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

Abstract

The present invention relates to: a hollow fiber membrane for fuel cell membrane humidifiers; a method for manufacturing same; and a membrane humidifier comprising same, the hollow fiber membrane comprising a porous polymer and a composite antioxidant, wherein the composite antioxidant comprises a metal-based antioxidant and an antioxidant aid.

Description

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

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

[0002] A fuel cell is a power generation battery that converts the chemical energy of hydrogen and oxygen into electrical energy through an electrochemical reaction. Unlike conventional chemical batteries such as dry batteries or storage batteries, fuel cells can continuously produce electricity as long as hydrogen and oxygen are supplied, and they have the advantage of being more than twice as efficient as internal combustion engines because there is no heat loss.

[0003] Furthermore, since it uses hydrogen and oxygen as raw materials and produces water as a byproduct, it is an eco-friendly energy generation device that produces no pollutants. Therefore, fuel cells have the advantage of not only being environmentally friendly but also reducing concerns about resource depletion caused by 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 low temperatures compared to other fuel cells and have a high power density.

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

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

[0008] The decomposition and degradation of hollow fiber membranes hinder the delivery of sufficiently moist air to the fuel cell stack, thereby reducing the efficiency of the fuel cell stack and the fuel cell as a whole.

[0009] Accordingly, there is a market demand for technology to protect hollow fiber membranes included in fuel cell membrane humidifiers from oxidizing substances and, furthermore, to prevent their decomposition and degradation.

[0010] The object of the present invention is to provide a hollow fiber membrane used in a membrane humidifier for a fuel cell that has durability against oxidizing substances transferred from the fuel cell into the membrane humidifier.

[0011] Depending on one aspect,

[0012] Includes porous polymer and composite antioxidant,

[0013] A hollow fiber membrane for a fuel cell membrane humidifier is provided, wherein the composite antioxidant comprises three or more different antioxidants selected from phenolic antioxidants, amine-based antioxidants, metal-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-based antioxidants, and reducing antioxidants.

[0014] Depending on other aspects,

[0015] A step of preparing a dope solution for forming a hollow fiber membrane comprising a polymer and a composite antioxidant comprising three or more different antioxidants selected from phenolic antioxidants, amine-based antioxidants, metal-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-oxidants, and reducing antioxidants;

[0016] A step of discharging the above dope solution into a coagulation bath through a tubular spinning device; and

[0017] A method for manufacturing a hollow fiber membrane for a fuel cell humidifier is provided, comprising the step of solidifying a spinning solution discharged into the above-mentioned coagulation bath, then winding and drying to obtain a hollow fiber membrane.

[0018] Depending on another aspect,

[0019] A fuel cell membrane humidifier comprising the above-mentioned hollow fiber membrane for a fuel cell membrane humidifier is provided.

[0020] According to one aspect, a hollow fiber membrane for a fuel cell membrane humidifier includes a composite antioxidant comprising three different types of antioxidants, thereby effectively preventing the progression of radical reactions when the porous polymer forming the framework of the hollow fiber membrane comes into contact with an oxidizing agent, thereby suppressing the decomposition of the porous polymer and, as a result, improving the durability of the membrane humidifier. In particular, by using a mixture of three or more different types of antioxidants, oxidation resistance is improved at a specific point in time after fuel cell operation, for example, in the early, middle, and / or late stages.

[0021] FIGS. 1 and FIGS. 2 are exploded perspective views of a humidifier for a fuel cell according to one embodiment.

[0022] The present inventive concept described below is subject to various modifications and may have various embodiments, and 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 and should be understood to include all modifications, equivalents, or substitutions that fall within the scope of the description of the present inventive concept.

[0023] The terms used below are used merely to describe specific embodiments and are not intended to limit the creative concept. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the following, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, components, materials, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, components, materials, or combinations thereof.

[0024] When it is stated that a component is "connected or coupled" to another component, it should be understood that the component may be directly connected or coupled to the other component, but that a new component may also exist between the component and the other component. On the other hand, when it is stated that a component is "directly connected" or "directly coupled" to another component, it should be understood that no new component exists between the component and the other component.

[0025] Throughout the specification, when a part such as a layer, film, region, plate, etc. is described as being "on" or "above" another part, this includes not only cases where it is immediately above another part, but also cases where there is another part in between. Throughout the specification, terms such as "first," "second," etc., may be used to describe various components, but the components should not be limited by these terms. The terms are used solely for the purpose of distinguishing one component from another.

[0026] As used throughout the specification, the term "polymer" refers to a polymer formed by the polymerization of one or more monomer units, and encompasses polymer resins and polymer polymers.

[0027] The embodiments described below are merely illustrative, and various modifications are possible from these embodiments.

[0028] A hollow fiber membrane for a fuel cell membrane humidifier according to one aspect comprises a porous polymer and a composite antioxidant, wherein the composite antioxidant may comprise three or more different antioxidants selected from phenolic antioxidants, amine-based antioxidants, metal-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-based antioxidants, and reducing antioxidants.

[0029] Here, the porous polymer is a polymer that forms a tube-shaped hollow fiber membrane having a hollow portion in the center and has a plurality of pores capable of selectively passing water molecules, having 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 an issue, and if the pore size is excessively small, moisture exchange is not easy, making it difficult to sufficiently humidify the outside air passing through the humidifier.

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

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

[0032] [Mathematical Formula 1]

[0033] Porosity (%) = (Air Volume / Total Volume) X 100

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

[0035] According to one embodiment, the composite antioxidant may be present by physically intervening in the network of the porous polymer.

[0036] For example, the composite antioxidant may be physically dispersed within the network of the porous polymer. For example, the porous polymer forms the framework of the hollow fiber membrane, the porous polymer includes a plurality of pores, and at least some of the composite antioxidant may be present within the pores.

[0037] For example, some of the above composite antioxidants may be physically attached to the surface of pores present in the network of porous polymers or embedded in the surface of pores.

[0038] According to one embodiment, the composite antioxidant can be embedded within the framework of a porous polymer to form an integral with the porous polymer.

[0039] For example, some of the above-mentioned composite antioxidant may exist on the pore surface of the porous polymer, and the remaining portion may be embedded within the framework of the porous polymer to form one body with the porous polymer.

[0040] Since the above-mentioned composite antioxidant does not form a chemical bond with the porous polymer, the composite antioxidant can leak out as outside air passes through the hollow parts of the hollow fiber membrane and be delivered to the fuel cell stack along with the humidified air. As a result, oxidizing substances generated in the stack during fuel cell operation can be removed before they are delivered to the humidifier.

