Self-cleaning composite coating and preparation method thereof

Abstract

The invention discloses an ultra-long-acting intelligent self-cleaning coating based on a bionic multilevel structure and rare earth-graphene synergistic enhancement and a preparation method of the ultra-long-acting intelligent self-cleaning coating. According to the coating, through an organic-inorganic-hybridization three-module design, multifunctional nano materials such as three-rare-earth co-doped TiO, graphene oxide-CeO-ZrO and nano boron nitride are adopted, and a pre-hydrolyzed three-functional silane and fluorosilicone-polyurethane double-resin system is combined; through plasma-solvent thermal activation, high-energy three-step compounding, electrostatic spraying and ultraviolet-heat-moisture gradient curing processes, the composite coating with micro-nano roughness, full-spectrum catalysis, ultraviolet shielding, high thermal conductivity and strong adhesion characteristics is formed. The water contact angle of the coating is smaller than or equal to 3 degrees, the visible light transmittance is larger than or equal to 94%, the performance retention rate is larger than 90% after QUVB accelerated aging is conducted for 3000 hours, and the coating has excellent self-cleaning performance, abrasion resistance, salt fog resistance and outdoor long-acting stability and is suitable for surface functionalization and protection of various base materials.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary fields of functional coating materials, nanocomposite materials and surface engineering. Specifically, it relates to a composite coating with superhydrophilicity, photocatalytic self-cleaning, high light transmittance, strong adhesion and extreme weather resistance and its preparation process. It is suitable for surface functionalization and long-term protection of various substrates such as photovoltaic glass, building curtain walls, automotive glass, optical lenses, and marine facilities. Background Technology

[0002] With the increasing global demand for energy-saving and environmentally friendly, low-maintenance buildings and high-performance optical devices, self-cleaning coating technology has become a research hotspot in the field of surface engineering. Traditional self-cleaning coatings are mainly divided into two categories: one is superhydrophobic coatings based on the "lotus effect," which use low surface energy materials and micro-nano rough structures to allow water droplets to roll off and remove contaminants, but suffers from problems such as easy adhesion of oil stains, poor durability, and low light transmittance; the other is superhydrophilic coatings based on "water film spreading," which form a continuous water film to wash the surface, but its hydrophilicity is easily degraded, its weather resistance is poor, its mechanical strength is insufficient, and its self-cleaning ability is limited in low light or no light environments.

[0003] Several superhydrophilic self-cleaning coatings are currently available on the market, such as "Rainbow Porcelain Superhydrophilic Coating," which claims a water contact angle of ≤9° and possesses a certain degree of self-cleaning ability. However, they still suffer from the following common defects:

[0004] 1. Generally insufficient weather resistance; QUVB shows a significant performance decline after 500-1000 hours of aging.

[0005] 2. Photocatalytic activity depends on ultraviolet light, and the response to visible light is weak;

[0006] 3. Most are two-component or require high-temperature curing, making construction inconvenient;

[0007] 4. Poor adhesion to complex substrates (such as polymers, ceramics, and composite materials);

[0008] 5. After long-term outdoor use, the hydrophilicity and light transmittance decrease significantly.

[0009] Furthermore, in existing technologies, silane coupling agents are prone to hydrolysis and self-polymerization in single-component aqueous systems, resulting in short coating shelf life and insufficient interfacial adhesion after application. Therefore, developing a single-component coating system that combines superhydrophilicity, full-spectrum photocatalysis, superior adhesion, high light transmittance, and long-term stable operation in harsh outdoor environments has significant scientific and engineering value. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a self-cleaning composite coating and its preparation method. The coating employs a three-module design of "organic-inorganic-hybrid," utilizing multifunctional nanomaterials such as tri-rare earth co-doped TiO2, graphene oxide-CeO2-ZrO2, and nano-boron nitride, combined with a pre-hydrolyzed trifunctional silane and a fluorosilicone-polyurethane dual-resin system, forming a composite coating with micro-nano roughness, full-spectrum catalysis, UV shielding, high thermal conductivity, and strong adhesion. This coating exhibits a water contact angle ≤3°, visible light transmittance ≥94%, and performance retention >90% after 3000 hours of QUVB accelerated aging. It possesses excellent self-cleaning properties, wear resistance, salt spray resistance, and long-term outdoor stability, making it suitable for surface functionalization and protection of various substrates.

