Intelligent temperature-regulating radiation refrigeration fiber as well as preparation method and application thereof

Abstract

The invention relates to an intelligent temperature-regulating radiation refrigeration fiber as well as a preparation method and application thereof, i.e., based on the difference of emission performance of polyurethane in a mid-infrared band (8-13 microns) under different temperature conditions, the intelligent temperature-regulating radiation refrigeration fiber is prepared through synthesis of room-temperature reversible solid-solid phase change polyurethane, surface grafting dispersion modification of nanoparticles, polyurethane / nanoparticle dry spinning processing and the like. The invention discloses a method for preparing fibers and textiles with high and medium infrared band emissivity (relatively strong radiation refrigeration effect) under a high-temperature condition and low and medium infrared band emissivity (relatively weak radiation refrigeration effect) under a low-temperature condition. According to the method, the radiation refrigeration effect of the textile can be intelligently regulated and controlled based on the phase state structure change of the fiber material, and then the thermal comfort requirement of clothes under the high-temperature and low-temperature conditions is met. In addition, the method is simple in process and remarkable in effect, and overcomes the defects in the prior art.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and fiber preparation technology, specifically to a smart temperature-regulating radiative cooling fiber and its preparation method and application. More particularly, it relates to a radiative cooling polyurethane fiber with smart temperature regulation function and its preparation method and application, and especially to the preparation of smart temperature-regulating radiative cooling fiber through room temperature reversible solid-solid phase change polyurethane synthesis, surface grafting and dispersion modification of nanoparticles, and dry spinning of polyurethane / nanoparticles. Background Technology

[0002] With global warming and the increasing demand for functional textile materials, the development of fiber materials with passive cooling capabilities has become a research hotspot. Radiative cooling materials can cool objects by radiating heat into outer space through the atmospheric transmission window (8–13 μm), thus achieving cooling without energy consumption. However, most existing radiative cooling materials are film-like or rigid structures, making it difficult to meet the requirements for flexibility and textile fabrication. Therefore, developing flexible fiber materials that combine good mechanical properties with radiative cooling capabilities is of great significance. However, most current radiative cooling fiber materials are only suitable for a single environment and cannot actively adjust the radiative cooling performance of textiles according to ambient temperature conditions.

[0003] For example, patent CN115772351A provides a passive radiation cooling material, its preparation method, and its uses, including: styrene-acrylic / silicone-acrylic emulsion, high-reflectivity functional filler, nano-silica, hollow glass microspheres, additives, organic solvents, and a yellow oil-based dye; wherein, the high-reflectivity filler is a wide-bandgap compound; this invention achieves a bright yellow appearance while ensuring cooling and energy-saving effects; thus solving the technical problem in the prior art that passive radiation materials cannot simultaneously meet the requirements for sunlight reflection and diverse color tones.

[0004] Patent CN113862815A discloses a passive radiative cooling material. It uses a fluorinated resin, capable of directly radiating heat into space, as a base material. Specially treated modified graphene with extremely high thermal conductivity and reflectivity is introduced into this resin, and after thorough mixing, a porous structure capable of efficiently reflecting sunlight is prepared. Each component works in harmony to maximize its own properties, resulting in extremely high sunlight reflection and heat scattering effects. It can achieve a maximum reflection efficiency of >98% for visible and infrared light, and an infrared emissivity of >99% in the atmospheric window band. This invention can significantly cool objects it covers without the need for external energy sources.

[0005] Patent CN116004026A relates to a radiative cooling material and its application. This radiative cooling material reflects ultraviolet and / or visible and / or near-infrared light from sunlight and emits heat through an atmospheric window via infrared radiation. The radiative cooling material comprises a polymer matrix material and a primary inorganic filler. The primary inorganic filler is selected from borate, and the mass fraction of borate in the radiative cooling material is 15%–60%, with an average particle size of 0.1–35 μm. The mass ratio of total inorganic filler to polymer matrix material in the radiative cooling material is (3-6):(7-4). The radiative cooling material of this invention has a solar reflectivity of over 92% during the day, exhibits good radiative cooling effect, and also possesses good weather resistance and a long service life.

[0006] While the aforementioned patents have made breakthroughs in the research and development of radiation cooling materials, they still suffer from the following technical pain points and limitations, hindering their expansion in the field of flexible textiles: insufficient adaptability to form and flexibility, limited environmental adaptability, lack of dynamic control capabilities, low integration of textile functions, and poor compatibility between the manufacturing process and the textile industry. These shortcomings make it difficult for existing radiation cooling materials to simultaneously achieve "flexible textile form," "dynamic environmental adaptability," and "practical functional integration." Therefore, there is an urgent need to develop a new type of fiber material that combines excellent mechanical properties, adaptive cooling regulation capabilities, and compatibility with textile industry processes. Summary of the Invention

[0007] Based on the shortcomings of the existing technology, the purpose of this application is to provide a smart temperature-regulating radiative cooling fiber and its preparation method and application. Based on the difference in the emission performance of polyurethane in the mid-infrared band under different temperature conditions, the fiber and textiles with excellent smart temperature regulation and radiative cooling effects are prepared by designing room temperature reversible solid-solid phase change polyurethane, surface grafting and dispersion modification of nanoparticles, and polyurethane / nanoparticle dry spinning processing.

[0008] Polyurethane, due to its excellent spinnability, flexibility, and film-forming properties, has become an important matrix for functional fiber research. Introducing nanoparticles with high infrared reflectivity, such as zirconium oxide, alumina, boron nitride, and calcium fluoride, into the polyurethane system can effectively improve its radiation efficiency in the atmospheric window band, endowing the fiber with good passive cooling properties. Furthermore, polyurethane exhibits a typical microphase separation structure at room temperature, presenting mutually separated soft and hard phases at the nanoscale. When the soft phase melts, the macromolecular chains move vigorously, resulting in high infrared emissivity and weak radiative cooling effect. Conversely, when the soft phase crystallizes, the macromolecular movement is restricted, leading to low infrared emissivity and significant radiative cooling effect. Therefore, by designing the molecular structure and developing polyurethane fibers with a soft phase transition temperature at room temperature, and utilizing the differences in mid-infrared emissivity under different temperature conditions, it is hoped that radiative cooling fibers and textiles with intelligent temperature regulation functions can be developed.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] Technical solution 1 provides an intelligent temperature-regulating radiative cooling fiber. The intelligent temperature-regulating radiative cooling fiber has a fineness of 40-100D and a strength of 1.4-1.9 cN / dtex.

