Metal-based water-based radiation refrigeration coating finish paint and preparation method thereof

Abstract

The invention discloses a metal-based water-based radiation refrigeration coating finish paint and a preparation method thereof, the metal-based water-based radiation refrigeration coating finish paint comprises a component A and a component B, and the mass ratio of the component A to the component B is (5-6): 1; the component A is mainly prepared from hydroxyl acrylic emulsion, a dispersing agent, a wetting agent, a defoaming agent, an anti-settling agent, a thickening agent, a flatting agent, a preservative, a pH regulator, deionized water, a high-reflection particle mixture and a full-atmospheric window radiation particle composition; and the component B is a polyisocyanate curing agent. The coating finish paint is suitable for a metal base surface, has excellent environmental protection performance and physical performance, has high reflectivity and high radiance performance, can effectively reflect sunlight and reduce the sunlight absorption capacity of a coating, and can passively cool a system through the heat radiation capacity of high-radiance particles.

Description

Technical Field

[0001] This application relates to the field of radiation cooling technology, and in particular to a water-based radiation cooling coating with high reflectivity and high emissivity, and its preparation method, which is especially suitable for metal substrates. Background Technology

[0002] With global warming, the energy consumption of traditional air conditioning temperature control methods is further increasing. How to replace traditional air conditioning methods and obtain new energy-saving and environmentally friendly space temperature control technologies has become a research hotspot. Radiation cooling coatings can radiate electromagnetic waves into outer space through the "atmospheric window" band (8-13μm) without requiring electrical input. Simultaneously, they can strongly reflect solar irradiance in the 0.3-2.5μm range. Utilizing the high reflectivity of the solar light band and the high emissivity of the atmospheric window, the surface temperature of the radiation cooling material is reduced to below the ambient temperature, making it a highly promising green and energy-saving cooling technology.

[0003] Currently, radiation-cooling coatings on the market still have some problems, especially their application on metal substrates is relatively limited. Traditional radiation-cooling coatings typically use powders such as barium sulfate, barium carbonate, and titanium dioxide to achieve good solar reflectivity and hemispherical emissivity, but their emissivity is low, resulting in poor radiation-cooling effect. In addition, existing water-based metal-based radiation-cooling coatings have poor physical properties, particularly in that they generally cannot simultaneously possess both strength and toughness, and their weather resistance and environmental performance are insufficient. Summary of the Invention

[0004] In view of this, this application provides a metal-based water-based radiation cooling coating topcoat and its preparation method. The coating topcoat is suitable for metal-based substrates, has excellent environmental and physical properties, and has high reflectivity and high emissivity. It can effectively reflect sunlight, reduce the coating's ability to absorb sunlight, and passively cool the system through the thermal radiation capability of high emissivity particles.

[0005] To achieve the above objectives, this application employs the following technical solution: A metal-based waterborne radiation cooling coating topcoat, comprising component A and component B, wherein the mass ratio of component A to component B is 5-6:1; Component A is mainly prepared from the following components in the indicated weight proportions: Hydroxy acrylic emulsion 38-50 parts, 1-2 parts dispersant 0.2-0.5 parts of wetting agent, Defoamer 0.4-0.8 parts, Anti-settling agent 0.2-0.5 parts, Thickener 0.2-0.5 parts, Leveling agent 0.2-0.5 parts, Preservative 0.2-0.5 parts, pH adjuster 0.1-0.15 parts, 7-15 parts deionized water 25-35 parts of a high-reflectivity particle mixture 10-20 parts of a full atmospheric window radiation particle composition; Component B is a polyisocyanate curing agent; The preparation method of the full atmospheric window radiation particle composition is as follows: nano titanium dioxide, nano cerium oxide, β-type polyvinylidene fluoride and zirconium dioxide high emissivity particles are uniformly mixed in a weight ratio of 2.7-3.3:0.9-1.1:0.9-1.1:0.4-0.6, and then melted at a high temperature of 150℃-160℃ for 3-5 minutes. After that, it is rolled with a 50T-60T rolling mill and then ground to form micron-sized irregular synaptic agglomerates, thus obtaining the full atmospheric window radiation particle composition. The high-reflectivity particle mixture is physically and uniformly mixed from primary reflective particles fumed alumina and auxiliary reflective enhancement particles at a weight ratio of 4-5:1; the auxiliary reflective enhancement particles are composed of at least two of the following in equal mass: rutile titanium dioxide, α-phase ceramic micro powder, zinc oxide, or barium sulfate.

