Double-layer radiation refrigeration coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of energy-saving coatings, and particularly relates to a double-layer radiation refrigeration coating as well as a preparation method and application thereof. The invention provides a double-layer radiation refrigeration coating. The double-layer radiation refrigeration coating comprises an upper-layer protective coating and a lower-layer reflective coating, the upper-layer protective coating is prepared from the following raw materials in parts by mass: 5 to 100 parts of fluorine-containing polymer, 30 to 500 parts of organic solvent and 5 to 160 parts of deionized water; the lower-layer reflective coating is prepared from the following raw materials in parts by mass: 10 to 200 parts of inorganic pigment powder, 5 to 300 parts of water-based resin and 30 to 400 parts of organic dispersing solvent.

Description

Technical Field

[0001] The invention belongs to the technical field of energy-saving coatings, and in particular relates to a double-layer radiation cooling coating and a preparation method and application thereof. Background Art

[0002] Global warming has increased the demand for refrigeration in all walks of life. However, traditional refrigeration technologies (such as air conditioning, etc.) consume about 15% of the world's electricity and emit greenhouse gases, causing a more serious greenhouse effect. Radiative cooling is a zero-energy sub-ambient (below ambient temperature) refrigeration technology. It continuously inputs heat into a natural cold sink such as outer space (3K) through the thermal radiation of the "atmospheric window" (wavelength 8-13 microns), thereby achieving zero-energy sub-ambient refrigeration.

[0003] However, many current radiant cooling coatings lack the ability to withstand extreme weather conditions, especially continuous heavy rainfall. In fact, in areas with frequent rainfall, rain erosion seriously hinders the long-term and efficient functioning of radiant cooling coatings.

[0004] Therefore, developing a radiant cooling coating with rain erosion resistance can fill a major gap in weather-resistant radiant cooling coatings. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the embodiment of the present invention proposes a double-layer radiation cooling paint, the radiation cooling coating formed by the paint has an average reflectivity of 96% in the sunlight band and an average reflectivity of 91% in the range of 8 to 13 microns. Its own temperature at noon is 6 to 7°C lower than the ambient air, and the cooling effect is higher than that of the white paint sold on the market.

[0006] A double-layer radiation cooling paint according to an embodiment of the present invention comprises: an upper layer of protective paint and a lower layer of reflective paint;

[0007] The upper protective coating comprises the following raw materials by weight: 5-100 parts of fluorine-containing polymer, 30-500 parts of organic solvent, and 5-160 parts of deionized water.

[0008] The lower reflective coating comprises the following raw materials in parts by mass: 10-200 parts of inorganic pigment powder, 5-300 parts of water-based resin, and 30-400 parts of organic dispersing solvent.

[0009] The advantages and technical effects brought by the double-layer radiation cooling coating of the embodiment of the present invention are as follows: 1. In the embodiment of the present invention, the upper protective coating formed by the fluorine-containing polymer, organic solvent and deionized water can phase separate during the film-forming process to form a protective coating with a porous structure, which has good resistance to rainwater corrosion, scouring and soaking, and can withstand continuous heavy rain for at least 220 days; 2. In the embodiment of the present invention, the water-based resin and pigment used make the coating have good film-forming properties, strong adhesion, and resistance to aging and light; 3. In the embodiment of the present invention, the raw materials used are all raw materials that have been widely industrialized, cheap and easy to purchase, and the use of this coating can obtain a radiation cooling coating that is easy to apply and tightly bonded.

[0010] In some embodiments, the fluorine-containing polymer includes at least one of polychlorotrifluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, polyperfluoroethylene propylene, polyvinyl fluoride, perfluoropropylene, fluorinated polyimide, chlorotrifluoroethylene-vinyl ether copolymer or polytetrafluoroethylene powder;

[0011] And / or, the organic solvent includes at least one of isopropanol, acetone, ethanol, cyclohexanone, toluene, dichloromethane, ether, ethyl acetate, carbon tetrachloride, propylene carbonate or cyclohexane.

[0012] In some embodiments, the inorganic pigment powder includes at least one of silicon oxide, calcium oxide, titanium dioxide, barium sulfate, calcium carbonate, zinc oxide, magnesium oxide, lithopone, zirconium oxide, yttrium oxide or aluminum oxide;

[0013] And / or, the inorganic pigment powder is formed by mixing inorganic pigment powder with a particle size of 10 to 900 nm and inorganic pigment powder with a particle size of 1 to 10 μm in a mass ratio of 1 to 9:9 to 1.

