Composite proton exchange membrane and preparation method and application thereof

Abstract

The application provides a composite proton exchange membrane and a preparation method and application thereof. The composite proton exchange membrane comprises an expanded polytetrafluoroethylene fiber membrane and perfluorosulfonic acid resin particles distributed among the pores of the expanded polytetrafluoroethylene fiber membrane. The perfluorosulfonic acid resin particles are directly compounded with polytetrafluoroethylene to form a composite reinforced structure, and the perfluorosulfonic acid resin particles are uniformly dispersed inside the pores of the expanded polytetrafluoroethylene fiber membrane, which can effectively improve the filling performance of ePTFE and perfluorosulfonic acid resin particles, thereby improving the anti-swelling performance of the composite proton exchange membrane, reducing the dissolution of perfluorosulfonic acid resin, and also effectively reducing the amount of perfluorosulfonic acid resin and improving the service life and durability of the composite proton exchange membrane.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane technology, and more specifically, to a composite proton exchange membrane, its preparation method, and its application. Background Technology

[0002] With the development of new energy technologies, hydrogen-oxygen fuel cells and PEM (proton exchange membrane) water electrolysis for hydrogen production are considered important methods for solving environmental pollution and energy problems. Proton exchange membranes are crucial components in both fuel cell and PEM water electrolysis hydrogen production technologies. Fuel cells place high demands on proton exchange membranes, which perform functions such as conducting protons and blocking reactant gases. Requirements include high proton conductivity, low reactant gas permeability, sufficient mechanical strength, and good chemical and electrochemical stability, making them a research hotspot in hydrogen energy technology and membrane fabrication technology.

[0003] Currently, there are two main types of proton exchange membranes on the market. One type is a homogeneous membrane made of perfluorosulfonic acid resin using melt extrusion casting, represented by the Nafion membrane from Chemours Corporation in the United States. The other type is a proton exchange membrane reinforced with porous polytetrafluoroethylene membrane using solution casting coating, represented by Gore Corporation in the United States. Although DuPont's traditional Nafion membrane exhibits excellent electrochemical and mechanical properties at low temperatures, it requires a large amount of perfluorosulfonic acid resin, has a relatively thick film, and is expensive. Furthermore, it exhibits performance degradation under high-temperature conditions.

[0004] With the development of hydrogen energy technology and the improvement of perfluorosulfonic acid resin quality and membrane fabrication processes, proton exchange membranes are also constantly being optimized and developed. Since Penner RM and Matrin CR first immersed Nafion solution into expanded polytetrafluoroethylene (ePTFE) microporous membrane materials to prepare composite proton exchange membranes, the application of ePTFE microporous membranes has greatly improved the performance of composite proton exchange membranes. ePTFE microporous membranes themselves possess excellent mechanical properties, and their hydrophobicity effectively maintains the size of the proton exchange membrane, significantly reducing swelling deformation, thickness, and resistance, thereby greatly improving the durability and practicality of fuel cell proton exchange membranes. However, due to the poor wetting properties of the ePTFE microporous membrane, it is not conducive to the wetting of the perfluorosulfonic acid resin solution, resulting in a small amount of perfluorosulfonic acid resin entering between the ePTFE micropores. As a result, it is difficult to improve the conductivity of the proton exchange membrane. At the same time, the perfluorosulfonic acid resin entering the ePTFE has a small molecular weight, and the perfluorosulfonic acid resin is more likely to dissolve during the use of the composite membrane, resulting in poor durability and short life of the composite proton exchange membrane. Summary of the Invention

[0005] The main objective of this invention is to provide a composite proton exchange membrane, its preparation method, and its application, in order to solve the problems of poor wettability of perfluorosulfonic acid resin solution and ePTFE microporous membrane in the prior art, resulting in poor swelling resistance, poor durability, and short lifespan of the prepared composite proton exchange membrane.

[0006] To achieve the above objectives, according to one aspect of the present invention, a composite proton exchange membrane is provided, comprising an expanded polytetrafluoroethylene fiber membrane and perfluorosulfonic acid resin particles distributed in the pores of the expanded polytetrafluoroethylene fiber membrane.

[0007] Furthermore, the thickness of the composite proton exchange membrane is 5–150 μm, preferably the average particle size of the perfluorosulfonic acid resin particles is 100–200 μm, and preferably the fiber diameter of the expanded polytetrafluoroethylene fiber membrane is 50–500 nm.

[0008] Furthermore, the perfluorosulfonic acid resin particles account for 1% to 25% of the mass of the composite proton exchange membrane.

[0009] To achieve the above objectives, according to one aspect of the present invention, a method for preparing the above-mentioned composite proton exchange membrane is provided, the method comprising: step S1, mixing polytetrafluoroethylene resin powder and perfluorosulfonate resin particles to obtain a mixture; step S2, aging the mixture to obtain an aged mixture; step S3, mixing the aged mixture with a lubricant to obtain a mixture with added lubricant; step S4, extruding the mixture with added lubricant to obtain a raw material blank; calendering the raw material blank into a film to obtain a calendered film; step S5, heating and drying the calendered film to obtain a dried calendered film; biaxially stretching the dried calendered film to obtain a composite membrane; step S6, flexibly rolling the composite membrane to obtain a pressed film; sintering and shaping the pressed film to obtain a shaped composite membrane; step S7, acidifying the shaped composite membrane to obtain an acidified composite membrane; and drying the acidified composite membrane to obtain a composite proton exchange membrane.

