A hollow fiber membrane for fuel cell humidifier and preparation method thereof

Abstract

The present application relates to the field of fuel cell technology, and in particular to a hollow fiber membrane for a fuel cell humidifier and a preparation method thereof. The preparation method of the hollow fiber membrane for a fuel cell humidifier provided in the present application comprises the following steps: mixing a first polymer, a first porogen and a first solvent, stirring at 50-80°C for 4-8 hours, and standing for 5-48 hours to deaerate to obtain an intermediate layer spinning solution; mixing a second polymer, a second porogen and a second solvent, stirring at 50-80°C for 4-8 hours, and standing for 5-48 hours to deaerate to obtain an inner layer spinning solution; using the intermediate layer spinning solution and the inner layer spinning solution to prepare a hollow fiber membrane using a three-layer coaxial spinning machine; immersing the hollow fiber membrane in a coating solution, followed by heat treatment, cleaning and drying to achieve a single-sided hydrophilic treatment on the outer surface, thereby obtaining a hollow fiber membrane for a fuel cell humidifier.

Description

Technical Field

[0001] The present application relates to the field of fuel cell technology, and in particular to a hollow fiber membrane for a fuel cell humidifier and a preparation method thereof. Background Art

[0002] Proton exchange membranes (PEMs) are the core material of fuel cells. Commercial PEMs are primarily made of perfluorosulfonic acid resin membranes, which require water as the proton conducting medium. PEM fuel cells typically operate at a temperature of 80°C. At this temperature, water within the PEM evaporates, causing a sharp drop in proton conductivity and consequently, a dramatic decrease in battery performance, significantly shortening battery life. Therefore, maintaining a consistent humidity within the PEM within fuel cells is a key factor in improving performance and extending battery life.

[0003] Currently, membrane humidifiers are primarily used to maintain the humidity of the proton exchange membrane within fuel cells. Membrane humidifiers are categorized into flat-plate humidifiers and membrane tube humidifiers based on the membrane's morphology. The membrane tube humidifiers used in existing technologies are primarily hollow fiber membrane humidifiers. Hollow fiber membranes are made from perfluorosulfonic acid resins and suffer from issues such as easy swelling, poor dimensional stability, and high cost. Therefore, some researchers have incorporated high-performance polyetheretherketone (PEEK), polysulfone (PS), polyphenylsulfone (PS), and polyvinylidene fluoride (PVDF) into fuel cell hollow fiber membrane humidifiers, producing humidifiers assembled from hollow fiber membranes via dry-wet spinning methods. However, hollow fiber membranes made from these polymers have poor hydrophilicity, making them difficult to achieve the desired humidification effect. Currently, researchers are focusing on hydrophilizing polymers such as PEEK, polysulfone, and polyphenylsulfone, such as through sulfonation, or preparing hollow fiber membranes by dissolving a hydrophobic polymer and a hydrophilic polymer in a specific ratio into a spinning solution. The modified membrane tube is difficult to meet the requirements of enhancing dimensional stability, strength, barrier properties, hydrophilicity, etc. while improving the humidification effect.

[0004] Patent CN106378014A discloses a composite humidification membrane based on an asymmetric structure and its preparation method. Although the composite membrane has a double-layer structure, the hydrophilic polymer is coated only on the surface of the porous layer polymer. The thickness of the hydrophilic layer polymer is much smaller than that of the hydrophobic layer polymer. The large transmembrane resistance of the hydrophobic layer is not conducive to the transmission of water molecules, resulting in unsatisfactory humidification effect. Patent CN101765457A discloses a hollow fiber membrane for humidifiers and its manufacturing method. This method uses a perfluorosulfonic acid copolymer, polyvinyl alcohol or polyacrylonitrile to form the inner layer, and a polyetherimide, polyimide, polyamide imide, polysulfone or polyethersulfone to form the outer layer. The resulting fiber membrane has difficulty in achieving both good fiber strength and dimensional stability while simultaneously improving humidification effect. Patent CN 113926316 A discloses a leak-proof and humidifying composite hollow fiber membrane, a preparation method, and its application. One side of the fiber membrane is hydrophilic and the other side is hydrophobic. The hydrophilic layer as the middle layer is difficult to meet the requirements of enhancing the dimensional stability and hydrophilicity of the hollow fiber membrane while improving the humidification effect.

