Online continuous production process of separation membrane and separation membrane

Abstract

The invention provides an online continuous production process of a separation membrane and the separation membrane, and particularly relates to the technical field of separation membranes. The online continuous production process of the separation membrane comprises the following steps: coating an end-capping reagent solution on a separation membrane base material which is subjected to interfacial polymerization reaction, solvent washing and first drying by coating equipment, feeding the separation membrane base material into a reaction drying tunnel for end capping, and finally performing post-treatment by a transmission roller group to obtain the separation membrane. Wherein an end-capping reagent in the end-capping reagent solution comprises a first end-capping reagent and a second end-capping reagent; the first end-capping reagent comprises at least one of methylamine, ethylamine, aniline, 2-hydroxyethylamine, diethanol amine, p-aminophenol, ortho-aminophenol and m-aminophenol; the second end-capping reagent comprises a pyridine compound. The whole process can be directly integrated on the basis of an existing production line, continuous and large-scale preparation is achieved, off-line treatment is not needed, the production efficiency is high, and the batch stability is good.

Description

Technical Field

[0001] This invention relates to the technical field of separation membranes, and in particular to an online continuous production process for separation membranes and a separation membrane. Background Technology

[0002] Separation membranes are widely used in fields with extremely high water quality requirements, such as electronics and pharmaceuticals. Their performance hinges on the density and surface charge state of the polyamide separation layer. However, in the traditional interfacial polymerization process, incomplete monomer reactions result in a large number of residual carboxyl groups on the membrane surface. At normal operating pH, these carboxyl groups partially ionize into carboxylate ions, causing electrostatic repulsion, membrane pore expansion, and decreased selectivity. Simultaneously, they readily adsorb cationic and colloidal pollutants, exacerbating membrane fouling. Furthermore, existing membrane products generally lack effective end-capping treatments, leading to the long-term presence of these active functional groups, becoming a core defect restricting the improvement of organic matter retention and antifouling performance.

[0003] Although existing technologies have attempted to improve membrane performance through methods such as end-capping with multifunctional reagents or surface grafting, they generally suffer from problems such as large flux losses, complex processes, and reliance on offline soaking, making them difficult to integrate with continuous production lines and resulting in low levels of industrial application. In particular, some modification methods require the introduction of additional high-cost materials or special conditions (such as light exposure or high temperatures), which is not conducive to large-scale stable production.

[0004] Therefore, there is an urgent need for an end-capping technology that can efficiently neutralize surface charge, reduce and stabilize membrane pore structure, and can be implemented online and is suitable for continuous manufacturing, so as to achieve low-cost, large-scale preparation of high-performance reverse osmosis membranes.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an online continuous production process for a separation membrane and a separation membrane, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: The first aspect of the present invention provides an online continuous production process for a separation membrane. A separation membrane substrate that has undergone interfacial polymerization, solvent washing, and initial drying is coated with a capping agent solution using a coating device, then enters a reaction drying tunnel for capping. Finally, post-processing by a transfer roller group yields the separation membrane. The capping agent solution comprises a first capping agent and a second capping agent. The first capping agent comprises at least one of methylamine, ethylamine, aniline, 2-hydroxyethylamine, diethanolamine, p-aminophenol, o-aminophenol, and m-aminophenol. The second capping agent comprises a pyridine compound.

[0008] Furthermore, the pyridine compound includes at least one of 4-dimethylaminopyridine, 2-dimethylaminopyridine, and 4-dimethylamino-3-methylpyridine, preferably 4-dimethylaminopyridine.

[0009] Preferably, the concentration of the second capping agent is 0.01~0.1wt%.

[0010] Preferably, the first capping agent includes at least one of aniline, p-aminophenol, and m-aminophenol.

[0011] Preferably, the concentration of the first capping agent is 0.05~0.15wt%.

[0012] Furthermore, the solvent in the capping agent solution includes at least one of ethanol, isopropanol, or acetone.

[0013] Preferably, the temperature of the sealing end is 80~100℃.

[0014] Preferably, the sealing time for applying the sealing agent solution is 30-60 seconds.

[0015] Furthermore, the preparation process of the separation membrane substrate is as follows: the polysulfone membrane is first passed through an aqueous solution for 20-40 seconds, then the excess aqueous phase is removed, and one of its surfaces is brought into contact with the oil phase to carry out an interfacial polymerization reaction. After rinsing and first drying, the separation membrane substrate is obtained.

