Nanometer electrostatic spinning fiber filter material and preparation method thereof

Abstract

The invention relates to a nano electrostatic spinning fiber filter material and a preparation method thereof. According to the method, a PVA nanofiber membrane is prepared through an electrostatic spinning technology, and the PVA nanofiber membrane is compounded to a polypropylene (PP) needled felt material base material through a hot pressing technology. The preparation method specifically comprises the following steps: dissolving PVA to form a spinning solution, and adding a PEO-PPO-PEO block copolymer and an antistatic filler to enhance interface bonding force and antistatic performance; preparing a fiber membrane by using electrostatic spinning equipment, and controlling the thickness of the membrane to be 0.3-0.5 mu m; interface combination is optimized through a hot pressing process, and the efficient and stable composite filter material is formed. The prepared filter material has excellent filtering efficiency and mechanical strength, can be used in a high-humidity and high-flow-rate environment, and effectively captures micron and submicron particles. The technology is widely applied to the fields of industrial filtration, waste gas treatment and liquid separation, and has relatively high stability, durability and applicability.

Description

Technical Field

[0001] The invention relates to the technical field of filter materials, and in particular to a nano electrostatically spun fiber filter material and a preparation method thereof. Background Art

[0002] As a new type of high-efficiency filtration material, nano-electrospinning fiber materials have been widely used in the field of industrial filtration in recent years. Electrospinning technology stretches polymer solutions or melts into nano-scale fibers through a high-voltage electric field, and is a key process for preparing ultrafine fibers. Compared with traditional filtration materials, electrospun nanofibers have high specific surface area, high porosity and good multifunctional potential, which makes them show excellent filtration performance in industrial dust removal, waste gas purification, liquid separation and other fields. Polyvinyl alcohol (PVA), as a common electrospinning material, has been widely used in industrial filtration membrane materials due to its excellent film-forming properties, chemical stability and environmental protection characteristics. However, the mechanical strength of a single polyvinyl alcohol nanofiber membrane is weak and it is difficult to withstand industrial high flow rates and high pressure environments. Therefore, the composite of polyvinyl alcohol nanofiber membrane and polypropylene (PP) needle felt material can not only maintain its high-efficiency filtration characteristics, but also use the mechanical support of polypropylene (PP) needle felt material to form a composite filter material with both strength and functionality, which has become an important development direction of industrial filtration technology.

[0003] In the prior art, silica sol is generally sprayed on the surface of polypropylene (PP) needle felt material, PVA nanofiber membrane is laid flat on the surface of polypropylene (PP) needle felt material, and composited by roller extrusion, then left to stand, and put into an oven for drying to obtain filter material. Under high humidity conditions, the surface of silica sol particles is rich in hydroxyl (-OH), which binds to water molecules in the air through hydrogen bonds, causing the particles to absorb moisture and expand, thereby causing structural changes. The adsorption of moisture reduces the electrostatic repulsion between particles, making the particles easy to aggregate or agglomerate, resulting in a decrease in the uniformity and stability of the coating or membrane. In addition, the hygroscopic effect will also cause the porosity in the silica sol coating to decrease, and some pores may be blocked by moisture, further increasing the airflow resistance and reducing the filtration performance. In a high flow rate environment, the silica sol coating may fail due to the high shear force and impact force of the airflow. The shear stress applied to the coating by the high-speed airflow may exceed the binding force between the particles, causing the particles to fall off or the surface to be damaged. In addition, the particles or droplets in the high-velocity airflow hit the coating at high speed, which may cause surface erosion and structural damage, thereby affecting the filtration accuracy. At the same time, high flow rates may exert a compressive effect on the pore walls of the coating, further reducing the porosity and causing an increase in pressure drop, leading to increased energy consumption and deterioration of filtration performance. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing a nano electrospun fiber filter material, comprising the following technical steps:

[0005] Step S1. Add PVA to deionized water at a concentration of 10wt%-15wt%, stir in a constant temperature water bath at 80-90°C until completely dissolved to form a uniform and transparent polymer solution, cool to 40-50°C, add PEO-PPO-PEO block copolymer and antistatic filler, and ultrasonically disperse for 10-20 minutes to form a spinning solution; Step S2. Inject the spinning solution into an electrospinning device and uniformly deposit it on a receiving device to form a PVA nanofiber membrane; Step S3. Use a polypropylene (PP) needle-punched felt material as a substrate, cover the PVA nanofiber membrane on the surface of the polypropylene (PP) needle-punched felt material, and compound it through a hot pressing process.

[0006] It should be noted that in step S1, PVA is dissolved in deionized water to form a uniform polymer solution. PVA is a water-soluble polymer with excellent film-forming properties. The hydroxyl structure in its molecular chain interacts through hydrogen bonds to provide intermolecular adhesion for subsequent electrospinning. By heating the solution to 80-90°C, the activity and solubility of the molecular chain are improved to ensure the uniformity of the solution. After cooling to 40-50°C, PEO-PPO-PEO block copolymer and antistatic filler are added. On the one hand, the PEO-PPO-PEO block copolymer can improve the flexibility of the PVA material through its flexible PPO segment, thereby reducing the brittleness of the material. On the other hand, PEO-PPO-PEO enhances the interfacial bonding force between the fiber membrane and the polypropylene (PP) needle felt material through the synergistic effect of the hydrophilic (PEO) and hydrophobic (PPO) segments, while the antistatic filler improves the antistatic ability of electrospinning. Ultrasonic dispersion makes the functional components evenly distributed in the solution to form a spinning solution suitable for spinning. In step S2, after the spinning solution is injected into the electrospinning equipment, under the action of the high-voltage electric field, the spinning solution forms a Taylor cone at the end of the needle. When the electrostatic force overcomes the surface tension of the droplet, the liquid flow is ejected and stretched into nanofibers. In this process, the solvent evaporates quickly, and the PVA molecular chain solidifies into a fiber form to form a high specific surface area fiber membrane with nanoscale pores. The diameter and distribution of the fiber are affected by factors such as the electric field strength, the concentration of the spinning solution, and the injection speed. The receiving device (such as a rotating drum) provides a deposition surface, and the fibers are uniformly deposited on it to form a multilayer structure. In step S3, during the hot pressing composite process, the PVA nanofiber membrane is evenly covered on the surface of the polypropylene (PP) needle felt material, and the composite is achieved through the action of temperature and pressure. The molecular chain behavior of PEO-PPO-PEO is changed by high temperature and pressure, so that it is dynamically rearranged and oriented at the interface. Specifically, the hydrophilic PEO segments are stretched and rearranged in the direction of the PVA fibers at high temperatures, forming a large number of hydrogen bonding points with the hydroxyl groups in the PVA, increasing the adhesion area and bonding force of the interface. The hydrophobic PPO segments are rearranged in the direction of the polypropylene (PP) needle felt cloth under pressure, and are tightly bonded to the non-polar molecular chains of the polypropylene (PP) needle felt material through hydrophobic interactions and van der Waals forces. This rearrangement and orientation behavior of the molecular chains is locked in the cooling stage to form stable physical cross-linking points, which greatly improves the overall strength of the interface bonding. In addition, high temperature and pressure compress the thickness of the PEO-PPO-PEO interface layer, eliminate the common micropores in the direct bonding interface, and form a high-density molecular stacking structure. This dense interface layer shows excellent stability in a high-humidity environment. The PEO segment effectively alleviates the swelling effect by forming hydrogen bonds and hydration with water molecules. At the same time, the hydrophobic barrier formed by the PPO segment on the surface of the polypropylene (PP) needle felt cloth repels the intrusion of water and protects the integrity of the bonding point.Under high flow rate environment, the molecular bridge structure and dense stacking layer in the hot pressing interface can disperse the shear stress, improve the friction resistance and anti-delamination ability of the interface, while the interface of directly bonded PVA and polypropylene (PP) needle-punched felt cloth lacks such molecular bridge and micro-optimized structure, and is prone to slippage or delamination under swelling and flow rate impact.

