High solid nano fluorocarbon primer

Abstract

This invention relates to the field of coating technology, specifically to a high-solids nano-fluorocarbon primer. The first component of this invention comprises fluorocarbon resin, leveling agent, defoamer, dispersant, filler, pigment, additives, thixotropic agent, and solvent. The second component is an aliphatic isocyanate polymer. The additives consist of modified carbon nanotubes and fluorinated nanocellulose. Due to the conductivity of the carbon nanotubes, the loaded BYK-306 can better exert its leveling effect. Furthermore, the polyamide wax can better utilize intermolecular hydrogen bonds to form a network structure within the modified carbon nanotubes, preventing sagging and exhibiting strong adsorption affinity for metal ions, which facilitates better adhesion of the primer to the substrate. Additionally, the -CF3 groups introduced onto the surface of the fluorinated nanocellulose can reduce surface energy and enhance compatibility with the fluorocarbon resin, further improving the overall leveling properties of the fluorocarbon primer and demonstrating broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a high-solids nano-fluorocarbon primer. Background Technology

[0002] Fluorocarbon coatings refer to coatings that use fluoropolymers as the main film-forming substance. In Europe and America, coatings based on fluoroolefin polymers or copolymers of fluoroolefins with other monomers are called "fluorocarbon coatings," while in my country they are often called "fluorinated coatings." The development of fluorocarbon coatings has gone through several stages, from the initial hot-melt type to solvent-soluble type, then to room temperature / room temperature curing type (crosslinking type), subsequently developing into water-based / high-solids coatings, and finally to today's powder coatings. Each step of progress is based on scientific advancements and technological innovation.

[0003] Fluorocarbon primer is made by grinding and dispersing various corrosion-resistant pigments, fillers, additives and solvents into a fluorocarbon base material, which is based on fluorine-modified polymer resin. It is widely used in cement mortar, concrete, brick walls and asbestos boards for the interior and exterior walls of buildings.

[0004] Fluorocarbon primers, due to the high electronegativity of fluorine and the strong carbon-fluorine bond, possess exceptionally superior properties. These include excellent weather resistance, heat resistance, low-temperature resistance, and chemical resistance, as well as unique non-stick and low-friction characteristics. After decades of rapid development, fluorocarbon coatings have been widely used in various fields, including construction, chemical industry, electrical and electronic industry, machinery industry, aerospace industry, and household products. With current technological advancements, the preparation and research of fluorocarbon coatings are becoming increasingly extensive, further enhancing their performance.

[0005] Currently, countries worldwide are increasingly emphasizing environmental protection and green development. Long-lasting fluorocarbon coatings are still primarily solvent-based, resulting in high VOC emissions, posing a threat to the environment and the health of construction workers. Furthermore, the recent introduction of a consumption tax on coatings has made it crucial for the industry to address how to reduce VOC emissions and losses during application while ensuring the protective effect of the coating. Waterborne fluorocarbon coatings have lower VOCs, but their application in industrial coatings remains limited due to factors such as synthesis technology and performance limitations. Powdered fluorocarbon coatings emit no VOCs during production and application, meeting environmental requirements, but their application requires specialized equipment and high-temperature drying, making them unsuitable for large structural components. High-solids fluorocarbon coatings can be applied to large and complex structures indoors or outdoors, exhibiting high tolerance to environmental temperature and humidity, making them a widely applicable green industrial anti-corrosion coating option.

[0006] In existing technical literature, such as patent document CN105238170A, a high-solids fluorocarbon coating formulation and its preparation method are disclosed. The fluorocarbon coating in this invention is prepared from polymers such as low-polymerization-degree polychlorotrifluoroethylene resin, low-viscosity hydroxyl polysiloxane resin, and fluorinated hydroxyl vinyl resin, as well as a highly active low-viscosity crosslinking agent, organic and inorganic coloring pigments, inorganic fillers, organic solvents, dispersants, thickeners, defoamers, and leveling agents. The fluorocarbon coating prepared by this invention has a high solids content, which can greatly reduce the emission of organic solvents. However, the overall leveling properties of this fluorocarbon material need to be further improved.