[0005] Based on the above analysis, it is very important to provide a method for preparing a hollow fiber membrane that can simultaneously meet the hydrophilicity and humidification effects. Summary of the Invention

[0006] The embodiments of the present application provide a method for preparing a hollow fiber membrane for a fuel cell humidifier to solve the problem in the related art that the existing hollow fiber membrane cannot simultaneously meet the requirements of dimensional stability, hydrophilicity and good humidification effect.

[0007] The present application provides a method for preparing a hollow fiber membrane for a fuel cell humidifier, comprising the following steps:

[0008] (1) preparing an intermediate layer spinning casting solution: mixing a first polymer, a first porogen, and a first solvent, stirring at 50 to 80° C. for 4 to 8 hours, and standing for 5 to 48 hours for degassing to obtain an intermediate layer spinning casting solution;

[0009] (2) preparing an inner layer spinning casting solution: mixing a second polymer, a second porogen, and a second solvent, stirring at 50 to 80° C. for 4 to 8 hours, and standing for 5 to 48 hours to degas, thereby obtaining an inner layer spinning casting solution;

[0010] (3) Phase inversion spinning: hollow fiber membranes are prepared using a three-layer coaxial spinning machine using the middle layer spinning solution and the inner layer spinning solution;

[0011] (4) Surface treatment: The hollow fiber membrane is immersed in a coating liquid, and then heat-treated, cleaned, and dried to achieve a one-sided hydrophilic treatment on the outer surface, thereby obtaining a hollow fiber membrane for a fuel cell humidifier.

[0012] In some embodiments, the mass percentages of the raw materials for preparing the intermediate layer spinning solution are: 15% to 30% of the first polymer, 0.1% to 15% of the first porogen, and 58% to 84% of the first solvent.

[0013] In some embodiments, the first polymer is a mixture of any one or more of sulfonated polyetheretherketone, sulfonated polysulfone, and sulfonated polyphenylsulfone with a sulfonation degree of 5% to 30%.

[0014] In some embodiments, the first porogen is a mixture of one or more of polyethylene glycol, polyvinyl pyrrolidone, lithium chloride, and potassium nitrate.

[0015] In some embodiments, the first solvent is a mixture of any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0016] In some embodiments, the mass percentages of the raw materials for preparing the inner layer spinning solution are: 5% to 30% of the second polymer, 1% to 10% of the second porogen, and 66% to 94% of the second solvent.

[0017] In some embodiments, the second polymer is a mixture of one or more of polyetheretherketone, polysulfone, polyphenylsulfone, and polyvinylidene fluoride.

[0018] In some embodiments, the second porogen is a mixture of one or more of polyethylene glycol, polyvinyl pyrrolidone, lithium chloride, and potassium nitrate.

[0019] In some embodiments, the second solvent is a mixture of any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0020] In some embodiments, the mass concentration of the coating liquid is 0.5% to 6%.

[0021] In some embodiments, the coating liquid is selected from a mixture of one or more of perfluorosulfonic acid resin, sulfonated polyetheretherketone with a sulfonation degree of 40% to 60%, sulfonated polysulfone, or sulfonated polyphenylsulfone.

[0022] In some embodiments, the phase inversion spinning process is as follows: the middle layer spinning casting liquid, the inner layer spinning casting liquid and the core liquid are extruded from the spinneret of the three-layer coaxial spinning machine together with the core liquid, and the core liquid and the external coagulation bath are both water; the liquid flow rate of the middle layer spinning casting liquid and the inner layer spinning casting liquid is controlled to be 1-10 mL / min, the core liquid flow rate is 1-10 mL / min, the temperature of the core liquid and the temperature of the external coagulation bath are 25-80°C, after a dry spinning stage of 3-50 cm, washed with water for 24-72 hours and dried to obtain a hollow fiber membrane, the inner layer thickness of the hollow fiber membrane is 2-20 microns, the middle layer thickness is 50-100 microns, and the outer layer thickness is 2-20 microns.

