CN114672205A - Radiation-cooled coating and surface coating method - Google Patents
Radiation-cooled coating and surface coating method Download PDFInfo
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- CN114672205A CN114672205A CN202111591407.2A CN202111591407A CN114672205A CN 114672205 A CN114672205 A CN 114672205A CN 202111591407 A CN202111591407 A CN 202111591407A CN 114672205 A CN114672205 A CN 114672205A
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- 239000011248 coating agent Substances 0.000 title claims abstract description 94
- 238000001816 cooling Methods 0.000 claims abstract description 55
- 230000005855 radiation Effects 0.000 claims abstract description 46
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- 238000000034 method Methods 0.000 claims description 30
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- 239000002904 solvent Substances 0.000 claims description 20
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
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- 239000011148 porous material Substances 0.000 claims description 10
- 229920005569 poly(vinylidene fluoride-co-hexafluoropropylene) Polymers 0.000 claims description 9
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 238000009736 wetting Methods 0.000 claims description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 4
- 238000005507 spraying Methods 0.000 claims description 4
- 239000012080 ambient air Substances 0.000 claims description 3
- 239000010426 asphalt Substances 0.000 claims description 3
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- 239000002023 wood Substances 0.000 claims description 3
- 238000010345 tape casting Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 15
- 238000002310 reflectometry Methods 0.000 abstract description 11
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 abstract description 3
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Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
- C09D127/02—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
- C09D127/12—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C09D127/16—Homopolymers or copolymers of vinylidene fluoride
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D1/00—Processes for applying liquids or other fluent materials
- B05D1/28—Processes for applying liquids or other fluent materials performed by transfer from the surfaces of elements carrying the liquid or other fluent material, e.g. brushes, pads, rollers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/24—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials for applying particular liquids or other fluent materials
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/004—Reflecting paints; Signal paints
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/20—Diluents or solvents
Abstract
The invention relates to a radiation cooling coating and a surface coating method. The radiation cooling coating comprises a mixture comprising a polymer, wherein the mixture is capable of curing to form a porous structure, and the porous structure is arranged to facilitate reflection of solar radiation away from a surface coated with the radiation cooling coating and dissipation of heat by thermal radiation. The invention also provides a surface coating method using the radiation cooling coating. The white porous coating provides high reflectivity in the ultraviolet, visible and near infrared ranges and high emissivity in the mid-infrared range, so that it also exhibits passive radiative cooling in direct sunlight. The coating only uses low-cost and non-toxic green materials, so that the coating is suitable for large-scale application. Because the traditional air conditioner uses a refrigerant and a compressor for cooling, the traditional air conditioner not only damages the ozone layer, but also generates great noise, so that the air conditioner can become a more environment-friendly air conditioner substitute.
Description
Technical Field
The invention relates to a coating, in particular to a radiation cooling coating, and also relates to a method for coating a surface by using the radiation cooling coating, belonging to the technical field of coatings.
Background
In reality, there are various ways to achieve cooling, for example, using an air conditioning system. However, as a major driver of building power demand, air conditioning systems consume large amounts of energy. In particular, the compressor in the conventional air conditioning system consumes a large amount of energy, and the use of refrigerant is a main cause of ozone layer consumption and climate change.
The present invention aims to address the above-mentioned needs and overcome or substantially ameliorate the above disadvantages.
Disclosure of Invention
According to a first aspect of the present invention there is provided a radiation cooling coating comprising a mixture comprising a polymer, wherein the mixture is capable of curing to form a porous structure and the porous structure is arranged to assist in reflecting solar radiation away from a surface coated with the radiation cooling coating and dissipating the heat by thermal radiation.
According to a particular embodiment of the invention, preferably, the polymer-containing mixture is suitable for being subjected to a phase inversion process (phase inversion) to form a porous structure.
According to a particular embodiment of the present invention, preferably, the phase inversion process comprises wet phase inversion (wet phase inversion).
According to a specific embodiment of the present invention, it is preferable that the pore size is distributed in the porous structure from 100nm to 10 μm.
According to a specific embodiment of the present invention, preferably, the porous structure is a multi-layered mesh-like pore structure having a porosity of 50% or more.
According to a particular embodiment of the invention, preferably the radiation-cooled paint is white.
According to a particular embodiment of the invention, preferably, the mixture containing the polymer is capable of curing to form a white coating having a porous structure for coating on a surface.
