Preparation method and device of perfluorinated sulfonic acid resin dispersion liquid

Abstract

The invention discloses a preparation method and device of perfluorinated sulfonic acid resin dispersion liquid, and the method comprises the following steps: 1) in an inert atmosphere, mixing perfluorinated sulfonic acid resin and a first solvent under heating and pressure control conditions, and carrying out resin dispersion; wherein the pressure in the dispersing process is controlled in a range of 1.0 MPa (g) to 8.0 MPa (g); 2) after the resin is dispersed, cooling the material liquid to a certain temperature, adding a second solvent, mixing, and cooling; (3) cooling the feed liquid in the system, filtering, concentrating and extracting part of the solvent to obtain the perfluorosulfonic acid resin dispersion liquid; in the step 1), the first solvent is a mixed solvent of an alcohol compound and water; in the step 2), the second solvent is an alcohol compound. The resin content, solvent composition and viscosity of the perfluorosulfonic acid resin dispersion liquid are controllable, and the perfluorosulfonic acid resin dispersion liquid is used for preparing the proton exchange membrane and is smooth in coating, uniform in membrane formation and high in membrane proton conductivity.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a method and a device for preparing a perfluorosulfonic acid resin dispersion. Background Art

[0002] Hydrogen energy is regarded as the clean energy with the greatest development potential in the 21st century, and hydrogen fuel cell (Proton Exchange Membrane Fuel Cell, PEMFC) technology is considered to be the preferred solution for humans to use hydrogen energy to solve the future energy crisis. So far, most energy conversions are achieved through thermal engine processes. Thermal engine processes are limited by the Carnot cycle, which not only has low conversion efficiency, causing serious energy waste, but also pollutes the environment. Hydrogen fuel cells, as an electrochemical power generation device, directly convert chemical energy into electrical energy in an electrochemical way. Because they do not go through the thermal engine process, hydrogen fuel cells are not limited by the Carnot cycle, and have the advantages of high specific power, high energy efficiency, low operating temperature, and fast start-up speed, making them particularly suitable for use as power batteries. The combustion product of hydrogen fuel cells is water, and they do not emit carbon dioxide, nitrogen oxides or sulfur oxides, making them environmentally friendly.

[0003] As the core component of hydrogen fuel cells, proton exchange membrane (PEM) plays a dual role as electrolyte and diaphragm, and is the most important factor in determining battery performance and service life. Most proton exchange membranes used in hydrogen fuel cells are perfluorosulfonic acid proton exchange membranes, with DuPont's Nafion series membranes and Gore's Gore-Select series membranes being the most representative. They have the advantages of good mechanical properties, super strong cation selective permeability, chemical corrosion resistance, and high temperature resistance. The main raw material for preparing perfluorosulfonic acid proton exchange membranes is perfluorosulfonic acid resin, such as DuPont's Nafion series resin, which is obtained by polymerization of tetrafluoroethylene and perfluoro(4-methyl-3,6-dioxa-7-octene)sulfonyl fluoride followed by hydrolysis and acidification. The preparation process is as follows:

[0004]

[0005] There are two main preparation processes for perfluorosulfonic acid proton exchange membranes: melt extrusion and solution. The melt extrusion method uses perfluorosulfonyl fluoride resin as raw material, heats it to a molten state on processing equipment, and then extrudes it into a film. The membrane is then hydrolyzed and acidified to obtain a perfluorosulfonic acid proton exchange membrane. The solution method is to disperse the perfluorosulfonic acid resin in a solvent to obtain a dispersion, then cast the resin dispersion onto a mold and remove the solvent to form a membrane. Early proton exchange membranes produced by DuPont, such as Nafion TM N-117, Nafion TM N-115、Nafion TMN-112, Nafion TM N-1135, etc. are all manufactured by the melt extrusion method. This type of membrane is a homogeneous membrane with a relatively thick thickness and is mainly applied to the fields of hydrogen production by electrolyzing water and energy storage of liquid flow batteries. In order to significantly reduce the thickness of the proton exchange membrane without affecting the mechanical strength, improve the membrane performance while reducing the cost, Gore Company developed the Gore-Select series of e-PTFE reinforced membranes by combining perfluorosulfonic acid resin with expanded polytetrafluoroethylene (e-PTFE). Currently, the proton exchange membranes used in commercial hydrogen fuel cells are basically such e-PTFE reinforced membranes.

[0006] The film-forming process of the melt extrusion method is mainly used for the preparation of homogeneous membranes. The solution film-forming process can be used for the preparation of both homogeneous membranes and e-PTFE reinforced membranes. For example, a homogeneous membrane can be obtained by casting a perfluorosulfonic acid resin dispersion onto a mold, and an e-PTFE reinforced membrane can be obtained by casting or impregnating a perfluorosulfonic acid resin dispersion onto expanded polytetrafluoroethylene.

[0007] Through the study of the microstructure, it is found that the perfluorosulfonic acid resin is arranged in a regular layered structure in the proton exchange membrane, which is beneficial to the aggregation of sulfonate groups to form ion channels, thereby obtaining high proton conductivity. When preparing a perfluorosulfonic acid proton exchange membrane by the solution film-forming method, the preparation process and membrane performance are greatly affected by the properties of the perfluorosulfonic acid resin dispersion, such as resin content, solvent composition, viscosity, etc. A higher resin content can enable the resin to pre-self-assemble into aggregates in the dispersion, which is beneficial to the formation of good ion channels after film formation and obtaining high proton conductivity. A suitable solvent composition, for example, a certain proportion of alcohol and water mixed, is beneficial to obtaining a stable dispersion with a high resin content. A suitable viscosity is beneficial to the uniform coating of the dispersion to form a film.

