Water-based single-layer self-adaptive thermochromic radiation refrigeration coating and preparation method thereof

Abstract

The invention discloses a water-based single-layer self-adaptive thermochromic radiation refrigeration coating and a preparation method thereof. The preparation method comprises the following steps: preparing radiation refrigeration coating dispersion liquid; the radiation refrigeration coating dispersion liquid comprises the following components in parts by mass: 30-40 parts of spherical zirconium dioxide powder, 20-30 parts of deionized water, 25-35 parts of a water-based emulsion, 1.5-3 parts of a wetting dispersant and 7-9 parts of an auxiliary agent, preparing a thermochromic coating dispersion liquid; the thermochromic dispersion liquid comprises 15-25 parts of thermochromic capsules, 27-37 parts of deionized water, 2-3 parts of an ultraviolet light absorber, 35-42 parts of a water-based emulsion, 1.5-3 parts of a wetting dispersant and 7-9 parts of an auxiliary agent; the radiation refrigeration coating dispersion liquid and the thermochromic coating dispersion liquid are mixed according to the mass ratio of 1: 1-4: 1 and stirred to form the self-adaptive thermochromic radiation refrigeration coating. The purposes of self-adaptive radiation refrigeration and heat preservation can be achieved by sensing the temperature change of the external environment to change color.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering thermophysics, and in particular relates to a water-based single-layer self-adaptive temperature-sensitive color-changing radiation refrigeration coating and a preparation method thereof. Background Art

[0002] The energy consumption of cooling systems accounts for 15% of the world's total energy consumption. Compared with active cooling methods that require energy input, passive cooling does not require additional energy input, which can significantly reduce the energy consumption of cooling systems, thereby effectively alleviating the energy crisis. One of the strategies to achieve passive cooling is radiative cooling. To achieve efficient radiative cooling, the key is to make the heat dissipating object spectrally selective: it has strong radiation capabilities within the atmospheric transparent window range of 8-13 microns, and at the same time has strong reflection capabilities for the sunlight band.

[0003] In the existing radiant cooling coatings, although they can achieve good radiant cooling effects, they cannot adapt to all seasons and all times of the day. In winter or mornings and evenings when the temperature is relatively low, the strong passive radiant cooling effect of the existing coatings increases the heating cost of the building; it also cannot be applied to scenes where the temperature needs to be relatively stable in the four seasons or day and night range with significant temperature changes. At the same time, the organic solvents used in the existing radiant cooling coatings will pollute the environment and cause certain damage to the human respiratory system and brain nervous system. The requirements of the national policy on the prevention and control of volatile organic compounds (VOCs) pollution are becoming increasingly perfect. The latest VOC emission standards issued by the Environmental Protection Bureau have strict requirements for different industries. Among them, the VOC emission limit of the coating production industry is 60mg / m³, which limits the production and application of organic solvent coatings. The existing adaptive radiant cooling coatings are mostly multi-layer structures. It is necessary to apply the radiant cooling coating bottom layer on the substrate and ensure that the bottom layer is flat, otherwise it will affect the coating of other coatings in the multi-layer structure. After at least 28 hours of drying, the adaptive coating can be applied on the radiant cooling bottom layer and secondary drying can be performed. The preparation process is cumbersome, which brings obstacles to practical application. Summary of the invention

[0004] Objective: In view of at least one of the above technical problems, the present invention provides a water-based single-layer adaptive thermochromic radiation cooling coating and a preparation method. When the ambient temperature is high, the coating is white and the solar reflectivity is high; when the ambient temperature is low, the coating is colorful and the solar absorption rate is increased; it can sense the change of external ambient temperature and change color, thereby achieving the purpose of adaptive radiation cooling and heat preservation.

[0005] The technical solution adopted by the present invention is: In a first aspect, an embodiment of the present invention provides a method for preparing a water-based single-layer adaptive thermochromic radiation refrigeration coating, comprising: S1, preparing a radiation cooling coating dispersion; the radiation cooling coating dispersion comprises, by weight, 30-40 parts of spherical zirconium dioxide powder, 20-30 parts of deionized water, 25-35 parts of aqueous emulsion, 1.5-3 parts of wetting dispersant, and 7-9 parts of additives; the additives include pH regulators, preservatives, film-forming additives, leveling agents, defoamers, and thickeners; A pH regulator, a wetting and dispersing agent, a leveling agent, a defoaming agent and a preservative are added to deionized water under stirring at 50-150 rpm; then spherical zirconium dioxide powder is added under stirring at 400-800 rpm; then an aqueous emulsion, a film-forming aid and a thickener are added under stirring at 200-400 rpm; after all the additions are completed, the mixture is stirred at 200-400 rpm for 60-100 minutes to form a radiation cooling coating dispersion.

