PA6 / PEO (Polyamide 6 / Polyethylene Oxide) micro-nanofiber air filtering membrane with bent form and preparation method thereof

Abstract

The invention discloses a preparation method of a PA6 / PEO micro-nanofiber air filtering membrane with a bent form, which comprises the following steps: (1) weighing PA6 particles and PEO powder with a certain mass, and dissolving in a formic acid solution with the mass fraction of 88% to obtain a mixed solution; (2) stirring the mixed solution to obtain a PA6 / PEO spinning solution; (3) forming a fiber membrane under a room-temperature dry condition through a gas jet spinning machine; (4) drying overnight at 60 DEG C to remove the residual solvent; (5) performing heat treatment in a drying oven, and (6) at normal temperature, placing the fiber membrane subjected to heat treatment in a container, and adding deionized water to immerse the fiber membrane; (7) heating the container in a water bath, and repeating the water bath treatment twice; and (8) immediately taking out the sample after the reaction is finished, and performing vacuum drying treatment. According to the invention, oily and salty ultrafine particles can be efficiently filtered at the same time, and the technical problem that effective filtration of fine oily and salty particles is difficult to realize in the prior art is solved by optimizing the structural characteristics of the fiber membrane.

Description

Technical Field

[0001] The invention belongs to the technical field of functional fiber filter materials, and in particular relates to a PA6 / PEO micro-nano fiber air filter membrane with a curved shape and a preparation method thereof. Background Art

[0002] Nowadays, with the rapid development of industrialization and urbanization, as well as environmental problems caused by climate change and pollution caused by human activities, air quality has become one of the most concerned issues today. Fine particulate matter (PM2.5), viruses, bacteria and other harmful substances in the air pose a serious threat to human health and the ecological environment. According to data released by the World Health Organization (WHO), more than 7 million people die prematurely each year due to air pollution worldwide, and in Chinese cities, the average annual concentration has exceeded the national limit in most cases in recent years. Therefore, air quality issues have become the focus of global attention, and the development of high-efficiency and low-resistance air filtration materials is particularly important.

[0003] Existing filtration technologies mainly include nanofiber filtration technology and electrostatic filtration technology. The nanofiber membrane, with its fine fiber structure, not only provides higher particle interception efficiency than traditional mechanical filtration, but also achieves lower filtration resistance and energy consumption due to the high porosity between fibers. Compared with electrostatic filtration technology, nanofiber materials have stronger chemical and physical stability and are less sensitive to humidity and temperature changes, thereby extending their service life and reducing maintenance costs. The current patented technologies of nanofiber membranes related to air filtration and purification are as follows:

[0004] CN114452719A discloses a method for preparing an electrostatically spun nanofiber membrane for air filtration, belonging to the technical field of fiber membrane preparation. The method for preparing an electrostatically spun nanofiber membrane for air filtration in situ loads silicon dioxide nanoparticles on the surface of modified polyacrylonitrile nanofibers by a sol-gel method, and then modifies the surface by 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane to make it have hydrophobic and oleophobic properties. Compared with the reported self-cleaning filter membrane, the preparation method of this patent has lower equipment requirements, and good filtering performance, self-cleaning performance, flexibility and corrosion resistance can be obtained on the basis of low cost. It is suitable for the field of air filtration and purification in complex environments, and has the advantages of effective filtration, easy self-cleaning, corrosion resistance, low cost and simplicity and practicality.

[0005] CN 119261345A discloses a high-efficiency, low-resistance electrospun multilayer filter material for a mask filter element and a preparation method thereof. The method comprises the following steps: first, dissolving ODA and PMDA raw materials in a solvent to prepare a first PAA solution; then, using electrostatic spinning technology to make the solution into a first beaded PAA nanofiber membrane. Then, the ZIF-8 raw material is dissolved in, mixed with ODA and PMDA to form a second PAA / ZIF-8 solution, and the second PAA / ZIF-8 nanofiber layer is superimposed on the first layer by electrostatic spinning technology, and after thermal imidization treatment, a multilayer filter material having a ZIF-8 modified PI / beaded PI / ZIF-8 modified PI structure is successfully prepared. The preparation process of the present invention is simplified and efficient, and the prepared beaded multilayer filter material not only has excellent filtration efficiency and low resistance characteristics, but also shows great application potential in the field of air purification.

[0006] CN105536352A discloses a high-efficiency, low-resistance, staggered nanofiber composite material and a preparation method thereof. The high-efficiency, low-resistance nanofiber composite material is a staggered arrangement structure of fibers with nanoporous surfaces and nanofibers. The composite material has an air filtration efficiency of more than 99.99% for sodium chloride aerosol particles with a weight median diameter of 260nm, and a filtration resistance of less than 140Pa. The preparation method is as follows: in the electrostatic spinning process, a fully automatic transverse roller receiving device is used to interlace nanofibers of about 100 to 300nm with 1.2 to 1.8μm nanoporous fibers on the surface to prepare a composite nanofiber filter material with high filtration efficiency and low resistance in one step. The preparation method is simple, high in yield, and low in cost. The prepared staggered composite filter material has high filtration efficiency and low filtration resistance for fine particles, and has broad application prospects in the fields of personal protection and air purification.

[0007] It can be seen from the above patented technology that the current filtration technology for atmospheric particulate matter is mainly concentrated on the nanofiber membrane prepared by electrospinning technology. It changes the arrangement orientation of nanofibers in the fiber membrane and adds other components to form a beaded structure on the fiber to increase the high porosity between fibers, reduce the pore size and increase the roughness to improve the filtration and interception effect and efficiency, thereby achieving the purpose of high efficiency, low resistance and excellent filtration efficiency. However, there are still some defects.