[0011] The purpose of this invention is to provide a self-cleaning composite coating, comprising 55-60 wt% film-forming resin, 18-22 wt% inorganic functional nanomodules, and the remainder being interface and process aids;

[0012] The film-forming resin comprises an aqueous aliphatic polyurethane dispersion and an aqueous fluorosilicone-modified acrylate emulsion, wherein the aqueous aliphatic polyurethane dispersion and the aqueous fluorosilicone-modified acrylate emulsion account for 50-55 wt% and 5-7 wt% of the composite coating, respectively.

[0013] The inorganic functional nanomodule comprises 55.6%~60 wt% amino-modified hydrophilic nano-SiO2, 22.2%~27.3 wt% Nd-Eu-La rare earth co-doped nano-TiO2, 11.1%~13.6 wt% graphene oxide-CeO2-ZrO2 ternary hybrid material, and 5.6%~9.1 wt% boron nitride nanoparticles;

[0014] The interface and process aids include pre-hydrolyzed mercapto-epoxy-vinyl trifunctional silane, propylene glycol phenyl ether, polyether-siloxane copolymer leveling agent, aqueous UV-Oxygen dual-curing initiator, ethanol, and deionized water; the proportions of pre-hydrolyzed mercapto-epoxy-vinyl trifunctional silane, propylene glycol phenyl ether, polyether-siloxane copolymer leveling agent, aqueous UV-Oxygen dual-curing initiator, and ethanol in the composite coating are 2.5~3.5wt%, 7~9wt%, 0.4~0.8wt%, 1.2~1.8wt%, and 3~5wt%, with the balance being deionized water.

[0015] Another object of the present invention is to provide a method for preparing a self-cleaning composite coating, which includes the following steps:

[0016] Step 1, Plasma-solvent thermal synergistic activation of nanomaterials, includes the following sub-steps:

[0017] Step 1-1: Mix amino-modified hydrophilic nano-SiO2, Nd-Eu-La rare earth co-doped nano-TiO2, graphene oxide-CeO2-ZrO2 ternary hybrid material, and nano-boron nitride in a certain proportion, place them in a plasma fluidized bed, and treat them for 15 minutes at 300W under an Ar / O2 mixed atmosphere to obtain a nanomaterial mixture.

[0018] Steps 1-2: The nanomaterial mixture, along with pre-hydrolyzed mercapto-epoxy-vinyl trifunctional silane and ethanol, are added to a solvothermal reactor and reacted at 120°C under autogenous pressure for 6 hours to achieve surface organic modification.

[0019] Steps 1-3: The product obtained in Step 1-2 is centrifuged, washed, and vacuum dried to obtain composite nanopowder;

[0020] Step 2, Vacuum degassing and pre-emulsification of the resin matrix, includes the following sub-steps:

[0021] Step 2-1: Mix the waterborne aliphatic polyurethane dispersion with the waterborne fluorosilicone modified acrylate emulsion in a certain proportion, and add propylene glycol phenyl ether, polyether-siloxane copolymer leveling agent, waterborne UV-oxygen dual curing initiator and deionized water to the mixture in sequence.

[0022] Step 2-2: Mix the mixture obtained in Step 2-1 in a vacuum planetary mixer to form a uniform, bubble-free resin pre-emulsion.

[0023] Step 3, the three-step composite process of high-energy shearing, ultrasound, and microwave, includes the following sub-steps:

[0024] Step 3-1: Slowly add the composite nanopowder to the resin pre-emulsion and process it with a high-speed shear emulsifier for 1 hour;

[0025] Step 3-2: Transfer to an ultrasonic-microwave synergistic reactor, and circulate the material for 3 cycles under alternating action of 40kHz ultrasound and 800W microwave, with each cycle lasting 10 minutes, to obtain the coating slurry;

[0026] Step 4: The coating slurry is cured through an electrostatic spraying-UV-heat-humidity gradient to form an interpenetrating-crosslinked network structure; including the following sub-steps:

[0027] Step 4-1, Substrate pretreatment: The substrate is cleaned with acetone solution, the substrate is cleaned by plasma, and the silane coupling agent is atomized.

[0028] Step 4-2: Use a six-axis robot electrostatic spraying system to uniformly spray the coating slurry obtained in step 3 onto the pretreated substrate surface to form a wet film.

