A sun-protective and cooling material with radiative cooling and phase change cold storage effects, its preparation method and application

Abstract

This invention belongs to the field of new energy and energy-saving materials technology, specifically relating to a sun-protective and cooling material with radiative cooling and phase change cold storage effects, its preparation method, and its application. The material comprises, in sequence, a heat dissipation layer, a breathable layer I, a cold storage layer, and a breathable layer II. The heat dissipation layer has a reflectivity of not less than 90% in the solar spectrum and an infrared emissivity of not less than 90% in the atmospheric window wavelength range. The cold storage layer adjusts the temperature through a phase change cold storage effect. Breathable layers I and II have good water vapor transport rates. The advantages of this sun-protective and cooling material are: 1. It can actively cool and has ultraviolet protection; 2. It effectively regulates the temperature of the covered object, preventing a rapid temperature rise; 3. It is energy-saving, low-cost, and has a wide range of applications, including thermal management in daily chemicals, clothing, and automobiles; 4. It has excellent hydrophobicity and is resistant to dirt. Therefore, it has broad market and industrial application prospects.

Description

Technical Field

[0001] This invention belongs to the field of new energy and energy-saving materials technology, specifically relating to a sun-protective and cooling material with radiation cooling and phase change cold storage effects, its preparation method and application. Background Technology

[0002] Recently, due to climate change, extreme heat events have become more frequent and intense, making cooling our living environment an urgent challenge. In hot environments, building temperatures rise sharply, requiring air conditioning and other cooling equipment to maintain comfortable indoor conditions. However, these cooling systems require energy, which generates heat and releases greenhouse gases, exacerbating global warming and further intensifying the need for cooling. Furthermore, cars parked outdoors are exposed to intense sunlight, causing interior temperatures to rise dramatically in a short time, sometimes reaching around 60°C. This not only causes significant inconvenience and poses a serious threat to personal safety but also damages vehicles, shortening their lifespan and potentially leading to dangerous situations. Simultaneously, exposure to extreme heat can affect skin health and even overall health, posing a significant environmental challenge, especially for those who need to spend time outdoors. Therefore, outdoor cooling is crucial for sustainable human development.

[0003] Patent CN114685816A discloses a hydrogel phase change cold storage material that uses the latent heat of phase change of water to cool down. However, the latent heat of phase change of water is relatively small, resulting in poor cold storage effect and short duration. Furthermore, the gel hardens after the temperature rises or falls, making it unable to adhere to the surface of the covered object. Patent CN115216276A proposes a jelly-like gel-type high enthalpy phase change cold storage agent, but it is only suitable for temperatures below 0°C. The phase change temperature of the cold storage agent required for outdoor shading and cooling needs to match the outdoor temperature, and the duration of cooling effect of the phase change cold storage needs to be further improved. Summary of the Invention

[0004] To address the shortcomings and deficiencies of existing technologies, the present invention aims to provide a sun-protective and cooling material with radiative cooling and phase change heat storage effects, its preparation method, and its applications. In this invention, radiative cooling is a passive cooling process that selectively reflects most sunlight (wavelength 0.3–2.5 μm) while simultaneously transferring heat to the universe through atmospheric transparency (mainly 8–13 μm) in the form of infrared radiation. This all-weather passive cooling requires no additional energy input, and the radiative cooling material prepared using the radiative cooling principle has advantages such as high near-infrared reflectivity and no ultraviolet damage. Simultaneously, phase change heat storage utilizes the high latent heat of the phase change material for cooling, making it green, environmentally friendly, energy-saving, and reducing refrigeration costs.

[0005] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0006] This invention provides a sun-protective and cooling material with radiative cooling and phase change cold storage effects. The material comprises, in sequence, a heat dissipation layer, a breathable layer I, a cold storage layer, and a breathable layer II. The heat dissipation layer has a reflectivity of not less than 90% in the solar spectrum and an infrared emissivity of not less than 90% in the atmospheric window wavelength range. The cold storage layer adjusts the temperature through a phase change cold storage effect. The water vapor transport rate of breathable layers I and II is not less than 5000 g / m³. 2 / 24h.

[0007] By adopting the aforementioned technical solution, the heat dissipation layer of the present invention can strongly reflect sunlight and emit thermal radiation into outer space, reducing the surface temperature of objects. Its reflectivity is not less than 90% in the solar spectrum range (wavelength 300 to 2500 nm) and its infrared emissivity is not less than 90% in the atmospheric window wavelength range (wavelength 8 to 13 μm), exhibiting excellent radiative cooling effect and achieving superior solar protection across the entire wavelength band. It demonstrates great potential for sustainable energy conservation. The cold storage layer can store a large amount of cold air below the phase change temperature and release it uniformly during the phase change process, ensuring that the temperature of outdoor covered objects does not rise rapidly. The breathable layer can encapsulate the cold storage layer and serve as the base for the heat dissipation layer, while also having a good water vapor transport rate, which can further improve cooling performance.