According to a particular embodiment of the present invention, preferably, the polymer comprises poly (vinylidene fluoride-co-hexafluoropropylene)).
According to a particular embodiment of the invention, preferably, the mixture further comprises a polar solvent and a non-solvent.
More preferably, according to a particular embodiment of the present invention, the polar solvent comprises N-methyl-2-pyrrolidone and/or acetone.
More preferably, according to a particular embodiment of the invention, the non-solvent comprises water and/or ethanol.
According to a particular embodiment of the invention, preferably, the mixture consists of 8-10% w/w poly (vinylidene fluoride-co-hexafluoropropylene), 80-90% w/w N-methyl-2-pyrrolidone solution and 4-10% w/w water.
According to a particular embodiment of the invention, the coating is preferably adapted to reflect radiation in the ultraviolet-visible and/or near-infrared range.
More preferably, according to a particular embodiment of the invention, the coating is adapted to reflect radiation having a wavelength of 0.25 μm to 2.5 μm.
More preferably, according to particular embodiments of the present invention, the coating has a reflectance of greater than about 95% in the ultraviolet-visible range and the near-infrared range.
According to a particular embodiment of the invention, the coating is preferably adapted to radiate heat in the mid-infrared range.
More preferably, according to a particular embodiment of the invention, the coating is adapted to radiate heat at a wavelength of 8 μm to 13 μm.
More preferably, according to a specific embodiment of the present invention, the coating has a mid-infrared emissivity (emissivity) of greater than about 95%.
According to a particular embodiment of the invention, preferably, the surface comprises wood, metal, concrete, asphalt or clay, etc.
According to a second aspect of the present invention there is provided a method of coating a surface with a radiation-cooled paint according to the first aspect of the present invention. The method comprises the following steps: applying a radiation-cooled coating to a surface; the mixture (polymer-containing mixture) is cured to form a porous structure to facilitate reflection of solar radiation off the radiation-cooled coating-coated surface and heat dissipation by thermal radiation.
According to a particular embodiment of the present invention, the curing step is preferably carried out using a phase inversion process.
According to a particular embodiment of the invention, preferably, the curing step comprises wetting the mixture in a non-solvent solution.
More preferably, according to a particular embodiment of the present invention, the non-solvent solution comprises water and/or ethanol.
More preferably, according to a particular embodiment of the invention, the radiation-cooled paint is white.
According to a particular embodiment of the present invention, preferably, the curing step comprises exposing the mixture to ambient air for a predetermined time.
According to a specific embodiment of the present invention, more preferably, the predetermined time is 12 hours or more.
More preferably, according to a specific embodiment of the present invention, the curing step further comprises wetting the surface of the exposed mixture with a non-solvent solution.
More preferably, according to a particular embodiment of the present invention, the non-solvent solution comprises water and/or ethanol.
More preferably, according to a particular embodiment of the invention, the radiation-cooled paint is white.
According to a particular embodiment of the invention, preferably, the curing step is carried out at ambient temperature.
According to a particular embodiment of the present invention, preferably, the step of applying the radiation cooling coating to the surface comprises spraying, knife coating or coating the radiation cooling coating.
Drawings
Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic diagram of the working principle of a radiation-cooled paint according to an embodiment of the present invention.
FIG. 2 is a graph of spectral emissivity of a radiation cooled paint.
Fig. 3 is a graph of spectral reflectance of a radiation cooled coating.
FIG. 4 is a flow chart showing a method of coating a surface with a radiation-cooled coating.
Detailed Description
For objects with a temperature between-40 c and 40 c, the emitted radiation is mainly concentrated in the wavelength range of 8 μm to 13 μm, in which range the atmosphere has a rather high radiation transmission. Thus, radiation in this band is readily transmitted to cold outer space at temperatures of about-273 ℃ to effect cooling. At night, the surface cooling effect is relatively easy to achieve, since without solar radiation, radiative cooling plays a dominant role in thermal equilibrium. However, it may be difficult to achieve a surface cooling effect during the day.
Without wishing to be bound by theory, typical coatings have limited cooling effect. For example, a typical white paint reflects only about 80% of incident visible light, while still absorbing significant amounts of infrared and ultraviolet light. As another example, conventional thermal barrier coatings may assist cooling by increasing the reflectivity of the material, but the reflectivity of these materials has not reached the desired value-few thermal barrier coatings are able to achieve reflectivities above 90%.
