Hollow fiber membrane for fuel cell membrane humidifier, fuel cell membrane humidifier comprising same, and method for manufacturing hollow fiber membrane

Abstract

The present invention relates to a hollow fiber membrane for a fuel cell membrane humidifier, a method for manufacturing same, and a fuel cell membrane humidifier comprising the hollow fiber membrane, the fuel cell membrane humidifier comprising a porous polymer and an amine-based antioxidant having a molecular weight of more than 1000.

Description

Hollow fiber membrane for fuel cell membrane humidifier, fuel cell membrane humidifier including same, and method for manufacturing the hollow fiber membrane

[0001] The present invention relates to a hollow fiber membrane for a fuel cell membrane humidifier, a method for manufacturing the same, and a fuel cell membrane humidifier including the same, and more particularly, to a hollow fiber membrane for a fuel cell membrane humidifier that prevents deterioration and decomposition of the hollow fiber membrane, and a fuel cell membrane humidifier including the same.

[0002] Fuel cells are power-generating cells that convert the chemical energy of hydrogen and oxygen into electrical energy through an electrochemical reaction. Unlike conventional chemical cells like batteries or accumulators, fuel cells can continuously produce electricity as long as hydrogen and oxygen are supplied. They also have the advantage of no heat loss, making them more than twice as efficient as internal combustion engines.

[0003] Furthermore, fuel cells are environmentally friendly energy generators that generate no pollutants, as they use hydrogen and oxygen as raw materials and produce water as a product. Therefore, fuel cells are not only environmentally friendly but also offer the advantage of reducing concerns about resource depletion due to increased energy consumption.

[0004] Fuel cells can be classified into polymer electrolyte membrane fuel cells (PEMFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), solid oxide fuel cells (SOFC), and alkaline fuel cells (AFC).

[0005] Among these, polymer electrolyte fuel cells are known to be suitable for use in transportation systems because they can operate at lower temperatures and have a higher power density than other fuel cells.

[0006] Meanwhile, polymer electrolyte fuel cells generally form water by reacting 2 moles of hydrogen and 1 mole of oxygen in the fuel cell stack during operation. However, if the reaction is incomplete, peroxide or hydroxyl radicals may be formed as byproducts.

[0007] There is a problem in that when the peroxide or hydroxyl radicals generated in this way flow from the fuel cell stack to the membrane humidifier, they cause oxidation of the organic hollow fiber membrane within the membrane humidifier, resulting in decomposition and deterioration of the hollow fiber membrane.

[0008] Decomposition and deterioration of the hollow fiber membrane impede the delivery of sufficiently moist air to the fuel cell stack, thereby reducing the efficiency of the fuel cell stack and the entire fuel cell.

[0009] Accordingly, there is a market demand for technology to protect the hollow fiber membrane included in a membrane humidifier for fuel cells from oxidizing substances and further prevent its decomposition and deterioration.

[0010] An object of the present invention is to provide a hollow fiber membrane used in a membrane humidifier for a fuel cell, which has durability against oxidizing substances.

[0011] According to one aspect, a hollow fiber membrane for a fuel cell membrane humidifier is provided, comprising a porous polymer and an amine-based antioxidant having a molecular weight exceeding 1000.

[0012] According to another aspect, a step of preparing a radiation source solution comprising a polymer and an amine-based antioxidant having a molecular weight exceeding 1000;

[0013] A step of irradiating the above-mentioned radiation source into a coagulation tank through a nozzle;

[0014] A method for manufacturing a hollow fiber membrane for a fuel cell membrane humidifier is provided, including a step of solidifying a radiation source in the above-mentioned coagulation tank.

[0015] According to another aspect, a membrane humidifier for a fuel cell including the above hollow fiber membrane is provided.

[0016] According to one aspect, the hollow fiber membrane comprises an amine-based antioxidant having a molecular weight exceeding 1000, thereby facilitating the removal of oxidizing substances such as hydroxyl radicals or peroxides generated in a fuel cell stack and introduced into a membrane humidifier. In addition, the hollow fiber membrane has the advantageous effect of providing long-term oxidation resistance to the hollow fiber membrane by reducing the amount of antioxidant eluted from the inside of the hollow fiber membrane. In addition, a portion of the amine-based antioxidant is eluted from the hollow fiber membrane during the humidification process of the outside air and is delivered to the fuel cell stack together with the humidified air, resulting in the primary removal of oxidizing substances generated within the fuel cell stack. In addition, the hollow fiber membrane can improve the durability or oxidation resistance against hydroxyl radicals or peroxides without significantly reducing the moisture exchange capacity of the hollow fiber membrane by including a certain amount of the amine-based antioxidant. Therefore, the hollow fiber membrane according to one aspect contributes to improving the durability of not only the humidifier but also the fuel cell stack while maintaining the existing humidifying capacity.

[0017] Figures 1 and 2 are exploded perspective views of a fuel cell humidifier according to one embodiment.

[0018] The present inventive concept described below is capable of various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present inventive concept to specific embodiments, but should be understood to encompass all modifications, equivalents, or alternatives within the technical scope of the present inventive concept.

[0019] The terminology used below is only used to describe specific embodiments and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. Hereinafter, it should be understood that terms such as "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, ingredient, material, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, ingredients, materials, or combinations thereof.

[0020] When a component is referred to as being "connected, coupled" to another component, it should be understood that while the component may be directly connected or coupled to the other component, there may also be a new component between the component and the other component. Conversely, when a component is referred to as being "directly connected" or "directly coupled" to another component, it should be understood that no new component exists between the component and the other component.

[0021] Throughout the specification, when an element, such as a layer, film, region, or plate, is referred to as being "on" or "above" another element, this includes not only instances where the element is directly above the other element, but also instances where there are other elements intervening between them. Terms such as first, second, etc. may be used throughout the specification to describe various components, but the components themselves should not be limited by these terms. These terms are used solely to distinguish one element from another.

