A double-layer micro-nano fiber fabric with daytime cooling function and a preparation method thereof

Abstract

The application discloses a double-layer micro-nano fiber fabric with a daytime cooling function and a preparation method thereof. Micro-nano fiber yarn is prepared through micro-nano fiber spinning technology, and then the micro-nano fiber yarn is knitted into a double-layer micro-nano fiber fabric. In the double-layer micro-nano fiber fabric, the warp yarns of the lower fabric correspond to the gaps between two adjacent warp yarns in the upper fabric, and the weft yarns of the lower fabric correspond to the gaps between two adjacent weft yarns in the upper fabric. The upper fabric has hydrophilicity, high mid-infrared emission and high thermal conductivity, and the lower fabric has hydrophobicity, high mid-infrared emission and high thermal conductivity. The lower fabric contains hydrophilic contact points. The special double-layer fabric structure design, micro-nano fiber size structure distribution and material-specific radiation cooling performance make the fabric integrate multiple cooling paths such as daytime radiation cooling, evaporation heat absorption and heat conduction, which not only helps to improve the cooling performance, but also is soft and wearable, and can be applied to human body cooling under outdoor strong sunlight irradiation conditions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional textiles, and relates to a double-layer micro-nano fiber fabric with daytime cooling function and a preparation method thereof, in particular to a double-layer micro-nano fiber fabric prepared by micro-nano fiber spinning technology and weaving technology. BACKGROUND

[0002] At present, global warming, especially high-temperature weather with strong sunlight in summer, causes serious distress to people's outdoor life and work, and thus textile and clothing products with daytime cooling function are in urgent need. In outdoor activities, the human body mainly offsets heat input through four different heat dissipation ways, i.e. heat radiation, heat conduction, heat convection and evaporation, to maintain the human body thermal steady state. When the skin temperature exceeds 35℃, sweat evaporation is the main heat dissipation way of the human body. Therefore, based on the above four heat dissipation ways, researchers have developed radiation cooling textiles, high-thermal-conductivity textiles, thermal evaporation textiles and thermal convection textiles to meet the personal thermal comfort in different ranges and different situations. For example, radiation cooling textiles mainly have selective spectral regulation, which can send heat in the form of infrared radiation to the natural cold source, outer space, to achieve cooling; high-thermal-conductivity textiles mainly rely on the high thermal conductivity of the material itself to improve the thermal conductivity of the textile to achieve cooling effect; thermal evaporation textiles mainly use the moisture absorption capacity of the material to achieve cooling effect by rapid evaporation of water; thermal convection textiles achieve cooling effect by increasing the contact space between the textile and the skin to accelerate air convection. The above four textiles have achieved different degrees of cooling effect, but the heat dissipation ways are relatively single and the daytime cooling performance is poor. In order to further improve the cooling effect and the application environment of the textile, cooling textiles combining multiple heat dissipation ways have been studied, such as thermal conduction and thermal evaporation synergistic cooling textiles, radiation cooling and thermal evaporation synergistic cooling textiles, etc. Although the cooling effect of textiles combining multiple cooling ways is greatly improved, the preparation process is complicated, the cost is high, and the textile made of composite metal material is not comfortable to wear. Therefore, flexible fabric with simple process and high-efficiency daytime cooling function has important research value and market application potential. SUMMARY

[0003] In view of the limitations of existing cooling textiles, the present application provides a double-layer micro-nano fiber fabric with daytime cooling function and a preparation method thereof, i.e. first preparing micro-nano fiber yarns by micro-nano fiber spinning technology, then weaving the micro-nano fiber yarns into double-layer micro-nano fiber fabric, and applying the double-layer micro-nano fiber fabric to the field of daytime cooling textiles.

[0004] To solve the above technical problems, the present application adopts the following technical solutions:

[0005] The double-layer micro-nano fiber fabric with daytime cooling function has a double-layer structure, namely the double-layer micro-nano fiber fabric comprises an upper fabric and a lower fabric; the double-layer micro-nano fiber fabric is directly woven by designing fabric organization structure, or is sewn by two single-layer fabrics; the upper fabric and the lower fabric are both plain weave structures, wherein the warp yarns of the lower fabric correspond to the gaps between adjacent two warp yarns in the upper fabric, and the weft yarns of the lower fabric correspond to the gaps between adjacent two weft yarns in the upper fabric.

