All-weather four-season energy-saving low-emission building coating, preparation method and application thereof

Abstract

The application discloses a kind of all-weather four seasons energy-saving low-emissivity building coating, preparation method and application, belong to functional building coating technical field.The coating includes: low-emissivity material, high infrared transmittance film-forming emulsion, directional arrangement auxiliary system, other auxiliary agent and water.Low-emissivity material is ATO or ITO and the core-shell structure of cerium dioxide coated flaky aluminum silver paste, 4-16 μm mid-infrared emissivity 0.1-0.3;Directional arrangement auxiliary system is by interface lubricating auxiliary system, physical positioning auxiliary system and volume shrinkage auxiliary system synergistically formed;The mid-infrared emissivity of prepared coating is less than or equal to 0.4, near-infrared reflectivity is greater than or equal to 0.83, winter energy-saving efficiency is about 30% on average, summer energy-saving efficiency is about 37% on average.

Description

Technical Field

[0001] This invention belongs to the field of functional building coatings technology, specifically relating to an all-weather, all-season energy-saving low-emission building coating, its preparation method, and its application. Background Technology

[0002] With increasingly stringent energy efficiency requirements, thermal insulation of building envelopes has become a crucial aspect of energy conservation and emission reduction. Low-E materials effectively suppress heat radiation transfer, making them an effective means of reducing building heating and cooling loads. In the field of Low-E coatings, aluminum, due to its free electron gas properties, possesses excellent infrared reflectivity and is typically used as a functional filler in the form of flake aluminum paste (also known as aluminum pigment). This flake aluminum paste has a large aspect ratio, and its smooth, sheet-like surface produces a significant specular reflection effect on mid-infrared and near-infrared radiation, which is the key physical basis for achieving low emissivity in coatings.

[0003] However, flake aluminum silver paste is prone to oxidation and blackening in aqueous systems, exhibits poor alkali resistance, and is limited by the rheological properties of the coating. During film formation, it is susceptible to flipping, agglomeration, or random accumulation, making it difficult to form a continuous reflective layer parallel to the substrate surface. This results in an actual emissivity of the coating that is far higher than the theoretical value, failing to achieve energy-saving effects throughout the year. While existing technologies employ coating schemes using aluminum or silver powder, they generally lack systematic control over the orientation behavior of flake metallic pigments in aqueous wet films and lack long-term weather resistance protection for the aluminum core, limiting their application in harsh environments such as building exterior walls. For example, CN119775833A discloses a self-layering colored low-emissivity coating and its preparation method, but it uses a large amount of organic solvents, resulting in poor environmental friendliness. CN117925073A discloses an infrared coating with synergistic regulation of heat insulation and low emissivity, and its application method, employing a two-component coating system and utilizing the filler sedimentation principle to form a gradient composite coating. However, it requires stringent control over the sedimentation of the flake filler and does not address the anti-oxidation treatment of the aluminum pigment.

[0004] Therefore, it is of great significance to develop a water-based, environmentally friendly, weather-resistant, high infrared reflectance coating that can be achieved through microstructural regulation and is adaptable to all seasons. Summary of the Invention

[0005] This invention aims to provide an all-weather, all-season energy-saving low-emission (Low-E) architectural coating, its preparation method, and its application. This invention achieves excellent low-emission and energy-saving effects by constructing a specific oriented additive system to regulate the rheological properties of the coating and induce the formation of a highly oriented layered structure in the flake aluminum silver paste during film formation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first objective of this invention is: A low-emission (Low-E) architectural coating that is energy-efficient in all climates and seasons is provided, comprising the following raw material components by weight percentage: Low emissivity material 5-14%, high infrared transmittance film-forming emulsion 10-50%, orientation alignment aid system 3-18%, other aids 0.1-3%, balance is water, and the sum of all raw material components is 100%; The low emissivity material is a core-shell structure material (ATO / CeO2@Al or ITO / CeO2@Al) with sheet-like aluminum silver paste as the core and antimony tin oxide (ATO) or indium tin oxide (ITO) and cerium dioxide as the coating layer, and its mid-infrared emissivity in the wavelength range of 4 to 16 μm is 0.1 to 0.3. The antimony tin oxide (ATO) or indium tin oxide (ITO) in the coating layer are both synergistically coated with cerium dioxide to form a core-shell structure; among them, ITO / CeO2@Al can achieve a lower mid-infrared emissivity and a higher near-infrared reflectivity due to the higher carrier concentration of ITO, and can be regarded as a preferred embodiment.