[0008] Preferably, the heat dissipation layer comprises a heat dissipation agent. More preferably, the heat dissipation agent comprises at least one of a mixture of an organic polymer and inorganic micro / nano particles, or organic polymer microspheres. More preferably, the heat dissipation agent comprises, by weight, 5-20 parts of organic polymer, 10-30 parts of inorganic micro / nano particles, and 0-20 parts of organic polymer microspheres.

[0009] Preferably, the organic polymer is selected from at least one of polydimethylsiloxane, polymethyl methacrylate, polyvinylidene fluoride, polyethylene oxide, and polylactic acid. More preferably, the radiative cooling performance of the organic polymer is determined by the functional groups / bonds of the polymer, which have vibrational absorption in the infrared region that overlap with the atmospheric transmittance window, resulting in strong infrared radiation, such as the CF bond in PVDF, the COC bond in PMMA, and the C-OH bond in PEO.

[0010] Preferably, the inorganic micro / nanoparticles are selected from at least one of titanium dioxide, aluminum oxide, silicon dioxide, barium sulfate, or hollow glass microspheres. More preferably, the particle size of the inorganic micro / nanoparticles is 1 nm-1000 μm. Even more preferably, based on the Mie scattering law, the wide particle size distribution of the inorganic micro / nanoparticles can achieve high reflectivity by scattering sunlight.

[0011] Preferably, the organic polymer microspheres are selected from at least one of polymethyl methacrylate microspheres, polylactic acid microspheres, polystyrene microspheres, and cellulose acetate microspheres. More preferably, the particle size of the organic polymer microspheres is 1 nm-100 μm. Even more preferably, the spherical or hollow spherical structure of the organic polymer microspheres can further improve solar reflectivity, and the organic polymer microspheres can effectively scatter sunlight while possessing high emissivity.

[0012] Preferably, the heat dissipation layer further includes a sunscreen agent. More preferably, the sunscreen agent is selected from at least one of titanium dioxide, zinc oxide, ethylhexyl methoxycinnamate, octyl cyanobenzyl acrylate, methyl anthranilate, hydroxybenzophenone, oracrine, and trimethylcyclohexyl salicylate. Even more preferably, the sunscreen agent can effectively reflect or absorb ultraviolet rays, blocking the harmful effects of ultraviolet rays on the human body and further enhancing the sun protection effect. Even more preferably, the amount of the sunscreen agent is 10-20 parts by weight.

[0013] Preferably, the breathable layer I and breathable layer II are breathable materials with hydrophobic properties. The breathable material includes at least one of cotton cloth, linen cloth, non-woven fabric, cellulose-based fabric, and chemical fiber fabric. The breathable material can be made hydrophobic after being treated with a hydrophobic agent. The hydrophobic agent is preferably at least one of silane coupling agent and fluorosilicone coupling agent. The hydrophobic treatment involves applying a hydrophobic agent to the surface of the breathable material through methods such as coating, brushing, spraying, or impregnation, followed by air drying at room temperature for a certain period, such as 24 hours. More preferably, the silane coupling agent is selected from at least one of trimethylchlorosilane, dimethyldichlorosilane, dimethyldiethoxysilane, methyltrichlorosilane, trimethylethoxysilane, vinyltrimethoxysilane, and γ-aminopropyltriethoxysilane; the fluorosilicone coupling agent is selected from at least one of perfluorooctyltrichlorosilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecylfluorodecyltrimethoxysilane, heptadecylfluorodecyltriethoxysilane, and heptadecylfluorosilane coupling agent. This hydrophobic treatment prevents moisture leakage from the material.

[0014] Preferably, the cold storage layer comprises a polymeric gel matrix and a phase change cold storage material. More preferably, the cold storage layer comprises, by weight, 2 to 5 parts of polymeric gel matrix and 20 to 40 parts of phase change cold storage material.