[0011] Technical solution 2 provides a method for preparing intelligent temperature-regulating radiative cooling fiber, the preparation process including the following steps:

[0012] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0013] S1. Activation of hydroxyl groups on the surface of nanoparticles: Weigh nanoparticles and boric acid, mix them thoroughly and place them in a crucible, then place the crucible in a high-temperature furnace for calcination. After natural cooling, wash, centrifuge and dry to obtain nanoparticles with activated hydroxyl groups on the surface.

[0014] Furthermore, the nanoparticles mentioned in step S1 are selected from one or more of the following: nano-zirconia, nano-alumina, nano-boron nitride, or nano-calcium fluoride.

[0015] Further, the ratio of nanoparticles to boric acid in step S1 is (5-15) parts: 1 part, preferably 5 parts: 1 part;

[0016] Furthermore, the calcination temperature in step S1 is 400–600°C, and the time is 2–5 hours;

[0017] S2. Hydrophobic modification of nanoparticles: The hydroxyl-activated nanoparticles, catalyst, and modifier obtained in step S1 are mixed evenly, heated to react, and then centrifuged, washed, and dried to obtain highly dispersed hydrophobic nanoparticles.

[0018] Further, the catalyst in step S2 is selected from one or more of dodecylbenzenesulfonic acid, benzenesulfonic acid, or p-toluenesulfonic acid;

[0019] Furthermore, the modifier mentioned in step S2 is a long-chain alkanol with the molecular formula CH3(CH2). n OH, where n = 8 to 12;

[0020] Further, in step S2, the mass ratio of the hydroxyl-activated nanoparticles, catalyst, and modifier is 50 parts: (0.5-1) parts: (200-400) parts;

[0021] Furthermore, the heating reaction conditions described in step S2 are 80–120°C for 3–7 hours;

[0022] Furthermore, the diameter of the highly dispersed hydrophobic nanoparticles obtained in step S2 is 200–500 nm.

[0023] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0024] S3. Preparation of polyurethane prepolymer: Polyether glycol and polycaprolactone glycol are mixed evenly, then diphenylmethane diisocyanate is added and heated to react until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeds 96%, thus obtaining polyurethane prepolymer.

[0025] Further, the polyether diol mentioned in step S3 is one of polytetrahydrofuran ether diol and polytrimethylene ether diol; the number average molecular weight of the polyether diol and polycaprolactone diol is 1000-2000 g / mol;

[0026] Furthermore, the polyether glycol and polycaprolactone glycol mentioned in step S3 need to be dehydrated before use. The dehydration process involves drying and dehydrating them in a vacuum oven.

[0027] Further, in step S3, the mass ratio of polyether diol, polycaprolactone diol and diphenylmethane diisocyanate is (80-90) parts: (10-20) parts: 26 parts;

[0028] Furthermore, the heating reaction conditions described in step S3 are 80–85°C for 4–6 hours;

[0029] In some specific embodiments, the conversion rate of the isocyanate bond (NCO) is determined by di-n-butylamine titration. Diphenylmethane diisocyanate reacts quantitatively with excess di-n-butylamine ((C4H9)2NH) to form a urea bond. The remaining di-n-butylamine is back-titrated with a standard hydrochloric acid solution, and the NCO content is determined by calculating the amount of di-n-butylamine consumed. The specific experimental steps are routine procedures for those skilled in the art and will not be described in detail here. In some other embodiments, hydroxyl compound titration, amine value method, or analysis and quantification using instruments such as spectrometers and chromatograms can be used, which does not affect the inventiveness of this invention.

[0030] S4. Chain extension reaction of polyurethane: After cooling the prepolymer obtained in step S3 to 50°C, 1,4-butanediol is added to carry out the chain extension reaction. Then, n-butanol is added to terminate the reaction, and finally room temperature reversible solid-solid phase change polyurethane is obtained.

[0031] Furthermore, the room-temperature reversible solid-solid phase change polyurethane described in step S4 has a soft-hard phase separation structure at the nanoscale, and the melting point of the soft phase is 32-37°C.

[0032] Further, in step S4, the molar amount of 1,4-butanediol added is 94-96% (preferably 95%) of the number of moles of residual isocyanate bonds (NCO) in the reaction system; the molar amount of n-butanol added is 4-6% (preferably 5%) of the number of moles of residual isocyanate bonds (NCO) in the reaction system.

[0033] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0034] S5. Preparation of polyurethane spinning solution: The room temperature reversible solid-solid phase change polyurethane obtained in step S4 and the highly dispersed hydrophobic nanoparticles obtained in step S2 are dissolved in dimethylacetamide and mixed evenly to obtain polyurethane spinning solution.

[0035] Further, in step S5, the mass ratio of the room-temperature reversible solid-solid phase change polyurethane, highly dispersed hydrophobic nanoparticles, and dimethylacetamide is 100 parts: (15-25) parts: (800-1000) parts; preferably 100 parts: (15-25) parts: 900 parts.

[0036] S6. Dry spinning of polyurethane: The spinning solution obtained in step S5 is sprayed out through a shaped spinneret and the solvent is evaporated in hot air to form a filament bundle. After the filament bundle is drawn and shaped, intelligent temperature-regulating radiation cooling fiber is obtained.

[0037] Furthermore, the irregularly shaped spinneret mentioned in step S6 is one of a cross shape, a trilobal shape, or a flat shape;

[0038] Furthermore, the cross-section of the intelligent temperature-regulating radiative cooling fiber obtained in step S6 is one of the following: cross-shaped, trilobal, or flat.

[0039] Furthermore, in step S6, the dry spinning temperature is 80-110℃, the spinning speed is 500-600m / min, the airflow speed is 0.5-3m / s, and the stretching ratio is 1.5-2 times.

[0040] Technical solution 3 provides an application of intelligent temperature-regulating radiative cooling fiber, which is used to manufacture adaptive radiative cooling textiles.

[0041] Technical solution 4 provides an adaptive radiation cooling textile, wherein the textile has a basis weight of 100 g / m². 2 The textile has a solar reflectance of 91%-95% and a mid-infrared emissivity of 73%-77% at 30°C, with a temperature difference of 2.1-2.6°C compared to the ambient temperature. At 40°C, the textile has a solar reflectance of 91%-95% and a mid-infrared emissivity of 93%-96%, with a temperature difference of 4.9-5.6°C compared to the ambient temperature.

[0042] Compared with the prior art, this application has at least the following improvements and beneficial effects:

[0043] (1) The dispersibility of inorganic particles in polyurethane matrix is ​​improved by surface hydrophobic modification technology; polyurethane and fiber with obvious microphase separation structure and soft phase transition temperature at room temperature are prepared by molecular structure regulation and inorganic particle doping method.

