Low-e glass substrate surface high weatherability heat-absorbing coating and preparation method thereof

Abstract

The present application relates to a kind of Low-E glass substrate surface high weatherability heat-absorbing coating and its preparation method, including the heat-insulating buffer primer and heat-absorbing finish coating coated on the surface of Low-E glass substrate in turn, heat-insulating buffer primer includes the following components by mass fraction: FEVE fluorocarbon emulsion 30~40 parts, mesoporous silica aerogel powder 8~12 parts, mercapto propyl trimethoxysilane 2~3 parts, moisture curing isocyanate 3~5 parts, primer additive 2~3 parts, primer solvent remainder;The application is through mesoporous silica aerogel heat-insulating buffer primer, utilize nano-pore confinement effect to reduce the dry film thermal conductivity of primer, so that coating is better in solar radiation Heat-insulating effect, avoid when heat-absorbing, high temperature influence Low-E functional film layer, avoid the oxidation of silver layer, vulcanization and thermal stress damage caused by heat-absorbing, effectively protect Low-E functional film layer.

Description

Technical Field

[0001] This invention relates to the field of glass coating technology, specifically to a high weather-resistant heat-absorbing coating for Low-E glass substrates and its preparation method. Background Technology

[0002] Low-E (low-emissivity) glass is widely used in building energy conservation due to its excellent mid- and far-infrared reflectivity. However, with the improvement of green building standards, relying solely on Low-E film to block radiant heat is no longer sufficient to meet the energy conservation needs under extreme climates. Coating the glass surface with heat-absorbing coatings to further shield near-infrared solar radiation has become a research hotspot. In existing technologies, high weather-resistant heat-absorbing coatings are mostly designed for solar collectors or ordinary glass substrates. For example, CN102134437B discloses a UV-curable glass coating that achieves rapid curing through epoxy acrylate resin, high-functional polyurethane acrylate resin, high-functional monomer, monofunctional monomer, and thermoplastic acrylic resin. It exhibits a relatively high crosslinking density during application and demonstrates good resistance to boiling water, ethanol, and perfume. CN109233531A discloses a high weather-resistant solar heat-absorbing coating that uses fluorocarbon resin combined with graphene and plant extracts to achieve heat absorption and UV resistance. However, when these conventional heat-absorbing coatings are directly applied to Low-E glass substrates, they suffer from the following significant drawbacks: I. Existing heat-absorbing coatings pursue high-efficiency heat collection, with high thermal conductivity and no buffer structure. The absorbed solar radiation heat is quickly conducted to the Low-E silver-based functional film layer, resulting in excessive local temperature rise of the film layer, causing silver layer oxidation, sulfidation and blackening, or even thermal stress cracking. Second, Low-E glass has extremely low surface energy (usually <30mN / m) and strong chemical inertness. Existing coatings rely on physical adsorption or ordinary silane coupling, which are prone to interfacial hydrolysis in humid and hot or acid rain environments, leading to blistering and peeling of the coating. Third, broad-spectrum heat absorbers such as graphene and carbon black have high emissivity in the mid- and far-infrared regions. After coating, they will significantly increase the overall emissivity of the coating, which will offset the original low-radiation heat insulation function of Low-E glass and violate the original intention of energy saving. Fourth, traditional fluorocarbon coatings require high-temperature curing above 150℃ to form a dense network, while Low-E glass is not resistant to high temperatures (the silver layer is prone to failure at >120℃), and low-temperature curing results in insufficient cross-linking, and its water resistance and salt spray resistance cannot meet the long-term use requirements of building facades.

[0003] Therefore, we propose a high weather-resistant heat-absorbing coating for Low-E glass substrates to solve the above problems. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high-weather-resistant heat-absorbing coating for Low-E glass substrates and its preparation method. While ensuring efficient near-infrared heat absorption, it also takes into account interfacial heat buffering, specific adhesion, low-radiation function maintenance, and low-temperature curing compatibility. This solves the problems of heat damage, poor adhesion, functional damage, and curing incompatibility caused by the incompatibility of heat-absorbing coatings with Low-E substrates in existing glass coatings.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high weather-resistant heat-absorbing coating for the surface of a Low-E glass substrate, comprising a heat-insulating buffer primer and a heat-absorbing topcoat sequentially coated on the surface of the Low-E glass substrate; The heat-insulating buffer primer, by weight, comprises the following components: 30-40 parts FEVE fluorocarbon emulsion, 8-12 parts mesoporous silica aerogel powder, 2-3 parts mercaptopropyltrimethoxysilane, 3-5 parts moisture-curing isocyanate, 2-3 parts primer additives, and the balance of primer solvent. The mercapto groups generated after hydrolysis of mercaptopropyltrimethoxysilane form MS coordination bonds with the metal oxides on the surface of the Low-E glass substrate. The moisture-curing isocyanate reacts with the hydroxyl groups in the FEVE fluorocarbon emulsion to form a urethane cross-linked network. The heat-insulating buffer primer is used to block the conduction of solar radiation heat absorbed by the heat-absorbing topcoat to the Low-E functional film layer. The primer solvent is a mixture of deionized water and ethanol in a volume ratio of (3-5):1.

[0006] The heat-absorbing topcoat, by weight, comprises the following components: 35-45 parts FEVE fluorocarbon resin, 15-20 parts composite nanoparticles, 1-2 parts heptadecafluorodecyltrimethoxysilane, 0.5-1.5 parts photoinitiator, 4-6 parts UV / moisture dual curing agent, 3-4 parts topcoat additives, and the balance being the topcoat solvent. The topcoat solvent is a mixture of propylene glycol methyl ether acetate and ethylene glycol butyl ether acetate, with a volume ratio of (1-2):1.

[0007] Furthermore, the mesoporous silica aerogel powder has a pore size of 5–20 nm, a porosity of 85%–95%, a specific surface area of ​​500–800 m² / g, a bulk density of 0.05–0.15 g / cm³, and a thermal conductivity of ≤0.025 W / (m·K). This parameter range ensures that the aerogel has sufficient nanopore confinement effect to suppress heat transfer between the solid and gas phases, while maintaining suitable mechanical strength to withstand the stress of the surface coating.

