Electromagnetic shielding composite film with porous structure and preparation method thereof
By adding low-filling amounts of AgNWs and HO-CNTs to the EVOH nanofiber substrate, a porous electromagnetic shielding composite film was prepared, which solved the problem of balancing electromagnetic shielding effect and mechanical properties, and achieved efficient and economical electromagnetic shielding effect and excellent tensile properties.
Patent Information
- Application Number
- CN202510744456.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-05
- Publication Date
- 2025-09-16
AI Technical Summary
Existing electromagnetic shielding composite films cannot guarantee electromagnetic shielding effects while maintaining mechanical properties, especially the degradation of mechanical properties caused by high filler addition.
EVOH nanofibers were used as the substrate, combined with low-filling AgNWs and HO-CNTs as conductive fillers. A composite membrane was prepared by stirring, ultrasonic treatment and vacuum filtration, and then heat treated under specific conditions to form a uniform porous structure and a continuous conductive network.
It achieves excellent electromagnetic shielding performance (up to 50dB) and good tensile properties (up to 15Mpa) in a wide frequency range, while reducing the amount of conductive filler used and improving preparation efficiency and mechanical properties.
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Figure CN120648024A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electromagnetic shielding material preparation, and in particular to a porous structure electromagnetic shielding composite film and a preparation method thereof. Background Art
[0002] Conventional polymer composites require high filler loading to achieve high electrical conductivity and effective EM shielding performance; however, high filler loading leads to high cost, low processability, and poor mechanical properties.
[0003] At present, the main way to improve the electromagnetic shielding performance of composite membrane materials is to control the filler and structural design. Electromagnetic shielding membrane materials often need a high filler addition to have excellent electromagnetic shielding performance, but too high a filler addition often affects the mechanical properties of the membrane material, resulting in poor tensile properties. Therefore, under the condition of ensuring a low dielectric filling amount, the internal structure of the composite membrane can be changed through process control to greatly increase the attenuation ability of electromagnetic waves. The general composite membrane structure is mainly a stacked structure such as a double-layer structure, a sandwich structure and a multi-layer structure. Although this structure can ensure the electromagnetic shielding effect of the composite membrane and increase the tensile properties of the composite membrane to a certain extent, the increase in thickness will lead to a decrease in the flexibility of the composite membrane, thereby limiting its application range. Summary of the Invention
[0004] In view of the technical problems existing in the background technology, the present application provides a porous structure electromagnetic shielding composite membrane and a preparation method thereof, aiming to solve the problem that it is difficult to balance the electromagnetic shielding effect and mechanical properties of the existing electromagnetic shielding composite membrane.
[0005] In a first aspect, the present application provides a method for preparing a porous structure electromagnetic shielding composite film, characterized by comprising the following steps: S1. The EVOH nanofibers were added to a mixture of isopropyl alcohol and deionized water and mixed uniformly to prepare an EVOH nanofiber suspension; S2. A carbon nanotube dispersion and a silver nanowire dispersion were added to the EVOH nanofiber suspension, and the mixture was stirred and ultrasonicated to prepare an EVOH / CNTs / AgNWs nanofiber suspension; S3. The EVOH / CNTs / AgNWs nanofiber suspension was vacuum-assisted filtered and then air-dried to prepare an EVOH / CNTs / AgNWs composite membrane; S4. The EVOH / CNTs / AgNWs composite membrane is subjected to heat treatment to obtain a porous EVOH / CNTs / AgNWs composite membrane.
[0006] In the technical solution of the present embodiment, EVOH nanofibers are used as a substrate, and a suspension is prepared with low-loaded AgNWs and HO-CNTs as conductive fillers. This suspension is stirred and ultrasonicated, and a composite membrane is prepared using vacuum-assisted filtration. The composite membrane is then heat-treated under specific conditions to obtain a porous EVOH / CNTs / AgNWs electromagnetic shielding nanofiber composite membrane. This preparation method is convenient and highly efficient.
[0007] In some embodiments, in step S4, the heat treatment includes: placing two copper plates on the upper and lower sides of the EVOH / CNTs / AgNWs composite film, respectively, and placing them at 55-65° C. for 22-26 hours; the weight of the copper plates is 50 g.
