High-durability multilayer biomimetic radiative cooling fabric and preparation method and application thereof

Abstract

The present application relates to a kind of high durability multilayer biomimetic radiation refrigeration fabric and its preparation method and application, the radiation refrigeration fabric from bottom to top includes structural support layer, adhesive layer, functional scattering core layer and external protective layer in turn;The structural support layer is flexible textile base material;The adhesive layer is formed by high molecular adhesive, for connecting structural support layer and functional scattering core layer;The functional scattering core layer is porous polymer nanofiber membrane;The external protective layer is the polymer coating containing high refractive index particle;The stable interface with cross-scale physical interlocking structure is formed between the structural support layer, adhesive layer and functional scattering core layer by hot pressing.The fabric in the present application can meet the long-term use requirements under complex application scenarios while maintaining high-efficiency radiation refrigeration performance, with excellent mechanical strength, interface stability and environmental durability.

Description

Technical Field

[0001] This invention belongs to the field of functional textile materials and passive thermal management technology, and specifically relates to a highly durable multilayer biomimetic radiation cooling fabric, its preparation method and application. Background Technology

[0002] Against the backdrop of global energy transition and sustainable development, developing low-energy or even zero-energy thermal management technologies has become a common goal and urgent need across multiple technological fields. For applications exposed to solar radiation for extended periods, such as outdoor facilities, mobile equipment, building envelopes, and personal protective equipment, the temperature rise of materials caused by solar irradiation is particularly prominent. This not only directly damages their service life but also leads to enormous energy consumption for space cooling.

[0003] Passive radiative cooling technology, through spectral design, achieves high reflectivity in the solar spectrum (0.3-2.5 μm) to suppress heat absorption, while maintaining high emissivity in the atmospheric window band (8-13 μm) to enhance radiative heat dissipation into outer space, providing a feasible path to achieve zero-energy cooling. Integrating this technology into flexible substrates holds promise for wide applications in various scenarios such as outdoor textiles, deployable shading systems, building cladding, and mobile device housings. However, real-world applications place stringent comprehensive performance requirements on the materials: they must not only possess efficient and stable optical properties but also withstand repeated mechanical loads (such as folding, stretching, and friction) and the long-term effects of environmental factors such as ultraviolet radiation and temperature and humidity fluctuations.

[0004] Currently, research on flexible passive radiative cooling materials mainly relies on the following technical approaches: The electrospun porous nanofiber membrane scheme disclosed in Chinese patent CN120575388A can achieve good light scattering and infrared emission, but it generally suffers from low mechanical strength and poor structural stability, making it difficult to maintain structural integrity under actual mechanical stress. The particle-filled coating scheme disclosed in Chinese patent CN117701042B relies on high-refractive-index particles to reflect sunlight, but a high filler ratio and coating thickness easily lead to a decrease in flexibility. The multilayer photonic structure scheme disclosed in Chinese patent CN117804093A possesses precise spectral control capabilities, but it is extremely sensitive to deformation, has poor mechanical robustness, and high manufacturing costs, making it difficult to implement on flexible substrates on a large scale.

[0005] This demonstrates that the existing technological system has long suffered from a common contradiction: the difficulty in synergistically optimizing both "optical performance" and "mechanical and environmental durability." Therefore, there is an urgent need to develop a flexible radiative cooling material that is simple to manufacture, has balanced performance, and is suitable for engineering application, capable of simultaneously achieving efficient cooling and long-term durability under complex service conditions. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high-durability multilayer biomimetic radiation cooling fabric, its preparation method and application, so as to overcome the technical defects of existing flexible radiation cooling materials, such as insufficient mechanical strength, weak interlayer bonding, poor weather resistance, and easy delamination and aging under dynamic working conditions.

[0007] This invention provides a highly durable multilayer biomimetic radiation-cooling fabric. The radiation-cooling fabric has a multilayer composite structure, comprising, from bottom to top, a structural support layer, an adhesive layer, a functional scattering core layer, and an outer protective layer. The structural support layer is a flexible textile substrate. The adhesive layer is formed by a polymer adhesive and is used to connect the structural support layer and the functional scattering core layer. The functional scattering core layer is a porous polymer nanofiber membrane. The outer protective layer is a polymer coating containing high refractive index particles. The structural support layer, adhesive layer, and functional scattering core layer form a stable interface with a cross-scale physical interlocking structure through hot pressing.

