A ptfe microporous membrane-based two-dimensional nanomesh composite material and a preparation method thereof

Abstract

The present application relates to a kind of PTFE microporous membrane-based two-dimensional nanometer net composite and its preparation method, the specific preparation method is: first, the PTFE resin raw material doped with hydrophilic nanoparticles is made into PTFE microporous membrane by embryo preparation, calendering, two-way stretching and heat setting;Subsequently, with PTFE microporous membrane as substrate, electrostatic spraying is carried out in gradient temperature field, so that polymer droplets are in homogeneous stable state in flight process, deposited on the substrate surface to form polymer liquid film, and temperature-induced phase separation occurs at the hydrophilic nanoparticles to form solvent-rich phase, finally solvent volatilization forms two-dimensional net structure, and obtains two-dimensional nanometer net material continuously covered on the surface of PTFE microporous membrane.The two-dimensional nanometer net prepared by the present application has a diameter of 10-40nm and a pore size of 0.5-1μm;The PTFE microporous membrane-based two-dimensional nanometer net composite has a porosity of ≥90%, a thickness of 10-30μm, a filtration efficiency of ≥95% for 0.1-10μm particles, and has great application potential in the field of filtration and separation.

Description

Technical Field

[0001] This invention belongs to the field of nanofiber filtration materials technology, specifically relating to a PTFE microporous membrane-based two-dimensional nanomesh composite material and its preparation method. Background Technology

[0002] PTFE (polytetrafluoroethylene) microporous membranes are widely used in waterproofing, filtration, separation, and electronic energy fields due to their small pore size, high temperature resistance, and excellent chemical stability. PTFE microporous membranes with a porous structure are obtained through extrusion molding, calendering, biaxial stretching, and heat setting of the raw resin. Their pore size is in the micrometer range, exhibiting high filtration efficiency for submicrometer particles. However, their thinness and poor mechanical properties necessitate compounding with other materials to improve their mechanical properties in practical applications.

[0003] Patent ZL200910083780.X discloses a composite electret membrane, its preparation method, and its uses. This method uses a melt method to prepare a PTFE / FEP electret membrane, and then composites a PP membrane with the PTFE / FEP electret membrane at low temperature to create a novel composite electret membrane. The composite membrane prepared by this method cannot further reduce the pore size of the PTFE microporous membrane, which is above 10 μm, resulting in low physical interception efficiency. Furthermore, the layered composite structure between the fiber membranes increases its thickness, making it difficult to reduce filtration resistance. Patent ZL201610986587.7 discloses a polytetrafluoroethylene (PTFE) coated filter material and its preparation method. This method composites a PTFE microporous membrane with needle-punched felt using an adhesive hot-pressing method. While this improves the mechanical properties of the material, the adhesive easily clogs the pores of the PTFE microporous membrane during the hot-pressing process, leading to reduced porosity and decreased filtration performance. Patent ZL202011521805.2 discloses a high-temperature resistant PTFE membrane filter material and its production method. This method involves processing raised structures on the surface of a PTFE microporous membrane and then hot-pressing the PTFE microporous membrane with a needle-punched felt composed of aramid fibers and glass fibers to obtain a filter material with a multi-layered composite structure. However, this surface processing of the PTFE microporous membrane easily damages its original pore structure and further reduces its mechanical properties, making it prone to cracking during subsequent lamination processes. Summary of the Invention

[0004] The purpose of this invention is to provide a PTFE microporous membrane-based two-dimensional nanomesh composite material and its preparation method, especially a PTFE microporous membrane-based two-dimensional nanomesh composite material with small pore size and high porosity and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solution: a method for preparing a PTFE microporous membrane-based two-dimensional nanomesh composite material, comprising the following steps:

[0006] Step (1): Hydrophilic nanoparticles are doped into PTFE resin to obtain a mixed raw material. The mixed raw material is then subjected to preform preparation, calendering, biaxial stretching and heat setting to obtain a PTFE microporous membrane.

[0007] Step (2): Add the polymer and conductive additive to the solvent and stir evenly to obtain the spinning solution;

[0008] Step (3): By adjusting the spinning environment parameters, a gradient temperature field is formed so that the temperature at the spinneret is lower than the critical temperature for separation of the spinning dopant phase and the temperature at the substrate is higher than the critical temperature for separation of the spinning dopant phase.

