Preparation method and application of passive cooling light and heat regulation fiber and fabric

Abstract

The present invention provides a preparation method and application of passive cooling photothermal regulation fibers and fabrics. The present invention achieves high reflection of the solar radiation band by designing the micro-nano optical structure of the fiber and utilizing the difference between different refractive indices inside the fiber. The imaginary part of the refractive index of the fiber material and the introduced nano-medium particles is combined to achieve high emission in the entire mid-infrared band, thereby achieving wide-spectrum selective regulation of the passive cooling photothermal regulation fibers and fabrics in the solar radiation band and the mid-infrared band, and ultimately achieving efficient passive cooling effects on the human body in outdoor high-temperature environments. In addition, high-refractive-index nano-medium particles or low-refractive-index nano-medium particles are introduced into polymer fibers using a solution spinning process to achieve excellent passive cooling photothermal regulation effects, and are woven into highly flexible fabrics suitable for cooling the surface of human skin, thereby achieving precise regulation of solar radiation and mid-infrared spectra during the mass preparation of passive cooling photothermal regulation fibers and fabrics.

Description

Technical Field

[0001] The present invention relates to the technical field of passive cooling, and in particular to a preparation method and application of passive cooling photothermal regulation fiber and fabric. Background Art

[0002] Passive cooling technology uses structural design and material selection to enable objects to obtain high emissivity in the 8-13μm mid-infrared band and high reflectivity in the 0.3-2.5μm solar radiation band. This selective spectral regulation is used to effectively radiate heat and block energy input. Compared with traditional space thermal control systems (such as air conditioning, etc.), passive cooling technology does not consume any energy and is eco-friendly. It is an effective strategy to alleviate global warming and change the energy structure, and has a positive role in reducing global energy consumption and strengthening environmental protection.

[0003] Prolonged exposure to high temperature outdoor environments can damage important organs such as the heart and liver, and even cause heat stroke, which is life-threatening. People are increasingly in need of personal thermal management. Compared with passive cooling devices in the form of films and coatings, passive cooling devices in the form of fiber fabrics with good air permeability, moisture permeability, softness, and comfort are also gradually being developed.

[0004] The prior art discloses a passive cooling fiber membrane and its preparation method and application, wherein radiation particles are randomly dispersed between polymer fibers through electrospinning to prepare a fiber membrane with a simple structure that can be used for heat dissipation and cooling of the human body. The above patent has low production efficiency, complex process, high equipment cost, and is not weavable, and cannot prepare fabrics for passive cooling of the human body.

[0005] The prior art proposes a passive cooling fiber and its preparation method and application, wherein the passive cooling fiber is prepared by mixing melt-spinning functional fillers with matrix materials, and the passive cooling fabric obtained by weaving has a reflectivity greater than 60% in the solar radiation band and an emissivity of not less than 80% in the human body thermal radiation band. The functional fillers doped in the fiber in the above patent have a low mass fraction and cannot effectively block the input of solar radiation, so its passive cooling effect is limited.

[0006] The prior art proposes a method for preparing a passive cooling functional fabric, which utilizes the difference in polymer solubility to form a yarn with a porous structure, and weaves it into a fabric, wherein the porous micro-nano structure can improve the reflectivity of the solar radiation band and effectively block solar radiation. The above patent does not make a precise structural design of the nanoparticle content and porosity, and it is difficult to achieve the full reflection effect of the solar radiation band, so its passive cooling effect is limited.

[0007] The prior art proposes a three-dimensional porous micro-nano composite material and its preparation method and application, which uses the jet electrospinning technology to construct a three-dimensional porous micro-nano composite material in one step, so that the material has a high reflectivity within the solar spectrum. The above patent modifies the outer layer of the fiber so that the final three-dimensional material has a porous structure, which has certain limitations on improving the reflectivity of the solar radiation band, and the fiber is a homogeneous material inside, so its passive cooling effect is limited.

[0008] In summary, the existing passive cooling technologies that can be used to cool the human body are complex and have limited cooling effects. There is a lack of new methods for mass production of highly flexible passive cooling photothermal control fibers and fabrics based on micro-nano optical structure design and solution spinning technology. Summary of the invention

[0009] In order to solve the above problems, the present application provides a preparation method and application of passive cooling photothermal control fiber and fabric; through the design of the micro-nano optical structure of the passive cooling photothermal control fiber, the difference between different refractive indices inside the fiber (Δn) is used to achieve high reflection of the entire solar radiation band, and the imaginary part of the refractive index of the fiber material and the introduced nano-medium particles is combined to achieve high emission of the entire mid-infrared band, thereby realizing the passive cooling photothermal control fiber and fabric in the solar radiation band and the mid-infrared band. The wide spectrum selective control, ultimately achieving the efficient passive cooling effect of the human body in the outdoor high temperature environment. In addition, the solution spinning process is used to introduce high-refractive index nano-medium particles (refractive index is n2, n2>n1) or low-refractive index nano-medium particles (refractive index is n3, n3<n1) into the polymer fiber (refractive index is n1), to achieve excellent passive cooling photothermal control effect, and weave into a highly flexible fabric suitable for cooling the surface of human skin, so as to achieve the passive cooling photothermal control fiber and fabric in the macro-preparation process. The precise control of solar radiation and mid-infrared spectrum.

[0010] The specific technical solutions of this application are as follows:

[0011] In a first aspect, the present invention provides a method for preparing a passive cooling photothermal regulation fiber, comprising the following steps:

[0012] The spinning solution is spun to obtain passive cooling photothermal regulation fiber;

[0013] Wherein, the spinning solution comprises a polymer material and a solvent, or the spinning solution comprises a high-refractive-index nano-medium and / or a low-refractive-index nano-medium, a polymer material and a solvent;

[0014] Wherein, the refractive index of the high refractive index nano-medium is greater than the refractive index of the polymer material;

[0015] The refractive index of the low-refractive-index nanomaterial is lower than that of the polymer material.

[0016] Preferably, in the method for preparing the passive temperature-lowering photothermal control fiber, the refractive index of the high-refractive-index nano-medium is n2, the refractive index of the polymer material is n1, and the refractive index of the low-refractive-index nano-medium is n3;

[0017] Among them, n2>1.9,1.2 <n1<1.6,n3<1.2。

[0018] Preferably, in the preparation method of the passive cooling photothermal control fiber, the high refractive index nano-medium is an inorganic nano-particle, and the inorganic nano-particle includes at least one of titanium dioxide, silicon dioxide, zinc oxide, silicon carbide, silicon nitride, zinc sulfide, aluminum oxide, iron oxide, boron nitride, magnesium oxide, barium sulfate, barium carbonate, and aluminum silicate;

[0019] And / or, the particle size of the high refractive index nano-medium is 0.04 μm to 10.1 μm;

[0020] And / or, the particle size of the low refractive index nano-medium is 0.04 μm to 10.1 μm.

[0021] Preferably, in the method for preparing the passive cooling photothermal regulation fiber, the low refractive index nano-medium is composed of air holes or aerogel powder.

