An Inorganic Composite Photonic Coating and Its Application

Abstract

This invention relates to an inorganic composite photonic coating and its applications. The inorganic composite photonic coating of this invention includes a radiation-cooling functional coating or an infrared-reflecting functional coating, or a composite coating including the radiation-cooling functional coating and the infrared-reflecting functional coating arranged from top to bottom. The inorganic composite photonic coating of this invention can perform radiation cooling, infrared reflection blocking and heat preservation, or both, thereby achieving a self-adaptive effect of cooling in summer and blocking and insulating in winter.

Description

Technical Field

[0001] This invention relates to an inorganic composite photonic coating and its applications. Background Technology

[0002] To mitigate the greenhouse effect and global warming, daytime radiative cooling technology has been proposed in recent years. Radiative cooling uses outer space as a cold source and objects on the ground as heat sources to establish a radiative heat transfer channel. Through an "atmospheric window," heat is directly transferred from the ground objects to outer space via electromagnetic radiation of a specific wavelength through the Earth's atmosphere, thus achieving the purpose of cooling.

[0003] However, current radiation-cooling coatings primarily use organic emulsions / organic substrates combined with inorganic pigments and fillers. The use of organic emulsions / organic substrates can lead to yellowing and chalking, resulting in poor weather resistance and consequently a shorter coating lifespan. Furthermore, coatings containing a high amount of organic compounds are easily contaminated, exhibiting poor stain resistance, which also affects the radiation-cooling effect. Additionally, many radiation-cooling coatings are quite thick, leading to higher costs. Moreover, most current radiation-cooling coatings cannot simultaneously achieve both high reflectivity and high emissivity.

[0004] Another side effect of radiative cooling coatings is that they cannot meet the needs of insulation in low-temperature environments such as winter when radiative cooling is not required. Although some technologies exist to improve the thermal insulation performance of radiative cooling coatings, these technologies have shortcomings in terms of weather resistance and service life, radiative cooling performance, and adaptability to winter and summer seasons.

[0005] WO2021083250A1 (PCT / CN2020 / 124665) discloses a coating with intelligent cooling below ambient radiation, comprising TiO2 particles; inorganic particles selected from the group consisting of SiO2, CaCO3, SiC, ZnO, Al2O3, ZnO, BaSO4, Si3N4, and mixtures thereof; fluorescent pigment particles; and a polymer as a binder; the polymer including polystyrene, polyacrylate, alkyl polyacrylate, polymethacrylate, alkyl polymethacrylate, polycarbonate, polyacrylic acid, polymethacrylic acid, mixtures thereof, and copolymers thereof. This coating uses rare-earth-doped fluorescent particles to downconvert the wavelength of incident light with a peak wavelength less than 450 nm to the wavelength of emitted light in the 500 nm to 700 nm range, reducing the absorption of ultraviolet light by titanium dioxide, zinc oxide, etc., due to their inherent properties. However, the adhesive in this coating is an organic polymer, which will inevitably cause yellowing and powdering during long-term outdoor use. Its service life is only 3-6 years, and the surface is easily contaminated, affecting the radiant cooling effect.

[0006] CN102585572A discloses a heat-reflective and heat-insulating inorganic composite material, its preparation method, and its application. This inorganic composite material is a micro / nano composite material with alumina, titanium oxide, and silicon oxide as matrices, doped with one or more rare earth elements selected from yttrium, cerium, and lanthanum. It can be prepared by liquid-phase method, liquid-phase coating method, and solid-phase mixing method, and heat-reflective and heat-insulating coatings can be formulated from this inorganic composite material. However, the reflectivity of this inorganic composite material is low, only about 90%.

[0007] CN114350215A discloses a water-based thermal hysteresis heat storage coating and its application. The coating comprises, by mass percentage: 22-35% aluminum powder, 3.0-10.0% rare earth metal oxides, 2-6% pigment, 35-45% emulsion, 3-6% additives, and 17-22% water. The coating exhibits extremely low emissivity in the infrared region and selective absorption in the visible light region of the solar spectrum, thus allowing for color adjustment. When used on interior walls, compared to polystyrene board insulation systems, it can significantly delay heat dissipation, providing internal insulation. When used on exterior walls, the coating's low-emissivity infrared characteristics can significantly reduce radiative heat exchange between the building's interior / interior and the surrounding external / exterior thermal environments, resulting in warmer winters and cooler summers, improving the building's thermal comfort. However, the aluminum powder in this patent is not coated, making it prone to oxidation or hydrogen evolution reaction with water, thus losing its effectiveness. Furthermore, the particle size of the aluminum powder and titanium dioxide is not mentioned. In addition, the paint uses an organic styrene-acrylic emulsion, which results in poor outdoor weather resistance, potentially requiring replacement every 3-5 years. Replacing the paint will increase the amount of work, raise costs, and cause inconvenience to residents. Summary of the Invention

[0008] The problem the invention aims to solve

[0009] To address the aforementioned problems in current radiative cooling technologies, there is a need for an inorganic radiative cooling coating that is weather-resistant, stain-resistant, environmentally friendly, thin-film, and possesses both high reflectivity and high emissivity (both above 95%). To improve the thermal insulation effect of a space, a coating that reduces heat loss is also needed. Furthermore, to simultaneously meet the needs of both cooling and heating in different seasons, a composite coating that combines cooling and infrared reflective insulation is also required.

[0010] Solution for solving the problem

[0011] To address the aforementioned issues, the inventors conducted in-depth research and, for the first time, proposed an organic combination of radiative cooling and infrared reflection. This enhances near-infrared solar reflection in summer, and more importantly, blocks bidirectional mid-infrared radiation (bidirectional heat transfer), achieving both summer cooling and winter insulation. Applying this to coatings on interior and / or exterior walls has significant economic and environmental benefits, impacting building energy consumption, energy structure, and even the building structure itself (primarily the internal and external insulation layers). Simultaneously, it can reduce or even eliminate the need for insulation materials on interior and exterior walls, reducing costs, construction, building weight, and wall thickness. It solves the problems of doubled construction work, increased costs, inconvenience to residents, and safety concerns associated with repainting ordinary exterior wall coatings every 3-5 years. The coating of this invention can achieve a lifespan as long as the building itself. Furthermore, the radiative cooling layer and infrared reflection layer can be used separately or in combination for different application scenarios.

[0012] Specifically, the present invention provides an inorganic composite photonic coating, wherein the inorganic composite photonic coating includes a radiation-cooling functional coating or an infrared-reflecting functional coating, or includes a composite coating comprising the radiation-cooling functional coating and the infrared-reflecting functional coating arranged from top to bottom.

[0013] The radiation cooling layer includes a first coating and a second coating. The first coating is used to convert a portion of the ultraviolet light in sunlight into visible light, to emit heat through the atmospheric window in a way that enhances infrared radiation within the maximum wavelength range of 8-14 μm of the atmospheric window, and to partially or completely reflect ultraviolet light and / or visible light and / or near-infrared light in the 0.3-2.5 μm wavelength range of sunlight. The second coating is used to enhance the reflection of ultraviolet light and / or visible light and / or near-infrared light in the 0.3-2.5 μm wavelength range of sunlight.

[0014] The infrared reflective coating is used to reflect and block infrared light, and the infrared reflective coating includes inorganic pigments and fillers with reflective and blocking functions.

[0015] The inorganic pigments and fillers with reflective barrier function include coated aluminum powder or coated aluminum silver paste with a particle size of 10-60μm, preferably with a median particle size of 40-60μm, and one or more of titanium dioxide and graphite / graphene with a particle size of 400-1200nm, preferably 600-1000nm.

[0016] According to the inorganic composite photonic coating described above, the thickness of the radiation cooling functional coating is 200-800 μm; and / or, the thickness of the infrared reflection functional coating is 50-200 μm; and / or, the thickness of the first coating is 100-500 μm; and / or, the thickness of the second coating is 100-500 μm.

[0017] According to the inorganic composite photonic coating described above, the first coating comprises an ultraviolet light-converting agent, inorganic pigments and fillers that serve as atmospheric window emission particles, and a first binder; and / or,

[0018] The second coating comprises inorganic pigments and fillers forming a refractive index gradient and a second binder; and / or,

[0019] The infrared reflective coating also includes a third adhesive.

[0020] According to the inorganic composite photonic coating described above, the ultraviolet conversion agent includes one or more of the following: fluorescent whitening agent, ultramarine, zinc copper sulfide, and strontium europium dysprosium aluminate; and / or

[0021] The inorganic pigments and fillers used as atmospheric window emission particles include one or more of silicon dioxide, hexagonal boron nitride, barium sulfate, modified barium metaborate, and modified calcium metaborate, wherein the particle size of each of silicon dioxide, hexagonal boron nitride, barium sulfate, modified barium metaborate, and modified calcium metaborate is 0.1-20 μm.