[0009] Step (4): Using PTFE microporous membrane as substrate, electrostatic spraying is performed using spinning solution. During the flight of polymer droplets, a liquid film is formed and deposited on the surface of the substrate. The solvent is enriched around the hydrophilic nanoparticles on the surface of the substrate. Under the action of temperature-induced phase separation, a two-dimensional mesh structure is formed, thus obtaining a two-dimensional nano-mesh composite material continuously covered on the surface of PTFE microporous membrane.

[0010] Further, in step (1), the hydrophilic nanoparticles include one or more of the following: silica nanoparticles, titanium dioxide nanoparticles, hydroxyapatite nanoparticles, lithium iron phosphate tourmaline nanoparticles, or calcium magnesium tourmaline nanoparticles. The nanoparticle size is 10-200 nm, and the mass fraction of hydrophilic nanoparticles in the PTFE microporous membrane is 1-20 wt%.

[0011] Furthermore, the PTFE microporous membrane obtained in step (1) has a pore size of 1-5 μm, a porosity of ≥70%, and a thickness of 10-30 μm.

[0012] Furthermore, the polymer in step (2) includes one or more of polyamide, polyvinylidene fluoride, polyacrylonitrile, polyimide, or polystyrene, and the weight-average molecular weight of the polymer is 1×10⁻⁶. 4 ~1.5×10 5 g / mol, the mass fraction of polymer in the spinning solution is 0.5-5 wt%.

[0013] Further, the solvent in step (2) includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, ethanol, isobutanol, n-propanol, ethyl acetate or acetone.

[0014] Further, in step (2), the conductive additive includes one or more of sodium chloride, lithium chloride, zinc chloride, calcium chloride, sodium acetate, sodium benzoate, tetrabutylammonium bromide or silver acetylene, and the mass fraction of the conductive additive in the spinning solution is 0.001 to 0.5 wt%.

[0015] Furthermore, in step (3), the critical temperature for phase separation of the spinning solution is 25-45℃, and phase separation occurs in the spinning solution under conditions higher than the critical temperature for phase separation.

[0016] Furthermore, in step (3), the temperature at the spinneret is 10-25°C, the temperature at the substrate is 35-45°C, and the distance between the spinneret and the substrate is 10-40cm.

[0017] Furthermore, in step (4), the parameters of the electrostatic spraying net are: spinning voltage of 10-80kV, injection speed of 0.1-1mL / h, and ambient humidity of 20-40%.

[0018] The second objective of this invention is to provide a PTFE microporous membrane-based two-dimensional nano-mesh composite material prepared by the above method.

[0019] Furthermore, the diameter of the two-dimensional nanomesh is 10-40 nm and the pore size is 0.5-1 μm; the porosity of the PTFE microporous membrane-based two-dimensional nanomesh composite material is ≥90%, the thickness is 10-30 μm, and the filtration efficiency for 0.1-10 μm particles is ≥95%.

[0020] The technical principle of this invention is as follows: using a PTFE microporous membrane doped with hydrophilic nanoparticles as a substrate, a continuous ultrathin two-dimensional nano-mesh layer is coated on its surface by electrostatic spraying, giving it excellent filtration performance. First, PTFE resin raw material doped with hydrophilic nanoparticles is biaxially stretched to form a PTFE microporous membrane. The hydrophilic nanoparticles are dispersed on the surface of the PTFE microporous membrane, improving its surface roughness and hydrophilicity, making it easier to wet the polymer solution. Then, the spinning environment parameters are adjusted to form a gradient temperature field. The temperature at the spinneret is lower than the critical temperature for phase separation of the spinning solution, while the temperature at the substrate is higher than the critical temperature for phase separation of the spinning solution. This ensures that the polymer droplets extruded from the spinneret are in a homogeneous and stable state during their flight in the electrostatic field until they are deposited on the surface of the PTFE microporous membrane substrate. The polymer liquid film formed by the droplets undergoes phase separation under temperature induction. The solvent phase is enriched around the hydrophilic nanoparticles on the surface of the PTFE microporous membrane substrate and gradually nucleates and grows, causing the continuous polymer-enriched phase to be displaced and aggregated to form a two-dimensional network structure. Finally, under gradually increasing temperature conditions, the solvent evaporates to form a two-dimensional network structure, thus obtaining a PTFE microporous membrane-based two-dimensional nano-network composite material with small pore size and high porosity.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The two-dimensional nano-mesh obtained by electrostatic spraying in this invention has a pore size of 0.5-1 μm, and the porosity of the PTFE microporous membrane-based two-dimensional nano-mesh composite material is ≥90%, with a filtration efficiency of ≥95% for particles of 0.1-10 μm. This significantly reduces the pore size of the PTFE microporous membrane (1-5 μm), and its continuous two-dimensional network structure further improves the porosity and pore connectivity of the PTFE microporous membrane-based two-dimensional nano-mesh composite material, giving it excellent separation and filtration performance.