[0008] The composition of atmospheric particulate matter mainly includes inorganic components, organic components and water-soluble components. Inorganic components mainly include oxides of elements such as silicon, aluminum, calcium, phosphorus, potassium, and some trace and trace metal elements such as mercury, lead, cadmium, etc. Organic components include aliphatic hydrocarbons, aromatic hydrocarbons, polycyclic aromatic hydrocarbons, etc., some of which are carcinogenic to humans12. In addition, water-soluble components mainly include sulfates, nitrates, chlorides, etc. It can be seen that the types of atmospheric particulate matter, complex chemical composition and different particle sizes have brought great challenges to adsorption and filtration materials. In particular, oily particles produced by oil smoke, oil mist, asphalt smoke, coke oven smoke and diesel engine exhaust in the air, as well as salt particles such as sulfates, nitrates and ammonium salts, are particularly harmful to the human body due to their small size, high concentration and complex chemical composition. Moreover, the chemical action of oily particles is mainly manifested as hydrophobic action and affinity between molecules. At the same time, they have no specific shape structure. Oily particles usually have strong adhesion. After being intercepted and retained inside the fiber membrane, they are easy to form an oil film. After a long period of aggregation, they block the nanofiber membrane and affect its filtration effect. Although the beaded structure further reduces the pore size and porosity, it aggravates the clogging problem for oily particles. Salt particles usually have higher surface tension and polarity, and more obvious crystal structure. After entering the fiber membrane and contacting the fiber, they cannot be confined in the pores. Even in nanofiber membranes with high porosity, low pore size and high roughness, it is not easy to achieve better barrier and interception effects for these salty particles.

[0009] It can be seen that the membrane materials currently on the market cannot efficiently filter both oily and salty particles at the same time. Therefore, how to optimize the structural characteristics of the membrane while ensuring the filtration efficiency, so that the fiber membrane material can effectively filter both fine oily and salty particles at the same time, and take into account the high filtration efficiency and good air permeability, and extend the service life, has become a difficult problem that technicians in the field of functional fiber filtration materials need to solve urgently. Summary of the invention

[0010] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a PA6 / PEO micro-nano fiber air filtration membrane with a curved shape and a preparation method thereof, which enables the fiber membrane material to effectively filter both fine oily and saline particles and has both high filtration efficiency and good air permeability.

[0011] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a PA6 / PEO micro-nano fiber air filter membrane with a curved shape, characterized in that it comprises the following steps:

[0012] 1. Preparation of spinning solution:

[0013] (1) Weigh a certain mass of PA6 particles and PEO powder, dissolve them in a formic acid solution with a mass fraction of 88% to obtain a mixed solution;

[0014] (2) The mixed solution is magnetically stirred at room temperature for 6-8 hours until it is completely dissolved to obtain a uniform PA6 / PEO spinning solution;

[0015] 2. Preparation of fiber membrane:

[0016] (3) The PA6 / PEO spinning solution prepared in step (2) was extracted with a 10 ml syringe and installed on a gas jet spinning machine;

[0017] (4) Adjust the output air pressure of the air compressor, connect the spinning needle with the airflow nozzle, and under certain propulsion speed and receiving distance conditions, the PA6 / PEO spinning solution is extruded through the needle and mixed with the high-pressure airflow, and then sprayed onto the rolling receiving roller after being stretched and refined, and a fiber membrane is formed under room temperature drying conditions;

[0018] (5) Drying the prepared fiber membrane at 60°C overnight to remove residual solvent;

[0019] 3. Heat treatment and deionized water etching treatment:

[0020] (6) placing the fiber membrane obtained in step (5) into an oven for heat treatment, setting the heating temperature to 100-120° C. and the heating time to 0.3-0.6 h. After the heating is completed, immediately taking out the fiber membrane and naturally cooling it to room temperature;

[0021] (7) At room temperature, place the heat-treated fiber membrane in a container, add deionized water to immerse the fiber membrane, the mass ratio of the fiber membrane to the deionized water is 1:40-1:60, and then add PEG200 to the water until the concentration of PEG200 reaches 1% for later use;

[0022] (8) Place the container in a water bath at 60-80°C, heat the container in a water bath, set the water bath time to 0.8-1.2h, and repeat the water bath treatment twice;

[0023] (9) After the reaction, the sample was taken out immediately and vacuum dried at 60°C for 2 h to ensure that the sample was completely dry and did not deform, thereby obtaining a PA6 / PEO micro-nano fiber air filtration membrane with a curved shape.

[0024] In the method for preparing the PA6 / PEO micro-nano fiber air filtration membrane with a curved morphology, in the step (1), the molecular weight of the PEO powder is 100,000-1,000,000.

[0025] In the method for preparing the PA6 / PEO micro-nano fiber air filter membrane with a curved morphology, in the PA6 / PEO spinning solution prepared in step (2), the concentration of PA6 is 5-7%, and the concentration of PEO is 0.5-1.5%.

[0026] In the above-mentioned method for preparing the PA6 / PEO micro-nano fiber air filtration membrane with a curved morphology, in the step (4), the air compressor output pressure is 0.04-0.08MPa, the propulsion speed is 1.5-2.5ml / h, the receiving distance is 28-32cm, and the inner diameter of the spinning needle is 0.33mm.

[0027] In the above-mentioned method for preparing the PA6 / PEO micro-nano fiber air filtration membrane with a curved morphology, in the step (6), the heat treatment heating temperature is 110° C., and the heating time is set to 0.5 h.

[0028] In the above-mentioned method for preparing the PA6 / PEO micro-nano fiber air filtration membrane with a curved morphology, in the step (7), the mass ratio of the fiber membrane to deionized water is 1:50.

[0029] In the above-mentioned method for preparing the PA6 / PEO micro-nano fiber air filtration membrane with a curved morphology, in the step (8), the water bath temperature is set to 70° C. and the water bath time is 1 hour.

[0030] In the above-mentioned method for preparing the PA6 / PEO micro-nano fiber air filter membrane with a curved morphology, in the step (4), the air compressor output pressure is 0.06MPa, the propulsion speed is 2ml / h, and the receiving distance is 30cm.

[0031] A PA6 / PEO micro-nano fiber air filtration membrane with a curved shape is prepared by the above-mentioned preparation method.

[0032] The PA6 / PEO micro-nano fiber air filter membrane with a curved morphology has an average fiber diameter of 212-4110 nm and a porosity of 69.02%-93.09%.

