Yarn with infrared shielding function and fabric made of yarn

Abstract

The invention provides a yarn with an infrared shielding function. The yarn comprises a core yarn and a sheath yarn, the sheath yarn comprises Kevlar composite reinforced fibers and silver-plated aramid fibers; the core yarn is formed by plying and twisting Kevlar fibers, spiral carbon nanofibers and modified K49 aramid fibers. The used Kevlar composite reinforced fiber has the characteristics of high strength, high porous structure and low emissivity, and can endow infrared stealth performance; the silver-plated aramid fiber is based on surface modified aramid fiber, and the surface of the fiber is plated with a silver simple substance layer, so that the silver-plated aramid fiber has infrared stealth and electromagnetic shielding effects. Kevlar fibers in the core yarn have the characteristic of high strength, and spiral carbon nanofibers and modified K49 aramid fibers have the effect of enhancing fiber gaps, so that light energy can be further consumed. The fabric prepared from the yarn prepared by the invention has the advantages of breathability, comfort, high strength and good infrared shielding effect, and can be further popularized and used.

Description

Technical Field

[0001] This invention relates to the field of textile fabric technology, specifically to a yarn with infrared shielding function and the fabric made therefrom. Background Technology

[0002] With the booming development of the outdoor sports industry and the continuous advancement of military equipment technology, the demand for high-end functional textiles is increasing. Among them, fabrics used to make tents, protective clothing and other equipment not only need to have traditional waterproof, abrasion-resistant and breathable properties, but are also endowed with special functions such as infrared stealth and repelling harmful organisms to protect the personal safety of users.

[0003] First, in the field or during military operations, the thermal radiation emitted by the human body and equipment (mainly in the mid-to-far infrared band of 8-14µm) is easily detected by wild animals or advanced infrared detection equipment from the enemy, thus revealing their location and causing danger. Currently, the main method for achieving infrared shielding is to coat the fabric with a layer of metal (such as aluminum) or conductive polymer coating during the finishing stage. These coatings can effectively reflect infrared rays, but they have significant drawbacks: First, the coating is prone to peeling or cracking during repeated use, folding, and friction, leading to a decrease in shielding performance and unreliability; second, the coating process is complex and may cause environmental pollution.

[0004] Secondly, for clothing fabrics used in outdoor environments, the biosafety risks posed by mosquitoes, ants, ticks, snakes, and other insects must be considered, especially their potential to spread diseases or directly attack humans. Existing insect repellents or antibacterial agents primarily adhere to the fiber surface through impregnation or microencapsulation. However, these finishing methods suffer from poor durability; antibacterial components are rapidly lost through washing, evaporation, and friction, requiring frequent re-treatment to maintain effectiveness, which cannot meet the needs of long-term outdoor operations or military deployments. We urgently need yarns with this protective property that can be directly woven into the fabric to minimize friction damage or performance failure.

[0005] Finally, after screening the fiber materials, we selected Kevlar fiber as the main fiber material. Due to its extremely high strength, modulus, and excellent cut and tear resistance, Kevlar fiber has been widely used in bulletproof vests, protective gloves, and high-performance ropes. Fabrics made from it naturally possess high strength and durability, making them an ideal substrate for high-end outdoor tents and military equipment. However, pure Kevlar fabric itself does not have infrared shielding or insect-repellent properties, and its breathability is somewhat inferior to ordinary textile materials.

[0006] In summary, the existing technology has the following obvious drawbacks:

[0007] 1. Limited functionality: High-performance fabrics often focus on a single aspect of performance. In particular, Kevlar fiber cannot meet both high strength and shielding requirements. High-performance fabrics are difficult to integrate multiple key functions into one.

[0008] 2. Insufficient durability: Functions added through finishing processes (such as infrared shielding) have weak bonding with the fiber body, resulting in short service life and unreliable performance.

[0009] 3. Sacrifice of comfort: Coatings or finishing agents added to achieve functionality often come at the cost of sacrificing the fabric's breathability, lightness, and softness. Furthermore, multi-step finishing processes increase production complexity and cost, and may use environmentally unfriendly chemicals, resulting in a complex and environmentally unfriendly process.

[0010] Therefore, there is an urgent need in this field for a novel technical solution that can fundamentally solve the above problems from the perspective of fiber and yarn structure design, and develop a new type of yarn and fabric that integrates infrared shielding, ultra-high strength, and good breathability to meet the urgent needs of high-end outdoor and military fields for multifunctional protective materials. In view of this, we disclose a yarn with infrared shielding function and a fabric made from it. Summary of the Invention

[0011] In view of the shortcomings of the prior art, the present invention aims to provide a yarn with infrared shielding function and a fabric made therefrom.

