A single-layer UV-resistant heavy-duty anti-corrosion powder coating, its preparation method and application

Abstract

This invention relates to the field of polymer materials and protective coatings, and discloses a single-layer UV-resistant heavy-duty anti-corrosion powder coating, its preparation method, and its application. The preparation method of the single-layer UV-resistant heavy-duty anti-corrosion powder coating includes: carboxyl polyester resin, triglycidyl isocyanurate, modified nano-silica, modified chitosan, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-amylphenol, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, flake aluminum powder, and phosphorus... Zinc sulfate, BYK-392, 2-hydroxy-1,2-diphenyl ethyl ketone, and γ-aminopropyltriethoxysilane were mixed at room temperature with stirring at 300-350 rpm for 10-15 minutes to obtain a mixture. This mixture was then extruded using a twin-screw extruder at 110-120°C and a screw speed of 450-500 rpm. The mixture was then ground to obtain a single-layer UV-resistant heavy-duty anti-corrosion powder coating. This single-layer UV-resistant heavy-duty anti-corrosion powder coating can be applied to the protection of metal substrates. The coating prepared by this invention has excellent UV resistance and anti-corrosion properties.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and protective coating technology, specifically to the formulation design, preparation process and application of a high-performance powder coating, and in particular to a high-durability heavy-duty anti-corrosion powder coating that can achieve excellent UV aging resistance and meet the requirements of harsh corrosive environments (C4-C5 level) with a single coating. Background Technology

[0002] Traditional protective systems have several limitations in application. For example, multi-layer coating systems, while offering good protection, suffer from complex construction procedures, long cycles, high VOC emissions, poor inter-coating compatibility, difficult quality control, and high overall costs. Single-layer powder coatings, primarily based on epoxy and epoxy polyester, while providing good corrosion resistance and mechanical properties, have poor weather resistance and are prone to chalking, discoloration, and loss of gloss outdoors, making them unsuitable for long-term protective topcoats. Therefore, avoiding these issues is key to solving the problem. The market urgently needs coating solutions that simplify construction, are environmentally friendly and efficient, and possess both long-term UV aging resistance and excellent heavy-duty corrosion resistance. These solutions should effectively integrate high-corrosion-resistant and high-weather-resistant components in a single layer, ensuring processing stability, leveling properties, and mechanical properties. For instance, patent CN120310435A discloses an environmentally friendly epoxy asphalt anti-corrosion coating. This coating is simple and convenient to prepare and possesses green environmental protection and corrosion resistance characteristics; however, its UV aging resistance needs improvement. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a single-layer UV-resistant heavy-duty anti-corrosion powder coating, its preparation method, and its application. The coating prepared by this invention has excellent UV resistance and anti-corrosion properties and can be applied to the protection of metal substrates.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a single-layer UV-resistant heavy-duty anti-corrosion powder coating, comprising the following weight components: 55-60 parts by weight of carboxyl polyester resin, 8-12 parts by weight of triglycidyl isocyanurate, 3-5 parts by weight of modified nano-silica, 2-4 parts by weight of modified chitosan, 1-2 parts by weight of 2-(2H-benzotriazol-2-yl)-4,6-ditert-amylphenol, 1-1.5 parts by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 8-10 parts by weight of flake aluminum powder, 3-6 parts by weight of zinc phosphate, 0.6-1 parts by weight of BYK-392, 0.3-0.5 parts by weight of 2-hydroxy-1,2-diphenyl ethyl ketone, and 0.2-0.3 parts by weight of γ-aminopropyltriethoxysilane.

[0007] Furthermore, the method for preparing the modified nano-silica is as follows:

[0008] Step 1: Add 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and 3-mercaptopropionic acid to tetrahydrofuran solvent, stir and mix, then add p-toluenesulfonic acid, and react at 65-75℃ for 6-8 hours. After the reaction is completed, wash and dry, purify, and obtain intermediate 1.