[0023] In the second aspect, the present application also provides a hollow fiber membrane prepared using the above-mentioned preparation method, wherein the hollow fiber membrane has a three-layer gradient hydrophilicity and hydrophobicity structure, the outer hydrophilic layer is one of polyetheretherketone, polysulfone, polyphenylsulfone or perfluorosulfonic acid resin with a higher degree of sulfonation, and its thickness is much smaller than the thickness of the middle layer. The outer hydrophilic layer is coated on the surface of the hollow fiber membrane with a two-layer composition structure prepared by dry-wet spinning. The strong hydrophilic surface is beneficial for the hollow fiber to capture water molecules in wet gas; the thicker middle layer is one of polyetheretherketone, polysulfone, and polyphenylsulfone with a low degree of sulfonation. While ensuring strength and dimensional stability, the hydrophilic functional groups with a low degree of sulfonation can form hydrophilic channels between the micropores of the middle layer, which is beneficial to the water molecule transmission effect; the inner hydrophobic layer is one of polyetheretherketone, polysulfone, polyphenylsulfone, and polyvinylidene fluoride, the thickness of which is much smaller than the thickness of the middle layer. The hydrophobic inner surface can enable water molecules to escape quickly, thereby improving the humidification efficiency of the gas.

[0024] The beneficial effects of the technical solution provided by this application include:

[0025] (1) The humidification hollow fiber membrane prepared in the present application has a three-layer gradient hydrophilicity structure. The thickness of the inner hydrophobic layer and the outer hydrophilic layer of the membrane are both less than the thickness of the middle layer. The three-layer structure has different hydrophilicities, which is conducive to the capture of water molecules on the outer surface, the transfer and penetration of water molecules in the middle layer, and the escape of water vapor on the inner surface;

[0026] (2) The hollow fiber membrane prepared in this application is conducive to the directional transport of water from the outer surface through the middle layer to the inner surface, and the inner hydrophobic layer can effectively prevent the reverse penetration of water molecules. Compared with the traditional hydrophilic humidification hollow fiber membrane, it has excellent humidification performance;

[0027] (3) The hollow fiber membrane prepared in this application has a strong hydrophilic outer layer, which is conducive to the capture and permeation of water molecules. At the same time, the surface is not easily contaminated during the humidification process and is easy to clean, thereby improving the humidification effect and the service life of the membrane. The inner hydrophobic layer is easy for water vapor to escape when the dry gas circulates, which can effectively improve the dry gas humidification efficiency;

[0028] (4) The hollow fiber membrane prepared in this application exhibits asymmetric hydrophilic / hydrophobic properties on both sides of the membrane. The hollow fiber membrane prepared by coaxial spinning and having an inner hydrophobic layer and a middle layer with a low degree of sulfonation has a mechanical strength of 2 to 14a. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 This is a cross-sectional view of the hollow fiber membrane prepared in Example 1 of the present application;

[0031] Figure 2 This is a partial cross-sectional view (SEM image) of the hollow fiber membrane prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0032] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0033] The embodiment of the present application provides a method for preparing a hollow fiber membrane for a fuel cell humidifier, which can solve the problem in the related art that the existing hollow fiber membrane cannot simultaneously meet the requirements of dimensional stability, hydrophilicity and good humidification effect.

[0034] Example 1:

[0035] Example 1 provides a method for preparing a hollow fiber membrane for a fuel cell humidifier, comprising the following steps:

[0036] (1) Preparing an intermediate layer spinning casting solution: sulfonated polyphenylsulfone with a sulfonation degree of 15% was vacuum dried at 80°C for 24 hours to remove moisture, and then the sulfonated polyphenylsulfone was dissolved in N-methylpyrrolidone, and then polyvinylpyrrolidone K30 was added. The mixture was mechanically stirred at 70°C for 6 hours, and allowed to stand for degassing for 24 hours to obtain a uniform and transparent intermediate layer spinning casting solution for use. The mass percentages of the raw materials were as follows: 26% sulfonated polyphenylsulfone, 8% polyvinylpyrrolidone, and 66% N-methylpyrrolidone.

