Cation exchange membrane, its preparation method and application

Abstract

The application provides a cation exchange membrane and a preparation method and application thereof, and belongs to the technical field of cation exchange membranes.The method provided by the application is free of volatile organic compounds, toxic and harmful monomers or heavy metal components, and the raw material itself is environmentally friendly.The method is free of harmful gas emission and hazardous waste generation, and is environmentally friendly.The cation exchange membrane material prepared by the method is chemically stable, easy to recycle after being discarded, free of additive precipitation during use, and free of pollution to the treatment system.The water-soluble dispersion bonding medium adopted by the application forms rich and uniform connected pore structures in the cation exchange membrane after being washed by water, greatly reduces ion migration resistance, significantly alleviates membrane polarization, and improves ion exchange rate and energy utilization efficiency when used for separation.The method provided by the application is free of complex chemical reactions, harsh process conditions, and standardized operation steps, and is easy to realize large-scale continuous production.

Description

Technical Field

[0001] This invention relates to the field of cation exchange membrane technology, and in particular to a cation exchange membrane, its preparation method, and its application. Background Technology

[0002] Ion exchange membranes, as a core separation material with selective ion permeation, achieve the directional migration of specific ions through ion exchange groups fixed on the membrane surface. They are widely used in key fields such as electrodialysis desalination, industrial wastewater treatment, electrolytic hydrogen production, chlor-alkali industry, seawater desalination, and food and pharmaceutical purification. Currently, the mainstream preparation technologies for ion exchange membranes are mainly divided into two categories: homogeneous membranes and heterogeneous membranes. Traditional homogeneous membranes rely on highly polar organic solvents such as DMF and dichloromethane for material dissolution and blending, resulting in high VOC emissions, high wastewater treatment costs, and solvent residues that can damage the activity of ion exchange groups. Processes such as radiation grafting and chemical crosslinking have stringent conditions, narrow process windows, low industrialization efficiency, and scrap rates ≥10%, making it difficult to optimize performance through physical control. Traditional heterogeneous membranes are opaque films made by mixing and stretching non-polar ion exchange resins with polar binders such as PVC and polyvinyl chloride. Although it has good environmental friendliness, the process leads to resin particle agglomeration (particle size ≥200μm), forming obvious interfacial voids with the matrix. This causes disruption of ion conduction pathways, increased membrane resistance, and interfacial stress concentration, which can easily lead to brittle fracture. Increasing the proportion of binder reduces ion exchange capacity, while increasing the proportion of resin disrupts matrix continuity, making it impossible to balance uniformity and mechanical strength. Therefore, existing ion exchange membrane preparation methods struggle to simultaneously meet the combined requirements of "high performance and environmental friendliness." Summary of the Invention

[0003] The purpose of this invention is to provide a high-performance, environmentally friendly cation exchange membrane, its preparation method, and its application.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a method for preparing a cation exchange membrane, comprising:

[0006] The dispersant is mixed with a water-soluble dispersing and binding medium to obtain a dispersion base liquid;

[0007] Low-density polyethylene powder, functional ion exchange resin and the dispersion base liquid are mixed and homogenized to obtain a suspension; the functional ion exchange resin is a styrene-type cation exchange resin.

[0008] The suspension is defoamed to obtain a composite slurry;

[0009] The composite slurry is coated onto a mesh material and then subjected to a heating and curing process to obtain an ion exchange membrane.

[0010] The ion exchange membrane was sequentially washed with water to remove impurities and then activated to obtain a cation exchange membrane.

[0011] Preferably, the raw materials for preparing the cation exchange membrane, by mass percentage, include the following components: 30-50% low-density polyethylene powder; 20-40% functional ion exchange resin; 15-35% water-soluble dispersing and binding medium; and 1-5% dispersant.

[0012] Preferably, the water-soluble dispersion binder includes polyethylene glycol; the polyethylene glycol includes PEG-200, PEG-400, PEG-2000 or PEG-4000.

[0013] Preferably, the dispersant comprises one or more of isomeric alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and polyoxyethylene sorbitan monooleate.

[0014] Preferably, the particle size of the low-density polyethylene powder is ≤5μm.

[0015] Preferably, the homogenization pressure is 20~80MPa; the homogenization temperature is 50~80℃; the homogenization cycle is 5~6 times, and the homogenization time for each cycle is 10~35min.

[0016] Preferably, the mesh count of the mesh material is 50 to 300 meshes; the wire diameter of the mesh material is 0.1 to 0.3 mm.

[0017] Preferably, the coating method is high-pressure jet coating; the parameters of the high-pressure jet coating include: the material tank temperature is maintained at 5~80℃; the conveying device speed is set at 1~5m / min; the nozzle orifice diameter is 0.1~0.5mm; the jet pressure is 0.5~1.5MPa; the jet distance is 5~15cm; and the nozzle moving speed is 5~10cm / s.

[0018] Preferably, the heating and curing process includes: heating from room temperature to a first temperature at a first heating rate, and holding at the first temperature for a first time; then heating to a second temperature at a second heating rate, and holding at the second temperature for a second time; wherein the first heating rate is 5~10℃ / min; the first temperature is 50~90℃; the first holding time is 1~3h; the second heating rate is 5~10℃ / min; the second temperature is 105~140℃; and the second holding time is 3~6h.

[0019] The present invention also provides a cation exchange membrane prepared by the preparation method described in the above technical solution.

[0020] The present invention also provides the application of the cation exchange membrane described above as a separation material.

