A production process for a refurbished filtration membrane

Abstract

The application relates to the field of filter membrane materials, in particular to a production process of a refurbished filter membrane, which comprises the following steps: 1) removing the shell of a recycled filter membrane, immersing the obtained membrane in a strong alkali solution for 10-15 hours, washing, drying, and obtaining an alkali-washed membrane; 2) rewinding the alkali-washed membrane and winding glass silk on the surface of the alkali-washed membrane to form a glass silk layer; 3) fixing the glass silk through an adhesive to form a protective layer on the surface of the membrane, and obtaining the refurbished filter membrane. Through winding the filter membrane after strong alkali descaling through the glass silk, a protective layer is formed on the surface of the filter membrane, the strength of the membrane after alkali washing is further enhanced, the phenomenon of damage and breakage of the membrane is reduced, the metal and salt substances in the sewage have a blocking effect, and the desalination rate of the membrane is further enhanced.

Description

Technical Field

[0001] This application relates to the field of filter membrane materials, and more specifically, it relates to a manufacturing process for refurbishing filter membranes. Background Technology

[0002] Membrane technology is a highly efficient technology for separation, concentration, purification, and refining, and therefore it is widely used in petrochemical, light industry and textile, food, pharmaceutical, and environmental protection fields.

[0003] Membrane separation technology is widely used in wastewater treatment due to its simple operation, small footprint, and lack of new pollution during the treatment process. Most membranes used in wastewater treatment are filtration membranes, which are generally microporous membranes, including mixed fiber microporous membranes, polypropylene membranes, polyethersulfone membranes, polyvinylidene fluoride membranes, polytetrafluoroethylene membranes, and nylon membranes.

[0004] In wastewater treatment, filter membranes primarily trap substances such as proteins, bacteria, viruses, latex, microparticles, inorganic particles, garbage, and sludge, thereby improving water quality and purifying wastewater. However, after a period of use, the pores of the filter membrane are easily clogged by these substances, affecting its filtration efficiency and reducing its physical strength and flux.

[0005] Therefore, regular replacement of the filter membrane is necessary. Usually, the replaced filter membrane is discarded directly, while some are cleaned and descaled for continued use. However, the cleaning and descaling process requires soaking the membrane in strong alkalis and strong oxidants. While soaking removes a large amount of dirt, it also makes the filter membrane brittle or soft, making it prone to breakage or rupture upon reuse. This reduces its ability to retain substances such as proteins, bacteria, viruses, latex, microparticles, inorganic particles, garbage, and sludge, resulting in a lower desalination rate and thus reduced wastewater treatment efficiency. Therefore, further research is needed to improve the desalination rate of the filter membrane. Summary of the Invention

[0006] To solve the above-mentioned technical problems, this application provides a manufacturing process for refurbishing filter membranes.

[0007] This application provides a manufacturing process for refurbished filter membranes, including the following steps:

[0008] 1) Remove the outer shell of the recovered filter membrane, immerse the resulting membrane in a strong alkaline solution for 10-15 hours, rinse, and dry to obtain an alkaline washed membrane;

[0009] 2) Rewind the alkaline-washed film and wrap glass fibers around its surface to form a glass fiber layer;

[0010] 3) Then, the glass fibers are fixed with adhesive to form a protective layer on the membrane surface, resulting in a refurbished filter membrane.

[0011] The refurbished filter membrane obtained by the above preparation method has better strength and a desalination rate of 80-90% of that of a brand new filter membrane, while the desalination rate of only 20-30% is achieved by strong alkali treatment alone.

[0012] This application improves the cleaning and descaling effect by removing the outer shell of the filter membrane, allowing for better contact with the strong alkaline solution. During the rewinding process, glass fibers are wound around the surface to form a glass fiber layer; this layer is then fixed with adhesive, creating a structurally stable protective layer on the membrane surface, resulting in a refurbished filter membrane.

[0013] Among them, glass fibers are fine filaments made of ordinary glass, plastic or other artificial synthetic materials. They have good strength and flexibility, so they are easy to bend. The protective layer formed by the winding of glass fibers can reduce the possibility of the filter membrane breaking when it is impacted. It can also effectively block sand, stones, garbage and other substances, and further improve the desalination rate of the refurbished filter membrane.

[0014] Furthermore, the tensile strength of the glass fiber in this application is 40-50 MPa. Preferably, it is 42 MPa in the embodiments.