[0009] Step 2: Under nitrogen protection, add intermediate 1 and vinyltriethoxysilane to N,N-dimethylformamide solvent, stir and disperse, then add benzoin dimethyl ether photoinitiator, and irradiate with 365nm ultraviolet light at 30-45℃ for 3-4 hours. After the irradiation, centrifuge, wash and dry to obtain intermediate 2.

[0010] Step 3: Disperse nano-silica in deionized water and sonicate at 55-60℃ for 20-30 min. Then add intermediate 2, stir and mix, and continue the reaction for 3-4 h. After the reaction is complete, centrifuge, filter, and dry to obtain modified nano-silica.

[0011] Further, in step one, the ratio of tetrahydrofuran, 2-(2,4-dihydroxyphenyl)-2H-benzotriazole, 3-mercaptopropionic acid, and p-toluenesulfonic acid is 40-50 mL: 2.25-2.28 g: 1.06-1.08 g: 0.04-0.05 g.

[0012] Furthermore, in step two, the ratio of N,N-dimethylformamide, intermediate 1, vinyltriethoxysilane, and benzoin dimethyl ether is 22-25 mL: 2.14-2.18 g: 2.41-2.45 g: 0.03-0.05 g.

[0013] Furthermore, in step three, the ratio of nano-silica, deionized water, and intermediate 2 is 3.62-3.66g: 28-30mL: 2.32-2.38g.

[0014] Furthermore, the method for preparing the modified chitosan is as follows:

[0015] S1: Chitosan was swollen in a 3% acetic acid solution for 1-2 hours, and then N,N-diisopropylethylamine and pyrazole-1-formamidin were added. The mixture was stirred and stirred, and the reaction was carried out at room temperature for 20-24 hours. After the reaction was completed, the mixture was filtered, washed and dried, and purified by column chromatography to obtain guanidinolated chitosan.

[0016] S2: Guanidyl-modified chitosan was swollen in a 3% acetic acid solution for 2-3 hours, then stearic acid and p-toluenesulfonic acid were added, and the mixture was stirred at 50-60℃ for 5-8 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain modified chitosan.

[0017] Furthermore, in S1, the ratio of chitosan, acetic acid solution with a mass fraction of 3%, N,N-diisopropylethylamine, and pyrazole-1-formamidin is 1.12-1.15g:18-20mL:4.32-4.36mL:3.83-3.87g.

[0018] Furthermore, in S2, the ratio of guanidinated chitosan, acetic acid solution with a mass fraction of 3%, stearic acid, and p-toluenesulfonic acid is 2.03-2.05g: 22-25mL: 1.65-1.68g: 0.04-0.06g.

[0019] Further, the preparation method of the single-layer UV-resistant heavy-duty anti-corrosion powder coating is as follows: carboxylated polyester resin, triglycidyl isocyanurate, modified nano silica, modified chitosan, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-amylphenol, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, flake aluminum powder, zinc phosphate, BYK-392, 2-hydroxy-1,2-diphenyl ethyl ketone, and γ-aminopropyltriethoxysilane are stirred and mixed at 300-350 rpm for 10-15 min at room temperature to obtain a mixture. The mixture is then extruded through a twin-screw extruder at an extrusion temperature of 110-120℃ and a screw speed of 450-500 rpm. After grinding, a single-layer UV-resistant heavy-duty anti-corrosion powder coating is obtained.

[0020] Furthermore, the application of the single-layer UV-resistant heavy-duty anti-corrosion powder coating in the protection of metal substrates.