[0022] The terms "polymer" and "polymer" as used throughout the specification mean a polymer formed by polymerization of one or more monomer units, and have a meaning encompassing polymer resins and polymer supports.

[0023] The term "molecular weight" as used throughout the specification has units of g / mol and, in relation to polymers or macromolecules, should be understood as weight average molecular weight (Mw).

[0024] The embodiments described below are merely exemplary, and various modifications are possible from these embodiments.

[0025] A hollow fiber membrane for a fuel cell membrane humidifier according to one aspect may include a porous polymer and an amine-based antioxidant having a molecular weight exceeding 1000. In this case, the hollow fiber membrane for a fuel cell membrane humidifier is a hollow fiber membrane that selectively permeates moisture.

[0026] The hollow fiber membrane can prevent the decomposition of the porous polymer by hydrogen peroxide or hydroxyl radicals flowing from the fuel cell stack by including an amine-based antioxidant having a molecular weight exceeding 1000, and a portion of the amine-based antioxidant included in the hollow fiber membrane can be delivered to the fuel cell stack by being contained in humidified air, thereby preventing oxidation of the fuel cell stack. In addition, the amine-based antioxidant having a molecular weight exceeding 1000 interacts with the porous polymer through physical bonding, thereby reducing the amount of leached out from the hollow fiber membrane and allowing a greater amount of the amine-based antioxidant to remain within the porous polymer, thereby providing long-term oxidation resistance to the hollow fiber membrane.

[0027] In particular, the amine-based antioxidant having a molecular weight exceeding 1000 used in one embodiment of the present invention is advantageous in terms of improving the long-term oxidation resistance of the hollow fiber membrane because the amount of elution is reduced compared to the amine-based antioxidant having a molecular weight of 1000 or less.

[0028] According to one embodiment, the hollow fiber membrane selectively permeates moisture and has a three-dimensional membrane shape with a cavity in the center. For example, the three-dimensional membrane may have a shape of a cylinder with a circular cross-section, a square column with a square cross-section, a triangular column with a triangular cross-section, a hexagonal column with a hexagonal cross-section, or a polygonal column with a polygonal cross-section.

[0029] According to one embodiment, the porous polymer is a polymer that forms a tube-shaped hollow fiber membrane having a hollow portion in the center and has a plurality of pores that can selectively pass water molecules, and has an average pore size of 0.05 nm to 90,000 nm. If the pore size of the hollow fiber membrane is excessively large, durability becomes a problem, and if the pore size is excessively small, moisture exchange is not easy, making it difficult to sufficiently humidify the outside air passing through the humidifier.

[0030] The above average pore size was measured using CFP (Capillary flow porometry), and the pore size refers to the straight-line distance connecting the two furthest points on the pore cross-section circumference.

[0031] Additionally, the porosity of the porous polymer forming the hollow fiber membrane may be 45% to 85%. The porosity can be calculated by the ratio of the air volume to the total volume of the hollow porous polymer, as shown in the following mathematical equation 1.

[0032] [Mathematical Formula 1]

[0033] Porosity (%) = (air volume / total volume) X 100

[0034] The average pore size of the hollow fiber membrane not including the above antioxidant is 0.1 nm to 100,000 nm, and the porosity is 50% to 90%. Even when the above composite antioxidant is applied to the hollow fiber membrane, the difference in the above-mentioned average pore size and porosity is not large, so that the moisture exchange capacity of the hollow fiber membrane is maintained, while deterioration of the hollow fiber membrane due to hydroxyl radicals and peroxides is effectively prevented, thereby improving durability.

[0035] According to one embodiment, the antioxidant may be physically dispersed within the porous polymer. For example, the antioxidant may be non-cross-linked and dispersed within the porous polymer. For example, the porous polymer may form the skeleton of the hollow fiber membrane, the porous polymer may include a plurality of pores, and at least a portion of the antioxidant may be present within the pores. Here, the term "physically dispersed" is distinguished from chemical bonds such as covalent bonds, ionic bonds, and metallic bonds, and means physically attached without change in the substance, one material containing another material, or contained by interactions such as van der Waals.

[0036] For example, some of the above antioxidants may be physically attached to the surface of the pores of the porous polymer or may be present embedded in the surface of the pores.

[0037] According to one embodiment, the antioxidant can be embedded within the skeleton of the porous polymer to form an integral part with the porous polymer.

[0038] For example, some of the antioxidant may be present on the pore surface of the porous polymer, and the remaining part may be embedded within the skeleton of the porous polymer to form one body with the porous polymer.

[0039] Since the above-mentioned antioxidant does not form a chemical bond with the porous polymer, the antioxidant can be released and delivered to the fuel cell stack along with the humidified air as outside air passes through the hollow portion of the hollow fiber membrane. As a result, oxidants generated in the stack during fuel cell operation can be removed before they are delivered to the humidifier.

[0040] According to one embodiment, the antioxidant may be incorporated into the hollow fiber membrane by the manufacturing process described below. For example, the antioxidant may be incorporated into the hollow fiber membrane by mixing it into a dope solution and then being incorporated into the hollow fiber membrane during the membrane-forming process, or the antioxidant may be incorporated into the hollow fiber membrane by discharging a complex antioxidant into the core solution and then being incorporated into the hollow fiber membrane during the phase inversion process, or the antioxidant solution may be injected into the hollow portion after the hollow fiber membrane is manufactured to form an antioxidant coating layer on the inner surface of the hollow fiber membrane.

[0041] For example, one of the above antioxidants may be mixed into the dope solution, and the other may be included in the core solution or included in the hollow fiber membrane coating layer forming solution.