[0012] To achieve the above objectives, the present invention proposes the following technical solution:

[0013] A yarn with infrared shielding function, comprising core yarn and sheath yarn;

[0014] The sheath yarn is wound around the outer surface of the core yarn, and the sheath yarn includes at least one set of mixed yarn groups, the mixed yarn groups including Kevlar composite reinforcing fibers and silver-plated aramid fibers arranged in sequence;

[0015] The core yarn is made by twisting together a first fiber, a second fiber, and a third fiber; the first fiber is Kevlar fiber, the second fiber is helicalized carbon nanofiber, and the third fiber is modified K49 aramid fiber.

[0016] Based on the above scheme and as a preferred embodiment of the above scheme, the Kevlar composite reinforcing fiber (21) is a Kevlar / aerogel composite reinforcing fiber.

[0017] Based on the above scheme and as a preferred embodiment of the above scheme, the aerogel comprises a composite aerogel of MXene.

[0018] Based on the above scheme and as a preferred embodiment of the above scheme, the preparation method of the Kevlar composite reinforced fiber (21) is as follows:

[0019] S1, Kevlar fiber pretreatment

[0020] Kevlar fibers are immersed in N-methylpyrrolidone and ultrasonically treated. The ultrasonically treated Kevlar fibers are then immersed in N-methylpyrrolidone again to obtain pretreated Kevlar fibers.

[0021] Meanwhile, half of the pretreated Kevlar fibers were immersed in a KOH / dimethyl sulfoxide solution and stirred at room temperature for 60-100 h to obtain a Kevlar nanofiber solution.

[0022] S2, Preparation of Composite Aerogel

[0023] Ti3AlC2 was added to a mixed solution of HCl and LiF, and MXene powder was prepared by in-situ etching. Then, graphene oxide powder and MXene powder were mixed at a mass ratio of (5-6):1 and hydrothermally heated at 120-130℃ for 15-20h to obtain MXene-rGO-based aerogel, i.e., composite aerogel.

[0024] S3, Preparation of Mixed Dispersion

[0025] The Kevlar nanofiber solution in step S1 is mixed with the composite aerogel and stirred evenly. Then, it is ultrasonically treated with a 100-200W ultrasonic machine for 4-6 hours to obtain a mixed dispersion, wherein the composite aerogel accounts for 2%-3% of the mass of Kevlar nanofiber.

[0026] Preparation of S4 Kevlar Composite Reinforced Fibers

[0027] The Kevlar fibers are processed using an impregnation device (3). After passing through a number of guide rollers (31) in step S1, they are passed through at least two plasma treatment device electrodes (32) in sequence and wound back and forth between two adjacent plasma treatment device electrodes (32) 8-10 times. Then they are immersed in the mixed dispersion liquid in the impregnation tank (33) for treatment and the fiber is pressed down using a pressing roller (34) to ensure complete impregnation. Then the Kevlar fibers are taken out and dried in the air environment. The Kevlar composite reinforced fibers are collected using a take-up roller (34) and can be used for later use.

[0028] Based on the above scheme and as a preferred option, in order to better utilize aramid fiber and achieve the combined use of aramid fiber and Kevlar fiber, we carried out surface improvement treatment of aramid fiber. The silver-plated aramid fiber is aramid fiber that has been cleaned, modified by coating, placed in silver nitrate solution and then chemically silver-plated on the fiber surface, so that a layer of silver elemental layer is attached to the fiber surface.

[0029] Based on the above scheme and as a preferred embodiment of the above scheme, the mixed yarn group is provided in two groups.

[0030] Based on the above scheme and as a preferred embodiment of the above scheme, the modified K49 aramid fiber is obtained by treating K49 aramid with supercritical CO2 fluid.

[0031] Based on the above scheme and as a preferred embodiment, the supercritical CO2 fluid treatment conditions for the modified K49 aramid are as follows:

[0032] Temperature 40-45℃, pressure 10-15MPa;

[0033] The in-vessel processing time is 80-90 minutes.

[0034] Based on the above scheme and as a preferred embodiment of the above scheme, a fabric is provided, wherein the fabric is woven from the above-mentioned yarn with infrared shielding function, or the fabric is woven from the above-mentioned yarn with infrared shielding function and other yarns.

[0035] Based on the above scheme and as a preferred embodiment of the above scheme, the other yarns include polyester yarns; the fabrics include woven fabrics and flyweave fabrics.

[0036] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0037] This invention discloses a yarn with infrared shielding function, comprising a core yarn and a sheath yarn. The sheath yarn is wound around the outer surface of the core yarn, and the sheath yarn comprises at least one set of mixed yarn groups, wherein the mixed yarn groups comprise Kevlar composite reinforcing fibers and silver-plated aramid fibers arranged in sequence. The core yarn is formed by twisting together a first fiber, a second fiber, and a third fiber. The first fiber is Kevlar fiber, the second fiber is helicalized carbon nanofiber, and the third fiber is modified K49 aramid fiber.