[0007] As a preferred technical solution for the preparation of nano electrospun fiber filter material, in step S1, the PEO-PPO-PEO block copolymer accounts for 4wt% to 6wt% of the mass of PVA.

[0008] It should be noted that the addition amount of the PEO-PPO-PEO block copolymer was optimized.

[0009] As a preferred technical solution for the preparation of nano electrospun fiber filter material, in step S1, the antistatic filler is graphene and hexadecyltrimethylammonium bromide, and the antistatic filler accounts for 0.1wt% to 0.3wt% of the mass of PVA.

[0010] It should be noted that CTAB is a cationic surfactant. The long-chain alkyl groups in its molecules bind to the hydrophobic regions on the graphene surface through hydrophobic interactions. 16 H 33 N + (CH3)3) imparts a positive charge to the graphene surface through electrostatic adsorption. This dual effect enhances the dispersibility of graphene in polar solutions (such as PVA matrix solutions) and prevents graphene sheets from agglomerating. During the filter material compounding process, CTAB cations form a stable charge layer on the graphene surface, which not only improves the conductivity of graphene, but also enhances its interfacial charge migration ability with the PVA matrix. This interface optimization reduces the charge accumulation phenomenon, makes the charge distribution on the filter material surface more uniform, and reduces the risk of discharge that may be caused by static electricity concentration. At the same time, the high dispersibility of CTAB-modified graphene makes the conductive path inside the filter material more uniform, enhances the overall charge discharge capacity, and significantly reduces the surface resistance of the filter material, thereby achieving an antistatic effect.

[0011] As a preferred technical solution for the preparation method of nano electrospinning fiber filter material, in step S2, the process parameters of the electrospinning equipment are: spinning voltage of 15kV to 25kV, injection speed of 0.5ml / min to 1.0ml / min, distance between needle and receiving device of 15cm to 20cm, working temperature of 20℃ to 30℃ and relative humidity of 40% to 60%.

[0012] It should be noted that the process parameter setting of the electrospinning equipment plays a key role in the quality and performance of the PVA nanofiber membrane. The spinning voltage is set to 15kV to 25kV, which is mainly used to overcome the surface tension of the spinning solution and produce a stable Taylor Cone. The choice of voltage directly affects the jet intensity and fiber diameter of the spinning solution. A lower voltage may lead to unstable spinning, while a too high voltage may cause the fiber to be overstretched, resulting in breakage or the formation of non-uniform fibers. The injection speed is set to 0.5ml / min to 1.0ml / min to ensure that the spinning solution is supplied at a constant speed to maintain the stability of the spinning process; too high a speed may cause droplet accumulation and affect fiber formation, while too low a speed may cause uneven fiber diameter. The distance between the needle and the receiving device is 15cm to 20cm, which is used to control the solvent volatilization and stretching time of the fiber during flight. If the distance is too short, the fiber may not be fully solidified and adhere, affecting the porosity and structure of the fiber membrane; if it is too long, the fiber may be unevenly dispersed, affecting the uniformity of the membrane. The working temperature of 20℃ to 30℃ and the relative humidity of 40% to 60% are used to regulate the volatilization rate of the spinning solution and the surface quality of the fiber. At lower humidity, too fast evaporation of the solvent may cause the fiber surface to be rough; while too high humidity may cause fiber adhesion or diameter fluctuation. By optimizing the above process parameters, it is possible to ensure that the nanofiber membrane has a uniform diameter distribution, high porosity and excellent filtration performance, laying the foundation for the subsequent composite steps.