[0006] Further, the upper fabric is woven by middle infrared emission and hydrophilic, heat-conducting yarns; the lower fabric is woven by middle infrared emission and hydrophobic, heat-conducting yarns; for the double-layer fabric directly woven, part of the warp yarns or (and) weft yarns in the upper fabric regularly shuttle in the lower fabric, and all the warp yarns and weft yarns in the lower fabric cannot appear in the upper fabric; for the double-layer fabric sewn, the sewing line is the same as the yarns in the upper fabric, and regularly passes through the upper and lower fabrics.

[0007] Further, the yarns in the fabric are all micro-nano fiber yarns, which can be single yarns or strands, the yarn diameter is distributed in 10-1000 μm, and the yarns have certain mechanical properties, the breaking elongation is greater than 5%, and the breaking strength is greater than 10 MPa; the micro-nano fiber yarns are prepared by micro-nano fiber spinning technology; the micro-nano fiber spinning technology is any one of wet electrospinning, airflow spinning or melt-blow spinning, namely first stretching the polymer solution or melt into micro-nano fibers by electrostatic or airflow, and then gathering and twisting the micro-nano fibers into yarns or strands.

[0008] Further, the micro-nano fibers can have conventional structure, or have convex structure or porous structure, the fiber diameter is distributed in 0.2-2.5 μm, the fiber surface convex diameter is 0.2-2.5 μm, and the fiber hole diameter is 0.2-2.5 μm. The polymer solution or melt is a single high molecular polymer or a mixture of one or more functional factors and high molecular polymers.

[0009] The application further provides a preparation method of the double-layer micro-nano fiber fabric with daytime cooling function, which specifically comprises the following steps:

[0010] (1) dissolving middle infrared emission and hydrophilic polymer or a mixture of middle infrared emission and hydrophilic polymer and functional factors in a solvent, stirring at 25-100 ℃ for 1-24 h to obtain a polymer spinning solution A with a mass fraction of 5%-50%;

[0011] (2) Dissolve a mid-infrared emitting and hydrophobic polymer or a mid-infrared emitting and hydrophobic polymer and a functional factor together in a solvent and stir at 25-100℃ for 1-24h to obtain a polymer spinning solution B with a mass fraction of 5%-50%.

[0012] (3) Place the polymer spinning solution A from step (1) into the feeding system of the conjugate electrospinning device, and use the conjugate electrospinning method to prepare cellulose acetate micro-nano fiber single yarn, and then twist the single yarn into a ply yarn A.

[0013] (4) Place the polymer spinning solution B from step (2) into the feeding system of the conjugate electrospinning device, and use the conjugate electrospinning method to prepare polyvinylidene fluoride micro-nano fiber single yarn, and then twist the single yarn into a ply yarn B.

[0014] (5) Weave the strands B from step (4) into a lower plain weave fabric;

[0015] (6) Weave another layer of fabric, namely the upper plain weave fabric, on top of the lower plain weave fabric in step (5) using the strand A in step (3). The lower plain weave fabric contains the yarn contact points in the upper plain weave fabric, thereby obtaining a double-layer micro-nano fiber fabric with daytime cooling function.

[0016] Furthermore, the ply yarn A in step (3) is woven into an upper plain weave fabric and stacked with the lower plain weave fabric obtained in step (5) in an alternating manner, that is, the warp yarns in the upper plain weave fabric are in the gap between the two warp yarns of the lower plain weave fabric. Then, the ply yarn A in step (3) is used to shuttle between the upper and lower plain weave fabrics to form a double-layer fabric. The lower plain weave fabric contains the yarn contact points of the upper plain weave fabric, thus obtaining a double-layer micro-nano fiber fabric with daytime cooling function.

[0017] Furthermore, the mid-infrared emitting and hydrophilic polymers include cellulose acetate, fluorinated polyethylene, and polyvinyl alcohol; the mid-infrared emitting and hydrophobic polymers include polyvinylidene fluoride, polyurethane, and polylactic acid.