[0008] In this embodiment, the specific heat treatment temperature and time can make the solvents isopropyl alcohol and water in the EVOH / CNTs / AgNWs composite film evaporate fully and stably, so that the obtained composite film has a uniform porous structure; by using a copper plate to apply pressure during the heat treatment process, the conductive network is made more continuous. Through specific heat treatment conditions and pressure treatment, the composite film not only has a uniform porous structure, but also has a uniform and continuous conductive network distribution.
[0009] In some embodiments, in step S2, the total concentration of carbon nanotubes and silver nanowires in the EVOH / CNTs / AgNWs nanofiber suspension is 2.7-7.4 wt %.
[0010] In this embodiment, the specific concentration of the conductive filler combined with the structure of the composite film can ensure the electromagnetic shielding effect of the composite film while ensuring the mechanical properties of the composite film.
[0011] In some embodiments, in step S2, the concentration of the carbon nanotube dispersion is 3 wt %, and the concentration of the silver nanowire dispersion is 4.4 wt %; the usage ratio of the carbon nanotube dispersion to the silver nanowire dispersion is 1:1.3.
[0012] In this example, carbon nanotubes, as carbon-based materials, have the advantages of high electrical and thermal conductivity, but their dispersion in the composite film is poor and they are prone to agglomeration. Silver nanowires have an excellent aspect ratio, which helps form a good conductive network with the carbon nanotubes within the composite film.
[0013] In some embodiments, in step S1, the mass ratio of the EVOH nanofibers, isopropyl alcohol, and deionized water is 1:50:50; and the concentration of the EVOH nanofiber suspension is 0.9-1.1 wt%.
[0014] In this embodiment, isopropyl alcohol and deionized water are used as solvents and mixed with EVOH nanofibers in a specific ratio to form a substrate. During the subsequent heat treatment process, the solvent evaporates, so that the composite membrane forms a porous structure.
[0015] In some embodiments, in step S1, the mixing includes: using a high-speed shearing machine for 15 to 25 minutes.
[0016] In this embodiment, a stable EVOH nanofiber suspension can be obtained by processing with a high-speed shearing machine.
[0017] In some embodiments, in step S2, the stirring time is 30-45 min, and the ultrasonic treatment time is 1-1.5 h.
[0018] In this embodiment, a uniformly dispersed EVOH / CNTs / AgNWs nanofiber suspension can be obtained by stirring and ultrasonic treatment.
[0019] In the second aspect, the present application provides a porous structure electromagnetic shielding composite membrane, characterized in that it is prepared by the preparation method of the porous structure electromagnetic shielding composite membrane described in any one of claims 1 to 8, comprising an EVOH nanofiber substrate, and AgNWs and HO-CNTs conductive fillers uniformly dispersed in the substrate, the interior of the porous structure electromagnetic shielding composite membrane has a porous structure; the electromagnetic shielding efficiency of the porous structure electromagnetic shielding composite membrane is 45~55dB; the tensile strength of the porous structure electromagnetic shielding composite membrane is 12~15Mpa.
[0020] In the technical solution of the embodiment of the present application, the EVOH / CNTs / AgNWs nanofiber composite membrane with a uniform porous structure has both good electromagnetic shielding effect and mechanical properties.
[0021] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.
[0023] Figure 1 This is the SEM image of the porous EVOH / CNTs / AgNWs composite film prepared in Example 1.
[0024] Figure 2 This is the SEM image of the porous EVOH / CNTs / AgNWs composite film prepared in Comparative Example 1.
[0025] Figure 3 Graphs showing the conductivity and resistivity of the porous EVOH / CNTs / AgNWs composite films prepared in Example 1 and Comparative Example 1.
[0026] Figure 4 Graph showing the electromagnetic shielding performance of the porous EVOH / CNTs / AgNWs composite films prepared in Example 1 and Comparative Example 1.
[0027] Figure 5 Graph showing the tensile properties of the porous EVOH / CNTs / AgNWs composite membranes prepared in Example 1 and Comparative Example 1.