[0041] According to one embodiment, the composite antioxidant may be incorporated into the hollow fiber membrane by a manufacturing process described below. For example, the composite antioxidant may be incorporated into the hollow fiber membrane during the membrane formation process by mixing it with a dope solution, or it may be incorporated into the hollow fiber membrane during the phase transition process by incorporating the composite antioxidant into the core solution and extruding it, or it may be incorporated into the hollow fiber membrane 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.

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

[0043] For example, the above-mentioned composite antioxidant is mixed into a dope solution, and any one of the plurality of antioxidants included in the above-mentioned composite antioxidant may be included in the core solution or in the hollow fiber membrane coating layer forming solution.

[0044] According to one embodiment, some of the composite antioxidants may be exposed and present on the surface of a porous polymer.

[0045] According to one embodiment, the composite antioxidant may be in the form of a dispersed layer on at least one of the inner and outer surfaces of the hollow fiber or in the form of a coating layer. For example, the composite antioxidant may be in the form of particles attached to at least one of the inner and outer surfaces of the hollow fiber, or a plurality of particles may form a coating layer.

[0046] For example, the above composite antioxidant particles can be uniformly distributed across the entire surface so as not to block the pores of the hollow fiber.

[0047] According to one embodiment, the composite antioxidant may form an antioxidant coating layer disposed on at least one of the inner and outer surfaces of the hollow fiber. In this case, the composite antioxidant coating layer may be configured to allow a certain amount of the antioxidant to leak out when in contact with the outside air. In order for the composite antioxidant to be configured to leak out a certain amount, there must be no chemical bonding between the antioxidant and the porous polymer, and it is advantageous to have it located on the inner surface of the membrane. Therefore, when forming the humidification membrane, crosslinking agents or additives capable of causing crosslinking between the antioxidant and the main polymer must not be used.

[0048] According to one embodiment, the composite antioxidant may include at least one of a phenolic antioxidant and an amine antioxidant.

[0049] For example, the above composite antioxidant may include a phenolic antioxidant and may further include two or more different antioxidants selected from amine-based antioxidants, metal-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-based antioxidants, and reducing antioxidants.

[0050] For example, the above composite antioxidant may include an amine-based antioxidant and may further include two or more different antioxidants selected from phenol-based antioxidants, metal-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-based antioxidants, and reducing antioxidants.

[0051] For example, the above composite antioxidant includes a phenolic antioxidant and an amine-based antioxidant, and may further include one or more antioxidants selected from metal-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-based antioxidants, and reducing antioxidants.

[0052] According to one embodiment, the composite antioxidant may be a mixture of three different types of antioxidants.

[0053] According to one embodiment, the composite antioxidant may be included in an amount greater than 0 and less than or equal to 5 parts by weight per 100 parts by weight of the porous polymer. 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.

[0054] When the above composite antioxidant satisfies the aforementioned numerical range, a porous polymer network can be formed during the hollow fiber membrane formation process, and durability against oxidizing substances can be achieved without a decrease in water exchange capacity due to pore clogging. In addition, as the antioxidant is included within the aforementioned range in the hollow fiber membrane, an antioxidant of 1 µg / 1000 hr or more can be supplied from the humidifying membrane into the fuel cell stack.

[0055] According to one embodiment, the composite antioxidant may comprise, with respect to 100 parts by weight of the composite antioxidant, 9 to 72 parts by weight or less of a phenolic antioxidant when present, 9 to 72 parts by weight or less of an amine-based antioxidant when present, 9 to 72 parts by weight or less of a metal-based antioxidant when present, 9 to 72 parts by weight or less of a phosphorus-based antioxidant when present, 9 to 72 parts by weight or less of a sulfur-based antioxidant when present, 9 to 72 parts by weight or less of a quinone-based antioxidant when present, 9 to 72 parts by weight or less of a bio-based antioxidant when present, and 9 to 72 parts by weight or less of a reducing antioxidant when present.

[0056] For example, the composite antioxidant may comprise 9 to 72 parts by weight of a phenolic antioxidant and 9 to 72 parts by weight of an amine-based antioxidant, and at least one antioxidant selected from metal-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-based antioxidants, and reducing antioxidants, in an amount of 9 to 72 parts by weight per 100 parts by weight of the composite antioxidant.

[0057] For example, the composite antioxidant may comprise 9 to 72 parts by weight of a phenolic antioxidant and 9 to 72 parts by weight of a metal-based antioxidant, and at least one antioxidant selected from phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-based antioxidants, and reducing antioxidants, in an amount of 9 to 72 parts by weight, based on 100 parts by weight of the composite antioxidant.

[0058] For example, the composite antioxidant may comprise 9 to 72 parts by weight of an amine-based antioxidant and 9 to 72 parts by weight of a metal-based antioxidant, and at least one antioxidant selected from phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-based antioxidants, and reducing antioxidants, in an amount of 9 to 72 parts by weight, based on 100 parts by weight of the composite antioxidant.

[0059] Phenolic antioxidants have higher reactivity with oxidizing agents compared to other antioxidants, offering an advantage in the initial oxidation prevention effect during fuel cell operation. Amine-based antioxidants, while having lower reactivity than phenolic antioxidants, have a lower leaching amount from the polymer support, making them advantageous for maintaining the oxidation resistance of the hollow fiber membrane for an extended period after fuel cell operation. Additionally, metal-based antioxidants contribute to maintaining the long-term oxidation resistance of the hollow fiber membrane because they have a lower leaching amount compared to amine-based antioxidants. Furthermore, phosphorus-based and sulfur-based antioxidants contribute to maintaining the oxidation resistance of the hollow fiber membrane even after prolonged fuel cell operation due to their low reactivity with oxidizing agents and low leaching amounts. Since reducing aids release antioxidant substances upon decomposition by oxidizing agents such as radicals, they provide the advantage of being able to quickly respond when high levels of oxidizing agents enter the humidifier due to rapid fuel cell operation.

[0060] Fuel cells are exposed to various environments, such as long-term operation or environments requiring high output in a short period; since the content of oxidizing substances entering the membrane humidifier changes each time, it is difficult to adequately cope with these diverse environments. The inventor of the present invention discovered that when multiple antioxidants are incorporated into a hollow fiber membrane in a non-crosslinked form, oxidation resistance can be provided evenly during the initial, middle, and late stages. Based on this finding, the inventor has developed a composite antioxidant capable of maintaining excellent oxidation resistance in various environments.

[0061] In particular, when the three types of antioxidants included in the above-mentioned composite antioxidant satisfy the aforementioned content range, excellent oxidation resistance of the hollow fiber membrane is obtained at the early, middle, and / or late stages after fuel cell operation.