[0006] S2, prepare a thermochromic coating dispersion; in terms of weight percentage, the thermochromic dispersion includes 15-25 parts of thermochromic capsules, 27-37 parts of deionized water, 2-3 parts of ultraviolet absorbers, 35-42 parts of aqueous emulsions, 1.5-3 parts of wetting dispersants, and 7-9 parts of additives; the additives include pH regulators, preservatives, film-forming aids, leveling agents, defoaming agents, and thickeners.

[0007] Add pH adjuster, wetting dispersant, leveling agent, defoamer, preservative and UV absorber to deionized water under stirring at 50-150 rpm; then add thermochromic capsules under stirring at 400-800 rpm; then add aqueous emulsion, film-forming aid and thickener under stirring at 200-400 rpm; after all are added, stir at 200-400 rpm for 60-100 minutes to form a thermochromic coating dispersion.

[0008] S3, mixing the radiation cooling coating dispersion and the thermochromic coating dispersion in a mass ratio of 1:1-4:1 (preferably 2:1) and stirring for 60-100 minutes to form a self-adaptive thermochromic radiation cooling coating.

[0009] In some embodiments, in S1 and S2, the proportion of the additives, calculated by weight, is: 2 parts of pH adjuster, 1 part of preservative, 34 parts of film-forming aid, 9 parts of leveling agent, 1 part of defoamer, and 5 parts of thickener.

[0010] In some embodiments, the pH adjuster is 2-amino-2-methyl-1-propanol; The preservative is 5-chloro-2-methyl-4-isothiazoline-3-one; The film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and ethylene glycol, and the mass ratio of the 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate to ethylene glycol is 1:1-2:1; The leveling agent is polyether modified polydimethylsiloxane; The defoamer is 681F mineral oil; The thickener is polyurethane.

[0011] In some embodiments, in S1 and S2, the aqueous emulsion is a silicone acrylic emulsion.

[0012] In some embodiments, in S1 and S2, the wetting and dispersing agent is ammonium polyacrylate.

[0013] In some embodiments, in S2, the ultraviolet absorber is 3-[3-(2-H-benzotriazole-2-yl)-4-hydroxy-5-tert-butylphenyl]-propionic acid-polyethylene glycol 300 ester.

[0014] In some embodiments, the particle size of the spherical zirconium dioxide powder is 0.8 to 1.2 microns.

[0015] In a second aspect, an embodiment of the present invention provides a water-based single-layer adaptive thermochromic radiation cooling coating, which is prepared by the above method.

[0016] In the third aspect, an embodiment of the present invention provides a method for preparing an adaptive thermochromic radiation refrigeration coating, comprising: uniformly coating the aqueous single-layer adaptive thermochromic radiation refrigeration coating on the substrate to be coated, drying it in an oven at 30 to 50°C for 22 to 36 hours to form an adaptive thermochromic radiation refrigeration coating.

[0017] In some embodiments, the self-adaptive thermochromic radiation cooling coating is uniformly coated on the substrate to be coated, and dried in an oven at a temperature of 40° C. for 28 hours to form a self-adaptive thermochromic radiation cooling coating.

[0018] In some embodiments, the coating thickness of the adaptive thermochromic radiation refrigeration coating dispersion is 200-800 angstroms.

[0019] The present invention also provides a self-adaptive temperature-sensitive color-changing radiation refrigeration coating, which is prepared by adopting the above method.

