Flexible fluorocarbon paint and method of making

Abstract

The application discloses a kind of flexible fluorocarbon paint and preparation method, it is related to coating technical field.The flexible fluorocarbon paint, comprising the following weight parts raw materials: 40-55 parts modified fluorocarbon resin, 15-25 parts hydroxyl acrylic resin, 5-10 parts modified nanometer titanium dioxide, 3-8 parts barium sulfate, 2-6 parts talcum powder, 0.5-1.5 parts polyacrylic acid salt, 0.3-1 part polydimethylsiloxane, 0.2-0.8 parts acrylate leveling agent, 2-5 parts epoxy soybean oil, 8-15 parts toluene diisocyanate, 10-20 parts xylene and butyl acetate mixed liquid, 0.5-1.2 parts silane coupling agent KH-550, 0.3-0.8 parts organic bentonite.The raw material of the application is scientifically proportioned, and the performance of each component is synergistically improved, such as modified fluorocarbon resin to enhance weather resistance, modified nanometer titanium dioxide to optimize the ultraviolet resistance effect;Modification process is fine, and parameters are controlled in stages to ensure that the raw materials are fully modified;Preparation step is standard, and each link from pretreatment to filtration is strictly controlled to ensure stable product quality, wide applicability, and is beneficial to industrial production.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a flexible fluorocarbon paint and its preparation method. Background Technology

[0002] Fluorocarbon paints, due to the high bond energy of their fluorine-containing groups, possess excellent weather resistance, corrosion resistance, and chemical stability, making them widely used in outdoor and high-requirement protection fields such as building exteriors, bridges, and machinery. However, traditional fluorocarbon paints have significant technical drawbacks: on the one hand, the rigidity of fluorocarbon resin molecular chains leads to insufficient coating flexibility, making them prone to cracking and peeling under thermal expansion and contraction, vibration, or external impact on the substrate. This is especially true when applied to low-temperature environments or flexible substrates such as color steel plates and composite materials, significantly shortening the protective lifespan. On the other hand, pigments in conventional fluorocarbon paints, such as titanium dioxide, have poor dispersibility and are prone to agglomeration, which not only affects the uniformity and gloss of the coating appearance but also reduces its UV shielding efficiency. Long-term outdoor use can easily lead to chalking and fading, requiring frequent maintenance.

[0003] Meanwhile, existing fluorocarbon paint preparation processes have room for optimization: some formulations use a single resin system, making it difficult to balance weather resistance and flexibility; pigment modification is often a single step, resulting in insufficient interfacial compatibility and easy delamination with the resin matrix; parameter control during preparation is often crude, such as the lack of precise standardization of grinding fineness and stirring rate, leading to poor batch stability and significant fluctuations in the pass rate during industrial production. Furthermore, traditional organic bentonite anti-settling agents are added directly without pretreatment, easily causing clumping during paint storage, leading to pigment sedimentation and affecting application performance and coating quality. These problems limit the further application of fluorocarbon paints in high-end protective applications, necessitating the development of a flexible fluorocarbon paint with scientifically proportioned raw materials, advanced modification processes, and standardized preparation procedures to address the aforementioned issues of insufficient flexibility, poor weather resistance and dispersibility, and poor production stability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a flexible fluorocarbon paint and its preparation method, solving the problems of insufficient flexibility, poor dispersibility, and poor stability of traditional fluorocarbon paints.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A flexible fluorocarbon paint comprises the following raw materials in parts by weight: 40-55 parts modified fluorocarbon resin, 15-25 parts hydroxyl acrylic resin, 5-10 parts modified nano titanium dioxide, 3-8 parts barium sulfate, 2-6 parts talc, 0.5-1.5 parts polyacrylate, 0.3-1 part polydimethylsiloxane, 0.2-0.8 parts acrylate leveling agent, 2-5 parts epoxidized soybean oil, 8-15 parts toluene diisocyanate, 10-20 parts xylene and butyl acetate mixture, 0.5-1.2 parts silane coupling agent KH-550, and 0.3-0.8 parts organobentonite.

[0007] Furthermore, in the xylene and butyl acetate mixture, the mass ratio of xylene to butyl acetate is 1:1. This not only fully dissolves film-forming substances such as modified fluorocarbon resin and hydroxyl acrylic resin, but also matches the coating drying process, avoiding pinholes in the coating due to excessively rapid solvent evaporation or sagging due to excessively slow evaporation. This ensures that the coating forms a smooth and flat surface after drying, while maintaining the stability of the coating system and reducing the risk of delamination.

[0008] Furthermore, the organic bentonite requires pretreatment. The pretreatment steps are as follows: add the organic bentonite to xylene, stir at 600 rpm for 15 minutes, then add ethanol, and continue stirring for 5 minutes until a uniform paste is formed. Let it stand for 30 minutes before use. The mass ratio of organic bentonite, xylene, and ethanol is 1:8-10:0.5-0.8. The addition of ethanol can break the agglomeration structure of the organic bentonite, promote the formation of a uniform paste, and allow it to stand for 30 minutes to further stabilize the dispersion state, avoiding clumping when added directly. This mass ratio ensures sufficient pretreatment, allowing the organic bentonite to quickly form a three-dimensional network structure after being added to the coating, efficiently encapsulating pigment particles, preventing pigment sedimentation during storage, extending the shelf life of the coating, and without affecting the fluidity of the coating during application.

[0009] Furthermore, the modified fluorocarbon resin is prepared using the following specific steps:

[0010] A1. Add vinylidene fluoride-hexafluoropropylene copolymer and methyl isobutyl ketone to a four-necked flask, stir at 300-400 rpm and heat to 85-95°C, keep warm and stir for 1.5-2 hours until completely dissolved to form a transparent and homogeneous solution; dissolve 50% hydroxyl acrylic resin in methyl isobutyl ketone, and slowly add it dropwise to the four-necked flask at 1-2 mL / min. Slowly adding the hydroxyl acrylic resin can avoid excessive local concentration and prevent phase separation during blending. Maintain the temperature at 85-95°C and stir at 300-400 rpm. After the addition is complete, continue to keep warm and stir for 3-4 hours. Take 10 mL of sample every hour, cool to room temperature and observe until the sample is a homogeneous and transparent liquid. Then turn off the heating and let it cool naturally to 40-50°C. Vacuum filter with a 0.22 μm pore size filter to ensure the purity of the blended resin, lay a stable foundation for subsequent modification, and improve the weather resistance and flexibility compatibility of the final coating to obtain a fluorocarbon / acrylic blended resin.