[0015] In summary, this application forms a protective layer on the surface of the filter membrane by winding it with glass fibers after the strong alkali descaling process. This protective layer can further enhance the strength of the membrane after alkali washing, reduce the occurrence of membrane damage and rupture, and at the same time, it has a barrier effect on metals, salts and other substances in wastewater, thereby enhancing the desalination rate of the membrane.

[0016] The strong alkaline solution is obtained by mixing sodium hydroxide and water; or by adding hydrogen peroxide to sodium hydroxide solution, and the pH value of the strong alkaline solution is 12.

[0017] Preferably, the diameter of the glass fiber is 10-80 μm.

[0018] Glass fibers with the above particle size are easy to wind around on the surface of an alkaline film, thus forming a protective film. If the wire diameter is too thick, it is difficult to wind around the surface; if the wire diameter is too thin, it is prone to breakage during winding and pulling.

[0019] Preferably, the adhesive is an epoxy resin adhesive.

[0020] Epoxy resin adhesives possess good adhesion and water resistance, thus stably adhering glass fibers to the surface of the membrane. The epoxy resin adhesive of this application contains 0.5-1.5% epoxy resin curing agent, preferably from the brand Adico, model EP-4010S. Therefore, it can accelerate the curing efficiency of the epoxy resin adhesive during use.

[0021] Preferably, step 2) further includes spraying a filter adhesive onto the surface of the alkaline washing membrane, specifically as follows:

[0022] 2) Spray filter adhesive onto the surface of the alkaline-washed membrane to form a filter reinforcement layer on the membrane surface, then rewind it and wrap glass fibers around the surface of the filter reinforcement layer to form a glass fiber layer.

[0023] The formed filter reinforcement layer not only further improves the strength of the membrane surface, but also further enhances the filtration membrane's ability to block or adsorb substances such as salt and particles in wastewater, thereby further improving the desalination effect of the refurbished filtration membrane.

[0024] Preferably, the filter material is composed of the following raw materials in parts by weight:

[0025] PP: 30-50 copies

[0026] Polyester-based TPU: 3-8 parts

[0027] Ethyl oleate: 1-3 parts

[0028] EAA lotion: 5-8 parts

[0029] EVA emulsion: 10-20 parts

[0030] Filler: 20-30 parts

[0031] Polyvinylidene fluoride: 1-5 parts.

[0032] The composition and dosage range of the aforementioned raw materials are preferred choices for this application. Recycled PP has environmental advantages, while also possessing good strength, toughness, and chemical corrosion resistance. Polyester-based TPU has good strength, toughness, and abrasion resistance, and also exhibits good adhesion in the molten state. Polyvinylidene fluoride (PVDF) has aging resistance, UV resistance, and chemical corrosion resistance. When compounded with PP and TPU, their combined properties result in a filter reinforcement layer with good strength, toughness, abrasion resistance, aging resistance, and corrosion resistance when sprayed. Therefore, when a refurbished filter membrane is obtained and reused after a period of use, corrosion is reduced, improving its practicality. For the second refurbishment, only strong alkaline cleaning is required; the same applies to the third and fourth refurbishments. The membrane is discarded when its desalination rate falls below 30%.

[0033] EAA and EVA emulsions have good adhesion, which further improves the adhesion between the filter material and the filter membrane surface, making the resulting filter reinforcement layer bond stably to the surface of the refurbished filter membrane.

[0034] The filler material not only further enhances the strength of the refurbished filter membrane, but also acts as an adsorbent, further improving the deoxygenation rate of the refurbished filter membrane.

[0035] Ethyl oleate, as a plasticizer, can further enhance the plasticizing effect of the filter material. When the filter material is molten, it is easy to spray through the spraying device, reducing the possibility of the filter material adhering to the nozzle of the spraying device during the spraying process.

[0036] This application utilizes a filter compound made from PP, TPU, polyvinylidene fluoride, EAA emulsion, EVA emulsion, and fillers. By combining the properties of these raw materials, the resulting filter reinforcement layer exhibits excellent adhesion stability, aging resistance, strength, and corrosion resistance. This further enhances the filtration effect on salt compounds in the refurbished filter membrane, improving its durability and desalination rate. Furthermore, the addition of TPU, a polyester with a low melting temperature, allows the filter compound to be sprayed at lower temperatures, thereby improving processing efficiency.