[0016] Furthermore, the aqueous solution is a m-phenylenediamine solution.

[0017] Preferably, the oil phase is a pyromellitic acid chloride solution.

[0018] Preferably, the interfacial polymerization reaction takes 20-40 seconds.

[0019] Further, rinse with the same solvent used in the oil phase.

[0020] Preferably, the solvent grade in the oil phase includes Isopar G.

[0021] Furthermore, the temperature of the first drying process is 90~110℃, and the time is 60~90s.

[0022] Furthermore, the post-treatment includes sequential alkaline washing, hot water rinsing, and a second drying.

[0023] A second aspect of the present invention provides a separation membrane, which is produced using the aforementioned online continuous production process.

[0024] Furthermore, the absolute value of the Zeta potential is less than 10 mV under pH conditions of 7.5–8.0.

[0025] Preferably, when tested in a mixed aqueous solution of 2000 ppm sodium chloride and 10 ppm isopropanol, the pressure is 225 psi, the test temperature is 25°C, the pH is 7.5-8, the desalination rate is ≥99.8%, and the isopropanol retention rate is not less than 96.2%.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects: The online continuous production process provided by this invention involves a first capping agent that reacts with residual carboxyl groups to generate an electrically neutral amide structure, significantly reducing the negative charge density on the membrane surface, suppressing pore size fluctuations caused by pH changes, and enhancing the steric hindrance retention capacity for neutral organic matter. The second capping agent acts as a reaction promoter or synergistic stabilizer, enhancing the efficiency and uniformity of the capping reaction. The entire process can be directly integrated into existing production lines, enabling continuous and large-scale preparation without offline processing. It boasts high production efficiency and good batch stability, achieving not only high desalination rates, high organic matter removal rates, and excellent antifouling performance, but also avoiding flux losses caused by multifunctional crosslinking agents. It is fully compatible with existing industrial production lines and possesses the advantages of high efficiency, stability, and scalability.

[0027] The separation membrane provided by this invention effectively reduces the ionization capacity of residual carboxyl groups on the surface of the polyamide functional layer through an online continuous end-capping process. This significantly reduces the negative charge density on the membrane surface, suppresses membrane pore expansion caused by electrostatic repulsion, and results in a denser and narrower pore structure. Consequently, it greatly improves the retention rate of small-molecule dissolved organic matter (such as isopropanol), meeting the stringent TOC requirements in the preparation of electronic-grade ultrapure water. Simultaneously, the electrically neutralized surface weakens the interaction with cations and positively charged colloids, reducing the adsorption and bridging effects of pollutants on the membrane surface, significantly enhancing antifouling capabilities, extending membrane lifespan, and improving flux recovery after chemical cleaning. This membrane achieves synergistic optimization of selectivity and stability while maintaining high desalination rate and good water flux, making it suitable for high-end water treatment applications. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 The pore size distribution of the separation membrane obtained in Test Example 2 is shown. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.

[0032] The first aspect of the present invention provides an online continuous production process for a separation membrane. A separation membrane substrate that has undergone interfacial polymerization, solvent washing, and initial drying is coated with a capping agent solution using a coating device, then enters a reaction drying tunnel for capping. Finally, post-processing by a transfer roller group yields the separation membrane. The capping agent solution comprises a first capping agent and a second capping agent. The first capping agent comprises at least one of methylamine, ethylamine, aniline, 2-hydroxyethylamine, diethanolamine, p-aminophenol, o-aminophenol, and m-aminophenol. The second capping agent comprises a pyridine compound.

[0033] The online continuous production process provided by this invention involves a first capping agent that reacts with residual carboxyl groups to generate an electrically neutral amide structure, significantly reducing the negative charge density on the membrane surface, suppressing pore size fluctuations caused by pH changes, and enhancing the steric hindrance retention capacity for neutral organic matter. The second capping agent acts as a reaction promoter or synergistic stabilizer, enhancing the efficiency and uniformity of the capping reaction. The entire process can be directly integrated into existing production lines, enabling continuous and large-scale preparation without offline processing. It boasts high production efficiency and good batch stability, achieving not only high desalination rates, high organic matter removal rates, and excellent antifouling performance, but also avoiding flux losses caused by multifunctional crosslinking agents. It is fully compatible with existing industrial production lines and possesses the advantages of high efficiency, stability, and scalability.