[0015] Preferably, the polymeric gel matrix is ​​selected from at least one of carbomer, hydroxypropyl methylcellulose, methylcellulose, sodium carboxymethylcellulose, and chitosan, and the phase change cold storage material is a phase change cold storage microcapsule encapsulating a cold storage agent; more preferably, the cold storage agent is a cold storage agent with phase change cold storage function, the phase change temperature of the cold storage agent is all in the range of 25-35℃, and the latent heat of phase change is not less than 100J / g. Through heat exchange with the environment, it can effectively improve the adaptability to the external environmental temperature, which is crucial to the thermal comfort of the human body; even more preferably, the cold storage agent is selected from at least one of paraffin, sodium sulfate decahydrate, decanoic acid, and tetradecyl alcohol, whose phase change temperature matches the outdoor body surface temperature, and the microcapsule shell material is selected from at least one of polyurethane, melamine resin, gelatin, gum arabic, polyolefin, and urea-formaldehyde resin. Even more preferably, the phase change microcapsules are tiny capsules with a diameter of 5-200um, which can encapsulate and protect the cold storage agent inside their core. The phase change microcapsule material can effectively solve the problem of shape and volume changes when solid-liquid phase change materials become liquid.

[0016] Preferably, the thickness of the sun-protective and cooling material of the present invention is 300-2000 μm, the thickness of the heat dissipation layer is 50-400 μm, the thickness of the cold storage layer is 50-400 μm, and the thicknesses of the breathable layers I and II are 100-500 μm respectively.

[0017] Preferably, the porosity of the heat dissipation layer is 10-70%, and the pore size is 0.4-5 μm.

[0018] The present invention also provides a method for preparing any of the above-mentioned sunscreen and cooling materials with radiative cooling and phase change cold storage effects, comprising the following steps:

[0019] (1) Dissolve 5-20 parts by weight of organic polymer in 60-80 parts by weight of organic solvent, then add 10-20 parts by weight of sunscreen agent and mix evenly, then add 10-30 parts by weight of inorganic micro-nano particles and 0-20 parts by weight of organic polymer microspheres and mix evenly to obtain solution A.

[0020] Preferably, the organic solvent is selected from at least one of N-methylpyrrolidone, N,N-dimethylformamide, toluene, tetrahydrofuran, and acetone;

[0021] Preferably, the organic polymer and organic solvent are stirred at 60°C for 1-2 hours until the organic polymer is completely dissolved; the stirring rate is preferably 100-500 r / min.

[0022] Preferably, after adding the sunscreen, stir for 1-2 hours, with a stirring speed preferably of 100-500 r / min, until the mixture is homogeneous;

[0023] Preferably, after adding inorganic micro / nano particles and organic polymer microspheres, the mixture is stirred at room temperature for 2–6 hours, with a preferred stirring rate of 100–500 r / min, until the mixture is homogeneous.

[0024] (2) 2-5 parts by mass of polymer gel matrix, 20-40 parts by mass of phase change cold storage material and 80-100 parts by mass of water are stirred at room temperature to obtain solution B;

[0025] Preferably, the mixture is stirred for 10 to 30 minutes at a stirring rate of 100 to 300 r / min, so that the water and the gel matrix form a gel and the phase change cold storage material microcapsules are uniformly distributed in the gel.

[0026] (3) Apply solution A to one side of the breathable layer I and dry it to obtain a heat dissipation layer with the breathable layer I as the base; then immediately apply solution B to the other side of the breathable layer I and one side of the breathable layer II respectively, stack them and dry them to obtain the sun protection and cooling material with radiation cooling and phase change cold storage effect described in this invention.

[0027] Preferably, solution A is uniformly coated on one side of the breathable layer I using a scraper of different thickness on an automatic coating machine, and then placed in an oven at 60-100°C for 1-2 hours. After drying, it is taken out to obtain a 50-400μm heat dissipation layer with the breathable layer as the base.

[0028] After coating with solution B, place the two coated surfaces face to face together and dry them in an oven at 40-70℃ for 1-2 hours.

[0029] This invention also provides an application of any of the above-mentioned sunscreen and cooling materials with radiative cooling and phase change cold storage effects in the field of thermal management. The thermal management field includes thermal management applications involving cooling needs, such as daily chemicals, clothing, and automobiles.