[0007] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop a high-solids nano-fluorocarbon primer. Summary of the Invention

[0008] In view of this, the purpose of this invention is to provide a high-solids nano-fluorocarbon primer to solve the problem of poor flowability of high-solids fluorocarbon coatings in electrostatic spraying in the prior art.

[0009] To achieve the above objectives, the present invention provides a high-solids nano-fluorocarbon primer, comprising the following raw materials in parts by weight:

[0010] Component 1: 32-40g; Component 2: 3-4g;

[0011] The first component is prepared from the following parts by weight of raw materials:

[0012] Fluorocarbon resin 95-108g; leveling agent 0.28-0.35g; defoamer 0.6-0.72g; dispersant 1.8-2.5g; filler 1-3g; pigment 0.5-1g; thixotropic agent 2.6-3g; additives 0.3-1.2g; solvent 18-23g;

[0013] The second component is an aliphatic isocyanate polymer;

[0014] The aliphatic isocyanate polymer was obtained by mixing N3390 and Basonat HI-190 in a mass ratio of 8-14:4-7;

[0015] The fluorocarbon resin is obtained by mixing HLR-6 and HLR-670 in a mass ratio of 1:2-2.7;

[0016] The additive is obtained by mixing modified carbon nanotubes and fluorinated nanocellulose in a mass ratio of 23-30:7-12;

[0017] The modified carbon nanotubes were prepared from carbon nanotubes, heptadecafluorodecyltriethoxysilane, BYK-306, and polyamide wax.

[0018] The solvent is obtained by mixing propylene glycol methyl ether acetate, dipropylene glycol dimethyl ether, and butyl acetate in a mass ratio of 8-12:5-8:2-4.

[0019] Preferably, the modified carbon nanotubes are prepared by the following method:

[0020] S1. Add a 70% (w / w) concentrated nitric acid solution to carbon nanotubes and boil for 30-40 minutes. Then, place the solution at 40°C and sonicate for 4-5 hours. After repeated centrifugation and precipitation with deionized water until the solution is neutral, dry the solution to obtain compound A.

[0021] S2. Add a mixed solution A of ethanol and water in a volume ratio of 9:1 to heptadecafluorodecyltriethoxysilane, then add acetic acid to adjust the pH of the solution to 3-4, then add compound A, sonicate for 30-40 min, stir at 55-62℃ for 4-5 h, then centrifuge, wash with deionized water, and dry to obtain compound B;

[0022] S3. Add tetrahydrofuran to compound B, mix well, then add leveling agent BYK-306 and polyamide wax, stir at 40-50℃ for 2.5-3.5h, filter, wash with ethanol aqueous solution, and dry to obtain modified carbon nanotubes.

[0023] Preferably, the ratio of carbon nanotubes to concentrated nitric acid solution in S1 is 0.2-0.32g: 180-230mL;

[0024] The drying temperature is 85-95℃.

[0025] Preferably, the ratio of heptadecafluorodecyltriethoxysilane, mixed solution A, and compound A in S2 is 4.5-5.5g: 110-125mL: 9.8-10.6g;

[0026] The drying temperature is 60-70℃ and the time is 25-30 minutes.

[0027] Preferably, the mass ratio of compound B, tetrahydrofuran, leveling agent BYK-306, and polyamide wax in S3 is 12-16; 30-40: 6-9: 2-5.

[0028] The drying temperature is 55-65℃ and the time is 35-40 minutes.

[0029] Preferably, the preparation method of the fluorinated cellulose nanoparticles is as follows:

[0030] Nanocellulose was added to dimethyl sulfoxide and stirred until homogeneous. The mixture was then placed in a plasma reactor, with carbon tetrafluoride used as the plasma gas. The reactor was evacuated to an initial vacuum level of less than 3 × 10⁻⁶.-3 Pa is subjected to plasma treatment in a dielectric barrier discharge cavity, followed by washing with ethanol 2-3 times and drying to obtain fluorinated nanocellulose.

[0031] Preferably, the mass ratio of dimethyl sulfoxide to nanocellulose is 25-32:5-11; the plasma treatment time is 15-20 min, the power is 110-125 W, and the gas flow rate of carbon tetrafluoride is 4-7 mL / min.

[0032] The drying temperature is 50-60℃ and the time is 20-25 minutes.