[0062] According to one embodiment, the phenolic antioxidant is 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), 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), Irganox 1035 (Irganox 1035: Thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], manufactured by BASF), Irganox 1135 (Irganox 1135: Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 side-chain alkyl ester, manufactured by BASF), Irganox 1520L (Irganox 1520L: 4,6-bis(octylthiomethyl)-o-cresol, manufactured by BASF), Irganox 3125 (Irganox 3125, manufactured by BASF), Irganox 565 (Irganox 565: 2,4-bis(n-octylthio)-6-(4-hydroxy-3',5'-di-t-butylanilino)-1,3,5-triazine, manufactured by BASF), Adecastav (registered trademark) AO-80 (Adecastav 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,The above may include GA-80, GS (both manufactured by Sumitomo Chemical Co., Ltd.), Cyanox (registered trademark) 1790 (Cyanox 1790, manufactured by Cytech Inc.), and Vitamin E (manufactured by Eizai Inc.), or any combination thereof. For example, the above phenolic antioxidant may include octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate.

[0063] According to one embodiment, the phenolic antioxidant may be included in an amount greater than 0 parts by weight and less than or equal to 2 parts by weight per 100 parts by weight of the porous polymer.

[0064] For example, the above-mentioned phenolic antioxidant may be included in an amount of 0.1 parts by weight or more and 1.9 parts by weight or less, 0.2 parts by weight or more and 1.8 parts by weight or less, or 0.3 parts by weight or more and 1.5 parts by weight or less per 100 parts by weight of the porous polymer, but is not limited thereto, and a numerical range formed according to any combination of the aforementioned ranges may be selected.

[0065] When the above-mentioned phenolic antioxidant is included in the aforementioned amount, it is possible to maximize the antioxidant effect during the initial operation of the fuel cell without closing the pores of the porous polymer or hindering the formation of the porous polymer network.

[0066] According to one embodiment, the amine-based antioxidant may include phenyl-α-naphthylamine, phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-naphthyl-p-phenylenediamine, HALS-based compounds, or a combination thereof.

[0067] According to one embodiment, the amine-based antioxidant may be included in an amount greater than 0 parts by weight and less than 2 parts by weight per 100 parts by weight of the porous polymer.

[0068] For example, the above amine-based antioxidant may be included in an amount of 0.1 parts by weight or more and 1.9 parts by weight or less, 0.2 parts by weight or more and 1.8 parts by weight or less, or 0.3 parts by weight or more and 1.5 parts by weight or less per 100 parts by weight of the porous polymer, but is not limited thereto, and a numerical range formed according to any combination of the aforementioned ranges may be selected.

[0069] When the above-mentioned amine-based antioxidant is included in the aforementioned amount, the antioxidant effect can be maximized during the early and mid-stages of fuel cell operation without closing the pores of the porous polymer or hindering the formation of the porous polymer network.

[0070] According to one embodiment, the metal-based antioxidant may include metal microparticles, or metal ions, oxides thereof, salts thereof, or mixtures thereof.

[0071] For example, metal-based antioxidants may include cerium, nickel, tungsten, ruthenium, palladium, silver, rhodium, cesium, zirconium, cobalt, chromium, zinc, yttrium, manganese, iron, molybdenum, lead, vanadium, titanium, niobium, lanthanum, ions thereof, oxides thereof, salts thereof, or any mixture thereof.

[0072] According to one embodiment, the metal-based antioxidant may be included in an amount greater than 0 and less than 2 parts by weight per 100 parts by weight of the porous polymer.

[0073] For example, the metal-based antioxidant may be included in an amount of 0.1 parts by weight or more and 1.9 parts by weight or less, 0.2 parts by weight or more and 1.8 parts by weight or less, or 0.3 parts by weight or more and 1.5 parts by weight or less per 100 parts by weight of the porous polymer, but is not limited thereto, and a numerical range formed according to any combination of the aforementioned ranges may be selected.

[0074] When the above-mentioned metal-based antioxidant is included in the aforementioned amount, the antioxidant effect can be maximized during the mid-to-late stages of fuel cell operation without closing the pores of the porous polymer or hindering the formation of the porous polymer network.

[0075] According to one embodiment, the phosphorus-based 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]dioxafospherin-6-yl]oxy]ethyl]amine (Irgafos 12), bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl)ethyl ester phosphoric acid (Irgafos 38), Adecastab 329K, Adecastab PEP36, Adecastab PEP-8, Sandstab P-EPQ, Weston 618, Weston 619G, Ultranox 626, It may include (6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphospherine) (Smilizer GP), bis(2,4-dicumylphenyl)pentaerythritol diphosphate, or any mixture thereof.

[0076] According to one embodiment, the phosphorus-based antioxidant may be included in an amount greater than 0 parts by weight and less than 2 parts by weight per 100 parts by weight of the porous polymer.

[0077] For example, the above phosphorus-based antioxidant may be included in an amount of 0.1 parts by weight or more and 1.9 parts by weight or less, 0.2 parts by weight or more and 1.8 parts by weight or less, or 0.3 parts by weight or more and 1.5 parts by weight or less per 100 parts by weight of the porous polymer, but is not limited thereto, and a numerical range formed according to any combination of the aforementioned ranges may be selected.

[0078] When the above-mentioned phosphorus-based antioxidant is included in the aforementioned amount, it is possible to maximize the antioxidant effect during the initial and mid-stages of fuel cell operation without closing the pores of the porous polymer or hindering the formation of the porous polymer network.

[0079] According to one embodiment, the sulfur-based antioxidant may comprise dilaurylthiodipropionate (DLTDP), distearylthiodipropionate (DSTDP), ditridecylthiodipropionate (DMTDP), bis 2-methyl-4(3-alkylthio)-propionyloxy)-5-tert-butylphenol sulfide, tetrakismethylene-3-(laurylthio)propionate methane, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diyl bis[3-(dodecylthio)propionate] (2,2-Bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diyl bis[3-(dodecylthio)propionate]), or any mixture thereof.

[0080] According to one embodiment, the sulfur-based antioxidant may be included in an amount greater than 0 parts by weight and less than 2 parts by weight per 100 parts by weight of the porous polymer.

[0081] For example, the above-mentioned sulfur-based antioxidant may be included in an amount of 0.1 parts by weight or more and 1.9 parts by weight or less, 0.2 parts by weight or more and 1.8 parts by weight or less, or 0.3 parts by weight or more and 1.5 parts by weight or less per 100 parts by weight of the porous polymer, but is not limited thereto, and a numerical range formed according to any combination of the aforementioned ranges may be selected.

[0082] When the above-mentioned sulfur-based antioxidant is included in the aforementioned amount, it is possible to maximize the antioxidant effect during the initial and mid-stages of fuel cell operation without closing the pores of the porous polymer or hindering the formation of the porous polymer network.

[0083] According to one embodiment, the quinone-based antioxidant may include butylhydroquinone, 2-tert-butylhydroquinone, anthraquinone, or any mixture thereof.

[0084] According to one embodiment, the quinone-based antioxidant may be included in an amount greater than 0 parts by weight and less than 2 parts by weight per 100 parts by weight of the porous polymer.