[0037] Preferably, the filler is composed of the following raw materials in parts by weight:

[0038] 2-8 parts of expanded granules

[0039] 5-10 parts of organic fiber filler

[0040] Other fillers: 10-20 parts.

[0041] Expanded granules act as fillers and adsorbents, thereby adsorbing proteins, bacteria, fungi, and other pollutants in wastewater and improving the desalination rate of the refurbished filter membrane. Organic fiber fillers and other fillers have good toughening effects, further enhancing the filtration performance of the refurbished filter membrane.

[0042] Preferably, the expanded particles are expanded graphite and / or expanded perlite; the organic fiber filler is one or more of nylon fiber, chitosan fiber, polyester fiber, and cellulose acetate.

[0043] Both expanded graphite and expanded perlite contain a large number of pores, which have good adsorption properties. As a result, the adsorption properties of the filter reinforcement layer formed by spraying the filter material are further improved, thereby increasing the deoxygenation rate of the refurbished filter membrane.

[0044] When expanded graphite and expanded perlite are combined in a weight ratio of (1-1.5):1, they have a synergistic effect, further improving the deoxygenation rate of the refurbished filter membrane.

[0045] Nylon fiber, polyester fiber, and cellulose acetate all have good strength and toughness, which can further improve the strength and toughness of the filter reinforcement layer, reduce the phenomenon of damage to the refurbished filter membrane, and thus improve the desalination rate.

[0046] Both chitosan fiber and cellulose acetate have good adsorption properties and can adsorb impurities in wastewater, thereby further improving the desalination rate of the refurbished filter membrane.

[0047] When nylon fiber, chitosan fiber, and cellulose acetate are used in combination in a weight ratio of 1:(0.3-1):(0.3-0.5), they have a good toughening and adsorption effect, thereby further improving the desalination rate of the refurbished filter membrane.

[0048] Preferably, the other filler is one or more of carbon fiber, bamboo fiber, glass fiber, and asbestos fiber.

[0049] Carbon fiber refers to high-strength, high-modulus fibers with a carbon content of over 90%, possessing good strength and fiber orientation. Bamboo fiber has good toughness and absorbency. Glass fiber has good strength, and asbestos fiber also has good strength.

[0050] Therefore, carbon fiber, bamboo fiber, glass fiber, or asbestos fiber can all enhance the strength of the filter membrane. Thus, they should be used in the filter reinforcement layer of the refurbished filter membrane to reduce the occurrence of damage to the refurbished filter membrane and improve its filtration effect.

[0051] Preferably, the other fillers are composed of carbon fiber, bamboo fiber, glass fiber and asbestos fiber in a weight ratio of 1:(1.4-2.1):(0.1-0.3):(0.8-1.5).

[0052] When carbon fiber, bamboo fiber, glass fiber, and asbestos fiber are used in combination, their combined properties further improve the strength and adsorption of the filter material, thereby further improving the strength and adsorption of the filter membrane and enhancing the desalination effect.

[0053] Preferably, the filter material is prepared by the following method:

[0054] Weigh the filler, EVA emulsion, and EAA emulsion by weight, mix them evenly, dry them, pulverize them, and sieve them through a 200-500 mesh sieve to obtain a mixture; weigh the polyvinylidene fluoride, PP, ethyl oleate, and the mixture, mix them evenly, heat them to 178-190℃, stir them at a speed of 20-50 r / min for 20-30 min, cool them down to 135-150℃, add polyester TPU, and continue stirring for 20-30 min to obtain a filter adhesive.

[0055] The above preparation method is simple to operate and has high production efficiency. By mixing the filler with EVA emulsion and EAA emulsion, the EVA and EAA emulsions coat the surface of the filler, thereby improving the compatibility between the filler and the filter material raw material system. Then, polyvinylidene fluoride, PP, ethyl oleate, and a mixture are mixed. Under heating, the polyvinylidene fluoride is melted and thoroughly mixed with ethyl oleate and the mixture. After cooling, polyester polyurethane is added and mixed evenly to obtain the filter material. This filter material has good strength and adsorption properties. The filter reinforcement layer formed can further enhance the stability of the refurbished filter membrane structure and improve the adsorption effect of the refurbished filter membrane. In this way, it has a better adsorption effect on impurities in wastewater, and its desalination rate is further improved.