[0023] 2. The mesh structure of the two-dimensional nanomesh of the present invention can be controlled by electrostatic spraying parameters, and its pore size is highly adjustable, which can improve the problem of uneven pore size of the original PTFE microporous membrane.

[0024] 3. The spinning solution used in the preparation of the PTFE microporous membrane-based two-dimensional nano-mesh composite material of this invention contains a variety of polymers, indicating that the method is highly versatile and has a wide range of applications, and can meet the functional requirements in various application scenarios. Detailed Implementation

[0025] The embodiments of the present invention will be described in detail below. The following embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0026] All reagents used in the following examples are commercially available. All equipment used in the following examples is commercially available.

[0027] Example 1

[0028] The preparation steps of PTFE microporous membrane-based two-dimensional nanomesh composite material are as follows:

[0029] 1) 20g of hydrophilic silica nanoparticles with a particle size of 200nm were doped into 500g of PTFE resin to obtain a mixed raw material. After the mixed raw material was mixed evenly, a preform was made and calendered under a pressure of 0.5MPa. The transverse stretching ratio was set to 10 times and the longitudinal stretching ratio was set to 8 times. After biaxial stretching, the preform was heat-set at 250℃ to obtain a PTFE microporous membrane with a pore size of 1μm, a porosity of 90%, and a thickness of 10μm.

[0030] 2) Dissolve 20g of polyvinylidene fluoride in 500g of N,N-dimethylformamide, add 0.5g of lithium chloride, and stir to obtain the spinning solution;

[0031] 3) Set the spinning environment parameters: the temperature at the spinneret is 25℃, the temperature at the PTFE microporous membrane substrate is 35℃, and the distance between the spinneret and the substrate is 10cm.

[0032] 4) Set the electrostatic spraying parameters: spinning voltage of 80kV, pouring speed of 1mL / h, and ambient humidity of 40%. After electrostatic spraying for 10 minutes, a two-dimensional nano-mesh composite material continuously covering the surface of the PTFE microporous membrane was obtained. The diameter of the obtained two-dimensional nano-mesh was 10nm, the pore size was 0.8μm, the porosity of the obtained PTFE microporous membrane-based two-dimensional nano-mesh composite material was 96%, the thickness was 10μm, and the filtration efficiency for particles of 0.1~10μm was 98%.

[0033] Example 2

[0034] The preparation steps of PTFE microporous membrane-based two-dimensional nanomesh composite material are as follows:

[0035] 1) 20g of hydrophilic hydroxyapatite nanoparticles with a particle size of 150nm were doped into 600g of PTFE resin to obtain a mixed raw material. After the mixed raw material was mixed evenly, a preform was made and calendered under a pressure of 0.5MPa. The transverse stretching ratio was set to 10 times and the longitudinal stretching ratio was set to 8 times. After biaxial stretching, the PTFE microporous membrane was obtained after heat setting at 250℃ with a pore size of 5μm, a porosity of 70%, and a thickness of 20μm.

[0036] 2) Dissolve 12g of polyamide in 250g of formic acid, add 1g of sodium acetate, and stir to obtain the spinning solution;

[0037] 3) Set the spinning environment parameters: the temperature at the spinneret is 20℃, the temperature at the substrate is 45℃, and the distance between the spinneret and the substrate is 20cm.

[0038] 4) Set the electrostatic spraying parameters: spinning voltage 30kV, pouring speed 0.5mL / h, ambient humidity 40%. After electrostatic spraying for 20 minutes, a two-dimensional nano-mesh composite material continuously covering the surface of the PTFE microporous membrane was obtained. The diameter of the obtained two-dimensional nano-mesh was 20nm, the pore size was 0.6μm, the porosity of the obtained PTFE microporous membrane-based two-dimensional nano-mesh composite material was 92%, the thickness was 21μm, and the filtration efficiency for particles of 0.1~10μm was 97%.