[0022] Preferably, in the method for preparing the passive cooling photothermal regulation fiber, if the spinning solution comprises a polymer material and a solvent, the mass fraction of the polymer material in the spinning solution is 1-40%;

[0023] If the spinning solution comprises a high-refractive-index nano-medium, a polymer material and a solvent, the mass fraction of the polymer material in the spinning solution is 1-70%, and the mass of the high-refractive-index nano-medium in the spinning solution is 1-80% of the mass of the polymer material;

[0024] If the spinning solution includes low-refractive index nano-medium, polymer material and solvent, the mass fraction of the polymer material in the spinning solution is 40-70%, and the mass of the low-refractive index nano-medium in the spinning solution is 1-45% of the mass of the polymer material.

[0025] Preferably, in the preparation method of the passive cooling optical thermal regulation fiber, the polymer material includes at least one of polyamide, polyvinyl alcohol, polyacrylonitrile, polyphenylene terephthalate, poly(p-phenylene terephthalamide), meta-aromatic polyamide, polyvinylidene fluoride and its copolymer, and polymethyl methacrylate;

[0026] And / or, the solvent includes at least one of water, N,N-dimethylformamide, dimethylacetamide, nitric acid, acetic acid, toluene, cyclohexane, tetrahydrofuran-dioxane mixed solution, benzene, carbon tetrachloride, amyl acetate, acetone, 4-methylmorpholine-N-oxide, N-ethylpyridine chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium diethyl phosphate, a mixture of NaOH / CH4N2O / water, a mixture of NaOH / thiourea / water, a mixture of NaOH / thiourea / urea / water, a mixture of urea / caprolactam / NaOH / water, a mixture of NaOH / ZnO / water, a mixture of NaOH / ethanol / water, tetralin, naphthalene, mineral oil, paraffin oil, decahydronaphthalene and paraffin).

[0027] Preferably, the method for preparing the passive cooling photothermal regulation fiber comprises the following steps:

[0028] The spinning solution is delivered to a spinning device, and then ejected from the spinneret holes of the spinneret in the spinning device to obtain an ejected solution;

[0029] The sprayed liquid passes through an air layer or a coagulation bath to form primary fibers;

[0030] The nascent fiber is washed and stretched to form a passive cooling photothermal control fiber;

[0031] The spinning temperature is 10-150°C and the spinning speed is 0.6-3000 m / min.

[0032] Preferably, in the method for preparing the passive cooling photothermal control fiber, the viscosity of the spinning solution is 50-400 Pa·s;

[0033] And / or, the mass fraction of the polymer material in the spinning solution is 1 to 70%.

[0034] In a second aspect, the present invention further provides a passive cooling photothermal regulation fabric, which is obtained by weaving the passive cooling photothermal regulation fiber prepared by the preparation method.

[0035] In a third aspect, the present invention also provides an application of the passive cooling photothermal regulation fiber prepared by the preparation method or the passive cooling photothermal regulation fabric in the preparation of passive cooling materials.

[0036] The preparation method of the passive cooling photothermal control fiber of the present invention has the following beneficial effects compared with the prior art:

[0037] 1. The preparation method of the passive cooling photothermal regulation fiber of the present invention is prepared by a solution spinning process; wherein, the passive cooling photothermal regulation fiber may contain a high refractive index nano-medium (refractive index n2) and a low refractive index nano-medium (refractive index n3) respectively, or contain two kinds of nano-medium particles at the same time; the introduction of media with different refractive indices into the polymer material can cause multi-order Mie scattering and diffraction of light at interfaces with different refractive indices, thereby enhancing the reflection performance of solar radiation; in the above three situations, when two different nano-medium particles exist at the same time, the number of multi-order Mie scattering and the number of diffraction orders are greatly increased, which can greatly enhance the reflection performance of the passive cooling photothermal regulation fiber to solar radiation, so that the finally formed fabric has a better passive cooling effect. When the high-refractive-index nano-medium is an inorganic nano-particle, and the low-refractive-index nano-medium is an air hole, the inorganic nano-particle and the air hole are randomly distributed inside the passive cooling photothermal regulation fiber as high-scattering nano-medium with multi-order diffraction and strong multi-order Mie scattering ability, and sunlight induces multi-order resonance at the interfaces of three materials with different refractive indices: polymer-nanoparticle, air-polymer, and air-nanoparticle. The multi-order diffraction and strong forward Mie scattering of the micro-nano optical structure in the solar radiation band are utilized to achieve the total reflection effect of the passive cooling photothermal regulation fiber and fabric in the entire solar radiation band, and finally the passive cooling photothermal regulation fiber and fabric have excellent passive cooling effect;

[0038] 2. The present invention designs and regulates the internal structure of the fiber, and designs and selects the refractive index, particle size and volume fraction of the scattering medium inside the passive cooling photothermal regulation fiber, so that the passive cooling photothermal regulation fabric has excellent mid-infrared (8-13μm) weighted emissivity, reaching above 0.90, and can even reach 0.96; the weighted reflectivity of solar radiation (0.3-2.5μm) reaches above 0.92, and can even reach 0.97. In addition, the present invention uses solution spinning as a spinning process, which can effectively reduce the degradation of the polymer during the spinning process, improve the comprehensive performance of the fiber, and the prepared passive cooling photothermal regulation fiber and fabric have high flexibility, which greatly enhances the comfort of the human body. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 A schematic diagram of a spinning device used for spinning by dry spinning in one embodiment of the present invention;

[0041] Figure 2 A schematic diagram of a spinning device for spinning wet filaments in one embodiment of the present invention;

[0042] Figure 3 A schematic diagram of a spinning device used for spinning by dry-wet spinning in one embodiment of the present invention;

[0043] Figure 4 This is a simulated data diagram of the reflectivity of the passive cooling photothermal regulation fibers with different structures obtained by the present invention;

[0044] Figure 5 This is a cross-sectional SEM image of the passive cooling photothermal regulation fiber prepared in Example 1 of the present invention;

[0045] Figure 6 This is a cross-sectional SEM image of the passive cooling photothermal regulation fiber prepared in Example 15 of the present invention;

[0046] Figure 7 This is a cross-sectional SEM image of the passive cooling photothermal regulation fiber prepared in Example 16 of the present invention;

[0047] Figure 8 This is a schematic diagram of the passive cooling light-heat regulating fabric prepared in Example 1 of the present invention;

[0048] Fig. 9 This is a data diagram of the pore size distribution of the passive cooling photothermal regulation fiber prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] In order to better understand the present invention but not to limit the scope of the present invention, all the numbers used in this application to express the amount, percentage, and other numerical values ​​should be understood as modified by the word "about" in all cases. Therefore, unless otherwise specified, the numerical parameters listed in the specification and the appended claims are approximate values, which may be changed according to the different ideal properties attempted to be obtained. Each numerical parameter should at least be regarded as obtained based on the reported significant figures and by conventional rounding methods.

