A method for producing a multifunctional protective fabric with low infrared emissivity

Abstract

The application discloses a preparation method of multifunctional protective fabric with low infrared emissivity, which uses aminated cotton fabric as a substrate, modifies MXene with chlorogenic acid, enhances the oxidation resistance of MXene and enriches the functional groups on the surface of MXene, and then sprays the modified MXene@CGA nanosheet on the surface of the aminated cotton fabric through electrostatic interaction; meanwhile, silver nanoparticles are loaded on the MXene@CGA nanosheet by using chemical silver plating technology to form a stable conductive network. The method has the advantages of simple process, environmental protection and the like, and the coated fabric has excellent electromagnetic interference shielding and joule heating performance, and has a low infrared emissivity, and the infrared emissivity in the 8-14 mu m wave band range can be as low as 0.458.

Description

Technical Field

[0001] This invention relates to a method for preparing a multifunctional textile, and more particularly to a method for preparing a multifunctional protective fabric with low infrared emissivity. Background Technology

[0002] With the advancement of modern technology, infrared stealth technology, especially the development of low-infrared emissivity fabrics, has become an important research direction in many fields such as stealth camouflage and thermal management in recent years. By reducing the infrared emissivity of fabrics, the probability of being detected by infrared detectors can be effectively reduced, thus showing broad prospects in applications such as drone stealth and wilderness survival. Infrared stealth fabrics, through specific material design, can effectively shield infrared radiation in the mid-infrared (3-5μm) and far-infrared (8-14μm) bands, thereby achieving an "invisibility" effect. According to Stefan Boltzmann's law: E = εσT 4 (where E is the infrared radiation energy of the object; σ is the Boltzmann constant; ε is the infrared emissivity of the object; and T is the absolute temperature of the object). Infrared stealth can be achieved through two approaches: first, reducing the infrared emissivity of the target; and second, controlling the surface temperature to reduce the target's emissivity. Therefore, combining materials with low infrared emissivity and temperature-controlled materials can effectively reduce the infrared radiation energy of the target.

[0003] To achieve this goal, researchers in related fields have proposed various technical solutions, mainly focusing on using metals, conductive non-metals, metamaterials, etc., and employing techniques such as magnetron sputtering and coatings to reduce the infrared emissivity of fabrics. However, the inherent rigidity of the materials leads to a reduction in the fabric's inherent softness and comfort. Simultaneously, the binders, additives, and other auxiliaries added to the coatings have high infrared emissivity, affecting the overall stealth performance of the coating. Commonly used temperature-controlling materials in existing technologies include hollow fibers, hollow glass microspheres, aerogels, and phase change microcapsules; however, the complex manufacturing processes and high equipment requirements of these materials limit their widespread application.

[0004] Therefore, how to better integrate low infrared emissivity materials with fabrics without affecting the properties of the fabric itself has become a challenge. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a method for preparing a multifunctional protective fabric with low infrared emissivity, which not only retains the softness of the fabric itself, but also significantly reduces the infrared emissivity of the fabric.

[0006] Technical solution: The preparation method of the multifunctional protective fabric with low infrared emissivity according to the present invention includes the following steps:

[0007] (1) Preparation of aminated modified cotton fabric;

[0008] (2) Chlorogenic acid solution and MXene dispersion were mixed at a mass ratio to carry out a hybridization reaction. After the reaction was completed, MXene@CGA dispersion was obtained.

[0009] (3) Spray the MXene@CGA dispersion onto the surface of the aminated modified cotton fabric, wash, and dry;

[0010] (4) The dried fabric is immersed in silver ammonia solution, the fabric is taken out and placed in the reducing solution for shaking reaction. After the reaction is completed, the fabric is taken out, washed and dried to obtain MXene@CGA / Ag NPs coated fabric.

[0011] In step (2), the concentration of chlorogenic acid solution is 5~10 mg / mL.

[0012] In step (2), the mass ratio of MXene dispersion to chlorogenic acid solution is 2-4:1.

[0013] In step (3), the amount of MXene@CGA dispersion used is 5~10mL.

[0014] In step (4), the concentration of the silver ammonia solution is 10~20g / L.

[0015] In step (4), the reducing solution includes glucose and anhydrous ethanol, and the mass ratio of glucose to anhydrous ethanol is 1:2~6.

[0016] In step (2), the preparation method of MXene dispersion is as follows: LiF is added to hydrochloric acid solution, and then Ti3AlC2 is slowly added. After the reaction is completed, the solution is washed until pH > 6, centrifuged, washed, and the upper turbid liquid is MXene.

