High flux polyvinylidene fluoride microfiltration membranes with support and methods of making the same
A high-flux, hydrophilic polyvinylidene fluoride (PVDF) microfiltration membrane was prepared by solution blending modification of PVP and PVDF. This method solved the problems of easy fouling and complex modification of PVDF microfiltration membranes, and achieved the preparation of a high-flux, heat-resistant, and chemically stable microfiltration membrane suitable for high-temperature environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 浙江泰林生命科学有限公司
- Filing Date
- 2023-04-06
- Publication Date
- 2026-06-23
AI Technical Summary
Existing polyvinylidene fluoride microfiltration membranes are easily contaminated in biological systems, and existing modification methods are complex and not easy to scale up.
A solution blending modification method using PVP and PVDF was employed. By adding PVP and PVDF to the casting solution and combining physical blending with chemical post-treatment, a microfiltration membrane with high flux, hydrophilicity, and excellent mechanical properties was prepared.
The prepared microfiltration membrane has a flux of up to 1.5×10⁴ L/h/m², excellent heat resistance and chemical stability, long-lasting hydrophilicity, and is suitable for high-temperature environments. Moreover, the preparation process is simple and easy to industrialize.
Smart Images
Figure CN116196772B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of polymer membrane materials technology, specifically to a supported high-flux polyvinylidene fluoride microfiltration membrane and its preparation method. Background Technology
[0002] In recent years, in addition to traditional applications such as water treatment and chemical smelting, membrane separation technology has received increasing attention in areas such as the separation and purification of biosynthetic products and the sterilization and devirulence of pharmaceutical production. Several key national projects have focused on the research of high-efficiency membrane separation technologies, hoping to establish efficient membrane separation and purification processes to meet the continuous and large-scale separation requirements of modern biotechnology products. As the application fields of membrane separation technology continue to expand, industry applications are placing higher demands on the performance of separation membranes. These demands not only require membrane materials to possess excellent heat resistance, chemical stability, and mechanical properties, but also to exhibit superior separation efficiency, hydrophilicity, and resistance to protein adsorption and fouling.
[0003] Currently, commercially available microfiltration membranes are mainly made of materials such as nylon, mixed cellulose, polyethersulfone, and polyvinylidene fluoride (PVDF). However, nylon, mixed cellulose, and polyethersulfone membranes are easily corroded by chemical reagents and their operating temperature cannot exceed 70°C, severely limiting their application. PVDF, on the other hand, possesses excellent chemical resistance, thermal stability, processability, and low leaching, making it an ideal microfiltration membrane material. However, the natural hydrophobicity of PVDF makes its microfiltration membranes susceptible to fouling during biological system treatment. Hydrophilic modification of PVDF microfiltration membranes is an effective way to develop novel, fouling-resistant, high-temperature resistant, chemically resistant, and high-performance separation microfiltration membranes.
[0004] Hydrophilic modification of polyvinylidene fluoride (PVDF) microfiltration membranes mainly includes physical and chemical modifications. Physical modification is typically achieved through multi-component blending and surface coating. While improving the hydrophilicity of PVDF without compromising its excellent properties, physical modification suffers from drawbacks such as the easy leaching of hydrophilic components from the membrane and the inability to maintain the modification effect in the long term. Chemical modification can be achieved through surface grafting, surface polymerization, and plasma treatment, but these methods have many limitations in practice, such as demanding reaction conditions, difficulty in controlling the environment, complex and precise operating equipment, high production costs, and difficulty in scaling up production.
[0005] Chinese patent CN 108261931 A discloses a method for preparing polyvinylidene fluoride (PVDF) microporous filter membranes. The method involves coating a nonwoven fabric support layer with a casting solution composed of PVDF, additives, and a solvent. A high-flux microporous filter membrane is then prepared via a non-solvent-induced phase inversion method, achieving a maximum flux of 2977 L / h / m. 2The drawback of this technical solution is that achieving antifouling performance solely through adding hydrophilic components to the casting solution and soaking the film with surfactants or other pore-retaining agents after film formation is not stable or long-lasting. Chinese patent CN 109482072 A discloses a method for preparing a polyvinylidene fluoride composite membrane with a gradient functional distribution structure. Polyvinylidene fluoride, hydroxyl iron powder, and additives are sequentially dissolved in an organic solvent, and the membrane is dried under an external magnetic field using non-woven fabric as the substrate. The drawback of this technical solution is that the compatibility between hydroxyl iron powder and polyvinylidene fluoride is poor, leading to easy aggregation within the membrane and reducing the hydrophilic modification effect. Furthermore, the drying process requires an external magnetic field, making continuous industrial production difficult.
