Water-based environment-friendly aerosol coating composition and rapid film forming and drying method

Abstract

The invention discloses a water-based environment-friendly aerosol coating composition and a rapid film forming and drying method. The water-based environment-friendly aerosol coating composition is prepared from a water-based acrylic resin emulsion, water-based fluorocarbon resin, a modified nano titanium dioxide composite dispersion liquid, an environment-friendly organic coalescing agent, a natural plant extract mildew preventive, a porous silicon-based adsorption type pigment, a nonionic wetting dispersant, a polyether modified organic silicon defoaming agent, an alkali swelling type thickening agent, a defoaming agent, a defoaming agent and a solvent. The ultraviolet light absorber UV-326 and hindered amine light stabilizer compound and the deionized water are prepared. An ultraviolet light absorber microcapsule coating technology is combined with core-shell nano titanium dioxide, so that the ultraviolet shielding rate is improved, the photooxidation fracture rate is reduced, and migration of the auxiliary agent is inhibited based on hydrogen bond crosslinking.

Description

Technical Field

[0001] The present invention belongs to the technical field of water-based environmentally friendly aerosol coatings, and specifically relates to a water-based environmentally friendly aerosol coating composition; in particular, it also relates to a rapid film-forming and drying method for the water-based environmentally friendly aerosol coating composition. Background Art

[0002] Water-based, environmentally friendly aerosol coatings are a type of aerosol spray coating that uses water as a dispersion medium. By encapsulating the coating composition and propellant in a pressure vessel, atomization and spraying are achieved. They offer advantages such as low volatile organic compound (VOC) content, convenient application, and uniform coatings. They are widely used in automotive repair, furniture decoration, and metal corrosion protection. In recent years, with the tightening of environmental protection policies, the design of their components has gradually evolved towards high performance and functionalization, such as the introduction of nanocomposites and natural plant extracts to enhance overall performance.

[0003] The UV absorber in the existing water-based environmentally friendly aerosol coating has weak interaction with the resin matrix. The UV absorber that is only physically mixed easily migrates to the coating surface, which not only reduces the photostability but also accelerates the photooxidative breakage of the resin chain segments, resulting in coating powdering. At the same time, increasing the amount of thickener to improve anti-settling properties will deteriorate the atomization effect and coating permeability; while reducing the thickener will easily cause nanofiller agglomeration and stratification. Based on the above problems, we propose a water-based environmentally friendly aerosol coating composition and a rapid film-forming and drying method. Summary of the Invention

[0004] The purpose of the present invention is to provide a water-based environmentally friendly aerosol coating composition and a rapid film-forming and drying method, which adopts ultraviolet absorber microcapsule coating technology combined with core-shell nano titanium dioxide to improve the ultraviolet shielding rate, reduce the photooxidation breakage rate, and inhibit the migration of additives based on hydrogen bond crosslinking.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The water-based environmentally friendly aerosol coating composition is prepared by, by weight, 30-50 parts of water-based acrylic resin emulsion, 10-20 parts of water-based fluorocarbon resin, 5-15 parts of modified nano-titanium dioxide composite dispersion, 0-8 parts of environmentally friendly organic film-forming aid, 1-5 parts of natural plant extract mildew inhibitor, 8-18 parts of porous silicon-based adsorption pigment, 0.5-2 parts of non-ionic wetting dispersant, 0.1-1 parts of polyether modified silicone defoamer, 0.3-1.5 parts of alkali swelling thickener, 0.2-1 parts of ultraviolet absorber UV-326 and hindered amine light stabilizer compound, and some deionized water.

[0007] Preferably, the fluorine content in the resin of the aqueous fluorocarbon resin is 15-22 wt%, which is copolymerized from tetrafluoroethylene, vinyl dodecafluoroheptanoate and butyl acrylate in a molar ratio of 2:1:0.5, the number average molecular weight is 8000-15000, and the glass transition temperature Tg is 25-35℃.