[0034] Furthermore, the pyridine compound includes at least one of 4-dimethylaminopyridine, 2-dimethylaminopyridine, and 4-dimethylamino-3-methylpyridine, preferably 4-dimethylaminopyridine.

[0035] Preferably, the concentration of the second capping agent is 0.01~0.1wt%, which can ensure the efficiency of catalytic or synergistic promotion of the capping reaction while avoiding the risk of side reactions or residues due to excessive addition. This concentration has little impact on membrane flux, does not introduce significant swelling or structural damage, and is easily removed by subsequent rinsing.

[0036] Typical, but not limiting, concentrations of the second capping agent can be, for example, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, or 0.1 wt%, or any value in the range of 0.01 to 0.1 wt%.

[0037] Preferably, the first capping agent includes at least one of aniline, p-aminophenol, and m-aminophenol.

[0038] Preferably, the concentration of the first capping agent is 0.05~0.15wt% to ensure that it reacts fully with the residual carboxyl groups on the surface of the separation membrane, thereby achieving efficient capping, forming an electrically neutral amide structure, significantly reducing the negative charge density on the membrane surface, inhibiting membrane pore expansion, improving the steric hindrance retention capacity for small molecule organic matter, and avoiding excessive reaction or excessive membrane densification caused by excessive concentration, which would lead to a decrease in water flux.

[0039] Typical, but not limiting, concentrations of the first capping agent can be, for example, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.10 wt%, 0.11 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, or 0.15 wt%, or any value in the range of 0.05 to 0.15 wt%.

[0040] Furthermore, the solvent in the capping agent solution includes at least one of ethanol, isopropanol, or acetone.

[0041] Preferably, the temperature of the sealing end is 80~100℃.

[0042] Typical, but not limiting, end-capping temperatures can be, for example, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C, or 100°C, or any value within the range of 80°C to 100°C.

[0043] Preferably, the time for coating the end-capping agent solution and performing end-capping is 30-60 seconds. This time refers to the entire continuous processing time from the moment the end-capping agent solution enters the coating section until it completes the end-capping reaction after passing through the reaction drying tunnel. This time includes the application process of the coating solution on the film surface and the subsequent chemical reaction process under heating conditions, i.e., the residence time from the start of coating to the substantial completion of the end-capping reaction.

[0044] Typical, but not limiting, the time for coating the end-capping agent solution and performing end-capping can be, for example, 60s, 62s, 64s, 66s, 68s, 70s, 72s, 74s, 76s, 78s, 80s, 82s, 84s, 86s, 88s, or 90s, or any value within the range of 60 to 90s.

[0045] Furthermore, the preparation process of the separation membrane substrate is as follows: the polysulfone membrane is first passed through an aqueous solution for 20-40 seconds, then the excess aqueous phase is removed, and one of its surfaces is brought into contact with the oil phase to carry out an interfacial polymerization reaction. After rinsing and first drying, the separation membrane substrate is obtained.

[0046] Furthermore, the aqueous solution is a m-phenylenediamine solution.

[0047] Preferably, the oil phase is a pyromellitic acid chloride solution.

[0048] Preferably, the interfacial polymerization reaction takes 20-40 seconds.

[0049] Typical, but not limiting, the time for the interfacial polymerization reaction can be, for example, 20s, 22s, 24s, 26s, 28s, 30s, 32s, 34s, 36s, 38s, or 40s, or any value within the range of 20 to 40s.

[0050] Further, rinse with the same solvent used in the oil phase.

[0051] Preferably, the solvent grade in the oil phase includes Isopar G.

[0052] Furthermore, the temperature of the first drying process is 90~110℃, and the time is 60~90s.

[0053] Typically, but not limitingly, the temperature of the first drying step can be, for example, 90°C, 92°C, 94°C, 96°C, 98°C, 100°C, 102°C, 104°C, 106°C, 108°C, or 110°C, or any value within the range of 90°C to 110°C; the time of the first drying step can be, for example, 60s, 65s, 70s, 75s, 80s, 85s, or 90s, or any value within the range of 60 to 90s.

[0054] Furthermore, the post-treatment includes sequential alkaline washing, hot water rinsing, and a second drying.

[0055] A second aspect of the present invention provides a separation membrane, which is produced using the aforementioned online continuous production process.