[0008] Preferably, the flexible textile substrate includes, but is not limited to, one or more of polyethylene terephthalate, nylon, polypropylene, polyacrylonitrile, polyurethane, cotton, linen, silk, wool, aramid, polyimide, or polytetrafluoroethylene fiber; its structural form includes, but is not limited to, woven fabric, knitted fabric, nonwoven fabric, or braided fabric; the structural support layer, as a biomimetic keratinocyte base, mainly provides macroscopic mechanical load-bearing capacity, endows the fabric with excellent tensile strength and tear resistance, and ensures that it can withstand mechanical stress during repeated winding and folding processes.

[0009] Preferably, the polymeric adhesive includes, but is not limited to, one or more composite systems selected from waterborne polyurethane, solvent-based polyurethane, acrylic resin, epoxy resin, silicone resin, polyvinyl alcohol, polyester hot melt adhesive, ethylene-vinyl acetate copolymer (EVA), and their derivatives. This layer can melt and flow during the hot-pressing process, penetrating into the fiber gaps of the structural support layer and the nanopores of the functional scattering core layer. After curing, it forms a robust cross-scale anchoring structure, thereby ensuring interlayer bonding strength and effectively transferring mechanical stress. The thickness of the adhesive layer is 5-15 μm.

[0010] Preferably, the porous polymer nanofiber membrane is made of one or more copolymers or blends of the following polymers: 1) thermoplastic elastomers: thermoplastic polyurethane, styrene-ethylene-butene-styrene block copolymers; 2) fluoropolymers: polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene; 3) general-purpose polymers: polyacrylonitrile, polymethyl methacrylate, polystyrene, polyethylene terephthalate, polyamide; 4) biodegradable polymers: polylactic acid, cellulose acetate, polycaprolactone. The porous polymer nanofiber membrane has a thickness of 100-300 μm, an average fiber diameter distribution range of 0.3-2.5 μm, and a porosity of 50%-98%. The functional scattering core layer, as a biomimetic porous chitin network, utilizes a micro-nano scale disordered fiber network structure to efficiently reflect solar radiation through the Mie scattering effect.

[0011] Preferably, in the polymer coating containing high-refractive-index particles, the polymer is one or more of waterborne polyurethane, acrylic resin, or silicone resin; the high-refractive-index inorganic particles (refractive index typically in the range of 1.5-3.5) are selected from one or more of titanium dioxide (TiO2), zinc oxide (ZnO), aluminum oxide (Al2O3), barium sulfate (BaSO4), silicon dioxide (SiO2), aluminum nitride (AlN), silicon nitride (Si3N4), aluminum phosphate (AlPO4), or zirconium oxide (ZrO2), with a particle size distribution range of 0.15-0.4 μm. The outer protective layer, as a biomimetic chitinous hard skin layer, efficiently reflects ultraviolet and visible light using the Mie scattering principle. Simultaneously, it acts as a dense physical barrier, endowing the fabric with excellent hydrophobicity, abrasion resistance, and UV aging resistance, preventing the internal porous structure from failing due to contamination.

[0012] In this invention, the fabric has a solar reflectivity of not less than 95% in the 0.3-2.5 μm band and an infrared emissivity of not less than 90% in the 8-13 μm atmospheric window band.

[0013] This invention provides a method for preparing the above-mentioned high-durability multilayer biomimetic radiation cooling fabric, comprising the following steps:

[0014] (1) Preparation of nanofiber membranes: Porous polymer nanofiber membranes were prepared using electrospinning technology;

[0015] (2) Base fabric pretreatment and adhesive coating: The flexible textile substrate is used as a structural support layer, and a polymer adhesive is uniformly coated on its surface. Then it is dried to pre-cur it and form an adhesive layer.