[0022] The inorganic pigments and fillers forming the refractive index gradient include one or more of the following: titanium dioxide with a particle size of 200-400 nm, hollow glass microspheres with a particle size of 1-30 μm, hollow ceramic microspheres with a particle size of 1-30 μm, aerogel, fumed silica, calcium silicate, calcium phosphate, heavy calcium carbonate powder, modified barium metaborate, and modified calcium metaborate, wherein the particle size of calcium silicate, calcium phosphate, heavy calcium carbonate powder, modified barium metaborate, and modified calcium metaborate is 0.1-20 μm.

[0023] In this invention, the first binder may include one or more of inorganic silicates, liquid silica sol, and organic emulsions. To reduce the organic content in the composite coating, when an organic emulsion is included, the solid content of the organic emulsion shall not exceed 8% by weight relative to the total solid content of the entire inorganic composite photonic coating.

[0024] The first adhesive, the second adhesive, and the third adhesive may be the same as or different from each other.

[0025] According to the inorganic composite photonic coating described above, in the first coating, the content of the ultraviolet conversion agent is 0.2-2.0% by mass relative to the mass of the first coating; the content of the inorganic pigments and fillers that serve as atmospheric window emitting particles is 30-70% by mass relative to the mass of the first coating; and the content of the first binder is 30-70% by mass relative to the mass of the first coating; and / or

[0026] In the second coating, the content of the inorganic pigments and fillers forming the refractive index gradient is 30-70% by mass relative to the mass of the second coating, and the content of the second binder is 30-70% by mass relative to the mass of the second coating; and / or

[0027] In the infrared reflective functional coating, the content of the inorganic pigments and fillers with reflective blocking function is 30-60% by mass relative to the mass of the infrared reflective functional coating, and the content of the third binder is 30-70% by mass relative to the mass of the infrared reflective functional coating.

[0028] According to the inorganic composite photonic coating described above, the coated aluminum powder and the coated aluminum silver paste are respectively coated with silicon or with stearic acid.

[0029] The present invention also provides an application of the inorganic composite photonic coating as described above, wherein, when the inorganic composite photonic coating includes a radiation-cooling functional coating, the inorganic composite photonic coating is applied to the exterior or outer side of a three-dimensional structure and a two-dimensional planar structure.

[0030] When the inorganic composite photonic coating includes an infrared-reflective coating, the inorganic composite photonic coating is applied to the interior or inner side and / or exterior or outer side of a three-dimensional structure or a two-dimensional planar structure.

[0031] When the inorganic composite photonic coating comprises both a radiation-cooling functional coating and an infrared-reflecting functional coating arranged from top to bottom, the inorganic composite photonic coating is applied to the exterior or outer side of a three-dimensional structure or a two-dimensional planar structure.

[0032] The three-dimensional structure includes one of the following: building, container, pipeline, automobile, photovoltaic module, outdoor product, agricultural, livestock and aquaculture equipment, aerospace equipment, cold chain transportation equipment, outdoor container tank, textile industry equipment, outdoor communication equipment, public utility, cooling water system, and energy-saving equipment.

[0033] The two-dimensional planar structure includes one of the following: sheet-like or plate-like metals, plastics, rubber, concrete, cement, asphalt, paper, textiles, wood, ceramic tiles, glass, glass fiber, ceramic fiber, and organic synthetic materials.

[0034] The effects of the invention

[0035] (1) The inorganic composite photonic coating of the present invention, including the radiation cooling functional coating, can convert part of the ultraviolet light in sunlight into visible light, emit heat through the atmospheric window in the maximum wavelength range of 8-14μm in the atmospheric window by enhancing infrared radiation, and partially or completely reflect ultraviolet light and / or visible light and / or near-infrared light in the 0.3-2.5μm wavelength range of sunlight. It can also enhance the reflection of ultraviolet light and / or visible light and / or near-infrared light in the 0.3-2.5μm wavelength range of sunlight, and has a high reflectivity of more than 95% and a high emissivity of more than 95%.

[0036] (2) The inorganic composite photonic coating of the present invention, including an infrared reflective functional coating, can effectively reflect and block infrared light in both directions, thereby enabling space infrared reflection and blocking for heat preservation.

[0037] (3) The inorganic composite photonic coating of the present invention, which includes both a radiation cooling functional coating and an infrared reflection functional coating, has the functions of the above two layers. It can both radiate cooling and infrared reflection for heat insulation, thereby achieving the effect of adaptive cooling in summer and heat insulation in winter. When applied to the coating of building (interior) and exterior walls, it can reduce or even eliminate the need for thermal insulation materials for interior and exterior walls, thereby reducing costs, construction and building weight, and wall thickness. It has a significant impact on the energy consumption and energy structure of buildings, resulting in both economic and energy-saving and environmental benefits.

[0038] (4) The coating of the present invention can be used separately or in combination for different application scenarios, and has a wide range of applications.

[0039] (5) The inorganic composite photonic coating of the present invention mainly uses inorganic materials instead of a large amount of organic emulsion, so it has good weather resistance, is not easy to crack, has a long service life (it can reach the same long service life as the building itself), the inorganic coating has good stain resistance on the hydrophilic surface, is environmentally friendly, and has a thinner thickness and lower cost.

[0040] (6) The inorganic composite photonic coating of the present invention solves the problems of double the amount of construction work, cost, inconvenience to residents' lives and safety caused by the need to replace and recoat ordinary exterior wall coatings every 3-5 years.

[0041] (7) The combination of alkaline coating and borate can play the role of anti-corrosion, anti-mildew, anti-rust and anti-powdering. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the layer structure of the inorganic composite photonic coating including a radiation-cooling functional coating of the present invention.

[0043] Figure 2 This is a schematic diagram of the layer structure of the inorganic composite photonic coating including an infrared reflective functional coating of the present invention.

[0044] Figure 3 This is a schematic diagram of the layer structure of the inorganic composite photonic coating of the present invention, which includes both a radiation cooling functional coating and an infrared reflection functional coating.

[0045] Figure 4 This diagram illustrates the photon propagation and coating position of the radiative cooling infrared reflective layer, the radiative cooling layer, and the infrared reflective layer, using a three-dimensional building envelope as an example.

[0046] Figure 5 Blackbody radiation intensity versus wavelength distribution at different temperatures

[0047] Figure 6 Full-band blackbody radiation capability versus temperature graph

[0048] Figure 7 , Figure 8 , Figure 9 , Figure 10 ,and Figure 11 These are the coating temperatures tested at different locations and at different time periods.

[0049] Figure 12 It is a graph showing the reflectivity of aluminum and aluminum coated with silicon at different wavelengths. Detailed Implementation

[0050] The embodiments of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below; various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining different embodiments and appropriately combining the technical means disclosed in the embodiments are also included within the technical scope of the present invention. Furthermore, all documents described in this specification are incorporated herein by reference.

[0051] Unless otherwise defined, the technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0052] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0053] Unless otherwise stated, in this instruction manual, "more" in "multiple", "multi-variety", "multiple", etc., means a value of 2 or more.

[0054] In this specification, the terms "substantially," "largely," or "truly" mean that the error is less than 5%, or less than 3%, or less than 1% compared to the relevant perfect or theoretical standard.

[0055] Unless otherwise specified, "%" in this instruction manual refers to the percentage content by mass.

[0056] In this instruction manual, if terms such as "room temperature" or "normal temperature" appear, the temperature is generally between 10 and 37°C, or between 15 and 35°C.

[0057] In this specification, the meaning of "may" or "can" includes both the existence or non-existence of something, and both the performance of a certain treatment and the non-performance of a certain treatment.

[0058] In this specification, “optional,” “optional,” and “optionally” mean that the event or situation described below may or may not occur, and the description includes both the scenario in which the event occurs and the scenario in which the event does not occur.

[0059] The term "comprising" and any variations thereof in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion.

[0060] <First Aspect>

[0061] A first aspect of the present invention relates to an inorganic composite photonic coating comprising a radiation-cooling functional coating disposed on a substrate.

[0062] Figure 1 A schematic diagram of the layer structure of the inorganic composite photonic coating of this aspect is shown. For example... Figure 1 As shown, the inorganic composite photonic coating of this aspect includes a radiation-cooling functional coating 1 disposed on a substrate. The radiation-cooling functional coating 1 includes a first coating 101 and a second coating 102 in direct contact with the substrate.

[0063] The first coating 101 is used to convert a portion of the ultraviolet light in sunlight into visible light, to emit heat through the atmospheric window in a way that enhances infrared radiation within the maximum wavelength range of 8-14 μm of the atmospheric window, and to partially or completely reflect ultraviolet and / or visible and / or near-infrared light in the 0.3-2.5 μm wavelength range of sunlight. Therefore, the first coating 101 is an ultraviolet light conversion layer and an "atmospheric window" emitting layer, but it also has a reflective function.

[0064] In this invention, the thickness of the first coating can be 100-500μm, preferably 100-300μm, more preferably 100-200μm, for example, it can be 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, etc.

[0065] The first coating 101 includes an ultraviolet light-converting agent, inorganic pigments and fillers that act as atmospheric windows for emitting particles, and a first binder.

