Hollow fiber membrane for fuel cell membrane humidifier and fuel cell membrane humidifier including same

Abstract

The present invention relates to a hollow fiber membrane, a manufacturing method therefor, and a fuel cell membrane humidifier comprising the hollow fiber membrane, the hollow fiber membrane comprising: a polymer support; and a metal-based antioxidant or a composite antioxidant comprising a metal-based antioxidant and an antioxidant adjuvant, wherein the metal-based antioxidant and / or the antioxidant adjuvant are dispersed in a non-crosslinked form in the polymer support, and the hollow fiber membrane selectively permeates moisture.

Description

Hollow fiber membrane for fuel cell membrane humidifier and fuel cell membrane humidifier including same

[0001] The present invention relates to a hollow fiber membrane and a fuel cell membrane humidifier including the same, and more particularly, to a hollow fiber membrane 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] When the peroxide or hydroxyl radicals generated in this way flow from the fuel cell stack to the membrane humidifier, there is a problem in that 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 an industrial demand for hollow fiber membranes that are resistant to decomposition by peroxide or hydroxyl radicals.

[0010] The present invention provides a hollow fiber membrane for a fuel cell membrane humidifier with improved durability that is prevented from deterioration and decomposition by peroxide or hydroxyl radicals.

[0011] According to one aspect, a hollow fiber membrane for a fuel cell membrane humidifier is provided, which comprises a polymer support and a metal-based antioxidant, wherein the metal-based antioxidant is dispersed in a non-crosslinked form within the polymer support and selectively permeates moisture.

[0012] According to one embodiment, the metal-based antioxidant may be included in an amount of more than 0 and less than 5 parts by weight based on 100 parts by weight of the hollow fiber membrane.

[0013] According to one embodiment, the metal-based antioxidant may be included in an amount of 0.001 to 5 parts by weight.

[0014] According to one embodiment, the metal-based antioxidant may include metal particles, metal ions, metal oxides, metal salts, or mixtures thereof.

[0015] According to one embodiment, the metal-based antioxidant may include one or more metals selected from the group consisting of cerium, nickel, tungsten, ruthenium, palladium, silver, rhodium, cesium, zirconium, cobalt, chromium, yttrium, manganese, iron, molybdenum, lead, vanadium, titanium, niobium, and lanthanum, or an ion of the metal, an oxide of the metal, a salt of the metal, or any mixture thereof.

[0016] According to one embodiment, the hollow fiber membrane may include a concentration gradient region in which the concentration of the metal-based antioxidant increases from the inner surface of the hollow fiber membrane toward the outer surface.

[0017] According to one embodiment, the hollow fiber membrane may further include a phenol-based antioxidant, a phosphorus-based antioxidant, an amine-based antioxidant, an organo-metallic antioxidant, a sulfur-based antioxidant, or a combination thereof.

[0018] According to one embodiment, the polymer may include a polyvinylidene fluoride (PVDF) polymer, a polysulfone polymer, a sulfonated polysulfone, cellulose acetate, cellulose triacetate, polymethyl methacrylate, Nafion, a polystyrene (PS) polymer, a polytetrafluoroethylene (PTFE) polymer, a perfluorosulfonic acid (PFSA) polymer, a polyphenylsulfone polymer, a polyethersulfone (PES) polymer, a polyacrylonitrile (PAN) polymer, a polyetherimide (PEI) polymer, a polyimide (PI) polymer, or a combination thereof.

[0019] According to one embodiment, the 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.

[0020] According to one embodiment, the hollow fiber membrane may have a thickness of 0.5 nm to 1 mm.

[0021] According to one embodiment, the hollow fiber membrane may have a weight loss ratio of less than 25% after being immersed in a 3% H2O2 solution at a temperature of 80°C for 48 hours.

[0022] A method for manufacturing a hollow fiber membrane for a fuel cell membrane humidifier is provided, comprising the steps of: preparing a spinning solution containing a polymer and a metal-based antioxidant according to one aspect; spinning the spinning solution into a coagulation tank through a nozzle; and solidifying the spinning solution in the coagulation tank.

[0023] According to one embodiment, the metal-based antioxidant may be included in an amount of more than 0 and less than 5 parts by weight based on 100 parts by weight of the radiation source.

[0024] According to one embodiment, the metal-based antioxidant may include one or more metals selected from the group consisting of cerium, nickel, tungsten, ruthenium, palladium, silver, rhodium, cesium, zirconium, cobalt, chromium, yttrium, manganese, iron, molybdenum, lead, vanadium, titanium, niobium, and lanthanum, or an ion of the metal, an oxide of the metal, a salt of the metal, or any mixture thereof.

[0025] According to one embodiment, the step of obtaining the radiation source comprises a step of mixing the antioxidant and the polymer in a solvent, wherein the solvent may include at least two solvents among a first solvent, a second solvent, and a third solvent.

[0026] According to one embodiment, the first solvent comprises butanol, isobutanol, octanol, pentanol, isopentanol, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, polyoxyethylene octylphenyl ether, or a combination thereof,

[0027] The second solvent comprises water, methanol, ethanol, isopropanol, acetone, hexane, pentane, benzene, toluene, carbon tetrachloride, o-dichlorobenzene, polyethylene glycol, or a combination thereof,

[0028] The third solvent may include N-methyl-2-pyrrolidone, dimethylsulfoxide, dimethylacetamide, dimethylformamide, methyl ethyl ketone, tetrahydrofuran, tetramethylurea, or trimethyl phosphate.

[0029] According to one embodiment, a post-treatment step may be further included after the step of coagulating the above-described radiation source.

[0030] According to one embodiment, the post-treatment step may include chemical treatment and / or physical treatment.

[0031] According to another aspect, a membrane humidifier for a fuel cell including the hollow fiber membrane is provided.

[0032] According to one aspect, a hollow fiber membrane for a fuel cell membrane humidifier is provided, comprising a polymer support and a composite antioxidant, wherein the composite antioxidant comprises a metal-based antioxidant and an antioxidant auxiliary agent.

[0033] According to one embodiment, the composite antioxidant may be included in an amount of 5 parts by weight or less per 100 parts by weight of the polymer support.

[0034] According to one embodiment, the content ratio of the metal-based antioxidant and the antioxidant auxiliary agent in the composite antioxidant may be 3:1 to 1:3.

[0035] In one embodiment, the complex antioxidant may be physically present in the network of the polymer support.

[0036] In one embodiment, the composite antioxidant may be physically dispersed and present within the network of the polymer support.

[0037] According to one embodiment, the metal-based antioxidant may include metal particles, metal ions, metal oxides, metal salts, or mixtures thereof.

[0038] According to one embodiment, 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.

[0039] According to one embodiment, the antioxidant may further include a phenolic antioxidant, a phosphorus antioxidant, an amine antioxidant, a sulfur antioxidant, a reducing agent, or a combination thereof.

[0040] According to one embodiment, the polymer may include a polyvinylidene fluoride (PVDF) polymer, a polysulfone polymer, a sulfonated polysulfone, cellulose acetate, cellulose triacetate, polymethyl methacrylate, Nafion, a polystyrene (PS) polymer, a polytetrafluoroethylene (PTFE) polymer, a perfluorosulfonic acid (PFSA) polymer, a polyphenylsulfone polymer, a polyethersulfone (PES) polymer, a polyacrylonitrile (PAN) polymer, a polyetherimide (PEI) polymer, a polyimide (PI) polymer, or a combination thereof.

[0041] According to one embodiment, the polymer may comprise a polystyrene-based polymer.