[0033] The advantages of the PA6 / PEO micro-nano fiber air filtration membrane with a curved morphology and the preparation method thereof of the present invention are: due to the hydrophilicity of PEO and the fact that formic acid is a volatile acid, the concentration at the gas-liquid interface is low, thereby attracting more PEO to aggregate. At the same time, this also makes the solution completely dissolved into the spinning solution. Although it is homogeneous as a whole, the solute therein is not evenly distributed in a completely sense in some places. Therefore, in the heat treatment stage, since PEO is unevenly distributed on the surface of the micro-nano fiber, the fiber obtains a highly curved surface morphology after heating; at the same time, in the water bath treatment stage, the heated and dissolved PEO is more likely to gather together, and its own water-soluble characteristics make it possible to remove most of the PEO on the surface after multiple water bath treatments, so that the fiber obtains a rough surface morphology. It is through this method that the structural characteristics of the fiber membrane (fiber curvature and fiber surface roughness) are optimized, and the capture capacity of oily and saline ultrafine particles is significantly improved. The technical problem that the micro-nano fiber membrane of the prior art is difficult to take into account the effective filtration of fine oily and saline particles is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a product picture of the PA6 / PEO micro-nano fiber air filtration membrane with a curved shape of the present invention;

[0035] Figure 2 This is a SEM image of the air filtration membrane prepared by adding medium molecular weight PEO in Example 2;

[0036] Figure 3 This is a diameter distribution diagram of the fibers in the air filtration membrane prepared by adding medium molecular weight PEO in Example 2;

[0037] Figure 4 This is a comparison diagram of the fiber morphology and diameter distribution of the air filter membrane with low molecular weight PEO added before and after heat treatment and deionized water etching treatment under the preparation conditions of Example 2;

[0038] Figure 5 This is a comparison diagram of the fiber morphology and diameter distribution of the air filter membrane with medium molecular weight PEO added before and after heat treatment and deionized water etching treatment under the preparation conditions of Example 2;

[0039] Figure 6 This is a comparison diagram of the fiber morphology and diameter distribution of the air filter membrane with high molecular weight PEO added before and after heat treatment and deionized water etching treatment under the preparation conditions of Example 2;

[0040] Figure 7 The multiple light scattering diagrams of the solute dissolution process in the spinning solution of PEO with different molecular weights;

[0041] Figure 8 The multiple light scattering diagrams after the solutes in the spinning solutions with different molecular weights are completely dissolved;

[0042] Fig. 9 This is a schematic diagram of the fiber morphology change of the air filtration membrane of the present invention after heat treatment and deionized water etching treatment;

[0043] Fig.10 Comparison and schematic diagram of fiber morphology changes before and after heat treatment and deionized water etching in air filtration membrane;

[0044] Fig.11 The pore size distribution diagram of the fiber membrane after mixed spinning of 1% PEO and 6% PA6 with different molecular weights;

[0045] Fig.12 This is the infrared spectrum of the fiber membrane before and after treatment under the preparation conditions of Example 2;

[0046] Fig.13 This is a test graph of the porosity of air filtration membranes with PEO of different molecular weights added under the preparation conditions of Example 2;

[0047] Fig.14 This is a high-magnification SEM image of the fibers in the air filtration membrane prepared in Example 2 of the present invention;

[0048] Fig.15 This is a schematic diagram of using the ImageJ tool to characterize the proportion of pores on the fiber membrane surface;

[0049] Fig.16 It is a schematic diagram of the interception process of fine oily and saline particles filtered by the air filter membrane of the present invention;

[0050] Fig.17 This is a test chart of the filtration efficiency of the air filter membrane for oily and saline particles before and after treatment. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] A method for preparing a PA6 / PEO micro-nano fiber air filter membrane with a curved morphology comprises the following steps:

[0053] 1. Preparation of spinning solution:

[0054] (1) Weigh a certain mass of PA6 particles and PEO powder, dissolve them in a formic acid solution with a mass fraction of 88% to obtain a mixed solution;

[0055] (2) The mixed solution is magnetically stirred at room temperature for 6-8 hours until it is completely dissolved to obtain a uniform PA6 / PEO spinning solution;

[0056] 2. Preparation of fiber membrane:

[0057] (3) The PA6 / PEO spinning solution prepared in step (2) was extracted with a 10 ml syringe and installed on a gas jet spinning machine;

[0058] (4) Adjust the output air pressure of the air compressor, connect the spinning needle with the airflow nozzle, and under certain propulsion speed and receiving distance conditions, the PA6 / PEO spinning solution is extruded through the needle and mixed with the high-pressure airflow, and then sprayed onto the rolling receiving roller after being stretched and refined, and a fiber membrane is formed under room temperature drying conditions;

[0059] (5) Drying the prepared fiber membrane at 60°C overnight to remove residual solvent;

[0060] 3. Heat treatment and deionized water etching treatment:

[0061] (6) placing the fiber membrane obtained in step (5) into an oven for heat treatment, setting the heating temperature to 100-120° C. and the heating time to 0.3-0.6 h. After the heating is completed, immediately taking out the fiber membrane and naturally cooling it to room temperature;

[0062] (7) At room temperature, place the heat-treated fiber membrane in a container, add deionized water to immerse the fiber membrane, the mass ratio of the fiber membrane to the deionized water is 1:40-1:60, and then add PEG200 to the water until the concentration of PEG200 reaches 1% for later use;

[0063] (8) Place the container in a water bath at 60-80°C, heat the container in a water bath, set the water bath time to 0.8-1.2h, and repeat the water bath treatment twice;

[0064] (9) After the reaction, the sample was taken out immediately and vacuum dried at 60°C for 2 h to ensure that the sample was completely dry and did not deform, thereby obtaining a PA6 / PEO micro-nano fiber air filtration membrane with a curved shape.

[0065] The materials and equipment used in the product of the present invention are as follows: polycaprolactam (PA6, general grade, granules, dielectric constant 0.65, Shanghai McLean Biochemical Technology Co., Ltd., CAS: 25038-54-4), which is selected based on its good fiber-forming property and mechanical properties; polyethylene oxide (PEO, Mv~600000, Mv~100000, Mv~1000000, powder, Shanghai McLean Biochemical Technology Co., Ltd., CAS: 68441-17-8), because its different molecular weights have a significant effect on the morphology and porosity of the fiber membrane; and formic acid (analytical pure AR88%, Shanghai Aladdin Biochemical Technology Co., Ltd., CAS: 64-18-6), which is used to dissolve PA6 and PEO because it has good solubility for the two materials. The air compressor uses a silent oil-free air compressor (Zhejiang Shengyuan Air Compressor Manufacturing Co., Ltd.) to provide air pressure, and the spinning machine uses a JNS-SBS-01 microfluidic nano gas jet spinning machine (Janus New Materials Co., Ltd.) to control the ejection flow of the spinning solution.

[0066] like Figure 1 As shown, Figure 1 (a) is a physical picture of the prepared single-layer filter membrane of the PA6 / PEO micro-nano fiber air filter membrane with a curved morphology, Figure 1 (b) is a real picture of a multi-layer filtration membrane. Depending on the actual filtration application product, application environment or filtration requirements, the thickness of the membrane can be produced or stacked according to actual needs.