[0008] The preparation of the perfluorosulfonic acid resin dispersion needs to meet the following conditions: ① The heating temperature needs to be higher than the glass transition temperature of the resin, generally not lower than 200 °C, so that the resin has fluidity; ② The solubility parameter of the selected solvent is close to the solubility parameter of the polytetrafluoroethylene main chain of the resin, and the dielectric constant is moderate, which is beneficial to the dispersion of the resin and its pre-self-assembly into aggregates. The solvents reported in the literature for the perfluorosulfonic acid resin dispersion are generally mixtures of organic solvents and water. Organic solvents include alcohols, tetrahydrofuran, N, N-dimethylformamide, etc. Low-boiling alcohols such as methanol, ethanol, n-propanol, and isopropanol, mixed with a certain proportion of water, are preferred solvents for the preparation of the dispersion due to their solubility parameters being close to the solubility parameter of the polytetrafluoroethylene main chain of the perfluorosulfonic acid resin and their moderate dielectric constants.

[0009] The preparation of perfluorosulfonic acid resin dispersion requires a high temperature above 200 °C. Alcohol solvents are prone to dehydration to form ethers, alkenes, or carbon-carbon bond cleavage and isomerization to form other by-products, making the solvent composition complex. If there are multiple organic solvents in the dispersion, due to different boiling points and different evaporation rates, it is difficult to coat and form a film. The change in the solvent composition will also change the solubility parameter and dielectric constant, thus affecting the stability of the dispersion and making the resin prone to sedimentation and precipitation. In addition, the resin content, solvent composition, and the temperature and pressure during the preparation process of the dispersion will all affect the viscosity of the dispersion. If the viscosity of the dispersion is too high or too low, it will lead to uneven coating and film formation, and the proton conductivity of the obtained proton exchange membrane is low. The existing preparation methods of perfluorosulfonic acid resin dispersion cannot well control the resin content, solvent composition, and viscosity of the dispersion. For example, in the DuPont patent WO2008 / 082496A1, the perfluorosulfonic acid resin dispersion obtained by the disclosed preparation method contains multiple organic solvents such as n-propanol, isopropanol, and ethanol, and the viscosity cannot be controlled. Summary of the Invention

[0010] In order to improve the deficiencies of the prior art, the present invention provides a preparation method and device for perfluorosulfonic acid resin dispersion. The method and device can well control the viscosity of the dispersion. Further, the resin content, solvent composition, and viscosity of the dispersion can be well controlled simultaneously. The obtained dispersion is used to prepare a proton exchange membrane, with smooth coating, uniform film formation, and high proton conductivity of the membrane.

[0011] The technical solution adopted by the present invention is as follows:

[0012] A preparation method of perfluorosulfonic acid resin dispersion, the preparation method includes the following steps:

[0013] 1) Under an inert atmosphere, perfluorosulfonic acid resin and a first solvent are mixed under heating and pressure control conditions for resin dispersion; wherein, the pressure during the dispersion process is controlled within the range of 1.0 MPa(g)-8.0 MPa(g);

[0014] 2) After the resin dispersion is completed, the liquid material is cooled to a certain temperature, a second solvent is added and mixed, and then cooled;

[0015] 3) After the liquid material in the system is cooled, it is filtered, concentrated, and part of the solvent is removed to obtain the perfluorosulfonic acid resin dispersion;

[0016] In step 1), the first solvent is a mixed solvent of an alcohol compound and water;

[0017] In step 2), the second solvent is an alcohol compound.

[0018] According to the present invention, in step 1), the addition amount of the perfluorosulfonic acid resin is not higher than 15 wt% of the total feed amount of the perfluorosulfonic acid resin and the first solvent, and preferably is 5 wt% - 10 wt%.

[0019] According to the present invention, in step 1), the alcohol compound in the first solvent is selected from saturated monohydric alcohols that are miscible with water. For example, the alcohol compound is selected from at least one of methanol, ethanol, n-propanol, and isopropanol.

[0020] According to the present invention, in step 1), the mass ratio of the alcohol compound to water in the first solvent is 0.2:1 - 2.0:1, and preferably is 0.5:1 - 1.5:1.

[0021] According to the present invention, in step 1), the inert atmosphere refers to a nitrogen atmosphere or an argon atmosphere, and preferably is high-purity nitrogen.

[0022] According to the present invention, in step 1), the heating temperature is not lower than 200 °C, and preferably is 200 °C - 250 °C.

[0023] According to the present invention, step 1) is carried out in a reaction kettle, and the temperature is achieved by heating the reaction kettle through an oil bath.

[0024] According to the present invention, step 1) is carried out in a reaction kettle. The pressure of 1.0 MPa(g) - 8.0 MPa(g) is controlled by a pressure control valve. When the pressure in the kettle is higher than a certain value, the gas release pressure control valve opens to discharge part of the gas. When the pressure in the kettle is lower than a certain value, the nitrogen supply pressure control valve opens to supply part of the nitrogen. It is found that through pressure control, the viscosity of the dispersion can be well controlled within the required range, so as to better achieve coating and film formation during the preparation of the proton exchange membrane.