[0042] According to one embodiment, the thickness of the hollow fiber membrane for the fuel cell membrane humidifier may be 0.5 nm to 1 mm.

[0043] According to another aspect, a method for manufacturing a hollow fiber membrane for a fuel cell humidifier is provided, comprising the steps of: preparing a dope solution for forming a hollow fiber membrane comprising a composite antioxidant including a polymer and metal-based antioxidant and an antioxidant auxiliary agent; discharging the dope solution into a coagulation tank through a tubular spinning device; and coagulating the spinning solution discharged into the coagulation tank in the coagulation tank, and then winding and drying the spinning solution to obtain a hollow fiber membrane.

[0044] According to one embodiment, the tubular radiator includes a mixed solution of a second solvent and a third solvent in a volume ratio of 3:7 to 7:3 as a core solution in the hollow portion,

[0045] The second solvent comprises water, methanol, ethanol, isopropanol, acetone, hexane, pentane, benzene, toluene, carbon tetrachloride, o-dichlorobenzene, polyethylene glycol, or a combination thereof.

[0046] The third solvent may include N-methyl-2-pyrrolidone, dimethylsulfoxide, dimethylacetamide, dimethylformamide, methyl ethyl ketone, tetrahydrofuran, tetramethylurea, trimethyl phosphate, or a combination thereof.

[0047] According to one embodiment, the slurry may further comprise a complex antioxidant.

[0048] According to another aspect, a fuel cell membrane humidifier including the hollow fiber membrane for a fuel cell membrane humidifier described above is provided.

[0049] According to one aspect, the hollow fiber membrane comprises a polymer support and a metal-based antioxidant, so that hydroxyl radicals and / or peroxides contained in the high-temperature and humid steam generated in the fuel cell stack and introduced into the membrane humidifier preferentially react with the metal-based antioxidant, thereby suppressing deterioration and decomposition of the hollow fiber membrane including the polymer support, thereby improving the durability of the membrane humidifier. In addition, the outside air introduced into the membrane humidifier is humidified and supplied to the fuel cell stack. At this time, a trace amount of the metal-based antioxidant contained in the hollow fiber membrane is eluted and transported to the fuel cell stack as part of the humidified air, thereby preventing decomposition of the polymer electrolyte membrane by peroxides or hydroxyl radicals generated within the fuel cell stack. In addition, the hollow fiber membrane can improve durability against hydroxyl radicals and / or peroxides without reducing the moisture exchange capacity of the hollow fiber membrane by including the metal-based antioxidant in a certain content range. 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 humidifying capacity.

[0050] According to one aspect, a hollow fiber membrane for a fuel cell membrane humidifier effectively prevents a polymer support forming the skeleton of the hollow fiber membrane from contacting an oxidizing substance and undergoing a radical reaction by including a composite antioxidant, thereby suppressing decomposition of the polymer support and, as a result, improving the durability of the membrane humidifier.

[0051] Additionally, by appropriately selecting an antioxidant auxiliary agent used together with a metal-based antioxidant, the durability of the hollow fiber membrane can be selectively improved at the initial / mid-term or mid-term / late stage of fuel cell operation.

[0052] Figures 1 and 2 are exploded perspective views of a fuel cell humidifier according to one embodiment.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] The term "polymer" as used throughout the specification means a polymer formed by polymerization of one or more monomer units, and has a meaning encompassing polymer resins and polymer macromolecules.

[0058] The embodiments described below are merely exemplary, and various modifications are possible from these embodiments.

[0059]

[0060] [Hollow Desert General]

[0061] A hollow fiber membrane for a fuel cell membrane humidifier that selectively transmits moisture according to one side includes a polymer support and a metal-based antioxidant, and the metal-based antioxidant can be dispersed in a non-crosslinked form within the polymer support.

[0062] The polymer support is a porous polymer having a tube-shaped hollow fiber membrane having a hollow portion in the center and 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.

[0063] 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.

[0064] Additionally, the porosity of the polymer support 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 polymer support, as shown in the following mathematical equation 1.

[0065] [Mathematical Formula 1]

[0066] Porosity (%) = (air volume / total volume) X 100

[0067] The average pore size of the hollow fiber membrane not including the antioxidant is 0.1 nm to 100,000 nm, and the porosity is 50% to 90%. Even when the antioxidant is applied to the hollow fiber membrane, the difference in the 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 by hydroxyl radicals and peroxides is effectively prevented, thereby improving durability.

[0068] The hollow fiber membrane can prevent degradation of the hollow fiber membrane including the polymer due to hydrogen peroxide and / or hydroxyl radicals flowing in from the fuel cell stack by including a metal-based antioxidant, and a portion of the metal-based antioxidant included in the hollow fiber membrane can be contained in humidified air and transferred to the fuel cell stack, thereby preventing oxidation of the fuel cell stack. In addition, by removing hydrogen peroxide and / or hydroxyl radicals generated within the fuel cell stack during the operation of the fuel cell in advance, the content of hydrogen peroxide and hydroxyl radicals in the high-temperature, humid air transferred from the fuel cell stack to the membrane humidifier can be reduced.

[0069] The metal-based antioxidant included in the hollow fiber membrane not only blocks the radical-initiated reaction of the organic polymer forming the hollow fiber membrane with hydrogen peroxide and / or hydroxyl radicals by capturing hydrogen peroxide and / or hydroxyl radicals and suppresses decomposition of the organic polymer, but also has the effect of suppressing deformation of the hollow fiber membrane polymer even when high-temperature, high-humidity air is introduced from the stack by imparting the essential properties of a heat-resistant metal to the hollow fiber membrane.

[0070] 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.

[0071] According to one embodiment, the hollow fiber membrane has an inner surface (i.e., an inner surface) and an outer surface (i.e., an outer surface), and the metal-based antioxidant may be included in an antioxidant layer disposed on the inner surface, the outer surface, or the inner surface and the outer surface.

[0072] For example, the anti-oxidation layer may be a continuous coating layer or a discontinuous coating layer in the shape of an island.

[0073] According to one embodiment, the antioxidant may be dispersed within a polymer support having a network structure. For example, the antioxidant may have a particle shape and may be dispersed within the polymer support in a structure embedded within the polymer support. For example, the antioxidant may be dispersed within the network structure without forming bonds with the polymer support forming the skeleton of the hollow fiber membrane.

[0074] According to one embodiment, the antioxidant may be randomly or uniformly dispersed within the polymer support. For example, the antioxidant may be uniformly dispersed within the polymer support.

[0075] According to one embodiment, at least a portion of the antioxidant may be exposed to the outside (i.e., the outside of the hollow fiber membrane) from the inner or outer surface of the hollow fiber membrane. For example, a portion of the antioxidant exposed to the inner or outer surface of the hollow fiber membrane may be embedded within the polymer support skeleton structure, and only a portion thereof may be exposed to the outside.

[0076] According to one embodiment, the hollow fiber membrane may include a concentration gradient region in which the concentration of the antioxidant within the hollow fiber membrane varies. For example, the concentration of the antioxidant may increase from the inner surface of the hollow fiber membrane toward the outer surface.

[0077] By configuring the outer surface of the hollow fiber membrane to have a higher concentration of antioxidant than the inner surface, hydrogen peroxide and / or hydroxyl radicals contained in the high-temperature, humid air flowing into the humidifier from the fuel cell stack can be effectively captured and decomposed.