[0067] Compared with the preparation of micro-nano fiber membrane by traditional electrospinning process, the present invention adopts air-jet spinning process, and uses high-speed airflow to stretch and solidify polymer liquid fiber to form continuous fiber membrane. Since electrospinning is a process in which the spinning solution is stretched at high speed, the solvent is volatilized and solidified under the action of electric field force, and finally deposited on the receiving plate to form polymer fiber, the electric field force is unstable in the process from the needle to the receiving roller, which causes the functional additive added in the spinning solution to be easily unevenly distributed during the fiber formation process. The present invention adopts air-jet spinning process to ensure the uniformity of polymer PEO in the fiber, improve the quality of the fiber, and provide guarantee for subsequent heat treatment and water bath treatment. Most of the micro-nano fiber membrane materials prepared by electrospinning technology in the prior art are difficult to form a highly curved structure with porous surface that is conducive to filtration due to the characteristics of the spinning solution itself, traction force and receiving roller configuration, so it is difficult to ensure the efficient filtration of two kinds of particulate matter. In addition, electrospinning technology has a small output, slow production speed, and requires high-quality raw materials as spinning liquid, a high-voltage electric field, and relatively high costs. Air-jet spinning does not require a high-voltage electric field, but only requires accurate control of airflow and temperature to achieve stable production. The equipment cost is relatively low, and it can achieve the industrialization goals of high output, continuous production, and open production.

[0068] Regarding the use of additives in the spinning solution, PEG200 increases the viscosity of the solution, helps buffer the contact between PEO particles and water, prevents local dissolution from forming lumps too quickly, and promotes more uniform dissolution. Both PEG200 and PEO are polyether materials. PEG200 can be used as a co-solvent to increase the solubility of PEO and promote its dissolution process in water. At the same time, PEG200 can reduce the surface tension of water, promote the wetting of PEO particles, and thus accelerate dissolution. PEG200 can accelerate the unzipping process of PEO through interaction with the PEO molecular chain, thereby increasing the dissolution rate.

[0069] Regarding the range of process parameters and bath ratio, the reason for selecting 0.06MPa is that too high air pressure can easily lead to instability of the spinning solution jet, which makes it difficult to collect micro-nano fibers. Too low air pressure can easily lead to incomplete evaporation of the solvent in the spinning solution and weak stretching effect of the airflow. The reason for selecting the propulsion pump propulsion speed of 2ml / h is that too high propulsion speed will cause incomplete evaporation of the solvent in the spinning solution. Selecting the largest possible propulsion speed can ensure that a large number of fiber membranes are quickly produced. The reason for selecting the receiving distance of 30cm is that the spinning solution will not evaporate completely if the distance is too close, and the spinning solution jet will be discontinuous if the distance is too far. Selecting a larger distance can ensure that the macromolecular chains in the spinning solution are fully stretched and oriented, and the spinning solution is fully drawn, making the fibers thinner and more uniform. Regarding the water treatment temperature, 70℃ is selected because too high water temperature can easily cause the fiber membrane to shrink and destroy the original mechanical properties, while the glass transition temperature of PEO in the fiber is 65℃, at which temperature, the macromolecular chain segments begin to move freely. The reason why the fiber membrane to water mass ratio is 1:50 is that it is difficult to heat when there is too much water, and too low a membrane water mass ratio will not dissolve and remove PEO sufficiently. The reason why the heat treatment temperature is 110℃ is that if it is too low, the fiber will not bend sufficiently, and if it is too high, the fiber membrane will age too quickly due to heat.

[0070] The present application is described in detail below through specific embodiments. The following embodiments are only partial embodiments of the present application and are not limitations of the present application.

[0071] Embodiment 1:

[0072] A method for preparing a PA6 / PEO micro-nano fiber air filter membrane with a curved morphology comprises the following steps:

[0073] 1. Preparation of spinning solution:

[0074] (1) Weigh a certain amount of PA6 particles and PEO powder, dissolve them in a formic acid solution with a mass fraction of 88%, to obtain a mixed solution; wherein the molecular weight of the PEO powder is 100,000;

[0075] (2) The mixed solution was magnetically stirred at room temperature for 6 hours until it was completely dissolved to obtain a uniform PA6 / PEO spinning solution; in the PA6 / PEO spinning solution, the concentration of PA6 was 5%, and the concentration of PEO was 0.5%;

[0076] 2. Preparation of fiber membrane:

[0077] (3) The PA6 / PEO spinning solution prepared in step (2) was extracted with a 10 ml syringe and installed on a gas jet spinning machine;

[0078] (4) Adjust the air compressor output pressure to 0.04 MPa, connect the spinning needle to the airflow nozzle, set the propulsion speed to 1.5 ml / h, the receiving distance to 28 cm, the inner diameter of the spinning needle to 0.33 mm, and mix the PA6 / PEO spinning solution with the high-pressure airflow after being extruded through the needle. After being stretched and refined, it is sprayed onto the rolling receiving roller to form a fiber membrane under room temperature drying conditions;

[0079] (5) Drying the prepared fiber membrane at 60°C overnight to remove residual solvent;

[0080] 3. Heat treatment and deionized water etching treatment:

[0081] (6) placing the fiber membrane obtained in step (5) into an oven for heat treatment, setting the heating temperature to 100° C. and the heating time to 0.3 h. After the heating is completed, immediately taking out the fiber membrane and naturally cooling it to room temperature;

[0082] (7) At room temperature, place the heat-treated fiber membrane in a container, add deionized water to immerse the fiber membrane, the mass ratio of the fiber membrane to the deionized water is 1:40, and then add PEG200 to the water until the concentration of PEG200 reaches 1% for later use;

[0083] (8) Place the container in a water bath at 80°C, heat the container in a water bath, set the water bath time to 0.8h, and repeat the water bath treatment twice;

[0084] (9) After the reaction, the sample was taken out immediately and vacuum dried at 60°C for 2 h to ensure that the sample was completely dry and did not deform, thereby obtaining a PA6 / PEO micro-nano fiber air filtration membrane with a curved shape.

[0085] In the PA6 / PEO micro-nano fiber air filtration membrane with curved morphology prepared in this embodiment, the average diameter of the fiber is 212 nm and the porosity is 69.02%.