[0011] A2. Add fluorocarbon / acrylic blend resin and butyl acetate to the reactor, stir at 250-300 r / min and heat to 110-120℃, maintain the temperature and stir for 30 min; slowly add caprolactone and stannous octoate to the reactor after they are evenly mixed, and continue to keep the temperature and react for 5-6 h. During this period, take a sample every 1 h and test the hydroxyl value of the resin by acetylation method. When the hydroxyl value reaches the target range of 30-40 mgKOH / g, turn off the heating and let it cool naturally to room temperature to obtain hydroxyl-containing fluorocarbon resin; caprolactone introduces flexible segments, stannous octoate catalyzes its reaction with the resin, slow addition avoids violent reaction, and keeping the temperature for 5-6 h ensures sufficient reaction. The hydroxyl value is controlled at 30-40 mgKOH / g, which provides sufficient reaction sites for subsequent crosslinking and avoids excessive hydroxyl groups that cause the coating to be too brittle, thereby improving the resin's flexibility and crosslinking potential;

[0012] A3. Add hydroxyl-containing fluorocarbon resin and propylene glycol methyl ether to a four-necked flask, stir at 200-250 r / min and heat to 100-110℃, keep stirring at this temperature for 30 min to fully dissolve the resin and reach the reaction activation temperature; add glycidyl ether and continue to keep the reaction at this temperature for 4-5 h. During the reaction, use a rotational viscometer to check the viscosity of the system at 25℃ every 15 min. When the viscosity at 25℃ reaches 2000-3000 mPa·s, turn off the heating and cool down to 40-50℃. Add xylene to adjust the viscosity to 1500-2000 mPa·s, filter with a 0.45 μm pore size filter to obtain the modified fluorocarbon resin. Glycidyl ether is crosslinked with hydroxyl groups, and a moderately crosslinked network is constructed through a heat-insulating reaction. The viscosity is adjusted to 1500-2000 mPa·s to ensure both the density and weather resistance of the resin film after formation, while also meeting the viscosity requirements for subsequent coating preparation. Crosslinking byproducts are removed by filtration to ensure the stable quality of the modified fluorocarbon resin.

[0013] Furthermore, in A1, 350-400g of vinylidene fluoride-hexafluoropropylene copolymer is dissolved in 120-150mL of methyl isobutyl ketone; and 40-50g of hydroxyl acrylic resin is dissolved in 80-100mL of methyl isobutyl ketone.

[0014] Furthermore, the ratio of fluorocarbon / acrylic blend resin, butyl acetate, caprolactone, and stannous octoate in A2 is 300-350g: 80-100mL: 10-15g: 0.5-1.0g.

[0015] Furthermore, the ratio of hydroxyl fluorocarbon resin, propylene glycol methyl ether, glycidyl ether, and xylene in A3 is 250-300g: 60-80mL: 12-18g: 10-15mL.

[0016] Furthermore, the modified nano-titanium dioxide is prepared using the following specific steps:

[0017] B1. Add rutile nano-titanium dioxide and deionized water to a beaker, and ultrasonically disperse for 300-500W for 30-40 minutes to form a uniform suspension. Adjust the pH to 9-10 with 1mol / L sodium hydroxide solution. Slowly add sodium dodecylbenzenesulfonate while stirring at 800-1000r / min, and stir at room temperature for 2-3 hours to allow sodium dodecylbenzenesulfonate to be uniformly adsorbed onto the particle surface, forming a charge layer to prevent re-agglomeration. Then, increase the pressure of the suspension at 3000-4000... Centrifuge at r / min to separate and collect the bottom solid particles. Wash the solid particles with deionized water until the surface tension difference between the washing liquid and pure deionized water at the same temperature is ≤1mN / m. Then dry in an oven at 80-100℃ for 4-5 hours. After taking it out, grind it into powder with a high-speed pulverizer at 10000-12000r / min to improve the compatibility of nano titanium dioxide in coatings and lay the foundation for subsequent optimization of UV shielding performance. The first modified nano titanium dioxide was obtained.

[0018] B2. Add the first-modified nano-titanium dioxide and a 1:1 volume ratio ethanol-water solution to a beaker, and ultrasonically disperse at 300W for 20-30 minutes to form a uniform suspension. Heat to 55-65℃ and stir at 600-800 r / min. Dissolve ammonium dihydrogen phosphate in deionized water to form a transparent solution, and slowly add it dropwise to the above suspension. After the addition is complete, keep the mixture warm and stir for 3-4 hours. After the reaction is complete, filter and collect the solid particles, wash them three times with ethanol, and dry the solid in an oven at 90-110℃ for 3-4 hours to obtain the second-modified nano-titanium dioxide. Slow dropwise addition avoids uneven local reaction, and keeping the mixture warm for 3-4 hours allows the phosphate groups to firmly bind to the particle surface. Washing with ethanol and drying at 90-110℃ removes residual impurities, introduces phosphate functional groups, enhances the interfacial bonding with the resin matrix, and improves the overall density of the coating.

[0019] B3. Add zinc nitrate and deionized water to a beaker, stir until completely dissolved, then add citric acid and continue stirring for 10-15 minutes to form a stable zinc ion complex solution. Add the second batch of modified nano-titanium dioxide to another beaker, along with the above zinc ion complex solution. Disperse the mixture using ultrasonication at 300W for 15-20 minutes to form a uniform suspension. Heat to 60-70℃ and stir at 500-600 r / min, slowly evaporating the water until the system becomes a paste to obtain the precursor. Place the precursor in a forced-air drying oven at 120-140℃ for 4-5 hours, then transfer it to a muffle furnace and calcine at 350-400℃ at a rate of 5℃ / min for 2-3 hours. After calcination, remove the product and grind it into powder with a particle size ≤10μm using a high-speed pulverizer to obtain modified nano-titanium dioxide. Slow heating at 5℃ / min and calcination at 350-400℃ ensure that zinc ions are converted into zinc oxide and uniformly coated on the particle surface, forming a "titanium dioxide-zinc oxide" synergistic system.

