Modified FEVE fluorocarbon resin coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to a modified FEVE fluorocarbon resin coating and a preparation method thereof. The problem that the FEVE fluorocarbon coating is poor in durability is solved. The preparation method comprises the following steps: modifying FEVE fluorocarbon resin with linoleic acid to obtain a granular material; stirring the modified FEVE fluorocarbon resin, polyisocyanate, montmorillonite and a composite solvent to obtain a prepolymer; pre-dispersing and grinding silicon carbide, modified zinc oxide, a dispersing agent and a composite solvent, adding nano composite particles for ultrasonic dispersion, and adding a prepolymer and a flatting agent to obtain the modified FEVE fluorocarbon resin coating. Wherein the FEVE fluorocarbon resin is modified, so that the crosslinking speed, the coating strength and the adhesive force are improved, the stain resistance, the weather resistance and the corrosion resistance are improved through the nano composite particles and the like, and finally the durability of the FEVE fluorocarbon resin coating is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, in particular to a modified FEVE fluorocarbon resin coating and a preparation method thereof. Background Art

[0002] FEVE coatings, with their excellent corrosion resistance, weather resistance, and strong adhesion, are widely used for the protection of aircraft, ships, bridges, and other structures. Currently, the domestic market is dominated by solvent-based and water-based two-component FEVE resin coatings. Water-based two-component FEVE coatings, in particular, are widely used for the protection of large civil, defense, and aerospace structures due to their superior corrosion resistance, weather resistance, stain resistance, and solvent resistance. However, two-component water-based fluorocarbon coatings have complex construction processes, and single-component water-based fluorocarbon resins suffer from poor adhesion, low hardness, and weak impact resistance.

[0003] In order to solve the problems of slow drying speed and poor adhesion of one-component water-based FEVE fluorocarbon coatings, the strong activity of the hydroxyl groups in the FEVE fluorocarbon resin main chain is utilized to modify the FEVE fluorocarbon resin, which can effectively improve the strength and adhesion of the coating. The modification can also effectively increase the cross-linking speed of the coating during the curing process, thereby increasing the drying speed of the coating. In summary, due to the poor adhesion and corrosion resistance of one-component water-based FEVE fluorocarbon coatings, the current FEVE fluorocarbon coatings have poor durability, which greatly limits the promotion and application of FEVE fluorocarbon coatings.

[0004] Therefore, a modified FEVE fluorocarbon resin coating and a preparation method thereof are proposed. Summary of the Invention

[0005] The present invention aims to design a modified FEVE fluorocarbon resin coating and its preparation method. The present invention uses linoleic acid to modify FEVE fluorocarbon resin to obtain a dispersion; the modified FEVE fluorocarbon resin is stirred with a polyisocyanate, montmorillonite, and a composite solvent to obtain a prepolymer; silicon carbide and modified zinc oxide are pre-dispersed and ground with a dispersant and a composite solvent; nanocomposite particles are added and ultrasonically dispersed; and the prepolymer and a leveling agent are added to obtain the modified FEVE fluorocarbon resin coating. The modification of the FEVE fluorocarbon resin improves crosslinking speed, coating strength, and adhesion, while the nanocomposite particles enhance stain resistance, weather resistance, and corrosion resistance, ultimately increasing the durability of the FEVE fluorocarbon resin coating.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In one aspect, the present invention provides a method for preparing a modified FEVE fluorocarbon resin coating, the preparation method comprising the following steps:

[0008] FEVE fluorocarbon resin is modified by using linoleic acid to obtain a modified FEVE fluorocarbon resin dispersion;

[0009] Adding a modified FEVE fluorocarbon resin dispersion, polyisocyanate, montmorillonite and a composite solvent into a reaction kettle, respectively, and stirring to obtain a prepolymer; the composite solvent is a mixture of butyl acetate and xylene in a weight ratio of 2:1;

[0010] Silicon carbide, modified zinc oxide and a dispersant are mixed, a composite solvent is added, and pre-dispersed and ground to obtain a dispersion system; nanocomposite particles are then added, and after ultrasonic dispersion, prepolymer and a leveling agent are added to obtain a modified FEVE fluorocarbon resin coating;

[0011] The modified zinc oxide is obtained by modifying the surface of zinc oxide with thiol; the nanocomposite particles include modified nano titanium dioxide and graphene oxide; and the modified nano titanium dioxide is obtained by grafting modification of nano titanium dioxide.