[0007] Preferably, the aluminum silver paste has an aspect ratio of not less than 50, and more preferably 60-80, and its flat, sheet-like surface forms the physical basis for the infrared reflection of the coating; the coating of ATO / ITO and CeO2 can effectively block oxidation and improve infrared optical stability; the coating layer of the low emissivity material has a thickness of 30-70 nm and an overall particle size of 30-40 μm; the preferred addition amount is 8%.

[0008] The high infrared transmittance film-forming emulsion has an infrared transmittance of not less than 85% in the wavelength range of 4 to 16 μm; the high infrared transmittance emulsion can reduce the absorption of infrared radiation by the resin matrix, so that the radiation energy can reach the aluminum-based reflective layer efficiently; the high infrared transmittance film-forming emulsion is selected from one or a combination of pure acrylic emulsion, silicone acrylic emulsion, fluorocarbon emulsion, fluorosilicone modified acrylic emulsion, nonionic waterborne polyurethane emulsion, and acrylic polyurethane composite emulsion; preferably, the high infrared transmittance film-forming emulsion is a low acid value pure acrylic emulsion, fluorosilicone modified acrylic emulsion, or a compound emulsion of the two, with an acid value of not more than 10 mg KOH / g; more preferably, the high infrared transmittance film-forming emulsion has a glass transition temperature Tg of -10 to 40 °C, a solid content of 35 to 55 wt%, and an acid value of not more than 10 mg KOH / g.

[0009] The directional alignment additive system includes: an interface lubrication additive system, a physical positioning additive system, and a volume shrinkage additive system; in, The interface lubrication aid system comprises: phosphate ester surfactants and polymeric dispersants, used to form an adsorption protective layer on the surface of low emissivity materials and provide steric hindrance, reducing aluminum sheet agglomeration and corrosion, and promoting wetting and spreading; preferably, the phosphate ester surfactants are selected from one or a combination of monoalkyl phosphates, dialkyl phosphates, fatty alcohol polyether phosphates, AEO polyether phosphates, fluorophosphates, amine-neutralized phosphates, and low-acid-value alkyl phosphates; more preferably, AEO polyether phosphates and fluorophosphates are used in combination; the polymeric dispersant is selected from one or a combination of AB block copolymers, ABA block copolymers, comb-like acrylic copolymers, polyurethane modified dispersants, polyether modified polyurethane dispersants, and waterborne polyurethane wetting and dispersing agents; more preferably, comb-like acrylic copolymers.

[0010] The physical positioning aid system includes: an inorganic thixotropic rheology agent and wax particles, used to construct a three-dimensional thixotropic network to prevent aluminum sheet sedimentation and to force the aluminum sheets to be arranged in parallel layers during film formation; preferably, the inorganic thixotropic rheology agent is selected from one or a combination of lithium magnesium silicate, hydropyrite, synthetic flake silicate, fumed silica, organobentonite, attapulgite, and sepiolite; more preferably, it is lithium magnesium silicate or hydropyrite; the wax particles are selected from one or a combination of polyethylene wax emulsion, polypropylene wax emulsion, waterborne polyamide wax dispersion, waterborne polyethylene wax dispersion, waterborne PTFE composite wax dispersion, and waterborne PE composite wax dispersion; more preferably, it is waterborne polyamide wax dispersion.

[0011] The volume shrinkage aid system includes: high molecular weight cellulose, microparticles / microgels, and film-forming conditioning aids, used to generate vertical shrinkage force or physical extrusion force during the drying process of wet film, locking the sheet-like aluminum silver paste into a layered structure parallel to the substrate; preferably, the high molecular weight cellulose is selected from one or a combination of water-modified cellulose acetate butyrate, hydrophobically modified hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and carboxymethyl cellulose; more preferably, water-modified cellulose acetate butyrate and hydrophobically modified hydroxyethyl cellulose are used in combination; the microparticles / microgels are selected from one or a combination of internally cross-linked core-shell microgels, pH-responsive microgels, and water-based polyurethane-acrylic hybrid microspheres; more preferably, water-based polyurethane-acrylic hybrid microspheres.

[0012] The film-forming modifier is selected from one or a combination of ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol, ethylene glycol, hexanediol, and isopropanol; more preferably, isopropanol and ethylene glycol butyl ether are used in combination.