[0006] The all-atmospheric window radiation particle composition used in this invention can absorb electromagnetic waves in the 8-13 μm wavelength band. Specifically, nano-titanium dioxide mainly absorbs electromagnetic waves with wavelengths of 11-13 μm, nano-cerium oxide mainly absorbs electromagnetic waves with wavelengths of 9-12 μm, and β-type polyvinylidene fluoride mainly absorbs electromagnetic waves with wavelengths of 8-10 μm. Through high-temperature melting, rolling, and grinding processes, radiation particles (β-type polyvinylidene fluoride (PVDF)) are used as a carrier to bind other radiation microparticles (nano-titanium dioxide, nano-cerium oxide, and zirconium dioxide) together in a specific ratio, forming micron-sized irregular synaptic aggregates. This ensures uniform mixing of the functional particles, increases the surface area of ​​the radiation particles, and improves the synergistic effect between the particles (ensuring that each radiation particle can fully absorb electromagnetic waves in its main wavelength band, thereby enhancing the radiative cooling effect).

[0007] Preferably, the mass ratio of component A to component B is 5.3-5.7:1, and component A is mainly prepared from the following components in parts by weight: Hydroxyacrylic emulsion 38-47 parts, Dispersant 1.3-1.8 parts, Wetting agent 0.25-0.3 parts, Defoamer 0.5-0.7 parts, Anti-settling agent 0.25-0.3 parts, Thickener 0.25-0.3 parts, Leveling agent 0.27-0.4 parts, Preservative 0.2-0.3 parts, pH adjuster 0.1-0.12 parts, 8-11 parts deionized water 25-35 parts of a high-reflectivity particle mixture 10-20 parts of a full atmospheric window radiation particle composition.

[0008] Preferably, the dispersant is a polyether-based nonionic dispersant, the wetting agent is a polyether-modified silicone wetting agent, the defoamer is a polyether siloxane defoamer, the anti-settling agent is a titanate coupling agent anti-settling agent, the thickener is a polyether polyurethane thickener, the leveling agent is a dipropylene glycol n-butyl ether leveling agent, the preservative is an isothiazolinone-based water-based preservative, and the pH adjuster is dimethylethanolamine.

[0009] Preferably, in the all-atmospheric window radiation particle composition, the nano-titanium dioxide has a particle size of 50-200 nm; the nano-cerium oxide has a particle size of 50-200 nm; the β-type polyvinylidene fluoride has a molecular weight of 80,000-100,000 and a particle size of 2-4 μm; and the zirconium dioxide has a particle size of 0.1-1 μm. The particle size of the primary reflective particles, fumed alumina, is 0.1-1 μm; the particle size of the rutile titanium dioxide is 0.5-2 μm; the particle size of the α-phase ceramic micropowder is 0.1-1 μm; the particle size of the zinc oxide is 0.1-1 μm; and the particle size of the barium sulfate is 0.5-2 μm.

[0010] The present invention also provides a method for preparing the above-mentioned metal-based waterborne radiation-cooling coating topcoat, comprising the following steps: (a) Preparation of component A: (1) Add 70-80% deionized water, 60%-80% dispersant and 40%-60% defoamer to the stirred tank and stir at a speed of 300-500 rpm for 3-5 minutes. Then add the high reflectivity particle mixture and the full atmospheric window radiation particle composition to the stirred tank and stir for 5-8 minutes. Then increase the speed to 1500-1800 rpm and disperse at high speed for 15-20 minutes to form a uniform slurry. (2) Add the slurry to the grinder and grind it appropriately so that the particle size in the slurry is less than 40μm; (3) Add the ground slurry to the mixing tank, add hydroxy acrylic emulsion, the remaining deionized water, the remaining dispersant, leveling agent, preservative, wetting agent and the remaining defoamer according to the formula, and stir at a stirring speed of 500-800 rpm for 15-20 minutes until uniform. (4) Keep the rotation speed of step (3), continue to add anti-precipitant, thickener and pH adjuster, stir to adjust the viscosity to 100-105KU, continue to stir for 10-15 minutes until uniform, and obtain component A; (ii) During construction, mix component A and component B evenly to obtain the metal-based water-based radiation cooling coating topcoat.