[0021] This invention provides a method for preparing a cation exchange membrane, comprising: mixing a dispersant with a water-soluble dispersion and binding medium to obtain a dispersion base liquid; mixing low-density polyethylene powder and a functional ion exchange resin with the dispersion base liquid and then homogenizing the mixture to obtain a suspension; wherein the functional ion exchange resin is a styrene-type cation exchange resin; degassing the suspension to obtain a composite slurry; coating the composite slurry onto a mesh material and then curing it at a high temperature to obtain an ion exchange membrane; and sequentially removing impurities and activating the ion exchange membrane to obtain a cation exchange membrane. This invention uses low-density polyethylene powder (LDPE powder) and ion exchange resin in a formulation. LDPE powder and styrene-type cation exchange resin have excellent compatibility, resulting in uniform dispersion of LDPE powder and ion exchange resin particles without significant phase separation. The prepared cation exchange membrane exhibits low resistance and uniformity. Furthermore, the formulation does not require complex chemical polymerization or functional group reactions, making the process economical. The method provided by this invention contains no volatile organic compounds (VOCs), toxic or harmful monomers, or heavy metals, and the raw materials are environmentally friendly. The entire preparation process produces no harmful gas emissions or hazardous waste, making it environmentally friendly. The cation exchange membrane material prepared by this invention is chemically stable, easily recyclable after disposal, and produces no additives during use, thus avoiding pollution of the treatment system. The degassing treatment of the suspension in this invention prevents the presence of bubbles from reducing the mechanical properties of the cation exchange membrane. The water-soluble dispersing and binding medium used in this invention, after being washed to remove impurities, forms a rich and uniform interconnected pore structure inside the ion exchange membrane, significantly reducing ion migration resistance, mitigating membrane polarization, and improving ion exchange rate and energy utilization efficiency. Activation in this invention enables the cation exchange membrane to have a high exchange capacity. The method provided by this invention involves no complex chemical reactions or demanding process conditions, has standardized operating steps, and is easily scalable for continuous production. Detailed Implementation

[0022] This invention provides a method for preparing a cation exchange membrane, comprising:

[0023] The dispersant is mixed with a water-soluble dispersing and binding medium to obtain a dispersion base liquid;

[0024] Low-density polyethylene powder, functional ion exchange resin and the dispersion base liquid are mixed and homogenized to obtain a suspension; the functional ion exchange resin is a styrene-type cation exchange resin.

[0025] The suspension is defoamed to obtain a composite slurry;

[0026] The composite slurry is coated onto a mesh material and then subjected to a heating and curing process to obtain an ion exchange membrane.

[0027] The ion exchange membrane was sequentially washed with water to remove impurities and then activated to obtain a cation exchange membrane.

[0028] In this invention, the raw materials for preparing the cation exchange membrane, by weight percentage, include the following components: 30-50% low-density polyethylene powder; 20-40% functional ion exchange resin; 15-35% water-soluble dispersing and binding medium; and 1-5% dispersant.

[0029] The raw material for preparing the cation exchange membrane of the present invention preferably comprises 30-50% low-density polyethylene powder by weight percentage. As one embodiment of the present invention, the weight percentage of the low-density polyethylene powder can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%.

[0030] In this invention, the particle size of the low-density polyethylene powder is preferably ≤5μm. The low-density polyethylene powder with the above-mentioned particle size used in this invention is a commercially available ultrafine low-density polyethylene powder, which is more conducive to compatibility with ion exchange resins to form a composite slurry without significant phase separation. This invention does not have a special limitation on the source of the low-density polyethylene powder; any conventional commercially available product can be used. In the embodiments of this invention, the low-density polyethylene powder is sourced from BASF, ExxonMobil, or Sinopec.

[0031] The raw materials for preparing the cation exchange membrane of the present invention preferably include 20-40% functional ion exchange resin by weight percentage. As one embodiment of the present invention, the weight percentage of the functional ion exchange resin can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%.

[0032] In this invention, the functional ion exchange resin is a styrene-type cation exchange resin, and the functional groups of the functional ion exchange resin are preferably sulfonic acid groups or carboxylic acid groups. In this invention, the degree of crosslinking of the functional ion exchange resin is preferably 2-6, more preferably 4-5; the particle size of the functional ion exchange resin is preferably 0.1-0.8 mm, more preferably 0.3-0.5 mm. In the embodiments of this invention, the functional ion exchange resin can be of type 001×7, D001, Amberlite IR-120, or Lewatit S10, and is a commercially available product from Lanxess Chemical (China) Co., Ltd., Dow Chemical, or Rohm and Haas. This invention utilizes the above-mentioned functional ion exchange resin, which has good compatibility with low-density polyethylene powder.

[0033] The raw materials for preparing the cation exchange membrane of the present invention preferably include 15-35% water-soluble dispersion binder by mass percentage. As one embodiment of the present invention, the mass percentage of the water-soluble dispersion binder may be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, or 35%.

[0034] In this invention, the water-soluble dispersion and binding medium preferably comprises polyethylene glycol, and the polyethylene glycol preferably comprises PEG-200, PEG-400, PEG-2000, or PEG-4000. In embodiments of this invention, the polyethylene glycol can be a commercially available product from Dow Chemical, BASF, or Sinopec. This invention utilizes a water-soluble dispersion and binding medium to form a rich and uniform interconnected pore structure inside the ion exchange membrane after water washing, significantly reducing ion migration resistance, significantly alleviating membrane polarization, and improving ion exchange rate and energy utilization efficiency.

[0035] The raw materials for preparing the cation exchange membrane of the present invention preferably include 1-5% dispersant by mass percentage. As one embodiment of the present invention, the mass percentage of the dispersant may be 1%, 2%, 2.5%, 3%, 4%, or 5%.

[0036] In this invention, the dispersant preferably comprises one or more of isomeric alcohol polyoxyethylene ethers, fatty alcohol polyoxyethylene ethers, alkylphenol polyoxyethylene ethers, and polyoxyethylene sorbitan monooleate. This invention utilizes dispersants to improve the dispersion stability of composite slurries.

[0037] This invention mixes a dispersant with a water-soluble dispersing and binding medium to obtain a dispersion base liquid.

[0038] In this invention, the mixing of the dispersant and the water-soluble dispersion and binding medium is preferably carried out under stirring. The stirring speed is preferably 600-1200 rpm, more preferably 700-1000 rpm; the stirring time is preferably 20-180 min, more preferably 50-150 min. This invention enables the rapid formation of a uniform dispersion base liquid through stirring. This invention does not impose any particular limitation on the stirring device; any conventional stirring device can be used. In embodiments of this invention, the stirring device can be a reaction vessel equipped with a temperature control device, a high-speed stirrer, and a thermometer.

[0039] In this invention, when the water-soluble dispersing and binding medium is in a liquid state, it is preferable to directly stir and mix the dispersant and the water-soluble dispersing and binding medium.

[0040] In this invention, when the water-soluble dispersing and binding medium is solid, it is preferable to first heat and melt the water-soluble dispersing and binding medium and stir it, and then mix it with the dispersant. In this invention, the heating and melting stirring temperature is preferably 40~90℃, more preferably 60~70℃; the heating and melting stirring speed is preferably 500~1000 rpm, more preferably 700~800 rpm; and the heating and melting stirring time is preferably 20~80 min, more preferably 50~60 min.

