A waste biomass material-based flame-retardant fire-resistant electromagnetic shielding carbon composite material and a preparation method thereof

Abstract

The present application relates to the technical field of flame-retardant electromagnetic shielding materials, and discloses a flame-retardant fire-resistant electromagnetic shielding carbon composite material based on waste biomass materials and a preparation method thereof, which comprises the following steps: S1, mixing an intumescent flame retardant with waste biomass materials, adding water and performing ultrasonic dispersion, loading the obtained mixed solution on a fabric by means of spraying, and then drying to obtain a modified fabric-based composite material; S2, clamping the modified fabric-based composite material prepared in S1 between two quartz plates, and carbonizing together to obtain a flame-retardant fire-resistant electromagnetic shielding carbon composite material. The carbon fabric-based composite material is prepared quickly and efficiently by taking the intumescent flame retardant and the waste biomass materials as raw materials, compared with traditional carbonized materials, the preparation steps are simple, there is no requirement for inert gas, and the carbon fabric-based composite material has good flame-retardant performance and can maintain good electromagnetic shielding performance in a flame environment.

Description

Technical Field

[0001] This invention belongs to the technical field of flame-retardant electromagnetic shielding materials, and more specifically relates to a flame-retardant and fire-resistant electromagnetic shielding carbon composite material based on waste biomass materials and its preparation method. Background Technology

[0002] As electronic devices become increasingly miniaturized and complex, electromagnetic interference (EMI) issues are becoming more prominent in various fields, including consumer electronics, medical technology, and the automotive industry. EMI shielding textiles, characterized by their softness and lightweight properties, are widely used in flexible wearable devices and sensors. However, the complexity of the application environment, coupled with the inherent flammability of these textiles, has raised concerns about fire hazards. Zhang Sheng's team (Sustainable Materials and Technologies, 2024, 40, e00949) achieved an EMI shielding effect of 24 dB by alternately depositing MXene and polyphosphoramide on PA6 fibers, while simultaneously increasing the limiting oxygen index from 19% to 25.5%. However, the conductive network of these materials is damaged when exposed to flame, resulting in a loss of EMI shielding effectiveness. Therefore, developing flame-retardant EMI shielding textiles that can maintain their flame-retardant EMI shielding effect in fire conditions can effectively mitigate fire-related damage and protect the data integrity of internal electronic components and equipment.

[0003] Carbonized materials are lightweight, heat-resistant, and possess excellent electrical and thermal conductivity and chemical stability, making them widely used as conductive materials, refractory materials, and photothermal conversion materials. The team led by Kong Jie at Northwestern Polytechnical University (Carbon, 2024, 227, 119268) prepared carbonized wood by carbonizing phosphoric acid wood at 600℃ for 210 min in a nitrogen atmosphere, achieving an electromagnetic shielding effect of 52 dB while also exhibiting good flame retardant properties. The team led by Zhang Yingying at Tsinghua University (Advanced Functional Materials, 2017, 27(2), 1604795) prepared carbonized textiles with good electrical conductivity by carbonizing cotton fabric for 200 min in a mixed atmosphere of argon and hydrogen, which can be applied to high-sensitivity wearable sensors. However, this traditional method of preparing carbonized materials requires high temperature and inert gas conditions, resulting in long preparation times and high energy consumption. Therefore, exploring rapid preparation methods for carbonized materials in an air atmosphere is of great significance.

[0004] Biomass materials are a widely available carbon source in nature, mainly composed of cellulose, hemicellulose, and lignin. During pyrolysis, organic matter decomposes to form stable carbon. However, in industrial production and daily life, a large amount of biomass materials are discarded during processing, such as bamboo powder, rice husks, and coffee grounds, which is inconsistent with current energy conservation and emission reduction policies. Therefore, developing rapid, environmentally friendly, and efficient methods for preparing highly effective flame-retardant and durable electromagnetic shielding carbon-based composite materials from waste biomass materials is of significant research importance. Summary of the Invention

[0005] The main objective of this invention is to address the aforementioned problems by providing a flame-retardant and fire-resistant electromagnetic shielding carbon composite material based on waste biomass materials and its preparation method. By using an intumescent flame retardant (IFR) to provide a slightly inert atmosphere, and by introducing waste biomass materials to increase the overall carbon content, the integrated preparation of high-temperature rapid flame-retardant electromagnetic shielding materials is achieved. Furthermore, the raw materials are readily available, low-carbon, energy-saving, and fast and efficient.

