Functional fabric with both electromagnetic shielding and microwave absorption and preparation method thereof

Abstract

This application provides a functional fabric that combines electromagnetic shielding and microwave absorption, and its preparation method, belonging to the field of functional textile technology. The fiber cross-section of the functional fabric is composed, from the inside out, of a core fiber layer, a conductive reflective layer, a microwave absorption layer, and an impedance matching layer. This application effectively integrates a multi-level impedance gradient structure with a fiber structure, achieving efficient expression of electromagnetic shielding and microwave absorption performance in the fiber morphology, while also retaining the flexibility and breathability of the fabric substrate. It has broad application prospects in both civilian and military fields.

Description

Technical Field

[0001] The present application relates to a functional fabric having both electromagnetic shielding and microwave absorption and a preparation method thereof, belonging to the technical field of functional textiles. Background Art

[0002] With the rapid development of electronic information technology, a growing number of household electrical appliances and electronic communications products are increasingly becoming smaller, more high-frequency, and more power-efficient, with a high degree of integration. Infrastructure such as 5G base stations, substations, and various electromagnetic equipment are becoming increasingly important to production and daily life. However, while these facilities bring significant convenience to people's lives, they also deteriorate the surrounding electromagnetic environment, severely impacting human health and the proper functioning of high-precision instruments. Once attacked by electromagnetic weapons, command and communication systems will be completely paralyzed. To enhance the survivability of military targets and the penetration capability of weapon systems, electromagnetic shielding technology is becoming increasingly important. Electromagnetic functional fabrics offer properties such as softness, breathability, lightness, washability, foldability, and ease of processing. They can be customized into electromagnetic radiation protective clothing, electromagnetic shielding curtains, electromagnetic shielding tents, and weapon covers, making them the preferred electromagnetic shielding material for both military and civilian applications.

[0003] The electromagnetic functional fabrics currently available on the market mainly include metal fiber blended / blended fabrics (such as CN1045428A and CN1718889A) and metal-coated fabrics (such as CN1621603A and CN103061114A). These products have excellent electrical conductivity and electromagnetic shielding properties, but they mainly reflect electromagnetic waves through the high electrical conductivity of metal materials, which can easily cause secondary electromagnetic radiation pollution and is difficult to apply to specific application scenarios such as military electromagnetic stealth. Absorbent electromagnetic shielding fabrics, also known as absorbing fabrics, can convert electromagnetic energy into heat energy and are the most effective means to solve the problem of secondary electromagnetic radiation pollution. Currently, absorbing fabrics are mainly made by coating absorbers with fabric substrates, such as absorbing electromagnetic shielding fabrics (CN113622187A) and magnetic absorbing fabrics (CN108951192A). This method can effectively absorb electromagnetic waves of different frequency bands by controlling the filler content and thickness of the coating. However, the existing absorbers are all nano-micro powders, which are very easy to agglomerate and settle in the adhesive, making it difficult to form a continuous absorbing layer. In addition, problems such as high absorber filling density, high coating thickness, stiff feel of the coated fabric and poor adhesion have also limited the further development of this type of absorbing fabric.

[0004] Electromagnetic shielding and microwave absorption are two distinct properties. Existing electromagnetic shielding technology primarily utilizes the material's high electrical conductivity to reflect electromagnetic waves, preventing them from entering the material's interior. Microwave absorption, on the other hand, minimizes surface reflection of electromagnetic waves and dissipates them internally. These two properties conflict in material design. For example, fabrics with effective electromagnetic shielding properties often have high electrical conductivity and low skin depth, with reflection being the primary shielding mechanism. Absorbent fabrics, on the other hand, require good impedance matching and electromagnetic loss characteristics. Their poor electrical conductivity results in low electromagnetic shielding performance, making them difficult to meet the requirements of military applications or high-performance electromagnetic shielding (>60dB). In recent years, researchers have demonstrated that impedance gradient structures can provide ideal low reflectivity and high shielding effectiveness. Attempts have been made to construct such structures to achieve both electromagnetic shielding and microwave absorption (e.g., CN113121982A, CN111138706A, and CN115500067A). However, gradient structures typically require considerable thickness, making them incompatible with thin fabrics, especially fibers. Therefore, how to integrate efficient electromagnetic shielding and microwave absorption properties on fabrics remains a daunting challenge. Summary of the Invention

[0005] In view of this, the present application first provides a method for preparing a functional fabric with both electromagnetic shielding and microwave absorption. The preparation process is simple and is not limited by the type of fabric substrate. The obtained electromagnetic functional fiber fabric not only has high-efficiency electromagnetic shielding and microwave absorption properties, but also better retains the flexibility and air permeability of the fabric substrate.

