A fluorine-containing acrylic resin coating and a method for preparing the same

Abstract

The present application relates to the technical field of paint preparation, and particularly relates to a fluorine-containing acrylic resin paint and a preparation method thereof, which comprises the following steps: copolymerizing hydroxyethyl methacrylate and hexafluorobutyl methacrylate under the action of an initiator to obtain a hydroxyl-containing fluorine-containing acrylic copolymer; dissolving the hydroxyl-containing fluorine-containing acrylic copolymer in a mixed solvent of anhydrous tetrahydrofuran and acetone; adding mercaptopropanoic acid, p-toluenesulfonic acid and dibenzyl diselenide in sequence to carry out reflux reaction to obtain a mercapto-seleno-disulfide modified resin; preparing a graphene-doped calcium carbonate composite filler and modifying the graphene-doped calcium carbonate composite filler by dopamine; centrifuging to obtain a precipitate; adding a dispersing agent and a leveling agent into the precipitate to obtain a mixed solution; mixing the mixed solution with a mercapto-seleno-disulfide modified resin solution; and stirring bidirectionally to obtain a fluorine-containing acrylic resin paint.

Description

Technical Field

[0001] This invention relates to the field of coating preparation technology, and in particular to a fluorinated acrylic resin coating and its preparation method. Background Technology

[0002] While traditional acrylic resins possess basic weather resistance and ease of application, the CH bonds in their molecular structure are susceptible to erosion by ultraviolet light and chemical media, leading to coating chalking, fading, or failure. Fluorinated acrylic resins are high-performance materials formed by copolymerizing fluorinated acrylate monomers (such as hexafluorobutyl methacrylate and trifluoroethyl methacrylate) with traditional acrylates. The CF bonds in their molecular structure endow the material with the following unique physicochemical properties: excellent weather resistance; the CF bonds effectively resist ultraviolet light bombardment, converting light energy into heat energy for dissipation and preventing main chain breakage. Under natural outdoor exposure conditions, its service life can reach 15-20 years, significantly superior to ordinary acrylic resins, making it the preferred material for long-term protection applications such as building exterior walls and bridge corrosion protection; ultra-low surface energy; the electronegativity of fluorine atoms forms a tightly packed electron cloud shielding layer on the molecular surface, reducing the surface tension of the coating and providing excellent hydrophobic and oleophobic properties, achieving a self-cleaning effect; excellent chemical stability; the steric hindrance effect of the fluorinated side chains effectively protects the main chain structure, and the helical arrangement of the fluorinated side chains forms a three-dimensional barrier, hindering H... + Cl - Corrosive ions are close to the main chain, making it widely used in harsh corrosive environments such as chemical equipment and marine facilities. Announcement No. CN118813105B describes a method for preparing a fluorosilicone-containing anti-corrosion acrylic resin coating. The method involves mixing a monomer solution and an initiator solution, reacting them, then adding a fluorosilicone acrylamide monomer and reacting again. Dilute ammonia, defoamer, leveling agent, and film-forming aid are then added and mixed thoroughly to obtain the fluorosilicone-containing anti-corrosion acrylic resin coating. This coating exhibits water resistance, salt spray resistance, and anti-corrosion properties, but lacks self-healing properties when scratched. Fluorinated acrylic resins, due to the unique electronegativity of fluorine atoms and the high bond energy of the CF bond, endow coatings with excellent weather resistance, low surface energy, chemical corrosion resistance, and self-cleaning properties, occupying an important position in aerospace coatings, building exterior wall protection, automotive paints, and electronic device packaging. Fluorinated coatings have excellent lubrication properties, reducing surface friction resistance on aircraft and lowering fuel consumption. For example, Boeing uses fluorinated coatings on some aircraft models to reduce fuel consumption. Electronic products (such as mobile phones and laptops) require waterproof coatings to protect their internal circuitry. Fluorine-containing coatings can provide excellent waterproof performance without affecting the appearance. Fluorine-containing coatings can also improve the light transmittance and self-cleaning ability of solar panel surfaces, extending battery life. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this application provides a fluorinated acrylic resin coating and its preparation method, comprising the following steps: copolymerizing hydroxyethyl methacrylate and hexafluorobutyl methacrylate under the action of an initiator to obtain a hydroxyl-containing fluorinated acrylic copolymer; dissolving the above hydroxyl-containing fluorinated acrylic copolymer in a mixed solvent of anhydrous tetrahydrofuran and acetone; sequentially adding mercaptopropionic acid, p-toluenesulfonic acid, and diselenyl dibenzyl chloride and refluxing to obtain a mercapto-selenodisulfide modified resin; preparing a fluorite-graphene-calcium carbonate composite solution and modifying it with dopamine; centrifuging to collect the precipitate; adding a dispersant and a leveling agent to the precipitate to obtain a mixed solution; mixing the mixed solution with the mercapto-selenodisulfide modified resin solution; and then stirring in both directions to obtain a fluorinated acrylic resin coating.