[0011] Compared with the prior art, this invention application has the following advantages: 1. The all-atmospheric window radiation particle composition used in this invention can absorb electromagnetic waves in the 8-13 μm wavelength band. Specifically, nano-titanium dioxide mainly absorbs electromagnetic waves with wavelengths of 11-13 μm, nano-cerium oxide mainly absorbs electromagnetic waves with wavelengths of 9-12 μm, and β-type polyvinylidene fluoride mainly absorbs electromagnetic waves with wavelengths of 8-10 μm. Through high-temperature melting, rolling, and grinding processes, the radiation particles β-type polyvinylidene fluoride (PVDF) are used as a carrier to bond other radiation particles (nano-titanium dioxide, nano-cerium oxide, and zirconium dioxide) together in a specific ratio, forming micron-sized irregular synaptic aggregates. This ensures uniform mixing of the functional particles, increases the surface area of ​​the radiation particle composition, and improves the synergistic effect between the radiation particles (ensuring that each radiation particle can fully absorb electromagnetic waves in its main wavelength band, thereby enhancing the radiative cooling effect).

[0012] 2. This invention employs a high-reflectivity particle mixture composed of primary reflective particles (vaporized alumina) and auxiliary reflective enhancement particles. This mixture, along with a full-atmospheric window radiation particle composition, exhibits excellent synergistic effects, significantly improving the coating's solar reflectivity and radiative cooling performance. Furthermore, by optimizing the proportions of each component, a dual enhancement of high reflectivity and high emissivity is achieved, enabling the coating to effectively reflect sunlight and radiate 8-13μm electromagnetic waves into outer space through the atmospheric window, thereby reducing the internal temperature of the coating and achieving significant energy-saving effects.

[0013] 3. The coating topcoat of the present invention uses hydroxyl acrylic emulsion and polyisocyanate curing agent, as well as a variety of additives, so that the coating has good physical properties and high environmental performance.

[0014] 4. The coating of the present invention has wide applicability on different substrate materials. Since the coating of the present invention meets the product requirements of water-based polyurethane coatings as topcoats for metal surfaces, it is particularly suitable for metal substrates, such as industrial plants, power equipment, grain storage, petrochemicals, cold chain transportation, etc., thus meeting the diverse needs of the construction and industrial fields for radiation cooling coatings.

[0015] 5. The coating topcoat of the present invention can be used with Three Trees FFDWOO6 water-based epoxy zinc-rich primer and Three Trees FZWO66 water-based epoxy micaceous iron oxide intermediate paint, and the composite coating has better weather resistance and other physical properties. Attached Figure Description

[0016] Figure 1 This is a scanning electron microscope image of the all-atmospheric window radiation particle composition of Example 1 of this application. Detailed Implementation

[0017] The exemplary embodiments of the present invention are described in more detail below. These embodiments are intended to provide a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art. While exemplary embodiments of the present invention are shown, it should be understood that the invention should not be limited to the embodiments set forth herein.

[0018] Table 1. Formulations (parts by weight) for Examples 1-6

[0019] Table 2 Formulations (parts by weight) of Examples 7-10 and Comparative Example 1

[0020] Example 1 A method for preparing a metal-based waterborne radiation-cooling coating topcoat includes the following steps: (a) Preparation of component A: (1) Add 80% deionized water, 80% dispersant and 50% defoamer to the mixing tank and stir at a speed of 300 rpm for 3 minutes. Then add the high reflectivity particle mixture and the full atmospheric window radiation particle composition to the mixing tank and stir for 5 minutes. Then increase the speed to 1500 rpm and disperse at high speed for 15 minutes to form a uniform slurry. (2) Add the slurry to the grinder and grind it appropriately so that the particle size in the slurry is less than 40μm; (3) Add the ground slurry to the mixing tank, add hydroxy acrylic emulsion, the remaining deionized water, the remaining dispersant, leveling agent, preservative, wetting agent and the remaining defoamer according to the ratio, and stir at a stirring speed of 500 rpm for 15 minutes until uniform. (4) Keep the rotation speed of step (3), continue to add anti-settling agent, thickener and pH adjuster, adjust the viscosity to 100-105KU, continue to stir for 10 minutes until uniform, and obtain component A; (ii) During construction, mix component A and component B evenly in proportion to obtain the metal-based water-based radiation cooling coating topcoat.