[0039] Example 3

[0040] The preparation steps of PTFE microporous membrane-based two-dimensional nanomesh composite material are as follows:

[0041] 1) 20g of hydrophilic silica nanoparticles with a particle size of 10nm were doped into 500g of PTFE resin to obtain a mixed raw material. After the mixed raw material was mixed evenly, a preform was made and calendered under a pressure of 0.5MPa. The transverse stretching ratio was set to 10 times and the longitudinal stretching ratio was set to 8 times. After biaxial stretching, the preform was heat-set at 250℃ to obtain a PTFE microporous membrane with a pore size of 2μm, a porosity of 90%, and a thickness of 25μm.

[0042] 2) Dissolve 15g of polyurethane in 300g of N,N-dimethylformamide, add 1g of sodium chloride, and stir to obtain the spinning solution;

[0043] 3) Set the spinning environment parameters: the temperature at the spinneret is 10℃, the temperature at the substrate is 45℃, and the distance between the spinneret and the substrate is 40cm.

[0044] 4) Set the electrostatic spraying parameters: spinning voltage 70kV, pouring speed 0.8mL / h, ambient humidity 30%. After electrostatic spraying for 12 minutes, a two-dimensional nano-mesh composite material continuously covering the surface of the PTFE microporous membrane was obtained. The diameter of the obtained two-dimensional nano-mesh was 15nm, the pore size was 0.5μm, the porosity of the obtained PTFE microporous membrane-based two-dimensional nano-mesh composite material was 94%, the thickness was 26μm, and the filtration efficiency for particles of 0.1~10μm was 95%.

[0045] Example 4

[0046] The preparation steps of PTFE microporous membrane-based two-dimensional nanomesh composite material are as follows:

[0047] 1) 18g of hydrophilic hydroxyapatite nanoparticles with a particle size of 150nm were doped into 400g of PTFE resin to obtain a mixed raw material. After uniform mixing, a preform was prepared and calendered under a pressure of 0.5MPa. The transverse stretching ratio was set to 10 times and the longitudinal stretching ratio to 8 times. After biaxial stretching, the preform was heat-set at 250℃ to obtain a PTFE microporous membrane with a pore size of 3μm, a porosity of 75%, and a thickness of 10μm.

[0048] 2) Dissolve 10g of polyvinylpyrrolidone in 250g of ethanol, add 0.6g of calcium chloride, and stir to obtain the spinning solution;

[0049] 3) Set the spinning environment parameters: the temperature at the spinneret is 20℃, the temperature at the substrate is 35℃, and the distance between the spinneret and the substrate is 30cm.

[0050] 4) Set the electrostatic spraying parameters: spinning voltage of 10kV, pouring speed of 0.1mL / h, and ambient humidity of 30%. After 8 minutes of electrostatic spraying, a two-dimensional nano-mesh composite material continuously covering the surface of the PTFE microporous membrane was obtained. The diameter of the obtained two-dimensional nano-mesh was 40nm, the pore size was 1μm, the porosity of the obtained PTFE microporous membrane-based two-dimensional nano-mesh composite material was 91%, the thickness was 15μm, and the filtration efficiency for particles of 0.1~10μm was 95%.

[0051] Example 5

[0052] The preparation steps of PTFE microporous membrane-based two-dimensional nanomesh composite material are as follows:

[0053] 1) 16g of hydrophilic silica nanoparticles with a particle size of 150nm were doped into 500g of PTFE resin to obtain a mixed raw material. After uniform mixing, a preform was prepared and calendered under a pressure of 0.5MPa. The transverse stretching ratio was set to 10 times and the longitudinal stretching ratio to 8 times. After biaxial stretching, the preform was heat-set at 250℃ to obtain a PTFE microporous membrane with a pore size of 1.5μm, a porosity of 80%, and a thickness of 20μm.

[0054] 2) Dissolve 10g of polyacrylonitrile in 500g of N,N-dimethylacetamide, add 0.4g of calcium chloride, and stir to obtain the spinning solution;

[0055] 3) Set the spinning environment parameters: the temperature at the spinneret is 20℃, the temperature at the substrate is 40℃, and the distance between the spinneret and the substrate is 25cm.