[0004] Hydroxyethyl methacrylate and hexafluorobutyl methacrylate form a copolymer under the action of an initiator. The initiator decomposes to generate free radicals, which attack the double bonds of the monomers and form active centers. The two monomers then connect to each other through the opening of the double bonds, forming a main chain structure. The copolymerization reaction is completed through chain growth, chain transfer, and chain termination processes, ultimately forming a copolymer with both hydroxyl reactivity and fluorine characteristics. In the preparation of mercapto-selenodisulfide modified resins, the hydroxyl-containing copolymer undergoes esterification and selenium-sulfur exchange reactions with mercaptopropionic acid and diselenodibenzyl diselenoide under reflux conditions. The hydroxyl groups in the copolymer undergo esterification with the carboxyl groups of mercaptopropionic acid under the action of p-toluenesulfonic acid, forming ester bonds, while simultaneously introducing mercapto groups into the resin molecular chain. The mercapto groups undergo redox reactions with diselenodibenzyl diselenoide, ultimately introducing a selenodisulfide structure into the resin molecular chain. The fluorine-containing compound (Na3FeF6) in fluorine oxide and the fluorine-containing acrylic copolymer form a synergistic effect of fluorine, forming a stable fluorine-rich layer on the coating surface. This effectively blocks the penetration of moisture, oxygen, and corrosive ions, reduces the permeability of the coating, and thus significantly improves corrosion resistance and weather resistance.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] This application provides a fluorinated acrylic resin coating and a method for preparing the same, comprising the following steps:

[0007] Hydroxyethyl methacrylate and hexafluorobutyl methacrylate were copolymerized under the action of an initiator to obtain a hydroxyl-containing fluorinated acrylic copolymer.

[0008] The hydroxyl-containing fluorinated acrylic copolymer was dissolved in a mixed solvent of anhydrous tetrahydrofuran and acetone, and mercaptopropionic acid, p-toluenesulfonic acid and diselenyl dibenzyl were added in sequence and refluxed to obtain a mercapto-selenodisulfide modified resin solution.

[0009] A calcium chloride solution was added to graphene, and the mixture was ultrasonically dispersed to form a graphene-calcium chloride mixture. Then, fluorite was added, and after mechanical stirring, sodium carbonate solution was added to adjust the pH to 8-9 to prepare a fluorite-graphene-calcium carbonate composite solution. The fluorite-graphene-calcium carbonate composite solution was modified with dopamine, and the supernatant was removed by centrifugation to obtain fluorite-graphene-calcium carbonate composite particles with surface-modified polydopamine. A dispersant and a leveling agent were added to the fluorite-graphene-calcium carbonate composite particles with surface-modified polydopamine to obtain a mixture. Then, a mercapto-selenodisulfide modified resin solution was added, mixed, and stirred bidirectionally to obtain the fluorinated acrylic resin coating.

[0010] In one feasible implementation, the initiator is azobisisobutyronitrile; the molar ratio of hydroxyethyl methacrylate, hexafluorobutyl methacrylate and azobisisobutyronitrile is 1:(1.2-1.6):(0.01-0.03).

[0011] In one feasible implementation, the mixed solvent is anhydrous tetrahydrofuran and acetone, with a volume ratio of anhydrous tetrahydrofuran to acetone of 1:1, the mass ratio of the hydroxyl-containing fluorinated acrylic copolymer to the mixed solvent is 1:(4-8), and the mass ratio of diselenylbenzyl, mercaptopropionic acid to the hydroxyl-containing fluorinated acrylic copolymer is (0.05-0.2):(0.1-0.3):1.