[0021] (iii) Beneficial technical effects

[0022] This invention modifies nano-silica with 2-(2,4-dihydroxyphenyl)-2H-benzotriazole, introducing benzotriazole groups. Benzotriazole groups effectively absorb ultraviolet light, converting light energy into heat energy through intramolecular structural transformation, thus reducing UV damage to the coating. Furthermore, the small size of the nano-silica particles allows for uniform dispersion within the coating, reducing UV penetration depth by scattering and reflecting ultraviolet light, thereby improving the coating's resistance to UV aging. Additionally, the nano-silica itself is chemically stable, resistant to acids, alkalis, and solvents, and does not readily react with corrosive media, thus protecting the coating substrate from erosion and enhancing the coating's resistance to corrosion. The corrosion resistance is improved. By reacting chitosan with N,N-diisopropylethylamine, guanidine groups are introduced. The electron-rich nitrogen atoms in the guanidine group can combine with the empty orbitals on the surface of the metal substrate to form a dense coordination compound film, which inhibits the anodic dissolution reaction and improves the anti-corrosion ability of the coating. In addition, the conjugated structure in the guanidine group can absorb part of the ultraviolet band and can synergistically enhance the effect with benzotriazole ultraviolet absorbers. Subsequently, it undergoes an esterification reaction with stearic acid. Stearic acid is a fatty acid with long carbon chain and low surface energy. Introducing low surface energy materials into the metal surface to prepare hydrophobic coatings can effectively enhance the anti-corrosion performance of the coating and prevent corrosive ion etching of metal. Attached Figure Description

[0023] Figure 1 It is the synthesis reaction formula for intermediate 2.

[0024] Figure 2 It is the synthesis reaction formula for modified chitosan. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0026] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0027] According to the reference "Research and Application of 2,2,4,4-Tetramethyl-1,3-cyclobutanediol in Polyester Resin Synthesis and Powder Coatings": Based on the finished product weight, the following formula is used: neopentyl glycol: 38-42%, 2,2,4,4-tetramethyl-1,3-cyclobutanediol: 0-5%, terephthalic acid: 58-60%, acid hydrolysate: 10-11%, monobutyltin oxide: 0.06%, and other raw materials (triphenyl phosphite, antioxidant, and BETP): 0.5%. Neopentyl glycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, monobutyltin oxide, and a small amount of distilled water are added to a 6L glass reactor and heated until completely dissolved. Then, terephthalic acid is added, nitrogen gas is introduced, and the temperature is raised to 240℃ and maintained for 4-5 hours. During the process, maintain the column top temperature ≤101℃; after the material becomes clear and transparent, take a sample to test the acid value; when the acid value reaches 8-15 mg KOH / g, add triphenyl phosphite and acid hydrolysate, and heat again to 245℃ and hold for 2-3 hours. During this process, maintain the column top temperature ≤101℃. After the column top temperature drops below 55℃, take a sample to test the acid value. When the acid value reaches 45-48 mg KOH / g, perform vacuum polycondensation at -0.01 MPa until the acid value reaches 33-36 mg KOH / g, then stop the polycondensation. Finally, cool to about 200℃, add antioxidant and BETP, stir evenly, pour out and allow to cool naturally to obtain carboxylated polyester resin.

[0028] Example 1

[0029] (1) Add 2.25 g of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and 1.06 g of 3-mercaptopropionic acid to 40 mL of tetrahydrofuran solvent, stir and mix, then add 0.04 g of p-toluenesulfonic acid, and react at 65 °C for 6 h. After the reaction is completed, wash and dry, purify, and obtain intermediate 1;

[0030] (2) Under nitrogen protection, 2.14 g of intermediate 1 and 2.41 g of vinyltriethoxysilane were added to 22 mL of N,N-dimethylformamide solvent, stirred and dispersed, and then 0.03 g of benzoin dimethyl ether photoinitiator was added. The mixture was irradiated with 365 nm ultraviolet light at 30 °C for 3 h. After the irradiation, the mixture was centrifuged, washed and dried to obtain intermediate 2.

[0031] (3) Disperse 3.62g of nano silica in 28mL of deionized water, sonicate at 55℃ for 20min, then add 2.32g of intermediate 2, stir and mix, and continue to react for 3h. After the reaction is completed, centrifuge, filter, and dry to obtain modified nano silica.

[0032] (4) 1.12 g of chitosan was swollen in 18 mL of 3% acetic acid solution for 1 h, and then 4.32 mL of N,N-diisopropylethylamine and 3.83 g of pyrazole-1-formamidin were added. The mixture was stirred and stirred, and the reaction was carried out at room temperature for 20 h. After the reaction was completed, the mixture was filtered, washed and dried, and purified by column chromatography to obtain guanidinolated chitosan.