[0042] For example, the antioxidant may be mixed into the dope solution, and any one of the plurality of antioxidants included in the antioxidant may be included in the core solution or in the hollow fiber membrane coating layer forming solution.

[0043] In one embodiment, some of the antioxidants may be present and exposed on the porous polymer surface.

[0044] According to one embodiment, the antioxidant may be dispersed on at least one of the inner and outer surfaces of the hollow fiber or may be in the form of a coating layer. For example, the antioxidant may be attached in the form of particles to at least one of the inner and outer surfaces of the hollow fiber or a plurality of particles may form a coating layer.

[0045] For example, the antioxidant particles can be uniformly distributed over the entire surface so as not to block the pores of the hollow fiber.

[0046] According to one embodiment, the antioxidant may form an antioxidant coating layer disposed on at least one surface among the inner and outer surfaces of the hollow fiber. At this time, the antioxidant coating layer may be configured so that a certain amount of the antioxidant can flow out when in contact with the outside air. In order for the antioxidant to be configured so that a certain amount can flow out, there must be no chemical bonding between the antioxidant and the porous polymer, and it is advantageous for the antioxidant to be located on the inner surface of the membrane. Therefore, when forming a humidifying membrane, a crosslinking agent or additive that can cause crosslinking between the antioxidant and the main polymer must not be used.

[0047] According to one embodiment, the amine antioxidant may have an oligomeric or polymeric structure. Here, an oligomer refers to a molecule in which dozens of monomers are linked.

[0048] For example, amine antioxidants include poly-{6-[(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidyl)imino]} (Poly-{6-[(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidyl)imino)}), Chimassorb ®2020, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidine ethanol-alt-1,4-butanedioic acid), a polymer of epichlorohydrin and 2,2,4,4,-Tetramethyl-7-oxa-3,20-diazadispiro-(5.1.11.2)heneicosan-21-one, or a combination thereof.

[0049] According to one embodiment, the amine-based antioxidant may be included in an amount of more than 0 parts by weight and less than 5 parts by weight based on 100 parts by weight of the porous polymer. For example, the composite antioxidant may be included in an amount of more than 0.05 parts by weight and less than or equal to 5 parts by weight, 0.1 parts by weight or more and 5 parts by weight or less, or 1 part by weight or more and 4 parts by weight or less.

[0050] For example, the amine-based antioxidant may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the porous polymer.

[0051] If an antioxidant is not included in the hollow fiber membrane, the hollow fiber membrane may be deteriorated by peroxide or hydroxyl radicals generated in the fuel cell reaction, and if it exceeds 5 parts by weight, not only is the hollow fiber membrane not sufficiently formed, but the pores of the hollow fiber membrane are closed, which reduces the moisture exchange performance and deteriorates the membrane humidifier function.

[0052] In addition, since the antioxidant is included within the above-described range in the hollow fiber membrane, an antioxidant of 1 ug / 1000 hr or more can be provided from the humidifying membrane into the fuel cell stack.

[0053] According to one embodiment, the hollow fiber membrane may further include a phenol-based antioxidant, a phosphorus-based antioxidant, a metal-based antioxidant, an organo-metallic antioxidant, or a sulfur-based antioxidant in addition to an amine-based antioxidant.

[0054] For example, the phenolic antioxidants include Irganox 1010 (Irganox 1010: pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, manufactured by BASF), Irganox 1076 (Irganox 1076: octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, manufactured by BASF), Irganox 1330 (Irganox 1330: 3,3',3",5,5',5"-hexa-t-butyl-a,a',a"-(mesitylene-2,4,6-triyl)tri-p-cresol, manufactured by BASF), and Irganox 3114 (Irganox 3114: 1,3,5-Tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, manufactured by BASF Corporation), Irganox 3790 (Irganox 3790: 1,3,5-Tris((4-t-butyl-3-hydroxy-2,6-xylyl)methyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, manufactured by BASF Corporation), Irganox 1035 (Irganox 1035: thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], manufactured by BASF Corporation), Irganox 1135 (Irganox 1135: Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 branched alkyl ester, manufactured by BASF Corporation), Irganox 1520L (Irganox 1520L: 4,6-bis(octylthiomethyl)-o-cresol, manufactured by BASF Corporation), Irganox 3125 (Irganox 3125, manufactured by BASF Corporation), Irganox 565 (Irganox 565: 2,4-bis(n-octylthio)-6-(4-hydroxy-3',5'-di-t-butylanilino)-1,3,5-triazine, manufactured by BASF Corporation), Adekastab (registered trademark) AO-80 (Adekastab AO-80: 3,9-bis(2-(3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro(5,5)undecane, (manufactured by ADEKA Co., Ltd.), Smilizer (registered trademark) BHT, Dong GA-80, Dong GS (above,It may include Cyanox 1790 (manufactured by Sumitomo Chemical Co., Ltd.), Cyanox (registered trademark) 1790 (manufactured by Cytech Co., Ltd.), and Vitamin E (manufactured by Eisai Co., Ltd.), or any combination thereof.

[0055] For example, phosphorus antioxidants include tris(2,4-di-t-butylphenyl)phosphite (Irgafos 168), tris[2-[[2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy]ethyl]amine (Irgafos 12), bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl)ethyl esterphosphite (Irgafos 38), Adecastab 329K, Adecastab PEP36, Adecastab PEP-8, Sandstab P-EPQ, Weston 618, Weston 619G, Ultranox 626, (6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepin) (Smilizer GP), or a combination thereof.

[0056] For example, the metal-based antioxidant may include cerium, nickel, tungsten, ruthenium, palladium, silver, rhodium, cesium, zirconium, cobalt, chromium, yttrium, manganese, iron, molybdenum, lead, vanadium, titanium, niobium, lanthanum, ions thereof, oxides thereof, salts thereof, or any mixture thereof.