[0025] According to the present invention, in step 1), the mixing time is not particularly limited as long as the perfluorosulfonic acid resin can be dispersed in the first solvent. For example, it is not less than 1.0 hour.

[0026] According to the present invention, in step 2), "lowering to a certain temperature" means lowering to below the boiling point of the second solvent. For example, lowering to below 100 °C and not lower than 40 °C. It is found that adding the second solvent at a certain temperature is more conducive to controlling the viscosity of the resulting dispersion.

[0027] According to the present invention, in step 2), the alcohol compound in the second solvent is selected from saturated monohydric alcohols that are miscible with water, such as at least one of methanol, ethanol, n-propanol, or isopropanol.

[0028] According to the present invention, in step 2), the addition amount of the second solvent is more than 100 wt% of the water feed amount of the first solvent, for example, more than 150 wt%.

[0029] According to the present invention, in step 2), a second solvent is added and mixed, and the mixture is cooled to room temperature.

[0030] According to the present invention, in step 2), the mixing time is not particularly limited as long as the uniformity of the perfluorosulfonic acid resin dispersion can be ensured. For example, the mixing time is not less than 5 min, and for another example, it is not less than 10 min.

[0031] According to the present invention, in step 3), the filtration is carried out in a filter, and the filtration means that the liquid in the stirring kettle is filtered through the filter, and then the filtrate is transferred to the bottom of the rectification column; wherein, the stirring kettle is used to add the second solvent in this device.

[0032] According to the present invention, in step 3), the concentration is carried out in a rectification column. The present invention creatively proposes a method for concentrating the dispersion by using a rectification column. By using this method, problems such as uncontrollable viscosity, components and content of the dispersion when using a rotary evaporation method can be avoided, and simultaneous control of the viscosity, components and content of the dispersion is achieved.

[0033] According to the present invention, in step 3), the concentration is a reduced-pressure concentration, and the concentration temperature is not higher than 60 °C. Based on the solvent type and the content requirements of the components in the dispersion, the number of theoretical plates is set to be 10 - 26, for example, 20, the pressure is 5 KPa(a) - 8 KPa(a), the vaporization temperature at the bottom of the column is 26 °C - 34 °C, the condensation temperature at the top of the column is 0 °C - 10 °C, and the reflux ratio is 3 - 5.

[0034] For example, taking the composition of the dispersion as perfluorosulfonic acid resin, propanol and water, the operating parameters of the rectification column are: the number of theoretical plates is 10 - 26, for example, 20, the pressure is 5 KPa(a) - 8 KPa(a), the vaporization temperature at the bottom of the column is 26 °C - 34 °C, the condensation temperature at the top of the column is 0 °C - 10 °C, and the reflux ratio is 3 - 5.

[0035] In the present invention, MPa(g) is the gauge pressure and MPa(a) is the absolute pressure.

[0036] According to the present invention, in step 3), the solvent is taken out at the top of the rectification column, and the amount of the solvent taken out can be set according to the resin content target of the dispersion. Exemplarily, the amount of the solvent taken out is more than 100 wt% of the resin feed amount, for example, more than 500 wt%, preferably 500 - 2300 wt%, and more preferably 1600 - 2000 wt%.

[0037] According to the present invention, in step 3), the perfluorosulfonic acid resin dispersion is taken out from the bottom of the rectification column.

[0038] According to the present invention, in step 3), in the perfluorosulfonic acid resin dispersion, the content of the perfluorosulfonic acid resin can be controlled by controlling the solvent withdrawal amount, for example, it is 20-25%, and exemplarily it is 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, 23%, 23.5%, 24%, 24.5% or 25 wt%.

[0039] According to the present invention, in step 3), the solvent in the perfluorosulfonic acid resin dispersion is an alcohol compound and water, wherein the mass ratio of the alcohol compound to water is 1.2:1 - 1.4:1, more preferably 1.3:1. Additionally, the content of other organic volatiles other than alcohols is not higher than 0.1 wt%. Among them, the other organic volatiles include diethyl ether.

[0040] According to the present invention, in step 3), the dynamic viscosity of the perfluorosulfonic acid resin dispersion is 40 cP - 100 cP, more preferably 60 cP - 80 cP.

[0041] The present invention also provides a device for implementing the preparation method of the above perfluorosulfonic acid resin dispersion, and the device includes a reaction kettle and a stirring kettle connected in sequence;

[0042] Among them, the reaction kettle is used for mixing perfluorosulfonic acid resin and a first solvent under heating and pressure control conditions for resin dispersion; the pressure in the reaction kettle is controlled within the range of 1.0 MPa(g) - 8.0 MPa(g);

[0043] The stirring kettle is used for mixing the dispersion in the reaction kettle with a second solvent.

[0044] According to the present invention, the device further includes a rectification column arranged behind the stirring kettle, and the rectification column is used for concentration.

[0045] According to the present invention, a filter is also arranged between the stirring kettle and the rectification column, and the filter is used for filtering the mixture in the stirring kettle.

[0046] In the present invention, the reaction kettle is used for the dispersion of perfluorosulfonic acid resin in the first solvent, the stirring kettle is used for supplementing the second solvent, the filter is used for filtering out insoluble impurities, and the rectification column is used for the vacuum concentration of the dispersion.

[0047] According to the present invention, the outer layer of the reaction kettle is provided with a reaction kettle jacket; a thermometer is arranged inside the reaction kettle; a stirring paddle is arranged at the upper part of the reaction kettle.