[0013] The other additives include one or a combination of film-forming aids, pH adjusters, defoamers, leveling agents, and thickeners; wherein the film-forming aids are selected from one or a combination of alcohol ester film-forming aids, alcohol ether film-forming aids, and alcohol film-forming aids. The defoamer is selected from one or a combination of polyether defoamers, mineral oil / polyether compound defoamers, emulsion defoamers, and polyether-modified silicone defoamers; The leveling agent is selected from one or a combination of polyether-modified polydimethylsiloxane, organosilicon wetting and leveling agents, low-foaming silicone wetting agents, and fluorinated wetting agents. The thickener is selected from one or a combination of nonionic polyurethane associative thickener (HEUR), associative hydrophobic modified alkali-swellable emulsion thickener (HASE), and alkali-swellable acrylic thickener.

[0014] Through the triple synergistic effect of the above-mentioned directional additive system, the architectural coating achieves high performance at low shear rates (0.1 s⁻¹). -1 The viscosity of the coating is 15000–35000 mPa·s, the thixotropic index is 4.0–5.5, the mid-infrared emissivity of the coating in the wavelength range of 4–16 μm is ≤0.4, and the near-infrared reflectivity in the wavelength range of 780–2000 nm is ≥0.83; in addition, the pH range of the building coating system is 7.5–8.5, and the film-forming open time is not less than 8 minutes.

[0015] The second objective of this invention is: A method for preparing the aforementioned all-weather, all-season energy-saving low-emission (Low-E) architectural coating is provided, comprising the following steps: S1. Slurry dispersion: Add film-forming regulator, phosphate ester surfactant, and polymeric dispersant, and shear and stir at low speed for 10-15 minutes. Then add the low emissivity material and continue to stir slowly so that the phosphate ester is adsorbed on the surface of the low emissivity material for passivation and lubrication, thereby obtaining a low emissivity material dispersion slurry. S2. Preparation of base material: Add water, high molecular weight cellulose, inorganic thixotropic rheology modifier, and pH adjuster. Shear and stir at high speed (800-1500 r / min) for 5-10 minutes to shear the inorganic thixotropic rheology modifier into a gel. Then add high infrared transmittance film-forming emulsion and switch to medium speed (400-800 r / min) for shear and stir for 5-10 minutes to obtain the base material. S3. Combining: Slowly pour the low emissivity material dispersion slurry obtained in step S1 into the base material obtained in step S2, and disperse it at medium speed for 5-10 minutes to allow the emulsion in the base material to encapsulate the low emissivity material; S4. Oriented Alignment: Add wax particles and microcolloids / microgels to the mixture obtained in step S3, disperse at a medium speed for 10-15 minutes, so that the wax particles and microcolloids / microgels are embedded in the gaps of the low emissivity materials, forcing the low emissivity materials (such as aluminum silver paste) to align in parallel. S5. Post-adjustment: Add film-forming aid, defoamer, leveling agent and thickener, adjust the pH of the system to 7.5-8.5, use deionized water to fine-tune the viscosity at 25℃ to 90-110 KU, and after filtration, the all-weather, all-season energy-saving low-emission (Low-E) architectural coating is obtained.

[0016] The third objective of this invention is: A substrate coated with the aforementioned all-weather, all-season, energy-saving, low-emission (Low-E) architectural coating is provided: The dry film formed on the surface of the substrate has a thickness of 45-55 μm, and the aluminum silver paste in the dry film has a layered arrangement structure parallel to the surface of the substrate, forming a reflective layer with high coverage.

[0017] Compared with the prior art, the present invention has the following technical features and effects: (1) This invention achieves parallel orientation of aluminum sheets through a triple synergistic mechanism of a directional alignment additive system. The interface lubrication additive system forms a dense adsorption layer on the aluminum sheet surface and provides steric hindrance, reducing agglomeration and corrosion; the physical positioning additive system constructs a three-dimensional thixotropic network and forces the aluminum sheets to stack in parallel through wax particle embedding; the volume shrinkage additive system generates physical extrusion force through the chain entanglement shrinkage of high molecular weight cellulose and the dehydration collapse of microparticles / microgels, locking the aluminum sheets into a layered structure parallel to the substrate. In this layered structure, the planar surfaces of the sheet-like aluminum pigments are aligned, maximizing the reflection of incident and radiant heat energy, resulting in an emissivity of ≤0.4 in the mid-infrared band and a reflectivity of ≥0.83 in the near-infrared band. The coating exhibits high spectral density at low shear rates (0.1 s⁻¹). -1 The rheological characteristics of the aluminum sheet, with a viscosity of 15,000–35,000 mPa·s and a thixotropic index of 4.0–5.5, provide the necessary mechanical constraints and time window for the orientation of the aluminum sheet.