[0085] For example, the above-mentioned quinone-based antioxidant may be included in an amount of 0.1 parts by weight or more and 1.9 parts by weight or less, 0.2 parts by weight or more and 1.8 parts by weight or less, or 0.3 parts by weight or more and 1.5 parts by weight or less per 100 parts by weight of the porous polymer, but is not limited thereto, and a numerical range formed according to any combination of the aforementioned ranges may be selected.

[0086] When the above-mentioned quinone-based antioxidant is included in the aforementioned amount, it is possible to maximize the antioxidant effect during the initial and mid-stages of fuel cell operation without closing the pores of the porous polymer or hindering the formation of the porous polymer network.

[0087] According to one embodiment, the biogenic antioxidant may include tocopherol, ascorbic acid, β-carotene, nicotinic acid, butyl hydroxyl anisol, or any mixture thereof. Here, the term "biogenic" means obtained by extraction from a natural material.

[0088] According to one embodiment, the bio-oxidant may be included in an amount greater than 0 parts by weight and less than 2 parts by weight per 100 parts by weight of the porous polymer.

[0089] For example, the above bio-oxidant may be included in an amount of 0.1 parts by weight or more and 1.9 parts by weight or less, 0.2 parts by weight or more and 1.8 parts by weight or less, or 0.3 parts by weight or more and 1.5 parts by weight or less per 100 parts by weight of the porous polymer, but is not limited thereto, and a numerical range formed according to any combination of the aforementioned ranges may be selected.

[0090] When the above-mentioned bio-oxidant is included in the aforementioned amount, it is possible to maximize the antioxidant effect during the initial and mid-stages of fuel cell operation without closing the pores of the porous polymer or hindering the formation of the porous polymer network.

[0091] According to one embodiment, the reducing antioxidant may include salsalate.

[0092] According to one embodiment, the reducing antioxidant may be included in an amount greater than 0 parts by weight and less than 2 parts by weight per 100 parts by weight of the porous polymer.

[0093] For example, the above-mentioned reducing antioxidant may be included in an amount of 0.1 parts by weight or more and 1.9 parts by weight or less, 0.2 parts by weight or more and 1.8 parts by weight or less, or 0.3 parts by weight or more and 1.5 parts by weight or less per 100 parts by weight of the porous polymer, but is not limited thereto, and a numerical range formed according to any combination of the aforementioned ranges may be selected.

[0094] When the above-mentioned reducing antioxidant is included in the aforementioned amount, oxidation of the porous polymer of the hollow fiber membrane can be prevented during the initial stage of fuel cell operation by preferentially reacting with oxidizing substances to be reduced without closing the pores of the porous polymer or hindering the formation of the porous polymer network, and the oxidation prevention effect during the initial and mid-stages of fuel cell operation can be maximized.

[0095] According to one embodiment, the porous polymer may include a polyvinylidene fluoride (PVDF)-based polymer, a polysulfone-based polymer, a sulfonated polysulfone, cellulose acetate, cellulose triacetate, polymethyl methacrylate, Nafion, a polystyrene (PS)-based polymer, a polytetrafluoroethylene (PTFE)-based polymer, a perfluorosulfonic acid (PFSA)-based polymer, a polyphenylsulfone-based polymer, a polyethersulfone (PES)-based polymer, a polyacrylonitrile (PAN)-based polymer, a polyetherimide (PEI)-based polymer, a polyimide (PI)-based polymer, or a combination thereof.

[0096] According to one embodiment, the porous polymer may include a sulfonate-containing polymer.

[0097] For example, the above sulfonate-containing polymer is not particularly limited as long as it is a polymer containing sulfonate groups within the main backbone, and the polymer may include polysulfone-based polymers, sulfonated polysulfone, perfluorosulfonic acid (PFSA)-based polymers, polyphenylsulfone-based polymers, polyethersulfone (PES)-based polymers, or any combination thereof.

[0098] According to one embodiment, the porous polymer may include a polyethersulfone-based polymer.

[0099] According to one embodiment, the porous polymer comprises the aforementioned sulfonate-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.

[0100] According to one embodiment, the porous polymer may further comprise at least one auxiliary polymer selected from polyvinylidene fluoride (PVDF)-based polymer, cellulose acetate, cellulose triacetate, polymethyl methacrylate, Nafion, polystyrene (PS)-based polymer, polytetrafluoroethylene (PTFE)-based polymer, polyacrylonitrile (PAN)-based polymer, polyetherimide (PEI)-based polymer, and polyimide (PI)-based polymer. When such an auxiliary polymer is used together with the sulfonate-containing polymer, it may be used in an amount of 5 to 20 parts by weight relative to the main polymer.

[0101] According to one embodiment, the porous polymer may be included in an amount of 90 parts by weight or more and less than 100 parts by weight per 100 parts by weight of the hollow fiber membrane.

[0102] For example, the above porous polymer may be included in an amount of 91 to 99 parts by weight, 92 to 98 parts by weight, 93 to 97 parts by weight, and 94 to 96 parts by weight per 100 parts by weight of the hollow fiber membrane.

[0103] When the porous polymer among the above hollow fiber membranes satisfies the above range, sufficient durability of the hollow fiber membrane is achieved, and sufficient moisture exchange capacity can be exhibited in the humidifier.

[0104] 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. When the thickness of the hollow fiber membrane satisfies the above range, the hollow fiber membrane for the membrane humidifier may possess strength and moisture exchange capacity.

[0105] 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.

[0106] For example, the above additive may include at least one of polyethylene glycol, glycerin, diethyl glycol, triethylene glycol, ethanol, polyvinylpyrrolidone, water, zinc chloride, and lithium chloride.

[0107] These additives may be selected and added in appropriate amounts within a range that does not impair the inherent properties of the hollow fiber membrane. In addition, it will be obvious to a person skilled in the art that known materials used in the manufacture of hollow fiber membranes may be used.

[0108]

[0109] According to one 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 polymer and a composite antioxidant comprising three different types of antioxidants selected from a polymer, a phenolic antioxidant, an amine antioxidant, a metal antioxidant, a phosphorus antioxidant, a sulfur antioxidant, a quinone antioxidant, a bio-oxidizing antioxidant, and a reducing antioxidant; discharging the dope solution into a coagulation bath through a tubular spinning device; and coagulating the discharging solution into the coagulation bath in the coagulation bath, then winding and drying it to obtain a hollow fiber membrane.