[0008] Preferably, the core layer of the core-shell structure is anatase titanium dioxide with a size of 20-40 nm, the shell layer is a crosslinked network formed by copolymerization of methyl methacrylate and hydroxyethyl acrylate in a mass ratio of 3:1, and the mass ratio of the core to the shell is 1:0.8-1.2; the quaternary ammonium salt is selected from dioctadecyldimethylammonium chloride, and the addition amount is 1.5-3% of the total mass of the core-shell particles; the dispersion liquid further contains 0.1-0.5 parts of a phosphono carboxylic acid copolymer type dispersion stabilizer, which has a molecular weight of 5000-10000 and a carboxylic acid group density of ≥2 mmol / g; the volume ratio of ethylene glycol butyl ether to water is 1:3-5, and the pH value of the dispersion liquid is adjusted to the range of 8.5-9.5.

[0009] Preferably, the mixing mass ratio of the resin to the aqueous acrylic resin emulsion in the composition is 1:2.5-4.0, and 0.01-0.1 parts of an epoxy siloxane coupling agent is added as a compatibilizer in the mixed system; the average particle size of the fluorocarbon resin emulsion is 80-150 nm, the solid content is 40-50%, and the absolute value of Zeta potential determined by dynamic light scattering method is ≥30 mV; the crosslinking density of the mixed resin system is controlled by adding 0.05-0.3 parts of an aziridine crosslinking agent, and the crosslinking reaction temperature is 60-80℃.

[0010] The method for rapid film-forming drying of the aqueous environment-friendly aerosol coating composition, which uses the above-mentioned aqueous environment-friendly aerosol coating composition as raw material, comprises the following steps:

[0011] S1, aerosol spraying stage: the composition is atomized into liquid droplets with a particle size of 10-50 μm by compressed air with a pressure of 0.3-0.6 MPa, and a porous cyclone type spray gun is used to uniformly cover the surface of the substrate at a spraying distance of 200-300 mm, and the wet film thickness of the sprayed layer is 80-150 μm;

[0012] S2, flash drying stage: infrared radiation is performed within 10-30 seconds after spraying for pre-drying, the infrared wavelength is controlled to be 2.5-5.5 μm, and the irradiation intensity is controlled to be 1.5-3 kW / m2, so that 40-60% of the volatile components in the wet film are instantaneously vaporized to form a porous skeleton structure;

[0013] S3, gradient temperature rising stage: the ambient temperature is raised from 50℃ to 80-90℃ at a rate of 3-5℃ / min by a segmented temperature control tunnel, and maintained for 15-30 minutes, so as to promote the formation of interpenetrating networks of the fluorocarbon resin and the acrylic resin through the epoxy siloxane coupling agent.

[0014] S4, dynamic crosslinking stage: ring-opening reaction of aziridine crosslinking agent is triggered when temperature is raised to 75℃, high-frequency ultrasonic vibration of 20-40 kHz is applied synchronously for 5-15 minutes, and amplitude is controlled at 5-15 μm to accelerate secondary crosslinking of shell layer acrylate;

[0015] S5, final state curing stage: rapid cooling to room temperature is performed by using vertical laminar flow wind with a circulation wind speed of 3-8 m / s, and surface crack propagation is inhibited by light shielding effect of UV absorber compound.

[0016] Preferably, the calculation formula of infrared drying time T is as follows:

[0017] wherein δ is the initial wet film thickness of the sprayed layer, ρ is the density of the coating composition, C p is the specific heat capacity of the mixed resin, L v is the average latent heat of vaporization of deionized water and film-forming additives, is the mass proportion of volatile components, k is the thermal conductivity coefficient of the porous skeleton structure, E is the infrared irradiance, α is the absorption coefficient of the coating film layer to infrared light, and d is the effective absorption thickness of the wet film.

[0018] Preferably, the temperature regulation calculation formula of the gradient temperature rising stage is as follows:

[0019] wherein T0 is the end temperature of the flash stage, ΔT max is the maximum temperature rising amplitude, R is the interfacial tension adjustment coefficient of the film-forming resin, t is the current temperature rising time, t1 is the characteristic time constant, β is the film surface tension influence factor, S v is the instantaneous film surface tension, and S0 is the critical surface tension threshold.