[0010] Furthermore, the preparation method also includes the step of preparing perfluorosulfonate resin particles: mixing sulfonyl fluoride resin with an aqueous solution of potassium hydroxide and / or sodium hydroxide and heating to react, thereby obtaining perfluorosulfonate resin particles; preferably, the heating temperature is 70-90°C, preferably the heating time is 1-3 hours, and preferably the perfluorosulfonate resin particles are sodium perfluorosulfonate particles and / or potassium perfluorosulfonate resin particles.

[0011] Furthermore, the average particle size of the polytetrafluoroethylene resin powder is 300-500 μm, and preferably the crystallinity of the polytetrafluoroethylene resin powder is not less than 98%.

[0012] Further, by weight, the polytetrafluoroethylene resin powder is 100 parts, the perfluorosulfonate resin particles are 1 to 25 parts, and the lubricant is 15 to 30 parts; preferably, the lubricant is one or more of petroleum ether, white oil, silicone oil, alcohol, and aromatic hydrocarbons.

[0013] Further, in step S2, the curing temperature is 25-40°C, and the curing time is preferably not less than 24 hours, and more preferably 24-48 hours; preferably, in step S4, the extrusion molding pressure is 3-10 MPa; preferably, the calendering film temperature is 50-80°C; preferably, the thickness of the calendered film is 1-2 mm.

[0014] Further, in step S5, the heating and drying temperature is 200-300°C, and the heating and drying time is preferably 10-30 minutes; preferably, the biaxial stretching includes longitudinal stretching and transverse stretching; more preferably, the longitudinal stretching includes: stretching the dried calendered film by 400%-1000% at a temperature of 250-350°C; the transverse stretching includes: stretching the dried calendered film by 500%-2500% at a temperature of 200-250°C.

[0015] Furthermore, in step S6, the sintering temperature is 300–350°C, and the sintering time is preferably 2–5 minutes.

[0016] Further, in step S7, the drying temperature is 50-80°C, and the drying time is 5-20 min. Preferably, the acidification treatment includes: immersing the shaped composite membrane in a 1-2 mol / L sulfuric acid solution at 50-80°C for 20-48 h to obtain the acidified composite membrane. Preferably, the acidification treatment also includes cleaning the acidified composite membrane at least once. More preferably, the cleaning solvent is water. More preferably, the cleaning time is 10-20 min.

[0017] According to another aspect of the present invention, an application of the above-described composite proton exchange membrane is provided, the application comprising: applying the composite proton exchange membrane to fuel cells and PEM water electrolysis for hydrogen production.

[0018] By applying the technical solution of this invention, perfluorosulfonic acid resin particles are directly composited with polytetrafluoroethylene to form a composite reinforced structure. The perfluorosulfonic acid resin particles are uniformly dispersed inside the pores of the expanded polytetrafluoroethylene fiber membrane, which can effectively improve the filling performance of ePTFE and perfluorosulfonic acid resin particles, thereby improving the anti-swelling performance of the composite proton exchange membrane, reducing the leaching of perfluorosulfonic acid resin, and also effectively reducing the amount of perfluorosulfonic acid resin used and improving the lifespan and durability of the composite proton exchange membrane. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1 A schematic diagram of the composite proton exchange membrane of the present invention is shown;

[0021] Figure 2 A schematic diagram of the three-layer composite proton exchange membrane of Comparative Example 1 of the present invention is shown;

[0022] The above figures include the following reference numerals:

[0023] a. PTFE particles; b. Raw material sodium perfluorosulfonate particles; c. PTFE joint; d. PTFE fiber; e. Sodium perfluorosulfonate particles after reaction;

[0024] 1. First perfluorosulfonic acid resin layer; 2. Perfluorosulfonic acid resin impregnated ePTFE composite layer; 3. Second perfluorosulfonic acid resin layer. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] As analyzed in the background section, most current research in the field of ePTFE composite proton exchange membrane preparation involves modifying ePTFE or adjusting perfluorosulfonic acid resin solutions to alter the sulfonic acid resin filling degree of the composite proton exchange membrane. However, due to the poor wetting properties of the ePTFE microporous membrane, the perfluorosulfonic acid resin solution is not easily impregnated, resulting in a low amount of perfluorosulfonic acid resin entering the ePTFE micropores. Furthermore, the concentration and viscosity limitations of the perfluorosulfonic acid resin solution restrict the filling capacity of the composite proton exchange membrane, making it difficult to improve the conductivity of the proton exchange membrane. Simultaneously, the perfluorosulfonic acid resin entering the ePTFE has a relatively small molecular weight, making it easier for the perfluorosulfonic acid resin to dissolve during use, leading to poor durability, short lifespan, and poor anti-swelling properties of the composite proton exchange membrane. To address these issues, this application provides a composite proton exchange membrane, its preparation method, and its applications.