[0037] (2) Preparing an inner layer spinning casting solution: sulfonated polyphenylsulfone with a sulfonation degree of 15% was vacuum dried at 80°C for 24 hours to remove moisture, and then the sulfonated polyphenylsulfone was dissolved in N-methylpyrrolidone, and then polyvinylpyrrolidone K30 was added. The mixture was mechanically stirred at 70°C for 6 hours, and allowed to stand for degassing for 24 hours to obtain a uniform and transparent inner layer spinning casting solution for use; wherein the mass percentages of the raw materials are: 26% sulfonated polyphenylsulfone, 8% polyvinylpyrrolidone, and 66% N-methylpyrrolidone;

[0038] (3) Phase transformation spinning:

[0039] The middle layer spinning casting solution and the inner layer spinning casting solution are extruded together with the core solution from the spinneret of the three-layer coaxial spinning machine, and the core solution and the outer coagulation bath are both water; the flow rate of the middle layer spinning casting solution and the inner layer spinning casting solution is controlled to be 2 mL / min, the flow rate of the core solution is controlled to be 2 mL / min, the temperature of the core solution and the temperature of the outer coagulation bath are both 60°C, after a 40 cm dry spinning stage, the membrane is washed with water and dried to obtain a hollow fiber membrane for standby use;

[0040] (4) Hollow fiber surface treatment:

[0041] The obtained hollow fiber membrane was quickly immersed in a 2% mass concentration perfluorosulfonic acid resin solution (solution temperature was 40°C) for 6 seconds, and then heat treated at 100°C for 2 minutes. It was further washed and dried to achieve a single-side hydrophilic treatment of the outer surface, thus obtaining a hollow fiber membrane for a fuel cell humidifier. The cross-sectional view and partial cross-sectional view of the hollow fiber membrane are shown in FIG. Figure 1 and Figure 2 ,from Figure 1 and Figure 2 It can be seen that the fiber membrane prepared in this application is a hollow porous structure.

[0042] Example 2:

[0043] Example 2 provides a method for preparing a hollow fiber membrane for a fuel cell humidifier, comprising the following steps:

[0044] (1) Preparing an intermediate layer spinning casting solution: sulfonated polysulfone with a sulfonation degree of 20% is vacuum dried at 80°C for 24 hours to remove moisture, and then the sulfonated polysulfone is dissolved in N,N-dimethylacetamide, and then polyvinylpyrrolidone K30 is added. The mixture is mechanically stirred at 60°C for 7 hours, and allowed to stand for degassing for 36 hours to obtain a uniform and transparent intermediate layer spinning casting solution for use; wherein the mass percentages of the raw materials are: 20% sulfonated polysulfone, 6% polyvinylpyrrolidone, and 74% N,N-dimethylacetamide;

[0045] (2) Preparation of inner layer spinning casting solution: Sulfonated polysulfone with a sulfonation degree of 15% was vacuum dried at 80°C for 24 hours to remove moisture, and then the sulfonated polysulfone was dissolved in N,N-dimethylacetamide, and then polyvinylpyrrolidone K30 was added. The mixture was mechanically stirred at 60°C for 6 hours, and allowed to stand for degassing for 36 hours to obtain a uniform and transparent inner layer spinning casting solution for standby use; wherein the mass percentages of the raw materials are: sulfonated polysulfone 15%, polyvinylpyrrolidone 3%, and N,N-dimethylacetamide 82%;

[0046] (3) Phase transformation spinning:

[0047] The middle layer spinning casting solution and the inner layer spinning casting solution are extruded together with the core solution from the spinneret of the three-layer coaxial spinning machine, and the core solution and the outer coagulation bath are both water; the flow rate of the middle layer spinning casting solution and the inner layer spinning casting solution is controlled to be 3 mL / min, the flow rate of the core solution is controlled to be 3 mL / min, the temperature of the core solution and the temperature of the outer coagulation bath are both 45°C, after a 30 cm dry spinning stage, the membrane is washed with water and dried to obtain a hollow fiber membrane for standby use;

[0048] (4) Hollow fiber surface treatment:

[0049] The obtained hollow fiber membrane was quickly immersed in a polysulfone solution with a mass concentration of 2% and a sulfonation degree of 55% (the solution temperature was 40°C), the immersion time was controlled to be 6 seconds, and then heat treated at 100°C for 2 minutes, and then further cleaned and dried to achieve single-sided hydrophilization treatment on the outer surface, thereby obtaining a hollow fiber membrane for a fuel cell humidifier.