[0056] 4) Set the electrostatic spraying parameters: spinning voltage of 30kV, infusion rate of 0.6mL / h, and ambient humidity of 30%. After electrostatic spraying for 20 minutes, a two-dimensional nano-mesh composite material continuously covering the surface of the PTFE microporous membrane was obtained. The diameter of the obtained two-dimensional nano-mesh was 30nm, the pore size was 0.8μm, the porosity of the obtained PTFE microporous membrane-based two-dimensional nano-mesh composite material was 93%, the thickness was 20μm, and the filtration efficiency for particles of 0.1-10μm was 97%.

[0057] Example 6

[0058] The preparation steps of PTFE microporous membrane-based two-dimensional nanomesh composite material are as follows:

[0059] 1) 6g of hydrophilic titanium dioxide nanoparticles with a particle size of 70nm were doped into 500g of PTFE resin to obtain a mixed raw material. After the mixed raw material was mixed evenly, a preform was made and calendered under a pressure of 0.5MPa. The transverse stretching ratio was set to 10 times and the longitudinal stretching ratio was set to 8 times. After biaxial stretching, the preform was heat-set at 250℃ to obtain a PTFE microporous membrane with a pore size of 1.2μm, a porosity of 75%, and a thickness of 10μm.

[0060] 2) Dissolve 26g of polyimide in 5000g of dimethyl sulfoxide, add 0.06g of zinc chloride, and stir to obtain the spinning solution;

[0061] 3) Set the spinning environment parameters: the temperature at the spinneret is 25℃, the temperature at the PTFE microporous membrane substrate is 40℃, and the distance between the spinneret and the substrate is 20cm.

[0062] 4) Set the electrostatic spraying parameters: spinning voltage of 50kV, infusion rate of 0.7mL / h, and ambient humidity of 20%. After electrostatic spraying for 15 minutes, a two-dimensional nano-mesh composite material continuously covering the surface of the PTFE microporous membrane was obtained. The diameter of the obtained two-dimensional nano-mesh was 15nm, the pore size was 0.5μm, the porosity of the obtained PTFE microporous membrane-based two-dimensional nano-mesh composite material was 97%, the thickness was 11μm, and the filtration efficiency for particles of 0.1-10μm was 38%.

[0063] Example 7

[0064] The preparation steps of PTFE microporous membrane-based two-dimensional nanomesh composite material are as follows:

[0065] 1) 120g of hydrophilic calcium magnesium tourmaline nanoparticles with a particle size of 50nm were doped into 500g of PTFE resin to obtain a mixed raw material. After the mixed raw material was mixed evenly, a preform was made and calendered under a pressure of 0.5MPa. The transverse stretching ratio was set to 10 times and the longitudinal stretching ratio was set to 8 times. After biaxial stretching, the PTFE microporous membrane was obtained after heat setting at 250℃. The pore size was 2μm, the porosity was 72%, and the thickness was 30μm.

[0066] 2) Dissolve 25g of polystyrene in 500g of N-methylpyrrolidone, add 2.5g of tetrabutylammonium bromide, and stir to obtain the spinning solution;

[0067] 3) Set the spinning environment parameters: the temperature at the spinneret is 20℃, the temperature at the PTFE microporous membrane substrate is 40℃, and the distance between the spinneret and the substrate is 20cm.

[0068] 4) Set the electrostatic spraying parameters: spinning voltage of 60kV, infusion rate of 0.8mL / h, and ambient humidity of 20%. After 15 minutes of electrostatic spraying, a two-dimensional nano-mesh composite material continuously covering the surface of the PTFE microporous membrane was obtained. The diameter of the obtained two-dimensional nano-mesh was 20nm, the pore size was 0.6μm, the porosity of the obtained PTFE microporous membrane-based two-dimensional nano-mesh composite material was 95%, the thickness was 30μm, and the filtration efficiency for particles of 0.1-10μm was 96%.

