Weather-resistant optical functional coating nanoparticles, and preparation method and application thereof

Abstract

The application provides a kind of weather-resistant optical functional coating nanoparticles and its preparation method and application, belong to the field of coating.The nanoparticles include: inner core, the inner core is near-infrared reflective material;The near-infrared reflective material uses metal oxide nanoparticles with near-infrared reflective function;First wrapping layer, the first wrapping layer is silica intermediate layer, which wraps the inner core;Second wrapping layer, the second wrapping layer is alumina passivation layer, which wraps the silica intermediate layer.The nanoparticles are used as the functional filler of weather-resistant optical functional coating.The application provides a kind of core-shell structure nanoparticles, by introducing specific passivation layer, while retaining the near-infrared reflective function of inner core material, fundamentally eliminate its photo-catalytic damage to organic matrix, so as to obtain long-acting stability, high visible light transmittance, excellent spectral selectivity and weather-resistant coating.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, and specifically relates to a weather-resistant optical functional coating nanoparticle, its preparation method, and its application. Background Technology

[0002] Spectral-selective optical functional coatings (such as near-infrared reflective heat-insulating coatings and photovoltaic module gain coatings) have broad application prospects in building energy conservation, green transportation, and new energy fields. The core function of these coatings typically relies on inorganic near-infrared reflective nanomaterials such as antimony-doped tin oxide and indium tin oxide. However, these materials generate photogenerated electron-hole pairs under sunlight, especially in the ultraviolet band. The holes possess extremely strong oxidizing capabilities, initiating irreversible photocatalytic oxidation and degradation reactions in the surrounding organic resin matrix. Beyond the building and transportation sectors, the casings of industrial equipment such as outdoor cabinets, 5G base stations, and new energy charging facilities also face severe outdoor aging problems. Existing coatings struggle to balance long-term weather resistance with functional integration. This fundamental contradiction leads to coatings being prone to yellowing, chalking, loss of adhesion, and functional degradation in harsh outdoor environments, resulting in a service life far shorter than the substrate (such as the 25-year requirement for photovoltaic modules), becoming a key technological bottleneck restricting their large-scale application.

[0003] To improve the dispersibility and optical compatibility of functional fillers, existing technologies often employ silica to coat the surface of nanoparticles. For example, patent application CN120059581A discloses a method for preparing hollow double-shell nanofillers and its application in the preparation of transparent heat-insulating coatings. The SiO2 shell primarily functions to regulate refractive index, improve dispersion, and utilize the photocatalytic properties of TiO2 to achieve superhydrophilicity. However, conventional SiO2 coatings are typically porous or amorphous, failing to form a completely dense physicochemical barrier. They cannot effectively block the penetration of small molecules such as water vapor and oxygen, nor can they quench or isolate reactive oxygen species generated by the near-infrared reflective material in the core. Therefore, coatings using only SiO2 coatings offer limited improvement in long-term weather resistance, and the problem of photocatalytic degradation of the core remains unresolved. Summary of the Invention

[0004] In view of this, the present invention provides weather-resistant optical functional coating nanoparticles, their preparation method and application, aiming to solve at least one technical problem in the background art.

[0005] This invention is implemented as follows:

[0006] The first aspect of this invention provides weather-resistant optical functional coating nanoparticles, the nanoparticles comprising:

[0007] The core is a near-infrared reflective material; the near-infrared reflective material is made of metal oxide nanoparticles with near-infrared reflective function.

[0008] The first encapsulation layer is a silicon dioxide intermediate layer that encapsulates the core.

[0009] The second encapsulation layer is an alumina passivation layer that encapsulates the silicon dioxide intermediate layer.

[0010] Furthermore, the near-infrared reflective material is selected from at least one of antimony-doped tin dioxide, indium tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, gallium-doped zinc oxide, molybdenum-doped tungsten oxide, titanium-doped tungsten oxide, or tungsten oxide.

[0011] Furthermore, the near-infrared reflective material is selected from antimony-doped tin dioxide, indium tin oxide, or titanium-doped tungsten oxide.

[0012] Furthermore, the thickness of the silicon dioxide intermediate layer is 10nm-25nm.

[0013] Furthermore, the thickness of the alumina passivation layer is 1nm-5nm.

[0014] A second aspect of this invention provides a method for preparing weather-resistant optical functional coating nanoparticles, the method comprising the following steps:

[0015] Provide near-infrared reflective material as the core;

[0016] The core surface is coated with silicon dioxide to form a core-shell intermediate with a silicon dioxide intermediate layer;

[0017] Alumina is deposited on the surface of the silica intermediate layer of the core-shell intermediate to form the alumina passivation layer.