[0051] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0052] The present invention provides a method for preparing a passive cooling photothermal regulation fiber, comprising the following steps:

[0053] The spinning solution is spun to obtain passive cooling photothermal regulation fiber;

[0054] Wherein, the spinning solution comprises a polymer material and a solvent, or the spinning solution comprises a high-refractive-index nano-medium and / or a low-refractive-index nano-medium, a polymer material and a solvent;

[0055] Wherein, the refractive index of the high refractive index nano-medium is greater than the refractive index of the polymer material;

[0056] The refractive index of the low-refractive-index nanomaterial is lower than that of the polymer material.

[0057] It should be noted that the method for preparing the passive cooling photothermal regulation fiber of the present invention, the spinning solution used includes a polymer material and a solvent, or the spinning solution includes a high-refractive index nano-medium and / or a low-refractive index nano-medium, a polymer material and a solvent; specifically, the method for preparing the spinning solution includes: adding the polymer material to the solvent, mixing and stirring to obtain the spinning solution; or, adding the high-refractive index nano-medium and / or the low-refractive index nano-medium and the polymer material to the solvent, mixing and stirring to obtain the spinning solution; the passive cooling photothermal regulation fiber is prepared by the spinning process; wherein the refractive index of the high-refractive index nano-medium The refractive index of the polymer material is n2, the refractive index of the polymer material is n1, and the refractive index of the low-refractive-index nano-medium is n3, where n3<n1<n2; the present invention uses the difference (Δn) between the different refractive indices inside the fiber to achieve high reflection of the entire solar radiation band, and combines the imaginary part of the refractive index of the fiber material and the introduced nano-medium particles to achieve high emission of the entire mid-infrared band, thereby achieving wide-spectrum selective regulation of the passive cooling photothermal regulation fiber and fabric in the solar radiation band and the mid-infrared band, and finally achieving efficient passive cooling effect on the human body in outdoor high-temperature environment. In addition, a solution spinning process is used to introduce high-refractive-index nano-medium particles (n2, n2>n1) or low-refractive-index nano-medium particles (n3, n3<n1) into the polymer material (n1), so as to achieve excellent passive cooling photothermal regulation effect, and weave into a highly flexible fabric suitable for cooling the surface of human skin, so as to achieve precise regulation of solar radiation and mid-infrared spectrum of the passive cooling photothermal regulation fiber and fabric during the macro-scale preparation process.

[0058] In some embodiments, the refractive index of the high refractive index nanomaterial is n2, the refractive index of the polymer material is n1, and the refractive index of the low refractive index nanomaterial is n3;

[0059] Among them, n2>1.9,1.2 <n1<1.6,n3<1.2。

[0060] The passive cooling photothermal regulation fiber of the present invention has a passive cooling photothermal regulation function, and can discharge its own heat in the form of 8-13μm electromagnetic waves through an "atmospheric window" to the outside space with a temperature close to absolute zero, so as to achieve the purpose of self-cooling.

[0061] In some embodiments, the high refractive index nano-medium is an inorganic nano-particle. The inorganic nano-particle has the characteristic of high refractive index and can produce high scattering efficiency in polymer materials, so that the passive cooling and photothermal regulation fiber can have a high reflectivity in the solar radiation band. Specifically, the inorganic nano-particle is selected from one or more of titanium dioxide (TiO2), silicon dioxide (SiO2), zinc oxide (ZnO), silicon carbide (SiC), silicon nitride (Si3N4), zinc sulfide (ZnS), aluminum oxide (Al2O3), iron oxide (Fe2O3), boron nitride (BN), magnesium oxide (MgO), barium sulfate (BaSO4), barium carbonate (BaCO3) and aluminum silicate (Al2SiO5), preferably titanium dioxide, zinc oxide or silicon nitride.

[0062] In some embodiments, the low refractive index nano-medium is an air hole. Specifically, the air hole is formed in the process of spinning the spinning solution to obtain the passive cooling photothermal regulation fiber, wherein the content of the air hole is determined by the solvent concentration in the spinning solution. The greater the solvent concentration, the less the air hole content, and the smaller the solvent concentration, the more the air hole content; the amount is controlled by changing the weight percentage of the polymer material in the spinning solution. The air hole has the characteristic of a low refractive index and can also generate scattering in the polymer material, which can further improve the reflectivity of the passive cooling photothermal regulation fiber in the solar radiation band.

[0063] In some embodiments, the low refractive index nano-medium is composed of aerogel powder.

[0064] In some embodiments, the polymer material has the characteristic of high infrared emissivity, and the polymer material is selected from one or more of polyamide, polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyphenylene terephthalate (PET), polyphenylene terephthalamide (PPTA), meta-aromatic polyamide, polyvinylidene fluoride (PVDF) and its copolymers, and polymethyl methacrylate (PMMA), preferably polyvinylidene fluoride-hexafluoropropylene copolymer or polyacrylonitrile.

[0065] In some embodiments, if the spinning solution comprises a polymer material and a solvent, the mass fraction of the polymer material in the spinning solution is 1-40%, preferably 5-15%.

[0066] In some embodiments, if the spinning solution includes high refractive index nano-medium, polymer material and solvent, the mass fraction of the polymer material in the spinning solution is 1-70%, preferably 5-15%, and the mass of the high refractive index nano-medium in the spinning solution is 1-80% of the mass of the polymer material, preferably 30-50%.

[0067] In some embodiments, if the spinning solution includes low-refractive index nano-medium, polymer material and solvent, the mass fraction of the polymer material in the spinning solution is 40-70%, preferably 40-50%, and the mass of the low-refractive index nano-medium in the spinning solution is 1-45% of the mass of the polymer material, preferably 20-40%.

[0068] Specifically, if the spinning solution includes a polymer material and a solvent, air holes are formed during the spinning process, and the air holes are low-refractive-index nano-mediums; the refractive-index difference between the polymer material and the air holes is utilized to achieve high reflection of the entire solar radiation band;

[0069] Specifically, if the spinning solution includes high-refractive-index nano-medium, polymer material and solvent, air holes are formed during the spinning process, and the air holes are low-refractive-index nano-medium; the refractive-index difference between the high-refractive-index nano-medium, polymer material and air holes is utilized to achieve high reflection of the entire solar radiation band.

[0070] In some embodiments, the particle size of the high refractive index nano-medium is 0.04 μm to 10.1 μm, preferably 0.3±0.1 μm to 0.5±0.1 μm. The particle size refers to: the average diameter of the high refractive index nano-medium.

[0071] In some embodiments, the particle size of the low refractive index nano-medium is 0.05±0.01 μm-10±0.1 μm, preferably 0.2±0.1 μm-0.5±0.1 μm. The particle size refers to: the average diameter of the low refractive index nano-medium.

