an alkaline water electrolysis membrane of the present invention is performed as a roll-to-roll process, it may additionally include a step (S20) of partially drying the solvent of the slurry-coated polymer support by passing it through a drying section (30, 30').

[0084] The drying temperature and drying time of the drying step (S20) above may be applied as described above, and the drying time may refer to the total time from the point in time when the separator membrane, which is continuously transported according to roll-to-roll, enters the drying section (30, 30') until the point in time when it passes through the drying section (30, 30') and exits.

[0085] The above step (S3) of the present invention may include an extraction step (S31) in which a dried polymer substrate is passed through an extraction unit (40) and some of the dried product is immersed in a non-solvent to form pores.

[0086] According to one embodiment of the present invention, the step (S31) may be performed in an extraction unit (40), wherein the extraction unit (40) may be configured in the form of a bath containing a non-solvent. Accordingly, when the partially dried slurry-coated mesh substrate passes through the extraction unit (40), pores are formed by solvent substitution by the non-solvent, and the separation membrane can be washed simultaneously.

[0087] According to one embodiment of the present invention, the method for manufacturing an alkaline water electrolysis membrane may include a step (S4) of removing a non-solvent from a porous product manufactured in step (S3). At this time, the step (S4) may be performed by removing the non-solvent while the porous membrane passes through a non-solvent removal unit composed of two rollers (50, 50') capable of compression, and, if necessary, by performing drying (not shown) within a range that does not cause a change in the physical properties of the membrane.

[0088] According to one embodiment of the present invention, the method for manufacturing an alkaline water electrolysis membrane may include a step (S5) of winding the membrane from which the non-solvent has been removed in step (S4).

[0089] According to one embodiment of the present invention, at each step, when the polymer support, the polymer support coated with a slurry, the partially dried slurry-coated polymer support, and the pore-formed separator, etc. are transferred to the next step in a roll-to-roll process, they may be transferred using one or more transfer rollers (TR1, TR2, TR3, TR4, TR5, TR6, TR7), and the number of transfer rollers may be selected as needed.

[0090]

[0091] Hereinafter, the present invention will be described in more detail through examples and experimental examples to specifically explain the invention, but the present invention is not limited by these examples and experimental examples. The embodiments according to the present invention may be modified in various different forms, and the scope of the present invention should not be interpreted as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the invention to those with average knowledge in the art.

[0092] The following examples and comparative examples are the results of simulating the manufacturing method according to the present invention using Python code and the Ansys Fluent program. The constant values ​​required for the simulation were built-in values ​​within the program.

[0093]

[0094] Example 1

[0095] A slurry containing 39.6 g of ZrO2 and 8.6 g of polysulfone, with a solid content of 48.2 wt%, was coated onto a polyphenylene sulfide mesh (SKB-TECH, PPS #50, thickness 280 μm, aperture ratio 50%, wire diameter 150 μm). Subsequently, an alkaline water electrolysis membrane was prepared by drying at 120°C for 2 minutes and then immersing in deionized water, which is a non-solvent. At this time, the coating was carried out by a coating unit including an impregnation head as shown in Fig. 3a, the moving speed of the polymer substrate was controlled to 5 mm / s, and the discharge direction of the slurry was maintained at an inclination of 10˚ relative to the direction perpendicular to the transport direction of the polymer substrate.

[0096]

[0097] Example 2

[0098] In Example 1 above, an alkaline water electrolysis membrane was manufactured in the same manner as in Example 1, except that the coating was carried out by a coating unit including an impregnation head as shown in FIG. 3b, and the discharge direction of the slurry was adjusted to maintain a slope of 15˚ relative to the direction perpendicular to the transport direction of the polymer substrate.

[0099]

[0100] Example 3

[0101] In the above Example 1, an alkaline water electrolysis membrane was manufactured in the same manner as in Example 1, except that the coating was carried out by a coating unit including an impregnation head as shown in FIG. 3c, and the discharge direction of the slurry was adjusted to maintain a slope of 19˚ relative to the direction perpendicular to the transport direction of the polymer substrate.

[0102]

[0103] Comparative Example 1

[0104] In the above Example 1, an alkaline water electrolysis membrane was manufactured in the same manner as in Example 1, except that the coating was carried out by a coating unit including an impregnation head as shown in FIG. 3d, and the discharge direction of the slurry was adjusted to maintain a slope of 0˚ with respect to the direction perpendicular to the transport direction of the polymer substrate.