[0078] According to one embodiment, the antioxidant may be embedded in the polymer support constituting the hollow fiber membrane and dispersed in a non-crosslinked state. Here, non-crosslinked dispersion means that the polymer support having a network structure (i.e., porous) and the metal-based antioxidant are not chemically bonded together, but are physically dispersed in the pores between the network of the polymer support or are physically attached to the polymer support.

[0079] According to one embodiment, the metal-based antioxidant may include metal particles, metal ions, metal oxides, metal salts, or mixtures thereof.

[0080] For example, the metal-based antioxidant may include one or more metals selected from the group consisting of cerium, nickel, tungsten, ruthenium, palladium, silver, rhodium, cesium, zirconium, cobalt, chromium, yttrium, manganese, iron, molybdenum, lead, vanadium, titanium, niobium, and lanthanum, an ion of the metal, an oxide of the metal, a salt of the metal, or any mixture thereof.

[0081] According to one embodiment, the metal-based antioxidant may be included in an amount of more than 0 and less than or equal to 5 parts by weight, 0.001 to 5 parts by weight, 0.5 to 4.5 parts by weight, or 0.5 to 4 parts by weight, based on 100 parts by weight of the polymer support forming the skeleton of the hollow fiber membrane.

[0082] If the above hollow fiber membrane does not contain an antioxidant, the hollow fiber membrane may be decomposed by peroxide and / or hydroxyl radicals generated during fuel cell operation, resulting in a deterioration in the humidifying effect. If the amount exceeds 5 parts by weight, pores may not be sufficiently formed during the membrane forming process, or the pores of the hollow fiber membrane may be closed by the metal-based antioxidant particles, resulting in a decrease in moisture exchange performance, which may lead to a decrease in the performance of the membrane humidifier.

[0083] According to one embodiment, since the antioxidant is included in the hollow fiber membrane in a non-crosslinked form within the aforementioned range, an antioxidant of 1 ug / 1000 hr or more can be provided from the humidifying membrane into the fuel cell stack.

[0084] According to one embodiment, the hollow fiber membrane may further include an antioxidant auxiliary agent in addition to the metal-based antioxidant.

[0085] When the above hollow fiber membrane includes a metal-based antioxidant and the above antioxidant auxiliary agent (hereinafter referred to as a "composite antioxidant"), the composite antioxidant may be included in an amount of more than 0 and less than or equal to 5 parts by weight based on 100 parts by weight of the polymer support. For example, the composite antioxidant may be included in an amount of 1 part by weight or more and 4 parts by weight or less, or 1.5 parts by weight or more and 4 parts by weight or less, but is not limited thereto, and may be included in an appropriate numerical range within the aforementioned numerical range.

[0086] When the above-described composite antioxidant satisfies the aforementioned numerical range, a polymer support network can be formed during the hollow fiber membrane forming process, and durability against oxidizing substances can be ensured without a decrease in moisture exchange capacity due to pore blockage. In addition, since the hollow fiber membrane contains the antioxidant within the aforementioned range, an antioxidant of 1 ug / 1000 hr or more can be provided from the humidifying membrane into the fuel cell stack.

[0087] According to one embodiment, the weight-based content ratio of the metal-based antioxidant and the antioxidant auxiliary agent in the composite antioxidant may be 3:1 to 1:3. For example, the content ratio of the metal-based antioxidant and the antioxidant auxiliary agent may be 3:1 to 1:1, or 1:1 to 1:3.

[0088] The metal-based antioxidant included in the above complex antioxidant does not have a high reactivity with oxidizing substances, but it prevents the triggering of a chain reaction of polymers by removing oxidizing substances such as radicals, while the metal-based antioxidant itself does not decompose. Accordingly, the metal-based antioxidant provides long-term oxidation resistance within the membrane humidifier, and non-metallic antioxidants such as amine / phenolic antioxidants, which are antioxidant adjuvants, have a higher reactivity than metal-based antioxidants, so they have the advantage of effectively removing oxidizing substances in the early stages through a chemical reaction. However, since the antioxidant adjuvants also decompose at the same time as removing the oxidizing substances, there is a limitation in that the content of the antioxidant adjuvants within the membrane humidifier decreases over time. The complex antioxidant according to one embodiment of the present invention has the advantage that the metal-based antioxidant and the antioxidant adjuvants can be used both in environments requiring long-term durability and in high-power environments where high concentrations of oxidizing substances are instantaneously generated.

[0089] That is, when the content of the metal-based antioxidant and antioxidant auxiliary among the above-mentioned complex antioxidants satisfies the aforementioned range, a humidifying film can be manufactured that not only achieves a high level of durability but also efficiently responds to the momentary intrusion of a high level of radicals into the humidifier. However, when the numerical ratio range is exceeded, the membrane humidifier does not achieve sufficient oxidation resistance.

[0090] In one embodiment, the composite antioxidant may be physically present in the network of the polymer support.

[0091] For example, the complex antioxidant may be physically dispersed and present within a network of the polymer support. For example, the polymer support may form the skeleton of the hollow fiber membrane, the polymer support may include a plurality of pores, and at least a portion of the complex antioxidant may be present within the pores.

[0092] For example, some of the above complex antioxidants may be physically attached to the surface of pores present in the network of the polymer support or may be present embedded in the surface of the pores.

[0093] According to one embodiment, the composite antioxidant can be embedded within the skeleton of the polymer support to form an integral part with the polymer support.

[0094] For example, a portion of the above complex antioxidant may be present on the pore surface of the polymer support, and the remaining portion may be embedded within the skeleton of the polymer support to form one body with the polymer support.

[0095] Since the above-mentioned composite antioxidant does not form a chemical bond with the polymer support, the composite antioxidant can be released and delivered to the fuel cell stack along with the humidified air as ambient 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 being delivered to the humidifier.

[0096] According to one embodiment, the composite antioxidant may be incorporated into the hollow fiber membrane by the manufacturing process described below. For example, the composite 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, by including the composite antioxidant in the core solution and then discharging it and then being incorporated into the hollow fiber membrane during the phase inversion process, or by injecting a composite antioxidant solution into the hollow portion after manufacturing the hollow fiber membrane to form an antioxidant coating layer on the inner surface of the hollow fiber membrane and then being incorporated into the hollow fiber membrane.

[0097] For example, one of the above complex 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.

[0098] For example, the above complex antioxidant may be mixed into a dope solution, and any one of the plurality of antioxidants included in the complex antioxidant may be included in the core solution or in the hollow fiber membrane coating layer forming solution.

[0099] In one embodiment, some of the complex antioxidants may be present and exposed on the surface of the polymer support.

[0100] According to one embodiment, the composite 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 composite antioxidant may be attached in particle form to at least one of the inner and outer surfaces of the hollow fiber or a plurality of particles may form a coating layer.

[0101] For example, the composite antioxidant particles can be uniformly distributed over the entire surface so as not to block the pores of the hollow fiber.

[0102] According to one embodiment, the composite 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 composite 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 composite antioxidant to be configured so that a certain amount can flow out, there must be no chemical bonding between the antioxidant and the polymer support, and it is advantageous for the composite 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.

[0103] According to one embodiment, the antioxidant may further include a phenolic antioxidant, a phosphorus antioxidant, an amine antioxidant, a reducing agent, or a combination thereof.

[0104] For example, the phenolic antioxidants include 4,4'-biphenol, 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), 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,It may include Dong GS (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. For example, the phenolic antioxidant may include octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate.

[0105] According to one embodiment, the phenolic antioxidant may be included in an amount of more than 0 parts by weight and less than or equal to 2 parts by weight based on 100 parts by weight of the polymer support.