[0029] Step 4-3: Immediately transfer the sprayed wet film into a UV-IR curing tunnel oven for curing. The UV-IR curing tunnel oven includes the following three processing zones:

[0030] Zone 1: 365nm LED UV, intensity 1000mW / cm², treatment time 30 seconds;

[0031] Zone 2: Mid-infrared, wavelength 2-4μm, preheated at 80℃ for 1 minute;

[0032] Zone 3: Hot air circulation, maintained at 60℃ for 2 hours;

[0033] Step 4-4: Cur the cured coating in a constant temperature and humidity chamber for 7 days.

[0034] The beneficial effects of this invention are as follows: The coating of this invention adopts a three-module design of "organic-inorganic-hybrid" and uses multifunctional nanomaterials such as tri-rare earth co-doped TiO2, graphene oxide-CeO2-ZrO2, and nano-boron nitride, combined with a pre-hydrolyzed trifunctional silane and a fluorosilicone-polyurethane dual resin system. Through plasma-solvent thermal activation, high-energy three-step composite, electrostatic spraying, and UV-heat-humidity gradient curing processes, a composite coating with micro-nano roughness, full-spectrum catalysis, UV shielding, high thermal conductivity, and strong adhesion is formed. This coating has a water contact angle ≤3°, visible light transmittance ≥94%, and performance retention >90% after 3000 hours of QUVB accelerated aging. It possesses excellent self-cleaning properties, wear resistance, salt spray resistance, and long-term outdoor stability, making it suitable for surface functionalization and protection of various substrates. Detailed Implementation

[0035] The technical solution of the present invention will be further explained below with reference to specific implementations.

[0036] A self-cleaning composite coating comprises 55-60 wt% film-forming resin, 18-22 wt% inorganic functional nanomodules, and the remainder being interface and process aids.

[0037] The film-forming resin comprises an aqueous aliphatic polyurethane dispersion (Bayhydrol® UH 2606) and an aqueous fluorosilicone-modified acrylate emulsion (Dow DOW FA-4632), with the aqueous aliphatic polyurethane dispersion and the aqueous fluorosilicone-modified acrylate emulsion accounting for 50-55 wt% and 5-7 wt% respectively in the composite coating. The aqueous aliphatic polyurethane dispersion accounts for approximately 90.9%-91.7% by weight in the film-forming resin; the use of dual-resin compounding can improve the weather resistance and adhesion of the coating.

[0038] The inorganic functional nanomodule comprises 55.6%–60 wt% amino-modified hydrophilic nano-SiO2 (Evonik AEROSIL® COK 84), 22.2%–27.3 wt% Nd-Eu-La rare earth co-doped nano-TiO2 (Huzheng Nano HZ-TRE-03), 11.1%–13.6 wt% graphene oxide-CeO2-ZrO2 ternary hybrid material (Zhongke Nano CN-GCZ-10), and 5.6%–9.1 wt% boron nitride nanoparticles (hexagonal crystal system, Saint-Gobain BN-NP-20, USA). The proportions of amino-modified hydrophilic nano-SiO2, Nd-Eu-La rare earth co-doped nano-TiO2, graphene oxide-CeO2-ZrO2 ternary hybrid material, and boron nitride nanoparticles in the composite coating are approximately 10–12 wt%, 4–6 wt%, 2–3 wt%, and 1–2 wt%, respectively.

[0039] Amino-modified hydrophilic nano-SiO2 particles (20-50 nm) aggregate to form a micron-scale protruding structure. The core-shell structure formed by the graphene oxide-CeO2-ZrO2 ternary hybrid material can selectively reflect and absorb ultraviolet light, achieving ultraviolet shielding. Nd-Eu-La rare earth co-doped nano-TiO2 and the graphene oxide-CeO2-ZrO2 ternary hybrid material can synergistically achieve full-spectrum catalysis, while nano-boron nitride can enhance thermal conductivity. Through the above-mentioned inorganic functional nanomaterials, multiple functions such as micro-nano roughness, full-spectrum catalysis, ultraviolet shielding, and enhanced thermal conductivity can be achieved in the coating.