[0006] The core idea of ​​this invention is to use an IFR composed of ammonium polyphosphate, melamine, and urea. Ammonium polyphosphate, as an acid source, generates acidic substances such as phosphoric acid to promote carbonization of the matrix. Melamine, as a carbon source, forms a dense carbon layer through its own carbonization during pyrolysis. Urea, as an acid source, generates ammonia during pyrolysis, creating a slightly inert atmosphere and facilitating the formation of an expandable carbon layer. These three components work synergistically in a specific ratio to form a uniform and stable carbon layer while maintaining the integrity of the internal structure. Waste biomass materials often have a high carbon content and are renewable. Their synergistic addition with the IFR effectively increases the carbon source content during carbonization, contributing to the formation of a thicker and stronger carbon layer. Simultaneously, integrated molding quickly and efficiently yields a high-carbon-content carbon fabric composite material with high overall fire resistance and good electromagnetic shielding durability.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] One of the technical solutions of this invention: a method for preparing a flame-retardant and fire-resistant electromagnetic shielding carbon composite material based on waste biomass materials, comprising the following steps:

[0009] S1. Mix the intumescent flame retardant with waste biomass material, add water and ultrasonically disperse the mixture. The resulting mixture is then sprayed onto the fabric and dried to obtain the modified fabric-based composite material.

[0010] S2. The modified fabric-based composite material prepared in S1 is sandwiched between two quartz plates and carbonized together to obtain a flame-retardant and fire-resistant electromagnetic shielding carbon composite material.

[0011] More preferably, in step S1, the intumescent flame retardant is a compound of ammonium polyphosphate, melamine, and urea.

[0012] More preferably, in step S1, the intumescent flame retardant contains ammonium polyphosphate at 50-90% of the total flame retardant mass, melamine at 5-30% of the total flame retardant mass, and urea at 5-20% of the total flame retardant mass.

[0013] More preferably, in step S1, the average molecular weight of the ammonium polyphosphate is >1000.

[0014] More preferably, in step S1, the areal density of the intumescent flame retardant loaded on the fabric is 5-25 mg / cm³. 2 More preferably, in step S1, the areal density of the intumescent flame retardant loaded on the fabric is 10-25 mg / cm³. 2 .

[0015] More preferably, in step S1, the areal density of the waste biomass material loaded on the fabric is 2-30 mg / cm³. 2 .

[0016] More preferably, in step S1, the areal density of the waste biomass material loaded on the fabric is 10-30 mg / cm³. 2 .

[0017] More preferably, in step S1, the ratio of the areal density of the intumescent flame retardant to that of the waste biomass material is 0.5-3:1.

[0018] More preferably, in step S1, the waste biomass material is one or more of the following: sawdust, rice husks, bamboo powder, coconut shells, sugarcane bagasse, and coffee grounds.

[0019] More preferably, in step S1, the drying is performed at a temperature of 50-70°C.

[0020] More preferably, in step S2, the carbonization atmosphere is an air atmosphere.

[0021] More preferably, in step S2, the carbonization temperature is 500-1200℃ and the carbonization time is 5-30 min.

[0022] The second technical solution of the present invention: a flame-retardant and fire-resistant electromagnetic shielding composite material prepared by the above preparation method.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) Compared with the preparation of traditional carbon fabric matrix composites, the carbonization atmosphere of the carbon fabric matrix composites prepared in this invention is simply air atmosphere.

[0025] (2) Compared with the preparation of traditional carbon fabric matrix composites, the carbon fabric matrix composites prepared by the present invention are prepared in an integrated and rapid manner, with low carbonization temperature and short time.

[0026] (3) Compared with traditional electromagnetic shielding materials, the carbon fabric-based composite material prepared by the present invention has good flame retardant properties while maintaining good electromagnetic shielding performance in a flame environment.

[0027] (4) This invention rapidly and efficiently prepares carbon fabric-based composite materials using intumescent flame retardants and waste biomass materials as raw materials. Compared with the preparation of traditional carbonized materials, it has simpler steps, no inert gas requirements, higher yield, readily available raw materials, lower cost, and can be mass-produced and used. At the same time, the carbon fabric-based composite materials prepared through integrated carbonization have good flame-retardant and electromagnetic shielding properties, and can be widely used in fields such as communications, electromagnetic protection, and aerospace, with excellent application value. Attached Figure Description

[0028] Figure 1 The combustion of the flame-retardant and fire-resistant electromagnetic shielding carbon composite material of this invention under an alcohol lamp is shown.