[0006] In summary, current technologies have some drawbacks, such as complex modification methods and difficulty in large-scale production. Therefore, there is an urgent need for a supported high-flux polyvinylidene fluoride microfiltration membrane and its preparation method to solve the problems existing in the current technology.
[0007] Application content
[0008] The purpose of this application is to address the aforementioned problems in the prior art by providing a supported high-throughput polyvinylidene fluoride microfiltration membrane and its preparation method.
[0009] To achieve the above-mentioned objectives, this application adopts the following technical solution: A method for preparing a supported high-flux polyvinylidene fluoride microfiltration membrane, comprising the following steps:
[0010] S00. Polyvinylidene fluoride powder, polyvinylpyrrolidone or its copolymer, polymethyl methacrylate, non-solvent reagent, volatile reagent and organic solvent are mixed and dissolved into a homogeneous solution, and PVDF blend casting solution is prepared through the homogeneous solution.
[0011] S10. Using PET nonwoven fabric as the support layer, PVDF blend casting liquid is coated onto the support layer and pre-evaporated and treated with a water coagulation bath to obtain a flat PVDF microfiltration membrane with a nascent support layer.
[0012] S20. Immerse the flat PVDF microfiltration membrane in the post-treatment solution. After the reaction is complete, perform a hydrophilicity persistence treatment to obtain a flat PVDF microfiltration membrane with persistent hydrophilicity.
[0013] Further, in step S00, a homogeneous solution is obtained by thoroughly stirring and dissolving the solution within the range of 20-50°C. This homogeneous solution is then used to prepare a PVDF blend casting solution by standing or vacuum degassing.
[0014] Further, in step S00, the organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, or triethyl phosphate.
[0015] Further, in step S00, polyvinylpyrrolidone is at least one of PVP(K60), PVP(K90), PVP(K120), and PVP-VA copolymer.
[0016] Further, in step S00, before mixing the homogeneous solution, the components by mass parts are: 10-20 parts of polyvinylidene fluoride powder, 5-10 parts of polyvinylpyrrolidone or its copolymer, 1-2 parts of polymethyl methacrylate, 3-6 parts of non-solvent reagent, 1-4 parts of volatile reagent, and 65-75 parts of organic solvent.
[0017] Furthermore, in step S10, the liquid film formed by scraping is pre-evaporated in a constant temperature and humidity environment.
[0018] Furthermore, in step S10, the constant temperature and humidity environment is a temperature range of 20-50℃ and a humidity range of 50-90%RH.
[0019] Furthermore, in step S20, the post-treatment solution is an azobisisobutyronitrile solution or a potassium persulfate solution, the treatment temperature is 30-90℃, and the treatment time is 1-24 hours.
[0020] Furthermore, non-solvent reagents include water or glycerol, and volatile reagents include acetone, methanol, or ethanol.
[0021] The supported high-flux polyvinylidene fluoride microfiltration membrane was prepared by the above-described method for preparing a supported high-flux polyvinylidene fluoride microfiltration membrane.
[0022] Compared with the prior art, this application has the following beneficial effects:
[0023] 1. Based on the good compatibility between PVP and PVDF, this application employs a modification method of solution blending linear long-chain, high-molecular-weight PVP (including PVP(K90), PVP(K120), PVP-VA copolymers, etc.) with PVDF. The resulting microfiltration membrane exhibits macroscopic uniformity, excellent performance, high porosity, and interconnected pores. Flux test results demonstrate ultra-high pure water flux; the flux of a 0.45 μm pore size microfiltration membrane can reach 1.5 × 10⁻⁶. 4 L / h / m2, while patent CN108261931A discloses a method for preparing a high-flux supported polyvinylidene fluoride microporous filter membrane, the flux of which is 2977 L / h / m2. 2 Obviously, the flux of the PVDF microfiltration membrane prepared in this application is 5 times that of the original membrane, and it exhibits good heat resistance and chemical stability; at the same time, the non-woven fabric as the support layer endows the membrane material with excellent mechanical properties.