[0033] Preferably, the leveling agent is BYK-306;

[0034] The defoamer is AFCONA-2722;

[0035] The filler is either calcium carbonate or silica.

[0036] Preferably, the dispersant is either BASF4401 or BYK161;

[0037] The pigment is diamond titanium dioxide;

[0038] The thixotropic agent is organobentonite.

[0039] Preferably, the preparation method of the first component includes the following steps:

[0040] Fluorocarbon resin, leveling agent, defoamer, dispersant, filler, pigment, additives and thixotropic agent are added to the reaction vessel respectively, then solvent is added, and the mixture is dispersed at high speed until uniform. It is then ground 2-3 times with a horizontal mill until the fineness is below 30μm to obtain the first component. The first component and the second component are mixed to obtain the fluorocarbon resin.

[0041] The high-speed dispersion rate is 800-1000 r / min, and the stirring time is 25-35 min.

[0042] The beneficial effects of this invention are:

[0043] This invention provides a high-solids nano-fluorocarbon primer. The invention involves mixing fluorocarbon resin, leveling agent, defoamer, dispersant, filler, pigment, additives, thixotropic agent, and solvent to obtain a first component. This first component is then combined with an aliphatic isocyanate polymer as a second component to prepare a high-solids fluorocarbon primer with good leveling properties during electrostatic spraying. In this invention, the additives consist of modified carbon nanotubes and fluorinated nanocellulose. During electrostatic spraying, due to the conductivity of the carbon nanotubes, the leveling agent BYK-306 loaded on them can better exert its leveling effect. Furthermore, the polyamide wax contains various active groups, which can better utilize intermolecular hydrogen bonds to form a network structure within the modified carbon nanotubes, preventing sagging. The amide groups have a strong adsorption affinity for metal ions, meaning that this fluorocarbon primer has good adhesion to the metal substrate.

[0044] Furthermore, on the one hand, the surface of fluorinated nanocellulose exhibits slight roughness changes, which helps improve the spreading ability of the paint film and avoids sagging; on the other hand, the -CF3 groups introduced on its surface can reduce surface energy and enhance compatibility with fluorocarbon resins, further improving the overall leveling properties of fluorocarbon primers. Compared with existing technologies, it has broad application prospects. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0046] The sources and properties of some of the raw materials used in this invention are as follows:

[0047] N3390 was purchased from Guangzhou Haoyi Chemical Technology Co., Ltd. Shenzhen Branch; Basonat HI-190 was purchased from BASF; rutile titanium dioxide was purchased from Jinan Yuxing Chemical Co., Ltd.; organo-bentonite was purchased from Shijiazhuang Shuoheng New Material Technology Co., Ltd.; HLR-6 was purchased from Sanaifu Chemical Co., Ltd.; HLR-670 was purchased from Shandong Huafu Co., Ltd.; AFCONA-2722 was purchased from Evcona Co., Ltd.; nanocellulose was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; BASF4401 was purchased from BASF; organo-bentonite was purchased from Zhejiang Fenghong New Material Co., Ltd.; and calcium carbonate was purchased from Xuancheng Huaxin Chemical Co., Ltd.

[0048] Example 1: A method for preparing a high-solids nano-fluorocarbon primer, comprising the following steps:

[0049] S1. Add 180 mL of 70% concentrated nitric acid solution to 0.2 g of carbon nanotubes and boil for 30 min. Then, place the solution at 40 °C and sonicate for 4 h. After repeated centrifugation and precipitation with deionized water until the solution is neutral, dry it at 85 °C to obtain compound A.

[0050] S2. Add 110 mL of a mixed solution A of ethanol and water in a volume ratio of 9:1 to 4.5 g of heptadecafluorodecyltriethoxysilane. Then, add acetic acid dropwise to adjust the pH of the solution to 3. Add 9.8 g of compound A, sonicate for 30 min, stir at 55 °C for 4 h, centrifuge, wash with deionized water, and dry at 60 °C for 25 min to obtain compound B.

[0051] S3. Add 30g tetrahydrofuran to 12g compound B, mix well, then add 6g leveling agent BYK-306 and 2g polyamide wax, stir at 40℃ for 2.5h, filter, wash with ethanol aqueous solution, and dry at 55℃ for 25min to obtain modified carbon nanotubes.