[0030] Compared with existing technologies, the beneficial effects of this invention are as follows: The material of this invention comprises, in sequence, a heat dissipation layer, a breathable layer I, a cold storage layer, and a breathable layer II. The heat dissipation layer is mainly composed of organic polymers, inorganic micro / nano particles, and sunscreen agents, and may further include organic polymer microspheres. It possesses radiative cooling properties, with a reflectivity of not less than 90% in the solar spectrum and an infrared emissivity of not less than 90% in the atmospheric window wavelength range. It can actively reduce surface temperature, reflect sunlight, and dissipate additional heat in the form of infrared radiation. The breathable layer is composed of a breathable and moisture-permeable fabric, which can encapsulate the cold storage layer and serve as the base for the heat dissipation layer. It has a good water vapor transport rate, further improving cooling performance. Simultaneously, it is treated with a hydrophobic agent, giving it hydrophobic properties and preventing moisture leakage. The cold storage layer is mainly composed of a polymer gel matrix and a phase change cold storage material. The phase change temperature of the phase change cold storage material matches the outdoor temperature. Through heat exchange with the environment, it can effectively improve the adaptability to external environmental temperatures and slow down temperature changes in the covered object. This invention also provides a simple, low-cost, energy-saving, and efficient method for preparing sun-protective and cooling materials. The advantages of the sun-protective and cooling material of this invention are: 1. It can actively cool and has ultraviolet protection; 2. It effectively regulates the temperature of the covered object, preventing a rapid increase in temperature; 3. It is energy-saving, low-cost, and has a wide range of applications, including thermal management in daily chemicals, clothing, automobiles, and other fields; 4. It has excellent hydrophobicity and is resistant to dirt. Therefore, it has broad market and industrial application prospects. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the sunshade and cooling material described in this invention; in the figure: 1-heat dissipation layer, 2-breathable layer I, 3-cold storage layer, 4-breathable layer II. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings, specific embodiments and data. However, the specific embodiments do not constitute a limitation on the technical solution described in the present invention.

[0033] Example 1

[0034] (1) Dissolve 5 parts by mass (1 part by mass is preferably 0.1 g) of polymethyl methacrylate in 75 parts by mass of N,N-dimethylformamide, then add 20 parts by mass of olliculin and mix and stir for 1 h at a stirring speed of 300 r / min. Then add 10 parts by mass of polystyrene microspheres and 10 parts by mass of silica and stir at room temperature for 6 h at a stirring speed of 300 r / min to obtain solution A.

[0035] (2) 4 parts by mass of methylcellulose, 35 parts by mass of 10 μm decanoic acid phase change microcapsules with polyolefin as shell material and 100 parts by mass of deionized water were stirred at room temperature for 20 min at a stirring rate of 200 r / min to obtain solution B.

[0036] (3) Apply solution A uniformly to one side of 500μm cotton cloth I using a scraper on an automatic coating machine, place it in an oven at 60℃ for 1 hour, and after drying, take it out to obtain a heat dissipation layer with cotton cloth I as the base. The thickness of the heat dissipation layer is 100μm, the porosity is 60%, and the average pore size is 2μm. Immediately apply solution B to the other side of cotton cloth I and one side of 500μm thick cotton cloth II, and stack them together. The coating thickness is 100μm. Place them in an oven at 40℃ for 2 hours, and after drying, take them out to obtain a sun protection and cooling material.

[0037] The sun protection and cooling material obtained in this embodiment has a thickness of approximately 1200 μm, a reflectivity of 90% in the solar spectrum range (wavelength 300 to 2500 nm), an infrared emissivity of 90% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a maximum latent heat of phase change of 224.68 J / g at high temperature, a maximum tensile breaking strength of 150 N / 5 cm, and a maximum elongation at break of 50%.

[0038] Comparative Example 1

[0039] (1) Dissolve 5 parts by mass of polymethyl methacrylate in 75 parts by mass of N,N-dimethylformamide, then add 20 parts by mass of olliculin and mix and stir for 1 hour at a stirring speed of 300 r / min. Then add 10 parts by mass of polystyrene microspheres and 10 parts by mass of silica and stir at room temperature for 6 hours at a stirring speed of 300 r / min to obtain solution A.

[0040] (2) Mix 4 parts by mass of methylcellulose with 100 parts by mass of deionized water at room temperature for 20 min at a stirring rate of 200 r / min to obtain solution B.

[0041] (3) Solution A was uniformly coated on one side of 500μm cotton cloth I using a scraper on an automatic coating machine. It was placed in an oven at 60℃ for 1 hour. After drying, it was taken out to obtain a heat dissipation layer with cotton cloth I as the base. The thickness of the heat dissipation layer was 100μm, the porosity was 60%, and the average pore size was 2μm. Solution B was immediately coated on the other side of cotton cloth I and one side of 500μm thick cotton cloth II, and stacked together. The coating thickness was 100μm. It was placed in an oven at 40℃ for 2 hours. After drying, it was taken out to obtain the sun protection and cooling material comparative example 1.