[0057] For example, the organo-metallic antioxidant may include a Ce-crown complex, a Ce-phosphoric acid complex, a Ce-Bypyridine, or any mixture thereof.

[0058] For example, the sulfur-based antioxidant may include dilaurylthiodipropionate (DLTDP), distearylthiodipropionate (DSTDP), ditridecylthiodipropionate (DMTDP), bis 2-methyl-4(3-alkylthio)-propionyloxy)-5-tert-butylphenol sulfide, tetrakis methylene-3-(laurylthio)propionate methane, or combinations thereof.

[0059] According to one embodiment, the porous polymer may include a sulfone group-containing polymer as a main polymer.

[0060] For example, the sulfone group-containing polymer is not particularly limited as long as it is a polymer containing a sulfone group in the main backbone and molecule, and the polymer may include a polysulfone polymer, a sulfonated polysulfone, a perfluorosulfonic acid (PFSA) polymer, a polyphenylsulfone polymer, a polyethersulfone (PES) polymer, or any combination thereof.

[0061] According to one embodiment, the porous polymer may include a polyethersulfone polymer.

[0062] According to one embodiment, the porous polymer includes the aforementioned sulfone-containing polymer as a main polymer, and may further include an auxiliary polymer described below in consideration of the desired properties of the hollow fiber membrane.

[0063] For example, the auxiliary polymer may include at least one selected from polyvinylidene fluoride (PVDF) polymers, cellulose acetate, cellulose triacetate, polymethyl methacrylate, Nafion, polystyrene (PS) polymers, polytetrafluoroethylene (PTFE) polymers, polyacrylonitrile (PAN) polymers, polyetherimide (PEI) polymers, and polyimide (PI) polymers. When such auxiliary polymers are used together with the sulfone group-containing polymer, they may be used in an amount of 5 to 20 parts by weight relative to the main polymer.

[0064] According to one embodiment, the porous polymer may be included in an amount of 90 parts by weight or more and less than 100 parts by weight based on 100 parts by weight of the hollow fiber membrane.

[0065] For example, the porous polymer may be included in an amount of 91 to 99 parts by weight, 92 to 98 parts by weight, 93 to 97 parts by weight, or 94 to 96 parts by weight per 100 parts by weight of the hollow fiber membrane.

[0066] When the porous polymer in the above hollow fiber membrane satisfies the above range, sufficient durability of the hollow fiber membrane is achieved, and sufficient moisture exchange capacity can be exhibited in the humidifier.

[0067] According to one embodiment, the hollow fiber membrane for the fuel cell membrane humidifier may have a thickness of 0.5 nm to 1 mm. When the thickness of the hollow fiber membrane satisfies the above range, the hollow fiber membrane for the membrane humidifier may have strength and moisture exchange capacity.

[0068] According to one embodiment, the hollow fiber membrane may further include additives such as a surfactant, a hydrophilic organic compound, a hydrophilic polymer, or a crosslinking agent.

[0069] For example, the additive may include at least one of polyethylene glycol, glycerin, diethyl glycol, triethylene glycol, ethanol, polyvinylpyrrolidone, water, zinc chloride, and lithium chloride.

[0070] These additives can be selected and added in appropriate amounts, as long as they do not impair the inherent properties of the hollow fiber membrane. It will be apparent to those skilled in the art that any known materials used in the manufacture of hollow fiber membranes can also be used.

[0071] These additives can be selected and added in appropriate amounts, as long as they do not impair the inherent properties of the hollow fiber membrane. It will be apparent to those skilled in the art that any known materials used in the manufacture of hollow fiber membranes can also be used.

[0072] A method for manufacturing a hollow fiber membrane according to one aspect may include the steps of preparing a spinning solution containing a polymer and an amine-based antioxidant having a molecular weight exceeding 1000; the step of spinning the spinning solution into a coagulation tank through a nozzle; and the step of coagulating the spinning solution in the coagulation tank.

[0073] For any overlapping configurations with the previous descriptions in the description of the above hollow fiber desert, refer to the above.

[0074] According to one embodiment, the step of obtaining the above-mentioned radiation source may include a step of mixing a radiation source material comprising the amine-based antioxidant and the polymer in a solvent. The radiation source may be formed by dissolving the polymer and the amine-based antioxidant in a solvent. In this case, the radiation source material may further include the aforementioned additives.

[0075] The solvent may include at least one of a first solvent, a second solvent, and a third solvent. For example, the solvent may be a mixed solvent including two types of solvents among the first solvent, the second solvent, and the third solvent.

[0076] The first solvent is a solvent that cannot dissolve the polymer at room temperature (e.g., 23 to 25°C) but can dissolve the polymer at high temperatures (e.g., 80°C or higher), and may include butanol, isobutanol, octanol, pentanol, isopentanol, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, polyoxylethylene octylphenyl ether, or a combination thereof.

[0077] The second solvent is a solvent that cannot dissolve the polymer, and may include water, methanol, ethanol, isopropanol, acetone, hexane, pentane, benzene, toluene, carbon tetrachloride, o-dichlorobenzene, polyethylene glycol, or a combination thereof.

[0078] The third solvent is a solvent that can dissolve the polymer even at room temperature, and may include N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl acetamide, dimethyl formamide, methyl ethyl ketone, tetrahydrofuran, tetramethyl urea, or trimethyl phosphate.

[0079] A person skilled in the art can use one or a mixture of two or more of the first solvent, the second solvent, and the third solvent, taking into consideration the characteristics of the polymer raw material and the production of a hollow fiber membrane having desired properties.

[0080] According to one embodiment, when the solvent is a mixed solvent of two types of solvents, the mixing ratio of the solvents may be 1:9 to 9:1 by weight, but is not limited thereto, and a person skilled in the art may select an appropriate range by considering the content of the polymer and the antioxidant, the viscosity of the spinning solution, the porosity of the hollow fiber membrane, and the physical properties of the final hollow fiber membrane.