[0013] As a preferred technical solution for the preparation of a nano-electrospinning fiber filter material, the thickness of the PVA nanofiber membrane is 0.3 to 0.5 um.

[0014] It should be noted that, on the one hand, the moderate thickness during the hot pressing process enables the hot pressing pressure to be evenly transmitted to the interior of the fiber, preventing local damage or interface stratification due to stress concentration, thereby improving the overall mechanical strength and stability of the composite filter material. On the other hand, the appropriate thickness can enable the filter material to maintain a relatively high filtration efficiency.

[0015] As a preferred technical solution for the preparation of nano electrospun fiber filter material, the parameters of the hot pressing process are: hot pressing temperature of 80°C to 100°C, hot pressing pressure of 1 to 2MPa, and hot pressing time of 10 to 20s.

[0016] It should be noted that the hydrophilic PEO chain segments are stretched and rearranged in the direction of the PVA fibers at an appropriate temperature, forming a large number of hydrogen bonding points with the hydroxyl groups in the PVA, increasing the adhesion area and bonding strength of the interface. The hydrophobic PPO chain segments are rearranged in the direction of the polypropylene (PP) needle felt cloth under appropriate pressure, and are tightly bonded to the non-polar molecular chains of the polypropylene (PP) needle felt material through hydrophobic interactions and van der Waals forces. This rearrangement and orientation behavior of the molecular chains is locked in the cooling stage to form stable physical cross-linking points, which greatly improves the overall strength of the interface bonding.

[0017] In addition, the present invention provides a nano-electrospinning fiber industrial filter material prepared by the above-mentioned preparation method, which is specially designed for industrial filtration scenarios and has excellent filtration efficiency and mechanical properties. The PVA nanofiber membrane prepared by the electrospinning process exhibits a high specific surface area and a fine pore distribution, providing an ideal structural basis for industrial waste gas treatment, liquid separation, and high-precision particle capture. Under the action of the hot pressing process (temperature 80°C to 100°C, pressure 1 to 2MPa, time 10 to 20 seconds), a strong interfacial bonding force is formed between the fiber membrane and the polypropylene (PP) needle felt material substrate, which greatly improves the compression resistance, durability and long-term operation stability of the filter material. The PVA nanofiber membrane thickness of the industrial filter material is 0.3 to 0.5um, which can effectively capture micron and submicron particles in industrial waste gas or liquid, and is suitable for complex working conditions with high flow rate and high pressure difference.

[0018] The nano electrostatically spun fiber filter material of the present invention has the following beneficial effects:

[0019] First, the PVA nanofiber membrane prepared by electrospinning technology has a high specific surface area and a fine pore structure, which effectively improves the particle capture efficiency. The optimized preparation process ensures that the thickness of the fiber membrane is between 0.3 and 0.5um. The membrane within this range can not only maintain a high filtration efficiency, but also has good mechanical strength and stability. Secondly, through the optimization of the hot pressing process, the molecular chains of the PEO-PPO-PEO block copolymer are dynamically rearranged at the interface between the fiber membrane and the substrate. The hydrophilic segment (PEO) forms a hydrogen bond with the hydroxyl group in PVA, and the hydrophobic segment (PPO) forms a hydrophobic effect and van der Waals force with the polypropylene (PP) needle felt substrate. This dual effect significantly enhances the interfacial bonding force, allowing the fiber membrane to remain stable under harsh conditions of high humidity and high flow rate without stratification or detachment, thereby improving the overall filtration performance of the filter material. In addition, the strong interfacial bonding force significantly improves the structural stability of the fiber membrane and the substrate, avoids the occurrence of airflow bypass or leakage, and ensures the integrity of the filtration path. The enhanced binding force also improves the impact resistance and long-term durability of the composite filter material by dispersing mechanical stress. Finally, the filter material shows excellent stability in high humidity and high flow rate environments. The PEO segment alleviates the swelling effect by forming hydrogen bonds with water molecules, and the hydrophobic barrier formed by the PPO segment on the substrate surface effectively protects the interface bonding point. The synergistic effect of the overall structural design and material properties makes the filter material of the present invention show excellent application potential in industrial waste gas treatment, liquid separation and high-precision particle capture. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0023] Example 1