[0018] Furthermore, the solvent in step (1) is deionized water, dichloromethane, chloroform, tetrahydrofuran (THF), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), acetone, or a mixture of THF and DMF, or a mixture of DMAC and acetone.

[0019] Furthermore, the functional factors are thermally conductive factors, cooling factors, highly reflective photons, or highly emitted photons; the thermally conductive factors include graphene sheets, carbon nanotubes, silver nanoparticles, etc.; the cooling factors include menthol microcapsules, isocyanates, silk protein cooling finishing agents, etc.; the highly reflective photons include zinc oxide nanoparticles (ZnO), titanium dioxide (TiO2), calcium carbonate, etc.; the highly emitted photons include silicon dioxide, silicon nitride (Si3N4), silicon oxynitride, etc.

[0020] The present invention also provides the application of the micro / nano fiber fabric in the field of daytime cooling textiles.

[0021] The beneficial effects of this invention are as follows: First, the special double-layer fabric structure design, the micro-nano fiber size distribution, and the material's unique mid-infrared emission properties give it high solar reflectivity and radiative cooling properties, thereby achieving daytime radiative cooling. Second, the hydrophilic and hydrophobic properties of the double-layer fabric and the hydrophilic yarn contacts running through the lower layer allow it to effectively absorb sweat and quickly transport it from the hydrophobic layer (lower layer) to the hydrophilic layer (upper layer), thus achieving evaporative cooling. Third, the double-layer micro-nano fiber fabric prepared by this invention has multiple heat dissipation and cooling pathways, including daytime radiative cooling, evaporative heat absorption, and thermal conductivity, making it suitable for cooling the human body under strong sunlight conditions outdoors. Fourth, the process is simple and requires no secondary processing. Attached Figure Description

[0022] Figure 1 A schematic diagram of the structure of a double-layer micro / nano fiber fabric.

[0023] Figure 2 The results of the change in surface temperature of the skin and fabric over time when the double-layered fabric was applied to human skin under direct sunlight in Example 1.

[0024] Figure 3 The results of the change in surface temperature of the skin and fabric over time when the double-layered fabric was applied to human skin under direct sunlight outdoors in Example 2.

[0025] Figure 4 The results of the change in surface temperature of the skin and fabric over time when the double-layered fabric was applied to human skin under direct sunlight outdoors in Example 3.

[0026] Figure 5 The results of the change in surface temperature of the skin and fabric over time when the double-layered fabric was applied to human skin under direct sunlight outdoors in Example 4. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above-described invention.

[0028] Example 1

[0029] The preparation steps of a double-layer micro / nano fiber fabric with daytime cooling function in this embodiment are as follows:

[0030] (1) Dissolve cellulose acetate polymer in a mixed solvent (DMAC and acetone in a mass ratio of 1:2) and stir for 3 hours to obtain a cellulose acetate spinning solution with a mass fraction of 13%.

[0031] (2) Dissolve the polyvinylidene fluoride polymer in a mixed solvent (DMF and THF in a mass ratio of 1:1) and stir at 80°C for 8 hours to obtain a polyvinylidene fluoride spinning solution with a mass fraction of 10%.

[0032] (3) Place the cellulose acetate spinning solution from step (1) into the feeding system of the conjugate electrospinning device, and prepare cellulose acetate micro-nano fiber single yarn by conjugate electrospinning. Then twist the single yarn into a ply.

[0033] (4) Place the polyvinylidene fluoride spinning solution from step (2) into the feeding system of the conjugate electrospinning device, prepare polyvinylidene fluoride micro-nano fiber single yarn using the conjugate electrospinning method, and then twist the single yarn into a ply.

[0034] (5) Weave the polyvinylidene fluoride micro-nano fiber strands from step (4) into a plain weave single-layer fabric.

[0035] (6) Weave another layer of fabric on top of the single-layer polyvinylidene fluoride plain weave fabric in step (5) with the cellulose acetate micro-nano fiber strands in step (3). It is required that some of the warp yarns of the upper fabric are regularly shuttled in the lower fabric, so as to obtain a double-layer micro-nano fiber fabric with cellulose acetate on the upper layer and polyvinylidene fluoride on the lower layer. The lower polyvinylidene fluoride fabric contains the cellulose acetate yarn contacts in the upper fabric, thus obtaining a double-layer micro-nano fiber fabric with daytime cooling function.