[0017] The preparation method of step (1) is as follows: the cotton fabric is activated by immersing it in an alkaline solution, taken out and washed until neutral, the cotton fabric is immersed in NaIO4 solution and reacted at 50~70℃ for 3~5h to obtain oxidized cotton fabric, after washing, the oxidized cotton fabric is immersed in ethylenediamine solution and reacted at 30~50℃ for 6~10h; after the reaction is completed, it is washed and dried to obtain aminated modified cotton fabric.

[0018] The concentration of the NaIO4 solution is 1~5 g / L; the concentration of the ethylenediamine solution is 5~10 g / L.

[0019] Invention Principle: The phenolic hydroxyl groups of chlorogenic acid molecules form Ti-OC covalent bonds with Ti atoms on the MXene surface, achieving stable grafting. This not only inhibits MXene oxidation by scavenging reactive oxygen species but also prevents MXene lamellar aggregation and improves dispersion stability through steric hindrance. Simultaneously, -OH and -COOH functional groups are introduced into MXene, enabling strong electrostatic adsorption with aminated cotton fabrics and providing uniform nucleation sites for silver nanoparticles. Based on this, MXene@CGA and silver nanoparticles are uniformly deposited on the fabric surface through electrostatic self-assembly and chemical silver plating. The infrared emissivity of the fabric is effectively reduced by utilizing the multilayer interfacial reflection of MXene and the localized surface plasmon resonance effect of silver nanoparticles.

[0020] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0021] (1) This invention uses electrostatic self-assembly to uniformly deposit MXene@CGA dispersion on the surface of aminated modified cotton fabric. Due to the rich functional groups of MXene@CGA nanosheets, a large number of adhesion sites are provided for chemical silver plating. The conductive network constructed between the two endows the fabric with excellent conductivity. This method is simple and not only preserves the softness of the fabric itself, but also significantly reduces the infrared emissivity of the fabric. (2) This application utilizes the metallic conductivity of MXene. Its two-dimensional sheet structure forms a continuous conductive network on the fabric surface, which reflects infrared waves through free electron oscillation, thereby reducing the infrared emissivity. At the same time, the rich functional groups of chlorogenic acid-modified MXene, such as -OH, -COOH, and -O, provide uniform anchor points for Ag NPs and avoid agglomeration. The MXene sheets and Ag NPs form a "conductive bridge" to enhance the overall conductivity. Since Ag NPs have extremely high carrier density, their plasma frequency is much higher than that of the infrared band, thus further suppressing thermal radiation. The assembled fabric exhibits high conductivity (603.28 S / m), low infrared emissivity (0.458), excellent electromagnetic interference shielding performance (75 dB) in the X-band, and outstanding Joule heating performance, reaching 114.14 °C when a 4 V voltage is applied. (3) The fabric prepared in this application achieves directional alignment of nanosheets through electrostatic adsorption without the use of adhesives, forming a dense coating layer and avoiding the accumulation defects of traditional coating processes. Furthermore, the chemical silver plating process is mild and causes little damage to the fibers. Therefore, this method has the advantages of simple operation and environmental friendliness. Attached Figure Description

[0022] Figure 1 A schematic diagram of the assembly mechanism of MXene@CGA / Ag NPs coated fabric;

[0023] Figure 2SEM images of the fabrics prepared in Comparative Examples 1, 2 and Examples 1-4 of the present invention: (a) Comparative Example 1; (b) Comparative Example 2; (c) Example 1; (d) Example 2; (e) Example 3; (f) Example 4;

[0024] Figure 3 FTIR images (a) of chlorogenic acid-modified Mxene in Examples 1-4 and Comparative Examples 2 and 3, and FTIR images (b) of aminated modified cotton fabrics in Examples 1-4 and Comparative Examples 1-5.

[0025] Figure 4 The XRD patterns are of the fabrics prepared in Comparative Examples 1 and 2 and Examples 1-4 of the present invention.

[0026] Figure 5 The time-temperature curves of the fabrics prepared in Examples 1-4 of this invention under a 3V voltage are shown.

[0027] Figure 6 The electromagnetic shielding effectiveness of the fabrics prepared in Comparative Examples 1, 2 and Examples 1-4 of the present invention in the X-band range;

[0028] Figure 7 The infrared emissivity of the fabrics prepared in Comparative Examples 1, 2 and Examples 1-4 of the present invention in the 3-14 μm wavelength range;

[0029] Figure 8 Infrared thermographs of the fabrics prepared for Comparative Example 1 and Example 4 of the present invention covering a human hand and a ceramic cup containing hot water. Detailed Implementation

[0030] The present invention will now be described in further detail.

