Hollow fiber composite fabric and method of making same

Abstract

The application discloses a kind of hollow fiber composite fabric and its preparation method, first with the DMF solution of PVP as core layer spinning solution, with the DMF solution of the blend of TPU, silica aerogel microspheres and phase change microcapsule as shell layer spinning solution, composite gel fiber is prepared using coaxial wet spinning process;Subsequently, by ultrasonic treatment, PVP template in core layer is selectively removed, and the gel fiber with hollow structure is constructed. The obtained hollow gel fiber is woven into a fabric as a flexible thermal insulation substrate;Then, a conductive silver paste is coated on the surface of the fabric and solidified to form a continuous and uniform metal conductive layer, finally giving the composite fabric infrared wave band stealth performance. The composite fabric prepared by the application has excellent flexible thermal insulation performance and infrared stealth performance. The synergistic effect of the hollow structure and the phase change material improves the thermal insulation effect, and the metallized surface realizes the infrared stealth function. It can be widely used in intelligent protection, flexible electronics and other fields.

Description

Technical Field

[0001] This invention belongs to the field of functional fiber and intelligent textile material technology, specifically relating to a hollow fiber composite fabric with infrared stealth properties prepared based on coaxial wet spinning technology and its preparation method. Background Technology

[0002] With the rapid development of fields such as intelligent protection and flexible electronics, the demand for multifunctional integration of fabrics is increasing, especially composite fabrics that combine flexibility, heat insulation and infrared stealth properties, which have broad application prospects in military camouflage, personal protection and smart wearable scenarios.

[0003] Currently, the preparation of infrared stealth fabrics mostly employs surface metallization or the addition of infrared masking agents. However, traditional methods have several drawbacks: while simple surface metallization can achieve infrared stealth, the fabric suffers from poor flexibility and breathability, as well as insufficient thermal insulation; fabrics with added infrared masking agents have limited stealth effects, and the masking agents are prone to agglomeration, affecting the fabric's mechanical properties and appearance. Furthermore, existing hollow fiber preparation methods primarily utilize melt spinning or dry spinning, which suffer from complex processes, high equipment costs, and poor controllability of the fiber's hollow structure, making it difficult to simultaneously achieve a synergistic improvement in fabric flexibility, thermal insulation, and infrared stealth performance.

[0004] Coaxial wet spinning technology boasts advantages such as simple process, low equipment cost, and strong controllability of fiber structure, enabling precise preparation of core-shell structured fibers and providing a new approach for hollow fiber fabrication. Phase change microcapsules possess energy storage and release functions, which can help improve the thermal insulation performance of fabrics; silica aerogel microspheres have extremely low thermal conductivity, making them excellent thermal insulation filler materials; and the metallic conductive layer can effectively reduce the infrared emissivity of fabrics, achieving infrared stealth. Combining these three technologies with coaxial wet spinning technology can produce composite fabrics that combine flexibility, thermal insulation, and infrared stealth properties, effectively addressing the shortcomings of existing technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing infrared stealth fabrics, such as poor flexibility, poor heat insulation effect, and complex preparation process. It provides a hollow fiber composite fabric with infrared stealth performance prepared based on coaxial wet spinning technology and its preparation method. The preparation method is simple, highly controllable, and the prepared composite fabric has both excellent flexible heat insulation performance and infrared stealth performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a hollow fiber composite fabric includes the following steps: Step (1) Preparation of core spinning solution and shell spinning solution: The core spinning solution is a solution of polyvinylpyrrolidone (PVP) in N,N-dimethylformamide (DMF); the shell spinning solution is a DMF solution of thermoplastic polyurethane (TPU), silica aerogel microspheres and phase change microcapsules. Step (2) Preparation of composite gel fiber: Using coaxial wet spinning technology, the core spinning solution and shell spinning solution prepared in step (1) are simultaneously extruded and solidified in a coagulation bath to obtain composite gel fiber; Step (3) Constructing hollow gel fibers: The composite gel fibers obtained in step (2) are subjected to ultrasonic treatment to selectively remove the PVP template in the core layer and obtain hollow gel fibers. Step (4) Preparation of flexible thermal insulation substrate: The hollow gel fibers obtained in step (3) are woven into fabric as flexible thermal insulation substrate; Step (5) Imparting infrared stealth properties: The surface of the flexible heat insulation substrate obtained in step (4) is coated with conductive silver paste, and after curing, a continuous and uniform metal conductive layer is formed, resulting in a hollow fiber composite fabric with infrared stealth properties.