[0066] UV-converting agents are chemical substances that can convert ultraviolet light into visible light. Ultraviolet light excites one or more electrons within the UV-converting agent molecule, causing them to transition from the ground state to an excited state, forming excited-state molecules. These excited-state molecules can return to the ground state through non-radiative transitions, releasing energy in the process and transferring that energy to the matrix. UV-converting agents can improve the color, brightness, transparency, and lightfastness of materials.

[0067] The ultraviolet conversion agent of the present invention may include one or more of the following: fluorescent whitening agents, ultramarine, zinc copper sulfide, and strontium europium dysprosium aluminate. Examples of fluorescent whitening agents may include OB, VBL, etc.

[0068] The inorganic pigments and fillers used as atmospheric window emission particles in this invention may include one or more of the following: silica, hexagonal boron nitride, barium sulfate, modified barium metaborate, modified calcium metaborate, quartz, and aerogel. The particle size of the inorganic pigments and fillers used as atmospheric window emission particles may be 0.1-20 μm. Specifically, the particle size of silica, hexagonal boron nitride, barium sulfate, modified barium metaborate, and modified calcium metaborate is 0.1-20 μm, for example, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, etc.

[0069] Silica at 1090 cm -1 Nearby, there is a Si-O-Si antisymmetric stretching vibration peak at 800 cm⁻¹. -1 Nearby, there is a Si-O bond symmetric stretching vibration peak at 470 cm⁻¹. -1 The vicinity exhibits Si-O bond symmetric stretching vibration peaks. Therefore, silicon dioxide possesses strong emission capability in the 9-12 μm "atmospheric window" range.

[0070] Hexagonal boron nitride (BON) is characterized by high hardness, excellent wear resistance, and good corrosion resistance. Due to its absorption characteristics in the infrared spectral region, it is widely used in optical devices such as infrared windows. The infrared spectral characteristics of hexagonal boron nitride mainly include six characteristic peaks, among which the characteristic peak for infrared radiation from atmospheric windows includes the 810 cm⁻¹ peak generated by the absorption between nitrogen and boron atoms. -1 The most prominent characteristic peak is the one near 12.3 μm; the 1290 cm⁻¹ peak is due to the vibration between nitrogen and boron atoms. -1 Nearby peaks (7.8 μm) and 1300 cm⁻¹ -1 The peak is near (7.7 μm). The inherent properties of hexagonal boron nitride compensate for the insufficient emission capability of silicon dioxide in the 7-9 μm and 12-14 μm bands of the "atmospheric window".

[0071] The most prominent absorption characteristic peaks of barium sulfate in the atmospheric window, from strongest to weakest, are: 1075 cm⁻¹ -1 1123cm-1 1187cm -1 1377cm -1 1366cm -1 984cm -1 722cm -1 Due to its multiple characteristic peaks, it has a high radiation capability in the atmospheric window, further enhancing the emission capability of the maximum band "atmospheric window (8-14μm)".

[0072] The first binder of this invention includes one or more of inorganic silicates, liquid silica sol, and organic emulsions. The inorganic silicates may include potassium silicate, lithium silicate, etc., and the organic emulsions may include fluorocarbon emulsions, tertiary carbon emulsions, styrene-acrylic emulsions, pure acrylic emulsions (i.e., acrylic emulsions), etc. To improve the weather resistance of the inorganic composite photonic coating and reduce VOC release, inorganic silicates and liquid silica sols are preferred. When the first binder includes an organic emulsion, the solid content of the organic emulsion does not exceed 8% by weight relative to the total solid content of the entire inorganic composite photonic coating. Even when using an organic emulsion, this invention uses an emulsion that does not contain alkylphenol polyoxyethylene ether (APEO).

[0073] Silica sol, also known as silica hydrosol, is a colloidal solution of polypolymers of silicic acid. Its colloidal particles have a diameter of 5-80 μm and appear as a translucent milky white substance. Generally, silica sol used in architectural coatings contains 20%-30% silica. When the silica solution loses water, the monomeric silicic acid gradually polymerizes into high-polymer silica gel. As water evaporates, the colloidal molecules increase in size, eventually forming a gel structure with a "-Si-O-Si-" network framework. After drying, it forms a porous structure with a certain degree of air permeability. Due to the low Na2O content in silica sol, its water resistance and heat resistance are significantly better than organic coatings. Furthermore, its film is dense and hard, does not generate static electricity, and does not easily adsorb various dust particles from the air, thus exhibiting strong anti-fouling capabilities. Fine particles can penetrate into the substrate through capillaries and react with calcium hydroxide in the concrete substrate to form calcium silicate, giving the coating strong adhesion. However, silica sol experiences significant volume shrinkage during film formation, making the coating prone to cracking. Therefore, in this invention, silica sol can be used in combination with silicates (potassium silicate, lithium silicate, etc.) and an organic emulsion of no more than 8% by mass.

[0074] Potassium silicate, also known as potassium metasilicate, is a colorless crystal, soluble in water but insoluble in ethanol. Its aqueous solution is alkaline, and it decomposes in acid to release silicic acid gel. In this invention, by combining silica sol, potassium silicate, and no more than 8% by mass of an organic emulsion, the early gelling and film-forming properties of the coating can be improved. Simultaneously, the coating gradually cures and firmly bonds to the substrate throughout its entire lifespan, exhibiting excellent fire resistance, breathability, mildew resistance, rust resistance, corrosion resistance, and UV aging resistance. Furthermore, potassium silicate prevents surface hardening and powdering. Additionally, the silicate nanoparticles in the silica sol can penetrate and embed into the cement-based material along with water molecules, forming a unified gel that solidifies. Therefore, the inorganic coating achieves the same ultra-long service life as the cement-based wall.

[0075] Lithium silicate is a compound formed by the structure and structure of metallic lithium and silicate ions. Commercially known as lithium silicate glass, it is an odorless, tasteless, transparent liquid, alkaline with a pH of around 11 and a relative density between 1.16 and 1.19 (25°C). It is soluble in water and alkaline solutions, but insoluble in alcohols and organic solvents. It reacts with acids to form a gel and exhibits self-drying properties; after the water in the solution evaporates, it forms a water-insoluble dry film with excellent resistance to alternating wet and dry conditions. Lithium silicate aqueous solutions have the characteristic of reacting with hydrophilic surfaces such as glass, steel, aluminum, and fibers to form films; the higher the temperature, the faster the reaction.

[0076] In this invention, an alkaline coating is formed by using alkaline potassium silicate or lithium silicate. With the assistance of borate in the filler, the alkaline coating provides corrosion protection, mildew prevention, rust prevention, and anti-chalking properties.

[0077] In the first coating 101, the content of the ultraviolet light-converting agent relative to the mass of the first coating can be 0.2% to 2.0% by mass, for example, 0.2% by mass, 0.5% by mass, 0.8% by mass, 1.0% by mass, 1.2% by mass, 1.5% by mass, 1.8% by mass, 2.0% by mass, etc. When the content of the ultraviolet light-converting agent is greater than or equal to 1.5% by mass, it can also function as a fluorescent colorant.

[0078] In the first coating 101, the content of inorganic pigments and fillers that serve as atmospheric windows for emitting particles can be 30 to 70% by mass, preferably 40 to 60% by mass, relative to the mass of the first coating. For example, it can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% by mass, etc.

[0079] In the first coating 101, the content of the first adhesive relative to the mass of the first coating can be 30 to 70% by mass, preferably 40 to 60% by mass, for example, it can be 30% by mass, 35% by mass, 40% by mass, 45% by mass, 50% by mass, 55% by mass, 60% by mass, 65% by mass, 70% by mass, etc.

[0080] Additionally, the first coating 101 may optionally contain additives, as long as they do not impair the effects of the invention. Examples of additives may include dispersants, wetting agents, defoamers, thickeners, stabilizers, etc. There are no particular restrictions on the specific types of the additives mentioned above; nonionic additives are preferred, and anionic additives are secondary. However, when inorganic materials can be used, inorganic materials are preferred to reduce the amount of organic matter used in the coating. The content of the aforementioned additives relative to the mass of the first coating may be 0.05 to 2% by mass, preferably 0.1 to 0.5% by mass.

[0081] In some specific embodiments of the present invention, examples of dispersants may include one or more of the following: ammonium polycarboxylate, polyacrylate, polymethacrylate, methylcellulose, carboxymethylcellulose, gelatin, starch, sodium alginate, etc. Examples of wetting agents may include anionic or nonionic wetting agents. Anionic wetting agents include sodium fatty alcohol sulfate, sodium dodecylbenzene sulfonate, or sodium hydroxymethyl dodecyl carboxylate, etc., while nonionic wetting agents include polyoxyethylene ethers such as alkylphenol polyoxyethylene ether (APEO), high-carbon fatty alcohol polyoxyethylene ether (AEO), or fatty acid polyoxyethylene ester (AE), etc. Examples of defoamers may include modified polysiloxanes, special hydrocarbon compounds, hydrophobic particles and hydrocarbons, nonionic surfactants, or modified silicone defoamers, etc. Modified polysiloxanes include amino-modified polysiloxanes or acrylic polysiloxanes; special hydrocarbons include commercially available Deqian W-090 or W-092; hydrophobic particles and hydrocarbons include commercially available BYK-011; nonionic surfactants include polyoxyethylene amines or polyoxyethylene amides; and modified silicone defoamers include commercially available KLD-970 or commercially available LH-511. Examples of thickeners may include cellulose thickeners, cementitious clays, polyurethane thickeners, alkali-swellable thickeners, and combinations thereof.