[0031] Example 1

[0032] A method for preparing a multifunctional protective fabric with low infrared emissivity includes the following steps:

[0033] (1) Preparation of aminated modified cotton fabric: A 5cm×5cm piece of cotton fabric was immersed in a 10g / L NaOH solution for 2h to activate it. Then it was taken out and rinsed with deionized water until neutral. After that, the cotton fabric was immersed in a 3g / L NaIO4 solution and reacted at 60℃ for 4h to obtain oxidized cotton fabric. The fabric was taken out and rinsed with deionized water to remove the residual NaIO4. Then the oxidized cotton fabric was immersed in an 8g / L ethylenediamine solution and reacted at 40℃ for 8h. After the reaction was completed, it was washed with deionized water and then dried in an oven at 60℃ for 12h to obtain aminated modified cotton fabric, denoted as ACF.

[0034] (2) Preparation of MXene dispersion: 2g LiF was added to 40mL of 9 mol / L hydrochloric acid solution and stirred at 40℃ for 30 min. Then 2g Ti3AlC2 was slowly added and stirred at 40℃ for 24 h. After the reaction was completed, the solution was washed with deionized water until the pH of the solution was 6.8. Then the supernatant was discarded by centrifugation. Then 80mL of deionized water was added and sonicated for 2 h. After sonication, the solution was centrifuged at 5000r / min for 10 min and the supernatant was discarded. Then 20mL of deionized water was added and centrifuged at 3500r / min for 5 min. The resulting upper turbid liquid was MXene.

[0035] (3) Preparation of chlorogenic acid modified MXene dispersion: 8 mg / mL chlorogenic acid (hereinafter referred to as CGA) solution and 8 mg / mL MXene dispersion were mixed at a mass ratio of 2:1 and the mixture was magnetically stirred at room temperature for 2 h for hybridization reaction. After the reaction was completed, the mixture was ultrasonically treated for 30 min to obtain MXene@CGA dispersion.

[0036] (4) Preparation of MXene@CGA / Ag NPs coated fabric: The MXene@CGA dispersion obtained in step (3) is uniformly sprayed onto the surface of the aminated modified cotton fabric using a spray gun. After washing and drying, the fabric is immersed in a silver ammonia solution with a concentration of 15 g / L for 2 h. Then the fabric is taken out and placed in 100 mL of reducing solution, which includes 2 g of glucose and 10 mL of anhydrous ethanol. The reaction is shaken at room temperature for 2 h. After the reaction is completed, the fabric is taken out and washed with deionized water. It is then dried in an oven at 40 °C for 4 h to obtain the MXene@CGA / Ag NPs coated fabric.

[0037] Example 2

[0038] The difference between this embodiment and embodiment 1 is that the operation in step (4) is repeated twice, while the remaining steps are the same as in embodiment 1.

[0039] Example 3

[0040] The difference between this embodiment and embodiment 1 is that the operation in step (4) is repeated 3 times, while the remaining steps are the same as in embodiment 1.

[0041] Example 4

[0042] The difference between this embodiment and embodiment 1 is that the operation in step (4) is repeated 4 times, while the remaining steps are the same as in embodiment 1.

[0043] Comparative Example 1

[0044] The difference between Comparative Example 1 and Example 1 is that no coating treatment was performed; it was used only as a blank control fabric. The remaining steps were the same as in Example 1.

[0045] Comparative Example 2

[0046] The difference between Comparative Example 2 and Example 4 is that no chemical silver plating was performed, while the remaining steps were the same as in Example 4.

[0047] Comparative Example 3

[0048] The difference between Comparative Example 3 and Example 4 is that chemical silver plating was not performed, but polyaniline loading was performed instead: the MXene@CGA coated fabric was immersed in a mixed solution of 0.2 mol / L aniline and 1 mol / L hydrochloric acid, pre-soaked at 0-5°C for 30 min, and then ammonium persulfate solution was added dropwise for oxidative polymerization for 4 h to complete the polyaniline loading. The remaining steps were the same as in Example 4.

[0049] Comparative Example 4

[0050] The difference between Comparative Example 4 and Example 4 is that citric acid was used to replace chlorogenic acid in an equal amount to modify MXene, while the other steps were the same as in Example 4.

[0051] Comparative Example 5

[0052] The difference between Comparative Example 5 and Example 4 is that chlorogenic acid was not used to modify MXene, and pure MXene dispersion was used directly. The remaining steps are the same as in Example 4.