[0056] The separation membrane provided by this invention effectively reduces the ionization capacity of residual carboxyl groups on the surface of the polyamide functional layer through an online continuous end-capping process. This significantly reduces the negative charge density on the membrane surface, suppresses membrane pore expansion caused by electrostatic repulsion, and results in a denser and narrower pore structure. Consequently, it greatly improves the retention rate of small-molecule dissolved organic matter (such as isopropanol), meeting the stringent TOC requirements in the preparation of electronic-grade ultrapure water. Simultaneously, the electrically neutralized surface weakens the interaction with cations and positively charged colloids, reducing the adsorption and bridging effects of pollutants on the membrane surface, significantly enhancing antifouling capabilities, extending membrane lifespan, and improving flux recovery after chemical cleaning. This membrane achieves synergistic optimization of selectivity and stability while maintaining high desalination rate and good water flux, making it suitable for high-end water treatment applications.

[0057] Furthermore, the absolute value of the Zeta potential is less than 10 mV under pH conditions of 7.5–8.0.

[0058] Preferably, when tested in a mixed aqueous solution of 2000 ppm sodium chloride and 10 ppm isopropanol, the pressure is 225 psi, the test temperature is 25°C, the pH is 7.5-8, the desalination rate is ≥99.8%, and the isopropanol retention rate is not less than 96.2%.

[0059] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0060] Example 1 This embodiment provides an online continuous production process for separation membranes, the specific steps of which are as follows: 1. The polysulfone-based film is unwound and fed into a continuous production line. It is first immersed in a 2.5wt% m-phenylenediamine (MPD) aqueous solution for 30 seconds to allow the MPD to fully diffuse into the micropores on the surface of the base film. Then, excess aqueous solution remaining on the surface is removed by a pair of counter-rotating extrusion rollers.

[0061] 2. The treated base film is introduced into an organic phase solution containing 0.15 wt% trimesoyl chloride (TMC) in a single-sided contact manner. Isopar G is used as the solvent, and the interfacial polymerization reaction time is controlled at 30 s. A polyamide separation layer is generated in situ on the surface of the base film.

[0062] 3. After interfacial polymerization is completed, the membrane surface is immediately sprayed and rinsed with pure Isopar G solvent to remove unreacted TMC and its byproducts. The rinsed membrane is then transferred to the first drying section via a transfer roller assembly and dried in a 100°C hot air tunnel for 60 seconds to complete preliminary curing and remove residual solvent, resulting in a stable separation membrane substrate.

[0063] 4. The above-mentioned substrate is continuously introduced into the end-capping section, where a slit coating machine is used to uniformly coat the polyamide surface with a end-capping agent solution. The end-capping agent solution contains 0.1 wt% aniline and 0.05 wt% 4-dimethylaminopyridine (DMAP), and anhydrous ethanol is used as the solvent. The film material is then placed in a reaction drying tunnel and reacted at 80°C. The coating and drying process of the end-capping agent is controlled to last 60 seconds.

[0064] 5. After the end-capping reaction is completed, the membrane material enters the post-processing unit and undergoes the following operations in sequence: Alkaline washing: Wash with a dilute sodium hydroxide solution with a pH of 10 for 10 seconds to remove residual small molecule organic matter and byproducts; Hot water rinse: Rinse with 60℃ deionized water for 30 seconds to thoroughly remove alkaline solution and soluble impurities; Second drying: Enter a 70℃ low-temperature hot air drying tunnel and dry for 90 seconds to obtain a dry finished film.

[0065] 6. After passing inspection, the finished film is wound up to a fixed length by a winding machine, packaged, and stored for testing.

[0066] Example 2 This embodiment provides an online continuous production process for separation membranes. The difference from Embodiment 1 is that p-aminophenol is used instead of aniline. The remaining steps are the same as in Embodiment 1 and will not be repeated here.

[0067] Example 3 This embodiment provides an online continuous production process for separation membranes. The difference from Embodiment 1 is that 2-dimethylaminopyridine is used instead of 4-dimethylaminopyridine. The remaining steps are the same as in Embodiment 1 and will not be repeated here.

[0068] Example 4 This embodiment provides an online continuous production process for a separation membrane. The difference from Example 1 is that the concentration of aniline in the capping agent solution is 0.02 wt%, and the concentration of 4-dimethylaminopyridine is 0.005 wt%. The remaining steps are the same as in Example 1 and will not be repeated here.