[0007] Preferably, in step (1) of the present invention, the mass fraction of PVP in the core spinning solution is 20%~60%, the stirring temperature is 40~60 ℃, and the stirring time is 2~4 h until PVP is completely dissolved, so as to ensure that the core spinning solution is uniform and free of sediment, laying the foundation for the subsequent formation of hollow structure.

[0008] Preferably, in step (1) of the present invention, the shell spinning solution contains 8%~20% TPU by mass, 2%~8% silica aerogel microspheres by mass, and 5%~12% phase change microcapsules by mass. After blending, the components are stirred at 50~70 °C for 3~6 h to form a uniformly dispersed spinning solution. TPU, as the fiber-forming substrate, imparts good flexibility and mechanical properties to the fiber; silica aerogel microspheres can reduce the thermal conductivity of the fiber and improve its thermal insulation performance; phase change microcapsules can further optimize the thermal insulation effect through energy storage and release. The three work synergistically to ensure the comprehensive performance of the fiber.

[0009] Preferably, the phase change microcapsules of the present invention have a particle size of 1-10 μm, the core material is one or a mixture of two of paraffin wax and polyethylene glycol, and the wall material is one of melamine-formaldehyde resin and urea-formaldehyde resin. This particle size range ensures that the phase change microcapsules are uniformly dispersed in the shell spinning solution, preventing agglomeration, while also ensuring the fiber-forming properties of the fibers; the selected core material has a suitable phase change temperature, and the wall material has good stability, allowing it to maintain its phase change function for a long time.

[0010] Preferably, in step (2) of the present invention, the spinning speed of the coaxial wet spinning is 0.5~2 mL / min, the flow ratio of the core layer to the shell layer spinning solution is 1:2~1:5; the coagulation bath is a mixed solution of deionized water and DMF, wherein the volume fraction of DMF is 10%~30%, the coagulation bath temperature is 20~35 ℃, and the residence time of the fiber in the coagulation bath is 5~15 min. By adjusting the spinning speed and flow ratio, the core-shell thickness ratio of the fiber can be precisely controlled; the composition and temperature of the coagulation bath can affect the coagulation rate of the fiber, thereby affecting the structure and mechanical properties of the fiber, ensuring good formation of the composite gel fiber.

[0011] Preferably, in step (3) of the present invention, the ultrasonic treatment power is 80~200 W, the ultrasonic time is 10~30 min, the ultrasonic temperature is 25~40 ℃, and the ultrasonic medium is deionized water. Ultrasonic treatment can selectively remove the PVP template in the core layer without damaging the shell structure. By adjusting the ultrasonic parameters, the hollow pore size can be precisely controlled to obtain hollow gel fibers with uniform structure.

[0012] Preferably, in step (4) of the present invention, the weaving method is one of machine weaving, knitting, or braiding, and the fabric thickness is 0.3~1.5 mm. Different weaving methods can adapt to different application scenarios, and the control of weaving density and thickness can take into account the flexibility and heat insulation performance of the fabric, ensuring that the fabric has good wearing comfort and protective effect.