[0038] The yarn of this invention uses Kevlar composite reinforcing fibers and silver-plated aramid fibers as sheath yarns wound around the outer surface of the core yarn. The Kevlar composite reinforcing fibers not only possess high strength but also a highly porous structure and a low emissivity surface, significantly improving infrared stealth performance. The silver-plated aramid fibers are based on surface-modified aramid with a layer of silver coating on the fiber surface, further enhancing the infrared stealth properties of the mixed yarn assembly. Furthermore, the conductive network structure formed after weaving provides excellent electromagnetic shielding. The Kevlar fibers in the core yarn exhibit high strength, while the spiralized carbon nanofibers and modified K49 aramid fibers enhance fiber spacing, further dissipating light energy. Fabrics made using the yarn prepared according to this invention offer advantages such as breathability, comfort, high strength, and good infrared shielding, and can be further promoted for wider application.

[0039] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered part of the subject matter disclosure of the present invention, provided that such concepts do not contradict each other.

[0040] The foregoing and other aspects, embodiments, and features of the teachings of this invention will be more fully understood from the following description. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of this invention. Attached Figure Description

[0041] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0042] Figure 1 This is a schematic diagram of the yarn structure of the present invention;

[0043] Figure 2 This is a schematic diagram of the resin impregnation equipment;

[0044] Figure 3 This is a schematic diagram of infrared stealth performance testing.

[0045] 1. Core yarn; 2. Sheath yarn; 11. First fiber; 12. Second fiber; 13. Third fiber; 21. Kevlar composite reinforcing fiber; 22. Silver-plated aramid fiber; 3. Impregnation equipment; 31. Guide roller; 32. Electrode of plasma treatment device; 33. Impregnation tank; 34. Pressure roller; 35. Take-up roller. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific examples, but these should not be construed as limiting the present patent.

[0047] Unless otherwise specified, the test methods or experimental methods described in the following examples / comparative examples are conventional methods; unless otherwise specified, the reagents and materials are obtained from conventional commercial sources or prepared by conventional methods.

[0048] In this invention, the preparation method of the Kevlar composite reinforced fiber 21 is as follows:

[0049] S1, Kevlar fiber pretreatment

[0050] Kevlar fibers are immersed in N-methylpyrrolidone and ultrasonically treated. The ultrasonically treated Kevlar fibers are then immersed in N-methylpyrrolidone again to obtain pretreated Kevlar fibers.

[0051] Meanwhile, half of the pretreated Kevlar fibers were immersed in a KOH / dimethyl sulfoxide solution and stirred at room temperature for 60-100 h to obtain a Kevlar nanofiber solution.

[0052] S2, Preparation of Composite Aerogel

[0053] Ti3AlC2 was added to a mixed solution of HCl and LiF, and MXene powder was prepared by in-situ etching. Then, graphene oxide powder and MXene powder were mixed at a mass ratio of (5-6):1 and hydrothermally heated at 120-130℃ for 15-20h to obtain MXene-rGO-based aerogel, i.e., composite aerogel.

[0054] S3, Preparation of Mixed Dispersion

[0055] The Kevlar nanofiber solution in step S1 is mixed with the composite aerogel and stirred evenly. Then, it is ultrasonically treated with a 100-200W ultrasonic machine for 4-6 hours to obtain a mixed dispersion, wherein the composite aerogel accounts for 2%-3% of the mass of Kevlar nanofiber.

[0056] Preparation of S4 Kevlar Composite Reinforced Fibers

[0057] The Kevlar fibers are processed using the impregnation equipment 3. After passing through a number of guide rollers 31, they are passed through at least two plasma treatment device electrodes 32 in sequence, and wound back and forth between two adjacent plasma treatment device electrodes 32 8-10 times. Then, they are immersed in the mixed dispersion liquid in the impregnation tank 33 for treatment, and the fibers are pressed down using the pressing roller 34 to ensure complete impregnation. The Kevlar fibers are then taken out and dried in the air. The Kevlar composite reinforced fibers are collected using the take-up roller 35 and are ready for use.