[0040] The interface and process aids include pre-hydrolyzed mercapto-epoxy-vinyl trifunctional silane (Evonik Dynasylan® 3145), propylene glycol phenyl ether (Dow Dowanol® PPh), polyether-siloxane copolymer leveling agent (BYK-3495), waterborne UV-Oxygen dual-curing initiator (Tianjin Jiuri 907W / TPO-L compound), ethanol (analytical grade), and deionized water; the proportions of pre-hydrolyzed mercapto-epoxy-vinyl trifunctional silane, propylene glycol phenyl ether, polyether-siloxane copolymer leveling agent, waterborne UV-Oxygen dual-curing initiator, and ethanol in the composite coating are 2.5~3.5wt%, 7~9wt%, 0.4~0.8wt%, 1.2~1.8wt%, and 3~5wt%, with the balance being deionized water.

[0041] This invention pioneers a multifunctional nanosynergistic system of "tri-rare earth co-doped TiO2 + graphene oxide-CeO2-ZrO2 ternary hybrid material + nano boron nitride"; and introduces a dual film-forming process of waterborne aliphatic polyurethane dispersion and waterborne fluorosilicone modified acrylate emulsion, which can significantly improve the weather resistance and adhesion of the coating; and uses pre-hydrolyzed mercapto-epoxy-vinyl trifunctional silane to achieve triple chemical bonding between nano-resin-substrate.

[0042] The composite coating of the present invention can form a core-shell-bridged structure: the core is inorganic nanoparticles in the inorganic functional nanomodule (including amino-modified hydrophilic nano-SiO2 and Nd-Eu-La rare earth co-doped nano-TiO2); the shell is an organic modification layer formed by pre-hydrolyzed thiol-epoxy-vinyl trifunctional silane; the bridge is the thiol, epoxy, vinyl and other functional groups in the silane, one end of the bridge is connected to the surface of the inorganic nanoparticles, and the other end is connected to the film-forming resin matrix or adjacent nanoparticles, realizing the triple chemical bonding of nano-resin-substrate.

[0043] This invention discloses a method for preparing a self-cleaning composite coating, which comprises four stages: nanomaterial pretreatment, resin compounding, high-energy composite, and gradient curing. The entire process is carried out in a temperature and humidity-controlled environment, and specifically includes the following steps:

[0044] Step 1, Plasma-solvent thermal synergistic activation of nanomaterials, includes the following sub-steps:

[0045] Step 1-1: Mix amino-modified hydrophilic nano-SiO2, Nd-Eu-La rare earth co-doped nano-TiO2, graphene oxide-CeO2-ZrO2 ternary hybrid material, and nano-boron nitride in a certain proportion, place them in a plasma fluidized bed, and treat them for 15 minutes at 300W under an Ar / O2 mixed atmosphere (volume ratio 4:1) to obtain a nanomaterial mixture;

[0046] Steps 1-2: The nanomaterial mixture, along with pre-hydrolyzed mercapto-epoxy-vinyl trifunctional silane and ethanol, are added to a solvothermal reactor and reacted at 120°C under autogenous pressure for 6 hours to achieve surface organic modification.

[0047] Steps 1-3: The product obtained in Step 1-2 is centrifuged, washed, and vacuum dried to obtain composite nanopowder with a "core-shell-bridged" structure.

[0048] Step 2, Vacuum degassing and pre-emulsification of the resin matrix, includes the following sub-steps:

[0049] Step 2-1: Mix the waterborne aliphatic polyurethane dispersion with the waterborne fluorosilicone modified acrylate emulsion in a certain proportion, and add propylene glycol phenyl ether, polyether-siloxane copolymer leveling agent, waterborne UV-oxygen dual curing initiator and deionized water to the mixture in sequence.

[0050] Step 2-2: Mix the mixture obtained in Step 2-1 in a vacuum planetary mixer (NETZSCH Vacuum-Mixer, Germany) at a low speed of 100-200 rpm, with a vacuum degree of -0.095 MPa, for 30 minutes to degas and form a uniform, bubble-free resin pre-emulsion.

[0051] Step 3, the three-step composite process of high-energy shearing, ultrasound, and microwave, includes the following sub-steps:

[0052] Step 3-1: Slowly add the composite nanopowder to the resin pre-emulsion and process it for 1 hour using a high-speed shear emulsifier (Swiss IKAUltra-Turrax, 15000rpm).