[0018] Furthermore, the method for coating the core surface with silica is the sol-gel method, and the silica source is tetraethyl orthosilicate.

[0019] Furthermore, the method for depositing aluminum oxide on the surface of the silica intermediate layer of the core-shell intermediate is atomic layer deposition; the aluminum source is trimethylaluminum, and the deposition temperature is 180℃-220℃.

[0020] A third aspect of the present invention provides the application of the above-mentioned weather-resistant optical functional coating nanoparticles, wherein the nanoparticles serve as functional fillers for the weather-resistant optical functional coating; the coating is applied to the surface of an outdoor product that is exposed to the elements for a long period of time.

[0021] A fourth aspect of the present invention provides a weather-resistant optical functional coating, the weather-resistant optical functional coating comprising a resin matrix and a functional filler; the functional filler is the weather-resistant optical functional coating nanoparticles.

[0022] Furthermore, the mass fraction of the nanoparticles in the coating is 0.5%-12%.

[0023] The fifth aspect of this invention provides the application of the aforementioned weather-resistant optical functional coating in vehicle housings, building components, photovoltaic modules, or industrial equipment housings. The vehicle housing is a car body or automotive parts; the building component is architectural glass or a metal curtain wall panel; and the photovoltaic module is a photovoltaic glass cover or back panel.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention solves the problem of the contradiction between high performance (near-infrared reflection) and high reliability (inertness to organic phase) of materials by using a core-shell-shell structural design, especially the outermost functional Al2O3 passivation layer, thereby unifying the high activity of functional fillers with the long life of coatings.

[0026] 2. The weather-resistant optical functional coating prepared using the nanoparticles of this invention (such as MO@SiO2@Al2O3) exhibits stability far exceeding expectations in accelerated UV aging tests. After several years of enhanced UV irradiation equivalent to outdoor exposure, the visible light transmittance of the coating remains greater than 95%, and the yellowing index changes very little. In contrast, coatings using similar particles without Al2O3 coating (such as ATO@SiO2) or directly using raw ATO powder show a significant decrease in visible light transmittance retention and exhibit significant yellowing. This directly verifies the decisive role of the Al2O3 passivation layer in inhibiting photocatalytic degradation and protecting the resin matrix.

[0027] 3. The passivation layer of this invention ensures the long-term stable operation of the core function, and the coating maintains its spectral selectivity throughout its entire life cycle. Combining this particle with superhydrophobic technology, a self-cleaning and heat-insulating integrated coating can be prepared. This coating not only reduces dust adhesion through its superhydrophobic surface (solving dust accumulation loss), but also continuously reduces the module's operating temperature through persistent and effective near-infrared reflection (solving temperature rise loss). The synergy of these two aspects enables a stable and long-term improvement in the overall power generation efficiency of the module.

[0028] 4. The last two steps of the SiO2 coating onto Al2O3 deposition process of this invention are highly versatile for different core materials. The process parameters are clear, the repeatability is good, and it is highly compatible with existing wet chemical and vapor deposition equipment for nanomaterials, making it easy to transition to pilot-scale and large-scale production. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the weather-resistant optical functional coating nanoparticles of the present invention;

[0030] Figure 2 Typical transmission electron microscope images of ATO@SiO2@Al2O3 nanoparticles prepared in Example 1;

[0031] Figure 3 The bar chart shows the Tvis retention rate of coatings prepared from different samples of Example 1, Comparative Examples 1 to 4 after UV accelerated aging. Detailed Implementation

[0032] 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 merely illustrative and not intended to limit the invention.

[0033] like Figure 1 As shown, a weather-resistant optical functional coating nanoparticle comprises:

[0034] (1) Core 101, wherein the core is a near-infrared reflective material, which is made of metal oxide nanoparticles with near-infrared reflective function;

[0035] (2) First encapsulation layer 102, wherein the first encapsulation layer is a silicon dioxide intermediate layer that encapsulates the core;

[0036] (3) Second encapsulation layer 103, the second encapsulation layer is an aluminum oxide passivation layer, which encapsulates the silicon dioxide intermediate layer.

[0037] The core 101, the first encapsulation layer 102, and the second encapsulation layer 103 constitute the core-shell structure of the nanoparticle.

[0038] The near-infrared reflective material is selected from at least one of antimony-doped tin dioxide (ATO), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), fluorine-doped tin oxide (FTO), gallium-doped zinc oxide (GZO), molybdenum-doped tungsten oxide, titanium-doped tungsten oxide, or tungsten oxide (WO3); preferably antimony-doped tin dioxide, indium tin oxide, or titanium-doped tungsten oxide.

[0039] In specific implementations, the thickness of the silicon dioxide intermediate layer is 10nm-25nm; the thickness of the aluminum oxide passivation layer is 1nm-5nm.