[0012] In one feasible implementation, the mass ratio of graphene to calcium chloride solution is 1:(40-50), the mass ratio of graphene-calcium chloride mixture to fluorite is (4-6):1, the concentration of sodium carbonate solution is 0.1-0.3 mol / L, and fluorite is a fluorine-containing compound containing Na3FeF6.

[0013] In one feasible implementation, the concentration of the calcium chloride solution is 0.1-0.3 mol / L, the ultrasonic power is 200-300W, and the duration is 10-20 minutes.

[0014] In one feasible implementation, the dopamine modification of the fluorspar-graphene-calcium carbonate composite solution includes: adding 3% dopamine to the fluorspar-graphene-calcium carbonate composite solution, adjusting the pH to 8-9 with Tris-HCl buffer, and reacting at 30-40°C for 1-2 hours.

[0015] In one feasible implementation, the centrifugation involves adding anhydrous ethanol to a dopamine-modified fluorite-graphene-calcium carbonate composite solution, ultrasonically dispersing it at 200-300W for 10-15 minutes, centrifuging it at 8000-10000rpm for 10-15 minutes, and removing the supernatant to obtain fluorite-graphene-calcium carbonate composite particles with polydopamine surface modification.

[0016] In one feasible implementation, the dispersant is BYK-111, which is 1wt%-2wt% of the mixture, and the leveling agent is BYK-333, which is 0.3wt%-0.5wt% of the mixture.

[0017] In one feasible implementation, the mass ratio of the mixture to the mercapto-selenium disulfide modified resin solution is 1:(5-8).

[0018] In one feasible implementation, the bidirectional stirring is performed at a radial speed of 300 r / min and an axial speed of 100 r / min for 20-30 minutes, followed by stirring for another 10-15 minutes.

[0019] Beneficial technical effects:

[0020] This application involves dissolving a hydroxyl-containing fluorinated acrylic copolymer in a mixed solvent of anhydrous tetrahydrofuran and acetone, then sequentially adding mercaptopropionic acid, p-toluenesulfonic acid, and diselenylbenzyl diselenide under reflux to obtain a mercapto-selenodisulfide modified resin. The reaction of mercaptopropionic acid, diselenylbenzyl diselenide, and the hydroxyl-containing copolymer introduces mercapto and selenodisulfide structures through covalent bonds, resulting in a dual effect. The selenodisulfide bonds can undergo reversible breakage and recombination triggered by mechanical force or at room temperature. When the coating is scratched by external force, the broken -Se-S- bonds can be reconnected through molecular chain movement, achieving self-repair of minor damage and extending the service life of the coating. The mercapto groups can chemically react with the active groups (catechol groups of dopamine) on the surface of the composite filler, strengthening the interfacial forces between the resin and the filler, reducing interfacial voids, and improving the overall integrity of the coating. After being modified with dopamine, the fluorite-graphene-calcium carbonate composite filler forms a synergistic effect of physical barrier, chemical rust prevention, and mechanical enhancement: The two-dimensional sheet structure of graphene forms an interlaced physical barrier in the coating, which can prolong the penetration path of corrosive media such as water, oxygen, and chloride ions, significantly reducing the corrosion rate. Its high mechanical strength can also enhance the impact resistance of the coating. The in-situ generated calcium carbonate, as an inorganic rigid filler, can be uniformly dispersed between the graphene sheets, improving the hardness and wear resistance of the coating, while reducing the amount of resin used and optimizing costs. Fluorite can form a passivation film on the surface of the metal substrate, inhibiting the anodic oxidation reaction and achieving chemical rust prevention. The catechol groups of dopamine can combine with the oxygen-containing groups of graphene on the filler surface through hydrogen bonds and coordination bonds, and react with the hydroxyl and mercapto groups in the resin to eliminate the interfacial tension between the filler and the resin, avoid stress concentration defects caused by filler agglomeration, and ensure the uniformity of mechanical and anti-corrosion properties. Attached Figure Description

[0021] Figure 1 It is a reaction formula between mercapto-modified fluorinated acrylic resin and diselenylbenzyl diselenide.

[0022] Figure 2This is a physical image of a fluorinated acrylic resin coating prepared in Example 1. Detailed Implementation

[0023] To make the technical problems, solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. However, this should not be construed as limiting the scope of this application to the following embodiments. All other embodiments obtained by those skilled in the art without creative effort, without departing from the above-described methodological spirit, are within the scope of protection of this application.