[0042] The sunscreen and cooling material obtained in this comparative example has a thickness of approximately 1200 μm, a reflectivity of 90% in the solar spectrum (wavelength 300 to 2500 nm), an infrared emissivity of 90% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a maximum latent heat of phase change of 80.21 J / g at high temperatures, a maximum tensile breaking strength of 150 N / 5 cm, and a maximum elongation at break of 50%. Furthermore, the hydrogel hardens due to water loss at high or low temperatures, making it difficult to adhere to the covered object.

[0043] Example 2

[0044] (1) Dissolve 15 parts by mass of polyvinylidene fluoride in 60 parts by mass of N-methylpyrrolidone, stirring at 300 r / min. Then add 20 parts by mass of zinc oxide and 15 parts by mass of barium sulfate and stir at room temperature for 4 h at 500 r / min. After stirring evenly, add the mixture to obtain solution A.

[0045] (2) Two parts by mass of carbomer 940, 20 parts by mass of 50 μm sodium sulfate decahydrate phase change microcapsules with polyurethane as shell material, and 100 parts by mass of deionized water were stirred at room temperature for 30 min at a stirring rate of 100 r / min to obtain solution B.

[0046] (3) Apply solution A uniformly on one side of 300μm nonwoven fabric I using a scraper on an automatic coating machine, place it in an oven at 80℃ for 2 hours, and after drying, take it out to obtain a heat dissipation layer with nonwoven fabric I as the base. The thickness of the heat dissipation layer is 200μm, the porosity is 50%, and the average pore size is 3μm. Immediately apply solution B to the other side of nonwoven fabric I and one side of 300μm thick nonwoven fabric II, and stack them together. The coating thickness is 300μm. Place them in an oven at 60℃ for 1 hour, and after drying, take them out to obtain a sun protection and cooling material.

[0047] The sun protection and cooling material obtained in this embodiment has a thickness of approximately 1100 μm, a reflectivity of 90% in the solar spectrum range (wavelength 300 to 2500 nm), an infrared emissivity of 98% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a maximum latent heat of phase change of 309.31 J / g at high temperature, a maximum tensile breaking strength of 130 N / 5 cm, and a maximum elongation at break of 60%.

[0048] Comparative Example 2

[0049] (1) Dissolve 15 parts by mass of polyvinylidene fluoride in 60 parts by mass of N-methylpyrrolidone, stirring at 300 r / min. Then add 20 parts by mass of zinc oxide and 15 parts by mass of barium sulfate and stir at room temperature for 4 h at 500 r / min. After stirring evenly, add the mixture to obtain solution A.

[0050] (2) Mix 2 parts by mass of Carbomer 940 with 100 parts by mass of deionized water at room temperature for 30 min at a stirring rate of 100 r / min to obtain solution B.

[0051] (3) Solution A was uniformly coated on one side of a 300μm nonwoven fabric I using a scraper on an automatic coating machine. The coating was placed in an oven at 80℃ for 2 hours. After drying, the coating was removed to obtain a heat dissipation layer with nonwoven fabric I as the base. The thickness of the heat dissipation layer was 200μm, the porosity was 50%, and the average pore size was 3μm. Solution B was immediately coated on the other side of nonwoven fabric I and one side of a 300μm thick nonwoven fabric II. The two layers were stacked together and coated with a thickness of 300μm. The layers were placed in an oven at 60℃ for 1 hour. After drying, the coating was removed to obtain the sun protection and cooling material comparative example 2.

[0052] The sunscreen and cooling material obtained in this comparative example has a thickness of approximately 1100 μm, a reflectivity of 90% in the solar spectrum (wavelength 300 to 2500 nm), an infrared emissivity of 98% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a maximum latent heat of phase change of 159.42 J / g at high temperature, a maximum tensile breaking strength of 130 N / 5 cm, and a maximum elongation at break of 60%.

[0053] Example 3

[0054] (1) Dissolve 20 parts by mass of polyethylene oxide in 70 parts by mass of N,N-dimethylformamide, then add 20 parts by mass of ethylhexyl methoxycinnamate and stir for 2 hours at a stirring speed of 400 r / min. Then add 30 parts by mass of hollow glass microspheres and stir at room temperature for 3 hours at a stirring speed of 500 r / min to obtain solution A.

[0055] (2) 5 parts by mass of methylcellulose, 20 parts by mass of 100 μm paraffin phase change microcapsules with melamine resin as shell material and 100 parts by mass of deionized water were stirred at room temperature for 10 min at a stirring rate of 200 r / min to obtain solution B.