[0036] like Figure 2 As shown, under outdoor sunlight (outdoor temperature 39℃), when the double-layer micro / nano fiber fabric obtained in Example 1 was applied to the surface of human skin for temperature monitoring, an average skin surface temperature reduction of 10.28℃ was achieved.

[0037] Example 2

[0038] The preparation steps of a double-layer micro / nano fiber fabric with daytime cooling function in this embodiment are as follows:

[0039] (1) Hydrophilic silica (SiO2) was ultrasonically dispersed in a mixed solvent (DMAC and acetone in a mass ratio of 1:2) and stirred for 0.5 h. Then, cellulose acetate (CA) polymer was added and stirred at room temperature for 8 h to obtain a CA / SiO2 spinning solution, wherein the mass concentration of CA was 13%, the mass concentration of SiO2 was 20%, and the particle size of SiO2 was 500 nm.

[0040] (2) Polyvinylidene fluoride (PVDF) polymer and silver nanosheets were dissolved in a mixed solvent (DMF and THF mass ratio 1:1) and stirred at 80°C for 8 hours to obtain a PVDF / Ag spinning solution. The mass concentration of PVDF was 10% and the mass concentration of silver nanoparticles was 28%.

[0041] (3) Place the CA / SiO2 spinning solution from step (1) into the feeding system of the wet electrospinning device, prepare CA / SiO2 micro / nano fiber single yarn using the wet electrospinning method, and then twist the single yarn into a ply.

[0042] (4) Place the PVDF / Ag spinning solution from step (2) into the feeding system of the wet electrospinning device, prepare PVDF / Ag micro / nano fiber single yarn using the wet electrospinning method, and then twist the single yarn into a ply.

[0043] (5) Weave the PVDF / Ag micro-nano fiber strands from step (4) into a plain weave single-layer fabric.

[0044] (6) The CA / SiO2 micro / nano fiber strands from step (3) are woven into another layer of fabric above the PVDF / Ag fabric. The warp yarns of the upper fabric are required to regularly weave through the lower fabric, thus obtaining a double-layer micro / nano fiber fabric with CA / SiO2 as the upper layer and PVDF / Ag as the lower layer. The lower PVDF / Ag fabric contains CA / SiO2 yarn contacts from the upper fabric. This yields a double-layer micro / nano fiber fabric with daytime cooling function. The test results of the relevant properties of the double-layer fabric in Example 2 are shown in Table 1.

[0045] Table 1. Test results of relevant properties of the double-layer fabric in Example 2.

[0046]

[0047] like Figure 3 As shown, under outdoor sunlight (outdoor temperature 39°C), the double-layer micro-nano fiber fabric obtained in Example 2 was used to cover the surface of human skin for temperature monitoring, and the average temperature drop of the skin surface was 11.12°C.

[0048] Example 3

[0049] The preparation steps of a double-layer micro / nano fiber fabric with daytime cooling function in this embodiment are as follows:

[0050] (1) Dissolve polylactic acid (PLA) polymer in chloroform and stir at 60°C for 12 h to obtain a PLA spinning solution with a mass fraction of 15%.

[0051] (2) Polyvinylidene fluoride (PVDF) polymer and silver nanoparticles were dissolved in a mixed solvent (DMF and THF mass ratio 1:1) and stirred at 80°C for 8 hours to obtain a PVDF / Ag spinning solution. The mass concentration of PVDF was 10% and the mass concentration of silver nanoparticles was 28%.

[0052] (3) Place the PLA spinning solution from step (1) into the feeding system of the conjugate electrospinning device, prepare PLA micro-nano fiber single yarn using the conjugate electrospinning method, and then twist the single yarn into a ply.

[0053] (4) Place the PVDF / Ag spinning solution from step (2) into the feeding system of the conjugate electrospinning device, prepare PVDF / Ag micro / nano fiber single yarn using the conjugate electrospinning method, and then twist the single yarn into a ply.

[0054] (5) Weave the PVDF / Ag micro-nano fiber strands from step (4) into a plain weave single-layer fabric.

