A wound filter cartridge filter media for high viscosity fluid filtration and method of making and use thereof

Abstract

The application provides a wound filter core filter layer material for high-viscosity fluid filtration and a preparation method and application thereof, and relates to the technical field of filter core materials. According to mass fraction, the wound filter core filter layer material comprises the following components: 10-25% of a base material polymer, 0.5-10% of modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, 0.2-10% of rigid reinforcing material, 2-8% of a pore former and 55-85% of a solvent; end groups of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer contain crosslinkable groups. Technical problems that the strength of a PEO-PPO-PEO physical blending modified filter layer is reduced, the modifier is lost and the flux and the strength are difficult to be considered in high-viscosity fluid filtration are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of filter material technology, and more specifically, to a wound filter element filter layer material for filtering high-viscosity fluids, its preparation method, and its application. Background Technology

[0002] A wound filter element (also known as a wire-wound filter element or a coiled filter element) is a deep filtration element widely used in the field of liquid filtration. Its typical structure includes three core components: a central tube, a filter layer, and a flow guide layer.

[0003] The central tube serves as the supporting framework for the filter element. It is typically a rigid, porous cylindrical tube with numerous small holes in its wall, acting as both a structural support and a channel for the collection and outflow of the filtered liquid. The filter layer is the core component responsible for filtration, composed of filter materials (such as natural fiber yarns, synthetic fibers, and filter membranes), and tasked with trapping particulate impurities in the fluid. The flow guide layer and filter layer are alternately wound around the central tube, providing a flow path for the filtered liquid while isolating adjacent filter layers to prevent premature clogging. These three elements are tightly bonded together through a winding process, forming a multi-layered, barrel-shaped structure with deep filtration capabilities.

[0004] The selection of filter layer materials for wound filter cartridges is extensive, including natural fibers (such as cotton fibers), synthetic fibers (such as polypropylene and polyester fibers), filter paper, metal mesh, ceramics, and foam materials. Among these, fiber materials are the most commonly used due to their low cost and ease of processing. They are made by regularly winding large-diameter yarns onto a porous core under a certain tension. The alternating winding design of the filter layer and the flow guiding layer allows the fluid to pass through multiple layers of filter media sequentially during radial flow. Particles are trapped layer by layer from coarse to fine, thereby achieving high dirt-holding capacity and filtration accuracy.

[0005] However, when the above-mentioned wound filter elements are used for filtering high-viscosity fluids (such as high-concentration polymer solutions, heavy oil products, viscous chemical liquids, etc.), the existing filter layer materials will have the following problems: (1) The flow resistance of high-viscosity fluids is much higher than that of low-viscosity fluids, and the pressure drop generated when the fluid passes through the filter layer increases significantly. Impurities and colloidal components in high-viscosity fluids are very easy to adhere to the filter material fibers or pore walls, resulting in membrane pore blockage and rapid formation of filter cake layer, and the flux drops sharply under constant pressure operation. (2) High-viscosity fluid filtration usually requires a higher operating pressure to maintain an acceptable flux, but the higher the porosity of the deep filter medium, the easier it is to be compressed by the pressure drop generated when the fluid passes through, the filter layer structure is not stable enough, and it is easy to be compressed and deformed. (3) Most polymer filter materials themselves have a certain degree of hydrophobicity and have a strong affinity for oily and colloidal pollutants in high-viscosity fluids. Pollutants are easily and irreversibly adsorbed on the material surface and in the pores. This irreversible pollution is difficult to recover by conventional backwashing and other means, resulting in a shortened service life of the filter element and an increased replacement frequency.

