An anion exchange membrane and a method for producing the same

Abstract

The application provides an anion exchange membrane and a preparation method thereof, and the anion exchange membrane comprises a polymer with specific structural units, wherein the polymer comprises an A element, a Cn group, R1, R2 and R3 groups, A is C, N or O, Cn is C1-C5 alkylene, and R1, R2 and R3 are each independently selected from C1-C6 alkyl. The anion exchange membrane provided by the application can effectively resist corrosion of oxidizing substances.

Description

Technical Field

[0001] This invention relates to an anion exchange membrane, and more particularly to an anion exchange membrane and its preparation method, belonging to the field of electrochemistry. Background Technology

[0002] Over the past 50 years, ion exchange membranes have evolved from laboratory tools into industrial products with significant technological and commercial impact. Today, ion exchange membranes are receiving widespread attention and have been successfully applied to the desalination of seawater and brackish water, as well as the treatment of industrial wastewater. They are effective tools for concentrating or separating ion-containing species in food and pharmaceuticals, and in the manufacture of essential chemical products. The evolution of ion exchange membranes has not only made the process cleaner and more energy-efficient, but also recycled useful wastewater that was previously wasted, thus contributing to the sustainability of societal development.

[0003] However, during the concentration of chloride salts using ion exchange membranes, a small amount of chloride ions are electrolyzed and reduced to chlorine gas under the influence of electric current. This gas then reacts with water to form hypochlorous acid anions, which is fatal to traditional anion exchange membranes containing benzene ring structures.

[0004] Therefore, developing an anion exchange membrane that can effectively resist corrosion by oxidizing substances is a huge challenge for the development of ion exchange membranes. Summary of the Invention

[0005] This invention provides an anion exchange membrane with high ion exchange capacity, low resistance, and good antioxidant properties for electrodialysis of chloride systems.

[0006] The present invention also provides a method for preparing anion exchange membrane. The preparation method is simple to operate, low in cost, and the prepared anion exchange membrane can effectively resist corrosion by oxidizing substances.

[0007] In one aspect, the present invention provides an anion exchange membrane comprising a polymer having structural units shown in Formula I:

[0008]

[0009] In Formula I, A is C, N or O, Cn is a C1 to C5 alkylene group, and R1, R2 and R3 are each independently selected from C1 to C6 alkyl groups.

[0010] The anion exchange membrane described above, wherein the polymer is a cross-linked polymer comprising the structural unit shown in Formula I.

[0011] The anion exchange membrane described above comprises a polyolefin porous membrane and the polymer filling the pores of the polyolefin porous membrane.

[0012] The thickness of the polyolefin porous membrane in the anion exchange membrane described above is 90–120 μm.

[0013] And / or, the pore size of the polyolefin porous membrane is 1 to 1000 nm.

[0014] In another aspect, the present invention provides a method for preparing the anion exchange membrane as described above, comprising the following steps:

[0015] A raw material system including the monomer shown in Formula II is coated onto a substrate, and a polymerization reaction is initiated to obtain the anion exchange membrane.

[0016]

[0017] The preparation method described above further includes a crosslinking agent, an initiator, and / or a plasticizer in the raw material system.

[0018] Preferably, the raw material system comprises 70 wt% to 89 wt% of the monomer shown in Formula II, 5 wt% to 15 wt% of the crosslinking agent, 5 wt% to 10 wt% of the plasticizer, and 1 wt% to 5 wt% of the initiator.

[0019] In the preparation method described above, the crosslinking agent includes an aliphatic crosslinking agent, preferably ethylene glycol dimethacrylate;

[0020] And / or, the plasticizer includes one or more of phthalates and fatty acid esters;

[0021] And / or, the initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

[0022] In the preparation method described above, the polymerization reaction is carried out at a temperature of 80–100°C for 6–8 hours.

[0023] As described above, the preparation method further includes, after the polymerization reaction is completed, thermal swelling treatment of the polymer product in water at 40–60°C.

[0024] In the preparation method described above, the substrate is selected from polyolefin porous membranes;

[0025] Preferably, the thickness of the polyolefin porous membrane is 90-120 μm, and / or the pore size of the polyolefin porous membrane is 1-1000 nm.