[0056] In summary, this application has the following beneficial effects:

[0057] 1. This application involves winding a glass fiber around a filter membrane after it has been descaled with strong alkali, thereby forming a protective layer on the surface of the filter membrane. This protective layer can further enhance the strength of the membrane after alkali washing, reduce the occurrence of membrane damage and breakage, and at the same time, it has a barrier effect on metals, salts and other substances in wastewater, thereby enhancing the desalination rate of the refurbished filter membrane.

[0058] 2. This application utilizes a filter compound made from PP, TPU, polyvinylidene fluoride, EAA emulsion, EVA emulsion, and fillers. By combining the properties of these raw materials, the filter compound forms a reinforcing layer with excellent adhesion stability, aging resistance, strength, and corrosion resistance. This further enhances the filtration effect on salt compounds in the refurbished filter membrane, improving its durability and desalination rate. Furthermore, the addition of TPU, a polyester with a low melting temperature, allows the filter compound to be sprayed at lower temperatures, thereby improving processing efficiency. Detailed Implementation

[0059] The present application will be further described in detail below with reference to the embodiments.

[0060] Sources of some raw materials:

[0061] The preferred brand for polyester TPU is Bayer Udeland, model U-95A10;

[0062] The average molecular weight of PP is 30,000-50,000, and 50,000 is preferred in the preparation example;

[0063] The EAA emulsion has a solid content of 55%, a viscosity of 5500 cps at 25°C, and an AA content of 8%.

[0064] The EVA emulsion has a solid content of 50%, a viscosity of 3500 cps at 25°C, and a VA content of 23%.

[0065] The average molecular weight of polyvinylidene fluoride is 100,000, and the fluorine content is 60%.

[0066] Example of filter material preparation

[0067] Preparation Example 1

[0068] A filter material is prepared by the following method:

[0069] Weigh 0.2 kg of expanded granules (expanded graphite), 0.5 kg of organic fiber filler (cellulose acetate), and 2 kg of other fillers (carbon fiber), mix them evenly, and obtain the filler.

[0070] Weigh 2 kg of filler, 1 kg of EVA emulsion, and 0.5 kg of EAA emulsion, mix them evenly, put them in an oven at 60°C to dry, then put them in a grinder to grind, and sieve them through a 300-mesh sieve to obtain the mixture.

[0071] Weigh 0.1 kg of polyvinylidene fluoride, 3 kg of PP, and 0.1 kg of ethyl oleate and mix them evenly with all the obtained mixtures. Heat the mixture to 182°C and stir it at 30 r / min for 20 min. Cool it down to 150°C, add 0.3 kg of polyester TPU, and continue stirring for 20 min to obtain the filter material.

[0072] Preparation Example 2

[0073] A filter material is prepared by the following method:

[0074] Weigh 0.5 kg of expanded granules (expanded graphite), 0.8 kg of organic fiber filler (cellulose acetate), and 1.5 kg of other fillers (carbon fiber), mix them evenly, and obtain the filler.

[0075] Weigh out 2.5 kg of filler, 1.5 kg of EVA emulsion, and 0.6 kg of EAA emulsion, mix them evenly, put them in an oven at 60°C to dry, then put them in a grinder to grind, and sieve them through a 300-mesh sieve to obtain the mixture.

[0076] Weigh 0.3 kg of polyvinylidene fluoride, 4 kg of PP, and 0.2 kg of ethyl oleate and mix them evenly with all the obtained mixtures. Heat the mixture to 182°C and stir it at 30 r / min for 20 min. Cool it down to 150°C, add 0.5 kg of polyester TPU, and continue stirring for 20 min to obtain the filter material.

[0077] Preparation Example 3

[0078] A filter material is prepared by the following method:

[0079] Weigh 0.8 kg of expanded granules (expanded graphite), 1 kg of organic fiber filler (cellulose acetate), and 1 kg of other fillers (carbon fiber), mix them evenly, and obtain the filler.

[0080] Weigh out 3 kg of filler, 2 kg of EVA emulsion, and 0.8 kg of EAA emulsion, mix them evenly, put them in an oven at 60°C to dry, then put them in a grinder to grind, and sieve them through a 300-mesh sieve to obtain the mixture.