[0020] Furthermore, the ratio of rutile nano-titanium dioxide, deionized water, and sodium dodecylbenzenesulfonate in B1 is 80-100g: 500-600mL: 15-20g.

[0021] Furthermore, the ratio of the first modified nano-titanium dioxide, ethanol aqueous solution, ammonium dihydrogen phosphate, and deionized water in B2 is 60-80g: 300-400mL: 8-12g: 50-60mL.

[0022] Furthermore, the ratio of zinc nitrate, deionized water, citric acid, and second-modified nano-titanium dioxide in B3 is 5-8g: 100-120mL: 2-3g: 50-70g.

[0023] Furthermore, during ultrasonic dispersion in B1, an intermittent ultrasonic mode is adopted, i.e., ultrasonic operation for 3 minutes, followed by a 1-minute pause, repeated until the total dispersion time reaches 30-40 minutes. The intermittent ultrasonic mode avoids the localized high temperatures generated by continuous ultrasonication, preventing damage to the nano-titanium dioxide particle structure, while ensuring dispersion efficiency, guaranteeing sufficient particle dispersion and uniform particle size, and preventing particle agglomeration and recurrence due to high temperatures. This provides a high-quality initial dispersion system for subsequent modification steps, ultimately improving the coating's appearance uniformity and UV resistance.

[0024] A method for preparing a flexible fluorocarbon paint specifically includes the following steps:

[0025] S1. Place the modified nano-titanium dioxide, barium sulfate, and talc powder separately into a forced-air drying oven and dry at 100-120℃ for 2-3 hours to prevent moisture from causing bubbling during coating storage or affecting film quality. After drying, mix them and add them to an air jet mill with an inlet pressure of 0.6-0.8MPa and a classifier wheel speed of 20000r / min. Grind for 15-20 minutes, controlling the particle size of the pigment powder to 1-5μm to ensure uniform pigment particle size and good dispersibility. This avoids rough coating due to excessively large particles or agglomeration due to excessively small particles, laying the foundation for uniform mixing of the coating in the subsequent process.

[0026] S2. Add the xylene and butyl acetate mixture to the dispersion vessel, and add polyacrylate and organobentonite sequentially while stirring at 800-1000 r / min. Stir for 15-20 min until completely dissolved. Slowly add the pigment powder mixture from S1 while stirring. After the addition is complete, increase the speed to 1500-2000 r / min and disperse at high speed for 30-40 min to form a uniform pigment slurry. Filter with a 40-mesh filter to remove any obvious particles.

[0027] S3. Transfer the pigment paste to a horizontal sand mill. The grinding media is zirconium beads with a particle size of 1.0-1.2 mm and a filling rate of 70-75%. Ensure grinding efficiency and avoid over-grinding to prevent zirconium bead wear and contamination of the coating. Add modified fluorocarbon resin and hydroxyl acrylic resin. Grind at a sand mill speed of 1500-1800 r / min for 2-3 hours. During this period, take samples every 30 minutes and test them with a scraper fineness gauge. Control the temperature ≤40℃ until the fineness is ≤15μm and then stop grinding.

[0028] S4. Transfer the properly ground coating to a mixing tank. While stirring at 600-800 rpm, add epoxidized soybean oil, silane coupling agent KH-550, acrylate leveling agent, and polydimethylsiloxane in sequence. Stir for 5-10 minutes after each addition to ensure uniform dispersion and avoid excessive local concentrations that could affect coating performance. Finally, slowly add toluene diisocyanate and stir for 15-20 minutes. Measure the viscosity using a Ford cup at 25°C for 20-30 seconds. If the viscosity is too high, add an appropriate amount of solvent to adjust it. Stir for 5 minutes and measure again to ensure viscosity stability. Filter the coating through a 100-200 mesh nylon filter to obtain flexible fluorocarbon paint.

[0029] This invention provides a flexible fluorocarbon paint and its preparation method, which has the following beneficial effects:

[0030] 1. This invention constructs a composite resin structure of "rigid fluorocarbon segments - flexible acrylic segments - moderately cross-linked network" through multi-step modification and synergistic formulation design of fluorocarbon resin. Simultaneously, it incorporates an epoxidized soybean oil toughening agent, significantly improving the flexibility of the coating while retaining the excellent UV and chemical corrosion resistance of the fluorocarbon groups. The modified coating can withstand significant thermal expansion and contraction and slight vibration of the substrate, and is less prone to breakage due to stress concentration during stretching, effectively solving the cracking and peeling problems caused by excessively rigid molecular chains in traditional fluorocarbon paints. Furthermore, the composite structure slows down the degradation rate of the resin molecular chains by ultraviolet light, maintaining good appearance and protective performance even after long-term outdoor use, significantly extending the coating's service life and broadening the application range of fluorocarbon paints in flexible substrates and complex outdoor conditions.

[0031] 2. This invention addresses coating defects caused by poor pigment dispersion. Through a three-step modification process of nano-titanium dioxide, a charge layer, compatible functional groups, and a zinc oxide composite layer are formed on its surface. This not only completely solves the problem of nanoparticle agglomeration, ensuring uniform dispersion in the coating system, but also constructs a synergistic UV shielding system of "rutile nano-titanium dioxide-zinc oxide". The uniformly dispersed pigment results in a smooth and even coating surface, free from rough spots caused by particle agglomeration, and significantly improved gloss. The synergistic UV shielding system efficiently absorbs and reflects ultraviolet rays of different wavelengths, reducing UV damage to the internal structure of the coating and delaying chalking and fading. Simultaneously, the zinc oxide composite layer isolates moisture and oxygen, reducing the risk of corrosive media penetration, ensuring good color stability and structural integrity of the coating during long-term use. This balances decorative appeal and durability, enhancing the product's application value in fields with high requirements for appearance and performance, such as building exteriors and high-end equipment.