[0081] According to one embodiment, the spinning solution comprises a polymer forming the skeleton of a hollow fiber membrane, an antioxidant, a solvent, and, if necessary, additional additives. The solvent is removed during the spinning solution forming into a hollow fiber membrane, so that the final product has a structure in which the antioxidant is incorporated into the polymer skeleton.

[0082] According to one embodiment, the content of the polymer contained in the spinning solution may be 15 to 25 parts by weight based on 100 parts by weight of the total spinning solution. For example, the content of the polymer contained in the spinning solution may be 16 to 24 parts by weight, 17 to 23 parts by weight, 18 to 22 parts by weight, or 19 to 21 parts by weight.

[0083] According to one embodiment, the content of the antioxidant included in the above-described radiation source may be more than 0 and less than 5 parts by weight, more than 0.05 to 5 parts by weight, or 0.1 to 5 parts by weight, relative to 100 parts by weight of the polymer forming the skeleton of the hollow fiber membrane.

[0084] According to one embodiment, the temperature at which the polymer, antioxidant, and optionally additives are mixed in the solvent in the step of obtaining the above-described radiation source may be appropriately selected at room temperature or high temperature in consideration of the polymer, antioxidant, additive, and solvent used.

[0085] According to one embodiment, the mixing time of the above-described radiation source may be performed for a time sufficient for the polymer, antioxidant, and any additives to be sufficiently dissolved and / or dispersed in the solvent.

[0086] According to one embodiment, the viscosity of the spinning solution may be 5,000 to 50,000 cps at 35°C. When the viscosity of the spinning solution satisfies the above range, the spinning solution can be smoothly discharged through the nozzle without clogging.

[0087] In order to maintain the viscosity of the above-mentioned spinning solution within the aforementioned range, the temperature of the spinning nozzle may be adjusted to a temperature above a certain temperature. Alternatively, the spinning solution may further include a viscosity modifier to control the viscosity as needed.

[0088] According to one embodiment, the spinning solution may further include an additive in consideration of the membrane forming properties and porosity of the hollow fiber membrane, the dispersibility of the antioxidant, and the viscosity of the spinning solution.

[0089] For example, the additive may include at least one of polyethylene glycol, glycerin, diethyl glycol, triethylene glycol, ethanol, polyvinylpyrrolidone, water, zinc chloride, and lithium chloride.

[0090] According to one embodiment, the step of irradiating the above-mentioned radiation source into the coagulation tank may include a step of irradiating the discharge liquid using a tubular radiation device, for example, a double-tubular radiation device or a triple-tubular radiation device, but is not limited to such a tubular type, and any discharge method capable of forming a hollow shape may be used without limitation.

[0091] According to one embodiment, when the spin-off solution is discharged into the coagulation tank through a double-tube type spin-off device, the composition of the spin-off solution discharged from each tube of the double-tube type may be the same or different. For example, when the spin-off solution is discharged using a triple-tube type spin-off device, the composition of the spin-off solution passing through each tube may be the same or different. For example, when a triple-tube type spin-off device is used, the composition of the spin-off solution passing through the tubes arranged on the inner and outer sides of the tube may be the same, and only the composition of the spin-off solution passing through the intermediate tube between the inner and outer sides may be different.

[0092] According to one embodiment, in the step of irradiating the above-mentioned radiation source into the coagulation tank, the radiation temperature may be set to a temperature equal to or higher than the radiation source mixing temperature. In this case, when using a multi-tubular nozzle, the temperature of each nozzle may be set differently, enabling the optimal radiation source to be discharged at an appropriate temperature.

[0093] According to one embodiment, in the step of radiating the above-mentioned radiation source into the coagulation tank, the discharge speed may be 5 to 100 g / min.

[0094] According to one embodiment, when the above-mentioned radiation source is discharged through a tubular nozzle, a core liquid (core liquid) may be discharged together into the inner hollow portion of the tubular body. The core liquid may include a mixed solution of a second solvent and a third solvent.

[0095] According to one embodiment, the core solution may be a mixture of a second solvent and a third solvent in a volume ratio of 3:7 to 7:3. When the core solution satisfies the volume ratio within the above range, the antioxidant contained in the core solution may be incorporated into the hollow fiber membrane during the phase conversion process of the radiation. For example, the core solution may be a mixture of a second solvent and a third solvent in a volume ratio of 5:5 to 7:3.

[0096] When the above-mentioned core solution is mixed in the volume ratio of the second solvent and the third solvent, a composite antioxidant including a first amine-based antioxidant and a second amine-based antioxidant can be dispersed and present within the porous polymer without crosslinking (i.e., non-crosslinking).

[0097] According to one embodiment, the core solution may further comprise at least one of a first amine-based antioxidant and a second amine-based antioxidant. By further including an antioxidant in the core solution, the antioxidant can be dispersed onto the inner surface of the hollow fiber membrane through phase separation during the hollow fiber membrane formation process. As a result, the antioxidant can be dispersed and present at a high concentration on the inner surface of the hollow fiber membrane. As described above, when the core solution including the antioxidant is discharged together, the antioxidant can be contained in small amounts or not contained in the spinning solution.

[0098] According to one embodiment, the radiation emitted from the radiation device can contact the coagulation liquid in the coagulation tank through the air gap.

[0099] The above air gap is the region where the radiant comes into contact with air, and artificial cooling air can be introduced therein, taking into account the physical properties of the radiant. For example, the length of the air gap can be set to 0.1 to 50 cm. The air gap is the region where the first phase transition occurs, where the phase transition is achieved by exchanging moisture in the atmosphere with the organic solvent in the radiant solution. When the length of the air gap satisfies the above range, sufficient phase transition occurs, and a hollow fiber membrane having a desired pore structure can be obtained.