[0072] In some embodiments, the solvent used in the present invention is not limited, for example, water, N,N-dimethylformamide (DMF), dimethylacetamide (DMAc), nitric acid (HNO3), acetic acid (CH3COOH), toluene (C7H8), cyclohexane (C6H 12 ), tetrahydrofuran-dioxane mixed solution (C4H8O-C4H8O2), benzene (C6H6), carbon tetrachloride (CCl4), amyl acetate (C7HO2), acetone (CH3COCH3), 4-methylmorpholine-N-oxide (C5H 11 NO2), N-ethylpyridinium chloride (C7H 10 O4NCl), 1-butyl-3-methylimidazolium chloride (C8H 15 ClN2), 1-ethyl-3-methylimidazolium chloride (C6H 11 ClN2), 1-butyl-3-methylimidazolium acetate (C 10 H 18 N2O2), 1-ethyl-3-methylimidazolium acetate (C8H 14N2O2), 1-ethyl-3-methylimidazole diethyl phosphate (C 10 H 21 N2O4P), sodium hydroxide (NaOH) / urea (CH4N2O) / water (H2O), NaOH / thiourea (CH4N2S) / water, NaOH / thiourea / urea / water, urea / caprolactam / NaOH / water, NaOH / ZnO / water, NaOH / ethanol / water, tetralin (C 10 H 12 ), naphthalene (C 10 H8), mineral oil (C 15 H 11 ClO7), paraffin oil (C 15 H 11 ClO7), decahydronaphthalene (C 10 H 18 ) and paraffin (C 31 H 64 ), preferably NaOH / urea / water, DMF, acetic acid or 4-methylmorpholine-N-oxide.

[0073] Specifically, sodium hydroxide (NaOH) / urea (CH4N2O) / water (H2O) is a solvent formed by NaOH, urea and water, and the three can be in any mass ratio. For example, in terms of the mass percentage in the NaOH / urea / water solvent, NaOH can be 8%, urea is 10%, and the remainder is water.

[0074] NaOH / thiourea (CH4N2S) / water is a solvent formed by NaOH, thiourea and water, and the three can be in any mass ratio. For example, in terms of the mass percentage in the NaOH / thiourea / water solvent, NaOH can be 8%, thiourea can be 6.5%, and the balance is water.

[0075] NaOH / thiourea / urea / water is a solvent formed by NaOH, thiourea, urea and water, and the four can be in any mass ratio. For example, based on the mass percentage of the NaOH / thiourea / urea / water solvent, NaOH can be 8%, thiourea can be 6.5%, urea can be 8%, and the balance is water.

[0076] Urea / caprolactam / sodium hydroxide / water is a solvent formed by urea, caprolactam, sodium hydroxide and water, and the four can be in any mass ratio. For example, in terms of the mass percentage in the urea / caprolactam / sodium hydroxide / water solvent, urea can be 10%, caprolactam can be 4%, sodium hydroxide can be 8%, and the balance is water.

[0077] NaOH / ZnO / water is a solvent formed by NaOH, ZnO and water, and the three can be in any mass ratio. For example, in terms of mass percentage in the NaOH / ZnO / water solvent, NaOH can be 8%, ZnO can be 10%, and the balance is water.

[0078] The NaOH / ethanol / water solvent is a solvent formed by NaOH, ethanol and water, and the three can be in any mass ratio. For example, based on the mass percentage of the NaOH / ethanol / water solvent, NaOH can be 8%, ethanol can be 10%, and the balance is water.

[0079] The tetrahydrofuran-dioxane blend solution is a solution formed by tetrahydrofuran and dioxane. The present invention does not limit the volume ratio of tetrahydrofuran to dioxane, for example, the volume ratio can be 1:1.

[0080] In some embodiments, the polymer material is 1-70%, preferably 5-15%, based on the weight percentage of the polymer material in the spinning solution. For example, based on the weight percentage of the polymer material in the spinning solution, the polymer material can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or any range therebetween.

[0081] In some embodiments, the spinning solution is spun to obtain a passive cooling photothermal regulation fiber, comprising the following steps:

[0082] S1, delivering the spinning solution to a spinning device, and then spraying the solution from the spinneret holes of the spinneret in the spinning device to obtain a spray solution;

[0083] S2, the sprayed liquid passes through the air layer or coagulation bath to form primary fibers;

[0084] S3. Washing and stretching the nascent fiber to form passive cooling photothermal regulation fiber.

[0085] The present invention does not impose any limitation on the spinning device, as long as it can perform spinning. For example, the spinning device can be a spinning tank or a spinning box.

[0086] The present invention does not limit the specific spinning process, as long as spinning can be performed, for example, the spinning process can be dry spinning, wet spinning or dry-wet spinning.

[0087] In some embodiments, the present invention does not limit the spinning temperature. For example, the spinning temperature can be 10-150°C, such as 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc.

[0088] In some embodiments, the present invention is not limited to the spinning speed. For example, the spinning speed can be 0.6-3000 m / min, such as 0.6 m / min, 1 m / min, 10 m / min, 50 m / min, 100 m / min, 500 m / min, 1000 m / min, 1500 m / min, 2000 m / min, 2500 m / min, 3000 m / min, etc.

[0089] In some embodiments, the viscosity of the spinning solution is 50-400 Pa·s, preferably 300 Pa·s. For example, the viscosity of the spinning solution of the nano-medium particles and polymer material can be 50 Pa·s, 100 Pa·s, 150 Pa·s, 200 Pa·s, 250 Pa·s, 300 Pa·s, 350 Pa·s, 400 Pa·s, etc.

[0090] The above viscosity is measured by a viscosity meter known in the art, for example, the NDJ-5S viscosity meter, NDJ-8S viscosity meter or NDJ-9S viscosity meter produced by Shanghai Lichen Technology.

[0091] In some embodiments, the present invention does not limit the length of the air layer in the dry spinning and dry-wet spinning processes. The technical personnel in this field can set the length of the air layer as needed. For example, the length of the air layer can be 2 mm, 10 mm, 50 mm, 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, etc.

[0092] In some embodiments, for the coagulation bath temperature in wet spinning and dry-wet spinning processes, preferably, the temperature of the coagulation bath is 0-100°C, for example, it can be 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, etc.

[0093] The present invention does not limit the number of coagulation baths, and those skilled in the art can set the number of coagulation baths as needed. For example, the coagulation baths include two coagulation baths. Preferably, the temperature of coagulation bath one is ≥ the temperature of coagulation bath two. Coagulation bath one refers to the coagulation bath one that the ejected liquid first enters after passing through the air layer, and the coagulation bath two that the ejected liquid enters next.

[0094] In some embodiments, the present invention does not limit the coagulation bath. For example, the solute of the coagulation bath may be water, dimethyl sulfoxide (DMSO), sulfuric acid (H2SO4), sodium sulfate (Na2SO4), ammonium sulfate ((NH4)2SO4);

[0095] The mass percentage of the solute in the coagulation bath can be 0-80%, for example, 0, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc.

[0096] If, if the spinning solution includes high-refractive index nano-medium, polymer material and solvent, the volume of the high-refractive index nano-medium in the prepared passive cooling photothermal regulation fiber is 5%-30% of the volume of the polymer material, preferably 10%-15%; the volume of the low-refractive index nano-medium (air pores) is 5%-80% of the volume of the polymer material, preferably 40%-70%.