[0053] Table 1 Performance Comparison of Various Samples

[0054]

[0055] Comparing the performance of each embodiment and comparative example in Table 1, it can be seen that as the number of coating layers increases, the infrared emissivity of Examples 1 to 4 gradually decreases from 0.58 to 0.46, while the electromagnetic shielding effectiveness, conductivity, and Joule heating temperature increase simultaneously. Example 4, with four coating layers, exhibits the best overall performance: infrared emissivity of 0.46, electromagnetic shielding of 75 dB, conductivity of 603.28 S / m, and heating temperature of 80.26 ℃. Comparative Example 1, with its blank fabric, has an infrared emissivity as high as 0.82, near-zero electromagnetic shielding, and conductivity of less than 1 S / m, showing no electrothermal effect. Comparative Example 2, without silver plating, has an infrared emissivity of 0.62, electromagnetic shielding of 16 dB, conductivity of 246.37 S / m, and Joule temperature of 27.63 ℃. At ℃, the performance significantly decreased; Comparative Example 3, which replaced silver with polyaniline, showed lower performance across all indicators than Example 4, failing to replace silver in constructing a high-performance composite network; Comparative Example 4, which replaced chlorogenic acid with citric acid, exhibited poorer dispersion and loading effects, resulting in significant performance degradation; Comparative Example 5, without chlorogenic acid modification, showed MXene agglomeration, uneven silver loading, an infrared emissivity of 0.72, and a substantial decrease in shielding and conductivity. In summary, chlorogenic acid modification, silver nanoparticle loading, and an appropriate number of coating layers are the core keys to achieving low infrared emissivity, high electromagnetic shielding, high conductivity, and excellent Joule heating performance in fabrics.

[0056] Figure 1 This diagram illustrates the assembly mechanism of MXene@CGA / Ag NPs coated fabric. It shows how positively charged -NH2 groups are grafted onto the surface of the amino-modified cotton fabric, adsorbing negatively charged MXene@CGA nanosheets via electrostatic interactions. Chlorogenic acid is stably grafted onto the MXene surface through Ti-OC covalent bonds, inhibiting its oxidative aggregation and providing uniform nucleation sites for silver nanoparticles. The in-situ loaded silver nanoparticles bridge adjacent MXene sheets, constructing a continuous and dense conductive network, ultimately achieving the fabric's comprehensive properties of low infrared emissivity, high electromagnetic shielding, high conductivity, and excellent Joule heating performance.

[0057] Figure 2 In the figures, a~f correspond to the SEM images of the fabrics prepared in Comparative Examples 1 and 2 and Examples 1~4, respectively. As can be seen from the figures, the aminated modified cotton fabric prepared in Comparative Example 1 was not damaged and retained the original morphology and structure of the cotton fabric; the coated fabric prepared in Comparative Example 2 had MXene@CGA nanosheets uniformly deposited on its surface; and the coated fabrics prepared in Examples 1~4 had a continuous conductive network constructed from MXene@CGA nanosheets and silver nanoparticles deposited on their surface.

[0058] Figure 3 Figure a in the figure is the infrared spectrum of the powder obtained after drying the chlorogenic acid-modified Mxene dispersion prepared in step (3) of Examples 1-4 and Comparative Examples 2 and 3, at 815 cm⁻¹.-1 977 cm -1 1266 cm -1 The presence of distinct characteristic peaks at the point corresponds to the out-of-plane bending vibration of CH and the stretching vibration of CO, indicating that chlorogenic acid and MXene are successfully bonded. This confirms the successful modification of MXene nanosheets by chlorogenic acid and provides a basis for subsequent assembly and silver plating. Figure 3 Figure b in the figure shows the infrared spectra of the aminated modified cotton fabrics prepared in step (1) of Examples 1-4 and Comparative Examples 1-5. It can be seen that at 1651 cm⁻¹... -1 The characteristic peak at the point corresponds to the tensile vibration of C=N, indicating that the cotton fiber and ethylenediamine are linked through a Schiff base reaction, confirming that the cotton fabric has been successfully modified by amination.

[0059] Figure 4 The XRD pattern results showed that the coated fabric prepared in Comparative Example 2 exhibited Ti3C2T at 2θ = 6.91°. x The diffraction peaks of MXene at the (002) crystal plane. Meanwhile, the diffraction peaks of the coated fabrics prepared in Examples 1-4 at 2θ = 37.3°, 43.5°, 63.7°, 76.7° and 80.9° are the face-centered cubic crystal planes (111), (200), (220), (311) and (222) of Ag NPs, confirming that Ag NPs were successfully deposited on the surface of cotton fabric by chemical silver plating.

