Preparation method of high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure

Abstract

The application discloses a preparation method of a high-efficiency low-resistance 3D microsphere composite air filtering material with a string-bead structure, and is characterized in that the method comprises the following steps: (1) dissolving a spinning polymer and microsphere particles in a solvent to obtain a spinning liquid; (2) performing ultrasonic treatment on the spinning liquid to obtain a microsphere suspension; (3) conveying the microsphere suspension to a device composed of coaxial injectors; (4) outputting the microsphere suspension from an inner nozzle of the coaxial injectors under the drafting action of high-pressure airflow to form a continuous jet flow for spinning, and stacking the fibers to form a fiber membrane; and (3) drying. The application solves the contradiction between the filtering efficiency and the air resistance when nanofibers are used to manufacture air filtering materials, can make the gaps between the fibers more compact, quickly and effectively intercept fine particles, can improve the porosity, effectively reduce the air resistance, improve the filtering performance and the filtering efficiency, and has obvious social significance and economic value in actual industrial application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional composite filter materials, and particularly relates to a preparation method of a high-efficiency low-resistance 3D microsphere composite air filter material with a string-bead structure. BACKGROUND

[0002] Air pollution is one of the major challenges faced by mankind. In addition to gaseous pollutants, airborne fine particulate matter such as dust, smoke, and dust, etc. is very harmful to human health, among which PM2.5 can penetrate into the lungs and cause greater harm to human health. Nanofiber filter material has natural advantages in the field of air filtration materials due to its nanometer diameter, large specific surface area, and high porosity. However, generally, the finer the fiber, the smaller the pore, the smaller the particle filtered by the fiber membrane, and the higher the filtration efficiency. The high fiber packing density will also lead to high pressure drop. How to reduce the pressure drop while ensuring high filtration efficiency is a difficult problem faced by air filtration materials at present. In addition, electrostatically charged non-woven filter materials will lose their filtering efficiency due to static electricity elimination. Therefore, developing high-efficiency nanofiber air filtration materials that rely on physical interception to separate particles of various sizes is of great significance to human health.

[0003] In recent years, nanofiber filter materials have been widely used due to their small fiber diameter and large specific surface area. However, nanofiber still has the problem of dense structure. The problem can be solved by doping microspheres to form a layered structure and a multi-layer composite structure, which can achieve a low air resistance nanofiber filter. At present, the main methods for producing microsphere nanofiber are electrospinning and electrostatic spraying. In recent years, gas jet spinning has emerged as a new technology for producing fibers driven by high-speed gas instead of high voltage. Although electrospinning is more popular and widely used, it requires high voltage and safety issues need to be addressed. Moreover, its production rate, yield, and equipment operation complexity are not as good as gas jet spinning.

[0004] Although there are many types of membrane materials used for air filtration, their structures and preparation processes are different. Although the specific surface area and adsorption capacity are improved by improving the roughness of the fiber surface, the air resistance of the filtration membrane is too large due to the dense structure of the nanofiber, so the overall filtration performance and filtration efficiency are not high, and the filtration effect lacks durability in practical applications. Therefore, how to make the fiber gap more compact, quickly and effectively intercept fine particles, and at the same time improve the porosity, effectively reduce the air resistance, and improve the filtration performance and filtration efficiency, has become a difficult problem that needs to be solved by air filtration material field technicians. SUMMARY

[0005] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide a preparation method of high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure, which has a porous structure, can make the inter-fiber space more compact, quickly and effectively intercept fine particles, increase porosity, effectively reduce air resistance, and improve filtration efficiency.

[0006] To solve the above technical problems, the technical solution adopted by the present application is: a preparation method of high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure, comprising the following steps:

[0007] I. Preparation of microsphere suspension:

[0008] (1) Dissolve the spinning polymer and microsphere particles in a solvent, and completely dissolve them at room temperature for 8-12 hours through magnetic stirring to obtain a spinning solution, which is ready for use;

[0009] (2) Treat the spinning solution at 25 DEG C through ultrasonic wave for 1-2 hours to ensure that the polymer is completely dissolved and the microspheres are fully dispersed, thereby obtaining a microsphere suspension;

[0010] II. Solution jet spinning:

[0011] (3) Deliver the microsphere suspension to a device composed of a coaxial injector, wherein the microsphere suspension delivery pipe is connected to the inner nozzle of the coaxial injector, and the high-pressure gas delivery pipe is connected to the outer nozzle of the coaxial injector;

[0012] (4) Adjust the microfluidic gas jet spinning parameters, and the microsphere suspension is output from the inner nozzle of the coaxial injector under the drawing action of high-pressure gas flow to form a continuous jet for spinning, and the fibers are stacked to form a fiber membrane;

[0013] III. Drying:

[0014] (5) Dry the fiber membrane prepared in step (4) at a drying temperature of 40-80 DEG C for 3-8 minutes to obtain a 3D microsphere composite air filtration material.

[0015] The preparation method of high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure described above, wherein the spinning polymer is one or more of polyamide 6, polyamide 66, polyurethane, polyacrylonitrile, polyimide, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride or polyethylene oxide.

[0016] The preparation method of high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure described above, wherein the microspheres are one or more of silica, polystyrene, polymethyl methacrylate, and titanium dioxide.

[0017] The preparation method of the high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure, wherein the particle size of the microspheres is 0.1-15 microns, and the microspheres are hydrophilic and polydisperse.

[0018] The preparation method of the high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure, wherein the molecular weight of the spinning polymer is 50-200 thousand.

[0019] The preparation method of the high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure, wherein the solvent is one or several kinds of water solution prepared from formic acid, ethanol or N, N-dimethylformamide, and the mass fraction is 88%.

[0020] The preparation method of the high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure, wherein the mass percentage of the spinning polymer in the microsphere suspension prepared in step (2) is 5-20%, and the mass percentage of the microspheres is 1-5%.

[0021] The preparation method of the high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure, wherein in step (5), the inner diameter of the needle is 0.25-0.42 mm, the liquid propelling speed is 1-3 ml / h, the spinning gas pressure is 0.05-0.15 MPa, the distance from the spinning nozzle to the receiving curtain is 25-35 cm, the winding speed of the collector is 700-900 r / h, the ambient temperature is 28-32℃, and the ambient humidity is 35-45%.

[0022] The preparation method of the high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure, wherein in step (5), the inner diameter of the needle is 0.33 mm, the liquid propelling speed is 2 ml / h, the spinning gas pressure is 0.10 MPa, the distance from the spinning nozzle to the receiving curtain is 30 cm, the winding speed of the collector is 800 r / h, the ambient temperature is 30℃, and the ambient humidity is 40%.

[0023] The advantages of the preparation method of the high-efficiency, low-resistance 3D microsphere composite air filter material with a beaded structure of this invention are as follows: To resolve the contradiction between filtration efficiency and air resistance when manufacturing air filter materials from nanofibers, this invention uses a microsphere suspension as the spinning solution for one-step solution jet spinning, developing nanofibers with a beaded, rough, and specially structured structure to achieve high efficiency and low resistance in the air filter material. By doping with microspheres, the three-dimensional packing structure and surface roughness of the nanofiber membrane are controlled. The addition of larger-sized microspheres can support the cavity structure between fibers, increasing the gaps between fibers and making the packing structure of the nanofiber membrane more porous, thus improving the traditional dense structure of nanofiber membranes. Smaller-sized microspheres can increase the surface roughness of the fibers, thereby reducing air resistance while maintaining a relatively constant filtration efficiency, achieving a high-efficiency, low-resistance filtration effect. This invention simultaneously achieves good filtration performance and low air resistance, realizing a simultaneous improvement in filtration performance and filtration efficiency. Furthermore, solution jet spinning technology has advantages such as simple preparation process, high safety performance, low cost, and adjustable fiber diameter. Moreover, the preparation process is simple, highly controllable, and has high production efficiency, which has significant social and economic value in practical industrial applications. Attached Figure Description

[0024] Figure 1 This is a process flow diagram for preparing the 3D microsphere composite air filter material of the present invention;

[0025] Figure 2 A schematic diagram of the structure of the 3D microsphere composite air filter material of this invention;

[0026] Figure 3 This is a scanning electron microscope image of the 3D microsphere composite air filter material prepared in Example 2 of the present invention;

[0027] Figure 4 Comparison of the internal pore morphology of the fiber in the 3D microsphere composite air filter material of this invention with that of the filter material without microspheres.