[0086] Embodiment 2:

[0087] A method for preparing a PA6 / PEO micro-nano fiber air filter membrane with a curved morphology comprises the following steps:

[0088] 1. Preparation of spinning solution:

[0089] (1) Weigh a certain amount of PA6 particles and PEO powder, dissolve them in a formic acid solution with a mass fraction of 88%, to obtain a mixed solution; wherein the molecular weight of the PEO powder is 600,000;

[0090] (2) The mixed solution was magnetically stirred at room temperature for 7 hours until it was completely dissolved to obtain a uniform PA6 / PEO spinning solution; in the PA6 / PEO spinning solution, the concentration of PA6 was 6% and the concentration of PEO was 1%;

[0091] 2. Preparation of fiber membrane:

[0092] (3) The PA6 / PEO spinning solution prepared in step (2) was extracted with a 10 ml syringe and installed on a gas jet spinning machine;

[0093] (4) Adjust the air compressor output pressure to 0.06 MPa, connect the spinning needle to the airflow nozzle, set the propulsion speed to 2 ml / h, the receiving distance to 30 cm, the inner diameter of the spinning needle to 0.33 mm, and mix the PA6 / PEO spinning solution with the high-pressure airflow after extrusion through the needle. After stretching and thinning, spray it onto the rolling receiving roller to form a fiber membrane under room temperature drying conditions;

[0094] (5) Drying the prepared fiber membrane at 60°C overnight to remove residual solvent;

[0095] 3. Heat treatment and deionized water etching treatment:

[0096] (6) placing the fiber membrane obtained in step (5) into an oven for heat treatment, setting the heating temperature to 110° C. and the heating time to 0.5 h. After the heating is completed, immediately taking out the fiber membrane and naturally cooling it to room temperature;

[0097] (7) At room temperature, place the heat-treated fiber membrane in a container, add deionized water to immerse the fiber membrane, the mass ratio of the fiber membrane to the deionized water is 1:50, and then add PEG200 to the water until the concentration of PEG200 reaches 1% for later use;

[0098] (8) Place the container in a 70°C water bath, heat the container in a water bath, set the water bath time to 1 h, and repeat the water bath treatment twice;

[0099] (9) After the reaction, the sample was taken out immediately and vacuum dried at 60°C for 2 h to ensure that the sample was completely dry and did not deform, thereby obtaining a PA6 / PEO micro-nano fiber air filtration membrane with a curved shape.

[0100] In the PA6 / PEO micro-nano fiber air filtration membrane with a curved morphology prepared in this embodiment, the average diameter of the fiber is 673 nm and the porosity is 72.13%.

[0101] Embodiment 3:

[0102] A method for preparing a PA6 / PEO micro-nano fiber air filter membrane with a curved morphology comprises the following steps:

[0103] 1. Preparation of spinning solution:

[0104] (1) Weigh a certain amount of PA6 particles and PEO powder, dissolve them in a formic acid solution with a mass fraction of 88%, to obtain a mixed solution; wherein the molecular weight of the PEO powder is 1,000,000;

[0105] (2) The mixed solution was magnetically stirred at room temperature for 8 hours until it was completely dissolved to obtain a uniform PA6 / PEO spinning solution; in the PA6 / PEO spinning solution, the concentration of PA6 was 7%, and the concentration of PEO was 1.5%;

[0106] 2. Preparation of fiber membrane:

[0107] (3) The PA6 / PEO spinning solution prepared in step (2) was extracted with a 10 ml syringe and installed on a gas jet spinning machine;

[0108] (4) Adjust the air compressor output pressure to 0.08 MPa, connect the spinning needle to the airflow nozzle, set the propulsion speed to 2.5 ml / h, the receiving distance to 32 cm, the inner diameter of the spinning needle to 0.33 mm, and mix the PA6 / PEO spinning solution with the high-pressure airflow after extrusion through the needle. After stretching and thinning, spray it onto the rolling receiving roller to form a fiber membrane under room temperature drying conditions;

[0109] (5) Drying the prepared fiber membrane at 60°C overnight to remove residual solvent;

[0110] 3. Heat treatment and deionized water etching treatment:

[0111] (6) placing the fiber membrane obtained in step (5) into an oven for heat treatment, setting the heating temperature to 120° C. and the heating time to 0.6 h. After the heating is completed, immediately taking out the fiber membrane and naturally cooling it to room temperature;

[0112] (7) At room temperature, place the heat-treated fiber membrane in a container, add deionized water to immerse the fiber membrane, the mass ratio of the fiber membrane to the deionized water is 1:60, and then add PEG200 to the water until the concentration of PEG200 reaches 1% for later use;

[0113] (8) Place the container in a 60°C water bath, heat the container in a water bath, set the water bath time to 1.2 h, and repeat the water bath treatment twice;

[0114] (9) After the reaction, the sample was taken out immediately and vacuum dried at 60°C for 2 h to ensure that the sample was completely dry and did not deform, thereby obtaining a PA6 / PEO micro-nano fiber air filtration membrane with a curved shape.

[0115] In the PA6 / PEO micro-nano fiber air filtration membrane with a curved morphology prepared in this embodiment, the fiber diameter is 4110 nm and the porosity is 93.09%.

[0116] The performance test results of the PA6 / PEO micro-nano fiber air filtration membrane with curved morphology of the present invention are as follows:

[0117] 1. About fiber morphology (diameter, bending shape):

[0118] like Figure 2 , 3 As shown, PA6 can be well dissolved in formic acid at a certain concentration, but too high a concentration will make the fiber diameter thicker on the one hand, and on the other hand, too high a concentration will make the viscosity of the spinning solution too large, which is easy to clog the needle and cause the inability to spin. Low molecular weight PEO can be well dissolved in formic acid, but too high a concentration will make the dissolving process of PEO slow, and the addition of PEO will also increase the viscosity of the solution, causing the inability to spin smoothly. Medium molecular weight PEO can be well dissolved in formic acid, and the reason for not selecting high concentration is similar to the previous material. The reason why low concentration is not selected is that the coating effect of low-concentration medium molecular weight PEO on the fiber is limited, and the phenomenon after dissolution is not obvious. High molecular weight PEO can be well dissolved in formic acid, and in order to determine a single variable for comparison, high concentration of PEO will make the fiber diameter thicker, which is helpful to the improvement of mechanical properties. Therefore, taking all factors into consideration, the fiber state obtained by the air filter membrane of the present invention with the addition of medium weight PEO in Example 2 is the best.