[0110] A problem has been raised regarding hollow fiber membranes for fuel cell humidifiers, where the polymer decomposes due to oxidation or radical reactions caused by hydrogen peroxide or hydroxyl radicals introduced from the fuel cell stack. Efforts have been made to coat the surface with an oxidation-resistant material or crosslink the hollow fiber membrane with an oxide-capturing agent to impart oxidation resistance to the hollow fiber membrane. However, when the hollow fiber membrane is coated with an oxidation-resistant material, the coating layer closes the pores of the hollow fiber membrane and / or acts as a resistance layer for moisture exchange, resulting in reduced humidification performance. When an oxide-capturing agent is crosslinked, impurities such as the crosslinking agent are inevitably included, preventing sufficient formation of the polymer framework. Furthermore, during the thermal crosslinking process, the polymer degrades, causing the porous structure to deform due to pore shrinkage, and consequently, a reduction in moisture exchange capacity has been identified.

[0111] The inventors completed the present invention by obtaining the insight that when an antioxidant is mixed in a mixed solvent with a dope for hollow fiber membrane production, and then the dope is spun and solidified, the antioxidant forms an integral part with the polymer backbone, thereby allowing the antioxidant to be contained within the polymer backbone structure.

[0112] In particular, the inventors confirmed that when a composite antioxidant comprising three or more different antioxidants selected from phenolic antioxidants, amine-based antioxidants, metal-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-based antioxidants, and reducing antioxidants is used, oxidation resistance is further improved at one or more of the early, middle, and late stages of fuel cell operation compared to when one or two types of antioxidants are used.

[0113] According to one embodiment, the dope solution may include the step of mixing a polymer and a complex antioxidant comprising three or more different antioxidants selected from a phenolic antioxidant, an amine-based antioxidant, a metal-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant, a quinone-based antioxidant, a bio-antioxidant, and a reducing antioxidant in an organic solvent, wherein the complex antioxidant is mixed in an amount greater than 0 parts by weight and less than or equal to 5 parts by weight per 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 later, for example, N-methyl-2-methylpyrrolidone.

[0114] The above solvent may include at least one of a first solvent, a second solvent, and a third solvent. For example, the above solvent may be a mixed solvent comprising two types of solvents among the first solvent, the second solvent, and the third solvent.

[0115] The first solvent above is a solvent that cannot dissolve the polymer at room temperature (e.g., 23 to 25°C) but can dissolve it at high temperature (e.g., 80°C or higher), and may include butanol, isobutanol, octanol, pentanol, isopentanol, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, polyoxyethylene octylphenyl ether, or a combination thereof.

[0116] The second solvent above is a solvent that does not dissolve the polymer and may include water, methanol, ethanol, isopropanol, acetone, hexane, pentane, benzene, toluene, carbon tetrachloride, o-dichlorobenzene, polyethylene glycol, or a combination thereof.

[0117] The above third solvent is a solvent capable of dissolving the polymer even at room temperature and may include N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, methyl ethyl ketone, tetrahydrofuran, tetramethylurea, or trimethyl phosphate.

[0118] A person skilled in the art may use a mixture of one or more of the first solvent, the second solvent, and the third solvent, taking into account the characteristics of the polymer raw material and the manufacture of a hollow fiber membrane having desired physical properties.

[0119] 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 antioxidant, the viscosity of the spinning solution, the porosity of the hollow fiber membrane, and the physical properties of the final hollow fiber membrane.

[0120] According to one embodiment, the spinning solution comprises a polymer forming the framework of a hollow fiber membrane, a composite antioxidant comprising three or more different antioxidants selected from a phenolic antioxidant, an amine-based antioxidant, a metal-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant, a quinone-based antioxidant, a bio-antioxidant, and a reducing antioxidant, and a solvent, and may further include additives as needed. During the process of forming the hollow fiber membrane from the spinning solution, the solvent is removed, so that the final product has a structure in which the composite antioxidant is included in a non-crosslinked form within the framework of a porous polymer. Here, the non-crosslinked form means that the porous polymer and the composite antioxidant are not connected by chemical bonds, but are physically dispersed in the pores between the networks of the porous polymer or are physically attached to the porous polymer.

[0121] According to one embodiment, the content of the polymer contained in the spinning solution may be 15 to 25 parts by weight with respect to 100 parts by weight of the total spinning solution. For example, the content of the polymer contained in the spinning solution may be 16 to 24 parts by weight, 17 to 23 parts by weight, 18 to 22 parts by weight, or 19 to 21 parts by weight.

[0122] According to one embodiment, the content of the composite antioxidant included in the spinning solution may be greater than 0 and less than 5 parts by weight relative to 100 parts by weight of the polymer constituting the framework of the hollow fiber membrane.

[0123] According to one embodiment, in the step of obtaining the spinning solution, the temperature at which a composite antioxidant comprising three or more different antioxidants selected from a polymer, a phenolic antioxidant, an amine-based antioxidant, a metal-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant, a quinone-based antioxidant, a bio-antioxidant, and a reducing antioxidant, and an additive are mixed in a solvent as needed, can be appropriately selected at room temperature or high temperature, taking into account the polymer, composite antioxidant, additive, and solvent used.

[0124] According to one embodiment, the mixing time of the spinning solution may be performed for a sufficient time for the polymer, the composite antioxidant, and any additive to be sufficiently dissolved and / or dispersed in the solvent.

[0125] 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 die without clogging.

[0126] 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 level. Alternatively, if necessary, the spinning solution may further include a viscosity modifier to control the viscosity.

[0127] According to one embodiment, the spinning solution may further include additives considering the film-forming properties and porosity of the hollow fiber membrane, the dispersibility of the antioxidant, and the viscosity of the spinning solution.

[0128] For example, the above additive may include at least one of polyethylene glycol, glycerin, diethyl glycol, triethylene glycol, ethanol, polyvinylpyrrolidone, water, zinc chloride, and lithium chloride.

[0129] According to one embodiment, the step of extruding the extruded liquid into a coagulation bath may include the step of extruding the extruded liquid using a tubular extruded device, for example, a double-tube extruded device or a triple-tube extruded device, but is not limited to such tubular types and can be used without limitation as long as the extrusion method capable of forming a hollow shape is used.

[0130] According to one embodiment, when the spinning solution is discharged into a coagulation bath through a double-tube spinning device, the composition of the spinning solution discharged from each tube of the double tube may be the same or different. For example, when the spinning solution is discharged using a triple-tube spinning device, the composition of the spinning solution passing through each tube may be the same or different. For example, when using a triple-tube spinning device, the composition of the spinning 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 spinning solution passing through the intermediate layer tube between the inner and outer sides may be different.

[0131] According to one embodiment, in the step of extruding the spinning solution into a coagulation bath, the spinning temperature may be set to a temperature equal to or higher than the mixing temperature of the spinning solution. In this case, when using a multi-tubular tube, the temperature of each individual tube can be set differently to enable extrusion at an optimal temperature for the spinning solution.