[0016] (3) Hot-pressing composite: The porous polymer nanofiber membrane obtained in step (1) is covered on the adhesive layer in step (2) and hot-pressed. The temperature of the hot-pressing process is higher than the softening point of the adhesive layer and lower than the melting point of the porous polymer nanofiber membrane. Under the action of hot pressing, the polymer adhesive melts and partially penetrates into the pores at the interface of the porous polymer nanofiber membrane and the fiber gaps at the interface of the structural support layer. At the same time, the nanofiber membrane as a whole maintains its solid porous structure. After cooling, the polymer adhesive is cured and forms a cross-scale physical interlocking interface between the layers.

[0017] (4) Surface protective coating: The polymer slurry containing high refractive index particles is coated on the surface of the porous polymer nanofiber membrane after hot pressing in step (3), and then dried and cured to form an external protective layer, thereby obtaining the radiation cooling fabric.

[0018] Preferably, in step (3), the hot pressing temperature is 60-120 ℃, the pressure is 2-10 MPa, and the holding time is 30-120 s; the softening point temperature of the polymer adhesive in the adhesive layer is 60-120 ℃; these process conditions cause the adhesive layer to soften thermally and form molecular chain entanglement and penetration diffusion at the interface, thereby enhancing the interfacial bonding force.

[0019] Preferably, the coating method in step (4) is any one of scraping, spraying, dipping or screen printing.

[0020] The present invention also provides an application of the above-mentioned high-durability multilayer biomimetic radiation cooling fabric in the field of passive thermal management.

[0021] Furthermore, the applications include, but are not limited to, outdoor personal protective clothing, tents, building cooling roof coverings, interior sunshades for new energy vehicles, car covers, or roof cooling films.

[0022] Unlike traditional laminated composite materials, this invention constructs a hierarchical synergistic structure comprising a flexible structural support layer, a hot-pressed interlocking adhesive layer, a porous functional scattering core layer, and a dense outer protective layer. The flexible structural support layer bears deformation and distributes loads, adapting to winding and bending conditions. The adhesive layer, through hot-pressing and melting, penetrates into the gaps between fabric fibers and the pores of the nanofiber membrane at the interface, solidifying to form a mechanically interlocking interface, enhancing interlayer bonding and suppressing warping and delamination. The functional scattering core layer relies on a disordered nanofiber network to achieve bulk multiple scattering, obtaining broadband high solar reflectance while maintaining high mid-infrared emissivity. The outer protective layer reinforces short-wave scattering and provides wear-resistant, anti-fouling, and weather-resistant barriers, protecting the stability of the porous network structure and suppressing optical attenuation. This structure, biomimetic to the hierarchical architecture of white-spotted longhorn beetle scales, achieves decoupling and synergistic gain between optical control and structural load-bearing, thus balancing radiative cooling effects, flexibility, and long-term service stability.

[0023] Beneficial effects

[0024] (1) Excellent optical performance: Through the synergistic effect of the external protective layer and the functional scattering core layer, this invention achieves efficient reflection (reflectivity ≥ 95%) in the main bands of the solar spectrum and efficient radiation (emissivity ≥ 90%) in the atmospheric window band, with optical performance significantly better than that of single structural materials.

[0025] (2) Strong interface bonding: The present invention uses hot pressing process to form a cross-scale physical interlocking structure between adhesive layers. After 1000 tape peeling cycles test, there is no delamination phenomenon, which effectively solves the technical problem of weak interface bonding of cross-scale multi-layer materials.

[0026] (3) Good environmental durability: The external protective layer in this invention provides an effective protective barrier. After 500 hours of ultraviolet aging and 1000 wear tests, the optical performance retention rate exceeds 94%, which is reliable for long-term outdoor use.

[0027] (4) Excellent process compatibility: The linear electrospinning, coating and hot pressing processes involved in this invention are all compatible with existing roll-to-roll industrial production lines and have the potential for large-scale industrial production.

[0028] (5) Wide range of applications: The high-durability multilayer biomimetic radiation cooling fabric of the present invention can be applied to outdoor protective equipment, building energy-saving materials and new energy vehicle thermal management components. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the fabric structure in Example 1.

[0030] Figure 2 This is a SEM image of the fabric cross-section in Example 1.