[0028] Figure 6 Graphs showing the electromagnetic shielding effects of the porous EVOH / CNTs / AgNWs composite films prepared in Example 1 and Comparative Examples 2-4.
[0029] Figure 7 Graphs showing the mechanical properties of the porous EVOH / CNTs / AgNWs composite membranes prepared in Example 1 and Comparative Examples 2-4. DETAILED DESCRIPTION
[0030] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.
[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms "including" and "having" and any variations thereof used herein are only for the purpose of describing specific embodiments and are not intended to limit this application.
[0032] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.
[0033] In order to solve the problem that the electromagnetic shielding effect and mechanical properties of existing electromagnetic shielding composite membranes are difficult to balance, the present application provides a porous structure electromagnetic shielding composite membrane and its preparation method. EVOH nanofibers are used as a substrate, AgNWs and HO-CNTs are used as conductive fillers to prepare a suspension, the prepared suspension is stirred and ultrasonicated, and a composite membrane is prepared by vacuum-assisted filtration technology. The composite membrane is then heat-treated under specific conditions. With the gradual evaporation of the solvent combined with a certain pressure, the final EVOH / CNTs / AgNWs electromagnetic shielding nanofiber composite membrane has a uniform porous structure, and the conductive network is evenly distributed and continuous. This structure enables the composite membrane to have excellent electromagnetic shielding performance, with an electromagnetic shielding performance of 50dB in a wide frequency range, and excellent tensile properties, reaching a maximum of 15Mpa. The preparation method does not require the addition of additional porogens, and the preparation process is convenient and highly efficient. In addition, the amount of conductive filler used is small, providing a simple and economical method for preparing electromagnetic shielding nanofiber composite membranes with both good mechanical properties and good electromagnetic shielding effects.
[0034] The present application provides a porous structure electromagnetic shielding composite film and a preparation method thereof, characterized by comprising the following steps: S1. The EVOH nanofibers were added to a mixture of isopropyl alcohol and deionized water and mixed uniformly to prepare an EVOH nanofiber suspension; S2. A carbon nanotube dispersion and a silver nanowire dispersion were added to the EVOH nanofiber suspension, and the mixture was stirred and ultrasonicated to prepare an EVOH / CNTs / AgNWs nanofiber suspension; S3. The EVOH / CNTs / AgNWs nanofiber suspension was vacuum-assisted filtered and then air-dried to prepare an EVOH / CNTs / AgNWs composite membrane; S4. The EVOH / CNTs / AgNWs composite membrane is subjected to heat treatment to obtain a porous EVOH / CNTs / AgNWs composite membrane.
[0035] In the technical solution of the present embodiment, EVOH nanofibers are used as a substrate, and a suspension is prepared with low-loaded AgNWs and HO-CNTs as conductive fillers. This suspension is stirred and ultrasonicated, and a composite membrane is prepared using vacuum-assisted filtration. The composite membrane is then heat-treated under specific conditions to obtain a porous EVOH / CNTs / AgNWs electromagnetic shielding nanofiber composite membrane. This preparation method is convenient and highly efficient.
[0036] Furthermore, in some embodiments, in step S4, the heat treatment includes: placing two copper plates on the upper and lower sides of the EVOH / CNTs / AgNWs composite film, respectively, and placing them at 55-65° C. for 22-26 hours; the weight of the copper plates is 50 g.
[0037] In the technical solution of the embodiment of the present application, the specific heat treatment temperature and time can make the solvent isopropyl alcohol and water in the EVOH / CNTs / AgNWs composite film evaporate fully and stably, so that the obtained composite film has a uniform porous structure; by using copper plates to apply pressure during the heat treatment process, the conductive network is made more continuous. Through specific heat treatment conditions and pressure treatment, the composite film not only has a uniform porous structure, but also the conductive network is evenly and continuously distributed.
[0038] Furthermore, in some embodiments, in step S2, the total concentration of carbon nanotubes and silver nanowires in the EVOH / CNTs / AgNWs nanofiber suspension is 2.7-7.4 wt %.