[0058] The specific preparation method of MXene powder is as follows:

[0059] MXene material Ti3AlC2 was added to a mixed solution of HCl and LiF, with a mass ratio of Ti3AlC2 to LiF of 1:(1.45-1.58). After maintaining the solution at room temperature for 48-60 hours, a stable solution was formed. A higher amount of LiF was used than Ti3AlC2 because using less LiF would result in insufficient HF production, incomplete etching, and failure to completely remove the Al layer; furthermore, the generated Li... + Insufficient ions result in poor intercalation, making MXene difficult to exfoliate and easily leading to unexfoliated multilayered precipitates, thus rendering it unsuitable for use in composite aerogels. This also demonstrates the triple role of LiF: firstly, the combination of LiF and HCl, rather than directly using HF solution, allows for the safe, controllable, and slow release of HF; secondly, Li... + Ions can be embedded into the interlayer spaces of these MXenes during stirring or sonication, effectively widening the interlayer spacing and weakening the interlayer forces; finally, the LiCl generated in the reaction and the excess LiF also participate in the chemical modification of the MXene surface. Preferably, the HCl concentration used in this invention is 8-10M.

[0060] The stabilized solution was then centrifuged multiple times at 3000-3500 r / min and washed alternately with deionized water and ethanol until the pH of the supernatant reached 5.8-6.2. The lower layer was then dried to obtain MXene powder. A hydrothermal reduction process was then performed between the graphene oxide powder and the MXene powder to obtain the MXene-rGO-based composite aerogel.

[0061] Generally, the conductive treatment of aramid fibers employs two methods: surface coating and co-spinning or weaving with composite conductive materials. Surface coating involves attaching materials such as silver nanowires and graphene to the aramid surface via vacuum filtration to form a conductive layer. Co-spinning or weaving with composite conductive materials involves blending or co-spinning carbon fibers, metal wires, or other modern materials with aramid to form a composite structure. Considering cost and preparation methods, we adopted the surface coating method. Furthermore, the silver-plated aramid fiber is prepared by cleaning aramid fibers, modifying them with a coating, placing them in a silver nitrate solution, and then chemically plating the fiber surface with silver, resulting in a layer of elemental silver adhering to the fiber surface. The specific preparation method of the silver-plated aramid fiber includes four steps: fiber cleaning, preparation of the modification solution, fiber modification, and chemical plating, as detailed below:

[0062] Step 1: Immerse the aramid long fibers in anhydrous ethanol solution and sonicate for 0.5-1 hour to remove oil, dust and other impurities deposited on the fiber surface; after sonication, rinse with deionized water at least 3 times, and after rinsing, place in a vacuum oven and vacuum dry at 60-70℃ for 6-10 hours. After drying, remove and seal for storage to obtain cleaned aramid fibers.

[0063] Step 2: Prepare a pH buffer solution using tromethamine. This preparation method is a standard technique in the field and will not be described in detail here. After measuring the pH of the buffer solution, adjust the pH to 8.5-9.5 using dilute hydrochloric acid solution to obtain a combined buffer reagent. Then, add catechol, pyrogallol, and tetraethylenepentamine to the combined buffer reagent in a molar ratio of 10:10:(6-7) and stir evenly. After the raw materials are added, continue stirring for 15-20 minutes to obtain a modified solution.

[0064] Step 3: Place the aramid fibers cleaned in Step 1 into the prepared modification solution and maintain a constant temperature of 40℃ for 5-10 hours. Finally, rinse with deionized water at least 3 times to remove excess catechol, pyrogallol and other substances from the fiber surface. Then, dry the fibers in a vacuum oven at 60-70℃ for 3-6 hours to obtain modified aramid fibers. Store in a sealed container for later use.

[0065] In this step, after the aramid fibers are cleaned and added, the catechol and pyrogallol added in the combined buffer reagent will undergo Michael addition reaction and Schiff base reaction, and the solution can be clearly seen to change from colorless to orange and then to dark brown. Finally, after the modified aramid fibers are dried, a dark brown modified coating can be seen on the fiber surface.

[0066] Step 4: Prepare the chemical plating solution, and then subject the modified aramid fibers from Step 3 to chemical silver plating for 0.5-4 hours, so that a layer of elemental silver adheres to the fiber surface. For example, in the laboratory setting, weigh silver nitrate and potassium hydroxide in a mass ratio of 2:1. Then, take 6-7 times the mass of silver nitrate in ammonia water, dissolve the silver nitrate and potassium hydroxide in the ammonia water, and stir until homogeneous to obtain a mixture. Next, place the mixture in 10 times the volume of ammonia water in deionized water and stir thoroughly to obtain solution A.

[0067] Similarly, take glucose and sodium potassium tartrate in a mass ratio of 4:1 and dissolve them in 10 times the mass of sodium potassium tartrate in ethanol to obtain a mixed solution. Place the well-stirred mixed solution in 10 times the volume of deionized water to obtain solution B.

[0068] Finally, solutions A and B are mixed evenly to obtain the chemical plating solution.

[0069] The modified coating on the surface of aramid fibers increases the surface roughness, improves the uniformity of coating adhesion without peeling, and increases the number of oxygen-containing active groups, thus improving the surface activity of the aramid fibers. Furthermore, compared to unmodified aramid fibers, the modified aramid fibers exhibit a 13.2% reduction in contact angle, enhanced wettability, and a 10.98% increase in tensile breaking strength.

