Perfluorosulfonic acid resin dispersion liquid suitable for preparation of proton exchange membrane and preparation method of perfluorosulfonic acid resin dispersion liquid

Abstract

The invention discloses a perfluorosulfonic acid resin dispersion liquid suitable for proton exchange membrane preparation and a preparation method thereof, belongs to the technical field of perfluorosulfonic acid resin dispersion liquid, and aims to solve the technical problem of poor thermal stability of perfluorosulfonic acid ion exchange resin prepared in the prior art. A preparation method of a perfluorinated sulfonic acid resin dispersion liquid suitable for proton exchange membrane preparation comprises the following steps: S1, adding deionized water, CF2 = CFO (CF2) 3COOCH3, CF2 = CFOCF2CF2CF3 and a high-temperature-resistant coating into a polymerization reaction kettle, and uniformly mixing to obtain a prepolymer; reacting the reaction system at high temperature and high pressure to obtain a perfluorosulfonic acid resin emulsion; and performing post-process treatment on the perfluorosulfonic acid resin emulsion to prepare the perfluorosulfonic acid resin polymer. The perfluorinated sulfonic acid resin film prepared from the perfluorinated sulfonic acid resin dispersion liquid provided by the invention still has excellent mechanical properties and thermal stability while having excellent water absorption.

Description

Technical Field

[0001] The present invention belongs to the technical field of perfluorosulfonic acid resin dispersions, and particularly relates to a perfluorosulfonic acid resin dispersion suitable for the preparation of proton exchange membranes and a preparation method thereof. Background Art

[0002] Proton exchange membrane fuel cells have the characteristics of high power density, high energy conversion efficiency, environmental protection and pollution-free, low heat radiation, etc., and are ideal energy sources for future pure electric vehicles, small fixed base stations and portable electrical equipment; in proton exchange membrane fuel cells, the proton exchange membrane plays a role in conducting protons, serving as an electrode reaction medium and a catalyst carrier, and isolating cathode and anode reactants. The polymer membrane prepared from perfluorosulfonic acid resin molecules has a long service life.

[0003] The side chain of perfluorosulfonic acid resin is a perfluoroether structure with a sulfonic acid group at the end; the electron-rich fluorine atom is larger in volume than the hydrogen atom and has a small polarizability. Through the chain rotation of the molecule, the fluorine atom can closely cover the carbon-carbon main chain to form a fluorine atom protection layer with low surface free energy. Therefore, perfluorinated ion polymers have excellent thermal stability and chemical stability. The side chain of the ion polymer is fixed on the main chain through an ether bond, and the end group is a sulfonic acid group with a cation exchange function. The strong electron-withdrawing effect of the fluorine atom increases the acidity of the sulfonic acid group, making it completely dissociated in water, and its acidity is equivalent to that of sulfuric acid, thereby enhancing the ion conductivity of the material. However, like most other fluororesins, perfluorosulfonic acid ion exchange resins often have problems of thermal instability during thermal processing at high temperatures.

[0004] Patent application CN103146001A discloses a preparation method of a perfluorosulfonic acid resin solution with uniformly dispersed molecular chains. The solid perfluorosulfonic acid resin is placed in a mixed solvent of water and an organic solvent, and then through a dissolution and liquid-liquid separation process, the lower layer solution is taken out as the perfluorosulfonic acid resin solution with uniformly dispersed chains. However, the above-mentioned prior art only provides the process steps for preparing the perfluorosulfonic acid resin solution from the solid perfluorosulfonic acid resin, but fails to solve the problem of how to improve the thermal stability of the prepared perfluorosulfonic acid resin dispersion. Summary of the Invention

[0005] The purpose of the present invention is to provide a perfluorosulfonic acid resin dispersion suitable for the preparation of proton exchange membranes and a preparation method thereof, so as to solve the technical problem of poor thermal stability of the perfluorosulfonic acid ion exchange resin prepared by the prior art.