[0006] Polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO) triblock copolymers are an important class of nonionic amphiphilic surfactants. Their molecular structure consists of a hydrophobic polyoxypropylene (PPO) mid-segment and hydrophilic polyoxyethylene (PEO) segments on both sides. In recent years, researchers have made progress in using this copolymer for the hydrophilic modification of filter membrane materials, significantly improving the hydrophilicity and antifouling ability of the filter layer and significantly increasing water flux. Summary of the Invention

[0007] The inventors discovered several problems when using PEO-PPO-PEO for filter layer modification: ① Adding PEO-PPO-PEO copolymers leads to a decrease in the tensile strength and other mechanical properties of the filter membrane, resulting in reduced mechanical strength. ② PEO-PPO-PEO introduced through physical blending mainly relies on hydrophobic interactions to anchor itself to the matrix. This physical bonding method carries the risk of slow precipitation and loss during long-term use, especially under high shear force, high pressure, and chemical cleaning conditions. ③ It is difficult to simultaneously improve flux and maintain strength. The hydrophilic segments of PEO-PPO-PEO can improve antifouling ability and flux, but for high-viscosity fluid filtration, it leads to strength loss. Therefore, developing a novel wound filter layer material that can leverage the advantages of PEO-PPO-PEO hydrophilic modification while ensuring sufficient mechanical strength and long-term stability has significant research and application value.

[0008] The filter layer material of this application achieves chemical cross-linking and fixation with the substrate polymer through end-group chemical modification of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer. By adding rigid reinforcing materials, the three work synergistically to construct a filter layer material with high hydrophilicity, high anti-fouling properties, high mechanical strength, and long-term operational stability. This solves the technical problems of strength reduction, modifier loss, and difficulty in balancing flux and strength in the filtration of high-viscosity fluids by existing PEO-PPO-PEO physically blended modified filter layers.

[0009] Furthermore, crosslinkable groups are introduced into the modified PEO-PPO-PEO end groups. Through subsequent chemical crosslinking reactions, PEO-PPO-PEO is covalently fixed in the substrate polymer matrix, solving the problem of easy precipitation and loss of physical blending modifiers and ensuring the long-term stability of hydrophilic modification. The rigid reinforcing material forms a physical reinforcing network in the matrix, effectively compensating for the mechanical property loss caused by the introduction of PEO-PPO-PEO, achieving a balance between hydrophilic modification and strength maintenance. Through the leaching of pore-forming agents and solvent replacement during phase inversion, a suitable pore structure and porosity are formed, ensuring that the filter layer material has sufficient permeability and avoiding a sharp decline in permeability due to high viscosity fluid resistance.

[0010] The first aspect of this invention provides a wound filter cartridge filter layer material for filtering high-viscosity fluids, comprising, by mass fraction: 10-25% base polymer, 0.5-10% modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, 0.2-10% rigid reinforcing material, 2-8% pore-forming agent, and 55-85% solvent; The end groups of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer contain crosslinkable groups.

[0011] This application's filter layer material utilizes a modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, introducing crosslinkable groups at the end groups. Through subsequent chemical crosslinking reactions, the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is covalently fixed within the substrate polymer matrix, solving the problem of easy precipitation and loss of physical blending modifiers and ensuring the long-term stability of hydrophilic modification. Simultaneously, rigid reinforcing materials are added to form a physical reinforcing network within the matrix, effectively compensating for the mechanical property loss caused by the introduction of PEO-PPO-PEO, achieving a balance between hydrophilic modification and strength retention. Through the leaching of pore-forming agents and solvent replacement during phase inversion, a suitable pore structure and porosity are formed, ensuring sufficient permeability of the filter layer material and preventing a sharp decline in permeability due to high viscosity fluid resistance.

[0012] Furthermore, the filter layer material of this application provides a filter layer material with high hydrophilicity, high antifouling properties, high mechanical strength, and long-term operational stability through the synergistic combination of the base polymer, modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, rigid reinforcing material, pore-forming agent, and solvent. This solves the technical problems of strength reduction, modifier loss, and difficulty in balancing flux and strength in the filtration of high-viscosity fluids by existing PEO-PPO-PEO physically blended modified filter layers.

[0013] The substrate polymer serves as the main framework of the filter layer material, providing basic mechanical properties and structural support. Insufficient addition results in poor film formation and insufficient strength; excessive addition leads to decreased flux. Insufficient addition of modified PEO-PPO-PEO results in poor hydrophilic modification, while excessive addition leads to over-crosslinking and brittleness. Insufficient addition of rigid reinforcing material results in insignificant reinforcement, while excessive addition easily leads to agglomeration and poor dispersibility.