[0052] S4. Add 5g of nanocellulose to 25g of dimethyl sulfoxide, stir well, and place in a plasma reactor. Use carbon tetrafluoride as the plasma gas, and evacuate the reactor to an initial vacuum level of less than 3×10⁻⁶. -3 Pa was subjected to plasma treatment in a dielectric barrier discharge cavity. The plasma treatment time was set to 15 min, the power to be 110 W, and the gas flow rate of carbon tetrafluoride to be 4 mL / min. The mixture was then washed twice with ethanol and dried at 50 °C for 20 min to obtain fluorinated nanocellulose.

[0053] S5. Mix 8g of propylene glycol methyl ether acetate, 5g of dipropylene glycol dimethyl ether, and 2g of butyl acetate evenly to obtain a solvent; mix 1g of HLR-6 and 2g of HLR-670 evenly to obtain a fluorocarbon resin; mix 23g of modified carbon nanotubes and 7g of fluorinated nanocellulose to obtain an additive; mix 8g of N3390 and 4g of Basonat HI-190 to obtain the second component;

[0054] S6. Add 95g of fluorocarbon resin, 0.28g of BYK-306, 0.6g of AFCONA-2722, 1.8g of BYK161, 1g of calcium carbonate, 0.5g of diamond titanium dioxide, 0.3g of additives and 2.6g of organobentonite to the reaction vessel, then add 18g of solvent, disperse at a high speed of 800r / min for 25min, and grind twice with a horizontal mill until the fineness is below 30μm to obtain the first component;

[0055] S7. Mix 32g of the first component and 3g of the second component to obtain a fluorocarbon resin.

[0056] Example 2: A method for preparing a high-solids nano-fluorocarbon primer, comprising the following steps:

[0057] S1. Add 200 mL of 70% concentrated nitric acid solution to 0.24 g of carbon nanotubes and boil for 33 min. Then, place the solution at 40 °C and sonicate for 4.5 h. After repeated centrifugation and precipitation with deionized water until the solution is neutral, dry it at 88 °C to obtain compound A.

[0058] S2. Add 115 mL of a mixed solution A of ethanol and water in a volume ratio of 9:1 to 4.8 g of heptadecafluorodecyltriethoxysilane. Then, add acetic acid dropwise to adjust the pH of the solution to 3. Add 10 g of compound A, sonicate for 33 min, stir at 58 °C for 4.5 h, centrifuge, wash with deionized water, and dry at 63 °C for 25 min to obtain compound B.

[0059] S3. Add 33g of tetrahydrofuran to 14g of compound B, mix well, then add 7g of leveling agent BYK-306 and 3g of polyamide wax, stir at 43℃ for 3h, filter, wash with ethanol aqueous solution, and dry at 58℃ for 28min to obtain modified carbon nanotubes.

[0060] S4. Add 7g of nanocellulose to 28g of dimethyl sulfoxide, stir well, and place in a plasma reactor. Use carbon tetrafluoride as the plasma gas, and evacuate to an initial vacuum level of less than 3×10⁻⁶ using a vacuum pump. -3 Pa was subjected to plasma treatment in a dielectric barrier discharge cavity. The plasma treatment time was set to 17 min, the power to be 115 W, and the gas flow rate of carbon tetrafluoride to be 5 mL / min. The mixture was then washed twice with ethanol and dried at 53 °C for 23 min to obtain fluorinated nanocellulose.

[0061] S5. Mix 9g of propylene glycol methyl ether acetate, 6g of dipropylene glycol dimethyl ether, and 3g of butyl acetate evenly to obtain a solvent; mix 1g of HLR-6 and 2.2g of HLR-670 evenly to obtain a fluorocarbon resin; mix 25g of modified carbon nanotubes and 9g of fluorinated nanocellulose to obtain an additive; mix 10g of N3390 and 5g of Basonat HI-190 to obtain the second component;

[0062] S6. Add 99g of fluorocarbon resin, 0.30g of BYK-306, 0.64g of AFCONA-2722, 2g of BYK161, 1-3g of calcium carbonate, 0.7g of diamond titanium dioxide, 0.6g of additives and 2.7g of organobentonite to the reaction vessel, then add 20g of solvent, disperse at a high speed of 900r / min for 28min, and grind three times with a horizontal mill until the fineness is below 30μm to obtain the first component;

[0063] S7. Mix 35g of the first component and 3.4g of the second component to obtain a fluorocarbon resin.