[0031] Figure 3 The image shows a comparison of the reflectance spectra of the fabrics in Example 1, Comparative Example 3, and Comparative Example 4 in the solar radiation band.

[0032] Figure 4 The image shows a comparison of the mid-infrared emissivity spectra of the fabrics in Example 1, Comparative Example 3, and Comparative Example 4.

[0033] Figure 5 This is the reflectance spectrum of the fabric after aging test in Example 1.

[0034] Figure 6 The images show the contact angle test diagram and self-cleaning experiment diagram of the fabric in Example 1.

[0035] Figure 7 This is a comparison chart of the actual vehicle test temperature curves of the fabric in Example 1.

[0036] Figure 8This is a comparison diagram of the stress-strain curves of the fabrics in Example 1 and Comparative Example 1.

[0037] Figure 9 This is a comparison curve of the peel force test of the fabrics in Example 1 and Comparative Example 2.

[0038] Figure 10 These are comparative photos of the tape peeling tests on the fabrics in Example 1 and Comparative Example 4.

[0039] Reference numerals: 1-Outer protective layer, 2-Functional scattering core layer, 3-Adhesive layer, 4-Structural support layer. Detailed Implementation

[0040] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0041] The following embodiments of this invention highlight the application of highly durable multilayer biomimetic radiative cooling fabrics in the thermal management of new energy vehicles. This does not imply that the application scope of this invention is limited to the automotive field. The fabrics of this invention are also applicable to a wide range of fields, including building energy conservation (cool roofs, awnings), outdoor personal protection (sunscreen clothing, tents), cold chain logistics (heat insulation covers), and modern agriculture (greenhouse coverings). Any cross-domain application based on the core structure and process of this invention falls within the protection scope of this invention.

[0042] Example 1

[0043] A highly durable multilayer biomimetic radiation-cooling fabric, the preparation method of which includes the following steps:

[0044] (1) Preparation of nanofiber membrane: 15 g of thermoplastic polyurethane (TPU, hardness 95 A) particles were dissolved in 85 g of N,N-dimethylformamide (DMF) / tetrahydrofuran (THF) mixed solvent (volume ratio 1:1) and ultrasonically dispersed to obtain a spinning solution. Using a single-needle electrospinning device with a voltage of 11 kV, a receiving distance of 15 cm, an ambient temperature of 25 ℃, and a humidity of 45%, a porous TPU nanofiber membrane with a thickness of about 100 μm and a fiber diameter distribution of 0.3-0.8 μm was prepared.

[0045] (2) Base fabric pretreatment and adhesive coating: High-strength polyethylene terephthalate (PET) knitted fabric was selected as the structural support layer. Water-based polyurethane (WPU) adhesive was uniformly coated on its surface using a doctor blade coating process, with the coating amount controlled at 40 g / m². 2Then it is dried and pre-cured to form an adhesive layer.

[0046] (3) Hot-pressing composite: The TPU nanofiber membrane obtained in step (1) is applied to the adhesive layer obtained in step (2), and then placed in a flat vulcanizing machine for hot-pressing. Key process parameters: The hot-pressing temperature is set at 80 ℃ (higher than the activation temperature of WPU adhesive, lower than the melting point temperature of TPU fiber), the pressure is 3 MPa, and the holding time is 60 s. Under these conditions, the adhesive melts and penetrates directionally into the pores of the nanofiber membrane and the fiber gaps of the structural support layer, while keeping the nanofiber skeleton from melting and collapsing; after cooling and curing, the cured adhesive forms an anchoring structure between the layers, constructing a cross-scale physical interlocking interface.

[0047] (4) Construction of surface protective coating: 30 g of rutile TiO2 nanoparticles (particle size 0.25 μm) were dispersed in 70 g of waterborne polyurethane (WPU) emulsion, and appropriate amounts of leveling agent and defoamer were added. The mixture was stirred at high speed for 30 min to obtain a protective slurry. The slurry was uniformly coated onto the surface of the composite TPU nanofiber membrane by screen printing or blade coating, and then cured in an 80 ℃ forced-air drying oven for 30 min to form an external protective layer with a thickness of about 45 μm.