[0053] Step 3-2: Transfer to an ultrasonic-microwave synergistic reactor (Shanghai Xintuo XT-USMW-1000), and cycle through 3 times under the alternating action of 40kHz ultrasound and 800W microwave, each cycle lasting 10 minutes, to obtain a highly uniform, semi-transparent coating slurry with controllable viscosity.

[0054] Step 4: The coating slurry is cured through an electrostatic spraying-UV-heat-humidity gradient to form an interpenetrating-crosslinked network structure; including the following sub-steps:

[0055] Step 4-1, Substrate Pretreatment: The substrate (glass, metal, polymer, etc. to be coated) is cleaned with acetone solution to remove grease and contaminants from the substrate surface; then the substrate is cleaned with plasma (Ar, 400W, 10 minutes) to increase surface energy and improve adhesion; finally, silane coupling agent atomization treatment is performed, in which the silane coupling agent solution is atomized through a spray gun and uniformly sprayed onto the substrate surface to form a chemical bonding layer;

[0056] Step 4-2: Use a six-axis robot electrostatic spraying system (FANUC P-250iB, Japan) to uniformly spray the coating slurry obtained in step 3 onto the pretreated substrate surface to form a wet film; the voltage of the spraying system is 70kV, the spraying speed is 500mm / s, and the film thickness is controlled at 5±0.3μm.

[0057] Step 4-3: Immediately transfer the sprayed wet film into a UV-IR curing tunnel oven for curing. The UV-IR curing tunnel oven includes the following three processing zones:

[0058] Zone 1: 365nm LED UV, intensity 1000mW / cm², treatment time 30 seconds;

[0059] Zone 2: Mid-infrared, wavelength 2-4μm, preheated at 80℃ for 1 minute;

[0060] Zone 3: Hot air circulation, maintained at 60℃ for 2 hours;

[0061] Although the components are uniformly dispersed in the slurry, during the curing process, due to differences in surface energy, functional group orientation, phase separation, and gradient curing conditions (such as UV curing of the surface layer first and hot air promoting internal cross-linking), the components will spontaneously form a layered structure such as a substrate interface layer, a resin film layer, a micro-nano rough layer, a functional nano-dispersion layer, a surface hydrophilic layer, and a UV shielding layer.

[0062] Step 4-4: Cur the cured coating in a constant temperature and humidity chamber (25℃, RH 65%) for 7 days to complete the final cross-linking.

[0063] In-depth analysis of the coating mechanism of the present invention

[0064] 1. Superhydrophilic long-lasting retention mechanism: Amino-modified hydrophilic nano-SiO2 provides permanent hydrophilic sites, the -CF3 and -Si-O- bonds introduced by fluorosilicone acrylate inhibit the adsorption of surface contaminants, and nano-boron nitride conducts heat to accelerate the evaporation and re-spreading cycle of surface moisture.

[0065] 2. Full-spectrum photocatalytic mechanism: Nd-Eu-La rare earth doping introduces intermediate energy levels into the band gap of TiO2, broadening the photoresponse to 600nm; graphene oxide acts as an electronic conductor, delaying electron-hole recombination; CeO2-ZrO2 synergistically generate oxygen vacancies, enhancing the generation of reactive oxygen species.

[0066] 3. Ultra-long-lasting weather resistance mechanism: CeO2 and ZrO2 form a double-layer shield of ultraviolet reflection and absorption; graphene oxide sheets physically block the penetration of oxygen and moisture; the Si-O-Si network constructed by trifunctional silane resists photo-oxidative aging.

[0067] 4. Universal mechanism of strong adhesion: Thiol groups form coordination bonds with metals; epoxy groups react with polymers and ceramics; vinyl groups participate in UV curing to achieve covalent bonding.

[0068] Example 1: Ultra-long-lasting self-cleaning coating for photovoltaic glass

[0069] Substrate: Photovoltaic ultra-clear glass (Xinyi Glass, 3.2mm thick);

[0070] Coating formulation (by weight): Bayhydrol® UH 2606: 52%; DOW FA-4632: 6%; AEROSIL® COK 84: 11%; HZ-TRE-03: 5%; CN-GCZ-10: 2.5%; Saint-Gobain BN-NP-20: 1.5%; Dynasylan® 3145: 3%; Dowanol® PPh: 8.5%; BYK-3495: 0.6%; 907W / TPO-L: 1.5%; Ethanol: 4%; Deionized water: balance to 100%.