[0100] The above radiation passes through the air gap and comes into contact with the coagulation liquid contained in the coagulation tank, thereby solidifying and forming a porous hollow fiber membrane.

[0101] According to one embodiment, the coagulation tank may be configured as a single tank, but is not limited thereto, and may be configured such that two or more coagulation tanks are arranged in series. When there are two or more coagulation tanks, the coagulant used in each coagulation tank may be the same or different.

[0102] According to one embodiment, the coagulant contained in the coagulation tank serves to coagulate the discharged liquid through the detention into the form of a hollow fiber membrane, and the coagulant used at this time can be appropriately selected and used by a person skilled in the art from among known coagulants by considering the porosity of the hollow fiber membrane, the pore structure of the hollow fiber membrane, etc.

[0103] For example, a second solvent such as an acidic solution or water, or a mixed solvent of a second solvent and a third solvent may be used as the coagulant.

[0104] According to one embodiment, the hollow fiber membrane obtained through the above coagulation tank may undergo a post-processing step.

[0105] According to one embodiment, the post-treatment step may include performing a chemical treatment and / or a physical treatment.

[0106] For example, the chemical treatment in the above post-treatment step is performed to remove and dry the coagulant contained in the pores after the hollow fiber membrane is formed, and may include water washing, washing, hot water treatment, etc., and if necessary, the solution used for water washing, washing, hot water treatment, etc. may further include an antioxidant.

[0107] For example, the physical treatment in the above post-processing step may further include a stretching or shrinking process to control the size and shape of the pores inside the hollow fiber membrane to improve the strength and durability of the hollow fiber membrane.

[0108] According to one embodiment, after forming a hollow fiber membrane, a post-treatment may be performed by injecting a solution of the amine-based antioxidant in a second solvent into the hollow portion of the hollow fiber, followed by drying. Through this post-treatment, an antioxidant coating layer may be provided on the inner surface of the hollow fiber membrane. The post-treatment for providing an antioxidant coating layer on the inner surface of the hollow fiber membrane may be performed additionally to the process described above, or may be performed for the purpose of forming a selective antioxidant coating layer only on the inner surface of a hollow fiber membrane, which may or may not contain an antioxidant, after forming the hollow fiber membrane.

[0109] When forming such a coating layer, its thickness must be limited to a range that does not impair the moisture exchange ability of the hollow fiber membrane.

[0110] The hollow fiber membrane for a fuel cell humidifier manufactured through the process described above does not have an antioxidant bound to the hollow fiber through a crosslinking agent or binder, but is dispersed inside the hollow fiber membrane or forms a coating layer on the inner surface of the hollow fiber membrane, so that the antioxidant is easily dissolved and included in the external air during the moisture exchange process of the hollow fiber membrane.

[0111] A fuel cell membrane humidifier according to one aspect may include the hollow fiber membrane described above.

[0112] For the hollow fiber desert, please refer to the above, and below, the humidifier will be described with reference to FIGS. 1 and 2.

[0113] Figures 1 and 2 are perspective views of a fuel cell humidifier (100) according to one embodiment of the present invention.

[0114] As shown in FIGS. 1 and 2, the fuel cell humidifier (100) of the present invention includes a middle case (110), a cap case (120), a fixing part (130), and a hollow fiber membrane bundle (200).

[0115] The middle case (110) is combined with the cap case (120) to form the outer shape of the membrane humidifier (100). The middle case (110) and the cap case (120) may be made of a hard plastic such as polycarbonate or a metal. The middle case (110) and the cap case (120) may have a circular cross-sectional shape in the width direction, as shown in FIG. 1, or may have a polygonal cross-sectional shape in the width direction, as shown in FIG. 2. The polygon may be a rectangle, a square, a trapezoid, a parallelogram, a pentagon, a hexagon, etc., and the polygon may have rounded corners. In addition, the circle may be an oval.

[0116] In the middle case (110), a second fluid inlet (112) through which the second fluid is supplied and a second fluid outlet (113) through which the second fluid is discharged are formed.

[0117] In FIGS. 1 and 2, a plurality of hollow fiber membranes (210) are arranged in the middle case (110) in the form of a single hollow fiber membrane bundle (200), but the hollow fiber membranes (210) may also be arranged in the middle case (110) in a state of being divided and accommodated in two or more cartridges.

[0118]

[0119] A fluid inlet (121) is formed in the cap case (120). The fluid inlet (121) formed in one of the cap cases (120) respectively connected to both ends of the middle case (110) becomes a first fluid inlet, and the fluid inlet (121) formed in the other one becomes a first fluid outlet. The first fluid introduced through the fluid inlet (121) functioning as the first fluid inlet passes through the internal conduits (i.e., lumens) of the hollow fiber membranes (210) accommodated inside the middle case (110) and then exits through the fluid inlet (121) functioning as the first fluid outlet.

[0120] The ends of the hollow fiber membranes (210) are potted in the fixing member (130). The fixing member (130) binds the hollow fiber membranes (210) and fills the gap between the hollow fiber membranes (210) and the gap between the hollow fiber membranes (210) and the middle case (110). As a result, each of the two ends of the middle case (110) is blocked by the fixing member (130), and a flow path through which a second fluid passes is formed therein. The material of the fixing member (130) is known in the art, and a detailed description thereof is omitted herein.

[0121] Hereinafter, an embodiment of the present invention will be described through examples and comparative examples, and the scope of the present invention is not intended to be limited to the examples.

[0122]

[0123] Examples 1 to 3 and Comparative Examples 1 to 3

[0124] An amine-based antioxidant was mixed into a hollow fiber membrane polymer composition, and a spinning solution was prepared so that the amine-based antioxidant was included in the amount shown in Table 1 below based on the weight of the polymer contained in the hollow fiber membrane polymer composition. Then, the spinning solution was spun into a coagulation tank through a tubular spinneret, solidified in the coagulation tank, and then washed and dried to produce a humidifying membrane.