[0013] Preferably, in step (5) of the present invention, the solid content of the conductive silver paste is 50%~80%, the coating method is one of scraping, spraying or dipping, the coating thickness is 10~50 μm, the curing temperature is 80~120 ℃, and the curing time is 30~90 min. The solid content and coating thickness of the conductive silver paste can affect the continuity and conductivity of the metal conductive layer. The curing parameters can ensure that the conductive silver paste is fully cured to form a stable metal conductive layer, effectively reducing the infrared emissivity of the fabric and achieving infrared stealth.

[0014] Preferably, in step (5) of the present invention, the surface resistance of the metal conductive layer is ≤10 mΩ / □ and the infrared emissivity is ≤0.3, which can ensure that the fabric has excellent infrared stealth performance and meet the needs of practical applications.

[0015] The present invention also protects a hollow fiber composite fabric prepared by the above preparation method. The composite fabric uses hollow gel fiber woven fabric as the substrate, and the surface of the substrate is provided with a continuous and uniform metal conductive layer. The hollow pore size of the hollow gel fiber is 50~200 μm. The fabric has both flexible heat insulation properties and infrared stealth properties.

[0016] Compared with the prior art, the technical solution of the present invention has the following advantages: 1. This invention uses coaxial wet spinning technology combined with ultrasonic template removal process to prepare hollow gel fibers. The process is simple, the equipment cost is low, and the controllability is strong. It can accurately control the pore size and structure of hollow fibers. Compared with traditional melt spinning and dry spinning technologies, it significantly improves the preparation efficiency and quality of hollow fibers.

[0017] 2. The present invention introduces silica aerogel microspheres and phase change microcapsules into the shell spinning solution. The two work synergistically with the hollow structure to significantly improve the thermal insulation performance of the fabric: the low thermal conductivity of silica aerogel microspheres can effectively block heat transfer, the phase change microcapsules can regulate temperature through energy storage and release, and the hollow structure can form an air insulation layer, further reducing the thermal conductivity.

[0018] 3. The present invention forms a continuous and uniform metal conductive layer by coating the fabric surface with conductive silver paste and curing it, which can effectively reduce the infrared emissivity of the fabric and achieve infrared stealth performance. At the same time, the metal conductive layer is tightly bonded to the fabric substrate and will not significantly affect the flexibility and wearing comfort of the fabric.

[0019] 4. The composite fabric prepared by this invention has excellent flexibility, heat insulation and infrared stealth properties. It has a stable structure and good mechanical properties, and can be widely used in fields such as intelligent protection, military camouflage, flexible electronics and wearable devices, with broad application prospects. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure and a flowchart of the preparation process of the infrared stealth composite fabric of the present invention; Figure 2 Cross-sectional scanning electron microscope images of hollow gel fibers for all examples; Figure 3 This is a schematic diagram of the emissivity of the composite fabric in Example 1 at 3-5 μm and 8-14 μm. Figure 4 The image shows the actual hollow fiber composite fabric obtained in Example 3. Figure 5 The image shows a cross-sectional scanning electron microscope image of the hollow gel fiber in Example 3. Figure 6 This is a schematic diagram of the surface of the hollow gel fiber in Example 3 using a scanning electron microscope. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments, but these embodiments do not limit the scope of protection of the present invention. In the embodiments of the present invention, N,N-dimethylformamide (DMF 99.5%) was purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd., polyvinylpyrrolidone K30 (PVP K30) was obtained from Tianjin Tianli Chemical Reagent Co., Ltd., and thermoplastic polyurethane elastomer (TPU, 1185a) was purchased from BASF GmbH in Ludwigshafen, Germany. All chemicals are analytical grade reagents and can be used without further purification.

[0022] Example 1: A method for preparing hollow fiber composite fabrics with infrared stealth properties based on coaxial wet spinning technology, comprising the following steps: Step (1) Preparation of core spinning solution and shell spinning solution: The core spinning solution is a DMF solution of PVP, wherein the mass fraction of PVP is 20%, and it is stirred at 40 °C for 2 h until PVP is completely dissolved; The shell spinning solution is a DMF solution of TPU, silica aerogel microspheres and phase change microcapsules, wherein the mass fraction of TPU is 8%, the mass fraction of silica aerogel microspheres is 2%, the mass fraction of phase change microcapsules is 5%, the particle size of phase change microcapsules is 3 μm, the core material is paraffin wax, and the wall material is melamine-formaldehyde resin. After the components are mixed, they are stirred at 50 °C for 3 h to form a uniformly dispersed spinning solution.