[0106] For example, the phenolic antioxidant may be included in an amount of 0.1 to 1.9 parts by weight, or 0.2 to 1.8 parts by weight, based on 100 parts by weight of the polymer support, but is not limited thereto, and a numerical range formed according to any combination of the above-mentioned ranges may be selected.

[0107] When the above-mentioned phenol-based antioxidant is included in the above-mentioned amount, the initial oxidation prevention effect of the fuel cell operation by the metal-based antioxidant can be maximized without closing the pores of the polymer support or inhibiting the network formation of the polymer support.

[0108] According to one embodiment, the amine antioxidant may include phenyl-α-naphthylamine, phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-naphthyl-p-phenylenediamine, a HALS compound, or a combination thereof.

[0109] According to one embodiment, the amine-based antioxidant may be included in an amount of more than 0 parts by weight and less than 2 parts by weight based on 100 parts by weight of the polymer support.

[0110] For example, the amine-based antioxidant may be included in an amount of 0.1 to 1.9 parts by weight, or 0.2 to 1.8 parts by weight, based on 100 parts by weight of the polymer support, but is not limited thereto, and a numerical range formed according to any combination of the above-mentioned ranges may be selected.

[0111] When the above-mentioned amine-based antioxidant is included in the above-mentioned amount, the oxidation prevention effect of the metal-based antioxidant can be maximized from the initial stage of fuel cell operation to the later stage without closing the pores of the polymer support or inhibiting the network formation of the polymer support.

[0112] According to one embodiment, the phosphorus antioxidant is 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 esterphosphorous acid (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), Bis(2,4-dicumylphenyl)pentaerythritol diphosphate, or a combination thereof.

[0113] According to one embodiment, the above-mentioned antioxidant may be included in an amount of more than 0 parts by weight and less than 2 parts by weight based on 100 parts by weight of the polymer support.

[0114] For example, the above-mentioned antioxidant may be included in an amount of 0.1 to 1.9 parts by weight, or 0.2 to 1.8 parts by weight, based on 100 parts by weight of the polymer support, but is not limited thereto, and a numerical range formed according to any combination of the above-mentioned ranges may be selected.

[0115] When the above-mentioned phosphorus antioxidant is included in the aforementioned amount, the initial oxidation prevention effect of the fuel cell operation by the metal-based antioxidant can be maximized without closing the pores of the polymer support or inhibiting the network formation of the polymer support.

[0116] According to one embodiment, the reducing agent may include salsalate.

[0117] According to one embodiment, the reducing agent may be included in an amount of more than 0 parts by weight and less than 2 parts by weight based on 100 parts by weight of the polymer support.

[0118] For example, the reducing agent may be included in an amount of 0.1 to 1.9 parts by weight, or 0.2 to 1.8 parts by weight, based on 100 parts by weight of the polymer support, but is not limited thereto, and a numerical range formed according to any combination of the above-mentioned ranges may be selected.

[0119] When the above-mentioned reducing agent is included in the above-mentioned amount, oxidation of the polymer support of the hollow fiber membrane can be prevented in the early stage of fuel cell operation by preferentially reacting with the oxidizing agent and being reduced without closing the pores of the polymer support or inhibiting the network formation of the polymer support, and oxidation of the polymer support can be prevented in the middle and late stages by the action of the metal-based antioxidant.

[0120] According to one embodiment, the hollow fiber membrane may further include an organo-metallic antioxidant and a sulfur-based antioxidant in addition to a metal-based antioxidant, as needed.

[0121] For example, the organo-metallic antioxidant may include a Ce-crown complex, a Ce-phosphoric acid complex, a Ce-Bypyridine, or any mixture thereof.

[0122] 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.

[0123] According to one embodiment, the polymer support may be selected from known polymers suitable for forming a hollow fiber membrane, and may include, for example, a polyvinylidene fluoride (PVDF) polymer, a polysulfone polymer, a sulfonated polysulfone, cellulose acetate, cellulose triacetate, polymethyl methacrylate, Nafion, a polystyrene (PS) polymer, a polytetrafluoroethylene (PTFE) polymer, a perfluorosulfonic acid (PFSA) polymer, a polyphenylsulfone polymer, a polyethersulfone (PES) polymer, a polyacrylonitrile (PAN) polymer, a polyetherimide (PEI) polymer, a polyimide (PI) polymer, or any combination of the above-mentioned polymers.

[0124] According to one embodiment, the polymer support may include a sulfone group-containing polymer.

[0125] 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.

[0126] According to one embodiment, the polymer support may include a polyethersulfone polymer.

[0127] According to one embodiment, the polymer support comprises the above-described sulfone-containing polymer as a main polymer, and may further comprise an auxiliary polymer described below in consideration of the desired properties of the hollow fiber membrane.

[0128] According to one embodiment, the polymer support may further include at least one auxiliary polymer selected from the group consisting of 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.

[0129] According to one embodiment, the polymer support may be included in an amount of 90 to less than 100 parts by weight, 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, based on 100 parts by weight of the hollow fiber membrane.

[0130] According to one embodiment, the thickness of the hollow fiber membrane may be 0.5 nm to 1 mm.

[0131] According to one embodiment, the hollow fiber membrane does not show a significant difference in porosity even when it includes a metal-based antioxidant.

[0132] For example, the average pore size of the hollow fiber membrane not including a metal-based antioxidant may be 0.1 nm to 100,000 nm, and the porosity may be 50% to 90%, and the average pore size of the hollow fiber membrane according to one embodiment of the present invention including a metal-based antioxidant may be 0.05 nm to 90,000 nm, and the porosity may be 45% to 85%.

[0133] Even when a metal-based antioxidant is applied to a hollow fiber membrane, the difference in the average pore size and porosity described above 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] According to one embodiment, the hollow fiber membrane has a water vapor permeability of 0.1 g / s / m measured under conditions of 1 bar pressure and 80 ℃ temperature. 2 It could be strange.

[0138] According to one implementation example, the hollow fiber membrane has a nitrogen permeability of 100 cc / min / cm under a pressure condition of 0.7 bar. 2 It could be as follows:

[0139] The above hollow fiber membrane has the aforementioned water vapor permeability, nitrogen permeability and oxygen permeability, and is suitable for use in a humidifier of a fuel cell with improved durability by having sufficient moisture exchange and gas permeability even when an antioxidant is introduced to improve durability.

[0140]

[0141] [Method for manufacturing hollow fiber membrane]

[0142] A method for manufacturing a hollow fiber membrane according to one aspect may include the steps of: mixing a spinning material including a polymer and a metal-based antioxidant in an organic solvent, wherein the metal-based antioxidant is mixed in an amount of more than 0 and 5 parts by weight or less, or 0.001 to 5 parts by weight, based on 100 parts by weight of the polymer to obtain a spinning solution; spinning the spinning solution into a coagulation tank through a nozzle; and solidifying the spinning solution in the coagulation tank.

[0143] According to another aspect, a method for manufacturing a hollow fiber membrane for a fuel cell humidifier is provided, comprising the steps of: preparing a dope solution for forming a hollow fiber membrane comprising a composite antioxidant comprising a polymer and metal-based antioxidant and an antioxidant auxiliary agent; discharging the dope solution into a coagulation tank through a tubular spinning device; and coagulating the spinning solution discharged into the coagulation tank in the coagulation tank, and then winding and drying the same to obtain a hollow fiber membrane.

[0144] For the overlapping components of the manufacturing method of the above hollow fiber membrane with the above-described ones, refer to the above.