[0024] Embodiment 1 provides a nano electrospun fiber filter material and a preparation method thereof, wherein:

[0025] The preparation method of nano electrostatic spinning fiber filter material includes the following technical steps:

[0026] Step S1. Add PVA at a concentration of 10wt% to deionized water, stir in a constant temperature water bath at 90°C until completely dissolved to form a uniform and transparent polymer solution, cool to 40°C, add PEO-PPO-PEO block copolymer and antistatic filler, and ultrasonically disperse for 10 minutes to form a spinning solution; wherein the PEO-PPO-PEO block copolymer accounts for 4wt% of the mass of PVA, and the antistatic filler is hexadecyltrimethylammonium bromide, and the antistatic filler accounts for 0.1wt% of the mass of PVA.

[0027] Step S2. injecting the spinning solution into the electrospinning device and uniformly depositing it on the receiving device to form a PVA nanofiber membrane; wherein the process parameters of the electrospinning device are a spinning voltage of 15 kV, a push injection speed of 1.0 ml / min, a distance between the needle and the receiving device of 20 cm, an operating temperature of 20° C., and a relative humidity of 60%;

[0028] Step S3. Use polypropylene (PP) needle-punched felt material as a substrate, cover the PVA nanofiber membrane on the surface of the polypropylene (PP) needle-punched felt material, and compound it through a hot pressing process. The hot pressing temperature is 100° C., the hot pressing pressure is 1 MPa, and the hot pressing time is 20 s.

[0029] Nano electrospun fiber filter material: The nano electrospun fiber filter material prepared by the above preparation method comprises a polypropylene (PP) needle-punched felt layer and a PVA nanofiber membrane, wherein the thickness of the PVA nanofiber membrane is 0.3 um.

[0030] Example 2

[0031] Embodiment 2 provides a nano electrospun fiber filter material and a preparation method thereof, wherein:

[0032] The preparation method of nano electrostatic spinning fiber filter material includes the following technical steps:

[0033] Step S1. Add PVA at a concentration of 12wt% to deionized water, stir in a constant temperature water bath at 80°C until completely dissolved to form a uniform and transparent polymer solution, cool to 45°C, add PEO-PPO-PEO block copolymer and antistatic filler, and ultrasonically disperse for 10 minutes to form a spinning solution; wherein the PEO-PPO-PEO block copolymer accounts for 6wt% of the mass of PVA, and the antistatic filler is hexadecyltrimethylammonium bromide, and the antistatic filler accounts for 0.2wt% of the mass of PVA.

[0034] Step S2. Injecting the spinning solution into the electrospinning device and uniformly depositing it on the receiving device to form a PVA nanofiber membrane; wherein the process parameters of the electrospinning device are a spinning voltage of 25 kV, a push injection speed of 0.8 ml / min, a distance between the needle and the receiving device of 15 cm, an operating temperature of 30° C., and a relative humidity of 40%;

[0035] Step S3. Use polypropylene (PP) needle felt material as a substrate, cover the PVA nanofiber membrane on the surface of the polypropylene (PP) needle felt material, and compound it through a hot pressing process. The hot pressing temperature is 80°C, the hot pressing pressure is 1 MPa, and the hot pressing time is 10 s.

[0036] Nano electrospun fiber filter material: The nano electrospun fiber filter material prepared by the above preparation method comprises a polypropylene (PP) needle-punched felt layer and a PVA nanofiber membrane, wherein the thickness of the PVA nanofiber membrane is 0.5 um.