[0012] Preferably, the preparation method of the modified FEVE fluorocarbon resin dispersion is as follows: 40-50 parts of linoleic acid, 18 parts of trimethylolpropane, 10-15 parts of FEVE fluorocarbon resin, 2.5 parts of polypropylene glycol, 1 part of pentaerythritol, 2.5 parts of adipic acid, 13 parts of phthalic anhydride and 0.1 parts of dibutyltin dilaurate are added to a flask, and xylene is added as a reflux agent, and the mixture is stirred and heated under N2 atmosphere, and the mixture is kept at 150°C. The mixture was refluxed under warm condensation for 1 hour. After the sublimed phthalic anhydride disappeared, the temperature was continued to be raised to 220°C and deep esterification was carried out for 4 hours. After the acid value was lower than 3 mgKOH / g, the mixture was vacuumed and depressurized for 1 hour. The temperature was adjusted to 180°C, 5 parts of trimellitic anhydride were added, and the mixture was reacted for 2 hours. The temperature was then lowered to 80°C, the pH value was adjusted to neutral, and butyl acetate was added until the solid content of the system was 70%-80%. After stirring for 30 minutes, the mixture was filtered to obtain a modified FEVE fluorocarbon resin dispersion.

[0013] Preferably, the specific process of the stirring treatment is as follows, by weight: 55-65 parts of modified FEVE fluorocarbon resin dispersion and 20 parts of composite solvent are added to the reactor, stirred for 30 minutes, and then 20-30 parts of polyisocyanate are added three times, with an interval of 10 minutes between each addition, and stirred for 8 minutes after each addition. After all the polyisocyanate is added and stirred evenly, 1-5 parts of montmorillonite are slowly added to the reactor, heated to 80°C and stirred for 3 hours to obtain a prepolymer; the polyisocyanate contains a silicon propoxy group and an NCO content of 15%-18%.

[0014] Preferably, the preparation method of the modified zinc oxide is as follows, in parts by weight: 90-100 parts of zinc oxide powder are added to 500 parts of deionized water, stirred evenly to form a suspension, the pH is adjusted to 7, ultrasonically dispersed for 30 minutes, filtered, washed with deionized water until neutral, and dried to obtain pretreated zinc oxide; 5-10 parts of 3-mercaptopropionic acid are dissolved in 200 parts of anhydrous ethanol, stirred evenly to prepare a modifier solution; the pretreated zinc oxide is added to the modifier solution, stirred and reacted in a constant temperature water bath at 60°C under nitrogen protection for 3h-5h, and after the reaction is completed, cooled to room temperature, filtered to separate the solid product, and washed in vacuum to obtain the modified zinc oxide.

[0015] Preferably, the specific process of pre-dispersion grinding is as follows, by weight: 10-15 parts of silicon carbide, 4-8 parts of modified zinc oxide and 30 parts of a composite solvent are added to a stirring container and stirred for 10-20 minutes to form a premixed slurry; the premixed slurry is transferred to a bead mill, zirconium oxide beads are selected as the grinding medium, and zirconium oxide beads are filled according to 70% of the volume of the bead mill. The bead mill is turned on for grinding, the temperature is controlled at 35°C, and the grinding is continued for 80-100 minutes. When the grinding is carried out for 60 minutes, 1 part of dispersant BYK-163 is slowly added to the bead mill, and the grinding is continued for 30 minutes. After the grinding is completed, it is filtered through a 100-mesh filter to obtain a dispersed system.