[0082] The second coating 102 of the present invention is used to enhance the reflection of ultraviolet and / or visible and / or near-infrared light in the 0.3-2.5μm band of sunlight.

[0083] In this invention, the thickness of the second coating 102 can be 100-500μm, preferably 100-300μm, more preferably 100-200μm, for example, it can be 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, etc.

[0084] The second coating 102 includes inorganic pigments and fillers forming a refractive index gradient and a second binder. The inorganic pigments and fillers forming the refractive index gradient of the present invention may include one or more of the following: titanium dioxide with a particle size of 200-400 nm, hollow glass microspheres with a particle size of 1-30 μm, hollow ceramic microspheres with a particle size of 1-30 μm, aerogel, fumed silica, calcium silicate, calcium phosphate, heavy calcium carbonate powder, modified barium metaborate, and modified calcium metaborate. The particle size of the aerogel and fumed silica is not particularly limited and can be adjusted according to actual needs. Regarding the particle size of calcium silicate, calcium phosphate, heavy calcium carbonate powder, modified barium metaborate, and modified calcium metaborate, it can be 0.1-20 μm, preferably 0.5-10 μm, for example, 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, etc. In this invention, by using the aforementioned inorganic pigments and fillers, a coating combining open and closed porous structures, forming multiple high refractive index gradients, can be formed, thereby enabling the coating to possess high reflectivity in the solar band. In the above examples, the hollow glass microspheres and hollow ceramic microspheres have relatively large particle sizes, utilizing the extremely low refractive index close to 1 within the hollow structure to form a gradient with medium refractive index materials (around 1.5) and high refractive index materials such as titanium dioxide (greater than 2). In the above examples, compared to barium metaborate and calcium metaborate, modified barium metaborate and modified calcium metaborate can reduce the occurrence of ionic reactions, making the coating more stable and thus extending its lifespan. Therefore, the second coating 102 is the main reflective layer, but also serves as an atmospheric window auxiliary emission function.

[0085] In some specific embodiments, the particle size of titanium dioxide used for the second coating 102 can be 200nm, 220nm, 250nm, 280nm, 300nm, 320nm, 350nm, 380nm, 400nm, etc. The particle size of hollow glass microspheres or hollow ceramic microspheres used for the second coating 102 can be 1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, etc.

[0086] Titanium dioxide has a high refractive index, with rutile (2.73) having a higher refractive index than anatase (2.55), thus exhibiting superior performance. Therefore, rutile titanium dioxide is preferred in this invention. In films containing high-refractive-index titanium dioxide, light is refracted more significantly, the light path is shorter, and less light is absorbed, thereby enhancing light reflection.

[0087] The type and content of the second adhesive in the second coating 102 are the same as those in the first coating 101 described above, and will not be repeated here. It should be noted that, in specific embodiments, the second adhesive and the first adhesive may be the same as or different from each other.

[0088] In this invention, the content of inorganic pigments and fillers forming the refractive index gradient relative to the mass of the second coating can be 30-70% by mass, preferably 40-60% by mass, for example, 30% by mass, 35% by mass, 40% by mass, 45% by mass, 50% by mass, 55% by mass, 60% by mass, 65% by mass, 70% by mass, etc.

[0089] Similar to the first coating 101, the second coating may also contain additives without compromising the effects of the invention. The types and amounts of additives used in the second coating are the same as those in the first coating, and will not be repeated here. In specific embodiments, the additives used in the second coating may be the same as those used in the first coating, or different.

[0090] The thickness of the radiation cooling functional coating in this aspect can be 200-800μm, for example, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, etc.

[0091] The reflectivity and emissivity of the radiation cooling coating in this aspect can reach over 95%, for example, 95%, 96%, 97%, 98%, etc.

[0092] This invention does not specifically limit the substrate; it can be the interior or inner side and / or exterior or outer side of any three-dimensional or two-dimensional planar structure, such as the interior and / or exterior walls of a building. The three-dimensional structure can include one of the following: buildings, boxes, pipes, automobiles, photovoltaic modules, outdoor products, agricultural, livestock, and aquaculture equipment, aerospace equipment, cold chain transportation equipment, outdoor containers, textile industry equipment, outdoor communication equipment, public utilities, cooling water systems, and energy-saving equipment. The two-dimensional planar structure can include one of the following: sheet-like or plate-like metals, plastics, rubber, concrete, cement, asphalt, paper, textiles, wood, ceramic tiles, glass, glass fiber, ceramic fiber, and organic synthetic materials.

[0093] <Second aspect>

[0094] A second aspect of the present invention relates to an inorganic composite photonic coating comprising an infrared-reflective functional coating 2 disposed on a substrate, such as... Figure 2 As shown. The infrared reflective coating 2 is used to reflect and block infrared light in the mid-infrared band, thereby achieving thermal isolation between the interior and exterior of the space and minimizing heat exchange with the external environment. Examples of substrates in this aspect are the same as those in the first aspect described above, and will not be repeated here.

[0095] The thickness of the infrared reflective functional coating 2 of the present invention can be 50-200μm, preferably 50-150μm, for example, 50μm, 80μm, 100μm, 120μm, 150μm, 180μm, 200μm, etc.

[0096] The infrared reflective functional coating 2 of the present invention includes inorganic pigments and fillers with reflective blocking function. These inorganic pigments and fillers include coated aluminum powder or coated aluminum silver paste with a particle size of 10-60 μm, preferably a median particle size of 40-60 μm, and more preferably 50 μm; and one or more of titanium dioxide, graphite, and graphene with a particle size of 400-1200 nm, preferably 600-1000 nm. The coated aluminum powder and coated aluminum silver paste are each coated with silicon or stearic acid. The silicon-coated or stearic acid-coated aluminum powder or aluminum silver paste has stable properties and can extend the coating life.

[0097] It's important to note that metals possess unique electronic structures and electrical conductivity, significantly different from non-conducting materials. Their free electrons can move freely within the crystal lattice, thus exerting a unique influence on the propagation and interaction of light. The refractive index of a metal is a complex number. The complex refractive index can be divided into a real part and an imaginary part. The real part represents the phase change of light propagating through the metal, measuring how the material affects the speed of light. The imaginary part represents the intensity of light absorption in the metal, determining whether light is absorbed and converted into other forms of energy, typically heat. Due to the high absorption capacity of metals, their imaginary part is large, causing light to attenuate rapidly within them. Metal surfaces can absorb incident light of all wavelengths, and excited electrons transition to higher unoccupied energy levels. For metals, refracted light is immediately absorbed, meaning the energy is immediately absorbed by the free electrons. When light shines on a metal surface, photons excite electrons on the surface to transition from their original orbits to higher energy levels, forming excited-state electrons and generating new photons that radiate outwards. This process of reabsorbing and re-emitting photons is called photon recycling. Therefore, the infrared reflective functional coating of the present invention preferably includes coated aluminum powder or coated aluminum silver paste.

[0098] Aluminum powder consists of flaky aluminum particles with a metallic luster, reflecting 60%-90% of visible, ultraviolet, and infrared light, thus exhibiting excellent light reflection and a metallic luster. Objects coated with paint containing aluminum powder have a bright, silvery-white surface, a characteristic of aluminum powder's light reflection. Aluminum silver paste (also known as aluminum powder paste) is a mixture of aluminum powder and solvent, with uses and properties essentially the same as aluminum powder. Aluminum powder or aluminum silver paste is characterized by its flaky, flake-like structure floating on the coating surface, resulting in smooth, flat, and regularly shaped aluminum flakes. Aluminum is the only material with high reflectivity from the ultraviolet to the infrared region; however, aluminum surfaces are easily oxidized in the atmosphere. Therefore, this invention uses coated aluminum powder or coated aluminum silver paste to extend the coating's lifespan.

[0099] In addition, the inventors have also discovered that the reflectivity, especially the reflectivity in the infrared band, is minimal after aluminum powder or aluminum silver paste is coated compared to before coating. Figure 12The figure shows the reflectivity of aluminum and aluminum coated with silicon at different wavelengths. As can be seen from the figure, the difference in reflectivity between the two is small, so the coating does not significantly affect the infrared reflectivity of aluminum powder or aluminum silver paste.

[0100] In some specific embodiments of the present invention, the particle size of the coated aluminum powder can be 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, etc. The particle size of the coated aluminum silver paste can be 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, etc. The particle size of the titanium dioxide can be 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1200nm, etc.

