A method and apparatus for preparing a bipolar membrane

Abstract

The application discloses a preparation method and device of a bipolar membrane, and the preparation method comprises the following steps: 1) treating a base film by using a plasma surface treatment machine; 2) immersing the base film into a catalyst solution and then drying; 3) coating a positive film liquid on one side of the base film and drying; and 4) coating a negative film liquid on the other side of the base film and drying. By improving the surface polarity of the base material in the plasma treatment machine, the positive and negative film layers of the bipolar membrane are more firmly bonded. The application realizes full automation, has low energy consumption and low production cost, and has stable product quality. The application effectively solves the problems of easy blistering, easy peeling and breaking of the traditional bipolar membrane, greatly improves the operation efficiency of the bipolar membrane, and reduces the manufacturing cost and equipment investment cost of the bipolar membrane.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bipolar membrane production, and particularly relates to a preparation method and device of a bipolar membrane. BACKGROUND

[0002] Bipolar membranes (BPMs) are a kind of special ion exchange membranes composed of anion exchange layer and cation exchange layer. Due to its unique water dissociation performance, bipolar membranes play an irreplaceable role in the fields of chemical industry, environmental protection, energy storage, food processing, etc. In the past 20 years, the commercial market of bipolar membranes has been expanding, and the research on bipolar membranes has also been rapidly developing.

[0003] Bipolar membranes are a new type of ion exchange composite membrane, which is usually composed of a cation exchange layer (CEL), an intermediate layer and an anion exchange layer (AEL). The intermediate layer is usually several nanometers thick, electrically neutral and contains a catalyst. Under the action of a direct current electric field, the intermediate layer of the bipolar membrane can dissociate water to produce H + and OH - . Subsequently, the generated H+ and OH- migrate to the anode and cathode, respectively, driven by the potential difference between the anode and cathode. At the same time, the water in the solution on both sides of the bipolar membrane will enter the intermediate layer through the AEL and CEL to replenish the consumption of water. The working principle of bipolar membranes is that different components in the membrane can be specially designed to produce greater differences in transmission or reaction, and has the advantages of simple process, good selectivity, mild operating conditions, etc. Therefore, it has broad and potential applications in the fields of pollution control, resource recovery, chemical production, etc. In particular, bipolar membrane electrodialysis (BMED) technology has unique advantages in acid and alkali production and energy conversion, and is an irreplaceable process.

[0004] At present, commercial bipolar membranes generally have high resistance, low current efficiency, easy cracking of anode and cathode membranes, short service life and high energy consumption.

[0005] Chinese patent CN 114432894 A discloses a preparation process of a bipolar membrane. In the preparation process, sulfonated polyether sulfone (SPES) is dissolved in DMF solvent and then scraped into a film as the anode membrane surface of the bipolar membrane. Molybdenum sulfide (MoS2) catalyst is coated in the middle. Polyethylene (PE) and polyvinylidene fluoride (PVDF) are dissolved in dimethyl sulfoxide (DMSO) and coated on the anode membrane surface with the catalyst. After drying, trimethylamine is aminated, and finally the bipolar membrane is obtained. The invention has a complex process, the anode and cathode layers are easy to peel off, and the service life has not been verified. SUMMARY

[0006] In view of the above problems existing in the prior art, the purpose of the present application is to provide a preparation method and device of bipolar membrane. The process can quickly, efficiently, and continuously produce bipolar membrane at low cost, and the prepared bipolar membrane has low resistance, high current efficiency, and long service life.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] A method for preparing a bipolar membrane, comprising the following steps:

[0009] 1) treating the base film with a plasma surface treatment machine;

[0010] 2) immersing the base film into a catalyst solution, and then drying;

[0011] 3) coating a positive membrane liquid on one side of the base film, and drying;

[0012] 4) coating a negative membrane liquid on the other side of the base film, and drying.

[0013] Preferably, the base film is a polyethylene terephthalate base film.

[0014] The base film is ionized by a high-frequency electric field of the plasma surface treatment machine, and the ionized gas generates plasma, which reacts with the surface of the polyethylene terephthalate to break part of the molecular bonds on the surface of the polyethylene terephthalate, generate polar bonds, and improve the surface polarity and surface tension of the polyethylene terephthalate. The wettability and adhesion of the surface of the polyethylene terephthalate are strengthened, so that the catalyst is more easily immersed into the polyethylene terephthalate base film, and the positive and negative membrane materials of the bipolar membrane are more easily adhered to the surface of the polyethylene terephthalate base film.