[0027] In a typical implementation, this application provides a composite proton exchange membrane, such as... Figure 1 As shown, the composite proton exchange membrane includes an expanded polytetrafluoroethylene fiber membrane and perfluorosulfonic acid resin particles distributed in the pores of the expanded polytetrafluoroethylene fiber membrane.

[0028] This application directly combines perfluorosulfonic acid resin particles with polytetrafluoroethylene (PTFE) to form a composite reinforced structure. The perfluorosulfonic acid resin particles are uniformly dispersed inside the pores of the expanded PTFE fiber membrane, which can effectively improve the filling performance of ePTFE and perfluorosulfonic acid resin particles, thereby enhancing the anti-swelling performance of the composite proton exchange membrane, reducing the leaching of perfluorosulfonic acid resin, and effectively reducing the amount of perfluorosulfonic acid resin used while improving the lifespan and durability of the composite proton exchange membrane.

[0029] Depending on the application scenario, the composite proton exchange membrane can be designed with different thicknesses. In some embodiments, the thickness of the composite proton exchange membrane is 5–150 μm. For example, when the composite proton exchange membrane is applied to a fuel cell, a thickness of 5–20 μm is preferred to reduce resistance. To ensure that the perfluorosulfonic acid resin particles are uniformly dispersed in the pores of the ePTFE fiber membrane, the average particle size of the perfluorosulfonic acid resin particles is preferably 100–200 μm, and the fiber diameter of the expanded polytetrafluoroethylene fiber is preferably 50–500 nm.

[0030] In some embodiments, the perfluorosulfonic acid resin particles account for 1-25% of the mass of the composite proton exchange membrane. Compared with the use of perfluorosulfonic acid resin solution in the prior art, the composite proton exchange membrane of this application can save on the amount of perfluorosulfonic acid resin used.

[0031] In another typical embodiment of this application, a method for preparing the above-mentioned composite proton exchange membrane is provided. The method includes: step S1, mixing polytetrafluoroethylene resin powder and perfluorosulfonate resin particles to obtain a mixture; step S2, aging the mixture to obtain an aged mixture; step S3, mixing the aged mixture with a lubricant to obtain a mixture with added lubricant; step S4, extruding the mixture with added lubricant to obtain a raw material blank; calendering the raw material blank into a film to obtain a calendered film; step S5, heating and drying the calendered film to obtain a dried calendered film; biaxially stretching the dried calendered film to obtain a composite membrane; step S6, flexibly rolling the composite membrane to obtain a pressed film; sintering and shaping the pressed film to obtain a shaped composite membrane; step S7, acidifying the shaped composite membrane to obtain an acidified composite membrane; and drying the acidified composite membrane to obtain a composite proton exchange membrane.

[0032] This application directly composites perfluorosulfonate resin particles with polytetrafluoroethylene, such as Figure 1As shown, perfluorosulfonate resin particles b are dispersed in PTFE particles a. Through extrusion, hot pressing, and biaxial stretching, the PTFE is drawn into PTFE nodes c and PTFE fibers d, along with reacted sodium perfluorosulfonate particles e. Then, rolling, high-temperature setting, and acidification are performed to directly prepare a composite proton exchange membrane. In this preparation process, the perfluorosulfonate resin particles do not require dissolution, which improves the swelling resistance and dissolution performance of the composite proton exchange membrane, effectively solving the problem of poor wettability between the perfluorosulfonate resin solution and the ePTFE microporous membrane. The composite proton exchange membrane prepared in this application exhibits good swelling resistance, long lifespan, and good durability.

[0033] This application does not impose any particular limitation on the preparation method of perfluorosulfonate resin particles. Perfluorosulfonate resin particles can be prepared simply by mixing sulfonyl fluoride resin with a corresponding hydroxide. In some embodiments, this application utilizes the reaction of sulfonyl fluoride resin with an alkali metal to prepare perfluorosulfonate resin particles. This preparation method further includes the step of preparing perfluorosulfonate resin particles: mixing sulfonyl fluoride resin with an aqueous solution of potassium hydroxide and / or sodium hydroxide and heating the mixture to obtain perfluorosulfonate resin particles; preferably, the heating temperature is 70–90°C, and preferably the heating time is 1–3 hours. The reaction of sulfonyl fluoride resin in an aqueous solution of potassium hydroxide and / or sodium hydroxide is as follows: R-SO2F + 2NaOH → R-SO3Na + NaF + H2O; R-SO2F + 2KOH → R-SO3Na + KF + H2O. Wherein, the general formula of R is... The perfluorosulfonic acid resin particles are then obtained by heating and stirring, filtering and separating, drying and grinding. The sulfonyl fluoride resin used in this application is a commonly used sulfonyl fluoride resin in the prior art, which will not be described in detail here.

[0034] In some embodiments, in step S1, the polytetrafluoroethylene resin powder and perfluorosulfonate resin particles can be mixed in a mixer for 12 to 20 hours to ensure that the polytetrafluoroethylene resin powder and perfluorosulfonate resin particles are fully and evenly mixed.

