Preparation method and application of carbonized fabric

Abstract

The invention discloses a carbonized fabric and a preparation method thereof. A metal chlorate solution (such as cobalt chloride, nickel chloride and other metal chlorates) is introduced as a charring coating, so that a conductive network can be stabilized in the charring process, the microstructure regulation and control capability is improved, and the high temperature resistance and oxidation resistance of the material can be enhanced. According to the material, renewable fibers are used as raw materials, carbon conversion is achieved through a green low-energy-consumption technology, and the material has good electromagnetic shielding performance and a flexible structure, has corrosion resistance and practicability and can be widely applied to the fields of intelligent electronics, wearable equipment, building protection and the like.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic shielding materials technology, specifically relating to a method for preparing carbonized fabric and its application. Background Technology

[0002] With the rapid development of flexible electronics and smart devices, the demand for lightweight, flexible, and multifunctional electromagnetic shielding materials continues to rise. Carbonized textiles, a new type of material made from natural fibers through high-temperature carbonization, have shown broad application prospects in wearable electronics, intelligent sensing systems, and medical electronics due to their excellent softness, intrinsic conductivity, structural stability, and chemical corrosion resistance (the shielding performance is basically stable after immersion in 0.1 mol / L hydrochloric acid or sodium hydroxide solution for 24 hours). However, their practical promotion and performance optimization still face multiple challenges, most notably the imbalance between conductivity, electromagnetic shielding effectiveness, and thermal stability.

[0003] From the perspective of manufacturing process, most carbonized textiles currently rely on a long carbonization process in a high-temperature inert atmosphere (such as argon, nitrogen or argon-hydrogen mixture). This process is not only time-consuming and energy-intensive (for example, the team led by Zhang Yingying at Tsinghua University carbonized fabrics in an argon-hydrogen mixture for up to 200 minutes), but also has stringent requirements for equipment sealing and temperature control, which significantly increases production costs and technical barriers, limiting large-scale applications.

[0004] More importantly, the performance shortcomings of traditional carbonized textiles are particularly pronounced in extreme environments: their structural stability is insufficient under harsh conditions such as high temperatures or open flames, which can easily lead to the breakage of the internal conductive network, thereby causing electromagnetic shielding performance failure. This contradiction is directly reflected in the difficulty of coordinating "conductivity-electromagnetic shielding effectiveness-thermal stability"—although the material has basic conductivity and electromagnetic shielding capabilities (relying on the continuous conductive network formed by carbonization), its short thermal stability prevents it from maintaining performance under complex working conditions (such as high temperature and mechanical impact); while extending the carbonization time or increasing the temperature to enhance thermal stability will further increase energy consumption and cost, forming a dual constraint of "performance improvement-process burden". Summary of the Invention

[0005] To address the challenge of preparing carbonized fabrics with combined conductivity, electromagnetic shielding effectiveness, and thermal stability using existing technologies, this invention proposes a method for preparing and applying carbonized fabrics. By introducing a metal chloride solution (such as aluminum chloride, nickel chloride, etc.) as a carbonizing coating, not only can the conductive network be stabilized during carbonization, enhancing the ability to control the microstructure, but the material's high-temperature resistance and oxidation resistance can also be improved. Metal salts can construct a stable carbonization environment under high-temperature conditions, avoiding uneven reactions and structural damage, thereby effectively improving the conductivity, electromagnetic shielding effectiveness, and thermal stability of the carbonized products. This novel strategy combines the advantages of green processes, low-cost preparation, and material multifunctionality, providing an ideal material solution for flexible electronics, fire-resistant shielding fabrics, and high-reliability electronic devices.

[0006] The specific technical solution of the present invention is as follows: S1. Modifying cellulose-based textiles with a charcoal coating; wherein the charcoal coating is one or more of cobalt chloride hexahydrate, ferric chloride hexahydrate, nickel chloride hexahydrate, aluminum chloride hexahydrate, chromium chloride hexahydrate, strontium chloride hexahydrate, and calcium chloride hexahydrate; preferably, the areal density of the charcoal coating on the fabric is 5-20 mg / cm³. 2 .

[0007] S2. The cellulose-based fabric treated with the carbonization coating in S1 is calcined and carbonized in an air atmosphere.