[0039] In the technical solution of the embodiment of the present application, the specific concentration of conductive filler combined with the structure of the composite film can ensure the electromagnetic shielding effect of the composite film while ensuring the mechanical properties of the composite film.
[0040] Furthermore, in some embodiments, in step S2, the concentration of the carbon nanotube dispersion is 1-3 wt %, and the concentration of the silver nanowire dispersion is 1.7-4.4 wt %.
[0041] In the technical solutions of the embodiments of this application, carbon nanotubes, as carbon-based materials, have the advantages of high electrical and thermal conductivity. However, they have poor dispersion in the composite film material and are prone to agglomeration. Silver nanowires have an excellent aspect ratio, which helps form a good conductive network with the carbon nanotubes within the composite film.
[0042] Furthermore, in some embodiments, in step S1, the mass ratio of the EVOH nanofibers, isopropyl alcohol, and deionized water is 1:50:50; and the concentration of the EVOH nanofiber suspension is 0.9-1 wt%.
[0043] In the technical solution of the embodiment of the present application, isopropyl alcohol and deionized water are used as solvents and mixed with EVOH nanofibers in a specific ratio as a substrate. During the subsequent heat treatment process, the solvent evaporates, so that the composite membrane forms a porous structure.
[0044] Furthermore, in some embodiments, in step S1, the mixing includes: using a high-speed shearing machine for 15 to 25 minutes.
[0045] In the technical solution of the embodiment of the present application, a stable EVOH nanofiber suspension can be obtained by processing with a high-speed shearing machine.
[0046] Furthermore, in some embodiments, in step S2, the stirring time is 30-45 min, and the ultrasonic treatment time is 1-1.5 h.
[0047] In the technical solution of the embodiment of the present application, a uniformly dispersed EVOH / CNTs / AgNWs nanofiber suspension can be obtained by stirring and ultrasonic treatment.
[0048] In the second aspect, an embodiment of the present application provides a porous structure electromagnetic shielding composite membrane, characterized in that it is prepared by the preparation method of the porous structure electromagnetic shielding composite membrane described in any one of claims 1 to 8, comprising an EVOH nanofiber substrate, and AgNWs and HO-CNTs conductive fillers uniformly dispersed in the substrate, the interior of the porous structure electromagnetic shielding composite membrane has a porous structure; the electromagnetic shielding efficiency of the porous structure electromagnetic shielding composite membrane is 45~55dB; the tensile strength of the porous structure electromagnetic shielding composite membrane is 12~15Mpa.
[0049] In the technical solution of the embodiment of the present application, the EVOH / CNTs / AgNWs nanofiber composite membrane with a uniform porous structure has both good electromagnetic shielding effect and mechanical properties.
[0050] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.
[0051] Example 1 This embodiment provides a porous structure electromagnetic shielding composite film and a preparation method thereof, which specifically includes the following steps: (1) Weigh 1 g of EVOH nanofibers, add isopropyl alcohol and deionized water in a ratio of 1:50:50 into a high-speed shearing machine and treat for 20 minutes to prepare an EVOH nanofiber suspension.
[0052] (2) HO-CNTs dispersion with a concentration of 5 mg / ml and AgNWs with a concentration of 6 mg / ml were added to the EVOH nanofiber suspension at a mass ratio of 1:1.3, stirred for 1 h, and then ultrasonically treated for 30 min. The total concentration of HO-CNTs and AgNWs in the EVOH / CNTs / AgNWs nanofiber suspension was 5.2%.
[0053] (3) The EVOH / CNTs / AgNWs nanofiber suspension was vacuum-filtered and then air-dried to obtain an EVOH / CNTs / AgNWs nanofiber composite membrane.
[0054] (4) A 50 g copper block was placed on the surface and bottom of the prepared EVOH / CNTs / AgNWs nanofiber composite membrane, and then the membrane was placed in a vacuum oven at 60 °C for 24 h to obtain a porous EVOH / CNTs / AgNWs nanofiber composite membrane.
[0055] The SEM image of the porous EVOH / CNTs / AgNWs nanofiber composite membrane prepared in this example is as follows: Figure 1 shown.