[0044] (2) The polyurethane fiber prepared by this invention has good spinnability and mechanical properties. At the same time, it has high mid-infrared emissivity and significant radiative cooling effect under high temperature conditions, while the mid-infrared emissivity weakens and the radiative cooling effect decreases at lower temperatures. Therefore, the cooling effect can be intelligently controlled, making it suitable for preparing individual cooling, sun protection fabrics, functional clothing, etc. Attached Figure Description

[0045] Figure 1 SEM image of the nano-zirconia powder provided in step S2 of Example 1;

[0046] Figure 2 The infrared thermal image of the fabric provided in Example 1 is obtained under light conditions at room temperature of approximately 40°C. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below with reference to specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0048] Unless otherwise specified, the source of all raw materials used in this invention is not particularly limited; they may be purchased from the market or prepared using conventional methods known to those skilled in the art. All testing equipment is well-known in the industry.

[0049] The test method for the performance of radiation-cooling fabrics involves placing the fabrics in environments of 30℃ and 40℃ respectively, and testing their radiation-cooling performance under different conditions.

[0050] (1) The emissivity of the fabric to the mid-infrared band (8-13μm) was tested using a Fourier transform infrared spectrometer containing an integrating sphere (a hollow sphere with an inner wall coated with a high diffuse reflectance material such as barium sulfate or polytetrafluoroethylene, whose core function is to uniformly scatter and mix the incident light to achieve accurate measurement of optical parameters such as light flux, reflectivity, and emissivity).

[0051] (2) The emissivity of the fabric to the solar light band (250-2200nm) was tested using an ultraviolet-visible-near-infrared spectrometer containing an integrating sphere;

[0052] (3) Use thermocouples to test the temperature under the fabric covering conditions, and evaluate the radiative cooling effect of the fabric by the difference between the temperature and the ambient temperature.

[0053] Example 1

[0054] A smart temperature-regulating radiative cooling fiber and its preparation method, the preparation process includes the following steps:

[0055] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0056] S1. Activation of hydroxyl groups on the surface of nano-zirconia. Weigh 50g of nano-zirconia and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine at 600℃ for 2 hours. After natural cooling, wash (the washing reagents are deionized water and ethanol, the same in the following examples), centrifuge, and dry (preferably vacuum drying, preferably at 60℃, the same below) to obtain nano-zirconia with activated hydroxyl groups on the surface.

[0057] S2. Hydrophobic modification of nano-zirconia. 50g of hydroxyl-activated nano-zirconia obtained in step S1, 1g of dodecylbenzenesulfonic acid, and 200g of decacarbonyl alcohol were uniformly mixed and reacted at 120℃ for 4h. After centrifugation, washing, and drying, highly dispersed hydrophobic nano-zirconia with a particle size of 200-400nm and a water contact angle of 116° was obtained.

[0058] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0059] S3. Preparation of polyurethane prepolymer. 90g of dehydrated polytetrahydrofuran ether diol with a number average molecular weight of 2000g / mol was uniformly mixed with 10g of dehydrated polycaprolactone diol with a number average molecular weight of 2000g / mol. Then, 26g of diphenylmethane diisocyanate was added and reacted at 85℃ for 4 hours until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeded 96%, thus obtaining polyurethane prepolymer.

[0060] S4. Chain extension reaction of polyurethane. The prepolymer obtained in step S3 was cooled to 50°C, and 1,4-butanediol was added to the reactants to carry out a chain extension reaction (the molar amount of 1,4-butanediol added was 95% of the molar amount of residual NCO in the reaction system). Then, n-butanol was added to terminate the reaction (the molar amount of n-butanol added was 5% of the molar amount of residual NCO in the reaction system), and finally, a room temperature reversible solid-solid phase change polyurethane was obtained, which has a microphase separation structure at room temperature and a soft phase melting point of 33°C.

[0061] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0062] S5. Preparation of polyurethane spinning solution. 100g of the room temperature reversible solid-solid phase change polyurethane obtained in step S4 and 15g of the highly dispersed hydrophobic nano-zirconia obtained in step S2 were dissolved in 900g of dimethylacetamide to prepare polyurethane spinning solution.

[0063] S6. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a cross-shaped spinneret, and the solvent evaporates in hot air to form a fiber bundle. After the fiber bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a cross-shaped cross-section, a fineness of 50D, and a strength of 1.9cN / dtex.

[0064] (4) Preparation of adaptive radiation-cooled textiles

[0065] The intelligent temperature-regulating radiant cooling fiber obtained in step S6 is woven to produce a product with a basis weight of 100 g / m. 2The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 92%, a mid-infrared emissivity of 76%, and a temperature difference of 2.1℃ with the environment (this refers to the temperature difference between the fabric and the environment after the temperature has stabilized; the specific exposure time is generally not specified. All differences indicate that the fabric is at a lower temperature). At 40℃, the fabric has a solar reflectance of 93%, a mid-infrared emissivity of 94%, and a temperature difference of 5.6℃ with the environment.

[0066] Example 2

[0067] A smart temperature-regulating radiative cooling fiber and its preparation method, the preparation process includes the following steps:

[0068] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0069] S1. Activation of hydroxyl groups on the surface of nano-boron nitride. Weigh 50g of nano-boron nitride and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine at 600℃ for 2 hours. After natural cooling, wash, centrifuge, and dry to obtain nano-boron nitride with activated surface hydroxyl groups.

[0070] S2. Hydrophobic modification of boron nitride nanoparticles. 50g of hydroxyl-activated boron nitride nanoparticles obtained in step S1, 1g of dodecylbenzenesulfonic acid, and 200g of decacarbonyl alcohol were uniformly mixed and reacted at 120℃ for 4h. Afterwards, centrifugation, washing, and drying were performed to obtain highly dispersed hydrophobic boron nitride nanoparticles with a particle size of 200–400nm and a water contact angle of 117°.

[0071] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0072] S3. Preparation of polyurethane prepolymer. 85g of dehydrated polytetrahydrofuran ether diol with a number average molecular weight of 2000g / mol was uniformly mixed with 15g of dehydrated polycaprolactone diol with a number average molecular weight of 2000g / mol. Then, 26g of diphenylmethane diisocyanate was added and reacted at 85℃ for 4 hours until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeded 96%, thus obtaining polyurethane prepolymer.

[0073] S4. Chain extension reaction of polyurethane. The prepolymer obtained in step S3 was cooled to 50°C, and 1,4-butanediol was added to the reactants to carry out a chain extension reaction (the molar amount of 1,4-butanediol added was 95% of the molar amount of residual NCO in the reaction system). Then, n-butanol was added to terminate the reaction (the molar amount of n-butanol added was 5% of the molar amount of residual NCO in the reaction system), and finally, a room temperature reversible solid-solid phase change polyurethane was obtained, which has a microphase separation structure at room temperature and a soft phase melting point of 34°C.

