Efficient casting process for curtain type membrane module
By end-sealing hollow fiber membrane filaments and using modified epoxy resin encapsulant, combined with a specific casting process, the problem of membrane filament root breakage in curtain membrane modules was solved, improving the strength and casting efficiency of the membrane modules.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 江苏艾乐膜科技有限公司
- Filing Date
- 2025-12-23
- Publication Date
- 2026-05-01
AI Technical Summary
During the use of curtain membrane modules, the roots of hollow fiber membrane filaments are prone to tearing, which leads to a decrease in separation performance. This is mainly due to the phenomenon of glue spreading and tearing at the root of the membrane filaments.
End-sealing adhesive is used to seal both ends of the hollow fiber membrane filaments. Combined with a modified epoxy resin that is well compatible with the hollow fiber membrane filaments, a specific casting process and parameter control are used to ensure good bonding between the encapsulating adhesive and the membrane filament interface and avoid clogging.
It improves the strength and casting efficiency of the curtain membrane module, ensures good bonding between the membrane fibers and the encapsulating adhesive interface, avoids root rupture of the membrane fibers, and increases the pure water flux and bonding strength of the membrane module.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of curtain membrane module technology, specifically to a high-efficiency casting process for curtain membrane modules. Background Technology
[0002] Hollow fiber membranes are self-supporting separation membranes with a fibrous shape and micropores throughout their walls. They can selectively separate substances based on molecular weight or particle size, enabling efficient separation, concentration, and purification of different components in solutions or gases. Curtain membrane modules integrate a large number of hollow fiber membranes in a parallel array to form a "curtain" structure, with both ends encapsulated with materials such as epoxy resin to form membrane elements. This design significantly increases the effective membrane area per unit volume, achieving system compactness. Therefore, curtain membrane modules have found widespread application.
[0003] However, after a period of use, tears easily form on the surface of the membrane filaments at the root of the hollow fiber curtain membrane module, causing it to lose its separation performance. The phenomenon of adhesive creeping up the membrane filaments at the root of the hollow fiber curtain membrane is a significant cause of this damage. When the hollow fiber curtain membrane is immersed in a wastewater treatment tank, the membrane filaments continuously vibrate laterally and longitudinally due to the influence of water flow and aeration. This causes significant tensile stress at the adhesive-sealed areas of the filaments. Due to capillary action, adhesive creeping occurs at the root of the hollow fiber curtain membrane during the adhesive-sealing process, leading to adhesion between the filaments. When the filaments vibrate, this adhesion is prone to tearing, causing the coating layer to peel off from the braided tube surface and damaging the hollow fiber membrane separation layer. Summary of the Invention
[0004] To address the aforementioned problems, this invention provides an efficient casting process for curtain membrane modules.
[0005] The technical solution of this invention is: a high-efficiency casting process for curtain membrane modules, comprising the following steps: S1. After arranging multiple hollow fiber membrane filaments neatly, fix them with a clamp. Cut both ends of the fixed hollow fiber membrane filaments to make the ends of the hollow fiber membrane filaments neat, and obtain the cut membrane filaments. S2. Immerse both ends of the cut membrane fiber in a sealing adhesive at 65~75℃ for 1~2 minutes. After immersion, remove the fiber and let it stand for 20~30 minutes to obtain the sealed membrane fiber. S3. Place the sealed membrane filaments into the mold, then pour the encapsulating adhesive into the mold. After pouring, let it stand and cure for 12~18 hours before demolding to obtain the membrane module. S4. Cut both ends of the membrane module, and then immerse the cut membrane module in water at 85~95℃ for 20~30 minutes to remove the end-sealing adhesive from both ends of the membrane module, thus obtaining the curtain membrane module.
[0006] Note: The above casting process uses end-sealing adhesive to seal both ends of the hollow fiber membrane filaments, preventing blockage during casting. Furthermore, the encapsulating adhesive has good compatibility with the hollow fiber membrane filaments, ensuring a good interface bond between the hollow fiber membrane filaments and the encapsulating adhesive. This ensures the strength of the curtain membrane module while improving casting efficiency.