[0018] (2) This invention employs a core-shell structured low-emissivity material (ATO / CeO2@Al or ITO / CeO2@Al) combined with a high-infrared-transmittance emulsion, which improves the coating's weather resistance while optimizing the infrared optical path design. The ATO / ITO and CeO2 coating layers effectively isolate oxygen and moisture, protecting the aluminum core from oxidation. After being placed at 60°C for 60 days, the emissivity of the coating only increases by 0.02 to 0.04, far superior to the 0.06 increase of the uncoated aluminum silver paste. The high-infrared-transmittance emulsion reduces the absorption of radiation in the 4–16 μm band by the resin matrix, allowing thermal radiation to reach the aluminum-based reflective layer efficiently, achieving high reflection of solar thermal radiation in summer and low emission of indoor thermal radiation in winter.

[0019] (3) This invention achieves true all-weather, all-season energy-saving effect. In winter, the low emissivity reduces the loss of indoor heat to the outside in the form of thermal radiation, resulting in an energy saving efficiency of about 30% compared to conventional aluminum silver paste systems. In summer, the high near-infrared reflectivity blocks solar radiation from entering the room, resulting in an energy saving efficiency of about 37% compared to conventional aluminum silver paste systems. The coating has a two-way adjustment capability of heat insulation and cooling in summer and heat preservation and energy saving in winter, making it suitable for building envelopes in different climate zones.

[0020] (4) This invention is an aqueous system, which is environmentally friendly and has a simple preparation process and a wide construction window. Compared with the existing technology that uses a lot of organic solvents, this invention has a low VOC content, which is in line with the development direction of green building materials. The preparation method adopts a step-by-step feeding process, which has strong operational controllability and is suitable for large-scale production and on-site construction. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and comparative experiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Unless otherwise specified, the reagents, equipment, and methods used in this invention are conventional reagents, equipment, and general methods in this technical field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products; conventional auxiliaries whose dosages are not specified are within the appropriate ranges commonly used in this technical field.

[0022] Obtaining low emissivity materials: The low emissivity material used in this embodiment is an ATO / CeO2@Al core-shell structure material, which is a core-shell structure material with commercially available sheet aluminum silver paste (aspect ratio of about 60 to 80) as the core and antimony tin oxide (ATO) and cerium dioxide as the coating layer. The coating layer is about 50 nm thick, the overall particle size is about 35 μm, and the mid-infrared emissivity in the wavelength range of 4 to 16 μm is 0.25.

[0023] The specific preparation method of the low emissivity material includes the following steps: S1. Add 2g of binder (maleic anhydride-grafted EPDM rubber) and 0.16g of emulsifier (SDBS, AEO-9) to 12.5mL of pure water, stir and emulsify for 30min to obtain binder solution; S2. Mix 100g of aluminum silver paste with 2.5mL of anhydrous ethanol, put the mixture into a ball mill jar, add zirconia beads (φ0.8mm, bead-to-material mass ratio 5:1), and ball mill at 250rpm for 45min to obtain a metal paste. S3. Add 3g of nano-ATO and 1g of nano-CeO2 to the metal slurry obtained in step S2, and ball mill at 180rpm for 30min to obtain a mixed slurry; S4. Add the binder solution obtained in step S1 to the mixed slurry obtained in step S3, and ball mill at 180 rpm for 60 min to obtain ATO / CeO2@Al low emissivity material.

[0024] Test method: 1. Rheological properties: The shear rate was measured at 0.1 s⁻¹ using a rotational rheometer at 25°C. -1 The viscosity at 6 r / min; the thixotropic index (TI) is defined as the ratio of the apparent viscosity at 6 r / min to that at 60 r / min.

[0025] 2. Film-forming open time: Refer to GB / T 9269-2009, and use the finger touch method to record the time when the wet film surface loses its fluidity.

[0026] 3. Mid-infrared emissivity: Measured in the range of 4–16 μm using an infrared emissivity meter, in accordance with GB / T 7287-2008.

[0027] 4. Near-infrared reflectance: The reflectance in the 780–2000 nm band was measured using a UV / Vis / NIR spectrophotometer with an integrating sphere (PerkinElmerLambda 1050+) according to ASTM E903.

[0028] Examples 1-5: An all-weather, all-season energy-saving low-emission (Low-E) architectural coating The formulations of Examples 1 to 4 are shown in Table 1. The formulation of Example 5 is the same as that of Example 1, except that ATO / CeO2@Al in Example 1 is replaced with ITO / CeO2@Al.