[0014] For example, the base polymer can be any point value or any range between any two points from 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, or 25%; the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer can be any point value or any range between any two points from 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%; the rigid reinforcing material can be any point value or any range between any two points from 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%; the pore-forming agent can be any point value or any range between any two points from 2%, 3%, 4%, 5%, 6%, 7%, or 8%; and the solvent can be any point value or any range between any two points from 55%, 60%, 65%, 70%, 75%, 80%, or 85%.

[0015] Optionally, by mass fraction, it includes: 15-22% base polymer, 0.6-7% modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, 0.5-8% rigid reinforcing material, 2-6% pore-forming agent, and 65-80% solvent.

[0016] Optionally, the crosslinkable group includes at least one of carbon-carbon double bonds, epoxy groups, hydroxyl groups, carboxyl groups, and amino groups.

[0017] Preferably, the crosslinkable group is a carbon-carbon double bond.

[0018] Optionally, when the crosslinkable group is a carbon-carbon double bond, the preparation method of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer includes the following steps: The polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer was dissolved in an organic solvent, an acid-binding agent was added, and an acylation reagent containing carbon-carbon double bonds was added dropwise under inert gas protection at 0-30℃. The temperature was raised to 20-60℃ for reaction. After separation, purification and drying, the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with carbon-carbon double bonds at the end groups was obtained. The acylation reagent containing a carbon-carbon double bond is selected from at least one of acryloyl chloride, methacryloyl chloride, acrylic anhydride, and methacrylic anhydride.

[0019] Optionally, the molar ratio of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer to the acylation agent containing carbon-carbon double bonds is 1:1 to 1:10.

[0020] Optionally, the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer has a number average molecular weight of 2000-20000, wherein the mass fraction of polyoxyethylene segments is 10%-80%. For example, the number average molecular weight of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer can be any value or a range between any two values ​​from 2000, 5000, 10000, 15000, or 20000; the mass fraction of polyoxyethylene segments can be any value or a range between any two values ​​from 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%.

[0021] Furthermore, controlling the polyoxyethylene (PE) chain segments within a suitable range can further ensure hydrophilicity and antifouling effects. If the PE content is too high, the polyoxypropylene (PO) chain segments will be too short, potentially weakening the interaction with the substrate polymer.

[0022] Optionally, the rigid reinforcing material is selected from at least one of cellulose nanofibers, carbon nanotubes, and nano-silica. Preferably, the rigid reinforcing material is cellulose nanofibers.

[0023] Optionally, the substrate polymer is selected from at least one of polyvinylidene fluoride, polyethersulfone, polysulfone, polyacrylonitrile, polyamide, polyester, polypropylene, and polyethylene.

[0024] Optionally, the pore-forming agent is selected from at least one of polyvinylpyrrolidone and polyethylene glycol.

[0025] Optionally, the solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0026] Optionally, the cellulose nanocrystals are modified cellulose nanocrystals with surface nitrate esterification.

[0027] Optionally, the preparation method of surface-nitrated modified cellulose nanocrystals includes the following steps: mixing a cellulose nanocrystal suspension with a nitrifying agent, reacting at a certain temperature, and then separating, washing, and drying to obtain modified cellulose nanocrystals.

[0028] Optionally, the temperature range is 0-10℃.

[0029] Optionally, the nitrating agent is a mixture of nitric acid and dichloromethane. The mass ratio of nitric acid to dichloromethane is 1:(1-4).

[0030] Optionally, nitric acid accounts for 20-40% of the total mass of the reaction system.

[0031] Furthermore, introducing nitrate ester groups onto the surface of cellulose nanocrystals through nitration can further improve the dispersion performance of cellulose nanocrystals in the system. In addition, as polar groups, the nitrate ester groups can interact with the PEO segments of the PEO-PPO-PEO chain, upgrading from physical mixing to chemical bonding, significantly enhancing interfacial bonding and long-term stability. Furthermore, it can promote uniform dispersion and anchoring of the copolymer, further improving the hydrophilic modification effect.