[0035] To ensure that the mechanical strength of the polytetrafluoroethylene resin can achieve the tensile effect, in some embodiments, the average particle size of the polytetrafluoroethylene resin powder is 300-500 μm, and preferably the crystallinity of the polytetrafluoroethylene resin powder is not less than 98%.

[0036] In some embodiments, the mass of polytetrafluoroethylene resin powder is 100 parts, the mass of perfluorosulfonic acid resin particles is 1-25 parts, and the mass of lubricant is 15-30 parts. This application allows direct adjustment of the perfluorosulfonic acid resin particle loading in the composite proton exchange membrane by adjusting the amount of perfluorosulfonic acid resin particles. To further improve the anti-swelling performance of the composite proton exchange membrane and the dissolution performance of the perfluorosulfonic acid resin particles, it is preferable that the perfluorosulfonic acid resin particles are within the above-mentioned range. Excessive use of perfluorosulfonic acid resin will reduce the number of PTFE nodes, thereby decreasing the strength of the proton exchange membrane.

[0037] This application does not impose any particular restrictions on the amount or type of lubricant used; any lubricant commonly used in the art can be applied to this application. Preferably, the lubricant is one or more of petroleum ether, white oil, silicone oil, alcohols, and aromatic hydrocarbons.

[0038] To further improve the compatibility of polytetrafluoroethylene resin powder and perfluorosulfonate resin particles, in some embodiments, the curing temperature in step S2 is 25-40°C, the curing time is preferably not less than 24 hours, and the curing time is more preferably 24-48 hours.

[0039] In order to make the composite proton exchange membrane more uniform, in some embodiments, in step S4, the extrusion pressure is 3 to 10 MPa; the calendering temperature is preferably 50 to 80°C; and the thickness of the calendered film is preferably 1 to 2 mm.

[0040] In some embodiments, in step S5, the heating and drying temperature is 200–300°C, and the heating and drying time is preferably 10–30 minutes, thereby removing the lubricant from the calendered film. The lubricant can be recycled.

[0041] To ensure the composite proton exchange membrane possesses sufficient mechanical strength, this application subjectes the dried calendered film to biaxial stretching. In some embodiments, biaxial stretching includes longitudinal stretching and transverse stretching. Preferably, longitudinal stretching includes: stretching the dried calendered film by 400% to 1000% at a temperature of 250–350°C; transverse stretching includes: stretching the dried calendered film by 500% to 2500% at a temperature of 200–250°C.

[0042] This application does not impose any particular restrictions on the sintering and shaping conditions; conditions commonly used in the art can be applied to this application. In order to ensure uniform pore size and a certain shaping strength of the proton exchange membrane, in some embodiments, the sintering and shaping temperature in step S6 is 300-350°C, and the preferred sintering and shaping time is 2-5 minutes.

[0043] In some embodiments, in step S7, the drying temperature is 50–80°C, and the drying time is 5–20 min. Commonly used drying conditions in the art can be applied to this application. This application converts the above-mentioned perfluorosulfonate resin into perfluorosulfonic acid resin through acidification treatment. Preferably, the acidification treatment includes: immersing the shaped composite film in a 1–2 mol / L sulfuric acid solution at 50–80°C for 20–48 h to obtain the acidified composite film; preferably, the acidification treatment further includes cleaning the acidified composite film at least once; more preferably, the cleaning solvent is water; and even more preferably, the cleaning time is 10–20 min.

[0044] In another typical embodiment of this application, an application of the above-mentioned composite proton exchange membrane is provided, the application including: applying the composite proton exchange membrane to fuel cells and PEM water electrolysis for hydrogen production.

[0045] The composite proton exchange membrane of this application has a high proton conduction capacity, low reactive gas permeability, certain mechanical strength, and good chemical and electrochemical stability, and therefore can be applied to fuel cells and PEM water electrolysis hydrogen production technology.

[0046] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0047] Unless otherwise specified, all compounds used in the embodiments of this application (such as sulfonyl fluoride resin and polytetrafluoroethylene resin) are commercially available.

[0048] Example 1

[0049] A: Preparation of sodium perfluorosulfonate particles: 500g of sulfonyl fluoride resin was added to 3L of 1mol / L sodium hydroxide solution, stirred at 80℃ for 2h, filtered and separated, soaked in 3L of deionized water for 30min, washed three times, dried at 80℃ for 12h, and ground and sieved to obtain sodium perfluorosulfonate with an average particle size of 100μm~200μm.

[0050] B: Select polytetrafluoroethylene resin powder with a particle size of approximately 300μm to 500μm. The crystallinity of the polytetrafluoroethylene resin should be no less than 98% to ensure the strength and tensile properties of the raw material.

[0051] C: With 100 parts by weight of polytetrafluoroethylene resin and 20 parts by weight of sodium perfluorosulfonate resin particles, the polytetrafluoroethylene and sodium perfluorosulfonate resin were placed in a mixer and mixed for 12 hours to obtain a mixture.

[0052] D: Maturation treatment: The above mixture is left to stand at 35°C for 24 hours to mature, and the matured mixture is obtained.

[0053] E: Add 25 parts by weight of lubricant to the matured mixture, mix thoroughly and set aside (the lubricant is mainly a mixture of petroleum ether, white oil, and silicone oil organic solvents) to obtain the lubricant-added mixture.