[0033] (5) 2.03 g of guanidinated chitosan was swollen in 22 mL of 3% acetic acid solution for 2 h, and then 1.65 g of stearic acid and 0.04 g of p-toluenesulfonic acid were added. The mixture was stirred at 50 °C for 5 h. After the reaction was completed, the mixture was filtered, washed and dried to obtain modified chitosan.

[0034] (6) 55 parts by weight of carboxylated polyester resin, 8 parts by weight of triglycidyl isocyanurate, 3 parts by weight of modified nano silica, 2 parts by weight of modified chitosan, 1 part by weight of 2-(2H-benzotriazol-2-yl)-4,6-ditert-pentylphenol, 1 part by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 8 parts by weight of flake aluminum powder, 3 parts by weight of zinc phosphate, 0.6 parts by weight of BYK-392, 0.3 parts by weight of 2-hydroxy-1,2-diphenyl ethyl ketone, and 0.2 parts by weight of γ-aminopropyltriethoxysilane were stirred and mixed at 300 rpm for 10 min at room temperature to obtain a mixture. The mixture was then extruded through a twin-screw extruder at an extrusion temperature of 110°C and a screw speed of 450 rpm. After grinding, a single-layer UV-resistant heavy-duty anti-corrosion powder coating was obtained.

[0035] Example 2

[0036] (1) Add 2.28 g of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and 1.08 g of 3-mercaptopropionic acid to 50 mL of tetrahydrofuran solvent, stir and mix, then add 0.05 g of p-toluenesulfonic acid, and react at 75 °C for 8 h. After the reaction is completed, wash and dry, purify, and obtain intermediate 1;

[0037] (2) Under nitrogen protection, 2.18 g of intermediate 1 and 2.45 g of vinyltriethoxysilane were added to 25 mL of N,N-dimethylformamide solvent, stirred and dispersed, and then 0.05 g of benzoin dimethyl ether photoinitiator was added. The mixture was irradiated with 365 nm ultraviolet light at 45 °C for 4 h. After the irradiation, the mixture was centrifuged, washed and dried to obtain intermediate 2.

[0038] (3) Disperse 3.66g of nano silica in 30mL of deionized water, sonicate at 60℃ for 30min, then add 2.38g of intermediate 2, stir and mix, and continue to react for 4h. After the reaction is completed, centrifuge, filter, and dry to obtain modified nano silica.

[0039] (4) 1.15 g of chitosan was swollen in 20 mL of 3% acetic acid solution for 2 h, and then 4.36 mL of N,N-diisopropylethylamine and 3.87 g of pyrazole-1-formamidin were added. The mixture was stirred and mixed, and the reaction was carried out at room temperature for 24 h. After the reaction was completed, the mixture was filtered, washed and dried, and purified by column chromatography to obtain guanidinolated chitosan.

[0040] (5) 2.05 g of guanidinated chitosan was swollen in 25 mL of 3% acetic acid solution for 3 h, and then 1.68 g of stearic acid and 0.06 g of p-toluenesulfonic acid were added. The mixture was stirred at 60 °C for 8 h. After the reaction was completed, the mixture was filtered, washed and dried to obtain modified chitosan.

[0041] (6) 60 parts by weight of carboxylated polyester resin, 12 parts by weight of triglycidyl isocyanurate, 5 parts by weight of modified nano silica, 4 parts by weight of modified chitosan, 2 parts by weight of 2-(2H-benzotriazol-2-yl)-4,6-ditert-pentylphenol, 1.5 parts by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 10 parts by weight of flake aluminum powder, 6 parts by weight of zinc phosphate, 1 part by weight of BYK-392, 0.5 parts by weight of 2-hydroxy-1,2-diphenyl ethyl ketone, and 0.3 parts by weight of γ-aminopropyltriethoxysilane were stirred and mixed at 350 rpm for 15 min at room temperature to obtain a mixture. The mixture was then extruded through a twin-screw extruder at an extrusion temperature of 120°C and a screw speed of 500 rpm. After grinding, a single-layer UV-resistant heavy-duty anti-corrosion powder coating was obtained.