[0081] Weigh 0.5 kg of polyvinylidene fluoride, 5 kg of PP, and 0.3 kg of ethyl oleate and mix them evenly with all the mixtures obtained above. Heat the mixture to 185°C and stir it at 20 r / min for 30 min. Cool it down to 140°C, add 0.8 kg of polyester TPU, and continue stirring for 30 min to obtain the filter material.

[0082] Preparation Example 4

[0083] The difference between Preparation Example 4 and Preparation Example 1 is that the expanded particles are composed of expanded graphite and expanded perlite in a weight (kg) ratio of 1:1.

[0084] Preparation Example 5

[0085] The difference between Preparation Example 5 and Preparation Example 4 is that the organic fiber filler is composed of nylon fiber, chitosan fiber and cellulose acetate in a weight (kg) ratio of 1:1:0.3.

[0086] Preparation Example 6

[0087] The difference between Preparation Example 6 and Preparation Example 5 is that the other fillers are composed of carbon fiber, bamboo fiber, glass fiber and asbestos fiber in a weight (kg) ratio of 1:1.2:0.3:0.5. Example

[0088] Example 1

[0089] A manufacturing process for refurbished filter membranes includes the following steps:

[0090] 1) Weigh out caustic soda flakes and dissolve them in water, adjust the pH to 12 to obtain a strong alkaline solution; retrieve the filter membrane from the sewage treatment pond to obtain the recovered filter membrane, remove the outer shell of the filter membrane, immerse the obtained membrane completely in the strong alkaline solution for 12 hours, rinse with clean water, and let it air dry in the sun to obtain a dry alkaline washed membrane.

[0091] 2) The alkaline-washed membrane is rewound using a film winding device. During the rewinding process, glass fibers with a diameter of 20 μm are wound around its surface, so that a layer of glass fibers is formed on both sides of the membrane.

[0092] 3) Then, the glass fibers in the glass fiber layer are fixed with epoxy resin to prevent the layer structure of the glass fiber layer from disintegrating. This forms a stable protective layer on the membrane surface, resulting in a refurbished filter membrane.

[0093] Example 2

[0094] The difference between Example 2 and Example 1 is that Example 2 also includes spraying a filter adhesive onto the surface of the alkaline washing membrane. The specific process is as follows:

[0095] 1) Weigh out caustic soda flakes and dissolve them in water, adjust the pH to 12 to obtain a strong alkaline solution; retrieve the filter membrane from the sewage treatment pond to obtain the recovered filter membrane, remove the outer shell of the filter membrane, immerse the obtained membrane completely in the strong alkaline solution for 12 hours, rinse with clean water, and let it air dry in the sun to obtain a dry alkaline washed membrane.

[0096] 2) The filter material of Example 1 was prepared by spraying on the surface of the alkaline washing membrane using a spraying device. The melt spraying temperature of the filter material was 135℃ and the spraying amount was 15g / min. After the spraying was cured, a filter reinforcement layer was formed on both sides of the membrane. The membrane was then rewound. During the rewinding process, glass fibers were wound around the surface of the filter reinforcement layer to form a glass fiber layer.

[0097] 3) Then, the glass fibers in the glass fiber layer are fixed with epoxy resin to prevent the layer structure of the glass fiber layer from disintegrating. This forms a stable protective layer on the membrane surface, resulting in a refurbished filter membrane.

[0098] Examples 3-7

[0099] The difference between Examples 3-7 and Example 2 is that the source of the filter material is different, as shown in Table 1.

[0100] Table 1. Sources of filter media in Examples 2-7

[0101]

[0102] Comparative Example

[0103] Comparative Example 1

[0104] The difference between Comparative Example 1 and Example 1 is that steps 1)-2) are omitted. The specific process is as follows:

[0105] Weigh out caustic soda flakes and dissolve them in water to adjust the pH to 12 to obtain a strong alkaline solution. Retrieve the filter membrane from the sewage treatment pond to obtain the recovered filter membrane. Remove the outer shell of the filter membrane and immerse the entire membrane in the strong alkaline solution for 12 hours. Then rinse it with clean water and let it air dry in the sun to obtain a refurbished filter membrane.

[0106] Performance testing

[0107] Detection methods / test methods

[0108] The refurbished filter membranes obtained in Examples 1-7 and Comparative Example 1 were subjected to the following performance tests.

[0109] Desalination rate: The test was conducted in accordance with the national standard GB / T 32373-2015 Reverse osmosis membrane test method, and the data are shown in Table 2.