[0048] The resulting biomimetic graded radiation cooling fabric has a core layer (TPU fiber layer) to shell layer (coating) thickness ratio of approximately 2.2:1, which highly simulates the structural proportions of longhorn beetle scales.

[0049] Figure 1 The diagram shows the fabric structure prepared in Example 1. The fabric structure consists of a structural support layer 4, an adhesive layer 3, a functional scattering core layer 2, and an outer protective layer 1 arranged sequentially from bottom to top. The thickness of the functional scattering core layer 2 is 100-300 μm, and the thickness of the outer protective layer 1 is 40-120 μm.

[0050] Figure 2 The image shows a cross-sectional SEM image of the fabric prepared in Example 1. A clear three-layer structure is visible in the image: a bottom layer of micron-sized PET fiber skeleton, a middle layer of porous TPU nanofiber network, and a top layer of dense TiO2 / WPU coating.

[0051] Figure 3 This is a comparison of the reflectance spectra of various fabrics in the solar radiation band. As can be seen from the figure, Example 1 has an average reflectance of 98.7% in the visible light band and 96.4% in the full solar spectrum.

[0052] Figure 4The figure shows a comparison of the emissivity spectra of various fabrics in the mid-infrared band. As can be seen from the figure, the average emissivity of Example 1 in the mid-infrared band is 94.2%, which is significantly higher than that of the fabrics prepared in Comparative Examples 3 and 4.

[0053] Figure 5 This is a comparison of the solar radiation reflectance spectra of various fabrics after aging tests. As shown in the figure, after 1000 cycles of reciprocating rubbing with a nylon brush, the fabric surface coating remained intact, without damage or chalking, and the average reflectance in the visible light band was 94.7%. In the UV aging chamber (UVA-340 lamp, 0.89 W / m²), the reflectance was also satisfactory. 2 After 500 hours of irradiation, the sample did not show yellowing, embrittlement or delamination, and the average reflectance in the visible light band was 94.8%. After undergoing high and low temperature damp heat cycling (50 cycles) from -20 ℃ to 80 ℃, the morphology of the sample remained basically unchanged, and the average reflectance in the visible light band was 92.5%.

[0054] Figure 6 Photographs of the contact angle of the fabric prepared in Example 1 and experimental diagrams of the self-cleaning test: As can be seen from the figures, the water contact angle of the fabric surface is 102.377°. After the simulated pollution test, it can be restored to whiteness with just a simple water rinse.

[0055] Figure 7 The temperature curve comparison chart shows the fabric prepared in Example 1 being used in a Tesla Model 3 exterior vehicle exterior covering test. The test conditions were midday in summer (ambient temperature approximately 25 °C, solar irradiance approximately 700 W / m²). 2 The fabric prepared in Example 1 was cut and sewn into a car cover, which was then applied to the roof and windows of the vehicle. As shown in the figure, compared to an unprotected vehicle (where the interior air temperature soars to over 65 °C), the interior air temperature of the vehicle covered with the fabric was reduced by an average of 7.73 °C. Compared to a vehicle covered with a commercially available aluminized film car cover, the fabric of Example 1 further reduced the interior temperature by 2.34 °C, demonstrating its potential for efficient thermal management in real-world vehicle environments.

[0056] Comparative Example 1

[0057] A traditional nanofiber radiation cooling membrane is prepared by the following steps:

[0058] 1) Dissolve 15 g of thermoplastic polyurethane (TPU, hardness 95A) in 85 g of DMF / THF mixed solvent (volume ratio 1:1) and stir magnetically at 80 °C for 12 h to obtain a uniform and transparent spinning solution.

[0059] 2) The obtained spinning solution was electrospun at a spinning voltage of 11 kV, a receiving distance of 15 cm, a feed rate of 1.0 mL / h, an ambient temperature of 25 ℃, and a humidity of 45%. The nanofiber membrane was directly collected through a roller receiving device, and the spinning time was 6 h, resulting in a pure TPU nanofiber membrane with a thickness of approximately 100 μm.

