Preparation method of flame-resistant electromagnetic shielding coated fabric

Abstract

The invention discloses a flame-resistant electromagnetic shielding coated fabric preparation method, which comprises: placing a PEDOT: PSS solution on a magnetic stirrer, continuously stirring under a normal temperature condition, slowly adding a component A organic solvent to carry out doping, stirring and carrying out ultrasonic treatment so as to completely dope the organic solvent into the PEDOT: PSS solution, and drying to obtain the flame-resistant electromagnetic shielding coated fabric. The preparation method comprises the following steps: adding a component A acid solution into a carbon nanomaterial to ensure that the solution reaches molecular-level uniform dispersion, slowly adding a component B acid solution to carry out double doping, carrying out stirring and ultrasonic treatment to obtain a double-doped system PEDOT: PSS solution, and compounding the double-doped system PEDOT: PSS solution with the carbon nanomaterial according to a certain ratio to obtain the carbon nanomaterial / PEDOT / PSS composite material. Uniform compounding is achieved through ultrasonic treatment, the obtained coating solution is finished on the surface of the cellulose-based fabric through an after-finishing process, and the functional coating is constructed. According to the flame-retardant electromagnetic shielding fabric coating, the problem that the shielding performance of a flame-retardant shielding coating reported at present fails under combustion is solved, the preparation process is simplified, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of material preparation, and in particular to a method for preparing flame-resistant electromagnetic shielding coated fabric. Background Art

[0002] In modern society, with the widespread use of electronic devices, electromagnetic radiation issues are becoming increasingly prominent, and the importance of electromagnetic shielding fabrics is becoming increasingly prominent. Coated electromagnetic shielding fabrics, with their advantages of lightweight, flexible and foldable design, play a key role in civilian protective equipment such as electromagnetic protective clothing and medical shielding curtains, as well as military equipment such as tactical shielding tents and electronic warfare shields. They can effectively prevent electromagnetic radiation from interfering with organisms, precision instruments, and military communication systems, as well as preventing information leakage.

[0003] However, as electronic devices develop towards miniaturization and high integration, the problem of heat accumulation during operation becomes increasingly serious. In special environments such as military operations, extreme thermal shocks, such as fuel explosions and high-temperature environments caused by electromagnetic pulse weapons, can cause localized combustion, which can lead to pyrolysis and carbonization of the fabric matrix and oxidation and fracture of the conductive network, resulting in a sharp decline in shielding effectiveness. Electromagnetic shielding performance primarily relies on the continuous conductive path created by conductive fillers on the substrate surface. Therefore, solving the problem of rapid failure of the conductive network under high temperature or combustion conditions is of great strategic value to ensuring the continuity of electromagnetic protection functions in complex working conditions.

[0004] At present, flame-retardant electromagnetic shielding fabrics have made some progress. For example, Professor Fu Shaohai's team at Jiangnan University (ACS Appl. Mater. Interfaces, 2021, 13, 38761-38772) constructed an alternating titanium carbide (MXene) / polyetherimide (PEI) coating on the surface of ordinary cotton fabric, making the fabric's electromagnetic shielding performance meet commercial requirements while also having excellent flame retardant properties. Zhang Sheng's team at Beijing University of Chemical Technology (Chem. Eng. J., 2023, 476, 146837) induced polypyrrole to polymerize on the surface with phytic acid (PA) and then dip-coated silver nanowires (AgNWs) to construct an environmentally friendly nylon / cotton blended fabric with both flame retardant and electromagnetic shielding functions. However, existing flame-retardant electromagnetic shielding materials still have defects. The physical structure or chemical properties of the conductive component are prone to irreversible changes at high temperatures, resulting in a decrease or loss of conductive properties. For example, MXene oxidizes to form TiO2 at high temperatures, while AgNWs are converted into isolated Ag2O particles due to the thermal effects of high temperatures. This destroys the original conductive network, impairs the structural integrity of the material upon heating, and makes it difficult to maintain a continuous conductive path. Therefore, the fire resistance of existing flame-retardant electromagnetic shielding fabrics still needs to be improved. The effective protection time of coated fabrics in extreme fire environments needs to be extended as much as possible to avoid secondary risks to electronic equipment caused by shielding failure.

[0005] Based on this, a preparation method of flame-resistant electromagnetic shielding coated fabric is proposed. Summary of the Invention

[0006] The purpose of the present invention is to solve the above problems and to propose a method for preparing a flame-resistant electromagnetic shielding coated fabric.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a flame-resistant electromagnetic shielding coated fabric comprises the following steps: The PEDOT:PSS solution was placed on a magnetic stirrer and stirred continuously at room temperature; Slowly add the organic solvent of component A for doping, stir and perform ultrasonic treatment to fully dope the organic solvent into the PEDOT:PSS solution to ensure that the solution is evenly dispersed at the molecular level; Slowly add the acidic solution of component B for dual doping, and after stirring and ultrasonic treatment, obtain a dual-doping system PEDOT:PSS solution; Compounding the PEDOT:PSS solution of the dual-doping system with carbon nanomaterials in a certain ratio, and achieving uniform compounding through ultrasonic treatment; The obtained coating solution is applied to the surface of cellulose-based fabric through a post-finishing process to construct a functional coating. Preferably, the organic solvent is one or more of ethylene glycol, dimethyl sulfoxide, N,N-dimethylformamide, and glycerol, and its doping amount is 5-12% of the mass fraction of the PEDOT:PSS solution.