[0014] In some embodiments, the water-based resin includes at least one of water-based acrylic resin, styrene acrylic resin, melamine resin, silicone acrylic resin, polyurethane resin, alkyd resin, phenolic resin, amino resin, acetate acrylic resin, pure acrylic resin or epoxy resin.

[0015] In some embodiments, the organic dispersing solvent includes at least one of ethanol, acetone, cyclohexanone, ethyl acetate, ethyl butyrate, toluene, styrene, ethylene glycol ether, triethanolamine, or dichloromethane.

[0016] An embodiment of the present invention provides a method for preparing a double-layer radiation coating, comprising the following steps:

[0017] (1) mixing inorganic pigment powder, water-based resin and organic dispersing solvent to form a lower reflective coating;

[0018] (2) The fluorine-containing polymer is mixed with an organic solvent and then deionized water is added to form an upper protective coating.

[0019] In some embodiments, in step (1) and / or step (2), the mixing method includes at least one of mechanical stirring, magnetic stirring or ultrasound.

[0020] An embodiment of the present invention also provides an application of the above-mentioned double-layer radiation cooling coating or the double-layer radiation cooling coating prepared by the above-mentioned preparation method, comprising: coating a lower reflective coating on a substrate and drying it to form a lower reflective coating layer, and then coating an upper protective coating layer on the lower reflective coating layer to form an upper protective coating layer.

[0021] In some embodiments, the coating method includes at least one of drop coating, spin coating, and spray coating.

[0022] In some embodiments, the thickness of the upper protective coating is not less than 30 micrometers, and the thickness of the lower reflective coating is not less than 100 micrometers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a microscopic morphology of the double-layer radiation cooling coating with rain erosion resistance obtained in Example 1;

[0024] Figure 2 is a spectral response curve diagram of the double-layer radiation cooling coating with rain erosion resistance prepared in Example 1;

[0025] Figure 3 This is a diagram showing the cooling effect of the double-layer radiation cooling coating with rain erosion resistance obtained in Example 1. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0027] A double-layer radiation cooling paint according to an embodiment of the present invention comprises: an upper layer of protective paint and a lower layer of reflective paint;

[0028] The upper protective coating comprises the following raw materials by weight: 5-100 parts of fluorine-containing polymer, 30-500 parts of organic solvent, and 5-160 parts of deionized water.

[0029] The lower reflective coating comprises the following raw materials in parts by mass: 10-200 parts of inorganic pigment powder, 5-300 parts of water-based resin, and 30-400 parts of organic dispersing solvent.

[0030] In the double-layer radiation cooling coating of the embodiment of the present invention, the upper protective coating formed by the fluorine-containing polymer, organic solvent and deionized water can phase separate during the film-forming process to form a protective coating with a porous structure, and has good resistance to rainwater corrosion, scouring and soaking, and can withstand continuous heavy rain for at least 220 days; in the embodiment of the present invention, the water-based resin and pigment used make the coating have good film-forming properties, strong adhesion, and resistance to aging and light; in the embodiment of the present invention, the raw materials used are all raw materials that have been widely industrialized, cheap and easy to purchase, and the use of this coating can obtain a radiation cooling coating that is easy to apply and tightly bonded.

[0031] In some embodiments, preferably, the fluorine-containing polymer includes at least one of polychlorotrifluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, polyperfluoroethylene propylene, polyvinyl fluoride, perfluoropropylene, fluorinated polyimide, chlorotrifluoroethylene-vinyl ether copolymer or polytetrafluoroethylene powder.

[0032] In the embodiment of the present invention, the preferred fluoropolymer can be constructed into a porous structure by a phase separation method, and has very good hydrophobic properties, and can achieve very good protection effects.

[0033] In some embodiments, preferably, the organic solvent includes at least one of isopropanol, acetone, ethanol, cyclohexanone, toluene, dichloromethane, ether, ethyl acetate, carbon tetrachloride, propylene carbonate or cyclohexane. In the embodiments of the present invention, there is no need to specifically limit the organic solvent, as long as it can dissolve the fluorine-containing polymer.

[0034] In some embodiments, preferably, the inorganic pigment powder includes at least one of silicon oxide, calcium oxide, titanium dioxide, barium sulfate, calcium carbonate, zinc oxide, magnesium oxide, lithopone, zirconium oxide, yttrium oxide or aluminum oxide.

[0035] In the embodiment of the present invention, a type of inorganic pigment powder is preferably selected. This type of inorganic pigment has a relatively good refractive index in the sunlight band and is suitable for forming a high-reflectivity coating.