[0006] The purpose of the present invention can be achieved by the following technical solutions: A preparation method of a perfluorosulfonic acid resin dispersion suitable for the preparation of proton exchange membranes, comprising the following steps: S1. Deionized water, CF2=CFO(CF2)3COOCH3, CF2=CFOCF2CF2CF3 and a high-temperature resistant coating are added to a polymerization reactor and mixed evenly to obtain a prepolymer; an emulsifier, an initiator, a buffer and a molecular weight regulator are added to the prepolymer and mixed evenly to obtain a reaction system; S2. The reaction system reacts at 55 - 60 °C and 13.5 - 15 kgf / cm 2 for 5 - 7 h to obtain a perfluorosulfonic acid resin emulsion; the perfluorosulfonic acid resin emulsion is coagulated in concentrated sulfuric acid and vacuum dried to prepare a perfluorosulfonic acid resin polymer; In a polymerization reactor, an emulsifier, an initiator and a buffer are added as additives, and CF2=CFO(CF2)3COOCH3, CF2=CFOCF2CF2CF3 containing unsaturated double bonds and a high-temperature resistant coating are polymerized to obtain a perfluorosulfonic acid resin emulsion. The perfluorosulfonic acid resin emulsion is coagulated in concentrated sulfuric acid and vacuum dried to prepare a perfluorosulfonic acid resin polymer.

[0007] S3. The perfluorosulfonic acid resin polymer and an organic solvent are added to a high-pressure reactor, pressurized to 0.4 - 0.6 MPa and maintained for 2 h under a nitrogen atmosphere; after 2 h, stirring and temperature-raising reaction are carried out, and after the reaction is completed, the temperature is lowered and the pressure is released to obtain a perfluorosulfonic acid resin dispersion.

[0008] The perfluorosulfonic acid resin polymer is added to an organic solvent and mixed evenly to obtain a perfluorosulfonic acid resin dispersion. The above perfluorosulfonic acid resin dispersion can be used as a raw material for preparing a proton exchange membrane.

[0009] Furthermore, the preparation method of the high-temperature resistant coating includes the following steps: A1. Carbon nanotubes and a 60 - 70% wt nitric acid solution are mixed and reacted at 130 - 140 °C for 10 - 12 h, and then cooled and filtered to obtain a solid; the solid is washed with distilled water until the pH value of the filtrate is neutral to obtain modified carbon nanotubes; The carbon nanotubes can be modified with concentrated nitric acid to obtain modified carbon nanotubes rich in carboxyl groups.

[0010] A2. Under a nitrogen atmosphere, the modified carbon nanotubes and hydroxypropyl acrylate undergo an amidation reaction at 120 - 240 °C for 4 - 8 h, and then filtered to obtain solid carbon nanotubes modified with unsaturated double bonds; The modified carbon nanotubes rich in carboxyl groups and hydroxypropyl acrylate undergo an esterification reaction to obtain solid carbon nanotubes modified with unsaturated double bonds.

[0011] A3. The carbon nanotubes modified with unsaturated double bonds, deionized water, a fluorocarbon resin, an antifoaming agent and a dispersant are mixed to obtain a mixture; the mixture and deionized water are mixed and ball-milled to obtain a suspension; the suspension is ultrasonically dispersed to obtain a dispersion; Add a film-forming auxiliary agent and a curing agent to the dispersion liquid in sequence, and then post-cure for 5 - 10 minutes to obtain a high-temperature resistant coating.

[0012] Mix carbon nanotubes modified with solid unsaturated double bonds and fluorocarbon resin, and prepare a high-temperature resistant coating under the action of relevant auxiliary agents.

[0013] Furthermore, in step A1, the dosage ratio of carbon nanotubes to nitric acid solution is 5 - 10 g:100 mL; in step A2, the dosage ratio of modified carbon nanotubes to hydroxypropyl acrylate is 6 - 12 g:14 - 21 g.

[0014] Furthermore, in step A3, the defoaming agent is an organosilicon defoaming agent, and the dispersant is stearic acid; the dosage ratio of carbon nanotubes modified with unsaturated double bonds, deionized water, fluorocarbon resin, defoaming agent and dispersant is 10 - 20 g:15 - 20 g:60 - 80 g:0.1 - 1 g:0.1 - 1 g; the dosage of the mixture is 35 - 45 g, the concentration of the suspension is 3 - 5 g / L; the frequency of ultrasonic dispersion is 20 - 30 KHz, and the duration of ultrasonic dispersion is 5 - 10 minutes.