[0101] Graphite is an allotrope of carbon, a gray-black, opaque solid. It is chemically stable, corrosion-resistant, and does not readily react with acids, alkalis, or other reagents. Graphite's infrared emissivity is typically between 0.75 and 0.85, exhibiting high energy radiation efficiency.

[0102] Graphene is a type of poly(phosphorus) 2 A novel material, graphene, is a single-layer two-dimensional honeycomb lattice structure formed by the close packing of hybridized carbon atoms. The infrared emissivity of graphene is typically between 0.1 and 0.5, mainly depending on the size, number of layers, and other factors. Graphene can absorb and retain thermal energy well in the infrared spectral range.

[0103] In some specific embodiments of the present invention, the particle size of graphite may be 0.5-15 μm, preferably 2-5 μm; the number of graphene layers may be 1-9 layers, preferably 2-5 layers.

[0104] The inorganic pigments and fillers used in the infrared reflective functional coating 2 have a larger particle size, which can reduce the absorption of ultraviolet light and reflect more infrared light, especially infrared light in the mid-infrared band (2.5-25μm).

[0105] In the infrared reflective functional coating of the present invention, the content of inorganic pigments and fillers with reflective blocking function can be 30-60% by mass, preferably 35-50% by mass, relative to the mass of the infrared reflective functional coating, for example, 30% by mass, 35% by mass, 40% by mass, 45% by mass, 50% by mass, 55% by mass, 60% by mass, etc.

[0106] The infrared reflective functional coating of the present invention may further include a third binder. The type and content of the third binder are the same as those in the first coating 101 and the second coating 102 described above, and will not be repeated here. In specific embodiments, the third binder may be the same as or different from the second binder and the first binder.

[0107] In some alternative embodiments, the infrared reflective coating may also optionally include inorganic pigments that allow for good infrared light transmittance, thereby enabling the inorganic composite photonic coating of the present invention to exhibit colors other than white. The inorganic pigments may be selected from one or more of chrome yellow, iron blue, cadmium red, cadmium yellow, lithopone, carbon black, iron oxide red, and iron oxide yellow.

[0108] The infrared reflective layer of the inorganic composite photonic coating in this invention has an infrared reflectivity of over 80% in the mid-infrared band (2.5-25μm).

[0109] <Third aspect>

[0110] The third aspect of the present invention relates to an inorganic composite photonic coating comprising, from top to bottom, a radiation-cooling functional coating as described in the first aspect and an infrared-reflecting functional coating as described in the second aspect, disposed on a substrate, wherein the second coating 102 of the radiation-cooling functional coating is in direct contact with the infrared-reflecting functional coating 2, such as... Figure 3 As shown.

[0111] The present invention can also have a simplified structure, in which the first coating 101 can directly contact the infrared reflective coating when the coating thickness is greater than 150μm, that is: the 101 coating is applied on the second coating to achieve the effect of radiation cooling infrared reflection.

[0112] The inorganic composite photonic coating in this invention has both radiative cooling and reflective heat insulation functions. Therefore, it can radiate cooling when the ambient temperature is high and infrared reflection blocking insulation when the ambient temperature is low, thus achieving a temperature adaptive effect that is warm in winter and cool in summer.

[0113] The thickness of the inorganic composite photonic coating in this aspect can be 250-1000 μm, preferably 250-800 μm, more preferably 250-500 μm, for example, 250 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, etc. The radiation-cooling layer of the inorganic composite photonic coating has a solar reflectivity (0.3-2.5 μm band) of over 95% and an atmospheric window (8-14 μm) emissivity of over 95%. The infrared reflective layer of the inorganic composite photonic coating has an infrared reflectivity of over 80% in the mid-infrared band (2.5-25 μm).

[0114] <Fourth Aspect>

[0115] This aspect relates to a method for preparing inorganic composite photonic coatings.

[0116] The coating of the present invention is prepared by combining all the components. There are no particular limitations on the specific preparation method. Conventional methods can be used, such as combining the above components and mixing them at room temperature or with heat using a mixer, roller, kneader, etc., or using a solvent to dissolve and mix the components.

[0117] In some specific embodiments of the present invention, the coating is a liquid mixture prepared by conventional mixing methods of a light-converting agent, filler, binder, additives, and a suitable solvent. The inorganic composite photonic coating is obtained by applying the obtained liquid mixture to a substrate by spraying, spin-coating, or brushing.

[0118] <Fifth Aspect>

[0119] The fourth aspect of the present invention relates to the application of the inorganic composite photonic coatings described in the first to third aspects above.

[0120] When the inorganic composite photonic coating includes a radiation-cooling functional coating, the inorganic composite photonic coating can be applied to the outside or outside of three-dimensional and two-dimensional planar structures, thereby playing a role in radiation cooling.

[0121] Figure 4 Figure c shows an example of applying a radiative cooling composite coating to the roof and exterior walls of a building. As can be seen from the figure, after applying the radiative cooling composite coating to the roof, significant cooling can be achieved in summer and slight cooling in winter due to atmospheric evaporation and solar reflection. Therefore, radiative cooling composite coatings can be used in situations requiring year-round cooling, such as grain silos or heat-generating facilities and equipment.

[0122] When an inorganic composite photonic coating includes an infrared-reflective coating, it can be applied to the interior or inner side and / or exterior or outer side of three-dimensional and two-dimensional planar structures, thereby providing infrared light reflection and infrared light blocking insulation functions. When applied to the interior or inner side, it can significantly delay the dissipation of indoor heat in winter, providing internal insulation, and in summer, it can block indoor radiation from the sun. When applied to the exterior or outer side, it can reduce radiative heat exchange between the interior or inner side and the surrounding hot or cold environment, providing a warm winter and cool summer effect.

[0123] Figure 4 Figure d shows an example of applying an infrared reflective coating to the roof and inner walls of a house. As can be seen from the figure, the infrared reflective coating functions as a bidirectional reflective barrier, blocking the radiation of outdoor heat (cold) into the room and blocking the radiation of indoor heat (cold) outwards. Therefore, infrared reflective coatings can be used in situations requiring bidirectional insulation throughout the year.

[0124] In addition, in practical applications, radiation-cooling composite coatings and infrared reflective coatings can be used in combination. Figure 4 Figure b shows an example of using both in combination. As can be seen from the figure, a radiative cooling composite coating is applied to the roof to achieve a cooling effect, while an infrared reflective coating is applied to the inner side of the building walls to achieve a thermal insulation effect, thus achieving the effect of keeping the house warm in winter and cool in summer.

[0125] When an inorganic composite photonic coating includes both a radiation cooling functional coating and an infrared reflection functional coating arranged from top to bottom, the inorganic composite photonic coating can be applied to the outside or outside of three-dimensional and two-dimensional planar structures, thereby achieving both radiation cooling and reflective heat insulation functions.

[0126] Figure 4 Figure a shows an example of an inorganic composite photonic coating applied to a roof, comprising both a radiative cooling coating and an infrared reflective coating. As can be seen from the figure, the radiative cooling coating in the inorganic composite photonic coating provides cooling, while the infrared reflective coating provides thermal insulation, making it suitable for both winter and summer use.

[0127] Regarding winter applications, according to the Stefan-Boltzmann law, which states that "the total energy (j) radiated per unit area of ​​a blackbody per unit time is proportional to the fourth power of the blackbody's thermodynamic temperature (T, absolute temperature, in K)," i.e., e b =σΤ 4 σ is the Stefan-Boltzmann constant, with a value of 5.67 × 10⁻⁶. -8 W·m -2 ·K -4 According to the Stefan-Boltzmann law, the total radiant energy of a blackbody depends only on its temperature. The emissivity of a real object is always less than that of a blackbody at the same temperature. Given a fixed material and coating (thus determining the emissivity of the quasi-blackbody or gray body) and the same atmospheric window, the Stefan-Boltzmann law can be used to calculate the difference in emissivity of a blackbody at different temperatures: 10℃ (283K) is 71% of 35℃ (308K), and 0℃ (273K) is 51% of 50℃ (323K). In other words, when the temperature at the top of a three-dimensional building envelope drops from 50℃ in summer to 0℃ in winter, its atmospheric window emissivity decreases to approximately half of its original value. This demonstrates that the radiative cooling capacity in winter has a significantly reduced impact on buildings. (See also...) Figure 6 .

[0128] According to the blackbody radiation law, the wavelength distribution of blackbody radiation is directly related to its temperature; the higher the temperature, the shorter the wavelength of the radiation. The wavelength distribution of blackbody radiation can be described by Planck's formula, which shows that as temperature increases, the radiation capacity of shorter wavelengths increases more rapidly, while the radiation capacity of longer wavelengths increases more slowly. Therefore, the spectrum of high-temperature blackbody radiation is mainly concentrated in the ultraviolet and visible light regions, while the spectrum of low-temperature blackbody radiation is mainly concentrated in the infrared region.