[0056] (3) Apply solution A uniformly to one side of 200μm linen I using a scraper on an automatic coating machine, place it in an oven at 70℃ for 1 hour, and after drying, take it out to obtain a heat dissipation layer with linen I as the base. The thickness of the heat dissipation layer is 400μm, the porosity is 65%, and the average pore size is 1μm. Immediately apply solution B to the other side of linen I and one side of 200μm thick linen II, and stack them together. The coating thickness is 100μm. Place them in an oven at 70℃ for 1 hour, and after drying, take them out to obtain a sun protection and cooling material.

[0057] The sun protection and cooling material obtained in this embodiment has a thickness of approximately 900 μm, a reflectivity of 92% in the solar spectrum range (wavelength 300 to 2500 nm), an infrared emissivity of 96% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a maximum latent heat of phase change of 260.68 J / g at high temperature, a maximum tensile breaking strength of 180 N / 5 cm, and a maximum elongation at break of 60%.

[0058] Comparative Example 3

[0059] (1) Dissolve 20 parts by mass of polyethylene oxide in 70 parts by mass of N,N-dimethylformamide, then add 20 parts by mass of ethylhexyl methoxycinnamate and stir for 2 hours at a stirring speed of 400 r / min. Then add 30 parts by mass of hollow glass microspheres and stir at room temperature for 3 hours at a stirring speed of 500 r / min to obtain solution A.

[0060] (2) Mix 5 parts by mass of methylcellulose with 100 parts by mass of deionized water at room temperature for 10 min at a stirring rate of 200 r / min to obtain solution B.

[0061] (3) Solution A was uniformly coated on one side of 200μm linen I using a scraper on an automatic coating machine. After drying, it was placed in an oven at 70℃ for 1 hour and then removed to obtain a heat dissipation layer with linen I as the base. The thickness of the heat dissipation layer was 400μm, the porosity was 65%, and the average pore size was 1μm. Solution B was immediately coated on the other side of linen I and one side of 200μm thick linen II, and then stacked together. The coating thickness was 100μm. After drying, it was placed in an oven at 70℃ for 1 hour and then removed to obtain the sun protection and cooling material comparative example 3.

[0062] The sunscreen and cooling material obtained in this comparative example has a thickness of approximately 900 μm, a reflectivity of 92% in the solar spectrum (wavelength 300 to 2500 nm), an infrared emissivity of 96% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a maximum latent heat of phase change of 109.86 J / g at high temperature, a maximum tensile breaking strength of 180 N / 5 cm, and a maximum elongation at break of 60%.

[0063] Example 4

[0064] (1) Dissolve 10 parts by mass of polydimethylsiloxane in 65 parts by mass of toluene solution, then add 20 parts by mass of titanium dioxide and 25 parts by mass of nano aluminum oxide and stir at room temperature for 5 hours at a stirring speed of 400 r / min to obtain solution A.

[0065] (2) 5 parts by mass of sodium carboxymethyl cellulose, 20 parts by mass of 150 μm paraffin phase change microcapsules with urea-formaldehyde resin as shell material, and 80 parts by mass of deionized water were stirred at room temperature for 15 min at a stirring rate of 300 r / min to obtain solution B.

[0066] (3) Apply solution A uniformly to one side of 400μm cellulose-based fabric I using a scraper on an automatic coating machine, place it in an oven at 75℃ for 1h, and after drying, take it out to obtain a heat dissipation layer with cellulose-based fabric I as the base. The thickness of the heat dissipation layer is 300μm, the porosity is 45%, and the average pore size is 4μm. Immediately apply solution B to the other side of 400μm thick cellulose-based fabric I and one side of cellulose-based fabric II, and stack them together. The coating thickness is 200μm. Place them in an oven at 50℃ for 2h, and after drying, take them out to obtain a sun protection and cooling material.

[0067] The sun protection and cooling material obtained in this embodiment has a thickness of approximately 1300 μm, a reflectivity of 90% in the solar spectrum range (wavelength 300 to 2500 nm), an infrared emissivity of 92% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a maximum latent heat of phase change of 170.72 J / g at high temperature, a maximum tensile breaking strength of 70 N / 5 cm, and a maximum elongation at break of 45%.

[0068] Comparative Example 4

[0069] (1) Dissolve 10 parts by mass of polydimethylsiloxane in 65 parts by mass of toluene solution, then add 20 parts by mass of titanium dioxide and 25 parts by mass of nano aluminum oxide and stir at room temperature for 5 hours at a stirring speed of 400 r / min to obtain solution A.

[0070] (2) Mix 5 parts by mass of sodium carboxymethyl cellulose with 80 parts by mass of deionized water at room temperature for 15 min at a stirring rate of 300 r / min to obtain solution B.