[0007] Furthermore, the end-capping adhesive is a polyvinyl alcohol aqueous solution with a mass concentration of 10-15%.
[0008] Note: The above-mentioned end-sealing adhesive can effectively seal hollow fiber membrane fibers, and is easy to remove with minimal residue, effectively preventing the hollow fiber membrane fibers from becoming clogged.
[0009] Furthermore, the cut membrane fibers are immersed in the end-sealing adhesive to a depth of 25-50 mm.
[0010] Note: Limiting the immersion depth of the end-capping adhesive can ensure the sealing effect of the hollow fiber membrane fibers and prevent the encapsulating adhesive from entering the hollow fiber membrane fibers and causing blockage.
[0011] Furthermore, the components of the encapsulating adhesive, by weight, include: 40-50 parts modified epoxy resin, 10-20 parts polyetheramine, 5-10 parts fatty amine, 15-25 parts o-tolyl glycidyl ether, 0.5-1 part polydimethylsiloxane, and 1-3 parts silane coupling agent.
[0012] Note: The above-mentioned encapsulating adhesive has good flowability and can fully fill the mold. Furthermore, the modified epoxy resin has good compatibility with the hollow fiber membrane filaments, which can ensure good bonding between the hollow fiber membrane filaments and the encapsulating adhesive.
[0013] Furthermore, the method for preparing the encapsulating adhesive includes the following steps: 1) According to the stated weight parts, the modified epoxy resin, o-tolyl glycidyl ether, and polydimethylsiloxane are mixed and stirred at 50~70℃ for 1.5~3h, followed by vacuum degassing to obtain the resin component; 2) Mix polyetheramine, fatty amine and silane coupling agent, stir for 30-60 minutes to obtain curing agent component; 3) Add the curing agent component to the resin component, stir for 3-5 minutes, and let stand for 5-10 minutes to obtain the encapsulating adhesive.
[0014] Note: The encapsulating adhesive prepared by the above method can ensure that the components within the encapsulating adhesive are evenly distributed, thus guaranteeing the fluidity of the encapsulating adhesive. Furthermore, air within the encapsulating adhesive can be fully removed, preventing the formation of air bubbles.
[0015] Furthermore, the vacuum degree during vacuum degassing is -0.095 to -0.100 N, and the time is 10 to 20 minutes.
[0016] Note: The above vacuum degassing parameters can effectively remove air from the resin components and prevent air from being trapped within them.
[0017] Furthermore, the preparation method of the modified epoxy resin includes the following steps: 1) Add epoxy resin to acetone and stir until completely dissolved. Then add allylamine and stir for 10-15 minutes to obtain a mixture. The mass ratio of epoxy resin, allylamine and acetone is 1:0.7-0.8:3-4. 2) The mixture was heated to 70-85°C under an inert gas atmosphere and kept at this temperature for 6-8 hours with stirring to obtain the reactants. The reactants were then distilled under reduced pressure to obtain the intermediate products. 3) Add methyl methacrylate and benzoyl peroxide to the intermediate product, and then stir at 70~90℃ for 4~6h to obtain the reactant; wherein, the mass ratio of intermediate product, methyl methacrylate and benzoyl peroxide is 1:0.6~0.7:0.05~0.1; 4) Add the reactants to petroleum ether, then filter to obtain solid particles. Wash and dry the solid particles to obtain modified epoxy resin; wherein the mass ratio of reactants to petroleum ether is 1:2~3.
[0018] Explanation: The above preparation method involves a ring-opening addition reaction between allylamine and epoxy resin to graft allylamine onto the epoxy resin. Then, methyl methacrylate is copolymerized onto the epoxy resin through a reaction between methyl methacrylate and the double bonds on the allylamine. This improves the flowability of the epoxy resin and its compatibility with hollow fiber membrane fibers, allowing the hollow fiber membrane fibers to bond well with the hollow fiber membrane fiber interface without plasma treatment.