[0040] A method for preparing weather-resistant optical functional coating nanoparticles includes the following steps:

[0041] S1. Provide near-infrared reflective material as the core;

[0042] Specifically, the above-mentioned metal oxide nanoparticles with near-infrared reflection function are mixed with a polar solvent (such as ethanol, isopropanol or ethanol-water solution, preferably ethanol-water solution) to prepare a nanocrystalline seed slurry (solid content 5wt%-15wt%).

[0043] S2. Coating the surface of the core with silicon dioxide to form a core-shell intermediate with a silicon dioxide intermediate layer;

[0044] The specific coating method adopts the sol-gel method; the surface of metal oxides in the nanocrystalline seed slurry usually contains hydroxyl groups (-OH); a catalyst (such as 25%-28% ammonia water) and a silicon source (tetraethyl orthosilicate TEOS) are added, and the amount of catalyst is 5%-10% of the mass of TEOS; the silanol groups (Si-OH) generated by the hydrolysis of TEOS undergo hydrogen bonding or condensation reaction with the hydroxyl groups on the surface of the metal oxide, so that the nucleation and growth of SiO2 preferentially takes place on the surface of the metal oxide nanoparticles, rather than homogeneous nucleation in the solution, thereby achieving uniform coating.

[0045] The amount of tetraethyl orthosilicate (TEOS) used is determined by the target shell thickness (15nm-20nm) and the total surface area of ​​the core. A recommended molar ratio is n(TEOS):n(core surface -OH groups) = 2:1 to 4:1. In practice, the amount can be based on the weight of the metal oxide, with a metal oxide:SiO2 (target) mass ratio of 3:1.

[0046] In practice, the sol-gel method involves the following steps: Under vigorous stirring, the catalyst is added dropwise to the nanocrystalline seed slurry to bring the system pH to 9-11. Stirring is then continued for a period of time (e.g., 30 minutes) to form a homogeneous particle suspension. The TEOS solution is then added very slowly dropwise to the vigorously stirred particle suspension. After the TEOS solution is added, stirring continues, allowing the reaction to proceed for 6-24 hours. During this period, TEOS undergoes hydrolysis and condensation on the surface of the metal oxide nanoparticles, forming a complete and dense amorphous silica layer. After the reaction, the product is centrifuged, washed, and dried to obtain a powdered product, i.e., a core-shell intermediate with a silica intermediate layer.

[0047] S3. Aluminum oxide is deposited on the surface of the silicon dioxide intermediate layer of the core-shell intermediate to form the aluminum oxide passivation layer. The final product is the nanoparticle MO@SiO2@Al2O3.

[0048] The specific deposition method employed is atomic layer deposition (ALD), a thin film growth technique based on surface self-limitation and alternating saturation reactions. ALD deposits alumina on the surface of particulate matter to form a uniform, dense, and conformal nanoscale film. This invention uses trimethylaluminum (TMA) and water (H2O) as precursors to deposit alumina (Al2O3) at a deposition temperature of 180℃-220℃ (200℃ is selected in the following examples). One ALD cycle consists of a TMA pulse-nitrogen purging-H2O pulse-nitrogen purging cycle, with approximately 0.11 nm of Al2O3 grown per cycle. The number of deposition cycles depends on the target thickness of the alumina passivation layer (1 nm-5 nm). Therefore, this invention requires approximately 9-46 cycles.

[0049] The nanoparticle MO@SiO2@Al2O3 has a three-layer core-shell structure, consisting of a core, a silicon dioxide intermediate layer, and an aluminum oxide passivation layer from the inside out.

[0050] Core MO: Composed of near-infrared reflective material, it performs spectral selectivity; its function is to selectively reflect the near-infrared band (780nm-2500nm) in sunlight, thereby reducing the absorption of heat by the substrate device (such as photovoltaic module).

[0051] The silicon dioxide intermediate layer (SiO2) encapsulates the core and plays multiple roles: (a) Optical buffer layer: matching the refractive index, reducing light scattering, and maintaining high light transmittance; (b) Ideal reaction substrate: its uniform and abundant silanol groups provide a perfect chemical anchoring point for subsequent atomic-precision thin film deposition, which is a key prerequisite for achieving a high-quality passivation layer; (c) Primary isolation layer: initially isolating the core.