[0032] 3. This invention significantly improves the storage and application performance of coatings by addressing both raw material pretreatment and preparation processes. Firstly, the organic bentonite is pretreated with a specific ratio of xylene-ethanol to form a uniform paste. Upon addition to the coating, this paste rapidly constructs a three-dimensional network structure, efficiently encapsulating pigment particles and preventing pigment sedimentation and stratification during storage. Even with long-term storage, the coating maintains a uniform state, extending its shelf life. Secondly, airflow milling controls the uniformity of the pigment powder particle size, followed by precise grinding to a fineness ≤15μm using a horizontal sand mill. This, combined with polyacrylate dispersants and acrylate leveling agents, ensures a stable colloidal dispersion in the coating system. During application, the coating exhibits excellent leveling properties, minimizing defects such as sagging, pinholes, and orange peel. Furthermore, the consistency of key indicators such as viscosity and fineness across different batches is high, reducing quality fluctuations in industrial production and ensuring stable and controllable coating performance after application. This reduces operational difficulty and quality risks for the application team.

[0033] 4. This invention constructs a strong interfacial bonding system of "modified fluorocarbon resin - modified nano-titanium dioxide - toluene diisocyanate" through multi-component synergistic design. The hydroxyl functional groups introduced into the modified fluorocarbon resin can undergo cross-linking reactions with the NCO groups of toluene diisocyanate to form a dense polyurethane cross-linking network. At the same time, the polar groups on the resin molecular chain form hydrogen bonds or coordination bonds with the phosphate and hydroxyl functional groups on the surface of the modified nano-titanium dioxide, so that the pigment particles are firmly bound in the resin cross-linking network. In addition, the addition of silane coupling agent KH-550 further builds a chemical bridge between the resin, pigment, and substrate. Through the reaction of its amino groups with the resin hydroxyl groups and the functional groups on the pigment surface, as well as the combination of alkoxy groups after hydrolysis with the hydroxyl groups on the substrate surface, the adhesion between the coating and the substrate is enhanced. This multi-layered, high-strength interface bonding structure not only enhances the hardness and wear resistance of the coating, but also effectively prevents corrosive media such as moisture and salt from penetrating to the substrate surface, thus avoiding substrate corrosion. At the same time, it reduces stress concentration inside the coating, allowing the coating to maintain structural integrity during long-term use and fully exert its dual functions of protection and decoration. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1: Preparation of flexible fluorocarbon paint. The specific preparation steps are as follows:

[0036] S1. Place 5 parts of nano titanium dioxide, 3 parts of barium sulfate and 2 parts of talc powder into a forced-air drying oven and dry at 100℃ for 2 hours. After drying, mix them and add them to an air jet mill with an inlet pressure of 0.6MPa and a classifier wheel speed of 20000r / min. Grind for 15 minutes and control the particle size of the pigment mixed powder to be 1-5μm.

[0037] S2. Add 10 parts of xylene and butyl acetate mixture to the dispersion vessel. While stirring at 800 r / min, add 0.5 parts of polyacrylate and 0.3 parts of organobentonite in sequence, and stir for 15 min until completely dissolved. Slowly add the pigment powder mixture from S1 while stirring. After the addition is complete, increase the speed to 1500 r / min and disperse at high speed for 30 min to form a uniform pigment slurry. Filter with a 40 mesh filter and no obvious particles are found.

[0038] S3. Transfer the pigment paste to a horizontal sand mill. The grinding media is zirconium beads with a particle size of 1.0 mm and a filling rate of 70%. Add 40 parts of fluorocarbon resin and 15 parts of hydroxyl acrylic resin. Grind at 1500 r / min for 2 hours. During the grinding process, take a sample every 30 minutes and test it with a scraper fineness gauge. Control the temperature to ≤40℃ until the fineness is ≤15μm and then stop grinding.

[0039] S4. Transfer the properly ground coating to a mixing tank. While stirring at 600 rpm, add 2 parts of epoxidized soybean oil, 0.5 parts of silane coupling agent KH-550, 0.2 parts of acrylate leveling agent, and 0.3 parts of polydimethylsiloxane in sequence. Stir for 5 minutes after each addition. Finally, slowly add 8 parts of toluene diisocyanate and stir for 15 minutes. Measure the viscosity for 20 seconds using a Ford cup at 25°C. If the viscosity is too high, add an appropriate amount of solvent to adjust it. Stir for 5 minutes and measure again to ensure the viscosity is stable. Filter the coating through a 100-mesh nylon filter to obtain flexible fluorocarbon paint.

[0040] Example 2: Preparation of flexible fluorocarbon paint. The specific preparation steps are as follows:

[0041] S1. Place 10 parts of nano titanium dioxide, 8 parts of barium sulfate and 6 parts of talc powder into a forced-air drying oven and dry at 120℃ for 3 hours. After drying, mix them and add them to an air jet mill with an inlet pressure of 0.8MPa and a classifier wheel speed of 20000r / min. Grind for 20 minutes and control the particle size of the pigment mixed powder to be 1-5μm.

[0042] S2. Add 20 parts of xylene and butyl acetate mixture to the dispersion vessel. While stirring at 1000 r / min, add 1.5 parts of polyacrylate and 0.8 parts of organobentonite in sequence, and stir for 20 min until completely dissolved. Slowly add the pigment powder mixture from S1 while stirring. After the addition is complete, increase the speed to 2000 r / min and disperse at high speed for 40 min to form a uniform pigment slurry. Filter with a 40 mesh filter and no obvious particles are found.

[0043] S3. Transfer the pigment slurry to a horizontal sand mill. The grinding media is zirconium beads with a particle size of 1.2 mm and a filling rate of 75%. Add 55 parts of fluorocarbon resin and 25 parts of hydroxyl acrylic resin. Grind at 1800 r / min for 3 hours. During the grinding process, take a sample every 30 minutes and test it with a scraper fineness gauge. Control the temperature to ≤40℃ until the fineness is ≤15μm and then stop grinding.

[0044] S4. Transfer the properly ground coating to a mixing tank. While stirring at 800 rpm, add 5 parts of epoxidized soybean oil, 1.2 parts of silane coupling agent KH-550, 0.8 parts of acrylate leveling agent, and 1 part of polydimethylsiloxane in sequence. Stir for 5-10 minutes after each additive is added. Finally, slowly add 15 parts of toluene diisocyanate and stir for 20 minutes. Measure the viscosity for 30 seconds using a Ford cup at 25°C. If the viscosity is too high, add an appropriate amount of solvent to adjust it. Stir for 5 minutes and measure again to ensure the viscosity is stable. Filter the coating through a 200-mesh nylon filter to obtain flexible fluorocarbon paint.

