High-reflection passive radiation refrigeration paint, coating, preparation method of high-reflection passive radiation refrigeration paint and coating, and coating structure

Abstract

The invention relates to a high-reflection passive radiation refrigeration paint and coating, a preparation method and a coating structure. The paint and the coating comprise deionized water, a functional additive, an inorganic functional reflection filler, a thermal radiation filler and a film-forming emulsion. The preparation method comprises the following steps: S1, weighing deionized water and a part of functional aids in parts by weight, and stirring and dispersing to obtain a first mixed solution; s2, sieving the inorganic functional reflective filler; s3, adding the inorganic functional reflective filler into the first mixed solution in parts by weight, and stirring and dispersing to obtain a second mixed solution; s4, synchronously adding the thermal radiation filler and the film-forming emulsion into the second mixed solution, and stirring and dispersing to obtain a third mixed solution; and S5, adding the rest functional additive into the third mixed solution to obtain the high-reflection passive radiation refrigeration coating. And S6, coating a base material with the high-reflection passive radiation refrigeration coating, and curing to obtain the high-reflection passive radiation refrigeration coating. The coating and the coating are excellent in refrigeration effect. The preparation method is simple in process, easy to operate and long in service life.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving coating technology, specifically relating to a high-reflectivity passive radiation cooling coating and coating preparation method and coating structure. Background Technology

[0002] With accelerating climate change and global warming, humanity faces ever-increasing demands for electricity for cooling. Energy consumption and greenhouse gas emissions from cooling have reached unprecedented levels. Radiative cooling technology, as a novel passive zero-energy cooling technology, has enormous application potential. It achieves a cooling effect below ambient temperature by strongly reflecting or scattering energy in the solar radiation band (0.25–2.5 μm) and utilizing the "atmospheric window" (8–13 μm) to exchange heat with the universe at temperatures close to 3 K.

[0003] To improve the cooling effect of radiation-cooling coatings, it is usually necessary to balance the requirements of broad-spectrum reflection and high emission. However, the functional fillers commonly used in radiation-cooling coatings currently have limitations in spectral matching. At the same time, the fillers used are often limited to a single particle size, and the particle size distribution of the fillers is narrow, resulting in a narrow solar spectrum that can be scattered. This cannot effectively match the broad-spectrum scattering effect of Mie scattering theory, thus limiting the matching with different spectral bands.

[0004] Chinese invention patent CN119529612A relates to the field of polymer materials technology and provides a radiation-cooling coating and its preparation method. The coating comprises the following components by weight: 5-20 parts heat-reflective filler, 5-20 parts heat-radiative filler, 5-20 parts ordinary filler, 0.1-0.5 parts thickener, 10-25 parts aerogel paste, 0.25-0.75 parts hydrophobic agent, 0.2-0.5 parts defoamer, 0.3-1.5 parts dispersant, 0.1-0.3 parts pH adjuster, 0.3-1 parts bactericide, preservative, and mildew inhibitor, 0.1-0.5 parts wetting agent, 25-40 parts acrylic emulsion, 1-2 parts antifreeze, 2-4 parts film-forming aid, and 15-30 parts water. This invention provides a functional coating that combines high reflectivity and radiation-cooling properties, exhibiting significant reflective heat insulation / radiation-cooling effects. It is non-toxic, odorless, pollution-free, and easy to apply, making it an ideal decorative material. However, the thermal radiation filler used in this invention is alumina-modified PVDF-HFP, which is expensive. Furthermore, the extensive use of titanium dioxide as a reflective filler leads to ultraviolet absorption in the ultraviolet band, thus limiting the sunlight reflection effect. In addition, the single particle size and poor spectral compatibility of the functional filler used in this invention result in insufficient sunlight reflection in the near-infrared band.