[0021] The preparation method of the full atmospheric window radiation particle composition is as follows: nano titanium dioxide, nano cerium oxide, β-type polyvinylidene fluoride and zirconium dioxide high emissivity particles are uniformly mixed according to the formula in Table 1, and after being melted at 160°C for 3 minutes, they are rolled with a 50T rolling mill and then ground to form micron-sized irregular synaptic agglomerates, thus obtaining the full atmospheric window radiation particle composition. Example 2

[0022] A method for preparing a metal-based waterborne radiation-cooling coating topcoat includes the following steps: (a) Preparation of component A: (1) Add 70% deionized water, 70% dispersant and 60% defoamer to the mixing tank and stir at a speed of 500 rpm for 4 minutes. Then add the high reflectivity particle mixture and the full atmospheric window radiation particle composition to the mixing tank and stir for 7 minutes. Then increase the speed to 1700 rpm and disperse at high speed for 20 minutes to form a uniform slurry. (2) Add the slurry to the grinder and grind it appropriately so that the particle size in the slurry is less than 40μm; (3) Add the ground slurry to the mixing tank, add hydroxy acrylic emulsion, the remaining deionized water, the remaining dispersant, leveling agent, preservative, wetting agent and the remaining defoamer according to the ratio, and stir at a stirring speed of 800 rpm for 18 minutes until uniform. (4) Keep the rotation speed of step (3), continue to add anti-settling agent, thickener and pH adjuster, adjust the viscosity to 100-105KU, and continue to stir for 15 minutes until uniform, thus obtaining component A; (ii) During construction, mix component A and component B evenly in proportion to obtain the metal-based water-based radiation cooling coating topcoat.

[0023] The preparation method of the full atmospheric window radiation particle composition is as follows: nano titanium dioxide, nano cerium oxide, β-type polyvinylidene fluoride and zirconium dioxide high emissivity particles are uniformly mixed according to the formula in Table 1, and after being melted at 150°C for 5 minutes, they are rolled with a 55T rolling mill and then ground to form micron-sized irregular synaptic agglomerates, thus obtaining the full atmospheric window radiation particle composition. Example 3

[0024] A method for preparing a metal-based waterborne radiation-cooling coating topcoat includes the following steps: (a) Preparation of component A: (1) Add 75% deionized water, 60% dispersant and 40% defoamer to the mixing tank and stir at a speed of 400 rpm for 5 minutes. Then add the high reflectivity particle mixture and the full atmospheric window radiation particle composition to the mixing tank and stir for 8 minutes. Then increase the speed to 1800 rpm and disperse at high speed for 18 minutes to form a uniform slurry. (2) Add the slurry to the grinder and grind it appropriately so that the particle size in the slurry is less than 40μm; (3) Add the ground slurry to the mixing tank, add hydroxy acrylic emulsion, the remaining deionized water, the remaining dispersant, leveling agent, preservative, wetting agent and the remaining defoamer according to the ratio, and stir at a stirring speed of 700 rpm for 20 minutes until uniform. (4) Keep the rotation speed of step (3), continue to add anti-settling agent, thickener and pH adjuster, adjust the viscosity to 100-105KU, and continue to stir for 13 minutes until uniform, thus obtaining component A; (ii) During construction, mix component A and component B evenly in proportion to obtain the metal-based water-based radiation cooling coating topcoat.

[0025] The preparation method of the full atmospheric window radiation particle composition is as follows: nano titanium dioxide, nano cerium oxide, β-type polyvinylidene fluoride and zirconium dioxide high emissivity particles are uniformly mixed according to the formula in Table 1, and after being melted at 155°C for 4 minutes, they are rolled with a 60T rolling mill and then ground to form micron-sized irregular synaptic agglomerates, thus obtaining the full atmospheric window radiation particle composition.

[0026] Examples 4-10: The preparation methods of the metal-based waterborne radiation cooling coating topcoat according to the formulations in Table 1 or Table 2 are the same as in Example 1, and the preparation methods of the all-atmospheric window radiation particle composition are also the same as in Example 1.