[0026] The anion exchange membrane provided by this invention comprises a polymer with a specific structure. This polymer does not contain benzene rings or carbon-carbon double bonds and has the characteristics of high hardness and high resistance to chemical corrosion. It can effectively resist the corrosion of oxidizing substances and effectively solve the problem of the poor oxidation resistance of traditional anion exchange membranes. Attached Figure Description

[0027] Figure 1 This is a partial view of the preparation system according to a specific embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1-First roller; 2-Second roller; 3-Third roller; 4-Immersion tank; 5-Fifth roller; 6-Sixth roller; 7-Seventh roller; 8-Eighth roller. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0031] In one aspect, the present invention provides an anion exchange membrane comprising a polymer having structural units shown in Formula I:

[0032]

[0033] In Formula I, A is C, N or O, Cn is a C1 to C5 alkylene group, and R1, R2 and R3 are each independently selected from C1 to C6 alkyl groups.

[0034] The C1-C5 alkylene groups can be straight-chain alkylene groups of C1-C5 or cyclic alkylene groups of C3-C5. In this invention, straight-chain alkylene groups of C1-C5 are preferred, as they have higher stability compared to cyclic alkylene groups.

[0035] Considering the flexibility and hydrophilicity of the formed polymer, C3 alkyl groups are preferred; considering the stability and ion exchange capacity of the formed polymer, A=O groups are preferred.

[0036] R1, R2, and R3 are each independently selected from C1-C6 alkyl groups, and can be either straight-chain alkyl groups from C1-C6 or cyclic alkyl groups from C3-C6.

[0037] In one specific embodiment, two of R1, R2, and R3 are methyl groups. The inventors discovered through experimental research that when two of R1, R2, and R3 are methyl groups, the anion exchange membrane exhibits better stability and stronger resistance to corrosion by oxidizing substances. Conversely, the longer the carbon chain length of R1, R2, and R3, the more easily Hoffmann elimination occurs, affecting the stability of the anion exchange membrane.

[0038] The anion exchange membrane provided by this invention comprises polymers with structural units as shown in Formula I, which can effectively resist corrosion by oxidizing substances and solve the problem of poor oxidation resistance of traditional anion exchange membranes. The inventors analyzed this and believe the reason may be that the carbonyl structure in the polymer with the structural units shown in Formula I can stabilize the free radical reaction of the carbon-carbon double bond through a conjugation effect. In addition, the polymer with the structural units shown in Formula I does not contain double bonds or benzene rings, which can effectively resist corrosion by oxidizing substances, improving the service life of the formed anion exchange membrane. Furthermore, the A atoms therein can also provide good ion exchange capacity to the anion exchange membrane through a conjugation effect, thereby improving the oxidation resistance of the anion exchange membrane under electrodialysis in a chloride system.

[0039] Furthermore, in one specific embodiment of the present invention, the polymer is a cross-linked polymer comprising the structural unit shown in Formula I.

[0040] In detail, the structural units shown in Formula I are chemically cross-linked to form a polymer with a three-dimensional network structure, wherein the structural units shown in Formula I can be interconnected by a cross-linking agent.

[0041] This invention does not limit the specific type of crosslinking agent, and crosslinking agents commonly used in the art, such as aliphatic crosslinking agents, can be selected.

[0042] When the anion exchange membrane includes the above-mentioned crosslinking agents, the mechanical strength and oxidation resistance of the anion exchange membrane can be further enhanced.

[0043] Furthermore, in one specific embodiment of the present invention, the anion exchange membrane includes a polyolefin porous membrane and a polymer filling the pores of the polyolefin porous membrane.

[0044] Among them, polyolefin porous membranes can provide mechanical support and enhance structural stability, while polymers can improve oxidation resistance.

[0045] In detail, the present invention does not limit the material of the polyolefin porous membrane, and can select materials commonly used in the art, such as PE and PP. Specifically, it can be divided into single-layer PP, single-layer PE, double-layer PP / PE, double-layer PP / PP and triple-layer PP / PE / PP, etc., with triple-layer PP / PE / PP having high flexibility being preferred.

