High weatherability solar heat reflecting coating and preparation and use method thereof

Abstract

This invention provides a high-weather-resistant solar heat-reflective coating and its preparation and application methods. The coating system consists of a low-surface-energy long-chain silane coupling agent, a low-surface-energy solvent, and functional pigment and filler nanoparticles. The preparation process is simple and mild, requiring no vacuum equipment or complex processes, effectively solving problems in existing technologies such as insufficient solar reflectivity, poor long-term weather resistance, and susceptibility to surface contamination. The long-chain silane coupling agent is selected from perfluorooctyltrichlorosilane, perfluoroquinolyltrichlorosilane, perfluorooctyltriethoxysilane, polydimethylsiloxane, or hexadecyltrichlorosilane; the low-surface-energy solution is selected from ethanol, propanol, or acetone; the pigment and filler nanoparticles include titanium dioxide, barium sulfate, aluminum oxide, calcium carbonate, silicon dioxide, or zinc oxide, with a particle size ranging from 10 nm to 5 μm. The volume ratio of each component is pigment and filler nanoparticles: low-surface-energy solution: long-chain silane coupling agent = 1–5: 5–10: 0.1–0.3.

Description

Technical Field

[0001] This invention relates to the field of functional coating materials, specifically to a highly weather-resistant solar heat-reflective coating and its preparation and application methods. Background Technology

[0002] Global climate change has led to more frequent extreme heat events, posing a serious challenge to building energy conservation and indoor thermal comfort management. Active cooling technologies, such as air conditioning, consume large amounts of electricity, exacerbating energy demand and greenhouse gas emissions. Therefore, developing passive cooling technologies that require no additional energy consumption is of great significance for building energy conservation, emission reduction, and sustainable development.

[0003] Against this backdrop, passive technologies for indoor cooling that leverage the inherent optical properties of materials have garnered significant attention. The core principle is to endow materials with two optical properties: first, extremely high reflectivity in the solar spectrum (0.3-2.5 micrometers) to minimize the absorption of solar radiation; and second, high thermal emissivity in specific mid-infrared bands (especially the atmospheric window band) to promote heat dissipation to external cold sources. Based on this principle, researchers have developed various optical metamaterials and thin films. For example, by depositing precise multilayer film structures on substrates, they have achieved excellent solar reflection and infrared radiation properties, demonstrating the potential for daytime cooling. However, these fabrication processes typically rely on complex and expensive vacuum deposition equipment, with demanding processing conditions, making large-scale coating on complex shapes or large-area building surfaces difficult, thus limiting their practical applications.

[0004] Coatings, as a convenient application method, are considered an ideal solution for achieving large-scale functional coverage of building surfaces. Currently, relevant functional coatings are mainly based on two systems: one is a composite paint made by dispersing high-refractive-index nanoparticles in polymer resin; the other is to enhance light scattering by constructing porous polymers. However, these existing systems have significant limitations: First, the refractive index contrast between nanoparticles and the polymer matrix, or between the solid and phases within the porous structure, is limited, resulting in insufficient scattering intensity of sunlight and an overall need to improve reflectivity; second, organic polymer substrates are susceptible to aging, yellowing, and chalking under long-term outdoor exposure due to factors such as ultraviolet radiation, temperature, and humidity, leading to performance degradation; third, coating surface energy is usually high, making it easy to adsorb dust and pollutants. Once dirty, its reflectivity will significantly decrease, and it is difficult to clean, resulting in high maintenance costs.

[0005] Therefore, developing a new type of solar heat reflective coating that combines high solar reflectivity, excellent long-term weather resistance and self-cleaning ability, while also having a simple preparation process and convenient construction, has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This invention provides a high weather-resistant solar heat reflective coating and its preparation and application method. The preparation process is simple and easy to control, and does not require any additional vacuum equipment or complex preparation conditions. It effectively solves the problems of insufficient solar reflectivity, poor long-term weather resistance of materials, and easy contamination of the surface in the prior art.

[0007] The technical problem to be solved by the present invention is achieved through the following technical solution: This invention provides a high weather-resistant solar heat-reflective coating comprising a low surface energy long-chain silane coupling agent, a low surface energy solvent, and functional pigment and filler nanoparticles.

[0008] Preferably, the long-chain silane coupling agent is selected from one of perfluorooctyltrichlorosilane, perfluoroquinolyltrichlorosilane, perfluorooctyltriethoxysilane, polydimethylsiloxane, or hexadecyltrichlorosilane.