To facilitate cooling, a radiant cooling method may be used. Typical radiative cooling methods include coating the surface with a high emissivity metal material in the mid-infrared wavelength range, coating with an effective emissive material that has strong emission in the atmospheric window wavelength range, using photonic crystal materials or multilayer films with metal reflectors (metal reflectors). However, these methods have various disadvantages such as single emission peak, poor cooling effect, complicated manufacturing process, high material cost or unsuitability for large-scale industrial application.
Fig. 1 shows a radiation-cooled paint 100 for coating/covering a surface according to one embodiment of the present invention. The radiant cooling coating 100 can be used to coat the surfaces of various structures and objects, such as walls, exterior walls, tiles, roofs, vehicles, clothing, etc., as well as the surfaces of various materials, such as wood, metal, concrete, asphalt, clay, etc.
For example, the radiation cooling coating 100 can be applied to the exterior surfaces of buildings, ships, vehicles, etc. to enhance heat dissipation to achieve a cooling effect on the surfaces coated with the radiation cooling coating 100. The radiant cooling coating 100 can achieve nighttime and daytime cooling effects as further described below.
The radiant cooling coating 100 can be used as a cooling source to produce cooling effects during the night and day, even when directed in the sun. In particular, the cooling effect is passively generated by dissipating heat from the surface coated with the coating 100 and/or reflecting solar radiation, in particular infrared and/or solar energy, from the coated surface. For example, during passive radiative cooling, the surface of paint 100 (particularly the skyward-facing surface) reflects sunlight at a reflectivity of about 95% or more and radiates heat to outer space at a mid-IR emissivity of about 95% or more, thereby cooling the surface and the material to which paint 100 is applied to a temperature that may be below ambient.
The dope 100 is preferably white and has a porous structure, preferably nano-or micro-sized pores having a pore diameter of 100nm to 10 μm. In particular, the coating 100 has a porosity of about 50%, which creates many discontinuities in the optical index (numerical optical index discontinuities), resulting in high reflectivity in the ultraviolet-visible range and near infrared range that contributes to the reflection of solar radiation on the surface. The high porosity also enhances backscattering and reduces transmission. The pore structure also helps to facilitate emission in the mid-infrared range by high-order Florish resonance (Frohlich resonance).
Specifically, as shown in fig. 2 and 3, the coating 100 can reflect strong sunlight in the wavelength range of 0.25 μm to 2.5 μm, including ultraviolet, ultraviolet-visible, and near-infrared radiation, have a high reflectivity of 95%, and promote reduction of heat obtained from the solar radiation. Coating 100 may also emit thermal radiation in the 8 μm to 13 μm wavelength range, including mid-infrared radiation, with a high emissivity of 95%, and allow ground thermal radiation to pass through, thereby enhancing heat dissipation from surfaces and structures. In this example, the coating 100 provides about 150W/m2And reduces the indoor air temperature of the model house by about 2 c.
Referring to fig. 4, a method 400 of applying a radiation-cooled coating to a surface is shown, including the preparation of the radiation-cooled coating. The method 400 begins with step 402 in which the polymer, polar solvent, and non-solvent are mixed (e.g., by magnetic or mechanical stirring) to form a mixture. The mixture is preferably a homogeneous solution that is capable of solidifying to form a porous structure. In a preferred example, the polymer may comprise a material capable of forming pores, preferably a durable polymer such as poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). As mentioned above, the holes play an important role in achieving high reflectivity and emissivity as well as cooling effect. The polar solvent preferably comprises a volatile organic solvent, such as N-methyl-2-pyrrolidone (NMP), and the non-solvent may comprise water and/or ethanol.
The importance of the polar solvent and the non-solvent will be discussed later. In a preferred embodiment, PVDF-HFP powder is dissolved in NMP solution and stirred by a magnetic stirrer at 25 ℃ to 40 ℃ to form a transparent homogeneous solution. As will be appreciated by those skilled in the art, other methods of agitation may be employed to mix the components of the mixture.
Deionized water was then added to the solution and stirred for about 4 hours until a further clear homogeneous solution was formed. In particular, the further transparent homogeneous solution comprises 8-10% w/w PVDF-HFP, 80-90% w/w NMP solution and 4-10% w/w water.
In step 404, the mixture used to form the radiation cooled coating is obtained by allowing the solution to stand at room temperature for more than about 4 hours until no bubbles are observed in the solution that would otherwise affect the reflectivity and emissivity of the resulting coating 100.