[0046] This invention is not limited to the mass ratio of polymer to polyolefin porous membrane; in one specific embodiment, the mass ratio is 1:0.5 to 1:1.5.

[0047] Furthermore, in one specific embodiment of the present invention, the thickness of the polyolefin porous membrane is 90–120 μm;

[0048] And / or, the pore size of the polyolefin porous membrane is 1 to 1000 nm.

[0049] In this invention, the thickness of the polyolefin porous membrane is the average thickness, and the pore size of the polyolefin porous membrane is the average pore size.

[0050] In detail, the thickness of the polyolefin porous membrane includes, but is not limited to, a range of 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, or any combination thereof.

[0051] When the thickness of the polyolefin porous membrane is within the above range, it can avoid the problems of high impedance, increased energy consumption, and impaired ion transport caused by excessive thickness, and also avoid the problems of low structural mechanical strength and poor stability caused by excessively thin thickness.

[0052] The pore size of polyolefin porous membranes includes, but is not limited to, a range of 1 nm, 10 nm, 50 nm, 100 nm, 500 nm, 1000 nm, or any combination thereof.

[0053] When the pore size of the polyolefin porous membrane is within the above range, it can provide a good supporting structure, improve the mechanical strength of the anion exchange membrane, and at the same time provide an appropriate porosity, so that the anion exchange membrane has good ion exchange efficiency.

[0054] In another aspect, the present invention provides a method for preparing the anion exchange membrane as described above, comprising the following steps:

[0055] A raw material system including the monomer shown in Formula II is coated onto a substrate, and a polymerization reaction is initiated to obtain an anion exchange membrane.

[0056]

[0057] In detail, a raw material system including the monomers shown in Formula II is coated onto a substrate to initiate a polymerization reaction. The monomers described in Formula II are polymerized to obtain the polymer shown in Formula I, which in turn constitutes an anion exchange membrane.

[0058] In one specific implementation, utilizing Figure 1 The production system shown performs coating processing. Specifically, the production system includes a first roller 1, a second roller 2, a third roller 3, a fifth roller 5, a sixth roller 6, a seventh roller 7, an eighth roller 8, and an immersion tank 4, wherein the immersion tank 4 contains the raw material system, the first roller 1, the second roller 2, the third roller 3, and the eighth roller 8 are driven rollers, and the remaining rollers are empty rollers.

[0059] By applying a brake to the second roller 2, the substrate retained on the second roller 2 is tensioned along its length, and then immersed in the raw material system in the impregnation tank 4. The cover material supplied from the first roller 1 is tensioned and expanded in the same manner as the substrate. The reinforcing material impregnated with the raw material system and the substrate are subjected to double-layer extrusion by the sixth roller 6 and directional peeling by the seventh roller 7, and then wound up on the third roller 3. Another layer of cover material contaminated with the raw material system is wound up and scrapped on the eighth roller 8. The fifth roller 5 serves to traction and stretch, preventing the substrate from sagging and deforming during the coating process. The content of the raw material system coated on the substrate is adjusted by adjusting the distance between the two sixth rollers 6.

[0060] Understandably, after coating, the membrane roll is removed from the third roller 3 and subjected to polymerization to obtain anion exchange membrane.

[0061] The covering material primarily serves as a protective layer. Covering materials include, but are not limited to, polyester film (PET), cellulose film, polyimide film (PI), polyamide film (PA), spandex film, and aramid film, with PET film being preferred due to its low cost, high temperature resistance, and resistance to deformation. Before the polymerization reaction, the covering material is peeled off from the substrate of the coating raw material system to prevent the covering material from affecting the subsequent polymerization reaction.

[0062] In one specific embodiment, the monomer shown in Formula II is prepared by a method comprising the following steps: using an alcohol solvent as an ammoniation solvent; ammoniation of the methylpropene-diamino monomer with a haloalkane R3X (X being a halogen), wherein the ammoniation reaction parameters are an ammoniation temperature of 40–50°C and an ammoniation time of 6–8 h, to obtain the monomer shown in Formula II. The general structural formula of the methylpropene-diamino monomer is shown in Formula III.