[0009] Preferably, the low surface energy solvent is selected from ethanol, propanol, or acetone.

[0010] Preferably, the pigment and filler nanoparticles are titanium dioxide, barium sulfate, aluminum oxide, calcium carbonate, silicon dioxide, or zinc oxide.

[0011] Preferably, the particle size range of the pigment and filler nanoparticles is 10 nm to 5 μm.

[0012] Preferably, the volume ratio of the pigment / filler nanoparticles, the low surface energy solvent, and the long-chain silane coupling agent is 1-5: 5-10: 0.1-0.3.

[0013] A method for preparing the aforementioned high weather-resistant solar heat-reflective coating includes the following steps: S1. Disperse the pigment and filler nanoparticles in a low surface energy solvent and stir thoroughly; S2. Add a long-chain silane coupling agent to the dispersion obtained in step S1, mix well, and prepare a coating.

[0014] Preferably, step S1 is further specified as follows: adding pigment and filler nanoparticles into a low surface energy solvent and magnetically stirring for 1-3 hours to form a uniform and stable dispersion.

[0015] Preferably, step S2 is further specified as follows: adding a long-chain silane coupling agent to the dispersion and stirring magnetically for 1-5 hours to obtain the coating.

[0016] A method for using the aforementioned high weather-resistant solar heat-reflective coating is characterized by: coating an adhesive layer on the substrate surface, then applying the coating onto the adhesive layer, and after the solvent evaporates, forming a solar heat-reflective coating.

[0017] Preferably, after the coating is applied to the adhesive, it is allowed to dry naturally at room temperature for 6-24 hours to form a coating layer.

[0018] Preferably, the specific method of application is spraying, dripping, brushing, or rolling.

[0019] Preferably, the adhesive is a solid double-sided tape, a liquid spray adhesive, or a two-component reactive adhesive.

[0020] Preferably, the thickness of the solar heat reflective coating is 80-150 μm.

[0021] The beneficial effects of this invention are as follows: 1. Simple preparation and wide applicability: The preparation process of this invention is simple, the conditions are mild, and no complex equipment is required. The resulting coating can be firmly adhered to various substrate surfaces through an adhesive interlayer, making it highly versatile.

[0022] 2. Low cost and readily available raw materials: Preparation requires no polymer matrix, and the main raw materials are low cost and readily available. Optical properties can be optimized by controlling the particle size and type of nanoparticles.

[0023] 3. Clear optical mechanism and excellent performance: The porous structure formed after the coating film is formed utilizes the huge refractive index difference between nanoparticles and air to achieve extremely high solar reflectivity through a strong backscattering effect.

[0024] 4. Low surface energy and good self-cleaning properties: Long-chain silane coupling agents give the coating extremely low surface energy, so pollutants do not adhere firmly and can be easily removed by natural conditions such as rain and wind, keeping the surface clean and highly reflective.

[0025] 5. Inorganic main body with excellent weather resistance: The coating is based on inorganic nanoparticles and does not contain easily aged organic polymers. Therefore, it has excellent resistance to ultraviolet rays and high temperature oxidation. It is not easy to yellow or degrade with long-term use and has high stability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the coating formed by the solar heat reflective coating with long-term stability of the present invention; Figure 2 These are scanning electron microscope images of the coating formed by the solar heat reflective coating of the present invention, magnified 10,000 times and 40,000 times. Figure 3 The spectral properties (reflectivity of the solar spectrum and emissivity of the atmospheric transparency window) of the coating formed by the solar heat reflective coating with long-term stability of the present invention are described. Figure 4 The superhydrophobic properties of the coating formed by the solar heat reflective coating of the present invention have long-lasting stability.

[0027] Figure 5 This is a schematic diagram of the dynamic change process of the coating surface formed by the solar heat reflective coating with long-term stability of the present invention being cleaned by water droplets. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0029] Figure 1 This is a schematic diagram illustrating the formation of the high-weather-resistant solar heat-reflective coating in this embodiment. A layer of transparent adhesive is first coated onto the substrate to enhance adhesion between the coating and the substrate. Subsequently, long-chain silane coupling agent and pigment / filler nanoparticles are added to a low surface energy solution and magnetically stirred to prepare a uniformly dispersed suspension. Finally, this coating-like solution is applied to the adhesive layer on the substrate by spraying, dripping, or dipping. After the solvent evaporates naturally, a solid solar heat-reflective coating is obtained.