[0145] Hollow fiber membranes for fuel cell humidifiers have been raised as having the problem of polymer decomposition due to oxidation or radical reactions caused by hydrogen peroxide or hydroxyl radicals flowing from the fuel cell stack. Efforts have been made to provide oxidation resistance to hollow fiber membranes by coating the surface with an oxidation-resistant substance or crosslinking the hollow fiber membrane with an oxide-containing scavenger. However, coating the hollow fiber membrane with an oxidation-resistant substance has limitations in that the coating layer closes the pores of the hollow fiber membrane and / or acts as a layer resisting moisture exchange, thereby reducing humidifying performance. In addition, crosslinking the oxide-containing scavenger inevitably includes impurities such as the crosslinker, preventing sufficient polymer skeleton formation. In addition, the polymer deteriorates during the thermal crosslinking process, resulting in pore shrinkage and deformation of the porous structure, which in turn reduces moisture exchange capacity.

[0146] The inventor of the present invention has obtained the knowledge that when an antioxidant is mixed in a mixed solvent with a dope for forming a hollow fiber membrane and the dope is then spun and solidified, the antioxidant can be incorporated into the polymer skeleton structure by forming an integral part with the polymer skeleton, thereby completing the present invention.

[0147] According to one embodiment, when a metal-based antioxidant and another antioxidant auxiliary are used together, it was confirmed that oxidation resistance is additionally improved at one or more of the initial, middle, and late stages of fuel cell operation due to the synergistic effect between the antioxidants compared to when the metal-based antioxidant is used alone.

[0148] According to one embodiment, when a metal-based antioxidant and another antioxidant auxiliary agent are used together, the dope solution may include a step of mixing a polymer and a complex antioxidant including the metal-based antioxidant and the antioxidant auxiliary agent in an organic solvent, and mixing the complex antioxidant in an amount of more than 0 part by weight and less than 5 parts by weight based on 100 parts by weight of the polymer to obtain a spinning solution. At this time, the organic solvent used in the preparation of the dope solution may be a third solvent described below, for example, N-methyl-2-methylpyrrolidone.

[0149] According to one embodiment, when only a metal-based antioxidant is used as the antioxidant, the step of obtaining the radiation source may include a step of mixing the metal-based antioxidant and a radiation material including the polymer in a solvent. In this case, the radiation material may further include the aforementioned additive.

[0150] 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.

[0151] 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 any combination thereof.

[0152] 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 any combination thereof.

[0153] 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, trimethyl phosphate, or any combination thereof.

[0154] 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.

[0155] 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.

[0156] According to one embodiment, the spinning solution comprises a polymer forming a hollow fiber membrane framework, an antioxidant, a solvent, and may further comprise additives as needed. The solvent is removed from the spinning solution during the process of forming the hollow fiber membrane, so that the final product has a structure in which the antioxidant or the antioxidant and the antioxidant auxiliary are contained in a non-crosslinked form in the polymer support framework. Here, the non-crosslinked form means that the polymer support and the complex antioxidant are not chemically bonded, but are physically dispersed in the pores between the network of the polymer support or are physically attached to the polymer support.

[0157] 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 (i.e., polymer composition). 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.

[0158] According to one embodiment, the content of the antioxidant or the antioxidant and antioxidant auxiliary agent contained in the radiation source may be more than 0 and less than 5 parts by weight, or 0.001 to less than 5 parts by weight, based on 100 parts by weight of the radiation source.

[0159] According to one embodiment, the solvent used in the preparation of the radiation source may include a third solvent. For example, the third solvent may include N-methyl-2-pyrrolidone.

[0160] According to one embodiment, the content of the solvent included in the spinning solution may be 75 to 85 parts by weight based on 100 parts by weight of the spinning solution. For example, the content of the solvent included in the spinning solution may be 75 to 80 parts by weight, or 76 to 79 parts by weight.

[0161] According to one embodiment, the temperature at which the polymer, antioxidant, antioxidant aid, 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, antioxidant aid, additive, and solvent used.

[0162] According to one embodiment, the mixing time of the above-described radiation source may be performed for a time sufficient for the polymer, antioxidant, antioxidant auxiliary agent, and any additives to be sufficiently dissolved and / or dispersed in the solvent.

[0163] 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.

[0164] 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, if necessary.

[0165] 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.

[0166] For example, the additive may include at least one of polyethylene glycol, glycerin, diethyl glycol, triethylene glycol, ethanol, polyvinylpyrrolidone, water, zinc chloride, salsalate, and lithium chloride.

[0167] According to one embodiment, the radiation source further comprises an additive, and the additive may comprise polyvinylpyrrolidone.

[0168] According to one embodiment, when the spinning solution contains an additive, the content of the additive contained in the spinning solution may be 1 to 5 parts by weight based on 100 parts by weight of the spinning solution. For example, the content of the additive contained in the spinning solution may be 2 to 4 parts by weight.

[0169] 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.

[0170] 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.

[0171] 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 injection of the radiation source at an optimal temperature.

[0172] 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.

[0173] 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.

[0174] 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 in the above range, the antioxidant or the antioxidant and antioxidant auxiliary contained in the core solution may be eluted outside the hollow fiber membrane during the phase conversion process of the radiation product, thereby minimizing loss and allowing them to be incorporated into the hollow fiber membrane. 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.

[0175] When the above-mentioned solution is mixed in the volume ratio of the second solvent and the third solvent, the antioxidant or the antioxidant and the antioxidant auxiliary agent can be dispersed and present within the polymer support without crosslinking (i.e., without being fixed by chemical bonding with the polymer support as non-crosslinking).

[0176] According to one embodiment, when an antioxidant and an antioxidant auxiliary are used together, the core solution may further include at least one of a phenol-based antioxidant and an amine-based antioxidant as an antioxidant auxiliary. By further including an antioxidant auxiliary 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 a core solution including an antioxidant is discharged together, the antioxidant can be contained in small amounts or not contained in the spinning solution.

[0177] According to one embodiment, the radiation emitted from the radiation device can contact the coagulation liquid in the coagulation tank through the air gap.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] For example, a second solvent such as an acidic solution or water may be used as the coagulant.

[0183] According to one embodiment, the coagulant may include a mixed solvent of a second solvent and a third solvent. For example, the coagulant may be a mixed solvent of water and NMP, and the water and NMP may be a mixed solvent in a mass ratio of 5:5 to 8:2, 6:4 to 8:2, or 7:3.

[0184] According to one embodiment, the hollow fiber membrane obtained through the above coagulation tank may undergo a post-processing step.

[0185] According to one embodiment, the post-treatment step may include performing a chemical treatment and / or a physical treatment.

[0186] Among the above post-treatment steps, the chemical treatment is performed to remove and dry the coagulant contained within 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 or an antioxidant auxiliary agent.

[0187] According to one embodiment, when a metal-based antioxidant and an antioxidant aid are used together, a post-treatment may be performed after forming a hollow fiber membrane, in which a solution of at least one of the metal-based antioxidant and the antioxidant aid dissolved in a second solvent is infiltrated 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 producing a hollow fiber membrane with or without an antioxidant and then selectively producing an antioxidant coating layer only on the inner surface.

[0188] The hollow fiber membrane for a fuel cell humidifier manufactured through the process described above does not have the antioxidant bonded and fixed 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 eluted into the outside air during the moisture exchange process of the hollow fiber membrane.

[0189] Among the above post-processing steps, physical processing may include stretching, shrinking, etc. 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.