[0016] Preferably, the preparation method of the nanocomposite particles is as follows: adding 90-100 parts of nano-titanium dioxide to 500 parts of anhydrous ethanol, ultrasonically dispersing for 30 minutes to form a uniform suspension; filtering and separating the solid, and vacuum drying to obtain pretreated nano-titanium dioxide; adding the pretreated nano-titanium dioxide, 500 parts of toluene and 0.5 parts of dibutyltin dilaurate to a four-necked flask, passing nitrogen protection, reflux at 110° C. for 1 hour, and then slowly adding 15-25 parts of glycidyl methacrylate dropwise for 30 minutes. After the dropwise addition is completed, the reaction is continued for 5h-7h; after the reaction is completed, it is cooled to room temperature, washed and vacuum-dried to obtain modified nano-titanium dioxide; 10-20 parts of modified nano-titanium dioxide, 3-7 parts of graphene oxide and 80 parts of butyl acetate are added to the reactor, and stirred at a speed of 1000 rpm for 10 minutes to form an initial mixed solution; then the ultrasonic device is turned on and ultrasonic stirring is carried out for 20 minutes, followed by adding 1 part of fluorocarbon surfactant FC-4430, continuing stirring for 15 minutes, and then passing through a 100-mesh filter to obtain nano-composite particles.

[0017] Preferably, the specific process of ultrasonic dispersion is: adding 3-5 parts of nanocomposite particles to the dispersion system, adding prepolymer and 0.5-1 part of leveling agent BYK300 after ultrasonic dispersion for 30 minutes, continuing stirring for 30 minutes, and passing through a 100 mesh sieve to obtain a modified FEVE fluorocarbon resin coating.

[0018] Another aspect of the present invention provides a modified FEVE fluorocarbon resin coating, which includes a modified FEVE fluorocarbon resin dispersion, polyisocyanate, montmorillonite, silicon carbide, modified zinc oxide, a dispersant, nanocomposite particles, a leveling agent and a composite solvent.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The modified FEVE fluorocarbon resin dispersion, after being modified with linoleic acid, provides abundant active hydroxyl groups, which react with polyisocyanates to form an interpenetrating network with fluorocarbon as the main chain and silicon oxide as the side chains, giving the coating excellent weather resistance and corrosion resistance. Montmorillonite induces the directional arrangement of the resin molecular chains under the staged heating process, forming a gradient cross-linking structure, enhancing the hardness and flexibility of the coating. At the same time, its nanosheets block the corrosive medium and form hydrogen bonds with the silicon hydroxyl groups generated by the hydrolysis of polyisocyanates, strengthening the interfacial bonding between the filler and the resin. The three factors synergistically optimize the functional properties of the coating and significantly improve the durability of the coating.

[0021] 2. Silicon carbide provides a physical barrier with its high hardness, effectively resisting mechanical wear and penetration of corrosive media. Modified zinc oxide releases zinc ions through surface thiol modification to achieve chemical corrosion inhibition. In the pre-dispersion grinding process, the two are infiltrated with composite solvents and acted on by dispersants. With the help of the shear force and impact force of the grinding equipment, they are evenly dispersed and refined to the ideal particle size. This not only strengthens the coupling effect of physical barrier and chemical corrosion inhibition, but also improves the compatibility with subsequent nano-composite particles and prepolymers, ensuring uniform distribution of each component, and ultimately forming a dense and stable coating structure, significantly enhancing the corrosion resistance of the coating.

[0022] 3. Among the nanocomposite particles, the photocatalytic activity of modified nano-titanium dioxide gives the coating a self-cleaning function, and the two-dimensional barrier structure of graphene oxide improves weather resistance and impermeability. The leveling agent reduces the surface tension of the coating, promotes the uniform spreading of nano-composite particles on the coating surface, reduces agglomeration and pores, and enables the nanoparticles to fully exert their functions; at the same time, the leveling agent improves the flatness of the coating and enhances the efficiency of nano-titanium dioxide in receiving light. The two work together to optimize the microstructure of the coating surface and significantly improve the durability of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The flowchart of the preparation method of the modified FEVE fluorocarbon resin coating of the present invention is shown in FIG. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Specific reference Figure 1 The present invention provides a modified FEVE fluorocarbon resin coating and a preparation method thereof, and the technical solution is as follows:

[0026] Example 1

[0027] 95 parts of zinc oxide powder were added to 500 parts of deionized water, stirred evenly to form a suspension, the pH was adjusted to 7, ultrasonically dispersed for 30 minutes, filtered, washed with deionized water until neutral, and dried to obtain pretreated zinc oxide; 8 parts of 3-mercaptopropionic acid were dissolved in 200 parts of anhydrous ethanol, stirred evenly to prepare a modifier solution; the pretreated zinc oxide was added to the modifier solution, stirred and reacted in a constant temperature water bath at 60°C for 4 hours under nitrogen protection, and after the reaction was completed, cooled to room temperature, filtered to separate the solid product, and washed in vacuum to obtain modified zinc oxide.