[0074] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0075] S5. Preparation of polyurethane spinning solution. 100g of the room temperature reversible solid-solid phase change polyurethane obtained in step S4 and 15g of the highly dispersed hydrophobic nano-boron nitride obtained in step S2 were dissolved in 900g of dimethylacetamide to prepare a polyurethane spinning solution.

[0076] S6. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a trilobal spinneret, and the solvent evaporates in hot air to form a filament bundle. After the filament bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a trilobal cross-section, a fineness of 50D, and a strength of 1.9cN / dtex.

[0077] (4) Preparation of adaptive radiation-cooled textiles

[0078] The intelligent temperature-regulating radiant cooling fiber obtained in step S6 is woven to produce a product with a basis weight of 100 g / m. 2 The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 93%, a mid-infrared emissivity of 75%, and a temperature difference of 2.2℃ with the environment. At 40℃, the fabric has a solar reflectance of 92%, a mid-infrared emissivity of 93%, and a temperature difference of 5.2℃ with the environment.

[0079] Example 3

[0080] A smart temperature-regulating radiative cooling fiber and its preparation method, the preparation process includes the following steps:

[0081] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0082] S1. Activation of hydroxyl groups on the surface of nano-alumina. Weigh 50g of nano-alumina and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine at 600℃ for 2 hours. After natural cooling, wash, centrifuge, and dry to obtain nano-alumina with activated hydroxyl groups on the surface.

[0083] S2. Hydrophobic modification of nano-alumina. 50g of hydroxyl-activated nano-alumina obtained in step S1, 1g of dodecylbenzenesulfonic acid, and 250g of undecanoic acid were uniformly mixed and reacted at 120℃ for 3h. Afterwards, centrifugation, washing, and drying were performed to obtain highly dispersed hydrophobic nano-alumina with a particle size of 220–450nm and a water contact angle of 118°.

[0084] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0085] S3. Preparation of polyurethane prepolymer. 80g of dehydrated polytetrahydrofuran ether diol with a number average molecular weight of 2000g / mol was uniformly mixed with 20g of dehydrated polycaprolactone diol with a number average molecular weight of 2000g / mol. Then, 26g of diphenylmethane diisocyanate was added and reacted at 85℃ for 4 hours until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeded 96%, thus obtaining polyurethane prepolymer.

[0086] S4. Chain extension reaction of polyurethane. The prepolymer obtained in step S3 was cooled to 50°C, and 1,4-butanediol was added to the reactants to carry out a chain extension reaction (the molar amount of 1,4-butanediol added was 95% of the molar amount of residual NCO in the reaction system). Then, n-butanol was added to terminate the reaction (the molar amount of n-butanol added was 5% of the molar amount of residual NCO in the reaction system), and finally, a room temperature reversible solid-solid phase change polyurethane was obtained, which has a microphase separation structure at room temperature and a soft phase melting point of 37°C.

[0087] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0088] S5. Preparation of polyurethane spinning solution. 100g of the room temperature reversible solid-solid phase change polyurethane obtained in step S4 and 15g of the highly dispersed hydrophobic nano-alumina obtained in step S2 were dissolved in 900g of dimethylacetamide to prepare a polyurethane spinning solution.

[0089] S6. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a flat spinneret, and the solvent evaporates in hot air to form a filament bundle. After the filament bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a flat cross-section, a fineness of 50D, and a strength of 1.8cN / dtex.

[0090] (4) Preparation of adaptive radiation-cooled textiles

[0091] The intelligent temperature-regulating radiant cooling fiber obtained in step S6 is woven to produce a product with a basis weight of 100 g / m. 2 The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 91%, a mid-infrared emissivity of 77%, and a temperature difference of 2.1℃ with the environment. At 40℃, the fabric has a solar reflectance of 91%, a mid-infrared emissivity of 94%, and a temperature difference of 5.1℃ with the environment.

[0092] Example 4

[0093] A smart temperature-regulating radiative cooling fiber and its preparation method, the preparation process includes the following steps:

[0094] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0095] S1. Activation of hydroxyl groups on the surface of nano-calcium fluoride. Weigh 50g of nano-calcium fluoride and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine at 600℃ for 2 hours. After natural cooling, wash, centrifuge, and dry to obtain nano-calcium fluoride with activated surface hydroxyl groups.

[0096] S2. Hydrophobic modification of nano-calcium fluoride. 50g of hydroxyl-activated nano-calcium fluoride obtained in step S1, 1g of dodecylbenzenesulfonic acid, and 250g of undecanoic acid were uniformly mixed and reacted at 120℃ for 3h. Afterwards, centrifugation, washing, and drying were performed to obtain highly dispersed hydrophobic nano-calcium fluoride with a particle size of 220–450nm and a water contact angle of 117°.

[0097] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0098] S3. Preparation of polyurethane prepolymer. 90g of dehydrated polytetrahydrofuran ether diol with a number average molecular weight of 2000g / mol was uniformly mixed with 10g of dehydrated polycaprolactone diol with a number average molecular weight of 2000g / mol. Then, 26g of diphenylmethane diisocyanate was added and reacted at 85℃ for 4 hours until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeded 96%, thus obtaining polyurethane prepolymer.

[0099] S4. Chain extension reaction of polyurethane. The prepolymer obtained in step S3 was cooled to 50°C, and 1,4-butanediol was added to the reactants to carry out a chain extension reaction (the molar amount of 1,4-butanediol added was 95% of the molar amount of residual NCO in the reaction system). Then, n-butanol was added to terminate the reaction (the molar amount of n-butanol added was 5% of the molar amount of residual NCO in the reaction system), and finally, a room temperature reversible solid-solid phase change polyurethane was obtained, which has a microphase separation structure at room temperature and a soft phase melting point of 33°C.

[0100] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0101] S5. Preparation of polyurethane spinning solution. 100g of the room temperature reversible solid-solid phase change polyurethane obtained in step S4 and 15g of the highly dispersed hydrophobic nano-calcium fluoride obtained in step S2 were dissolved in 900g of dimethylacetamide to prepare polyurethane spinning solution.

[0102] S6. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a cross-shaped spinneret, and the solvent evaporates in hot air to form a fiber bundle. After the fiber bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a cross-shaped cross-section, a fineness of 50D, and a strength of 1.9cN / dtex.