[0045] Example 3: Preparation of flexible fluorocarbon paint. The specific preparation steps are as follows:

[0046] S1. Place 7 parts of nano titanium dioxide, 5 parts of barium sulfate and 4 parts of talc powder into a forced-air drying oven and dry at 110℃ for 2.5h. After drying, mix them and add them to an air jet mill with an inlet pressure of 0.7MPa and a classifier wheel speed of 20000r / min. Grind for 18min and control the particle size of the pigment mixed powder to be 1-5μm.

[0047] S2. Add 15 parts of xylene and butyl acetate mixture to the dispersion vessel. While stirring at 900 r / min, add 1 part of polyacrylate and 0.5 parts of organobentonite in sequence, and stir for 18 min until completely dissolved. Slowly add the pigment powder mixture from S1 while stirring. After the addition is complete, increase the speed to 1750 r / min and disperse at high speed for 35 min to form a uniform pigment slurry. Filter with a 40 mesh filter and no obvious particles are found.

[0048] S3. Transfer the pigment slurry to a horizontal sand mill. The grinding media is zirconium beads with a particle size of 1.1 mm and a filling rate of 73%. Add 48 parts of fluorocarbon resin and 20 parts of hydroxyl acrylic resin. Grind at 1750 r / min for 2.5 h. During the grinding process, take a sample every 30 min and test it with a scraper fineness gauge. Control the temperature to ≤40℃ until the fineness is ≤15μm and then stop grinding.

[0049] S4. Transfer the properly ground coating to a mixing tank. While stirring at 700 rpm, add 3 parts of epoxidized soybean oil, 0.8 parts of silane coupling agent KH-550, 0.5 parts of acrylate leveling agent, and 0.6 parts of polydimethylsiloxane in sequence. Stir for 7 minutes after each addition. Finally, slowly add 12 parts of toluene diisocyanate and stir for 17 minutes. Measure the viscosity for 25 seconds using a Ford cup at 25°C. If the viscosity is too high, add an appropriate amount of solvent to adjust it. Stir for 5 minutes and measure again to ensure the viscosity is stable. Filter the coating through a 150-mesh nylon filter to obtain flexible fluorocarbon paint.

[0050] Example 4: Preparation of modified fluorocarbon resin. The specific preparation steps are as follows:

[0051] A1. Add 350g of vinylidene fluoride-hexafluoropropylene copolymer and 120mL of methyl isobutyl ketone to a four-necked flask. Stir at 300r / min and heat to 85℃. Keep stirring for 1.5h until completely dissolved to form a transparent and homogeneous solution. Dissolve 40g of 50% hydroxyl acrylic resin in 80mL of methyl isobutyl ketone and slowly add it dropwise to the four-necked flask at 1mL / min. Maintain the temperature at 85℃ and stir at 300r / min. After the addition is complete, continue stirring for 3h. Take 10mL of sample every 1h and cool to room temperature for observation until the sample is a homogeneous and transparent liquid. Then turn off the heating and let it cool naturally to 40℃. Vacuum filter with a 0.22μm pore size filter to obtain fluorocarbon / acrylic blend resin.

[0052] A2. Add 300g of fluorocarbon / acrylic blend resin and 80mL of butyl acetate to the reactor, stir at 250r / min and heat to 110℃, and keep stirring for 30min; slowly add 10g of caprolactone and 0.5g of stannous octoate to the reactor after they are evenly mixed. After the addition is complete, continue to keep the reaction at the temperature for 5h. During this period, take a sample every 1h and use the acetylation method to detect the hydroxyl value of the resin. When the hydroxyl value reaches the target range of 30mgKOH / g, turn off the heating and let it cool naturally to room temperature to obtain hydroxyl-containing fluorocarbon resin.

[0053] A3. Add 250g of hydroxyl-containing fluorocarbon resin and 60mL of propylene glycol methyl ether to a four-necked flask. Stir at 200r / min and heat to 100℃. Maintain the temperature and stir for 30min to fully dissolve the resin and reach the reaction activation temperature. Add 12g of glycidyl ether and continue to react for 4h. During the reaction, use a rotational viscometer to check the viscosity of the system at 25℃ every 15min. When the viscosity at 25℃ reaches 2000mPa·s, turn off the heating and cool down to 40℃. Add 10mL of xylene to adjust the viscosity to 1500mPa·s. Filter with a 0.45μm pore size filter to obtain the modified fluorocarbon resin.

[0054] Example 5: Preparation of modified fluorocarbon resin. The specific preparation steps are as follows:

[0055] A1. Add 400g of vinylidene fluoride-hexafluoropropylene copolymer and 150mL of methyl isobutyl ketone to a four-necked flask. Stir at 400r / min and heat to 95℃. Keep stirring at this temperature for 2h until completely dissolved to form a transparent and homogeneous solution. Dissolve 50g of hydroxyl acrylic resin with a solid content of 50% in 100mL of methyl isobutyl ketone. Slowly add the solution dropwise to the four-necked flask at 2mL / min, maintaining the temperature at 95℃ and stirring at 400r / min. After the addition is complete, continue stirring at this temperature for 4h. Take 10mL of sample every 1h and cool to room temperature for observation until the sample is a homogeneous and transparent liquid. Then turn off the heating and allow it to cool naturally to 50℃. Vacuum filter using a 0.22μm pore size filter to obtain a fluorocarbon / acrylic blend resin.

[0056] A2. Add 350g of fluorocarbon / acrylic blend resin and 100mL of butyl acetate to the reactor, stir at 300r / min and heat to 120℃, and keep stirring for 30min; slowly add 15g of caprolactone and 1.0g of stannous octoate to the reactor after they are evenly mixed. After the addition is complete, continue to keep the reaction at the temperature for 6h. During this period, take a sample every 1h and use the acetylation method to detect the hydroxyl value of the resin. When the hydroxyl value reaches the target range of 40mgKOH / g, turn off the heating and let it cool naturally to room temperature to obtain hydroxyl-containing fluorocarbon resin.

[0057] A3. Add 300g of hydroxyl-containing fluorocarbon resin and 80mL of propylene glycol methyl ether to a four-necked flask. Stir at 250r / min and heat to 110℃. Maintain the temperature and stir for 30min to fully dissolve the resin and reach the reaction activation temperature. Add 18g of glycidyl ether and continue to react for 5h. During the reaction, measure the viscosity of the system every 15min at 25℃ using a rotational viscometer. When the viscosity reaches 3000mPa·s at 25℃, turn off the heating and cool to 50℃. Add 15mL of xylene to adjust the viscosity to 2000mPa·s. Filter with a 0.45μm pore size filter to obtain the modified fluorocarbon resin.