[0055] (6) Weave another layer of fabric on top of the PVDF / Ag fabric using the PLA micro-nano fiber strands from step (3). Ensure that some warp yarns of the upper fabric regularly weave through the lower fabric to obtain a double-layer micro-nano fiber fabric with PLA on the upper layer and PVDF / Ag on the lower layer. The lower PVDF / Ag fabric contains PLA yarn contacts from the upper fabric. This results in a double-layer micro-nano fiber fabric with daytime cooling function.

[0056] like Figure 4 As shown, under outdoor sunlight (outdoor temperature 39°C), when the double-layer micro / nano fiber fabric obtained in Example 3 was applied to the surface of human skin for temperature monitoring, an average skin surface temperature reduction of 9.04°C was achieved.

[0057] Example 4

[0058] The preparation steps of a double-layer micro / nano fiber fabric with daytime cooling function in this embodiment are as follows:

[0059] (1) Dissolve polylactic acid (PLA) polymer in chloroform and stir at 60°C for 12 h to obtain a PLA spinning solution with a mass fraction of 15%.

[0060] (2) Polyvinylidene fluoride (PVDF) polymer and silver nanoparticles were dissolved in a mixed solvent (DMF and THF mass ratio 1:1) and stirred at 80°C for 8 hours to obtain a PVDF / Ag spinning solution. The mass concentration of PVDF was 10% and the mass concentration of silver nanoparticles was 28%.

[0061] (3) Place the PLA spinning solution from step (1) into the feeding system of the conjugate electrospinning device, prepare PLA micro-nano fiber single yarn using the conjugate electrospinning method, and then twist the single yarn into a ply.

[0062] (4) Place the PVDF / Ag spinning solution from step (2) into the feeding system of the conjugate electrospinning device, prepare PVDF / Ag micro / nano fiber single yarn using the conjugate electrospinning method, and then twist the single yarn into a ply.

[0063] (5) Weave the PLA micro-nano fiber strands from step (3) into a plain weave single-layer fabric.

[0064] (6) The PVDF / Ag micro-nano fiber strands from step (4) are woven into a plain weave single-layer fabric.

[0065] (7) Stack the PLA single-layer fabric in step (5) and the PVDF / Ag single-layer fabric in step (6) in an alternating manner, that is, the warp yarns in the upper layer fabric are in the gap between the two warp yarns of the lower layer fabric. Then, the PLA micro-nano fiber strands in step (3) shuttle between the upper and lower layers of fabric to form a double-layer fabric. At the same time, the lower PVDF / Ag fabric is required to contain PLA micro-nano fiber yarn contacts.

[0066] like Figure 5 As shown, under outdoor sunlight (outdoor temperature 39°C), the double-layer micro / nano fiber fabric obtained in Example 4 was applied to the surface of human skin for temperature monitoring, achieving an average skin surface temperature reduction of over 9.6°C. This demonstrates and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the claims. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a micro / nano fiber fabric with daytime cooling function, characterized in that... Includes the following steps: (1) Mix a mid-infrared emitting and hydrophilic polymer or a mid-infrared emitting and hydrophilic polymer with a functional factor and dissolve it in a solvent. Stir at 25-100℃ for 1-24 h to obtain a polymer spinning solution A with a mass fraction of 5%-50%. (2) Dissolve a mid-infrared emitting and hydrophobic polymer or a mid-infrared emitting and hydrophobic polymer and a functional factor together in a solvent and stir at 25-100℃ for 1-24 h to obtain a polymer spinning solution B with a mass fraction of 5%-50%. (3) Place the polymer spinning solution A from step (1) into the feeding system of the conjugate electrospinning device, prepare micro-nano fiber single yarn using the conjugate electrospinning method, and then twist the single yarn into a ply yarn A. (4) Place the polymer spinning solution B from step (2) into the feeding system of the conjugate electrospinning device, prepare micro-nano fiber single yarn using the conjugate electrospinning method, and then twist the single yarn into a ply yarn B. (5) Weave the strands B from step (4) into a lower plain weave fabric; (6) Weave another layer of fabric, namely the upper plain weave fabric, above the lower plain weave fabric in step (5) using the ply yarn A in step (3). The lower plain weave fabric contains the yarn contact points of the upper plain weave fabric, thus obtaining a double-layer micro-nano fiber fabric with daytime cooling function; weave the ply yarn A in step (3) into an upper plain weave fabric and stack it with the lower plain weave fabric obtained in step (5) in an offset manner, that is, the warp yarns in the upper plain weave fabric are in the gap between the two warp yarns of the lower plain weave fabric. Then, use the ply yarn A in step (3) to shuttle between the upper and lower plain weave fabrics to form a double-layer fabric. The lower plain weave fabric contains the yarn contact points of the upper plain weave fabric, thus obtaining a double-layer micro-nano fiber fabric with daytime cooling function. The double-layer micro-nano fiber fabric with daytime cooling function has a double-layer structure, namely, the double-layer micro-nano fiber fabric includes an upper fabric and a lower fabric; the double-layer micro-nano fiber fabric is directly woven by designing the fabric structure, or it is formed by sewing two single-layer fabrics together; both the upper and lower fabrics are plain weave structures, wherein the warp yarns of the lower fabric correspond to the gaps between two adjacent warp yarns in the upper fabric, and the weft yarns of the lower fabric correspond to the gaps between two adjacent weft yarns in the upper fabric; the upper fabric is woven from mid-infrared emitting, hydrophilic, and thermally conductive yarns; the lower fabric is woven from mid-infrared emitting, hydrophobic, and thermally conductive yarns.