[0103] (4) Preparation of adaptive radiation-cooled textiles

[0104] The intelligent temperature-regulating radiant cooling fiber obtained in step S6 is woven to produce a product with a basis weight of 100 g / m. 2 The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 91%, a mid-infrared emissivity of 75%, and a temperature difference of 2.2℃ with the environment. At 40℃, the fabric has a solar reflectance of 94%, a mid-infrared emissivity of 94%, and a temperature difference of 4.9℃ with the environment.

[0105] Example 5

[0106] A smart temperature-regulating radiative cooling fiber and its preparation method, the preparation process includes the following steps:

[0107] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0108] S1. Activation of hydroxyl groups on the surface of nano-boron nitride. Weigh 50g of nano-boron nitride and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine it at 500℃ for 4 hours. After natural cooling, wash, centrifuge, and dry to obtain nano-boron nitride with activated surface hydroxyl groups.

[0109] S2. Hydrophobic modification of boron nitride nanoparticles. 50g of hydroxyl-activated boron nitride nanoparticles obtained in step S1, 1g of dodecylbenzenesulfonic acid, and 300g of dodecyl alcohol were uniformly mixed and reacted at 120℃ for 3h. Afterwards, centrifugation, washing, and drying were performed to obtain highly dispersed hydrophobic boron nitride nanoparticles with a particle size of 250–480nm and a water contact angle of 116°.

[0110] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0111] S3. Preparation of polyurethane prepolymer. 85g of dehydrated polytetrahydrofuran ether diol with a number average molecular weight of 2000g / mol was uniformly mixed with 15g of dehydrated polycaprolactone diol with a number average molecular weight of 2000g / mol. Then, 26g of diphenylmethane diisocyanate was added and reacted at 85℃ for 4 hours until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeded 96%, thus obtaining polyurethane prepolymer.

[0112] S4. Chain extension reaction of polyurethane. The prepolymer obtained in step S3 was cooled to 50°C, and 1,4-butanediol was added to the reactants to carry out a chain extension reaction (the molar amount of 1,4-butanediol added was 95% of the molar amount of residual NCO in the reaction system). Then, n-butanol was added to terminate the reaction (the molar amount of n-butanol added was 5% of the molar amount of residual NCO in the reaction system), and finally, a room temperature reversible solid-solid phase change polyurethane was obtained, which has a microphase separation structure at room temperature and a soft phase melting point of 34°C.

[0113] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0114] S5. Preparation of polyurethane spinning solution. 100g of the room temperature reversible solid-solid phase change polyurethane obtained in step S4 and 20g of the highly dispersed hydrophobic nano-boron nitride obtained in step S2 were dissolved in 900g of dimethylacetamide to prepare a polyurethane spinning solution.

[0115] S6. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a trilobal spinneret, and the solvent evaporates in hot air to form a filament bundle. After the filament bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a trilobal cross-section, a fineness of 50D, and a strength of 1.6cN / dtex.

[0116] (4) Preparation of adaptive radiation-cooled textiles

[0117] The intelligent temperature-regulating radiant cooling fiber obtained in step S6 is woven to produce a product with a basis weight of 100 g / m. 2 The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 94%, a mid-infrared emissivity of 73%, and a temperature difference of 2.3℃ with the environment. At 40℃, the fabric has a solar reflectance of 94%, a mid-infrared emissivity of 95%, and a temperature difference of 5.0℃ with the environment.

[0118] Example 6

[0119] A smart temperature-regulating radiative cooling fiber and its preparation method, the preparation process includes the following steps:

[0120] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0121] S1. Activation of hydroxyl groups on the surface of nano-zirconia. Weigh 50g of nano-zirconia and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine at 400℃ for 6 hours. After natural cooling, wash, centrifuge, and dry to obtain nano-zirconia with activated hydroxyl groups on the surface.

[0122] S2. Hydrophobic modification of nano-zirconia. 50g of hydroxyl-activated nano-zirconia obtained in step S1, 1g of dodecylbenzenesulfonic acid, and 300g of dodecyl alcohol were uniformly mixed and reacted at 80℃ for 7h. After centrifugation, washing, and drying, highly dispersed hydrophobic nano-zirconia with a particle size of 250-480nm and a water contact angle of 116° was obtained.

[0123] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0124] S3. Preparation of polyurethane prepolymer. 80g of dehydrated polytetrahydrofuran ether diol with a number average molecular weight of 2000g / mol was uniformly mixed with 20g of dehydrated polycaprolactone diol with a number average molecular weight of 2000g / mol. Then, 26g of diphenylmethane diisocyanate was added and reacted at 80℃ for 6 hours until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeded 96%, thus obtaining polyurethane prepolymer.

[0125] S4. Chain extension reaction of polyurethane. The prepolymer obtained in step S3 was cooled to 50°C, and 1,4-butanediol was added to the reactants to carry out a chain extension reaction (the molar amount of 1,4-butanediol added was 95% of the molar amount of residual NCO in the reaction system). Then, n-butanol was added to terminate the reaction (the molar amount of n-butanol added was 5% of the molar amount of residual NCO in the reaction system), and finally, a room temperature reversible solid-solid phase change polyurethane was obtained, which has a microphase separation structure at room temperature and a soft phase melting point of 37°C.

[0126] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0127] S5. Preparation of polyurethane spinning solution. 100g of the room temperature reversible solid-solid phase change polyurethane obtained in step S4 and 20g of the highly dispersed hydrophobic nano-zirconia obtained in step S2 were dissolved in 900g of dimethylacetamide to prepare polyurethane spinning solution.

[0128] S6. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a flat spinneret, and the solvent evaporates in hot air to form a filament bundle. After the filament bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a flat cross-section, a fineness of 50D, and a strength of 1.6cN / dtex.

[0129] (4) Preparation of adaptive radiation-cooled textiles

[0130] The intelligent temperature-regulating radiant cooling fiber obtained in step S6 is woven to produce a product with a basis weight of 100 g / m. 2 The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 93%, a mid-infrared emissivity of 76%, and a temperature difference of 2.3℃ with the environment. At 40℃, the fabric has a solar reflectance of 93%, a mid-infrared emissivity of 94%, and a temperature difference of 5.3℃ with the environment.

[0131] Example 7

[0132] A smart temperature-regulating radiative cooling fiber and its preparation method, the preparation process includes the following steps:

[0133] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0134] S1. Activation of hydroxyl groups on the surface of nano-calcium fluoride. Weigh 50g of nano-calcium fluoride and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine at 400℃ for 6 hours. After natural cooling, wash, centrifuge, and dry to obtain nano-calcium fluoride with activated surface hydroxyl groups.