[0054] F: The mixture with added lubricant is extruded into a raw material blank under a pressure of 7MPa to obtain the raw material blank.

[0055] G: The raw material blank is rolled into a film at a temperature of 60°C to obtain a calendered film with a thickness of about 1 mm.

[0056] H: Drying treatment: Heat and dry the calendered film at 250℃ for 20 minutes to remove the lubricant from the calendered film, and obtain the dried calendered film. The lubricant can be recycled.

[0057] I: Longitudinal stretching: The dried calendered film is stretched longitudinally by 600% at a temperature of 250℃ to obtain a longitudinally stretched calendered film.

[0058] J: Transverse stretching: The longitudinally stretched calendered film is subjected to a 1900% transverse stretch at 220°C to obtain a composite film. K: Roll pressing: The composite film that has undergone longitudinal and transverse stretching is subjected to flexible roll pressing to obtain a pressed film.

[0059] L: The above-mentioned press-fit film is sintered and shaped at a high temperature of 340℃ for 3 minutes to obtain a shaped composite film.

[0060] M: Soak the shaped composite membrane in a 1 mol / L sulfuric acid solution at 80℃ for 24 hours, soak it in deionized water for 10 minutes, wash it three times, and dry it at 80℃ for 10 minutes.

[0061] Example 2

[0062] A: Preparation of sodium perfluorosulfonate particles: 500g of sulfonyl fluoride resin was added to 3L of 1mol / L sodium hydroxide solution, stirred at 80℃ for 2h, filtered and separated, soaked in 3L of deionized water for 30min, washed three times, dried at 80℃ for 12h, and ground and sieved to obtain sodium perfluorosulfonate with an average particle size of 100-200μm.

[0063] B: Select polytetrafluoroethylene resin powder with a particle size of approximately 300μm to 500μm. The crystallinity of the polytetrafluoroethylene resin should be no less than 98% to ensure the strength and tensile properties of the raw material.

[0064] C: With 100 parts by weight of polytetrafluoroethylene resin and 15 parts by weight of sodium perfluorosulfonate resin particles, the polytetrafluoroethylene and sodium perfluorosulfonate resin were placed in a mixer and mixed for 12 hours to obtain a mixture.

[0065] D: Maturation treatment: The above mixture is left to stand at 35°C for 24 hours to mature, and the matured mixture is obtained.

[0066] E: Add 20 parts by weight of lubricant to the matured mixture, mix thoroughly and set aside (the lubricant is mainly a mixture of petroleum ether, white oil, and silicone oil organic solvents) to obtain the lubricant-added mixture.

[0067] F: The mixture with added lubricant is extruded into a raw material blank under a pressure of 5MPa to obtain the raw material blank.

[0068] G: The raw material blank is rolled into a film at 80°C to obtain a calendered film with a thickness of about 1 mm.

[0069] H: Drying treatment: Heat the calendered film at 220℃ for 10 minutes to remove the lubricant from the calendered film, and obtain the dried calendered film. The lubricant can be recycled.

[0070] I: Longitudinal stretching: The dried calendered film is stretched longitudinally by 800% at a temperature of 280℃ to obtain a longitudinally stretched calendered film.

[0071] J: Transverse stretching: Under a temperature of 230℃, the longitudinally stretched calendered film is subjected to 900% transverse stretching to obtain a composite film.

[0072] K: Roll pressing: The above composite film, which has been stretched longitudinally and laterally, is flexibly rolled to obtain a pressed film.

[0073] L: The above-mentioned press-fit film is sintered and shaped at a high temperature of 350℃ for 3 minutes to obtain a shaped composite film.

[0074] M: Soak the shaped composite membrane in a 1 mol / L sulfuric acid solution at 80℃ for 24 hours, soak it in deionized water for 10 minutes, wash it three times, and dry it at 80℃ for 20 minutes.

[0075] Example 3

[0076] A: Preparation of potassium perfluorosulfonate particles: 500g of sulfonyl fluoride resin was added to 3L of 1mol / L potassium hydroxide solution, stirred at 80℃ for 2h, filtered and separated, soaked in 3L of deionized water for 30min, washed three times, dried at 80℃ for 12h, and ground and sieved to obtain potassium perfluorosulfonate with an average particle size of 100-200μm.

[0077] B: Select polytetrafluoroethylene resin powder with a particle size of approximately 300μm-500μm. The crystallinity of the polytetrafluoroethylene resin should be no less than 98% to ensure the strength and tensile properties of the raw material.

[0078] C: With 100 parts by weight of polytetrafluoroethylene resin and 10 parts by weight of potassium perfluorosulfonate resin particles, the polytetrafluoroethylene and potassium perfluorosulfonate resin were placed in a mixer and mixed for 12 hours to obtain a mixture.

[0079] D: Maturation treatment: The above mixture is left to stand at 25°C for 24 hours to mature, and the matured mixture is obtained.

[0080] E: Add 15 parts by weight of lubricant to the matured mixture, mix thoroughly and set aside (the lubricant is mainly a mixture of petroleum ether, white oil, and silicone oil organic solvents) to obtain the mixture with added lubricant.