[0071] Following the above process steps, the dry film thickness of the coating is 5 μm. Performance test results are shown in Table 1, and outdoor test data are shown in Table 2.

[0072] Table 1

[0073] Test Project Test Standards initial value QUVB3000h after retention rate Water contact angle (°) GB / T 30447 2.1 3.8 82.9% Light transmittance (%, 550nm) GB / T 2680 95.2 94.1 98.8% Adhesion (cross-cut test) ASTM D3359 Level 0 Level 0 100% Pencil hardness ASTM D3363 4H 3H — Photocatalytic degradation rate (RhB, 4h) ISO 10678 91.3% 88.7% 97.2% Salt spray resistant (3000h) ASTM B117 Non-corrosive Non-corrosive — Abrasion resistance (Taber, CS-10, 1000 cycles) ASTM D4060 Δhaze < 0.5% Δhaze < 1.2% —

[0074] Table 2 Outdoor measured data (18 months, hot and humid marine environment in Hainan)

[0075] Test Project 3 months 6 months 12 months 18 months Water contact angle (°) 2.5 3.1 4.2 5.0 transmittance retention rate 99.2% 98.5% 97.3% 96.1% Self-cleaning effect (stain removal rate) 98% 96% 94% 91% Appearance No change No change slight watermarks slight watermarks

[0076] 1. Environmental Impact Assessment Report

[0077] Environmental friendliness assessment of raw materials

[0078] Material Category Environmental characteristics Meets standards Risk control Waterborne resin system No APEO, VOC < 50g / L HJ 2537-2014 Using bio-based propylene glycol phenyl ether as a replacement for traditional film-forming aids Nano silica Amorphous, non-crystalline, and non-hazardous. GB 30000.18 Surface modification reduces bioactivity <![CDATA[ Rare earth doped TiO2]]> <![CDATA[Free of heavy metals (Pb, Cd, Cr 6 ⁺), rare earth elements fixed in the lattice]]> RoHS 2.0 Optimize the doping ratio to avoid rare earth leaching. Graphene oxide hybrid materials <![CDATA[There is no free graphite dust, and CeO2 and ZrO2 have stable chemical properties]]> - Hybrid structures prevent the release of nanomaterials Pre-hydrolyzed silane The hydrolysis product is ethanol, with no formaldehyde released. GB 18582-2020 Use pre-hydrolyzed formulation to avoid methanol production during construction.

[0079] 2. Environmental impact of the production process

[0080] Energy consumption: By using UV curing instead of traditional thermal curing, energy consumption is reduced by approximately 65%.

[0081] Wastewater discharge: The production process is a closed-loop circulating water system, with no process wastewater discharged externally. The cleaning water is reused after flocculation and sedimentation.

[0082] Exhaust gas emissions: Ethanol volatilization is less than 3%, and the emissions are treated by activated carbon adsorption device, and the emissions comply with GB 16297-1996.

[0083] Solid waste: Filter residue (mainly undispersed nanoclusters) can be collected and reused as a filler in building materials.

[0084] 3. Environmental benefits during product use

[0085] Water-saving benefits: The super-hydrophilic coating reduces water consumption for surface cleaning by approximately 70%.

[0086] Energy saving benefits: (1) Photovoltaic glass application: Increased light transmittance improves the power generation efficiency of the module by 1.5-2%; (2) Building curtain wall application: Surface temperature is reduced by 3-5℃ due to hydrophilic evaporation, reducing air conditioning load.

[0087] Air purification: The photocatalytic function can degrade NOx and VOCs, with each square meter of coating degrading approximately 0.15 mg of NOx per hour.

[0088] 4. Waste disposal and recyclability

[0089] Coating removal: It can be peeled off by soaking in 5% NaOH solution, with a peeling rate of >90%.

[0090] Substrate recycling: Glass and metal substrates can be completely recycled after simple cleaning.

[0091] Biodegradability: The peeled coating film has a natural disintegration rate of about 40% in soil after 6 months and has no ecotoxicity.

[0092] 5. Summary of Life Cycle Assessment (LCA)

[0093] Carbon footprint: From raw materials to production, each kilogram of coating emits 3.8 kg of CO2 equivalent, which is 58% lower than that of solvent-based coatings.

[0094] Environmental Product Declaration (EPD): Compliant with ISO 14025 standards and awarded "Green Building Materials" three-star certification.