[0036] In some embodiments, preferably, the inorganic pigment powder is a mixture of inorganic pigment powders with a particle size of 10 to 900 nm and a particle size of 1 to 10 μm in a mass ratio of 1 to 9:9 to 1, for example, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, etc.

[0037] In the embodiment of the present invention, the use of fillers with mixed particle sizes can provide Mie scattering in a wide range in the sunlight band compared to fillers with a single particle size, thereby obtaining a higher reflectivity.

[0038] In some embodiments, preferably, the water-based resin includes at least one of water-based acrylic resin, styrene acrylic resin, melamine resin, silicone acrylic resin, polyurethane resin, alkyd resin, phenolic resin, amino resin, acetate acrylic resin, pure acrylic resin or epoxy resin.

[0039] In some embodiments, preferably, the organic dispersing solvent includes at least one of ethanol, acetone, cyclohexanone, ethyl acetate, ethyl butyrate, toluene, styrene, ethylene glycol ether, triethanolamine or dichloromethane.

[0040] An embodiment of the present invention provides a method for preparing a double-layer radiation coating, comprising the following steps:

[0041] (1) mixing inorganic pigment powder, water-based resin and organic dispersing solvent to form a lower reflective coating;

[0042] (2) The fluorine-containing polymer is mixed with an organic solvent and then deionized water is added to form an upper protective coating.

[0043] In some embodiments, preferably, in step (1) and / or step (2), the mixing method includes at least one of mechanical stirring, magnetic stirring or ultrasound.

[0044] An embodiment of the present invention also provides an application of the above-mentioned double-layer radiant cooling coating or the double-layer radiant cooling coating prepared by the above-mentioned preparation method, comprising: coating a lower reflective coating on a substrate and drying it to form a lower reflective coating layer, and then coating an upper protective coating layer on the lower reflective coating layer to form an upper protective coating layer.

[0045] In some embodiments, preferably, the coating method includes at least one of drop coating, spin coating or spray coating.

[0046] In some embodiments, preferably, the thickness of the upper protective coating is not less than 30 microns, and the thickness of the lower reflective coating is not less than 100 microns.

[0047] The technical solution of the present invention is described in detail below in conjunction with specific embodiments and drawings.

[0048] Example 1

[0049] (1) firstly, zinc oxide powder with a particle size of 10 to 900 nm and zinc oxide powder with a particle size of 1 to 10 μm are mixed in a mass ratio of 1:1, and the mixed zinc oxide powder, silicone-acrylic resin and acetone are mechanically stirred and uniformly mixed in a mass ratio of 25 parts, 60 parts and 80 parts to form a lower reflective coating;

[0050] (2) mixing polyvinylidene fluoride-hexafluoropropylene copolymer and ethyl acetate in a mass ratio of 5 parts to 80 parts, stirring evenly, and then adding 10 parts of deionized water to form an upper protective coating;

[0051] (3) The lower reflective coating is evenly coated on the substrate by a scraping method to form a lower reflective coating with a thickness of about 100 μm; the upper protective coating is coated on the lower reflective coating and dried to form an upper rain protection coating with a thickness of 50 μm.

[0052] The solar reflectivity of the double-layer radiative cooling coating prepared in this embodiment is 0.96, and the average emissivity of the atmospheric window 8-13 microns is 0.91. The surface temperature tested on a sunny day is 3°C lower than that of the commercial white coating. After 20 hours of rain scouring, the surface is intact, without blistering, peeling, or cracking, which is equivalent to withstanding about 220 rainstorms.

[0053] The double-layer radiative cooling coating prepared in this embodiment was characterized by SEM, and the results are as follows: Figure 1 As shown, Figure 1 Figure a is a microscopic structure picture of the surface of the lower coating, from which it can be seen that the nano-sized particles and micron-sized ions are evenly mixed; figure b is a microscopic structure picture of the upper rain protection coating, from which it can be seen that the upper rain protection coating presents a porous structure; figure c is a microscopic image of the coating cross section, from which it can be seen that the upper and lower coatings are tightly combined.