[0110] Table 2 shows the experimental data for Examples 1-7 and Comparative Example 1.

[0111]

[0112] As can be seen from Example 1 and Comparative Example 1 and Table 2, the desalination rate of Example 1 is 61.40% higher than that of Comparative Example 1. This indicates that the present application provides better protection by forming a protective layer, thereby reducing the occurrence of ruptures in the filter membrane during use, and improving the desalination rate by blocking some substances in the wastewater.

[0113] Combining Examples 1 and 2, and referring to Table 2, it can be seen that the desalination rate of Example 2 is higher than that of Examples 5-6. This indicates that by forming a filtration enhancement layer on the surface of the filter membrane, this application not only enhances the filter membrane but also provides a certain barrier against impurities, proteins, bacteria, and other substances in boiling water, thereby improving the deoxygenation rate of the Panxin filter membrane.

[0114] As can be seen from Examples 2 and 5, the deoxygenation rate of Example 2 is lower than that of Example 5, indicating that the combination of expanded graphite and expanded perlite has a synergistic effect, further enhancing the deoxygenation rate of the filter membrane.

[0115] Combining Examples 2 and 6, and referring to Table 2, it can be seen that the deoxygenation rate of Example 2 is lower than that of Example 6, indicating that the composite of nylon fiber, chitosan fiber, and cellulose acetate has a synergistic effect, resulting in a better deoxygenation rate of the refurbished filter membrane.

[0116] Combining Examples 2 and 7, and referring to Table 2, it can be seen that the deoxygenation rate of Example 2 is lower than that of Example 7. This indicates that other fillers obtained by combining carbon fiber, bamboo fiber, glass fiber, and asbestos fiber have a better filling effect, can absorb wastewater, improve the strength of the filter membrane, reduce the possibility of damage, and thus improve the deoxygenation rate of the filter membrane.

[0117] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A manufacturing process for refurbished filter membranes, characterized in that, Includes the following steps: 1) Remove the outer shell of the recovered filter membrane, immerse the resulting membrane in a strong alkaline solution for 10-15 hours, rinse, and dry to obtain an alkaline washed membrane; 2) Spray filter adhesive onto the surface of the alkaline washing membrane to form a filter reinforcement layer on the membrane surface, then rewind it and wrap glass fibers around the surface of the filter reinforcement layer to form a glass fiber layer; 3) The glass fibers are then fixed with adhesive to form a protective layer on the membrane surface, resulting in a refurbished filter membrane; The filter material is composed of the following raw materials in parts by weight: PP: 30-50 copies Polyester-based TPU: 3-8 parts Ethyl oleate: 1-3 parts EAA lotion: 5-8 parts EVA emulsion: 10-20 parts Filler: 20-30 parts Polyvinylidene fluoride: 1-5 parts; The filler is composed of the following raw materials in parts by weight: 2-8 parts of expanded granules 5-10 parts of organic fiber filler Other fillers: 10-20 parts; the other fillers are one or more of carbon fiber, bamboo fiber, glass fiber, and asbestos fiber; The expanded particles are expanded graphite and / or expanded perlite; the organic fiber filler is one or more of nylon fiber, chitosan fiber, polyester fiber, and cellulose acetate.

2. The manufacturing process for a refurbished filter membrane according to claim 1, characterized in that: The diameter of the glass filament is 10-80 μm.

3. The manufacturing process for a refurbished filter membrane according to claim 1, characterized in that: The adhesive is an epoxy resin adhesive.

4. The manufacturing process for a refurbished filter membrane according to claim 1, characterized in that: Other fillers consist of carbon fiber, bamboo fiber, glass fiber, and asbestos fiber in a weight ratio of 1:(1.4-2.1):(0.1-0.3):(0.8-1.5).

5. The manufacturing process for a refurbished filter membrane according to any one of claims 1-4, characterized in that, The filter material is prepared by the following method: Weigh the filler, EVA emulsion, and EAA emulsion by weight, mix them evenly, dry them, pulverize them, and sieve them through a 200-500 mesh sieve to obtain a mixture; weigh the polyvinylidene fluoride, PP, ethyl oleate, and the mixture, mix them evenly, heat them to 178-190℃, stir them at a speed of 20-50 r / min for 20-30 min, cool them down to 135-150℃, add polyester TPU, and continue stirring for 20-30 min to obtain a filter adhesive.

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