[0129] The relationship between temperature and peak emissivity wavelength can be explained using Wien's displacement law. Wien's displacement law states that at a given temperature, the product of the temperature T of a blackbody and the peak wavelength λ corresponding to its maximum emissivity is a constant, i.e., λmaxT = b (unit: μm·K), where b = 2898 μm·K, called Wien's constant. Therefore, the peak emissivity wavelength at 0℃ (273K) is 10.6 μm, and at 50℃ (323K) it is 9 μm. That is, within the range of 0-50℃, the peak emissivity wavelength is between 10.6 and 9 μm. Considering that there is a certain emissivity within a certain range around the peak wavelength, this invention takes an infrared emission wavelength range of 6-16 μm to cover the entire emissivity range. Within this range, based on literature and temperature tests of this scheme, it can be confirmed that the mid-infrared reflectivity of the infrared reflective material remains within a relatively stable range in both winter and summer, and can be approximately considered constant. (See also...) Figure 5 .

[0130] It is foreseeable that if the coating of the present invention is used in winter, under the condition that the radiative cooling efficiency decreases by the fourth power as the ambient temperature decreases, while the infrared reflectivity remains relatively stable, the infrared reflective coating can effectively block the loss of indoor temperature and the intrusion of outdoor cold air temperature, thus achieving the effect of winter warmth. This is also reflected in the change of temperature difference value in the temperature difference test in the following embodiments.

[0131] In this invention, the three-dimensional structures described above can include one of the following: buildings, boxes, pipes, automobiles, photovoltaic modules, outdoor products, agricultural, livestock and aquaculture equipment, aerospace equipment, cold chain transportation equipment, outdoor containers, textile industry equipment, outdoor communication equipment, public utilities, cooling water systems, and energy-saving equipment. The two-dimensional planar structures described above can include one of the following: sheet-like or plate-like metals, plastics, rubber, concrete, cement, asphalt, paper, textiles, wood, ceramic tiles, glass, glass fiber, ceramic fiber, and organic synthetic materials.

[0132] Example

[0133] The present invention will be described in detail below through embodiments. These embodiments are intended to explain the invention and should not be construed as limiting it. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0134] <Preparation Example>

[0135] Some of the substances used in the preparation example are shown below: Dispersant: Sodium polycarboxylate dispersant (Nopco 5040); Wetting agent: Composite silicone special polyether wetting agent (Nopco 126); Defoamer: Nopco NXZ; Thickener: Hydroxyethyl cellulose (HEC), Shin-Etsu Chemical; Stabilizer: Aorun Chemical CS1; Modified barium metaborate / calcium metaborate (ratio 2-5:1): Purchased from Zibo Luchuan Chemical; Hollow glass microspheres / hollow ceramic microspheres (1:1) (hereinafter referred to as "hollow microspheres"): 3M IM16k; Graphite / graphene: ratio 3-8:1; Graphite is flake powder, 1500-6000 mesh; Graphene: about 3 layers; Coated aluminum powder / coated aluminum silver paste (hereinafter also referred to as aluminum powder / aluminum silver paste): Purchased from Shandong Yinjian.

[0136] Preparation Example 1 (Preparation of the first coating layer of the radiation cooling layer: layers 1-101)

[0137] 1-101: Preparation of TI1

[0138] (1) Add 16 parts by weight of deionized water to the disperser, and add 0.5 parts by weight of wetting agent, 1 part by weight of dispersant and 0.5 parts by weight of defoamer at a speed of 300-500 rpm, and stir for 5 minutes.

[0139] (2) Adjust the speed of the disperser to 800-1000 rpm, and then add 16 parts by mass of silica (particle size 0.5-10 micrometers), 8 parts by mass of hexagonal boron nitride (particle size 0.5-10 micrometers), 9 parts by mass of barium sulfate, 5 parts by mass of modified barium metaborate / calcium metaborate (particle size 1-15 micrometers), 10 parts by mass of quartz (particle size 1-10 micrometers) and 2 parts by mass of aerogel as fillers. Then add 0.2 parts by mass of fluorescent whitening agent OB and 0.2 parts by mass of strontium europium dysprosium aluminate as light conversion agents. After dispersing and mixing for 60 minutes, add 1.1 parts by mass of thickener.

[0140] (3) Based on the above steps, add 1 part by mass of stabilizer, 11 parts by mass of silica sol and 8 parts by mass of potassium silicate as inorganic binders, 10 parts by mass of styrene-acrylic emulsion as organic binders, and 0.5 parts by mass of defoamer, and mix and stir for 15 minutes.

[0141] (4) The mixture obtained above is filtered through a 150-mesh sieve to obtain a functional coating.

[0142] 1-101: Preparation of TI2

[0143] (1) Add 16.6 parts by weight of deionized water to the disperser, and add 0.6 parts by weight of wetting agent, 1.5 parts by weight of dispersant and 0.6 parts by weight of defoamer at a speed of 300-500 rpm, and stir for 5 minutes.

[0144] (2) Adjust the speed of the disperser to 800-1000 rpm, and then add 9 parts by mass of silica (particle size 0.5-10 micrometers), 8 parts by mass of hexagonal boron nitride (particle size 0.5-10 micrometers), 10 parts by mass of barium sulfate, 6 parts by mass of modified barium metaborate / calcium metaborate (particle size 1-15 micrometers) and 13 parts by mass of quartz (particle size 1-10 micrometers) as fillers, then add 0.3 parts by mass of fluorescent whitening agent OB and 0.3 parts by mass of zinc copper sulfide as light conversion agents. After dispersing and mixing for 60 minutes, add 1 part by mass of thickener.

[0145] (3) Based on the above steps, add 0.5 parts by weight of stabilizer, 12 parts by weight of silica sol and 10 parts by weight of potassium silicate as inorganic binders, 5 parts by weight of styrene-acrylic emulsion and 5 parts by weight of pure acrylic emulsion as organic binders, and 0.6 parts by weight of defoamer, and mix and stir for 15 minutes.

[0146] (4) The mixture obtained above is filtered through a 150-mesh sieve to obtain a functional coating.

[0147] Preparation Example 2 (Preparation of the second coating layer of the radiation cooling layer: layers 1-102)

[0148] 1-102: Preparation of R1

[0149] (1) Add 13 parts by weight of deionized water to the disperser, and add 0.5 parts by weight of wetting agent, 1.5 parts by weight of dispersant and 1.0 parts by weight of defoamer at a speed of 300-500 rpm, and stir for 5 minutes.

[0150] (2) Adjust the speed of the disperser to 800-1000 rpm, and then add the fillers other than hollow microspheres: 15 parts by weight of titanium dioxide (particle size 300nm±100), 20 parts by weight of heavy calcium carbonate powder (particle size 0.1-20 micrometers), 5 parts by weight of quartz (particle size 1-10 micrometers), 2 parts by weight of aerogel and 2 parts by weight of fumed silica. After dispersing and mixing for 60 minutes, adjust the speed to 300-500 rpm, add 6 parts by weight of hollow microspheres and 1 part by weight of thickener;

[0151] (3) Based on the above steps, add 0.5 parts by weight of stabilizer, 10 parts by weight of silica sol and 12 parts by weight of potassium silicate as inorganic binders, 10 parts by weight of styrene-acrylic emulsion and 10 parts by weight of pure acrylic emulsion as organic binders, and 0.5 parts by weight of defoamer, and mix and stir for 15 minutes.

[0152] (4) The mixture obtained above is filtered through a 150-300 mesh sieve to obtain a functional coating.

[0153] 1-102: Preparation of R2

[0154] (1) Add 13 parts by weight of deionized water to the disperser, and add 0.6 parts by weight of wetting agent, 1.5 parts by weight of dispersant and 0.6 parts by weight of defoamer at a speed of 300-500 rpm, and stir for 5 minutes.

[0155] (2) Adjust the speed of the disperser to 800-1000 rpm, and then add the fillers other than the hollow microspheres: 12 parts by weight of titanium dioxide (particle size 300nm±100), 18 parts by weight of heavy calcium carbonate powder (particle size 0.1-20 micrometers), 8 parts by weight of modified barium metaborate / calcium metaborate (particle size 1-15 micrometers), 2 parts by weight of aerogel and 8 parts by weight of calcium silicate (particle size 1-20 micrometers). After dispersing and mixing for 60 minutes, adjust the speed to 300-500 rpm, add 8 parts by weight of hollow microspheres and 1.2 parts by weight of thickener;

[0156] (3) Based on the above steps, add 0.5 parts by weight of stabilizer, 8 parts by weight of silica sol and 10 parts by weight of potassium silicate as inorganic binders, 8 parts by weight of styrene-acrylic emulsion as organic binders, and 0.6 parts by weight of defoamer, and mix and stir for 15 minutes.

[0157] (4) The mixture obtained above is filtered through a 150-300 mesh sieve to obtain a functional coating.

[0158] Preparation Example 3 (Preparation of Infrared Reflective Layer: 2)

[0159] 2: Preparation of IRR1

[0160] (1) Add 26.6 parts by weight of deionized water to the disperser, and add 0.3 parts by weight of wetting agent, 0.6 parts by weight of dispersant and 0.5 parts by weight of defoamer at a speed of 300-500 rpm, and stir for 5 minutes.