[0019] Further, the casting process is as follows: first, pour encapsulating adhesive at 40-45°C into the mold at a rate of 150-200 ml / min until the height of the encapsulating adhesive in the mold reaches 8-10 cm; then, pour encapsulating adhesive at 30-35°C into the mold at a rate of 300-350 ml / min until the height of the encapsulating adhesive in the mold reaches 12-15 cm; then, heat the mold to raise the temperature of the encapsulating adhesive in the mold to 50-55°C; then, pour encapsulating adhesive at 45-50°C into the mold at a rate of 200-300 ml / min until the height of the encapsulating adhesive in the mold reaches 20-22 cm, thus completing the casting process.
[0020] Note: The above casting process combines slow and fast casting, which can ensure the casting rate while allowing the encapsulating glue to fully fill the mold and fully expel the gas inside the encapsulating glue, thereby reducing defects inside the encapsulating glue and ensuring casting quality.
[0021] Furthermore, the length of the portion cut off during the membrane assembly cutting is 10~20mm.
[0022] Note: Limiting the cutting length of the membrane module ensures that the end-capping adhesive is fully exposed, allowing for complete removal of the end-capping adhesive and ensuring the flowability of the membrane module.
[0023] The beneficial effects of this invention are: (1) The casting process of the present invention seals the two ends of the hollow fiber membrane filaments with end-sealing adhesive to avoid blockage of the hollow fiber membrane filaments during the casting process. Moreover, the compatibility between the encapsulating adhesive and the hollow fiber membrane filaments is good during casting, which can ensure good bonding between the hollow fiber membrane filaments and the encapsulating adhesive interface, thus ensuring the strength of the curtain membrane module while improving the casting efficiency.
[0024] (2) In this invention, allylamine is grafted onto epoxy resin by ring-opening addition reaction with allylamine, and then methyl methacrylate is copolymerized onto epoxy resin by reaction with the double bond on allylamine, thereby improving the flowability of epoxy resin and compatibility with hollow fiber membrane fibers, so that hollow fiber membrane fibers can be well bonded to the interface of hollow fiber membrane fibers without plasma treatment. Detailed Implementation
[0025] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.
[0026] Example 1: A high-efficiency casting process for curtain membrane modules, comprising the following steps: S1. After arranging 1500 hollow fiber membrane filaments neatly, fix them with a clamp. Cut both ends of the fixed hollow fiber membrane filaments to make the ends of the hollow fiber membrane filaments neat, and obtain the cut membrane filaments. S2. Immerse both ends of the cut membrane filament in a 70℃ sealing adhesive for 1.5 min. After immersion, remove the membrane filament and let it stand for 25 min to obtain the sealed membrane filament. The sealing adhesive is a 12% polyvinyl alcohol aqueous solution, and the immersion depth of the cut membrane filament in the sealing adhesive is 32 mm. S3. Place the sealed membrane filaments into the mold, then pour the encapsulating adhesive into the mold. After pouring, let it stand and cure for 16 hours before demolding to obtain the membrane module. The pouring process is as follows: First, pour 42°C encapsulating adhesive into the mold at a rate of 175ml / min until the encapsulating adhesive in the mold reaches a height of 9cm. Then pour 32°C encapsulating adhesive into the mold at a rate of 325ml / min until the height of the encapsulating adhesive in the mold reaches 14cm. Then heat the mold to raise the temperature of the encapsulating adhesive in the mold to 52°C. Then, pour 47°C encapsulating adhesive into the mold at a rate of 250 ml / min until the encapsulating adhesive reaches a height of 21 cm in the mold, and then complete the pouring process; and apply 35 Hz vibration to the mold during the pouring process. S4. Cut both ends of the membrane module, and then immerse the cut membrane module in 90℃ water for 25 minutes to remove the end-sealing adhesive at both ends of the membrane module to obtain a curtain-type membrane module; wherein, the length of the part cut off during the membrane module cutting is 15mm; The components of the encapsulating adhesive, by