[0097] For details, please refer to Figure 1 As shown, it is a schematic diagram of a spinning device used for spinning by dry spinning in one of the embodiments of the present invention, the spinning stock solution is sent to the spinning medicine tank 11 of the spinning device, and then sprayed out from the spinneret holes of the spinneret in the spinning device to obtain the spray liquid; the spray liquid passes through the air layer 12 to form nascent fibers; the nascent fibers are washed and stretched to form passive cooling photothermal regulation fibers.

[0098] Please refer to Figure 2 As shown, it is a schematic diagram of a spinning device used for wet spinning in one of the embodiments of the present invention, the spinning stock solution is sent to the spinning medicine tank 11 of the spinning device, and then sprayed out from the spinneret holes of the spinneret in the spinning device to obtain the spray liquid; the spray liquid passes through the coagulation bath 13 to form nascent fibers; the nascent fibers are washed and stretched to form passive cooling photothermal regulation fibers.

[0099] Please refer to Figure 3 As shown, it is a schematic diagram of a spinning device used for spinning by dry-wet spinning in one of the embodiments of the present invention, the spinning stock solution is sent to the spinning medicine tank 11 of the spinning device, and then sprayed out from the spinneret hole of the spinneret in the spinning device to obtain the spray liquid; the spray liquid first passes through the air layer 12, and then passes through the coagulation bath 13 to form the nascent fiber; the nascent fiber is washed and stretched to form the passive cooling photothermal regulation fiber.

[0100] Based on the same inventive concept, the present invention also provides a passive cooling photothermal regulation fiber, which is prepared by the above-mentioned preparation method.

[0101] Based on the same inventive concept, the present invention also provides a passive cooling photothermal regulation fabric, which is woven by weaving the passive cooling photothermal regulation fibers prepared by the above-mentioned preparation method.

[0102] Specifically, weaving can be knitting or weaving.

[0103] In some embodiments, the passive cooling and light-heat regulating fabric has an average reflectivity greater than or equal to 0.92 in the solar wavelength band.

[0104] For example, the average reflectivity of the passive cooling and light-heat regulating fabric in the solar light band can be 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, etc.

[0105] In some embodiments, the weighted emissivity of the passive cooling photothermal regulation fabric in the 8-13 μm band is greater than or equal to 0.90.

[0106] For example, the weighted emissivity of the passive cooling photothermal control fabric in the 8-13 μm band can be 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, etc.

[0107] In some embodiments, a method for preparing a passive cooling photothermal regulating fabric comprises: using the obtained passive cooling photothermal regulating fibers as weft yarns and warp yarns respectively, adjusting the warp yarns on the cloth winding roller to make the tension uniform and the tightness appropriate to avoid excessive friction and wear of the fibers; according to the changing law of warp and weft interweaving, using an opening mechanism to sequentially drive the upper and lower layers of warp yarns to form a shed channel; winding the fibers on a shuttle as weft yarns, and weaving the shuttle back and forth through the shed channel, coordinating with other mechanisms on the loom to adjust the arrangement density of the weft yarns, and winding and removing the fabric on the cloth winding roller, thereby obtaining a passive cooling photothermal regulating fabric.

[0108] Based on the same inventive concept, the present invention also provides an application of the passive cooling photothermal regulation fiber prepared by the above-mentioned preparation method or the passive cooling photothermal regulation fabric in the preparation of passive cooling materials.

[0109] The following further illustrates the preparation method of the passive cooling photothermal control fiber of the present application and its preparation method by specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be construed as a limitation of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0110] In the following examples, FDTD Solutions was used to model and simulate the structure, establish a two-dimensional model structure of passive cooling photothermal control fiber, construct randomly distributed nano-medium particles with different refractive indices inside, and obtain a micro-nano optical structure with excellent solar radiation band reflectivity and mid-infrared radiation band emissivity based on multi-level Mie scattering theory. The specific operation is: randomly add TiO2 nanoparticles and form nano-cavities in the PVDF substrate, reasonably equate the cross-section of the fiber fabric to a thin film structure and construct its two-dimensional model. The width of the model is 20μm, and periodic boundary conditions are used in the x direction of the model to simulate an infinitely large film. Based on the numerical simulation of multi-level Mie scattering theory, the solar spectrum reflectivity of the fiber fabric containing different volume fractions of TiO2 particles and nano-cavities in the 0.3-20μm band at a thickness of 500μm was calculated. Figure 4 From the weighted reflectivity graph of the simulated solar spectrum, it can be seen that the weighted reflectivity of the solar spectrum in the visible light band of Example 1 is the highest, so the optimal internal structure of the passive cooling photothermal regulation fiber is determined to be a volume ratio of high refractive index nano-medium particles to polymer materials of 14% and a volume ratio of low refractive index nano-medium particles to polymer materials of 50%.

[0111] Example 1

[0112] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0113] S1, preparing spinning solution, specifically comprising the following steps:

[0114] 3595g of 4-methylmorpholine-N-oxide (NMMO) solvent was heated at 110°C until completely melted, and 415g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 140g of TiO2 particles (particle size of 400±100nm) dried in a vacuum oven at 100°C for 24h were added under vigorous stirring to obtain a solution, and the solution was placed at 20°C for degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution was 10wt.%;

[0115] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer and into a water coagulation bath, the coagulation bath temperature is 80°C, and the primary fiber is obtained after being stretched in the coagulation bath;

[0116] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, the cross-section of the passive cooling photothermal regulation fiber is as follows Figure 5As shown, the obtained passive cooling photothermal regulation fiber is then collected on a winding roller.

[0117] The present application also provides a passive cooling photothermal control fabric, and the preparation method thereof is as follows: the passive cooling photothermal control fiber prepared in Example 1 is used as weft yarn and warp yarn respectively, and the warp and weft are woven to obtain the passive cooling photothermal control fabric; the schematic diagram of the passive cooling photothermal control fiber is as shown in Figure 8 shown.

[0118] Example 2

[0119] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0120] S1. Prepare a spinning solution, specifically comprising the following steps: add 1105 g of PAN polymer (polyacrylonitrile) to 9395 g of DMF (N,N-dimethylformamide) solvent, vigorously stir until completely dissolved, then add 550 g of TiO2 particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 hours, and stir at 90° C. for 7 hours. After standing and degassing for 9 hours, a spinning solution in which the weight proportion of PAN in the spinning solution is 10 wt.% is obtained;

[0121] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 90°C, and the spinning speed is 1000m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer to a first coagulation bath at 80°C where the solute is DMSO and the solvent is ethanol (the concentration of DMSO is (70wt.%)) and a second coagulation bath at 80°C where the solute is DMSO and the solvent is ethanol (the concentration of DMSO is (70wt.%)), and the nascent fiber is obtained after being stretched in the coagulation bath;

[0122] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0123] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 2 are used as weft yarns and warp yarns respectively, and the fabric is obtained by weaving the fabric in the warp and weft manner.