[0081] F: The mixture with added lubricant is extruded into a raw material blank under a pressure of 4MPa to obtain the raw material blank.

[0082] G: The raw material blank is rolled into a film at a temperature of 50°C to obtain a calendered film with a thickness of about 2mm.

[0083] H: Drying treatment: Heat and dry the calendered film at 260℃ for 20 minutes to remove the lubricant from the calendered film, and obtain the dried calendered film. The lubricant can be recycled.

[0084] I: Longitudinal stretching: The dried calendered film is stretched longitudinally by 400% at a temperature of 270℃ to obtain a longitudinally stretched calendered film.

[0085] J: Transverse stretching: Under a temperature of 220℃, the longitudinally stretched calendered film is subjected to a 500% transverse stretch to obtain a composite film.

[0086] K: Roll pressing: The above composite film, which has been stretched longitudinally and laterally, is flexibly rolled to obtain a pressed film.

[0087] L: The above-mentioned press-fit film is sintered and shaped at a high temperature of 350℃ for 5 minutes to obtain a shaped composite film.

[0088] M: The shaped composite membrane was soaked in 1 mol / L sulfuric acid solution at 80℃ for 24 hours, then soaked in deionized water for 10 minutes, washed three times, and dried at 80℃ for 5 minutes.

[0089] Example 4

[0090] Unlike Example 1, in step C, the mass of sodium perfluorosulfonate resin particles is 1 part.

[0091] Example 5

[0092] Unlike Example 1, in step C, the mass of sodium perfluorosulfonate resin particles is 25 parts.

[0093] Example 6

[0094] Unlike Example 1, in step C, the mass of sodium perfluorosulfonate resin particles is 33 parts.

[0095] Example 7

[0096] A: Preparation of sodium perfluorosulfonate particles: 500g of sulfonyl fluoride resin was added to 3L of 1mol / L sodium hydroxide solution, stirred at 70℃ for 2h, filtered and separated, soaked in 3L of deionized water for 30min, washed three times, dried at 80℃ for 12h, and ground and sieved to obtain sodium perfluorosulfonate with an average particle size of 100μm~200μm.

[0097] B: Select polytetrafluoroethylene resin powder with a particle size of approximately 300μm to 500μm. The crystallinity of the polytetrafluoroethylene resin should be no less than 98% to ensure the strength and tensile properties of the raw material.

[0098] C: With 100 parts by weight of polytetrafluoroethylene resin and 20 parts by weight of sodium perfluorosulfonate resin particles, the polytetrafluoroethylene and sodium perfluorosulfonate resin were placed in a mixer and mixed for 12 hours to obtain a mixture.

[0099] D: Maturation treatment: The above mixture is left to stand at 25°C for 48 hours to mature, and the matured mixture is obtained.

[0100] E: Add 30 parts by weight of lubricant to the matured mixture, mix thoroughly and set aside (the lubricant is mainly a mixture of petroleum ether, white oil, and silicone oil organic solvents) to obtain the mixture with added lubricant.

[0101] F: The mixture with added lubricant is extruded into a raw material blank under a pressure of 3MPa to obtain the raw material blank.

[0102] G: The raw material blank is rolled into a film at a temperature of 50°C to obtain a calendered film with a thickness of about 2mm.

[0103] H: Drying treatment: Heat the calendered film at 200℃ for 10 minutes to remove the lubricant from the calendered film, and obtain the dried calendered film. The lubricant can be recycled.

[0104] I: Longitudinal stretching: The dried calendered film is stretched longitudinally by 400% at a temperature of 250℃ to obtain a longitudinally stretched calendered film.

[0105] J: Transverse stretching: Under a temperature of 200℃, the longitudinally stretched calendered film is subjected to a 500% transverse stretch to obtain a composite film.

[0106] K: Roll pressing: The above composite film, which has been stretched longitudinally and laterally, is flexibly rolled to obtain a pressed film.

[0107] L: The above-mentioned press-fit film is sintered and shaped under a high temperature of 300℃ for 2 minutes to obtain a shaped composite film.

[0108] M: Soak the shaped composite membrane in a 2 mol / L sulfuric acid solution at 50℃ for 24 hours, soak it in deionized water for 10 minutes, wash it three times, and dry it at 80℃ for 20 minutes.

[0109] Example 8

[0110] A: Preparation of sodium perfluorosulfonate particles: 500g of sulfonyl fluoride resin was added to 3L of 1mol / L sodium hydroxide solution, stirred at 90℃ for 2h, filtered and separated, soaked in 3L of deionized water for 30min, washed three times, dried at 80℃ for 12h, and ground and sieved to obtain sodium perfluorosulfonate with an average particle size of 100μm~200μm.

[0111] B: Select polytetrafluoroethylene resin powder with a particle size of approximately 300μm to 500μm. The crystallinity of the polytetrafluoroethylene resin should be no less than 98% to ensure the strength and tensile properties of the raw material.

[0112] C: With 100 parts by weight of polytetrafluoroethylene resin and 20 parts by weight of sodium perfluorosulfonate resin particles, the polytetrafluoroethylene and sodium perfluorosulfonate resin were placed in a mixer and mixed for 12 hours to obtain a mixture.