[0006] Specifically, this application is implemented through the following solutions:

[0007] A method for preparing a functional fabric with both electromagnetic shielding and microwave absorption, comprising the following steps:

[0008] Step 1: Fabric surface pretreatment:

[0009] The surface of the fabric substrate is etched with plasma to remove impurities on the fabric surface and introduce oxygen-containing groups. After the treatment, the fabric is taken out and immediately immersed in an aqueous solution containing reactive molecules. After the reaction is completed, the fabric is taken out, washed and dried to obtain a surface-pretreated fabric substrate.

[0010] Step 2: Constructing a conductive reflective layer:

[0011] The fabric surface-pretreated in step 1 is immersed in a palladium chloride solution for activation, removed, washed, and dried, and then placed in a metal plating solution at a bath ratio of 20 to 50:1 at 25 to 85° C. for chemical plating for 20 to 60 minutes. The fabric is removed, washed, and dried to obtain a high-conductivity metal-plated fabric having a conductive reflective layer. The metal in the metal plating solution is one or more of nickel, copper, tungsten, or cobalt.

[0012] Step 3: Construct the microwave absorption layer:

[0013] The fabric with the conductive reflective layer constructed in step 2 is immersed in a plating solution containing magnetic metal salts for chemical plating, with a bath ratio of 20 to 50:1 and a chemical plating temperature of 60 to 85° C. After treatment for 30 to 90 minutes, the fabric is taken out, washed and dried to obtain a magnetic nickel-cobalt-iron plated fabric with a microwave absorption layer constructed thereon, wherein the magnetic metal salts include three metals: nickel, cobalt and iron.

[0014] Step 4: Build the impedance matching layer:

[0015] The fabric with the conductive reflective layer and the microwave absorbing layer constructed in step 3 is immersed in a reaction solution containing a magnetic metal salt with a bath ratio of 20 to 50:1, and a hydrothermal reaction is carried out at 85 to 120°C for 4 to 8 hours; after the reaction is completed, it is taken out, washed with water, and dried, and after annealing treatment in an inert gas atmosphere, it is taken out, washed, and dried to obtain a functional fabric with both electromagnetic shielding and microwave absorption.

[0016] In the above preparation process, through specially designed fabric surface pretreatment, preparation of high-conductivity metal coating to construct a conductive reflective layer, preparation of magnetic nickel-cobalt-iron coating to construct a microwave absorption layer, and preparation of magnetic metal oxide coating to construct an impedance matching layer, the multi-level impedance gradient structure is effectively integrated with the fiber structure, thereby obtaining a functional fabric including a conductive reflective layer (high-conductivity metal coating), a microwave absorption layer (nickel-cobalt-iron coating) and an impedance matching layer (magnetic metal oxide coating). This functional fabric has both electromagnetic shielding and microwave absorption functions.

[0017] Furthermore, as a preference:

[0018] In step one,

[0019] The fabric substrate is a general fiber fabric, such as cotton, polyester, nylon, aramid, polyimide, carbon fiber, etc.

[0020] The etching process comprises placing the fabric in a plasma etching chamber, wherein the atmosphere is air or oxygen, the discharge power is 50 to 400 W, the stabilization time is 5 to 10 seconds, the discharge time is 60 to 300 seconds, and the etching times are 1 to 5 times.

[0021] The reactive molecules are silane coupling agents (amino, mercapto, hydroxyl), polyethyleneimine, dopamine or ethylenediaminetetraacetic acid. The fabric is immersed in an aqueous solution containing the reactive molecules for 0.5 to 2 hours, with a bath ratio of 20 to 50:1.

[0022] The concentration of the palladium chloride solution is 0.05-0.5 g / L, and the activation time is 5-30 minutes.

[0023] The washing step comprises washing the fabric with deionized water for 1 to 3 times.

[0024] The drying temperature is 60-120° C., and the drying time is 5-30 minutes.

[0025] In step 2,

[0026] The fabric is washed with deionized water 1 to 3 times after activation, and the drying temperature is 60 to 90° C. and the drying time is 30 to 60 minutes.