[0052] Alumina passivation layer (Al2O3): Encasing the silica interlayer, this continuous, dense amorphous film functions as a chemically inert barrier, physically and chemically isolating the photocatalytically active core from the external environment (especially the subsequent organic resin coating substrate). This permanently inhibits the photocatalytic degradation of the resin caused by the core material under external conditions such as ultraviolet light excitation. ALD technology can achieve conformal, uniform, and pinhole-free film growth on complex nanoparticle surfaces. The deposited Al2O3 layer has extremely high density, chemical inertness, and ultraviolet shielding ability. This nanoscale-thick Al2O3 layer acts like an atomic armor, physically blocking the penetration of environmental media and chemically cutting off the pathway for ultraviolet light to excite the core to generate active species and attack the resin, thus achieving permanent passivation of the core's photocatalytic activity. The combination of the silica interlayer and the ALD-Al2O3 layer produces a synergistic effect of 1+1>2, which is key to obtaining intrinsically stable functional fillers.

[0053] In specific implementations, the aforementioned nanoparticles serve as functional fillers in weather-resistant optical functional coatings, with a mass fraction of 0.5%-12% in the coating. In specific implementations, the weather-resistant optical functional coating comprises a resin matrix and functional fillers, and this coating can be used in vehicle housings, building components, photovoltaic modules, or industrial equipment housings.

[0054] This invention uses an environmentally friendly near-infrared reflective material as its functional core. Through a three-layer structure design of core-silica intermediate layer-alumina passivation layer, it fundamentally solves the problem of catalytic aging of coating raw materials (such as organic resin matrix) under ultraviolet light while fully retaining its near-infrared reflective function. This results in a photovoltaic gain coating that has high optical performance, ultra-long weather resistance and significant cost advantages.

[0055] Example 1

[0056] A method for preparing weather-resistant optical functional coating nanoparticles includes the following steps:

[0057] S1. Weigh 1.0g of monodisperse antimony-doped tin dioxide (ATO) nanoparticles (Sb doping amount 8wt%, average particle size D50=40nm).

[0058] S2. 1.0 g of ATO nanoparticles were dispersed in a mixed solution of 200 mL ethanol and 50 mL deionized water, and sonicated for 30 minutes to form a uniform suspension. Under mechanical stirring, 6 mL of ammonia water was added as a catalyst, and the system was heated to 40 °C in a water bath. Subsequently, 3.0 mL of TEOS was slowly added dropwise at a rate of 0.5 mL / min using a constant pressure dropping funnel. After the addition was complete, the reaction was continued at 40 °C for 16 hours to coat the surface of the ATO nanoparticle core with a silica interlayer. After the reaction, the product was separated by centrifugation, washed three times with ethanol, and dried in a vacuum drying oven at 80 °C for 6 hours to obtain a white powdery ATO@SiO2. By adjusting the amount of TEOS, the thickness of the silica interlayer can be controlled from 10 nm to 25 nm; in this example, the target thickness of the silica interlayer is approximately 25 nm.

[0059] S3. 0.5g of the above ATO@SiO2 powder was evenly spread in the sample tray of the ALD reaction chamber and pretreated at 200℃ for 1 hour to remove surface physically adsorbed water. Subsequently, using high-purity nitrogen as the carrier and purge gas, deposition was performed in one cycle as follows: pulsed TMA 0.1 s → nitrogen purging 20 s → pulsed water vapor 0.1 s → nitrogen purging 25 s. This cycle was repeated 30 times to coat the ATO@SiO2 powder surface with an Al2O3 passivation layer. After deposition, the powder was naturally cooled to room temperature under a nitrogen atmosphere to obtain the final core-shell structured ATO@SiO2@Al2O3 nanoparticles. The Al2O3 passivation layer thickness can be controlled from 1nm to 5nm; in this embodiment, the target thickness of the Al2O3 passivation layer is approximately 3.3nm. Typical transmission electron microscopy (TEM) images of the ATO@SiO2@Al2O3 prepared in this embodiment are shown below. Figure 2 As shown.

[0060] Example 2

[0061] The difference between this embodiment and Example 1 is that the antimony-doped tin dioxide (ATO) nanoparticles in step S1 are replaced with indium tin oxide (ITO) nanoparticles (D50=80nm), and the amount of TEOS in step S2 is adjusted to 2.5mL. Other conditions and steps are the same as in Example 1, and the final product is ITO@SiO2@Al2O3 nanoparticles.

[0062] Example 3

[0063] The difference between this embodiment and Embodiment 1 is that the antimony-doped tin dioxide (ATO) nanoparticles in step S1 are replaced with titanium-doped tungsten oxide (WO3:Ti) nanoparticles (Ti doping amount 5at%, D50=70nm). Other conditions and steps are the same as in Embodiment 1, and the final product is WO3@SiO2@Al2O3 nanoparticles.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that step S3 is omitted, i.e. there is no aluminum oxide passivation layer, and the final product is ATO@SiO2 nanoparticles.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 1 is that it only includes step S1, namely ATO nanopowder.