[0029] Table 1. Formulations of architectural coatings in Examples 1-4 (unit: g)

[0030] The preparation method of the all-weather, all-season energy-saving low-emission (Low-E) architectural coating includes the following steps: S1. Slurry Dispersion: Film-forming conditioning agent, phosphate ester surfactant (fluorophosphate ester, AEO polyether phosphate ester), and polymeric dispersant (comb acrylic copolymer) are added sequentially, and the mixture is sheared and stirred at low speed for 10-15 min. Then, low emissivity material (ATO / CeO2@Al or ITO / CeO2@Al slurry) is added, and the mixture is stirred slowly to allow the phosphate ester to adsorb onto the surface of the low emissivity material for passivation and lubrication, thus obtaining a low emissivity material dispersion slurry. S2. Preparation of base material: Deionized water, high molecular weight cellulose, synthetic flake potassium silicate, and pH adjuster are added sequentially, and the mixture is sheared and stirred at high speed (1000-1500 r / min) for 5-10 min to shear the synthetic flake potassium silicate into a gel, forming a three-dimensional thixotropic network. Then, a high infrared transmittance film-forming emulsion is added, and the mixture is sheared and stirred at medium speed (400-800 r / min) for 5-10 min to obtain the base material. S3. Combining: Slowly pour the low emissivity material dispersion slurry obtained in step S1 into the base material obtained in step S2, and disperse it at medium speed for 5 to 10 minutes to ensure that the emulsion in the base material fully encapsulates the low emissivity material; S4. Oriented Alignment: Add water-based polyamide wax dispersion and microparticles / microgels to the mixture obtained in step S3, disperse at medium speed for 10-15 min, so that the wax particles and microparticles / microgels are embedded in the gaps of the low emissivity material, forcing the low emissivity material to align in parallel; S5. Post-adjustment: Add film-forming aid, defoamer, thickener and leveling agent (the leveling agent in the formula can be added together with the thickener or a commercially available composite thickener containing leveling components can be selected), adjust the pH of the system to 7.5-8.5, and use deionized water or thickener solution to fine-tune the viscosity at 25°C to 90-110 KU. After filtration, the all-weather, all-season energy-saving low-emission (Low-E) architectural coating is obtained.

[0031] Rheological performance testing: The rheological properties of the coating obtained in Example 1 at 25°C were tested and found to be: low shear rate (0.1 s⁻¹) -1 The viscosity at is 25500 mPa·s, the thixotropic index is 5, and the film-forming open time is approximately 10 minutes. These rheological characteristics indicate that the system can rapidly reconstruct the three-dimensional network structure after construction shearing, effectively suppressing the overturning and settling of the sheet-like aluminum silver paste, and providing the necessary mechanical constraints and time window for its parallel orientation.

[0032] Comparative Example 1: The low emissivity material of Example 1 was used, but a conventional formulation system was used (without the orientation alignment aid system, only ordinary alkali swelling thickener was used, and no film-forming modifiers, microparticles / microgels and wax particles or other orientation components were added).

[0033] Comparative Example 2: Commercially available uncoated ordinary aluminum silver paste is used, employing a conventional formulation system (excluding directional alignment aids).

[0034] Comparative Example 3: The coating was prepared using commercially available uncoated ordinary aluminum silver paste (aspect ratio of about 60-80, particle size of about 35 μm) and the same directional alignment additive system and preparation process as in Example 1.

[0035] Experimental Example 1: Emissivity and Reflectivity Detection After the above-described embodiments and comparative examples were filmed on aluminum plates (dry film thickness 50±5 μm), their optical properties were tested, and the results are shown in Table 2 below.

[0036] Table 2. Coating performance test results of Examples 1-5 and Comparative Examples 1-3

[0037] Results analysis: Comparative Example 2 used uncoated ordinary aluminum silver paste and did not use a directional alignment agent system, resulting in the highest emissivity and lowest reflectivity. Comparative Example 1, although using a core-shell structured low-emissivity material, still had a high emissivity of 0.43 due to the lack of a directional alignment agent system (especially the lack of film-forming regulators and microgels in the volume shrinkage system). Examples 1-4, through the triple synergistic effect of the core-shell structured low-emissivity material combined with the directional alignment agent system, significantly reduced the mid-infrared emissivity of the coating and improved the near-infrared reflectivity.