[0027] The metal plating solution comprises a metal salt, a reducing agent, a stabilizer and deionized water:

[0028] The metal salt is one or more of nitrate, sulfate and chloride, and the concentration of the metal salt is 2 to 50 g / L;

[0029] The reducing agent is one or more of glucose, sodium hypophosphite, formaldehyde, anhydrous ethanol, and boric acid, and the reducing agent concentration is 1 to 100 g / L;

[0030] The stabilizer is one or more of sodium citrate, potassium sodium tartrate, and sodium edetate, and the concentration of the stabilizer is 5 to 50 g / L.

[0031] The fabric is washed with deionized water 1 to 3 times after chemical plating, and the drying temperature is 60 to 80° C. and the drying time is 5 to 30 minutes.

[0032] In step three,

[0033] The plating solution containing magnetic metal salt includes magnetic metal salt, reducing agent, stabilizer, ammonia water and deionized water:

[0034] The magnetic metal salt is one or more of sulfate, nitrate, and chloride of the corresponding magnetic metal, with a concentration of 5 to 30 g / L;

[0035] The reducing agent is sodium hypophosphite with a concentration of 10 to 60 g / L;

[0036] The stabilizer is one or more of sodium citrate, sodium acetate, and potassium sodium tartrate, with a concentration of 10 to 60 g / L;

[0037] The ammonia water has a concentration of 50-100 g / L and a pH value of 8-10.

[0038] The washing step comprises washing the fabric with deionized water for 1 to 3 times.

[0039] The drying temperature is 60-80° C., and the drying time is 5-30 minutes.

[0040] In step four,

[0041] The reaction solution includes magnetic metal salt, ammonium fluoride, ethanol, urea and deionized water:

[0042] The magnetic metal salt is two or three of nickel salt, cobalt salt and iron salt: the nickel salt is nickel nitrate with a concentration of 0.5-20 g / L; the cobalt salt is cobalt nitrate with a concentration of 0.5-20 g / L; the iron salt is one or more of ferrous nitrate, ferric nitrate, ferrous chloride and ferric chloride with a concentration of 0.5-50 g / L;

[0043] The concentration of ammonium fluoride is 0.5 to 8 g / L;

[0044] Ethanol concentration is 20-100 mL / L;

[0045] The urea concentration is 2-30 g / L.

[0046] After the hydrothermal reaction, the fabric is washed with deionized water for 1 to 3 times and then vacuum dried at a temperature of 60 to 80° C. for 30 to 90 minutes.

[0047] The inert gas is nitrogen or argon, the annealing temperature is 130-200° C., and the annealing time is 3-12 hours.

[0048] The second purpose of the applicant is to provide a functional fiber with both electromagnetic shielding and microwave absorption. The functional fiber consists of a core fiber, a conductive reflective layer, a microwave absorption layer and an impedance matching layer from the inside to the outside. The functional fiber of this structure can be prepared by the above method.

[0049] The third purpose of the applicant is to provide a functional fabric with both electromagnetic shielding and microwave absorption, and the functional fabric is prepared by the above method.

[0050] The above solution solves the bottleneck problem that existing coating / plating technology has difficulty in achieving the integration of efficient electromagnetic shielding and microwave absorption properties on soft and thin fabrics. Using general fiber fabrics as the substrate, a specially designed metal chemical plating and metal oxide chemical growth method is used to construct a multi-layer electromagnetic functional structure with a gradient impedance on the surface of the textile fiber. By controlling the electromagnetic properties of the functional layers between the fiber surface layers, the surface impedance, microwave attenuation and shielding reflection / absorption performance are balanced, and the "absorption-reflection-reabsorption" process of electromagnetic waves is constructed to reduce the reflection of electromagnetic waves on the fabric surface, thereby achieving both efficient electromagnetic shielding and microwave absorption. Therefore, the working principle of this application is summarized as follows:

[0051] (1) The fabric substrate is pretreated by plasma etching and surface modification methods to construct a large number of functional groups on the surface of the textile fibers, thereby chelating and adsorbing catalytic metal ions, providing anchoring points for the subsequent construction of catalytic centers and chemical plating; at the same time, it helps to enhance the interfacial bonding between the metal coating and the fiber, and improve functional stability.

[0052] (2) A specially designed internal high-conductivity metal plating layer and an intermediate conductive and magnetic plating layer are sequentially constructed on the fiber surface by chemical plating. The internal high-conductivity metal plating layer mainly shields electromagnetic waves by reflection, giving the fabric high-efficiency electromagnetic shielding performance; the intermediate conductive and magnetic metal plating layer will enhance the electromagnetic properties of the fabric and improve the absorption (dielectric-magnetic) loss of electromagnetic waves.