[0132] According to one embodiment, in the step of extruding the spinning solution into a coagulation bath, the discharge rate may be 5 to 100 g / min.

[0133] According to one embodiment, when the spinning solution is discharged through a tubular nozzle, a core solution may be discharged together with it into the hollow portion inside the tubular tube. The core solution may include a mixed solution of a second solvent and a third solvent.

[0134] 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 of the above range, an antioxidant contained in the spinning solution may be incorporated into the hollow fiber membrane during the phase transition process of the spinneret. 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.

[0135] When the above-mentioned core solution is mixed in the volume ratio of the above-mentioned second solvent and third solvent, the composite antioxidant may exist dispersed within the porous polymer without crosslinking (i.e., without being fixed by chemical bonding with the porous polymer as a non-crosslinked polymer).

[0136] According to one embodiment, the core solution may further include at least one antioxidant among a plurality of antioxidants constituting a composite antioxidant. By including an additional antioxidant in the core solution, the antioxidant may be dispersed to the inner surface of the hollow fiber membrane through phase separation during the hollow fiber membrane formation process. As a result, the antioxidant may be dispersed and present at a high concentration on the inner surface of the hollow fiber membrane. As described above, when the core solution containing the antioxidant is discharged together, the spinning solution may contain less or no antioxidant.

[0137] According to one embodiment, the spun material discharged from the spinning device can come into contact with the coagulating liquid in the coagulation bath through an air gap.

[0138] The above air gap is an area where the spun material comes into contact with air, and artificial cooling air can be flowed considering the physical properties of the spun material. For example, the length of the air gap can be set to 0.1 to 50 cm. The air gap is a section where a primary phase transition occurs, and the phase transition takes place through the exchange of moisture in the atmosphere and the organic solvent in the spinning 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.

[0139] The above-mentioned spinning material forms a porous hollow fiber membrane by passing through an air gap and coming into contact with the coagulation liquid contained in the coagulation bath to solidify.

[0140] According to one embodiment, the coagulation tank may be composed of one unit, but is not limited thereto and may be configured so that two or more coagulation tanks are arranged in succession. When there are two or more coagulation tanks, the coagulation liquid used in each coagulation tank may be the same or different.

[0141] According to one embodiment, the coagulation liquid contained in the coagulation bath performs the role of coagulating the discharge liquid discharged through the tube into the form of a hollow fiber membrane, and the coagulation liquid used therein can be appropriately selected and used by a person skilled in the art from among known coagulation liquids, taking into consideration the porosity of the hollow fiber membrane, the pore structure of the hollow fiber membrane, etc.

[0142] For example, the above coagulation solution may be a second solvent such as an acidic solution or water, or a mixed solvent of the second solvent and the third solvent may be used.

[0143] According to one embodiment, the hollow fiber membrane obtained by passing through the above coagulation bath may undergo a post-processing step.

[0144] According to one embodiment, the post-processing step may include a step of performing chemical treatment and / or physical treatment.

[0145] For example, the chemical treatment among the above post-treatment steps is performed to remove and dry the coagulated liquid contained within the pores after the formation of the hollow fiber membrane, and may include water washing, cleaning, and hot water treatment, and if necessary, the solution used for water washing, cleaning, hot water treatment, etc. may further include one or more antioxidants among the composite antioxidant or the plurality of antioxidants constituting the composite antioxidant.

[0146] For example, among the above post-processing steps, the physical treatment may further include stretching and shrinking processes to improve the tensile strength and durability of the hollow fiber membrane by controlling the size and shape of the internal pores of the hollow fiber membrane.

[0147] According to one embodiment, after forming a hollow fiber membrane, a post-treatment can be performed in which a solution in which a composite antioxidant or one or more of the materials constituting the composite antioxidant are dissolved in a second solvent is injected into the hollow portion of the hollow fiber, and then dried. Through this post-treatment, an antioxidant coating layer can 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 in addition to the process described above, or it may also be performed for the purpose of selectively providing an antioxidant coating layer only on the inner surface after manufacturing a hollow fiber membrane that contains or does not contain an antioxidant.

[0148] In the hollow fiber membrane for a fuel cell humidifier manufactured from the aforementioned process, the composite antioxidant is not bonded and fixed to the hollow fiber through a crosslinking agent or binder, but is dispersed within the hollow fiber membrane or forms a coating layer on the inner surface of the hollow fiber membrane, making it easy for the antioxidant to leach into the outside air during the moisture exchange process of the hollow fiber membrane.

[0149]

[0150] According to another aspect, a fuel cell membrane humidifier comprising a hollow fiber membrane for a fuel cell membrane humidifier is provided.

[0151] For details regarding hollow fiber membranes, refer to the foregoing description, and below, a humidifier will be described with reference to Figures 1 and 2.

[0152] FIGS. 1 and FIGS. 2 are perspective views of a humidifier (100) for a fuel cell according to one embodiment of the present invention.

[0153] As illustrated in FIGS. 1 and 2, the humidifier (100) for a fuel cell of the present invention comprises a middle case (110), a cap case (120), a fixing part (130), and a hollow fiber membrane bundle (200).

[0154] The middle case (110) combines 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 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 square, a square, a trapezoid, a parallelogram, a pentagon, a hexagon, etc., and the polygon may have rounded corners. Additionally, the circle may be an ellipse.

[0155] In the middle case (110), a second fluid inlet (112) through which a second fluid is supplied and a second fluid outlet (113) through which the second fluid is discharged are respectively formed.

[0156] In FIGS. 1 and 2, a plurality of hollow fiber membranes (210) are exemplified as being arranged in a 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 divided state in two or more cartridges.

[0157] A fluid inlet / outlet (121) is formed in the cap case (120). The fluid inlet / outlet (121) formed in one of the cap cases (120) each coupled to both ends of the middle case (110) becomes the first fluid inlet, and the fluid inlet / outlet (121) formed in the other becomes the first fluid outlet. The first fluid introduced through the fluid inlet / outlet (121) functioning as the first fluid inlet passes through the internal channels [i.e., lumens] of the hollow fiber membranes (210) contained inside the middle case (110) and then exits through the fluid inlet / outlet (121) functioning as the first fluid outlet.

[0158] The ends of the hollow fiber membranes (210) are mounted on the fixed part (130). The fixed part (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). Thus, each of the two ends of the middle case (110) is blocked by the fixed part (130), and a flow path through which a second fluid passes is formed inside. The material of the fixed part (130) is known and is omitted from detailed description in this specification.

[0159]

[0160] Hereinafter, an embodiment of the present invention is described through examples and comparative examples, and it is not intended to limit the scope of the present invention to these examples.