[0060] Figure 8 The figure shows a comparison of the stress-strain curves of the fabrics prepared in Example 1 and Comparative Example 1. As can be seen from the figure, the tensile strength of Comparative Example 1 is only about 0.8 MPa, and it exhibits obvious yielding behavior; while the tensile strength of Example 1 is as high as 23.5 MPa, and the elongation at break exceeds 150%. This indicates that the introduction of a PET structural support layer combined with the hot pressing process greatly enhances the mechanical strength of the material.

[0061] Comparative Example 2

[0062] A method for preparing an adhesive-free laminated composite fabric includes the following steps:

[0063] 1) TPU nanofiber membranes were prepared using the same method as in Comparative Example 1;

[0064] 2) White PET knitted fabric is selected as the base fabric;

[0065] 3) Omit the adhesive coating step and lay the TPU nanofiber film directly on the PET base fabric. Perform simple hot-pressing at 100 ℃ (pressure 3 MPa, time 60 s).

[0066] Figure 9 The peel force test curves of the fabrics prepared in Example 1 and Comparative Example 2 are shown. It can be seen that the peel force of Comparative Example 2 is extremely low (<0.1 N / mm), with almost no interlayer bonding force; while the peel force curve of Example 1 shows a high and stable plateau region, and the interface can effectively resist interlayer separation, meeting the requirements of dynamic service.

[0067] Comparative Example 3

[0068] A coated fabric with an intermediate nanofiber layer removed is prepared by the following steps:

[0069] 1) The same white PET knitted fabric as in Example 1 was selected as the base fabric;

[0070] 2) Omitting the nanofiber membrane layer and its composite steps, the WPU protective slurry containing TiO2 high refractive index particles prepared in Example 1 is directly coated onto the surface of the PET base fabric by a scraping method.

[0071] 3) Dry and cure in an 80 ℃ oven to form a single-coated fabric with a thickness of about 50 μm.

[0072] Depend on Figures 3-4 It can be seen that the average reflectance of the fabric in Comparative Example 3 is only 76.9% in the visible light band, only 72.3% in the full solar spectrum, and 91.1% in the mid-infrared band.

[0073] Comparative Example 4

[0074] The specific steps of preparing a double-layer composite fabric with the top protective coating removed are as follows:

[0075] 1) The same white PET knitted fabric as in Example 1 was used as the base fabric, and the same WPU adhesive was applied;

[0076] 2) The TPU nanofiber membrane is laminated onto the base fabric using the same hot-pressing process as in Example 1 to form a PET / TPU bilayer structure;

[0077] 3) The surface protective coating construction step is omitted, and an uncoated nanofiber composite fabric is obtained directly.

[0078] Depend on Figures 3-4 It can be seen that the average reflectance of the fabric in Comparative Example 4 is only 88.7% in the visible light band, only 86.9% in the full solar spectrum, and 89.8% in the mid-infrared band.

[0079] Figure 10 The images show comparative photos of the fabrics after the tape peel test. As can be seen from the figures, the porous structure of Comparative Example 4 was damaged or even detached after 10 3M tape peel tests; while the surface coating of the fabric in Example 1 remained intact and showed no obvious wear after 1000 3M tape peel tests.

[0080] Example 2

[0081] A weather-resistant, radiation-cooling fabric based on a fluoropolymer, the preparation method of which includes the following steps:

[0082] PVDF-HFP nanofiber membranes (100 μm thick) were prepared by electrospinning after dissolving polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) in acetone / DMAc solvent.

[0083] 1) Select white nylon (PA6) fabric as the base material and coat it with an acrylic adhesive;

[0084] 2) Hot pressing composite was carried out at 100 ℃ and 4 MPa to construct the interlocking interface between PVDF-HFP nanofibers and PA6 substrate.

[0085] 3) Disperse alumina (Al2O3) particles with a particle size of 0.3 μm in an aqueous polyurethane resin emulsion, coat the surface and cure.