[0024] In this application, the terminology used is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0025] The singular forms “for,” “a,” “any one,” and “as described” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0026] Furthermore, the terms "first" and "second" appearing in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] The following will describe in detail, with reference to different embodiments, a fluorinated acrylic resin coating and its preparation method provided in this application.

[0028] Example 1

[0029] A method for preparing a fluorinated acrylic resin coating includes the following steps:

[0030] A hydroxyethyl methacrylate solution was added to a three-necked flask, and the oil bath temperature was raised to 85°C. Azobisisobutyronitrile was dissolved in hexafluorobutyl methacrylate to obtain a mixed solution of hexafluorobutyl methacrylate. The mixed solution of hexafluorobutyl methacrylate was added dropwise to the three-necked flask at a rate of 1 drop / second for 1.5 hours, and the reaction was continued for 3.5 hours to obtain a hydroxyl-containing fluorinated acrylic copolymer. The molar ratio of hydroxyethyl methacrylate, hexafluorobutyl methacrylate, and azobisisobutyronitrile was 1:1.4:0.02.

[0031] The hydroxyl-containing fluorinated acrylic copolymer was dissolved in a mixed solvent of anhydrous tetrahydrofuran and acetone (volume ratio 1:1), mercaptopropionic acid and p-toluenesulfonic acid were added, and the mixture was refluxed at 78°C for 1.5 hours. Then, diselenyl dibenzyl diselenide was added, and the mixture was refluxed at 80°C for another 3.5 hours to generate a mercapto-selenodisulfide modified resin. The mass ratio of the hydroxyl-containing fluorinated acrylic copolymer to the mixed solvent was 1:6, and the mass ratio of diselenyl dibenzyl diselenide, mercaptopropionic acid, and the hydroxyl-containing fluorinated acrylic copolymer was 0.1:0.2:1. Figure 1 As shown.

[0032] Graphene was added to a 0.2 mol / L calcium chloride solution and ultrasonically dispersed at 250 W for 15 minutes, with a graphene to calcium chloride solution mass ratio of 1:45, forming a graphene-calcium ion suspension. Fluorite (95% purity) was added to the above graphene-calcium ion suspension and mechanically stirred (300 r / min) until uniformly dispersed. A 0.1 mol / L sodium carbonate solution was added dropwise to adjust the pH to 8, and the mixture was reacted in a constant temperature water bath at 30℃ for 1 hour to allow nano-calcium carbonate to grow in situ between the graphene sheets. The mass ratio of the graphene-calcium chloride mixture to fluorite was 5:1.

[0033] Then, 3% dopamine was added, and the pH of the system was adjusted to 8.5 with Tris-HCl buffer. The mixture was stirred at 35°C for 1.5 hours to form a dense modified layer of polydopamine on the surface of the composite solution. Anhydrous ethanol was added to the polydopamine-modified fluorite-graphene-calcium carbonate composite solution, and the mixture was ultrasonically dispersed at 250W for 10 minutes and centrifuged at 8000rpm for 10 minutes. The precipitate was then collected for later use.

[0034] Add 1.5 wt% BYK-111 dispersant and 0.4 wt% BYK-333 leveling agent to the above precipitate, and ultrasonically disperse at 250W for 10 minutes; slowly dropwise add this mixture to the above-prepared mercapto-selenodisulfide modified resin, and stir bidirectionally (300 r / min radially and 100 r / min axially) for 25 minutes, then continue stirring for 10 minutes to obtain a fluorinated acrylic resin coating. The mass ratio of the mixture to the mercapto-selenodisulfide modified resin is 1:6. Figure 2 As shown.

[0035] Example 2

[0036] A method for preparing a fluorinated acrylic resin coating includes the following steps:

[0037] A hydroxyethyl methacrylate solution was added to a three-necked flask, and the oil bath temperature was raised to 85°C. Azobisisobutyronitrile was dissolved in hexafluorobutyl methacrylate to obtain a mixed solution of hexafluorobutyl methacrylate. The mixed solution of hexafluorobutyl methacrylate was added dropwise to the three-necked flask at a rate of 1 drop / second for 1.5 hours, and the reaction was continued for 3.5 hours to obtain a hydroxyl-containing fluorinated acrylic copolymer. The molar ratio of hydroxyethyl methacrylate, hexafluorobutyl methacrylate, and azobisisobutyronitrile was 1:1.2:0.01.