[0190] A membrane humidifier according to one aspect may include the hollow fiber membrane for a membrane humidifier for a fuel cell as described above.

[0191]

[0192] [Mountain Humidifier]

[0193] For the hollow fiber desert, please refer to the above, and below, the humidifier will be described with reference to FIGS. 1 and 2.

[0194] Figures 1 and 2 are perspective views of a fuel cell humidifier (100) according to one embodiment of the present invention.

[0195] 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).

[0196] 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 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.

[0197] 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, respectively.

[0198] 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.

[0199] 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.

[0200] 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.

[0201]

[0202] Hereinafter, one 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.

[0203]

[0204] Example 1-1

[0205] A spinning solution was prepared by including 5 parts by weight of CeO2 as a metal-based antioxidant relative to a hollow fiber membrane polymer composition, and 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. Here, the hollow fiber membrane polymer composition includes 20 wt% of polyethersulfone (PES), 77 wt% of N-methyl-2-pyrrolidone (NMP), and 3 wt% of polyvinylpyrrolidone (PVP) as other additives, and the coagulation tank includes a coagulation solution in which water and NMP are mixed in a mass ratio of 7:3.

[0206] Example 1-2

[0207] A humidifying film was manufactured in the same manner as in Example 1-1, except that 3 parts by weight of CeO2 was used.

[0208] Example 1-3

[0209] A humidifying film was manufactured in the same manner as in Example 1-1, except that 1 part by weight of CeO2 was used.

[0210] Example 1-4

[0211] A humidifying film was manufactured in the same manner as in Example 1-1, except that 0.1 part by weight of CeO2 was used.

[0212] Comparative Example 1-1

[0213] A humidifying film was manufactured in the same manner as in Example 1-1, except that the metal-based antioxidant was not included in the radiation solution.

[0214] Comparative Example 1-2

[0215] A humidifying film was manufactured in the same manner as in Example 1-1, except that 6 parts by weight of CeO2 was used.

[0216]

[0217] Evaluation Example 1 - Evaluation of Antioxidant Effect

[0218] The humidifying films manufactured in Examples 1-1 to 1-4 and Comparative Examples 1-1 and 1-2 were immersed in a 3% H2O2 (containing 2 ppm FeSO4) solution at 80°C for 24 hours, and the molecular weight reduction ratio was confirmed. After immersion for 48 hours, the ratio of the reduced weight to the initial oxide film weight was confirmed, and the results are shown in Table 1 below.

[0219] Evaluation Example 2 - Humidification Performance Evaluation

[0220] The humidifying membranes manufactured in Examples 1-1 to 1-4 and Comparative Examples 1-1 and 1-2 were applied as humidifying membranes of H10N (a humidifying membrane product of Kolon Industries) to evaluate humidifying performance. 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 2.

[0221] Molecular weight reduction ratio after 24 hoursWeight reduction ratio after 24 hoursMolecular weight reduction ratio after 48 hoursWeight reduction ratio after 48 hoursExample 1-13%4%5%7%Example 1-23%4%5%7%Example 1-34%7%13%16%Example 1-45%7%19%22%Comparative Example 1-112%15%25%30%Comparative Example 1-2----

[0222] Humidification performance (dew point) Example 1-143 Example 1-249 Example 1-350 Example 1-450 Comparative example 1-150 Comparative example 1-2-

[0223] As shown in Table 1 above, the humidifying film of Example 1-1 including a metal-based antioxidant was confirmed to have a 9% lower molecular weight reduction rate after 24 hours than the humidifying film of Comparative Example 1-1 not including a metal-based antioxidant. In addition, the humidifying film of Comparative Example 1-2 including 6 parts by weight of a metal-based antioxidant failed to form a film because the pore structure was not maintained during the manufacture of the hollow fiber, making it impossible to measure the humidifying performance. In light of these data, it was confirmed that the humidifying film including 5 parts by weight or less of a metal-based antioxidant sufficiently prevented deterioration of the humidifying film while maintaining the moisture exchange ability, which is the original performance of the humidifying film.

[0224] In addition, it was confirmed that the humidifying performance decreased as the added content of the metal-based antioxidant increased from 0.1 parts by weight to 5 parts by weight, and it was confirmed that the humidifying performance decreased rapidly to a dew point value of 43 at 5 parts by weight. Therefore, it was confirmed that when the metal-based antioxidant was included in an amount exceeding 5 parts by weight, not only did the humidifying performance deteriorate, but also, as in Comparative Example 1-2, it was difficult to form a film, making it difficult to apply it as a humidifying film.

[0225] Example 1-5

[0226] A spinning solution was prepared by including 3 parts by weight of CeO2 as a metal-based antioxidant relative to a hollow fiber membrane polymer composition, and further adding 3% by weight of a salsalate compound relative to the polymer composition to prepare a spinning solution. The spinning solution thus obtained was spun into a coagulation tank through a tubular spinneret, solidified in the coagulation tank, and then washed and dried to prepare a humidifying membrane.

[0227] Here, the hollow fiber membrane polymer composition includes 20 wt% of polyethersulfone (PES), 77 wt% of N-methyl-2-pyrrolidone (NMP), and 3 wt% of polyvinylpyrrolidone (PVP) as other additives, and the coagulation tank includes a 60°C coagulation solution containing water and NMP mixed at a mass ratio of 7:3. In addition, the spinning solution was coagulated in the coagulation tank after passing through the air over a length of about 10 cm.

[0228]

[0229] Example 1-6

[0230] A hollow fiber membrane was manufactured in the same manner as in Example 1-5, except that 3 wt% of ZnO was used instead of the CeO2.

[0231]

[0232] Example 1-7

[0233] A hollow fiber membrane was manufactured in the same manner as in Example 1-5, except that 3 wt% of Co2O3 was used instead of the CeO2.

[0234]

[0235] Example 1-8

[0236] A hollow fiber membrane was manufactured in the same manner as in Example 1-5, except that 3 wt% of MnO2 was used instead of the CeO2.

[0237]

[0238] Comparative Example 1-3

[0239] For the hollow fiber membrane manufactured in Example 1-5, a high-temperature gas of 140°C was allowed to flow inside the hollow fiber membrane to physically perform thermal cross-linking, thereby producing a thermally cross-linked hollow fiber membrane.

[0240]

[0241] Comparative Example 1-4

[0242] For the hollow fiber membrane manufactured in Example 1-6, a high-temperature gas of 140°C was allowed to flow inside the hollow fiber membrane to physically perform thermal cross-linking, thereby producing a thermally cross-linked hollow fiber membrane.

[0243]

[0244] Comparative Example 1-5

[0245] For the hollow fiber membrane manufactured in Example 1-7, a high-temperature gas of 140°C was allowed to flow inside the hollow fiber membrane to physically perform thermal cross-linking, thereby producing a thermally cross-linked hollow fiber membrane.

[0246]

[0247] Comparative Example 1-6

[0248] For the hollow fiber membrane manufactured in Example 1-8, a high-temperature gas of 140°C was allowed to flow inside the hollow fiber membrane to physically perform thermal cross-linking, thereby producing a thermally cross-linked hollow fiber membrane.

[0249]

[0250] Evaluation Example 3: Elution Test of Non-cross-linked Hollow Fiber Membrane

[0251] Each of the hollow fiber membranes obtained in Examples 1-5 to 1-8 and Comparative Examples 1-3 to 1-6 was placed in a 0.5 M 80°C sulfuric acid solution and stirred for 30 minutes. The amount of metal-based antioxidant dissolved in each hollow fiber membrane was confirmed using an XRF analyzer. The ratio of the residual content after dissolution to the initial content of metal-based antioxidant in the hollow fiber membrane was calculated and shown in Table 3 below.