[0050] Example 3:

[0051] Example 3 provides a method for preparing a hollow fiber membrane for a fuel cell humidifier, comprising the following steps:

[0052] (1) Preparing an intermediate layer spinning casting solution: vacuum drying sulfonated polyetheretherketone with a sulfonation degree of 15% at 80°C for 24 hours to remove moisture, then dissolving the sulfonated polyetheretherketone in N,N-dimethylformamide, then adding polyvinylpyrrolidone K30 and polyethylene glycol 1000, mechanically stirring at 50°C for 8 hours, and standing for degassing for 48 hours to obtain a uniform and transparent intermediate layer spinning casting solution for use; wherein the mass percentage of each raw material is: 24% sulfonated polyetheretherketone, 5% polyethylene glycol 1000, 3% polyvinylpyrrolidone K30, 68% N,N-dimethylformamide;

[0053] (2) Preparing an inner layer spinning casting solution: vacuum drying sulfonated polyetheretherketone with a sulfonation degree of 15% at 80°C for 24 hours to remove moisture, then dissolving the sulfonated polyetheretherketone in N,N-dimethylformamide, adding polyethylene glycol 1000, mechanically stirring at 50°C for 8 hours, and standing for degassing for 48 hours to obtain a uniform and transparent inner layer spinning casting solution for standby use; wherein the mass percentage of each raw material is: 15% sulfonated polyetheretherketone, 3% polyethylene glycol 1000, and 82% N,N-dimethylformamide;

[0054] (3) Phase transformation spinning:

[0055] The middle layer spinning casting solution and the inner layer spinning casting solution are extruded together with the core solution from the spinneret of the three-layer coaxial spinning machine, and the core solution and the outer coagulation bath are both water; the flow rate of the middle layer spinning casting solution and the inner layer spinning casting solution is controlled to be 3 mL / min, the flow rate of the core solution is controlled to be 3 mL / min, the temperature of the core solution and the temperature of the outer coagulation bath are both 45°C, after a 30 cm dry spinning stage, the membrane is washed with water and dried to obtain a hollow fiber membrane for standby use;

[0056] (4) Hollow fiber surface treatment:

[0057] The obtained hollow fiber membrane was quickly immersed in a 1% mass concentration of sulfonated polyetheretherketone solution with a sulfonation degree of 45% (the solution temperature was 40°C), the immersion time was controlled to be 6 seconds, and then heat treated at 100°C for 2 minutes, and then further cleaned and dried to achieve single-sided hydrophilization treatment on the outer surface, thereby obtaining a hollow fiber membrane for a fuel cell humidifier.

[0058] Example 4:

[0059] Example 4 provides a method for preparing a hollow fiber membrane for a fuel cell humidifier, comprising the following steps:

[0060] (1) Preparing an intermediate layer spinning casting solution: sulfonated polyetheretherketone with a sulfonation degree of 10% is vacuum dried at 80°C for 24 hours to remove moisture, and then the sulfonated polyetheretherketone is dissolved in dimethyl sulfoxide, and then lithium chloride and polyvinylpyrrolidone K30 are added. The mixture is mechanically stirred at 70°C for 6 hours, and allowed to stand for degassing for 24 hours to obtain a uniform and transparent intermediate layer spinning casting solution for use; wherein the mass percentages of the raw materials are: 15% sulfonated polyetheretherketone, 3% lithium chloride, 3% polyvinylpyrrolidone, and 79% dimethyl sulfoxide;