[0015] Preferably, after the base film is taken out in step 2), the excess catalyst solution is squeezed off and then dried.

[0016] Preferably, after the base film is taken out in step 2), the excess catalyst solution is squeezed off by a squeezing roller. The base film immersed in the catalyst is squeezed by the squeezing roller to remove the excess catalyst, so that the phenomenon of catalyst dripping is avoided in the subsequent process.

[0017] Preferably, in step 2), the base film is dried at a temperature of 40-80°C, preferably 50-65°C.

[0018] Preferably, the catalyst is an organic tin catalyst.

[0019] Preferably, the organic tin catalyst is selected from dibutyltin dilaurate, dibutyltin dibutyrate, stannous octoate, dibutyltin diacetate, and dioctyltin oxide; preferably, the organic tin catalyst is dibutyltin dibutyrate and dioctyltin oxide.

[0020] Preferably, a surfactant is also added into the catalyst solution.

[0021] Preferably, the surfactant is selected from fatty acid glyceride, polysorbate, sodium xylene sulfonate, polyoxyethylene fatty acid ester; the surfactant enables the organic tin catalyst to be uniformly formed into a catalyst solution with water.

[0022] Preferably, the mass content of the organic tin catalyst is 2-15%, preferably 5-12%, and the mass content of the surfactant is 0.01-0.15%, preferably 0.05-0.12%, based on the total mass of the catalyst solution being 100%.

[0023] Preferably, the positive membrane material solution comprises sulfonated polyphenyl ether and a solvent, wherein the solvent is preferably DMF.

[0024] Preferably, in step 3), drying is carried out at a temperature of 50-100°C, preferably 60-80°C.

[0025] Preferably, the negative membrane material solution comprises aminated polyphenyl ether and a solvent, wherein the solvent is chlorobenzene or DMF.

[0026] Preferably, in step 4), drying is carried out at a temperature of 60-80°C.

[0027] The application also provides a preparation device for a bipolar membrane, comprising a unwinding roller, a plasma surface treatment machine, a catalyst infiltration tank, an oven one, a coating roller one, an oven two, a coating roller two, and a winding roller connected in sequence.

[0028] The unwinding roller is provided with a base film, and the thickness of the base film is 60-120μm and the porosity is 60-90%.

[0029] The catalyst infiltration tank is inverted trapezoidal, and the bottom of the catalyst infiltration tank is provided with an infiltration roller, and the outlet of the catalyst infiltration tank is connected with a pressing roller,

[0030] The pressure of the pressing roller is 5-12kg / ㎝2, and the infiltration speed of the base film is 0.2-1m / min.

[0031] Preferably, the pressure of the pressing roller is 7-10kg / ㎝2.

[0032] Preferably, the infiltration speed of the non-woven fabric is 0.4-0.8m / min.

[0033] The coating roller one can be a transfer coating device, a doctor blade coating device, and a slit coating device. The coating thickness is 80-140μm.

[0034] Preferably, the coating one is a transfer coating device.

[0035] Preferably, the coating thickness is 100-120 μm;

[0036] The second coating roller can be a transfer coating roller, a doctor blade coating roller or a slot coating roller. The coating thickness is 20-50 μm.

[0037] Preferably, the second coating roller is a transfer coating device.

[0038] Preferably, the coating thickness of the second coating roller is 25-40 μm.

[0039] The dried membrane is wound by a winding roller to obtain a bipolar membrane, wherein the winding tension of the winding roller is 120-200 N / M, and the winding diameter is 10-40 cm.

[0040] Preferably, the tension of the winding roller is 150-180 n / m.

[0041] Preferably, the winding diameter is 15-30 cm.

[0042] Compared with the prior art, the present application has the following advantages:

[0043] 1. The base film is treated by a plasma surface treatment machine, so that the bonding of the cathode and anode films is more firm and is not easy to bubble and peel off.

[0044] 2. The use of a base material to infiltrate a catalyst increases the content of the catalyst and enhances the efficiency of the catalyst.