[0028] 95 parts of nano-titanium dioxide were added to 500 parts of anhydrous ethanol and ultrasonically dispersed for 30 minutes to form a uniform suspension; the solid was separated by suction filtration and vacuum dried to obtain pretreated nano-titanium dioxide; pretreated nano-titanium dioxide, 500 parts of toluene and 0.5 parts of dibutyltin dilaurate were added to a four-necked flask, nitrogen was introduced, and the mixture was refluxed at 110° C. for 1 hour, followed by slow dropwise addition of 20 parts of glycidyl methacrylate for 30 minutes. After the addition was complete, the reaction was continued for 6 hours; after the reaction was completed, the mixture was cooled to room temperature, washed and vacuum dried to obtain modified nano-titanium dioxide; 15 parts of modified nano-titanium dioxide, 5 parts of graphene oxide and 80 parts of butyl acetate were added to the reactor and stirred at 1000 rpm for 10 minutes to form an initial mixed solution; the ultrasonic device was then turned on and ultrasonic stirring was carried out for 20 minutes, followed by addition of 1 part of fluorocarbon surfactant FC-4430, continued stirring for 15 minutes, and then passed through a 100-mesh filter to obtain nano-composite particles.

[0029] Preparation of modified FEVE fluorocarbon resin coating:

[0030] 45 parts of linoleic acid, 18 parts of trimethylolpropane, 12 parts of FEVE fluorocarbon resin, 2.5 parts of polypropylene glycol, 1 part of pentaerythritol, 2.5 parts of adipic acid, 13 parts of phthalic anhydride and 0.1 parts of dibutyltin dilaurate were added to a flask, and xylene was added as a reflux agent. The mixture was stirred and heated under N2 atmosphere, and refluxed at a constant temperature of 150°C for 1 hour. After the sublimed phthalic anhydride disappeared, the temperature was continued to be raised to 220°C, and deep esterification was carried out for 4 hours. After the acid value was lower than 3 mgKOH / g, the mixture was vacuumed and depressurized for 1 hour, the temperature was adjusted to 180°C, 5 parts of trimellitic anhydride were added, the reaction was carried out for 2 hours, and then the temperature was lowered to 80°C. The pH value was adjusted to neutral, and butyl acetate was added until the solid content of the system was 75%; after stirring for 30 minutes, the mixture was filtered to obtain a modified FEVE fluorocarbon resin dispersion;

[0031] 60 parts of modified FEVE fluorocarbon resin dispersion and 20 parts of composite solvent were added to a reactor and stirred for 30 minutes. Then, 25 parts of polyisocyanate were added in three times with an interval of 10 minutes between each addition and stirred for 8 minutes after each addition. After all the polyisocyanate was added and stirred evenly, 3 parts of montmorillonite were slowly added to the reactor, and the temperature was raised to 80°C and stirred for 3 hours to obtain a prepolymer.

[0032] 12 parts of silicon carbide, 6 parts of modified zinc oxide, and 30 parts of a composite solvent were added to a stirring container and stirred for 15 minutes to form a premixed slurry. The premixed slurry was transferred to a bead mill, and zirconium oxide beads were selected as the grinding medium. The zirconium oxide beads were filled to 70% of the volume of the bead mill. The bead mill was started for grinding at a temperature of 35° C. and the grinding was continued for 90 minutes. When the grinding was carried out for 60 minutes, 1 part of dispersant BYK-163 was slowly added to the bead mill, and the grinding was continued for 30 minutes. After the grinding was completed, the dispersion was filtered through a 100-mesh filter to obtain a dispersion system.