[0061] (2) Preparing an inner layer spinning casting solution: sulfonated polyetheretherketone with a sulfonation degree of 15% was vacuum dried at 80°C for 24 hours to remove moisture, and then the sulfonated polyetheretherketone was dissolved in dimethyl sulfoxide, and then lithium chloride and polyvinylpyrrolidone K30 were added. The mixture was mechanically stirred at 70°C for 6 hours, and allowed to stand for degassing for 24 hours to obtain a uniform and transparent inner layer spinning casting solution for standby use; wherein the mass percentage of each raw material is: 10% sulfonated polyetheretherketone, 0.5% lithium chloride, 0.5% polyvinylpyrrolidone, and 89% dimethyl sulfoxide;

[0062] (3) Phase transformation spinning:

[0063] The middle layer spinning casting solution, the inner layer spinning casting solution and the core liquid are extruded from the spinneret of a three-layer coaxial spinning machine together, and the core liquid and the outer coagulation bath are both water; the flow rate of the middle layer spinning casting solution and the inner layer spinning casting solution is controlled to be 5 mL / min, the flow rate of the core liquid is controlled to be 3 mL / min, the temperature of the core liquid and the temperature of the outer coagulation bath are both 40°C, after a 35 cm dry spinning stage, the membrane is washed with water and dried to obtain a hollow fiber membrane for standby use;

[0064] (4) Hollow fiber surface treatment:

[0065] The obtained hollow fiber membrane was quickly immersed in a 5% mass concentration perfluorosulfonic acid resin solution (solution temperature was 40°C), the immersion time was controlled to be 3 seconds, and then heat treated at 100°C for 2 minutes, and then further cleaned and dried to achieve single-side hydrophilization treatment of the outer surface, thereby obtaining a hollow fiber membrane for fuel cell humidifier.

[0066] Example 5:

[0067] Example 5 provides a method for preparing a hollow fiber membrane for a fuel cell humidifier, comprising the following steps:

[0068] (1) Preparing an intermediate layer spinning casting solution: sulfonated polysulfone with a sulfonation degree of 25% is vacuum dried at 80°C for 24 hours to remove moisture, and then the sulfonated polysulfone is dissolved in N,N-dimethylformamide, and then polyvinylpyrrolidone K30 is added. The mixture is mechanically stirred at 50°C for 8 hours, and allowed to stand for degassing for 48 hours to obtain a uniform and transparent intermediate layer spinning casting solution for use; wherein the mass percentages of the raw materials are: 18% sulfonated polysulfone, 6% polyvinylpyrrolidone, and 76% N,N-dimethylformamide;

[0069] (2) Preparation of inner layer spinning casting solution: vacuum drying polyvinylidene fluoride at 80°C for 24 hours to remove moisture, then dissolving polyvinylidene fluoride in a mixed solvent of N,N-dimethylformamide and N,N-dimethylacetamide, then adding polyvinylpyrrolidone K30, mechanically stirring at 50°C for 4 hours, and standing for degassing for 48 hours to obtain a uniform and transparent inner layer spinning casting solution for standby use; wherein the mass percentage of each raw material is: 17% polyvinylidene fluoride, 3% polyvinylpyrrolidone, 40% N,N-dimethylformamide, and 40% N,N-dimethylacetamide;

[0070] (3) Phase transformation spinning:

[0071] The middle layer spinning casting solution and the inner layer spinning casting solution are extruded together with the core solution from the spinneret of the three-layer coaxial spinning machine, and the core solution and the outer coagulation bath are both water; the flow rate of the middle layer spinning casting solution and the inner layer spinning casting solution is controlled to be 8 mL / min, the flow rate of the core solution is controlled to be 5 mL / min, the temperature of the core solution and the temperature of the outer coagulation bath are both 30°C, after a 20 cm dry spinning stage, the membrane is washed with water and dried to obtain a hollow fiber membrane for standby use;

[0072] (4) Hollow fiber surface treatment:

[0073] The obtained hollow fiber membrane was quickly immersed in a 3% mass concentration sulfonated polysulfone solution with a 45% sulfonation degree (solution temperature was 40°C), the immersion time was controlled to be 6 seconds, and then heat treated at 100°C for 2 minutes, and then further cleaned and dried to achieve single-side hydrophilization treatment of the outer surface, thereby obtaining a hollow fiber membrane for a fuel cell humidifier.