[0069] It can be seen that the properties of the spinning solution and the electrostatic spraying parameters both affect the morphology of the two-dimensional nanomesh. Under the same polymer spinning solution conditions, reducing the spinning solution concentration and increasing the content of conductive additives are beneficial to improving the conductivity of the spinning solution, thereby reducing the diameter of the two-dimensional nanomesh. Under the same spinning solution conditions, increasing the spinning voltage, reducing the spinning humidity, and lowering the ambient temperature are beneficial to increasing the pore size of the two-dimensional nanomesh. Shortening the spinning time is beneficial to increasing its porosity. From the analysis of the two-dimensional nanomesh forming process, enhancing its spinning jet stretching and slowing down solvent evaporation to increase the jet flight stretching time are the fundamental methods to reduce the pore size and increase the porosity of the two-dimensional nanomesh.

[0070] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a PTFE microporous membrane-based two-dimensional nanomesh composite material, characterized in that, Includes the following steps: Step (1): Hydrophilic nanoparticles are doped into PTFE resin to obtain a mixed raw material. The mixed raw material is then subjected to preform preparation, calendering, biaxial stretching and heat setting to obtain a PTFE microporous membrane. Step (2): Add the polymer and conductive additive to the solvent and stir evenly to obtain the spinning solution; the polymer includes one or more of polyamide, polyvinylidene fluoride, polyacrylonitrile or polystyrene; Step (3): By adjusting the spinning environment parameters, a gradient temperature field is formed so that the temperature at the spinneret is lower than the critical temperature for separation of the spinning dopant phase and the temperature at the substrate is higher than the critical temperature for separation of the spinning dopant phase; the critical temperature for separation of the spinning dopant phase is 25~45℃, the temperature at the spinneret is 10~25℃, and the temperature at the substrate is 35~45℃. Step (4): Using PTFE microporous membrane as substrate, electrostatic spraying is performed using spinning solution to obtain a two-dimensional nano-mesh composite material that is continuously covered on the surface of PTFE microporous membrane.

2. The method for preparing a PTFE microporous membrane-based two-dimensional nanomesh composite material according to claim 1, characterized in that, In step (1), the hydrophilic nanoparticles include one or more of the following: silica nanoparticles, titanium dioxide nanoparticles, hydroxyapatite nanoparticles, lithium iron phosphate tourmaline nanoparticles, or calcium magnesium tourmaline nanoparticles. The nanoparticle size is 10-200 nm, and the mass fraction of hydrophilic nanoparticles in the PTFE microporous membrane is 1-20 wt%.

3. The method for preparing a PTFE microporous membrane-based two-dimensional nanomesh composite material according to claim 1, characterized in that, The PTFE microporous membrane obtained in step (1) has a pore size of 1~5 μm, a porosity of ≥70%, and a thickness of 10~30 μm.

4. The method for preparing a PTFE microporous membrane-based two-dimensional nanomesh composite material according to claim 1, characterized in that, The weight-average molecular weight of the polymer in step (2) is 1×10⁻⁶. 4 ~1.5×10 5 g / mol, the mass fraction of polymer in the spinning solution is 0.5~5 wt%.

5. The method for preparing a PTFE microporous membrane-based two-dimensional nanomesh composite material according to claim 1, characterized in that, The solvent in step (2) includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, ethanol, isobutanol, n-propanol, ethyl acetate or acetone.

6. The method for preparing a PTFE microporous membrane-based two-dimensional nanomesh composite material according to claim 1, characterized in that, In step (2), the conductive additives include one or more of sodium chloride, lithium chloride, zinc chloride, calcium chloride, sodium acetate, sodium benzoate, tetrabutylammonium bromide or silver acetylene, and the mass fraction of the conductive additives in the spinning solution is 0.001~0.5 wt%.

7. The method for preparing a PTFE microporous membrane-based two-dimensional nanomesh composite material according to claim 1, characterized in that, In step (3), the distance between the spinneret and the substrate is 10~40 cm.

8. The method for preparing a PTFE microporous membrane-based two-dimensional nanomesh composite material according to claim 1, characterized in that, In step (4), the parameters for electrostatic spraying are: spinning voltage of 10-80 kV, injection speed of 0.1-1 mL / h, and ambient humidity of 20-40%.

9. A PTFE microporous membrane-based two-dimensional nanomesh composite material prepared by the method of claim 1, characterized in that, The two-dimensional nanomesh has a diameter of 10~40 nm and a pore size of 0.5~1 μm; the PTFE microporous membrane-based two-dimensional nanomesh composite material has a porosity of ≥90%, a thickness of 10~30 μm, and a filtration efficiency of ≥95% for particles of 0.1~10 μm.