[0023] Step (2) Preparation of composite gel fiber: Coaxial wet spinning technology was used with a spinning speed of 0.5 mL / min and a core-to-shell spinning solution flow ratio of 1:2. The core-to-shell spinning solution was extruded simultaneously. The coagulation bath was a mixed solution of deionized water and DMF (DMF volume fraction of 10%), the coagulation bath temperature was 20 °C, and the fiber residence time in the coagulation bath was 5 min. After solidification, composite gel fiber was obtained.

[0024] Step (3) Constructing hollow gel fibers: Place the composite gel fibers in deionized water and sonicate them for 10 min at a power of 80 W and a temperature of 25 °C to selectively remove the PVP template in the core layer and obtain hollow gel fibers with a pore size of 50~100 μm.

[0025] Step (4) Preparation of flexible thermal insulation substrate: Hollow gel fibers are woven into a fabric with a thickness of 0.3 mm, which serves as the flexible thermal insulation substrate.

[0026] Step (5) Imparting infrared stealth properties: Using a scraping method, a conductive silver paste (solid content of 50%) is coated on the surface of the flexible heat insulation substrate with a coating thickness of 10 μm. Then, it is cured at 80 ℃ for 90 min to form a continuous and uniform metal conductive layer, thus obtaining a hollow fiber composite fabric with infrared stealth properties.

[0027] Testing revealed that the surface resistance of the metal conductive layer in the hollow fiber composite fabric prepared in Example 1 was 20 mΩ, the infrared emissivity was 0.50, the hollow gel fiber structure was uniform, the fabric had good flexibility, excellent thermal insulation performance, and a thermal conductivity of 0.05876 W / (m·K).

[0028] Example 2: A method for preparing hollow fiber composite fabrics with infrared stealth properties based on coaxial wet spinning technology, comprising the following steps: Step (1) Preparation of core spinning solution and shell spinning solution: The core spinning solution is a DMF solution of PVP, wherein the mass fraction of PVP is 40%, and it is stirred at 50 °C for 3 h until PVP is completely dissolved; The shell spinning solution is a DMF solution of TPU, silica aerogel microspheres and phase change microcapsules, wherein the mass fraction of TPU is 14%, the mass fraction of silica aerogel microspheres is 5%, the mass fraction of phase change microcapsules is 8%, the particle size of phase change microcapsules is 3 μm, the core material is polyethylene glycol, and the wall material is urea-formaldehyde resin. After the components are mixed, they are stirred at 60 °C for 4.5 h to form a uniformly dispersed spinning solution.

[0029] Step (2) Preparation of composite gel fiber: Coaxial wet spinning technology was used with a spinning speed of 1.2 mL / min and a core-to-shell spinning solution flow ratio of 1:3.5. The core-to-shell spinning solution was extruded simultaneously. The coagulation bath was a mixed solution of deionized water and DMF (DMF volume fraction of 20%), the coagulation bath temperature was 28 ℃, and the fiber residence time in the coagulation bath was 10 min. After solidification, composite gel fiber was obtained.

[0030] Step (3) Constructing hollow gel fibers: Place the composite gel fibers in deionized water and sonicate them for 20 min at a power of 140 W and a temperature of 32 ℃ to selectively remove the PVP template in the core layer and obtain hollow gel fibers with a pore size of 100~150 μm.

[0031] Step (4) Preparation of flexible thermal insulation substrate: Hollow gel fibers are woven into a fabric with a thickness of 0.9 mm, which serves as the flexible thermal insulation substrate.