[0028] Figure 5 A comparison chart of the porosity properties of the microsphere-free filter material and the air filter material prepared in Example 2;

[0029] Figure 6 A comparison of the air permeability performance of the microsphere-free filter material and the air filter material prepared in Example 2;

[0030] Figure 7 A comparison chart of the filtration efficiency of the microsphere-free filter material and the air filter material prepared in Example 2; Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] In the present application, the orientation words such as "upper" and "lower" are generally used to refer to the upper and lower positions of the device in the actual use or working state, and specifically refer to the orientation of the drawing surface in the drawings, unless otherwise specified. In addition, in the description of the present application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are only used as labels and do not impose numerical requirements or establish an order. The term "a plurality of" means "two or more".

[0033] As shown in the figure, a method for preparing a high-efficiency low-resistance 3D microsphere composite air filtration material with a string of beads structure, comprising the following steps: Figure 1

[0034] I. Preparation of microsphere suspension

[0035] (1) Dissolve the spinning polymer and microsphere particles in the solvent, and completely dissolve at room temperature under magnetic stirring for 8-12 h to obtain a spinning solution, which is ready for use;

[0036] (2) The spinning solution is treated by ultrasonic wave at 25°C for 1-2 h to ensure that the polymer is completely dissolved and the microspheres are fully dispersed, and a microsphere suspension is obtained;

[0037] II. Solution jet spinning

[0038] (3) The microsphere suspension is delivered to a device composed of a coaxial syringe, the microsphere suspension delivery tube is connected to the inner nozzle of the coaxial syringe, and the high-pressure gas delivery tube is connected to the outer nozzle of the coaxial syringe;

[0039] (4) Adjust the microfluidic gas jet spinning parameters, the microsphere suspension is output from the inner nozzle of the coaxial syringe under the stretching action of high-pressure gas flow to form a continuous jet for spinning, and the fibers are stacked to form a fiber membrane;

[0040] III. Drying

[0041] (5) The fiber membrane prepared in step (4) is dried at a temperature of 40-80°C for 3-8 min to obtain a 3D microsphere composite air filtration material.

[0042] ​The spinning polymer is one or more of polyamide 6, polyamide 66, polyurethane, polyacrylonitrile, polyimide, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride or polyethylene oxide. The molecular weight of the spinning polymer is 50000-200000. The solvent is one or more of formic acid, ethanol or N,N-dimethylformamide prepared into an aqueous solution with a mass fraction of 88%. The microspheres are one or more of silica, polystyrene, polymethyl methacrylate or titanium dioxide. The particle size of the microspheres is 0.1-15 microns, and the microspheres used are hydrophilic and polydisperse. In the microsphere suspension, the mass percentage of the spinning polymer is 5-20%, and the mass percentage of the microspheres is 1-5%. The inner diameter of the needle is 0.25-0.42 mm, the liquid propelling speed is 1-3 ml / h, the spinning gas pressure is 0.05-0.15 MPa, the distance from the spinneret to the receiving curtain is 25-35 cm, the winding speed of the collector is 700-900 r / h, and the ambient temperature is 28-32℃, and the ambient humidity is 35-45%.

[0043] The application will be specifically described below through specific examples. The following examples are only part of the examples of the application, and are not a limitation of the application.

[0044] Example 1

[0045] The preparation method of the high-efficiency low-resistance nanofiber microsphere composite film comprises the following steps:

[0046] (1) Dissolve polyurethane, polyvinylidene fluoride and polystyrene microsphere powder in an ethanol aqueous solution with a mass fraction of 88% to obtain a spinning solution, and treat the spinning solution at 25℃ through ultrasonic waves for 1-2 h to ensure that the polymer is completely dissolved and the microspheres are fully dispersed, thereby obtaining a microsphere suspension;

[0047] The mass percentage of the polyurethane in the spinning solution is 4.75%.

[0048] The mass percentage of the polyvinylidene fluoride is 0.25%.

[0049] The mass percentage of the polystyrene microspheres is 1%, and the particle size is 0.1 microns.