[0252] Residual amount after dissolution (%)Example 1-585.7 %Example 1-675.5 %Example 1-782.0 %Example 1-892.2 %Comparative Example 1-389.3 %Comparative Example 1-481.2 %Comparative Example 1-585.3 %Comparative Example 1-694.1 %

[0253] As shown in Table 3 above, it can be confirmed that the elution amount of Comparative Examples 1-3 to 1-6, in which a metal-based antioxidant was cross-linked to the hollow fiber membrane, was slightly reduced compared to the non-cross-linked Examples 1-5 to 1-8. However, no significant difference was observed compared to the non-cross-linked Examples 1-5 to 1-8.

[0254] Evaluation Example 4: Humidification Performance Test

[0255] The humidifying membranes manufactured in Examples 1-5 to 1-8 and Comparative Examples 1-3 and 1-6 were applied as humidifying membranes of H10N (a humidifying membrane product of Kolon Industries) to evaluate humidifying performance. 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 4.

[0256] Humidification performance (dew point) Example 1-549 Example 1-648 Example 1-748 Example 1-850 Comparative Example 1-342 Comparative Example 1-443 Comparative Example 1-542 Comparative Example 1-643

[0257] As shown in Table 4 above, it was confirmed that the humidifying performance of Comparative Examples 1-3 to 1-6, which underwent crosslinking treatment for hollow fiber membranes containing metal-based antioxidants, was significantly reduced compared to Examples 1-5 to 1-8, which were non-crosslinked. This is thought to be due to the high-temperature gas applied for crosslinking the metal-based antioxidant causing shrinkage of the pore structure, resulting in a reduction in humidifying performance.

[0258] That is, Examples 1-5 to 1-8, which include a non-crosslinked metal-based antioxidant, can provide sufficient oxidation durability and humidification performance of the hollow fiber membrane by having a similar level of outflow as the crosslinked type without any decrease in humidification performance. In addition, the oxidation stability of the fuel cell stack located at the rear end of the system can also be secured through the intentional elution of the metal-based antioxidant.

[0259] Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-4

[0260] A metal-based antioxidant (CeO2) and an antioxidant auxiliary agent (product name: Tinuvin 770) were mixed into a hollow fiber membrane polymer composition, and a spinning solution was prepared so that the CeO2 and Tinuvin 770 were included in the contents of the hollow fiber membrane polymer support in the amounts shown in Table 5 below. 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.

[0261] 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.

[0262] However, in the case of Comparative Example 2-4, after manufacturing the humidifying membrane, a post-treatment was additionally performed to crosslink the mixed antioxidant to the polyethersulfone polymer by flowing 140 degree dry air into the hollow fiber membrane tube for 3 hours.

[0263] CeO2 (parts by weight)Tinuvin 770 (parts by weight)Total weight partsExample 2-11.50.52Example 2-2112Example 2-30.51.52Comparative Example 2-1---Comparative Example 2-2202Comparative Example 2-3022Comparative Example 2-4112

[0264] Evaluation Example 5 - Evaluation of Antioxidant Effect

[0265] The humidifying films manufactured in Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-4 were immersed in a 5% H2O2 (containing 3 ppm FeSO4) solution at 80°C for 24 hours, and then the molecular weight reduction ratio was confirmed. After immersion for 48 hours, the ratio of the reduced weight to the initial oxide film weight was confirmed. After immersion for 72 hours, the ratio of the reduced weight to the initial oxide film weight was confirmed. The results are shown in Table 6 below.

[0266] Reduced weight percentage after 24 hours Reduced weight percentage after 48 hours Reduced weight percentage after 72 hours Example 2 - 16 % 12 % 19 % Example 2 - 26 % 12 % 19 % Example 2 - 36 % 12 % 21 % Comparative Example 2 - 112 % 21 % 30 % Comparative Example 2 - 27 % 13 % 18 % Comparative Example 2 - 35 % 11 % 23 % Comparative Example 2 - 46 % 13 % 19 %

[0267] Referring to Tables 5 and 6 above, in a hollow fiber membrane containing the same amount of complex antioxidant, it was confirmed that when an antioxidant auxiliary agent was mixed with a metal-based antioxidant, the oxidation resistance was improved in the initial (24 hr) and mid-term (48 hr) compared to when the metal-based antioxidant was used alone or when no antioxidant was used.

[0268] In addition, Comparative Example 4, which underwent crosslinking post-treatment, showed an antioxidant effect at a level similar to that of Examples 2-1 and 2-2, even though crosslinking was performed.

[0269] Examples 2-4 to 2-6 and Comparative Examples 2-5 to 2-6

[0270] A hollow fiber membrane polymer composition was mixed with a phenolic antioxidant (CeO2) and an antioxidant auxiliary agent (product name: Tinuvin 770), and a spinning solution was prepared so that the CeO2 and Tinuvin 770 were contained in a weight ratio of 3:1 as shown in Table 7. 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.

[0271] 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.

[0272] In the case of Examples 2-4 to 2-6 and Comparative Example 2-5, a humidifying film was well formed, but in the case of Comparative Example 2-6, the nozzle was clogged and the spinning solution could not maintain the hollow fiber, making it impossible to form a film into the hollow fiber.

[0273] CeO2 (parts by weight)Tinuvin 770 (parts by weight)Total weight partsExample 2-40.750.251Example 2-52.250.753Example 2-63.751.255Comparative Example 2-5---Comparative Example 2-65.251.757

[0274] Evaluation Example 6 - Evaluation of the Effect of Different Contents of Complex Antioxidants

[0275] The humidifying films manufactured in Examples 2-4 to 2-6 and Comparative Example 2-5 were immersed in a 5% H2O2 (containing 3 ppm FeSO4) solution at 80°C for 24 hours, and then the molecular weight reduction ratio was confirmed. After immersion for 48 hours, the ratio of the reduced weight to the initial oxide film weight was confirmed. After immersion for 72 hours, the ratio of the reduced weight to the initial oxide film weight was confirmed. The results are shown in Table 8 below.

[0276] 24hr48hr72hrExample 2-49 %15 %22 %Example 2-54 %6 %8 %Example 2-62 %3 %4 %Comparative Example 2-512 %21 %30 %

[0277] Referring to Tables 7 and 8 above, it was confirmed that the oxidation resistance improved as the total content of the composite antioxidant increased to 1, 3, and 5 parts by weight, and in the case of Comparative Example 2-6, which exceeded 5 parts by weight, it was impossible to form a porous hollow fiber membrane.

[0278] Therefore, these experimental data show that it is possible to manufacture a hollow fiber membrane with improved oxidation resistance when the total content of the complex antioxidant is more than 0 parts by weight and less than or equal to 5 parts by weight.

[0279] Examples 2-7 to 2-9 and Comparative Example 2-7

[0280] A spinning solution was prepared so that a phenol-based antioxidant (product name: Irganox1076), a phosphorus-based antioxidant (Irgafos 168), and a reducing agent (Salsalate) were included in a hollow fiber membrane polymer composition along with a metal-based antioxidant (CeO2) in an amount shown in Table 9 below with respect to the hollow fiber membrane polymer support content. 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.

[0281] 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.