[0020] Beneficial effects: Compared with existing radiation cooling coatings, the present invention provides a water-based single-layer adaptive radiation cooling coating, which uses deionized water as a solvent to reduce the emission of volatile organic compounds. At the same time, it is designed as a single-layer structure to reduce the difficulty of preparation. When the ambient temperature is high, the coating is white and the solar reflectivity is high; when the ambient temperature is low, the coating is colorful and the solar light absorption rate increases. The coating maintains a stable high emissivity in the infrared band of 8-13 microns and does not change with the ambient temperature. Thereby, the internal temperature of the building can be adjusted energy-free and adaptively throughout the year, reducing the energy consumption caused by refrigeration and heating equipment and reducing carbon emissions. The color change point temperature and the color at low temperature can be changed by adjusting the formula. The temperature control range is 5-35°C. The color at low temperature can be selected including but not limited to black, red, green, blue and yellow. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the principle of the adaptive temperature-sensitive color-changing radiation cooling coating according to an embodiment of the present invention; Figure 2 1 is a schematic diagram comparing the reflectivity spectra of the coatings of Examples 1-2 of the present invention at different color change temperatures at 0.19-1.8 microns; Figure 3 1 is a schematic diagram comparing the emissivity spectra of coatings with different color change temperatures in Examples 1-2 of the present invention at 2-20 microns; Figure 4 1 is a schematic diagram showing a comparison of reflectance spectra of coatings of Example 1 of the present invention and Comparative Example 2 at different color change temperatures at 0.19-1.8 microns; Figure 5 It is a schematic diagram comparing the emissivity spectra of coatings with different color change temperatures at 2-20 microns in Example 1 of the present invention and Comparative Example 2. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0023] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article.

[0024] For the purpose of this specification and the appended claims, unless otherwise stated, all numbers expressing amounts, percentages or ratios and other numerical values ​​used in this specification and the appended claims are understood to be modified in all cases by the term "about". In addition, all ranges disclosed herein are inclusive and independently combinable.

[0025] The present invention mixes a radiation cooling paint with zirconium dioxide as the main component with a thermochromic paint with thermochromic capsules as the main component to form a new adaptive thermochromic radiation cooling paint, which changes color by sensing the temperature change of the external environment, thereby achieving the purpose of adaptive radiation cooling and heat preservation. The principle diagram is shown in FIG. Figure 1 As shown. The radiation cooling coating not only has a high reflectivity to sunlight, especially electromagnetic waves within the visible light wavelength range, but also has a high infrared emissivity to infrared light of 8-13 microns; the thermochromic coating of the specific formula has a fixed critical color change temperature. When the ambient temperature is higher than the critical color change temperature of the thermochromic capsule, the color is white. At this time, the coating will not absorb the visible light of the sun, and the coating performance is displayed as the performance of the radiation cooling coating, thereby achieving radiation cooling and cooling; when the ambient temperature is lower than the near color change temperature of the thermochromic coating, the coating is colored. At this time, the thermochromic coating will absorb a certain band of visible light from the sun, weakening the cooling effect of the coating. This invention achieves a better radiation cooling effect when the ambient temperature is high by combining the color change of the thermochromic coating with the radiation cooling coating, and actively absorbs part of the sunlight when the ambient temperature is low, thereby achieving adaptive temperature regulation. At the same time, the critical color change temperature and color of the adaptive radiation cooling coating can be regulated by the formula, which not only improves the aesthetics of the traditional radiation cooling coating, but also can turn on or off the radiation cooling according to the adaptive choice of the ambient temperature, so that the coating has a wider range of autonomous adaptive temperature choices.

[0026] The embodiment of the present invention provides a method for preparing a water-based single-layer adaptive thermochromic radiation refrigeration coating, comprising: S1, preparing a radiation cooling coating dispersion; the radiation cooling coating dispersion comprises, by weight, 30-40 parts of spherical zirconium dioxide powder, 20-30 parts of deionized water, 25-35 parts of aqueous emulsion, 1.5-3 parts of wetting dispersant, and 7-9 parts of additives; the additives include pH regulators, preservatives, film-forming additives, leveling agents, defoamers, and thickeners; A pH regulator, a wetting and dispersing agent, a leveling agent, a defoaming agent and a preservative are added to deionized water under stirring at 50-150 rpm; then spherical zirconium dioxide powder is added under stirring at 400-800 rpm; then an aqueous emulsion, a film-forming aid and a thickener are added under stirring at 200-400 rpm; after all the additions are completed, the mixture is stirred at 200-400 rpm for 60-100 minutes to form a radiation cooling coating dispersion.

[0027] S2, prepare a thermochromic coating dispersion; in terms of weight percentage, the thermochromic dispersion includes 15-25 parts of thermochromic capsules, 27-37 parts of deionized water, 2-3 parts of ultraviolet absorbers, 35-42 parts of aqueous emulsions, 1.5-3 parts of wetting dispersants, and 7-9 parts of additives; the additives include pH regulators, preservatives, film-forming aids, leveling agents, defoaming agents, and thickeners.