[0050] (2) Deliver the microsphere suspension to a device composed of a coaxial syringe, connect the infusion tube of the microsphere suspension to the inner nozzle of the coaxial syringe, and connect the high-pressure gas delivery tube to the outer nozzle of the coaxial syringe;

[0051] (3) Adjust the microfluidic gas jet spinning parameters, and the microsphere suspension is output from the inner nozzle of the coaxial syringe to form a continuous jet under the stretching action of the high-pressure gas flow for spinning, and the fibers are stacked to form a fiber film.

[0052] The spinning parameters are as follows: the inner diameter of the needle used is 0.25 mm, the liquid propulsion speed is 1 ml / h, the spinning gas pressure is 0.05 MPa, the distance from the spinneret to the receiving curtain is 25 cm, the collector winding speed is 700 r / h, the ambient temperature is 28 DEG C, and the ambient humidity is 35%.

[0053] (4) After spinning, the microsphere fiber composite wet film is dried in a 40 DEG C oven for 3 min, and the fiber composite film of the application is obtained.

[0054] Example 2

[0055] The preparation method of the high-efficiency low-resistance nanofiber microsphere composite film comprises the following steps:

[0056] (1) Dissolve polyamide 6, polyethylene oxide and silica microsphere particles in a mass fraction of 88% formic acid aqueous solution to obtain a spinning solution, and treat the spinning solution at 25 DEG C for 1-2 h by ultrasonic wave treatment to ensure that the polymer is completely dissolved and the microspheres are fully dispersed, thereby obtaining a microsphere suspension;

[0057] The mass percentage of polyamide 6 in the spinning solution is 7.8%;

[0058] The mass percentage of polyethylene oxide is 0.2%;

[0059] The mass percentage of silica microspheres is 1.5%, and the particle size is 10 μm.

[0060] (2) The microsphere suspension is transported to a device composed of a coaxial syringe, the infusion tube of the microsphere suspension is connected with the inner nozzle of the coaxial syringe, and the high-pressure gas conveying pipe is connected with the outer nozzle of the coaxial syringe;

[0061] (3) Adjust the microfluidic gas jet spinning parameters, the microsphere suspension is output from the inner nozzle of the coaxial syringe under the stretching action of the high-pressure gas flow to form a continuous jet for spinning, and the fibers are stacked to form a fiber film;

[0062] The spinning parameters are as follows: the inner diameter of the needle used is 0.33 mm, the liquid propulsion speed is 2 ml / h, the spinning gas pressure is 0.10 MPa, the distance from the spinneret to the receiving curtain is 30 cm, the collector winding speed is 800 r / h, the ambient temperature is 30 DEG C, and the ambient humidity is 40%.

[0063] (4) After spinning, the microsphere fiber composite wet film is dried in a 60 DEG C oven for 5 min, and the fiber composite film of the application is obtained.

[0064] Example 3

[0065] The preparation method of the high-efficiency low-resistance nanofiber microsphere composite film comprises the following steps:

[0066] (1) polyacrylonitrile, polyvinyl chloride and titanium dioxide microspheres powder are dissolved in an N, N-dimethylformamide solution with a mass fraction of 88% to obtain a spinning solution, the spinning solution is treated by ultrasonic wave at 25 DEG C for 1-2h to ensure that the polymer is completely dissolved and the microspheres are fully dispersed, thereby obtaining a microsphere suspension;

[0067] The mass percentage of the polyacrylonitrile in the spinning solution is 19.75%;

[0068] The mass percentage of the polyvinyl chloride is 0.25%;

[0069] The mass percentage of the titanium dioxide microspheres is 5%, and the particle size is 15 μm.

[0070] (2) the microsphere suspension is delivered to a device composed of a coaxial injector, the delivery pipe of the microsphere suspension is connected with the inner nozzle of the coaxial injector, and the high-pressure gas delivery pipe is connected with the outer nozzle of the coaxial injector;

[0071] (3) the microfluidic gas jet spinning parameters are adjusted, the microsphere suspension is output from the inner nozzle of the coaxial injector, and a continuous jet is formed under the drawing action of the high-pressure gas flow to perform spinning, and the fibers are stacked to form a fiber membrane;

[0072] The spinning parameters are as follows: the inner diameter of the needle used is 0.42 mm, the liquid propelling speed is 3 ml / h, the spinning gas pressure is 0.15 MPa, the distance from the spinneret to the receiving curtain is 35 cm, the winding speed of the collector is 900 r / h, the environmental temperature is 32 DEG C, and the environmental humidity is 45%.