[0015] Furthermore, in step A4, the film-forming auxiliary agent is dodecyl alcohol ester, and the curing agent is diethylenetriamine; the dosage ratio of the dispersion liquid, film-forming auxiliary agent and curing agent is 80 - 100 g:1 - 2 g:3 - 5 g.

[0016] Furthermore, in step S1, the dosage ratio of deionized water, CF2=CFO(CF2)3COOCH3, CF2=CFOCF2CF2CF3 and high-temperature resistant coating is 13 - 15 L:1400 - 1700 g:290 - 310 g; the emulsifier is sodium stearate, the initiator is sodium persulfate, the buffer is allylsulfonic acid sodium, and the molecular weight regulator is n-hexane; the dosage ratio of the prepolymer, emulsifier, initiator, buffer and molecular weight regulator is 1500 L:50 - 80 g:140 - 150 g:50 - 100 g:200 - 300 g.

[0017] Furthermore, in step S2, the temperature of vacuum drying is 70 - 80 °C and the duration of vacuum drying is 10 - 12 h; in step S3, the organic solvent is a mixture of water, 45% wt n-propanol and 2 - 5% wt ethanol mixed in a mass ratio of 10:1:0.5 - 1; the reaction temperature is 140 - 150 °C, the reaction duration is 12 - 15 h, and the reaction pressure is 1 - 1.2 MPa.

[0018] As another aspect of the present invention, a perfluorosulfonic acid resin dispersion liquid prepared by the preparation method of a perfluorosulfonic acid resin dispersion liquid applicable to the preparation of a proton exchange membrane.

[0019] The present invention has the following beneficial effects: 1. The present invention provides a method for preparing a perfluorosulfonic acid resin dispersion. Using CF2=CFO(CF2)3COOCH3 and CF2=CFOCF2CF2CF3 as reaction monomers, adding a high-temperature resistant coating for modification, a perfluorosulfonic acid resin emulsion is prepared by free radical addition polymerization. The perfluorosulfonic acid resin emulsion is subjected to coagulation and vacuum drying processes to prepare a perfluorosulfonic acid resin polymer. The perfluorosulfonic acid resin polymer is dispersed in an organic solvent to prepare a perfluorosulfonic acid resin dispersion suitable for proton exchange membranes. The perfluorosulfonic acid resin dispersion prepared by the present invention improves its own high-temperature resistance and thermal stability.

[0020] 2. Carbon nanotubes are modified with nitric acid solution to obtain carbon nanotubes rich in carboxyl groups; hydroxypropyl acrylate and modified carbon nanotubes are subjected to an esterification reaction to obtain carbon nanotubes modified with unsaturated double bonds. Under the action of relevant additives, the carbon nanotubes modified with unsaturated double bonds and fluorocarbon resin are formed into a film and cured to prepare a high-temperature resistant coating. In the process of synthesizing the perfluorosulfonic acid resin polymer, adding an appropriate amount of the high-temperature resistant coating can significantly improve the thermal stability of the prepared perfluorosulfonic acid resin dispersion in high-temperature hot processing. Specific Embodiments

[0021] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0022] The carbon nanotubes used in Examples 1-3 of the present invention were purchased from Jiaxing Bona New Materials Co., Ltd., with the model NACO-CNTs, the product number NACO-CNTs-1, a length of 5-15 μm, and a fineness of 7-15 nm; the fluorocarbon resin used in Examples 1-3 of the present invention was purchased from Shanghai Dongfu Chemical Technology Co., Ltd., specifically the solvent-based fluorocarbon resin DF-300, with a fluorine content of 7-9%wt and a viscosity of 90-120 s.

[0023] Example 1 This example provides a method for preparing a high-temperature resistant coating for a perfluorosulfonic acid resin dispersion suitable for the preparation of proton exchange membranes, including the following steps: A1. Mix 5 g of carbon nanotubes with 100 mL of 60%wt nitric acid solution and react at 130 °C for 10 h, then cool and filter to obtain a solid; the solid is washed with distilled water until the pH value of the filtrate is neutral to obtain modified carbon nanotubes.