[0070] After electroless plating of the modified fibers, the silver in the solution is reduced onto the surface of the modified aramid fibers, thus achieving the deposition of a silver layer and forming modified fibers with good conductivity. The thickness of the elemental silver layer formed on the surface of the modified fibers can be controlled by varying the electroless plating time.

[0071] Furthermore, the modified K49 aramid fiber is obtained by treating K49 aramid with supercritical CO2 fluid. The supercritical CO2 fluid treatment conditions are as follows:

[0072] Temperature 40-45℃, pressure 10-15MPa;

[0073] The in-vessel processing time is 80-90 minutes.

[0074] Preferably, the treatment temperature is 42℃, the pressure is 13MPa, and the treatment time in the autoclave is 85min. Supercritical CO2 fluid treatment not only removes the treatment agent from the fiber surface but also further increases the surface roughness of the fiber. Atomic force microscopy analysis of the fiber surface roughness revealed that the root mean square roughness, average roughness, and maximum roughness of the K49 aramid fiber treated with supercritical CO2 fluid all increased to varying degrees. This demonstrates that the overall roughness of the K49 aramid fiber increased after supercritical CO2 fluid treatment, which helps to continuously reflect and dissipate light within the fiber, thereby enhancing infrared shielding.

[0075] Furthermore, the spiral carbon nanofibers are purchased from the Advanced Institute of Technology (Shenzhen) Co., Ltd., and the fibers have also undergone plasma surface treatment by the plasma treatment device electrode 32 in the impregnation equipment.

[0076] It should be further explained that the first fiber 11, the second fiber 12 and the third fiber 13 are twisted and fixed into core yarn 1 using common twisting equipment; when twisting and fixing the sheath yarn 2 on the outer surface of the core yarn 1, it is necessary to twist them in the order of one Kevlar composite reinforcing fiber and one silver-plated aramid fiber.

[0077] Performance testing

[0078] Mechanical property testing

[0079] According to standard GB / T 3923.1-2013 "Textiles - Tensile Properties of Fabrics - Part 1: Determination of Breaking Strength and Elongation at Break (Strip Method)", the mechanical properties of the yarn were tested using a JYG061FQ electronic single yarn tensile tester under normal temperature conditions, with the yarn spacing being 200 mm and the tensile speed being 200 mm / min.

[0080] Infrared shielding performance

[0081] Infrared stealth is another indispensable function of multifunctional military fabrics, protecting electronic equipment and military weapon materials from detection by various enemy detection methods. The infrared shielding yarn of this invention was woven into textiles according to GB / T 30127-2013 "Testing and Evaluation of Far-Infrared Properties of Textiles" for performance testing.

[0082] The requirement is that the far-infrared emissivity must be ≥0.88.

[0083] Furthermore, to further test the infrared stealth performance of fabrics made from the yarn of this invention, we wove the yarn into fabrics of the same thickness for infrared stealth performance testing. Specifically, the square fabric to be tested was placed on a heated platform and exposed to a 53°C circular spotlight for the same amount of time to evaluate its infrared stealth performance. A schematic diagram of the operation is shown below. Figure 3 As shown, the bottom layer is the hot platform, exposed to the air, and its temperature is generally the same as room temperature according to thermal imaging. The central ring represents the exposure temperature of the searchlight, which was set to 53°C during testing. The central square object is the test square fabric. The stealth performance of the square fabric is judged by its feedback temperature (°C). If the square fabric has excellent stealth performance, it can effectively prevent heat from being transferred from the bottom platform to the surface of the upper fabric, and its temperature will be closer to the temperature of the hot platform.

[0084] Electromagnetic shielding performance

[0085] Electromagnetic shielding performance was tested using a vector network analyzer (PNA-LN 5230C, Agilent), following the measurement method for electromagnetic shielding effectiveness in standard GB / T12190-2021. The shielding effectiveness of the fabrics made from the yarns used in the examples and comparative examples was tested within a frequency range of 150MHz-18GHz. It is important to note that the fabrics used in the tests had the same weave pattern and were of consistent thickness.

[0086] The electromagnetic shielding effectiveness (EMI) measured in tests is expressed in dB. The higher the EMI value, the better the electromagnetic radiation protection performance.

[0087] Weather resistance test

[0088] To test the electromagnetic shielding stability of textiles, we conducted further tests on the electromagnetic shielding performance after 10 washes, according to the above standards.