[0032] A second aspect of the present invention provides a method for preparing a filter layer material for a wound filter cartridge used for filtering high-viscosity fluids, comprising the following steps: (1) Disperse the rigid reinforcing material in a solvent, sonicate it, and then add the substrate polymer, modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and pore-forming agent. Stir at a certain temperature to form a casting solution. (2) The non-woven fabric is attached to the glass plate, and then the casting solution is poured onto the surface of the non-woven fabric for coating. After coating, the obtained membrane is placed in deionized water for phase inversion to obtain the filter layer material. In step (1), the temperature is 60-90℃.

[0033] For example, a certain temperature can be any point value or a range between any two points from 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, or 90℃.

[0034] A fourth aspect of the present invention provides a wound filter element for filtering high-viscosity fluids, comprising a central tube, a flow guiding layer, and a filter layer, wherein the filter layer is made of the filter layer material described above or a filter layer material prepared by the above preparation method.

[0035] Optionally, wound filter cartridges are used for filtering high-viscosity fluids with a viscosity of 100 mPa·s or higher.

[0036] Compared with the prior art, the present invention achieves at least one of the following beneficial effects: (1) The filter layer material of this application provides a filter layer material with high hydrophilicity, high anti-fouling, high mechanical strength and long-term operational stability through the synergistic combination of the base polymer, modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, rigid reinforcing material, pore-forming agent and solvent, so as to solve the technical problems of strength reduction, modifier loss and difficulty in balancing flux and strength of existing PEO-PPO-PEO physical blend modified filter layers in high viscosity fluid filtration.

[0037] (2) The filter layer material of this invention is modified by introducing crosslinkable groups into the end groups of a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer. Through subsequent chemical crosslinking reactions, the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is fixed in the polymer matrix of the substrate in the form of covalent bonds, which solves the problem of easy precipitation and loss of physical blending modifiers and ensures the long-term stability of hydrophilic modification. At the same time, rigid reinforcing materials are added to form a physical reinforcing network in the matrix, which effectively compensates for the loss of mechanical properties caused by the introduction of PEO-PPO-PEO, and achieves a balance between hydrophilic modification and strength maintenance.

[0038] (3) The tensile strength of the filter layer material prepared by the present invention is not less than 4.3 MPa, and the pure water flux is not less than 780 L / m. 2 The flux retention rate of high-viscosity fluids at 150 mPa·s is not less than 75% and the flux decay rate is not higher than 6% after 100 hours of continuous operation. This effectively solves the technical problems of strength reduction, modifier loss and difficulty in balancing flux and strength in the filtration of high-viscosity fluids by existing PEO-PPO-PEO physical blend modified filter layers.

[0039] (4) The wound filter element filter layer material and its preparation method for high viscosity fluid filtration provided by the present invention can be widely used in the filtration and separation process of high viscosity fluids in the fields of petrochemical, fine chemical, food processing, and pharmaceutical manufacturing. Attached Figure Description

[0040] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 An exemplary embodiment of the present invention is shown, which compares the flux retention rates over time for Embodiment 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention. Detailed Implementation

[0041] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0042] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application were all purchased commercially.

[0043] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art.

[0044] Example 1 In an exemplary embodiment of the present invention, the filter layer material of the wound filter cartridge for filtering high-viscosity fluids comprises, by mass fraction: 18% polyethersulfone, 3% modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, 2% cellulose nanofibers, 4% polyvinylpyrrolidone, and 73% N,N-dimethylacetamide.

[0045] The preparation method of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer includes the following steps: dissolving the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer (Pluronic F127, number-average molecular weight approximately 12600, PEO mass fraction approximately 70%) in anhydrous dichloromethane, adding triethylamine under nitrogen protection, and slowly adding acryloyl chloride dropwise at 0°C. After the addition is complete, the temperature is raised to 30°C and reacted for 12 hours. After the reaction is completed, the copolymer is filtered, washed with deionized water, and dried to obtain the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer. The molar ratio of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer to acryloyl chloride is 1:3.