[0033] 4 parts of nanocomposite particles were added to the dispersion system, and after ultrasonic dispersion for 30 minutes, the prepolymer and 0.8 parts of leveling agent BYK300 were added, and stirring was continued for 30 minutes. The modified FEVE fluorocarbon resin coating was obtained after passing through a 100-mesh sieve.

[0034] Examples 2-9 refer to the parameter conditions in Example 1, and the specific differences are shown in Table 1.

[0035] The parameter conditions of Examples 1, 4 and 7 are all the same.

[0036] Table 1 Parameter conditions of Examples 1-9 Comparative Example 1 Refer to the parameter conditions in Example 1, except that the FEVE fluorocarbon resin is not modified.

[0037] Comparative Example 2 refers to the parameter conditions in Example 1, except that no polyisocyanate is added.

[0038] Comparative Example 3 refers to the parameter conditions in Example 1, except that montmorillonite is not added.

[0039] Experimental Example 1 Adhesion, Weathering and Corrosion Resistance Tests

[0040] Adhesion of Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T 9286-1998. Weather resistance of the coatings was tested by exposing them to outdoor sunlight for 8000 hours. Acid resistance was tested by immersing them in a 50g / L H2SO4 solution for 7 days, and alkali resistance was tested by immersing them in a 50g / L NaOH solution for 7 days. The coatings were considered to have passed the test if there was no blistering, rusting, cracking, or shedding. The results are shown in Table 2.

[0041] Table 2 Adhesion, weather resistance and corrosion resistance of Examples 1-3 and Comparative Examples 1-3

[0042] Example Adhesion / Grade Weather resistance Acid resistance Alkali resistance Example 1 0 excellent pass pass Example 2 0 excellent pass pass Example 3 0 excellent pass pass Comparative Example 1 3 Difference Fail Fail Comparative Example 2 2 Poor Fail Fail Comparative Example 3 1-2 medium Fail Fail

[0043] It can be seen from Table 2 that the comprehensive performance of the embodiments is relatively strong. The unmodified FEVE fluorocarbon resin in Comparative Example 1 is unable to fully cross-link with polyisocyanate due to insufficient hydroxyl activity, resulting in weak chemical bonding between the coating and the substrate, decreased adhesion, and severe fading and powdering of the coating after outdoor exposure, and is unable to resist acid and alkali corrosion. In Comparative Example 2, polyisocyanate is a key component for forming an interpenetrating network with fluorocarbon as the main chain and silicon oxygen as the side chain. Its absence causes the resin to form a film only through physical adsorption, resulting in a decrease in adhesion level, and insufficient cross-linking density causes the weather resistance of the coating to decrease, resulting in obvious fading, and easy penetration by corrosive media in acid and alkali environments. In Comparative Example 3, montmorillonite was not added. The interlayer intercalation effect of montmorillonite can induce the directional arrangement of the resin molecular chains, forming a gradient structure with high cross-linking density on the surface and low cross-linking density on the inner layer. After the montmorillonite is missing, the cross-linking density of the coating is uniform but low overall, and the adhesion is slightly reduced. Although the weather resistance and acid and alkali resistance are better than the first two comparative examples, the overall protective ability is weakened.

[0044] In summary, modified FEVE fluorocarbon resin is the core of improving adhesion. Hydroxyl groups are introduced through linoleic acid, and chemically cross-linked with polyisocyanates to form a strong skeleton. Polyisocyanates are the key to building corrosion-resistant and weather-resistant networks. Their silyl propoxy groups hydrolyze to form siloxy bonds, enhancing chemical stability, and at the same time synergistically forming a gradient structure with montmorillonite. Montmorillonite further optimizes the mechanical properties and resistance to medium penetration of the coating through nano-barriers and induced cross-linking density gradients. All three are indispensable and together solve the problem of poor durability of traditional FEVE fluorocarbon coatings.

[0045] Comparative Example 4 refers to the parameter conditions in Example 4, except that the zinc oxide is not modified.

[0046] Comparative Example 5 refers to the parameter conditions in Example 4, except that modified zinc oxide is not added.

[0047] Comparative Example 6 refers to the parameter conditions in Example 4, except that silicon carbide is not added.