[0032] Step (5) Imparting low emissivity performance: Using a spraying method, a conductive silver paste (solid content of 50%) is coated on the surface of the flexible heat insulation substrate with a coating thickness of 30 μm. Then, it is cured at 100 ℃ for 60 min to form a continuous and uniform metal conductive layer, thus obtaining a hollow fiber composite fabric with infrared stealth performance.

[0033] According to the test results, the surface resistance of the metal conductive layer in the hollow fiber composite fabric prepared in Example 2 is 20 mΩ, the infrared emissivity is 0.50, the hollow gel fiber structure is uniform, the fabric has good flexibility, excellent heat insulation performance, and the thermal conductivity is 0.04651 W / (m·K).

[0034] Example 3: A method for preparing hollow fiber composite fabrics with infrared stealth properties based on coaxial wet spinning technology, comprising the following steps: Step (1) Preparation of core spinning solution and shell spinning solution: The core spinning solution is a DMF solution of PVP, wherein the mass fraction of PVP is 60%, and it is stirred at 60 °C for 4 h until PVP is completely dissolved; The shell spinning solution is a DMF solution of TPU, silica aerogel microspheres and phase change microcapsules, wherein the mass fraction of TPU is 20%, the mass fraction of silica aerogel microspheres is 8%, the mass fraction of phase change microcapsules is 12%, the particle size of phase change microcapsules is 3 μm, the core material is a mixture of paraffin and polyethylene glycol (mass ratio 1:1), and the wall material is melamine-formaldehyde resin. After the components are mixed, they are stirred at 70 °C for 6 h to form a uniformly dispersed spinning solution.

[0035] Step (2) Preparation of composite gel fiber: Coaxial wet spinning technology was used, the spinning speed was 2 mL / min, the flow ratio of the core layer and the shell layer spinning solution was 1:5, the core layer spinning solution and the shell layer spinning solution were extruded simultaneously, the coagulation bath was a mixed solution of deionized water and DMF (DMF volume fraction was 30%), the coagulation bath temperature was 35 ℃, the fiber residence time in the coagulation bath was 15 min, and the composite gel fiber was obtained after solidification.

[0036] Step (3) Constructing hollow gel fibers: Place the composite gel fibers in deionized water and sonicate them for 30 min at a power of 200 W and a temperature of 40 ℃ to selectively remove the PVP template in the core layer and obtain hollow gel fibers with a pore size of 150~200 μm.

[0037] Step (4) Preparation of flexible thermal insulation substrate: Hollow gel fibers are woven into a fabric with a thickness of 1.5 mm, which serves as the flexible thermal insulation substrate.

[0038] Step (5) Imparting low emissivity properties: Using an dip coating method, conductive silver paste (solid content of 50%) is coated on the surface of the flexible heat insulation substrate with a coating thickness of 50 μm. Then, it is cured at 120 ℃ for 30 min to form a continuous and uniform metal conductive layer, thus obtaining a hollow fiber composite fabric with infrared stealth properties.

[0039] Testing revealed that the surface resistance of the metal conductive layer in the hollow fiber composite fabric prepared in Example 3 was 20 mΩ, the infrared emissivity was 0.50, the hollow gel fiber structure was uniform, the fabric had good flexibility, excellent thermal insulation performance, and a thermal conductivity of only 0.03676 W / (m·K).

[0040] Example 4: Preparation of hollow fiber composite fabric with infrared stealth properties based on coaxial wet spinning technology: According to Example 3, the solid content of the conductive silver paste in step (5) of Example 3 was changed to 65%, and the rest were the same as in Example 3, resulting in a hollow fiber composite fabric with infrared stealth properties.

[0041] Testing revealed that the surface resistance of the metal conductive layer in the hollow fiber composite fabric prepared in Example 4 was 13 mΩ, the infrared emissivity was 0.40, the hollow gel fiber structure was uniform, the fabric had good flexibility, excellent thermal insulation performance, and a thermal conductivity of only 0.03676 W / (m·K).