[0042] Example 3

[0043] (1) Add 2.27 g of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and 1.07 g of 3-mercaptopropionic acid to 45 mL of tetrahydrofuran solvent, stir and mix, then add 0.04 g of p-toluenesulfonic acid, and react at 70 °C for 7 h. After the reaction is completed, wash and dry, purify, and obtain intermediate 1;

[0044] (2) Under nitrogen protection, 2.16 g of intermediate 1 and 2.43 g of vinyltriethoxysilane were added to 24 mL of N,N-dimethylformamide solvent, stirred and dispersed, and then 0.04 g of benzoin dimethyl ether photoinitiator was added. The mixture was irradiated with 365 nm ultraviolet light at 40 °C for 3.5 h. After the irradiation, the mixture was centrifuged, washed and dried to obtain intermediate 2.

[0045] (3) Disperse 3.64g of nano silica in 29mL of deionized water, sonicate at 58℃ for 25min, then add 2.35g of intermediate 2, stir and mix, and continue to react for 3.5h. After the reaction is completed, centrifuge, filter and dry to obtain modified nano silica.

[0046] (4) 1.14 g of chitosan was swollen in 19 mL of 3% acetic acid solution for 1.5 h, and then 4.34 mL of N,N-diisopropylethylamine and 3.85 g of pyrazole-1-formamidin were added. The mixture was stirred and mixed, and the reaction was carried out at room temperature for 22 h. After the reaction was completed, the mixture was filtered, washed and dried, and purified by column chromatography to obtain guanidinolated chitosan.

[0047] (5) 2.04 g of guanidinated chitosan was swollen in 24 mL of 3% acetic acid solution for 2.5 h, and then 1.67 g of stearic acid and 0.05 g of p-toluenesulfonic acid were added. The mixture was stirred at 55 °C for 7 h. After the reaction was completed, the mixture was filtered, washed and dried to obtain modified chitosan.

[0048] (6) 58 parts by weight of carboxylated polyester resin, 10 parts by weight of triglycidyl isocyanurate, 4 parts by weight of modified nano silica, 3 parts by weight of modified chitosan, 1 part by weight of 2-(2H-benzotriazol-2-yl)-4,6-ditert-pentylphenol, 1.2 parts by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 9 parts by weight of flake aluminum powder, 5 parts by weight of zinc phosphate, 0.8 parts by weight of BYK-392, 0.4 parts by weight of 2-hydroxy-1,2-diphenyl ethyl ketone, and 0.2 parts by weight of γ-aminopropyltriethoxysilane were stirred and mixed at 325 rpm for 13 min at room temperature to obtain a mixture. The mixture was extruded through a twin-screw extruder at an extrusion temperature of 115°C and a screw speed of 475 rpm. After grinding, a single-layer UV-resistant heavy-duty anti-corrosion powder coating was obtained.

[0049] Example 4

[0050] (1) Add 2.26 g of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and 1.06 g of 3-mercaptopropionic acid to 42 mL of tetrahydrofuran solvent, stir and mix, then add 0.04 g of p-toluenesulfonic acid, and react at 70 °C for 7 h. After the reaction is completed, wash and dry, purify, and obtain intermediate 1;

[0051] (2) Under nitrogen protection, 2.15 g of intermediate 1 and 2.42 g of vinyltriethoxysilane were added to 23 mL of N,N-dimethylformamide solvent, stirred and dispersed, and then 0.03 g of benzoin dimethyl ether photoinitiator was added. The mixture was irradiated with 365 nm ultraviolet light at 35 °C for 3 h. After the irradiation, the mixture was centrifuged, washed and dried to obtain intermediate 2.

[0052] (3) Disperse 3.63g of nano silica in 28mL of deionized water, sonicate at 56℃ for 22min, then add 2.33g of intermediate 2, stir and mix, continue to react for 3h, centrifuge, filter, and dry to obtain modified nano silica.