[0058] Example 6: Preparation of modified nano-titanium dioxide. The specific preparation steps are as follows:

[0059] B1. Add 80g of rutile nano-titanium dioxide and 500mL of deionized water to a beaker. Disperse the mixture by ultrasonication at 300W for 30min, using an intermittent ultrasonication pattern of 3min operation followed by 1min pause to form a uniform suspension. Adjust the pH to 9 with 1mol / L sodium hydroxide solution. Slowly add 15g of sodium dodecylbenzenesulfonate while stirring at 800r / min. Stir and react at room temperature for 2h. Then, centrifuge the suspension at 3000r / min, collect the bottom solid particles, and wash the solid particles with deionized water until the surface tension difference between the washing liquid and pure deionized water at the same temperature is ≤1mN / m at 25℃. Then, dry the mixture in an oven at 80℃ for 4h. After drying, grind the mixture into powder using a high-speed pulverizer at 10000r / min to obtain the first modified nano-titanium dioxide.

[0060] B2. Add 60g of the first-modified nano-titanium dioxide and 300mL of ethanol-water solution with a volume ratio of 1:1 to a beaker. Disperse the solution by ultrasonication at 300W for 20min to form a uniform suspension. Heat the solution to 55℃ and stir at 600r / min. Dissolve 8g of ammonium dihydrogen phosphate in 50mL of deionized water to form a transparent solution. Slowly add the solution dropwise to the above suspension. After the addition is complete, keep the solution warm and stir for 3h. After the reaction is complete, filter and collect the solid particles. Wash the solid three times with ethanol. Place the solid in an oven at 90℃ and dry for 3h to obtain the second-modified nano-titanium dioxide.

[0061] B3. Add 5g of zinc nitrate and 100mL of deionized water to a beaker, stir until completely dissolved, then add 2g of citric acid and continue stirring for 10min to form a stable zinc ion complex solution. Add 50g of the second modified nano-titanium dioxide to another beaker, add the above zinc ion complex solution, and ultrasonically disperse at 300W for 15min to form a uniform suspension. Heat to 60℃ and stir at 500r / min, slowly evaporate the water until the system becomes a paste to obtain the precursor. Place the precursor in a forced-air drying oven at 120℃ for 4h, then transfer it to a muffle furnace and calcine at 350℃ for 2h at a rate of 5℃ / min. After calcination, remove the product and grind it into powder with a particle size ≤10μm using a high-speed pulverizer to obtain modified nano-titanium dioxide.

[0062] Example 7: Preparation of modified nano-titanium dioxide. The specific preparation steps are as follows:

[0063] B1. Add 100g of rutile nano-titanium dioxide and 600mL of deionized water to a beaker. Disperse the mixture by ultrasonication at 500W for 40min, using an intermittent ultrasonication pattern of 3min operation followed by 1min pause to form a uniform suspension. Adjust the pH to 10 with 1mol / L sodium hydroxide solution. Slowly add 20g of sodium dodecylbenzenesulfonate while stirring at 1000r / min. Stir and react at room temperature for 3h. Then, centrifuge the suspension at 4000r / min, collect the bottom solid particles, and wash the solid particles with deionized water until the surface tension difference between the washing liquid and pure deionized water at the same temperature is ≤1mN / m at 25℃. Then, dry the mixture in an oven at 100℃ for 5h. After drying, grind the mixture into powder using a high-speed pulverizer at 12000r / min to obtain the first modified nano-titanium dioxide.

[0064] B2. Add 80g of the first-modified nano-titanium dioxide and 400mL of ethanol-water solution with a volume ratio of 1:1 to a beaker. Disperse the solution by ultrasonication at 300W for 30min to form a uniform suspension. Heat the solution to 65℃ and stir at 800r / min. Dissolve 12g of ammonium dihydrogen phosphate in 60mL of deionized water to form a transparent solution. Slowly add the solution dropwise to the above suspension. After the addition is complete, keep the solution warm and stir for 4h. After the reaction is complete, filter and collect the solid particles. Wash the solid three times with ethanol. Place the solid in an oven at 110℃ and dry for 4h to obtain the second-modified nano-titanium dioxide.

[0065] B3. Add 8g of zinc nitrate and 120mL of deionized water to a beaker, stir until completely dissolved, then add 3g of citric acid and continue stirring for 15min to form a stable zinc ion complex solution. Add 70g of the second modified nano-titanium dioxide to another beaker, add the above zinc ion complex solution, and ultrasonically disperse at 300W for 20min to form a uniform suspension. Heat to 70℃ and stir at 600r / min, slowly evaporate the water until the system becomes a paste to obtain the precursor. Place the precursor in a forced-air drying oven at 140℃ for 5h, then transfer it to a muffle furnace and calcine at 400℃ for 3h at a rate of 5℃ / min. After calcination, remove the product and grind it into powder with a particle size ≤10μm using a high-speed pulverizer to obtain modified nano-titanium dioxide.

[0066] Comparative Example 1: A flexible fluorocarbon paint was prepared. The specific preparation steps are as follows:

[0067] The remaining steps remain unchanged, except that the fluorocarbon resin in Example 3 is replaced with the modified fluorocarbon resin prepared in Example 4 to prepare a flexible fluorocarbon paint.

[0068] Comparative Example 2: A flexible fluorocarbon paint was prepared. The specific preparation steps are as follows:

[0069] The remaining steps remain unchanged, except that the nano-titanium dioxide in Example 3 is replaced with the modified nano-titanium dioxide prepared in Example 7 to prepare flexible fluorocarbon paint.

[0070] Comparative Example 3: A flexible fluorocarbon paint was prepared. The specific preparation steps are as follows:

[0071] The remaining steps remain unchanged, except that the fluorocarbon resin in Example 3 is replaced with the modified fluorocarbon resin prepared in Example 4, and the nano-titanium dioxide is replaced with the modified nano-titanium dioxide prepared in Example 7, to prepare a flexible fluorocarbon paint.