[0073] (4) after spinning, the microsphere fiber composite wet membrane is dried in an oven at 80 DEG C for 8 min, thereby obtaining the fiber composite membrane of the application.

[0074] The performance test results of the high-efficiency low-resistance 3D microsphere composite air filtration material with string bead structure prepared in Example 2 of the application are as follows:

[0075] As Figures 2-4As shown, the present application can be prepared by formulating a microsphere suspension, and performing a one-step solution jet spinning process. During the spinning process, the microspheres and fibers are intertwined and connected to form a structure similar to "beads". This fiber and microsphere stacking structure not only more effectively intercepts and fixes particles, but also changes the flow path of the gas in the gap, increases the tortuosity of the airflow through the nanofiber membrane, and increases the time for particles to pass through the fiber membrane, thereby enhancing the interception and collision effect and improving the filtration efficiency. The presence of a large number of microspheres in the nanofiber membrane can increase the longitudinal spacing between adjacent nanofibers, making the three-dimensional network structure of the nanofiber membrane more fluffy, thereby reducing the packing density, reducing the filtration resistance, and having higher porosity, higher air and moisture permeability, and good filtration performance. In addition, the addition of microspheres also occupies a certain fiber gap (2D), reducing the transverse gap between fibers, which is also beneficial to improve the filtration efficiency. Moreover, through the combined action of the solution jet spinning airflow and the spinning solution, the microspheres are coated in the fibers, and the combination with the fibers is more firm, increasing the durability of the filtration.

[0076] As shown in Figure 5 , the pore size refers to the size of the pores in the nanofiber membrane, which directly affects the filtration precision and air resistance of the membrane. The addition of microspheres in traditional nanofiber membranes can expand the gap between fibers and fibers, expand the pore structure of the nanofiber membrane, and increase the pore size. The porosity is a key factor affecting the filtration pressure drop. After adding microspheres to the nanofiber membrane, the porosity increases from 50.9% to 88.3%, so the porosity of the nanofiber membrane can be adjusted by adding microspheres. The larger the porosity, the smaller the packing density of the nanofibers, which is more conducive to high-efficiency and low-resistance air filtration.

[0077] As shown in Figure 6 , the air permeability of the fiber membrane refers to the ability of air or gas to pass through the membrane. The air permeability of the fiber membrane depends on factors such as the material, structure, and preparation method of the membrane. In general, a fiber membrane with good air permeability can allow air or gas to pass freely, thereby achieving the functions of air permeability, ventilation, and moisture removal. Proper air permeability can improve comfort, reduce discomfort caused by moisture and air impermeability, and also help keep the skin dry and comfortable. To evaluate the air permeability of the fiber membrane, the air permeability index such as air permeability can be measured. As can be seen from the observation figure, the air permeability of the nanofiber membrane increases from 71.6 m / s to 118.3 cm / s with the addition of microspheres. This is because the addition of microspheres can expand the gap between fibers and fibers, increase the porosity, and make the three-dimensional stacking structure of the nanofiber membrane more fluffy. Therefore, with the addition of microspheres, the air permeability of the nanofiber membrane also increases.

[0078] As shown in Figure 7As shown, according to the classical filtration theory, there are five main mechanisms of filtration of nanofiber materials, including interception effect, inertial effect, electrostatic adsorption effect, gravity effect and diffusion effect. The nanofiber filtration material has a high specific surface area and a reasonable pore structure distribution, has a direct interception effect, and can obtain a high filtration efficiency without a polyelectrolyte. As can be seen from the figure, with the successful incorporation of microspheres, the filtration efficiency of the nanofiber membrane increases from 97.35% to 98.84%, and the pressure drop decreases from 162 Pa to 126 Pa; on the one hand, the incorporation of microspheres can increase the longitudinal spacing between fibers, making the fiber membrane more fluffy, thereby reducing the filtration pressure drop of the fiber membrane, on the other hand, from the two-dimensional structure, the incorporation of microspheres reduces the horizontal spacing of the fiber plane, and the filtration efficiency is improved.