[0041] After obtaining the dispersion base liquid, the present invention mixes low-density polyethylene powder, functional ion exchange resin and the dispersion base liquid and then performs homogenization treatment to obtain a suspension.

[0042] In this invention, the method for mixing the low-density polyethylene powder, the functional ion exchange resin, and the dispersion base liquid preferably includes: adding the low-density polyethylene powder to the dispersion base liquid under a first stirring to obtain a preliminary suspension; adding the functional ion exchange resin to the preliminary suspension, and then performing a second stirring to obtain a slurry of low-density polyethylene powder, functional ion exchange resin, and the dispersion base liquid.

[0043] In this invention, the stirring speed of the first stirring is preferably 1000~1200 rpm, more preferably 700~1000 rpm; the stirring time of the first stirring is preferably 20~240 min, more preferably 100~180 min.

[0044] In this invention, the functional ion exchange resin is preferably dried first, and then added to the suspension. In this invention, the drying temperature is preferably 60-80℃, more preferably 70-80℃; the vacuum degree of the drying is preferably -0.09MPa; and the drying time is preferably 2-4 hours. Through drying, this invention removes moisture and volatile impurities adsorbed on the particle surface. After cooling to room temperature and sealing for later use, the moisture content of the functional ion exchange resin can be ≤0.5%, avoiding secondary moisture absorption.

[0045] In this invention, the feeding rate of the functional ion exchange resin added to the step suspension is preferably 1~15 g / L / min, more preferably 6~8 g / L / min.

[0046] In this invention, the stirring speed of the second stirring is preferably 1000~1200 rpm, more preferably 700~1000 rpm; the stirring time of the second stirring is preferably 20~360 min, more preferably 200~240 min.

[0047] In this invention, the homogenization pressure of the homogenization process is preferably 20-80 MPa, more preferably 50-60 MPa; the homogenization temperature of the homogenization process is preferably 50-80°C, more preferably 70-80°C; the cyclic homogenization process is preferably performed 5-6 times, and the time for each homogenization is preferably 10-35 min, more preferably 22-25 min.

[0048] After obtaining the suspension, the present invention performs degassing treatment on the suspension to obtain a composite slurry.

[0049] In this invention, the degassing treatment is preferably static constant temperature negative pressure degassing; the temperature of the static constant temperature negative pressure degassing is preferably 50~80℃, more preferably 60~70℃; the negative pressure vacuum degree of the static constant temperature negative pressure degassing is preferably -0.08~-0.10MPa, more preferably -0.09MPa; the time of the static constant temperature negative pressure degassing is preferably 4~18h, more preferably 10~12h. This invention can remove bubbles through degassing treatment, improving the uniformity of the prepared cation exchange membrane.

[0050] In this invention, the viscosity of the composite slurry is preferably 3000~8000 mPa·s, more preferably 4000~5000 mPa·s. In this invention, if the viscosity of the composite slurry is not within the above range, it is preferably adjusted by adding PEG to bring the viscosity of the composite slurry within the above range; if the viscosity is too high, PEG200 can be added; if the viscosity is too low, PEG4000 can be added.

[0051] After obtaining the composite slurry, the present invention coats the composite slurry onto the mesh material and then performs a heating and curing treatment to obtain an ion exchange membrane.

[0052] In this invention, the material of the mesh is preferably PP mesh or PE mesh; the mesh count of the mesh is preferably 50-300 mesh, more preferably 100-250 mesh; the wire diameter of the mesh is preferably 0.1-0.3 mm, more preferably 0.1-0.2 mm.

[0053] In this invention, the coating method is preferably high-pressure jet coating. The parameters for high-pressure jet coating preferably include: a material tank temperature of 5-80°C, more preferably 50-70°C; a conveyor speed of 1-5 m / min, more preferably 2-3 m / min; a nozzle orifice diameter of 0.1-0.5 mm, more preferably 0.2-0.3 mm; a jet pressure of 0.5-1.5 MPa, more preferably 1.0-1.2 MPa; a jet distance of 5-15 cm, more preferably 10-12 cm; and a nozzle moving speed of 5-10 cm / s, more preferably 5-7 cm / s. This invention, through high-pressure jet coating and adjusting the number of high-pressure jet coating passes, can form a uniform coating thickness on the mesh material. In this invention, the coating thickness is preferably 5-150 μm, more preferably 10-100 μm. The number of high-pressure jet coating passes is preferably 1-10.

[0054] In this invention, during the coating process, it is preferable to fix the mesh material to the conveying device to control the mesh tension at 0.1~0.3MPa. By fixing the mesh material, this invention can prevent deformation of the mesh material during the coating process.

[0055] In this invention, the heating and curing process preferably includes: heating from room temperature to a first temperature at a first heating rate, and performing a first heat preservation at the first temperature; then heating to a second temperature at a second heating rate, and performing a second heat preservation at the second temperature.

[0056] In this invention, the first heating rate is preferably 5~10℃ / min, more preferably 5~8℃ / min; the first temperature is preferably 50~90℃, more preferably 80℃; the first holding time is preferably 1~3h, more preferably 2h; the second heating rate is preferably 5~10℃ / min, more preferably 5~8℃ / min; the second temperature is preferably 105~140℃, more preferably 120℃; and the second holding time is preferably 3~6h, more preferably 4h. By heating and curing under the above conditions, this invention enables the coating to solidify and form a cation exchange membrane.

[0057] After obtaining the ion exchange membrane, the present invention sequentially washes the ion exchange membrane with water to remove impurities and activates it to obtain a cation exchange membrane.

[0058] In this invention, the preferred method for removing impurities by water washing is immersion in deionized water. In an embodiment of this invention, the immersion time can be 24 hours, during which the deionized water is replaced 2-3 times. This invention, through the above-described impurity removal method, can remove uncured PEG, dispersant, and trace impurities remaining on the surface of the ion exchange membrane.

[0059] In this invention, the activation method is preferably as follows: immersing the ion-exchange membrane obtained by water washing and impurity removal in an acid solution for soaking treatment. In this invention, the acid solution is preferably a hydrochloric acid solution, and the concentration of the hydrochloric acid solution is preferably 0.5 mol / L. In this invention, the soaking treatment time is preferably 1 hour.