[0046] The preparation method of the filter layer material of the wound filter element includes the following steps: (1) Disperse cellulose nanocrystals in N,N-dimethylacetamide, sonicate for 40 min, then add polyethersulfone, modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and polyvinylpyrrolidone, stir at 75°C for 6 h, and then let stand to degas for 8 h.

[0047] (2) Place the non-woven fabric on a clean glass plate, pour the defoamed casting solution onto the surface of the non-woven fabric, scrape it with a scraper to form a liquid film with a thickness of 200μm, and then immerse it in deionized water to form a membrane and obtain the formed filter layer precursor.

[0048] (3) UV crosslinking treatment of the filter layer precursor: Prepare a 1wt% benzophenone solution by dissolving the photoinitiator benzophenone in anhydrous ethanol. Immerse the filter layer precursor in the benzophenone solution, then remove it and air dry it in the dark. Then place it in a UV crosslinking device and perform UV irradiation crosslinking under nitrogen protection. The UV wavelength is 365nm and the light intensity is 20mW / cm. 2 The light exposure time was 30 minutes. After crosslinking, the filter layer material was soaked in deionized water for 24 hours to remove unreacted photoinitiators and uncrosslinked copolymers, and then dried at 70°C.

[0049] Example 2 Based on Example 1, the main difference is that the filter layer material of the wound filter cartridge used for filtering high-viscosity fluids, by mass fraction, includes: 16% polyvinylidene fluoride, 2% modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, 1.5% cellulose nanofibers, 3% polyethylene glycol, and 77.5% N,N-dimethylformamide.

[0050] The preparation method of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer includes the following steps: Polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer (Pluronic F127, number-average molecular weight approximately 12600, PEO mass fraction approximately 70%) is dissolved in anhydrous dichloromethane. Triethylamine is added under nitrogen protection. Methacrylamide is slowly added dropwise at 0°C. After the addition is complete, the temperature is raised to 50°C and reacted for 10 hours. After the reaction, the copolymer is filtered, washed with deionized water, and dried to obtain the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer. The molar ratio of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer to methacrylic anhydride is 1:4. The remaining steps are the same as in Example 1.

[0051] Example 3 Based on Example 1, the main difference is that the filter layer material of the wound filter element used for filtering high-viscosity fluids, by mass fraction, includes: 20% polysulfone, 1.5% modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, 3.0% cellulose nanocrystals, 5% polyvinylpyrrolidone, and 70.5% N-methylpyrrolidone.

[0052] The preparation method of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer includes the following steps: Polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer (number-average molecular weight approximately 5800, PEO mass fraction approximately 30%) is dissolved in anhydrous dichloromethane, tetrabutylammonium bromide is added, followed by sodium hydroxide, and then epichlorohydrin is slowly added dropwise under stirring. The molar ratio of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer to epichlorohydrin is 1:50. Under nitrogen protection, the reaction temperature is raised to 60℃ and the reaction is carried out for 12 hours. After separation, purification, and drying, the epoxy-modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is obtained.

[0053] The filter layer precursor prepared by phase inversion method was immersed in an ethanol solution of triethylenetetramine (2% by mass) for 15 minutes, then removed and crosslinked at 80°C for 4 hours. After crosslinking, it was immersed in deionized water for 24 hours to remove unreacted curing agent and dried at 70°C.

[0054] The remaining steps are the same as in Example 1.

[0055] Example 4 The main difference from Example 1 is that the rigid reinforcing material is carbon nanotubes. The other steps are the same as in Example 1.