[0105]

[0106] Experimental Example 1: Determination of Coating Process Stability

[0107] The stability of the coating process according to the moving speed of the substrate and the flow rate of the discharged slurry during the manufacture of the separation membranes of Examples 1 to 3 and Comparative Example was simulated and is shown in FIGS. 4a to 4c and FIG. 5, respectively.

[0108] As can be seen through FIGS. 4a to 4c and FIG. 5, in the embodiment of the present invention, the leaking region, where the coating liquid leaks due to an excessively high flow rate relative to the moving speed of the substrate, appears smaller compared to the comparative example. Additionally, in the embodiment of the present invention, the bead break-up (BB) region, where the coating layer becomes thin due to an excessively low flow rate relative to the moving speed of the substrate, also appears narrower compared to the comparative example. Accordingly, in the embodiment of the present invention, the stable region, where a stable coating layer can be formed, excluding the leaking region and the bead break-up region from the entire area, appears wider compared to the comparative example.

[0109] Specifically, in the case of Examples 1 to 3, the area of ​​the stable region increases by 304%, 2328%, and 6268%, respectively, compared to the comparative example, so that the uniformity of the coating layer can be improved when following the manufacturing method of the present invention, and a stable coating layer can be formed without the formation of a discontinuous coating layer.

[0110] From these results, it was confirmed that when the discharge direction of the slurry is controlled to maintain a constant slope relative to the direction perpendicular to the transport direction of the polymer substrate, leakage and bead splitting phenomena are minimized, allowing for the stable formation of a uniform coating layer.

[0111]

[0112] Experimental Example 2: Observation of Coating Thickness Variation

[0113] The discharge pressure of the slurry, the average coating thickness, and the coating thickness deviation at the discharge section during the manufacturing process of Examples 1, 2 and Comparative Example were measured in the following manner and summarized in Table 1 below.

[0114]

[0115] [measurement method]

[0116] Average coating thickness [㎛]: When the area immediately below the Nip was set to 0 during coating, the thickness was measured at 10 measurement points in the longitudinal direction between 10 mm and 30 mm, and the average thickness was calculated.

[0117] Coating thickness deviation [㎛]: The coating thickness was measured at each point, the average of the deviations was calculated, and the standard deviation was calculated.

[0118] Discharge pressure [Pa]: The pressure generated at the bottom of the slot die nip was measured.

[0119]

[0120] Exit pressure [Pa] Average coating thickness [㎛] (A) Coating thickness deviation [㎛] (B) Deviation / Average [%] = (B / A) * 100 Example 187.75781.090.19 Example 212.45640.080.01 Comparative Example 12375803.040.52

[0121]

[0122] As can be seen from Table 1 above, in the case of the manufacturing method of the embodiment of the present invention, the exit pressure of the slot die is lower than that of the comparative example, so it can be confirmed that the coating thickness can be easily controlled and a uniform coating can be achieved. In addition, it can be confirmed that the coating thickness variation of the separator manufactured by the embodiment of the present invention is significantly lower than that of the comparative example, so it can be confirmed that a uniform coating layer is formed in the separator manufactured in the embodiment of the present invention compared to the separator manufactured in the comparative example.

[0123] From these results, it was found that when the discharge direction of the slurry is controlled to maintain a constant slope with respect to the direction perpendicular to the transport direction of the polymer substrate as in the present invention, a uniform coating layer can be formed on the polymer substrate, and the separation membrane manufactured accordingly can have improved ion conductivity, suppress gas crossover, and improve durability and mechanical strength.

[0124]

[0125] [Explanation of the symbol]