[0029] Figure 2 The conductivity and electromagnetic shielding properties of the IFR-Cot-W sample are shown in the following figures: (a) Initial conductivity of the IFR-Cot-W sample; (b) Initial electromagnetic shielding properties of the IFR-Cot-W sample; (c) Conductivity of the IFR-Cot-W sample after exposure to flame; (d) Electromagnetic shielding properties of the IFR-Cot-W sample after exposure to flame.

[0030] Figure 3 The conductivity and electromagnetic shielding properties of IFR-Cot-C samples are shown below: (a) Initial conductivity of IFR-Cot-C samples; (b) Initial electromagnetic shielding properties of IFR-Cot-C samples; (c) Conductivity of IFR-Cot-C samples after exposure to flame; (d) Electromagnetic shielding properties of IFR-Cot-C samples after exposure to flame.

[0031] Figure 4 The electrical conductivity and electromagnetic shielding performance of the IFR-Cot-B sample are shown in the following figures: (a) Initial electrical conductivity of the IFR-Cot-B sample; (b) Initial electromagnetic shielding performance of the IFR-Cot-B sample; (c) Electrical conductivity of the IFR-Cot-B sample after exposure to flame; (d) Electromagnetic shielding performance of the IFR-Cot-B sample after exposure to flame. Detailed Implementation

[0032] The following examples further illustrate the above-described content of the present invention, but it should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention.

[0033] Example 1

[0034] S1. An IFR (Integrated Fluorescent Refrigerant) was prepared by mixing 70 wt% ammonium polyphosphate, 20 wt% melamine, and 10 wt% urea with waste wood chips. The mixture was then diluted with deionized water and ultrasonically dispersed until homogeneous. The resulting mixture was then sprayed onto a fabric, with the areal density of the IFR on the fabric controlled at 10 mg / cm³. 2 The areal densities of the waste biomass materials were 10, 15, and 20 mg / cm³, respectively. 2 Then it is dried in a 60℃ oven.

[0035] S2. The modified fabric-based composite material prepared above was placed between two quartz plates and carbonized in a muffle furnace at 700℃ for 20 minutes in an air atmosphere to obtain the flame-retardant and fire-resistant electromagnetic shielding carbon composite material IFR-Cot-W. Table 1 shows the preparation parameters of IFR-Cot-W.

[0036] To characterize its electromagnetic shielding performance, flame retardant 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; an alcohol lamp burning test was conducted to test its flame retardant performance; and its conductivity and electromagnetic shielding performance after exposure to flame were also tested.

[0037] Table 1. Preparation parameters of IFR-Cot-W

[0038]

[0039] Example 2

[0040] S1. An IFR (Integrated Fluorescent Refrigerant) was composed of 75 wt% ammonium polyphosphate, 16 wt% melamine, and 9 wt% urea, and mixed with waste coffee grounds. The mixture was then diluted with deionized water and ultrasonically dispersed until homogeneous. The resulting mixture was then sprayed onto a fabric, with the areal density of the IFR on the fabric controlled at 10 mg / cm³. 2 The areal densities of the waste biomass materials were 10, 15, and 20 mg / cm³, respectively. 2 Then it is dried in a 65℃ oven.

[0041] S2. The modified fabric-based composite material prepared above was placed between two quartz plates and carbonized in a muffle furnace at 1000℃ for 10 minutes in an air atmosphere to obtain the flame-retardant and fire-resistant electromagnetic shielding carbon composite material IFR-Cot-C. Table 2 shows the preparation parameters of IFR-Cot-C.

[0042] To characterize its electromagnetic shielding performance, flame retardant 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; an alcohol lamp burning test was conducted to test its flame retardant performance; and its conductivity and electromagnetic shielding performance after exposure to flame were also tested.