[0069] Example 5 This embodiment provides an online continuous production process for a separation membrane. The difference from Example 1 is that the concentration of aniline in the capping agent solution is 0.05 wt%, and the concentration of 4-dimethylaminopyridine is 0.01 wt%. The remaining steps are the same as in Example 1 and will not be repeated here.

[0070] Example 6 This embodiment provides an online continuous production process for a separation membrane. The difference from Example 1 is that the concentration of aniline in the capping agent solution is 0.15 wt%, and the concentration of 4-dimethylaminopyridine is 0.1 wt%. The remaining steps are the same as in Example 1 and will not be repeated here.

[0071] Example 7 This embodiment provides an online continuous production process for a separation membrane. The difference from Example 1 is that the concentration of aniline in the capping agent solution is 0.2 wt%, and the concentration of 4-dimethylaminopyridine is 0.2 wt%. The remaining steps are the same as in Example 1 and will not be repeated here.

[0072] Comparative Example 1 This comparative example provides an online continuous production process for a separation membrane. Unlike Example 1, the concentration of aniline in the capping agent solution is 0.05 wt%, and 4-dimethylaminopyridine is not used. The remaining steps are the same as in Example 1 and will not be repeated here.

[0073] Comparative Example 2 This comparative example provides an online continuous production process for a separation membrane. Unlike Example 1, the concentration of aniline in the capping agent solution is 0.1 wt%, and 4-dimethylaminopyridine is not used. The remaining steps are the same as in Example 1 and will not be repeated here.

[0074] Comparative Example 3 This comparative example provides an online continuous production process for a separation membrane. Unlike Example 1, the concentration of aniline in the capping agent solution is 0.15 wt%, and 4-dimethylaminopyridine is not used. The remaining steps are the same as in Example 1 and will not be repeated here.

[0075] Comparative Example 4 This comparative example provides an online continuous production process for a separation membrane. Unlike Example 1, only 4-dimethylaminopyridine is used in the capping agent solution, and aniline is not used. The remaining steps are the same as in Example 1, and will not be repeated here.

[0076] Comparative Example 5 This comparative example provides an online continuous production process for a separation membrane. Unlike Example 1, step 4 is omitted, and the separation membrane substrate directly enters the post-processing unit. The remaining steps are the same as in Example 1 and will not be repeated here.

[0077] Test Example 1 The separation membranes obtained in the examples and comparative examples were tested for their desalination rate, water flux, and organic matter rejection rate. The test solution was a mixed aqueous solution of 2000 ppm sodium chloride and 10 ppm isopropanol, the test pressure was 225 psi, the test temperature was 25 °C, and the test pH was 7.5-8.

[0078] Adopt GB / T 37617 The 2019 nanofiltration membrane surface zeta potential test method detects the zeta potential of each membrane surface.

[0079] The static water contact angle was tested according to GB / T 30447-2013.

[0080] Table 1 Comparison of diaphragm performance

[0081] As shown in Table 1, the isopropanol rejection rates of Examples 1 (Zeta -8 mV) and 2 (Zeta -9 mV) reached 96.2% and 96.42%, respectively, which were significantly better than those of Comparative Examples 1-3 (92.67%-94.82%) without the second capping agent, indicating that effective capping improved selectivity. Meanwhile, the introduction of aromatic rings and hydrophobic groups by the primary amine increased the water contact angle from 55° in Comparative Example 5 to 72° in Example 7, reflecting an enhanced trend in surface hydrophobicity.

[0082] However, excessively increasing the amount of capping agent can lead to over-crosslinking and densification of the separation layer, resulting in a significant decrease in flux. For example, in Example 7, the flux dropped to 42.88 L / m. 2 Although h still maintains a relatively high rejection rate of 95.46%, its improvement is lower than that of Example 1, indicating that the trade-off between flux and rejection rate is evident.

[0083] The second end-capping agent, 4-dimethylaminopyridine (DMAP), acts as a reaction promoter. Although it does not directly participate in covalent end-capping, it significantly improves reaction efficiency by catalyzing the amidation reaction. It can achieve efficient charge neutralization and pore control even at low primary amine concentrations. Example 1 achieved optimal overall performance with only 0.1% aniline and 0.05% DMAP, while Comparative Example 2, with the same aniline concentration but without DMAP, had a higher Zeta potential of -25 mV and a lower rejection rate of 93.55%, which fully demonstrates the role of DMAP in improving reaction controllability and process economy.