[0119] like Figure 4 As shown, Figure 4 (a) is the fiber morphology and diameter distribution diagram of the air filter membrane with low molecular weight PEO added under the preparation conditions of Example 2 before heat treatment and deionized water etching treatment; Figure 4(b) is the fiber morphology and diameter distribution diagram of the air filter membrane after heat treatment and deionized water etching treatment with low molecular weight PEO added under the preparation conditions of Example 2;

[0120] like Figure 5 As shown, Figure 5 (a) is the fiber morphology and diameter distribution diagram of the air filter membrane with medium molecular weight PEO added under the preparation conditions of Example 2 before heat treatment and deionized water etching treatment; Figure 4 (b) is the fiber morphology and diameter distribution diagram of the air filter membrane after heat treatment and deionized water etching treatment with medium molecular weight PEO added under the preparation conditions of Example 2;

[0121] like Figure 6 As shown, Figure 6 (a) is the fiber morphology and diameter distribution diagram of the air filter membrane with high molecular weight PEO added under the preparation conditions of Example 2 before heat treatment and deionized water etching treatment; Figure 4 (b) is the fiber morphology and diameter distribution diagram of the air filter membrane after heat treatment and deionized water etching treatment with high molecular weight PEO added under the preparation conditions of Example 2;

[0122] from Figure 4-6 By comparison, it can be clearly seen from the fiber morphology diagram and the diameter distribution diagram that at the same PEO concentration, firstly, comparing the three untreated PEO air filtration membranes with different molecular weights, with the increase of PEO molecular weight, the diameter of the nanofibers in the fiber membrane gradually increases, and the fiber diameter distribution range becomes narrower; secondly, no matter what molecular weight PEO is added, the fiber diameter of the prepared air filtration membrane after heat treatment and deionized water etching is significantly smaller than that of the untreated one.

[0123] contrast Figure 4 (c), (d)- Figure 6(c) and (d) show that, with the increase of PEO molecular weight, the average fiber diameter on the fiber membrane with PEO L (low molecular weight) added is about 356 nanometers, the average fiber diameter on the fiber membrane with PEO M (medium molecular weight) added is about 1020 nanometers, and the average fiber diameter on the fiber membrane with PEO H (high molecular weight) added is 4870 nanometers. By observing the pore size distribution of the membrane fibers, it can be seen that there is a positive correlation between the pore size and the fiber diameter. The morphology and fiber diameter distribution diagram of the micro-nano fibers after hydrothermal treatment show that the average diameters of the PEO L, PEO M and PEO H solutions after treatment are reduced to 355 nanometers, 639 nanometers and 1163 nanometers, respectively, and the overall morphology of the fibers becomes more curved. Third, the treated fibers of the air filtration membranes made of the three molecular weights all show a very obvious curved morphology. This is because in the water bath treatment stage, the water-soluble property of PEO itself can make most of the PEO on the fiber surface be well removed during the heat treatment and deionized water etching, resulting in a reduction in fiber diameter, thereby increasing the specific surface area of ​​the nanofiber in the air filter membrane, and increasing pore size and porosity simultaneously. As can be seen, the air filter membrane processed by heat treatment and deionized water etching has better comprehensive filtering performance. Because the porosity is lower when the diameter is too small, the air permeability is poor, and the diameter distribution range is mainly concentrated on the large diameter, and the pore size is larger, which is not conducive to the adsorption and blocking of small particles, so taking all factors into consideration, the air filter membrane prepared by adding medium molecular weight PEO of the present invention has the best performance.

[0124] like Figure 7 As shown, the concentrations of PA6 and PEO in the spinning solution are 6% and 1%, respectively. From top to bottom, they are multiple light scattering diagrams of the dissolution process under 24 hours with low molecular weight PEO addition, medium molecular weight PEO addition, and high molecular weight PEO addition. This diagram can show the movement state of PEO macromolecule chains with different molecular weights in the solution. It shows that after the addition of high molecular weight PEO, the movement of macromolecules in the solution is more difficult, so the solute is not easily dissolved, and the solute is not easily dissolved, which leads to an increase in the diameter of the fiber during the spinning process and a wider pore size distribution.

[0125] like Figure 8 As shown, from top to bottom, they are multiple light scattering images of the dissolution process of low molecular weight PEO addition, medium molecular weight PEO addition, and high molecular weight PEO addition for 24 hours. From top to bottom, they are multiple light scattering images of the solution placed for 24 hours with low molecular weight PEO addition, medium molecular weight PEO addition, and high molecular weight PEO addition. This figure shows that the spinning solution is uniform and stable as a whole after the solute is completely dissolved, so spinning can be carried out smoothly, and PEO and PA6 will not separate under long-term spinning, and can be spun out at the same time.

[0126] pass Figure 7-8 It can be explained that:

[0127] 1. The above experimental phenomena prove that formic acid as a solvent can dissolve PA6 and PEO well to form a relatively uniform and stable polymer solution. A stable solution can ensure that the fiber membrane of the sample can be stably prepared.

[0128] 2. The data chart also shows that the molecular weight of the macromolecule directly affects the behavior of PEO and PA6 in solution. Formic acid, as a volatile acid, has a lower concentration at the gas-liquid interface, thus attracting more PEO to aggregate.

[0129] 3. At the same time, this also shows that after the solution is completely dissolved into the spinning solution, the entire solution is very stable and homogeneous as a whole, but the solute in it is not completely evenly distributed in some places. This provides a theoretical basis for treating PEO on PA6 / PEO fiber membrane at the molecular level. The behavior of macromolecules in the solution is the essential reason for deionized water etching and heat treatment.

[0130] like Figure 9-10 As shown in the figure, after the air filter membrane is treated, the nanofibers inside it have a significant high bending morphology. This is because after the mixed solution of nylon 6 and PEO undergoes SBS (solution blow spinning), composite fibers are initially formed. After the fibers reach the receiving net, stress accumulates inside the fibers. In the subsequent heating treatment, stress also accumulates inside the fibers due to the difference in thermal properties of the two polymers and the phase separation structure proved to exist in the previous article. Then, the PEO on the fiber surface is removed by water washing. This process not only changes the surface morphology of the fibers, such as increasing porosity and surface roughness, but also leads to an increase in the inhomogeneity of the internal structure. The removal of PEO releases the stress accumulated during spinning and heat setting. At the same time, the inhomogeneity of the internal structure of the fibers and the change in surface morphology work together to make the fibers prone to uneven deformation when subjected to force, ultimately resulting in a significant bending morphology of the fibers. The average curvature of the fibers before and after treatment differs by more than an order of magnitude. The filter device assembled from these highly curved PA6 nanofibers can exhibit excellent filtration performance.