[0005] Chinese invention patent CN109161241A belongs to the field of radiation cooling technology, and specifically relates to a radiation cooling coating with self-cleaning function and its preparation method. The radiation cooling coating includes a base adhesive and a radiator and hydrophobic nanoparticles covering the base adhesive. The infrared emission peak of the radiator is located in the infrared radiation band of 8–13 μm and covers at least one band within this range. This invention utilizes the high hydrophobicity of the nanoparticles to give the radiation cooling coating a self-cleaning effect, avoiding the phenomenon of reduced cooling effect due to dust accumulation. The radiation cooling coating of this invention has high emissivity in the 8–13 μm band and high transmittance in the visible light band, exhibiting good light-gathering performance, and also reduces the absorption of energy in other bands, ensuring the cooling effect. This invention further employs two radiators with different particle sizes to broaden the radiation range, maximizing the radiation of ground heat to outer space and improving the cooling effect. However, this invention only considers the characteristics of the infrared band and lacks optimization for the solar radiation band. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention proposes a high-reflectivity passive radiation cooling coating that uses special photonic crystal particles with a wide particle size distribution as fillers. This coating balances the requirements of broad-spectrum reflection and high emission, exhibiting high reflectivity in the ultraviolet, visible, and near-infrared light bands—that is, the entire solar emission energy spectrum—and high emissivity in the atmospheric window wavelength range (8μm-13μm).

[0007] The present invention provides a high-reflectivity passive radiation cooling coating and coating comprising deionized water, functional additives, inorganic functional reflective fillers, thermal radiation fillers and film-forming emulsion, wherein the functional additives include dispersants, wetting agents, defoamers, film-forming aids, pH adjusters, antifreeze agents, preservatives, leveling agents and thickeners.

[0008] Further, it includes the following components by weight: 5-30 parts deionized water; 20-60 parts inorganic functional reflective filler; 1-50 parts thermal radiation filler; 0.1-2 parts dispersant; 0.1-0.5 parts wetting agent; 0.1-1 parts defoamer; 0.1-0.5 parts pH adjuster; 0.1-4 parts antifreeze; 0.1-2 parts preservative; 0.1-1 parts leveling agent; 0.1-0.8 parts thickener; 5-80 parts film-forming emulsion; and 1-4 parts film-forming aid.

[0009] Furthermore, both the inorganic functional reflective filler and the thermal radiation filler are composite systems composed of one or more special photonic crystal particles with different particle sizes and wide particle size distributions, selected according to the Mie scattering theory.

[0010] Furthermore, the inorganic functional reflective filler includes a first inorganic functional reflective filler and a second inorganic functional reflective filler. The first inorganic functional reflective filler has a particle size distribution between 100-800 nm and a D50 particle size distribution between 400-500 nm, and is used for efficient scattering of visible light. The second inorganic functional reflective filler has a particle size distribution between 800-2000 nm and a D50 particle size distribution between 1000-1500 nm, and is used for efficient scattering of near-infrared light.

[0011] Furthermore, the inorganic functional reflective filler has a mass ratio of (1:9) to (9:1) in different particle size ranges.

[0012] Furthermore, the mass ratio of the inorganic functional reflective filler to the thermal radiation filler is (5-10):1.

[0013] Furthermore, the inorganic functional reflective filler includes at least one or more of titanium dioxide, aluminum oxide, barium sulfate, calcium carbonate, barium titanate, zinc oxide, zinc sulfide, zirconium oxide, yttrium oxide, and boron nitride.

[0014] Furthermore, the particle size distribution of the thermal radiation filler is between 0.1-20 μm, and the infrared emission peak is located in the infrared radiation band range of 8-13 μm and covers at least one band interval in the 8-13 μm range.

[0015] Furthermore, the thermal radiation filler includes at least one or more of silicon dioxide, silicon nitride, silicon carbide, aluminum nitride, and glass microspheres.

[0016] Furthermore, the film-forming emulsion is one or more of pure acrylic emulsion, styrene-acrylic emulsion, silicone-acrylic emulsion, and fluorocarbon emulsion, wherein the solid content of the mixture is 20-50 wt% and the glass transition temperature Tg is ≥20℃.

[0017] The solid content of 20-50wt% means that 20 to 50 grams of solid matter are present in every 100 grams of mixture, with the remainder being liquid or solvent. This range of solid content values ​​is common in industries such as coatings and adhesives, and is mainly used to control the viscosity and drying performance of products.

[0018] To address the aforementioned problems in the prior art, this invention provides a method for preparing a high-reflectivity passive radiation cooling coating and coating, used in the preparation of the high-reflectivity passive radiation cooling coating and coating described in any of the preferred embodiments above, comprising the following steps: S1: Weigh out deionized water and a portion of functional additives by weight and disperse them by stirring to form the first mixed solution; S2: The inorganic functional reflective filler is sieved through a screen; S3: Add the inorganic functional reflective filler to the first mixed solution according to the weight parts, stir and disperse evenly to form a second mixed solution; S4: Simultaneously add the thermal radiation filler and film-forming emulsion to the second mixed solution and stir to disperse evenly to form a third mixed solution; S5: After adding the remaining functional additives to the third mixed solution, a high-reflectivity passive radiation cooling coating is obtained; S6: The high-reflectivity passive radiation cooling coating is applied to a substrate, and the substrate is cured to obtain a high-reflectivity passive radiation cooling coating.