[0048] According to the present invention, the upper part of the reaction kettle is connected to a nitrogen pipeline, and a nitrogen supplementary pressure control valve, a pressure gauge and a gas release pressure control valve are arranged on the nitrogen pipeline.

[0049] According to the present invention, the reaction kettle is connected to the stirring kettle through a pipeline.

[0050] According to the present invention, a jacket is provided on the outer layer of the stirring kettle; a thermometer is provided inside the stirring kettle; and a stirring paddle is provided on the upper part of the stirring kettle.

[0051] According to the present invention, the stirring kettle is connected to a filter through a pipeline, and a pump is further provided between the stirring kettle and the filter.

[0052] According to the present invention, thermometers are provided at both the bottom and the top of the rectifying column.

[0053] According to the present invention, the top of the rectifying column is further connected to a condenser, and the condenser is connected to a reflux ratio controller; the reflux ratio controller is further connected to the rectifying column.

[0054] According to the present invention, a pressure gauge and a vacuum pump are provided above the condenser.

[0055] According to the present invention, the condenser is further connected to a receiving flask.

[0056] According to the present invention, the lower part of the receiving flask is connected to an electronic balance.

[0057] Advantages of the present invention:

[0058] (1) The present invention selects a mixed solvent of an alcohol compound and water in a suitable proportion as the first solvent, so that the solubility parameter of the first solvent is close to the solubility parameter of the polytetrafluoroethylene main chain of the perfluorosulfonic acid resin, and by controlling the feeding ratio of the resin, it can ensure that the resin is thoroughly dispersed; (2) The resin dispersion in the present invention is completed in a reaction kettle. The dispersion temperature can be accurately controlled by oil bath heating, and the gas is discharged and nitrogen is supplemented through a pressure control valve, so that the dispersion pressure can be accurately controlled while under nitrogen protection; (3) In the process of cooling in the present invention, the second solvent is added in time to prevent the resin from settling and precipitating; (4) Through vacuum concentration in the rectifying column in the present invention, part of the solvent (including alcohol compounds, water and other organic volatiles generated during the dispersion process) is taken out, and the resin content and solvent composition of the dispersion can be accurately regulated; (5) By accurately controlling the temperature, pressure and dispersion time of the resin dispersion process in the reaction kettle, and accurately controlling the concentration temperature, resin content and solvent composition of the dispersion through vacuum concentration in the rectifying column, the viscosity of the dispersion can be controlled; (6) In the perfluorosulfonic acid resin dispersion of the present invention, the resin content, solvent composition and viscosity are controllable. When used for the preparation of a proton exchange membrane, the coating is smooth, the film formation is uniform, and the proton conductivity of the film is high. Description of the Drawings

[0059] Figure 1 It is a process flow schematic diagram of the perfluorosulfonic acid resin dispersion of the present invention.

[0060] Figure 2This is a schematic diagram of the preparation device for the perfluorosulfonic acid resin dispersion of the present invention.

[0061] Among them, Figure 2 The labels in Figure 2 are as follows: 1. Reaction kettle, 2. Reaction kettle jacket, 3. Thermometer, 4. Stirring paddle, 5. Nitrogen supplement pressure control valve, 6. Pressure gauge, 7. Gas release pressure control valve, 8. Bottom pipe, 9. Stirring kettle, 10. Stirring kettle jacket, 11. Stirring paddle, 12. Thermometer, 13. Pump, 14. Filter, 15. Oil bath, 16. Distillation column kettle, 17. Thermometer, 18. Distillation column, 19. Thermometer, 20. Condenser, 21. Reflux ratio controller, 22. Receiving bottle, 23. Electronic balance, 24. Pressure gauge, 25. Vacuum pump. Specific embodiments

[0062] The technical solution of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate and explain the present invention by way of example, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0063] Unless otherwise specified, the raw materials and reagents used in the following embodiments are all commercially available products, or can be prepared by known methods.

[0064] The preparation device for the perfluorosulfonic acid resin dispersion of the present invention is as follows:

[0065] As Figure 2 shown, the device includes a reaction kettle 1, a stirring kettle 9, a filter 14 and a distillation column 18 connected in sequence.

[0066] The reaction kettle is used for the dispersion of perfluorosulfonic acid resin in the first solvent, the stirring kettle is used for adding the second solvent, the filter is used for filtering out insoluble impurities, and the distillation column is used for the vacuum concentration of the dispersion.

[0067] The outer layer of the reaction kettle 1 is provided with a reaction kettle jacket 2; a thermometer 3 is provided inside the reaction kettle; a stirring paddle 4 is provided above the reaction kettle.

[0068] The upper part of the reaction kettle 1 is connected to a nitrogen pipeline, and a nitrogen supplement pressure control valve 4, a pressure gauge 6 and a gas release pressure control valve 7 are provided on the nitrogen pipeline.

[0069] The reaction kettle 1 is connected to the stirring kettle 9 through a pipeline. The bottom of the reaction kettle 1 is inserted with a pipeline, that is, a bottom pipe 8.

[0070] The outer layer of the stirring kettle 9 is provided with a stirring kettle jacket 10; a thermometer 12 is provided inside the stirring kettle; a stirring paddle 11 is provided above the stirring kettle.

[0071] The stirring kettle 9 is connected to the filter 14 through a pipeline, and a pump 13 is also provided between the stirring kettle and the filter.