[0028] Add pH adjuster, wetting dispersant, leveling agent, defoamer, preservative and UV absorber to deionized water under stirring at 50-150 rpm; then add thermochromic capsules under stirring at 400-800 rpm; then add aqueous emulsion, film-forming aid and thickener under stirring at 200-400 rpm; after all are added, stir at 200-400 rpm for 60-100 minutes to form a thermochromic coating dispersion.

[0029] S3, mixing the radiation cooling coating dispersion and the thermochromic coating dispersion in a mass ratio of 1:1-4:1 (preferably 2:1) and stirring for 60-100 minutes to form a self-adaptive thermochromic radiation cooling coating.

[0030] For the radiation cooling coating dispersion, the present invention uses deionized water to replace organic solvents such as acetone and ethylene glycol in traditional radiation cooling coatings, thereby reducing the damage of volatile organic solvents to the human body; at the same time, the invention does not use titanium dioxide powder commonly used in existing radiation cooling coatings, but chooses spherical zirconium dioxide powder. Although the refractive index of zirconium dioxide is slightly lower than that of titanium dioxide, zirconium dioxide solves the problem of strong absorption of titanium dioxide in the ultraviolet band, and thus has a higher radiation cooling capacity. The water-based emulsion selects silicone acrylic emulsion, which is a dispersion containing latex particles. The latex particles are spherical at room temperature. When the temperature exceeds the glass transition temperature of the latex particles, the latex particles change from the glass state to the highly elastic state and fill in the gaps between the sunlight scattering particles to form a paint film; the wetting dispersant can effectively reduce the isoelectric point of the sunlight scattering particles and reduce the interaction potential on the particle surface, so that the particles can be well dispersed in water. Other additives include pH adjusters, preservatives, film-forming aids, leveling agents, defoamers, and thickeners, which are used to adjust the pH value of the coating, provide corrosion protection, adjust viscosity, level, defoam, thicken and other properties, so that it has similar workability to commercial coatings.

[0031] For the thermochromic coating dispersion, the water-based emulsion is still silicone acrylic emulsion, the UV absorber is 3-[3-(2-H-benzotriazole-2-yl)-4-hydroxy-5-tert-butylphenyl]-propionic acid-polyethylene glycol 300 ester, and the ratio of wetting dispersant and additive is the same as that of radiation cooling coating dispersion. The UV absorber can effectively improve the problem that the thermochromic capsule is prone to deterioration under direct sunlight and extend the life of the coating.

[0032] In this embodiment, the proportion of the auxiliary agent is: 2 parts of pH adjuster, 1 part of preservative, 34 parts of film-forming auxiliary agent, 9 parts of leveling agent, 1 part of defoaming agent, and 5 parts of thickener.

[0033] The pH regulator is 2-amino-2-methyl-1-propanol. In the embodiment of the present invention, 2-amino-2-methyl-1-propanol was purchased from ANGUS, and the model number is AMP-95.

[0034] The preservative is 5-chloro-2-methyl-4-isothiazoline-3-one; in the embodiment of the present invention, 5-chloro-2-methyl-4-isothiazoline-3-one was purchased from Rohm and Haas Company, and the model number is Kasson LXE.

[0035] The film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and ethylene glycol, and the mass ratio of the 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and ethylene glycol is 1:1-2:1; the mass ratio of the 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and ethylene glycol in the following embodiments is 1.5:1. In the embodiments of the present invention, the 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate was purchased from Eastman Chemical Company, and the model is Texanol.

[0036] The leveling agent is polyether-modified polydimethylsiloxane; in the embodiment of the present invention, the polyether-modified polydimethylsiloxane was purchased from Shandong Huling New Materials Co., Ltd., and the model number is BE-352.

[0037] The defoaming agent is 681F mineral oil; in the embodiment of the present invention, 681F mineral oil was purchased from Hantai Chemical, model number 681F.

[0038] The thickener is polyurethane. The polyurethane in the embodiment of the present invention is purchased from Hemmings Company, model R430.

[0039] The wetting and dispersing agent is polyacrylic acid ammonium salt. The polyacrylic acid ammonium salt used in the embodiment of the present invention is purchased from Nopco, with the model number being SN5040.