[0024] 2. In this application, after the casting solution solidifies into a film, an initiator is used to initiate a self-crosslinking reaction of PVP in the PVDF matrix. This allows PVP molecules to form a stable covalent bond structure within the PVDF matrix, effectively preventing the dissolution of PVP molecules during the use of the filter membrane and reducing the swelling phenomenon of high molecular weight PVP. The PVDF microfiltration membrane prepared by this application exhibits outstanding hydrophilicity and stability. It can be completely wetted by water within one or two seconds upon contact. Furthermore, even after undergoing dozens of autoclave sterilization and ethylene oxide sterilization processes, it maintains excellent hydrophilicity, meeting the requirements of downstream products such as filter cartridges and membrane packs for high-temperature environments.
[0025] 3. Although this application employs both physical blending and chemical post-treatment modification methods, the raw materials are readily available and the post-treatment can be achieved through soaking. This is different from the harsh and difficult-to-control conditions of general chemical reactions. The entire microfiltration membrane preparation process is simple and straightforward. The prepared PVDF microfiltration membrane has high flux, long-lasting hydrophilicity, excellent mechanical properties, and outstanding chemical stability, enabling low-cost industrial production and large-scale application. Attached Figure Description
[0026] Figure 1 This is an electron microscope image of the surface structure of the PVDF microfiltration membrane in Example 1. Detailed Implementation
[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.
[0028] Example 1:
[0029] 1) Weigh 340g N,N-dimethylacetamide, 30g glycerol and 20g acetone in sequence, mix them evenly, then add 75g polyvinylidene fluoride (Mw: 500,000 to 700,000) powder, 25g polyvinylpyrrolidone (PVP-K60) and 10g polymethyl methacrylate. Stir at 40℃ until completely dissolved, and let stand for 12 hours to remove bubbles after forming a homogeneous solution to obtain PVDF blend casting solution.
[0030] 2) Using PET nonwoven fabric as the support layer, the liquid film thickness is set to 250μm. The casting liquid at a temperature of 20-30℃ is coated onto the substrate by an automatic film coating machine. The liquid film is pre-evaporated for 5 minutes in a constant temperature and humidity environment, and then immersed in a coagulation bath to solidify into a film, thus obtaining a nascent PVDF microfiltration membrane.
[0031] 3) The nascent microfiltration membrane obtained above was immersed in sodium persulfate solution and subjected to a cross-linking reaction at 60°C for 12 hours. Then, the treated PVDF microfiltration membrane was rinsed multiple times with clean deionized water and finally dried and stored to obtain a hydrophilic and stable PVDF microfiltration membrane with a support layer.
[0032] in, Figure 1 The image shows a scanning electron microscope (SEM) image of the hydrophilic PVDF microfiltration membrane obtained in Example 1. As can be seen from the image, the surface pore structure of the PVDF microfiltration membrane in this application is an open network structure, indicating that the PVDF microfiltration membrane has excellent porosity and the pores are interconnected.
[0033] Flux tests were performed on the modified filter membrane using purified water, and the results showed a high flux of 1.5 × 10⁻⁶. 4 L / h / m 2 Hydrophilicity tests showed that the PVDF microfiltration membrane prepared in this application was completely wetted by purified water within 2 seconds. Furthermore, after undergoing moist heat sterilization at 121℃ for 50 hours, the PVDF microfiltration membrane still retained its ability to be wetted by water within 2 seconds.
[0034] Example 2:
[0035] 1) Weigh 325g of N,N-dimethylacetamide, 15g of water and 5g of acetone in sequence, mix them evenly, then add 100g of polyvinylidene fluoride (Mw: 500,000 to 700,000) powder, 50g of polyvinylpyrrolidone (PVP-K90) and 5g of polymethyl methacrylate. Stir at 40°C until completely dissolved, and let stand for 12 hours to remove bubbles after forming a homogeneous solution to obtain PVDF blend casting solution.
[0036] 2) Using PET nonwoven fabric as the support layer, the liquid film thickness is set to 250μm. The casting liquid at a temperature of 20-30℃ is coated onto the substrate by an automatic coating machine. The liquid film is pre-evaporated for 10 minutes in a constant temperature and humidity environment, and then immersed in a coagulation bath to solidify into a film, thus obtaining a nascent PVDF microfiltration membrane.
[0037] 3) The nascent microfiltration membrane obtained above is immersed in potassium persulfate solution and crosslinked at 50°C for 24 hours. Then, the treated PVDF microfiltration membrane is rinsed multiple times with clean deionized water and finally dried and stored to obtain a hydrophilic and stable PVDF microfiltration membrane with a support layer.