[0020] Preferably, the pressure of the porous cyclone spray gun in step S1 is dynamically adjusted as follows: 0.3 MPa is maintained within 0-5 seconds of initial spraying, linearly increased to 0.6 MPa within 5-20 seconds, and then periodically fluctuates ±0.1 MPa within 20-30 seconds, so as to improve the interfacial bonding force of multi-layer coating.

[0021] Preferably, the infrared irradiation pre-drying needs to be combined with a reflective grating regulator to focus more than 85% of the energy of infrared light on the resonance absorption wavelength band of nanometer titanium dioxide in the film layer, i.e., 3.8-4.2 μm, so as to selectively enhance the photo-thermal conversion efficiency.

[0022] Technical effects and advantages of the present application:

[0023] Microcapsule coating and porous adsorption structure enable the functional additive to form a chemical-physical dual combination with the resin matrix, breaking through the failure bottleneck of traditional physical blending; the adaptive design of rheology modifier and nanofiller takes into account both storage stability and construction performance; the gradient temperature rise-dynamic cross-linking process achieves deep curing while reducing the amount of film-forming additive. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the embodiments described are only a part of the embodiments of the present invention, not all of the embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] The water-based environmentally friendly aerosol coating composition is prepared from a water-based acrylic resin emulsion, a water-based fluorocarbon resin, a modified nano-titanium dioxide composite dispersion, an environmentally friendly organic film-forming aid, a natural plant extract mildew inhibitor, a porous silicon-based adsorption pigment, a non-ionic wetting and dispersing agent, a polyether-modified silicone defoamer, an alkali-soluble swelling thickener, a UV absorber UV-326 and a hindered amine light stabilizer compound, and deionized water.

[0026] The modified nano-titanium dioxide composite dispersion is further defined as:

[0027] The core layer of the core-shell structure is anatase titanium dioxide with a size of 20-40 nm, and the shell layer is a cross-linked network formed by copolymerization of methyl methacrylate and hydroxyethyl acrylate in a mass ratio of 3:1, with a core-shell mass ratio of 1:0.8-1.2; the quaternary ammonium salt is selected from dioctadecyldimethylammonium chloride, and its addition amount is 1.5-3% of the total mass of the core-shell particles; the dispersion further contains 0.1-0.5 parts of a phosphonocarboxylic acid copolymer-type dispersion stabilizer with a molecular weight of 5000-10000 and a carboxylic acid group density of ≥2 mmol / g; the volume ratio of ethylene glycol butyl ether to water is 1:3-5, and the pH value of the dispersion is adjusted to a range of 8.5-9.5;

[0028] Water-based fluorocarbon resin meets the following characteristics:

[0029] The resin has a fluorine content of 15-22% by weight and is copolymerized with tetrafluoroethylene, dodecafluoroheptanoate, and butyl acrylate in a molar ratio of 2:1:0.5. It has a number average molecular weight of 8,000-15,000 and a glass transition temperature (Tg) of 25-35°C. The resin is mixed with an aqueous acrylic resin emulsion in a mass ratio of 1:2.5-4.0, and 0.01-0.1 parts of an epoxysiloxane coupling agent are added to the mixed system as a compatibilizer. The fluorocarbon resin emulsion has an average particle size of 80-150 nm, a solid content of 40-50%, and an absolute value of a zeta potential of ≥30 mV as measured by dynamic light scattering. The crosslinking density of the mixed resin system is controlled by adding 0.05-0.3 parts of an aziridine crosslinking agent, and the crosslinking reaction temperature is 60-80°C.

[0030] The construction method of natural plant extract antifungal agent and antiseptic system is as follows:

[0031] In the graft copolymer of tea polyphenol and carboxymethyl cellulose, the substitution degree of carboxymethyl cellulose is 0.6-0.8, the graft reaction is carried out in a phosphate buffer with a pH of 4.5-5.5, the reaction temperature is controlled at 45-55°C, and the reaction time is 4-6 hours; the mildew inhibitor forms a synergistic system with 0.8-2 parts of a nano-silver-loaded zeolite antibacterial agent, wherein the nano-silver particle size is 5-15nm and the loading amount is 3-5% of the mass ratio of the zeolite; the microcapsule coating material of the ultraviolet absorber compound is a composite wall material of polymethyl methacrylate and polyurethane, and the mass ratio of the two is 1:0.3-0.7; the composition also contains 0.05-0.2 parts of a pH buffer, which is a composite system of 2-amino-2-methyl-1-propanol and sodium pyrophosphate, and the molar ratio of the two is 1:1.2-1.8, to ensure that the pH of the system is stable between 8.0 and 8.8 during the storage period.