[0045] 3. The use of a double-sided coating process technology of the base film can adjust the coating thickness of the cathode and anode films, and can maximize the performance of the bipolar membrane.

[0046] The continuous production process of the present application can realize rapid and efficient continuous production and automatic production of the bipolar membrane. The bipolar membrane has good performance, low production cost and stable product quality, and the cathode and anode films are not easy to peel off. The present application effectively solves the problems in the current bipolar membrane industry, such as low efficiency, short service life, high production cost and unstable product quality, and greatly reduces the production difficulty and equipment investment cost. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 Figure 1 is a schematic diagram of a device for preparing a bipolar membrane by a double-sided coating method according to Example 1.

[0048] Figure 1 is a schematic diagram of a device for preparing a bipolar membrane by a double-sided coating method according to Example 1.

[0049] 2, a plasma surface treatment machine

[0050] 3, a catalyst infiltration tank

[0051] 4, an oven

[0052] 5, a coating roller

[0053] 6, Oven II

[0054] 7, Coating roller II

[0055] 8, Winding roller DETAILED DESCRIPTION

[0056] The technical solutions of the present application will be further described in detail below in combination with the drawings and examples, but the present application is not limited thereto.

[0057] The catalyst preparation process comprises the following steps:

[0058] A certain amount of deionized water is placed in a measuring cup, then dibutyltin dibutyrate is added, stirred by a magnetic stirrer for 10 minutes, then dioctyltin oxide is added, and finally sodium dimethylxylene sulfonate is added, and after stirring for 30 minutes, a milky water emulsion is formed; wherein the mass fraction of dibutyltin dibutyrate is 10%, the mass fraction of dioctyltin oxide is 5%, and the mass fraction of sodium dimethylxylene sulfonate is 0.1%.

[0059] The anode membrane material liquid preparation process comprises the following steps:

[0060] Raw materials: sulfonated polyphenyl ether, DMF, chlorobenzene.

[0061] The preparation process is as follows:

[0062] Take 35 parts by mass of sulfonated polyphenyl ether, place it in a beaker, add 35 parts by mass of DMF, and at the same time add 30 parts by mass of chlorobenzene, heat to 45℃, and stir for 30 minutes to obtain an anode membrane coating solution.

[0063] The cathode membrane material liquid preparation process comprises the following steps:

[0064] Raw materials: brominated polyphenyl ether, dimethylamino ethanol, DMF

[0065] The preparation process is as follows:

[0066] The 50 parts by mass of brominated polyphenyl ether solid is crushed with a crusher, then dissolved in 30 parts by mass of DMF, the dissolved brominated polyphenyl ether and DMF mixture is placed in a beaker, and 20 parts by mass of dimethylamino ethanol is added dropwise into the mixture, and placed in a shaker for amination, with an amination temperature of 50℃ and a time of 55 minutes, and finally obtaining an aminated polyphenyl ether solution.

[0067] The plasma surface treatment machine in the example of the present application is a Shenzhen Hongzhan automatic plasma surface treatment machine.

[0068] Example 1

[0069] A device for preparing a bipolar membrane by a double-sided coating method, as shown in Figure 1As shown, including the sequence connection of unwinding roll 1 and plasma surface treatment machine 2, catalyst infiltration tank 3, oven 4, coating roll 1 5, oven 2 6, coating roll 2 7 and winding roll 8.

[0070] The length of the unwinding roll is 30 cm, the length of the catalyst infiltration tank is 40 cm, the bottom width is 10 cm, and the pressure of the upper extrusion roller of the catalyst infiltration tank is 8 kg / m2.

[0071] The length of the catalyst drying oven 1 is 3 m, and the oven temperature is 50℃.

[0072] The length of the coating roll 1 is 40 cm, and the coating method is transfer coating.

[0073] The length of the oven 2 is 5 m, and the oven temperature is set to 60℃.

[0074] The length of the coating roll 2 is 40 cm, and the coating method is transfer coating.

[0075] The length of the winding roll is 40 cm.