[0063]

[0064] The alcohol reagent is one or more of methanol, ethanol, propanol, isopropanol, and butanol, preferably isopropanol with high solubility; the haloalkane is one or more of halopropane, halobutane, halopentane, and halohexane.

[0065] In one specific embodiment, the mass ratio of methpropylene-diamino monomer to alcohol reagent is 1:1 to 1:3; the molar ratio of methpropylene-diamino monomer to haloalkanes is 1:1.1 to 1:1.3.

[0066] Furthermore, in one specific embodiment of the present invention, the raw material system further includes a crosslinking agent, an initiator, and / or a plasticizer;

[0067] Preferably, the raw material system comprises 70 wt% to 89 wt% of the monomer shown in Formula II, 5 wt% to 15 wt% of the crosslinking agent, 5 wt% to 10 wt% of the plasticizer, and 1 wt% to 5 wt% of the initiator.

[0068] When the components are combined according to the above-mentioned mass content range to obtain the raw material system, the synergistic effect of the various components is more conducive to the subsequent polymerization reaction, resulting in a polymer as shown in Formula I.

[0069] Furthermore, in one specific embodiment of the present invention, the crosslinking agent includes an aliphatic crosslinking agent, preferably ethylene glycol dimethacrylate;

[0070] And / or, plasticizers include one or more of phthalates and fatty acid esters;

[0071] And / or, the initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

[0072] The above-mentioned crosslinking agents can form chemical bonds between polymer chains, forming a three-dimensional network structure and enhancing the stability of the polymer; the above-mentioned plasticizers are mainly used in the polymerization reaction to improve the flexibility and processing performance of the polymer. By inserting into the gaps between polymer chains, they lower the glass transition temperature of the material, improve the processability of the polymer, and make the material easier to mold and process during the processing; the above-mentioned initiators can better start the polymerization process and make the polymerization reaction more complete.

[0073] Furthermore, in one specific embodiment of the present invention, the polymerization reaction is carried out at a temperature of 80–100°C for a duration of 6–8 hours.

[0074] In detail, the temperature of the polymerization reaction includes, but is not limited to, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C, 100°C or any combination thereof, and the time includes, but is not limited to, 6h, 6.5h, 7h, 7.5h, 8h or any combination thereof.

[0075] When the temperature and time of the polymerization reaction are within the above range, anion exchange membranes with superior performance can be obtained.

[0076] Furthermore, in one specific embodiment of the present invention, after the polymerization reaction is completed, the polymerization product is subjected to a thermal swelling treatment in water at 40-60°C.

[0077] The temperature of the thermal expansion treatment includes, but is not limited to, 40°C, 45°C, 50°C, 55°C, 60°C, or any combination thereof.

[0078] Thermal swelling treatment not only removes excess plasticizers but also makes the pores left by these non-reactive substances tighter, thereby improving the performance of the anion exchange membrane.

[0079] Furthermore, in one specific embodiment of the present invention, the substrate is selected from polyolefin porous membranes;

[0080] Preferably, the thickness of the polyolefin porous membrane is 90–120 μm, and / or the pore size of the polyolefin porous membrane is 1–1000 nm.

[0081] In detail, the thickness of the polyolefin porous membrane includes, but is not limited to, a range of 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, or any combination thereof.

[0082] When the thickness of the polyolefin porous membrane is within the above range, it can avoid the problems of high impedance, increased energy consumption, and impaired ion transport caused by excessive thickness, and also avoid the problems of low structural mechanical strength and poor stability caused by excessively thin thickness.

[0083] The pore size of polyolefin porous membranes includes, but is not limited to, a range of 1 nm, 10 nm, 50 nm, 100 nm, 500 nm, 1000 nm, or any combination thereof.

[0084] When the pore size of the polyolefin porous membrane is within the above range, it can provide a good supporting structure, improve the mechanical strength of the anion exchange membrane, and at the same time provide an appropriate porosity, so that the anion exchange membrane has good water permeability and ion exchange efficiency.

[0085] The anion exchange membrane provided by the present invention will be described in detail below through specific embodiments.