[0042] Example 5: A method for preparing hollow fiber composite fabrics with infrared stealth properties based on coaxial wet spinning technology, comprising the following steps: According to Example 3, the solid content of the conductive silver paste in step (5) of Example 3 was changed to 80%, and the rest were the same as in Example 3, resulting in a hollow fiber composite fabric with infrared stealth properties.

[0043] Testing revealed that the surface resistance of the metal conductive layer in the hollow fiber composite fabric prepared in Example 5 was 8 mΩ, the infrared emissivity was 0.28, the hollow gel fiber structure was uniform, the fabric had good flexibility, excellent thermal insulation performance, and a thermal conductivity of only 0.03676 W / (m·K).

[0044] All embodiments follow a unified core preparation process, in the following order: preparing core and shell spinning solutions → preparing composite gel fibers using coaxial wet spinning → ultrasonically removing the core layer PVP template to construct hollow gel fibers → weaving the hollow gel fibers to form a flexible thermal insulation substrate → coating with conductive silver paste and curing to form a metallic conductive layer, ultimately obtaining a composite fabric with infrared stealth properties. The core technical route of each embodiment is consistent, using PVP as the core template and TPU as the shell substrate, combined with silica aerogel microspheres and phase change microcapsules to improve thermal insulation performance, and achieving infrared stealth functionality through the metallic conductive layer.

[0045] The composite fabrics prepared in each embodiment all meet the basic requirements of "uniform hollow gel fiber structure, good flexibility, and excellent thermal insulation performance". The core infrared stealth, electrical conductivity, and thermal conductivity show clear patterns as the parameters change, as detailed below: 1. Examples 1-3: When the solid content of the conductive silver paste is fixed at 50%, regardless of how other process parameters (raw material concentration, spinning speed, ultrasonic conditions, etc.) are adjusted, the surface resistance of the metal conductive layer remains at 20 mΩ, and the infrared emissivity is 0.50. This indicates that the stealth and conductivity of the core are not affected by the fluctuation of the above parameters, and the process stability is good. At the same time, as the concentration of the shell raw material increases, the hollow pore size increases, and the fabric thickness increases, the thermal insulation performance is gradually optimized, and the thermal conductivity decreases in turn. The thermal conductivity of Example 1 is 0.05876 W / (m·K), Example 2 is 0.04651 W / (m·K), and Example 3 is only 0.03676 W / (m·K), which shows that the optimization of process parameters has a significant effect on improving the thermal insulation performance.

[0046] 2. Examples 4-5: Based on Example 3, only the solid content of the conductive silver paste was increased (from 50% to 65% and 80% respectively), while other process parameters remained unchanged. The thermal conductivity remained at 0.03676 W / (m·K), consistent with the value in Example 3, indicating that the solid content of the conductive silver paste does not affect the thermal insulation performance of the fabric. Simultaneously, with the increase in the solid content of the conductive silver paste, the surface resistance of the metal conductive layer decreased from 20 mΩ to 13 mΩ and 8 mΩ, and the infrared emissivity decreased from 0.50 to 0.40 and 0.28, indicating a positive correlation between the solid content of the conductive silver paste and conductivity and infrared stealth performance; the higher the solid content, the better the infrared stealth effect. Table 1 shows a comparison of the infrared stealth parameters of the hollow fiber composite fabrics obtained in each example.

[0047] Table 1

[0048] 3. In summary, Example 1 is the basic scheme, Examples 2 and 3 are process parameter gradient optimization schemes, and Examples 4 and 5 are single-variable verification schemes, which together constitute a complete technical solution system. This system not only clarifies the stability of the core process and reveals the influence of the solid content of conductive silver paste on infrared stealth and conductivity, but also demonstrates the optimization effect of raw material concentration, hollow structure, and fabric thickness on thermal insulation performance (thermal conductivity). Appropriate process parameters can be selected according to the needs of different application scenarios (such as thin / thick fabrics, conventional / high-performance stealth, and different thermal insulation standards).