[0032] A method for rapidly forming and drying a water-based environmentally friendly aerosol coating composition, comprising the following steps: S1, aerosol spraying stage: atomizing the composition into droplets with a particle size of 10-50 μm by compressed air at 0.3-0.6 MPa, using a porous swirl spray gun to evenly cover the surface of the substrate at a spraying distance of 200-300 mm, with the wet film thickness of the sprayed layer being 80-150 μm; dynamically adjusting the pressure of the porous swirl spray gun to maintain 0.3 MPa within 0-5 seconds of initial spraying, linearly increasing to 0.6 MPa within 5-20 seconds, and then periodically fluctuating by ±0.1 MPa within 20-30 seconds, thereby improving the interfacial bonding strength of the multi-layer coating;

[0033] S2. Flash drying stage: Infrared radiation pre-drying is carried out within 10-30 seconds after spraying, and the infrared wavelength is controlled to 2.5-5.5μm and the radiation intensity is controlled to 1.5-3kW / m, so that 40-60% of the volatile components in the wet film are instantly vaporized to form a porous skeleton structure; the infrared radiation pre-drying needs to be combined with a reflective grating regulator to focus more than 85% of the energy of the infrared light on the resonant absorption band of the nano-titanium dioxide in the film layer (wavelength 3.8-4.2μm) to selectively enhance the photothermal conversion efficiency;

[0034] In addition, the calculation formula for infrared drying time T is:

[0035] Wherein, δ is the initial wet film thickness of the spray coating, ρ is the density of the coating composition, C p is the specific heat capacity of the mixed resin, L v is the average latent heat of vaporization of deionized water and film-forming aid, is the mass ratio of volatile components, k is the thermal conductivity coefficient of the porous skeleton structure, E is the infrared irradiance, α is the absorption coefficient of the coating film to infrared light, and d is the effective absorption thickness of the wet film;

[0036] S3, gradient temperature rise stage: The ambient temperature is raised from 50°C to 80-90°C at a rate of 3-5°C / min through a segmented temperature-controlled tunnel and maintained for 15-30 minutes to promote the formation of an interpenetrating network between the fluorocarbon resin and the acrylic resin through the epoxysilicone coupling agent; during the gradient temperature rise stage, the dielectric constant change of the film layer must be monitored simultaneously. When the dielectric constant drops to 60-70% of the initial value, the next temperature zone is switched, and the switching error is controlled within ±1.5°C. The temperature control calculation formula for the gradient temperature rise stage is:

[0037] Among them, T0 is the end temperature of the flash stage, ΔT max is the maximum temperature rise amplitude, R is the interfacial tension adjustment coefficient of the film-forming resin, t is the current temperature rise time, t1 is the characteristic time constant, β is the film surface tension influencing factor, S v is the instantaneous membrane surface tension, S0 is the critical surface tension threshold;

[0038] S4, dynamic crosslinking stage: triggering the ring-opening reaction of the aziridine crosslinker when the temperature is raised to 75°C, and simultaneously applying high-frequency ultrasonic vibration of 20-40 kHz for 5-15 minutes with an amplitude controlled at 5-15 μm to accelerate the secondary crosslinking of the shell acrylate; also includes a dynamic crosslinking activation step: while applying high-frequency ultrasonic vibration, a pulsed electromagnetic field is used to assist the crosslinking reaction, with an electromagnetic field frequency of 50-100 MHz and a pulse width of 10-30 μs, thereby increasing the ring-opening efficiency of the aziridine crosslinker by 20-30%;

[0039] S5, final curing stage: quickly cool to room temperature with vertical laminar air at a circulating wind speed of 3-8m / s, and inhibit the expansion of surface cracks through the light shielding effect of the ultraviolet absorber compound; the circulating wind speed needs to be achieved through airflow zoning control, and a gradient distribution of front-section wind speed of 4-6m / s, middle-section wind speed of 2-3m / s, and end-section wind speed of 0.5-1m / s is set along the length direction of the curing zone to avoid stress concentration of film shrinkage; after the end, a gradient insulation treatment is required: first, keep warm at 60℃ for 10 minutes, then cool to 40℃ at a rate of 2℃ / min, and finally cool naturally to room temperature to fully release the internal stress of the modified nano-titanium dioxide composite dispersion.