[0095] Impact on human health: No harmful gases are released during the construction process, and no harmful substances migrate from the coating after curing.

[0096] Comparison table of the conformity of this invention with current national and industry standards

[0097] Standard Category Standard number Standard Name Relevant requirements This invention meets the following conditions Test Report Number Basic performance GB / T 9755-2014 Synthetic resin emulsion exterior wall coatings No abnormalities were observed in water resistance after 96 hours and in alkali resistance after 48 hours. Water resistance > 1000h, alkali resistance > 500h T2023-0856 GB / T 9756-2018 Synthetic resin emulsion interior wall paint Contrast ratio ≥0.95, washability ≥1000 cycles Contrast ratio 0.98, wash resistance >5000 times T2023-0857 Functionality GB / T 30789.5-2015 Coating self-cleaning performance test Water contact angle <10°, self-cleaning efficiency >80% Water contact angle 2.1°, self-cleaning efficiency 94%. T2023-0858 JG / T 304-2011 Anti-graffiti coating for buildings Anti-sticking performance ≥ Grade 3, stain resistance ≤ 15% Anti-sticking rating: 5; Stain resistance: 5% T2023-0859 Weather resistance GB / T 1865-2009 Artificial weathering of paints and varnishes QUVB 1000h: No bubbling, peeling, or cracking. QUVB 3000h no abnormalities T2023-0860 GB / T 1766-2008 Aging rating of paint and varnish coatings Level 0 (No change) QUVB rating after 3000 hours: Level 0 T2023-0861 Optical performance GB / T 2680-2021 Visible light transmittance of architectural glass Photovoltaic glass with a light transmittance of ≥91% After coating, the light transmittance is ≥94% (relative value). T2023-0862 GB / T 18915.1-2013 Part 1: Solar Control Coated Glass Ultraviolet transmittance <30% Ultraviolet (300-380nm) blocking rate >95% T2023-0863 Environmental protection HJ 2537-2014 Environmental Labeling Product Technical Requirements for Waterborne Coatings VOC ≤ 50g / L, free of APEO, formaldehyde, etc. VOC = 38 g / L, APEO / formaldehyde not detected T2023-0864 GB 18582-2020 Limits of hazardous substances in architectural wall coatings Total benzene series compounds ≤100mg / kg Not detected (<1 mg / kg) T2023-0865 Photovoltaic IEC 61215:2021 Design qualification and finalization of terrestrial crystalline silicon photovoltaic modules Power attenuation ≤5% after damp heat test (DH 1000h) Accelerated testing showed that the coating can reduce PID attenuation rate by 40%. T2023-0866 T / CPIA 0016-2020 Self-cleaning coated glass for photovoltaic modules Water contact angle ≤15°, ≤20° after 500h with QUVB Initially 2.1°, 3.8° after 3000h of QUVB treatment. T2023-0867 Building curtain wall JGJ 102-2013 Technical Specifications for Glass Curtain Wall Engineering Adhesion strength ≥ 1.5 MPa Adhesion > 8MPa (glass substrate) T2023-0868 GB / T 21086-2007 Building curtain wall Weather resistance: No significant discoloration after 3000 hours of accelerated aging. After 3000 hours of QUVB, ΔE < 1.5 T2023-0869 Automotive glass QC / T 1129-2019 Functional films for automotive glass Haze ≤2.0%, abrasion resistance (sand shedding) ≥10L Haze 0.8%, abrasion resistance 22L T2023-0870 GB9656-2021 Motor vehicle glass safety technical specifications Visible light transmittance ≥70% Visible light transmittance ≥ 94% T2023-0871

[0098] Conformity conclusion: The coating of this invention meets or significantly exceeds the requirements of current national, industry and international standards in terms of basic performance, functionality, weather resistance, optical performance and environmental protection. In particular, it has a significant leading advantage in core indicators such as ultra-long-lasting weather resistance (QUVB3000h), full-spectrum photocatalysis and strong adhesion to multiple substrates.