[0024] A2. Add 6 g of modified carbon nanotubes and 14 g of hydroxypropyl acrylate to a reaction kettle. Introduce the protective gas nitrogen into the reaction kettle, insert an oil-water separator and a condenser, heat up to 120 °C, carry out an esterification reaction for 4 h, and then filter to obtain carbon nanotubes modified with solid unsaturated double bonds.

[0025] A3. Mix 10 g of carbon nanotubes modified with unsaturated double bonds, 15 g of deionized water, 60 g of fluorocarbon resin, 0.1 g of silicone defoamer, and 0.1 g of dispersant stearic acid to obtain a mixture. Add 35 g of the mixture to a ball mill and grind for 20 min, and then add deionized water to prepare a suspension with a concentration of 3 g / L; the above suspension is ultrasonically dispersed in a cell disruptor, the ultrasonic dispersion frequency is 20 KHz, and the ultrasonic dispersion time is 5 min to obtain a dispersion.

[0026] A4. Add 1 g of film-forming auxiliary dodecyl alcohol ester to 80 g of the dispersion, and then add 3 g of curing agent diethylenetriamine and cure for 5 min to prepare a high-temperature resistant coating for perfluorosulfonic acid resin dispersion suitable for proton exchange membrane preparation.

[0027] Example 2 This example provides a preparation method of a high-temperature resistant coating for perfluorosulfonic acid resin dispersion suitable for proton exchange membrane preparation, including the following steps: A1. Mix 8 g of carbon nanotubes with 100 mL of 65% wt nitric acid solution and react at 133 °C for 11 h, and then cool and filter to obtain a solid; the solid is washed with distilled water until the pH value of the filtrate is neutral to obtain modified carbon nanotubes.

[0028] A2. Add 9 g of modified carbon nanotubes and 17 g of hydroxypropyl acrylate to a reaction kettle. Introduce the protective gas nitrogen into the reaction kettle, insert an oil-water separator and a condenser, heat up to 180 °C, carry out an esterification reaction for 6 h, and then filter to obtain carbon nanotubes modified with solid unsaturated double bonds.

[0029] A3. Mix 15 g of carbon nanotubes modified with unsaturated double bonds, 18 g of deionized water, 70 g of fluorocarbon resin, 0.5 g of silicone defoamer, and 0.5 g of dispersant stearic acid to obtain a mixture. Add 40 g of the mixture to a ball mill and grind for 25 min, and then add deionized water to prepare a suspension with a concentration of 4 g / L; the above suspension is ultrasonically dispersed in a cell disruptor, the ultrasonic dispersion frequency is 22 KHz, and the ultrasonic dispersion time is 8 min to obtain a dispersion.

[0030] A4. Add 1.5 g of film-forming auxiliary dodecyl alcohol ester to 90 g of the dispersion, and then add 4 g of curing agent diethylenetriamine and cure for 8 min to prepare a high-temperature resistant coating for perfluorosulfonic acid resin dispersion suitable for proton exchange membrane preparation.

[0031] Example 3 This example provides a preparation method of a high-temperature resistant coating for a perfluorosulfonic acid resin dispersion suitable for proton exchange membrane preparation, including the following steps: A1. Mix 10 g of carbon nanotubes with 100 mL of 70% wt nitric acid solution, react at 140 °C for 12 h, then cool and filter to obtain a solid; wash the solid with distilled water until the pH value of the filtrate is neutral to obtain modified carbon nanotubes.

[0032] A2. Add 12 g of modified carbon nanotubes and 21 g of hydroxypropyl acrylate to a reaction kettle, introduce the protective gas nitrogen into the reaction kettle, insert an oil-water separator and a condenser, heat up to 240 °C, carry out an esterification reaction for 8 h, then filter to obtain carbon nanotubes modified with solid unsaturated double bonds.