[0040] The ultraviolet absorber is 3-[3-(2-H-benzotriazole-2-yl)-4-hydroxy-5-tert-butylphenyl]-propionic acid-polyethylene glycol 300 ester. In the embodiment of the present invention, 3-[3-(2-H-benzotriazole-2-yl)-4-hydroxy-5-tert-butylphenyl]-propionic acid-polyethylene glycol 300 ester was purchased from Kangjin Chemical, model number UV-1130.

[0041] The thermochromic capsules in this application come from Shenzhen Huancai Bianse Technology Co., Ltd., and use thermochromic capsules with a variety of color developing colors and a critical color change temperature range of 5-35 degrees. For example: the color developing color can be selected from any one of black, red, orange-red, yellow, green, blue, and purple, and the critical thermochromic temperature can be selected from 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, and any value between 5-35 degrees.

[0042] The performance of the water-based single-layer self-adaptive thermochromic radiation refrigeration coating of the present invention is verified by example tests.

[0043] Example 1: In this example, the critical thermochromic temperature of the coating is regulated to 31 degrees Celsius. The thermochromic capsules used are from Shenzhen Huancai Bianse Technology Co., Ltd. The color is black and the critical color change temperature is 31 degrees. The mass fraction of spherical zirconium dioxide powder in the radiation cooling coating dispersion is 35wt%.

[0044] A method for preparing a water-based single-layer adaptive thermochromic radiation refrigeration coating comprises: S1, preparing a radiation cooling coating dispersion; the radiation cooling coating dispersion includes, by weight, 35 grams of spherical zirconium dioxide powder, 25 grams of deionized water, 30 grams of aqueous emulsion (silicone acrylic emulsion), 2 grams of wetting dispersant (ammonium polyacrylate), and 8 grams of additives; by weight, the additives are composed of: 2 parts of pH regulator (2-amino-2-methyl-1-propanol), 1 part of preservative (5-chloro-2-methyl-4-isothiazoline-3-one), 34 parts of film-forming additive (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and ethylene glycol mixed in a mass ratio of 1.5:1), 9 parts of leveling agent (polyether modified polydimethylsiloxane), 1 part of defoamer (681F mineral oil), and 5 parts of thickener (polyurethane).

[0045] A pH regulator, a wetting and dispersing agent, a leveling agent, a defoaming agent and a preservative were added to deionized water under stirring at 100 rpm; spherical zirconium dioxide powder was then added under stirring at 600 rpm; an aqueous emulsion, a film-forming aid and a thickener were then added under stirring at 300 rpm; after all the additions were completed, the mixture was stirred at 300 rpm for 80 minutes to form a radiation cooling coating dispersion.

[0046] S2, preparing a thermochromic coating dispersion; the thermochromic dispersion comprises 18 grams of thermochromic capsules, 30 grams of deionized water, an ultraviolet absorber (3-[3-(2-H-benzotriazole-2-yl)-4-hydroxy-5-tert-butylphenyl]-propionic acid-polyethylene glycol 300 Ester) 2 grams, water-based emulsion (silicone acrylic emulsion) 40 grams, wetting and dispersing agent (ammonium polyacrylate) 2 grams, auxiliary agent 8 grams; calculated by weight, the proportion of the auxiliary agent is as follows: pH regulator (2-amino-2-methyl-1-propanol) 2 parts, preservative (5-chloro-2-methyl-4-isothiazoline-3-one) 1 part, film-forming auxiliary agent (2,2,4-trimethyl-1,3 pentanediol monoisobutyrate and ethylene glycol mixed in a mass ratio of 1.5:1) 34 parts, leveling agent (polyether modified polydimethylsiloxane) 9 parts, defoamer (681F mineral oil) 1 part, thickener (polyurethane) 5 parts.

[0047] Add pH adjuster, wetting dispersant, leveling agent, defoamer, preservative and UV absorber into deionized water under stirring at 100 rpm; then add thermochromic capsules under stirring at 600 rpm; then add aqueous emulsion, film-forming aid and thickener under stirring at 300 rpm; after all are added, stir at 300 rpm for 80 minutes to form a thermochromic coating dispersion.

[0048] S3, mixing the radiation cooling coating dispersion and the thermochromic coating dispersion in a mass ratio of 2:1 and stirring for 80 minutes to form a self-adaptive thermochromic radiation cooling coating.

[0049] A method for preparing an adaptive thermochromic radiation cooling coating comprises: uniformly coating the adaptive thermochromic radiation cooling coating obtained in S3 on a substrate to be coated, and drying it in an oven at a temperature of 40° C. for 28 hours to form an adaptive thermochromic radiation cooling coating. The spectra of the test samples when they are displayed in white and black, respectively.