[0038] The above-mentioned hydroxyl-containing fluorinated acrylic copolymer was dissolved in a mixed solvent of anhydrous tetrahydrofuran and acetone (volume ratio 1:1), mercaptopropionic acid and p-toluenesulfonic acid were added, and the mixture was refluxed at 75°C for 1 hour; then diselenyl dibenzyl diselenide was added, and the mixture was refluxed at 75°C for another 3 hours to generate a mercapto-selenodisulfide modified resin. The mass ratio of the hydroxyl-containing fluorinated acrylic copolymer to the mixed solvent was 1:4, and the mass ratio of diselenyl dibenzyl diselenide, mercaptopropionic acid, and the hydroxyl-containing fluorinated acrylic copolymer was 0.05:0.1:1. Figure 1 As shown.

[0039] Graphene was added to a 0.2 mol / L calcium chloride solution and ultrasonically dispersed at 250 W for 10 minutes, with a graphene to calcium chloride solution mass ratio of 1:40, forming a graphene-calcium ion suspension. Fluorite (95% purity) was added to the above graphene-calcium ion suspension and mechanically stirred (350 r / min) until uniformly dispersed. A 0.2 mol / L sodium carbonate solution was added dropwise to adjust the pH to 8.5, and the mixture was reacted in a constant temperature water bath at 35℃ for 1.5 hours to allow nano-calcium carbonate to grow in situ between the graphene sheets. The mass ratio of the graphene-calcium chloride mixture to fluorite was 4:1.

[0040] Then, 3% dopamine was added, and the pH of the system was adjusted to 8.0 with Tris-HCl buffer. The mixture was stirred at 30°C for 1 hour to form a dense modified layer of polydopamine on the surface of the composite solution. Anhydrous ethanol was added to the polydopamine-modified fluorite-graphene-calcium carbonate composite solution, and the mixture was ultrasonically dispersed at 200W for 10 minutes and centrifuged at 8000rpm for 10 minutes. The precipitate was then collected for later use.

[0041] Add 1 wt% BYK-111 dispersant and 0.3 wt% BYK-333 leveling agent to the above precipitate, and ultrasonically disperse at 200W for 10 minutes; slowly drop the mixture into the mercapto-selenodisulfide modified resin prepared above, and stir in both directions (radial 300 r / min, axial 100 r / min) for 20 minutes, and continue stirring for 10 minutes to obtain a fluorinated acrylic resin coating. The mass ratio of the mixture to the mercapto-selenodisulfide modified resin is 1:5.

[0042] Example 3

[0043] A method for preparing a fluorinated acrylic resin coating includes the following steps:

[0044] A hydroxyethyl methacrylate solution was added to a three-necked flask, and the oil bath temperature was raised to 85°C. Azobisisobutyronitrile was dissolved in hexafluorobutyl methacrylate to obtain a mixed solution of hexafluorobutyl methacrylate. The mixed solution of hexafluorobutyl methacrylate was added dropwise to the three-necked flask at a rate of 1 drop / second for 1.5 hours, and the reaction was continued for 3.5 hours to obtain a hydroxyl-containing fluorinated acrylic copolymer. The molar ratio of hydroxyethyl methacrylate, hexafluorobutyl methacrylate, and azobisisobutyronitrile was 1:1.6:0.03.

[0045] The above-mentioned hydroxyl-containing fluorinated acrylic copolymer was dissolved in a mixed solvent of anhydrous tetrahydrofuran and acetone (volume ratio 1:1), mercaptopropionic acid and p-toluenesulfonic acid were added, and the mixture was refluxed at 80°C for 2 hours; then diselenyl dibenzyl diselenide was added, and the mixture was refluxed at 90°C for another 4 hours to generate a mercapto-selenodisulfide modified resin. The mass ratio of the hydroxyl-containing fluorinated acrylic copolymer to the mixed solvent was 1:8, and the mass ratio of diselenyl dibenzyl diselenide, mercaptopropionic acid, and the hydroxyl-containing fluorinated acrylic copolymer was 0.2:0.3:1. Figure 1 As shown.