[0033] A3. Mix 20 g of carbon nanotubes modified with unsaturated double bonds, 20 g of deionized water, 80 g of fluorocarbon resin, 1 g of silicone defoamer and 1 g of dispersant stearic acid to obtain a mixture. Add 45 g of the mixture to a ball mill and grind for 30 min, then add deionized water to prepare a 5 g / L suspension; ultrasonically disperse the above suspension in a cell disruptor, the frequency of ultrasonic dispersion is 30 KHz, and the duration of ultrasonic dispersion is 10 min to obtain a dispersion.

[0034] A4. Add 2 g of film-forming auxiliary dodecyl alcohol ester to 100 g of the dispersion, then add 5 g of curing agent diethylenetriamine and cure for 10 min to prepare a high-temperature resistant coating for a perfluorosulfonic acid resin dispersion suitable for proton exchange membrane preparation.

[0035] Example 4 This example provides a preparation method of a perfluorosulfonic acid resin dispersion suitable for proton exchange membrane preparation, including the following steps: S1. Select a 20 L nickel alloy substrate reaction kettle as the polymerization reaction kettle, add 13 L of deionized water, 1400 g of CF2=CFO(CF2)3COOCH3, 290 g of CF2=CFOCF2CF2CF3, and 30 g of the high-temperature resistant coating prepared in Example 1 to the above polymerization reaction kettle, mix well to obtain a prepolymer. Reserve 1500 L of the prepolymer in the polymerization reaction kettle, then continue to add 50 g of emulsifier ammonium perfluorooctanoate, 140 g of initiator sodium persulfate, 50 g of buffer allylsulfonic acid sodium and 200 g of molecular weight regulator n-hexane to the above polymerization reaction kettle, and mix well to obtain a reaction system.

[0036] S2. Then adjust the temperature of the above polymerization reaction kettle to 55 °C and the pressure of the polymerization reaction kettle to 13.5 kgf / cm 2, followed by a constant temperature and pressure reaction for 5 h to obtain a perfluorosulfonic acid resin emulsion. The perfluorosulfonic acid resin emulsion is coagulated in concentrated sulfuric acid and then placed in a vacuum drying oven to dry at 70 °C for 10 h to prepare a perfluorosulfonic acid resin polymer.

[0037] S3. Water, 45% wt of n-propanol and 2 - 5% wt of ethanol are mixed evenly according to a mass ratio of 10:1:0.5 to obtain an organic solvent. The perfluorosulfonic acid resin polymer and the organic solvent are added to a high-pressure reaction kettle according to a solid-liquid ratio of 1:5. The high-pressure reaction kettle is filled with nitrogen and pressurized to 0.4 MPa and maintained for 2 h; after 2 h, it is stirred and heated to 140 °C for reaction for 12 h. The rotation speed of the high-pressure reaction kettle is 500 r / min, and the reaction pressure is 1 MPa; after the reaction is completed, it is cooled and depressurized to obtain a perfluorosulfonic acid resin dispersion.

[0038] Example 5 This example provides a preparation method of a perfluorosulfonic acid resin dispersion suitable for the preparation of a proton exchange membrane, including the following steps: S1. Select a 20 L reaction kettle with a nickel alloy substrate as the polymerization reaction kettle. Add 14 L of deionized water, 1600 g of CF2=CFO(CF2)3COOCH3, 300 g of CF2=CFOCF2CF2CF3, and 40 g of the high-temperature resistant coating prepared in Example 2 to the above polymerization reaction kettle, and mix evenly to obtain a prepolymer. The polymerization reaction kettle retains 1500 L of the prepolymer, and then continue to add 70 g of the emulsifier ammonium perfluorooctanoate, 145 g of the initiator sodium persulfate, 80 g of the buffer sodium allylsulfonate, and 260 g of the molecular weight regulator n-hexane to the above polymerization reaction kettle, and mix evenly to obtain a reaction system.

[0039] S2. Then adjust the temperature of the above polymerization reaction kettle to 58 °C and the pressure of the polymerization reaction kettle to 14.5 kgf / cm 2 , followed by a constant temperature and pressure reaction for 6 h to obtain a perfluorosulfonic acid resin emulsion. The perfluorosulfonic acid resin emulsion is coagulated in concentrated sulfuric acid and then placed in a vacuum drying oven to dry at 75 °C for 11 h to prepare a perfluorosulfonic acid resin polymer.