[0064] Example 3: A method for preparing a high-solids nano-fluorocarbon primer, comprising the following steps:

[0065] S1. Add 220 mL of 70% concentrated nitric acid solution to 0.28 g of carbon nanotubes and boil for 38 min. Then, place the solution at 40 °C and sonicate for 4.5 h. Then, repeatedly centrifuge and precipitate with deionized water until the solution is neutral. Finally, dry the solution at 91 °C to obtain compound A.

[0066] S2. Add 120 mL of a mixed solution A of ethanol and water in a volume ratio of 9:1 to 5 g of heptadecafluorodecyltriethoxysilane. Then, add acetic acid to adjust the pH of the solution to 4. Add 10.3 g of compound A, sonicate for 38 min, stir at 60 °C for 4.5 h, centrifuge, wash with deionized water, and dry at 68 °C for 28 min to obtain compound B.

[0067] S3. Add 38g of tetrahydrofuran to 15g of compound B, mix well, then add 8g of leveling agent BYK-306 and 4g of polyamide wax, stir at 48℃ for 3h, filter, wash with ethanol aqueous solution, and dry at 62℃ for 28min to obtain modified carbon nanotubes.

[0068] S4. Add 9g of nanocellulose to 30g of dimethyl sulfoxide, stir well, and place in a plasma reactor. Use carbon tetrafluoride as the plasma gas, and evacuate the reactor to an initial vacuum level of less than 3×10⁻⁶. -3 Pa was subjected to plasma treatment in a dielectric barrier discharge cavity. The plasma treatment time was set to 18 min, the power to be 120 W, and the gas flow rate of carbon tetrafluoride to be 6 mL / min. The mixture was then washed three times with ethanol and dried at 58 °C for 25 min to obtain fluorinated nanocellulose.

[0069] S5. Mix 11g of propylene glycol methyl ether acetate, 7g of dipropylene glycol dimethyl ether, and 3g of butyl acetate evenly to obtain a solvent; mix 1g of HLR-6 and 2.5g of HLR-670 evenly to obtain a fluorocarbon resin; mix 28g of modified carbon nanotubes and 11g of fluorinated nanocellulose to obtain an additive; mix 12g of N3390 and 6g of Basonat HI-190 to obtain the second component;

[0070] S6. Add 104g of fluorocarbon resin, 0.32g of BYK-306, 0.68g of AFCONA-2722, 2.2g of BYK161, 2g of calcium carbonate, 0.8g of diamond titanium dioxide, 0.9g of additives and 2.9g of organobentonite to the reaction vessel, then add 22g of solvent, disperse at a high speed of 900r / min for 32min, and grind three times with a horizontal mill until the fineness is below 30μm to obtain the first component;

[0071] S7. Mix 37g of the first component and 4g of the second component to obtain a fluorocarbon resin.

[0072] Example 4: A method for preparing a high-solids nano-fluorocarbon primer, comprising the following steps:

[0073] S1. Add 230 mL of 70% concentrated nitric acid solution to 0.32 g of carbon nanotubes and boil for 40 min. Then, place the solution at 40 °C and sonicate for 5 h. After repeated centrifugation and precipitation with deionized water until the solution is neutral, dry it at 95 °C to obtain compound A.

[0074] S2. Add 125 mL of a mixed solution A of ethanol and water in a volume ratio of 9:1 to 5.5 g of heptadecafluorodecyltriethoxysilane. Then, add acetic acid to adjust the pH of the solution to 4. Add 10.6 g of compound A, sonicate for 40 min, stir at 62 °C for 5 h, centrifuge, wash with deionized water, and dry at 70 °C for 30 min to obtain compound B.

[0075] S3. Add 40g tetrahydrofuran to 16g compound B, mix well, then add 9g leveling agent BYK-306 and 5g polyamide wax, stir at 50℃ for 3.5h, filter, wash with ethanol aqueous solution, and dry at 65℃ for 30min to obtain modified carbon nanotubes.