[0037] Example 3

[0038] Embodiment 3 provides a nano electrospun fiber filter material and a preparation method thereof, wherein:

[0039] The preparation method of nano electrostatic spinning fiber filter material includes the following technical steps:

[0040] Step S1. PVA is added to deionized water at a concentration of 15wt%, stirred in a constant temperature water bath at 85°C until completely dissolved to form a uniform and transparent polymer solution, cooled to 50°C, PEO-PPO-PEO block copolymer and antistatic filler are added, and ultrasonic dispersion is performed for 10-20 minutes to form a spinning solution; wherein the PEO-PPO-PEO block copolymer accounts for 5wt% of the mass of PVA, and the antistatic filler is hexadecyltrimethylammonium bromide, and the antistatic filler accounts for 0.3wt% of the mass of PVA.

[0041] Step S2. injecting the spinning solution into the electrospinning device and uniformly depositing it on the receiving device to form a PVA nanofiber membrane; wherein the process parameters of the electrospinning device are a spinning voltage of 18 kV, a push injection speed of 0.5 ml / min, a distance between the needle and the receiving device of 18 cm, an operating temperature of 25° C., and a relative humidity of 50%;

[0042] Step S3. Use polypropylene (PP) needle-punched felt material as a substrate, cover the PVA nanofiber membrane on the surface of the polypropylene (PP) needle-punched felt material, and compound it through a hot pressing process. The hot pressing temperature is 90° C., the hot pressing pressure is 2 MPa, and the hot pressing time is 10 s.

[0043] Nano electrospun fiber filter material: The nano electrospun fiber filter material prepared by the above preparation method comprises a polypropylene (PP) needle-punched felt layer and a PVA nanofiber membrane, and the thickness of the PVA nanofiber membrane is 0.42 um.

[0044] Example 4

[0045] Embodiment 4 provides a nano electrospun fiber filter material and a preparation method thereof, wherein:

[0046] The preparation method of nano electrostatic spinning fiber filter material includes the following technical steps:

[0047] Step S1. Add PVA at a concentration of 12wt% to deionized water, stir in a constant temperature water bath at 85°C until completely dissolved to form a uniform and transparent polymer solution, cool to 45°C, add PEO-PPO-PEO block copolymer and antistatic filler, and ultrasonically disperse for 10-20 minutes to form a spinning solution; wherein the PEO-PPO-PEO block copolymer accounts for 4.5wt% of the mass of PVA, and the antistatic filler is hexadecyltrimethylammonium bromide, and the antistatic filler accounts for 0.2wt% of the mass of PVA.

[0048] Step S2. Injecting the spinning solution into the electrospinning device and uniformly depositing it on the receiving device to form a PVA nanofiber membrane; wherein the process parameters of the electrospinning device are a spinning voltage of 18 kV, a push injection speed of 0.8 ml / min, a distance between the needle and the receiving device of 16 cm, an operating temperature of 25° C., and a relative humidity of 50%;

[0049] Step S3. Use polypropylene (PP) needle felt material as a substrate, cover the PVA nanofiber membrane on the surface of the polypropylene (PP) needle felt material, and compound it through a hot pressing process. The hot pressing temperature is 85°C, the hot pressing pressure is 2MPa, and the hot pressing time is 15s.

[0050] Nano electrospun fiber filter material: The nano electrospun fiber filter material prepared by the above preparation method includes a polypropylene (PP) needle felt layer and a PVA nanofiber membrane. The thickness of the PVA nanofiber membrane is controlled by the spinning time of step S2, and the thickness of the PVA nanofiber membrane is 0.1um.

[0051] Examples 5 to 11

[0052] The difference between this embodiment and embodiment 4 is that the thickness of the PVA nanofiber membrane is controlled by controlling the spinning time of step S2. The thickness of the PVA nanofiber membrane is shown in Table 1 below.

[0053]

[0054] Comparative Example 1

[0055] The difference between this control example and Example 1 is that PVA with a concentration of 10 wt % is used to replace the PEO-PPO-PEO block copolymer.