[0084] In summary, this invention achieves chemical end-capping through a first end-capping agent and regulates reaction kinetics through a second end-capping agent, thereby synergistically realizing precise control of membrane surface charge, pore structure, and hydrophilicity-hydrophobicity balance. This significantly improves organic matter removal capacity and batch stability while ensuring a high desalination rate.

[0085] Test Example 2 The pore size and pore distribution of the separation membranes obtained in Example 2, Comparative Example 3, and Comparative Example 5 were characterized by positron annihilation, and the resulting images are shown below. Figure 1 As shown.

[0086] from Figure 1 It can be seen that the pore size distribution of Example 2 (black curve) is mainly concentrated around 0.1 nm. The normalization intensity of pores of this size is high, the pore size is more uniform, and there are only a few pores of other sizes. The main pore peaks of Comparative Example 5 (blue curve) are also concentrated around 0.1 nm, but the peak morphology is different from that of Example 2, and additional pore peaks appear later. The diversity of pore distribution is more obvious, and the proportion of large-sized pores (close to 1 nm) is higher. The pore peak intensity of Comparative Example 3 (red curve) is lower around 0.1 nm, the overall pore size distribution is more gradual, the concentration of pore structure is weaker, the proportion of pores of different sizes is more even, and there is no obvious dominant pore size.

[0087] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An online continuous production process for a separation membrane, characterized in that, After the interfacial polymerization reaction has been completed and the separation membrane substrate has been rinsed with solvent and dried, the end-capping agent solution is coated on the coating equipment and then the membrane enters the reaction drying tunnel for end-capping. Finally, the separation membrane is obtained through post-processing by the transfer roller group. The end-capping agent in the end-capping agent solution includes a first end-capping agent and a second end-capping agent; The first capping agent includes at least one of methylamine, ethylamine, aniline, 2-hydroxyethylamine, diethanolamine, p-aminophenol, o-aminophenol, and aminophenol; The second capping agent includes pyridine compounds.

2. The online continuous production process according to claim 1, characterized in that, The pyridine compounds include at least one of 4-dimethylaminopyridine, 2-dimethylaminopyridine and 4-dimethylamino-3-methylpyridine, preferably 4-dimethylaminopyridine; Preferably, the concentration of the second capping agent is 0.01~0.1 wt%; Preferably, the first capping agent comprises at least one of aniline, p-aminophenol, and m-aminophenol; Preferably, the concentration of the first capping agent is 0.05~0.15wt%.

3. The online continuous production process according to claim 1, characterized in that, The solvent in the capping agent solution includes at least one of ethanol, isopropanol, or acetone. Preferably, the temperature of the sealing end is 80~100℃; Preferably, the sealing time for applying the sealing agent solution is 30-60 seconds.

4. The online continuous production process according to any one of claims 1 to 3, characterized in that, The preparation process of the separation membrane substrate is as follows: the polysulfone membrane is first passed through an aqueous solution for 20-40 seconds, and then the excess aqueous phase is removed. One of the surfaces is then brought into contact with the oil phase to carry out an interfacial polymerization reaction. After rinsing and first drying, the separation membrane substrate is obtained.

5. The online continuous production process according to claim 4, characterized in that, The aqueous solution is a m-phenylenediamine solution; Preferably, the oil phase is a pyromellitic acid chloride solution; Preferably, the interfacial polymerization reaction takes 20 to 40 seconds.

6. The online continuous production process according to claim 4, characterized in that, Rinse using the same solvent as the oil phase; Preferably, the solvent grade in the oil phase includes Isopar G.

7. The online continuous production process according to claim 1, characterized in that, The first drying temperature is 90~110℃ and the time is 60~90s.

8. The online continuous production process according to claim 1, characterized in that, The post-treatment includes sequential alkaline washing, hot water rinsing, and a second drying.

9. A separation membrane, characterized in that, It is produced using the online continuous production process described in any one of claims 1 to 8.

10. The separation membrane according to claim 9, characterized in that, The absolute value of the Zeta potential is less than 10 mV under pH conditions of 7.5–8.

0. Preferably, when tested in a mixed aqueous solution of 2000 ppm sodium chloride and 10 ppm isopropanol, the pressure is 225 psi, the test temperature is 25°C, the pH is 7.5-8, the desalination rate is ≥99.8%, and the isopropanol retention rate is not less than 96.2%.

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