weight, include: 45 parts modified epoxy resin, 15 parts polyetheramine, 8 parts fatty amine, 20 parts o-tolyl glycidyl ether, 0.8 parts polydimethylsiloxane, and 2 parts silane coupling agent. The preparation method of the encapsulating adhesive includes the following steps: 1) According to the stated weight parts, the modified epoxy resin, o-tolyl glycidyl ether, and polydimethylsiloxane were mixed and stirred at 60°C for 2.5 h, followed by vacuum degassing to obtain the resin component; the vacuum degree of vacuum degassing was -0.098 N, and the time was 15 min. 2) Mix polyetheramine, fatty amine and silane coupling agent, stir for 45 min to obtain curing agent component; 3) Add the curing agent component to the resin component, stir for 4 minutes, and let stand for 8 minutes to obtain the encapsulating adhesive; The preparation method of modified epoxy resin includes the following steps: 1) Add epoxy resin to acetone and stir until completely dissolved. Then add allylamine and stir for 12 minutes to obtain a mixture. The mass ratio of epoxy resin, allylamine and acetone is 1:0.75:3.5. The epoxy resin is bisphenol A type epoxy resin. 2) The mixture was heated to 78°C under an inert gas atmosphere and kept at this temperature for 7 hours with stirring to obtain the reactants. The reactants were then distilled under reduced pressure to obtain the intermediate product. The pressure during the reduced pressure distillation was -0.08 N and the temperature was 40°C. 3) Add methyl methacrylate and benzoyl peroxide to the intermediate product, and then stir at 80°C for 5 hours to obtain the reactant; wherein the mass ratio of the intermediate product, methyl methacrylate and benzoyl peroxide is 1:0.65:0.08. 4) Add the reactants to petroleum ether, then filter to obtain solid particles. Wash and dry the solid particles to obtain modified epoxy resin; wherein the mass ratio of reactants to petroleum ether is 1:2.5.
[0027] Example 2: This example is basically the same as Example 1, except that the end-capping adhesive is a 10% (w / w) polyvinyl alcohol aqueous solution.
[0028] Example 3: This example is basically the same as Example 1, except that the end-capping adhesive is a 15% (w / w) polyvinyl alcohol aqueous solution.
[0029] Example 4: This example is basically the same as Example 1, except that the composition of the encapsulating adhesive, by weight, includes: 40 parts modified epoxy resin, 10 parts polyetheramine, 5 parts fatty amine, 15 parts o-tolyl glycidyl ether, 0.5 parts polydimethylsiloxane, and 1 part silane coupling agent.
[0030] Example 5: This example is basically the same as Example 1, except that the composition of the encapsulating adhesive, by weight, includes: 50 parts modified epoxy resin, 20 parts polyetheramine, 10 parts fatty amine, 25 parts o-tolyl glycidyl ether, 1 part polydimethylsiloxane, and 3 parts silane coupling agent.
[0031] Example 6: This example is basically the same as Example 1, except that the vacuum degree during vacuum degassing is -0.095N.
[0032] Example 7: This example is basically the same as Example 1, except that the vacuum degree during vacuum degassing is -0.100N.
[0033] Example 8: This example is basically the same as Example 1, except that the mass ratio of epoxy resin, allylamine and acetone is 1:0.7:3.
[0034] Example 9: This example is basically the same as Example 1, except that the mass ratio of epoxy resin, allylamine and acetone is 1:0.8:4.
[0035] Example 10: This example is basically the same as Example 1, except that the mixture is heated to 70°C under an inert gas protection environment and kept at that temperature for 6 hours while being stirred.
[0036] Example 11: This example is basically the same as Example 1, except that the mixture is heated to 85°C under an inert gas protection environment and kept at that temperature for 8 hours while being stirred.
[0037] Example 12: This example is basically the same as Example 1, except that the mass ratio of the intermediate product, methyl methacrylate and benzoyl peroxide is 1:0.6:0.05.
[0038] Example 13: This example is basically the same as Example 1, except that the mass ratio of the intermediate product, methyl methacrylate and benzoyl peroxide is 1:0.7:0.1.
[0039] Example 14: This example is basically the same as Example 1, except that methyl methacrylate and benzoyl peroxide are added to the intermediate product, and then stirred at 70°C for 4 hours.