[0048] Comparative Example 7 refers to the parameter conditions in Example 4, except that the dispersant BYK-163 is not added.

[0049] Comparative Example 8 refers to the parameter conditions in Example 4, except that no pre-dispersion grinding treatment is performed.

[0050] Experimental Example 2 Corrosion resistance and hardness test

[0051] The corrosion resistance of Examples 4-6 and Comparative Examples 4-8 was tested according to the method of Experimental Example 1. The hardness of Examples 4-6 and Comparative Examples 4-8 was tested according to the GB / T 6739-2006 standard. The results are shown in Table 3.

[0052] Table 3 Corrosion resistance and hardness of Examples 4-6 and Comparative Examples 4-8

[0053] Example Acid resistance Alkali resistance Hardness / H Example 4 pass pass 5H Example 5 pass pass 5H Example 6 pass pass 5H Comparative Example 4 Fail Fail 3H Comparative Example 5 Fail Fail 2H Comparative Example 6 Fail Fail 3H Comparative Example 7 Fail Fail 3H Comparative Example 8 Fail Fail 2H

[0054] It can be found from Table 3 that the corrosion resistance and hardness of the examples are relatively strong. In Comparative Example 4, the surface of the unmodified zinc oxide lacks thiol groups and cannot form chemical adsorption with the resin. The efficiency of zinc ion release is low, and it is difficult to construct a coupled system of physical barrier and chemical corrosion inhibition; in acid and alkali solutions, the coating is directly corroded due to the lack of chemical corrosion inhibition, and both acid resistance and alkali resistance are not passed; at the same time, the filler and the resin interface are weakly bonded, and the hardness is reduced. In Comparative Example 5, the thiol group of the modified zinc oxide can release zinc ions to form a passivation film. Its absence causes the coating to rely solely on the physical barrier of silicon carbide and cannot resist the penetration of highly corrosive media; the decrease in hardness indicates that the physical barrier is not sufficient to support the mechanical properties of the coating. In Comparative Example 6, the high hardness of silicon carbide is the core of constructing a mechanical barrier. Its absence causes the coating to be easily penetrated by corrosive media and the acid / alkali resistance is not passed; the decrease in hardness indicates a lack of rigid filler support and a weakened ability of the coating to resist deformation. In Comparative Example 7, BYK-163 ensures uniform filler dispersion through electrostatic repulsion and steric hindrance. In the absence of a dispersant, silicon carbide and modified zinc oxide aggregate to form pores, allowing corrosive media to easily penetrate through these defects, resulting in a decrease in corrosion resistance. Furthermore, the aggregates reduce the effective contact area between the filler and the resin, reducing hardness. In Comparative Example 8, pre-dispersion grinding reduces the filler particle size to the ideal range through mechanical shear forces. Without grinding, the filler particles are coarse and unevenly distributed, creating stress concentration points and penetration channels, resulting in a significant decrease in corrosion resistance and hardness.

[0055] The chemical inhibition of modified zinc oxide and the physical barrier of silicon carbide are the core elements of corrosion resistance, and neither is indispensable. Dispersants and pre-dispersion grinding processes are key to ensuring uniform dispersion of fillers and achieving a synergistic effect. The absence of a single component or process defects can lead to a loose coating structure and weak interfacial bonding, ultimately significantly reducing corrosion resistance and hardness.

[0056] Comparative Example 9 refers to the parameter conditions in Example 7, except that the titanium dioxide is not modified.

[0057] Comparative Example 10 refers to the parameter conditions in Example 7, except that only modified titanium dioxide is added when preparing the coating.

[0058] Comparative Example 11 refers to the parameter conditions in Example 7, except that only graphene oxide is added when preparing the coating.

[0059] Comparative Example 12 refers to the parameter conditions in Example 7, except that no nanocomposite particles are added.

[0060] Comparative Example 13 refers to the parameter conditions in Example 7, except that the leveling agent BYK300 is not added.

[0061] Comparative Example 14 refers to the parameter conditions in Example 7, except that ultrasonic dispersion and stirring and sieving are not performed.