[0125] Here, the hollow fiber membrane polymer composition was prepared by mixing 20 wt% of polyethersulfone (PES), 3 wt% of polyvinylpyrrolidone (PVP), and 77 wt% of N-methyl-2-pyrrolidone (NMP) as a solvent, and a 60°C coagulating solution containing water and NMP mixed in a weight ratio of 7:3 was used in the coagulation tank. The spinning solution was passed through the air over a length of about 10 cm, solidified in the coagulation tank, and then washed and dried to produce a humidifying membrane.

[0126] Tinuvin 765 1) (by weight)Tinuvin PA 123 2) (by weight) UV40 3) (weight) UV94 4)(Weight) UV119 5) (Weight) Comparative Example 1-----Comparative Example 21----Comparative Example 3-1---Example 1--1--Example 2---1-Example 3----1

[0127] 1) Molecular weight of Tinuvin 765 = 508 g / mol

[0128] 2) Molecular weight of Tinuvin PA 123 = 737.20 g / mol

[0129] 3) Molecular weight of UV40 = 2600~3400 g / mol

[0130] 4) Molecular weight of UV94 = 2000~3100 g / mol

[0131] 5) Molecular weight of UV119 = 2285.75 g / mol

[0132] Evaluation Example 1 - Oxidation Resistance Evaluation

[0133] The humidifying films manufactured in Examples 1 to 3 and Comparative Examples 1 to 3 were immersed in a 1% H2O2 (containing 2 ppm FeSO4) solution at 80°C for 48 hours, 96 hours, 144 hours, and 192 hours, and then the weight loss ratio was confirmed. After a certain period of time, the ratio of the reduced weight to the initial oxide film weight was confirmed, and the results are shown in Table 2 below.

[0134] 48hrs post-residual weight ratio (%) 96hrs post-residual weight ratio (%) 144hrs post-residual weight ratio (%) 192hrs post-residual weight ratio (%) Comparative example 178604122 Comparative example 295929082 Comparative example 393898780 Exemplary example 194929188 Exemplary example 292898886 Exemplary example 390878583

[0135] As shown in Tables 1 and 2 above, Examples 1 to 3 using an amine-based antioxidant having a molecular weight exceeding 1000 had a significantly higher residual weight ratio than Comparative Example 1 that did not include an antioxidant, and confirmed that the residual weight ratio was higher for a long period of time than Comparative Examples 2 and 3 using an amine-based antioxidant having a molecular weight of 1000 or less. This suggests that an amine-based antioxidant having a molecular weight exceeding 1000 provides a beneficial effect in imparting long-term oxidation resistance to a hollow fiber membrane.

[0136] Evaluation Example 2 - Evaluation of Residual Antioxidant Content

[0137] The oxidation resistance of the humidifying membranes manufactured in Examples 1 to 3 and Comparative Examples 2 and 3 was evaluated over time, and the content ratio of the antioxidant remaining in the hollow fiber membrane was measured for each time, and is shown in Table 3 below.

[0138] The content of the above antioxidant was confirmed through NMR analysis.

[0139] 48hr post-residual antioxidant ratio (%) 96hr post-residual antioxidant ratio (%) 144hr post-residual antioxidant ratio (%) 192hr post-residual antioxidant ratio (%) Comparative example 285736049 Comparative example 388776555 Exemplary example 195918885 Exemplary example 295908581 Exemplary example 391847872

[0140] Referring to Table 3 above, it was confirmed that the hollow fiber membranes of Examples 1 to 3, which applied an antioxidant having a molecular weight exceeding 1000, had a higher content of antioxidant remaining over time than the comparative examples 2 and 3, which applied an antioxidant having a molecular weight of 1000 or less. This suggests that the antioxidant having a molecular weight exceeding 1000 is less eluted from the hollow fiber membrane without crosslinking or chemical bonding, and as a result, contributes to maintaining the oxidation resistance of the hollow fiber membrane for a long time.

[0141]

[0142] Examples 4 to 7 and Comparative Examples 4 to 6

[0143] An amine-based antioxidant was mixed into a hollow fiber membrane polymer composition, and a spinning solution was prepared so that the amine-based antioxidant was included in the amount shown in Table 4 below based on the weight of the polymer contained in the hollow fiber membrane polymer composition. Then, the spinning solution was spun into a coagulation tank through a tubular spinneret, solidified in the coagulation tank, and then washed and dried to produce a humidifying membrane.

[0144] Here, the hollow fiber membrane polymer composition was prepared by mixing 20 wt% of polyethersulfone (PES), 3 wt% of polyvinylpyrrolidone (PVP), and 77 wt% of N-methyl-2-pyrrolidone (NMP) as a solvent, and a 60°C coagulating solution containing water and NMP mixed in a weight ratio of 7:3 was used in the coagulation tank. The spinning solution was passed through the air over a length of about 10 cm, solidified in the coagulation tank, and then washed and dried to produce a humidifying membrane.

[0145] UV40 (weight part) Example 40.1 Example 51 Example 63 Example 75 Comparative Example 47 Comparative Example 50.05 Comparative Example 60

[0146] Evaluation Example 3 - Antioxidant Content Evaluation

[0147] The humidifying films manufactured in Examples 4 to 7 and Comparative Examples 4 to 6 were immersed in a 5% H2O2 (containing 5 ppm FeSO4) solution at 80°C for 24 hours, 48 ​​hours, and 72 hours, and then the weight loss ratio was confirmed. After a certain period of time, the ratio of the reduced weight to the initial oxide film weight was confirmed, and the results are shown in Table 5 below.