[0089] Example 1

[0090] A yarn with infrared shielding function includes a core yarn 1 and a sheath yarn 2. The sheath yarn 2 is wound around the outer surface of the core yarn 1. The sheath yarn 2 includes at least one set of mixed yarn groups, which include Kevlar composite reinforcing fibers 21 and silver-plated aramid fibers 22 arranged in sequence. The core yarn 1 is formed by twisting together a first fiber 11, a second fiber 12 and a third fiber 13. The first fiber 11 is Kevlar fiber, the second fiber 12 is helicalized carbon nanofiber, and the third fiber 13 is modified K49 aramid fiber.

[0091] Furthermore, the Kevlar composite reinforcing fiber 21 is a Kevlar / aerogel composite reinforcing fiber. The preparation method of the Kevlar composite reinforcing fiber 21 is as follows:

[0092] S1, Kevlar fiber pretreatment

[0093] Kevlar fibers are immersed in N-methylpyrrolidone and ultrasonically treated. The ultrasonically treated Kevlar fibers are then immersed in N-methylpyrrolidone again to obtain pretreated Kevlar fibers.

[0094] Meanwhile, half of the pretreated Kevlar fibers were immersed in a KOH / dimethyl sulfoxide solution and stirred at room temperature for 80 hours to obtain a Kevlar nanofiber solution.

[0095] S2, Preparation of Composite Aerogel

[0096] Ti3AlC2 was added to a mixed solution of HCl and LiF, and MXene powder was prepared by in-situ etching. Then, graphene oxide powder and MXene powder were mixed at a mass ratio of 5:1 and hydrothermally heated at 125℃ for 15h to obtain MXene-rGO-based aerogel, i.e., composite aerogel.

[0097] S3, Preparation of Mixed Dispersion

[0098] The Kevlar nanofiber solution in step S1 was mixed with the composite aerogel and stirred evenly. Then, it was ultrasonically treated with a 150W ultrasonic machine for 5 hours to obtain a mixed dispersion, wherein the composite aerogel accounted for 2% of the mass of the Kevlar nanofiber.

[0099] Preparation of S4 Kevlar Composite Reinforced Fibers

[0100] The Kevlar fibers pretreated in step S1 are processed using an impregnation device 3. After passing through a number of guide rollers 31, they are sequentially passed through at least two plasma treatment device electrodes 32 and wound back and forth 9 times between two adjacent plasma treatment device electrodes 32. Then, they are immersed in the mixed dispersion liquid in the impregnation tank 33 for treatment, and the fibers are pressed down using a pressing roller 34 to ensure complete impregnation. The Kevlar fibers are then taken out and dried in an air environment. The Kevlar composite reinforced fibers are collected using a take-up roller 35 and are ready for use.

[0101] Furthermore, the silver-plated aramid fiber is a chemically silver-plated aramid fiber that has been cleaned, modified with a coating, placed in a silver nitrate solution, and then coated with silver to form a layer of elemental silver on the fiber surface.

[0102] Furthermore, the modified K49 aramid fiber is obtained by treating K49 aramid with supercritical CO2 fluid. The supercritical CO2 fluid treatment conditions for the modified K49 aramid are as follows:

[0103] Temperature 40℃, pressure 10MPa;

[0104] The in-vessel processing time is 80 minutes.

[0105] Example 2

[0106] Unlike Embodiment 1 above, the mixed yarn group is provided in two groups, namely, the sheath yarn 2 includes Kevlar composite reinforcing fiber 21, silver-plated aramid fiber 22, Kevlar composite reinforcing fiber 21, and silver-plated aramid fiber 22 arranged in sequence.

[0107] Other operating steps are the same as in Example 1.

[0108] Comparative Example 1

[0109] Unlike Example 1, the Kevlar composite reinforcing fibers in the mixed yarn group are replaced with silver-plated aramid fibers.

[0110] Other operating steps are the same as in Example 1.

[0111] Comparative Example 2

[0112] Unlike Example 1, in the preparation of the Kevlar composite reinforced fiber in the mixed yarn group, the composite aerogel was replaced with an equal mass of graphene oxide powder.

[0113] Other operating steps are the same as in Example 1.

[0114] Comparative Example 3

[0115] Unlike Example 1, in the preparation of the Kevlar composite reinforced fiber in the mixed yarn group, the composite aerogel was replaced with an equal mass of MXene powder.

[0116] Other operating steps are the same as in Example 1.

[0117] Comparative Example 4

[0118] Unlike Example 1, in the preparation process of the Kevlar composite reinforced fiber in the mixed yarn group, the composite aerogel is replaced with a mixture of graphene oxide powder and MXene powder of equal mass, and the graphene oxide powder and MXene powder are directly physically mixed.

[0119] Other operating steps are the same as in Example 1.

[0120] Comparative Example 5

[0121] Unlike Example 1, in the Kevlar composite reinforced fiber preparation process, the Kevlar nanofiber solution in the mixed dispersion is replaced with an equal mass of deionized water solution.