[0043] Table 2. Preparation parameters of IFR-Cot-C

[0044]

[0045] Example 3

[0046] S1. An IFR (Integrated Fluorescent Resin) was composed of 75 wt% ammonium polyphosphate, 16 wt% melamine, and 9 wt% urea, and mixed with waste bamboo powder. The mixture was then diluted with deionized water and ultrasonically dispersed until homogeneous. The resulting mixture was then sprayed onto a fabric, with the areal density of the IFR on the fabric controlled at 10 mg / cm³. 2 The areal densities of the waste biomass materials were 10, 15, and 20 mg / cm³, respectively. 2 Then it is dried in a 70℃ oven.

[0047] S2. The modified fabric-based composite material prepared above was placed between two quartz plates and carbonized in a muffle furnace at 900℃ for 15 minutes in an air atmosphere to obtain the flame-retardant and fire-resistant electromagnetic shielding carbon composite material IFR-Cot-B. Table 3 shows the preparation parameters of IFR-Cot-B.

[0048] To characterize its electromagnetic shielding performance, flame retardant 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; an alcohol lamp burning test was conducted to test its flame retardant performance; and its conductivity and electromagnetic shielding performance after exposure to flame were also tested.

[0049] Table 3. Preparation parameters of IFR-Cot-B

[0050]

[0051] Example 4

[0052] S1. An IFR (Integrated Fluorescent Resin) was composed of 75 wt% ammonium polyphosphate, 16 wt% melamine, and 9 wt% urea, and mixed with waste bamboo powder. The mixture was then diluted with deionized water and ultrasonically dispersed until homogeneous. The resulting mixture was then sprayed onto a fabric, with the areal density of the IFR on the fabric controlled at 5 mg / cm³. 2 10mg / cm 2 15mg / cm 2 20mg / cm 2 The areal density of the waste biomass materials is 10 mg / cm³.2 Then it is dried in a 70℃ oven.

[0053] S2. The modified fabric-based composite material prepared above was placed between two quartz plates and carbonized in a muffle furnace at 900℃ for 15 minutes in an air atmosphere to obtain the flame-retardant and fire-resistant electromagnetic shielding carbon composite material IFR-n-Cot-B. Table 4 shows the preparation parameters of IFR-n-Cot-B.

[0054] To characterize its electromagnetic shielding performance, flame retardant 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; an alcohol lamp burning test was conducted to test its flame retardant performance; and its conductivity and electromagnetic shielding performance after exposure to flame were also tested.

[0055] Table 4. Preparation parameters of IFR-n-Cot-B

[0056]

[0057] Comparative Example 1

[0058] Pure cotton fabric was carbonized in a muffle furnace at 900℃ for 15 minutes between two quartz plates to prepare the carbon fabric-based composite material Pure-Cot.

[0059] Comparative Example 2

[0060] Using the IFR composition and parameters of Example 3, without adding waste biomass materials, and with other conditions kept exactly the same, carbon fabric-based composite material IFR-C was prepared.

[0061] Comparative Example 3

[0062] The IFR composition was selected to be only ammonium polyphosphate. Using the parameters and conditions of Example 3, without adding waste biomass materials, and with other conditions controlled to be exactly the same, the carbon fabric matrix composite material IFR-APP was prepared.

[0063] Comparative Example 4

[0064] The IFR composition was selected as 80wt% ammonium polyphosphate and 20wt% melamine. Using the parameters and conditions of Example 3, without adding waste biomass materials, and with other conditions controlled exactly the same, the carbon fabric matrix composite material IFR-APP-Melamine was prepared.

[0065] Comparative Example 5

[0066] The IFR composition was selected as 75 wt% ammonium sulfate, 16 wt% cellulose and 9 wt% sodium bicarbonate. The carbon fabric matrix composite material IFR2 was prepared by using the parameters and conditions of Example 3 and controlling other conditions to be exactly the same.

[0067] Comparative Example 6

[0068] Using the IFR composition and parameter conditions of Example 3, the areal density of waste bamboo powder was 50 mg / cm³. 2 The carbon fabric matrix composite material IFR-Cot-B-5 was prepared by controlling other conditions to have the areal density ratio of IFR to waste biomass material to be 1:5.

[0069] Table 5. Test results of electrical conductivity and electromagnetic shielding performance

[0070]

[0071]

[0072] Table 6. Test results of electrical conductivity and electromagnetic shielding performance after exposure to flame.

[0073]

[0074]

[0075] 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 composite material prepared by the present invention has good flame retardant properties. It does not exhibit shrinkage or flame spread under an alcohol lamp and maintains good morphological integrity, thus possessing excellent flame retardant properties.