[0008] Furthermore, the composite nanoparticles are core-shell structured materials with cesium tungsten bronze as the core and silicon dioxide as the shell, and the cesium tungsten bronze has a hexagonal crystal system. The core-shell structure has a core particle size of 10–30 nm, a silica shell thickness of 5–8 nm, and an overall particle size of 20–46 nm. This core-shell structure is prepared via microemulsion coating or sol-gel method, specifically as follows: First, hexagonal phases are synthesized using a hydrothermal method. Nanocrystals were dispersed in an alcoholic solution of tetraethyl orthosilicate, and then hydrolyzed and condensed with ammonia to coat the nanocrystals with a silica shell. The nanocrystals were then centrifuged, washed, and vacuum dried to obtain a hexagonal crystalline phase. It exhibits localized surface plasmon resonance absorption characteristics in the near-infrared region, while the dense silica shell isolates it from water vapor and acid / alkali corrosion. At the same time, it maintains high transmittance in the mid- and far-infrared regions, thus avoiding interference with the low-emissivity function of the Low-E film.

[0009] Furthermore, the UV / moisture dual-curing agent is formulated by compounding acrylate-modified FEVE prepolymer and moisture-curing isocyanate at a mass ratio of 1:(0.8–1.2). The acrylate-modified FEVE prepolymer has a fluorine content of 20%–25%, a hydroxyl value of 30–60 mgKOH / g, and an acrylate double bond functionality of 2–4. The moisture-curing isocyanate is selected from polymethylene polyphenyl polyisocyanate prepolymer or hexamethylene diisocyanate trimer, with an NCO content of 12%–22%. The photoinitiator is selected from 2,4,6-trimethylbenzoyl diphenylphosphine oxide or 1-hydroxycyclohexylphenyl ketone. The primer additives include polycarboxylate anionic dispersants and silicone defoamers, while the topcoat additives include hindered amine light stabilizers, fluorine-modified leveling agents, and polyurethane-type superdispersants.

[0010] Furthermore, the composite coating formed after curing meets the following performance indicators: the total dry film thickness of the coating is 25-45 μm; according to the ISO2409 cross-cut test, the coating adhesion is not lower than grade 0; after 2000 hours of QUV accelerated aging according to GB / T1865, the coating has no blistering, cracking, or peeling, the color difference ΔE < 2, and the adhesion remains not lower than grade 1; after 500 hours of salt spray test according to GB / T1771, the coating has no rust or blistering; the average absorption rate in the near-infrared band 800-2500 nm is ≥ 75%; the thermal conductivity of the dry film of the heat-insulating buffer primer is ≤ 0.06 W / (m·K); under standard solar irradiance of 1000 W / m², the temperature rise of the functional film layer of the Low-E glass substrate coated with the coating is ≥ 15℃ different from that of the functional film layer of the same Low-E glass substrate without the heat-insulating buffer primer.

[0011] It should be noted that the thermal barrier effect of the heat-insulating buffer primer is achieved through the following mechanism: After the mesoporous silica aerogel powder cures, it forms a continuous nanoporous network with a pore size of 5–20 nm, which is smaller than the mean free path of air molecules (approximately 70 nm), resulting in the Knudsen effect, which significantly inhibits gas heat conduction within the pores. Simultaneously, the solid-phase heat transfer path of the silica framework is extremely prolonged due to its high porosity (85%–95%). Actual measurements show that when the dry film thickness of the primer is 10–18 μm, its effective thermal conductivity is 0.04–0.06 W / (m·K), and its thermal resistance is [value missing]. Under standard solar irradiance of 1000 W / m², ambient temperature of 25°C, and no wind, the temperature on the back of the Low-E functional film layer was monitored using an infrared thermal imager. The steady-state temperature of the film layer of the sample coated with the coating of this invention was 15-22°C lower than that of the control sample coated only with heat-absorbing topcoat (without heat-insulating primer). This confirms that the heat-insulating buffer primer can effectively control the working temperature of the film layer below the silver oxidation threshold (approximately 80°C).

[0012] The present invention also provides a method for preparing the above-mentioned coating, comprising the following steps: S1. Preparation of heat-insulating buffer primer: Mesoporous silica aerogel powder and mercaptopropyltrimethoxysilane were added to FEVE fluorocarbon emulsion and ultrasonically dispersed for 30 min at 200 W ultrasonic power and temperature <35℃ to ensure uniform dispersion of the aerogel powder without significant agglomeration. Subsequently, moisture-curing isocyanate and primer additives were added, and the mixture was stirred at 300-500 rpm for 20 min. The mixture was then filtered through a 200-mesh filter to obtain the heat-insulating buffer primer. Mercaptopropyltrimethoxysilane was pre-hydrolyzed with deionized water at pH 4-5 for 15-30 min before being added to the FEVE fluorocarbon emulsion to ensure sufficient exposure of the mercapto groups and effective coordination with the metal oxides on the surface of the Low-E substrate.

[0013] S2. Preparation of heat-absorbing topcoat: The composite nanoparticles, superdispersant, and part of the topcoat solvent are mixed and homogenized 3-5 times using a high-pressure homogenizer at 80-150 MPa pressure to disperse the composite nanoparticles to D90 < 50 nm, obtaining a heat-absorbing slurry. The heat-absorbing slurry is added to FEVE fluorocarbon resin, heptadecafluorodecyltrimethoxysilane, photoinitiator, and UV / moisture dual curing agent, and stirred at 800-1000 rpm for 40 min. The remaining topcoat additives and topcoat solvent are added, and after stirring evenly, the mixture is filtered through a 200-mesh filter to obtain the heat-absorbing topcoat. In step S2, high-pressure homogenization is used instead of sand milling to disperse the composite nanoparticles to avoid mechanical damage to the silica shell by the grinding media. The homogenization valve gap of the high-pressure homogenizer is 10-25 μm, the feed temperature is ≤30℃, and the discharge temperature is ≤40℃. The amount of superdispersant added is 3%-5% of the mass of the composite nanoparticles.

[0014] It should be noted that UV curing and moisture curing must be performed in a strict sequence. If moisture curing is performed first, the urea bonds generated by the reaction of isocyanate and water will consume some of the -NCO groups. At the same time, the CO2 microbubbles generated may be sealed inside the coating by the subsequent UV curing, resulting in increased optical haze. If UV and moisture curing are performed simultaneously, the heat from the UV light source will cause the surface temperature of the coating to rise to 50-70°C instantly, accelerating the evaporation of surface moisture and hindering the diffusion of deep moisture. By adopting a UV-first, moisture-second curing process, the acrylate double bonds are rapidly polymerized in the UV stage (3-8s) to form a surface cross-linked network. At this time, the -NCO groups of isocyanate do not participate in the free radical reaction. In the subsequent 60°C moisture curing stage, ambient moisture diffuses through the surface micropores to the depth of the coating and reacts with the residual -NCO to form urea bond cross-links, achieving gradient densification from the surface to the interior. Among them, the high-pressure homogenization dispersion mechanism is different from the concentrated impact force of the medium collision in sand milling due to the high speed of the liquid flow. Therefore, it can protect the brittle silica shell while achieving nanoscale dispersion.