[0053] (4) 1.13 g of chitosan was swollen in 18 mL of 3% acetic acid solution for 1 h, and then 4.33 mL of N,N-diisopropylethylamine and 3.84 g of pyrazole-1-formamidin were added. The mixture was stirred and stirred, and the reaction was carried out at room temperature for 21 h. After the reaction was completed, the mixture was filtered, washed and dried, and purified by column chromatography to obtain guanidinolated chitosan.

[0054] (5) 2.03 g of guanidinated chitosan was swollen in 23 mL of 3% acetic acid solution for 2 h, and then 1.66 g of stearic acid and 0.04 g of p-toluenesulfonic acid were added. The mixture was stirred at 52 °C for 6 h. After the reaction was completed, the mixture was filtered, washed and dried to obtain modified chitosan.

[0055] (6) 56 parts by weight of carboxylated polyester resin, 9 parts by weight of triglycidyl isocyanurate, 3 parts by weight of modified nano silica, 3 parts by weight of modified chitosan, 1 part by weight of 2-(2H-benzotriazol-2-yl)-4,6-ditert-pentylphenol, 1 part by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 8 parts by weight of flake aluminum powder, 4 parts by weight of zinc phosphate, 0.7 parts by weight of BYK-392, 0.3 parts by weight of 2-hydroxy-1,2-diphenyl ethyl ketone, and 0.2 parts by weight of γ-aminopropyltriethoxysilane were stirred and mixed at 310 rpm for 11 min at room temperature to obtain a mixture. The mixture was extruded through a twin-screw extruder at an extrusion temperature of 112°C and a screw speed of 460 rpm. After grinding, a single-layer UV-resistant heavy-duty anti-corrosion powder coating was obtained.

[0056] Example 5

[0057] (1) Add 2.27 g of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and 1.08 g of 3-mercaptopropionic acid to 48 mL of tetrahydrofuran solvent, stir and mix, then add 0.05 g of p-toluenesulfonic acid, and react at 72 °C for 8 h. After the reaction is completed, wash and dry, purify, and obtain intermediate 1;

[0058] (2) Under nitrogen protection, 2.17 g of intermediate 1 and 2.44 g of vinyltriethoxysilane were added to 24 mL of N,N-dimethylformamide solvent, stirred and dispersed, and then 0.05 g of benzoin dimethyl ether photoinitiator was added. The mixture was irradiated with 365 nm ultraviolet light at 42 °C for 4 h. After the irradiation, the mixture was centrifuged, washed and dried to obtain intermediate 2.

[0059] (3) Disperse 3.65g of nano silica in 30mL of deionized water, sonicate at 58℃ for 25min, then add 2.36g of intermediate 2, stir and mix, continue to react for 4h, after the reaction is completed, centrifuge, filter, dry to obtain modified nano silica.

[0060] (4) 1.14 g of chitosan was swollen in 20 mL of 3% acetic acid solution for 2 h, and then 4.35 mL of N,N-diisopropylethylamine and 3.86 g of pyrazole-1-formamidin were added. The mixture was stirred and mixed, and the reaction was carried out at room temperature for 23 h. After the reaction was completed, the mixture was filtered, washed and dried, and purified by column chromatography to obtain guanidinolated chitosan.

[0061] (5) 2.05 g of guanidinated chitosan was swollen in 24 mL of 3% acetic acid solution for 3 h, and then 1.67 g of stearic acid and 0.06 g of p-toluenesulfonic acid were added. The mixture was stirred at 58 °C for 8 h. After the reaction was completed, the mixture was filtered, washed and dried to obtain modified chitosan.

[0062] (6) 60 parts by weight of carboxylated polyester resin, 11 parts by weight of triglycidyl isocyanurate, 5 parts by weight of modified nano silica, 3 parts by weight of modified chitosan, 2 parts by weight of 2-(2H-benzotriazol-2-yl)-4,6-ditert-amylphenol, 1.5 parts by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 9 parts by weight of flake aluminum powder, 5 parts by weight of zinc phosphate, 1 part by weight of BYK-392, 0.5 parts by weight of 2-hydroxy-1,2-diphenyl ethyl ketone, and 0.3 parts by weight of γ-aminopropyltriethoxysilane were stirred and mixed at 340 rpm for 15 min at room temperature to obtain a mixture. The mixture was extruded through a twin-screw extruder at an extrusion temperature of 118°C and a screw speed of 500 rpm. After grinding, a single-layer UV-resistant heavy-duty anti-corrosion powder coating was obtained.