[0076] S4. Add 11g of nanocellulose to 32g of dimethyl sulfoxide, stir well, and place in a plasma reactor. Use carbon tetrafluoride as the plasma gas, and evacuate to an initial vacuum level of less than 3×10⁻⁶ using a vacuum pump. -3 Pa was subjected to plasma treatment in a dielectric barrier discharge cavity. The plasma treatment time was set to 20 min, the power to be 125 W, and the gas flow rate of carbon tetrafluoride to be 7 mL / min. The mixture was then washed three times with ethanol and dried at 60 °C for 25 min to obtain fluorinated nanocellulose.

[0077] S5. Mix 12g of propylene glycol methyl ether acetate, 8g of dipropylene glycol dimethyl ether, and 4g of butyl acetate evenly to obtain a solvent; mix 1g of HLR-6 and 2.7g of HLR-670 evenly to obtain a fluorocarbon resin; mix 30g of modified carbon nanotubes and 12g of fluorinated nanocellulose to obtain an additive; mix 14g of N3390 and 7g of Basonat HI-190 to obtain the second component;

[0078] S6. Add 108g of fluorocarbon resin, 0.35g of BYK-306, 0.72g of AFCONA-2722, 2.5g of BYK161, 3g of calcium carbonate, 1g of diamond titanium dioxide, 1.2g of additives and 3g of organobentonite to the reaction vessel, then add 23g of solvent, disperse at a high speed of 1000r / min for 35min, and grind three times with a horizontal mill until the fineness is below 30μm to obtain the first component;

[0079] S7. Mix 40g of the first component and 4g of the second component to obtain fluorocarbon resin.

[0080] Comparative Example 1:

[0081] Compared with Example 1, this comparative example did not add modified carbon nanotubes in the preparation process of the high-solids nano-fluorocarbon primer. All other steps and parameters were the same, and will not be repeated here. The final high-solids nano-fluorocarbon primer was obtained.

[0082] Comparative Example 2:

[0083] Compared with Example 1, this comparative example did not add fluorinated nanocellulose in the preparation process of the high-solids nano-fluorocarbon primer. All other steps and parameters were the same, and will not be repeated here. The final high-solids nano-fluorocarbon primer was obtained.

[0084] Comparative Example 3:

[0085] This comparative example differs from Example 1 only in that "modified carbon nanotubes" are replaced with "carbon nanotubes". All other steps and parameters are the same, and will not be repeated here. The final result is a high-solids nano-fluorocarbon primer.

[0086] Comparative Example 4:

[0087] This comparative example differs from Example 1 only in that "fluorinated nanocellulose" is replaced with "nanocellulose". All other steps and parameters are the same, and will not be repeated here. The final result is a high-solids nano-fluorocarbon primer.

[0088] Comparative Example 5:

[0089] Compared with Example 1, this comparative example only replaces "12g propylene glycol methyl ether acetate, 8g dipropylene glycol dimethyl ether and 4g butyl acetate" with "24g butyl acetate". All other steps and parameters are the same, and will not be repeated in this comparative example. The final result is a high-solids nano-fluorocarbon primer.

[0090] Performance testing:

[0091] Tinplate with dimensions of 150mm×70mm×(0.2-0.3)mm was used as the substrate. Before spraying, it was sanded with 400-grit sandpaper and then wiped clean with acetone. The high-solids nano-fluorocarbon primers prepared in Examples 1-4 and Comparative Examples 1-5 were uniformly sprayed onto the substrate using an electrostatic spray gun and dried in an oven at 105℃±2℃ for 1 hour. After drying, the samples were taken out and cooled to room temperature to obtain 9 samples of Examples 1-4 and Comparative Examples 1-5.

[0092] Solid content: According to the test standard GB / T 1725-2007, 1g of the high solids nano fluorocarbon primer prepared in Examples 1-4 and Comparative Examples 1-5 were taken and uniformly sprayed onto the sample using an electrostatic spray gun. The sample was then dried in an oven at 105℃±2℃ for 1h. After drying, the sample was taken out and cooled to room temperature. The mass (m2) of the dried sample was weighed using an electronic balance.