[0050] First, a UV-Vis-NIR spectrophotometer (Cary6000i) with an integrating sphere accessory was used to test the reflectivity of the coating at 0.19-1.8 microns. Then a Fourier transform infrared spectrometer (Nicolet iS50) was used to measure the reflectivity of the film at 2-20 microns.

[0051] Example 2: In this example, the critical temperature of the coating is 22 degrees Celsius, and the thermochromic capsule used is from Shenzhen Huancai Bianse Technology Co., Ltd. The color is black, and the critical temperature is 22 degrees. The rest is the same as Example 1. The spectra of the test samples when they are displayed in white and black, respectively, are measured in the same way as in Example 1.

[0052] Comparative Example 1: In this comparative example, the critical thermochromic temperature of the coating selected is 31 degrees Celsius. The thermochromic capsules used are from Shenzhen Huancai Bianse Technology Co., Ltd., the color developing color is black, and the critical color change temperature is 31 degrees. No ultraviolet absorber is added, and the rest is the same as Example 1.

[0053] Comparative Example 2: In this comparative example, only the radiation cooling coating is coated on the substrate.

[0054] S1, preparing a radiation cooling coating dispersion; the radiation cooling coating dispersion includes, by weight, 35 grams of spherical zirconium dioxide powder, 25 grams of deionized water, 30 grams of aqueous emulsion (silicone acrylic emulsion), 2 grams of wetting dispersant (ammonium polyacrylate), and 8 grams of additives; by weight, the additives are composed of: 2 parts of pH regulator (2-amino-2-methyl-1-propanol), 1 part of preservative (5-chloro-2-methyl-4-isothiazoline-3-one), 34 parts of film-forming additive (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and ethylene glycol mixed in a mass ratio of 1.5:1), 9 parts of leveling agent (polyether modified polydimethylsiloxane), 1 part of defoamer (681F mineral oil), and 5 parts of thickener (polyurethane).

[0055] A method for preparing a radiation cooling coating comprises: uniformly coating the radiation cooling coating dispersion prepared in S1 on a substrate, the coating thickness of the coating being 300 μm, and drying the coating in an oven at 40° C. for 28 hours to form a radiation cooling coating. The spectrum of the test sample is measured in the same manner as in Example 1.

[0056] Experimental conclusion: The reflectivity spectra of Example 1 and Example 2 at 0.19-1.8 μm are as follows Figure 2 As shown, the radiance spectrum of 2-20 microns is as follows Figure 3 As shown, it can be known that the color change temperature of the invention can be independently selected through formula regulation, which has little effect on the spectrum and has no impact on the effect of the invention.

[0057] The samples of Example 1 and Comparative Example 1 were subjected to ultraviolet irradiation aging tests respectively. After 48 hours, the comparative example sample changed color and failed obviously, while the sample of Example 1 did not change obviously, which proved that the durability of Example 1 was better.

[0058] The reflectivity spectra of Example 1 and Comparative Example 2 at 0.19-1.8 μm are as follows: Figure 4 As shown, the radiance spectrum of 2-20 microns is as follows Figure 5 It can be seen that the invention can change color by sensing temperature changes, thereby changing its own emissivity spectrum and achieving adaptive radiation cooling.