2. The method for preparing a double-layer micro / nano fiber fabric with daytime cooling function according to claim 1, characterized in that: When the double-layer micro-nano fiber fabric is directly woven by designing the fabric structure, some warp and / or weft yarns in the upper layer of the double-layer micro-nano fiber fabric must regularly shuttle through the lower layer of fabric, while all warp and weft yarns in the lower layer of fabric cannot appear in the upper layer of fabric; when the double-layer micro-nano fiber fabric is sewn together, its sewing line is the same as the yarn in the upper layer of fabric and regularly passes through the upper and lower layers of fabric.

3. The method for preparing a double-layer micro / nano fiber fabric with daytime cooling function according to claim 1, characterized in that: The yarns in the fabric are all micro-nano fiber yarns with a diameter ranging from 10 to 1000 μm. The breaking elongation of the micro-nano fiber yarns is greater than 5%, and the breaking strength is greater than 10 MPa.

4. The method for preparing a double-layer micro / nano fiber fabric with daytime cooling function according to claim 1, characterized in that: The micro / nano fibers have a conventional structure or a protruding or porous structure, with a fiber diameter distribution of 0.2-2.5 μm, a protrusion diameter of 0.2-2.5 μm on the fiber surface, and a pore diameter of 0.2-2.5 μm in the fiber; the polymer solution or melt is a single polymer or a mixture of one or more functional factors and polymers.

5. The method for preparing micro / nano fiber fabric with daytime cooling function according to claim 1, characterized in that: The mid-infrared emitting and hydrophilic polymers include cellulose acetate, fluorinated polyethylene, and polyvinyl alcohol; the mid-infrared emitting and hydrophobic polymers include polyvinylidene fluoride, polyurethane, and polylactic acid.

6. The method for preparing micro / nano fiber fabric with daytime cooling function according to claim 1, characterized in that: The solvent in step (1) is deionized water, dichloromethane, trichloromethane, tetrahydrofuran (THF), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), acetone, or a mixture of THF and DMF, or a mixture of DMAC and acetone.

7. The method for preparing micro / nano fiber fabric with daytime cooling function according to claim 1, characterized in that: The functional factors are thermally conductive factors, cooling factors, highly reflective photons, or highly emitted photons; the thermally conductive factors include graphene sheets, carbon nanotubes, and silver nanoparticles; the cooling factors include menthol microcapsules, isocyanates, and silk protein cooling finishing agents; the highly reflective photons include zinc oxide nanoparticles (ZnO), titanium dioxide (TiO2), and calcium carbonate; and the highly emitted photons include silicon dioxide, silicon nitride (Si3N4), and silicon oxynitride.

8. The application of the double-layer micro / nano fiber fabric with daytime cooling function prepared by any one of the preparation methods according to claims 1-7, characterized in that: The double-layer micro-nano fiber fabric is used in the field of daytime cooling textiles.

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