[0093] Formula for calculating solid content:

[0094]

[0095] Where m1 is the mass of the sample before drying, and m2 is the mass of the sample after drying;

[0096] Tensile strength: The tensile strength of each group of samples was tested in accordance with the GB / T 258-2009 test standard;

[0097] Acid resistance: According to the test standard GB / T 9274-88, each group of samples was immersed in a 10% hydrochloric acid solution for 672 hours and a 10% sodium hydroxide solution for 672 hours, and the weight gain of each group of samples was observed.

[0098] Salt spray resistance: Salt spray resistance performance of each group of samples was tested in accordance with ISO7253 standard, and the surface condition of each group of samples was recorded after 800h of salt spray test.

[0099] Impact resistance: The impact resistance of each group of samples was tested in accordance with GB / T1732-1993 standard;

[0100] Adhesion: The adhesion of each group of samples was tested in accordance with GB / T 9286—1998 standard;

[0101] Leveling property: The leveling property of each group of samples was tested in accordance with GB / T1727-79 standard;

[0102] Leveling performance evaluation criteria:

[0103] Good leveling properties: The coating reaches a smooth surface within 10 minutes after spraying, with no obvious brush marks or orange peel, and the surface is relatively flat.

[0104] Poor leveling: The coating does not achieve a smooth surface even after more than 10 minutes, and the surface has brush marks, orange peel, and general surface flatness.

[0105] Extremely poor leveling properties: The coating surface cannot be smoothed, and there are a large number of brush marks, bubbles or accumulation.

[0106] Table 1

[0107]

[0108] Table 2

[0109]

[0110]

[0111] Data Analysis:

[0112] As can be seen from Tables 1 and 2, the high-solids nano-fluorocarbon primer prepared by this invention exhibits better leveling properties, adhesion, and impact resistance, and also has a high solids content. This may be because the additives in this invention consist of modified carbon nanotubes and fluorinated nanocellulose. The modified carbon nanotubes, after being chemically modified with a fluorinated silane coupling agent, possess a large number of active groups on their surface, exhibiting high surface activity. This allows them to chemically react and physically adsorb with the fluororesins and pigments in the coating, thereby enhancing the adhesion between the coating and the substrate. Furthermore, it effectively improves the dispersibility of carbon nanotubes in the coating, preventing agglomeration and thus improving the overall leveling properties of the coating. In electrostatic spraying, due to the conductivity of the carbon nanotubes, the leveling agent BYK-306 loaded onto them can better exert its leveling effect. Additionally, the polyamide wax contains various active groups, which... Modified carbon nanotubes can better utilize intermolecular hydrogen bonds to form a network structure, preventing sagging. The amide groups within them have a strong adsorption affinity for metal ions, meaning the fluorocarbon primer has good adhesion to the metal substrate. Furthermore, on one hand, the fluorinated nanocellulose surface exhibits slight roughness changes, which improves the film's spreading ability and prevents sagging. On the other hand, the -CF3 groups introduced on its surface reduce surface energy and enhance compatibility with fluorocarbon resin, further improving the overall leveling properties of the fluorocarbon primer. Moreover, the solvent in this invention consists of three solvents with different evaporation rates: fast, medium, and slow. These three solvents work synergistically to make the entire coating surface smoother and flatter, reducing leveling defects such as orange peel and pinholes. During evaporation, a certain amount of shrinkage stress is generated, improving adhesion to the substrate.