[0053] (3) A hydrothermal method is used to grow a magnetic metal oxide with a specific three-dimensional structure on the outer layer of the fiber to balance the surface impedance and provide a magnetic loss and scattering interface, thereby reducing the surface reflection of electromagnetic waves while enhancing the magnetic loss performance.

[0054] Compared with the prior art, the beneficial effects of this application are summarized as follows:

[0055] (1) The present invention effectively integrates a multi-level impedance gradient structure with a fiber structure through a specially designed metal chemical plating and metal oxide chemical growth method, and can prepare functional fibers and functional fabrics that have both electromagnetic shielding and microwave absorption, including a conductive reflective layer (high conductivity metal plating), a microwave absorption layer (nickel-cobalt-iron plating) and an impedance matching layer (magnetic metal oxide layer).

[0056] (2) The present invention can balance the surface impedance, microwave attenuation and shielding reflection / absorption performance by adjusting the electromagnetic properties of the functional layer on the fiber surface, forming an "introduction-absorption-reflection-reabsorption" loss process of electromagnetic waves in the radial direction of the fiber, while reducing the surface reflection of electromagnetic waves and enhancing the absorption performance of electromagnetic waves; then, combined with the porous and interwoven structural characteristics of the fabric substrate, finally achieves efficient expression of electromagnetic shielding and microwave absorption performance in the fiber morphology.

[0057] (3) The functional fabric prepared by the present invention not only retains the flexibility and shape adaptability of the fabric substrate, but also has efficient electromagnetic shielding and microwave absorption properties. The electromagnetic shielding efficiency is as high as 60dB and the minimum reflection loss value is less than -10dB.

[0058] (4) The preparation method of the present invention is simple and can be produced continuously. The developed functional fabric can be cut and processed into electromagnetic protective clothing, shielding tents, weapon covering cloth, etc. for special occasions, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0060] Figure 1 This is a process flow chart for preparing the functional fabric of the present invention;

[0061] Figure 2 Scanning electron micrographs of PET (a), Ni-Cu@PET (b), Ni-Co-Fe@Ni-Cu@PET (c), and CoFe2O4@Ni-Co-Fe@Ni-Cu@PET (d) fabrics in Example 1;

[0062] Figure 3 This is the energy spectrum of the CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric in Example 1;

[0063] Figure 4 (a) in Example 1 is the electromagnetic shielding performance diagram of CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric, and (b) in Example 1 is the wave absorption effect diagram of CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric. DETAILED DESCRIPTION

[0064] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the technical solutions in the embodiments of this application will be further described in detail below in conjunction with the drawings in the embodiments of this application. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit the technical solutions of this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of this application.

[0065] In the following examples, the fabric substrates used were all provided by Sanyuan Holding Group Co., Ltd., and the chemical reagents used (such as nickel sulfate, cobalt sulfate, copper sulfate, ammonium ferrous sulfate, palladium chloride, sodium hypophosphite, potassium sodium tartrate, sodium citrate, ammonium sulfate, ammonia water, cobalt nitrate, ferric chloride, etc.) were purchased from Sinopharm Group. All reagents were of analytical grade and did not require further purification during use.

[0066] Example 1

[0067] This embodiment provides a functional fabric with both electromagnetic shielding and microwave absorption, with polyester fiber fabric as the base material, recorded as CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric, combined with Figure 1 , the preparation process is as follows:

[0068] (1) Fabric surface pretreatment:

[0069] Cut the polyester fabric into 10×10cm pieces 2 The sample was then placed in a plasma etching chamber, and the plasma equipment parameters were set (air atmosphere, discharge power of 300W, stabilization time of 5s, and discharge time of 200s). The etching number was set to 2 times. After the treatment was completed, the fabric was removed and immediately immersed in an aqueous solution containing polyethyleneimine molecules (2.5wt%) for 1 hour, with a bath ratio of 20:1. The fabric was removed and washed three times with deionized water, and finally dried in a vacuum oven at 60°C for 30 minutes to obtain the surface-pretreated polyester fiber fabric.