[0074] Example 6:

[0075] Example 6 provides a method for preparing a hollow fiber membrane for a fuel cell humidifier, comprising the following steps:

[0076] (1) Preparing an intermediate layer spinning casting solution: sulfonated polyphenylene sulfone with a sulfonation degree of 30% is vacuum dried at 80°C for 24 hours to remove moisture, and then the sulfonated polyphenylene sulfone is dissolved in a mixed solution of potassium nitrate and N-methylpyrrolidone, and then polyvinylpyrrolidone K30 is added. The mixture is mechanically stirred at 70°C for 6 hours, and allowed to stand for degassing for 24 hours to obtain a uniform and transparent intermediate layer spinning casting solution for use; wherein the mass percentages of the raw materials are: 28% sulfonated polyphenylene sulfone, 12% polyvinylpyrrolidone, 2% potassium nitrate, and 58% N-methylpyrrolidone;

[0077] (2) Preparing an inner layer spinning casting solution: sulfonated polyphenylsulfone with a sulfonation degree of 30% was vacuum dried at 80°C for 24 hours to remove moisture, and then the sulfonated polyphenylsulfone was dissolved in N-methylpyrrolidone, and then polyvinylpyrrolidone K30 was added. The mixture was mechanically stirred at 70°C for 6 hours, and allowed to stand for degassing for 24 hours to obtain a uniform and transparent inner layer spinning casting solution for standby use; wherein the mass percentages of the raw materials are: 10% sulfonated polyphenylsulfone, 1% polyvinylpyrrolidone, and 89% N-methylpyrrolidone;

[0078] (3) Phase transformation spinning:

[0079] The middle layer spinning casting solution, the inner layer spinning casting solution and the core liquid are extruded from the spinneret of a three-layer coaxial spinning machine together, and the core liquid and the outer coagulation bath are both water; the flow rate of the middle layer spinning casting solution and the inner layer spinning casting solution is controlled to be 10 mL / min, the flow rate of the core liquid is controlled to be 8 mL / min, the temperature of the core liquid and the temperature of the outer coagulation bath are both 40° C. After a 50 cm dry spinning stage, the hollow fiber membrane is washed with water and dried to obtain a standby hollow fiber membrane;

[0080] (4) Hollow fiber surface treatment:

[0081] The obtained hollow fiber membrane is quickly immersed in a 5% mass concentration sulfonated polyetheretherketone solution with a sulfonation degree of 60% (the solution temperature is 40°C), the immersion time is controlled to be 6 seconds, and then heat treated at 100°C for 2 minutes, and then further cleaned and dried to achieve single-sided hydrophilization treatment of the outer surface, thereby obtaining a hollow fiber membrane for a fuel cell humidifier.

[0082] The hollow fiber membranes prepared in Examples 1-6 are cut as required, and the hollow fiber membranes are made into a humidification membrane assembly with internal and external air flow channels, and the two ends of the hollow fiber membrane package are bonded and fixed to the humidifier membrane shell. In the membrane assembly of the present application, the dry air purged from the tube can carry away the water molecules that permeate and diffuse from the outside of the tube to the inside of the tube of the membrane assembly for humidification. During this test, the parameters of the wet air and the purge air (such as temperature, humidity and flow rate) can be controlled. The gas flow rate of the present application is 500SLPM, the inlet temperature of the purged dry air is 65°C, the humidity is 0%RH, and the flow rate is 10.8g / s; the inlet temperature of the wet air is 65°C, the humidity is 100%RH, and the flow rate is 10.8g / s.

[0083] The performance test data is shown in Table 1.

[0084] Table 1: Performance data of hollow fiber membranes prepared in Examples 1-6 of the present application

[0085]

[0086] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0087] It should be noted that, in the present application, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment comprising the elements. In the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly specified.