[0131] In summary, the curved nanofibers form an overall three-dimensional network structure in the air filtration membrane. The three-dimensional network structure formed by the curved nanofibers is equivalent to building a multi-level barrier, breathable, and tortuous channel filtration structure system inside the air filtration membrane, which can form a better barrier ability for tiny particles. The structure can also improve the mechanical strength, stability and air permeability of the air filtration membrane, thus providing a structural guarantee for enhancing adsorption performance, mechanical strength and air permeability.

[0132] 2. About pore size and porosity:

[0133] like Fig.11 As shown, the pore size refers to the size of the pores in the nanofiber membrane, which directly affects the filtration effect and air resistance of the membrane. The pore size distribution range of the fiber membrane after hydrothermal treatment is narrow, because the PEO on the surface that helps spinning is removed, and the remaining is a relatively pure PA6 fiber. Therefore, the pore size distribution of the constructed fiber is in a narrow range, especially the pore size distribution of the fiber membrane with the addition of medium molecular weight (6*10^5) PEO is in an extremely narrow range, which is conducive to the precise filtration of fine particles. In particular, the filtration effect for small-sized oily and saline particles described in the present invention is better.

[0134] like Fig.12 As shown in the infrared spectrum before treatment, 3295 cm-1 is the stretching vibration absorption peak of NH in nylon and OH in PEO, 2936 and 2862 cm-1 are the stretching vibration absorption peaks of NH in nylon and OH in PEO. -1 The stretching vibration absorption peak of CH is 1637 cm -1 The 1540 cm-1 is the stretching vibration absorption peak of C=O in nylon, the 1463 cm-1 is the bending vibration absorption peak of NH in nylon, and the -1 The bending vibration absorption peak of -CH2- is 1263cm -1 The stretching vibration absorption peak of CN in nylon is 1106cm -1 The peak at 690 cm is the stretching vibration absorption peak of COC in PEO. -1 The absorption peak at 1106 is the out-of-plane bending vibration absorption peak of CH. Comparing the infrared spectra after treatment, we found that the intensity of the infrared absorption peak has increased. This is attributed to the fact that after PEO is dissolved, the group absorption peak of nylon is revealed, which significantly increases the intensity of the infrared group peak. At the same time, the absorption peak at 1106 basically disappears. This is because COC is destroyed after PEO is dissolved, which once again confirms that PEO on the nylon surface is dissolved. 3295cm -1 The NH stretching vibration absorption peaks in nylon may also contain the OH absorption peaks of PEO. -1 The stretching vibration absorption peak of CH in nylon is 1637cm -1 The peak at 1540 cm is the stretching vibration absorption peak of C=O in nylon. -1 The bending vibration absorption peak of NH in nylon is 1463cm -1 The bending vibration absorption peak of -CH2- in 60 is 1263cm -1 The stretching vibration absorption peak of CN in nylon is 690cm -1The out-of-plane bending vibration absorption peak of CH is shown in FIG. 1 . This proves that in the water bath treatment stage, the PEO dissolved by heating is more likely to aggregate together, and its own property of being soluble in water enables most of the PEO on the surface to be well removed after multiple water bath treatments, further reducing the fiber diameter while increasing the pore size and porosity.

[0135] like Fig.13 As shown, compared with the porosity statistics of different molecular weights, the porosity of PEO L (low molecular weight PEO) is 69.02%, the porosity of PEO M (medium molecular weight PEO) is 72.13%, and the porosity of PEO H (high molecular weight PEO) is 93.09%. This shows that the porosity is significantly affected by different types of PEO, especially PEO H (high molecular weight PEO), which shows the highest porosity. This is because although the fiber diameter prepared by high molecular weight PEO is relatively large, due to the bending morphology of the fiber, a three-dimensional network-like structure is formed inside the air filtration membrane, which further increases the porosity of the fiber membrane, thus also proving the result of the bending morphology of the fiber formed by the present invention after heat treatment and water bath treatment.

[0136] 3. About fiber surface roughness:

[0137] like Fig.14As shown, it can be seen that the obvious roughness effect of the fiber surface. Due to the hydrothermal treatment, the fiber diameter of the fiber membrane with the addition of polymer PEO is reduced, while the fiber membrane with the addition of polymer PEO not only reduces the average fiber diameter, but also produces pores on the fiber surface, making it rougher. This is because the molecular chain of PEO is flexible. In the process of forming the fiber, as the solvent evaporates, the PEO macromolecules gradually move to the gas-liquid interface. At the same time, the rapid evaporation of formic acid causes the viscosity of the fiber to increase rapidly, and finally PEO is enriched in the outer layer of the fiber. In addition, the long molecular chain of PEO with a higher molecular weight is not easy to move completely in the spinning solution during the formation of the fiber, and it is also difficult to disperse evenly on the fiber surface during the solvent evaporation process. Therefore, when the water dissolves, more depressions and holes are formed. At the same time, during the heat treatment process, the orientation of the fiber will also produce shrinkage bending due to uneven distribution of components. The curved shape and finer fibers and rough surfaces are prepared by this process method. These characteristics are all conducive to the filtration of fine oil and salt particles. Therefore, after removing the PEO on the surface of the fiber membrane, the hydrophobicity of the fiber membrane is significantly improved. At the same time, the large number of depressions and holes formed on the surface are more conducive to the adsorption and spreading of oily particles, which alleviates the problem of oily particles gathering in the pores between fibers and slows down the time for oily particles to block the fiber membrane, which not only improves the filtration effect but also extends the service life. At the same time, the crystal structure of salt particles can be adsorbed and confined in the depressions and holes on the fiber surface, making it easier to intercept. The network-like multi-level interception structure formed by the fiber membrane with a high curvature structure allows salt particles to be better blocked and intercepted.