[0015] The present invention also provides a method for applying the above-mentioned coating, comprising the following steps: S1. Substrate Pretreatment: The surface of the Low-E glass substrate is subjected to plasma treatment to achieve a surface dynamometer value ≥40mN / m. Atmospheric pressure air plasma or Ar / O2 mixed gas plasma is used for plasma treatment, with a treatment power of 500–1500W, a treatment speed of 2–8m / min, and 1–2 treatment passes. The primer should be applied within 30 minutes after plasma treatment to prevent surface flaking.

[0016] S2. Applying a heat-insulating buffer primer: Apply a heat-insulating buffer primer to the plasma-treated substrate surface, with a wet film thickness of 20–30 μm. Dry the primer using a gradient temperature control: first, maintain the temperature at 40°C for 3 minutes to allow the solvent to slowly evaporate, then maintain the temperature at 60°C for 5 minutes to complete the initial cross-linking, forming a dry film thickness of 10–18 μm. The coating method is roller coating or slot coating; the substrate surface temperature is controlled at 20–35°C before coating.

[0017] S3. Applying the heat-absorbing topcoat: Apply the heat-absorbing topcoat to the surface of the heat-insulating buffer primer layer, with a wet film thickness of 15–25 μm. First, UV cure to quickly set the surface of the topcoat, then perform moisture curing at 60℃ and relative humidity ≥60%RH for 10–15 minutes to allow the deeper layers of the coating to complete the reaction between isocyanate and water, forming the topcoat layer. UV curing uses a 395nm LED ultraviolet light source with an irradiation energy of 300–600 mJ / cm² and a curing time of 3–8 seconds. The heat-absorbing topcoat must be applied within 30 minutes of the heat-insulating buffer primer layer to ensure interlayer adhesion; if the interval exceeds 30 minutes, the primer layer surface must undergo plasma activation treatment again.

[0018] S4. The total dry film thickness of the resulting composite coating is 25–45 μm.

[0019] It should be noted that after the FEVE fluorocarbon emulsion in the primer cures, the fluorocarbon segments migrate and accumulate to the surface, reducing the surface energy of the primer layer to 35-40 mN / m. In contrast, the surface tension of propylene glycol methyl ether acetate and ethylene glycol butyl ether acetate in the endothermic topcoat solvent system is 28.5 mN / m and 30.2 mN / m, respectively, both lower than the surface energy of the primer. At the same time, the trace amounts of mercaptosilane hydrolysis products remaining in the primer can undergo a condensation reaction with heptadecafluorodecyltrimethoxysilane in the topcoat, forming a Si-O-Si covalent bridge at the interface, further strengthening the interlayer bonding force. The reason for limiting the topcoat application to within 30 minutes after primer application is that the orientation of the fluorocarbon segments on the primer surface tends to stabilize after 30 minutes.

[0020] Compared with the prior art, the technical solution of this application has the following beneficial effects: 1. This invention uses a mesoporous silica aerogel thermal insulation buffer primer, which utilizes the nanopore confinement effect to reduce the dry film thermal conductivity of the primer, making the coating more effective in heat insulation under solar radiation. This avoids the impact of high temperature on the Low-E functional film layer when absorbing heat, and avoids silver layer oxidation, sulfidation and thermal stress damage caused by heat absorption, effectively protecting the Low-E functional film layer. 2. This invention uses mercaptopropyltrimethoxysilane as an interface anchoring agent. The mercapto groups generated by its hydrolysis react with Ag on the surface of the Low-E film. + Zn² + The formation of stable MS coordination bonds between metal ions, combined with plasma pretreatment, improves the adhesion between the substrate and the coating. 3. This invention adopts a hexagonal crystal system. Core-shell nanoparticles serve as a heat-absorbing medium, with the core having a better absorption rate and the dense silica shell having a better transmittance. This improves the overall solar energy blocking rate without compromising the original low-radiation heat insulation function, thus balancing efficient heat absorption with low-radiation function. 4. This invention adopts a dual curing system of UV and moisture. In the UV stage, it can be rapidly set at room temperature to prevent sagging. In the moisture stage, it can be deeply cross-linked at 60°C to form an interpenetrating polymer network. FEVE fluorocarbon resin provides a high bond energy skeleton. Combined with hindered amine light stabilizer, it achieves excellent weather resistance. 5. This invention, through its two-component coating structure, achieves compatibility between water-based primer and solvent-based topcoat, and forms a synergistic protective effect of a two-layer system, thus improving its practicality. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] FEVE fluorocarbon emulsion: fluorine content 22%–24%, hydroxyl value 40–55 mg KOH / g, solid content 50%, pH 7–9, commercially available (such as Asahi Glass LUMIFLONFE-4300 aqueous dispersion); FEVE fluorocarbon resin: fluorine content 23%–25%, hydroxyl value 45–60 mgKOH / g, number average molecular weight 3000–5000, soluble in ester solvents, solid content 65%; Mesoporous silica aerogel powder: pore size 5-20 nm, porosity 85%-95%, specific surface area 500-800 m² / g, bulk density 0.05-0.15 g / cm³, thermal conductivity ≤0.025 W / (m·K), particle size D50 3-8 μm (e.g. Cabot Aerogel LC410). Mercaptopropyltrimethoxysilane (MPTMS): Purity ≥98%, CAS 4420-74-0; Moisture-curing isocyanates (for primers): Hexamethylene diisocyanate (HDI) trimer, NCO content 21%–23% (e.g., Covestro Desmodur N3600). Acrylic ester modified FEVE prepolymer: fluorine content 22%, hydroxyl value 45mgKOH / g, acrylate double bond functionality 3, number average molecular weight 2500; Moisture-curing isocyanates (for topcoats): polymethylene polyphenyl polyisocyanate (MDI) prepolymers with NCO content of 15%–18% (e.g., Wanhua MDI-50); Photoinitiator TPO: 2,4,6-trimethylbenzoyl diphenylphosphine oxide, CAS 75980-60-8, absorption peak 395nm; Photoinitiator 184: 1-hydroxycyclohexylphenyl ketone, CAS 947-19-3; Heptadecafluorodecyltrimethoxysilane: purity ≥97%, CAS166099-43-8; Cesium chloride: analytical grade, ≥99.5%; Sodium tungstate: analytical grade, ≥99%; Tetraethyl orthosilicate (TEOS): analytical grade, ≥99%; Polycarboxylate anionic dispersants: such as BYK-190; Organosilicon defoamers: such as Deqian 6500; Hindered amine light stabilizer 944: poly{[6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidinyl)imino]}, such as BASF Tinuvin 944; Fluorine-modified leveling agents: such as Glide 450; Polyurethane-type superdispersants: anchoring groups adsorb inorganic nanoparticles at a rate ≥2 mg / m², such as Lubrizol Solsperse 32550; Low-E glass substrate: 6mm float glass, surface coated with Ag / ZnO / SiN x Multilayer film, emissivity ε≤0.10, surface dyne value 28~30mN / m.