[0054] Example 2

[0055] (1) firstly, titanium dioxide powder with a particle size of 10 to 900 nm and titanium dioxide powder with a particle size of 1 to 10 μm are mixed in a mass ratio of 7:3, and the mixed titanium dioxide powder, styrene acrylic resin and ethanol are mechanically stirred and uniformly mixed in a mass ratio of 25 parts, 70 parts and 150 parts to form a lower reflective coating;

[0056] (2) polyvinylidene fluoride and cyclohexane are mixed in a mass ratio of 5 parts to 100 parts and stirred evenly, and then 10 parts of deionized water are added to form an upper layer of rainwater protection coating;

[0057] (3) The radiation cooling coating is uniformly coated on the substrate by a scraping method to form a lower reflective coating with a thickness of 100 μm; the upper rain protection coating is coated on the lower reflective coating and dried to form an upper rain protection coating with a thickness of 50 μm.

[0058] Example 3

[0059] (1) firstly, calcium oxide powder with a particle size of 10 to 900 nm and calcium oxide powder with a particle size of 1 to 10 μm are mixed in a mass ratio of 6:4, and the mixed calcium oxide powder, epoxy resin and toluene are mechanically stirred and uniformly mixed in a mass ratio of 25 parts, 25 parts and 70 parts to form a lower reflective coating;

[0060] (2) polytetrafluoroethylene and acetone are mixed in a mass ratio of 5 parts to 80 parts and stirred evenly, and then 10 parts of deionized water are added to form an upper layer of rainwater protection coating;

[0061] (3) The radiant cooling coating is uniformly coated on the substrate by a scraping method to form a lower reflective coating with a thickness of 100 μm; the upper rain protection coating is applied on the lower reflective coating and dried to form an upper rain protection coating with a thickness of 50 μm.

[0062] Example 4

[0063] (1) firstly, aluminum oxide powder with a particle size of 10 to 900 nm and aluminum oxide powder with a particle size of 1 to 10 μm are mixed in a mass ratio of 1:1, and the mixed aluminum oxide powder, acrylic resin and ethanol are mechanically stirred and uniformly mixed in a mass ratio of 40 parts, 40 parts and 50 parts to form a lower reflective coating;

[0064] (2) mixing polyvinylidene fluoride-hexafluoropropylene copolymer and acetone in a mass ratio of 10 parts to 160 parts, stirring evenly, and then adding 5 parts of deionized water to form an upper protective coating;

[0065] (3) The lower reflective coating is evenly coated on the substrate by a scraping method to form a lower reflective coating with a thickness of about 100 μm; the upper protective coating is coated on the lower reflective coating and dried to form an upper rain protection coating with a thickness of 50 μm.

[0066] Example 5

[0067] The preparation method of this embodiment is the same as that of embodiment 1, except that in step (1), the mass ratio of zinc oxide powder with a particle size of 10 to 900 nm and that with a particle size of 1 to 10 μm is 7:3.

[0068] Example 6

[0069] The preparation method of this embodiment is the same as that of embodiment 1, except that in step (1), the mass ratio of zinc oxide powder with a particle size of 10 to 900 nm to that with a particle size of 1 to 10 μm is 3:7.

[0070] Example 7

[0071] The preparation method of this embodiment is the same as that of embodiment 1, except that the particle size of the zinc oxide powder used in step (1) is 10 to 900 nm.

[0072] Example 8

[0073] The preparation method of this embodiment is the same as that of embodiment 1, except that the particle size of the zinc oxide powder used in step (1) is 1 to 10 μm.

[0074] Comparative Example 1

[0075] The preparation method of this comparative example is the same as that of Example 1, except that the amount of zinc oxide powder used in step (1) is 10 parts.

[0076] Comparative Example 2

[0077] The preparation method of this comparative example is the same as that of Example 1, except that the upper layer of rain protection coating is not applied in step (2).

[0078] Comparative Example 3

[0079] The preparation method of this comparative example is the same as that of Example 1, except that in step (3), the lower reflective coating and the upper protective coating are mixed evenly and then applied on the substrate to form a coating with a thickness of 150 μm.

[0080] The coatings prepared in Examples 1 to 8 and Comparative Examples 1 to 3 were tested for performance, and the results are shown in Table 1. The test methods for each performance are as follows:

[0081] (1) Solar reflectance: The solar reflectance is measured by using an ultraviolet spectrophotometer (Hitachi UH5700) equipped with an integrating sphere attachment according to JIS K 5675. This method measures the reflectance spectrum of the coating sample and multiplies it by the weight coefficient of the transmission spectrum to calculate the solar reflectance by weighted averaging;

[0082] (2) The average emissivity of the atmospheric window of 8-13 μm is calculated using a Fourier transform infrared spectrometer. The inner diameter of the integrating sphere should not be less than 60 mm, and the inner wall should be made of highly reflective material. The standard plate is a gold mirror, which is used for baseline calibration. The atmospheric window emissivity of the sample can be calculated by performing a baseline scan and a sample spectral reflectance scan within the specified wavelength range;

