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

Abstract

The invention provides a functional fabric with both electromagnetic shielding and microwave absorption and a preparation method thereof, and belongs to the technical field of functional textiles. A core layer fiber, a conductive reflecting layer, a microwave absorbing layer and an impedance matching layer are sequentially arranged on the fiber section of the functional fabric from inside to outside. The multi-level impedance gradient structure and the fiber structure are effectively fused, efficient expression of electromagnetic shielding and microwave absorption performance in the fiber form is achieved, the flexibility and air permeability of a fabric base material are well reserved, and the application prospect in the civil and military fields is wide.

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, various daily electrical appliances and electronic communication products are increasing, and are constantly developing in the direction of miniaturization, high frequency, high power and high integration. Infrastructure such as 5G base stations, substations and various electromagnetic equipment are also becoming more and more important to production and life. However, while these equipment and facilities bring great convenience to people's lives, they also cause the deterioration of the surrounding electromagnetic environment, seriously affecting human health and the normal operation of high-precision instruments. Once electromagnetic weapons are attacked by them, the command and communication system will be completely paralyzed. In order to improve the survivability of military targets and the penetration capability of weapon systems, the importance of electromagnetic shielding technology is becoming increasingly prominent. Electromagnetic functional fabrics have the characteristics of softness and breathability, gentleness and washability, foldability and easy processing. They can be made into electromagnetic radiation protective clothing, electromagnetic shielding curtains, electromagnetic shielding tents and weapon covering cloths according to needs. They are the preferred electromagnetic shielding materials for military and civilian use.

[0003] The electromagnetic functional fabrics currently 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 pollution of electromagnetic radiation and are difficult to apply to application scenarios with specific requirements such as military electromagnetic stealth. Absorption-type 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 pollution of electromagnetic radiation. At present, absorbing fabrics are mainly made by coating technology to combine 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. Problems such as high absorber filling density, high coating thickness, stiff feel of the coated fabric and poor adhesion also limit the further development of this type of absorbing fabric.

[0004] Electromagnetic shielding and microwave absorption are two completely different properties. The existing electromagnetic shielding technology mainly uses the high conductivity of the material to reflect electromagnetic waves and prevent electromagnetic waves from entering the material. However, microwave absorption is to reduce the surface reflection of electromagnetic waves as much as possible and lose electromagnetic waves inside the material. There is a contradiction between these two characteristics in material design. For example, fabrics with high-efficiency electromagnetic shielding characteristics often have high conductivity and low skin depth, and the shielding mechanism is mainly reflection. However, microwave-absorbing fabrics need to have good impedance matching and electromagnetic loss characteristics. Their conductivity is poor and their shielding performance for electromagnetic waves is low, which makes it difficult to meet the application requirements of military or high-performance electromagnetic shielding (>60dB). In recent years, researchers have shown that impedance gradient change structure can provide ideal low reflectivity and high shielding effect, and try to construct this structure to take into account electromagnetic shielding and microwave absorption characteristics (such as CN113121982A, CN111138706A and CN115500067A, etc.), but the gradient structure usually requires a high thickness, which is difficult to form a good compatibility effect 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, the present application is implemented through the following scheme:

[0007] A method for preparing a functional fabric having 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 by 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: construct a conductive reflective layer:

[0011] The fabric with the surface pretreatment in step 1 is immersed in a palladium chloride solution for activation, taken out, 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 chemically plated at 25 to 85° C. for 20 to 60 minutes, and the fabric is taken out, washed and dried to obtain a high-conductivity metal-plated fabric with a conductive reflective layer. The metal in the metal plating solution refers to 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 a magnetic metal salt for chemical plating, the bath ratio is 20 to 50:1, the chemical plating treatment temperature is 60 to 85°C, and after treatment for 30 to 90 minutes, it is taken out, washed and dried to obtain a magnetic nickel-cobalt-iron plated fabric with a microwave absorption layer, wherein the magnetic metal salt includes 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 absorption 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, 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), which has both electromagnetic shielding and microwave absorption functions.

[0017] Further, 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 treatment is as follows: placing the fabric in a plasma etching chamber, the atmosphere is air or oxygen, the discharge power is 50-400W, the stabilization time is 5-10s, the discharge time is 60-300s, and the etching times are 1-5 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 min.

[0023] The washing adopts deionized water to wash the fabric 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 activated fabric is washed 1 to 3 times with deionized water, 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, sodium potassium tartrate, and sodium ethylenediaminetetraacetate, and the stabilizer concentration is 5 to 50 g / L.