[0027] The following is some information about the raw materials used in each embodiment: The high-reflectivity particle mixture is physically homogenized according to the formula in Table 1 or Table 2; The dispersant is a polyether nonionic dispersant, the wetting agent is a polyether-modified organosilicon wetting agent, the defoamer is a polyether siloxane defoamer, the anti-settling agent is a titanate coupling agent anti-settling agent, the thickener is a polyether polyurethane thickener, the leveling agent is a dipropylene glycol n-butyl ether leveling agent, the preservative is an isothiazolinone water-based preservative, and the pH adjuster is dimethylethanolamine; Component B is a polyisocyanate curing agent; The nano-titanium dioxide has a particle size of 50-200 nm; the nano-cerium oxide has a particle size of 50-200 nm; the β-type polyvinylidene fluoride has a molecular weight of 80,000 and a particle size of 2-4 μm; the zirconium dioxide has a particle size of 0.1-1 μm. The particle size of the fumed alumina is 0.1-1 μm, the particle size of the rutile titanium dioxide is 0.5-2 μm, the particle size of the α-phase ceramic micro powder is 0.1-1 μm, the particle size of the zinc oxide is 0.1-1 μm, and the particle size of the barium sulfate is 0.5-2 μm.

[0028] Comparative Example 1: The preparation method of the coating topcoat is the same as that in Example 1, according to the formula in Table 2.

[0029] Comparative Example 2: The topcoat of the present invention was replaced with Three Trees water-based acrylic polyurethane topcoat FFMW120 (i.e., commercially available common radiation cooling coating topcoat).

[0030] Performance testing: Physical properties: Refer to HG / T 4761—2014 "Waterborne Polyurethane Coatings", see Tables 3 and 4; Environmental performance: Refer to GB 30981.2—2025 "Limits of Hazardous Substances in Coatings - Part 2: Industrial Coatings", see Table 5; Radiative cooling performance: see Table 6; Among them, the radiation cooling performance of the metal-based waterborne radiation cooling coating topcoat and the various properties in item 13 of Table 2 need to be tested by preparing a composite coating, while the environmental performance and other physical properties are tested directly on the coating topcoat.

[0031] The composite coating is made by combining the topcoat of Examples 1-10 and Comparative Examples 1-2 with Three Trees FZWO66 waterborne epoxy micaceous iron oxide intermediate paint and Three Trees FFDWOO6 waterborne epoxy zinc-rich primer to form a composite coating with a total thickness of 200-250μm, wherein the primer is 50-60μm, the intermediate paint is 60-80μm, and the topcoat is 90-110μm.

[0032] Table 3. Physical performance test results of Examples 1-6

[0033] Table 4. Physical performance test results of Examples 7-10 and Comparative Examples 1-2

[0034] Table 5. Environmental performance test results of Examples 1-10 and Comparative Examples 1-2

[0035] Table 6. Test results of radiative cooling performance of Examples 1-10 and Comparative Examples 1-2

[0036] The metal-based radiation cooling coating topcoat of this invention not only meets the product requirements for using water-based polyurethane coatings as topcoats on metal surfaces in HG / T 4761—2014 "Waterborne Polyurethane Coatings" (i.e., the physical performance indicators in Tables 3 and 4), and the environmental protection indicators in GB30981.2—2025 "Limits of Hazardous Substances in Coatings - Part 2: Industrial Coatings", but also far exceeds the standards in some aspects. Specifically: Environmental performance: VOC content ≤100g / L (standard 300g / L); Physical performance: Pencil hardness ≥HB (standard ≥B), abrasion resistance (500g / 500r) ≤0.03g (standard ≤0.06g), dry heat resistance (70℃±2℃.15 min) ≤Grade 1 (standard ≤Grade 2).

[0037] The composite coating of this invention, consisting of a metal-based radiation cooling topcoat, an FFDWOO6 waterborne epoxy zinc-rich primer, and an FZWO66 waterborne epoxy micaceous iron oxide intermediate coat, exhibits excellent weather resistance, meeting the requirements of HG / T 4761—2014 "Waterborne Polyurethane Coatings," with some indicators exceeding the standard by more than double. It shows no abnormalities in water resistance after 96 hours (standard 48 hours), no abnormalities in acid and alkali resistance after 48 hours (standard 24 hours), and no blistering, peeling, or cracking after 1000 hours of artificial weathering (standard 500 hours). When the total thickness of the composite coating is 200-250 μm (primer 50-60 μm, intermediate coat 60-80 μm, topcoat 90-110 μm), the solar reflectance (TSR) is ≥0.87, the atmospheric window (8-13 μm band) emissivity (γ) is ≥0.88, the hemispherical emissivity (E) is ≥0.84, and the near-infrared reflectance is ≥0.85.