[0008] Preferably, the dual-doped acid solution includes one or more of phosphoric acid, phosphorous acid, and phytic acid, and the doping amount thereof is 1-5% of the mass fraction of the solution.

[0009] Preferably, the carbon-based nanomaterials mainly include one or more of carbon nanotubes, graphene, and carbon black.

[0010] Preferably, the compounding ratio is any ratio between 1:1-1:5.

[0011] Preferably, the stirring speed is 300-500 rpm, the stirring time is 20-30 min, the ultrasonic power is 300 W, the frequency is 40 kHz, and the ultrasonic time is 10-20 min.

[0012] Preferably, the cellulose-based fabric mainly includes one or more of pure cotton, ramie, linen and blended fabrics thereof. Preferably, the finishing method includes one or more combinations of spraying, direct dipping, screen printing, and padding.

[0013] A fabric coating that synergistically maintains electromagnetic shielding performance in flames is obtained by compounding a dual-doped PEDOT:PSS solution with carbon nanomaterials. The fabric coating is prepared by a method for preparing a flame-resistant electromagnetic shielding coating fabric.

[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: This application utilizes a dual-filler composite to produce a coated fabric. This synergistic mechanism, characterized by "densification of the expandable carbon layer and reconstruction of the conductive network" at high temperatures, maintains the fabric's electromagnetic shielding effectiveness after combustion. This approach provides an innovative solution for the design of electromagnetic shielding fabrics for complex operating conditions. Experimental data demonstrates that the coated fabric produced by this invention maintains electromagnetic shielding performance exceeding 20 dB after 10 minutes of combustion, while some existing materials exhibit near-ineffective electromagnetic shielding performance after combustion.

[0015] 2. This application adopts a more efficient and convenient preparation method. Compared with the traditional flame-retardant electromagnetic shielding fabric, which separates the flame retardancy and electromagnetic shielding into two steps, the present invention integrates the flame retardancy and electromagnetic shielding into an integrated design to prepare a flame-retardant electromagnetic shielding fabric coating, breaking through the currently reported problem that the shielding performance of the flame-retardant shielding coating fails under combustion, simplifies the preparation process, and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Shown is a schematic diagram of the SEM image structure of a coated fabric provided according to an embodiment of the present invention; Figure 2 A schematic diagram of the SEM image structure of the coated fabric after combustion provided by an embodiment of the present invention is shown; Figure 3 A schematic diagram of the image structure of the change in electromagnetic shielding performance of a coated fabric before and after combustion according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0018] Example 1 Raw material preparation: prepare PEDOT:PSS solution, 9% by mass ethylene glycol, 3% by mass phytic acid aqueous solution, electrochemical graphene, and pure cotton fabric.

[0019] Preparation of a dual-doped PEDOT:PSS solution: Place the PEDOT:PSS solution on a magnetic stirrer and stir at room temperature. Slowly add ethylene glycol (9% by weight of the PEDOT:PSS solution) for doping. Ultrasonication is performed during stirring at 300 W and 40 kHz. After stirring for a period of time, a phytic acid aqueous solution (3% by weight of the PEDOT:PSS solution) is slowly added for dual doping. Stir again and ultrasonicate. Repeat the "stirring-ultrasonication" cycle three times to ensure molecular-level dispersion and obtain a uniformly doped solution.

[0020] Compounding with carbon nanomaterials: The dual-doping solution is compounded with electrochemical graphene at a solid content ratio of 1:2, and uniform dispersion is achieved through ultrasonic treatment.

[0021] To create a functional coating, the compounded solution was evenly sprayed onto the cotton fabric surface using a spray gun (nozzle diameter 0.22 mm, pressure 0.2 MPa). The fabric was then dried in an oven at 60°C for 5 hours.

[0022] Example 2 The steps of this embodiment are basically the same as those of Example 1, except that 9% by mass of PEDOT:PSS ethylene glycol is replaced by 5% by mass of dimethyl sulfoxide, and 3% by mass of phytic acid solution is replaced by 1% by mass of phosphoric acid solution.

[0023] Example 3 The steps of this embodiment are basically the same as those of Example 1, except that the 3% mass fraction phytic acid solution is replaced with a 1% mass fraction phosphorous acid solution, and the solid content ratio of the electrochemical graphene is changed from 1:2 to 1:4.

[0024] Example 4 The steps of this embodiment are basically the same as those of embodiment 1, except that the pure cotton fabric is replaced with ramie fabric, and the spraying method is changed to the padding method.