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a hollow fiber composite fabric, characterized in that, Includes the following steps: Step (1) Preparation of core spinning solution and shell spinning solution: The core spinning solution is N,N-dimethylformamide solution of polyvinylpyrrolidone; the shell spinning solution is N,N-dimethylformamide solution of thermoplastic polyurethane, silica aerogel microspheres and phase change microcapsules. Step (2) Preparation of composite gel fiber: Using coaxial wet spinning technology, the core spinning solution and shell spinning solution prepared in step (1) are simultaneously extruded and solidified in a coagulation bath to obtain composite gel fiber; Step (3) Constructing hollow gel fibers: The composite gel fibers obtained in step (2) are subjected to ultrasonic treatment to selectively remove the PVP template in the core layer and obtain hollow gel fibers. Step (4) Preparation of flexible thermal insulation substrate: The hollow gel fibers obtained in step (3) are woven into fabric as flexible thermal insulation substrate; Step (5) Imparting infrared stealth properties: The surface of the flexible heat insulation substrate obtained in step (4) is coated with conductive silver paste, and after curing, a continuous and uniform metal conductive layer is formed, resulting in a hollow fiber composite fabric with infrared stealth properties.

2. The preparation method according to claim 1, characterized in that, In step (1), the mass fraction of polyvinylpyrrolidone in the core spinning solution is 20%~60%, the stirring temperature is 20~40 ℃, and the stirring time is 2~4 h until PVP is completely dissolved.

3. The preparation method according to claim 1, characterized in that, In step (1), the mass fraction of thermoplastic polyurethane in the shell spinning solution is 8%~20%, the mass fraction of silica aerogel microspheres is 2%~8%, and the mass fraction of phase change microcapsules is 5%~12%. After the components are mixed, they are stirred at 50~70 ℃ for 3~6 h to form a uniformly dispersed spinning solution.

4. The preparation method according to claim 3, characterized in that, The phase change microcapsules have a particle size of 3 μm, and the core material is one or a mixture of two of paraffin and polyethylene glycol, while the wall material is one of melamine-formaldehyde resin and urea-formaldehyde resin.

5. The preparation method according to claim 1, characterized in that, In step (2), the spinning speed of the coaxial wet spinning is 0.5~2 mL / min, the flow ratio of the core layer to the shell layer spinning solution is 1:2~1:5; the coagulation bath is a mixed solution of deionized water and DMF, wherein the volume fraction of DMF is 10%~30%, the coagulation bath temperature is 20~35 ℃, and the residence time of the fiber in the coagulation bath is 5~15 min.

6. The preparation method according to claim 1, characterized in that, In step (3), the ultrasonic power is 80~200 W, the ultrasonic time is 10~30 min, the ultrasonic temperature is 25~40 ℃, and the ultrasonic medium is deionized water.

7. The preparation method according to claim 1, characterized in that, In step (4), the weaving method is one of machine weaving, knitting or braiding, the weaving density is 20~60 threads / cm, and the fabric thickness is 0.3~1.5 mm.

8. The preparation method according to claim 1, characterized in that, In step (5), the solid content of the conductive silver paste is 50%~80%, the coating method is one of scraping, spraying or dipping, the coating thickness is 10~50 μm, the curing temperature is 80~120℃, and the curing time is 30~90 min.

9. The preparation method according to claim 1, characterized in that, In step (5), the surface resistance of the metal conductive layer is ≤10 mΩ and the infrared emissivity is ≤0.

5.

10. A hollow fiber composite fabric prepared by the method according to any one of claims 1 to 9, characterized in that, The composite fabric uses hollow gel fiber woven fabric as the base material, and the surface of the base material is provided with a continuous and uniform metal conductive layer. The hollow pore size of the hollow gel fiber is 0.9~1 mm. The fabric has both flexible heat insulation properties and infrared stealth properties.

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