[0070] (2) Preparation of Ni-Cu@PET fabric:

[0071] The polyester fiber fabric with the above surface pretreatment was immersed in a 0.5 g / L hydrochloric acid and palladium chloride solution for 30 minutes, removed and washed with deionized water, and then dried in a vacuum oven at 60°C for 30 minutes to obtain a palladium-activated polyester fiber fabric. The fabric was then immersed in a nickel-copper electroless plating solution (10 g / L nickel sulfate, 2 g / L copper sulfate, 15 g / L sodium hypophosphite, 10 g / L sodium citrate, and 10 g / L sodium acetate) for plating at a bath ratio of 30:1, a plating temperature of 80°C, and a plating time of 30 minutes. The pH value of the plating solution was adjusted to 7.5 with ammonia water. After the reaction was completed, the fabric was removed and washed with deionized water three times, and then dried in a vacuum oven at 65°C for 10 minutes. A high-conductivity metal coating was constructed on the fiber surface of the fabric. The fabric at this time was recorded as: Ni-Cu@PET fabric.

[0072] (3) Preparation of Ni-Co-Fe@Ni-Cu@PET fabric:

[0073] The Ni-Cu@PET fabric was immersed in a metal plating solution containing magnetic nickel, cobalt, and iron metal salts (19.6 g / L ammonium ferrous sulfate, 14.6 g / L cobalt sulfate, 14.4 g / L nickel sulfate, 26.5 g / L sodium hypophosphite, and 50 g / L potassium sodium tartrate) for chemical plating. The bath ratio was 50:1, the plating temperature was 75°C, the plating time was 60 min, and the pH value of the plating solution was adjusted to around 9 with ammonia water. After the reaction was completed, the fabric was taken out and washed three times with deionized water, and then dried in a vacuum oven at 60°C for 20 min. A magnetic nickel-cobalt-iron coating was constructed on the surface of the conductive metal coating. The fabric at this time was recorded as Ni-Co-Fe@Ni-Cu@PET fabric.

[0074] (4) Preparation of CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric:

[0075] The above-mentioned Ni-Co-Fe@Ni-Cu@PET fabric was immersed in a hydrothermal reaction solution containing 11.6 g / L cobalt nitrate, 21.6 g / L ferric chloride, 1.0 g / L ammonium fluoride, 15 g / L urea and 25 mL / L anhydrous ethanol at room temperature for 2 hours, and then hydrothermally reacted at 90°C for 6 hours; after the reaction was completed, the fabric was taken out and washed with deionized water 3 times, and placed in a vacuum oven at 60°C for 10 minutes; then it was placed in a nitrogen atmosphere and annealed at 120°C for 6 hours. The magnetic metal oxide was constructed on the surface of the magnetic nickel-cobalt-iron coating. The fabric at this time was recorded as CoFe2O4@Ni-Co-Fe@Ni-Cu@PET and sample 1#. The cross-section of the fabric fiber is shown in FIG. Figure 1 As shown: it includes an impedance matching layer i, a microwave absorption layer ii, a conductive reflection layer iii and a core fiber iv.

[0076] Scanning electron microscope (SU3800) was used to observe the changes in the surface morphology of polyester fibers. Figure 2 As shown. It can be found that polyester fiber ( Figure 2 a) in the figure has a smooth surface, a diameter of about 10 μm, and pores between fibers; after electroless nickel-copper plating ( Figure 2 b), the surface of the polyester fiber changed significantly, the nickel-copper coating was evenly wrapped on the fiber surface, and the fiber diameter increased slightly; after further nickel-cobalt-iron plating ( Figure 2 c), the fiber diameter increases, and large granular nickel-cobalt-iron deposits appear on the fiber surface; after hydrothermal loading of magnetic cobalt ferrite ( Figure 2 In (d), the fiber surface morphology changes significantly, and magnetic cobalt ferrite with a needle-like three-dimensional structure is deposited on the fiber surface and shows good uniformity. At this time, the fiber diameter reaches about 12 to 15 μm.

[0077] EDS (Quanta250) was used to test the element distribution on the surface of CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fiber. Figure 3 It can be seen that the fiber surface contains Cu, Ni, Co, and Fe elements, and they are evenly distributed.

[0078] The S parameters, relative complex permittivity and magnetic permeability of the fabric were tested by the waveguide method using a vector network analyzer (N5232B), and the electromagnetic shielding effectiveness (SE) and reflection loss (RL) values ​​were calculated based on these. The results are shown in Figure 2. Figure 4 Studies have shown that the average electromagnetic shielding effectiveness of 0.5mm thick CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric in the frequency range of 8.2 to 12.4GHz reaches 67.08dB, which can effectively shield 99.99998% of electromagnetic waves, meeting the basic requirements of military electromagnetic shielding (>60dB), but its reflection shielding effectiveness (SE R ) is only 0.29dB, which has obvious "low reflection, high shielding" characteristics; more importantly, the prepared CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric has a minimum reflection loss value (RL min ) reaches -12.50dB, indicating that it can effectively absorb more than 90% of the incident electromagnetic waves. The above results also fully demonstrate that the fabric prepared by this method has excellent electromagnetic shielding and microwave absorption properties.