[0019] Furthermore, in step S6, the dry film thickness of the high-reflectivity passive radiation cooling coating after coating the substrate is 200-400 μm, the solar reflectance of the high-reflectivity passive radiation cooling coating is ≥0.94, and the emissivity in the 8-13 μm atmospheric window band is ≥0.92.

[0020] Furthermore, in step S1, the stirring and dispersing speed is 500 r / min, and the stirring and dispersing time is 3-5 min.

[0021] Furthermore, in step S2, the screen mesh size is 300.

[0022] Furthermore, in step S3, the inorganic functional reflective filler is added in batches and dispersed by stirring. This batch addition and dispersion method specifically includes the following steps: S31: Add 50% by weight, adjust the stirring and dispersing speed from 500 r / min to 700 r / min, and stir and disperse for 5-10 min; S32: Add at 25% by weight, adjust the stirring and dispersing speed from 700 r / min to 900 r / min, and stir and disperse for 5-10 min; S33: Add at 25% by weight, adjust the stirring and dispersing speed from 900 r / min to 1200 r / min, and stir and disperse for 20-30 min.

[0023] Further, in step S4, the thermal radiation filler and film-forming emulsion are simultaneously added to the second mixed solution and dispersed by stirring at 300 r / min for 10 min, followed by the addition of a thickener to adjust the viscosity of the system.

[0024] Furthermore, the coating method in step S6 is any one of roller coating, brush coating, and spray coating, the substrate is the working surface, and the curing is air drying.

[0025] Furthermore, the high-reflectivity passive radiation cooling coating obtained in step S5 is VOC-free.

[0026] To address the aforementioned problems in the prior art, the present invention also provides a high-reflectivity passive radiation cooling coating structure, comprising the high-reflectivity passive radiation cooling coating material and coating described in any of the above-preferred options, wherein the coating structure is a single-layer structure.

[0027] Furthermore, the thickness of the single-layer structure is 200-400 μm.

[0028] Furthermore, the coating has a solar reflectance ≥0.94 and an emissivity ≥0.92 in the 8-13μm atmospheric window band.

[0029] Compared with the prior art, the beneficial effects of the present invention are: Based on Mie scattering theory, the high-reflectivity passive radiation cooling coating of this invention uses special photonic crystal particles with a wide particle size distribution as reflective and emitting fillers, taking into account both broad-spectrum reflection and high emission requirements, and improving the spectral matching limitations of traditional functional fillers. This invention utilizes the response capability of special photonic crystal particles with a wide particle size distribution to different wavelengths to improve the coating's adaptability to different spectral bands, broaden the radiation range of solar and atmospheric window bands, and achieve selective reflection and selective emission of spectral energy.

[0030] The high-reflectivity passive radiation cooling coating of this invention has a reflectance ≥0.94 across the entire solar spectrum (250-2500nm), effectively reflecting sunlight to reduce heat absorption and thus improving the cooling effect of the high-reflectivity passive radiation cooling coating. Furthermore, its emissivity ≥0.92 in the atmospheric window band of 8-13μm allows heat from the ground to be radiated into outer space through this band, facilitating radiative heat exchange with space and further enhancing the cooling effect of the high-reflectivity passive radiation cooling coating.

[0031] The high-reflectivity passive radiation cooling coating of this invention exhibits a reflectivity attenuation of no more than 5% after more than 1000 hours in an outdoor environment. This is suitable for outdoor sunlight intensity of 850-990 W / m². 2 During outdoor performance testing, sunlight shone on the surface of the coated group, and the temperature of the coating surface and the inside of the model were continuously recorded and measured simultaneously by a data acquisition device. At noon, the temperature difference between the outer surface of the coated group and the outer surface of the uncoated group reached more than 20°C, and the internal temperature of the coated group was 4-7°C lower than that of the ambient air. It can be seen that the cooling effect of the high-reflectivity passive radiation cooling coating and coating of the present invention is obvious.