[0086] Tests showed that the fabric in Example 2 had an average reflectance of 94.2% in the visible light band, 92.1% in the full solar spectrum, and an average emissivity of 90.5% in the mid-infrared band. Regarding chemical corrosion resistance, the fabric was immersed in a 5% (w / w) salt spray solution, a 0.1 mol / L hydrochloric acid solution, and a 0.1 mol / L sodium hydroxide solution for 20 hours each. No blistering, cracking, discoloration, or other corrosive damage was observed on the surface, and the tensile strength retention rate reached 90.5%. In terms of UV stability, in a UV aging chamber (UVA-340 lamp, 0.89 W / m²), the fabric exhibited good performance. 2 After 500 hours of irradiation, the sample did not show yellowing, embrittlement or delamination, and the tensile strength retention rate reached 86.2%.

[0087] The fabric prepared in this embodiment has good chemical corrosion resistance and UV stability, and is suitable for extreme outdoor environments (such as high altitude and strong UV areas).

[0088] Example 3

[0089] A biodegradable radiation cooling fabric, the preparation method of which includes the following steps:

[0090] 1) Polylactic acid (PLA) was dissolved in a dichloromethane / DMF mixed solvent, and PLA nanofiber membranes with a thickness of about 120 μm were prepared by electrospinning.

[0091] 2) Select cotton fabric as the base fabric and coat its surface with bio-based polyurethane adhesive;

[0092] 3) The PLA nanofiber membrane is bonded to the coated cotton fabric and hot-pressed at 85 ℃ and 3 MPa to form an environmentally friendly interlocking interface.

[0093] 4) Modified cellulose nanocrystals (CNC) with a particle size of 0.25 μm were used as high refractive index fillers, dispersed in biodegradable polyester emulsion, and coated on the surface to form a protective layer.

[0094] Tests showed that the fabric in Example 3 had an average reflectance of 93.2% in the visible light band, 91.3% in the full solar spectrum, and an average emissivity of 92.2% in the mid-infrared band.

[0095] The fabric prepared in this embodiment has good biocompatibility and biodegradability, and is suitable for fields with high environmental protection requirements, such as outdoor camping tents, parasols, and disposable cold chain packaging.

[0096] Example 4

[0097] A high-temperature resistant and flame-retardant radiation cooling fabric, the preparation method of which includes the following steps:

[0098] A high-temperature resistant PI nanofiber membrane with a thickness of approximately 80 μm was prepared by electrospinning a polyimide (PI) precursor solution and then subjecting it to thermal imidization.

[0099] 1) Aramid fabric is selected as the base fabric and coated with a high-temperature resistant silicone adhesive;

[0100] 2) The PI nanofiber membrane and aramid base fabric were hot-pressed together at 150 ℃ and 6 MPa.

[0101] 3) Disperse 0.3 μm zirconium oxide (ZrO2) and titanium dioxide (TiO2) mixed particles in organosilicon resin, coat the surface and cure at high temperature.

[0102] Tests showed that the fabric in Example 4 had an average reflectance of 95.1% in the visible light band, 93.5% in the full solar spectrum, and an average emissivity of 93.8% in the mid-infrared band. Regarding heat resistance, after being placed in a constant temperature environment of 200℃ for 24 hours, the fabric showed no melting, deformation, or embrittlement, and its tensile breaking strength retention rate reached 92.3%. In terms of flame retardancy, the fabric had a limiting oxygen index (LOI) ≥38%, a vertical burning damage length ≤8 cm, and no afterflame, meeting the Class B flame retardant requirements of GB 8965.1-2020.

[0103] The fabric prepared in this embodiment has good heat resistance and flame retardancy, and is suitable for scenarios such as heat insulation layers of fire suits and thermal protection of special vehicles.

[0104] In summary, this invention, mimicking the "flexible skeleton-porous scattering core-tough outer shell" configuration of white-spotted longhorn beetle scales, achieves highly efficient reflection (96.4%) in the solar spectrum (0.3-2.5 μm) and highly efficient emission (94.2%) in the mid-infrared spectrum (2.5-25 μm) through the synergistic effect of the coating particles and fiber network. Furthermore, the interlayer bonding strength and mechanical durability (tensile strength exceeding 20 MPa) are significantly enhanced through a thermo-pressed interlocking interface. This fabric possesses excellent radiative cooling properties, abrasion and weather resistance, and flexibility, making it particularly suitable for all-weather car covers or sunshades for new energy vehicles, effectively reducing high temperatures during parking and air conditioning energy consumption.