[0038] Example 5 uses ITO / CeO2@Al instead of ATO / CeO2@Al as the low emissivity material. The infrared emissivity of the coating is further reduced to 0.31, and the near-infrared reflectivity is increased to 0.882, both superior to the ATO-based coating material in Example 1. ITO (indium tin oxide) itself has superior carrier concentration and free electron flow capability compared to ATO (antimony tin oxide), exhibiting lower emissivity and higher reflectivity in the infrared band. Therefore, the ITO / CeO2 co-coating structure can achieve better optical performance. This result demonstrates that the directional alignment additive system of the present invention has good compatibility with different types of metal oxide-coated aluminum silver pastes, and ITO / CeO2@Al can be considered a preferred solution to achieve an even more extreme low emissivity effect.

[0039] Further analysis shows that the high viscosity and high thixotropic rheological field constructed by the directional alignment additive system is the physical basis for the parallel orientation of aluminum sheets. In Comparative Examples 1 and 2, due to the lack of an effective three-dimensional network structure, the sheet-like aluminum silver paste exhibits disordered arrangement or flipping in the coating, leading to increased emissivity. In this embodiment of the invention, through the synergistic effect of three systems—interfacial lubrication, physical positioning, and volume shrinkage—the viscosity of the coating reaches 25500–25600 mPa·s at low shear rates, the thixotropic index is 4.8–5.0, and the film-forming open time is extended to 8–11 minutes, providing sufficient mechanical constraints and time windows for aluminum sheet orientation. The rheological parameter range (viscosity 15000–35000 mPa·s, TI 4.0–5.5) defined in this technical solution is a range determined after repeated experimental verification, all of which can achieve the parallel orientation of the sheet-like aluminum silver paste.

[0040] Comparative Example 3 used uncoated ordinary aluminum silver paste, but employed the exact same orientation-aligning agent system as Example 1. Its coating exhibited an infrared emissivity of 0.56 and a near-infrared reflectivity of 0.752. Although its rheological parameters reached a viscosity of 25400 mPa·s, a thixotropic index of 5.1, and an open time of 9 min, its optical performance was still far inferior to Example 1. This indicates that even if parallel orientation of the aluminum sheet is successfully achieved through the three agent systems, the lack of a protective coating layer in the ordinary aluminum silver paste leads to oxidation of the aluminum sheet itself during wet film drying and long-term service, resulting in a significant decrease in infrared reflectivity. This comparison fully demonstrates that the synergy between the core-shell coating structure and the orientation-aligning agent system is indispensable.

[0041] Meanwhile, controlling the dry film thickness within the range of 45–55 μm is a preferred process window to ensure the aforementioned optical properties and coating stability. This thickness range ensures that the flake aluminum silver paste forms a sufficiently dense layered structure in the coating, avoiding incomplete metal coverage and increased emissivity due to excessively thin film thickness. It also prevents coating cracking, peeling, or significant cost increases caused by excessively thick film thickness, thus balancing energy-saving effects and engineering applicability.

[0042] Experimental Example 2: High Temperature Stability Study Each sample was placed at 60℃ for 60 days, and its performance changes were tested. The results are shown in Table 3 below.

[0043] Table 3. Stability study at high temperature (60℃) for 60 days

[0044] Results analysis: The examples used a core-shell structured low-emissivity material combined with a coating controlled by a directional alignment agent system. In high-temperature stability tests, the performance degradation was minimal, with little difference from the initial value, demonstrating excellent high-temperature aging resistance. Comparative Example 2 showed an emissivity increase of 0.06, which was attributed to the oxidation reaction of ordinary aluminum silver paste at high temperatures. This proves that the ATO / CeO2 (or ITO / CeO2) coating effectively isolated oxygen and moisture, protecting the aluminum core from oxidation. Comparative Example 1, lacking a directional alignment agent system, had loosely arranged aluminum flakes in its coating, and the coating layer may have developed microcracks under long-term thermal exposure, resulting in a greater increase in emissivity than the examples. Comparative Example 3 showed an emissivity increase of 0.11 after aging at 60°C, significantly higher than the increases in all examples. This further verifies the necessity of the coating layer: even with a directional alignment agent system providing rheological protection, ordinary aluminum silver paste, lacking a chemical coating layer, still undergoes severe oxidation in high-temperature, oxygen-rich environments, leading to a sharp increase in emissivity and a significant decrease in reflectivity. This result further demonstrates from a durability perspective that the core-shell encapsulation structure is a necessary condition for achieving long-term stable low emission performance in this invention.