[0038] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A metal-based water-based radiation cooling coating topcoat, characterized in that: It includes component A and component B, wherein the mass ratio of component A to component B is 5-6:1; Component A is mainly prepared from the following components in the indicated weight proportions: Hydroxy acrylic emulsion 38-50 parts, 1-2 parts dispersant Wetting agent 0.2-0.5 parts, Defoamer 0.4-0.8 parts, Anti-settling agent 0.2-0.5 parts, Thickener 0.2-0.5 parts, Leveling agent 0.2-0.5 parts, Preservative 0.2-0.5 parts, pH adjuster 0.1-0.15 parts, 7-15 parts deionized water 25-35 parts of a high-reflectivity particle mixture 10-20 parts of a full atmospheric window radiation particle composition; Component B is a polyisocyanate curing agent; The preparation method of the full atmospheric window radiation particle composition is as follows: nano titanium dioxide, nano cerium oxide, β-type polyvinylidene fluoride and zirconium dioxide high emissivity particles are uniformly mixed in a weight ratio of 2.7-3.3:0.9-1.1:0.9-1.1:0.4-0.6, and then melted at a high temperature of 150℃-160℃ for 3-5 minutes. After that, it is rolled with a 50T-60T rolling mill and then ground to form micron-sized irregular synaptic agglomerates, thus obtaining the full atmospheric window radiation particle composition. The high-reflectivity particle mixture is physically and uniformly mixed from primary reflective particles fumed alumina and auxiliary reflective enhancement particles at a weight ratio of 4-5:1; the auxiliary reflective enhancement particles are composed of at least two of the following in equal mass: rutile titanium dioxide, α-phase ceramic micro powder, zinc oxide, or barium sulfate.

2. The metal-based waterborne radiation cooling coating topcoat according to claim 1, characterized in that: The dispersant is a polyether-based nonionic dispersant, the wetting agent is a polyether-modified organosilicon wetting agent, the defoamer is a polyether siloxane defoamer, the anti-settling agent is a titanate coupling agent anti-settling agent, the thickener is a polyether polyurethane thickener, the leveling agent is a dipropylene glycol n-butyl ether leveling agent, the preservative is an isothiazolinone-based water-based preservative, and the pH adjuster is dimethylethanolamine.

3. The metal-based waterborne radiation cooling coating topcoat according to claim 1, characterized in that: In the full atmospheric window radiation particle composition, the nano-titanium dioxide has a particle size of 50-200 nm; the nano-cerium oxide has a particle size of 50-200 nm; the β-type polyvinylidene fluoride has a molecular weight of 80,000-100,000 and a particle size of 2-4 μm; and the zirconium dioxide has a particle size of 0.1-1 μm. The particle size of the primary reflective particles, fumed alumina, is 0.1-1 μm; the particle size of the rutile titanium dioxide is 0.5-2 μm; the particle size of the α-phase ceramic micropowder is 0.1-1 μm; the particle size of the zinc oxide is 0.1-1 μm; and the particle size of the barium sulfate is 0.5-2 μm.

4. The method for preparing the metal-based waterborne radiation-cooling coating topcoat according to any one of claims 1-3, characterized in that: Includes the following steps: (a) Preparation of component A: (1) Add 70%-80% deionized water, 60%-80% dispersant and 40%-60% defoamer to the mixing tank and stir at a speed of 300-500 rpm for 3-5 minutes. Then add the high reflectivity particle mixture and the full atmospheric window radiation particle composition to the mixing tank and stir for 5-8 minutes. Then increase the speed to 1500-1800 rpm and disperse at high speed for 15-20 minutes to form a uniform slurry. (2) Add the slurry to the grinder and grind it appropriately so that the particle size in the slurry is less than 40μm; (3) Add the ground slurry to the mixing tank, add hydroxy acrylic emulsion, the remaining deionized water, the remaining dispersant, leveling agent, preservative, wetting agent and the remaining defoamer according to the formula, and stir at a stirring speed of 500-800 rpm for 15-20 minutes until uniform. (4) Keep the rotation speed of step (3), continue to add anti-precipitant, thickener and pH adjuster, stir to adjust the viscosity to 100-105KU, continue to stir for 10-15 minutes until uniform, and obtain component A; (ii) During construction, mix component A and component B evenly to obtain the metal-based water-based radiation cooling coating topcoat.

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