[0056] Depend on Figure 1 It can be seen from the SEM images in that the prepared porous EVOH / CNTs / AgNWs nanofiber composite membrane has an obvious microscopic pore structure, and the pores are distributed in a relatively dense matrix.
[0057] Comparative Example 1 This comparative example provides a porous structure electromagnetic shielding composite film and a preparation method thereof. Compared with Example 1, the difference is that step (4) is not performed. The other steps are roughly the same as those in Example 1 and will not be repeated here.
[0058] The SEM image of the porous EVOH / CNTs / AgNWs nanofiber composite membrane prepared in Comparative Example 1 is as follows: Figure 2 shown.
[0059] The conductivity, resistivity, electromagnetic shielding effect and mechanical properties of the porous EVOH / CNTs / AgNWs nanofiber composite membranes prepared in Example 1 and Comparative Example 1 were tested. The results were as follows: Figure 3 、 Figure 4 and Figure 5 shown.
[0060] Depend on Figure 2 It can be seen that compared with the composite film in Example 1, the composite film in Comparative Example 1 has no obvious pore structure, and the overall base structure is relatively loose.
[0061] Depend on Figure 3 The results show that the electrical conductivity of the porous nanofiber composite membrane is improved after heat treatment, which may be due to the optimization of the conductive network of the composite membrane after pressurized densification treatment; Figure 4 It can be seen that the electromagnetic shielding performance of the composite film after heat treatment is also improved by nearly 10dB in a wide frequency range. The porous structure is conducive to extending the loss path of electromagnetic waves and increasing the multiple reflections of electromagnetic waves in the pore structure. Figure 5 It can be seen that the mechanical properties of the composite film after heat treatment are also greatly improved compared with those before hot pressing.
[0062] Examples 2-3 and Comparative Examples 2-3 Examples 2-3 and Comparative Examples 2-3 respectively provide a porous structure electromagnetic shielding composite membrane and a preparation method thereof. Compared with Example 1, the difference is that the heat treatment temperature in step (4) is different, as shown in Table 1. The other steps are roughly the same as those in Example 1 and will not be repeated here.
[0063] Table 1 Heat treatment temperature in Examples 2-3 and Comparative Examples 2-3 Comparative Example 4 This comparative example provides a porous structure electromagnetic shielding composite film and a preparation method thereof. Compared with Example 1, the difference is that no copper block is used in the heat treatment in step (4). The other steps are roughly the same as those in Example 1 and will not be repeated here.
[0064] The electromagnetic shielding effect and mechanical properties of the porous EVOH / CNTs / AgNWs nanofiber composite membranes prepared in Examples 2-3 and Comparative Examples 2-4 were tested, and the results were as follows: Figure 6 and Figure 7 shown.
[0065] Depend on Figure 6 From the data in , it can be seen that the electromagnetic shielding effect and mechanical properties of the porous EVOH / CNTs / AgNWs nanofiber composite membranes prepared in Examples 2 to 3 are close to those in Example 1, while the heat treatment temperature in Comparative Example 2 is too low, which causes the electromagnetic shielding performance of the composite membrane to decline. The reason is considered to be that the temperature is not enough, resulting in less pore formation, which is not conducive to multiple reflection losses of electromagnetic waves inside the composite membrane; the heat treatment temperature in Comparative Example 3 is too high, and the electromagnetic shielding performance and mechanical properties of the composite membrane are both declined. It is considered that the high temperature causes the gas inside the composite membrane to evaporate too quickly, resulting in excessively large or broken pores, and to a certain extent, the mesh structure inside the nanofiber membrane, resulting in poor electromagnetic shielding performance and mechanical properties of the composite membrane; when no copper plate is used for heat treatment in Comparative Example 4, the electromagnetic shielding and mechanical properties of the composite membrane are poor, which may be due to the lack of densification treatment, resulting in a low pore formation rate, which is not conducive to the loss of electromagnetic waves.