[0071] (3) Solution A was uniformly coated on one side of 400μm cellulose-based fabric I using a 300μm scraper on an automatic coating machine. After drying, it was placed in an oven at 75℃ for 1 hour and then removed to obtain a heat dissipation layer with cellulose-based fabric I as the base. The thickness of the heat dissipation layer was 300μm, the porosity was 45%, and the average pore size was 4μm. Solution B was immediately coated on the other side of cellulose-based fabric I and one side of 400μm thick cellulose-based fabric II, and then stacked together with a coating thickness of 200μm. After drying, it was placed in an oven at 50℃ for 2 hours and then removed to obtain a sun protection and cooling material.

[0072] The sunscreen and cooling material obtained in this comparative example has a thickness of approximately 1300 μm, a reflectivity of 90% in the solar spectrum (wavelength 300 to 2500 nm), an infrared emissivity of 92% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a maximum latent heat of phase change of 68.59 J / g at high temperature, a maximum tensile breaking strength of 70 N / 5 cm, and a maximum elongation at break of 45%.

[0073] Example 5

[0074] (1) Dissolve 20 parts by mass of polylactic acid in 80 parts by mass of tetrahydrofuran solution, then add 20 parts by mass of ethylhexyl methoxycinnamate and stir for 2 hours at a stirring speed of 400 r / min. Then add 10 parts by mass of silica and stir at room temperature for 6 hours at a stirring speed of 200 r / min to obtain solution A.

[0075] (2) 5 parts by mass of chitosan, 30 parts by mass of 100 μm tetradecyl alcohol phase change microcapsules with gelatin as the shell material and 100 parts by mass of deionized water were stirred at room temperature for 30 min at a stirring rate of 300 r / min to obtain solution B.

[0076] (3) Apply solution A uniformly to one side of 100μm synthetic fiber cloth I using a scraper on an automatic coating machine, place it in an oven at 70℃ for 1 hour, and after drying, take it out to obtain a heat dissipation layer with synthetic fiber cloth I as the base. The thickness of the heat dissipation layer is 350μm, the porosity is 56%, and the average pore size is 1.2μm. Immediately apply solution B to the other side of synthetic fiber cloth I and one side of 100μm thick synthetic fiber cloth II, and stack them together. The coating thickness is 70μm. Place them in an oven at 40℃ for 2 hours, and after drying, take them out to obtain a sun protection and cooling material.

[0077] The sun protection and cooling material obtained in this embodiment has a thickness of approximately 620 μm, a reflectivity of 90% in the solar spectrum range (wavelength 300 to 2500 nm), an infrared emissivity of 90% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a maximum latent heat of phase change of 122.63 J / g at high temperature, a maximum tensile breaking strength of 88 N / 5 cm, and a maximum elongation at break of 45%.

[0078] Comparative Example 5

[0079] (1) Dissolve 20 parts by mass of polylactic acid in 80 parts by mass of tetrahydrofuran solution, then add 20 parts by mass of ethylhexyl methoxycinnamate and stir for 2 hours at a stirring speed of 400 r / min. Then add 10 parts by mass of silica and stir at room temperature for 6 hours at a stirring speed of 200 r / min to obtain solution A.

[0080] (2) Mix 5 parts by mass of chitosan with 100 parts by mass of deionized water at room temperature for 30 minutes at a stirring rate of 300 r / min to obtain solution B.

[0081] (3) Apply solution A uniformly on one side of 100μm chemical fiber cloth I using a 350μm scraper on an automatic coating machine, place it in an oven at 70℃ for 1h, and after drying, take it out to obtain a heat dissipation layer with chemical fiber cloth I as the base. The thickness of the heat dissipation layer is 350μm, the porosity is 56%, and the average pore size is 1.2μm. Immediately apply solution B to the other side of chemical fiber cloth I and one side of 100μm thick chemical fiber cloth II, and stack them together. The coating thickness is 70μm. Place them in an oven at 40℃ for 2h, and after drying, take them out to obtain a sun protection and cooling material.

[0082] The sunscreen and cooling material obtained in this comparative example has a thickness of approximately 620 μm, a reflectivity of 90% in the solar spectrum (wavelength 300 to 2500 nm), an infrared emissivity of 90% in the atmospheric window wavelength range (wavelength 8 to 13 μm), a maximum latent heat of phase change of 61.77 J / g at high temperature, a maximum tensile breaking strength of 88 N / 5 cm, and a maximum elongation at break of 45%.