[0031] The washing after chemical plating uses deionized water to wash the fabric 1 to 3 times, 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 comprises 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 adopts deionized water to wash the fabric 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] The washing after the hydrothermal reaction is performed by washing the fabric with deionized water for 1 to 3 times and vacuum drying the fabric at a drying 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 scheme solves the bottleneck problem that the existing coating / plating technology is difficult to achieve the integration of efficient electromagnetic shielding and microwave absorption characteristics on soft and thin fabrics. It uses general fiber fabrics as the substrate and adopts a specially designed metal chemical plating and metal oxide chemical growth method to construct a multi-layer impedance gradient electromagnetic functional structure on the surface of textile fibers. 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 to construct the "absorption-reflection-reabsorption" process of electromagnetic waves, reduce the reflection of electromagnetic waves on the fabric surface, and thus achieve 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 textile fibers, which can chelate and adsorb catalytic metal ions and provide 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 coating and an intermediate conductive and magnetic coating are sequentially constructed on the fiber surface by chemical plating. The internal high-conductivity metal coating mainly shields electromagnetic waves by reflection, giving the fabric efficient electromagnetic shielding performance; the intermediate conductive and magnetic metal coating 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 the multi-level impedance gradient structure with the 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 layer), a microwave absorption layer (nickel-cobalt-iron plating layer) 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, thereby 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, the efficient expression of electromagnetic shielding and microwave absorption performance is achieved 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 performance. The electromagnetic shielding efficiency is as high as 60dB or more, 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 protection 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying any creative work.

[0060] Figure 1 is a process flow chart of the preparation of 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 clearer, 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 work are within the scope of protection of this application.

[0065] In the following embodiments, 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 is 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 2 The sample was then placed in a plasma etching chamber, and the plasma equipment parameters were set (the atmosphere was air, the discharge power was 300W; the stabilization time was 5s; the discharge time was 200s), and the etching times were 2 times. After the treatment was completed, the fabric was taken out and immediately immersed in an aqueous solution containing polyethyleneimine molecules (2.5wt%) for 1h, with a bath ratio of 20:1; the fabric was taken out, washed 3 times with deionized water, and finally dried in a 60°C vacuum oven for 30min to obtain a 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 0.5g / L hydrochloric acid·palladium chloride solution for 30 minutes, taken out 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; then it was immersed in a nickel-copper chemical plating solution (10g / L nickel sulfate, 2g / L copper sulfate, 15g / L sodium hypophosphite, 10g / L sodium citrate, 10g / L sodium acetate) for plating, the bath ratio was 30:1, the plating temperature was 80°C, the plating time was 30min, and the pH value of the plating solution was adjusted to 7.5 with ammonia water; after the reaction was completed, the fabric was taken out and washed with deionized water for 3 times, and then dried in a vacuum oven at 65°C for 10 minutes, and a high conductivity metal plating layer 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, 50 g / L potassium sodium tartrate) for chemical plating with a bath ratio of 50:1, a plating temperature of 75°C, a plating time of 60 min, and ammonia water was used to adjust the pH value of the plating solution to around 9. After the reaction was completed, the fabric was taken out and washed with deionized water for 3 times, 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 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 h, and then hydrothermally reacted at 90 ° C for 6 h; after the reaction, the fabric was taken out and washed with deionized water for 3 times, and dried in a 60 ° C vacuum oven for 10 min; then it was placed in a nitrogen atmosphere and annealed at 120 ° C for 6 h, and 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, recorded as sample 1#, and 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 microscopy (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 chemical nickel-copper plating ( Figure 2 b), the polyester fiber surface changes significantly, the nickel-copper coating is evenly wrapped on the fiber surface, and the fiber diameter increases slightly; after further nickel-cobalt-iron plating ( Figure 2 c), the fiber diameter increases, and large particles of nickel-cobalt-iron are deposited on the fiber surface; after the magnetic cobalt ferrite is loaded by the hydrothermal method ( 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 surface element distribution of CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fibers. 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) were calculated based on this. The results are shown in Figure 2. Figure 4 Studies have shown that the average electromagnetic shielding effectiveness of 0.5 mm thick CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric in the frequency range of 8.2 to 12.4 GHz reaches 67.08 dB, which can effectively shield 99.99998% of electromagnetic waves, meeting the basic requirements of military electromagnetic shielding (>60 dB), 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 case 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 chemical plating solution in step (2) is adjusted to a nickel chemical plating solution (10 g / L nickel sulfate, 15 g / L sodium hypophosphite, 10 g / L sodium citrate, 10 g / L sodium acetate), and the prepared CoFe2O4@Ni-Co-Fe@Ni@PET fabric is recorded 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 chemical plating solution in step (2) is adjusted to a nickel-tungsten chemical 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), and the prepared CoFe2O4@Ni-Co-Fe@Ni-W@PET fabric is recorded 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, and the prepared NiFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric is recorded 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, and the prepared NiCo2O4@Ni-Co-Fe@Ni-Cu@PET fabric is recorded 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, and the prepared Fe3O4@Ni-Co-Fe@Ni-Cu@PET fabric is recorded 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 adjusted to an aramid fiber fabric (AF) substrate, the annealing temperature in step (4) is adjusted to 200°C, and the time is 6 hours. 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) with reference to 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 performance 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 the present invention, polyester fiber fabric is used as the substrate, and examples 1, 2, and 3 change its conductivity (nickel-copper, nickel, nickel-tungsten) by adjusting the type of high-conductivity metal coating in the inner layer of the fiber, and study the effect of the conductive reflective layer on the electromagnetic shielding and microwave absorption performance of the fabric. The results show that the nickel-copper metal coating has good conductivity, and the conductivity of the prepared Ni-Cu@PET fabric reaches above 4200S / m, so the CoFe2O4@Ni-Co-Fe@Ni-Cu@PET fabric exhibits an excellent electromagnetic shielding effectiveness of 67.08dB; in comparison, the conductivity of the nickel metal coating and the nickel-tungsten metal coating is slightly reduced, which are 3150S / m and 3540S / m respectively, so the electromagnetic shielding effectiveness of CoFe2O4@Ni-Co-Fe@Ni@PET and CoFe2O4@Ni-Co-Fe@Ni-W@PET fabrics is slightly reduced. Since the middle microwave absorption layer and the outer impedance matching layer in samples 1#, 2# and 3# are consistent, the three fabrics all show good microwave absorption effect, and the minimum reflection loss is less than -10dB.