[0040] Example 15: This example is basically the same as Example 1, except that methyl methacrylate and benzoyl peroxide are added to the intermediate product, and then stirred at 90°C for 6 hours.
[0041] Example 16: This example is basically the same as Example 1, except that the mass ratio of reactants to petroleum ether is 1:2.
[0042] Example 17: This example is basically the same as Example 1, except that the mass ratio of reactants to petroleum ether is 1:3.
[0043] Example 18: This example is basically the same as Example 1, except that the casting process is as follows: First, pour 42℃ encapsulating glue into the mold at a rate of 150ml / min until the height of the encapsulating glue in the mold reaches 9cm. Then pour 32°C encapsulating adhesive into the mold at a rate of 300ml / min until the height of the encapsulating adhesive in the mold reaches 14cm. Then heat the mold to raise the temperature of the encapsulating adhesive in the mold to 52°C. Then pour 47°C encapsulating adhesive into the mold at a rate of 200ml / min until the encapsulating adhesive reaches a height of 21cm in the mold, thus completing the pouring process.
[0044] Example 19: This example is basically the same as Example 1, except that the pouring process is as follows: First, pour 42℃ encapsulating glue into the mold at a rate of 200ml / min until the height of the encapsulating glue in the mold reaches 9cm. Then pour 32°C encapsulating adhesive into the mold at a rate of 350ml / min until the height of the encapsulating adhesive in the mold reaches 14cm. Then heat the mold to raise the temperature of the encapsulating adhesive in the mold to 52°C. Then pour 47°C encapsulating adhesive into the mold at a rate of 300ml / min until the encapsulating adhesive reaches a height of 21cm in the mold, thus completing the pouring process.
[0045] Example 20: This example is basically the same as Example 1, except that the casting process is as follows: First, pour 40°C encapsulating adhesive into the mold at a rate of 175ml / min until the encapsulating adhesive in the mold reaches a height of 9cm. Then pour 30°C encapsulating adhesive into the mold at a rate of 325ml / min until the height of the encapsulating adhesive in the mold reaches 14cm. Then heat the mold to raise the temperature of the encapsulating adhesive in the mold to 50°C. Then pour 45°C encapsulating adhesive into the mold at a rate of 250 ml / min until the encapsulating adhesive reaches a height of 21 cm in the mold, thus completing the pouring process.
[0046] Example 21: This example is basically the same as Example 1, except that the casting process is as follows: First, pour 45℃ encapsulating glue into the mold at a rate of 175ml / min until the height of the encapsulating glue in the mold reaches 9cm. Then pour 35°C encapsulating adhesive into the mold at a rate of 325ml / min until the height of the encapsulating adhesive in the mold reaches 14cm. Then heat the mold to raise the temperature of the encapsulating adhesive in the mold to 55°C. Then pour 50°C encapsulating adhesive into the mold at a rate of 250 ml / min until the encapsulating adhesive reaches a height of 21 cm in the mold, thus completing the pouring process.
[0047] Comparative Example 1: Referring to Example 1, the modified epoxy resin was replaced with unmodified epoxy resin.
[0048] Comparative Example 2: Referring to Example 1, allylamine and methyl methacrylate were directly added to the encapsulating adhesive.
[0049] Comparative Example 3: Referring to Example 1, the encapsulating adhesive at 47°C was poured at a rate of 250 ml / min throughout the pouring process.
[0050] Experimental Example: To investigate the influence of preparation parameters of each embodiment on the performance of the curtain membrane module, the pure water flux of the curtain membrane modules prepared in each embodiment was tested at a temperature of 25°C and a pressure of 0.1 MPa. Subsequently, a pull-out test was performed on the curtain membrane module to obtain the adhesion strength between the hollow fiber membrane filaments and the encapsulation end. The specific investigation is as follows: 1. Investigate the effect of end-capping adhesive mass concentration on the performance of curtain membrane modules. Using Examples 1, 2, and 3 as experimental comparisons, the performance of the curtain membrane module under different end-capping adhesive mass concentrations is shown in Table 1 below: Table 1 Performance of curtain membrane modules at different end-capping adhesive concentrations
[0051] As shown in Table 1, compared with Examples 1, 2, and 3, the curtain membrane module of Example 1 has the highest pure water flux and bonding strength, indicating that the curtain membrane module selected in Example 1 has the best performance. This may be because the end capping adhesive selected in Example 1 can fully seal both ends of the hollow fiber membrane filaments at the selected end capping adhesive concentration, and leaves the least residue when removed. Therefore, the end capping adhesive concentration selected in Example 1 is the best.