[0068] Comparative Example 3

[0069] The difference between this comparative example and Example 1 is that ATO nanopowder, silicon dioxide, and aluminum oxide are directly mixed. The amounts of silicon dioxide and aluminum oxide can be calculated using tetraethyl orthosilicate and trimethylaluminum to obtain an ATO / SiO2 / Al2O3 mixture, rather than forming core-shell structured nanoparticles.

[0070] Comparative Example 4

[0071] This comparative example prepares core-shell particles without a silica interlayer, namely ATO@Al2O3 core-shell particles; it is used to verify the necessity of the silica interlayer in the overall structure, especially its key role in providing a uniform deposition substrate for the Al2O3 layer.

[0072] Its preparation method includes the following steps:

[0073] Step 1: Take 1.0g of the same batch and quality of the original ATO nanoparticles as in Example 1.

[0074] Step 2: Without SiO2 coating, the ATO powder is placed directly in the ALD reaction chamber and subjected to the same ALD process as step S3 in Example 1 (200℃ pretreatment, TMA / H2O precursor, repeated cycles 30 times) to directly deposit an Al2O3 layer on the ATO surface.

[0075] Example 4

[0076] This embodiment illustrates the application of functional fillers in the photovoltaic field. Specifically, nanoparticles prepared in Examples 1 to 3, Comparative Examples 1 and 4, as well as ATO nanoparticles in Comparative Example 2 and the ATO / SiO2 / Al2O3 mixture in Comparative Example 3, were used as functional fillers and uniformly dispersed in UV-curable fluorosilicone resin at a mass fraction of 3 wt% to prepare a photovoltaic gain coating. The photovoltaic gain coating was applied to the light-receiving surface of a photovoltaic module (i.e., a transparent glass substrate) using a blade coating method. After curing, a coating sample with a dry film thickness of approximately 10 μm was prepared and tested. The initial optical properties and accelerated aging durability of each coating sample were tested, and the results are shown in Table 1. A coating sample prepared without any functional fillers was used as a blank control group.

[0077] 1. Initial optical performance: The visible light (Tvis) transmittance of the coated sample at 550 nm and the weighted average near-infrared (RNIR) reflectance in the 780 nm-2500 nm band were measured using a UV-Vis-NIR spectrophotometer.

[0078] 2. Accelerated UV aging: Performed according to GB / T 23987-2009 "Artificial climate aging of paint and varnish coatings exposed to fluorescent ultraviolet lamps"; the coating samples were placed in an ultraviolet aging chamber (UVA-340 lamp, irradiance 0.76W / m²).2 After continuous irradiation for 1000 hours (approximately equivalent to 1-2 years of outdoor exposure) at 340nm and blackboard temperature of 60℃, the Tvis transmittance was measured again and compared with the initial Tvis transmittance to calculate the visible light transmittance retention rate (Tvis retention rate).

[0079] 3. Damp heat aging: Place the coating sample in a constant temperature and humidity chamber (85℃, 85% relative humidity) for 500 hours and evaluate its adhesion change (cross-cut test, grade 0-5).

[0080] 4. Measured steady-state temperature drop: Irradiate the coated sample under a standard solar simulator (AM1.5G, 1000W / m²), measure the center temperature of the back side of the coated glass substrate with an infrared thermal imager, and compare it with the blank glass substrate to calculate the steady-state temperature drop (ΔT).

[0081] Table 1

[0082]

[0083] Tests on the coating samples corresponding to Examples 1 to 3 showed that the coating had excellent light transmittance and did not affect the absorption of visible light by the photovoltaic module; the core effectively performed the near-infrared shielding function, reducing the temperature rise of the module; the extremely high Tvis retention rate after ultraviolet accelerated aging proved that the Al2O3 passivation layer effectively isolated the degradation of the resin caused by the photocatalytic reaction of the core induced by ultraviolet light, and the coating was firmly bonded to the substrate without peeling.

[0084] Tests on the coating sample corresponding to Example 2 showed that its initial Tvis transmittance was 92.5%, and its initial RNIR reflectance reached 39.5% (slightly higher than the ATO solution). After 1000 hours of UV aging under the same conditions, the Tvis retention rate was as high as 99.2%, fully verifying the excellent protective effect of the Al2O3 passivation layer on the highly photocatalytically active ITO core. This solution is suitable for high-end scenarios with extreme performance requirements.

[0085] The raw material cost of the core (ATO) in Example 1 is lower than that of the core (ITO) in Example 2. Compared with Example 2, Example 1 achieves a huge advantage of 70%-80% cost reduction while sacrificing a very small absolute performance peak.

[0086] Tests on the coating samples corresponding to Example 3 show that, while possessing good near-infrared management capabilities (initial RNIR reflectance 35.5%) and weather resistance (Tvis retention rate 98.0%), the coating, due to the characteristics of the WO3 core, lays the foundation for the development of adaptive smart coatings such as electrochromic or thermochromic coatings.