[0098] Using nickel-copper alloy as the internal conductive reflection layer and nickel-cobalt-iron as the intermediate microwave absorption layer, Examples 1, 4, 5, and 6 change the impedance matching characteristics of the fabric by adjusting the type of magnetic metal oxide on the outer layer of the fiber (CoFe2O4, NiFe2O4, NiCo2O4, Fe3O4). The research results show that the magnetic metal oxide on the outer layer of the fiber has little effect on the electromagnetic shielding performance of the fabric, but directly affects the reflection shielding effectiveness and microwave absorption performance of the fabric. Among them, it is difficult for magnetic Fe3O4 to form an effective impedance matching layer on the fiber surface, so that electromagnetic waves form a large amount of reflection on the surface of Fe3O4@Ni-Co-Fe@Ni-Cu@PET fabric, so its reflection shielding effectiveness is high and its microwave absorption performance is poor. Among them, the electromagnetic shielding effectiveness of the functional fabric provided in Example 1 is the highest, and the microwave absorption rate can reach more than 90%, which is more practical.

[0099] Compared with 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 absorption layer (nickel-cobalt-iron plating) and an impedance matching layer (magnetic metal oxide layer), has the characteristics of "low reflection and high shielding", and has a significant wave absorption effect, which can effectively solve the problem of electromagnetic wave secondary pollution. Compared with coated wave absorbing fabrics (such as CN113622187A and CN108951192A), the preparation method of electromagnetic functional fiber fabric provided by the present invention effectively integrates the multi-level impedance gradient structure with the fiber structure, realizes the efficient expression of electromagnetic shielding and microwave absorption performance in fiber morphology, and better retains the softness and air permeability 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. The results show 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-mentioned embodiments only express several feasible implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention, and the embodiments are not used to limit the scope of protection in the claims of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and all equivalent implementations or changes that do not depart from 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 by 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, and after the reaction is completed, the fabric is taken out, washed and dried to obtain a fabric substrate with a pre-treated surface; Step 2: construct a conductive reflective layer: The surface pretreated fabric is immersed in a palladium chloride solution for activation, taken out, 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 chemically plated at 25 to 85° C. for 20 to 60 min, and the fabric is taken out, washed and dried to obtain a fabric with 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, the bath ratio is 20-50:1, the chemical plating treatment temperature is 60-85°C, after the treatment for 30-90 min, the fabric is taken out, washed and dried to obtain the fabric having the conductive reflective layer and the microwave absorption 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 absorption 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℃ for 4~8 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.

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 according to claim 1, characterized in that: The reactive molecules are silane coupling agents, polyethyleneimine, dopamine or ethylenediaminetetraacetic acid. The fabric is immersed in an aqueous solution containing the reactive molecules for 0.5 to 2 hours, and the bath ratio is 20 to 50:

1.

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

5. 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 7-8 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, sodium potassium tartrate, and sodium ethylenediaminetetraacetate, and the stabilizer concentration is 5-50 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 3, the plating solution containing magnetic metal salt has a pH value of 8-10 and includes magnetic metal salt, reducing agent, stabilizer, ammonia water and deionized water; The magnetic metal salt is one or more of sulfate, nitrate and chloride, with a concentration of 5-30 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.

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 reaction solution includes 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 ammonium fluoride concentration is 0.5-8 g / L; Ethanol concentration is 20~100 mL / L; The urea concentration is 2~30 g / L.

8. 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.

9. A functional fabric with both electromagnetic shielding and microwave absorption, characterized in that: On the fiber cross section of the functional fabric, from the inside to the outside, there are core fiber, conductive reflection layer, microwave absorption layer and impedance matching layer.

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

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