[0135] S2. Hydrophobic modification of nano-calcium fluoride. 50g of hydroxyl-activated nano-calcium fluoride obtained in step S1, 0.8g of p-toluenesulfonic acid, and 300g of dodecanoic acid were uniformly mixed and reacted at 80℃ for 7h. Afterwards, centrifugation, washing, and drying were performed to obtain highly dispersed hydrophobic nano-calcium fluoride with a particle size of 250–480nm and a water contact angle of 118°.

[0136] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0137] S3. Preparation of polyurethane prepolymer. 90g of dehydrated polytetrahydrofuran ether diol with a number average molecular weight of 2000g / mol was uniformly mixed with 10g of dehydrated polycaprolactone diol with a number average molecular weight of 2000g / mol. Then, 26g of diphenylmethane diisocyanate was added and reacted at 80℃ for 6 hours until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeded 96%, thus obtaining polyurethane prepolymer.

[0138] S4. Chain extension reaction of polyurethane. The prepolymer obtained in step S3 was cooled to 50°C, and 1,4-butanediol was added to the reactants to carry out a chain extension reaction (the molar amount of 1,4-butanediol added was 95% of the molar amount of residual NCO in the reaction system). Then, n-butanol was added to terminate the reaction (the molar amount of n-butanol added was 5% of the molar amount of residual NCO in the reaction system), and finally, a room temperature reversible solid-solid phase change polyurethane was obtained, which has a microphase separation structure at room temperature and a soft phase melting point of 33°C.

[0139] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0140] S5. Preparation of polyurethane spinning solution. 100g of the room temperature reversible solid-solid phase change polyurethane obtained in step S4 and 20g of the highly dispersed hydrophobic nano-calcium fluoride obtained in step S2 were dissolved in 900g of dimethylacetamide to obtain the polyurethane spinning solution.

[0141] S6. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a cross-shaped spinneret, and the solvent evaporates in hot air to form a fiber bundle. After the fiber bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a cross-shaped cross-section, a fineness of 50D, and a strength of 1.7cN / dtex.

[0142] (4) Preparation of adaptive radiation-cooled textiles

[0143] The intelligent temperature-regulating radiant cooling fiber obtained in step S6 is woven to produce a product with a basis weight of 100 g / m. 2 The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 94%, a mid-infrared emissivity of 76%, and a temperature difference of 2.3℃ with the environment. At 40℃, the fabric has a solar reflectance of 94%, a mid-infrared emissivity of 96%, and a temperature difference of 5.3℃ with the environment.

[0144] Example 8

[0145] A smart temperature-regulating radiative cooling fiber and its preparation method, the preparation process includes the following steps:

[0146] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0147] S1. Activation of hydroxyl groups on the surface of nano-boron nitride. Weigh 50g of nano-boron nitride and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine it at 500℃ for 4 hours. After natural cooling, wash, centrifuge, and dry to obtain nano-boron nitride with activated surface hydroxyl groups.

[0148] S2. Hydrophobic modification of boron nitride nanoparticles. 50g of hydroxyl-activated boron nitride nanoparticles obtained in step S1, 0.8g of p-toluenesulfonic acid, and 300g of dodecanoic acid were uniformly mixed and reacted at 100℃ for 5h. Afterwards, centrifugation, washing, and drying were performed to obtain highly dispersed hydrophobic boron nitride nanoparticles with a particle size of 250–480nm and a water contact angle of 117°.

[0149] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0150] S3. Preparation of polyurethane prepolymer. 90g of dehydrated polytrimethylene ether glycol with a number average molecular weight of 2000g / mol was uniformly mixed with 10g of dehydrated polycaprolactone glycol with a number average molecular weight of 2000g / mol. Then, 26g of diphenylmethane diisocyanate was added and reacted at 80℃ for 6 hours until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeded 96%, thus obtaining polyurethane prepolymer.

[0151] S4. Chain extension reaction of polyurethane. The prepolymer obtained in step S3 was cooled to 50°C, and 1,4-butanediol was added to the reactants to carry out a chain extension reaction (the molar amount of 1,4-butanediol added was 95% of the molar amount of residual NCO in the reaction system). Then, n-butanol was added to terminate the reaction (the molar amount of n-butanol added was 5% of the molar amount of residual NCO in the reaction system), and finally, a room temperature reversible solid-solid phase change polyurethane was obtained, which has a microphase separation structure at room temperature and a soft phase melting point of 32°C.

[0152] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0153] S5. Preparation of polyurethane spinning solution. 100g of the room temperature reversible solid-solid phase change polyurethane obtained in step S4 and 25g of the highly dispersed hydrophobic nano-boron nitride obtained in step S2 were dissolved in 900g of dimethylacetamide to prepare a polyurethane spinning solution.

[0154] S6. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a trilobal spinneret, and the solvent evaporates in hot air to form a filament bundle. After the filament bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a trilobal cross-section, a fineness of 50D, and a strength of 1.5cN / dtex.

[0155] (4) Preparation of adaptive radiation-cooled textiles

[0156] The intelligent temperature-regulating radiant cooling fiber obtained in step S6 is woven to produce a product with a basis weight of 100 g / m. 2 The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 95%, a mid-infrared emissivity of 74%, and a temperature difference of 2.4℃ with the environment. At 40℃, the fabric has a solar reflectance of 95%, a mid-infrared emissivity of 94%, and a temperature difference of 5.4℃ with the environment.

[0157] Example 9

[0158] A smart temperature-regulating radiative cooling fiber and its preparation method, the preparation process includes the following steps:

[0159] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0160] S1. Activation of hydroxyl groups on the surface of nano-zirconia. Weigh 50g of nano-zirconia and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine at 500℃ for 4 hours. After natural cooling, wash, centrifuge, and dry to obtain nano-zirconia with activated hydroxyl groups on the surface.

[0161] S2. Hydrophobic modification of nano-zirconia. 50g of hydroxyl-activated nano-zirconia obtained in step S1, 0.5g of benzenesulfonic acid, and 350g of tridecanoic acid were uniformly mixed and reacted at 100℃ for 5h. Afterwards, centrifugation, washing, and drying were performed to obtain highly dispersed hydrophobic nano-zirconia with a particle size of 240–500nm and a water contact angle of 118°.

[0162] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0163] S3. Preparation of polyurethane prepolymer. 85g of dehydrated polytrimethylene ether glycol with a number average molecular weight of 2000g / mol was uniformly mixed with 15g of dehydrated polycaprolactone glycol with a number average molecular weight of 2000g / mol. Then, 26g of diphenylmethane diisocyanate was added and reacted at 80℃ for 6 hours until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeded 96%, thus obtaining polyurethane prepolymer.