[0072] Performance testing

[0073] Test Project Test Standards Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Flexibility (diameter of cylindrical shaft) GB / T1731-2020 ≤3mm, no cracks when bent ≤3mm, no cracks when bent ≤2mm, no cracks when bent ≤1mm, no cracks when bent ≤1mm, no cracks when bent ≤1mm, no cracks when bent Adhesion (cross-cut test, grade) GB / T9286-2021 2 2 1 1 1 0 Weather resistance (1000h xenon lamp aging) GB / T1865-2009 Gloss loss rate ≤35%, no obvious chalking or fading Gloss loss rate ≤30%, no chalking or fading Gloss loss rate ≤25%, no chalking or fading Gloss loss rate ≤18%, no chalking or fading Gloss loss rate ≤15%, no chalking or fading Gloss loss rate ≤8%, no chalking or fading Corrosion resistance (immersion in 5% NaCl solution for 500 hours) GB / T1771-2007 The coating surface is free of rust, with a few bubbles appearing at the edges, and the adhesion remains at level 2. The coating surface is free of rust and bubbles, and the adhesion remains at level 2. The coating surface is intact, free of rust and bubbles, and the adhesion remains at level 1. The coating surface is intact, free of rust and bubbles, and the adhesion remains at level 1. The coating surface is intact, free of rust and bubbles, and the adhesion remains at level 1. The coating surface is intact, free of rust and bubbles, and the adhesion remains unchanged. Gloss (60°, %) GB / T9754-2025 ≥75 ≥78 ≥82 ≥85 ≥88 ≥90

[0074] According to the performance test results, in terms of flexibility, Examples 1-2 had a bending cylindrical shaft diameter ≤3mm and no cracks, Example 3 had a bending cylindrical shaft diameter ≤2mm and no cracks, and Comparative Examples 1-3 all had bending cylindrical shaft diameters ≤1mm and no cracks, indicating that the comparative examples showed better flexibility. Regarding adhesion, Examples 1-2 were at level 2, Example 3 was improved to level 1, Comparative Examples 1-2 were at level 1, and Comparative Example 3 was further optimized to level 0. In terms of weather resistance, Example 1 had a gloss loss rate ≤35% and no obvious chalking or fading, Example 2 had a gloss loss rate ≤30%, and Example 3 had a gloss loss rate ≤25% and no chalking or fading. The comparative examples... The gloss loss rates of Examples 1-3 decreased continuously, reaching ≤18%, ≤15%, and ≤8% respectively, with no chalking or fading. Regarding corrosion resistance, the coating in Example 1 showed no rust but had a small number of bubbles at the edges, and its adhesion remained at level 2. Example 2 showed no rust or bubbles, and its adhesion remained at level 2. The coatings in Examples 3 and Comparative Examples 1-3 were all intact without rust or bubbles. The adhesion of Example 3 and Comparative Examples 1-2 remained at level 1, while the adhesion of Comparative Example 3 remained unchanged. In terms of gloss, Examples 1-3 showed ≥75%, ≥78%, and ≥82% respectively, while Comparative Examples 1-3 gradually increased to ≥85%, ≥88%, and ≥90%. Overall, the comparative examples, especially Comparative Example 3, exhibited the best performance.

[0075] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A flexible fluorocarbon paint, characterized in that: It contains the following raw materials in parts by weight: 40-55 parts modified fluorocarbon resin, 15-25 parts hydroxyl acrylic resin, 5-10 parts modified nano titanium dioxide, 3-8 parts barium sulfate, 2-6 parts talc, 0.5-1.5 parts polyacrylate, 0.3-1 part polydimethylsiloxane, 0.2-0.8 parts acrylate leveling agent, 2-5 parts epoxidized soybean oil, 8-15 parts toluene diisocyanate, 10-20 parts xylene and butyl acetate mixture, 0.5-1.2 parts silane coupling agent KH-550, and 0.3-0.8 parts organobentonite; The modified fluorocarbon resin is prepared using the following specific steps: A1. Add vinylidene fluoride-hexafluoropropylene copolymer and methyl isobutyl ketone to a four-necked flask, stir at 300-400 rpm and heat to 85-95℃, keep warm and stir for 1.5-2 hours until completely dissolved to form a transparent and homogeneous solution; dissolve 50% hydroxyl acrylic resin in methyl isobutyl ketone, and slowly add it dropwise to the four-necked flask at 1-2 mL / min, maintaining 85-95℃ and stirring at 300-400 rpm. After the addition is complete, continue to keep warm and stir for 3-4 hours. Take 10 mL of sample every hour, cool to room temperature and observe until the sample is a homogeneous and transparent liquid. Then turn off the heating and let it cool naturally to 40-50℃. Vacuum filter with a 0.22 μm pore size filter to obtain fluorocarbon / acrylic blend resin; A2. Add fluorocarbon / acrylic blend resin and butyl acetate to the reactor, stir and heat to 110-120℃ at 250-300r / min, and keep stirring for 30min; slowly add caprolactone and stannous octoate to the reactor after they are evenly mixed, and continue to keep the reaction for 5-6h after the addition is complete. During the reaction, take a sample every 1h and test the hydroxyl value of the resin by acetylation method. When the hydroxyl value reaches the target range of 30-40mgKOH / g, turn off the heating and let it cool naturally to room temperature to obtain hydroxyl-containing fluorocarbon resin. A3. Add hydroxyl-containing fluorocarbon resin and propylene glycol methyl ether to a four-necked flask, stir at 200-250 r / min and heat to 100-110℃, keep warm and stir for 30 min to fully dissolve the resin and reach the reaction activity temperature; add glycidyl ether and continue to keep warm for 4-5 h. During the reaction, use a rotational viscometer to check the viscosity of the system at 25℃ every 15 min. When the viscosity at 25℃ reaches 2000-3000 mPa·s, turn off the heating and cool down to 40-50℃. Add 10-15 mL of xylene to adjust the viscosity to 1500-2000 mPa·s. Filter with a 0.45 μm pore size filter to obtain the modified fluorocarbon resin. The modified nano-titanium dioxide is prepared using the following specific steps: B1. Add rutile nano-titanium dioxide and deionized water to a beaker, and ultrasonically disperse for 300-500W for 30-40 minutes to form a uniform suspension. Adjust the pH value to 9-10 with 1mol / L sodium hydroxide solution. Slowly add sodium dodecylbenzenesulfonate while stirring at 800-1000r / min, and stir at room temperature for 2-3 hours. Then, centrifuge the suspension at 3000-4000r / min, collect the bottom solid particles, and wash the solid particles with deionized water until the surface tension difference between the washing liquid and pure deionized water at the same temperature is ≤1mN / m at 25℃. Then, dry in an oven at 80-100℃ for 4-5 hours. After taking it out, grind it into powder with a high-speed pulverizer at 10000-12000r / min to obtain the first modified nano-titanium dioxide. B2. Add the first-modified nano-titanium dioxide and an ethanol-water solution with a volume ratio of 1:1 to a beaker, and ultrasonically disperse the mixture at 300W for 20-30 minutes to form a uniform suspension. Heat the mixture to 55-65℃ and stir at 600-800r / min. Dissolve ammonium dihydrogen phosphate in deionized water to form a transparent solution, and slowly add it dropwise to the above suspension. After the addition is complete, keep the mixture warm and stir for 3-4 hours. After the reaction is complete, filter and collect the solid particles, wash them three times with ethanol, and dry the solid in an oven at 90-110℃ for 3-4 hours to obtain the second-modified nano-titanium dioxide. B3. Add zinc nitrate and deionized water to a beaker, stir until completely dissolved, then add citric acid and continue stirring for 10-15 min to form a stable zinc ion complex solution. Add the second modified nano-titanium dioxide to another beaker, add the above zinc ion complex solution, and ultrasonically disperse at 300W for 15-20 min to form a uniform suspension. Heat to 60-70℃ and stir at 500-600 r / min, slowly evaporate the water until the system becomes a paste to obtain the precursor. Place the precursor in a forced-air drying oven at 120-140℃ and dry for 4-5 h, then transfer it to a muffle furnace and calcine at 350-400℃ at a rate of 5℃ / min for 2-3 h. After calcination, remove the product and grind it into powder with a particle size ≤10μm using a high-speed pulverizer to obtain modified nano-titanium dioxide.