[0282] CeO2 (parts by weight) Irganox 1076 (parts by weight) Irgafos 168 (parts by weight) Salsalate (parts by weight) Total weight Example 2-7 1.5 0.52 Example 2-8 1.5 0.52 Example 2-9 1.5 0.52 Comparative Example 2-7 ---- 0

[0283] Evaluation Example 7 - Evaluation of Antioxidant Effect

[0284] The humidifying films manufactured in Examples 2-7 to 2-9 and Comparative Example 2-7 were immersed in a 5% H2O2 (containing 3 ppm FeSO4) solution at 80°C for 24 hours, and the molecular weight reduction ratio was confirmed. After immersion for 48 hours, the ratio of the reduced weight to the initial oxide film weight was confirmed. After immersion for 72 hours, the ratio of the reduced weight to the initial oxide film weight was confirmed. The results are shown in Table 10 below.

[0285] 24hr48hr72hrExample 2-74 %9 %20 %Example 2-88 %13 %17 %Example 2-99 %14 %16 %Comparative Example 2-712 %21 %30 %

[0286] Referring to Tables 9 and 10 above, it was confirmed that when a phenol-based antioxidant aid was mixed with a metal-based antioxidant (Example 2-7), the initial (24 hr) oxidation resistance was significantly improved, and when a phosphorus-based antioxidant aid was used (Example 2-8) or a reducing aid was used (Example 2-9), the oxidation resistance was significantly improved in the later period (72 hr). In other words, it was confirmed that in a fuel cell operating environment where oxidizing substances are mainly generated in the early period, it is advantageous to use a combination of a metal-based antioxidant and a phenol-based antioxidant aid, and in a fuel cell operating environment where oxidizing substances are mainly generated in the later period, it is advantageous to use a combination of a metal-based antioxidant and a sulfur-based antioxidant or reducing aid.

[0287] Evaluation Example 8 - Humidifying Film Performance Evaluation

[0288] The humidifying performance of the humidifying membrane was evaluated by fabricating an H10N module (Kolon Industries) using the 24 cm, 1000 strands of the humidifying membranes manufactured in Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-4. Humid air at 80°C and 1350 SLPM was directed toward the inner surface of the membrane, and air at 85°C and 1500 SLPM was directed toward the outer surface of the membrane in a countercurrent direction. The dew point of the discharged dry air was measured and shown in Table 11, and based on this, it was confirmed whether the humidifying membrane could be used in practice.

[0289] Humidification performance (dew point, ℃) Example 2-158.2 Example 2-258.3 Example 2-358.3 Comparative Example 2-158.7 Comparative Example 2-258.5 Comparative Example 2-358.4 Comparative Example 2-452.1

[0290] Except for Comparative Example 2-4, a dew point result of 58 degrees or higher was confirmed. In the case of Comparative Example 2-4, which underwent cross-linking, it is thought that the performance decreased due to shrinkage of the internal pore structure of the humidifying membrane after the thermal cross-linking process. Since this performance decrease to the level of Comparative Example 2-4 is difficult to use as a humidifying membrane, it was determined that the cross-linked humidifying membrane cannot be applied as an actual humidifying membrane.

Claims

1. Contains a polymer support and a metal-based antioxidant, The above metal-based antioxidant is dispersed in a non-crosslinked form within the polymer support, A hollow fiber membrane for a fuel cell membrane humidifier that selectively transmits moisture.

2. In paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the metal-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 hollow fiber membrane.

3. In paragraph 2, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the metal-based antioxidant is contained in an amount of 0.001 to 5 parts by weight.

4. In paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the metal-based antioxidant comprises metal fine particles, metal ions, metal oxides, metal salts, or mixtures thereof.

5. In paragraph 4, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the metal-based antioxidant comprises at least one metal selected from the group consisting of cerium, nickel, tungsten, ruthenium, palladium, silver, rhodium, cesium, zirconium, cobalt, chromium, yttrium, manganese, iron, molybdenum, lead, vanadium, titanium, niobium, and lanthanum, or an ion of the metal, an oxide of the metal, a salt of the metal, or any mixture thereof.

6. In paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the hollow fiber membrane includes a concentration gradient region in which the concentration of the metal-based antioxidant increases from the inner surface to the outer surface of the hollow fiber membrane.

7. In paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the hollow fiber membrane further comprises an antioxidant additive.

8. In paragraph 7, The hollow fiber membrane for a fuel cell membrane humidifier, wherein the above hollow fiber membrane comprises an antioxidant auxiliary agent such as a phenol-based antioxidant, a phosphorus-based antioxidant, an amine-based antioxidant, a sulfur-based antioxidant, a reduction auxiliary agent, or a combination thereof.

9. In paragraph 7, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the weight-based content ratio of the metal-based antioxidant and the antioxidant auxiliary agent in the hollow fiber membrane is 3:1 to 1:

3.

10. In paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the polymer comprises a polyvinylidene fluoride (PVDF) polymer, a polysulfone polymer, a sulfonated polysulfone, cellulose acetate, cellulose triacetate, polymethyl methacrylate, Nafion, a polystyrene (PS) polymer, a polytetrafluoroethylene (PTFE) polymer, a perfluorosulfonic acid (PFSA) polymer, a polyphenylsulfone polymer, a polyethersulfone (PES) polymer, a polyacrylonitrile (PAN) polymer, a polyetherimide (PEI) polymer, a polyimide (PI) polymer, or a combination thereof.

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

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 a metal-based antioxidant; 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, A method for manufacturing a hollow fiber membrane for a fuel cell membrane humidifier, wherein the metal-based antioxidant is included in an amount of more than 0 and less than 5 parts by weight based on 100 parts by weight of the radiation source.

15. In paragraph 13, A method for producing a hollow fiber membrane for a fuel cell membrane humidifier, wherein the metal-based antioxidant comprises at least one metal selected from the group consisting of cerium, nickel, tungsten, ruthenium, palladium, silver, rhodium, cesium, zirconium, cobalt, chromium, yttrium, manganese, iron, molybdenum, lead, vanadium, titanium, niobium, and lanthanum, or an ion of the metal, an oxide of the metal, a salt of the metal, or any mixture thereof.

16. In paragraph 13, The above radiation source further contains an antioxidant additive, A method for manufacturing a hollow fiber membrane for a fuel cell membrane humidifier, wherein the total content of the above metal-based antioxidant and the above antioxidant auxiliary agent is more than 0 and less than 5 parts by weight based on 100 parts by weight of the above radiation source.

17. In paragraph 16, A method for manufacturing a hollow fiber membrane for a fuel cell membrane humidifier, wherein the antioxidant auxiliary agent comprises a phenol-based antioxidant, a phosphorus-based antioxidant, an amine-based antioxidant, a sulfur-based antioxidant, a reduction auxiliary agent, or a combination thereof.

18. In paragraph 13, The step of obtaining the above-mentioned radiation source includes a step of mixing the above-mentioned antioxidant and the above-mentioned polymer in a solvent, A method for manufacturing a hollow fiber membrane for a fuel cell membrane humidifier, wherein the solvent comprises at least two types of solvents among a first solvent, a second solvent, and a third solvent.

19. In paragraph 18, The first solvent comprises butanol, isobutanol, octanol, pentanol, isopentanol, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, polyoxyethylene octylphenyl ether, or a combination thereof, 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 membrane humidifier, wherein the third solvent comprises N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl acetamide, dimethyl formamide, methyl ethyl ketone, tetrahydrofuran, tetramethyl urea, or trimethyl phosphate.

20. In paragraph 13, A method for manufacturing a hollow fiber membrane for a fuel cell membrane humidifier, further comprising a post-treatment step after the step of coagulating the above-mentioned radiation source.

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