[0032] The high-reflectivity passive radiation cooling coating of this invention is green and environmentally friendly with no VOC release. The fillers used are inexpensive, the preparation process is simple and easy to operate, and the service life is long. It can be prepared without modifying the original coating manufacturing equipment. The construction effect is fast and the coating has good smoothness. It has the potential for large-scale production and can be conveniently and quickly used for construction and modification of existing building envelopes, outdoor power equipment and cold chain transportation equipment. It has great social and economic benefits, a very broad market prospect, and commercial promotion and use value. Attached Figure Description

[0033] Figure 1 The image shows the reflectance spectrum curve of the high-reflectance passive radiation cooling coating obtained in Specific Embodiment 1 of the present invention after it was brushed onto a sample to form a film, and the coating was tested in the solar spectrum band of 250-2500nm. Figure 2 The emission spectrum curve of the high-reflectivity passive radiation cooling coating obtained in Specific Embodiment 1 of the present invention was tested in the atmospheric window band of 8-13µm after the coating was applied to the sample and formed a film. Figure 3 The image shows a comparison of the surface and internal cooling effects of the high-reflectivity passive radiation cooling coating prepared in Specific Embodiment 1 of the present invention with those of the untreated group. Detailed Implementation

[0034] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The preferred embodiments described are only for illustration and explanation of the present invention and are not intended to limit the present invention.

[0035] To address the aforementioned problems in the prior art, the present invention provides a high-reflectivity passive radiation cooling coating and coating comprising deionized water, functional additives, inorganic functional reflective fillers, thermal radiation fillers, and a film-forming emulsion. The functional additives include dispersants, wetting agents, defoamers, film-forming aids, pH adjusters, antifreeze agents, preservatives, leveling agents, and thickeners.

[0036] Optionally, it includes the following components by weight: 5-30 parts deionized water; 20-60 parts inorganic functional reflective filler; 1-50 parts thermal radiation filler; 0.1-2 parts dispersant; 0.1-0.5 parts wetting agent; 0.1-1 parts defoamer; 0.1-0.5 parts pH adjuster; 0.1-4 parts antifreeze; 0.1-2 parts preservative; 0.1-1 parts leveling agent; 0.1-0.8 parts thickener; 5-80 parts film-forming emulsion; and 1-4 parts film-forming aid.

[0037] Optionally, both the inorganic functional reflective filler and the thermal radiation filler are composite systems composed of one or more special photonic crystal particles with different particle sizes and wide particle size distributions, selected according to the Mie scattering theory.

[0038] Optionally, the inorganic functional reflective filler includes a first inorganic functional reflective filler and a second inorganic functional reflective filler. The first inorganic functional reflective filler has a particle size distribution between 100-800 nm and a D50 particle size distribution between 400-500 nm, and is used for efficient scattering of visible light. The second inorganic functional reflective filler has a particle size distribution between 800-2000 nm and a D50 particle size distribution between 1000-1500 nm, and is used for efficient scattering of near-infrared light.

[0039] Optionally, the inorganic functional reflective filler has a mass ratio of (1:9) to (9:1) in different particle size ranges.

[0040] Optionally, the mass ratio of the inorganic functional reflective filler to the thermal radiation filler is (5-10):1.

[0041] Optionally, the inorganic functional reflective filler includes at least one or more of titanium dioxide, aluminum oxide, barium sulfate, calcium carbonate, barium titanate, zinc oxide, zinc sulfide, zirconium oxide, yttrium oxide, and boron nitride.

[0042] Optionally, the particle size distribution of the thermal radiation filler is between 0.1 and 20 μm, and the infrared emission peak is located in the infrared radiation band range of 8-13 μm and covers at least one band interval in the 8-13 μm range.

[0043] Optionally, the thermal radiation filler includes at least one or more of silicon dioxide, silicon nitride, silicon carbide, aluminum nitride, and glass microspheres.

[0044] Optionally, the film-forming emulsion is one or more of pure acrylic emulsion, styrene-acrylic emulsion, silicone-acrylic emulsion, and fluorocarbon emulsion, wherein the solid content of the mixture is 20-50 wt% and the glass transition temperature Tg is ≥20℃.