2. The flexible fluorocarbon paint according to claim 1, characterized in that: In the xylene and butyl acetate mixture, the mass ratio of xylene to butyl acetate is 1:

1.

3. The flexible fluorocarbon paint according to claim 1, characterized in that: The organic bentonite needs to be pretreated. The pretreatment steps are as follows: add organic bentonite to xylene, stir at 600 r / min for 15 min, then add ethanol, continue stirring for 5 min until a uniform paste is formed, and let stand for 30 min before use; wherein the mass ratio of organic bentonite, xylene and ethanol is 1:8-10:0.5-0.

8.

4. The flexible fluorocarbon paint according to claim 1, characterized in that: In A1, 350-400g of vinylidene fluoride-hexafluoropropylene copolymer is dissolved in 120-150mL of methyl isobutyl ketone; 40-50g of hydroxyl acrylic resin is dissolved in 80-100mL of methyl isobutyl ketone. The ratio of fluorocarbon / acrylic blend resin, butyl acetate, caprolactone, and stannous octoate in A2 is 300-350g: 80-100mL: 10-15g: 0.5-1.0g. The ratio of hydroxyl fluorocarbon resin, propylene glycol methyl ether, glycidyl ether, and xylene in A3 is 250-300g: 60-80mL: 12-18g: 10-15mL.

5. The flexible fluorocarbon paint according to claim 1, characterized in that: The ratio of rutile nano-titanium dioxide, deionized water, and sodium dodecylbenzenesulfonate in B1 is 80-100g: 500-600mL: 15-20g. The ratio of the first modified nano-titanium dioxide, ethanol aqueous solution, ammonium dihydrogen phosphate, and deionized water in B2 is 60-80g: 300-400mL: 8-12g: 50-60mL. The ratio of zinc nitrate, deionized water, citric acid, and second-modified nano-titanium dioxide in B3 is 5-8g: 100-120mL: 2-3g: 50-70g.

6. The flexible fluorocarbon paint according to claim 5, characterized in that: During ultrasonic dispersion in B1, an intermittent ultrasonic mode is used, that is, ultrasonic operation for 3 minutes, pause for 1 minute, and cycled until the total dispersion time reaches 30-40 minutes.

7. A method for preparing a flexible fluorocarbon paint, characterized in that: The preparation method is implemented based on the flexible fluorocarbon paint according to any one of claims 1-6, and specifically includes the following steps: S1. Place the modified nano-titanium dioxide, barium sulfate, and talc powder into a forced-air drying oven and dry them at 100-120℃ for 2-3 hours. After drying, mix them and add them to an air jet mill with an inlet pressure of 0.6-0.8MPa and a classifier speed of 20000r / min. Grind for 15-20 minutes and control the particle size of the pigment mixture powder to be 1-5μm. S2. Add the xylene and butyl acetate mixture to the dispersion vessel, and add polyacrylate and organobentonite sequentially while stirring at 800-1000 r / min. Stir for 15-20 min until completely dissolved. Slowly add the pigment powder mixture from S1 while stirring. After the addition is complete, increase the speed to 1500-2000 r / min and disperse at high speed for 30-40 min to form a uniform pigment slurry. Filter with a 40-mesh filter to remove any obvious particles. S3. Transfer the pigment slurry to a horizontal sand mill. The grinding media is zirconium beads with a particle size of 1.0-1.2 mm and a filling rate of 70-75%. Add modified fluorocarbon resin and hydroxyl acrylic resin. Grind at a sand mill speed of 1500-1800 r / min for 2-3 hours. During this period, take a sample every 30 minutes and test it with a scraper fineness gauge. Control the temperature to ≤40℃ until the fineness is ≤15μm and then stop grinding. S4. Transfer the properly ground coating to a mixing tank. While stirring at 600-800 rpm, add epoxidized soybean oil, silane coupling agent KH-550, acrylate leveling agent, and polydimethylsiloxane in sequence. Stir for 5-10 minutes after each addition. Finally, slowly add toluene diisocyanate and stir for 15-20 minutes. Use a Ford cup at 25°C to test the viscosity for 20-30 seconds. If the viscosity is too high, add an appropriate amount of solvent to adjust it. Stir for 5 minutes and test again to ensure the viscosity is stable. Filter the coating through a 100-200 mesh nylon filter to obtain flexible fluorocarbon paint.