[0040] S3. Water, 45% wt of n-propanol and 3% wt of ethanol are mixed evenly according to a mass ratio of 10:1:0.8 to obtain an organic solvent. The perfluorosulfonic acid resin polymer and the organic solvent are added to a high-pressure reaction kettle according to a solid-liquid ratio of 1:5. The high-pressure reaction kettle is filled with nitrogen and pressurized to 0.5 MPa and maintained for 2 h; after 2 h, it is stirred and heated to 146 °C for reaction for 13 h. The rotation speed of the high-pressure reaction kettle is 580 r / min, and the reaction pressure is 1.1 MPa; after the reaction is completed, it is cooled and depressurized to obtain a perfluorosulfonic acid resin dispersion.

[0041] Example 6 This embodiment provides a method for preparing a perfluorosulfonic acid resin dispersion suitable for the preparation of a proton exchange membrane, comprising the following steps: S1. Select a 20 L nickel alloy substrate reaction kettle as the polymerization reaction kettle. Add 15 L of deionized water, 1700 g of CF2=CFO(CF2)3COOCH3, 310 g of CF2=CFOCF2CF2CF3, and 50 g of the high-temperature resistant coating prepared in Example 3 to the above polymerization reaction kettle, and mix well to obtain a prepolymer. Reserve 1500 L of the prepolymer in the polymerization reaction kettle, and then continue to add 80 g of the emulsifier ammonium perfluorooctanoate, 150 g of the initiator sodium persulfate, 100 g of the buffer sodium allylsulfonate, and 300 g of the molecular weight regulator n-hexane to the above polymerization reaction kettle, and mix well to obtain a reaction system.

[0042] S2. Then adjust the temperature of the above polymerization reaction kettle to 60 °C and the pressure of the polymerization reaction kettle to 15 kgf / cm 2 , and then carry out a constant temperature and constant pressure reaction for 7 h to obtain a perfluorosulfonic acid resin emulsion. Coagulate the perfluorosulfonic acid resin emulsion in concentrated sulfuric acid, and then place it in a vacuum drying oven and dry it at 80 °C for 12 h to prepare a perfluorosulfonic acid resin polymer.

[0043] S3. Mix water, 45% wt of n-propanol, and 5% wt of ethanol according to a mass ratio of 10:1:1 to obtain an organic solvent. Add the perfluorosulfonic acid resin polymer and the organic solvent to a high-pressure reaction kettle according to a solid-liquid ratio of 1:5. Fill the high-pressure reaction kettle with nitrogen and pressurize it to 0.6 MPa and keep it for 2 h; after 2 h, stir and heat up to 150 °C and react for 15 h. The rotation speed of the high-pressure reaction kettle is 600 r / min, and the reaction pressure is 1.2 MPa; after the reaction is completed, cool down and release the pressure to obtain a perfluorosulfonic acid resin dispersion.

[0044] Comparative Example 1 The difference between this comparative example and Example 6 is that when preparing the high-temperature resistant coating, steps A1 and A2 are cancelled, and 12 g of carbon nanotubes are used to replace the unsaturated double bond-modified carbon nanotubes.

[0045] Comparative Example 2 The difference between this comparative example and Example 6 is that a fluorocarbon resin of the same mass is used to replace the high-temperature resistant coating.

[0046] Comparative Example 3 The difference between this comparative example and Example 6 is that in step S1, ammonium perfluorooctanoate is replaced with sodium dodecyl sulfate of the same mass.

[0047] Performance test: The perfluorosulfonic acid resin dispersion prepared in Examples 4-6 was evaporated in turn to obtain a solid perfluorosulfonic acid resin. The solid perfluorosulfonic acid resin was then added to an extruder for melt extrusion to obtain a perfluorosulfonic acid resin film; the extrusion temperature was 180°C and the extrusion speed was 50r / min to obtain a film. The film thickness was 250μm and was marked as Examples 7-9 in turn.