[0124] Example 3

[0125] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0126] S1. Prepare a spinning solution, specifically comprising the following steps: add 850 g of PVA polymer (polyvinyl alcohol) to a solvent mixed with 6470 g of acetone and 780 g of water, then add 400 g of TiO2 particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 h, and stir at 80° C. for 7 h to obtain a solution, and place the solution at 20° C. for degassing, and finally obtain a spinning solution in which the weight proportion of PVA in the spinning solution is 10 wt.%;

[0127] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 80°C, and the spinning speed is 2000m / min; then, the spinning solution is ejected from the spinneret with a diameter of 0.02mm in the spinning device at room temperature and coagulated in an air layer at 80°C to obtain primary fibers;

[0128] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0129] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 3 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft.

[0130] Example 4

[0131] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0132] S1. Preparation of SiO2 aerogel powder: Put SiO2 aerogel powder with a particle size of 5 μm into a ball mill, set the ball milling speed to 400 rpm, and the ball milling time to 13 h. As the ball milling time increases, the particle size of the SiO2 aerogel powder gradually decreases, and finally SiO2 aerogel powder with a particle size of 400±100 nm is prepared;

[0133] S2, prepare spinning solution, specifically including the following steps: heat 263g of 4-methylmorpholine-N-oxide (NMMO) solvent at 110°C until completely melted, add 415g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich), 140g of TiO2 particles (particle size of 400±100nm) dried in a vacuum oven at 100°C for 24h, and 11.7g of SiO2 aerogel powder (particle size of 400±100nm) prepared in S1 under vigorous stirring to obtain a solution, place the solution at 20°C for standing and degassing, and obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 50wt.% (50.02wt.% is approximately equal to 50wt.%);

[0134] S3, the spinning solution in S2 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer at 80°C to a water coagulation bath, the coagulation bath temperature is 80°C, and the nascent fibers are obtained after being stretched in the coagulation bath;

[0135] S4, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0136] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 4 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft.

[0137] Example 5

[0138] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0139] S1. Prepare a spinning solution, specifically comprising the following steps: mix 4963 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) and 270 g of water to obtain a solvent, add 567 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 140 g of Si4N3 particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, and place the solution at 20° C. for standing and degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 10 wt.%;

[0140] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, the spinning solution is ejected from the spinneret with a diameter of 0.05mm in the spinning device at room temperature and coagulated in a hot air layer at 80°C to obtain primary fibers;

[0141] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0142] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 5 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft.

[0143] Example 6

[0144] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0145] S1. Prepare a spinning solution, specifically comprising the following steps: heat 2704 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 316 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 140 g of ZnO particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, and place the solution at 20° C. for standing and degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 10 wt.%;

[0146] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 100°C, and the spinning speed is 500m / min; then, the raw fiber is obtained by spraying it from a spinneret with a diameter of 0.05mm in the spinning device at room temperature and stretching it in a water coagulation bath, and the coagulation bath temperature is 80°C;

[0147] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0148] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 6 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft weft weaving.

[0149] Example 7

[0150] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0151] S1. Prepare a spinning solution, specifically comprising the following steps: heat 3700 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 415 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 35 g of TiO2 particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, place the solution at 20° C. for standing and degassing, and obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 10 wt.%;

[0152] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer at 80°C to a water coagulation bath, the coagulation bath temperature is 80°C, and the nascent fibers are obtained after being stretched in the coagulation bath;

[0153] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0154] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 7 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft weft weaving.

[0155] Example 8

[0156] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0157] S1. Prepare a spinning solution, specifically comprising the following steps: heat 2345 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 285 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 220 g of TiO2 particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, and place the solution at 20° C. for standing and degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 10 wt.%;

[0158] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer at 80°C to a water coagulation bath, the coagulation bath temperature is 80°C, and the nascent fibers are obtained after being stretched in the coagulation bath;

[0159] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0160] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 8 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft.

[0161] Example 9

[0162] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0163] S1. Prepare a spinning solution, specifically comprising the following steps: heat 5265 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 608 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 205 g of TiO2 particles (particle size of 10±0.1 μm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, and place the solution at 20° C. for standing and degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 10 wt.%;

[0164] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer at 80°C to a water coagulation bath, the coagulation bath temperature is 80°C, and the nascent fibers are obtained after being stretched in the coagulation bath;

[0165] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0166] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 9 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft.

[0167] Example 10

[0168] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0169] S1. Prepare a spinning solution, specifically comprising the following steps: heat 3595 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 415 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 140 g of TiO2 particles (particle size of 0.1±0.05 μm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, and place the solution at 20° C. for standing and degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 10 wt.%;

[0170] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device into a water coagulation bath at room temperature, the coagulation bath temperature is 80°C, and the primary fiber is obtained after being stretched in the coagulation bath;

[0171] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0172] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 10 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft weft weaving.

[0173] Embodiment 11

[0174] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0175] S1. Prepare a spinning solution, specifically comprising the following steps: heat 2845 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 89 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 30 g of TiO2 particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, and place the solution at 20° C. for standing and degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 3 wt.%;

[0176] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer at 80°C to a water coagulation bath, the coagulation bath temperature is 80°C, and the nascent fibers are obtained after being stretched in the coagulation bath;

[0177] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0178] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 11 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft weft weaving.

[0179] Example 12

[0180] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0181] S1. Prepare a spinning solution, specifically comprising the following steps: heat 3250 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 1630 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 550 g of TiO2 particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, and place the solution at 20° C. for standing and degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 30 wt.% (30.02 wt.% is approximately equal to 30 wt.%);

[0182] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer at 80°C to a water coagulation bath, the coagulation bath temperature is 80°C, and the nascent fibers are obtained after being stretched in the coagulation bath;

[0183] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0184] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 12 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft weft weaving.

[0185] Embodiment 13

[0186] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0187] S1. Prepare a spinning solution, specifically comprising the following steps: heat 3595 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 415 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 140 g of TiO2 particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, and place the solution at 20° C. for standing and degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 10 wt.%;

[0188] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then it is ejected from the spinneret with a diameter of 0.05mm in the spinning device at room temperature, and solidified and formed by a hot air layer at 120°C to obtain primary fibers;

[0189] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0190] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 13 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft weft weaving.

[0191] Embodiment 14

[0192] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0193] S1. Prepare a spinning solution, specifically comprising the following steps: heat 3595 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 415 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 140 g of TiO2 particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, and place the solution at 20° C. for standing and degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 10 wt.%;

[0194] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then it is ejected from the spinneret with a diameter of 0.05mm in the spinning device at room temperature, and solidified and formed by a hot air layer at 50°C to obtain primary fibers;

[0195] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, and then collecting the obtained passive cooling photothermal regulation fiber onto a winding roller.

[0196] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 14 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft.

[0197] Embodiment 15

[0198] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0199] S1. Prepare a spinning solution, specifically comprising the following steps: heat 3000 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 330 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) under vigorous stirring to obtain a solution, and place the solution at 20° C. for degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 10 wt.% (9.91 wt.% is approximately equal to 10 wt.%);

[0200] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer at 80°C to a water coagulation bath, the coagulation bath temperature is 80°C, and the nascent fibers are obtained after being stretched in the coagulation bath;

[0201] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, the cross-section of the passive cooling photothermal regulation fiber is as follows Figure 6 As shown, the obtained passive cooling photothermal regulation fiber is then collected on a winding roller;

[0202] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 15 are used as weft yarns and warp yarns respectively, and the fabric is woven by weft and warp.