[0072] The bottom of the distillation column 18 (i.e., the bottom of the distillation column 16) is provided with a thermometer 17, and the top of the column is provided with a thermometer 19.

[0073] The top of the distillation column 18 is also connected to a condenser 20, and the condenser 20 is connected to a reflux ratio controller 21; the reflux ratio controller is also connected to the distillation column 18.

[0074] Above the condenser, a pressure gauge 24 and a vacuum pump 25 are provided.

[0075] The condenser is also connected to a receiving flask 22.

[0076] Below the receiving flask, it is connected to an electronic balance 23.

[0077] Exemplarily, in the following examples and comparative examples, the EW1050 type perfluorosulfonic acid resin with an ion exchange equivalent of 1050 g / mol and the EW850 type resin with an ion exchange equivalent of 850 g / mol are used as raw materials to prepare the dispersion liquid. The method and device of the present invention can be used for but are not limited to the preparation of the dispersion liquids of the above two types of perfluorosulfonic acid resins.

[0078] Figure 1 It is a process flow schematic diagram of the method for preparing the perfluorosulfonic acid resin dispersion liquid of the present invention.

[0079] As Figure 1 shown, the perfluorosulfonic acid resin and the first solvent are added into the reaction kettle, and under nitrogen protection, the temperature and pressure are controlled to disperse the resin. After the dispersion is completed, the liquid in the autoclave is transferred into the stirring kettle, cooled to below the boiling point of the second solvent, the second solvent is supplemented, the temperature is controlled and stirred, and then cooled to room temperature. The liquid in the stirring kettle is filtered, and the filtrate is transferred into the distillation column for vacuum concentration, and a certain weight of the solvent is collected to obtain the dispersion liquid.

[0080] Example 1

[0081] Add EW1050 perfluorosulfonic acid resin, ethanol, and water into a high-pressure reactor. The feeding ratio of ethanol to water is 1:1 by weight, and the addition amount of perfluorosulfonic acid resin is 7 wt% of the total feeding amount of perfluorosulfonic acid resin and the first solvent. Connect the high-pressure reactor to a high-purity nitrogen gas cylinder, set the pressure threshold after the nitrogen replenishment pressure control valve to 5.9 MPa(g), and set the pressure threshold before the gas discharge pressure control valve to 6.1 MPa(g). Raise the temperature inside the high-pressure reactor to 250 °C, control the temperature and stir for 3 hours, and then transfer the liquid material inside the high-pressure reactor to a stirring kettle. Cool the liquid material in the stirring kettle to 70 °C, add n-propanol (the addition amount of n-propanol is 200 wt% of the water feeding amount), control the temperature of the liquid material in the stirring kettle at 60 °C - 70 °C, stir for 30 minutes, and then cool to room temperature. Filter the liquid material in the stirring kettle through a filter, and transfer the filtrate to the bottom of a distillation column. The theoretical number of trays of the distillation column is 20, the pressure is 6 KPa(a), the vaporization temperature at the bottom of the column is 29 °C, the condensation temperature at the top of the column is 0 °C, the reflux distribution ratio is 5, concentrate under reduced pressure to extract the solvent, and the solvent extraction amount is 1874.1 wt% of the resin feeding amount, obtaining a perfluorosulfonic acid resin dispersion. The weight of the perfluorosulfonic acid resin dispersion is 454.5 wt% of the resin feeding amount. The resin content in the dispersion is 22.0 wt%, the n-propanol content is 43.1 wt%, the ethanol content is 1.0 wt%, the water content is 33.9 wt%, and the viscosity is 61 cP.

[0082] Use the obtained perfluorosulfonic acid resin dispersion for the preparation of a proton exchange membrane. The coating is smooth and the film formation is uniform. The proton conductivity of the obtained membrane is 40.2 mS / cm (100 mv).

[0083] Example 2

[0084] Add EW850 perfluorosulfonic acid resin, ethanol, and water into a high-pressure reactor. The feeding ratio of ethanol to water is 1:1 by weight, and the addition amount of perfluorosulfonic acid resin is 7 wt% of the total feeding amount of perfluorosulfonic acid resin and the first solvent. Connect the high-pressure reactor to a high-purity nitrogen gas cylinder. Set the pressure threshold behind the nitrogen replenishment pressure control valve to 5.9 MPa(g), and set the pressure threshold in front of the gas release pressure control valve to 6.1 MPa(g). Raise the temperature inside the high-pressure reactor to 250 °C, control the temperature and stir for 3 hours, and then transfer the liquid material in the high-pressure kettle to a stirring kettle. Cool the liquid material in the stirring kettle to 70 °C, add n-propanol, and the addition amount of n-propanol is 200 wt% of the water feeding amount. Control the temperature of the liquid material in the stirring kettle at 60 °C - 70 °C, stir for 30 minutes, and then cool to room temperature. Filter the liquid material in the stirring kettle through a filter, and transfer the filtrate to the bottom of the distillation column. The theoretical number of trays of the distillation column is 20, the pressure is 6 KPa(a), the vaporization temperature at the bottom of the column is 29 °C, the condensation temperature at the top of the column is 0 °C, the reflux distribution ratio is 5, concentrate under reduced pressure to extract the solvent, and the solvent extraction amount is 1874.1 wt% of the resin feeding amount, obtaining a perfluorosulfonic acid resin dispersion. The weight of the perfluorosulfonic acid resin dispersion is 454.5 wt% of the resin feeding amount. The resin content in the dispersion is 22.0 wt%, the n-propanol content is 43.1 wt%, the ethanol content is 1.0 wt%, the water content is 33.9 wt%, and the viscosity is 65 cP.