[0079] In summary, the present application adopts a solution jet spinning method, compared with the electrospinning process, this process is simple and fast, without high voltage, low energy consumption, and fast efficiency, high yield, safe and simple equipment operation. And the nanofiber microsphere composite membrane prepared by adjusting the fiber membrane stacking structure by microspheres achieves the purpose of high-efficiency and low-resistance filtration, according to the required filtration occasion, requirements, the thickness of the composite material can be flexibly adjusted (adjusting the spinning time, the rotation speed of the roller collector, the liquid propulsion speed, the spinning gas pressure, the receiving distance, etc.), the microsphere addition amount, to realize different filtration performance and filtration efficiency. Large-area microsphere nanofiber membrane preparation can be realized, and the production process is simple and fast; compared with the electrospinning and electrostatic spraying process, the present application does not require high voltage, low energy consumption, and fast production rate, high yield, safe and simple equipment operation.

[0080] Of course, the above description is not a limitation of the present application, and the present application is not limited to the above examples, and ordinary skilled in the art, within the scope of the present application, changes, modifications, additions or replacements made, should belong to the protection scope of the present application.

Claims

1. A method for preparing high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure, characterized in that, It comprises the following steps: I. Preparation of microsphere suspension: (1) Dissolve the spinning polymer and microsphere particles in a solvent, and completely dissolve them at room temperature for 8-12 hours under magnetic stirring to obtain a spinning solution, which is ready for use; (2) The spinning solution is treated by ultrasonic wave at 25℃ for 1-2 hours to ensure that the polymer is completely dissolved and the microspheres are fully dispersed, thereby obtaining a microsphere suspension; II. Solution jet spinning: (3) The microsphere suspension is delivered to a device composed of a coaxial injector, the delivery tube of the microsphere suspension is connected to the inner nozzle of the coaxial injector, and the high-pressure gas delivery tube is connected to the outer nozzle of the coaxial injector; (4) Adjust the microfluidic gas jet spinning parameters, the microsphere suspension is output from the inner nozzle of the coaxial injector under the drawing action of high-pressure gas flow to form a continuous jet for spinning, and the fibers are stacked to form a fiber membrane; III. Drying: (5) The fiber membrane prepared in step (4) is dried at a temperature of 40-80℃ for 3-8 minutes to obtain a 3D microsphere composite air filtration material.

2. The preparation method of the high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure according to claim 1, characterized in that: The spinning polymer is one or more of polyamide 6, polyamide 66, polyurethane, polyacrylonitrile, polyimide, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride or polyethylene oxide.

3. The method for preparing high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure according to claim 1, characterized in that: The microspheres are one or more of silica, polystyrene, polymethyl methacrylate, and titanium dioxide.

4. The method for preparing high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure according to claim 1, characterized in that: The particle size of the microspheres is 0.1-15μm, and the microspheres used are hydrophilic and polydisperse.

5. The method for preparing high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure according to claim 1, characterized in that: The molecular weight of the spinning polymer is 50-200 thousand.

6. The method for preparing high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure according to claim 1, characterized in that: The solvent is one or more of formic acid, ethanol or N,N-dimethylformamide prepared into an aqueous solution with a mass fraction of 88%.

7. The method for preparing high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure according to claim 1, characterized in that: In the microsphere suspension prepared in step (2), the mass percentage of the spinning polymer is 5-20%, and the mass percentage of the microspheres is 1-5%.

8. The method for preparing high efficiency low resistance 3D microsphere composite air filtration material with string-bead structure according to claim 1, characterized in that: In step (4), the inner diameter of the needle is 0.25-0.42mm, the liquid propelling speed is 1-3ml / h, the spinning gas pressure is 0.05-0.15MPa, the distance from the spinneret to the receiving curtain is 25-35cm, the collector winding speed is 700-900r / h, the environmental temperature is 28-32℃, and the environmental humidity is 35-45%.

9. The method for preparing high-efficiency low-resistance 3D microsphere composite air filtration material with string-bead structure according to claim 8, characterized in that: In step (4), the inner diameter of the needle is 0.33mm, the liquid propelling speed is 2ml / h, the spinning gas pressure is 0.10MPa, the distance from the spinneret to the receiving curtain is 30cm, the collector winding speed is 800r / h, the environmental temperature is 30℃, and the environmental humidity is 40%.

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