[0038] Flux tests were performed on the modified filter membrane using purified water, and the result was as high as 1.1 × 10⁻⁶. 4 L / h / m 2Hydrophilicity tests showed that the PVDF microfiltration membrane prepared in this application was completely wetted by purified water within 5 seconds. Furthermore, after undergoing moist heat sterilization at 121℃ for 40 hours, the PVDF microfiltration membrane still retained its ability to be wetted by water within 5 seconds.
[0039] Example 3:
[0040] 1) Weigh 340g of N,N-dimethylformamide, 25g of glycerol and 10g of ethanol in sequence, mix them evenly, then add 80g of polyvinylidene fluoride (Mw of 300,000 to 500,000) powder, 40g of polyvinylpyrrolidone copolymer (PVP-VA) and 5g of polymethyl methacrylate. Stir at 40℃ until completely dissolved, and let stand for 12 hours to remove bubbles after forming a homogeneous solution to obtain PVDF blend casting solution;
[0041] 2) Using PET nonwoven fabric as the support layer, the liquid film thickness is set to 250μm. The casting liquid at a temperature of 20-30℃ is coated onto the substrate by an automatic coating machine. The liquid film is pre-evaporated for 10 minutes in a constant temperature and humidity environment, and then immersed in a coagulation bath to solidify into a film, thus obtaining a nascent PVDF microfiltration membrane.
[0042] 3) The nascent microfiltration membrane obtained above was immersed in an azobisisobutyronitrile solution and subjected to a crosslinking reaction at 80°C for 5 hours. Then, the treated PVDF microfiltration membrane was rinsed multiple times with clean deionized water and finally dried and stored to obtain a hydrophilic and stable PVDF microfiltration membrane with a support layer.
[0043] Flux tests were performed on the modified filter membrane using purified water, and the result was as high as 1.3 × 10⁻⁶. 4 L / h / m 2 Hydrophilicity tests showed that the PVDF microfiltration membrane prepared in this application was completely wetted by purified water within 5 seconds. Furthermore, after undergoing moist heat sterilization at 121℃ for 25 hours, the PVDF microfiltration membrane still retained its ability to be wetted by water within 5 seconds.
[0044] Example 4:
[0045] 1) Weigh 200g of N,N-dimethylformamide, 140g of N-methylpyrrolidone, 25g of glycerol and 10g of acetone in sequence, mix them evenly, and then add 80g of polyvinylidene fluoride (Mw of 500,000 to 700,000) powder, 40g of polyvinylpyrrolidone copolymer (PVP-K90) and 5g of polymethyl methacrylate. Stir at 40°C until completely dissolved, and let it stand for 12 hours to remove bubbles after forming a homogeneous solution to obtain PVDF blend casting solution.
[0046] 2) Using PET nonwoven fabric as the support layer, the liquid film thickness is set to 250μm. The casting liquid at a temperature of 20-30℃ is coated onto the substrate by an automatic coating machine. The liquid film is pre-evaporated for 10 minutes in a constant temperature and humidity environment, and then immersed in a coagulation bath to solidify into a film, thus obtaining a nascent PVDF microfiltration membrane.
[0047] 3) The nascent microfiltration membrane obtained above is immersed in sodium persulfate solution and crosslinked at 90°C for 1 hour. Then, the treated PVDF microfiltration membrane is rinsed several times with clean deionized water and finally dried and stored to obtain a hydrophilic and stable PVDF microfiltration membrane with a support layer.
[0048] Flux tests were performed on the modified filter membrane using purified water, and the result was as high as 9.8 × 10⁻⁶. 3 L / h / m 2 Hydrophilicity tests showed that the PVDF microfiltration membrane prepared in this application was completely wetted by purified water within 5 seconds. Furthermore, after undergoing five consecutive ethylene oxide sterilization treatments, the PVDF microfiltration membrane still retained its ability to be wetted by water within 5 seconds.
[0049] Control group 1:
[0050] 1) Weigh 340g of N,N-dimethylformamide and 35g of water in sequence, mix them evenly, and then add 80g of polyvinylidene fluoride (Mw is 500,000 to 700,000) powder, 40g of polyvinylpyrrolidone copolymer (PVP-K120) and 5g of polymethyl methacrylate. Stir at 40℃ until completely dissolved, and after a homogeneous solution is formed, let it stand for 12 hours to remove bubbles to obtain PVDF blend casting solution;
[0051] 2) Using PET nonwoven fabric as the support layer, the liquid film thickness is set to 250μm. The casting liquid at a temperature of 20-30℃ is coated onto the substrate by an automatic film coating machine. The liquid film is pre-evaporated for 5 minutes in a constant temperature and humidity environment, and then immersed in a coagulation bath to solidify into a film, thus obtaining a nascent PVDF microfiltration membrane.