[0161] (2) Adjust the speed of the disperser to 800-1000 rpm, and then add 8 parts by mass of titanium dioxide (particle size 800nm±300), 1 part by mass of aerogel, 1 part by mass of fumed silica, 6 parts by mass of graphite / graphene and 17 parts by mass of aluminum powder (median particle size 50μm) as fillers. After dispersing and mixing for 60 minutes, add 1 part by mass of thickener.

[0162] (3) Based on the above steps, add 0.5 parts by weight of stabilizer, 12 parts by weight of silica sol and 15 parts by weight of potassium silicate as inorganic binders, 10 parts by weight of styrene-acrylic emulsion as organic binder, and 0.5 parts by weight of defoamer, and mix and stir for 15 minutes.

[0163] (4) The mixture obtained above is filtered through a 150-mesh sieve to obtain a functional coating.

[0164] 2: Preparation of IRR2

[0165] (1) Add 22.3 parts by weight of deionized water to the disperser, and add 0.5 parts by weight of wetting agent, 1 part by weight of dispersant and 0.6 parts by weight of defoamer at a speed of 300-500 rpm, and stir for 5 minutes.

[0166] (2) Adjust the speed of the disperser to 800-1000 rpm, and then add 9 parts by mass of titanium dioxide (particle size 800nm±300), 2 parts by mass of aerogel, 3 parts by mass of graphite / graphene and 20 parts by mass of aluminum powder (median particle size 20μm) as fillers. After dispersing and mixing for 60 minutes, add 0.5 parts by mass of thickener.

[0167] (3) Based on the above steps, add 0.5 parts by weight of stabilizer, 15 parts by weight of silica sol and 15 parts by weight of potassium silicate as inorganic binders, 5 parts by weight of styrene-acrylic emulsion and 5 parts by weight of pure acrylic emulsion as organic binders, and 0.6 parts by weight of defoamer, and mix and stir for 15 minutes.

[0168] (4) The mixture obtained above is filtered through a 150-mesh sieve to obtain a functional coating.

[0169] 2: IRR3 Preparation

[0170] (1) Add 23.8 parts by weight of deionized water to the disperser, and add 0.5 parts by weight of wetting agent, 1 part by weight of dispersant and 0.6 parts by weight of defoamer at a speed of 300-500 rpm, and stir for 5 minutes.

[0171] (2) Adjust the speed of the disperser to 800-1000 rpm, and then add 13 parts by mass of titanium dioxide (particle size of 300nm±100) and 18 parts by mass of aluminum silver paste (median particle size of 50μm) as fillers. After dispersing and mixing for 60 minutes, add 1 part by mass of thickener.

[0172] (3) Based on the above steps, add 0.5 parts by weight of stabilizer, 16 parts by weight of silica sol and 15 parts by weight of potassium silicate as inorganic binders, 10 parts by weight of pure acrylic emulsion as organic binder, and 0.6 parts by weight of defoamer, and mix and stir for 15 minutes.

[0173] (4) The mixture obtained above is filtered through a 150-mesh sieve to obtain a functional coating.

[0174] Example 1 (TI1+R1+IRR1)

[0175] By brushing, IRR1 (100 micrometers thick), R1 (250 micrometers thick), and TI1 (100 micrometers thick) are sequentially brushed from bottom to top onto a transparent PVC rigid sheet with a thickness of 0.4 mm as the substrate to obtain a radiation-cooled infrared reflective composite coating.

[0176] Example 2 (TI2+R2)

[0177] By brushing, R2 (250 micrometers) and TI2 (100 micrometers) are sequentially brushed from bottom to top onto a transparent PVC rigid sheet with a thickness of 0.4 mm as the substrate to obtain a radiation cooling composite coating.

[0178] Example 3 (IRR2)

[0179] An infrared reflective coating is obtained by brushing an IRR2 (100 micrometers) onto a transparent PVC rigid sheet with a thickness of 0.4 mm, which serves as the substrate.

[0180] Comparative Example 1 (TI1+IRR1)

[0181] By brushing, IRR1 (100 micrometers thick) and TI1 (100 micrometers thick) are sequentially brushed from bottom to top onto a transparent PVC rigid sheet with a thickness of 0.4 mm as the substrate to obtain a composite coating.

[0182] Comparative Example 2 (R1+IRR1)

[0183] By brushing, IRR1 (100 micrometers thick) and R1 (250 micrometers thick) are sequentially brushed from bottom to top onto a transparent PVC rigid sheet with a thickness of 0.4 mm as the substrate to obtain a radiation-cooled infrared reflective composite coating.

[0184] Comparative Example 3 (IRR3 small particle size aluminum powder aluminum silver paste + small particle size titanium dioxide)

[0185] An infrared reflective coating is obtained by brushing an IRR3 (100 micrometers) onto a transparent PVC rigid sheet with a thickness of 0.4 mm, which serves as the substrate.

[0186] Performance Testing

[0187] The coatings obtained in the above embodiments and comparative examples were subjected to the following tests.

[0188] The reflectance of the coating to the solar spectrum (0.3–2.5 μm) was measured using a UV-Vis-NIR spectrophotometer (PerkinElmer Lambda 950). Reflectance is the weighted average of the product of band energy and band reflectance. The test results are shown in Table 1.

[0189] The atmospheric window emissivity (8–14 μm) and mid-infrared (6–16 μm) reflectivity of the coating were measured using a Thermo Scientific Fourier transform infrared spectrometer (Model 6700) with an integrating sphere. The test results are shown in Table 1.

[0190] An IRIS CL-20 insulated box (20L, external dimensions 50cm*29cm*28cm, internal dimensions 43.2cm*22.6cm*20.5cm, constructed from PP resin / EPS foam / PS. The outer PS layer is white and wrapped with aluminum foil to reduce the influence of external absorption on the internal temperature) was used. The test sample was embedded in the original lid position of the foam box as a cover. Temperature probes from an Amber AT4208B multi-channel temperature meter were attached to the back of the test sample and the middle of the box (the side facing away from sunlight) to measure the surface and internal temperatures. Temperature data was recorded every minute, and the difference between the recorded data and the ambient temperature was calculated to obtain the average value. The test times and locations were as follows: September 30, 2023, 21:58 to October 1, 2023, 22:07, Tianchang City, Anhui Province; October 21, 2023, 00:00 to 06:00 (with indoor testing from 00:00 to 00:16 to achieve basically consistent temperatures at all measurement points, see figure), 06:00 to 24:00, and October 22, 2023, 00:00 to 06:00, Suzhou City, Jiangsu Province. The test results are shown in Table 2 and... Figures 7-10In addition, to simulate the effect of the radiation-cooling infrared-reflective composite coating of the present invention under near-winter conditions of sudden and rapid temperature drop, the following tests were conducted. The external dimensions and thickness of the test boxes (#1 and #2) made of white polystyrene foam were: length * width * height * thickness: 385 * 285 * 225 * 50 (mm). Box #1 had its inner surface coated with the infrared-reflective coating of Example 3, while box #2 had its inner surface coated with the infrared-reflective coating of Example 3 and its top outer surface coated with the radiation-cooling infrared-reflective composite coating of Example 1. The test was conducted from 17:00 on November 6, 2023 to 6:58 on November 7, 2023 in Suzhou City, Jiangsu Province. The test results are shown below. Figure 11 middle.

[0191] Table 1 Reflectivity and Emissivity Tests

[0192]

[0193] Table 2. Test results of surface temperature difference with ambient temperature and surface temperature difference with interior temperature.

[0194]

[0195] As shown in Table 1, Comparative Example 1 (without the second coating) and Comparative Example 2 (without the first coating) in the radiation-cooled infrared reflective composite coating cannot simultaneously achieve high solar reflectivity and atmospheric window emissivity. However, the composite coatings in Examples 1 and 2, which include both the first and second coatings, can achieve both high solar reflectivity and atmospheric window emissivity. The infrared reflectivity of Comparative Example 3, which uses small-particle-size aluminum powder, aluminum silver paste, and small-particle-size titanium dioxide to prepare the infrared reflective coating, is significantly lower than that of Example 3, which uses large-particle-size aluminum powder, aluminum silver paste, and large-particle-size titanium dioxide to prepare the infrared reflective coating.

[0196] From Table 2 and Figure 7-10 As can be seen, comparing Example 1 (radiative cooling infrared reflective coating) and Example 2 (radiative cooling coating), the 24-hour temperature difference between the surface and interior of the chamber is significantly smaller in the former than in the latter. The coating containing the infrared reflective layer effectively reflects and blocks the temperature difference between the inside and outside of the chamber, thus playing a role in temperature regulation. Furthermore, the surface temperature and interior temperature of the chamber are both lower in the former than in the latter, resulting in a better cooling effect in summer. Comparing the temperature difference results of Examples 1 and 2 with those of Example 3 shows that the infrared reflective coating of Example 3 has a better reflective heat preservation effect.