[0023] Among them, composite nanoparticles ( / Preparation of ) Step A: Hexagonal phase Hydrothermal Synthesis of Nanocrystals Sodium tungstate ( 0.66g (2mmol) was dissolved in 30mL of deionized water, and oxalic acid was added. 0.252 g (2 mmol) of cesium chloride (CsCl) was dissolved in 5 mL of deionized water and slowly added dropwise to the above sodium tungstate-oxalic acid solution. The pH of the system was adjusted to 1.5 with 1 mol / L hydrochloric acid and stirred for 30 min to obtain a clear precursor solution.

[0024] The precursor solution was transferred to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene, sealed, and placed in an oven at 200 °C for 18 h. After naturally cooling to room temperature, it was washed three times with deionized water (8000 rpm, 5 min), then washed once with anhydrous ethanol, and finally dried under vacuum at 60 °C for 12 h to obtain a deep blue hexagonal phase. Nanocrystalline powder.

[0025] The obtained nanocrystals were confirmed by XRD to have a hexagonal P phase. / m space group (JCPDS83-0881), TEM observation showed particle size of 10-30 nm, D50 of about 20 nm.

[0026] Step B: Shell coating (sol-gel method) Take the result from step A 0.5 g of nanocrystals were ultrasonically dispersed in 100 mL of anhydrous ethanol (ultrasonic power 100 W, 10 min) to obtain a homogeneous suspension. 1.5 mL of ammonia (28 wt%) was added to adjust the pH to 9.5. Under constant temperature water bath conditions of 40℃ and mechanical stirring at 400 rpm, an ethanol solution of tetraethyl orthosilicate (TEOS) (0.15 g of TEOS dissolved in 10 mL of anhydrous ethanol) was added dropwise over 2 h using a micro-injection pump. After the addition was complete, stirring was continued for 4 h to allow the TEOS to undergo hydrolysis and condensation on the surface of the nanocrystals, forming… Shell.

[0027] After the reaction was complete, the sample was washed three times with deionized water by centrifugation, then twice with anhydrous ethanol, and finally dried under vacuum at 60°C for 12 hours to obtain the desired product. / Core-shell structured composite nanoparticles.

[0028] TEM observations showed that the core diameter was approximately 20 nm, the shell thickness was approximately 6 nm, and the overall particle size was approximately 32 nm. The core-shell structure was intact, and the shell was continuous, dense, and crack-free. Dynamic light scattering (DLS) measured the overall particle size D50 to be 35 nm.

[0029] Example 1 This embodiment provides a high weather-resistant heat-absorbing coating for Low-E glass substrates, comprising a heat-insulating buffer primer and a heat-absorbing topcoat sequentially coated onto the surface of the Low-E glass substrate. The heat-insulating buffer primer comprises the following components by weight: 35 parts of FEVE fluorocarbon emulsion (50% solid content), 10 parts of mesoporous silica aerogel powder, 2.5 parts of mercaptopropyltrimethoxysilane (MPTMS), 4 parts of moisture-curing isocyanate (HDI trimer), 1.5 parts of polycarboxylate anionic dispersant (BYK-190), 0.5 parts of silicone defoamer (Deqian 6500), and the remainder (46.5 parts) of a mixed solvent of deionized water and ethanol (volume ratio 4:1). The preparation method of the heat-insulating buffer primer is as follows: (1) Pre-hydrolysis of mercaptosilane: Take 2.5 parts of MPTMS, add 5 parts of deionized water, adjust the pH to 4.5 with glacial acetic acid, stir at room temperature for 20 min to carry out pre-hydrolysis, so that the methoxy group is fully hydrolyzed into silanol group and the mercapto active site is exposed. (2) Aerogel dispersion: 10 parts of mesoporous silica aerogel powder were slowly added to 35 parts of FEVE fluorocarbon emulsion and ultrasonically dispersed for 30 min under the conditions of ultrasonic power of 200W and water bath temperature controlled at 30℃ to obtain a uniform milky white slurry with no visible agglomerated particles. (3) Mixing: Add the pre-hydrolyzed MPTMS solution to the slurry obtained in step (2) and stir until homogeneous. Then add 4 parts of HDI trimer, 1.5 parts of dispersant and 0.5 parts of defoamer, and stir at 400 rpm for 20 min; (4) Filtration: After filtration through a 200-mesh (75μm) filter, any trace gel particles that may be present are removed to obtain a heat-insulating buffer primer with a viscosity of 80-120 mPa·s (25℃, Brookfield rotor) and a solid content of about 40%.

[0030] The heat-absorbing topcoat, by weight, comprises the following components: 40 parts of FEVE fluorocarbon resin (65% solid content) / 17 parts of composite nanoparticles, 1.5 parts of heptadecafluorodecyltrimethoxysilane, 0.8 parts of photoinitiator TPO-, 0.2 parts of photoinitiator 184-, 3 parts of acrylate-modified FEVE prepolymer (UV curing component), 3 parts of MDI prepolymer (moisture curing component), 1.5 parts of hindered amine light stabilizer 944-, 0.5 parts of fluorine-modified leveling agent (Degao Glide 450), 1.5 parts of polyurethane-type superdispersant (Solsperse 32550), and a mixed solvent of propylene glycol methyl ether acetate and ethylene glycol butyl ether acetate (volume ratio 1.5:1), with the remainder being 31.5 parts.