[0052] 2. Investigate the influence of encapsulating adhesive composition on the performance of curtain membrane modules. Using Examples 1, 4, 5 and Comparative Example 1 as experimental comparisons, the performance of the curtain film module with different encapsulant compositions is shown in Table 2 below: Table 2 Performance of curtain membrane modules with different encapsulant compositions
[0053] As shown in Table 2, compared with Examples 1, 4, and 5, the curtain membrane module of Example 1 has the highest pure water flux and bonding strength, indicating that the curtain membrane module selected in Example 1 has the best performance. This may be because the encapsulating adhesive component selected in Example 1 has moderate fluidity, thus the encapsulating adhesive component selected in Example 1 is the best.
[0054] Compared with Comparative Example 1, after replacing the modified epoxy resin with the unmodified epoxy resin, the pure water flux and bonding strength of the curtain membrane module both decreased. This may be because the modified epoxy resin has better performance. Therefore, the encapsulating adhesive component selected in Example 1 is the optimal one.
[0055] 3. Investigate the influence of vacuum degassing parameters on the performance of curtain membrane modules. Using Examples 1, 6, and 7 as experimental comparisons, the performance of the curtain membrane module under different vacuum degassing parameters is shown in Table 3 below: Table 3 Performance of curtain membrane modules under different vacuum degassing parameters
[0056] As shown in Table 3, compared with Examples 1, 6, and 7, the curtain membrane module of Example 1 has the highest pure water flux and bonding strength, indicating that the curtain membrane module selected in Example 1 has the best performance. This may be because the vacuum degassing parameters selected in Example 1 have the fewest internal defects in the encapsulating adhesive, so the vacuum degassing parameters selected in Example 1 are the best.
[0057] 4. Investigate the influence of the mixture composition on the performance of the curtain membrane module. Using Examples 1, 8, and 9 as experimental comparisons, the performance of the curtain membrane module under different mixture compositions is shown in Table 4 below: Table 4 Performance of curtain membrane modules with different mixture compositions
[0058] As shown in Table 4, compared with Examples 1, 8, and 9, the curtain membrane module of Example 1 has the highest pure water flux and bonding strength, indicating that the curtain membrane module selected in Example 1 has the best performance. This may be because the epoxy resin and allylamine can fully react under the mixed liquid composition selected in Example 1, so the mixed liquid composition selected in Example 1 is the best.
[0059] 5. Investigate the influence of intermediate product preparation parameters on the performance of curtain membrane modules. Using Examples 1, 10, and 11 as experimental comparisons, the performance of the curtain membrane module under different preparation parameters of the intermediate product is shown in Table 5 below: Table 5 Performance of curtain membrane modules under different preparation parameters of intermediate products
[0060] As shown in Table 5, compared with Examples 1, 10, and 11, the curtain membrane module of Example 1 has the highest pure water flux and bonding strength, indicating that the curtain membrane module selected in Example 1 has the best performance. This may be because the intermediate product preparation parameters selected in Example 1 have the fewest by-products in the intermediate product. Therefore, the intermediate product preparation parameters selected in Example 1 are the best.
[0061] 6. Investigate the influence of reactant composition on the performance of curtain membrane modules. Using Examples 1, 12, and 13, as well as Comparative Example 2, as experimental comparisons, the performance of the curtain membrane module under different reactant compositions is shown in Table 6 below: Table 6 Performance of curtain membrane modules with different reactant compositions
[0062] As shown in Table 6, compared with Examples 1, 12, and 13, the curtain membrane module of Example 1 has the highest pure water flux and bonding strength, indicating that the curtain membrane module selected in Example 1 has the best performance. This may be because the intermediate product and methyl methacrylate can react fully under the reactant composition selected in Example 1, so the reactant composition selected in Example 1 is the best.