[0040] Based on the above, the specific embodiments are as follows:

[0041] Example 1

[0042]

[0043] Coating properties:

[0044] Light stability: After 1000h of QUV accelerated aging, light retention rate>92% (ISO11507);

[0045] Antibacterial rate: After 30 days, the antibacterial rate against Escherichia coli is 99.95%;

[0046] Drying time: surface drying ≤ 8 minutes, through drying ≤ 45 minutes (GB / T1728).

[0047] Example 1 optimizes the quick-drying and impact resistance of the coating by combining fluorocarbon resin with high Tg acrylic acid.

[0048] Example 2

[0049]

[0050] Coating properties:

[0051] Biocompatibility: passed ISO10993-5 cytotoxicity test (activity > 95%);

[0052] Wear resistance: Taber wear test (CS-10 wheel, 500g / 1000 revolutions) mass loss ≤ 5mg;

[0053] VOC content: ≤35g / L (GB38507-2020).

[0054] Example 3

[0055]

[0056] Coating properties:

[0057] Corrosion resistance: Salt spray test for 2000h, rust expansion at the scratch is less than 1mm (ASTMB117);

[0058] Fluorescence indication: The crack area emits red fluorescence under ultraviolet irradiation (λ_ex=365nm, λ_em=612nm);

[0059] Adhesion: Cross-hatch test level 0 (GB / T9286).

[0060] Based on the above three groups of embodiments, the key performance analysis is as follows:

[0061] (1) Light stability and weather resistance

[0062] Example 1: Through the synergistic effect of a high-dose UV absorber (0.6 parts) and core-shell TiO⁻ (12 parts), the optimal comprehensive weather resistance (gloss retention rate > 92%) was demonstrated in the automotive repair scenario;

[0063] Example 3: Although the amount of UV absorber used is higher (1.0 part), the gloss retention rate is slightly higher than that of Example 1 due to the difference in thermal expansion coefficient of the outdoor metal substrate, but some drying speed must be sacrificed.

[0064] (2) Functional adaptation differences

[0065] Example 2: To ensure the biosafety of medical devices, low VOC (35 g / L) and high-purity fluorocarbon resin (fluorine content 20%) were used to ensure cell viability > 95%, but the photostability was relatively low (light retention rate 88%).

[0066] Example 3: The crack self-diagnosis function is achieved by loading a rare earth fluorescent complex on a porous silicon-based pigment, but the antibacterial performance is sacrificed (no antibacterial system is designed).

[0067] (3) Process-performance correlation

[0068] Drying speed: Example 2 has the shortest actual drying time (35 min) due to the premixing of the aziridine crosslinker and the assistance of the pulsed electromagnetic field, while Example 3 has a longer drying time due to the high solid content design (50 parts of acrylic resin);

[0069] Wear resistance: The fluorocarbon resin of Example 2 has a higher molecular weight (12,000) and a precisely controlled cross-linking density, resulting in optimal wear resistance (mass loss ≤ 5 mg), which is 37.5% higher than that of the automotive repair coating (loss ≤ 8 mg).

[0070] (4) Environmental protection and safety

[0071] VOC Control: In Example 2, due to the strict standards for medical devices, a low-volatility sulfonate (sodium dodecyl diphenyl ether sulfonate) was selected as the film-forming aid, with a VOC of 35 g / L. However, automotive repair coatings require a balanced fast-drying property, so the VOC is slightly higher (50 g / L).

[0072] Heavy metal risk: The nanosilver loading in Examples 1 and 3 is ≤5%, and the zeolite carrier is coated to ensure that the silver ion dissolution rate is <0.1 μg / cm·d (lower than the EPA limit).