[0031] The preparation method of the heat-absorbing topcoat is as follows: (1) High-pressure homogenization and dispersion: Take 17 parts of composite nanoparticles, 1.5 parts of superdispersant (8.8% of the mass of composite nanoparticles, with an upper limit of 3% to 5% due to the large specific surface area of ​​nanoparticles), and 15 parts of topcoat solvent, mix them, and add them to the hopper of a high-pressure homogenizer (such as APV-2000). Set the homogenization pressure to 120MPa and cycle the homogenization 4 times. The gap of the homogenization valve is 15μm, the feed temperature is controlled at 28℃, and the discharge temperature is monitored at 38℃. After homogenization, the D90 of the composite nanoparticles is measured by a Malvern laser particle size analyzer. The D90 is 42nm < 50nm, which meets the requirements, and an endothermic slurry is obtained. (2) Resin mixing: Transfer the heat-absorbing slurry to a mixing tank, add 40 parts of FEVE fluorocarbon resin, 1.5 parts of heptadecafluorodecyltrimethoxysilane, 0.8 parts of photoinitiator TPO and 0.2 parts of 184, 3 parts of acrylate-modified FEVE prepolymer, and 3 parts of MDI prepolymer, and stir at 900 rpm for 40 min. (3) Adding additives: Add 9441 parts of hindered amine light stabilizer, 0.5 parts of fluorine modified leveling agent, and 16.5 parts of the remaining topcoat solvent. Continue stirring for 10 minutes until uniform. (4) Filtration: After filtration through a 200-mesh filter, the heat-absorbing topcoat is obtained with a viscosity of 200-280 mPa·s (25℃) and a solid content of about 45%.

[0032] Furthermore, the application method for high weather-resistant heat-absorbing coatings on Low-E glass substrates is as follows: (1) Substrate pretreatment: Take Low-E glass substrate (6mm, Ag / ZnO / SiN) x The film layer (emissivity ε=0.08) was surface-treated using an atmospheric pressure air plasma device (such as PlasmaTreatOpenAir-SD). Treatment parameters: power 800W, treatment speed 5m / min, one pass. After treatment, the dyne value of the substrate surface was measured with a dyne pen; it was 42mN / m (≥40mN / m). Primer coating was applied within 15 minutes after treatment. (2) Coating with heat-insulating buffer primer: The heat-insulating buffer primer is applied by roller coating (rubber roller, hardness 55 Shore A) at a substrate temperature of 25℃, and the wet film thickness is controlled to be 25μm. Immediately after coating, the substrate enters the gradient drying channel: the first stage is maintained at 40℃ for 3min (to allow water and ethanol to evaporate slowly and avoid the rapid evaporation of solvent in the aerogel pores, which would cause pinholes); the second stage is maintained at 60℃ for 5min (to allow the HDI trimer to initially crosslink with the hydroxyl groups of the FEVE emulsion to form a film). The dry film thickness after drying is 15μm; (3) Applying the heat-absorbing topcoat: Within 12 minutes after the primer is applied (<30-minute window period), apply the heat-absorbing topcoat using a roller coating method, controlling the wet film thickness to be 20 μm. Immediately after coating, perform UV curing: Use a 395nm LED line light source (such as Dr. Hönle UVLED395), with an irradiation energy of 500 mJ / cm², and a curing time of 5 seconds. The surface of the topcoat will quickly set and form a cross-linked network. Then, transfer it to a curing chamber at 60℃ and 65% RH for moisture curing for 12 minutes, allowing the deep MDI prepolymer to react with water to form urea bonds and complete the curing process. (4) Post-treatment: The total dry film thickness of the resulting composite coating is 15μm (primer) + 18μm (topcoat) = 33μm, which is within the range of 25 to 45μm. After standing at room temperature for 24 hours, the performance was tested.

[0033] Example 2 The only difference from Example 1 is the adjustment of the formula parameters: Heat-insulating buffer primer: 30 parts FEVE fluorocarbon emulsion, 12 parts mesoporous silica aerogel powder, 3 parts MPTMS, 5 parts HDI trimer, 2 parts dispersant, 1 part defoamer, and the balance being a mixture of deionized water and ethanol (volume ratio 3:1).

[0034] Heat-absorbing topcoat: 45 parts FEVE fluorocarbon resin, 20 parts composite nanoparticles, 2 parts heptadecafluorodecyltrimethoxysilane, 1 part photoinitiator TPO, 0.5 parts photoinitiator 184, 3.5 parts acrylate-modified FEVE prepolymer, 2.5 parts MDI prepolymer (UV / moisture curing agent mass ratio 1:0.71≈1:0.7, adjusted to 1:0.8, take 2.8 parts MDI), 1.5 parts hindered amine light stabilizer 944, 0.5 parts fluorine-modified leveling agent, 2 parts superdispersant, and the remainder of topcoat solvent.

[0035] Application parameters: Primer wet film thickness 30μm, dry film thickness 18μm; Topcoat wet film thickness 25μm, dry film thickness 22μm; Total dry film thickness 40μm. UV curing energy 600mJ / cm², curing time 8s.

[0036] The remaining steps are the same as in Example 1.

[0037] Example 3 The only difference from Example 1 is the adjustment of the formula parameters: Heat-insulating buffer primer: 40 parts FEVE fluorocarbon emulsion, 8 parts mesoporous silica aerogel powder, 2 parts MPTMS, 3 parts HDI trimer, 1 part dispersant, 0.5 parts defoamer, and the balance being a mixture of deionized water and ethanol (volume ratio 5:1).

[0038] Heat-absorbing topcoat: 35 parts FEVE fluorocarbon resin, 15 parts composite nanoparticles, 1 part heptadecafluorodecyltrimethoxysilane, 0.5 parts photoinitiator TPO, 2.5 parts acrylate-modified FEVE prepolymer, 3 parts MDI prepolymer (UV / moisture curing agent mass ratio 1:1.2), 9441 parts hindered amine light stabilizer, 0.3 parts fluorine-modified leveling agent, 1 part superdispersant, and the remainder of topcoat solvent.

[0039] Construction parameters: Plasma treatment uses an Ar / O2 mixed gas (O2 content 5%), power 1200W, treatment speed 3m / min, 2 passes, dyne value 45mN / m. Primer wet film 20μm, dry film 10μm; topcoat wet film 15μm, dry film 15μm; total dry film thickness 25μm. UV curing energy 300mJ / cm², curing time 3s.

[0040] The remaining steps are the same as in Example 1.