[0056] Example 5 The main difference from Example 1 is that the cellulose nanocrystals are modified cellulose nanocrystals with surface nitrate esterification. The preparation method of the surface nitrate esterified cellulose nanocrystals includes the following steps: mixing a cellulose nanocrystal suspension with a mixture of nitric acid and dichloromethane, reacting at 0°C for 10 min, and then separating, washing, and drying to obtain the modified cellulose nanocrystals. The mass ratio of nitric acid to dichloromethane is 1:3, and nitric acid accounts for 30% of the total mass of the reaction system. The remaining steps are the same as in Example 1.

[0057] Comparative Example 1 Based on Example 1, the main difference is that no modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is added, while the remaining steps are the same as in Example 1.

[0058] Comparative Example 2 Based on Example 1, the main difference is the addition of an unmodified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, while the remaining steps are the same as in Example 1.

[0059] Comparative Example 3 Based on Example 1, the main difference is that cellulose nanofibers are not added, while the rest of the steps are the same as in Example 1.

[0060] Comparative Example 4 The main difference from Example 1 is that the amount of modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer added is 0.2%.

[0061] Comparative Example 5 The main difference from Example 1 is that the amount of modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer added is 15%.

[0062] Comparative Example 6 The main difference from Example 1 is that the amount of cellulose nanocrystals added is 15%.

[0063] Test case The prepared filter layer was subjected to performance testing, and the test results are shown in Table 1.

[0064] Pure water flux test: A dead-end filtration device was used. The filter material (circular sample with a diameter of 60 mm) was placed in the membrane test cell. Under a constant operating pressure of 0.1 MPa, deionized water was used as the test medium. After pre-pressurization for 30 minutes until the flux stabilized, the volume of water permeated over a certain period of time was recorded. Three parallel samples were tested for each group of samples, and the average value was taken.

[0065] High-viscosity fluid flux retention test: A sodium carboxymethyl cellulose aqueous solution with a viscosity of 150 mPa·s was prepared to simulate a high-viscosity fluid. The filter material was cut into circular samples with a diameter of 60 mm and placed in a dead-end filtration test cell. Under a constant operating pressure of 0.3 MPa, the above-mentioned high-viscosity simulated fluid was introduced. The initial flux J0 was recorded at the 5th minute after filtration began. The process was continued for 2 hours, and the flux J at the 2-hour mark was recorded. t Flux retention rate (%) = J t / J0×100%, the average value of 3 parallel samples is taken for each group of samples.

[0066] Flux Decay Rate Test: Under a constant operating pressure of 0.3 MPa, a dead-end filter was used, and a sodium carboxymethyl cellulose aqueous solution at 150 mPa·s was used to simulate a high-viscosity fluid for continuous filtration testing of the filter media. Flux values ​​were recorded every 12 hours, with a test cycle of 100 hours. Flux Decay Rate (%) = (J) 初始 -J 100h ) / J 初始 ×100%.

[0067] Table 1

[0068] Referring to Table 1, the filter layer material prepared by this invention has a tensile strength of not less than 4.3 MPa and a pure water flux of not less than 780 L / m³. 2 The flux retention rate of high-viscosity fluids at 150 mPa·s is not less than 75% and the flux decay rate is not higher than 6% after 100 hours of continuous operation. This effectively solves the technical problems of strength reduction, modifier loss and difficulty in balancing flux and strength in the filtration of high-viscosity fluids by existing PEO-PPO-PEO physical blend modified filter layers.

[0069] Compared with Comparative Example 1, in Example 1, the pure water flux increased from 420 L / (m³) after the addition of modified PEO-PPO-PEO. 2 •h) increased to 852L / (m 2 The water contact angle was significantly reduced, with an increase of 103% (·h), indicating that the hydrophilic modification of PEO-PPO-PEO significantly improved the permeability and antifouling ability of the membrane material.

[0070] Compared with Comparative Example 2, Example 1, which was chemically modified with end groups and chemically crosslinked, showed significantly better long-term stability than Comparative Example 2, which was physically blended but not crosslinked.