[0060] In this invention, the ion-exchange membrane obtained after acid activation is preferably cleaned and then dried to obtain a cation exchange membrane.

[0061] The present invention does not specifically limit the cleaning method, as long as it can remove residual acid from the ion exchange membrane. In embodiments of the present invention, the cleaning reagent can be deionized water until the pH is close to neutral.

[0062] In this invention, the drying process is preferably carried out in a vacuum oven. The drying temperature is preferably 60-80°C, more preferably 70°C; the vacuum level is preferably -0.09 MPa; and the drying time is preferably 3-5 hours, more preferably 3-4 hours. Preferably, the dried ion-exchange membrane is cooled to room temperature to obtain a cation exchange membrane.

[0063] The method provided by this invention utilizes LDPE powder and ion exchange resin, exhibiting excellent compatibility. The LDPE powder and ion exchange resin particles are uniformly dispersed without significant phase separation, resulting in a cation exchange membrane with low resistance and uniformity. Furthermore, it eliminates the need for complex chemical polymerization and functional group reactions, making the process economical. The method provided by this invention contains no volatile organic compounds, toxic or harmful monomers, or heavy metals. The raw materials are environmentally friendly, with no harmful gas emissions or hazardous waste generation, making the production environment environmentally friendly. The cation exchange membrane prepared by this invention can improve ion exchange rate and energy utilization efficiency. The method provided by this invention involves no complex chemical reactions or harsh process conditions, with standardized operating steps, easily enabling large-scale continuous production.

[0064] The present invention also provides a cation exchange membrane prepared by the preparation method described in the above technical solution.

[0065] The cation exchange membrane provided by this invention has excellent adsorption capacity, mechanical properties and low ion conduction resistance.

[0066] The present invention also provides the application of the cation exchange membrane described above as a separation material.

[0067] In this invention, cation exchange membranes are used as separation materials because they have excellent adsorption capacity, mechanical properties and low ion conduction resistance.

[0068] In this invention, the separating material can be used in fields such as electrodialysis desalination, industrial wastewater treatment, electrolytic hydrogen production, chlor-alkali industry, seawater desalination, and food and pharmaceutical purification.

[0069] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0070] In this embodiment of the invention, the raw materials are pretreated before use. Specifically, LDPE ultrafine powder is placed in a vacuum oven, the vacuum degree is set to -0.09MPa and the temperature is 70℃, and dried for 3 hours. After drying, it is cooled to room temperature, sealed and stored for later use. The moisture content of the particles after pretreatment is tested to be ≤0.5%.

[0071] The functional ion exchange resin was washed four times with deionized water for 15 minutes each time to remove surface free impurities and broken fine powder. Then it was placed in a vacuum oven with a vacuum of -0.09 MPa and a temperature of 55°C for 4 hours until the resin moisture content was ≤5%. After removal, it was pulverized by an air jet mill (with a gas pressure of 0.7 MPa). After pulverization, the resin particle size was controlled to be ≤1 μm and then sealed for later use.

[0072] Heat the PEG in an 80℃ constant temperature bath until melted, set the stirring speed to 400 rpm, stir for 20 minutes to homogenize the system, and keep it at the temperature for later use.

[0073] Example 1

[0074] A method for preparing a cation exchange membrane; the raw materials for preparing the cation exchange membrane, by mass percentage, consist of: 40% LDPE ultrafine powder; 30% functional ion exchange resin (001×7, sulfonic acid styrene-type cation exchange resin, crosslinking degree 4, original particle size 0.3~0.5mm, functional group is sulfonic acid group); 27.5% water-soluble dispersion and binding medium (PEG4000); and 2.5% dispersant (isomeric alcohol polyoxyethylene ether).

[0075] The steps of the method for preparing the cation exchange membrane are as follows:

[0076] (1) Inject 5.5 kg of pretreated PEG4000 into a reactor equipped with a constant temperature device, a high-speed stirrer and a thermometer. Set the temperature inside the reactor to 65°C and the stirring speed to 750 rpm. Stir for 55 min. While stirring continuously, slowly add 0.5 kg of dispersant (isomeric alcohol polyoxyethylene ether), adjust the stirring speed to 800 rpm, and continue stirring for 120 min until the dispersant is completely dissolved and uniformly dispersed in the PEG4000 medium to form a uniform, transparent and stable dispersion base liquid without obvious particles.

[0077] (2) Add 8.0 kg of pretreated LDPE ultrafine powder to the dispersion base obtained in step (1), maintain the stirring speed at 850 rpm, stir for 150 min to form a uniform suspension; then add 6.0 kg of pretreated cation exchange resin at a feeding rate of 7 g / L / min, and continue stirring at 850 rpm for 220 min to achieve preliminary mixing and dispersion of LDPE ultrafine powder and cation exchange resin to obtain a preliminary suspension; transfer the preliminary suspension to a high-pressure homogenizer, set the homogenization pressure to 60 MPa and the homogenization temperature to 70 °C, cycle homogenize 5 times, and each homogenization time is 23 min. Break the particle agglomerates by high pressure shear force to obtain a suspension.

[0078] (3) The suspension obtained in step (2) is returned to the reactor. The temperature inside the reactor is set to 70°C and the vacuum degree is -0.09MPa. The mixture is allowed to stand under negative pressure for 11 hours to degas, and a composite slurry is obtained. The viscosity of the slurry after degassing is 4500mPa·s.

[0079] (4) Select 250 mesh polypropylene (PP) mesh (0.1 mm wire diameter) as the reinforcing mesh material, fix it on the conveying device, and precisely control the mesh tension to 0.2 MPa to avoid deformation of the mesh material during the coating process;

[0080] The composite slurry obtained in step (3) is injected into the tank of the high-pressure spray coating equipment, and the temperature of the tank is maintained at 70°C. The operating speed of the conveying device is set to 2.5 m / min, so that the mesh material passes through the spraying area at a uniform speed. The parameters of the high-pressure spray coating equipment are adjusted as follows: nozzle orifice diameter 0.2 mm, spraying pressure 1.1 MPa, spraying distance 11 cm, nozzle moving speed 6 cm / s. The target coating thickness of 90 μm is achieved through 3 sprays to ensure that the coating uniformly covers the surface of the mesh material and the inner wall of the mesh holes.