[0041] Comparative Example 1 The heat-absorbing topcoat prepared in Example 1 was directly coated onto the surface of a Low-E glass substrate (without a heat-insulating buffer primer), with a wet film thickness of 25 μm. The UV curing + moisture curing process was the same as in Example 1. The resulting dry film thickness of the topcoat was approximately 20 μm.

[0042] Comparative Example 2 In Example 1, the mercaptopropyltrimethoxysilane (MPTMS) in the heat-insulating buffer primer was replaced with an equal mass of γ-aminopropyltriethoxysilane (KH-550), while the rest of the formulation and application steps remained unchanged.

[0043] Comparative Example 3 In Example 1, step S2, the high-pressure homogenization dispersion was replaced with horizontal sand milling dispersion: 0.1mm zirconia grinding beads were used, the sand mill linear speed was 10m / s, and the milling was performed 3 times. The rest of the formula and steps remained unchanged.

[0044] Comparative Example 4 The MDI prepolymer in the heat-absorbing topcoat of Example 1 was removed (i.e., no moisture-curing component was added), and only 3 parts of the acrylate-modified FEVE prepolymer were retained in the UV / moisture dual-curing agent. During application, only UV curing (500 mJ / cm², 5 s) was performed, omitting the 60°C moisture curing step. Everything else remained unchanged.

[0045] Comparative Example 5 In Example 1, the photoinitiator and UV / moisture dual curing agent of the heat-absorbing topcoat were completely removed and replaced with 5 parts of a blocked isocyanate curing agent (such as Covestro Desmodur BL-3275). During application, the topcoat was baked at 150°C for 20 minutes for curing. Everything else remained unchanged.

[0046] Test methods Adhesion test: According to ISO2409:2013, a 6-blade cross-cutting tool (1mm spacing) is used to cut a grid on the coating surface. 3M 610 tape is then applied and quickly peeled off, and the extent of coating peeling off the grid areas is observed. Grade 0: Cut edges are completely smooth with no peeling; Grade 1: Minor peeling at intersections (≤5%); Grade 2: Peeling area 5%–15%; ≥3: Unacceptable; Weather resistance test (QUV accelerated aging): According to GB / T1865-2009, a Q-Panel QUV / spray ultraviolet aging test chamber was used, with UV-A 340nm lamps and an irradiance of 0.89W / (m²·nm). Cyclic conditions: 8h UV irradiation (60℃) + 4h condensation (50℃), for a total duration of 2000h. After the test, the coating appearance was observed, ΔE was measured using a colorimeter (such as Konica Minolta CM-3700d), and adhesion was retested. Salt spray test: According to GB / T1771-2007, use 5% NaCl solution and spray continuously at 35℃ for 500 hours. Observe the coating surface for rust, blistering, and peeling. Near-infrared absorptivity test: Using a UV-Vis-NIR spectrophotometer (such as ShimadzuUV-3600Plus) with an integrating sphere, the absorption spectrum of the coated sample in the 800-2500nm wavelength range was measured, and the average absorptivity was calculated. Thermal conductivity test: The transient planar heat source method (HotDiskTPS2500S) was used. The primer was coated on the aluminum plate and cured to form a Φ10mm disc (15μm thick × multiple layers stacked to the measurable thickness). The effective thermal conductivity was measured at 25℃. Functional film temperature rise test: A Low-E glass sample (300mm × 300mm) coated with the coating was placed horizontally directly below a solar simulator (AM1.5G, 1000W / m²) at an ambient temperature of 25℃ and no wind. The surface temperature of the Low-E functional film was monitored from the back of the glass (uncoated side) using an infrared thermal imager (e.g., FLIRT1040), recorded every 30 seconds until the temperature stabilized (a change of <0.5℃ in three consecutive readings was considered steady state). The steady-state temperature was recorded, and the difference between the steady-state temperature and the initial temperature was calculated as the temperature rise. Core-shell structure characterization: EM: A JEOL JEM-2100F transmission electron microscope was used with an accelerating voltage of 200kV.

[0047] XRD: Using a Bruker D8 Advance X-ray diffractometer, CuKα radiation.

[0048] XPS: Using ThermoESCALAB250Xi, AlKα excitation source.

[0049] Emissivity test: According to GB / T2680-2021, the emissivity of the coating in the 8-14 μm band was measured using an FTIR spectrometer (such as Bruker Vertex 70) with an integrating sphere.

[0050] Test Results

[0051] The table above compares the coating performance of each embodiment with that of the comparative embodiment.

[0052] The table above shows the characterization results of the composite nanoparticle structure.

[0053] The table above shows the XPS interface bonding analysis. Therefore, as shown in Table 1, the steady-state temperature rise of the Low-E functional film layer in Examples 1-3, coated with heat-insulating buffer primer, was 35-42°C; while the temperature rise of the film layer in Comparative Example 1 (without heat-insulating primer) reached 62°C. The temperature rise difference in Example 1 was 24°C, far exceeding the "≥15°C" requirement in the claims.

[0054] The mechanism of this effect lies in the fact that the pore size of mesoporous silica aerogel, 5–20 nm, is much smaller than the mean free path of air molecules (approximately 70 nm, 25°C, 1 atm), resulting in the Knudsen effect, which significantly inhibits heat conduction of the gas within the pores; simultaneously, the high porosity of 85%–95% makes... The heat transfer path of the solid-phase skeleton is extremely tortuous. The two work together to control the thermal conductivity of the primer dry film within 0.048–0.058 W / (m·K), forming an effective thermal resistance layer. In contrast, in Comparative Example 1, the heat-absorbing topcoat is directly bonded to the film layer, resulting in unobstructed heat conduction. The film temperature approaches the surface temperature of the coating, posing a risk of silver layer oxidation and thermal stress cracking.

[0055] Comparative Example 2 used conventional γ-aminopropyltriethoxysilane (KH-550), which only forms Si-OM bonds with the Low-E film. XPS confirmed that the S 2p in Example 1 showed characteristic Ag-S and Zn-S peaks at 162.5 eV and 163.2 eV, respectively, while Comparative Example 2 did not show this signal. The MS bond energy (approximately 200–250 kJ / mol) was significantly higher than that of the Si-OM bond (approximately 150–180 kJ / mol), and the hydrolysis rate of the MS bond under acidic and humid conditions was much lower than that of the Si-OM bond. Therefore, the adhesion of Comparative Example 2 decreased to grade 3 (coating peeling) after 2000 h of QUV aging, while Example 1 still maintained grade 1.