[0076] Example 2

[0077] A preparation method of a bipolar membrane, using the device described in Example 1, the steps include:

[0078] 1) The polyethylene terephthalate non-woven fabric base film from the unwinding roll enters the catalyst infiltration tank after passing through the plasma surface treatment machine, infiltrates the catalyst solution, the infiltration speed is 0.5 m / min, then passes through the extrusion roller to extrude and remove the excess catalyst, and then enters the oven 1 for drying, the oven temperature is 52℃.

[0079] 2) The base film after passing through the oven 1 is coated with a positive film solution by the positive film coating roll, the coating method is transfer coating, and the coated base film enters the polymerization oven for polymerization, the temperature of the polymerization oven is 55℃.

[0080] 3) After the positive film layer is polymerized after passing through the polymerization oven, the negative film solution is coated on the other side of the base film by the negative film coating roll, the coating method is transfer coating, and the coated negative film layer enters the oven 2 for polymerization under the condition of 55℃.

[0081] 4) After the negative film layer is polymerized, it enters the winding roll for winding, and after winding, the bipolar membrane is completed.

[0082] During the film making process, samples were taken at 20 min, 40 min and 60 min respectively after the device started running, a total of three samples were taken to test the performance indicators of the bipolar membrane, and the results are shown in Table 1.

[0083] Table 1 Test results of three samples of Example 2

[0084]

[0085] Comparative Example 1

[0086] The main difference between the device of Comparative Example 1 and the device of Example 1 is that there is no plasma surface treatment machine. The preparation method of a bipolar membrane includes the following steps:

[0087] 1) The polyethylene terephthalate non-woven fabric base film from the unwinding roller enters the catalyst immersion tank, immerses in the catalyst solution, and the immersion speed is 0.5 m / min, then passes through the extrusion roller for extrusion, and after extruding the excess catalyst, enters Oven 1 for drying, and the temperature of Oven 1 is 52°C.

[0088] 2) The base film after passing through Oven 1 is coated with a positive membrane solution by the positive membrane coating roller, and the coating method is transfer coating. The base film after coating enters the polymerization oven for polymerization, and the temperature of the polymerization oven is 55°C.

[0089] 3) After passing through the polymerization oven, the positive membrane layer is polymerized, and then the negative membrane solution is coated on the other side of the base film by the negative membrane coating roller, and the coating method is transfer coating. After the negative membrane layer is coated, it enters Oven 2 for polymerization at 55°C again.

[0090] 4) After the negative membrane layer is polymerized, it enters the winding roller for winding, and after winding is completed, the preparation of the bipolar membrane is completed.

[0091] During the film preparation process, samples are taken at 20 min, 40 min, and 60 min after the device starts running, respectively, for testing, and a total of three samples are taken to test the performance indicators of the bipolar membrane. The results are shown in Table 2.

[0092] Table 2 Performance of samples of Comparative Example 1

[0093]

[0094] From the data of Example 2 and Comparative Example 1, we found that the bipolar membrane made without the plasma treatment machine has a significant gap in hydrolysis voltage, current efficiency, and burst strength compared to Example 2.

[0095] Examples 3-5

[0096] The same method as in Example 2 is used to prepare the bipolar membrane, except that the coating speed and oven temperature are changed. See Table 3 for details. Samples are taken at 60 min for testing, and the results are shown in Table 3.

[0097] Table 3 Performance testing of samples of Examples 3-5

[0098]

[0099] The process and device for continuously manufacturing the bipolar membrane realize efficient and stable manufacturing, and solve the problems of low current efficiency, high hydrolysis power and low blasting strength of the bipolar membrane of other processes.

[0100] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application. However, these corresponding changes and modifications shall belong to the protection scope of the claims of the present application.

Claims

1. A method for producing a bipolar membrane, characterized by, The method comprises the following steps: 1) treating the base film with a plasma surface treatment machine; 2) immersing the base film in a catalyst solution and then drying; 3) coating a positive film solution on one side of the base film and drying; 4) coating a negative film solution on the other side of the base film and drying; The base film is a polyethylene terephthalate base film; The catalyst is an organic tin catalyst.

2. The production method according to claim 1, characterized by, In step 2), the base film is squeezed to remove excess catalyst solution after being taken out and then dried.

3. The production method according to claim 2, characterized by, In step 2), the base film is squeezed to remove excess catalyst solution by a squeezing roller after being taken out, and the base film immersed in the catalyst is squeezed to remove excess catalyst by the squeezing roller, so that the phenomenon of catalyst dripping is avoided in the subsequent process.