[0086] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0087] The sources of raw materials in the examples and comparative examples are as follows:

[0088] 3-(dimethylamino)propyl methacrylate (3-DMAPPMA, Sigma-Aldrich, AR));

[0089] Dimethylaminopropylmethacrylamide (DMAPMA, Maclean's reagent, AR)

[0090] Ethylene glycol dimethacrylate (EGDMA, AR Chemicals);

[0091] Unless otherwise specified, all other raw materials and reagents are commercially available conventional chemical reagents.

[0092] Example 1

[0093] The anion exchange membrane provided in this embodiment is prepared by a method including the following steps:

[0094] 1. Mix 10 kg of 3-(dimethylamino)methacrylate (3-DMAPPMA) with 20 kg of isopropanol, then add 7.9 kg of bromopropane and react at 50 °C for 8 h to obtain a solution containing ammonium monomers.

[0095] 2. Prepare a polymerizable mixture by dissolving the ammonium monomer (80wt%), ethylene glycol dimethacrylate (EGDMA) (10wt%), dioctyl adipate (DOA) (7wt%), and azobisisobutyronitrile (AIBN) (3wt%) to obtain the raw material system.

[0096] 3. Add the prepared raw material system to the impregnation tank, select three layers of PP / PE / PP (thickness 100μm, width 0.8m, pore size 10nm) as the matrix and PET (100μm) as the covering material, set the coating speed to 0.5m / s, and after coating, obtain an unpolymerized anion exchange membrane roll.

[0097] 4. After coating, the anion exchange membrane is rolled up and placed in a vacuum oven for polymerization at 80°C for 8 hours. After polymerization, it is placed in warm water at 50°C for thermal swelling treatment to obtain the anion exchange membrane.

[0098] Example 2

[0099] The preparation method of the anion exchange membrane provided in this embodiment is basically the same as that in Example 1, except that:

[0100] In step 1), 10 kg of dimethylaminoethyl methacrylate (DMAEMA) and 20 kg of isopropanol are mixed and then 8.6 kg of bromopropane is added. The mixture is reacted at 50 °C for 8 h to obtain a solution containing ammonium monomers.

[0101] Example 3

[0102] The anion exchange membrane provided in this embodiment is prepared by a method including the following steps:

[0103] 1. Mix 10 kg of 3-DMAPPMA with 10 kg of butanol, then add 8.0 kg of bromobutane and react at 40 °C for 8 h to obtain a solution of ammonium-modified monomer.

[0104] 2. Prepare a polymerizable mixture by dissolving the ammonium monomer (70wt%), ethylene glycol dimethacrylate (EGDMA) (15wt%), phthalate (10wt%), and azobisisobutyronitrile (5wt%) to obtain the raw material system.

[0105] 3. Add the prepared raw material system to the impregnation tank, select double-layer PP / PE (thickness 90μm, width 0.8m, pore size 1nm) as the matrix and cellulose membrane (100μm) as the covering material, set the coating speed to 0.5m / s, and after coating, obtain an unpolymerized anion exchange membrane roll.

[0106] 4. After coating, the anion exchange membrane is rolled up and placed in a vacuum oven at 100°C for polymerization for 6 hours. After polymerization, it is placed in warm water at 40°C for thermal swelling treatment to obtain the anion exchange membrane.

[0107] Example 4

[0108] The anion exchange membrane provided in this embodiment is prepared by a method including the following steps:

[0109] 1. Mix 10 kg of 3-DMAPPMA with 30 kg of propanol, then add 8.3 kg of bromoethane and react at 50 °C for 6 h to obtain a solution containing ammonium monomers.

[0110] 2. Prepare a polymerizable mixture by dissolving the ammonium monomer (89 wt%), ethylene glycol dimethacrylate (EGDMA) (5 wt%), phthalate (5 wt%), and benzoyl peroxide (1 wt%) to obtain the raw material system.

[0111] 3. Add the prepared raw material system to the impregnation tank, select three layers of PP / PE / PP (thickness 120μm, width 0.8m, pore size 1000nm) as the matrix and polyimide membrane (100μm) as the covering material, set the coating speed to 0.5m / s, and after coating, obtain an unpolymerized anion exchange membrane roll.