[0030] The preparation method of the present invention will be described in detail below with reference to specific embodiments. Example

[0031] A method for preparing a highly weather-resistant solar heat-reflective coating includes the following steps: (1) Apply a layer of double-sided tape to the surface of a solid substrate, with one side of the double-sided tape attached to the solid substrate and the other side exposed to the air for coating. (2) Perfluorooctyltrichlorosilane and titanium dioxide nanoparticles with a particle size of 20 nm - 1 μm were added to anhydrous ethanol and magnetically stirred at 25°C for 5 hours to prepare a dispersion suspension solution with a mass ratio of perfluorooctyltrichlorosilane, titanium dioxide and ethanol of 1:15:100. (3) The coating solution prepared in step (2) is added to the exposed adhesive surface of the double-sided tape prepared in step (1) by drop application (amount is 0.3 ml / cm²). After the solvent evaporates for 3 hours, a solar heat reflective coating with a thickness of about 150 μm is obtained. Example

[0032] A method for preparing a highly weather-resistant solar heat-reflective coating includes the following steps: (1) Spray a layer of liquid adhesive onto the surface of the solid substrate in advance, leaving the adhesive-adhesive surface exposed to the air for coating; (2) Perfluoroquinoline trichlorosilane and barium sulfate nanoparticles with a particle size of 50 nm - 2 μm were added to anhydrous ethanol and magnetically stirred at 25°C for 5 hours to prepare a dispersion suspension solution with a mass ratio of perfluoroquinoline trichlorosilane, barium sulfate and ethanol of 1:20:100. (3) The coating solution prepared in step (2) is added to the adhesive surface exposed by the spray adhesive prepared in step (1) by drop application (amount is 0.2 ml / cm²). After the solvent evaporates for 5 hours, a solar heat reflective coating with a thickness of about 100 μm is obtained. Example

[0033] A method for preparing a highly weather-resistant solar heat-reflective coating includes the following steps: (1) On the surface of a solid substrate, mix A glue (epoxy resin) and B glue (hardener) in a ratio of approximately 2:1 by visual inspection and apply the mixture. The adhesive side is exposed to the air and left to be coated with paint. (2) Perfluorooctyltriethoxysilane and aluminum oxide nanoparticles with a particle size of 10 nm - 50 nm were added to isopropanol and magnetically stirred at 25 °C for 5 hours to prepare a dispersion suspension solution with a mass ratio of perfluorooctyltriethoxysilane, aluminum oxide and isopropanol of 1:30:100. (3) The coating solution prepared in step (2) is added to the exposed adhesive surface of the AB glue prepared in step (1) by drop application (amount is 0.15 ml / cm²). After the solvent evaporates for 5 hours, a solar heat reflective coating with a thickness of about 80 μm is obtained. Example

[0034] A method for preparing a highly weather-resistant solar heat-reflective coating includes the following steps: (1) Apply a layer of double-sided tape to the surface of a solid substrate, with one side of the double-sided tape attached to the solid substrate and the other side exposed to the air for coating. (2) Polydimethylsiloxane and calcium carbonate nanoparticles with a particle size of 100 nm - 1000 nm were added to n-propanol and magnetically stirred at 25°C for 5 hours to prepare a dispersion suspension solution with a mass ratio of polydimethylsiloxane, calcium carbonate and n-propanol of 1:15:100. (3) The coating solution prepared in step (2) is added to the exposed adhesive surface of the double-sided tape prepared in step (1) by drop application (amount is 0.2 ml / cm²). After the solvent evaporates for 5 hours, a solar heat reflective coating with a thickness of about 100 μm is obtained. Example

[0035] A method for preparing a highly weather-resistant solar heat-reflective coating includes the following steps: (1) Spray a layer of liquid adhesive onto the surface of the solid substrate in advance, leaving the adhesive-adhesive surface exposed to the air for coating; (2) Add hexadecyltrichlorosilane and zinc oxide nanoparticles with a particle size of 10 nm - 500 nm to anhydrous acetone and stir magnetically at 25°C for 5 hours to prepare a dispersion suspension solution with a mass ratio of hexadecyltrichlorosilane, zinc oxide and anhydrous acetone of 1:20:100. (3) The coating solution prepared in step (2) is added to the adhesive surface exposed by the spray adhesive prepared in step (1) by drop application (amount is 0.2 ml / cm²). After the solvent evaporates for 5 hours, a solar heat reflective coating with a thickness of about 100 μm is obtained. Example