[0073] The comparison of the above effects is shown in the following table:

[0074]

[0075]

[0076] The three embodiments precisely match the core requirements of different application scenarios through differentiated component design and process optimization:

[0077] Example 1: With fast drying and high weather resistance as the main features, it is suitable for dynamic load scenarios such as car repair;

[0078] Example 2: Focusing on biosafety and surface wear resistance to meet regulatory requirements for medical device coatings;

[0079] Example 3: Through the coordinated design of fluorescent indication and anti-corrosion, the maintenance blind spot of outdoor metal coating is broken through.

[0080] In summary, the present invention has the following effects:

[0081] 1. Enhanced synergistic stability of UV absorbers and resin matrix

[0082] By using a microcapsule-encapsulated UV absorber compound of UV-326 and HALS-622 with polyurethane-polymethyl methacrylate composite wall materials, the following breakthroughs have been achieved:

[0083] In-situ sustained-release mechanism: The polyurethane shell of the microcapsule forms a hydrogen bond cross-linking network with the hydroxyl groups in the resin through carboxyl groups, while the polymethyl methacrylate shell undergoes π-π conjugation with the acrylate chain segments, so that the UV absorber is anchored in the gaps between the resin molecular chains, and its migration rate is reduced to less than 1 / 5 of that of the traditional physical mixing system, as verified by TOF-SIMS testing.

[0084] Photochemical response protection: Under ultraviolet excitation, the benzotriazole structure of UV-326 undergoes photoisomerization. The released energy is quenched by the hindered amine group of HALS-622, forming a free radical capture cycle, which reduces the photooxidative breakage rate of acrylic resin by 70%-80% based on the results of Arrhenius accelerated aging test.

[0085] Nanostructured protective layer: The 100-300nm coating thickness of the microcapsules and the core-shell structure of nano-titanium dioxide form a light scattering synergistic effect, increasing the UV reflectivity to 85%-90%. At the same time, the UV absorber released after the microcapsules rupture repairs the surface microcracks, and the crack density is reduced by more than 90% according to SEM observation.

[0086] 2. Synergistic optimization of coating storage stability and construction performance

[0087] Innovative design based on porous silica-based adsorption pigments and thickening / dispersion systems:

[0088] Dual-action physical adsorption and chemical bonding: The 3-8 nm pore structure of the mesoporous silica carrier adsorbs azo dyes and rare earth fluorescent complexes through capillary forces. The surface silanol groups form ionic bonds with the carboxylic acid groups of the alkali-swellable thickener, reducing the pigment settling rate by 60%-75% compared to traditional titanium dioxide systems, as calculated by Stokes' law. Simultaneously, the hydrophobic segments of the non-ionic wetting and dispersing agent embed themselves within the porous structure, forming a three-dimensional barrier that reduces the aggregation rate of the nanofillers during dilution to less than 3%, according to dynamic light scattering measurements.

[0089] Precise control of rheological behavior: the thickener forms a shear-thinning pseudoplastic fluid at pH 8.0-8.8, with a static viscosity of 3500-4500 mPa·s to ensure anti-settling properties, and at a spraying shear rate of 10^4s －1 The viscosity drops instantly to 50-80mPa·s, and the standard deviation of the atomized particle size distribution is less than 15% according to laser particle size analysis data. At the same time, the coating porosity is maintained at 8%-12%, ensuring a balance between air permeability and corrosion resistance.

[0090] 3. Dynamic matching of resin cross-linking network and film-forming aid

[0091] Through the synergistic effect of fluorocarbon resin-acrylic resin composite system and aziridine crosslinking agent:

[0092] Gradient cross-linking density distribution: During the gradient heating stage (50→90℃), the epoxysilicone coupling agent promotes the interlaced entanglement between the -CF仩- chain segments of the fluorocarbon resin and the ester groups of the acrylic resin. After the aziridine cross-linker triggers the ring-opening reaction at 75℃, a three-dimensional cross-linking network is constructed through the condensation reaction of amino and hydroxyl groups. The elastic modulus of the coating gradually transitions from 1.2GPa in the surface layer to 2.8GPa in the bottom layer. Nanoindentation test results show that stress dispersion and impact resistance pass the drop ball impact test of 500g·cm are achieved.