[0063] 7. Investigate the influence of reactant preparation parameters on the performance of curtain membrane modules. Using Examples 1, 14, and 15 as experimental comparisons, the performance of the curtain membrane module under different reactant preparation parameters is shown in Table 7 below: Table 7 Performance of curtain membrane modules under different reactant preparation parameters
[0064] As shown in Table 7, compared with Examples 1, 14, and 15, the curtain membrane module of Example 1 has the highest pure water flux and bonding strength, indicating that the curtain membrane module selected in Example 1 has the best performance. This may be because the intermediate product and methyl methacrylate can react fully under the reactant preparation parameters selected in Example 1. Therefore, the reactant preparation parameters selected in Example 1 are the best.
[0065] 8. Investigate the effect of the ratio of reactants to petroleum ether on the performance of curtain membrane modules. Using Examples 1, 16, and 17 as comparative experiments, the performance of the curtain membrane module under different ratios of reactants and petroleum ether is shown in Table 8 below: Table 8 Performance of curtain membrane modules with different ratios of reactants and petroleum ether
[0066] As shown in Table 8, compared with Examples 1, 16, and 17, the curtain membrane module of Example 1 has the highest pure water flux and bonding strength, indicating that the curtain membrane module selected in Example 1 has the best performance. This may be because the modified epoxy resin has the highest purity under the reactant to petroleum ether ratio selected in Example 1. Therefore, the reactant to petroleum ether ratio selected in Example 1 is the optimal one.
[0067] 9. Investigate the effect of casting rate on the performance of curtain membrane modules. Using Examples 1, 18, 19 and Comparative Example 3 as experimental comparisons, the performance of the curtain membrane module at different casting rates is shown in Table 9 below: Table 9 Performance of curtain membrane modules at different casting rates
[0068] As shown in Table 9, compared with Examples 1, 18, and 19, the curtain membrane module of Example 1 has the highest pure water flux and bonding strength, indicating that the curtain membrane module selected in Example 1 has the best performance. This may be because the encapsulating adhesive has the fewest internal defects at the casting rate selected in Example 1, so the casting rate selected in Example 1 is the best.
[0069] Compared with Comparative Example 3, Example 1 showed a decrease in pure water flux and bonding strength of the curtain membrane module after the casting rate was kept constant. This indicates that the casting process of Example 1 can fully fill the mold with encapsulating adhesive and reduce internal defects of the encapsulating adhesive. Therefore, the casting rate selected in Example 1 is optimal.
[0070] 10. Investigate the effect of encapsulating adhesive temperature on the performance of curtain membrane modules. Using Examples 1, 20, and 21 as experimental comparisons, the performance of the curtain film module at different encapsulation temperatures is shown in Table 10 below: Table 10 Performance of curtain membrane modules at different encapsulation temperatures
[0071] As shown in Table 10, compared with Examples 1, 20 and 21, the curtain membrane module of Example 1 has the highest pure water flux and bonding strength, indicating that the curtain membrane module selected in Example 1 has the best performance. This may be because the encapsulating adhesive has moderate fluidity at the selected encapsulating adhesive temperature in Example 1, thus the encapsulating adhesive temperature selected in Example 1 is optimal.
Claims
1. A high-efficiency casting process for curtain-type membrane modules, characterized in that, Includes the following steps: S1. After arranging multiple hollow fiber membrane filaments neatly, fix them with a clamp. Cut both ends of the fixed hollow fiber membrane filaments to make the ends of the hollow fiber membrane filaments neat, and obtain the cut membrane filaments. S2. Immerse both ends of the cut membrane fiber in a sealing adhesive at 65~75℃ for 1~2 minutes. After immersion, remove the fiber and let it stand for 20~30 minutes to obtain the sealed membrane fiber. S3. Place the sealed membrane filaments into the mold, then pour the encapsulating adhesive into the mold. After pouring, let it stand and cure for 12~18 hours before demolding to obtain the membrane module. S4. Cut both ends of the membrane module, and then immerse the cut membrane module in water at 85~95℃ for 20~30 minutes to remove the end-sealing adhesive from both ends of the membrane module, thus obtaining the curtain membrane module.