[0062] Experimental Example 3 Weather resistance and water resistance test

[0063] The weather resistance of Examples 7-9 and Comparative Examples 9-14 was tested using the same method as in Experimental Example 1. The water resistance of Examples 7-9 and Comparative Examples 9-14 was tested by immersion in water at 40°C for 7 days. The samples were considered to have passed if no blistering or cracking occurred. The results are shown in Table 4.

[0064] Table 4 Weather resistance and water resistance of Examples 7-9 and Comparative Examples 9-14

[0065] Example Weather resistance Water resistance Example 7 pass pass Example 8 pass pass Example 9 pass pass Comparative Example 9 Fail Fail Comparative Example 10 Fail Fail Comparative Example 11 Fail Fail Comparative Example 12 Fail Fail Comparative Example 13 Fail Fail Comparative Example 14 Fail Fail

[0066] It can be seen from Table 4 that the durability of the embodiments is good. In Comparative Example 9, the unmodified titanium dioxide is prone to generate free radicals due to the photocatalytic effect, which leads to the breakage of the coating polymer chain and accelerated aging; and the surface hydroxyl groups are easy to absorb water, destroying the interfacial bonding force of the coating, resulting in blistering and cracking after water penetration. In Comparative Example 10, although the modified titanium dioxide can partially absorb ultraviolet rays, it lacks the two-dimensional barrier effect of graphene oxide and cannot effectively block the penetration of small molecules such as water and oxygen. In Comparative Example 11, graphene oxide itself has no ultraviolet absorption ability and cannot resist photoaging. The coating is easily degraded by light; although graphene oxide has a physical barrier effect, its oxygen-containing groups will increase the hygroscopicity of the coating, and the structure is easily destroyed after long-term immersion in water. In Comparative Example 12, when there is no nanoparticle reinforcement, the coating lacks light-stabilizing components and physical barrier layers and cannot resist ultraviolet rays and water erosion. In Comparative Example 13, the leveling agent reduces the coating's surface tension and promotes uniform film formation. However, its absence can lead to defects such as craters and orange peels in the coating, creating channels for water and UV penetration, and reducing weather and water resistance. In Comparative Example 14, without ultrasonic dispersion and stirring and screening, the nanoparticles tend to agglomerate, resulting in uneven filler dispersion, stress concentration points, and weak areas in the coating. Failure to screen the nanoparticles can also leave large impurities, disrupting the coating's continuity and reducing its overall protective capabilities.

[0067] Modified titanium dioxide is compounded with graphene oxide to form a dual protection system of photocatalytic inhibition and physical barrier. The former resists ultraviolet rays, and the latter blocks water and oxygen penetration. The leveling agent works together with the ultrasonic dispersion process to ensure the uniform dispersion of nanoparticles and avoid coating defects caused by agglomeration. At the same time, the leveling agent reduces surface tension and makes the coating film denser. Nanocomposite particles cooperate with other fillers (such as silicon carbide, modified zinc oxide) and resin matrix to construct a multi-layer protective structure, which synergistically enhances the physical barrier, chemical corrosion inhibition and light stability properties, and jointly improves the durability of the coating.

[0068] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a modified FEVE fluorocarbon resin coating, characterized in that: The preparation method comprises the following steps: FEVE fluorocarbon resin is modified by using linoleic acid to obtain a modified FEVE fluorocarbon resin dispersion; The modified FEVE fluorocarbon resin dispersion, polyisocyanate, montmorillonite and a composite solvent are added to a reaction kettle respectively, and stirred to obtain a prepolymer; the composite solvent includes butyl acetate and xylene; Silicon carbide, modified zinc oxide and a dispersant are mixed, the composite solvent is added, and the mixture is pre-dispersed and ground to obtain a dispersion system; nanocomposite particles are then added, and the prepolymer and a leveling agent are added after ultrasonic dispersion to obtain the modified FEVE fluorocarbon resin coating; The modified zinc oxide is obtained by modifying the surface of zinc oxide with thiol; the nanocomposite particles include modified nano titanium dioxide and graphene oxide; and the modified nano titanium dioxide is obtained by grafting modification of nano titanium dioxide.