In step 406, a transparent radiation-cooled paint is applied as a layer to the surface to cover the surface. This step can be carried out by spraying the coating material with a sprayer, drawing down the coating material with a doctor blade, coating with different coating tools such as a roller and a brush. The coating preferably coats the surface with a thickness of more than 200 μm (more preferably, 350 μm to 1200 μm).
In step 408, the radiation cooled coating (particularly a homogenous solution) applied to the surface is cured and hardened. Preferably, the solution cures at ambient temperature without the need for heating or the use of catalysts or other additives. Thus, the coating can be cured by simply placing it in a cool and dry place at room temperature and allowing the polar solvent to evaporate.
In addition, curing of the curable coating can be accelerated using a phase inversion process, specifically, a wet phase inversion process involving removal of the solvent from the coating and leaving a porous structure in the cured coating by immersing the coating in a non-solvent solution or exposing the coating to the ambient environment and then wetting the coating with the non-solvent solution. The non-solvent solution may comprise water and/or ethanol.
During curing, the volatile polar solvent (NMP) in the coating quickly volatilizes, leaving water and PVDF-HFP in the coating. During the wet phase inversion, the mixture then undergoes phase separation, with the formation of nano-or micro-scale pores as the water evaporates. As described above, these apertures help to scatter sunlight back and emit thermal radiation into space.
In a preferred embodiment, the clear coat is cured by exposure to ambient air for a predetermined time of about 12 hours. A small amount of, for example, water sufficient to cause a wet phase inversion is then applied to the coating (e.g., by spraying) and allowed to dry in the ambient environment for about 5 hours.
After curing and drying, the clear coating becomes a white coating 100 having a porous structure in step 410. The color and porous structure of the coating 100 collectively contribute to high reflectivity and emissivity. Preferably, the thickness of the coating 100 applied on the surface is more than 200 μm (more preferably, 300 to 1000 μm).
An advantage of these embodiments is that the white porous coating provides high reflectivity in the ultraviolet visible and near infrared ranges and high emissivity in the mid infrared range, such that it also exhibits passive radiative cooling in direct sunlight. Passive radiation cooling has the advantages of zero energy consumption, zero pollution, no mechanical parts, and remarkable energy-saving effect in cooling, protection and environment. The coating only uses low-cost and non-toxic green materials, so that the coating is suitable for large-scale application. Because the traditional air conditioner uses a refrigerant and a compressor for cooling, the traditional air conditioner not only damages the ozone layer, but also generates great noise, so that the air conditioner can become a more environment-friendly air conditioner substitute.
Eliminating or reducing the use of air conditioning also reduces the noise generated by mechanical transmission structures in these systems, and thus can facilitate maintaining a quiet environment by using cooling coatings as a solution to reduce indoor temperatures.
Advantageously, the white and porous coatings can be applied on different material surfaces and can therefore be used in different applications. For example, in transportation systems, cooling coatings may be applied to various forms of vehicles, such as automobiles, trains, ships, and trucks, to reduce heat within the passenger compartment; the cooling coating is coated on a metal frame or the ground around the solar generator set to cool the solar power generation panel, so that the power generation efficiency is improved; or the cooling coating is coated on any outdoor surface needing cooling, thereby achieving the purpose of passive electroless cooling.
In an alternative example, when the temperature becomes too high, the efficiency of the photovoltaic solar panel may be reduced, and a cooling paint may be applied on the mounting structure of the solar panel to make it more efficient.
Or, as the main component of the cooling coating, P (VdF-HFP) is a low-cost high polymer material, is nontoxic, and can be coated on a textile material to cool clothes worn by people.
Further, unlike typical coatings containing white pigments such as insoluble titanium oxide or calcium oxide, the white color of the coating is not generated by the white pigment but by the inherent color of the cured polymer layer having a porous structure. The preparation of the coating according to the invention is simpler and the coatings produced are more chemically stable than typical white coatings. Furthermore, since these metal oxides are not contained in the coating, the porous coating absorbs very little ultraviolet light, so it further lowers the temperature of the covered surface.
It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. For example, the radiation cooling coating may be made using a material other than PVDF-HFP, NMP, and water, or a mass ratio different from the above ratio, as long as it is made of a polymer, a polar solvent, and a non-solvent. In addition, the coating may have pores with a pore size smaller or larger than nano-or micro-scale, or have a porosity of about 50%. The curing process of the coating may also vary. For example, the curing process may include heating or use of chemicals, the wet phase inversion process may be omitted, and the like.