[0099] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A self-cleaning composite coating, characterized in that, It includes 55-60 wt% film-forming resin, 18-22 wt% inorganic functional nanomodules, and the remainder is interface and process aids; The film-forming resin comprises an aqueous aliphatic polyurethane dispersion and an aqueous fluorosilicone-modified acrylate emulsion, wherein the aqueous aliphatic polyurethane dispersion and the aqueous fluorosilicone-modified acrylate emulsion account for 50-55 wt% and 5-7 wt% of the composite coating, respectively. The inorganic functional nanomodule comprises 55.6%~60 wt% amino-modified hydrophilic nano-SiO2, 22.2%~27.3 wt% Nd-Eu-La rare earth co-doped nano-TiO2, 11.1%~13.6 wt% graphene oxide-CeO2-ZrO2 ternary hybrid material, and 5.6%~9.1 wt% boron nitride nanoparticles; The interface and process aids include pre-hydrolyzed mercapto-epoxy-vinyl trifunctional silane, propylene glycol phenyl ether, polyether-siloxane copolymer leveling agent, aqueous UV-Oxygen dual-curing initiator, ethanol, and deionized water; the proportions of pre-hydrolyzed mercapto-epoxy-vinyl trifunctional silane, propylene glycol phenyl ether, polyether-siloxane copolymer leveling agent, aqueous UV-Oxygen dual-curing initiator, and ethanol in the composite coating are 2.5~3.5wt%, 7~9wt%, 0.4~0.8wt%, 1.2~1.8wt%, and 3~5wt%, with the balance being deionized water.

2. A method for preparing a self-cleaning composite coating, used to prepare the self-cleaning composite coating as described in claim 1, characterized in that, Includes the following steps: Step 1, Plasma-solvent thermal synergistic activation of nanomaterials, includes the following sub-steps: Step 1-1: Mix amino-modified hydrophilic nano-SiO2, Nd-Eu-La rare earth co-doped nano-TiO2, graphene oxide-CeO2-ZrO2 ternary hybrid material, and nano-boron nitride in a certain proportion, place them in a plasma fluidized bed, and treat them for 15 minutes at 300W under an Ar / O2 mixed atmosphere to obtain a nanomaterial mixture. Steps 1-2: The nanomaterial mixture, along with pre-hydrolyzed mercapto-epoxy-vinyl trifunctional silane and ethanol, are added to a solvothermal reactor and reacted at 120°C under autogenous pressure for 6 hours to achieve surface organic modification. Steps 1-3: The product obtained in Step 1-2 is centrifuged, washed, and vacuum dried to obtain composite nanopowder; Step 2, Vacuum degassing and pre-emulsification of the resin matrix, includes the following sub-steps: Step 2-1: Mix the waterborne aliphatic polyurethane dispersion with the waterborne fluorosilicone modified acrylate emulsion in a certain proportion, and add propylene glycol phenyl ether, polyether-siloxane copolymer leveling agent, waterborne UV-oxygen dual curing initiator and deionized water to the mixture in sequence. Step 2-2: Mix the mixture obtained in Step 2-1 in a vacuum planetary mixer to form a uniform, bubble-free resin pre-emulsion; Step 3, the three-step composite process of high-energy shearing, ultrasound, and microwave, includes the following sub-steps: Step 3-1: Slowly add the composite nanopowder to the resin pre-emulsion and process it with a high-speed shear emulsifier for 1 hour; Step 3-2: Transfer to an ultrasonic-microwave synergistic reactor, and circulate the material for 3 cycles under alternating action of 40kHz ultrasound and 800W microwave, with each cycle lasting 10 minutes, to obtain the coating slurry; Step 4: The coating slurry is cured by electrostatic spraying-ultraviolet-heat-humidity gradient to form an interpenetrating-crosslinked network structure; Includes the following sub-steps: Step 4-1, Substrate pretreatment: The substrate is cleaned with acetone solution, the substrate is cleaned by plasma, and the silane coupling agent is atomized. Step 4-2: Use a six-axis robot electrostatic spraying system to uniformly spray the coating slurry obtained in step 3 onto the pretreated substrate surface to form a wet film. Step 4-3: Immediately transfer the sprayed wet film into a UV-IR curing tunnel oven for curing. The UV-IR curing tunnel oven includes the following three processing zones: Zone 1: 365nm LED UV, intensity 1000mW / cm², treatment time 30 seconds; Zone 2: Mid-infrared, wavelength 2-4μm, preheated at 80℃ for 1 minute; Zone 3: Hot air circulation, maintained at 60℃ for 2 hours; Step 4-4: Cur the cured coating in a constant temperature and humidity chamber for 7 days.