[0008] Furthermore, the cellulose-based textile is one or more of pure cotton, linen, and ramie fabric.

[0009] Furthermore, in step S1, the finishing method is one or more of spraying, padding, and soaking.

[0010] Preferably, the modified fabric is dried at a temperature of 50-90 ℃ before S2 calcination.

[0011] Furthermore, in step S2, the calcination method is one or more of the following: muffle furnace, blowtorch, and tube furnace.

[0012] Furthermore, in step S2, the calcination temperature is 800℃-1300℃.

[0013] Furthermore, the calcination time is 3-30 min.

[0014] By utilizing the catalytic protection of metal chlorides and a high-temperature carbonization process in air, a stable, high-temperature-resistant conductive carbon layer is formed, thereby improving the material's fire resistance and electromagnetic shielding performance. Specifically, metal chlorides decompose and catalytically protect the carbonization of fabrics under high-temperature conditions, while simultaneously optimizing the microstructure of the carbon layer, significantly improving the material's conductivity and stability. Biomass materials, as renewable resources, typically have a high carbon content; their synergistic effect with metal chlorides effectively increases the carbon source content during the carbonization process. This synergistic effect helps form a thicker and stronger carbon layer and enables rapid, integrated molding of carbon fabric materials, resulting in high-carbon-content, high-performance materials. Metal chlorides form oxide particles under high-temperature conditions; on one hand, the oxide layer, through a shell-like supporting effect, constructs a stable three-dimensional carbon skeleton structure at the microscale; on the other hand, this composite layer effectively inhibits oxygen penetration and concentrated heat conduction. Compared to traditional systems relying solely on surface carbon layers for protection under inert atmospheres, this oxide-carbon composite structure exhibits significant advantages: its synergistic effect not only slows down the thermal decomposition rate of the fiber matrix, but more importantly, through the anchoring effect of the oxide phase, it effectively avoids the structural collapse that easily occurs in a simple carbon layer under thermal stress, thus significantly reducing the risk of complete carbonization and structural collapse. This in-situ formed oxide-reinforced interface layer provides dual protection for the structural stability of fiber composites under high-temperature environments, significantly improving the material's resistance to thermal shock, slowing down the thermal decomposition rate of the fiber matrix, and reducing the risk of complete carbonization and structural collapse.

[0015] The present invention also provides a conductive carbon fabric prepared by the above method. The obtained carbon fabric not only has high electromagnetic shielding performance, but also exhibits excellent corrosion resistance.

[0016] The advantages of this invention are: the material possesses excellent electromagnetic shielding performance, and the electromagnetic shielding effect of the carbonized fabric prepared therefrom is SE T Reachable The resistance can be as low as 2.90. 0.17 mS -1 It also has good fire resistance and is suitable for various applications such as wearable electronics, smart sensors and energy conversion in complex environments, breaking through the limitations of traditional shielding materials in terms of single function and poor applicability. Attached Figure Description

[0017] Figure 1 The image shows the combustion of the electromagnetic shielding carbon material in this invention under an alcohol lamp flame. Figure 2 This is a schematic diagram of the Ni-Cot sample before and after carbonization; Figure 3 To assess the shielding performance at different carbonization temperatures; Figure 4The shielding performance at different carbonization times; Figure 5 This is a scanning electron microscope image; Figure 5 (a), (b), and (c) are scanning electron microscope images of Al-Cot-T1000 after carbonization; (d), (e), and (f) are surface morphology images of Al-Cot-L10 after carbonization. Detailed Implementation

[0018] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0019] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0020] The embodiments of the present invention will be further described below with reference to several examples.

[0021] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0022] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0023] Example 1 S1. Aluminum chloride hexahydrate (AlCl3·6H2O) was selected as the raw material for the metal chloride char coating. It was mixed with deionized water to prepare a solution, and ultrasonically dispersed to ensure uniform mixing. Then, the resulting mixture was uniformly loaded onto the surface of cotton fabric by spraying, and the areal density of the metal chloride char coating on the fabric was controlled to be 10 mg / cm². After that, it was placed in an oven at 80℃ to dry.