[0087] Example 1 and Comparative Examples 1 to 4: Comparison of Tvis retention rates of coatings prepared from different samples after UV accelerated aging (see bar chart). Figure 3 As shown.

[0088] The coating sample corresponding to Comparative Example 1 exhibited high initial optical performance, but after 1000 hours of UV aging, the Tvis transmittance decreased to 82.1% (Tvis retention rate was approximately 88.3%), and the coating showed significant yellowing. This indicates that the lack of an outermost Al2O3 passivation layer meant that the ATO core could not be suppressed under the adverse effects of UV light, leading to rapid coating degradation.

[0089] The initial Tvis transmittance of the coating sample corresponding to Comparative Example 2 was 90.5% (due to powder agglomeration). After UV aging, its performance decreased sharply, with a Tvis transmittance of 74.0% (Tvis retention rate of approximately 81.8%), and the coating showed severe chalking. This indicates that the original functional material without any coating treatment not only has poor dispersibility and poor initial performance, but also causes the most severe damage to the resin matrix, and its overall performance cannot meet the requirements for long-term use.

[0090] Comparative Example 3 tests showed that its performance was comprehensively and significantly inferior to all embodiments, with the lowest Tvis retention rate and the worst thermal insulation effect. This fully demonstrates that simple component mixing cannot achieve the synergistic effect of the core-shell structure. Only by using the sequential coating process described in this invention to form a precise structure with a core at the center and each layer tightly wrapped can high light transmittance, high reflectivity, and ultra-weather resistance be achieved simultaneously.

[0091] Comparative Example 4 tests showed a comprehensive deterioration in its overall performance, with low initial Tvis transmittance and RNIR reflectance. In particular, its weather resistance was even worse than Comparative Example 1, and its adhesion was also poor. This result demonstrates that the SiO2 interlayer is not simply a spacer, but rather an ideal chemical and physical substrate necessary for the uniform and dense deposition of the Al2O3 layer. Without this interlayer, the Al2O3 passivation layer cannot form effectively, leading to the loss of its core protective function.

[0092] Example 5

[0093] This embodiment analyzes the application and effects of high-end automotive exterior paint (clear coat), specifically as follows:

[0094] Example 1, Comparative Example 1, and Control Group 1 (Jiangsu Tianxing TTP-R80 commercially available rutile nano-TiO2) and Control Group 2 (Jiangsu Tianxing TSP-L12 commercially available hydrophobic modified SiO2 nanoparticles) were used as functional fillers and added to the commercially available MyutoS / 929-186 two-component polyurethane automotive clear coat system at an addition amount of 2.0 wt% to prepare clear coat samples. A two-component polyurethane automotive clear coat sample without any functional fillers was used as a blank control. Each clear coat sample was sprayed onto the car body to prepare a sample panel.

[0095] The heat insulation and self-cleaning (dust-repellent) properties of the above varnish samples were tested, and the results are shown in Tables 2 and 3.

[0096] Test method for thermal insulation performance: Referring to the concept of automotive interior heat load testing, the sample was placed under a standard solar simulator (irradiance 1000W / m²). 2 The temperature of the paint surface back (simulating paint surface temperature) and the air temperature behind the sample (simulating the effect of thermal radiation) were monitored using thermocouples, and the steady-state temperature difference (ΔT) was recorded; the RNIR reflectance test method was the same as in Example 4 above.

[0097] Test methods for self-cleaning (dust-repellent) performance: (1) Surface energy / contact angle: Measure the water contact angle (WCA). (2) Dust adhesion and cleaning experiment: Spread simulated road dust (a mixture of silicon micro powder and carbon powder) evenly on the sample surface, let it stand, and then rinse it with a fine water stream at a fixed angle and flow rate. Calculate the surface dust residue rate. (3) Pollution resistance: Add simulated acid rain solution and artificial bird droppings, and observe the residue and gloss loss after cleaning.

[0098] Table 2

[0099]

[0100] Table 2 shows that the coating of this invention exhibits excellent passive heat insulation, reducing the paint surface back temperature by up to 8.5°C. This effectively slows down paint aging under intense sunlight and reduces the heat load transferred to the vehicle interior. This is attributed to the highly efficient near-infrared reflection function of the ATO core (RNIR reflectivity up to 58%) and the complete core-shell structure, which avoids light scattering loss caused by filler agglomeration and maintains high paint film transparency. Control group 1 (nano TiO2), due to its strong photothermal conversion characteristics, actually caused the paint surface to heat up, proving that simple ultraviolet shielding cannot solve the problem of infrared heat radiation. This invention achieves the ideal effect of high light transmittance and infrared heat blocking through spectral selective reflection.