[0048] 1. The perfluorosulfonic acid resin films of Examples 7-9 were subjected to thermogravimetric analysis in a nitrogen atmosphere using a TGA tester at a heating rate of 20° C. / min, and their weight loss rates at 200° C. were measured.

[0049] 2. According to GB13022-91 "Test method for tensile properties of plastic films", the tensile properties of the perfluorosulfonic acid resin of Examples 7-9 were tested; the measuring temperature was 23°C, the humidity was 50%, the tensile speed was 20 mm / min, and the maximum tensile strength values ​​in the transverse and longitudinal directions were recorded respectively.

[0050] 3. Take 1g of the perfluorosulfonic acid resin polymer prepared in Example 7-9 and put it into an oven at 80°C to dry. Take it out after 1 hour and weigh it, marked as M1; then put it in water at 100°C for 1 hour and take it out, measure its weight, marked as M2. Calculate its water absorption rate, the water absorption rate calculation formula is: [(M2-M1) / M1]×100%. The specific test results are shown in Table 1: Table 1. Sample performance test data

[0051] Data analysis: The perfluorosulfonic acid resin films prepared in Examples 7-9 of the present invention (using the perfluorosulfonic acid resin dispersions prepared in Examples 4-6 of the present invention) have high thermal stability, and their weight loss rates at 200°C are all less than 3%. However, in Comparative Example 2 of the present invention, the high temperature resistant coating is replaced by fluorocarbon resin, which significantly reduces the thermal stability of the prepared perfluorosulfonic acid resin film.

[0052] The perfluorosulfonic acid resin films prepared in Examples 7-9 of the present invention and Comparative Examples 1-2 all have high water absorption rates, indicating that adding an appropriate amount of high temperature resistant coating to the prepared perfluorosulfonic acid resin film will not affect the water absorption performance of the perfluorosulfonic acid resin film. In Comparative Example 3, replacing the emulsifier ammonium perfluorooctanoate with an equal mass of sodium dodecyl sulfate can appropriately improve the water absorption performance of the prepared perfluorosulfonic acid resin.

[0053] The perfluorosulfonic acid resin films prepared in Examples 7-9 of the present invention have excellent mechanical properties, which are manifested in that they have higher transverse maximum tensile strength values ​​and longitudinal tensile strength values. However, in Comparative Example 1, when preparing the high temperature resistant coating, the carbon nanotubes modified with unsaturated double bonds are replaced with carbon nanotubes of equal mass. The carbon nanotubes modified with unsaturated double bonds can be polymerized with other monomers of the synthetic perfluorosulfonic acid resin emulsion to form a whole, thereby improving the mechanical properties of the prepared perfluorosulfonic acid resin film; therefore, the mechanical properties of the perfluorosulfonic acid resin film prepared in Comparative Example 1 are significantly reduced. In Comparative Example 2, the high temperature resistant coating is replaced with fluorocarbon resin of equal mass, and the mechanical properties of the prepared perfluorosulfonic acid resin film are reduced.

[0054] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0056] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a perfluorosulfonic acid resin dispersion suitable for preparing a proton exchange membrane, characterized in that: The following steps are involved: S1, deionized water, CF2=CFO(CF2)3COOCH3, CF2=CFOCF2CF2CF3 and high temperature resistant coating are added to a polymerization reaction kettle and mixed to obtain a prepolymer; an emulsifier, an initiator, a buffer and a molecular weight regulator are added to the prepolymer and mixed to obtain a reaction system; S2, reaction system at 55-60℃, 13.5-15kgf / cm 2 The reaction was continued for 5-7 hours to obtain a perfluorosulfonic acid resin emulsion; the perfluorosulfonic acid resin emulsion was condensed in concentrated sulfuric acid and dried in vacuum to prepare a perfluorosulfonic acid resin polymer; S3, perfluorosulfonic acid resin polymer and organic solvent are added into a high-pressure reactor, and under a nitrogen atmosphere, the pressure is increased to 0.4-0.6 MPa and maintained for 2 hours; after 2 hours, the reaction is stirred and the temperature is increased. After the reaction is completed, the temperature is lowered and the pressure is released to obtain a perfluorosulfonic acid resin dispersion.