[0036] A method for preparing a highly weather-resistant solar heat-reflective coating includes the following steps: (1) Spray a layer of liquid adhesive onto the surface of the solid substrate in advance, leaving the adhesive-adhesive surface exposed to the air for coating; (2) Perfluorooctyltrichlorosilane and silica nanoparticles with a particle size of 10 nm to 5 μm were added to anhydrous acetone and magnetically stirred at 25°C for 5 hours to prepare a dispersion suspension solution with a mass ratio of perfluorooctyltrichlorosilane, silica and anhydrous acetone of 1:10:100. (3) The coating solution prepared in step (2) is added to the adhesive surface exposed by the spray adhesive prepared in step (1) by drop application (amount is 0.2 ml / cm²). After the solvent evaporates for 5 hours, a solar heat reflective coating with a thickness of about 100 μm is obtained.

[0037] The structure and performance of the solar heat reflective coating of the present invention will be described below with reference to the accompanying drawings.

[0038] Figure 2 The images show scanning electron microscope (SEM) images of the solar heat-reflective coating of this invention, magnified 10,000 times and 40,000 times, respectively. As can be seen from the images, primary nanoparticles with a particle size of 20 nm - 1 μm self-assemble into a micro / nano composite porous structure with a multi-scale distribution. The surface of each nanoparticle is fully modified with long-chain silanes.

[0039] Figure 3 The spectral properties (reflectivity of the solar spectrum and emissivity of the atmospheric window band) of the coating of the present invention are shown.

[0040] Figure 4 The superhydrophobic properties of the solar heat-reflective coating were demonstrated.

[0041] Figure 5The dynamic process of the coating surface being cleaned by water droplets after being contaminated with dust is presented. It can be seen that the water droplets effectively cleaned the dust on the coating surface, and the coating still maintained its highly reflective appearance.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0043] Because of the adoption of the above technical solution, the present invention has the following advantages: Without polymer matrix materials, the inorganic nanoparticle phase has a greater difference in refractive index with the air phase, resulting in higher scattering efficiency and high solar reflectivity. After the surface of nanoparticles is modified with long-chain silanes, the resulting coating has high emissivity in the atmospheric window band, which is beneficial for heat dissipation. It has strong anti-pollution ability, low surface energy, and can effectively utilize the effects of rainwater, fog, wind and other natural environmental factors to achieve self-cleaning function; With inorganic nanoparticles as the main structure, it is resistant to high temperature and UV aging, and can be used stably in complex outdoor environments for a long time.

Claims

1. A high weather-resistant solar heat-reflective coating, characterized in that, This includes low surface energy long-chain silane coupling agents, low surface energy solvents, and functional pigment and filler nanoparticles.

2. The high weather-resistant solar heat-reflective coating according to claim 1, characterized in that, The long-chain silane coupling agent is selected from one of perfluorooctyltrichlorosilane, perfluoroquinolyltrichlorosilane, perfluorooctyltriethoxysilane, polydimethylsiloxane, or hexadecyltrichlorosilane.

3. The high weather-resistant solar heat-reflective coating according to claim 1, characterized in that, The low surface energy solvent is selected from ethanol, propanol, or acetone.

4. The high weather-resistant solar heat-reflective coating according to claim 1, characterized in that, The pigment and filler nanoparticles are titanium dioxide, barium sulfate, aluminum oxide, calcium carbonate, silicon dioxide, or zinc oxide.

5. The high weather-resistant solar heat-reflective coating according to claim 1, characterized in that, The particle size range of the pigment and filler nanoparticles is 10 nm to 5 μm.

6. The high weather-resistant solar heat-reflective coating according to claim 1, characterized in that, The volume ratio of each component is pigment / filler nanoparticles: low surface energy solvent: long-chain silane coupling agent = 1-5 : 5-10 : 0.1-0.

3.

7. A method for preparing a high weather-resistant solar heat-reflective coating as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Disperse the pigment and filler nanoparticles in a low surface energy solvent and stir thoroughly to form a uniform dispersion; S2. Add a long-chain silane coupling agent to the dispersion and continue stirring to mix evenly to obtain the coating.

8. A method of using a high weather-resistant solar heat-reflective coating as described in any one of claims 1 to 6, characterized in that, The process includes: coating an adhesive layer onto a substrate surface, then applying the coating onto the adhesive layer, and after the solvent evaporates, forming a solar heat-reflective coating.

9. The method of use according to claim 8, characterized in that, The adhesive is a solid double-sided tape, a liquid spray adhesive, or a two-component reactive adhesive.

10. The method of use according to claim 8, characterized in that, The dried thickness of the solar heat reflective coating is 80-150 μm.

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