Claims

1. A highly durable multilayer biomimetic radiation cooling fabric, characterized in that, The radiation-cooling fabric comprises, from bottom to top, a structural support layer, an adhesive layer, a functional scattering core layer, and an outer protective layer; the structural support layer is a flexible textile substrate; the adhesive layer is formed by a polymer adhesive and is used to connect the structural support layer and the functional scattering core layer; the functional scattering core layer is a porous polymer nanofiber membrane; the outer protective layer is a polymer coating containing high refractive index particles; the structural support layer, adhesive layer, and functional scattering core layer form a stable interface with a cross-scale physical interlocking structure through hot pressing.

2. The high-durability multilayer biomimetic radiation cooling fabric according to claim 1, characterized in that, The flexible textile substrate includes one or more of polyethylene terephthalate, nylon, polypropylene, polyacrylonitrile, polyurethane, cotton, linen, silk, wool, aramid, polyimide, or polytetrafluoroethylene fiber.

3. The high-durability multilayer biomimetic radiation cooling fabric according to claim 1, characterized in that, The polymeric adhesive comprises one or more composite systems selected from waterborne polyurethane, solvent-based polyurethane, acrylic resin, epoxy resin, silicone resin, polyvinyl alcohol, polyester hot melt adhesive, ethylene-vinyl acetate copolymer and its derivatives; the thickness of the adhesive layer is 5-15 μm.

4. The high-durability multilayer biomimetic radiation cooling fabric according to claim 1, characterized in that, The porous polymer nanofiber membrane is made of one or more copolymers or blends of the following polymers: 1) thermoplastic elastomers: thermoplastic polyurethane, styrene-ethylene-butene-styrene block copolymers; 2) fluoropolymers: polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene; 3) general polymers: polyacrylonitrile, polymethyl methacrylate, polystyrene, polyethylene terephthalate, polyamide; 4) biodegradable polymers: polylactic acid, cellulose acetate, polycaprolactone; the porous polymer nanofiber membrane has a thickness of 100-300 μm, an average fiber diameter distribution range of 0.3-2.5 μm, and a porosity of 50%-98%.

5. The high-durability multilayer biomimetic radiation cooling fabric according to claim 1, characterized in that, In the polymer coating containing high refractive index particles, the polymer is one or more of waterborne polyurethane, acrylic resin, or silicone resin; the high refractive index inorganic particles are one or more of titanium dioxide, zinc oxide, aluminum oxide, barium sulfate, silicon dioxide, aluminum nitride, silicon nitride, aluminum phosphate, or zirconium oxide, and their particle size distribution ranges from 0.15 to 0.4 μm.

6. A method for preparing a high-durability multilayer biomimetic radiation-cooling fabric as described in claim 1, comprising the following steps: (1) Prepare porous polymer nanofiber membranes using electrospinning technology; (2) A flexible textile substrate is used as a structural support layer, and a polymer adhesive is uniformly coated on its surface. Then it is dried to pre-cur it and form an adhesive layer. (3) The porous polymer nanofiber membrane obtained in step (1) is covered on the adhesive layer in step (2) and subjected to hot pressing treatment; the temperature of the hot pressing treatment is higher than the softening point of the adhesive layer and lower than the melting point of the porous polymer nanofiber membrane. (4) A polymer slurry containing high refractive index particles is coated onto the surface of the porous polymer nanofiber membrane after hot pressing in step (3), and then dried and cured to form an external protective layer, thereby obtaining a radiation cooling fabric.

7. The preparation method according to claim 6, characterized in that, In step (3), the hot pressing temperature is 60-120 ℃, the pressure is 2-10 MPa, and the holding time is 30-120 s.

8. The preparation method according to claim 6, characterized in that, The coating method in step (4) is any one of scraping, spraying, dipping or screen printing.

9. The application of the high-durability multilayer biomimetic radiation cooling fabric as described in claim 1 in the field of passive thermal management.

10. The application according to claim 9, characterized in that, The applications include outdoor personal protective clothing, tents, building cooling roof coverings, interior sunshades for new energy vehicles, car covers, or roof cooling films.

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