[0161]

[0162] Examples 1 to 18 and Comparative Example 1

[0163] A spinning solution was prepared such that a composite antioxidant, in which a plurality of antioxidants are mixed in the hollow fiber membrane polymer composition, is included in the amount shown in Table 1 below relative to the porous polymer content of the hollow fiber membrane. Then, the spinning solution was spun into a coagulation bath through a tubular tube, solidified in the coagulation bath, and then washed and dried to produce a humidified membrane.

[0164] Here, the hollow fiber membrane polymer composition was prepared by mixing 20 wt% polyethersulfone (PES), 3 wt% polyvinylpyrrolidone (PVP), and 77 wt% N-methyl-2-pyrrolidone (NMP) as a solvent, and a 60°C coagulation solution mixed with water and NMP in a weight ratio of 7:3 was used in the coagulation bath. The spinning solution was passed through the air over a length of about 10 cm, solidified in the coagulation bath, and then washed and dried to produce a humidified membrane.

[0165] Content relative to phenolic, amine, metal, phosphorus, sulfur, and quinone bioreducible porous polymers (based on weight) 4,4'-Biphenol (parts by weight) Tinuvin 783FDL (parts by weight) ZnO (parts by weight) Songnox 9228 PW (parts by weight) AO-412S (parts by weight) Anthraquinone (parts by weight) Nicotinic acid (parts by weight) Salsalat (parts by weight) e Example 10.50.50.51.5 Example 20.50.50.51.5 Example 30.50.50.51.5 Example 40.50.50.51.5 Example 50.50.50.51.5 Example 60.50.50.51.5 Example 70.50.50.51.5 Example 80.50.50.51.5 Example 9 20.50.53 Example 101.51.00.53 Example 111.50.51.03 Example 120.52.00.53 Example 131.01.50.53 Example 140.51.51.03 Example 150.50.52.03 Example 161.00.51.53 Example 170.51.01.53 Example 181.01.01.03 Comparative Example 1---

[0166]

[0167] Evaluation Example 1 - Evaluation of Antioxidant Effect

[0168] The humidification membranes prepared in Examples 1 to 18 and Comparative Example 1 were immersed in a 5% H2O2 (containing 3 ppm FeSO4) solution at a temperature of 80°C for 24 hours, and the ratio of the reduced weight relative to the initial oxide film weight was determined after immersion for 48 hours, and the ratio of the reduced weight relative to the initial oxide film weight was determined after immersion for 72 hours, and the results are shown in Table 2 below.

[0169] Weight loss ratio after 24 hours (early operation) Weight loss ratio after 48 hours (mid-operation) Weight loss ratio after 72 hours (late operation) Example 15 % 12 % 26 % Example 26 % 13 % 22 % Example 38 % 15 % 21 % Example 49 % 13 % 21 % Example 56 % 14 % 22 % Example 66 % 14 % 24 % Example 78 % 16 % 25 % Example 86 % 14 % 23 % Example 91 % 8 % 16 % Example 102 % 6 % 15 % Example 113 % 8 % 13 % Example 125 % 6 % 10 % Example 133 % 7 % 11 % Example 146 % 7 % 11 % Example 158 % 16 % 17 % Example 167 % 15 % 16 % Example 177 % 13 % 15 % Example 184 % 6 % 11 % Comparative Example 112 % 21 % 30 %

[0170] Referring to Tables 1 and 2 above, it was confirmed that in hollow fiber membranes containing equal amounts of three types of antioxidants, the initial antioxidant effect was excellent when a phenolic antioxidant was included, the initial-mid-stage antioxidant effect was excellent when an amine-based or metal-based antioxidant was included, and the late-stage antioxidant effect was excellent when phosphorus-based, sulfur-based, quinone-based, bio-based, or reducing antioxidants were included.

[0171] In addition, Examples 9 to 11, which had the highest content of the phenolic antioxidant among the three types of antioxidants, showed the smallest weight loss rate during the initial period (24 hr), suggesting that this is advantageous for ensuring the oxidation resistance of the hollow fiber membrane in situations where a large amount of oxidizing substances are generated during the initial operation of the fuel cell. Referring to Examples 12 to 14, which had the highest content of the amine-based antioxidant, the weight loss rate did not increase significantly from the initial period (24 hr) to the middle period (48 hr), suggesting that the amine-based antioxidant imparts oxidation resistance to the hollow fiber membrane during the initial and middle periods. Referring to Examples 15 to 17, which had the highest content of the phosphorus-based antioxidant, the weight loss rate did not increase significantly from the middle period (24 hr) to the late period (48 hr), suggesting that the phosphorus-based antioxidant imparts oxidation resistance to the hollow fiber membrane after the middle period.

[0172]

[0173] Examples 19 to 21 and Comparative Example 2

[0174] A phenolic antioxidant (4,4'-Biphenol), an amine-based antioxidant (product name: Tinuvin 783 FDL), and a phosphorus-based antioxidant (Songnox 9228 PW) were mixed in a 1:1:1 ratio in a hollow fiber membrane polymer composition, and spinning solutions were prepared such that the total content of the antioxidant mixture was 1.5, 3, and 4.5 parts by weight, respectively, based on the porous polymer content of the hollow fiber membrane. The spinning solutions were then spun into a coagulation bath through a tubular spinneret, solidified in the coagulation bath, and then washed and dried to produce a humidified membrane.

[0175] Here, the hollow fiber membrane polymer composition was prepared by mixing 20 wt% polyethersulfone (PES), 3 wt% polyvinylpyrrolidone (PVP), and 77 wt% N-methyl-2-pyrrolidone (NMP) as a solvent, and a 60°C coagulation solution mixed with water and NMP in a weight ratio of 7:3 was used in the coagulation bath. The spinning solution was passed through the air over a length of about 10 cm, solidified in the coagulation bath, and then washed and dried to produce a humidified membrane.

[0176] 4,4'-Bipehnol (parts by weight) Tinuvin 783 FDL (parts by weight) Songnox 9228 PW (parts by weight) Total weight (parts by weight) Example 1 90.50.50.51.5 Example 2 201.01.01.03 Example 2 11.51.51.54.5 Comparative Example 2----

[0177]

[0178] Evaluation Example 2 - Evaluation of Effects by Content of Complex Antioxidant

[0179] The humidification membranes prepared in Examples 19 to 21 and Comparative Example 2 were immersed in a 5% H2O2 (containing 3 ppm FeSO4) solution at a temperature of 80°C for 24 hours, and the ratio of the reduced weight relative to the initial oxide film weight was determined after immersion for 48 hours, and the ratio of the reduced weight relative to the initial oxide film weight was determined after immersion for 72 hours, and the results are shown in Table 4 below.

[0180] Weight loss rate after 24 hours Weight loss rate after 48 hours Weight loss rate after 72 hours Example 1: 96% 13% 22% Example 2: 04% 6% 11% Example 2: 12% 2% 3% Comparative Example 2: 12% 21% 30%

[0181] Referring to Tables 3 and 4 above, it was confirmed that oxidation resistance improved as the total content of the composite antioxidant increased to 1.5, 3, and 4.5 parts by weight, and that it was impossible to form a porous hollow fiber membrane when it exceeded 5 parts by weight.