[0045] The solid content of 20-50wt% means that 20 to 50 grams of solid matter are present in every 100 grams of mixture, with the remainder being liquid or solvent. This range of solid content values ​​is common in industries such as coatings and adhesives, and is mainly used to control the viscosity and drying performance of products.

[0046] To address the aforementioned problems in the prior art, this invention provides a method for preparing a high-reflectivity passive radiation cooling coating and coating, used in the preparation of the high-reflectivity passive radiation cooling coating and coating described in any of the preferred embodiments above, comprising the following steps: S1: Weigh out deionized water and a portion of functional additives by weight and disperse them by stirring to form the first mixed solution; S2: The inorganic functional reflective filler is sieved through a screen; S3: Add the inorganic functional reflective filler to the first mixed solution according to the weight parts, stir and disperse evenly to form a second mixed solution; S4: Simultaneously add the thermal radiation filler and film-forming emulsion to the second mixed solution and stir to disperse evenly to form a third mixed solution; S5: After adding the remaining functional additives to the third mixed solution, a high-reflectivity passive radiation cooling coating is obtained; S6: The high-reflectivity passive radiation cooling coating is applied to a substrate, and the substrate is cured to obtain a high-reflectivity passive radiation cooling coating.

[0047] Optionally, in step S6, the dry film thickness of the high-reflectivity passive radiation cooling coating after coating the substrate is 200-400 μm, the solar reflectance of the high-reflectivity passive radiation cooling coating is ≥0.94, and the emissivity in the 8-13 μm atmospheric window band is ≥0.92.

[0048] Optionally, in step S1, the stirring and dispersing speed is 500 r / min, and the stirring and dispersing time is 3-5 min.

[0049] Optionally, the mesh size of the sieve in step S2 is 300.

[0050] Optionally, in step S3, the inorganic functional reflective filler is added in batches and dispersed by stirring. The batch addition and dispersion method specifically includes the following steps: S31: Add 50% by weight, adjust the stirring and dispersing speed from 500 r / min to 700 r / min, and stir and disperse for 5-10 min; S32: Add at 25% by weight, adjust the stirring and dispersing speed from 700 r / min to 900 r / min, and stir and disperse for 5-10 min; S33: Add at 25% by weight, adjust the stirring and dispersing speed from 900 r / min to 1200 r / min, and stir and disperse for 20-30 min.

[0051] Optionally, in step S4, the thermal radiation filler and film-forming emulsion are simultaneously added to the second mixed solution, and after stirring and dispersing at a speed of 300 r / min for 10 min, a thickener is added to adjust the viscosity of the system.

[0052] Optionally, the coating method in step S6 can be any one of roller coating, brush coating, and spray coating, the substrate is the construction surface, and the curing is air drying.

[0053] Optionally, the high-reflectivity passive radiation cooling coating obtained in step S5 is VOC-free.

[0054] To address the aforementioned problems in the prior art, the present invention also provides a high-reflectivity passive radiation cooling coating structure, comprising the high-reflectivity passive radiation cooling coating material and coating described in any of the above-preferred options, wherein the coating structure is a single-layer structure.

[0055] Optionally, the thickness of the single-layer structure is 200-400 μm.

[0056] Optionally, the coating has a solar reflectance ≥0.94 and an emissivity ≥0.92 in the 8-13 μm atmospheric window band.

[0057] The following describes specific embodiments based on the preferred embodiments described above: Specific Implementation Example 1: A high-reflectivity passive radiation cooling coating comprises the following components in parts by weight: The first inorganic functional reflective filler is selected from barium sulfate particles with a D50 particle size of 400 nm, the second inorganic functional reflective filler is selected from barium sulfate particles with a D50 particle size of 1200 nm, and the thermal radiation filler is selected from silica with a particle size of 0.5 μm. 65 parts of the first and second inorganic functional reflective fillers and the thermal radiation filler are weighed in a mass ratio of 9:1:1; 15 parts of deionized water; 20 parts of silicone-acrylic emulsion; 1.5 parts of dispersant; 0.2 parts of wetting agent; 0.6 parts of defoamer; 0.1 parts of pH adjuster; 1.5 parts of antifreeze; 2.5 parts of film-forming aid; 0.15 parts of preservative; 0.6 parts of leveling agent; and 0.2 parts of thickener.