[0126] 10: Roll wound with polymer support

[0127] 20: 1st coating section

[0128] 20': Second coating part

[0129] 21: 1st Slot

[0130] 22: 2nd slot

[0131] 201: 1st Slot Die Head

[0132] 201': 1st slot die head

[0133] 202: Second slot die head

[0134] 202': 2nd slot die head

[0135] 30: 1st drying section

[0136] 30': 2nd drying section

[0137] 40: Extraction part

[0138] 50, 50': Non-solvent removal section

[0139] 60: Winder

[0140] TR1, TR2, TR3, TR4, TR5, TR6, TR7: Transfer rollers

[0141] CS, CS': Coating slurry

[0142] UWD: Unwinding direction

[0143] TD: Transfer direction

[0144] WD: Winding direction

Claims

1. A step of transferring a polymer substrate to a coating section (S1); A step (S2) of coating a slurry on both sides of the polymer substrate; and The method includes the step (S3) of immersing a slurry-coated polymer substrate in a non-solvent to form pores, and The above coating portion includes a first impregnation head and a second impregnation head located on both sides of a polymer substrate passing through the coating portion, and The first impregnation head comprises a first slot including a discharge portion for discharging a slurry, and a first slot die head and a first' slot die head having shapes symmetrical to each other with respect to the discharge direction of the slurry passing through the first slot. The second impregnation head comprises a second slot including a discharge portion for discharging a slurry, and a second slot die head and a second' slot die head having shapes symmetrical to each other with respect to the discharge direction of the slurry passing through the second slot. A method for manufacturing an alkaline water electrolysis membrane, wherein at least one of the discharge direction of the slurry passing through the first slot and the discharge direction of the slurry passing through the second slot has an inclination of 10° or more with respect to the direction perpendicular to the transport direction of the polymer substrate passing through the coating portion.

2. In Claim 1, A method for manufacturing an alkaline water electrolysis membrane, wherein the above-mentioned polymer substrate comprises one or more selected from the group consisting of polyphenylene sulfide, polypropylene, polyamide, polyether sulfone, polyphenyl sulfone, polyethylene terephthalate, polybutylene terephthalate, and polyether-ether ketone.

3. In Claim 1, A method for manufacturing an alkaline water electrolysis membrane, wherein the above slurry comprises inorganic particles, a polymer binder, and a solvent.

4. In Claim 3, A method for manufacturing an alkaline water electrolysis membrane, wherein the above-mentioned inorganic particles include metal oxides and metal hydroxides.

5. In Claim 4, A method for manufacturing an alkaline water electrolysis membrane, wherein the metal oxide and metal hydroxide comprises one or more selected from the group consisting of zirconium oxide, zirconium hydroxide, magnesium oxide, magnesium hydroxide, titanium oxide, titanium hydroxide, barium sulfate, silica, hafnium oxide, hafnium hydroxide, and alumina.

6. In Claim 3, A method for manufacturing an alkaline water electrolysis membrane, wherein the polymer binder comprises one or more selected from the group consisting of polysulfone, polyethersulfone, polyphenylsulfone, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose, starch, hydroxypropylcellulose, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer, sulfonated ethylene-propylene-diene polymer, styrene butadiene rubber, and fluororubber.

7. In Claim 3, A method for manufacturing an alkaline water electrolysis membrane, wherein the solvent comprises one or more selected from the group consisting of N-methylpyrrolidone, N-ethylpyrrolidone, N-butylpyrrolidone, N,N-dimethylformamide, formamide, dimethyl sulfoxide, N,N-dimethylacetamide, and acetonitrile.

8. In Claim 3, The above slurry contains 35 weight% or more and 60 weight% or less of inorganic particles, A method for manufacturing an alkaline water electrolysis membrane comprising 5% by weight or more and 10% by weight or less of a polymer binder.

9. In Claim 1, A method for manufacturing an alkaline water electrolysis membrane, wherein the total solid content of the above slurry is 40% by weight or more and 70% by weight or less.

10. In Claim 1, A method for manufacturing an alkaline water electrolysis membrane, characterized in that the slurry coated on both sides of the membrane has a thickness deviation (%) calculated by the following formula 1 of less than 5%. [Equation 1] 11. In Claim 1, A method for manufacturing an alkaline water electrolysis membrane, wherein the coating is performed while a polymer substrate passes through a coating section at a speed of 1 mm / s or more and 10 mm / s or less.

12. In Claim 1, A method for manufacturing an alkaline water electrolysis membrane, wherein the discharge pressure of the slurry at the discharge section is 10 Pa or more and 100 Pa or less.

13. In Claim 1, A method for manufacturing an alkaline water electrolysis membrane, comprising a drying step (S20) after the above S2 step.

14. In Claim 13, A method for manufacturing an alkaline water electrolysis membrane, wherein the above drying is performed at a temperature of 60°C or higher and 150°C or lower.

15. In Claim 13, A method for manufacturing an alkaline water electrolysis membrane, wherein the above drying is performed for a time of 1 minute or more and 20 minutes or less.

16. In Claim 1, A method for manufacturing an alkaline water electrolysis membrane, wherein the slope is 10˚ or more and 20˚ or less.

17. In Claim 1, The above method for manufacturing an alkaline water electrolysis membrane is a method for manufacturing an alkaline water electrolysis membrane that is carried out by a roll-to-roll process.

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