[0079] Example 2

[0080] The configuration of this embodiment is the same as that of embodiment 1, except that the nickel-copper electroless plating solution in step (2) is adjusted to a nickel electroless plating solution (10 g / L nickel sulfate, 15 g / L sodium hypophosphite, 10 g / L sodium citrate, 10 g / L sodium acetate). The prepared CoFe2O4@Ni-Co-Fe@Ni@PET fabric is designated as sample 2#.

[0081] Example 3

[0082] The configuration of this embodiment is the same as that of embodiment 1, except that the nickel-copper electroless plating solution in step (2) is adjusted to a nickel-tungsten electroless plating solution (10 g / L nickel sulfate, 5 g / L sodium tungstate, 15 g / L sodium hypophosphite, 10 g / L sodium citrate, 10 g / L sodium acetate). The prepared CoFe2O4@Ni-Co-Fe@Ni-W@PET fabric is designated as sample #3.

[0083] Example 4

[0084] The configuration of this embodiment is the same as that of embodiment 1, except that the hydrothermal reaction solution in step (4) is adjusted to 11.6 g / L nickel nitrate, 21.6 g / L ferric chloride, 1.0 g / L ammonium fluoride, 15 g / L urea, and 25 mL / L anhydrous ethanol. The prepared NiFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric is designated as sample 4#.

[0085] Example 5

[0086] The configuration of this embodiment is the same as that of embodiment 1, except that the hydrothermal reaction solution in step (4) is adjusted to 11.6 g / L nickel nitrate, 23.3 g / L cobalt nitrate, 1.0 g / L ammonium fluoride, 15 g / L urea, and 25 mL / L anhydrous ethanol. The prepared NiCo2O4@Ni-Co-Fe@Ni-Cu@PET fabric is designated as sample 5#.

[0087] Example 6

[0088] The configuration of this embodiment is the same as that of embodiment 1, except that the hydrothermal reaction solution in step (4) is adjusted to 7.92 g / L ferrous chloride, 21.6 g / L ferric chloride, 1.0 g / L ammonium fluoride, 15 g / L urea, and 25 mL / L anhydrous ethanol. The prepared Fe3O4@Ni-Co-Fe@Ni-Cu@PET fabric is designated as sample 6#.

[0089] Example 7

[0090] The configuration of this embodiment is the same as that of embodiment 1, except that the polyester fiber fabric substrate is changed to a cotton fiber fabric (CF) substrate, and the prepared CoFe2O4@Ni-Co-Fe@Ni-Cu@CF fabric is designated as sample 7#.

[0091] Example 8

[0092] The configuration of this embodiment is the same as that of embodiment 1, except that the polyester fiber fabric substrate is changed to an aramid fiber fabric (AF) substrate, the annealing temperature in step (4) is adjusted to 200°C and the time is 6 h, and the prepared CoFe2O4@Ni-Co-Fe@Ni-Cu@AF fabric is recorded as sample 8#.

[0093] The electromagnetic functional fiber fabric prepared in the above embodiment was tested for electromagnetic shielding and microwave absorption performance, and the air permeability of the fabric was tested (RT5300B fabric air permeability tester) in accordance with GB / T5453-1997 "Determination of Air Permeability of Textile Fabrics". The specific results are shown in Table 1.

[0094] Table 1: Electromagnetic shielding performance, microwave absorption performance and air permeability of samples 1-8#

[0095]

[0096] The above cases show that the eight electromagnetic functional fiber fabrics prepared in this application all have good electromagnetic shielding performance, with shielding effectiveness values ​​higher than 55dB; samples 1#, 2#, 3#, and 8# exhibit microwave absorption capabilities above -10dB, and the microwave absorption performance of other samples is poor.