[0113] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0114] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A high-solids nano-fluorocarbon primer, characterized in that, Includes the following quantities of raw materials: Component 1: 32-40g; Component 2: 3-4g; The first component is prepared from the following parts by weight of raw materials: Fluorocarbon resin 95-108g; leveling agent 0.28-0.35g; defoamer 0.6-0.72g; dispersant 1.8-2.5g; filler 1-3g; pigment 0.5-1g; thixotropic agent 2.6-3g; additives 0.3-1.2g; solvent 18-23g; The second component is an aliphatic isocyanate polymer; The aliphatic isocyanate polymer was obtained by mixing N3390 and Basonat HI-190 in a mass ratio of 8-14:4-7; The fluorocarbon resin is obtained by mixing HLR-6 and HLR-670 in a mass ratio of 1:2-2.7; The additive is obtained by mixing modified carbon nanotubes and fluorinated nanocellulose in a mass ratio of 23-30:7-12; The modified carbon nanotubes were prepared from carbon nanotubes, heptadecafluorodecyltriethoxysilane, BYK-306, and polyamide wax. The solvent is obtained by mixing propylene glycol methyl ether acetate, dipropylene glycol dimethyl ether and butyl acetate in a mass ratio of 8-12:5-8:2-4; The modified carbon nanotubes are prepared as follows: S1. Add a 70% (w / w) concentrated nitric acid solution to carbon nanotubes and boil for 30-40 minutes. Then, place the solution at 40°C and sonicate for 4-5 hours. Repeatedly centrifuge and precipitate with deionized water until the solution is neutral. Dry the solution to obtain compound A. S2. Add a mixed solution A of ethanol and water in a volume ratio of 9:1 to heptadecafluorodecyltriethoxysilane, then add acetic acid dropwise to adjust the pH of the solution to 3-4, then add compound A, sonicate for 30-40 min, stir at 55-62°C for 4-5 h, then centrifuge, wash with deionized water, and dry to obtain compound B; S3. Add tetrahydrofuran to compound B, mix well, then add leveling agent BYK-306 and polyamide wax, stir at 40-50°C for 2.5-3.5h, filter, wash with ethanol aqueous solution, and dry to obtain modified carbon nanotubes. The preparation method of the fluorinated cellulose nanoparticles is as follows: Nanocellulose was added to dimethyl sulfoxide and stirred until homogeneous. The mixture was then placed in a plasma reactor, with carbon tetrafluoride used as the plasma gas. The reactor was evacuated to an initial vacuum level of less than 3 × 10⁻⁶. -3 Pa was subjected to plasma treatment in a dielectric barrier discharge cavity, then washed with ethanol 2-3 times and dried to obtain fluorinated nanocellulose. The mass ratio of dimethyl sulfoxide to nanocellulose is 25-32:5-11; The plasma treatment time is 15-20 min, the power is 110-125 W, and the carbon tetrafluoride gas flow rate is 4-7 mL / min; The drying temperature is 50-60°C and the time is 20-25 minutes.

2. The high-solids nano-fluorocarbon primer according to claim 1, characterized in that, The ratio of carbon nanotubes to concentrated nitric acid solution in S1 is 0.2-0.32g: 180-230mL; The drying temperature is 85-95°C and the time is 25-30 minutes.

3. The high-solids nano-fluorocarbon primer according to claim 1, characterized in that, The ratio of heptadecafluorodecyltriethoxysilane, mixed solution A, and compound A in S2 is 4.5-5.5 g : 110-125 mL : 9.8-10.6 g; The drying temperature is 60-70°C and the time is 25-30 minutes.

4. The high-solids nano-fluorocarbon primer according to claim 1, characterized in that, The mass ratio of compound B, tetrahydrofuran, leveling agent BYK-306, and polyamide wax in S3 is 12-16; 30-40: 6-9: 2-5. The drying temperature is 55-65°C and the time is 35-40 minutes.

5. The high-solids nano-fluorocarbon primer according to claim 1, characterized in that, The leveling agent is BYK-306; The defoamer is AFCONA-2722; The filler is either calcium carbonate or silica.

6. The high-solids nano-fluorocarbon primer according to claim 1, characterized in that, The dispersant is either BASF4401 or BYK161; The pigment is diamond titanium dioxide; The thixotropic agent is organobentonite.

7. The high-solids nano-fluorocarbon primer according to claim 1, characterized in that, The preparation method of the first component includes the following steps: Fluorocarbon resin, leveling agent, defoamer, dispersant, filler, pigment, additives and thixotropic agent are added to the reaction vessel respectively, then solvent is added, and the mixture is dispersed at high speed until uniform. It is then ground 2-3 times with a horizontal mill until the fineness is below 30μm to obtain the first component. The first component and the second component are mixed to obtain the fluorocarbon resin. The high-speed dispersion rate is 800-1000 r / min, and the stirring time is 25-35 min.

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