[0024] S2. The modified fabric matrix material prepared above is placed between two quartz plates and placed in a muffle furnace at 800, 1100, and 1300 ℃, and carbonized in air atmosphere for 10 min to prepare electromagnetic shielding carbon materials Al-Cot-T800, Al-Cot-T1100, and Al-Cot-T1300. Table 1 shows the preparation parameters of Al-Cot-T.

[0025] To characterize its electromagnetic shielding performance and fire resistance stability, a four-point probe instrument was used to test its conductivity; a vector network analyzer was used to test its electromagnetic shielding performance; and an alcohol lamp burning test was conducted to test its fire resistance.

[0026] Example 2S1: Aluminum chloride hexahydrate (AlCl3·6H2O) was selected as the raw material for the metal chloride char coating. It was mixed with deionized water to prepare a solution, and ultrasonically dispersed to ensure uniform mixing. Then, the resulting mixture was uniformly loaded onto the fabric surface by spraying, and the areal density of the metal chloride char coating on the fabric was controlled to be 10 mg / cm². After that, it was placed in an oven at 80 ℃ to dry.

[0027] S2. The modified fabric matrix material prepared above is placed between two quartz plates and placed in a muffle furnace at 1100 ℃. It is then carbonized in air atmosphere for 3, 10, and 30 min to prepare electromagnetic shielding carbon materials Al-Cot-t3, Al-Cot-t10, and Al-Cot-t30. Table 1 shows the preparation parameters of Al-Cot-t.

[0028] To characterize its electromagnetic shielding performance and fire resistance stability, a four-point probe instrument was used to test its conductivity; a vector network analyzer was used to test its electromagnetic shielding performance; and an alcohol lamp burning test was conducted to test its fire resistance.

[0029] Example 3 S1. Aluminum chloride hexahydrate (AlCl3·6H2O) was selected as the raw material for the metal chloride char coating. It was mixed with deionized water to prepare a solution, and ultrasonically dispersed to ensure uniform mixing. Then, the resulting mixture was uniformly loaded onto the fabric surface by spraying, and the areal density of the metal chloride char coating on the fabric was controlled to be 5, 10, and 20 mg / cm². After that, it was dried in an oven at 80℃.

[0030] S2. The modified fabric matrix material prepared above is placed between two quartz plates and placed in a muffle furnace at 1100 ℃ for carbonization in air atmosphere for 10 min to prepare electromagnetic shielding carbon materials Al-Cot-L5, Al-Cot-L10, and Al-Cot-L20. Table 1 shows the preparation parameters of Al-Cot-L.

[0031] To characterize its electromagnetic shielding performance and fire resistance stability, a four-point probe instrument was used to test its conductivity; a vector network analyzer was used to test its electromagnetic shielding performance; and an alcohol lamp burning test was conducted to test its fire resistance.

[0032] Example 4 S1. Calcium chloride hexahydrate (CaCl₂) is selected. 2·Nickel chloride hexahydrate (NiCl2·6H2O) was used as a raw material for the carbonized metal chloride coating. It was mixed with deionized water to prepare a solution of a certain concentration, and then ultrasonically dispersed to ensure uniform mixing. The resulting mixture was then uniformly applied to the fabric surface by spraying, controlling the areal density of the carbonized metal chloride coating on the fabric to be 10 mg / cm², and finally dried in an oven at 80 ℃.

[0033] S2. The modified fabric matrix material prepared above is placed between two quartz plates and placed in a muffle furnace at 1100 ℃ for carbonization in air atmosphere for 10 min to prepare electromagnetic shielding carbon materials Ca-Cot and Ni-Cot. Table 1 shows the preparation parameters of Ca-Cot and Ni-Cot.

[0034] To characterize its electromagnetic shielding performance and fire resistance stability, a four-point probe instrument was used to test its conductivity; a vector network analyzer was used to test its electromagnetic shielding performance; and an alcohol lamp burning test was conducted to test its fire resistance.

[0035] Example 5 S1. Aluminum chloride hexahydrate (AlCl3·6H2O) was selected as the raw material for the metal chloride char coating. It was mixed with deionized water to prepare a solution of a certain concentration, and ultrasonically dispersed to ensure uniform mixing. Then, the resulting mixture was uniformly loaded onto the surface of linen and ramie fabric by spraying, controlling the areal density of the metal chloride char coating on the fabric to be 10 mg / cm², and then dried in an oven at 80 ℃.