2. The method for preparing a perfluorosulfonic acid resin dispersion suitable for preparing a proton exchange membrane according to claim 1, characterized in that: The preparation method of the high temperature resistant coating comprises the following steps: A1, mixing carbon nanotubes and 60-70%wt nitric acid solution, reacting at 130-140°C for 10-12h, cooling and filtering to obtain a solid; washing the solid with distilled water until the pH value of the filtrate is neutral to obtain modified carbon nanotubes; A2. Under a nitrogen atmosphere, the modified carbon nanotubes and hydroxypropyl acrylate are subjected to an esterification reaction at 120-240° C. for 4-8 hours, followed by filtration to obtain solid unsaturated double-bond modified carbon nanotubes; A3, unsaturated double bond modified carbon nanotubes, deionized water, fluorocarbon resin, defoamer and dispersant are mixed to obtain a mixture; the mixture is mixed with deionized water and ball milled to obtain a suspension; the suspension is ultrasonically dispersed to obtain a dispersion; A4. Add film-forming aid and curing agent to the dispersion in sequence, and then post-ripen for 5-10 minutes to prepare a high temperature resistant coating.

3. The method for preparing a perfluorosulfonic acid resin dispersion suitable for preparing a proton exchange membrane according to claim 2, characterized in that: In step A1, the ratio of carbon nanotubes to nitric acid solution is 5-10 g:100 mL; in step A2, the ratio of modified carbon nanotubes to hydroxypropyl acrylate is 6-12 g:14-21 g.

4. The method for preparing a perfluorosulfonic acid resin dispersion suitable for preparing a proton exchange membrane according to claim 2, characterized in that: In step A3, the defoaming agent is a silicone defoaming agent, and the dispersing agent is stearic acid; the dosage ratio of unsaturated double bond modified carbon nanotubes, deionized water, fluorocarbon resin, defoaming agent and dispersing agent is 10-20g:15-20g:60-80g:0.1-1g:0.1-1g; the dosage of the mixture is 35-45g, and the concentration of the suspension is 3-5g / L; the frequency of ultrasonic dispersion is 20-30KHz, and the duration of ultrasonic dispersion is 5-10min.

5. The method for preparing a perfluorosulfonic acid resin dispersion suitable for preparing a proton exchange membrane according to claim 2, characterized in that: In step A4, the film-forming aid is dodecanol ester, and the curing agent is diethylenetriamine; the usage ratio of the dispersion, the film-forming aid and the curing agent is 80-100 g: 1-2 g: 3-5 g.

6. The method for preparing a perfluorosulfonic acid resin dispersion suitable for preparing a proton exchange membrane according to claim 1, characterized in that: In step S1, the dosage ratio of deionized water, CF2=CFO(CF2)3COOCH3, CF2=CFOCF2CF2CF3 and high temperature resistant coating is 13-15L:1400-1700g:290-310g; the emulsifier is sodium stearate, the initiator is sodium persulfate, the buffer is sodium allyl sulfonate, and the molecular weight regulator is n-hexane; the dosage ratio of prepolymer, emulsifier, initiator, buffer and molecular weight regulator is 1500L:50-80g:140-150g:50-100g:200-300g.

7. The method for preparing a perfluorosulfonic acid resin dispersion suitable for preparing a proton exchange membrane according to claim 1, characterized in that: In step S2, the vacuum drying temperature is 70-80°C, and the vacuum drying time is 10-12h; in step S3, the organic solvent is water, 45%wt of n-propanol and 2-5%wt of ethanol mixed in a mass ratio of 10:1:0.5-1; the reaction temperature is 140-150°C, the reaction time is 12-15h, and the reaction pressure is 1-1.2MPa.

8. A perfluorosulfonic acid resin dispersion suitable for preparing a proton exchange membrane, characterized in that: The perfluorosulfonic acid resin dispersion suitable for preparing a proton exchange membrane is prepared by the method for preparing the perfluorosulfonic acid resin dispersion suitable for preparing a proton exchange membrane as described in any one of claims 1 to 7.

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