[0058] The preparation of high-reflectivity passive radiation cooling coatings and coatings based on the above-mentioned components by weight includes the following steps: S100: Weigh out deionized water, dispersant, wetting agent, defoamer, and pH adjuster by weight and put them into the mixing tank. Stir at 500 r / min for 3-5 min. After stirring and dispersing evenly, the first mixed solution is formed. S200: Inorganic functional reflective filler is sieved through a screen. S300: The inorganic functional reflective filler is added to the first mixed solution in batches. First, 50% by weight is added, and the stirring speed is adjusted to 700 r / min and stirred for 5 min. Second, 25% by weight is added, and the stirring speed is adjusted to 900 r / min and stirred for 5 min. Finally, 25% by weight is added, and the stirring speed is adjusted to 1200 r / min and stirred for 20 min to form a uniformly dispersed filler system, i.e., the second mixed solution. S400: Cool the second mixed solution to 28°C, adjust the stirring speed to 300r / min, slowly add silicone-acrylic emulsion and thermal radiation filler at the cooling temperature, stir and disperse for 10min to form an emulsion-filler composite dispersion system, i.e., the third mixed solution. S500: Add antifreeze, film-forming aid, preservative and leveling agent to the emulsion-filler composite dispersion system according to the above weight parts, adjust the stirring speed to 400 r / min, stir and disperse for 10 min, then add thickener to adjust the viscosity of the system, and continue stirring for 15 min to obtain a high-reflectivity passive radiation cooling coating. S600: The high-reflectivity passive radiation cooling coating obtained in step S500 is brushed onto the sample. The dry film thickness after coating is 300μm. The tested coating has a solar reflectance of 0.94 and an atmospheric window emissivity of 0.953.

[0059] Figure 1 After the high-reflectivity passive radiation cooling coating obtained in this specific embodiment was brushed onto the sample to form a film, the reflectance spectrum curve of the coating in the solar spectrum band of 250nm~2500nm was tested. Based on the reflectance spectrum curve, the solar reflectance of the coating was calculated to be 0.94.

[0060] Figure 2 After the high-reflectivity passive radiation cooling coating obtained in this specific embodiment was brushed onto the sample to form a film, the emission spectrum curve of the coating in the 8-13μm atmospheric window band was tested. Based on the emission spectrum curve, the atmospheric window emissivity of the coating was calculated to be 0.953.

[0061] Figure 3 The left figure shows the surface temperature changes over time for the model coated with the high-reflectivity passive radiation cooling coating of this specific embodiment and the surface temperature of the blank uncoated group. As can be seen from the figure, the surface temperature of the high-reflectivity passive radiation cooling coating model of this specific embodiment remained between 10-28°C over 48 hours, while the surface temperature of the blank uncoated group remained between 10-55°C over 48 hours. This experimental data demonstrates that the high-reflectivity passive radiation cooling coating of this invention has excellent cooling effect.

[0062] Figure 3 The right figure shows the changes in internal temperature and ambient temperature over time for the model coated with the high-reflectivity passive radiation cooling coating of this specific embodiment, the blank uncoated group, and the model model coated with the coating. The figure shows that the internal temperature of the high-reflectivity passive radiation cooling coating model remained between 12-28°C over 48 hours, while the internal temperature of the blank uncoated group remained between 12-43°C over 48 hours, and the ambient temperature remained between 15-33°C over 48 hours. This experimental data demonstrates that the high-reflectivity passive radiation cooling coating of this invention has excellent cooling performance. Specific Implementation Example 2: A high-reflectivity passive radiation cooling coating comprises the following components in parts by weight: The first inorganic functional reflective filler is selected from titanium dioxide particles with a D50 particle size of 250 nm; the second inorganic functional reflective filler is selected from barium sulfate particles with a D50 particle size of 1000 nm; the thermal radiation filler is selected from hollow glass microspheres with a D50 particle size of 15 μm; 55 parts of the first and second inorganic functional reflective fillers and the thermal radiation filler are weighed in a mass ratio of 1:9:2; 15 parts of deionized water; 25 parts of silicone-acrylic emulsion; 1 part of dispersant; 0.2 parts of wetting agent; 0.6 parts of defoamer; 0.1 parts of pH adjuster; 1.5 parts of antifreeze; 2 parts of film-forming aid; 0.15 parts of preservative; 0.4 parts of leveling agent; and 0.05 parts of thickener.