[0083] Test case

[0084] The sunshade and cooling materials prepared in Examples 1-5 and Comparative Examples 1-5 were applied to the arm, and the temperature of the exposed skin and the temperature of the corresponding breathable layer (double layer) used in each example were compared, with an average air temperature of 35°C and an average solar irradiance of 600 W / m². 2 Temperature was tested for 4 hours (10:00-14:00) under the experimental conditions. The temperature of the arm was recorded every hour. The average temperature test results are listed in Table 1.

[0085] Table 1 Temperature comparison of various embodiments and comparative examples

[0086]

[0087]

[0088] As can be seen from Table 1, the temperatures of Examples 1-5 are all lower than the comparative temperature, 3-5°C lower than the temperature of the bare arm, and 1-4°C lower than the temperature of the corresponding double-layer breathable layer. This shows that the sunshade and cooling material of the present invention can effectively and actively reduce the temperature and meet the corresponding thermal management requirements.

[0089] The embodiments described above are some, but not all, of the embodiments of the present invention. The present invention is not limited to the above embodiments, and various changes can be made according to the inventive purpose of the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sun-protective and cooling material with radiative cooling and phase change cold storage effects, characterized in that, The materials described herein include, in sequence, a heat dissipation layer, a breathable layer I, a cold storage layer, and a breathable layer II. The heat dissipation layer has a reflectivity of not less than 90% in the solar spectrum and an infrared emissivity of not less than 90% in the atmospheric window wavelength range. The cold storage layer adjusts the temperature through a phase change cold storage effect. The water vapor transport rate of breathable layers I and II is not less than 5000 g / m³. 2 / 24h; wherein, the heat dissipation layer includes a heat dissipation agent, which comprises, by weight, 5-20 parts of organic polymer, 10-30 parts of inorganic micro / nano particles and 0-20 parts of organic polymer microspheres; the cold storage layer includes a polymeric gel matrix and a phase change cold storage material, wherein the polymeric gel matrix is ​​selected from at least one of carbomer, hydroxypropyl methylcellulose, methylcellulose, sodium carboxymethyl cellulose, and chitosan; the phase change cold storage material is a phase change cold storage microcapsule encapsulating a cold storage agent, wherein the phase change temperature of the cold storage agent is 25-35℃ and the latent heat of phase change is not less than 100J / g.

2. The sun-protective and cooling material with radiative cooling and phase change cold storage effects according to claim 1, characterized in that, The organic polymer is selected from at least one of polydimethylsiloxane, polymethyl methacrylate, polyvinylidene fluoride, polyethylene oxide, and polylactic acid; the inorganic micro / nano particles are selected from at least one of aluminum oxide, silicon dioxide, barium sulfate, or hollow glass microspheres; the organic polymer microspheres are selected from at least one of polymethyl methacrylate microspheres, polylactic acid microspheres, polystyrene microspheres, and cellulose acetate microspheres.

3. The sun-protective and cooling material with radiative cooling and phase change cold storage effects according to claim 1, characterized in that, The heat dissipation layer also includes a sunscreen agent selected from at least one of titanium dioxide, zinc oxide, ethylhexyl methoxycinnamate, octyl cyanobenzyl acrylate, methyl anthranilate, hydroxybenzophenone, octocrylene, and trimethylcyclohexyl salicylate.

4. The sun-protective and cooling material with radiative cooling and phase change cold storage effects according to claim 1, characterized in that, The thickness of the sun-protective and cooling material is 300~2000μm, the thickness of the heat dissipation layer is 50~400μm, the thickness of the cold storage layer is 50~400μm, and the thicknesses of the breathable layers I and II are 100~500μm respectively.

5. A method for preparing a sun-protective and cooling material with radiative cooling and phase change cold storage effects as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Dissolve the organic polymer in an organic solvent, then add the sunscreen agent and mix well, then add the inorganic micro-nano particles and organic polymer microspheres and mix well to obtain solution A; (2) Solution B is obtained by stirring the polymer gel matrix, phase change cold storage material and water at room temperature; (3) Apply solution A to one side of breathable layer I and dry it; apply solution B to the other side of breathable layer I and one side of breathable layer II respectively, stack them and dry them to obtain sun protection and cooling material.

6. The method for preparing a sunscreen and cooling material with radiative cooling and phase change cold storage effects according to claim 5, characterized in that, In step (1), the organic solvent is selected from at least one of N-methylpyrrolidone, N,N-dimethylformamide, toluene, tetrahydrofuran, and acetone.

7. The application of the sun-protective and cooling material with radiative cooling and phase change cold storage effects as described in any one of claims 1-4 in the field of thermal management.

Images