[0182] Therefore, through these experimental data, it can be seen that it is possible to manufacture a hollow fiber membrane with improved oxidation resistance when the total content of the composite antioxidant is greater than 0 parts by weight and less than or equal to 5 parts by weight.

Claims

1. Includes a porous polymer and a composite antioxidant, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above-mentioned composite antioxidant comprises three or more different antioxidants selected from phenolic antioxidants, amine-based antioxidants, metal-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-based antioxidants, and reducing antioxidants.

2. In Paragraph 1, The above composite antioxidant comprises at least one of a phenolic antioxidant and an amine-based antioxidant, for a hollow fiber membrane for a fuel cell membrane humidifier.

3. In Paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above-mentioned composite antioxidant is included in an amount of 5 parts by weight or less per 100 parts by weight of a porous polymer.

4. In Paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above-mentioned composite antioxidant physically intervenes in the network of the above-mentioned porous polymer.

5. In Paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above-mentioned composite antioxidant is physically dispersed within the network of the above-mentioned porous polymer.

6. In Paragraph 1, The above-mentioned phenolic antioxidants are 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), and Irganox 3114 (Irganox 3114: 1,3,5-Tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, manufactured by BASF), 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), Irganox 1035 (Irganox 1035: Thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], manufactured by BASF), Irganox 1135 (Irganox 1135: Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-C7-C9 side-chain alkyl ester, manufactured by BASF), Irganox 1520L (Irganox 1520L: 4,6-bis(octylthiomethyl)-o-cresol, manufactured by BASF), Irganox 3125 (Irganox 3125, manufactured by BASF), Irganox 565 (Irganox 565: 2,4-bis(n-octylthio)-6-(4-hydroxy-3',5'-di-t-butylanilino)-1,3,5-triazine, manufactured by BASF), Adecastav (registered trademark) AO-80 (Adecastav 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 Inc.), Smilizer (registered trademark) BHT, the GA-80, the GS (the above,A hollow fiber membrane for a fuel cell membrane humidifier comprising Sumitomo Chemical Co., Ltd.), Cyanox (registered trademark) 1790 (Cyanox 1790, manufactured by Cytech Co., Ltd.) and Vitamin E (manufactured by Eisai Co., Ltd.), or any combination thereof.

7. In Paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above amine-based antioxidant comprises phenyl-α-naphthylamine, phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-naphthyl-p-phenylenediamine, HALS-based compounds, or any mixture thereof.

8. In Paragraph 1, The above-mentioned metal-based antioxidant comprises cerium, nickel, tungsten, ruthenium, palladium, silver, rhodium, cesium, zirconium, cobalt, chromium, zinc, yttrium, manganese, iron, molybdenum, lead, vanadium, titanium, niobium, lanthanum, ions thereof, oxides thereof, salts thereof, or any mixture thereof, for a hollow fiber membrane for a fuel cell membrane humidifier.

9. In Paragraph 1, The above phosphorus-based antioxidants are tris(2,4-di-t-butylphenyl)phosphite (Irgafos 168), tris[2-[[2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxafospherin-6-yl]oxy]ethyl]amine (Irgafos 12), bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl)ethyl ester phosphoric acid (Irgafos 38), Adecastab 329K, Adecastab PEP36, Adecastab PEP-8, Sandstab P-EPQ, Weston 618, Weston 619G, Ultranox 626, A hollow fiber membrane for a fuel cell membrane humidifier comprising (6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphospherine) (Smilizer GP), bis(2,4-dicumylphenyl)pentaerythritol diphosphate, or any mixture thereof.

10. In Paragraph 1, The above-mentioned sulfur-based antioxidant comprises dilaurylthiodipropionate (DLTDP), distearylthiodipropionate (DSTDP), ditridecylthiodipropionate (DMTDP), bis 2-methyl-4(3-alkylthio)-propionyloxy)-5-tert-butylphenol sulfide, tetrakismethylene-3-(laurylthio)propionate methane, 2,2-bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diyl bis[3-(dodecylthio)propionate] (2,2-Bis{[3-(dodecylthio)-1-oxopropoxy]methyl}propane-1,3-diyl bis[3-(dodecylthio)propionate]), or any mixture thereof, a hollow fiber membrane for a fuel cell membrane humidifier.

11. In Paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the above-mentioned quinone-based antioxidant comprises butylhydroquinone, 2-tert-butylhydroquinone, anthraquinone, or any mixture thereof.

12. In Paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier comprising the above-mentioned bio-antioxidants tocopherol, ascorbic acid, β-carotene, nicotinic acid, butyl hydroxyl anisol, or any mixture thereof.

13. In Paragraph 1, The above-mentioned reducing antioxidant is a hollow fiber membrane for a fuel cell membrane humidifier containing salsalate.

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

15. In Paragraph 14, The above porous polymer is a hollow fiber membrane for a fuel cell membrane humidifier comprising a polystyrene-based polymer.

16. In Paragraph 1, A hollow fiber membrane for a fuel cell membrane humidifier, wherein the thickness of the hollow fiber membrane for the fuel cell membrane humidifier is 0.5 nm to 1 mm.

17. A step of preparing a dope solution for forming a hollow fiber membrane comprising a composite antioxidant comprising three different types of antioxidants selected from polymers and phenolic antioxidants, amine-based antioxidants, metal-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, quinone-based antioxidants, bio-oxidants, and reducing antioxidants; A step of discharging the above dope solution into a coagulation bath through a tubular spinning device; and A method for manufacturing a hollow fiber membrane for a fuel cell humidifier, comprising the step of solidifying a spinning solution discharged into the above-mentioned coagulation bath, then winding and drying to obtain a hollow fiber membrane.

18. In Paragraph 17, The above tubular spinning device 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 liquid in the hollow part, and The second solvent comprises water, methanol, ethanol, isopropanol, acetone, hexane, pentane, benzene, toluene, carbon tetrachloride, o-dichlorobenzene, polyethylene glycol, or a combination thereof, and A method for manufacturing a hollow fiber membrane for a fuel cell humidifier, wherein the third solvent is N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, and comprises methyl ethyl ketone, tetrahydrofuran, tetramethylurea, trimethyl phosphate, or a combination thereof.

19. In Paragraph 17, A method for manufacturing a hollow fiber membrane for a fuel cell humidifier, wherein the above-mentioned core fluid further comprises a complex antioxidant.

20. A fuel cell membrane humidifier comprising a hollow fiber membrane for a fuel cell membrane humidifier according to any one of claims 1 to 16.

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