[0056] Comparative Example 2

[0057] The difference between this control example and Example 1 is that the hot pressing process in step S3 is cancelled, the silica sol is sprayed on the surface of the polypropylene (PP) needle felt material, the PVA nanofiber membrane is spread flat on the surface of the polypropylene (PP) needle felt material, and the composite is extruded by a roller, then left to stand and put into an oven for drying to obtain a filter material.

[0058] Performance Testing Methods

[0059] Filtration efficiency: The test environment is set to relative humidity ≥ 85%, flow rate ≥ 5m / s, and room temperature (25°C). The airflow humidity is adjusted to the target value through the high humidity system, and a high-speed airflow containing particulate matter is provided under the action of a high-flow air generator. Before the test, the filter material needs to be placed in a high humidity environment for 30 minutes to balance and ensure that its moisture absorption reaches a stable state. Subsequently, the filter material is installed in the filtration test device to ensure that it is firmly fixed and well sealed. Start the aerosol generator to generate a standard aerosol particle airflow with a particle size distribution of 5μm. Use a particle size distribution meter to measure the particle concentration before and after passing through the filter material, and record the capture efficiency of particles of different particle sizes. The calculation formula for filtration accuracy is:

[0060] Filtration accuracy (%) = (1-C outlet (d) / C inlet (d)) × 100

[0061] Wherein, Cinlet(d) and Coutlet(d) represent the concentration of particles of a specific size in the inlet and outlet airflows, respectively.

[0062] Delamination performance test method: Under high humidity (≥85% RH) and high flow rate (≥5m / s) test environment, 20 composite filter materials prepared in each embodiment and control example were tested for delamination performance, and data of three conditions were recorded: complete separation, partial separation and no separation.

[0063] Table 1 Experimental data of Examples 1 to 11 and Comparative Examples 1 to 2

[0064]

[0065]

[0066] Note: The filtration efficiency in the table is the average value of 20 filter element composite materials.

[0067] Combining Examples 1 to 3 and Table 1, it can be seen that the filter materials of Examples 1, 2 and 3 did not completely separate or partially separate in the layered test, and all samples remained in an unseparated state, proving that their interface bonding force under harsh working conditions is strong. At the same time, the filtration efficiencies of these examples reached 94.82%, 90.52% and 93.77%, respectively, indicating that the filter material after the preparation method is optimized not only has high mechanical stability, but also can effectively capture particulate matter, meeting the high efficiency requirements of industrial filtration.

[0068] It can be seen from Examples 4 to 11 and Table 1 that as the thickness of the PVA nanofiber membrane increases, the filtration efficiency also increases. When the thickness of the PVA nanofiber membrane increases to 0.5um, the filtration efficiency gradually decreases; in the layered experimental performance test, when the thickness of the PVA nanofiber membrane is 0.3 to 0.5um, there is basically no separation between the membranes, but when the thickness of the PVA nanofiber membrane is too large or too small, there are different degrees of membrane separation. The number of changes. When the thickness of the PVA nanofiber membrane is 0.3 to 0.5um, the interfacial bonding force between the membrane and the polypropylene (PP) needle felt substrate is the strongest, and this strong bonding force plays a key role in the optimization of filtration performance. The strong bonding force ensures the stable adhesion of the fiber membrane to the substrate, so that the fiber membrane can maintain integrity and uniformity under harsh conditions of high humidity and high flow rate without stratification or detachment. The integrity of the fiber membrane directly affects the capture capacity of particulate matter and the stability of the filtration path, thereby significantly improving the filtration efficiency. The strong bonding force also reduces the risk of airflow bypass and leakage by improving the structural stability of the interface. When the bonding force is insufficient, the membrane layer may warp or separate in local areas, forming a discontinuous filtration path, causing particles to penetrate or bypass the filter material. The interface with strong bonding force can evenly distribute mechanical stress, avoiding these phenomena and ensuring the integrity and efficiency of the filtration area.