[0071] Compared with Comparative Example 3, Example 1 with added cellulose nanofibers had a tensile strength of 4.8 MPa, which was significantly higher than that of Comparative Example 3 without added cellulose nanofibers (3.1 MPa), representing an increase of 55%. This indicates that the rigid reinforcing material effectively compensated for the loss of mechanical properties caused by the introduction of PEO-PPO-PEO.

[0072] refer to Figure 1 As shown, Figure 1 The flux variation curves of the filter layer materials prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 as a function of time when filtering a high-viscosity simulated liquid of 150 mPa·s under an operating pressure of 0.3 MPa are shown. Figure 1 The original data on flux retention rates at each time point were recorded. Example 1 showed a gradual decline, while Comparative Example 2 showed the most severe flux decline.

[0073] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A filter layer material for a wound filter cartridge used for filtering high-viscosity fluids, characterized in that, By mass fraction, it includes: 10-25% base polymer, 0.5-10% modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, 0.2-10% rigid reinforcing material, 2-8% pore-forming agent, and 55-85% solvent; The end groups of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer contain crosslinkable groups.

2. The wound filter element filter layer material for high-viscosity fluid filtration according to claim 1, characterized in that, Crosslinkable groups include at least one of carbon-carbon double bonds, epoxy groups, hydroxyl groups, carboxyl groups, and amino groups.

3. The wound filter element filter layer material for high-viscosity fluid filtration according to claim 2, characterized in that, The crosslinkable group is a carbon-carbon double bond.

4. The wound filter element filter layer material for high-viscosity fluid filtration according to claim 3, characterized in that, When the crosslinkable group is a carbon-carbon double bond, the preparation method of the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer includes the following steps: The polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer was dissolved in an organic solvent, an acid-binding agent was added, and an acylation reagent containing carbon-carbon double bonds was added dropwise under inert gas protection at 0-30℃. The temperature was raised to 20-60℃ for reaction. After separation, purification and drying, the modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with carbon-carbon double bonds at the end groups was obtained. The acylation reagent containing a carbon-carbon double bond is selected from at least one of acryloyl chloride, methacryloyl chloride, acrylic anhydride, and methacrylic anhydride.

5. The wound filter element filter layer material for high-viscosity fluid filtration according to claim 4, characterized in that, The molar ratio of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer to the acylation reagent containing carbon-carbon double bonds is 1:1 to 1:

10.

6. The wound filter element filter layer material for filtering high-viscosity fluids according to claim 1, characterized in that, The modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer has a number average molecular weight of 2000-20000, wherein the mass fraction of polyoxyethylene segments is 10%-80%.

7. The wound filter element filter layer material for high-viscosity fluid filtration according to claim 1, characterized in that, The rigidity-reinforcing material is selected from at least one of cellulose nanofibers, carbon nanotubes, and nano-silica; preferably, the rigidity-reinforcing material is cellulose nanofibers. And / or the substrate polymer is selected from at least one of polyvinylidene fluoride, polyethersulfone, polysulfone, polyacrylonitrile, polyamide, polyester, polypropylene, and polyethylene; And / or the pore-forming agent is selected from at least one of polyvinylpyrrolidone and polyethylene glycol; And / or the solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

8. The wound filter element filter layer material for high-viscosity fluid filtration according to claim 7, characterized in that, The cellulose nanocrystals are modified cellulose nanocrystals with surface nitrate esterification.

9. A method for preparing a wound filter element filter layer material for filtering high-viscosity fluids as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Disperse the rigid reinforcing material in a solvent, sonicate it, and then add the substrate polymer, modified polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and pore-forming agent. Stir at a certain temperature to form a casting solution. (2) The non-woven fabric is attached to the glass plate, and then the casting solution is poured onto the surface of the non-woven fabric for coating. After coating, the obtained membrane is placed in deionized water for phase inversion to obtain the filter layer material. In step (1), the temperature is 60-90℃.

10. A wound filter element for filtering high-viscosity fluids, characterized in that, It includes a central tube, a flow guide layer, and a filter layer, wherein the filter layer is made of the filter layer material according to any one of claims 1 to 8 or the filter layer material prepared by the preparation method according to claim 9.

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