[0112] 4. After coating, the anion exchange membrane is rolled up and placed in a vacuum oven for polymerization at 80°C for 8 hours. After polymerization, it is placed in warm water at 60°C for thermal swelling treatment to obtain the anion exchange membrane.

[0113] Example 5

[0114] The preparation method of the anion exchange membrane provided in this embodiment is basically the same as that in Example 1, except that:

[0115] In step 3), the thickness of the three-layer PP / PE / PP is 85μm, and the pore size of the three-layer PP / PE / PP is 1200nm.

[0116] Example 6

[0117] The preparation method of the anion exchange membrane provided in this embodiment is basically the same as that in Example 1, except that:

[0118] In step 2), a polymerizable mixture is prepared by mixing 90 wt% ammonium monomer, 4 wt% ethylene glycol dimethacrylate (EGDMA), 4 wt% dioctyl adipate (DOA), and 2 wt% azobisisobutyronitrile (AIBN) to obtain the raw material system.

[0119] Example 7

[0120] The preparation method of the anion exchange membrane provided in this embodiment is basically the same as that in Example 1, except that:

[0121] In step 4, the polymerization reaction is carried out at a temperature of 75°C for 9 hours.

[0122] Example 8

[0123] The preparation method of the anion exchange membrane provided in this embodiment is basically the same as that in Example 1, except that:

[0124] In step 4, no thermal swelling treatment is performed.

[0125] Comparative Example 1

[0126] The method for preparing the anion exchange membrane provided in this comparative example includes the following steps:

[0127] 1. Mix 8.9 kg of chloromethylstyrene with 20 kg of isopropanol, then add 7.9 kg of bromopropane and react at 50 °C for 8 h to obtain a solution containing ammonium monomer.

[0128] 2. Prepare a polymerizable mixture by dissolving the ammonium compound (80 wt%), divinylbenzene (10 wt%), dioctyl adipate (DOA) (7 wt%), and azobisisobutyronitrile (AIBN) (3 wt%) to obtain the raw material system.

[0129] 3. Add the prepared raw material system to the impregnation tank, select three layers of PP / PE / PP (thickness 100μm, width 0.8m, pore size 10nm) as reinforcing material and PET (100μm) as covering material, set the coating speed to 0.5m / s, and after coating, obtain an unpolymerized anion exchange membrane roll.

[0130] 4. Place the coated anion exchange membrane roll into a vacuum oven and heat it at 80°C for 8 hours for polymerization. After polymerization, place it in 50°C warm water for thermal swelling to obtain the formed anion exchange membrane.

[0131] Comparative Example 2

[0132] The preparation method of the anion exchange membrane provided in this comparative example is basically the same as that in Example 2, except that:

[0133] Excluding step 1), in step 2, the ammonium monomer is replaced with chloromethylstyrene and ethylene glycol dimethacrylate is replaced with divinylbenzene.

[0134] Test case

[0135] The antioxidant properties of the anion exchange membranes provided in all embodiments and comparative examples were evaluated, mainly by testing their surface resistance and migration number in sodium hypochlorite solutions of a certain concentration at different times.

[0136] 1. Sodium hypochlorite solution soaking treatment

[0137] Three small circular pieces with a diameter of 8 cm were cut from the anion exchange membrane prepared by continuous industrialization. These pieces were then immersed in a 1.0 wt% sodium hypochlorite solution. The membrane surface resistance and mobility number were measured at 0, 120 h, 240 h, 480 h, and 720 h, respectively. The test results are shown in Table 1.

[0138] 2. Film surface resistance test

[0139] An ion-exchange membrane was clamped in a two-chamber chamber containing an Ag / AgCl electrode. Both sides of the ion-exchange membrane were filled with a 0.5 mol / L NaCl aqueous solution. The resistance between the electrodes was measured using an electrochemical workstation (Ivium-N-Stat) at 25°C. The membrane surface resistance was calculated based on the difference between the resistance between the electrodes and the resistance between the electrodes without the ion-exchange membrane. It should be noted that the ion-exchange membrane used in the above determination was pre-equilibrated in a 0.5 mol / L NaCl aqueous solution. The test results are shown in Table 1.