[0203] Example 16

[0204] The present invention provides a method for preparing a passive cooling photothermal control fiber, comprising the following steps:

[0205] S1. Prepare a spinning solution, specifically comprising the following steps: heat 945 g of 4-methylmorpholine-N-oxide (NMMO, purchased from Sigma-Aldrich) solvent at 110° C. until completely melted, add 1425 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer, purchased from Sigma-Aldrich) and 480 g of TiO2 particles (particle size of 400±100 nm) dried in a vacuum oven at 100° C. for 24 h under vigorous stirring to obtain a solution, and place the solution at 20° C. for standing and degassing to obtain a spinning solution in which the weight proportion of PVDF-HFP in the spinning solution is 50 wt.%;

[0206] S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer at 80°C to a water coagulation bath, the coagulation bath temperature is 80°C, and the nascent fibers are obtained after being stretched in the coagulation bath;

[0207] S3, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber, the cross-section of the passive cooling photothermal regulation fiber is as follows Figure 7 As shown, the obtained passive cooling photothermal regulation fiber is then collected on a winding roller.

[0208] The embodiment of the present application also provides a passive cooling photothermal regulation fabric, and the preparation method thereof is as follows: the passive cooling photothermal regulation fibers prepared in Example 16 are used as weft yarns and warp yarns respectively, and the fabric is woven by warp and weft.

[0209] Comparative Example 1

[0210] This comparative example is a common commercially available white polyester fabric (made of PET).

[0211] Performance Testing

[0212] The solar spectrum weighted reflectivity diagram obtained by simulating the passive cooling photothermal control fibers of different structures obtained in Examples 1, 7, 8, 11, 12, 15, and 16 is as follows: Figure 4 As shown. Specifically, FDTD Solutions was used for modeling and simulation calculations to establish a two-dimensional model structure of passive cooling photothermal control fiber, and randomly distributed nano-medium particles with different refractive indices were constructed internally. Based on the multi-level Mie scattering theory, a micro-nano optical structure with excellent solar radiation band reflectivity and mid-infrared radiation band emissivity was obtained. The specific operation is: randomly adding TiO2 nanoparticles and forming nano-cavities in the PVDF substrate, and reasonably equivalent the cross-section of the fiber fabric to a thin film structure and constructing its two-dimensional model. The width of the model is 20μm, and periodic boundary conditions are used in the x direction of the model to simulate an infinitely large film. Based on the numerical simulation of the multi-level Mie scattering theory, the solar spectral reflectivity of the fiber fabric containing different volume fractions of TiO2 particles and nano-cavities at a thickness of 500μm in the 0.3-20μm band is calculated. Figure 4 From the simulated weighted reflectivity diagram of the solar spectrum, it can be seen that the weighted reflectivity of the solar spectrum in the visible light band of Example 1 is the highest, so the optimal internal structure of the passive cooling photothermal regulation fiber is determined to be a volume ratio of high refractive index nano-medium particles to polymer materials of 14%, and a volume ratio of low refractive index nano-medium particles to polymer materials of 50%.

[0213] The passive cooling photothermal control fiber obtained in Examples 1-15 and the ordinary commercially available white polyester fabric in Comparative Example 1 were subjected to performance tests. The specific operation method is: using a UV-VIS-NIR spectrophotometer combined with an integrating sphere to test the reflectivity of the fabric in the solar radiation (0.3-2.5μm) band, and using a Fourier transform infrared spectrometer combined with an integrating sphere to test the emissivity of the fabric in the mid-infrared (8-13μm) band. The passive cooling photothermal control fabric obtained in Examples 1-15 was subjected to a simulation experiment: the experiment was conducted outdoors with a clear sky, the entire device was placed in a foam box with low thermal conductivity and good insulation, a heating pad was used to simulate human skin, different samples were placed on the heating pad, and the temperature T was measured with a thermocouple attached to the heating pad, and the temperature difference ΔT between each example sample and the comparative example sample was calculated, wherein the comparative example sample was the ordinary commercially available white polyester fabric in Comparative Example 1. The top of the device is covered with a PE film to reduce the influence of thermal convection on the measurement. The power of the heating pad is stable at the power required for the temperature to be 36.5°C when it is not covered. The results are shown in Table 1. When the high refractive index nano-medium particles and the low refractive index nano-medium particles are aerogel powders, their volume ratio is calculated by the formula v = m / ρ (ρ PVDF-HFP =1.77 g / mL, ρ PAN =1.20 g / mL, ρ PVA =1.27g / mL, ρTiO2=4.26g / cm 3 , ρSi4N3=4.26g / cm 3 , ρ ZnO =5.6g / cm 3 ,ρSiO2 aerogel=0.1g / cm 3 ) When the low refractive index nano-medium particles are air holes, their volume ratio and particle size are obtained by relevant tests (BET test).

[0214] Table 1 - Volume ratios of various components in the embodiments and comparative examples, particle size ranges, test results of fabric reflectivity in the solar band and weighted emissivity in the mid-infrared band, and test results of simulated skin passive cooling temperature

[0215]

[0216]

[0217] In Table 1, the volume ratio of the high refractive index nano-medium (n2) to the polymer material refers to: the percentage of the volume of the high refractive index nano-medium in the finally prepared passive cooling photothermal regulation fiber to the volume of the polymer material. It can be understood that when the spinning solution includes the high refractive index nano-medium, the polymer material and the solvent, the volume ratio of the high refractive index nano-medium (n2) to the polymer material in the finally prepared passive cooling photothermal regulation fiber is the same as the volume ratio of the high refractive index nano-medium and the polymer material in the spinning solution.

[0218] In Table 1, if the low-refractive-index nano-medium particles are air holes, then the volume ratio of the low-refractive-index nano-medium particles (n3) to the polymer material refers to: the percentage of the volume of the air holes in the finally prepared passive cooling photothermal regulation fiber to the volume of the polymer material.

[0219] In Table 1, if the low-refractive-index nano-medium particles are SiO2 aerogels, then the volume ratio of the low-refractive-index nano-medium particles (n3) to the polymer material refers to: the percentage of the volume of SiO2 aerogel in the finally prepared passive cooling photothermal regulation fiber to the volume of the polymer material. It can be understood that when the spinning solution includes SiO2 aerogel, polymer material and solvent, the volume ratio of SiO2 aerogel to polymer material in the finally prepared passive cooling photothermal regulation fiber is the same as the volume ratio of SiO2 aerogel to polymer material in the spinning solution.

[0220] In Table 1, if the low-refractive-index nano-medium particles are air holes, the particle size of the low-refractive-index nano-medium particles refers to: the particle size of the air holes in the passive cooling photothermal regulation fiber finally prepared.