2. The method for preparing a modified FEVE fluorocarbon resin coating according to claim 1, wherein: The preparation method of the modified FEVE fluorocarbon resin dispersion is as follows: adding the linoleic acid, trimethylolpropane, the FEVE fluorocarbon resin, polypropylene glycol, pentaerythritol, adipic acid, phthalic anhydride and dibutyltin dilaurate into a flask, and then adding the xylene as a reflux agent, stirring and heating under the protection of N2 atmosphere, condensing and refluxing, and after the sublimated phthalic anhydride disappears, continuing to heat and deeply esterify, then vacuuming and reducing the pressure to react, and then adding trimellitic anhydride. After the reaction, the pH value is adjusted to neutral, and the butyl acetate is added for stirring treatment; after stirring, filtering is performed to obtain the modified FEVE fluorocarbon resin dispersion.

3. The method for preparing a modified FEVE fluorocarbon resin coating according to claim 1, characterized in that: The specific process of the stirring treatment is as follows: adding the modified FEVE fluorocarbon resin dispersion and the composite solvent to a reactor and stirring evenly, then adding the polyisocyanate three times, stirring after each addition, and after all the polyisocyanate is added and stirred evenly, slowly adding the montmorillonite to the reactor, heating and continuously stirring to obtain the prepolymer.

4. The method for preparing a modified FEVE fluorocarbon resin coating according to claim 1, wherein: The preparation method of the modified zinc oxide is as follows: adding zinc oxide powder to deionized water, stirring uniformly to form a suspension, adjusting the pH to neutral, ultrasonically dispersing, filtering, washing to neutrality, and drying to obtain pretreated zinc oxide; Dissolve 3-mercaptopropionic acid in anhydrous ethanol and stir evenly to prepare a modifier solution; add the pretreated zinc oxide to the modifier solution, stir and react in a water bath under nitrogen protection, cool to room temperature after the reaction is completed, filter and separate the solid product, wash in vacuum to obtain the modified zinc oxide.

5. The method for preparing a modified FEVE fluorocarbon resin coating according to claim 1, characterized in that: The specific process of the pre-dispersion grinding is as follows: adding the silicon carbide, the modified zinc oxide and the composite solvent into a stirring container, and stirring to form a pre-mixed slurry; The premixed slurry is transferred to a bead mill for grinding. During the grinding process, the dispersant BYK-163 is slowly added to the bead mill and the grinding is continued. After the grinding is completed, the mixture is filtered through a filter to obtain the dispersed system.

6. The method for preparing a modified FEVE fluorocarbon resin coating according to claim 1, characterized in that: The preparation method of the nanocomposite particles is as follows: adding the nano titanium dioxide into anhydrous ethanol and ultrasonically dispersing the nano titanium dioxide to form a uniform suspension; The solid is separated by suction filtration and vacuum dried to obtain pretreated nano-titanium dioxide; the pretreated nano-titanium dioxide, toluene and dibutyltin dilaurate are added to a flask, nitrogen is introduced for protection, glycidyl methacrylate is slowly added dropwise after reflux, and the reaction is continued after the addition is completed; after the reaction is completed, the mixture is washed and vacuum dried to obtain the modified nano-titanium dioxide; the modified nano-titanium dioxide, the graphene oxide and the butyl acetate are added to a reactor and stirred to form an initial mixed solution; followed by ultrasonic stirring, the fluorocarbon surfactant FC-4430 is added, the stirring is continued and the mixture is filtered to obtain the nano-composite particles.

7. The method for preparing a modified FEVE fluorocarbon resin coating according to claim 1, characterized in that: The specific process of the ultrasonic dispersion is: adding the nanocomposite particles into the dispersion system, adding the prepolymer and the leveling agent BYK300 after ultrasonic dispersion, and continuing to stir and filter to obtain the modified FEVE fluorocarbon resin coating.

8. A modified FEVE fluorocarbon resin coating, characterized in that: The modified FEVE fluorocarbon resin coating is prepared by the preparation method according to any one of claims 1 to 7; the modified FEVE fluorocarbon resin coating comprises a modified FEVE fluorocarbon resin dispersion, polyisocyanate, montmorillonite, silicon carbide, modified zinc oxide, a dispersant, nanocomposite particles, a leveling agent and a composite solvent.

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