[0122] Other operating steps are the same as in Example 1.

[0123] Comparative Example 6

[0124] Unlike Example 1, the silver-plated aramid fibers in the mixed yarn group are replaced with Kevlar composite reinforcing fibers.

[0125] Other operating steps are the same as in Example 1.

[0126] Comparative Example 7

[0127] Unlike Example 1, the core yarn 1 only includes a first fiber 11 and a second fiber 12.

[0128] Other operating steps are the same as in Example 1.

[0129] Comparative Example 8

[0130] Unlike Example 1, the core yarn 1 only includes a first fiber 11 and a third fiber 13.

[0131] Other operating steps are the same as in Example 1.

[0132] The yarns of the above embodiments and comparative examples were tested according to different performance test standards, and the test results are compared in Table 1.

[0133] Table 1 Performance Test Comparison Analysis

[0134] As shown in the performance comparison analysis in Table 1 above, the Kevlar composite reinforced fiber prepared by this invention possesses the high strength characteristics of Kevlar fiber. Combined with the support and assistance of multi-structured composite aerogel and Kevlar nanofibers, the Kevlar composite reinforced fiber exhibits high strength and good infrared stealth properties. Silver-plated aramid fiber is prepared by chemically plating silver onto the surface of cleaned aramid fiber after coating modification, followed by immersion in silver nitrate solution. This not only increases the surface roughness and the number of active groups, improving the surface activity of the aramid fiber, but the addition of a silver elemental layer also enhances the electromagnetic shielding effect of the fiber. Modified K49 aramid fiber utilizes a supercritical fluid treatment method to increase the surface roughness of the fiber, creating air gaps between fibers and thus enhancing light refraction efficiency. Similarly, helical carbon nanofibers, due to their helical structure, also form air gaps with adjacent fibers, exhibiting the same light energy consumption characteristics and demonstrating a synergistic effect in infrared shielding.

[0135] MXene-rGO-based aerogels, prepared via a hydrothermal reaction, possess a highly porous structure, making them a viable factor for improving infrared stealth performance. rGO provides a highly interconnected microporous structure with a pore size distribution maintained at the micrometer level. The cross-linked channels form a strong support, contributing to the enhanced toughness of the porous framework. Furthermore, the unique wrinkled morphology of rGO increases the internal specific surface area, broadening the mass transfer pathways for MXene. MXene is successfully loaded into the internal pores of the porous rGO aerogel and cross-linked with the surrounding rGO backbone, but is not encased by the wrinkles of the MXene aerogel, ensuring the exposure of active sites. Moreover, MXene materials exhibit low reflectance, particularly in the mid-infrared and far-infrared bands, providing another factor contributing to the overall infrared stealth performance of the yarn.

[0136] The comparative analysis shows that Kevlar composite reinforcing fibers have a significant impact on infrared stealth performance. When silver-plated aramid fibers are replaced with Kevlar composite reinforcing fibers, the temperature difference between the fiber fabric on the hot plate and the circular searchlight is not large compared to the temperature difference of the fabric prepared with the yarn of this invention. However, the temperature difference is still not as large as that of the fabric prepared with the yarn of this invention. This indicates that silver-plated aramid fibers also contribute to infrared stealth performance, and the fibers constituting the mixed yarn group have a synergistic effect on infrared stealth. In Comparative Example 4, the direct physical mixing of graphene oxide powder and MXene powder, due to their large size difference, easily leads to agglomeration, resulting in performance that is not as good as using a single element directly. The far-infrared emissivity and infrared stealth performance feedback show similar results.

[0137] For electromagnetic shielding performance, silver-plated aramid fiber is the primary factor affecting electromagnetic shielding performance. Secondly, in the Kevlar composite reinforcing fiber, Kevlar nanofibers, taking advantage of their size, are uniformly distributed on the surface of the Kevlar fiber along with the composite aerogel, which contributes to the electromagnetic shielding performance of the fabric prepared by the yarn of this invention. Moreover, after 10 washes, the fabric prepared by the yarn of this invention still has good electromagnetic shielding properties.

[0138] Regarding mechanical properties, in Kevlar composite reinforced fibers, Kevlar nanofibers can prevent the propagation of microcracks during the manufacturing process, which helps to improve mechanical properties. Composite aerogels utilize rGO to provide a micron-level microporous structure, and the cross-linked channels form a strong support. Combined with the mechanical amplification of MXene material, all of these contribute to improved mechanical properties. However, directly mixing graphene oxide powder and MXene powder physically can easily cause agglomeration and uneven distribution, resulting in a significant decrease in mechanical properties.