[0097] In this study, polyester fabric was used as the substrate. Examples 1, 2, and 3 varied the conductivity of the fiber's inner layer by adjusting the type of high-conductivity metal coating (nickel-copper, nickel, or nickel-tungsten). The effects of the conductive reflective layer on the fabric's electromagnetic shielding and microwave absorption properties were investigated. The results showed that the nickel-copper coating exhibited excellent conductivity, with the resulting Ni-Cu@PET fabric achieving a conductivity exceeding ~4200 S / m. Consequently, the CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric exhibited an excellent electromagnetic shielding effectiveness (EMI) of 67.08 dB. In comparison, the conductivity of the nickel and nickel-tungsten coatings decreased slightly, reaching ~3150 S / m and 3540 S / m, respectively. Consequently, the EMI performance of the CoFe2O4@Ni-Co-Fe@Ni@PET and CoFe2O4@Ni-Co-Fe@Ni-W@PET fabrics decreased slightly. Since the middle microwave absorption layer and the outer impedance matching layer in samples 1#, 2# and 3# are consistent, all three fabrics show good microwave absorption effect, and the minimum reflection loss is less than -10dB.

[0098] Using a nickel-copper alloy as the inner conductive reflective layer and a nickel-cobalt-iron intermediate microwave absorption layer, Examples 1, 4, 5, and 6 altered the impedance matching properties of the fabric by adjusting the type of magnetic metal oxide in the fiber's outer layer (CoFe2O4, NiFe2O4, NiCo2O4, or Fe3O4). The results showed that the magnetic metal oxide in the outer fiber layer had little effect on the fabric's electromagnetic shielding performance, but directly affected its reflective shielding effectiveness and microwave absorption properties. The magnetic Fe3O4 layer struggled to form an effective impedance matching layer on the fiber surface, causing significant electromagnetic wave reflection from the Fe3O4@Ni-Co-Fe@Ni-Cu@PET fabric. Consequently, its reflective shielding effectiveness was high, but its microwave absorption performance was poor. The functional fabric provided in Example 1 exhibited the highest electromagnetic shielding effectiveness, with a microwave absorption rate exceeding 90%, demonstrating its high practicality.

[0099] Compared to traditional metallized fabrics (such as CN1621603A and CN103061114A), the electromagnetic functional fiber fabric developed by the present invention, which includes a conductive reflective layer (high-conductivity metal plating), a microwave absorbing layer (nickel-cobalt-iron plating), and an impedance matching layer (magnetic metal oxide layer), has "low reflection and high shielding" characteristics, and has a significant wave absorption effect, which can effectively solve the problem of electromagnetic wave secondary pollution. Compared with coated absorbing fabrics (such as CN113622187A and CN108951192A), the electromagnetic functional fiber fabric preparation method provided by the present invention effectively integrates a multi-level impedance gradient structure with the fiber structure, achieving efficient expression of electromagnetic shielding and microwave absorption performance in the fiber morphology, and better retaining the softness and breathability of the fabric substrate (retention rate >60%).

[0100] In addition, the electromagnetic functional fiber fabrics prepared in Examples 7 and 8, respectively, use cotton fiber fabric and aramid fiber fabric as substrates, and still maintain relatively high electromagnetic shielding and microwave absorption properties. This result shows that the preparation method of the electromagnetic functional fiber fabric provided by the present invention is universal, is not limited by the type of fabric substrate, and has broad application prospects and huge market value.

[0101] The above-described embodiments merely represent several feasible implementation methods of the present invention. The description thereof is relatively specific and detailed, but it should not be understood as limiting the scope of the invention. The embodiments are not intended to limit the scope of protection in the claims of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention. Any equivalent implementation or modification that does not depart from the scope of the present invention should be included in the technology of the present invention.

Claims

1. A method for preparing a functional fabric having both electromagnetic shielding and microwave absorption, characterized in that: Here are the steps: Step 1: Fabric surface pretreatment: The surface of the fabric substrate is etched with plasma to remove impurities on the fabric surface and introduce oxygen-containing groups. After the treatment, the fabric is taken out and immediately immersed in an aqueous solution containing reactive molecules. After the reaction is completed, the fabric is taken out, washed and dried to obtain a surface-pretreated fabric substrate. The reactive molecule is a silane coupling agent, polyethyleneimine, dopamine or ethylenediaminetetraacetic acid, and the fabric is immersed in an aqueous solution containing the reactive molecule for 0.5 to 2 hours, with a bath ratio of 20 to 50:1; Step 2: Construct a conductive reflective layer: The surface-pretreated fabric is immersed in a palladium chloride solution for activation, removed, washed, and dried, and then the activated fabric is placed in a metal plating solution with a bath ratio of 20 to 50:1 and subjected to chemical plating at 25 to 85° C. for 20 to 60 minutes. The fabric is removed, washed, and dried to obtain a fabric having a conductive reflective layer, wherein the metal in the metal plating solution is one or more of nickel, copper, tungsten, or cobalt; Step 3: Construct the microwave absorption layer: The fabric having the conductive reflective layer is immersed in a plating solution containing a magnetic metal salt for chemical plating at a bath ratio of 20 to 50:1 and a temperature of 60 to 85° C. After treatment for 30 to 90 minutes, the fabric is taken out, washed, and dried to obtain a fabric having the conductive reflective layer and the microwave absorbing layer, wherein the metals in the magnetic metal salt include nickel, cobalt, and iron; Step 4: Build the impedance matching layer: The fabric constructed with a conductive reflective layer and a microwave absorbing layer is immersed in a reaction solution containing a magnetic metal salt with a bath ratio of 20-50:1, and a hydrothermal reaction is carried out at 85-120°C for 4-8 hours. After the reaction is completed, the fabric is taken out, washed with water, and dried. After annealing treatment in an inert gas atmosphere, the fabric is taken out, washed, and dried to obtain a functional fabric with both electromagnetic shielding and microwave absorption.