[0221] In Table 1, if the low-refractive-index nano-medium particles are SiO2 aerogels, then the particle size of the low-refractive-index nano-medium particles refers to: the particle size of the SiO2 aerogels in the passive cooling photothermal regulation fiber finally prepared.

[0222] Fig. 9 This is a pore size distribution data diagram of the passive cooling photothermal regulation fiber prepared in Example 1. The volume ratio and particle size can be obtained through BET testing.

[0223] As can be seen from Table 1, the weighted emissivity of Examples 1-16 in the mid-infrared band (8-13 μm) and the weighted reflectivity in the solar radiation band (0.3-2.5 μm) are significantly higher than those of the comparative example, and the weighted emissivity and solar radiation weighted reflectivity of Examples 1 and 4 are the highest, but in consideration of economic factors, Example 1 is preferred. Compared with Example 1, the intrinsic vibration frequencies of the CH bonds and CF bonds contained in the PVDF-HFP polymer used in Example 1 are in the "atmospheric window" band range, so Example 1 has a higher mid-infrared weighted emissivity. The refractive index difference (Δn) between the high refractive index nano-medium particles Si4N3 (n2=2.4) selected in Example 5 and the high refractive index nano-medium particles ZnO (n2=2.0) selected in Example 6 and the polymer PVDF-HFP (n1=1.42) is smaller than the Δn between the high refractive index nano-medium particles TiO2 (n2=2.76) selected in Example 1 and the polymer PVDF-HFP, so when the content of the nano-medium particles is the same, the scattering efficiency of solar radiation in Examples 5 and 6 is relatively lower, and thus has a lower weighted reflectivity of solar radiation. The content of the high refractive index nano-medium particles in Example 7 is too little, resulting in the inability to achieve effective scattering of electromagnetic waves in the sunlight radiation band, and thus has a lower weighted reflectivity of solar radiation. The content of high refractive index nano-medium particles in Example 8 is more than that in Example 1, but the weighted reflectivity in the solar radiation band (0.3-2.5 μm) is lower than that in Example 1. This is because too many high refractive index nano-medium particles are piled up inside the fiber, and the extrusion and contact between particles increase, resulting in that a single particle cannot play the optimal scattering effect, and therefore has a lower weighted reflectivity of solar radiation. According to the Mie scattering principle, the nano-medium particles that are too large or too small in Examples 9-10 and Examples 13-14 cannot achieve effective scattering of electromagnetic waves in the sunlight radiation band, and therefore have a lower weighted reflectivity of solar radiation. Compared with Example 1, in Examples 11 and 12, too many or too few low refractive index nano-medium particles will lead to a reduction in the scattering interface inside the fiber, and cannot achieve effective scattering of electromagnetic waves in the sunlight radiation band, and therefore have a lower weighted reflectivity of solar radiation. In Example 15, there are no high refractive index nano-medium particles. Compared with Example 1, the scattering interface that can be scattered in the fiber is significantly reduced, and therefore has a lower weighted reflectivity of solar radiation. Compared with Example 1, Example 16 increases the mass percentage of polymer materials in the spinning solution so that the fiber contains only high-refractive-index nano-medium particles, resulting in a significant reduction in the scattering interface in the fiber where scattering can occur, and thus has a lower solar radiation weighted reflectivity. Compared with the comparative example, the fiber prepared in Example 1 has both two types of nano-medium particles with light scattering and characteristic functional group chemical bonds with high absorption in the mid-infrared band, and therefore has excellent mid-infrared weighted emissivity and solar radiation weighted reflectivity.

[0224] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a passive cooling photothermal control fiber, characterized in that: The following steps are involved: The spinning solution is spun to obtain passive cooling photothermal regulation fiber; The spinning solution comprises a high-refractive-index nano-medium, a polymer material and a solvent; The high refractive index nano-medium is an inorganic nano-particle, and the inorganic nano-particle includes any one of titanium dioxide, silicon nitride, and zinc oxide; The particle size of the high refractive index nano-medium is 0.04 μm to 10.1 μm; The mass fraction of the polymer material in the spinning solution is 3-50%, and the mass of the high refractive index nano-medium in the spinning solution is 1-80% of the mass of the polymer material; The polymer material includes any one of polyacrylonitrile, polyvinyl alcohol, and polyvinylidene fluoride-hexafluoropropylene copolymer; The solvent includes at least one of 4-methylmorpholine-N-oxide, N,N-dimethylformamide, acetone, and water; The spinning solution is delivered to a spinning device, and then ejected from the spinneret holes of the spinneret in the spinning device to obtain an ejected solution; The sprayed liquid passes through an air layer or a coagulation bath to form primary fibers; The nascent fiber is washed and stretched to form a passive cooling photothermal control fiber; Wherein, the spinning temperature is 80-110°C and the spinning speed is 500-2000m / min; Alternatively, the method for preparing the passive cooling photothermal regulation fiber comprises the following steps: S1. Preparation of SiO2 aerogel powder: Put SiO2 aerogel powder with a particle size of 5 μm into a ball mill, set the ball milling speed to 400 rpm, and the ball milling time to 13 h, and finally prepare SiO2 aerogel powder with a particle size of 400±100 nm; S2, preparing spinning solution, specifically comprising the following steps: heating 263g of 4-methylmorpholine-N-oxide solvent at 110°C until completely melted, adding 415g of PVDF-HFP, 140g of TiO2 particles dried in a vacuum oven at 100°C for 24h and 11.7g of SiO2 aerogel powder prepared in S1 under vigorous stirring to obtain a solution, placing the solution at 20°C for degassing to obtain a spinning solution; the particle size of the TiO2 particles is 400±100nm; S3, the spinning solution in S2 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer at 80°C to a water coagulation bath, the coagulation bath temperature is 80°C, and the nascent fibers are obtained after being stretched in the coagulation bath; S4, washing and stretching the nascent fiber to form a passive cooling photothermal regulation fiber; Alternatively, the method for preparing the passive cooling photothermal regulation fiber comprises the following steps: S1, preparing a spinning solution, specifically comprising the following steps: heating 3000 g of 4-methylmorpholine-N-oxide solvent at 110° C. until completely melted, adding 330 g of PVDF-HFP under vigorous stirring to obtain a solution, and placing the solution at 20° C. for degassing to obtain a spinning solution; S2, the spinning solution in S1 is transferred to the spinning pot of the spinning device after passing through a candle filter, the spinning temperature is 110°C, and the spinning speed is 500m / min; then, at room temperature, it is ejected from a spinneret with a diameter of 0.05mm in the spinning device through an air layer at 80°C to a water coagulation bath, the coagulation bath temperature is 80°C, and the nascent fibers are obtained after being stretched in the coagulation bath; S3, washing and stretching the nascent fiber to form passive cooling photothermal regulation fiber.

2. A passive cooling light and heat control fabric, characterized in that: The passive cooling photothermal regulation fiber is prepared by the preparation method as claimed in claim 1 and then woven.

3. Use of the passive cooling photothermal regulation fiber prepared by the preparation method according to claim 1 or the passive cooling photothermal regulation fabric according to claim 2 in the preparation of passive cooling materials.

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