The described embodiments of the invention are, therefore, to be considered in all respects as illustrative and not restrictive. Unless otherwise indicated, any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge.
Claims (31)
1. A radiant cooling coating comprising a mixture comprising a polymer, wherein the mixture is capable of curing to form a porous structure and the porous structure is arranged to assist in reflecting solar radiation away from a surface coated with the radiant cooling coating and dissipating heat by thermal radiation.
2. The radiation-cooled paint of claim 1, wherein the mixture is adapted to undergo a phase inversion process to form a porous structure.
3. The radiation-cooled paint of claim 2, wherein the phase inversion process comprises wet phase inversion.
4. The radiation cooling coating of any one of claims 1-3, wherein the pore size distribution in the porous structure is from 100nm to 10 μm.
5. The radiation cooling coating of any one of claims 1-4, wherein the porous structure has a porosity of 50% or more.
6. The radiation-cooled paint of any one of claims 1-5, wherein the radiation-cooled paint is white.
7. The radiation-cooled paint of claim 6, wherein the mixture is curable to form a white paint having a porous structure for application on a surface.
8. The radiation-cooled paint of any one of claims 1-7, wherein the polymer comprises poly (vinylidene fluoride-co-hexafluoropropylene).
9. The radiation-cooled paint of any one of claims 1-8, wherein the mixture further comprises a polar solvent and a non-solvent.
10. The radiation-cooled paint of claim 9, wherein the polar solvent comprises N-methyl-2-pyrrolidone and/or acetone.
11. The radiation-cooled paint of claim 9 or claim 10, wherein the non-solvent comprises water and/or ethanol.
12. The radiation cooling coating of any one of claims 1-11, wherein the mixture consists of 8-10% w/w poly (vinylidene fluoride-co-hexafluoropropylene), 80-90% w/w N-methyl-2-pyrrolidone solution, and 4-10% w/w water.
13. The radiation cooling coating of any one of claims 1-12, wherein the coating is adapted to reflect solar radiation in the ultraviolet-visible and/or near-infrared range.
14. The radiation-cooled paint of claim 13, wherein the paint is adapted to reflect radiation having a wavelength of 0.25 to 2.5 μ ι η.
15. The radiation-cooled paint of claim 13 or 14, wherein the paint has a solar reflectance greater than 95%.
16. The radiation-cooled paint of any one of claims 1-15, wherein the mixture is adapted to radiate heat in the mid-infrared range.
17. The radiation-cooled paint of claim 16, wherein the paint is adapted to radiate heat at a wavelength of 8 to 13 μ ι η.
18. The radiation-cooled paint of claim 16 or 17, wherein the paint has a mid-ir emissivity of greater than 95%.
19. The radiation-cooled coating of any one of claims 1-18, wherein the surface comprises wood, metal, concrete, asphalt, or clay.
20. A surface coating method comprising the steps of:
applying the radiation-cooled coating of any one of claims 1-19 to a surface; and curing the mixture to form a porous structure.
21. The method of claim 20, wherein the curing step is performed using a phase inversion process.
22. The method of claim 21, wherein the curing step comprises wetting the mixture in a non-solvent solution.
23. The method of claim 22, wherein the non-solvent solution comprises water and/or ethanol.
24. The method of claim 22 or 23, wherein the radiation-cooled paint is white.
25. The method of claim 21, wherein the curing step comprises exposing the mixture to ambient air for a predetermined time.
26. The method of claim 25, wherein the predetermined time is 12 hours or more.
27. The method of claim 25 or 26, wherein the curing step further comprises wetting the surface of the exposed mixture with a non-solvent solution.
28. The method of claim 27, wherein the non-solvent solution comprises water and/or ethanol.
29. The method of claim 27 or 28, wherein the radiation-cooled paint is white.
30. The method of any of claims 20-29, wherein the curing step is performed at ambient temperature.
31. The method of any of claims 20-30, wherein applying the radiation-cooled coating to the surface comprises spraying, doctor blading, or coating the radiation-cooled coating.
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| US20240044593A1 (en) * | 2022-08-03 | 2024-02-08 | City University Of Hong Kong | Passive Radiative Cooling Ceramic |
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