[0052] 3) The nascent microfiltration membrane obtained above is immersed in an azobisisobutyronitrile solution and crosslinked at 30°C for 24 hours. Then, the treated PVDF microfiltration membrane is rinsed multiple times with clean deionized water and finally dried and stored to obtain a hydrophilic and stable PVDF microfiltration membrane with a support layer.
[0053] The flux of the modified filter membrane was tested with purified water, and the result was 7.2 × 10⁻⁶. 3 L / h / m 2 The hydrophilicity test results show that the PVDF microfiltration membrane prepared in this application is completely wetted by purified water in about 2 minutes.
[0054] The parts not described in detail in this application are prior art, and therefore are not described in detail in this application.
[0055] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.
[0056] Although this document uses a significant amount of technical terminology, the possibility of using other terms is not excluded. These terms are used merely to facilitate the description and explanation of the nature of this application; interpreting them as any additional limitation would be contrary to the spirit of this application.
[0057] This application is not limited to the above-described preferred embodiments. Anyone can derive other products in various forms under the guidance of this application. However, regardless of any changes made to their shape or structure, any product with the same or similar technical solution as this application falls within the protection scope of this application.
Claims
1. A method for preparing a supported high-flux polyvinylidene fluoride microfiltration membrane, characterized in that, Includes the following steps: S00. Polyvinylidene fluoride powder, polyvinylpyrrolidone or its copolymer, polymethyl methacrylate, non-solvent reagent, volatile reagent and organic solvent are mixed and dissolved into a homogeneous solution, and PVDF blend casting solution is prepared through the homogeneous solution. S10. Using PET nonwoven fabric as a support layer, the PVDF blend casting liquid is coated onto the support layer and pre-evaporated and treated with a water coagulation bath to obtain a flat PVDF microfiltration membrane with a nascent support layer. S20. The flat PVDF microfiltration membrane is immersed in a post-treatment solution. After the reaction is completed, a hydrophilicity persistence treatment is performed to obtain a flat PVDF microfiltration membrane with persistent hydrophilicity. The post-treatment solution is an azobisisobutyronitrile solution or a potassium persulfate solution, the treatment temperature is 30-90℃, and the treatment time is 1-24 hours.
2. The method for preparing a supported high-flux polyvinylidene fluoride microfiltration membrane according to claim 1, characterized in that, In step S00, a homogeneous solution is obtained by thoroughly stirring and dissolving the solution within a temperature range of 20-50°C. This homogeneous solution is then subjected to static or vacuum degassing to obtain the PVDF blend casting solution.
3. The method for preparing a supported high-flux polyvinylidene fluoride microfiltration membrane according to claim 1, characterized in that, In step S00, the organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, or triethyl phosphate.
4. The method for preparing a supported high-flux polyvinylidene fluoride microfiltration membrane according to claim 1, characterized in that, In step S00, the polyvinylpyrrolidone is at least one of PVP(K60), PVP(K90), PVP(K120), and PVP-VA copolymer.
5. The method for preparing a supported high-flux polyvinylidene fluoride microfiltration membrane according to claim 1, characterized in that, In step S00, before mixing the homogeneous solution, the composition by mass parts is as follows: 10-20 parts of polyvinylidene fluoride powder, 5-10 parts of polyvinylpyrrolidone or its copolymer, 1-2 parts of polymethyl methacrylate, 3-6 parts of non-solvent reagent, 1-4 parts of volatile reagent, and 65-75 parts of organic solvent.
6. The method for preparing a supported high-flux polyvinylidene fluoride microfiltration membrane according to claim 1, characterized in that, In step S10, the liquid film formed by scraping is pre-evaporated in a constant temperature and humidity environment.
7. The method for preparing a supported high-flux polyvinylidene fluoride microfiltration membrane according to claim 6, characterized in that, In step S10, the constant temperature and humidity environment is a temperature range of 20-50℃ and a humidity range of 50-90%RH.
8. The method for preparing a supported high-flux polyvinylidene fluoride microfiltration membrane according to any one of claims 1-7, characterized in that, The non-solvent reagent includes water or glycerol, and the volatile reagent includes acetone, methanol, or ethanol.
9. A supported high-flux polyvinylidene fluoride microfiltration membrane, characterized in that, It was prepared by the method for preparing a supported high-throughput polyvinylidene fluoride microfiltration membrane according to any one of claims 1-8.