[0060] Figure 5 The electrothermal properties of the coated fabrics prepared in Examples 1-4 of this invention are shown. With a safe voltage of 3V applied to both ends of the fabric, the coated fabric prepared in Example 4 can reach a saturation temperature of 79.64°C, which is attributed to its excellent electrical conductivity and is expected to be a candidate for active radiative heating textiles.

[0061] Figure 6 This demonstrates the electromagnetic shielding effectiveness of the coated fabrics prepared in Comparative Examples 1 and 2 and Examples 1-4 of this invention in the X-band range, i.e., 8.2 GHz-12.4 GHz. Due to the high conductivity of MXene and Ag NPs, they construct a conductive network on the fabric surface, endowing the fabric with excellent conductivity and thus giving it outstanding electromagnetic interference shielding performance. Therefore, the coated fabric prepared in Example 4 exhibits excellent electromagnetic protection performance, with EMI SE... T =75dB.

[0062] Depend on Figure 7 It can be seen that as the number of coating layers increases, the infrared emissivity of the fabric decreases significantly. In particular, the infrared emissivity of the coated fabric prepared in Example 4 is as low as 0.458 in the 8~14μm band. Figure 8Figures a and b in the figure show infrared thermal images of the fabrics prepared in Comparative Example 1 and Example 4 covering the palm of a human hand and the outer wall of a ceramic cup filled with hot water, respectively. It can be clearly seen that the surface temperature of the fabric in Example 4 is much lower than that of the fabric in Comparative Example 1, and is closer to the background temperature, indicating that the coated fabric prepared in Example 4 has excellent camouflage ability against heat sources.

Claims

1. A method for preparing a multifunctional protective fabric with low infrared emissivity, characterized in that, Includes the following steps: (1) Preparation of aminated modified cotton fabric; (2) Chlorogenic acid solution and MXene dispersion were mixed at a mass ratio to carry out a hybridization reaction. After the reaction was completed, MXene@CGA dispersion was obtained. (3) Spray the MXene@CGA dispersion onto the surface of the aminated modified cotton fabric, wash, and dry; (4) The dried fabric is immersed in silver ammonia solution, the fabric is taken out and placed in the reducing solution for shaking reaction. After the reaction is completed, the fabric is taken out, washed and dried to obtain MXene@CGA / Ag NPs coated fabric.

2. The method for preparing the multifunctional protective fabric with low infrared emissivity according to claim 1, characterized in that, The concentration of chlorogenic acid solution in step (2) is 5~10 mg / mL.

3. The method for preparing the multifunctional protective fabric with low infrared emissivity according to claim 1, characterized in that, In step (2), the mass ratio of MXene dispersion to chlorogenic acid solution is 2-4:

1.

4. The method for preparing the multifunctional protective fabric with low infrared emissivity according to claim 1, characterized in that, In step (3), the amount of MXene@CGA dispersion used is 5~10mL.

5. The method for preparing the multifunctional protective fabric with low infrared emissivity according to claim 1, characterized in that, The concentration of the silver ammonia solution in step (4) is 10~20g / L.

6. The method for preparing the multifunctional protective fabric with low infrared emissivity according to claim 1, characterized in that, In step (4), the reducing solution includes glucose and anhydrous ethanol, and the mass ratio of glucose to anhydrous ethanol is 1:2~6.

7. The method for preparing the multifunctional protective fabric with low infrared emissivity according to claim 1, characterized in that, In step (2), the preparation method of MXene dispersion is as follows: LiF is added to hydrochloric acid solution, and then Ti3AlC2 is slowly added. After the reaction is completed, the solution is washed until pH > 6, centrifuged, washed, and the upper turbid liquid is MXene.

8. The method for preparing the multifunctional protective fabric with low infrared emissivity according to claim 1, characterized in that, The preparation method of step (1) is as follows: the cotton fabric is activated by immersing it in an alkaline solution, taken out and washed until neutral, the cotton fabric is immersed in NaIO4 solution and reacted at 50~70℃ for 3~5h to obtain oxidized cotton fabric, after washing, the oxidized cotton fabric is immersed in ethylenediamine solution and reacted at 30~50℃ for 6~10h; after the reaction is completed, it is washed and dried to obtain aminated modified cotton fabric.

9. The method for preparing the multifunctional protective fabric with low infrared emissivity according to claim 8, characterized in that, The concentration of the NaIO4 solution is 1~5 g / L; the concentration of the ethylenediamine solution is 5~10 g / L.

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