[0139] The yarn of this invention uses Kevlar composite reinforcing fibers and silver-plated aramid fibers as sheath yarns wound around the outer surface of the core yarn. The Kevlar composite reinforcing fibers not only possess high strength but also a highly porous structure and a low emissivity surface, significantly improving infrared stealth performance. The silver-plated aramid fibers are based on surface-modified aramid with a layer of silver coating on the fiber surface, further enhancing the infrared stealth properties of the mixed yarn assembly. Furthermore, the conductive network structure formed after weaving provides excellent electromagnetic shielding. The Kevlar fibers in the core yarn exhibit high strength, while the spiralized carbon nanofibers and modified K49 aramid fibers enhance fiber spacing, further dissipating light energy. Fabrics made using the yarn prepared according to this invention offer advantages such as breathability, comfort, high strength, and good infrared shielding, and can be further promoted for wider application.

[0140] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A yarn with infrared shielding function, characterized in that, Includes core yarn (1) and sheath yarn (2): The sheath yarn (2) is wound around the outer surface of the core yarn (1). The sheath yarn (2) includes at least one set of mixed yarns, which includes Kevlar composite reinforcing fibers (21) and silver-plated aramid fibers (22) arranged in sequence. The core yarn (1) is made by twisting together a first fiber (11), a second fiber (12) and a third fiber (13); the first fiber (11) is Kevlar fiber, the second fiber (12) is helicalized carbon nanofiber, and the third fiber (13) is modified K49 aramid fiber.

2. The yarn with infrared shielding function according to claim 1, characterized in that, The Kevlar composite reinforcing fiber (21) is a Kevlar / aerogel composite reinforcing fiber.

3. A yarn with infrared shielding function according to claim 2, characterized in that, The aerogel contains a composite aerogel of MXene.

4. A yarn with infrared shielding function according to claim 3, characterized in that, The preparation method of the Kevlar composite reinforced fiber (21) is as follows: S1, Kevlar fiber pretreatment Kevlar fibers are immersed in N-methylpyrrolidone and ultrasonically treated. The ultrasonically treated Kevlar fibers are then immersed in N-methylpyrrolidone again to obtain pretreated Kevlar fibers. Meanwhile, half of the pretreated Kevlar fibers were immersed in a KOH / dimethyl sulfoxide solution and stirred at room temperature for 60-100 h to obtain a Kevlar nanofiber solution. S2, Preparation of Composite Aerogel Ti3AlC2 was added to a mixed solution of HCl and LiF, and MXene powder was prepared by in-situ etching. Then, graphene oxide powder and MXene powder were mixed at a mass ratio of (5-6):1 and hydrothermally heated at 120-130℃ for 15-20h to obtain MXene-rGO-based aerogel, i.e., composite aerogel. S3, Preparation of Mixed Dispersion The Kevlar nanofiber solution in step S1 is mixed with the composite aerogel and stirred evenly. Then, it is ultrasonically treated with a 100-200W ultrasonic machine for 4-6 hours to obtain a mixed dispersion, wherein the composite aerogel accounts for 2%-3% of the mass of Kevlar nanofiber. Preparation of S4 Kevlar Composite Reinforced Fibers The Kevlar fiber pretreated in step S1 is processed using an impregnation device (3). After passing through a number of guide rollers (31), it passes through at least two plasma treatment device electrodes (32) in sequence and is wound back and forth between two adjacent plasma treatment device electrodes (32) 8-10 times. Then it is immersed in the mixed dispersion liquid in the impregnation tank (33) for treatment and the fiber is pressed down using a pressing roller (34) to ensure complete impregnation. Then the Kevlar fiber is taken out and dried in the air environment. The Kevlar composite reinforced fiber is collected using a take-up roller (35) and can be used for later use.

5. A yarn with infrared shielding function according to claim 1, characterized in that, The silver-plated aramid fiber is made by cleaning aramid fiber, modifying it with a coating, placing it in a silver nitrate solution, and then chemically plating the fiber surface with silver, so that a layer of elemental silver is attached to the fiber surface.

6. A yarn with infrared shielding function according to claim 1, characterized in that, The mixed yarn group is provided in two groups.

7. A yarn with infrared shielding function according to claim 1, characterized in that, The modified K49 aramid fiber is obtained by treating K49 aramid with supercritical CO2 fluid.

8. A yarn with infrared shielding function according to claim 7, characterized in that, The supercritical CO2 fluid treatment conditions for the modified K49 aramid are as follows: Temperature 40-45℃, pressure 10-15MPa; The in-vessel processing time is 80-90 minutes.

9. A fabric, characterized in that, The fabric is woven from the infrared shielding yarn as described in any one of claims 1-8, or the fabric is woven from the infrared shielding yarn as described in any one of claims 1-8 and other yarns.

10. A yarn with infrared shielding function according to claim 9, characterized in that, The other yarns include polyester yarns; the fabrics include woven fabrics and knitted fabrics.

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