[0066] In summary, the present application provides a porous structure electromagnetic shielding composite membrane and its preparation method. EVOH nanofibers are used as a substrate, AgNWs and HO-CNTs are used as conductive fillers to prepare a suspension, the prepared suspension is stirred and ultrasonicated, and a composite membrane is prepared by vacuum-assisted filtration technology. The composite membrane is then heat-treated under specific conditions. With the gradual volatilization of the solvent combined with a certain pressure, the final EVOH / CNTs / AgNWs electromagnetic shielding nanofiber composite membrane has a uniform porous structure, and the conductive network is evenly distributed and continuous. This structure enables the composite membrane to have excellent electromagnetic shielding performance, and the electromagnetic shielding performance in a wide frequency range reaches 50dB, and has excellent tensile properties, reaching up to 15Mpa. This preparation method does not require the additional addition of porogens, and the preparation process is convenient and highly efficient. In addition, the amount of conductive filler used is small, providing a simple and economical method for preparing an electromagnetic shielding nanofiber composite membrane with both good mechanical properties and good electromagnetic shielding effects.
[0067] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.
Claims
1. A method for preparing a porous structure electromagnetic shielding composite film, characterized in that: The following steps are involved: S1. The EVOH nanofibers were added to a mixture of isopropyl alcohol and deionized water and mixed uniformly to prepare an EVOH nanofiber suspension; S2. A hydroxylated carbon nanotube dispersion and a silver nanowire dispersion were added to the EVOH nanofiber suspension, and the mixture was stirred and ultrasonically treated to prepare an EVOH / CNTs / AgNWs nanofiber suspension; S3. The EVOH / CNTs / AgNWs nanofiber suspension was vacuum-assisted filtered and then air-dried to prepare an EVOH / CNTs / AgNWs composite membrane; S4. The EVOH / CNTs / AgNWs composite membrane is subjected to heat treatment to obtain a porous EVOH / CNTs / AgNWs composite membrane.
2. The method for preparing a porous structure electromagnetic shielding composite film according to claim 1, characterized in that: In step S4, the heat treatment includes: placing two copper plates on the upper and lower sides of the EVOH / CNTs / AgNWs composite film respectively, and placing the film at 55-65° C. for 22-26 hours.
3. The method for preparing the aromatic porous structure electromagnetic shielding composite film according to claim 2, characterized in that: The weight of the copper plate is 50 g.
4. The method for preparing a porous structure electromagnetic shielding composite film according to claim 1, characterized in that: In step S2, the total concentration of carbon nanotubes and silver nanowires in the EVOH / CNTs / AgNWs nanofiber suspension is 2.7-7.4 wt%.
5. The method for preparing a porous structure electromagnetic shielding composite film according to claim 1, characterized in that: In step S2, the concentration of the carbon nanotube dispersion is 3 wt %, and the concentration of the silver nanowire dispersion is 4.4 wt %; the usage ratio of the carbon nanotube dispersion to the silver nanowire dispersion is 1:1.
3.
6. The method for preparing a porous structure electromagnetic shielding composite film according to claim 1, characterized in that: In step S1, the mass ratio of the EVOH nanofibers, isopropyl alcohol, and deionized water is 1:50:50; and the concentration of the EVOH nanofiber suspension is 0.9-1.0 wt%.
7. The method for preparing a porous structure electromagnetic shielding composite film according to claim 1, characterized in that: In step S1, the mixing includes: using a high-speed shearing machine for 15 to 25 minutes.
8. The method for preparing a porous structure electromagnetic shielding composite film according to claim 1, characterized in that: In step S2, the stirring time is 30 to 45 minutes, and the ultrasonic treatment time is 1 to 1.5 hours.
9. A porous structure electromagnetic shielding composite film, characterized in that: The porous structure electromagnetic shielding composite membrane is prepared by the preparation method of any one of claims 1 to 8, comprising an EVOH nanofiber substrate, and AgNWs and HO-CNTs conductive fillers uniformly dispersed in the substrate, wherein the interior of the porous structure electromagnetic shielding composite membrane has a porous structure.
10. The porous structure electromagnetic shielding composite film and the preparation method thereof according to claim 9, characterized in that: The electromagnetic shielding efficiency of the porous structure electromagnetic shielding composite film is 45-55dB; the tensile strength of the porous structure electromagnetic shielding composite film is 12-15Mpa.