[0148] 24hr post-residual weight ratio (%) 48hr post-residual weight ratio (%) 72hr post-residual weight ratio (%) Example 4898073 Example 5918478 Example 6938985 Example 7969493 Comparative Example 4 Film formation failure Film formation failure Film formation failure Comparative Example 5847261 Comparative Example 6826855

[0149] Referring to Tables 4 and 5 above, it was confirmed that the oxidation resistance was improved as the amount of the amine-based antioxidant having a molecular weight exceeding 1000 increased to 0.1, 1, 3, and 5 parts by weight. Considering that the residual weight ratio of the hollow fiber membrane when the content of the antioxidant was 0.05 (Comparative Example 5) was similar to that of Comparative Example 6 which did not include the antioxidant, it was confirmed that the antioxidant should be included in an amount of at least 0.1 part by weight. In addition, when the content of the amine-based antioxidant exceeded 5 parts by weight and was used at 7 parts by weight, the viscosity of the dope solution increased, and the hollow fiber membrane could not be formed to maintain its shape. That is, it was confirmed that the amine-based antioxidant having a molecular weight exceeding 1000 can be used in an amount of at least 0.1 part by weight and at most 5 parts by weight.

[0150]

[0151] Evaluation Example 4 - Humidification Performance Evaluation

[0152] Humidifying membranes manufactured in Examples 4 to 7 and Comparative Example 6 were manufactured as H10N products and their humidifying performance was evaluated. The performance was evaluated by having wet air (2000 slpm, 70°C, RH 100%) and dry air (2000 slpm, 70°C) meet in counter flow, and the performance was confirmed by dew point, and the results are shown in Table 6.

[0153] Humidification performance (dew point) Example 460.3 Example 560.0 Example 659.8 Example 759.5 Comparative example 660.3

[0154] As shown in Table 6 above, considering that the humidifying films of Examples 4 to 7 containing an amine-based antioxidant exhibited a similar level of humidifying performance to the humidifying film of Comparative Example 6 not containing an amine-based antioxidant, it can be seen that when the amine-based antioxidant was contained in an amount of 0.01 to 5 parts by weight, the improvement in oxidation resistance was achieved without deterioration of the humidifying performance, which is the original function of the humidifying film.

Claims

1. A hollow fiber membrane for a fuel cell membrane humidifier, comprising a porous polymer and an amine-based antioxidant having a molecular weight exceeding 1000.

2. In paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above amine-based antioxidant has an oligomer or polymer structure.

3. In paragraph 1, The above amine antioxidant is poly-{6-[(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidyl)imino]} (Poly-{6-[(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidyl)imino)}), Chimassorb ® 2020, a hollow fiber membrane for a fuel cell membrane humidifier comprising a polymer of epichlorohydrin and 2,2,4,4,-Tetramethyl-7-oxa-3,20-diazadispiro- (5.1.11.2)heneicosan-21-one or a combination thereof.

4. In paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above-mentioned amine-based antioxidant is contained in an amount of more than 0 and less than 5 parts by weight based on 100 parts by weight of the above-mentioned porous polymer.

5. In paragraph 4, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above amine-based antioxidant is included in an amount of 0.1 to 5 parts by weight.

6. In paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above-mentioned amine-based antioxidant is physically dispersed in a porous polymer.

7. In paragraph 1, The above porous polymer is a hollow fiber membrane for a fuel cell membrane humidifier, comprising a sulfone group-containing polymer.

8. In paragraph 7, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above sulfone-containing polymer comprises a polysulfone-based polymer, a sulfonated polysulfone, a perfluorosulfonic acid (PFSA)-based polymer, a polyphenylsulfone-based polymer, a polyethersulfone (PES)-based polymer, or any combination thereof.

9. In paragraph 7, The above porous polymer further comprises an auxiliary polymer, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the auxiliary polymer comprises at least one selected from among polyvinylidene fluoride (PVDF) polymers, cellulose acetate, cellulose triacetate, polymethyl methacrylate, Nafion, polystyrene (PS) polymers, polytetrafluoroethylene (PTFE) polymers, polyacrylonitrile (PAN) polymers, polyetherimide (PEI) polymers, and polyimide (PI) polymers.

10. In paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above porous polymer is contained in an amount of 90 parts by weight or more and less than 100 parts by weight based on 100 parts by weight of the hollow fiber membrane.

11. In paragraph 1, The hollow fiber membrane above has a thickness of 0.5 nm to 1 mm, and is a hollow fiber membrane for a fuel cell membrane humidifier.

12. A fuel cell membrane humidifier comprising a hollow fiber membrane according to any one of claims 1 to 11.

13. A step of preparing a radiation source solution containing a polymer and an amine-based antioxidant having a molecular weight exceeding 1000; A step of irradiating the above-mentioned raw material into a coagulation tank through a nozzle; A method for manufacturing a hollow fiber membrane for a fuel cell membrane humidifier, comprising the step of solidifying a radiation source in the above-mentioned coagulation tank.

14. In paragraph 13, The above tubular radiator contains a mixed solution of a second solvent and a third solvent in a volume ratio of 3:7 to 7:3 as a core liquid in the hollow part, The second solvent comprises water, methanol, ethanol, isopropanol, acetone, hexane, pentane, benzene, toluene, carbon tetrachloride, o-dichlorobenzene, polyethylene glycol, or a combination thereof. A method for producing a hollow fiber membrane for a fuel cell humidifier, wherein the third solvent comprises N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl acetamide, dimethyl formamide, methyl ethyl ketone, tetrahydrofuran, tetramethyl urea, trimethyl phosphate, or a combination thereof.

15. In paragraph 14, A method for manufacturing a hollow fiber membrane for a fuel cell humidifier, wherein the above-mentioned core solution further includes the above-mentioned amine-based antioxidant.

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