2. The method for preparing a functional fabric having both electromagnetic shielding and microwave absorption according to claim 1, characterized in that: In step 1, the etching treatment is as follows: placing the fabric in a plasma etching chamber, the atmosphere is air or oxygen, the discharge power is 50~400 W, the stabilization time is 5~10 s, the discharge time is 60~300 s, and the etching times are 1~5 times.

3. The method for preparing a functional fabric having both electromagnetic shielding and microwave absorption properties according to claim 1, wherein: The concentration of the palladium chloride solution is 0.05-0.5 g / L, and the activation time is 5-30 min.

4. The method for preparing a functional fabric having both electromagnetic shielding and microwave absorption according to claim 1, characterized in that: In step 2, the metal plating solution has a pH value of 7 to 8 and contains a metal salt, a reducing agent, a stabilizer, a pH regulator and deionized water; The metal salt is one or more of nitrate, sulfate and chloride, and the concentration of the metal salt is 2-50 g / L; The reducing agent is one or more of glucose, sodium hypophosphite, formaldehyde, anhydrous ethanol, and boric acid, and the reducing agent concentration is 1-100 g / L; The stabilizer is one or more of sodium citrate, potassium sodium tartrate, and sodium edetate, and the stabilizer concentration is 5-50 g / L.

5. The method for preparing a functional fabric having both electromagnetic shielding and microwave absorption according to claim 1, characterized in that: In step 3, the plating solution containing the magnetic metal salt has a pH value of 8 to 10 and includes the magnetic metal salt, a reducing agent, a stabilizer, ammonia water and deionized water; The magnetic metal salt is one or more of sulfate, nitrate, and chloride, with a concentration of 5 to 30 g / L; The reducing agent is sodium hypophosphite with a concentration of 10-60 g / L; The stabilizer is one or more of sodium citrate, sodium acetate, and potassium sodium tartrate, with a concentration of 10-60 g / L; The concentration of the ammonia water is 50-100 g / L.

6. The method for preparing a functional fabric having both electromagnetic shielding and microwave absorption according to claim 1, characterized in that: In step 4, the reaction solution includes a magnetic metal salt, ammonium fluoride, ethanol, urea and deionized water; The magnetic metal salt is two or three of nickel salt, cobalt salt and iron salt: the nickel salt is nickel nitrate with a concentration of 0.5-20 g / L; the cobalt salt is cobalt nitrate with a concentration of 0.5-20 g / L; the iron salt is one or more of ferrous nitrate, ferric nitrate, ferrous chloride and ferric chloride with a concentration of 0.5-50 g / L; The concentration of ammonium fluoride is 0.5-8 g / L; Ethanol concentration is 20-100 mL / L; The urea concentration is 2~30 g / L.

7. The method for preparing a functional fabric having both electromagnetic shielding and microwave absorption according to claim 1, characterized in that: In step 4, the inert gas is nitrogen or argon, the annealing temperature is 130-200° C., and the annealing time is 3-12 h.

8. A functional fabric with both electromagnetic shielding and microwave absorption properties prepared by the method of claim 1, characterized in that: On the fiber cross section of the functional fabric, from the inside out, there are core fiber, conductive reflective layer, microwave absorption layer and impedance matching layer.

9. The functional fabric having both electromagnetic shielding and microwave absorption properties according to claim 8, characterized in that: The core layer fiber is any one of cotton, polyester, nylon, aramid, polyimide, and carbon fiber.

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