[0063] Comparative Example 1

[0064] The difference between this comparative example and Example 5 is that nano-silica was used instead of modified nano-silica.

[0065] Comparative Example 2

[0066] The difference between this comparative example and Example 5 is that chitosan was used instead of modified chitosan.

[0067] Performance testing:

[0068] The powder coatings prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to performance tests.

[0069] Coating preparation: Seven pieces of plywood, each measuring 100mm × 100mm × 5mm, were used as substrates and placed in a forced-air drying oven. They were dried at 60℃ for 2 hours. The powder coatings prepared in Examples 1-5 and Comparative Examples 1-2 were then evenly brushed onto the plywood surface three times, with an interval of approximately 10 minutes between each application. The coatings were then dried at room temperature for 24 hours. The final thickness of the dried composite coating on the plywood surface should reach 0.5mm ± 0.001mm.

[0070] UV resistance aging test: The UV resistance of epoxy resin coatings was tested according to GB / T14522-93 "Coatings and Paints - UV Resistance Test Method for Epoxy Coatings". Detailed procedures are as follows: Place the coated and dried plywood into a UV aging test chamber, ensuring the plywood surface receives uniform UV radiation. The UV radiation intensity should be controlled at 0.35 W / m². 2 Up to 0.55W / m 2 The temperature was set at (60±3)℃, the relative humidity at (65±5)%, and the test duration was 800h. The gloss changes of the coating were recorded, and the test results are shown in Table 1.

[0071] Table 1: UV aging resistance test.

[0072]

[0073] As can be seen from Table 1, the powder coatings prepared in Examples 1-5 have better resistance to ultraviolet aging than the powder coatings prepared in Comparative Examples 1-2.

[0074] (2) Corrosion resistance test: The corrosion resistance of the prepared plywood coating was tested under the following conditions: immersion in 20% sulfuric acid, immersion in 20% sodium hydroxide, and salt spray test in 5% sodium chloride. The test results are shown in Table 2.

[0075] Table 2: Corrosion resistance test.

[0076]

[0077] As can be seen from Table 2, the powder coatings prepared in Examples 1-5 have better anti-corrosion properties than the powder coatings prepared in Comparative Examples 1-2.

[0078] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0079] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0080] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A single-layer UV-resistant heavy-duty anti-corrosion powder coating, characterized in that, It comprises the following components by weight: 55-60 parts by weight of carboxylated polyester resin, 8-12 parts by weight of triglycidyl isocyanurate, 3-5 parts by weight of modified nano-silica, 2-4 parts by weight of modified chitosan, 1-2 parts by weight of 2-(2H-benzotriazol-2-yl)-4,6-ditert-pentylphenol, 1-1.5 parts by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 8-10 parts by weight of flake aluminum powder, 3-6 parts by weight of zinc phosphate, 0.6-1 parts by weight of BYK-392, 0.3-0.5 parts by weight of 2-hydroxy-1,2-diphenyl ethyl ketone, and 0.2-0.3 parts by weight of γ-aminopropyltriethoxysilane. The method for preparing the modified nano-silica is as follows: Step 1: Add 2-(2,4-dihydroxyphenyl)-2H-benzotriazole and 3-mercaptopropionic acid to tetrahydrofuran solvent, stir and mix, then add p-toluenesulfonic acid, and react at 65-75℃ for 6-8 hours. After the reaction is completed, wash and dry, purify, and obtain intermediate 1. Step 2: Under nitrogen protection, add intermediate 1 and vinyltriethoxysilane to N,N-dimethylformamide solvent, stir and disperse, then add benzoin dimethyl ether photoinitiator, and irradiate with 365nm ultraviolet light at 30-45℃ for 3-4 hours. After the irradiation, centrifuge, wash and dry to obtain intermediate 2. Step 3: Disperse nano-silica in deionized water and sonicate at 55-60℃ for 20-30 min. Then add intermediate 2, stir and mix, and continue the reaction for 3-4 h. After the reaction is complete, centrifuge, filter, and dry to obtain modified nano-silica.