4. The method of claim 1, wherein, In step 2), the base film is dried at a temperature of 40-80℃.

5. The preparation method according to claim 4, characterized in that, In step 2), the base film is dried at a temperature of 50-65℃.

6. The preparation method according to claim 1, characterized in that, The organic tin catalyst is dibutyltin dilaurate, dibutyltin dibutyrate, stannous octoate, dibutyltin diacetate or dioctyltin oxide.

7. The preparation method according to claim 1, characterized in that, The mass content of the organic tin catalyst is 2-15% based on the total mass of the catalyst solution.

8. The production method according to claim 7, characterized by, The mass content of the organic tin catalyst is 5-12% based on the total mass of the catalyst solution.

9. The method of claim 1, wherein, The catalyst solution further comprises a surfactant.

10. The method of claim 9, wherein, The surfactant is a fatty acid glyceride, polysorbate, sodium xylene sulfonate or polyoxyethylene fatty acid ester.

11. The preparation method according to claim 9, characterized in that, The mass content of the surfactant is 0.01-0.15% based on the total mass of the catalyst solution.

12. The method of claim 11, wherein, The mass content of the surfactant is 0.05-0.12% based on the total mass of the catalyst solution.

13. The method of claim 1, wherein, The positive film solution comprises sulfonated polyphenylene ether and a solvent.

14. The method of claim 13, wherein, The solvent in the positive film solution is one or more of DMF or chlorobenzene.

15. The method of claim 1, wherein, In step 3), the drying is performed at a temperature of 50-100℃.

16. The method of claim 15, wherein, In step 3), the drying is performed at a temperature of 60-80℃.

17. The method of claim 1, wherein, The negative film solution comprises aminated polyphenylene ether and a solvent, wherein the solvent is chlorobenzene or DMF.

18. The method of claim 1, wherein, In step 4), the drying is performed at a temperature of 60-80℃.

19. An apparatus for the production of a bipolar membrane by the process according to any one of claims 1 to 18, characterized in that The preparation method comprises sequentially connected unwinding roller, plasma surface treatment machine, catalyst immersion tank, oven one, coating roller one, oven two, coating roller two and winding roller. The base film is placed on the unwinding roller, and the thickness of the base film is 60-120μm and the porosity is 60-90%.

20. The apparatus of claim 19, wherein, The catalyst immersion tank is inverted trapezoidal, and the bottom of the catalyst immersion tank is provided with an immersion roller, and the outlet of the catalyst immersion tank is connected with a squeezing roller.

21. The apparatus of claim 19, wherein, The pressure of the squeeze roller is 5-12 kg / cm 2 The immersion speed of the base film is 0.2-1 m / min.

22. The apparatus of claim 21, wherein, The pressure of the extrusion roller is 7-10 kg / cm 2 .

23. The apparatus of claim 21, wherein, The immersion speed of the base film is 0.4-0.8m / min.

24. The apparatus of claim 19, wherein, The coating roller one is one of transfer coating device, doctor blade coating device and slot coating device.

25. The apparatus of claim 24, wherein, The coating roller one is a transfer coating device.

26. The apparatus of claim 19, wherein, The coating thickness of the coating roller one is 80-140μm.

27. The apparatus of claim 26, wherein, The coating thickness of the coating roller one is 100-120μm.

28. The apparatus of claim 19, wherein, The coating roller two is one of transfer coating roller, doctor blade coating roller and slot coating roller.

29. The apparatus of claim 28, wherein, The coating roller two is a transfer coating device.

30. The apparatus of claim 19, wherein, The coating thickness of the coating roller two is 20-50μm.

31. The apparatus of claim 30, wherein, The coating thickness of the coating roller two is 25-40μm.

32. The apparatus of claim 19, wherein, The dried membrane is wound by a winding roller to obtain a bipolar membrane, wherein the winding tension of the winding roller is 120-200 N / m, and the winding diameter is 10-40 cm.

33. The apparatus of claim 32, wherein, The winding tension of the winding roller is 150-180 N / m.

34. The apparatus of claim 32, wherein, The winding diameter is 15-30 cm.

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