[0081] The coated mesh was transferred to an oven and cured using a segmented heating process: the temperature was increased from room temperature (25℃) to 80℃ at a rate of 5℃ / min and held for 2 hours; then the temperature was increased to 120℃ at a rate of 5℃ / min and held for 4 hours. This process allowed the LDPE ultrafine powder and cation exchange resin particles to form a strong physical entanglement and interfacial bond between the particles and the mesh surface, resulting in an ion exchange membrane.

[0082] (5) Immerse the ion exchange membrane obtained in step (4) in deionized water for 24 hours, changing the deionized water twice during the period to remove uncured PEG4000, dispersant and trace impurities remaining on the surface; then immerse the membrane material in 0.5 mol / L hydrochloric acid solution for 1 hour for activation treatment; place the activated membrane material in a vacuum oven, set the temperature to 70℃ and the vacuum degree to -0.09 MPa, and dry for 3.5 hours; after drying, cool to room temperature and package to obtain the finished cation exchange membrane.

[0083] The performance of the cation exchange membrane prepared in this embodiment was tested, and the test results are shown in Table 1:

[0084] Table 1 Performance test results of cation exchange membranes prepared in the examples

[0085]

[0086] Example 2

[0087] A method for preparing a cation exchange membrane; the raw materials for preparing the cation exchange membrane, by mass percentage, consist of: 45% LDPE ultrafine powder; 25% functional ion exchange resin (D001, sulfonic acid styrene-type cation exchange resin, crosslinking degree 4, original particle size 0.3~0.5mm, functional group is sulfonic acid group); 27% water-soluble dispersion and binding medium (PEG2000); and 3% dispersant (fatty alcohol polyoxyethylene ether).

[0088] The steps of the method for preparing the cation exchange membrane are as follows:

[0089] (1) Inject 5.4 kg of pretreated PEG2000 into a reactor equipped with a constant temperature device, a high-speed stirrer and a thermometer. Set the temperature inside the reactor to 65°C and the stirring speed to 750 rpm. Stir for 55 min. While stirring continuously, slowly add 0.6 kg of dispersant (fatty alcohol polyoxyethylene ether), adjust the stirring speed to 800 rpm, and continue stirring for 120 min until the dispersant is completely dissolved and uniformly dispersed in the PEG2000 medium to form a uniform, transparent and stable dispersion base liquid without obvious particles.

[0090] (2) Add 9.0 kg of pretreated LDPE ultrafine powder to the dispersion base obtained in step (1), maintain the stirring speed at 850 rpm, stir for 150 min to form a uniform suspension; then add 5.0 kg of pretreated cation exchange resin at a feeding rate of 7 g / L / min, and continue stirring at 850 rpm for 220 min to achieve the initial mixing and dispersion of LDPE ultrafine powder and cation exchange resin to obtain a preliminary suspension; transfer the preliminary suspension to a high-pressure homogenizer, set the homogenization pressure to 60 MPa and the homogenization temperature to 70 °C, cycle the homogenization 5 times, and each homogenization time is 23 min to break up the particle agglomerates by high pressure shear force to obtain a suspension;

[0091] (3) The suspension obtained in step (2) is returned to the reactor. The temperature inside the reactor is set to 70°C and the vacuum degree is -0.09MPa. The mixture is allowed to stand under negative pressure for 11 hours to degas, and a composite slurry is obtained. The viscosity of the slurry after degassing is 4600mPa·s.

[0092] (4) Select 250 mesh polypropylene (PP) mesh (0.1 mm wire diameter) as the reinforcing mesh material, fix it on the conveying device, and precisely control the mesh tension to 0.2 MPa to avoid deformation of the mesh material during the coating process;

[0093] The composite slurry obtained in step (3) is injected into the tank of the high-pressure spray coating equipment, and the temperature of the tank is maintained at 70°C. The operating speed of the conveying device is set to 2.5 m / min, so that the mesh material passes through the spraying area at a uniform speed. The parameters of the high-pressure spray coating equipment are adjusted as follows: nozzle orifice diameter 0.2 mm, spraying pressure 1.1 MPa, spraying distance 11 cm, nozzle moving speed 6 cm / s. The target coating thickness of 90 μm is achieved through 3 sprays to ensure that the coating uniformly covers the surface of the mesh material and the inner wall of the mesh holes.

[0094] The coated mesh was transferred to an oven and cured using a segmented heating process: the temperature was increased from room temperature to 80°C at a rate of 5°C / min and held for 2 hours; then the temperature was increased to 120°C at a rate of 5°C / min and held for 4 hours. This process allowed the LDPE ultrafine powder and cation exchange resin particles to form a strong physical entanglement and interfacial bond between the particles and the mesh surface, resulting in an ion exchange membrane.

[0095] (5) Immerse the ion exchange membrane obtained in step (4) in deionized water for 24 hours, changing the deionized water twice during the period to remove uncured PEG2000, dispersant and trace impurities remaining on the surface; then immerse the membrane material in 0.5mol / L hydrochloric acid solution for 1 hour for activation treatment; place the activated membrane material in a vacuum oven, set the temperature to 70℃ and the vacuum degree to -0.09MPa, and dry for 3.5 hours; after drying, cool to room temperature and package to obtain the finished cation exchange membrane.

[0096] The performance of the cation exchange membrane prepared in this embodiment was tested, and the test results are shown in Table 2:

[0097] Table 2 Performance test results of the cation exchange membrane prepared in Example 2

[0098]

[0099] Example 3

[0100] A method for preparing a cation exchange membrane; the raw materials for preparing the cation exchange membrane, by mass percentage, consist of: 35% LDPE ultrafine powder; 35% functional ion exchange resin (Amberlite IR-120, sulfonic acid styrene-type cation exchange resin, crosslinking degree 4, original particle size 0.3~0.5mm, functional group is sulfonic acid group); 27% water-soluble dispersion and binding medium (PEG4000); and 3% dispersant (alkylphenol polyoxyethylene ether).

[0101] The steps of the method for preparing the cation exchange membrane are as follows:

[0102] (1) Inject 5.4 kg of pretreated PEG4000 into a reactor equipped with a constant temperature device, a high-speed stirrer and a thermometer. Set the temperature inside the reactor to 65°C and the stirring speed to 750 rpm. Stir for 55 min. While stirring continuously, slowly add 0.6 kg of dispersant (alkylphenol polyoxyethylene ether), adjust the stirring speed to 800 rpm, and continue stirring for 120 min until the dispersant is completely dissolved and uniformly dispersed in the PEG4000 medium to form a uniform, transparent and stable dispersion base liquid without obvious particles.