[0083] (3) Rainwater erosion resistance time: The time when the sample is placed under a faucet with uniform flow rate and continuously flushed, and its reflection changes significantly;

[0084] (4) Spectral image: obtained by testing with an ultraviolet spectrophotometer and a Fourier transform infrared spectrometer, wherein the optical image of Example 1 is as follows Figure 2 As shown, from Figure 2It can be seen that the double-layer radiation cooling coating prepared in this embodiment has a higher reflectivity in the sunlight band and a higher emissivity in the mid- and far-infrared bands;

[0085] (5) Cooling effect: The test result was obtained by testing a designed device, which is composed of heat-insulating styrene foam, aluminum foil and polyethylene. The thermocouple was placed in the device under the sample and its temperature was recorded under strong sunlight. The temperature change of Example 1 is as follows: Figure 3 As shown, from Figure 3 It can be seen that the cooling effect of Example 1 is 3°C lower than that of ordinary white paint and 7°C lower than that of the environment.

[0086] Table 1

[0087]

[0088] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0089] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A double-layer radiant cooling coating, characterized in that: It includes an upper protective coating and a lower reflective coating; The upper protective coating comprises the following raw materials by weight: 5-100 parts of fluorine-containing polymer, 30-500 parts of organic solvent, and 5-160 parts of deionized water; The lower reflective coating comprises the following raw materials in parts by mass: 10-200 parts of inorganic pigment powder, 5-300 parts of water-based resin, and 30-400 parts of organic dispersing solvent.

2. The double-layer radiation cooling coating according to claim 1, characterized in that: The fluorine-containing polymer includes at least one of polychlorotrifluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, polyperfluoroethylene propylene, polyvinyl fluoride, perfluoropropylene, fluorinated polyimide, chlorotrifluoroethylene-vinyl ether copolymer or polytetrafluoroethylene powder; And / or, the organic solvent includes at least one of isopropanol, acetone, ethanol, cyclohexanone, toluene, dichloromethane, ether, ethyl acetate, carbon tetrachloride, propylene carbonate or cyclohexane.

3. The double-layer radiation cooling coating according to claim 1, characterized in that: The inorganic pigment powder includes at least one of silicon oxide, calcium oxide, titanium dioxide, barium sulfate, calcium carbonate, zinc oxide, magnesium oxide, lithopone, zirconium oxide, yttrium oxide or aluminum oxide; And / or, the inorganic pigment powder is formed by mixing inorganic pigment powder with a particle size of 10 to 900 nm and inorganic pigment powder with a particle size of 1 to 10 μm in a mass ratio of 1 to 9:9 to 1.

4. The double-layer radiation cooling coating according to claim 1, characterized in that: The water-based resin includes at least one of water-based acrylic resin, styrene-acrylic resin, melamine resin, silicone-acrylic resin, polyurethane resin, alkyd resin, phenolic resin, amino resin, acetate-acrylic resin, pure acrylic resin or epoxy resin.

5. The double-layer radiation cooling coating according to claim 1, characterized in that: The organic dispersing solvent includes at least one of ethanol, acetone, cyclohexanone, ethyl acetate, ethyl butyrate, toluene, styrene, ethylene glycol ether, triethanolamine or dichloromethane.

6. The method for preparing the double-layer radiation cooling coating according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) mixing inorganic pigment powder, water-based resin and organic dispersing solvent to form a lower reflective coating; (2) The fluorine-containing polymer is mixed with an organic solvent and then deionized water is added to form an upper protective coating.

7. The method for preparing the double-layer radiation cooling coating according to claim 6, characterized in that: In step (1) and / or step (2), the mixing method includes at least one of mechanical stirring, magnetic stirring or ultrasound.

8. Use of the double-layer radiation cooling coating according to any one of claims 1 to 5 or the double-layer radiation cooling coating prepared by the preparation method according to claim 6 or 7, characterized in that: include: The lower reflective coating is coated on the substrate and dried to form a lower reflective coating layer, and then the upper protective coating is coated on the lower reflective coating layer to form an upper protective coating layer.

9. The use according to claim 8, characterized in that: The coating method includes at least one of drop coating, spin coating or spray coating.

10. The use according to claim 8, characterized in that: The thickness of the upper protective coating is not less than 30 micrometers, and the thickness of the lower reflective coating is not less than 100 micrometers.

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