[0164] S4. Chain extension reaction of polyurethane. The prepolymer obtained in step S3 was cooled to 50°C, and 1,4-butanediol was added to the reactants to carry out a chain extension reaction (the molar amount of 1,4-butanediol added was 95% of the molar amount of residual NCO in the reaction system). Then, n-butanol was added to terminate the reaction (the molar amount of n-butanol added was 5% of the molar amount of residual NCO in the reaction system), and finally, a room temperature reversible solid-solid phase change polyurethane was obtained, which has a microphase separation structure at room temperature and a soft phase melting point of 34°C.

[0165] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0166] S5. Preparation of polyurethane spinning solution. 100g of the room temperature reversible solid-solid phase change polyurethane obtained in step S4 and 25g of the highly dispersed hydrophobic nano-zirconia obtained in step S2 were dissolved in 900g of dimethylacetamide to prepare polyurethane spinning solution.

[0167] S6. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a flat spinneret, and the solvent evaporates in hot air to form a filament bundle. After the filament bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a flat cross-section, a fineness of 50D, and a strength of 1.4cN / dtex.

[0168] (4) Preparation of adaptive radiation-cooled textiles

[0169] The intelligent temperature-regulating radiant cooling fiber obtained in step S6 is woven to produce a product with a basis weight of 100 g / m. 2 The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 94%, a mid-infrared emissivity of 76%, and a temperature difference of 2.6℃ with the environment. At 40℃, the fabric has a solar reflectance of 94%, a mid-infrared emissivity of 95%, and a temperature difference of 5.4℃ with the environment.

[0170] Example 10

[0171] A smart temperature-regulating radiative cooling fiber and its preparation method, the preparation process includes the following steps:

[0172] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0173] S1. Activation of hydroxyl groups on the surface of nano-alumina. Weigh 50g of nano-alumina and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine at 400℃ for 6 hours. After natural cooling, wash, centrifuge, and dry to obtain nano-alumina with activated hydroxyl groups on the surface.

[0174] S2. Hydrophobic modification of nano-alumina. 50g of hydroxyl-activated nano-alumina obtained in step S1, 0.5g of benzenesulfonic acid, and 400g of tridecanoic acid were uniformly mixed and reacted at 100℃ for 5h. Afterwards, centrifugation, washing, and drying were performed to obtain highly dispersed hydrophobic nano-alumina with a particle size of 300–500nm and a water contact angle of 117°.

[0175] (2) Preparation of room temperature reversible solid-solid phase change polyurethane

[0176] S3. Preparation of polyurethane prepolymer. 90g of dehydrated polytrimethylene ether glycol with a number average molecular weight of 2000g / mol was uniformly mixed with 10g of dehydrated polycaprolactone glycol with a number average molecular weight of 2000g / mol. Then, 26g of diphenylmethane diisocyanate was added and reacted at 80℃ for 6 hours until the conversion rate of isocyanate bonds (NCO) in diphenylmethane diisocyanate exceeded 96%, thus obtaining polyurethane prepolymer.

[0177] S4. Chain extension reaction of polyurethane. The prepolymer obtained in step S3 was cooled to 50°C, and 1,4-butanediol was added to the reactants to carry out a chain extension reaction (the molar amount of 1,4-butanediol added was 95% of the molar amount of residual NCO in the reaction system). Then, n-butanol was added to terminate the reaction (the molar amount of n-butanol added was 5% of the molar amount of residual NCO in the reaction system), and finally, a room temperature reversible solid-solid phase change polyurethane was obtained, which has a microphase separation structure at room temperature and a soft phase melting point of 32°C.

[0178] (3) Preparation of intelligent temperature-regulating radiative cooling fibers

[0179] S5. Preparation of polyurethane spinning solution. 100g of the room temperature reversible solid-solid phase change polyurethane obtained in step S4 and 25g of the highly dispersed hydrophobic nano-alumina obtained in step S2 were dissolved in 900g of dimethylacetamide to prepare polyurethane spinning solution.

[0180] S6. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a flat spinneret, and the solvent evaporates in hot air to form a filament bundle. After the filament bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a flat cross-section, a fineness of 50D, and a strength of 1.5cN / dtex.

[0181] (4) Preparation of adaptive radiation-cooled textiles

[0182] The intelligent temperature-regulating radiant cooling fiber obtained in step S6 is woven to produce a product with a basis weight of 100 g / m. 2 The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 94%, a mid-infrared emissivity of 76%, and a temperature difference of 2.6℃ with the environment. At 40℃, the fabric has a solar reflectance of 95%, a mid-infrared emissivity of 95%, and a temperature difference of 5.3℃ with the environment.

[0183] Comparative Example 1: The unmodified nano-zirconia has a particle size of approximately 960 nm and a water contact angle of approximately 21°. When mixed with polyurethane spinning solution, it exhibits significant agglomeration, and severe fiber breakage occurs during spinning, making it impossible to form fibers.

[0184] Comparative Example 2: The highly dispersed nano-zirconia prepared in Example 1 was added to conventional polyurethane in the same proportion to produce fibers and textiles of the same specifications. These fibers and textiles exhibited similar cooling effects in both 30°C and 40°C environments, i.e., 2.8°C lower than the actual product, and did not demonstrate any adaptive effect to ambient temperature. The specific process is as follows:

[0185] (1) Preparation of highly dispersed hydrophobic nanoparticles

[0186] S1. Activation of hydroxyl groups on the surface of nano-zirconia. Weigh 50g of nano-zirconia and 10g of boric acid, mix them thoroughly, and place them in a crucible. Then place the crucible in a high-temperature furnace and calcine at 600℃ for 2 hours. After natural cooling, wash, centrifuge, and dry to obtain nano-zirconia with activated hydroxyl groups on the surface.

[0187] S2. Hydrophobic modification of nano-zirconia. 50g of hydroxyl-activated nano-zirconia obtained in step S1, 1g of dodecylbenzenesulfonic acid, and 200g of decacarbonyl alcohol were uniformly mixed and reacted at 120℃ for 4h. After centrifugation, washing, and drying, highly dispersed hydrophobic nano-zirconia with a particle size of 200-400nm and a water contact angle of 116° was obtained.

[0188] (3) Preparation of radiation-cooled fibers

[0189] S3. Preparation of polyurethane spinning solution. 100g of polyurethane and 15g of highly dispersed hydrophobic nano-zirconia obtained in step S2 were dissolved in 900g of dimethylacetamide to prepare polyurethane spinning solution.