[0103] (2) Add 7.0 kg of pretreated LDPE ultrafine powder to the dispersion base obtained in step (1), maintain the stirring speed at 850 rpm, stir for 150 min to form a uniform suspension; then add 7.0 kg of pretreated cation exchange resin at a feeding rate of 7 g / L / min, and continue stirring at 850 rpm for 220 min to achieve the initial mixing and dispersion of LDPE ultrafine powder and cation exchange resin to obtain a preliminary suspension; transfer the preliminary suspension to a high-pressure homogenizer, set the homogenization pressure to 60 MPa and the homogenization temperature to 70 °C, cycle the homogenization 5 times, and each homogenization time is 23 min to break up the particle agglomerates by high pressure shear force to obtain a suspension;

[0104] (3) The suspension obtained in step (2) is returned to the reactor. The temperature inside the reactor is set to 70°C and the vacuum degree is -0.09MPa. The mixture is allowed to stand under negative pressure for 11 hours to degas, and a composite slurry is obtained. The viscosity of the slurry after degassing is 4400mPa·s.

[0105] (4) Select 250 mesh polypropylene (PP) mesh (0.1 mm wire diameter) as the reinforcing mesh material, fix it on the conveying device, and precisely control the mesh tension to 0.2 MPa to avoid deformation of the mesh material during the coating process;

[0106] The composite slurry obtained in step (3) is injected into the tank of the high-pressure spray coating equipment, and the temperature of the tank is maintained at 70°C. The operating speed of the conveying device is set to 2.5 m / min, so that the mesh material passes through the spraying area at a uniform speed. The parameters of the high-pressure spray coating equipment are adjusted as follows: nozzle orifice diameter 0.2 mm, spraying pressure 1.1 MPa, spraying distance 11 cm, nozzle moving speed 6 cm / s. The target coating thickness of 90 μm is achieved through 3 sprays to ensure that the coating uniformly covers the surface of the mesh material and the inner wall of the mesh holes.

[0107] The coated mesh was transferred to an oven and cured using a segmented heating process: the temperature was increased from room temperature to 80°C at a rate of 5°C / min and held for 2 hours; then the temperature was increased to 120°C at a rate of 5°C / min and held for 4 hours. This process allowed the LDPE ultrafine powder and cation exchange resin particles to form a strong physical entanglement and interfacial bond between the particles and the mesh surface, resulting in an ion exchange membrane.

[0108] (5) Immerse the ion exchange membrane obtained in step (4) in deionized water for 24 hours, changing the deionized water twice during the period to remove uncured PEG4000, dispersant and trace impurities remaining on the surface; then immerse the membrane material in 0.5 mol / L hydrochloric acid solution for 1 hour for activation treatment; place the activated membrane material in a vacuum oven, set the temperature to 70℃ and the vacuum degree to -0.09 MPa, and dry for 3.5 hours; after drying, cool to room temperature and package to obtain the finished cation exchange membrane.

[0109] The performance of the cation exchange membrane prepared in this embodiment was tested, and the test results are shown in Table 3:

[0110] Table 3 Performance test results of the cation exchange membrane prepared in Example 3

[0111]

[0112] Example 4

[0113] A method for preparing a cation exchange membrane; the raw materials for preparing the cation exchange membrane, by mass percentage, consist of: 38% LDPE ultrafine powder; 30% functional ion exchange resin (Lewatit S100, sulfonic acid styrene-type cation exchange resin, crosslinking degree 4, original particle size 0.3~0.5mm, functional group is sulfonic acid group); 30% water-soluble dispersion and binding medium (PEG2000); and 2% dispersant (polyoxyethylene sorbitan monooleate).

[0114] The steps of the method for preparing the cation exchange membrane are as follows:

[0115] (1) Inject 6.0 kg of pretreated PEG2000 into a reactor equipped with a constant temperature device, a high-speed stirrer and a thermometer. Set the temperature inside the reactor to 65°C and the stirring speed to 750 rpm. Stir for 55 min. While stirring continuously, slowly add 0.4 kg of dispersant (polyoxyethylene sorbitan monooleate), adjust the stirring speed to 800 rpm, and continue stirring for 120 min until the dispersant is completely dissolved and uniformly dispersed in the PEG2000 medium to form a uniform, transparent and stable dispersion base liquid without obvious particles.

[0116] (2) Add 7.6 kg of pretreated LDPE ultrafine powder to the dispersion base obtained in step (1), maintain the stirring speed at 850 rpm, stir for 150 min to form a uniform suspension; then add 6.0 kg of pretreated cation exchange resin at a feeding rate of 7 g / L / min, and continue stirring at 850 rpm for 220 min to achieve the initial mixing and dispersion of LDPE ultrafine powder and cation exchange resin to obtain a preliminary suspension; transfer the preliminary suspension to a high-pressure homogenizer, set the homogenization pressure to 60 MPa and the homogenization temperature to 70 °C, cycle homogenize 5 times, and each homogenization time is 23 min. The particle agglomerates are broken by high pressure shear force to obtain a suspension.

[0117] (3) The suspension obtained in step (2) is returned to the reactor. The temperature inside the reactor is set to 70°C and the vacuum degree is -0.09MPa. The mixture is allowed to stand under negative pressure for 11 hours to degas, and a composite slurry is obtained. The viscosity of the slurry after degassing is 4500mPa·s.

[0118] (4) Select 250 mesh polypropylene (PP) mesh (0.1 mm wire diameter) as the reinforcing mesh material, fix it on the conveying device, and precisely control the mesh tension to 0.2 MPa to avoid deformation of the mesh material during the coating process;

[0119] The composite slurry obtained in step (3) is injected into the tank of the high-pressure spray coating equipment, and the temperature of the tank is maintained at 70°C. The operating speed of the conveying device is set to 2.5 m / min, so that the mesh material passes through the spraying area at a uniform speed. The parameters of the high-pressure spray coating equipment are adjusted as follows: nozzle orifice diameter 0.2 mm, spraying pressure 1.1 MPa, spraying distance 11 cm, nozzle moving speed 6 cm / s. The target coating thickness of 90 μm is achieved through 3 sprays to ensure that the coating uniformly covers the surface of the mesh material and the inner wall of the mesh holes.