[0045] Experimental Example 3: Energy Efficiency Assessment 1. Winter Test The coatings obtained in the above embodiments and the coatings obtained in the comparative examples were sprayed onto the surface of a fully enclosed cube (20×20×30 cm) made of concrete substrate with a thickness of 3 cm. A 20×20 cm resistance wire heating element (resistance 28.8Ω) was installed inside, along with an external relay and power recorder. A temperature sensor was installed inside the cube to control the internal temperature to be maintained at 25°C. When the temperature was below 25°C, the relay started heating; when it was above 25°C, heating stopped. The power recorder recorded the peak power density required to maintain the temperature throughout the process, and the results are shown in Table 4.

[0046] Table 4 Peak power density in winter (W / m²)

[0047] 2. Summer Energy Saving Test A concrete cube of the same specifications was connected to a small, temperature-controlled refrigeration air compressor to maintain an internal temperature of 25°C. The peak power density required to maintain the temperature was recorded by a power recorder throughout the process, and the results are shown in Table 5.

[0048] Table 5. Peak power density in summer (W / m²)

[0049] Results analysis: This experiment used Comparative Example 2 (conventional aluminum silver paste + conventional coating system) as a benchmark to calculate the relative energy-saving efficiency, using the following formula: Energy-saving efficiency (%) = (Power consumption of comparative example - Power consumption of embodiment) / Power consumption of comparative example × 100%. In winter, due to the low emissivity of the coating, indoor heat loss through thermal radiation is reduced, thus significantly lowering the heating power required to maintain indoor temperature. In summer, the high reflectivity of the coating blocks solar heat radiation from entering the room, reducing the cooling load. Overall, compared to Comparative Example 2, and considering environmental temperature fluctuations and testing errors, the embodiment using the coating of this invention achieves an average energy-saving efficiency of approximately 30% in winter and approximately 37% in summer, realizing a true all-weather, all-season energy-saving effect.

[0050] Example 5 demonstrates superior energy-saving performance compared to Example 1, with an average energy-saving efficiency of approximately 36% in winter and approximately 39% in summer. This is attributed to the lower emissivity and higher reflectivity of ITO / CeO2@Al, which further enhances the coating's ability to reduce heat loss in winter and block solar radiation in summer.

[0051] Comparative Example 3 exhibited the second worst energy-saving effect among all tested samples (only better than Comparative Example 2), with an average energy-saving efficiency of approximately 9% in winter and approximately 7% in summer, significantly lower than the 30% / 37% of the Examples. Although Comparative Example 3 used the orientation-aligning agent system of this invention (rheological parameter TI≈5.1 confirms that the aluminum sheet is indeed oriented), the lack of coating protection in ordinary aluminum silver paste led to a continuous degradation of optical performance due to aluminum sheet oxidation during actual service, ultimately resulting in a significant reduction in energy-saving effect. This further validates the necessity and synergistic effect of the "coating + orientation" dual mechanism from the application perspective.

[0052] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low-emission architectural coating that is energy-saving in all climates and seasons, characterized in that: Includes the following raw material components by weight percentage: Low emissivity material 5-14%, high infrared transmittance film-forming emulsion 10-50%, orientation alignment aid system 3-18%, other aids 0.1-3%, balance is water, and the sum of all raw material components is 100%; The low emissivity material is a core-shell structure material with sheet-like aluminum silver paste as the core and tin oxide or indium tin oxide and cerium dioxide as the coating layer, and its mid-infrared emissivity in the wavelength range of 4 to 16 μm is 0.1 to 0.

3. The high infrared transmittance film-forming emulsion has an infrared transmittance of not less than 85% in the wavelength range of 4 to 16 μm; The directional alignment additive system includes: an interface lubrication additive system, a physical positioning additive system, and a volume shrinkage additive system; in, The interface lubrication aid system includes: phosphate ester surfactants and polymeric dispersants; The physical positioning aid system includes: inorganic thixotropic rheology agents and wax particles; The volume shrinkage aid system includes: high molecular weight cellulose, microparticles / microgels, and film-forming regulators.

2. The all-weather, all-season energy-saving low-emission building coating according to claim 1, characterized in that: The coating thickness of the low emissivity material is 30–70 nm, and the overall particle size is 30–40 μm.

3. The all-weather, all-season energy-saving low-emission building coating according to claim 1, characterized in that: The high infrared transmittance film-forming emulsion is selected from one or a combination of pure acrylic emulsion, silicone-acrylic emulsion, fluorocarbon emulsion, fluorosilicone modified acrylic emulsion, nonionic waterborne polyurethane emulsion, and acrylic-polyurethane composite emulsion. The other additives include one or a combination of film-forming aids, pH adjusters, defoamers, leveling agents, and thickeners.