[0056] Comparative Example 3 was milled using 0.1mm zirconium beads. TEM statistics showed that the core-shell integrity rate was only 76% (compared to 98.5% in Example 1), with approximately 24% of the particles exhibiting cracks or localized peeling in the shell. After 500 hours of QUV aging, the exposed core-shell integrity was... The core was oxidized, and the coating showed a bluish-gray discoloration (ΔE=5.3), with the NIR absorption rate decreasing from 77% to 62%. This confirms that the concentrated impact force of the abrasive media can disrupt brittleness. The shell, while the high-pressure homogeneous isotropic fluid shear force can maintain the integrity of the core and shell while achieving nanoscale dispersion.

[0057] Comparative Example 4, using only UV curing (without moisture-curing components), showed surface crosslinking but insufficient deep crosslinking. Microcracks (ΔE=3.1) appeared after 2000 hours of QUV aging, and microbubbles appeared in the salt spray test. Comparative Example 5, using high-temperature curing at 150℃, showed migration and recrystallization of the silver in the Low-E film at high temperatures. The coating adhesion decreased to level 2 after aging, and the high temperature caused partial degradation of the fluorocarbon segments in the FEVE (ΔE=7.5). The UV / moisture dual-curing system of Example 1 of this invention achieved gradient densification from the surface to the interior at ≤60℃, balancing curing efficiency and substrate safety.

[0058] In Example 1, the surface energy of the cured heat-insulating buffer primer was approximately 38 mN / m (measured using the water-diiodomethane two-drop method), and the surface tension of the endothermic topcoat solvent was 28.5–30.2 mN / m. According to the Young-Dupré equation:

[0059] The measured contact angle of the topcoat on the primer surface was 22° (<30°), and the adhesion work was calculated. =58.3mJ / m², spreading coefficient =-1.8mJ / m² (close to zero), the topcoat can be fully spread and wetted on the surface of the primer, and there are no pinholes or orange peel after application.

[0060] If the topcoat is applied more than 30 minutes after the primer is applied, the fluorocarbon segments on the primer surface further align, the surface energy drops below 30 mN / m, the measured contact angle increases to 48°, and the interlayer adhesion drops from grade 0 to grade 2. This verifies the necessity of the 30-minute interlayer coating window.

[0061] In Example 1, 17 parts of composite nanoparticles and 40 parts of FEVE fluorocarbon resin (65% solid content, i.e., 26 parts resin solids) were used. The density of the composite nanoparticles was approximately 6.5 g / cm³, and the density of the FEVE resin was 1.5 g / cm³. Calculations showed that the PVC of this formulation was approximately 21%, lower than the system's CPVC (approximately 32%, determined by the oil absorption method of the composite nanoparticles at 48 g / 100 g). PVC < CPVC ensures continuous resin phase encapsulation of the nanoparticles, resulting in a coating porosity <3%, and no abnormalities were observed after 500 hours of salt spray testing. If the PVC exceeds 28% (e.g., if the amount of composite nanoparticles increases to more than 25 parts), filamentous corrosion along scratches will appear after salt spray testing, indicating insufficient density.

[0062] In Examples 1-3, the emissivity change Δε of the coated Low-E glass was 0.02-0.03, far less than the warning threshold of 0.05. This is due to... / Dense core-shell structure The shell layer has a transmittance of ≥85% in the mid-to-far infrared region (8–14 μm), which does not significantly increase the overall emissivity of the coating. Meanwhile, a narrow-band NIR-absorbing medium is selected as the heat-absorbing medium. Instead of using carbon black or graphene with broad-spectrum absorption, the problem of high emission in the mid- and far-infrared regions is fundamentally avoided, and the low-emissivity heat insulation function of Low-E glass is maintained.

[0063] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-weather-resistant heat-absorbing coating for Low-E glass substrates, comprising a heat-insulating buffer primer and a heat-absorbing topcoat sequentially coated on the surface of the Low-E glass substrate, characterized in that: The heat-insulating and buffering primer, by weight, comprises the following components: 30-40 parts of FEVE fluorocarbon emulsion, 8-12 parts of mesoporous silica aerogel powder, 2-3 parts of mercaptopropyltrimethoxysilane, 3-5 parts of moisture-curing isocyanate, 2-3 parts of primer additives, and the remainder of primer solvent. The heat-absorbing topcoat, by weight, comprises the following components: FEVE fluorocarbon resin 35-45 parts, composite nanoparticles 15-20 parts, heptadecafluorodecyltrimethoxysilane 1-2 parts, photoinitiator 0.5-1.5 parts, UV / moisture dual curing agent 4-6 parts, topcoat additives 3-4 parts, topcoat solvent balance; Among them, the mercapto groups generated after the hydrolysis of mercaptopropyltrimethoxysilane form MS coordination bonds with the metal oxides on the surface of the Low-E glass substrate, the moisture-cured isocyanate reacts with the hydroxyl groups in the FEVE fluorocarbon emulsion to form a urethane cross-linking network, and the heat-insulating buffer primer is used to block the conduction of solar radiation heat absorbed by the heat-absorbing topcoat to the Low-E functional film layer. The primer solvent is a mixture of deionized water and ethanol in a volume ratio of (3-5):1, and the topcoat solvent is a mixture of propylene glycol methyl ether acetate and ethylene glycol butyl ether acetate in a volume ratio of (1-2):

1.

2. The high weather-resistant heat-absorbing coating for Low-E glass substrates according to claim 1, characterized in that: The pore size of the mesoporous silica aerogel powder is 5–20 nm, the porosity is 85%–95%, the specific surface area is 500–800 m² / g, the bulk density is 0.05–0.15 g / cm³, and the thermal conductivity is ≤0.025 W / (m·K).

3. The high weather-resistant heat-absorbing coating for Low-E glass substrates according to claim 2, characterized in that: The composite nanoparticles are core-shell structured materials with a cesium tungsten bronze core and a silicon dioxide shell, wherein: Cesium tungsten bronze has a hexagonal crystal system. The core particle size is 10–30 nm; The thickness of the silica shell is 5–8 nm; The overall particle size of the composite nanoparticles is 20–46 nm; The composite nanoparticles were prepared via the sol-gel method, specifically as follows: First, hexagonal phases are synthesized using a hydrothermal method. Nanocrystals are dispersed in an alcoholic solution of tetraethyl orthosilicate, and hydrolyzed and condensed with ammonia to coat the surface of the nanocrystals with a silica shell. The nanocrystals are then obtained by centrifugation, washing, and vacuum drying.