[0036] S2. The modified fabric matrix material prepared above is placed between two quartz plates and placed in a tube furnace at 1100 ℃ for carbonization in air atmosphere for 10 min to prepare electromagnetic shielding carbon materials Al-Lin and Al-Ram. Table 1 shows the preparation parameters of Al-Lin and Al-Ram.

[0037] To characterize its electromagnetic shielding performance and fire resistance stability, a four-point probe instrument was used to test its conductivity; a vector network analyzer was used to test its electromagnetic shielding performance; and an alcohol lamp burning test was conducted to test its fire resistance.

[0038] Table 1 Preparation Parameters <![CDATA[IS areal density (mg / cm 2 )]]> Carbonization temperature (°C) Carbonization time (min) Al-Cot-T800 10 800 10 Al-Cot-T1100 10 1100 10 Al-Cot-T1300 10 1300 10 Al-Cot-t3 10 1100 3 Al-Cot-t10 10 1100 10 Al-Cot-t30 10 1100 30 Al-Cot-L5 5 1100 10 Al-Cot-L10 10 1100 10 Al-Cot-L20 20 1100 10 Ca-Cot 10 1100 10 Ni-Cot 10 1100 10 Al-Lin 10 1100 10 Al-Ram 10 1100 10 Comparative Example 1 Pure cotton fabric was carbonized in a muffle furnace at 1100 ℃ for 10 min between two quartz plates to prepare carbon fabric-based material Pure-Cot.

[0039] Comparative Example 2 The only difference from Example 5 is that the substrate is polyester (Pol) fabric, and carbon fabric-based material Al-Pol is prepared.

[0040] Comparative Example 3 The only difference from Example 4 is that the IS composition is a 100% ammonium chloride (NH4Cl) solution, and the carbon fabric-based material NH3-Cot is prepared.

[0041] Comparative Example 4 The only difference from Example 1 is that the carbonization temperature is 1400 ℃, and the carbon fabric matrix material Al-Cot-T1400 is prepared.

[0042] Comparative Example 5 The only difference from Example 2 is that the carbonization time is 40 min, and the carbon fabric matrix material Al-Cot-t40 is prepared.

[0043] Comparative Example 6 The only difference from Example 3 is that the areal density of the coating is 30 mg / cm², and the carbon fabric-based material Al-Cot-L30 is prepared.

[0044] Comparative Example 7 The only difference from Example 3 is that the areal density of the coating is 0.5 mg / cm², and the carbon fabric-based material Al-Cot-L0.5 is prepared.

[0045] like Figure 1 As shown, based on the combustion of the sample under an alcohol lamp, it can be seen that the carbon fabric matrix material prepared by the present invention has good fire resistance. It does not exhibit shrinkage or flame spread under an alcohol lamp, maintains good morphological integrity, and has good fire resistance.

[0046] like Figure 2 As shown, the surface morphology of the fabric after carbonization in an air atmosphere is displayed. The texture of the fabric is still clearly visible after carbonization. Since biomass is mainly composed of cellulose and lignin, graphitic biochar is formed during the carbonization process. At the same time, the granular biochar forms a more complete conductive structural network, improving the electron conduction channels and thus increasing conductivity. Higher conductivity means more free electrons on the material surface. When electromagnetic waves are incident on the surface of the conductive material, the free electrons respond quickly, reflecting the electromagnetic waves, thus achieving higher electromagnetic shielding performance.

[0047] like Figure 3 , Figure 4As shown in the figure, the electromagnetic shielding performance of the carbonized samples increases with increasing carbonization time and temperature. However, the figure also shows that excessively long carbonization times may actually reduce the electromagnetic shielding performance of the carbonized fabric. This is because excessively long carbonization times in air can lead to over-oxidation of the formed conductive carbon layer, thereby damaging the conductive network.