[0113] D: Maturation treatment: The above mixture is left to stand at 40°C for 24 hours to mature, and the matured mixture is obtained.

[0114] E: Add 15 parts by weight of lubricant to the matured mixture, mix thoroughly and set aside (the lubricant is mainly a mixture of petroleum ether, white oil, and silicone oil organic solvents) to obtain the mixture with added lubricant.

[0115] F: The mixture with added lubricant is extruded into a raw material blank under a pressure of 10 MPa to obtain the raw material blank.

[0116] G: The raw material blank is rolled into a film at 80°C to obtain a calendered film with a thickness of about 1 mm.

[0117] H: Drying treatment: Heat and dry the calendered film at 300℃ for 30 minutes to remove the lubricant from the calendered film, and obtain the dried calendered film. The lubricant can be recycled.

[0118] I: Longitudinal stretching: The dried calendered film is stretched 1000% longitudinally at 350℃ to obtain a longitudinally stretched calendered film.

[0119] J: Transverse stretching: Under a temperature of 250°C, the longitudinally stretched calendered film is subjected to a transverse stretch of 2500% to obtain a composite film.

[0120] K: Roll pressing: The above composite film, which has been stretched longitudinally and laterally, is flexibly rolled to obtain a pressed film.

[0121] L: The above-mentioned press-fit film is sintered and shaped at a high temperature of 350℃ for 5 minutes to obtain a shaped composite film.

[0122] M: The shaped composite membrane was soaked in 1 mol / L sulfuric acid solution at 80℃ for 24 hours, then soaked in deionized water for 20 minutes, washed three times, and dried at 50℃ for 20 minutes.

[0123] Example 9

[0124] Unlike Example 1, in step I, the dried calendered film is subjected to 1100% longitudinal stretching.

[0125] Example 10

[0126] Unlike Example 1, in step I, the dried calendered film is stretched longitudinally by 400%.

[0127] The difference between Example 11 and Example 1 is that in step J, the longitudinally stretched calendered film is subjected to a 2500% transverse stretch.

[0128] Example 12

[0129] Unlike Example 1, in step J, the longitudinally stretched calendered film is subjected to a 500% transverse stretch.

[0130] Comparative Example 1

[0131] Using existing three-layer composite proton exchange membranes, such as Figure 2 As shown.

[0132] Test method for linear swelling ratio of composite proton exchange membranes:

[0133] Take a 7cm × 7cm sample of proton exchange membrane material, mark the TD × MD direction, and immerse the proton exchange membrane in 80℃ deionized water for 8 hours. After immersion, measure the dimensions of the proton exchange membrane. The results are: TD1 × MD1 = (TD1 - 7) / 7 × 100%, = (MD1 - 7) / 7 × 100%.

[0134] Test methods for water / alcohol resistance:

[0135] Take a 7cm×7cm sample of proton exchange membrane material, dry it at 80℃ for 24 hours, and weigh the proton exchange membrane mass M1. Soak the proton exchange membrane in 80℃ (deionized water or a water: alcohol = 1:1 mixed solution) for 8 hours, take it out and dry it at 80℃ for 24 hours, and weigh the proton exchange membrane mass M2.

[0136] The water dissolution rate is calculated as follows: Water dissolution rate = (M1-M2) / M1.

[0137] The test results of the anti-swelling composite proton exchange membranes prepared in the above embodiments and comparative examples are as follows:

[0138] Table 1

[0139]

[0140]

[0141] like Figure 2 As shown, the three-layer composite proton exchange membrane in Comparative Example 1 includes a first perfluorosulfonic acid resin layer 1, a perfluorosulfonic acid resin-impregnated ePTFE composite layer 2, and a second perfluorosulfonic acid resin layer 3. The first perfluorosulfonic acid resin layer 1 and the second perfluorosulfonic acid resin layer 3 are the main swelling regions. However, the composite proton exchange membrane in this application does not have a perfluorosulfonic acid resin layer. Therefore, the composite proton exchange membranes prepared in Examples 1-5 of this application have better anti-swelling properties compared to Comparative Example 1.

[0142] In Comparative Example 1, the three-layer composite proton exchange membrane was formed by impregnating ePTFE with a perfluorosulfonic acid resin solution. The perfluorosulfonic acid resin can enter the ePTFE and also dissolve from the ePTFE. In contrast, the composite proton exchange membranes in Examples 1-5 were formed by directly compounding with perfluorosulfonic acid resin particles and biaxially stretching them. The perfluorosulfonic acid resin particles did not undergo a dissolution process, so the composite proton exchange membranes had better solvent resistance and leaching resistance.

[0143] Based on the percentage content of perfluorosulfonic acid resin in Examples 1-12 and Comparative Example 1, it can be seen that the composite proton exchange membranes in Examples 1-12 do not have a perfluorosulfonic acid resin layer, thus reducing the amount of perfluorosulfonic acid resin used and lowering costs.