[0064] The preparation method of the high-reflectivity passive radiation cooling coating and the coating material according to the above-mentioned components in parts by weight is the same as that in Specific Embodiment 1. The dry film thickness of the prepared coating is 350 μm. The tested coating has a solar reflectance of 0.946 and an atmospheric window emissivity of 0.941. Specific Implementation Example 3: The weight composition and preparation method of the high-reflectivity passive radiation cooling coating and coating in this specific embodiment are the same as those in specific embodiment 1. The difference is that the first inorganic functional reflective filler in the inorganic functional reflective filler is selected from zinc oxide particles with a D50 particle size of 500 nm, and the second inorganic functional reflective filler is selected from zinc oxide particles with a D50 particle size of 1000 nm.

[0066] The dry film thickness of the coating obtained in this specific embodiment is 320 μm, and the measured solar reflectance of the coating is 0.952 and the atmospheric window emissivity is 0.946.

[0067] Comparative Example 1: The high-reflectivity passive radiation cooling coating and coating of this comparative embodiment have the same weight composition and preparation method as those of the specific embodiment 1, except that the inorganic functional reflective filler is titanium dioxide particles with a D50 particle size of 250nm.

[0068] The dry film thickness of the coating prepared in this comparative example is 280 μm, and the measured solar reflectance is 0.856 and the atmospheric window emissivity is 0.916.

[0069] Comparative Example 2: The high-reflectivity passive radiation cooling coating and coating of this comparative embodiment have the same weight composition and preparation method as those of the specific embodiment 1, except that the inorganic functional reflective filler is selected as barium sulfate particles with a D50 particle size of 1μm.

[0070] The dry film thickness of the coating prepared in this comparative example is 260 μm, and the measured solar reflectance is 0.922 and the atmospheric window emissivity is 0.938.

[0071] The above-described technical solutions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-reflectivity passive radiation cooling coating and coating layer, characterized in that, It includes deionized water, functional additives, inorganic functional reflective fillers, thermal radiation fillers, and film-forming emulsions. The functional additives include dispersants, wetting agents, defoamers, film-forming aids, pH adjusters, antifreeze agents, preservatives, leveling agents, and thickeners.

2. The high-reflectivity passive radiation cooling coating and coating according to claim 1, characterized in that, It includes the following components by weight: 5-30 parts deionized water; 20-60 parts inorganic functional reflective filler; 1-50 parts thermal radiation filler; 0.1-2 parts dispersant; 0.1-0.5 parts wetting agent; 0.1-1 parts defoamer; 0.1-0.5 parts pH adjuster; 0.1-4 parts antifreeze; 0.1-2 parts preservative; 0.1-1 parts leveling agent; 0.1-0.8 parts thickener; 5-80 parts film-forming emulsion; and 1-4 parts film-forming aid.

3. The high-reflectivity passive radiation cooling coating and coating according to claim 1, characterized in that, Both the inorganic functional reflective filler and the thermal radiation filler are composite systems composed of one or more special photonic crystal particles with different particle sizes and wide particle size distributions, selected according to the Mie scattering theory.

4. The high-reflectivity passive radiation cooling coating and coating according to claim 3, characterized in that, The inorganic functional reflective filler includes a first inorganic functional reflective filler and a second inorganic functional reflective filler. The first inorganic functional reflective filler has a particle size distribution between 100-800 nm and a D50 particle size distribution between 400-500 nm, and is used for efficient scattering of visible light. The second inorganic functional reflective filler has a particle size distribution between 800-2000 nm and a D50 particle size distribution between 1000-1500 nm, and is used for efficient scattering of near-infrared light.

5. The high-reflectivity passive radiation cooling coating and coating according to claim 3, characterized in that, The inorganic functional reflective filler has a mass ratio of (1:9) to (9:1) in different particle size ranges.

6. The high-reflectivity passive radiation cooling coating according to claim 3, characterized in that, The mass ratio of the inorganic functional reflective filler to the thermal radiation filler is (5-10):

1.

7. The high-reflectivity passive radiation cooling coating and coating according to claim 3, characterized in that, The inorganic functional reflective filler includes at least one or more of titanium dioxide, aluminum oxide, barium sulfate, calcium carbonate, barium titanate, zinc oxide, zinc sulfide, zirconium oxide, yttrium oxide, and boron nitride.

8. The high-reflectivity passive radiation cooling coating and coating according to claim 3, characterized in that, The particle size distribution of the thermal radiation filler is between 0.1 and 20 μm, and the infrared emission peak is located in the infrared radiation band range of 8-13 μm and covers at least one band interval in the 8-13 μm range.