[0120] The coated mesh was transferred to an oven and cured using a segmented heating process: the temperature was increased from room temperature to 80°C at a rate of 5°C / min and held for 2 hours; then the temperature was increased to 120°C at a rate of 5°C / min and held for 4 hours. This process allowed the LDPE ultrafine powder and cation exchange resin particles to form a strong physical entanglement and interfacial bond between the particles and the mesh surface, resulting in an ion exchange membrane.

[0121] (5) Immerse the ion exchange membrane obtained in step (4) in deionized water for 24 hours, changing the deionized water twice during the period to remove uncured PEG2000, dispersant and trace impurities remaining on the surface; then immerse the membrane material in 0.5mol / L hydrochloric acid solution for 1 hour for activation treatment; place the activated membrane material in a vacuum oven, set the temperature to 70℃ and the vacuum degree to -0.09MPa, and dry for 3.5 hours; after drying, cool to room temperature and package to obtain the finished cation exchange membrane.

[0122] The performance of the cation exchange membrane prepared in this embodiment was tested, and the test results are shown in Table 4:

[0123] Table 4 Performance test results of the cation exchange membrane prepared in Example 4

[0124]

[0125] Comparative Example 1

[0126] A method for preparing a cation exchange membrane; the raw materials for preparing the cation exchange membrane, by mass percentage, consist of: 70% LDPE ultrafine powder; 27% water-soluble dispersing and binding medium (PEG4000); and 3% dispersant (isomeric alcohol polyoxyethylene ether) (non-functional ion exchange resin).

[0127] The steps of the method for preparing the cation exchange membrane are as follows:

[0128] (1) Inject 5.4 kg of pretreated PEG4000 into a reactor equipped with a constant temperature device, a high-speed stirrer and a thermometer. Set the temperature inside the reactor to 65°C and the stirring speed to 750 rpm. Stir for 55 min. While stirring continuously, slowly add 0.6 kg of dispersant (isomeric alcohol polyoxyethylene ether), adjust the stirring speed to 800 rpm, and continue stirring for 120 min until the dispersant is completely dissolved and uniformly dispersed in the PEG4000 medium to form a uniform, transparent and stable dispersion base liquid without obvious particles.

[0129] (2) Add 14.0 kg of pretreated LDPE ultrafine powder to the dispersion base obtained in step (1), maintain the stirring speed at 850 rpm, stir for 150 min to form a uniform suspension (no functional ion exchange resin is added in this step); transfer the suspension to a high-pressure homogenizer, set the homogenization pressure to 60 MPa and the homogenization temperature to 70 °C, cycle the homogenization 5 times, and each homogenization time is 23 min to obtain the suspension;

[0130] (3) Return the suspension obtained in step (2) to the reactor, set the temperature inside the reactor to 70°C and the vacuum degree to -0.09MPa, and let it stand under negative pressure for degassing for 11 hours to obtain the composite slurry;

[0131] Steps (4) to (5) are exactly the same as in Example 1.

[0132] The performance of the membrane material prepared in this comparative example was tested, and the test results are shown in Table 5:

[0133] Table 5. Test results of membrane material performance in Comparative Example 1

[0134]

[0135] Comparative Example 2

[0136] A method for preparing a cation exchange membrane; the raw materials for preparing the cation exchange membrane, by mass percentage, consist of: 65% functional ion exchange resin (001×7, sulfonic acid styrene-type cation exchange resin, crosslinking degree 4, original particle size 0.3~0.5mm, functional group is sulfonic acid group); 32% water-soluble dispersion and binding medium (PEG4000); and 3% dispersant (isomeric alcohol polyoxyethylene ether) (LDPE ultrafine powder-free).

[0137] The steps of the method for preparing the cation exchange membrane are as follows:

[0138] (1) Inject 6.4 kg of pretreated PEG4000 into a reactor equipped with a constant temperature device, a high-speed stirrer and a thermometer. Set the temperature inside the reactor to 65°C and the stirring speed to 750 rpm. Stir for 55 min. While stirring continuously, slowly add 0.6 kg of dispersant (isomeric alcohol polyoxyethylene ether), adjust the stirring speed to 800 rpm, and continue stirring for 120 min until the dispersant is completely dissolved and uniformly dispersed in the PEG4000 medium to form a uniform, transparent and stable dispersion base liquid without obvious particles.

[0139] (2) Add 13.0 kg of pretreated cation exchange resin (no LDPE ultrafine powder is added in this step) directly to the dispersion base liquid obtained in step (1) at a feeding rate of 7 g / L / min, and stir continuously at a rate of 850 rpm for 220 min to obtain a preliminary suspension; transfer the preliminary suspension to a high-pressure homogenizer, set the homogenization pressure to 60 MPa and the homogenization temperature to 70 °C, and homogenize 5 times, with each homogenization time being 23 min to obtain a suspension;

[0140] (3) Return the suspension obtained in step (2) to the reactor, set the temperature inside the reactor to 70°C and the vacuum degree to -0.09MPa, and let it stand under negative pressure for degassing for 11 hours to obtain the composite slurry;

[0141] Steps (4) to (5) are exactly the same as in Example 1.

[0142] The performance of the membrane material prepared in this comparative example was tested, and the test results are shown in Table 6:

[0143] Table 6. Test results of membrane material performance in Comparative Example 2

[0144]

[0145] Effect verification

[0146] As can be seen from Tables 1 to 4, the cation exchange membrane obtained by the preparation method provided by the present invention has the low resistance uniformity of a homogeneous membrane (the sheet resistance is reduced by more than 50% compared with the traditional heterogeneous membrane), while the ion exchange capacity is maintained at 1.9~2.3 meq / g, the selective permeability is ≥98.2%, the tensile strength is ≥22 MPa, the membrane polarization phenomenon is slight, and the overall performance is significantly better than that of the traditional heterogeneous membrane.

[0147] Examples 1-4 achieved different performance focuses by adjusting the LDPE ultrafine powder, functional ion exchange resin, PEG type and dispersant type: Example 2 is more inclined to high mechanical strength, Example 3 has the highest ion exchange capacity, and Example 4 is well-balanced in all aspects, all of which can meet the needs of different application scenarios.