[0088] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for preparing a hollow fiber membrane for a fuel cell humidifier, characterized in that: The following steps are involved: Preparing an intermediate layer spinning casting solution: mixing a first polymer, a first porogen and a first solvent, stirring at 50 to 80° C. for 4 to 8 hours, and standing for 5 to 48 hours for degassing to obtain an intermediate layer spinning casting solution; Preparing an inner layer spinning casting solution: mixing a second polymer, a second porogen, and a second solvent, stirring at 50-80° C. for 4-8 hours, and standing for 5-48 hours for degassing to obtain an inner layer spinning casting solution; Phase inversion spinning: hollow fiber membranes are prepared using a three-layer coaxial spinning machine using the middle layer spinning solution and the inner layer spinning solution; Surface treatment: The hollow fiber membrane is immersed in the coating liquid, and then heat-treated, cleaned, and dried to achieve unilateral hydrophilic treatment of the outer surface, thereby obtaining a hollow fiber membrane for a fuel cell humidifier.

2. The method for preparing a hollow fiber membrane for a fuel cell humidifier according to claim 1, characterized in that: The mass percentages of the raw materials for preparing the intermediate layer spinning solution are: 15% to 30% of the first polymer, 0.1% to 15% of the first porogen, and 58% to 84% of the first solvent.

3. The method for preparing a hollow fiber membrane for a fuel cell humidifier according to claim 1, wherein: The first polymer is selected from a mixture of any one or more of sulfonated polyetheretherketone, sulfonated polysulfone, and sulfonated polyphenylsulfone with a sulfonation degree of 5% to 30%; the first porogen is selected from a mixture of any one or more of polyethylene glycol, polyvinylpyrrolidone, lithium chloride, and potassium nitrate; and the first solvent is selected from a mixture of any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

4. The method for preparing a hollow fiber membrane for a fuel cell humidifier according to claim 1, wherein: The mass percentages of the raw materials for preparing the inner layer spinning casting solution are: 5% to 30% of the second polymer, 1% to 10% of the second porogen and 66% to 94% of the second solvent.

5. The method for preparing a hollow fiber membrane for a fuel cell humidifier according to claim 1, characterized in that: The second polymer is selected from a mixture of any one or more of polyetheretherketone, polysulfone, polyphenylsulfone, and polyvinylidene fluoride; the second porogen is selected from a mixture of any one or more of polyethylene glycol, polyvinylpyrrolidone, lithium chloride, and potassium nitrate; and the second solvent is selected from a mixture of any one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

6. The method for preparing a hollow fiber membrane for a fuel cell humidifier according to claim 1, characterized in that: The mass concentration of the coating liquid is 0.5% to 6%.

7. The method for preparing a hollow fiber membrane for a fuel cell humidifier according to claim 1, characterized in that: The coating liquid is selected from a mixture of any one or more of perfluorosulfonic acid resin, sulfonated polyetheretherketone with a sulfonation degree of 40% to 60%, sulfonated polysulfone or sulfonated polyphenylsulfone.

8. The method for preparing a hollow fiber membrane for a fuel cell humidifier according to claim 1, characterized in that: The phase inversion spinning process is as follows: the middle layer spinning casting liquid, the inner layer spinning casting liquid and the core liquid are extruded from the spinneret of the three-layer coaxial spinning machine together, and the core liquid and the external coagulation bath are both water; the liquid flow rate of the middle layer spinning casting liquid and the inner layer spinning casting liquid is controlled to be 1-10mL / min, the core liquid flow rate is 1-10mL / min, the temperature of the core liquid and the temperature of the external coagulation bath are 25-80℃, after a dry spinning stage of 3-50cm, it is washed with water and dried to obtain a hollow fiber membrane.

9. A hollow fiber membrane for a fuel cell humidifier, characterized in that: The hollow fiber membrane is prepared by the preparation method according to any one of claims 1 to 8, wherein the hollow fiber membrane comprises an outer hydrophilic layer, an intermediate layer and an inner hydrophobic layer, and the thickness of the outer hydrophilic layer and the inner hydrophobic layer are both less than the thickness of the intermediate layer.

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