2. The high-efficiency casting process for a curtain-type membrane module according to claim 1, characterized in that, The end-capping adhesive is a polyvinyl alcohol aqueous solution with a mass concentration of 10-15%.
3. The high-efficiency casting process for a curtain-type membrane module according to claim 1, characterized in that, The cut membrane fibers are immersed in the end-capping adhesive to a depth of 25-50 mm.
4. The high-efficiency casting process for a curtain-type membrane module according to claim 1, characterized in that, The components of the encapsulating adhesive, by weight, include: 40-50 parts modified epoxy resin, 10-20 parts polyetheramine, 5-10 parts fatty amine, 15-25 parts o-tolyl glycidyl ether, 0.5-1 part polydimethylsiloxane, and 1-3 parts silane coupling agent.
5. The high-efficiency casting process for a curtain-type membrane module according to claim 4, characterized in that, The preparation method of the encapsulating adhesive includes the following steps: 1) According to the stated weight parts, the modified epoxy resin, o-tolyl glycidyl ether, and polydimethylsiloxane are mixed and stirred at 50~70℃ for 1.5~3h, followed by vacuum degassing to obtain the resin component; 2) Mix polyetheramine, fatty amine and silane coupling agent, stir for 30-60 minutes to obtain curing agent component; 3) Add the curing agent component to the resin component, stir for 3-5 minutes, and let stand for 5-10 minutes to obtain the encapsulating adhesive.
6. The high-efficiency casting process for a curtain-type membrane module according to claim 5, characterized in that, The vacuum degree during vacuum degassing is -0.095 to -0.100 N, and the time is 10 to 20 minutes.
7. The high-efficiency casting process for a curtain-type membrane module according to claim 4, characterized in that, The preparation method of the modified epoxy resin includes the following steps: 1) Add epoxy resin to acetone and stir until completely dissolved. Then add allylamine and stir for 10-15 minutes to obtain a mixture. The mass ratio of epoxy resin, allylamine and acetone is 1:0.7-0.8:3-4. 2) The mixture was heated to 70-85°C under an inert gas atmosphere and kept at this temperature for 6-8 hours with stirring to obtain the reactants. The reactants were then distilled under reduced pressure to obtain the intermediate products. 3) Add methyl methacrylate and benzoyl peroxide to the intermediate product, and then stir at 70~90℃ for 4~6h to obtain the reactant; wherein, the mass ratio of intermediate product, methyl methacrylate and benzoyl peroxide is 1:0.6~0.7:0.05~0.1; 4) Add the reactants to petroleum ether, then filter to obtain solid particles. Wash and dry the solid particles to obtain modified epoxy resin; wherein the mass ratio of reactants to petroleum ether is 1:2~3.
8. The high-efficiency casting process for a curtain-type membrane module according to claim 1, characterized in that, The casting process is as follows: First, pour encapsulating adhesive at 40-45°C into the mold at a rate of 150-200 ml / min until the height of the encapsulating adhesive in the mold reaches 8-10 cm; then, pour encapsulating adhesive at 30-35°C into the mold at a rate of 300-350 ml / min until the height of the encapsulating adhesive in the mold reaches 12-15 cm; then, heat the mold to raise the temperature of the encapsulating adhesive in the mold to 50-55°C; finally, pour encapsulating adhesive at 45-50°C into the mold at a rate of 200-300 ml / min until the height of the encapsulating adhesive in the mold reaches 20-22 cm, thus completing the casting process.
9. The high-efficiency casting process for a curtain-type membrane module according to claim 1, characterized in that, The length of the portion cut off during the membrane module cutting is 10~20mm.