4. The high weather-resistant heat-absorbing coating for Low-E glass substrates according to claim 3, characterized in that: The UV / moisture dual curing agent is formulated by compounding acrylate-modified FEVE prepolymer and moisture-curing isocyanate at a mass ratio of 1:(0.8-1.2). The fluorine content of the acrylate-modified FEVE prepolymer is 20%–25%, the hydroxyl value is 30–60 mgKOH / g, and the double bond functionality of the acrylate is 2–4. The moisture-curing isocyanate is selected from polymethylene polyphenyl polyisocyanate prepolymer or hexamethylene diisocyanate trimer, with an NCO content of 12% to 22%; The photoinitiator is selected from 2,4,6-trimethylbenzoyldiphenylphosphine oxide or 1-hydroxycyclohexylphenyl ketone; Primer additives include polycarboxylate anionic dispersants and silicone defoamers; Topcoat additives include hindered amine light stabilizers, fluorinated leveling agents, and polyurethane-type superdispersants.

5. The high weather-resistant heat-absorbing coating for Low-E glass substrates according to claim 4, characterized in that: The composite coating formed after the paint cures meets the following performance indicators: The total dry film thickness of the coating is 25–45 μm; According to the ISO2409 cross-cut adhesion test, the coating adhesion grade is not lower than 0. After undergoing QUV accelerated aging for 2000 hours according to GB / T1865, the coating showed no blistering, cracking, or peeling, with a color difference ΔE < 2 and adhesion maintained at a level of not less than 1. According to GB / T1771, after 500 hours of salt spray testing, the coating showed no rust or blistering. Average absorption rate in the near-infrared band (800–2500 nm) ≥75%; The thermal conductivity of the dry film of the heat-insulating buffer primer is ≤0.06W / (m·K); under standard solar irradiance of 1000W / m², the temperature rise of the functional film layer of the Low-E glass substrate coated with the paint is ≥15℃ compared with the temperature rise of the functional film layer of the same Low-E glass substrate without the heat-insulating buffer primer.

6. A method for preparing a high weather-resistant heat-absorbing coating for a Low-E glass substrate as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Preparation of heat-insulating buffer primer: Mesoporous silica aerogel powder and mercaptopropyltrimethoxysilane are added to FEVE fluorocarbon emulsion and ultrasonically dispersed for 30 min under ultrasonic power of 200W and temperature <35℃ to make the aerogel powder uniformly dispersed and without obvious agglomeration. Then, moisture-curing isocyanate and primer additives are added and stirred at 300-500 rpm for 20 min. After filtration through a 200-mesh filter, the heat-insulating buffer primer is obtained. S2. Preparation of heat-absorbing topcoat: The composite nanoparticles, superdispersant and part of the topcoat solvent are mixed and homogenized by circulating the mixture 3 to 5 times under a pressure of 80 to 150 MPa using a high-pressure homogenizer to disperse the composite nanoparticles to D90 < 50 nm, thus obtaining a heat-absorbing slurry; the heat-absorbing slurry is added to FEVE fluorocarbon resin, heptadecafluorodecyltrimethoxysilane, photoinitiator and UV / moisture dual curing agent, and stirred at a speed of 800 to 1000 rpm for 40 min, the remaining topcoat additives and topcoat solvent are added, and after stirring evenly, the mixture is filtered through a 200-mesh filter to obtain the heat-absorbing topcoat.

7. The method for preparing a high weather-resistant heat-absorbing coating for a Low-E glass substrate according to claim 6, characterized in that: In step S1, the system temperature is controlled to be <35℃ during ultrasonic dispersion to prevent premature reaction of isocyanate. Before adding mercaptopropyltrimethoxysilane to FEVE fluorocarbon emulsion, it is pre-hydrolyzed with deionized water at pH 4-5 for 15-30 minutes.

8. The method for preparing a high weather-resistant heat-absorbing coating for a Low-E glass substrate according to claim 7, characterized in that: In step S2, the homogenizing valve gap of the high-pressure homogenizer is 10-25 μm, the feed temperature is ≤30℃, the discharge temperature is ≤40℃, the amount of superdispersant added is 3%-5% of the mass of the composite nanoparticles, and high-pressure homogenization is used in step S2 instead of sand milling to disperse the composite nanoparticles in order to avoid mechanical damage to the silica shell by the grinding media.

9. A method for applying a high weather-resistant heat-absorbing coating to a Low-E glass substrate surface as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Substrate pretreatment: The surface of the Low-E glass substrate is subjected to plasma treatment to make the substrate surface ≥40mN / m; S2. Applying heat-insulating buffer primer: Applying heat-insulating buffer primer to the surface of the plasma-treated substrate, with a wet film thickness of 20-30 μm, and drying by gradient temperature increase: first holding at 40℃ for 3 min to allow the solvent to evaporate slowly, and then holding at 60℃ for 5 min to complete the initial cross-linking, forming a heat-insulating buffer primer layer with a dry film thickness of 10-18 μm. S3. Applying heat-absorbing topcoat: Apply heat-absorbing topcoat to the surface of the heat-insulating buffer primer layer, with a wet film thickness of 15-25μm; first, UV curing is performed to quickly set the surface of the topcoat, and then moisture curing is performed at 60℃ and relative humidity ≥60%RH for 10-15 minutes to allow the deep layer of the coating to complete the reaction between isocyanate and water and achieve complete curing, forming the topcoat layer. S4. The total dry film thickness of the resulting composite coating is 25–45 μm.

10. The method for applying a high weather-resistant heat-absorbing coating to a Low-E glass substrate as described in claim 9, characterized in that: In step S1, the plasma treatment uses atmospheric pressure air plasma or Ar / O2 mixed gas plasma, with a treatment power of 500-1500W, a treatment speed of 2-8m / min, and 1-2 treatments. After plasma treatment, the primer coating should be completed within 30 minutes to prevent the substrate surface from peeling off. In step S2, the heat-insulating buffer primer is applied by roller coating or slot coating; the surface temperature of the substrate is controlled at 20-35℃ before coating. In step S3, UV curing uses a 395nm LED ultraviolet light source with an irradiation energy of 300–600 mJ / cm² and a curing time of 3–8 s; Between steps S2 and S3, after the heat-insulating buffer primer layer is applied, the heat-absorbing topcoat should be applied within 30 minutes to ensure interlayer adhesion; if the interval exceeds 30 minutes, the surface of the primer layer needs to be plasma activated again.

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