2. The single-layer UV-resistant heavy-duty anti-corrosion powder coating according to claim 1, characterized in that, In step one, the ratio of tetrahydrofuran, 2-(2,4-dihydroxyphenyl)-2H-benzotriazole, 3-mercaptopropionic acid, and p-toluenesulfonic acid is 40-50 mL: 2.25-2.28 g: 1.06-1.08 g: 0.04-0.05 g.

3. The single-layer UV-resistant heavy-duty anti-corrosion powder coating according to claim 1, characterized in that, In step two, the ratio of N,N-dimethylformamide, intermediate 1, vinyltriethoxysilane, and benzoin dimethyl ether is 22-25 mL: 2.14-2.18 g: 2.41-2.45 g: 0.03-0.05 g.

4. The single-layer UV-resistant heavy-duty anti-corrosion powder coating according to claim 1, characterized in that, In step three, the ratio of nano-silica, deionized water, and intermediate 2 is 3.62-3.66g: 28-30mL: 2.32-2.38g.

5. The single-layer UV-resistant heavy-duty anti-corrosion powder coating according to claim 1, characterized in that, The modified chitosan is prepared by: S1: Chitosan was swollen in a 3% acetic acid solution for 1-2 hours, and then N,N-diisopropylethylamine and pyrazole-1-formamidin were added. The mixture was stirred and stirred, and the reaction was carried out at room temperature for 20-24 hours. After the reaction was completed, the mixture was filtered, washed and dried, and purified by column chromatography to obtain guanidinolated chitosan. S2: Guanidyl-modified chitosan was swollen in a 3% acetic acid solution for 2-3 hours, then stearic acid and p-toluenesulfonic acid were added, and the mixture was stirred at 50-60℃ for 5-8 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain modified chitosan.

6. The single-layer UV-resistant heavy-duty anti-corrosion powder coating according to claim 5, characterized in that, The ratio of chitosan, acetic acid solution with a mass fraction of 3%, N,N-diisopropylethylamine, and pyrazole-1-formamidin in S1 is 1.12-1.15g:18-20mL:4.32-4.36mL:3.83-3.87g.

7. The single-layer UV-resistant heavy-duty anti-corrosion powder coating according to claim 5, characterized in that, The ratio of guanidinated chitosan, acetic acid, stearic acid, and p-toluenesulfonic acid in S2 is 2.03-2.05g: 22-25mL: 1.65-1.68g: 0.04-0.06g.

8. A method for preparing a single-layer UV-resistant heavy-duty anti-corrosion powder coating as described in any one of claims 1-7, characterized in that, The preparation method of the single-layer UV-resistant heavy-duty anti-corrosion powder coating is as follows: carboxylated polyester resin, triglycidyl isocyanurate, modified nano silica, modified chitosan, 2-(2H-benzotriazol-2-yl)-4,6-di-tert-amylphenol, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, flake aluminum powder, zinc phosphate, BYK-392, 2-hydroxy-1,2-diphenyl ethyl ketone, and γ-aminopropyltriethoxysilane are stirred and mixed at 300-350 rpm for 10-15 min at room temperature to obtain a mixture. The mixture is then extruded through a twin-screw extruder at an extrusion temperature of 110-120℃ and a screw speed of 450-500 rpm. After grinding, a single-layer UV-resistant heavy-duty anti-corrosion powder coating is obtained.

9. The application of a single-layer UV-resistant heavy-duty anti-corrosion powder coating as described in any one of claims 1-7, characterized in that, Application of the single-layer UV-resistant heavy-duty anti-corrosion powder coating in the protection of metal substrates.

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