[0093] Optimized film-forming agent volatilization pathways: Environmentally friendly organic film-forming agents, such as Texanol, preferentially escape from the 3D channels of the porous framework during the flash drying phase, with residual levels below 0.5 ppm as determined by GC-MS. This prevents pore collapse after film formation. Furthermore, the fluorocarbon resin's Tg of 25-35°C complements the acrylic resin's Tg of 45-65°C, allowing a continuous phase to form during low-temperature film formation, reducing film-forming agent usage by 40%-50%.

[0094] 4. Long-term compatibility of anti-mildew and antibacterial and defoaming processes

[0095] Relying on the synergistic system of natural plant extract antifungal agent and nano-silver loaded zeolite:

[0096] Construction of dynamic antibacterial film: The phenolic hydroxyl groups of tea polyphenol-carboxymethyl cellulose graft copolymer continuously release reactive oxygen species (ROS) through redox reactions, while the slow-release silver ions (0.08-0.15 μg / cm·d) of nanosilver-loaded zeolite synergistically release ROS, ensuring that the antibacterial rate of the coating against Escherichia coli and Staphylococcus aureus remains >99.9% after 30 days of accelerated aging according to ISO22196 standard test.

[0097] Dual defoaming and antifoaming mechanism: Polyether-modified silicone defoamers with an HLB value of 4-6 migrate to the air-liquid interface with ultrasonic vibration during the dynamic crosslinking stage, breaking bubbles by reducing the surface tension to ≤25mN / m. At the same time, their hydrophobic segments form a hydrophobic barrier with the silanol groups on the surface of porous silicon-based pigments, inhibiting the formation of secondary bubbles after construction. The bubble density is less than 10 / cm², rated as Grade 2 according to ASTM D714.

[0098] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A water-based environmentally friendly aerosol coating composition, characterized in that: The water-based environmentally friendly aerosol coating composition is prepared from 30-50 parts of water-based acrylic resin emulsion, 10-20 parts of water-based fluorocarbon resin, 5-15 parts of modified nano-titanium dioxide composite dispersion, 0-8 parts of environmentally friendly organic film-forming assistant, 1-5 parts of natural plant extract mildew inhibitor, 8-18 parts of porous silicon-based adsorption pigment, 0.5-2 parts of non-ionic wetting dispersant, 0.1-1 parts of polyether modified organic silicon defoamer, 0.3-1.5 parts of alkali swelling thickener, 0.2-1 parts of ultraviolet absorber UV-326 and hindered amine light stabilizer compound and some deionized water by weight.

2. The water-based environmentally friendly aerosol coating composition according to claim 1, characterized in that: The fluorine content of the water-based fluorocarbon resin is 15-22wt%, and it is copolymerized by tetrafluoroethylene, dodecafluoroheptanoate and butyl acrylate in a molar ratio of 2:1:0.

5. The number average molecular weight is 8000-15000 and the glass transition temperature Tg is 25-35℃.

3. The water-based environmentally friendly aerosol coating composition according to claim 2, characterized in that: The core layer of the core-shell structure is anatase-type titanium dioxide with a size of 20-40 nm, and the shell layer is a cross-linked network formed by copolymerization of methyl methacrylate and hydroxyethyl acrylate in a mass ratio of 3:1, with a core-shell mass ratio of 1:0.8-1.2; the quaternary ammonium salt is selected from dioctadecyldimethylammonium chloride, and its addition amount is 1.5-3% of the total mass of the core-shell particles; the dispersion further contains 0.1-0.5 parts of a phosphonocarboxylic acid copolymer-type dispersion stabilizer with a molecular weight of 5000-10000 and a carboxylic acid group density of ≥2 mmol / g; the volume ratio of ethylene glycol butyl ether to water is 1:3-5, and the pH value of the dispersion is adjusted to the range of 8.5-9.

5.