[0048] like Figure 5 As shown in the scanning electron microscope (SEM) image of the carbonized fabric, after carbonization with aluminum chloride in an air atmosphere, a large number of particulate materials formed on the fiber surface. The morphological characteristics indicate that these are metal oxides generated by the pyrolysis of alumina. These particles exhibit a relatively uniform distribution on the fiber surface, with some areas even forming continuous or semi-continuous coating layers. This indicates a dual protection mechanism for the fiber structure during high-temperature treatment: on the one hand, the oxide layer, through a shell-like supporting effect, constructs a stable three-dimensional carbon skeleton structure at the microscale; on the other hand, this composite layer effectively inhibits oxygen penetration and concentrated heat conduction. Compared to traditional systems relying solely on surface carbon layers for protection under an inert atmosphere, this oxide-carbon composite structure exhibits significant advantages: its synergistic effect not only slows down the thermal decomposition rate of the fiber matrix, but more importantly, through the anchoring effect of the oxide phase, it effectively avoids the structural collapse phenomenon that easily occurs in a simple carbon layer under thermal stress, thereby significantly reducing the risk of complete carbonization and structural collapse. This in-situ formed oxide-reinforced interface layer provides dual protection for the structural stability of fiber composites under high-temperature conditions, significantly improves the material's resistance to thermal shock, slows down the thermal decomposition rate of the fiber matrix, and reduces the risk of complete carbonization and structural collapse.

[0049] Furthermore, the metal oxide particles formed on the fiber surface and the carbon skeleton jointly construct a typical conductive-dielectric heterostructure, possessing multiple electromagnetic wave response mechanisms. In this structure, the carbonized fabric acts as a conductive skeleton, providing certain channels for free charge carriers; the metal oxides, as the dielectric loss phase, possess excellent polarization capabilities. Their synergistic effect facilitates the reflection, absorption, and dissipation of electromagnetic waves within the material, constructing a multipath scattering and interfacial polarization mechanism, significantly improving the material's electromagnetic shielding performance. In addition, the high specific surface area resulting from surface roughening and the microstructure of the particles further promotes the multiple scattering and attenuation processes of electromagnetic waves.

[0050] Table 2 Test results of electrical conductivity and electromagnetic shielding performance As shown in Table 2, the analysis of the examples shows that selecting metal chlorides at appropriate carbonization temperatures or times achieves the best electromagnetic interference shielding effect. This is due to the catalytic protection effect of chlorides and the high-temperature carbonization process in air atmosphere, which forms a stable, high-temperature resistant conductive carbon layer, thereby improving the material's fire resistance and electromagnetic shielding performance. Specifically, chlorides decompose and catalytically protect the fabric carbonization under high-temperature conditions, while simultaneously optimizing the microstructure of the carbon layer, improving conductivity and stability, resulting in the optimal electromagnetic interference shielding effect. Comparative analysis shows that unloaded pure cotton fabrics, non-metallic chlorides (such as ammonium chloride), and low-content char-forming coatings cannot achieve fabric carbonization in a high-temperature air atmosphere; therefore, the loading amount of the char-forming coating is crucial.

[0051] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

Claims

1. A method for preparing carbonized fabric, characterized in that, It includes the following steps: S1. Modify cellulose-based textiles with a charcoal coating; the charcoal coating is one or more of cobalt chloride hexahydrate, ferric chloride hexahydrate, nickel chloride hexahydrate, aluminum chloride hexahydrate, chromium chloride hexahydrate, strontium chloride hexahydrate, and calcium chloride hexahydrate; the density of the charcoal coating on the textile is 5-20 mg / cm². 2.S2, The cellulose-based fabric treated with the carbonization coating in S1 is calcined and carbonized in an air atmosphere.

3. The method according to claim 1, characterized in that, The cellulose-based textiles are one or more of pure cotton, linen, and ramie.

4. The method according to claim 1, characterized in that, In step S2, the finishing method is one or more of spraying, padding, and soaking.

5. The method according to claim 1, characterized in that: In step S3, the calcination method is one or more of the following: muffle furnace, blowtorch, and tube furnace.

6. The method according to claim 1, characterized in that: In step S3, the calcination temperature is 800℃-1300℃.

7. The method according to claim 6, characterized in that: The calcination time is 3-30 minutes.

8. A conductive carbon fabric prepared by the method according to any one of claims 1-6.

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