[0076] like Figure 2 , 3 As shown in Figure 4, the conductivity of the sample before and after flame exposure indicates that the material has a low initial resistance and good conductivity. Furthermore, the conductivity increases with the increase in waste biomass loading. This is because waste biomass is mainly composed of cellulose and lignin, which forms graphite-like biochar during carbonization. The granular biochar also creates a more complete conductive network, improving electron conduction channels and thus enhancing conductivity. Higher conductivity also 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 and thus improving electromagnetic shielding performance. After flame exposure, the resistance change is small, and the overall electromagnetic shielding performance decreases slightly, but it still meets the commercial requirement of 20 dB, indicating that the material has good fire resistance stability.

[0077] As shown in Tables 5 and 6, comparative analysis revealed that the optimal electromagnetic interference (EMI) shielding effect is achieved when ammonium polyphosphate, melamine, and urea are used in combination according to the claims and in appropriate proportions with waste biomass materials. This is because the acid source in the intumescent flame retardant, ammonium polyphosphate, releases phosphoric acid and other substances during pyrolysis, catalyzing char formation. Melamine is an excellent carbon source, and urea, as a gas source, produces ammonia and other gases during pyrolysis, diluting the oxygen concentration and creating a slightly inert environment. The synergistic effect of these three substances, combined with an appropriate amount of waste biomass materials, maximizes char formation and achieves the best EMI shielding effect. Excessive load of waste biomass materials reduces the basic mechanical properties of the materials, leading to flaking and a decrease in EMI shielding effectiveness.

[0078] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a waste-biomass material based flame retardant fire resistant type electromagnetic shielding carbon composite material, characterized by, The method comprises the following steps: S1, mixing the intumescent flame retardant with the waste biomass material, adding water and performing ultrasonic dispersion, loading the obtained mixture on a fabric by spraying, and then drying to obtain a modified fabric-based composite material; S2, placing the modified fabric-based composite material prepared in S1 between two quartz plates and carbonizing together to obtain a flame-retardant and fire-resistant electromagnetic shielding carbon composite material.

2. The preparation method of the waste biomass material based flame retardant fire resistant type electromagnetic shielding carbon composite material according to claim 1, characterized in that, In step S1, the intumescent flame retardant is a mixture of ammonium polyphosphate, melamine and urea.

3. The preparation method of the waste biomass material based flame retardant fire resistant type electromagnetic shielding carbon composite material according to claim 2, characterized in that, In step S1, the ammonium polyphosphate in the intumescent flame retardant accounts for 50-90% of the total mass of the flame retardant, the melamine accounts for 5-30% of the total mass of the flame retardant, and the urea accounts for 5-20% of the total mass of the flame retardant.

4. The preparation method of the waste biomass material based flame retardant fire resistant type electromagnetic shielding carbon composite material according to claim 1, characterized in that, In step S1, the face density of the intumescent flame retardant loaded on the fabric is 5-25 mg / cm 2 .

5. The preparation method of the waste biomass material based flame retardant fire resistant type electromagnetic shielding carbon composite material according to claim 1, characterized in that, In step S1, the waste biomass material is loaded on the fabric with an areal density of 2-30 mg / cm 2 .

6. The method of producing a waste-biomass material based flame retardant fire resistant type electromagnetic shielding carbon composite material according to any one of claims 1 to 5, characterized by, In step S1, the ratio of the area density of the intumescent flame retardant to the waste biomass material is 0.5-3:

1.

7. The method of producing a waste-biomass material based flame retardant fire resistant type electromagnetic shielding carbon composite material according to any one of claims 1 to 5, characterized by, In step S1, the waste biomass material is one or more of wood chips, rice husk, bamboo powder, coconut shell, sugarcane residue and coffee residue.

8. The method of claim 1, wherein the preparation of the waste biomass material based flame retardant fire resistant type electromagnetic shielding carbon composite is characterized by, In step S2, the atmosphere for carbonization is an air atmosphere.

9. The preparation method of the flame-retardant fire-resistant type electromagnetic shielding carbon composite based on waste biomass material according to claim 1 or 8, characterized in that, In step S2, the carbonization temperature is 500-1200℃, and the carbonization time is 5-30 min.

10. The flame-retardant and fire-resistant electromagnetic shielding carbon composite material prepared by the method according to any one of claims 1-9.

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