[0140] 3. Migration Number Test

[0141] The ion exchange membrane was sandwiched in a double-chamber tank equipped with an Ag / AgCl electrode. The two sides were filled with 0.1 mol / L NaCl and 0.5 mol / L NaCl, respectively. Without applying current, the potential difference between the two chambers was measured through the Ag / AgCl electrode while the solutions in the two chambers were stirred. The migration number of Cl ions by the anion exchange membrane was then determined. The test results are shown in Table 1.

[0142] Table 1

[0143]

[0144]

[0145] As shown in Table 1, the anion exchange membranes provided in Examples 1-8 of this invention, after being immersed in sodium hypochlorite solution for different durations, still maintain low membrane surface resistance and high migration number. Specifically, without treatment, the resistance of the anion exchange membranes provided in Examples 1-8 is no higher than 7.21 Ω·cm. 2 The migration number is not less than 0.968, and after being treated with 1% sodium hypochlorite solution at room temperature for a certain period of time, the anion exchange membranes provided in Examples 1-8 still maintain relatively excellent performance.

[0146] In Example 8, the anion exchange membrane exhibited an increase in resistance at room temperature and in a 1% sodium hypochlorite solution for 720 hours, reaching 22.09 Ω·cm. 2 However, the migration number remains at 0.701. Therefore, considering all factors, the performance of the anion exchange membrane provided in Example 8 is better than that of the anion exchange membranes provided in Comparative Example 1 and Comparative Example 2.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An anion exchange membrane, characterized in that, Polymers including those having the structural units shown in Formula I: Equation I In Formula I, A is C, N or O, Cn is a C1 to C5 alkylene group, and R1, R2 and R3 are each independently selected from C1 to C6 alkyl groups; The polymer does not contain carbon-carbon double bonds or benzene rings.

2. The anion exchange membrane according to claim 1, characterized in that, The polymer is a cross-linked polymer comprising the structural unit shown in Formula I.

3. The anion exchange membrane according to claim 1 or 2, characterized in that, The anion exchange membrane comprises a polyolefin porous membrane and the polymer filling the pores of the polyolefin porous membrane.

4. The anion exchange membrane according to claim 3, characterized in that, The thickness of the polyolefin porous membrane is 90~120μm; And / or, the pore size of the polyolefin porous membrane is 1~1000 nm.

5. A method for preparing an anion exchange membrane according to any one of claims 1-4, characterized in that, Includes the following steps: A raw material system including the monomer shown in Formula II is coated onto a substrate, and a polymerization reaction is initiated to obtain the anion exchange membrane. Formula II.

6. The preparation method according to claim 5, characterized in that, The raw material system also includes crosslinking agents, initiators, and / or plasticizers.

7. The preparation method according to claim 5 or 6, characterized in that, The raw material system comprises 70wt% to 89wt% of the monomer shown in Formula II, 5wt% to 15wt% of the crosslinking agent, 5wt% to 10wt% of the plasticizer, and 1wt% to 5wt% of the initiator.

8. The preparation method according to claim 6, characterized in that, The crosslinking agent includes aliphatic crosslinking agents; And / or, the plasticizer includes one or more of phthalates and fatty acid esters; And / or, the initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

9. The preparation method according to claim 8, characterized in that, The aliphatic crosslinking agent includes ethylene glycol dimethacrylate.

10. The preparation method according to claim 5 or 6, characterized in that, The polymerization reaction is carried out at a temperature of 80-100℃ for 6-8 hours.

11. The preparation method according to claim 5 or 6, characterized in that, After the polymerization reaction is completed, the polymerization product is subjected to thermal swelling treatment in water at 40~60°C.

12. The preparation method according to claim 5 or 6, characterized in that, The substrate is selected from polyolefin porous membranes.

13. The preparation method according to claim 12, characterized in that, The thickness of the polyolefin porous membrane is 90~120μm, and / or the pore size of the polyolefin porous membrane is 1~1000nm.

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