4. The all-weather, all-season energy-saving low-emission building coating according to claim 3, characterized in that: The high infrared transmittance film-forming emulsion is a low-acid-value pure acrylic emulsion, a fluorosilicone-modified acrylic emulsion, or a compound emulsion of the two, with an acid value not exceeding 10 mg KOH / g.

5. The all-weather, all-season energy-saving low-emission architectural coating according to claim 1, characterized in that: The phosphate ester surfactants are selected from one or a combination of monoalkyl phosphates, dialkyl phosphates, fatty alcohol polyether phosphates, AEO polyether phosphates, fluorophosphates, amine-neutralized phosphates, and low-acid-value alkyl phosphates. The polymeric dispersant is selected from one or a combination of AB block copolymers, ABA block copolymers, comb-like acrylic copolymers, polyurethane modified dispersants, polyether modified polyurethane dispersants, and waterborne polyurethane wetting and dispersing agents.

6. The all-weather, all-season energy-saving low-emission architectural coating according to claim 1, characterized in that: The inorganic thixotropic rheology agent is selected from one or a combination of lithium magnesium silicate, hydropyrite, synthetic lamellar silicate, fumed silica, organobentonite, attapulgite, and sepiolite. The wax particles are selected from one or a combination of polyethylene wax emulsion, polypropylene wax emulsion, waterborne polyamide wax dispersion, waterborne polyethylene wax dispersion, waterborne PTFE composite wax dispersion, and waterborne PE composite wax dispersion.

7. The all-weather, all-season energy-saving low-emission architectural coating according to claim 1, characterized in that: The high molecular weight cellulose is selected from one or a combination of water-modified cellulose acetate butyrate, hydrophobically modified hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and carboxymethyl cellulose. The microparticles / microgels are selected from one or a combination of internally cross-linked core-shell microgels, pH-responsive microgels, and aqueous polyurethane-acrylic hybrid microspheres. The film-forming modifier is selected from one or a combination of ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol, ethylene glycol, hexanediol, and isopropanol.

8. The all-weather, all-season energy-saving low-emission building coating according to claim 1, characterized in that: The architectural coating has a mid-infrared emissivity ≤0.4 in the wavelength range of 4–16 μm and a near-infrared reflectivity ≥0.83 in the wavelength range of 780–2000 nm. and / or, The building coating has a viscosity of 15,000–35,000 mPa·s at low shear rates and a thixotropic index of 4.0–5.

5. and / or, The pH range of the architectural coating system is 7.5 to 8.5, and the film-forming open time is not less than 8 minutes.

9. A method for preparing an all-weather, all-season energy-saving, low-emission architectural coating as described in any one of claims 1 to 8, characterized in that: Includes the following steps: S1. Slurry dispersion: Add film-forming regulator, phosphate ester surfactant, and polymeric dispersant, and shear and stir at low speed for 10-15 minutes. Then add the low emissivity material and continue to stir slowly so that the phosphate ester is adsorbed on the surface of the low emissivity material for passivation and lubrication, thereby obtaining a low emissivity material dispersion slurry. S2. Preparation of base material: Add water, high molecular weight cellulose, inorganic thixotropic rheology agent, and pH adjuster. Shear and stir at high speed for 5-10 minutes to shear the inorganic thixotropic rheology agent into a gel. Then add high infrared transmittance film-forming emulsion and switch to medium speed shear and stir for 5-10 minutes to obtain the base material. S3. Combining: Slowly pour the low emissivity material dispersion slurry obtained in step S1 into the base material obtained in step S2, and disperse it at medium speed for 5-10 minutes; S4. Oriented arrangement: Add wax particles and microcolloids / microgels to the mixture obtained in step S3, and disperse at a medium speed for 10-15 min; S5. Post-adjustment: Add film-forming aid, defoamer, leveling agent and thickener, adjust the pH of the system to 7.5-8.5, use deionized water to fine-tune the viscosity at 25℃ to 90-110 KU, and after filtration, the all-weather, all-season energy-saving low-emission architectural coating is obtained.

10. A substrate coated with the all-weather, all-season, energy-saving, low-emission architectural coating according to any one of claims 1 to 8, characterized in that: The thickness of the dry film formed on the surface of the substrate is 45-55 μm, and the aluminum silver paste in the dry film has a layered arrangement structure parallel to the surface of the substrate.

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