[0138] like Fig.15 As shown, the imagej tool is used to characterize the proportion of pores formed on the surface of the fiber membrane: In terms of area: First, through image processing tools, such as Fig.15 As shown in (a), the fiber membrane Fig.15 (b) Remove the background to get Fig.15 (c) Use the ImageJ tool to calculate the total area of ​​the fiber membrane S1 and the total area of ​​the blank part S2, as shown in Fig.15 (d), the total area of ​​pores on the fiber surface S3, such as Fig.15 (e) in accordance with Figure 5The same type of addition calculation is performed in the same way, and the proportion of the surface pores to the fiber surface is N = S3 / (S1-S2)×100%=10210 / (2209682-1282576)×100%=1.1%. In terms of number: the total number of pores is 143 / 8 roots≈18 / root, that is, in the field of view magnified 10,000 times, there are still about 18 pores distributed on each fiber. It can be proved that the process of the present invention actually forms a large number of depressions and holes on the fiber surface, increasing the roughness of the fiber surface. Compared with the traditional beaded structure that simply increases the roughness, the present invention can reduce the fiber diameter while increasing the roughness, increase the pore size and porosity, and greatly improve the air permeability of the air filter membrane under the condition of equal filtering performance, improve the filtering efficiency, and especially for small-sized oily and salty particles, has obvious interception and filtering effects.

[0139] 4. About filtering effect:

[0140] like Figure 16-17 As shown in the figure, the comparison of the filtration effect of the fiber membrane on small-size oily particles and salt particles before and after treatment shows that the Fig.17 (a) Compared with the removal of PEO, Fig.17 As shown in (b), the filtration efficiency of the fiber membrane for oily and salty particles is significantly improved. The filtration efficiency of the same particle size is basically maintained above 98%, because the specific filtration efficiency is basically dependent on the arrangement of the fibers, the thickness of the membrane and the properties of the fluid. Under the combined effect of the curved fibers and the rough surface, the reduction in fiber diameter and the increase in surface roughness will lead to an increase in filtration efficiency. Generally, the fiber membrane of curved fibers has a higher porosity and smoother gas flow between the curved fibers, resulting in lower gas resistance. At the same time, the increase in surface roughness may lead to increased turbulence in the airflow, which will increase air resistance. Therefore, the change in filtration efficiency of particles with different properties is a combination of curved fibers and rough surfaces. Ultimately, the air resistance increases slightly, while the filtration efficiency is significantly improved, which makes the nanofiber membrane perform well in filtering oily and salty ultrafine particles, and can effectively capture particles of different diameters, especially in filtering small particles and complex pollutants. Considering the embodiment 2 of the present invention as the best embodiment.

[0141] In summary, the PA6 / PEO micro-nano fiber air filtration membrane with a curved shape of the present invention can efficiently filter oily and saline ultrafine particles at the same time, and solves the technical problem of the difficulty in effectively filtering fine oily and saline particles in the prior art by optimizing the structural characteristics of the fiber membrane.

[0142] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for preparing a PA6 / PEO micro-nano fiber air filter membrane with a curved morphology, characterized in that: The steps include:

1. Preparation of spinning solution: (1) Weigh a certain mass of PA6 particles and PEO powder, dissolve them in a formic acid solution with a mass fraction of 88% to obtain a mixed solution; (2) The mixed solution is magnetically stirred at room temperature for 6-8 hours until it is completely dissolved to obtain a uniform PA6 / PEO spinning solution; 2. Preparation of fiber membrane: (3) The PA6 / PEO spinning solution prepared in step (2) was extracted with a 10 ml syringe and installed on a gas jet spinning machine; (4) Adjust the output air pressure of the air compressor, connect the spinning needle with the airflow nozzle, and under certain propulsion speed and receiving distance conditions, the PA6 / PEO spinning solution is extruded through the needle and mixed with the high-pressure airflow, and then sprayed onto the rolling receiving roller after being stretched and refined, and a fiber membrane is formed under room temperature drying conditions; (5) Drying the prepared fiber membrane at 60°C overnight to remove residual solvent; 3. Heat treatment and deionized water etching treatment: (6) placing the fiber membrane obtained in step (5) into an oven for heat treatment, setting the heating temperature to 100-120° C. and the heating time to 0.3-0.6 h. After the heating is completed, immediately taking out the fiber membrane and naturally cooling it to room temperature; (7) At room temperature, place the heat-treated fiber membrane in a container, add deionized water to immerse the fiber membrane, the mass ratio of the fiber membrane to the deionized water is 1:40-1:60, and then add PEG200 to the water until the concentration of PEG200 reaches 1% for later use; (8) Place the container in a water bath at 60-80°C, heat the container in a water bath, set the water bath time to 0.8-1.2h, and repeat the water bath treatment twice; (9) After the reaction, the sample was taken out immediately and vacuum dried at 60°C for 2 h to ensure that the sample was completely dry and did not deform, thereby obtaining a PA6 / PEO micro-nano fiber air filtration membrane with a curved shape.

2. The method for preparing the PA6 / PEO micro-nano fiber air filter membrane with curved morphology according to claim 1, characterized in that: In the step (1), the molecular weight of the PEO powder is 100,000-1,000,000.

3. The method for preparing the PA6 / PEO micro-nano fiber air filter membrane with curved morphology according to claim 1, characterized in that: In the PA6 / PEO spinning solution prepared in step (2), the concentration of PA6 is 5-7%, and the concentration of PEO is 0.5-1.5%.

4. The method for preparing the PA6 / PEO micro-nano fiber air filter membrane with curved morphology according to claim 1, characterized in that: In the step (4), the air compressor output pressure is 0.04-0.08 MPa, the propulsion speed is 1.5-2.5 ml / h, the receiving distance is 28-32 cm, and the inner diameter of the spinning needle is 0.33 mm.

5. The method for preparing the PA6 / PEO micro-nano fiber air filter membrane with curved morphology according to claim 1, characterized in that: In the step (6), the heat treatment temperature is 110° C. and the heating time is set to 0.5 h.

6. The method for preparing the PA6 / PEO micro-nano fiber air filter membrane with curved morphology according to claim 1, characterized in that: In the step (7), the mass ratio of the fiber membrane to the deionized water is 1:

50.

7. The method for preparing the PA6 / PEO micro-nano fiber air filter membrane with curved morphology according to claim 1, characterized in that: In the step (8), the water bath temperature is set to 70° C. and the water bath time is 1 h.

8. The method for preparing the PA6 / PEO micro-nano fiber air filter membrane with curved morphology according to claim 4, characterized in that: In the step (4), the air compressor output pressure is 0.06 MPa, the propulsion speed is 2 ml / h, and the receiving distance is 30 cm.

9. A PA6 / PEO micro-nano fiber air filter membrane with a curved shape, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. The PA6 / PEO micro-nano fiber air filter membrane with a curved morphology according to claim 9, characterized in that: The average diameter of the fiber is 212-4110 nm, and the porosity is 69.02%-93.09%.

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