4. The water-based environmentally friendly aerosol coating composition according to claim 2, characterized in that: The mass ratio of the resin to the aqueous acrylic resin emulsion in the composition is 1:2.5-4.0, and 0.01-0.1 parts of epoxysilicone coupling agent are added to the mixed system as a compatibilizer; the average particle size of the fluorocarbon resin emulsion is 80-150 nm, the solid content is 40-50%, and the absolute value of the zeta potential measured by dynamic light scattering is ≥30 mV; the crosslinking density of the mixed resin system is regulated by adding 0.05-0.3 parts of an aziridine crosslinking agent, and the crosslinking reaction temperature is 60-80°C.

5. A method for rapid film formation and drying of a water-based environmentally friendly aerosol coating composition, characterized in that: The method uses the water-based environmentally friendly aerosol coating composition according to any one of claims 1 to 4 as a raw material, and comprises the following steps: S1. Aerosol spraying stage: The composition is atomized into droplets with a particle size of 10-50 μm by compressed air at 0.3-0.6 MPa, and the surface of the substrate is evenly covered with the composition by a multi-hole swirl spray gun at a spraying distance of 200-300 mm. The wet film thickness of the sprayed layer is 80-150 μm. S2. Flash drying stage: Infrared radiation pre-drying is carried out within 10-30 seconds after spraying, and the infrared wavelength is controlled at 2.5-5.5μm and the radiation intensity is controlled at 1.5-3kW / m, so that 40-60% of the volatile components in the wet film are instantly vaporized to form a porous skeleton structure; S3, Gradient temperature rise stage: The ambient temperature is raised from 50°C to 80-90°C at a rate of 3-5°C / min through a segmented temperature-controlled tunnel and maintained for 15-30 minutes to promote the formation of an interpenetrating network between the fluorocarbon resin and the acrylic resin through the epoxy-silicone coupling agent; S4, dynamic crosslinking stage: triggering the ring-opening reaction of the aziridine crosslinker when the temperature rises to 75°C, and simultaneously applying high-frequency ultrasonic vibration of 20-40kHz for 5-15 minutes with the amplitude controlled at 5-15μm to accelerate the secondary crosslinking of the shell acrylate; S5, final curing stage: Rapidly cool to room temperature with vertical laminar air circulation speed of 3-8m / s, and inhibit surface crack propagation through the light shielding effect of the ultraviolet absorber compound.

6. The rapid film-forming and drying method of the water-based environmentally friendly aerosol coating composition according to claim 5, characterized in that: The calculation formula of infrared drying time T is: Wherein, δ is the initial wet film thickness of the spray coating, ρ is the density of the coating composition, C p is the specific heat capacity of the mixed resin, L v is the average latent heat of vaporization of deionized water and film-forming aid, is the mass ratio of volatile components, k is the thermal conductivity coefficient of the porous skeleton structure, E is the infrared irradiance, α is the absorption coefficient of the coating film to infrared light, and d is the effective absorption thickness of the wet film.

7. The rapid film-forming and drying method of the water-based environmentally friendly aerosol coating composition according to claim 5, characterized in that: The temperature control calculation formula in the gradient heating stage is: Among them, T0 is the end temperature of the flash stage, ΔT max is the maximum temperature rise amplitude, R is the interfacial tension adjustment coefficient of the film-forming resin, t is the current temperature rise time, t1 is the characteristic time constant, β is the film surface tension influencing factor, S v is the instantaneous membrane surface tension, and S0 is the critical surface tension threshold.

8. The rapid film-forming and drying method of the water-based environmentally friendly aerosol coating composition according to claim 5, characterized in that: In step S1, the pressure of the porous swirl spray gun is dynamically adjusted to: maintain 0.3 MPa within 0-5 seconds of initial spraying, linearly increase to 0.6 MPa within 5-20 seconds, and then periodically fluctuate by ±0.1 MPa within 20-30 seconds, thereby improving the interfacial bonding strength of the multi-layer coating.

9. The rapid film-forming and drying method of the water-based environmentally friendly aerosol coating composition according to claim 5, characterized in that: The infrared radiation pre-drying needs to be combined with a reflective grating regulator to focus more than 85% of the energy of infrared light on the resonance absorption band of nano-titanium dioxide in the film layer, with a wavelength of 3.8-4.2μm, to selectively enhance the photothermal conversion efficiency.

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