[0046] Graphene was added to a 0.3 mol / L calcium chloride solution and ultrasonically dispersed at 300 W for 20 minutes, with a graphene to calcium chloride solution mass ratio of 1:50, forming a graphene-calcium ion suspension. Fluorite (95% purity) was added to the above graphene-calcium ion suspension and mechanically stirred (400 r / min) until uniformly dispersed. A 0.3 mol / L sodium carbonate solution was added dropwise to adjust the pH to 9, and the mixture was reacted in a constant temperature water bath at 40℃ for 2 hours to allow nano-calcium carbonate to grow in situ between the graphene sheets. The mass ratio of the graphene-calcium chloride mixture to fluorite was 6:1.

[0047] Then, 3% dopamine was added, and the pH of the system was adjusted to 9 with Tris-HCl buffer. The mixture was stirred at 40°C for 2 hours to form a dense modified layer of polydopamine on the surface of the composite solution. Anhydrous ethanol was added to the polydopamine-modified fluorite-graphene-calcium carbonate composite solution, and the mixture was ultrasonically dispersed at 300W for 15 minutes and centrifuged at 10,000 rpm for 15 minutes. The supernatant was then collected for later use.

[0048] Add 2wt% BYK-111 dispersant and 0.5wt% BYK-333 leveling agent to the supernatant of the above composite filler, and ultrasonically disperse at 300W for 15 minutes; slowly drop the mixture into the above-prepared mercapto-selenodisulfide modified resin, and stir in both directions (radial 300r / min, axial 100r / min) for 30 minutes, and continue stirring for 15 minutes to obtain a dan-containing acrylic resin coating. The mass ratio of the mixture to the mercapto-selenodisulfide modified resin is 1:8.

[0049] Comparative Example 1

[0050] A method for preparing a fluorinated acrylic resin coating includes the following steps:

[0051] A hydroxyethyl methacrylate solution was added to a three-necked flask, and the oil bath temperature was raised to 85°C. Azobisisobutyronitrile was dissolved in hexafluorobutyl methacrylate to obtain a mixed solution of hexafluorobutyl methacrylate. The mixed solution of hexafluorobutyl methacrylate was added dropwise to the three-necked flask at a rate of 1 drop / second for 1.5 hours, and the reaction was continued for 3.5 hours to obtain a hydroxyl-containing fluorinated acrylic copolymer solution. The molar ratio of hydroxyethyl methacrylate, hexafluorobutyl methacrylate, and azobisisobutyronitrile was 1:1.5:0.03.

[0052] Graphite powder was added to a 0.2 mol / L calcium chloride solution and ultrasonically dispersed for 15 minutes at 250 W. The mass ratio of graphite powder to calcium chloride solution was 1:45, forming a graphite powder-calcium ion suspension. Iron oxide was added to the above graphite powder-calcium ion suspension and mechanically stirred (300 r / min) until uniformly dispersed. A 0.1 mol / L sodium carbonate solution was added dropwise to adjust the pH to 8, and the mixture was reacted in a constant temperature water bath at 30℃ for 1 hour to obtain a composite filler. The composite filler was then added to anhydrous ethanol and ultrasonically dispersed for 15 minutes at 300 W. The mixture was centrifuged at 10,000 rpm for 15 minutes, and the precipitate was collected for later use. The molar ratio of calcium chloride:iron oxide:graphite powder:sodium carbonate was 1:4:8:1.

[0053] Add 1.5wt% BYK-111 dispersant and 0.4wt% BYK-333 leveling agent to the above precipitate, and ultrasonically disperse at 250W for 10 minutes to obtain a mixture; slowly drop the mixture into the hydroxyl-containing acrylic copolymer prepared above, and continue stirring for 15 minutes to obtain an acrylic resin coating, with the mass ratio of the mixture to the hydroxyl-containing acrylic copolymer being 1:6.

[0054] Comparative Example 2

[0055] A method for preparing a fluorinated acrylic resin coating includes the following steps:

[0056] A hydroxyethyl methacrylate solution was added to a three-necked flask, and the oil bath temperature was raised to 85°C. Azobisisobutyronitrile was dissolved in hexafluorobutyl methacrylate to obtain a mixed solution of hexafluorobutyl methacrylate. The mixed solution of hexafluorobutyl methacrylate was added dropwise to the three-necked flask at a rate of 1 drop / second for 1.5 hours, and the reaction was continued for 3.5 hours to obtain a hydroxyl-containing fluorinated acrylic copolymer solution. The molar ratio of hydroxyethyl methacrylate, hexafluorobutyl methacrylate, and azobisisobutyronitrile was 1:1.4:0.02. Carbon nanotubes were added to a 0.2 mol / L magnesium chloride solution and ultrasonically dispersed at 250 W for 15 minutes, with a mass ratio of carbon nanotubes to magnesium chloride solution of 1:45, forming a carbon nanotube-magnesium ion suspension. Zinc oxide was added to the above carbon nanotube-magnesium ion suspension and mechanically stirred (400 r / min) until uniformly dispersed. A 0.2 mol / L potassium carbonate solution was added dropwise to adjust the pH to 8.5, and the mixture was reacted in a constant temperature water bath at 35℃ for 1.5 hours to allow nano-magnesium carbonate to grow in situ on the surface of carbon nanotubes. The mass ratio of the carbon nanotube-magnesium chloride mixture to zinc oxide was 5:1, and the molar ratio of magnesium chloride:zinc oxide:carbon nanotubes:potassium carbonate was 1:4:8:1. Then add 3% chitosan, adjust the pH of the system to 5.5 with acetate buffer, stir at 35℃ for 1.5 hours to form a modified layer of chitosan on the surface of the composite particles to obtain a surface-modified chitosan solution; add anhydrous methanol to the surface-modified chitosan solution, sonicate at 250W for 10 minutes, centrifuge at 8000rpm for 10 minutes, and take the precipitate for later use.

[0057] Add 1.5wt% TEGODispers 750W dispersant and 0.4wt% TEGOGlide 410 leveling agent to the above precipitate, and ultrasonically disperse at 250W for 10 minutes to obtain a mixture; slowly drop the mixture into the hydroxyl-containing fluorinated acrylic copolymer prepared above, and continue stirring for 15 minutes to obtain a fluorinated acrylic resin coating, with a mass ratio of the mixture to the hydroxyl-containing fluorinated acrylic copolymer of 1:6.

[0058] The coatings prepared in the examples and comparative examples were subjected to the following performance tests:

[0059] 1. Adhesion: The coating surface is bonded to the cylindrical fixture using a cylindrical clamp, and a vertical tensile force is applied by an instrument to measure the maximum load when the coating peels off from the substrate surface.

[0060] 2. Hardness: The pencil method is used, with pencils of different hardness grades applied at a constant pressure at a 45° angle to scratch the coating surface.

[0061] 3. Weather resistance: The coating is exposed to simulated natural climatic conditions and the color difference before and after aging is compared. The weather resistance is quantified by the color difference ΔE. The smaller the ΔE value, the better the weather resistance and the stronger the color stability of the coating.

[0062] 4. Self-healing effect: If the coating has strong self-healing ability after damage, the surface roughness after repair will be close to the undamaged state. The repair effect can be evaluated by comparing the roughness changes before and after repair.

[0063] Table 1. Test results of fluorinated acrylic resin coatings prepared in the examples and comparative examples.

[0064]

[0065] In Examples 1-3, the hydroxyl-containing acrylic copolymers form hydrogen bonds with the polar groups on the substrate surface, while the thiol groups can form coordination bonds with the metal substrate surface. This dual interaction enhances interfacial bonding. Comparative Examples 1 and 2, lacking thiol modification, exhibit weaker interfacial interactions. In Examples 1-3, the graphene sheet structure possesses extremely high Young's modulus. Nano-calcium carbonate grows in situ between its sheets, effectively transferring stress and hindering crack propagation. Comparative Example 1 uses graphite powder, and Comparative Example 2 uses carbon nanotubes; both show poor filler reinforcement. In Examples 1-3, the thiol-selenodisulfide structure can form reversible crosslinks through dynamic covalent bonds, improving the rigidity of the resin matrix. Comparative Examples 1 and 2, lacking dynamic crosslinking structures, suffer from insufficient resin rigidity. In Examples 1-3, the selenodisulfide bonds can undergo reversible breakage and recombination under light or heat stimulation, autonomously repairing microcracks caused by early aging and delaying coating failure. Comparative Examples 1 and 2 lack such dynamic structures, leading to continuous accumulation of aging damage. When cracks appear in the coatings of Examples 1-3, the broken Se-S bonds can be reconnected through diffusion of adjacent molecular chains, achieving self-healing. Comparative Examples 1 and 2 have no dynamic chemical bonds and have almost no healing ability.