[0101] Table 3

[0102]

[0103] Table 3 shows that the coating of this invention achieves a balance between hydrophobicity and easy cleaning, as well as weather resistance and durability; its water contact angle is greater than 105°, exhibiting excellent hydrophobicity. This is mainly attributed to the outermost amorphous Al2O3 passivation layer, which is chemically stable, has low surface energy, and the surface microstructure formed by ALD technology is conducive to hydrophobicity. Under water rinsing, water droplets easily roll off and carry away most of the dust, significantly improving the efficiency of daily cleaning (such as rain washing). Outdoor simulation tests show that vehicles using the clear coat coating of this invention require approximately 50%-60% less car wash frequency to maintain a clean appearance under the same urban commuting conditions compared to traditional car paint. More importantly, this self-cleaning function is embedded in the weather-resistant coating, unlike control group 2 which only physically adds hydrophobic agents (which are prone to failure during aging), thus maintaining its function for a long time.

[0104] The coating of this invention is also applicable to protective coatings for metal / plastic housings such as outdoor communication cabinets and power control boxes. The ATO@SiO2@Al2O3 prepared in Example 1 is added at 2wt%-5wt% to polyester / polyurethane outdoor powder coatings or fluorocarbon liquid coatings, and then sprayed onto pretreated cold-rolled steel or aluminum alloy plates. After curing, a protective coating is formed. Housings based on the coating of this invention are expected to significantly delay chalking and gloss loss while maintaining the color and gloss of the substrate, and possess a certain infrared reflection cooling function, reducing the internal heat load of the cabinet; its weather resistance can meet the 20-year service life requirement for outdoor communication equipment, significantly reducing maintenance costs. Under similar coating systems and outdoor service conditions, the coating of this invention can also provide industrial equipment housings with long-term stability far exceeding that of existing technologies.

[0105] Example 6

[0106] This embodiment analyzes the application and effect of a transparent heat-insulating coating for architectural glass curtain walls. Specifically, Example 1, Comparative Example 1, and Control Group 3 (commercially purchased Hangzhou Jiupeng New Materials CY-S01A single-layer SiO2-based transparent heat-insulating liquid) were used as functional fillers and dispersed in an adhesive system (commercially purchased Huihe Yongsheng SG-1430-H1 silica sol-silane composite adhesive) at an addition amount of 4.0 wt% to obtain a coating. The coating was applied to clean architectural glass to form a uniform coating sample with a dry film thickness of approximately 120 nm. The spectral properties of the above coating sample were tested using ordinary glass as a reference, and the results are shown in Table 4.

[0107] The detection methods for indicators such as Tvis transmittance, Tvis retention rate, water contact angle, and measured glass back temperature drop are the same as those in Examples 4 and 5 above. The transmittance of the coating sample in the near-infrared band of 780nm-2500nm was measured using a spectrophotometer. Solar infrared blocking rate = 1 - transmittance. Under a solar simulator, the ratio of radiant heat transmitted through an external window (including the window frame and architectural glass) to radiant heat transmitted through a standard window (including the window frame and transparent glass) of the same area under the same conditions is the shading coefficient (SC).

[0108] Table 4

[0109]

[0110] Table 4 shows the results:

[0111] 1. The coating of this invention maintains high Tvis transmittance (>84%) while achieving over 60% solar infrared heat blocking, with a shading coefficient as low as approximately 0.5, significantly reducing the back temperature of glass under sunlight by more than 8°C. This not only improves indoor thermal comfort but is also expected to bring 20%-40% energy-saving potential to building air conditioning systems. Its thermal insulation performance is significantly superior to commercially available products, and the protection of the Al2O3 layer ensures low degradation after long-term use.

[0112] 2. The hydrophobic surface (WCA≥100°) of the coating of this invention makes it difficult for dust to adhere firmly, and when it encounters rainwater, it can form water droplets that roll off and carry away the dust, achieving a self-cleaning effect. Simulation calculations show that building glass curtain walls using this coating can reduce the annual frequency of manual cleaning and maintenance costs by about 40%-50%, effectively reducing the loss of power generation efficiency caused by dust obstruction, and achieving the dual benefits of increased power generation and reduced operation and maintenance costs.

[0113] 3. The coating of this invention has long-term performance guarantee, and all its excellent performance is based on ultra-long weather resistance. After 3,000 hours of UV aging, the Tvis retention rate exceeds 97%, which ensures that the heat insulation and self-cleaning functions are stably performed throughout the entire life cycle of the building, avoiding the problem of the performance of traditional functional coatings dropping sharply due to resin yellowing and chalking.