[0190] S4. Dry spinning of polyurethane. The spinning solution obtained in step S5 is spun out through a cross-shaped spinneret, and the solvent evaporates in hot air to form a fiber bundle. After the fiber bundle is processed by drawing, heat setting, etc., intelligent temperature-regulating radiant cooling fiber is obtained. The fiber has a cross-shaped cross-section, a fineness of 50D, and a strength of 2.1cN / dtex.

[0191] Preparation of (4) type radiation-cooled textiles

[0192] The radiation cooling fiber obtained in step S5 is woven to produce a product with a basis weight of 100 g / m². 2 The fabric is a satin weave. At 30℃, the fabric has a solar reflectance of 91%, a mid-infrared emissivity of 86%, and a temperature difference of 2.7℃ with the environment. At 40℃, the fabric has a solar reflectance of 92%, a mid-infrared emissivity of 87%, and a temperature difference of 2.6℃ with the environment.

[0193] The performance of the fabrics in Examples 1-10 above at 30°C or 40°C is summarized in Table 1:

[0194] Table 1

[0195]

[0196] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A smart temperature-regulating radiant cooling fiber, characterized in that, The intelligent temperature-regulating radiant cooling fiber has a fineness of 40-100D and a strength of 1.4-1.9cN / dtex.

2. A method for preparing the intelligent temperature-regulating radiative cooling fiber as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of highly dispersed hydrophobic nanoparticles S1. Activation of hydroxyl groups on the surface of nanoparticles: Weigh nanoparticles and boric acid, mix them thoroughly and evenly, calcine them, and after they cool naturally, wash, centrifuge and dry them to obtain nanoparticles with activated hydroxyl groups on the surface. S2. Hydrophobic modification of nanoparticles: The hydroxyl-activated nanoparticles, catalyst, and modifier obtained in step S1 are mixed evenly, heated to react, and then centrifuged, washed, and dried to obtain highly dispersed hydrophobic nanoparticles. (2) Preparation of room temperature reversible solid-solid phase change polyurethane S3. Preparation of polyurethane prepolymer: Polyether diol and polycaprolactone diol are mixed evenly, then diphenylmethane diisocyanate is added and heated to react until the conversion rate of isocyanate bonds in diphenylmethane diisocyanate exceeds 96%, thus obtaining polyurethane prepolymer. S4. Chain extension reaction of polyurethane: After cooling the prepolymer obtained in step S3 to 50°C, 1,4-butanediol is added to carry out the chain extension reaction. Then, n-butanol is added to terminate the reaction, and finally room temperature reversible solid-solid phase change polyurethane is obtained. (3) Preparation of intelligent temperature-regulating radiative cooling fibers S5. Preparation of polyurethane spinning solution: The room temperature reversible solid-solid phase change polyurethane obtained in step S4 and the highly dispersed hydrophobic nanoparticles obtained in step S2 are dissolved in dimethylacetamide and mixed evenly to obtain polyurethane spinning solution. S6. Dry spinning of polyurethane: The spinning solution obtained in step S5 is sprayed out through a shaped spinneret and the solvent is evaporated in hot air to form a filament bundle. After the filament bundle is drawn and shaped, intelligent temperature-regulating radiation cooling fiber is obtained.

3. The method for preparing intelligent temperature-regulating radiative cooling fiber according to claim 2, characterized in that, The nanoparticles in step S1 are selected from one or more of nano-zirconia, nano-alumina, nano-boron nitride, or nano-calcium fluoride; the mass ratio of the nanoparticles to boric acid is (5-15) parts: 1 part; the calcination temperature is 400-600℃ and the time is 2-5 hours.

4. The method for preparing intelligent temperature-regulating radiative cooling fiber according to claim 2, characterized in that, The catalyst in step S2 is selected from one or more of dodecylbenzenesulfonic acid, benzenesulfonic acid, or p-toluenesulfonic acid; the modifier is a long-chain alkanol with the molecular formula CH3(CH2). n OH, where n = 8 to 12; the mass ratio of the hydroxyl-activated nanoparticles, catalyst, and modifier is 50 parts: (0.5 to 1) parts: (200 to 400) parts; the heating reaction conditions are 80 to 120°C for 3 to 7 hours; the diameter of the obtained highly dispersed hydrophobic nanoparticles is 200 to 500 nm.

5. The method for preparing intelligent temperature-regulating radiative cooling fiber according to claim 2, characterized in that, The polyether glycol in step S3 is one of polytetrahydrofuran ether glycol and polytrimethylene ether glycol; the number average molecular weight of the polyether glycol and polycaprolactone glycol is 1000-2000 g / mol; the polyether glycol and polycaprolactone glycol need to be dehydrated before use, and the dehydration treatment step is: drying and dehydration in a vacuum oven; the mass ratio of the polyether glycol, polycaprolactone glycol and diphenylmethane diisocyanate is (80-90) parts: (10-20) parts: 26 parts; the heating reaction conditions are 80-85℃, 4-6 h.

6. The method for preparing intelligent temperature-regulating radiative cooling fiber according to claim 2, characterized in that, The room-temperature reversible solid-solid phase change polyurethane described in step S4 has a soft-hard phase separation structure at the nanoscale, and the melting point of the soft phase is 32-37℃; the molar amount of 1,4-butanediol added is 94-96% of the molar amount of residual isocyanate bonds in the reaction system; the molar amount of n-butanol added is 4-6% of the molar amount of residual isocyanate bonds in the reaction system.

7. The method for preparing intelligent temperature-regulating radiative cooling fiber according to claim 2, characterized in that, The ratio of the mass parts of the room temperature reversible solid-solid phase change polyurethane, highly dispersed hydrophobic nanoparticles, and dimethylacetamide in step S5 is 100 parts: (15-25) parts: (800-1000) parts.

8. The method for preparing intelligent temperature-regulating radiative cooling fiber according to claim 2, characterized in that, The irregularly shaped spinneret mentioned in step S6 is one of the following: cross-shaped, trilobal, and flat. The dry spinning temperature is 80-110℃, the spinning speed is 500-600m / min, the airflow speed is 0.5-3m / s, and the stretching ratio is 1.5-2 times.

9. An application of the intelligent temperature-regulating radiant cooling fiber as described in claim 1, characterized in that, The intelligent temperature-regulating radiative cooling fiber is used to manufacture adaptive radiative cooling textiles.

10. An adaptive radiative cooling textile, characterized in that, The weight of the textile is 100 g / m². 2 The textile has a solar reflectance of 91%-95% and a mid-infrared emissivity of 73%-77% at 30°C, with a temperature difference of 2.1-2.6°C compared to the ambient temperature. At 40°C, the textile has a solar reflectance of 91%-95% and a mid-infrared emissivity of 93%-96%, with a temperature difference of 4.9-5.6°C compared to the ambient temperature.

Images