[0085] Use the obtained perfluorosulfonic acid resin dispersion for the preparation of a proton exchange membrane. The coating is smooth and the film formation is uniform. The proton conductivity of the obtained membrane is 64.5 mS / cm (100 mv).

[0086] Comparative Example 1

[0087] Add EW1050 or EW850 perfluorosulfonic acid resin, n-propanol, and water into a high-pressure reactor. The feeding ratio of n-propanol to water is 1.3:1 by weight, and the addition amount of perfluorosulfonic acid resin is 20 wt% of the total feeding amount of perfluorosulfonic acid resin and the first solvent. Connect the high-pressure reactor to a high-purity nitrogen gas cylinder. Set the pressure threshold behind the nitrogen replenishment pressure control valve to 5.9 MPa(g), and set the pressure threshold in front of the gas release pressure control valve to 6.1 MPa(g). Raise the temperature inside the high-pressure reactor to 250 °C, control the temperature and stir for 3 hours, but the resin cannot be completely dissolved and dispersed, and a large amount of jelly-like substances remain.

[0088] Comparative Example 2

[0089] Add EW1050 or EW850 perfluorosulfonic acid resin, ethanol, and water into a high-pressure reactor. The feeding ratio of ethanol to water is 1:1 by weight, and the addition amount of perfluorosulfonic acid resin is 7 wt% of the total feeding amount of perfluorosulfonic acid resin and the first solvent. Connect the high-pressure reactor to a high-purity nitrogen gas cylinder, set the pressure threshold after the nitrogen replenishment pressure control valve to 5.9 MPa(g), and set the pressure threshold before the gas release pressure control valve to 6.1 MPa(g). Raise the temperature inside the high-pressure reactor to 250 °C, control the temperature and stir for 3 hours, then transfer it to a stirring kettle, cool it to 20 °C, and a large amount of jelly-like substances will settle out.

[0090] Comparative Example 3

[0091] Add EW1050 perfluorosulfonic acid resin, ethanol, and water into a high-pressure reactor. The feeding ratio of ethanol to water is 1:1 by weight, and the addition amount of perfluorosulfonic acid resin is 7 wt% of the total feeding amount of perfluorosulfonic acid resin and the first solvent. Replace the gas inside the high-pressure reactor with high-purity nitrogen. Raise the temperature inside the high-pressure reactor to 250 °C, control the temperature and stir for 3 hours. During the dispersion process, the pressure inside the kettle rises to 6.9 MPa(g). Transfer the liquid material inside the high-pressure kettle to a stirring kettle, cool it to 70 °C, add n-propanol, and the addition amount of n-propanol is 200 wt% of the water feeding amount. Control the temperature of the liquid material inside the stirring kettle at 60 °C - 70 °C, stir for 30 minutes, and then cool it to room temperature. Filter the liquid material inside the stirring kettle through a filter, and transfer the filtrate to the bottom of a distillation column. The theoretical number of trays of the distillation column is 20, the pressure is 6 KPa(a), the vaporization temperature at the bottom of the column is 29 °C, the condensation temperature at the top of the column is 0 °C, the reflux distribution ratio is 5, concentrate under reduced pressure to extract the solvent, and the solvent extraction amount is 1874.1 wt% of the resin feeding amount, obtaining a perfluorosulfonic acid resin dispersion. The content of the perfluorosulfonic acid resin dispersion is 454.5 wt% of the resin feeding amount. The resin content in the dispersion is 22.0 wt%, the n-propanol content is 43.1 wt%, the ethanol content is 1.0 wt%, the water content is 33.9 wt%, and the viscosity is 177 cP.

[0092] Use the obtained perfluorosulfonic acid resin dispersion for the preparation of a proton exchange membrane. The feeding of the coating line is blocked, the coating liquid cannot form a uniform film, and there are obviously a large number of particles in the obtained membrane. The proton conductivity of the membrane is 21.6 mS / cm (100 mv).

[0093] Comparative Example 4

[0094] Add EW850 perfluorosulfonic acid resin, ethanol, and water into a high-pressure reactor. The feeding ratio of ethanol to water is 1:1 by weight, and the addition amount of perfluorosulfonic acid resin is 7 wt% of the total feeding amount of perfluorosulfonic acid resin and the first solvent. Replace the gas in the high-pressure reactor with high-purity nitrogen. Raise the temperature in the high-pressure reactor to 250 °C, control the temperature and stir for 3 hours. During the dispersion process, the pressure in the reactor rises to 7.2 MPa(g). Transfer the liquid in the high-pressure reactor to a stirring kettle, cool down to 70 °C, add n-propanol, and the addition amount of n-propanol is 200 wt% of the water feeding amount. Control the temperature of the liquid in the stirring kettle at 60 °C - 70 °C, stir for 30 minutes, and then cool down to room temperature. Filter the liquid in the stirring kettle through a filter, and transfer the filtrate to the bottom of a distillation column. The theoretical number of plates of the distillation column is 20, the pressure is 6 KPa(a), the vaporization temperature at the bottom of the column is 29 °C, the condensation temperature at the top of the column is 0 °C, the reflux distribution ratio is 5, and the solvent is concentrated under reduced pressure and the solvent extraction amount is 1874.1 wt% of the resin feeding amount, obtaining a perfluorosulfonic acid resin dispersion. The weight of the perfluorosulfonic acid resin dispersion is 454.5 wt% of the resin feeding amount. The resin content in the dispersion is 22.0 wt%, the n-propanol content is 43.1 wt%, the ethanol content is 1.0 wt%, the water content is 33.9 wt%, and the viscosity is 201 cP.