[0059] In summary, the present invention provides a working principle, preparation scheme and coating scheme of a water-based single-layer adaptive radiation cooling coating, and through spectral measurement, it can be known that the coating can adaptively adjust the reflectivity of sunlight of some wavelengths according to the change of ambient temperature, so as to adaptively turn on and off the radiation cooling according to the ambient temperature to adjust the temperature. The radiation cooling dispersion and the thermochromic coating dispersion of the invention are both water-based coatings, which reduce the harm to the human body and the pollution to the environment; the design of the single-layer structure greatly reduces the difficulty of preparation and saves preparation time. The color change according to the ambient temperature is achieved by the thermochromic capsule, and the characteristics of adaptively turning on and off the radiation cooling not only broaden the application scenarios of the radiation cooling coating, so that the application of the radiation cooling coating is to a certain extent freed from the limitations brought by the temperature difference between the day and the temperature difference between the four seasons, but also reduces energy waste. Due to the selectivity of the temperature and color of the thermochromic capsule, the aesthetics and applicability of the coating are improved.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a water-based single-layer adaptive thermochromic radiation refrigeration coating, characterized in that: include: S1, preparing a radiation cooling coating dispersion; the radiation cooling coating dispersion comprises, by weight, 30-40 parts of spherical zirconium dioxide powder, 20-30 parts of deionized water, 25-35 parts of aqueous emulsion, 1.5-3 parts of wetting dispersant, and 7-9 parts of additives; the additives include pH regulators, preservatives, film-forming additives, leveling agents, defoamers, and thickeners; Adding pH regulator, wetting dispersant, leveling agent, defoamer and preservative to deionized water under stirring at 50-150 rpm; then adding spherical zirconium dioxide powder under stirring at 400-800 rpm; then adding water-based emulsion, film-forming aid and thickener under stirring at 200-400 rpm; after all additions are completed, stirring at 200-400 rpm for 60-100 minutes to form a radiation cooling coating dispersion; S2, preparing a thermochromic coating dispersion; the thermochromic dispersion comprises, by weight, 15-25 parts of thermochromic capsules, 27-37 parts of deionized water, 2-3 parts of ultraviolet absorbers, 35-42 parts of aqueous emulsions, 1.5-3 parts of wetting dispersants, and 7-9 parts of additives; the additives include pH regulators, preservatives, film-forming aids, leveling agents, defoamers, and thickeners; Add pH adjuster, wetting dispersant, leveling agent, defoamer, preservative and UV absorber to deionized water under stirring at 50-150 rpm; then add thermochromic capsule under stirring at 400-800 rpm; then add aqueous emulsion, film-forming aid and thickener under stirring at 200-400 rpm; after all are added, stir at 200-400 rpm for 60-100 minutes to form a thermochromic coating dispersion; S3, mixing the radiation cooling coating dispersion and the thermochromic coating dispersion in a mass ratio of 1:1 to 4:1 and stirring for 60 to 100 minutes to form a self-adaptive thermochromic radiation cooling coating.

2. The method for preparing the water-based single-layer adaptive thermochromic radiation refrigeration coating according to claim 1, characterized in that: In S1 and S2, the proportion of the auxiliary agents is as follows, calculated by weight: 2 parts of pH adjuster, 1 part of preservative, 34 parts of film-forming aid, 9 parts of leveling agent, 1 part of defoamer, and 5 parts of thickener.

3. The method for preparing the water-based single-layer adaptive thermochromic radiation refrigeration coating according to claim 1 or 2, characterized in that: The pH regulator is 2-amino-2-methyl-1-propanol; The preservative is 5-chloro-2-methyl-4-isothiazoline-3-one; The film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and ethylene glycol, and the mass ratio of the 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate to ethylene glycol is 1:1-2:1; The leveling agent is polyether modified polydimethylsiloxane; The defoamer is 681F mineral oil; The thickener is polyurethane.

4. The method for preparing the water-based single-layer adaptive thermochromic radiation refrigeration coating according to claim 1, characterized in that: In S1 and S2, the aqueous emulsion is a silicone acrylic emulsion.

5. The method for preparing the water-based single-layer adaptive thermochromic radiation refrigeration coating according to claim 1, characterized in that: In S1 and S2, the wetting and dispersing agent is ammonium polyacrylate.

6. The method for preparing the water-based single-layer adaptive thermochromic radiation refrigeration coating according to claim 1, characterized in that: In S2, the ultraviolet absorber is 3-[3-(2-H-benzotriazole-2-yl)-4-hydroxy-5-tert-butylphenyl]-propionic acid-polyethylene glycol 300 ester.

7. The method for preparing a water-based single-layer adaptive thermochromic radiation refrigeration coating according to claim 1, characterized in that: The particle size of the spherical zirconium dioxide powder is 0.8-1.2 microns.

8. A water-based single-layer adaptive thermochromic radiation cooling coating, characterized in that: The method is prepared by any one of claims 1 to 7.

9. A method for preparing an adaptive thermochromic radiation refrigeration coating, characterized in that: The water-based single-layer self-adaptive thermochromic radiation cooling coating according to claim 1 is uniformly coated on the substrate to be coated, and dried in an oven at 30-50° C. for 22-36 hours to form a self-adaptive thermochromic radiation cooling coating.

10. The method for preparing the adaptive thermochromic radiation refrigeration coating according to claim 9, characterized in that: The coating thickness of the adaptive thermochromic radiation refrigeration coating dispersion is 200-800 microns.

Images