[0066] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0067] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A method for preparing a fluorinated acrylic resin coating, characterized in that, Includes the following steps: Hydroxyethyl methacrylate and hexafluorobutyl methacrylate were copolymerized under the action of an initiator to obtain a hydroxyl-containing fluorinated acrylic copolymer. The hydroxyl-containing fluorinated acrylic copolymer was dissolved in a mixed solvent of anhydrous tetrahydrofuran and acetone, and mercaptopropionic acid, p-toluenesulfonic acid and diselenyl dibenzyl were added in sequence and refluxed to obtain a mercapto-selenodisulfide modified resin solution. A calcium chloride solution was added to graphene, and the mixture was ultrasonically dispersed to form a graphene-calcium chloride mixture. Then, fluorite was added, and after mechanical stirring, sodium carbonate solution was added to adjust the pH to 8-9 to prepare a fluorite-graphene-calcium carbonate composite solution. The fluorite-graphene-calcium carbonate composite solution was modified with dopamine, and the supernatant was removed by centrifugation to obtain fluorite-graphene-calcium carbonate composite particles with surface-modified polydopamine. A dispersant and a leveling agent were added to the surface-modified polydopamine-cored fluorite-graphene-calcium carbonate composite particles to obtain a mixture. Then, a mercapto-selenium disulfide modified resin solution was added and mixed, followed by bidirectional stirring to obtain the fluorinated acrylic resin coating.

2. The method for preparing a fluorinated acrylic resin coating according to claim 1, characterized in that, The initiator is azobisisobutyronitrile; the molar ratio of hydroxyethyl methacrylate, hexafluorobutyl methacrylate and azobisisobutyronitrile is 1:(1.2-1.6):(0.01-0.03).

3. The method for preparing a fluorinated acrylic resin coating according to claim 1, characterized in that, The mixed solvent is anhydrous tetrahydrofuran and acetone, with a volume ratio of 1:

1. The mass ratio of the hydroxyl-containing fluorinated acrylic copolymer to the mixed solvent is 1:(4-8). The mass ratio of diselenide dibenzyl, mercaptopropionic acid to the hydroxyl-containing fluorinated acrylic copolymer is (0.05-0.2):(0.1-0.3):

1.

4. The method for preparing a fluorinated acrylic resin coating according to claim 1, characterized in that, The mass ratio of graphene to calcium chloride solution is 1:(40-50), the mass ratio of graphene-calcium chloride mixture to fluorite is (4-6):1, the concentration of sodium carbonate solution is 0.1-0.3 mol / L, and fluorite is a fluorine-containing compound containing Na3FeF6.

5. The method for preparing a fluorinated acrylic resin coating according to claim 4, characterized in that, The concentration of the calcium chloride solution is 0.1-0.3 mol / L, the ultrasonic power is 200-300W, and the duration is 10-20 minutes.

6. The method for preparing a fluorinated acrylic resin coating according to claim 1, characterized in that, The dopamine modification of the fluorite-graphene-calcium carbonate composite solution includes: adding 3% dopamine to the fluorite-graphene-calcium carbonate composite solution, adjusting the pH to 8-9 with Tris-HCl buffer, and reacting at 30-40℃ for 1-2 hours.

7. The method for preparing a fluorinated acrylic resin coating according to claim 1, characterized in that, The centrifugation process involves adding anhydrous ethanol to a dopamine-modified fluorite-graphene-calcium carbonate composite solution, ultrasonically dispersing it at 200-300W for 10-15 minutes, centrifuging it at 8000-10000rpm for 10-15 minutes, and removing the supernatant to obtain fluorite-graphene-calcium carbonate composite particles with surface-modified polydopamine.

8. The method for preparing a fluorinated acrylic resin coating according to claim 1, characterized in that, The dispersant is BYK-111, which accounts for 1 wt%-2 wt% of the mixture, and the leveling agent is BYK-333, which accounts for 0.3%-0.5% of the mixture.

9. The method for preparing a fluorinated acrylic resin coating according to claim 1, characterized in that, The mass ratio of the mixture to the mercapto-selenium disulfide modified resin solution is 1:(5-8).

10. The method for preparing a fluorinated acrylic resin coating according to claim 1, characterized in that, The bidirectional stirring is performed at a radial speed of 300 r / min and an axial speed of 100 r / min for 20-30 minutes, followed by stirring for another 10-15 minutes.

Images