[0025] Example 5 The steps of this embodiment are basically the same as those of embodiment 1, except that the 3% by mass phytic acid solution is replaced with a 1% by mass phosphorous acid solution, and the electrochemical graphene is replaced with carbon black in a ratio of 1:4.

[0026] Example 6 The steps of this embodiment are basically the same as those of embodiment 1, except that the electrochemical graphene is replaced with multi-walled carbon nanotubes in a ratio of 1:4, and the post-finishing method is changed from spraying to direct dipping.

[0027] Comparative Example 1 The steps of this embodiment are exactly the same as those of embodiment 1, except that no organic solvent is added as a dopant.

[0028] Comparative Example 2 The steps of this embodiment are exactly the same as those of embodiment 1, except that no acid solution is added as a dopant.

[0029] Comparative Example 3 The steps of this embodiment are exactly the same as those of embodiment 1, except that no carbon nanomaterials are added.

[0030] Performance Testing Test items and methods Flame retardant performance test: Test according to the vertical burning test standard (such as GB / T5455-2014 "Textile combustion performance - Determination of vertical direction damage length, smoldering and afterflaming time"), observe the damage length, smoldering and afterflaming time of the fabric during the burning process to determine its flame retardant performance.

[0031] Electromagnetic Shielding Performance Test: A vector network analyzer (Model: N5242A) was used to test the electromagnetic shielding effectiveness (EMI SE) of the fabric in the 1-10 GHz frequency range. Fabric samples were cut to the appropriate size and mounted in a test fixture, ensuring a tight fit between the sample and the fixture to prevent electromagnetic leakage. Initial EMI shielding performance was tested, as well as after a 10-minute burn.

[0032] The test results are shown in the following table

[0033] The results of the Examples and Comparative Examples show that the electromagnetic shielding performance of the dual-doped PEDOT:PSS compounded with carbon nanofillers in the present invention remains above 40dB in its initial state and above 20dB after combustion. In the Comparative Example, which lacks organic solvent doping, the initial electromagnetic shielding performance is only 20.15dB, which remains essentially unchanged after combustion. The solution without the acid solution dual-doping exhibits no flame retardancy. And while the solution without the carbon nanomaterial synergistic compounding achieves an electromagnetic shielding performance of 46.78dB, it only reaches 2.89dB after combustion, virtually negating its electromagnetic shielding performance.

[0034] The above description of the embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a flame-resistant electromagnetic shielding coated fabric, characterized in that: The following steps are involved: The PEDOT:PSS solution was placed on a magnetic stirrer and stirred continuously at room temperature; Slowly add the organic solvent of component A for doping, stir and perform ultrasonic treatment to fully dope the organic solvent into the PEDOT:PSS solution to ensure that the solution is evenly dispersed at the molecular level; Slowly add the acidic solution of component B for dual doping, and after stirring and ultrasonic treatment, obtain a dual-doping system PEDOT:PSS solution; Compounding the PEDOT:PSS solution of the dual-doping system with carbon nanomaterials in a certain ratio, and achieving uniform compounding through ultrasonic treatment; The obtained coating solution is applied to the surface of cellulose-based fabric through a post-finishing process to construct a functional coating.

2. The method for preparing a flame-resistant electromagnetic shielding coated fabric according to claim 1, characterized in that: The organic solvent is one or more of ethylene glycol, dimethyl sulfoxide, N,N-dimethylformamide, and glycerol, and its doping amount is 5-12% of the mass fraction of the PEDOT:PSS solution.

3. The method for preparing a flame-resistant electromagnetic shielding coated fabric according to claim 1, characterized in that: The dual-doped acid solution includes one or more of phosphoric acid, phosphorous acid, and phytic acid, and the doping amount thereof is 1-5% of the mass fraction of the solution.

4. The method for preparing a flame-resistant electromagnetic shielding coated fabric according to claim 1, characterized in that: The carbon-based nanomaterials mainly include one or more of carbon nanotubes, graphene, and carbon black.

5. The method for preparing a flame-resistant electromagnetic shielding coated fabric according to claim 1, characterized in that: The compounding ratio is any ratio between 1:1 and 1:

5.

6. The method for preparing a flame-resistant electromagnetic shielding coated fabric according to claim 1, characterized in that: The stirring speed is 300-500 rpm, the stirring time is 20-30 min, the ultrasonic power is 300 W, the frequency is 40 kHz, and the ultrasonic time is 10-20 min.

7. The method for preparing a flame-resistant electromagnetic shielding coated fabric according to claim 1, characterized in that: The cellulose-based fabric mainly includes one or more of pure cotton, ramie, linen and blended fabrics thereof.

8. The method for preparing a flame-resistant electromagnetic shielding coated fabric according to claim 1, characterized in that: The finishing method includes one or more combinations of spraying, direct dipping, screen printing, and padding.

9. A fabric coating that synergistically maintains electromagnetic shielding performance in flames is obtained by compounding a dual-doped PEDOT:PSS solution with a carbon nanomaterial, characterized in that: The flame-resistant electromagnetic shielding coated fabric is prepared by the preparation method of any one of claims 1 to 8.

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