9. The high-reflectivity passive radiation cooling coating and coating according to claim 3, characterized in that, The thermal radiation filler includes at least one or more of silicon dioxide, silicon nitride, silicon carbide, aluminum nitride, and glass microspheres.

10. The high-reflectivity passive radiation cooling coating and coating according to claim 1, characterized in that, The film-forming emulsion is one or more of pure acrylic emulsion, styrene-acrylic emulsion, silicone-acrylic emulsion, and fluorocarbon emulsion, wherein the solid content of the mixture is 20-50 wt% and the glass transition temperature Tg is ≥20℃.

11. A method for preparing a high-reflectivity passive radiation cooling coating and a coating layer, characterized in that, The preparation of the high-reflectivity passive radiation cooling coating and coating according to any one of claims 1-10 includes the following steps: S1: Weigh out deionized water and a portion of functional additives by weight and disperse them by stirring to form the first mixed solution; S2: The inorganic functional reflective filler is sieved through a screen; S3: Add the inorganic functional reflective filler to the first mixed solution according to the weight parts, stir and disperse evenly to form a second mixed solution; S4: Simultaneously add the thermal radiation filler and film-forming emulsion to the second mixed solution and stir to disperse evenly to form a third mixed solution; S5: After adding the remaining functional additives to the third mixed solution, a high-reflectivity passive radiation cooling coating is obtained; S6: The high-reflectivity passive radiation cooling coating is applied to a substrate, and the substrate is cured to obtain a high-reflectivity passive radiation cooling coating.

12. The method for preparing the high-reflectivity passive radiation cooling coating and coating according to claim 11, characterized in that, The high-reflectivity passive radiation cooling coating in step S6 has a dry film thickness of 200-400 μm after coating on the substrate. The coating has a solar reflectance ≥0.94 and an emissivity ≥0.92 in the 8-13 μm atmospheric window band.

13. The method for preparing the high-reflectivity passive radiation cooling coating and coating according to claim 11, characterized in that, In step S1, the stirring and dispersing speed is 500 r / min, and the stirring and dispersing time is 3-5 min.

14. The method for preparing the high-reflectivity passive radiation cooling coating and coating according to claim 11, characterized in that, In step S2, the screen mesh size is 300.

15. The method for preparing the high-reflectivity passive radiation cooling coating and coating according to claim 11, characterized in that, In step S3, the inorganic functional reflective filler is added in batches and dispersed by stirring. The batch addition and dispersion method specifically includes the following steps: S31: Add 50% by weight, adjust the stirring and dispersing speed from 500 r / min to 700 r / min, and stir and disperse for 5-10 min; S32: Add at 25% by weight, adjust the stirring and dispersing speed from 700 r / min to 900 r / min, and stir and disperse for 5-10 min; S33: Add at 25% by weight, adjust the stirring and dispersing speed from 900 r / min to 1200 r / min, and stir and disperse for 20-30 min.

16. The method for preparing the high-reflectivity passive radiation cooling coating and coating according to claim 11, characterized in that, In step S4, the thermal radiation filler and film-forming emulsion are simultaneously added to the second mixed solution and dispersed by stirring at 300 r / min for 10 min. Then, a thickener is added to adjust the viscosity of the system.

17. The method for preparing the high-reflectivity passive radiation cooling coating and coating according to claim 11, characterized in that, The coating method in step S6 is any one of roller coating, brush coating, and spray coating, the substrate is the construction surface, and the curing is air drying.

18. The method for preparing the high-reflectivity passive radiation cooling coating and coating according to claim 11, characterized in that, The high-reflectivity passive radiation cooling coating obtained in step S5 is VOC-free.

19. A high-reflectivity passive radiation cooling coating structure, characterized in that, The coating includes the high-reflectivity passive radiation cooling coating and coating according to any one of claims 1-10, wherein the coating structure is a single-layer structure.

20. The high-reflectivity passive radiation cooling coating structure according to claim 19, characterized in that, The thickness of the single-layer structure is 200-400 μm.

21. The high-reflectivity passive radiation cooling coating structure according to claim 19, characterized in that, The coating has a solar reflectance ≥0.94 and an emissivity ≥0.92 in the 8-13μm atmospheric window band.

Images