[0144] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: This application directly combines perfluorosulfonic acid resin particles with polytetrafluoroethylene to form a composite reinforced structure, and the perfluorosulfonic acid resin particles are uniformly dispersed inside the pores of the expanded polytetrafluoroethylene fiber membrane, which can effectively improve the filling performance of ePTFE and perfluorosulfonic acid resin particles, thereby improving the anti-swelling performance of the composite proton exchange membrane, reducing the dissolution of perfluorosulfonic acid resin, and also effectively reducing the amount of perfluorosulfonic acid resin used and improving the life and durability of the composite proton exchange membrane.

[0145] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a composite proton exchange membrane, characterized in that, The preparation method includes: Step S1: Mix polytetrafluoroethylene resin powder and perfluorosulfonate resin particles to obtain a mixture; Step S2: The mixture is subjected to a aging process to obtain an aged mixture; Step S3: Mix the cured mixture with a lubricant to obtain a mixture with added lubricant; Step S4: The mixture with added lubricant is extruded to obtain a blank raw material; the blank raw material is calendered into a film to obtain a calendered film. Step S5: Heat and dry the calendered film to remove the lubricant, obtaining a dried calendered film; then biaxially stretch the dried calendered film to obtain a composite film. Step S6: The composite film is subjected to flexible roller pressing to obtain a pressed film; the pressed film is sintered and shaped to obtain a shaped composite film. Step S7: The shaped composite membrane is acidified to obtain an acidified composite membrane; the acidified composite membrane is dried to obtain the composite proton exchange membrane; the composite proton exchange membrane includes an expanded polytetrafluoroethylene fiber membrane and perfluorosulfonic acid resin particles distributed in the pores of the expanded polytetrafluoroethylene fiber membrane. The polytetrafluoroethylene resin powder comprises 100 parts by weight, the perfluorosulfonate resin particles comprise 1 to 25 parts by weight, and the lubricant comprises 15 to 30 parts by weight.

2. The preparation method according to claim 1, characterized in that, The thickness of the composite proton exchange membrane is 5~150 μm. And / or, the average particle size of the perfluorosulfonic acid resin particles is 100~200μm; And / or, the expanded polytetrafluoroethylene fiber membrane has a fiber diameter of 50~500nm.

3. The preparation method according to claim 1, characterized in that, The perfluorosulfonic acid resin particles account for 1% to 25% of the mass of the composite proton exchange membrane.

4. The preparation method according to claim 1, characterized in that, The preparation method further includes the step of preparing perfluorosulfonate resin particles: The perfluorosulfonate resin particles are obtained by mixing sulfonyl fluoride resin with an aqueous solution of potassium hydroxide and / or sodium hydroxide and heating the mixture.

5. The preparation method according to claim 4, characterized in that, The temperature of the heating reaction is 70~90℃; And / or, the perfluorosulfonate resin particles are sodium perfluorosulfonate particles and / or potassium perfluorosulfonate resin particles.

6. The preparation method according to claim 4, characterized in that, The heating reaction takes 1 to 3 hours.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The average particle size of the polytetrafluoroethylene resin powder is 300~500μm; and / or, the crystallinity of the polytetrafluoroethylene resin powder is not less than 98%.

8. The preparation method according to any one of claims 1 to 6, characterized in that, The lubricant is one or more of petroleum ether, white oil, silicone oil, alcohols, and aromatic hydrocarbons.

9. The preparation method according to any one of claims 1 to 6, characterized in that, In step S2, the ripening temperature is 25~40℃; And / or, the ripening time is not less than 24 hours; And / or, in step S4, the extrusion molding pressure is 3~10MPa; And / or, the calendering temperature is 50~80℃; And / or, the thickness of the calendered film is 1~2 mm.

10. The preparation method according to any one of claims 1 to 6, characterized in that, In step S2, the ripening time is 24~48 hours.

11. The preparation method according to any one of claims 1 to 6, characterized in that, In step S5, the heating and drying temperature is 200~300℃; and / or, the heating and drying time is 10~30 min; And / or, the bidirectional tension includes longitudinal tension and transverse tension.

12. The preparation method according to claim 11, characterized in that, The longitudinal stretching includes: stretching the dried calendered film by 400% to 1000% at a temperature of 250 to 350°C; the transverse stretching includes: stretching the dried calendered film by 500% to 2500% at a temperature of 200 to 250°C.

13. The preparation method according to any one of claims 1 to 6, characterized in that, In step S6, the sintering temperature is 300~350℃; and / or the sintering time is 2~5 min.

14. The preparation method according to any one of claims 1 to 6, characterized in that, In step S7, the drying temperature is 50~80℃, and the drying time is 5~20 min; and / or, the acidification treatment includes: The shaped composite membrane is immersed in a 1-2 mol / L sulfuric acid solution at 50-80℃ for 20-48 hours to obtain the acidified composite membrane. And / or, the acidification treatment further includes cleaning the acidified composite membrane at least once.

15. The preparation method according to claim 14, wherein the solvent for cleaning is water; And / or, the cleaning time is 10~20 minutes.

16. The application of a composite proton exchange membrane obtained by the preparation method according to any one of claims 1 to 15, characterized in that, The applications include: applying the composite proton exchange membrane to fuel cells and PEM water electrolysis for hydrogen production.

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