[0197] What is particularly surprising is that, as shown in Table 2 and Figure 8 and Figure 10As shown, using the single-layer infrared reflective coating of Example 3, during two identical nighttime periods (0:00 to 6:00), the internal temperature of the infrared reflective coating, given the material's certain atmospheric window emissivity, approached or even exceeded the ambient temperature in the latter half of the night. This demonstrates that even at lower temperatures, the infrared reflective coating of this invention exhibits a certain effect of photon environmental energy recovery, thereby raising the temperature inside the chamber and further promoting the effect of being warm in winter and cool in summer. For the mechanism of photon recovery using metals such as aluminum, please refer to the aforementioned <Second Aspect>.

[0198] In the simulated winter test, the weather conditions were as follows: Figure 11 As shown (test location: Suzhou City, Jiangsu Province). Specifically, on November 5th, the daytime was sunny with a high of 30℃. It became cloudy to overcast in the evening, with rain and a drop in temperature starting at 6 PM, gradually ending before 10 PM, and the weather turning cloudy again. On November 6th, the daytime was sunny with strong winds and continuous cold air intrusion. The daytime high was 18℃. That night, the temperature gradually decreased. By 4:48 AM on November 7th, the ambient temperature had dropped to 9.1℃. These weather changes effectively illustrate the nighttime and winter temperature drops, providing valuable meteorological information. Figure 11 It can be seen that from 17:00 on November 6th, the ambient temperature was significantly higher than the internal and external temperatures of boxes #1 and #2. However, from approximately 23:00 onwards until sunrise at 6:30 on November 7th, the internal temperature of boxes #1 and #2, coated with an infrared reflective layer, remained higher than the ambient temperature, demonstrating a good infrared reflection and insulation effect when the external ambient temperature rapidly decreased. Meanwhile, although the surface temperature of box #2, coated with a radiative cooling coating, rapidly decreased and fell below the ambient temperature as atmospheric transparency increased at night, the impact on the internal temperature of box #2 was not significant (see the temperature trend curve in the left figure and the average temperatures in the table at the bottom left of the figure).

[0199] The above results demonstrate that the bidirectional reflective blocking of the infrared reflective coating plays a dual role. On one hand, the infrared reflective coating can reflect heat from within the three-dimensional enclosure back to itself, thus maintaining warmth; on the other hand, it blocks the emission of the radiative cooling coating. During the day, the radiative cooling coating emits heat into the sky through an "atmospheric window" and also transfers heat (cooling) into the interior of the three-dimensional enclosure. During the day, as the ambient temperature rises, the radiative cooling capacity increases, and its cooling effect is conducted into the three-dimensional enclosure through the coating. The temperature inside the structure decreases relative to the ambient temperature, and the presence of the infrared reflective coating effectively retains this cooling effect within the three-dimensional enclosure. Therefore, based on the principles of the radiative cooling mechanism and the infrared reflection mechanism, as well as actual tests, it can be concluded that the bidirectional reflective blocking and photon recovery effect of the infrared reflective coating are compatible with the radiative cooling coating, adapting to temperature changes during the day and night, and summer and winter. The radiative cooling infrared reflective composite coating benefits from heat reflection and the blocking of heat emission; actual temperature test comparisons show that the effect is better at night than during the day.

Claims

1. An inorganic composite photonic coating, characterized in that, The inorganic composite photonic coating includes a radiation-cooling functional coating, or a composite coating consisting of the radiation-cooling functional coating and an infrared reflection functional coating arranged from top to bottom. The radiation cooling functional coating includes a first coating and a second coating. The first coating is used to convert a portion of the ultraviolet light in sunlight into visible light, to emit heat through the atmospheric window in a way that enhances infrared radiation within the maximum wavelength range of 8-14 μm of the atmospheric window, and to partially or completely reflect ultraviolet light and / or visible light and / or near-infrared light in the 0.3-2.5 μm wavelength range of sunlight. The second coating is used to enhance the reflection of ultraviolet light and / or visible light and / or near-infrared light in the 0.3-2.5 μm wavelength range of sunlight. The infrared reflective coating is used to reflect and block infrared light, and the infrared reflective coating includes inorganic pigments and fillers with reflective and blocking functions. The inorganic pigments and fillers with reflective barrier function include one or more of the following: coated aluminum powder or coated aluminum silver paste with a particle size of 10-60μm, titanium dioxide with a particle size of 400-1200nm, and graphite / graphene.

2. The inorganic composite photonic coating according to claim 1, wherein, The median particle size of the coated aluminum powder or coated aluminum silver paste is 40-60 μm, and the particle size of the titanium dioxide is 600-1000 nm.

3. The inorganic composite photonic coating according to claim 1, wherein, The thickness of the radiation cooling functional coating is 200-800 μm; and / or, the thickness of the infrared reflection functional coating is 50-200 μm; And / or, the thickness of the first coating is 100-500 μm; and / or, the thickness of the second coating is 100-500 μm.

4. The inorganic composite photonic coating according to claim 1, wherein, The first coating comprises a UV-converting agent, inorganic pigments and fillers that act as atmospheric window particles, and a first binder; and / or, The second coating comprises inorganic pigments and fillers forming a refractive index gradient and a second binder; and / or, The infrared reflective coating also includes a third adhesive.

5. The inorganic composite photonic coating according to claim 4, wherein, The ultraviolet light conversion agent includes one or more of the following: fluorescent whitening agent, ultramarine, zinc copper sulfide, and europium dysprosium aluminate; and / or The inorganic pigments and fillers used as atmospheric window emission particles include one or more of silicon dioxide, hexagonal boron nitride, barium sulfate, modified barium metaborate, and modified calcium metaborate, wherein the particle size of each of silicon dioxide, hexagonal boron nitride, barium sulfate, modified barium metaborate, and modified calcium metaborate is 0.1-20 μm; and / or The inorganic pigments and fillers forming the refractive index gradient include one or more of the following: titanium dioxide with a particle size of 200-400 nm, hollow glass microspheres with a particle size of 1-30 μm, hollow ceramic microspheres with a particle size of 1-30 μm, aerogel, fumed silica, calcium silicate, calcium phosphate, heavy calcium carbonate powder, modified barium metaborate, and modified calcium metaborate, wherein the particle size of calcium silicate, calcium phosphate, heavy calcium carbonate powder, modified barium metaborate, and modified calcium metaborate is 0.1-20 μm.

6. The inorganic composite photonic coating according to claim 4, wherein, The first adhesive, the second adhesive, and the third adhesive each comprise one or more of inorganic silicates, liquid silica sol, and organic emulsions. When an organic emulsion is included, the solid content of the organic emulsion does not exceed 8% by weight relative to the total solid content of the entire inorganic composite photonic coating. The first adhesive, the second adhesive, and the third adhesive may be the same as or different from each other.

7. The inorganic composite photonic coating according to claim 4, wherein, In the first coating, the content of the ultraviolet light-converting agent is 0.2~2.0% by mass relative to the mass of the first coating; the content of the inorganic pigments and fillers that serve as atmospheric window emitting particles is 30~70% by mass relative to the mass of the first coating; the content of the first binder is 30~70% by mass relative to the mass of the first coating; and / or In the second coating, the content of the inorganic pigments and fillers forming the refractive index gradient is 30-70% by mass relative to the mass of the second coating, and the content of the second binder is 30-70% by mass relative to the mass of the second coating. and / or In the infrared reflective functional coating, the content of the inorganic pigments and fillers with reflective blocking function is 30-60% by mass relative to the mass of the infrared reflective functional coating, and the content of the third binder is 30-70% by mass relative to the mass of the infrared reflective functional coating.

8. The inorganic composite photonic coating according to any one of claims 1 to 7, wherein the coated aluminum powder and the coated aluminum silver paste are each coated with silicon or stearic acid.

9. An application of the inorganic composite photonic coating according to any one of claims 1 to 8, characterized in that, When the inorganic composite photonic coating includes a radiation-cooling functional coating, the inorganic composite photonic coating is applied to the exterior or outer side of a three-dimensional structure or a two-dimensional planar structure. When the inorganic composite photonic coating includes an infrared-reflective coating, the inorganic composite photonic coating is applied to the interior or inner side and / or exterior or outer side of a three-dimensional structure or a two-dimensional planar structure. When the inorganic composite photonic coating comprises both a radiation-cooling functional coating and an infrared-reflecting functional coating arranged from top to bottom, the inorganic composite photonic coating is applied to the exterior or outer side of a three-dimensional structure or a two-dimensional planar structure. The three-dimensional structure includes one of the following: building, automobile, and photovoltaic module. The two-dimensional planar structure includes one of the following: sheet-like or plate-like metal, concrete, asphalt, paper, textiles, wood, ceramic tile, glass, glass fiber, and ceramic fiber.

10. The application according to claim 9, wherein the two-dimensional planar structure comprises one of sheet-like or plate-like plastic and rubber.

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