[0148] As shown in Table 5, Comparative Example 1, without the addition of functional ion exchange resin, resulted in an ion exchange capacity close to 0, with no actual ion exchange function. Table 6 shows that Comparative Example 2, without the addition of LDPE ultrafine powder, resulted in a membrane material with high brittleness, low tensile strength, and severe membrane polarization, failing to meet the mechanical properties required for industrial use. These results fully demonstrate that the synergistic compatibility of LDPE ultrafine powder and functional ion exchange resin, as well as the pore-forming effect of the water-soluble dispersing and binding medium, are key to achieving the superior performance of this invention.

[0149] The method provided by this invention contains no volatile organic compounds (VOCs), toxic or harmful monomers, or heavy metals, and the raw materials themselves are environmentally friendly. The entire process involves no harmful gas emissions and no hazardous waste generation. The washing wastewater has a simple composition, is easy to treat and meet standards, and the production environment is friendly. The membrane material itself is chemically stable, easily recyclable after disposal, and no additives are released during use, thus avoiding pollution of the treatment system.

[0150] This invention achieves precise control of the target membrane thickness from 5 to 150 μm by adjusting the number of high-pressure spray coatings (1 to 10 times), adapting to the ion migration rate requirements of different systems while balancing separation efficiency and mechanical strength. The cation exchange membrane prepared by this invention possesses both excellent mechanical strength and flexibility. The high toughness of the LDPE matrix and the skeletal support of the reinforcing mesh work synergistically to effectively disperse interfacial stress, avoiding the brittleness defects of traditional heterogeneous membranes. It is less prone to damage and deformation under long-term acid and alkaline conditions and repeated assembly and use, significantly extending its service life and meeting the stringent requirements of continuous industrial operation.

[0151] The cation exchange membrane prepared by this invention has low resistance and uniformity, while maintaining an ion exchange capacity of 1.9~2.3 meq / g, selective permeability ≥98.2%, tensile strength ≥22 MPa, and slight membrane polarization. Its comprehensive performance is significantly better than that of traditional heterogeneous membranes. Therefore, it can be used as a separation material in separation fields such as electrodialysis desalination, industrial wastewater treatment, electrolytic hydrogen production, chlor-alkali industry, seawater desalination, and food and pharmaceutical purification.

[0152] The results above demonstrate that the cation exchange membrane prepared using the method provided by this invention possesses the low-resistance uniformity of a homogeneous membrane (membrane resistance is reduced by more than 50% compared to traditional heterogeneous membranes) while retaining the process economy of heterogeneous membranes (no complex chemical polymerization or functional group reactions are required). Furthermore, the ion exchange rate and energy utilization efficiency are significantly improved. This is because the PEG component dissolves in water after washing, forming a rich and uniform interconnected pore structure within the ion exchange membrane, greatly reducing ion migration resistance, significantly alleviating membrane polarization, and improving ion exchange rate and energy utilization efficiency. In addition, the method provided by this invention is free of volatile organic compounds (VOCs), toxic or harmful monomers, or heavy metals, and the raw materials themselves are environmentally friendly. There are no harmful gas emissions or hazardous waste generated throughout the process; the washing wastewater has a simple composition, is easy to treat and meet standards, and the production environment is environmentally friendly. The membrane material itself is chemically stable, easily recyclable after disposal, and no additives are released during use, thus avoiding pollution of the treatment system. This invention achieves precise control of the target membrane thickness from 5 to 150 μm by adjusting the number of high-pressure spray coatings (1 to 10 times), adapting to the ion migration rate requirements of different systems while balancing separation efficiency and mechanical strength. The cation exchange membrane prepared by this invention possesses both excellent mechanical strength and flexibility. The high toughness of the LDPE matrix and the skeletal support of the reinforcing mesh work synergistically to effectively disperse interfacial stress, avoiding the brittleness defects of traditional heterogeneous membranes. It is less prone to damage and deformation under long-term acid and alkaline conditions and repeated assembly and use, significantly extending its service life and meeting the stringent requirements of continuous industrial operation.

[0153] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a cation exchange membrane, characterized in that, include: The dispersant is mixed with a water-soluble dispersing and binding medium to obtain a dispersion base liquid; Low-density polyethylene powder, functional ion exchange resin and the dispersion base liquid are mixed and homogenized to obtain a suspension; the functional ion exchange resin is a styrene-type cation exchange resin. The suspension is defoamed to obtain a composite slurry; The composite slurry is coated onto a mesh material and then subjected to a heating and curing process to obtain an ion exchange membrane. The ion exchange membrane was sequentially washed with water to remove impurities and then activated to obtain a cation exchange membrane. The water-soluble dispersion and binding medium includes PEG-200, PEG-400, PEG-2000 or PEG-4000.

2. The preparation method according to claim 1, characterized in that, The raw materials for preparing the cation exchange membrane, by weight percentage, include the following components: 30-50% low-density polyethylene powder; 20-40% functional ion exchange resin; 15-35% water-soluble dispersing and binding medium; and 1-5% dispersant.

3. The preparation method according to claim 1 or 2, characterized in that, The dispersant includes one or more of isomeric alcohol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and polyoxyethylene sorbitan monooleate.

4. The preparation method according to claim 1, characterized in that, The particle size of the low-density polyethylene powder is ≤5μm.

5. The preparation method according to claim 1, characterized in that, The homogenization pressure is 20~80MPa; the homogenization temperature is 50~80℃; the homogenization cycle is 5~6 times, and the homogenization time for each cycle is 10~35min.

6. The preparation method according to claim 1, characterized in that, The coating method is high-pressure jet coating; the parameters of the high-pressure jet coating include: the material tank temperature is maintained at 5~80℃; the conveying device speed is set at 1~5m / min; the nozzle orifice diameter is 0.1~0.5mm; the spray pressure is 0.5~1.5MPa; the spray distance is 5~15cm; and the nozzle moving speed is 5~10cm / s.

7. The preparation method according to claim 1, characterized in that, The heating and curing process includes: heating from room temperature to a first temperature at a first heating rate, and holding at the first temperature for a first time; then heating to a second temperature at a second heating rate, and holding at the second temperature for a second time; the first heating rate is 5~10℃ / min; the first temperature is 50~90℃; the first holding time is 1~3h; the second heating rate is 5~10℃ / min; the second temperature is 105~140℃; and the second holding time is 3~6h.

8. The cation exchange membrane prepared by the preparation method according to any one of claims 1 to 7.

9. The use of the cation exchange membrane of claim 8 as a separation material.

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