[0095] Use the obtained perfluorosulfonic acid resin dispersion for the preparation of a proton exchange membrane. There is difficulty in feeding the coating line, the coating liquid cannot form a uniform film, and there are obviously a large number of particles in the obtained membrane. The proton conductivity of the membrane is 26.9 mS / cm (100 mv).

[0096] Comparative Example 5

[0097] Add EW1050 perfluorosulfonic acid resin, ethanol, and water into a high-pressure reactor. The feeding ratio of ethanol to water is 1:1 by weight, and the addition amount of perfluorosulfonic acid resin is 7 wt% of the total feeding amount of perfluorosulfonic acid resin and the first solvent. Connect the high-pressure reactor to a high-purity nitrogen cylinder, set the pressure threshold value behind the nitrogen supplementary pressure control valve to 5.9 MPa(g), and set the pressure threshold value in front of the gas release pressure control valve to 6.1 MPa(g). Raise the temperature in the high-pressure reactor to 250 °C, control the temperature and stir for 3 hours, and then transfer the liquid in the high-pressure reactor to a stirring kettle. Cool down the liquid in the stirring kettle to 70 °C, add n-propanol, and the addition amount of n-propanol is 200 wt% of the water feeding amount. Control the temperature of the liquid in the stirring kettle at 60 °C - 70 °C, stir for 30 minutes, and then cool down to room temperature. Filter the liquid in the stirring kettle through a filter, and transfer the filtrate to a rotary evaporator for concentration under reduced pressure. The concentration temperature is 70 °C, and the obtained dispersion after concentration is 440.5 wt% of the resin feeding amount. The resin content is 22.7 wt%, the n-propanol content is 44.3 wt%, the ethanol content is 1.9 wt%, and the water content is 31.1 wt%, and the viscosity is 270 cP.

[0098] The obtained perfluorosulfonic acid resin dispersion is used for the preparation of a proton exchange membrane. Due to the too high viscosity, the coating line is severely blocked and normal feeding cannot be carried out.

[0099] Example 3

[0100] The EW850 type perfluorosulfonic acid resin, ethanol, and water are added into a high-pressure reaction kettle. The feeding ratio of ethanol to water is 1:1 by weight, and the addition amount of the perfluorosulfonic acid resin is 7 wt% of the total feeding amount of the perfluorosulfonic acid resin and the first solvent. Connect the high-pressure reaction kettle to a high-purity nitrogen gas cylinder. Set the pressure threshold value after the nitrogen replenishment pressure control valve to 5.9 MPa(g), and set the pressure threshold value before the gas release pressure control valve to 6.1 MPa(g). Raise the temperature in the high-pressure reaction kettle to 250 °C, control the temperature and stir for 3 hours, and then transfer the liquid in the high-pressure kettle to a stirring kettle. Cool the liquid in the stirring kettle to 70 °C, add n-propanol, and the addition amount of n-propanol is 200 wt% of the water feeding amount. Control the temperature of the liquid in the stirring kettle at 60 °C - 70 °C and stir for 30 minutes, and then cool to room temperature. Filter the liquid in the stirring kettle through a filter, and transfer the filtrate to a rotary evaporator for concentration under reduced pressure. The concentration temperature is 70 °C, and the obtained dispersion after concentration is 465.1 wt% of the resin feeding amount, wherein the resin content is 21.5 wt%, the n-propanol content is 42.0 wt%, the ethanol content is 1.4 wt%, the water content is 35.1 wt%, and the viscosity is 305 cP.

[0101] The obtained perfluorosulfonic acid resin dispersion is used for the preparation of a proton exchange membrane. Due to the too high viscosity, the coating line is severely blocked and normal feeding cannot be carried out.

[0102] Example 4

[0103] The EW1050 type perfluorosulfonic acid resin, ethanol, and water are added into a high-pressure reaction kettle. The feeding ratio of ethanol to water is 1:1 by weight, and the addition amount of the perfluorosulfonic acid resin is 7 wt% of the total feeding amount of the perfluorosulfonic acid resin and the first solvent. Connect the high-pressure reaction kettle to a high-purity nitrogen gas cylinder. Set the pressure threshold value after the nitrogen replenishment pressure control valve to 5.9 MPa(g), and set the pressure threshold value before the gas release pressure control valve to 6.1 MPa(g). Raise the temperature in the high-pressure reaction kettle to above 200 °C, control the temperature and stir for 3 hours, and then transfer the liquid in the high-pressure kettle to a stirring kettle. Cool the liquid in the stirring kettle to 70 °C, add n-propanol, and the addition amount of n-propanol is 100 wt% of the water feeding amount. Control the temperature of the liquid in the stirring kettle at 60 °C - 70 °C and stir for 30 minutes, and then cool to room temperature. Filter the liquid in the stirring kettle through a filter. The obtained dispersion has a resin content of 5.4 wt%, an n-propanol content of 35.9 wt%, an ethanol content of 18.0 wt%, a water content of 33.5 wt%, and an ether content of 7.2 wt%, and the viscosity of the dispersion is 17 cP.