[0114] Through systematic control group design, quantitative performance testing, and effect analysis closely aligned with real-world application scenarios, the invention's nanoparticles have been fully demonstrated to possess outstanding advantages in addressing the two market pain points of heat insulation and self-cleaning. In the automotive sector, they endow car paint with the dual high-end characteristics of staying cool and being easy to maintain, directly responding to consumers' demands for reduced vehicle maintenance costs and improved comfort. In the building and photovoltaic sectors, they achieve the dual economic benefits of energy conservation and reduced operation and maintenance, providing a technical solution for the long-term stable operation of green buildings and photovoltaic power plants.

[0115] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A weather-resistant optical functional coating nanoparticle, characterized in that, The nanoparticles include: The core is a near-infrared reflective material; the near-infrared reflective material is made of metal oxide nanoparticles with near-infrared reflective function. The first coating layer is a silica intermediate layer that encapsulates the core. The method for coating the core surface with silica is a sol-gel method, specifically: mixing near-infrared reflective metal oxide nanoparticles with a polar solvent to prepare a nanocrystalline seed slurry with a solid content of 5wt%-15wt%; adding a catalyst dropwise to the nanocrystalline seed slurry under vigorous stirring to make the system pH=9-11, and then continuing to stir stably to form a homogeneous particle suspension; and slowly adding a TEOS solution dropwise to the vigorously stirred particle suspension. After the TEOS solution is added dropwise, stirring continues, allowing the reaction to proceed for 6-24 hours. TEOS undergoes hydrolysis and condensation on the surface of the metal oxide nanoparticles, forming a complete and dense amorphous silica layer. After the reaction, the product is centrifuged, washed, and dried to obtain a core-shell intermediate with a silica intermediate layer. The polar solvent is ethanol, isopropanol, or an ethanol-water solution. The catalyst is ammonia solution with a concentration of 25%-28%, and the amount of catalyst is 5%-10% of the mass of TEOS. The molar ratio of TEOS to -OH groups on the core surface is 2:1 to 4:

1. The second encapsulation layer is an alumina passivation layer that encapsulates the silicon dioxide intermediate layer. The method for depositing alumina on the surface of the silicon dioxide intermediate layer of the core-shell intermediate is atomic layer deposition. The aluminum source is trimethylaluminum, and the deposition temperature is 180℃-220℃. The thickness of the alumina passivation layer is 1nm-5nm.

2. The weather-resistant optical functional coating nanoparticles according to claim 1, characterized in that, The near-infrared reflective material is selected from at least one of antimony-doped tin dioxide, indium tin oxide, aluminum-doped zinc oxide, fluorine-doped tin oxide, gallium-doped zinc oxide, molybdenum-doped tungsten oxide, titanium-doped tungsten oxide, or tungsten oxide.

3. The weather-resistant optical functional coating nanoparticles according to claim 1, characterized in that, The thickness of the silicon dioxide intermediate layer is 10nm-25nm.

4. A method for preparing weather-resistant optical functional coating nanoparticles according to any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: Provide near-infrared reflective material as the core; The core surface is coated with silicon dioxide to form a core-shell intermediate with a silicon dioxide intermediate layer; Alumina is deposited on the surface of the silica intermediate layer of the core-shell intermediate to form the alumina passivation layer.

5. The method for preparing weather-resistant optical functional coating nanoparticles according to claim 4, characterized in that, The method for coating the core surface with silica is the sol-gel method, and the silica source is tetraethyl orthosilicate.

6. The method for preparing weather-resistant optical functional coating nanoparticles according to claim 4, characterized in that, The method for depositing aluminum oxide on the silica intermediate layer surface of the core-shell intermediate is atomic layer deposition; the aluminum source is trimethylaluminum, and the deposition temperature is 180℃-220℃.

7. The application of the weather-resistant optical functional coating nanoparticles according to any one of claims 1 to 3, characterized in that, The nanoparticles serve as functional fillers for a weather-resistant optical functional coating; the coating is applied to the surface of products that are exposed to the elements for extended periods outdoors.

8. A weather-resistant optical functional coating, characterized in that, The weather-resistant optical functional coating comprises a resin matrix and a functional filler; the functional filler is the weather-resistant optical functional coating nanoparticles as described in any one of claims 1 to 3.

9. The weather-resistant optical functional coating according to claim 8, characterized in that, The mass fraction of the nanoparticles in the coating is 0.5%-12%.

10. The application of the weather-resistant optical functional coating of claim 8 or 9 in vehicle housings, building components, photovoltaic modules, or industrial equipment housings; characterized in that, The vehicle shell is a car body or car parts; the building component is architectural glass or metal curtain wall panel; the photovoltaic module is a photovoltaic glass cover or back panel.

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