[0069] It can be seen from Example 1, Reference Example 1, Reference Example 2 and Table 1 that the PEO-PPO-PEO block copolymer and the hot pressing process have a synergistic effect on enhancing the filtration efficiency of the filter material composite membrane. The hydrophilic PEO segments are stretched and rearranged in the direction of the PVA fibers at high temperatures, forming a large number of hydrogen bonding points with the hydroxyl groups in the PVA, increasing the adhesion area and bonding force of the interface. The hydrophobic PPO segments are rearranged in the direction of the polypropylene (PP) needle felt cloth under pressure, and are tightly combined with the non-polar molecular chains of the polypropylene (PP) needle felt material through hydrophobic interactions and van der Waals forces. The rearrangement and orientation behavior of this molecular chain are locked in the cooling stage to form stable physical crosslinking points, which greatly improves the overall strength of the interface bonding. In addition, high temperature and pressure compress the thickness of the PEO-PPO-PEO in the interface layer, eliminate the common micropores in the direct bonding interface, and form a high-density molecular stacking structure. This dense interface layer shows excellent stability in high humidity environments. The PEO segment effectively alleviates the swelling effect by forming hydrogen bonds and hydration with water molecules. At the same time, the hydrophobic barrier formed by the PPO segment on the surface of the polypropylene (PP) needle-punched felt repel the intrusion of water and protect the integrity of the bonding point. In a high flow rate environment, the molecular bridge structure and dense stacking layer in the hot pressing interface can disperse the shear stress, increase the friction resistance and anti-stratification ability of the interface, and thus improve the filtration accuracy of the composite filter element.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing nano electrospun fiber filter material, characterized in that: The technical steps include: Step S1. PVA is added to deionized water at a concentration of 10wt%-15wt%, stirred in a constant temperature water bath at 80-90°C until completely dissolved to form a uniform and transparent polymer solution, cooled to 40-50°C, PEO-PPO-PEO block copolymer and antistatic filler are added, and ultrasonic dispersion is performed for 10-20 minutes to form a spinning solution; Step S2. injecting the spinning solution into the electrospinning device and uniformly depositing it on the receiving device to form a PVA nanofiber membrane; Step S3. Use the polypropylene needle felt material as a substrate, cover the PVA nanofiber membrane on the surface of the polypropylene needle felt material, and perform compounding through a hot pressing process.

2. The method for preparing the nano electrostatically spun fiber filter material according to claim 1, characterized in that: In step S1, the PEO-PPO-PEO block copolymer accounts for 4wt% to 6wt% of the mass of PVA.

3. The method for preparing the nano electrostatically spun fiber filter material according to claim 1, characterized in that: In step S1, the antistatic filler is hexadecyltrimethylammonium bromide, and the antistatic filler accounts for 0.1wt% to 0.3wt% of the mass of PVA.

4. The method for preparing the nano electrospun fiber filter material according to claim 1, characterized in that: In step S2, the process parameters of the electrospinning equipment are: spinning voltage of 15kV to 25kV, injection speed of 0.5ml / min to 1.0ml / min, distance between needle and receiving device of 15cm to 20cm, working temperature of 20℃ to 30℃ and relative humidity of 40% to 60%.

5. The method for preparing the nano electrostatically spun fiber filter material according to claim 1, characterized in that: The parameters of the hot pressing process are as follows: the hot pressing temperature is 80° C. to 100° C., the hot pressing pressure is 1 to 2 MPa, and the hot pressing time is 10 to 20 seconds.

6. Nano electrospun fiber filter material prepared by the preparation method according to claims 1 to 4.

7. The nano electrostatically spun fiber filter material according to claim 6, characterized in that: The filter material comprises a polypropylene needle-punched felt layer and a PVA nanofiber membrane, and the thickness of the PVA nanofiber membrane is 0.3 to 0.5 um.

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