[0104] The obtained perfluorosulfonic acid resin dispersion was used for the preparation of a proton exchange membrane. However, due to the too low viscosity, the coating solution could not adhere to the skeleton membrane, and a complete membrane product could not be prepared.

[0105] Example 5

[0106] EW850 type perfluorosulfonic acid resin, ethanol, and water were added to a high-pressure reactor. The feeding ratio of ethanol to water was 1:1 by weight, and the addition amount of perfluorosulfonic acid resin was 7 wt% of the total feeding amount of perfluorosulfonic acid resin and the first solvent. The high-pressure reactor was connected to a high-purity nitrogen gas cylinder. The pressure threshold value behind the nitrogen replenishment pressure control valve was set to 5.9 MPa(g), and the pressure threshold value in front of the gas release pressure control valve was set to 6.1 MPa(g). The temperature in the high-pressure reactor was raised above 200 °C, and it was stirred for 3 hours while controlling the temperature. Then, the liquid in the high-pressure reactor was transferred to a stirring kettle. The temperature of the liquid in the stirring kettle was lowered to 70 °C, and n-propanol was added. The addition amount of n-propanol was 100 wt% of the feeding amount of water. The temperature of the liquid in the stirring kettle was controlled at 60 °C - 70 °C, and it was stirred for 30 minutes, and then cooled to room temperature. The liquid in the stirring kettle was filtered through a filter. The resin content of the obtained dispersion was 5.5 wt%, the n-propanol content was 36.5 wt%, the ethanol content was 16.6 wt%, the water content was 34.1 wt%, the ether content was 7.3 wt%, and the viscosity of the dispersion was 20 cP.

[0107] The obtained perfluorosulfonic acid resin dispersion was used for the preparation of a proton exchange membrane. However, due to the too low viscosity, the coating solution could not adhere to the skeleton membrane, and a complete membrane product could not be prepared.

[0108] The comparison results of the product performances obtained by the preparation processes of Examples 1 - 2 and Comparative Examples 1 - 8 are shown in Tables 1 and 2.

[0109] Table 1 Comparison Table of Product Performances of Examples 1, 3, 5 and Comparative Examples 1 - 3

[0110]

[0111]

[0112] Table 2 Comparison Table of Product Performances of Examples 2, 4, 6 and Comparative Examples 1 - 2, 4

[0113]

[0114]

[0115] As mentioned above, the embodiments of the present invention have been exemplarily described. However, the protection scope of the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a perfluorosulfonic acid resin dispersion, characterized in that, the method comprises the following steps: 1) Under an inert atmosphere, perfluorosulfonic acid resin and a first solvent are mixed under heating and pressure control conditions for resin dispersion; wherein, the pressure during the dispersion process is controlled within the range of 1.0 MPa(g) - 8.0 MPa(g); 2) After the resin dispersion is completed, the liquid material is cooled to a certain temperature, a second solvent is added and mixed, and then cooled; 3) After the liquid material in the system is cooled, it is filtered, concentrated, and a part of the solvent is recovered to obtain the perfluorosulfonic acid resin dispersion; In step 1), the first solvent is a mixed solvent of an alcohol compound and water; In step 2), the second solvent is an alcohol compound.

2. The method according to claim 1, characterized in that, in step 1), the addition amount of the perfluorosulfonic acid resin is not higher than 15 wt% of the total feed amount of the perfluorosulfonic acid resin and the first solvent.

3. The method according to claim 1 or 2, characterized in that, in step 1), the heating temperature is not lower than 200 °C. Preferably, in step 2), the cooling to a certain temperature means cooling to a temperature below the boiling point of the second solvent and not lower than 40 °C.

4. The method according to any one of claims 1 - 3, characterized in that, in step 2), the addition amount of the second solvent is more than 100 wt% of the water feed amount in the first solvent.

5. The method according to any one of claims 1 - 4, characterized in that, in step 3), the concentration is carried out in a distillation column; the amount of solvent recovered is more than 100 wt% of the water feed amount in the first solvent; the concentration temperature is not higher than 60 °C.

6. A device for implementing the method according to any one of claims 1 - 5, characterized in that, the device comprises a reaction kettle and a stirring kettle connected in sequence; wherein, the reaction kettle is used for mixing perfluorosulfonic acid resin and a first solvent under heating and pressure control conditions for resin dispersion; the pressure in the reaction kettle is controlled within the range of 1.0 MPa(g) - 8.0 MPa(g); the stirring kettle is used for mixing the dispersion in the reaction kettle with a second solvent.

7. The device according to claim 6, characterized in that, the upper part of the reaction kettle is connected to a nitrogen pipeline, and a nitrogen supplementary pressure control valve, a pressure gauge and a gas release pressure control valve are arranged on the nitrogen pipeline.

8. The device according to claim 6 or 7, characterized in that, the device further comprises a distillation column arranged behind the stirring kettle, and the distillation column is used for concentration.

9. The device according to claim 8, characterized in that, the top of the distillation column is further connected to a condenser, the condenser is connected to a reflux ratio controller; the reflux ratio controller is further connected to the distillation column.

10. The device according to claim 8 or 9, characterized in that, a filter is further arranged between the stirring kettle and the distillation column for filtering the mixture in the stirring kettle.

Images