A high-hardness anti-corrosion powder coating and its preparation method

Abstract

This invention relates to the field of coating technology, and proposes a high-hardness anti-corrosion powder coating and its preparation method. This high-hardness anti-corrosion powder coating is composed of the following raw materials in parts by weight: 80-100 parts bisphenol A epoxy resin, 200-220 parts polyester resin, 20-24 parts curing agent, 10-12 parts leveling agent, 5-7 parts dispersant, 34-38 parts modified nano-silica, 5-7 parts benzoin, and 3-4 parts titanium dioxide. The preparation method of this coating is also provided. Through the above technical solution, by optimizing the coating component ratio and preparation process, the hardness, wear resistance, and adhesion of the coating are significantly improved, meeting the market demand for high-performance coatings. It has broad application prospects in high-end equipment manufacturing and other fields, providing strong support for promoting the development of related industries.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a high-hardness anti-corrosion powder coating and its preparation method. Background Technology

[0002] High-hardness anti-corrosion powder coatings are widely used in various fields such as automotive parts, shipbuilding, and electronic products due to their excellent adhesion and mechanical properties. However, traditional epoxy powder coatings still have shortcomings in terms of hardness, making it difficult to meet the high-hardness requirements of some specific applications. This has prompted us to continuously explore new technologies and methods to develop high-hardness anti-corrosion powder coatings with even better performance.

[0003] How to reduce production costs and enhance market competitiveness while ensuring coating performance has become a pressing issue for the coating industry. In terms of technological development trends, the coating industry is constantly seeking innovative breakthroughs. By optimizing resin systems, improving curing agent formulations, and adding special hardening fillers, key performance indicators of coatings, such as hardness and abrasion resistance, have been significantly improved. Simultaneously, with the continuous development of cutting-edge technologies such as nanotechnology and smart materials, the coating industry is also actively exploring the application of these new technologies in coating products to develop coating products with more functional and intelligent features.

[0004] Specifically, in the field of high-hardness anti-corrosion powder coatings, the market prospects and application potential are vast. In the automotive parts industry, high-hardness coatings can improve the impact resistance and aesthetics of parts; in the shipbuilding industry, high-hardness anti-corrosion powder coatings are indispensable protective materials. Furthermore, with the widespread use of electronic products and consumers' increasing focus on product quality, the application of high-hardness coatings in the electronic product field will gradually increase. Based on this, this invention proposes a novel high-hardness anti-corrosion powder coating and its preparation method. Summary of the Invention

[0005] This invention proposes a high-hardness anti-corrosion powder coating and its preparation method, which solves the problem that epoxy powder coatings in related technologies still have shortcomings in terms of hardness and wear resistance, and also makes the coating have both adhesion and aesthetics.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention proposes a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 80-100 parts of bisphenol A epoxy resin, 200-220 parts of polyester resin, 20-24 parts of curing agent, 10-12 parts of leveling agent, 5-7 parts of dispersant, 34-38 parts of modified nano silica, 5-7 parts of benzoin, and 3-4 parts of titanium dioxide.

[0008] As a further technical solution, the bisphenol A epoxy resin has an epoxy equivalent of 420-440 g / mol and a softening point of 65-75℃.

[0009] As a further technical solution, the polyester resin has a solid content of 45wt%-55wt%, an acid value of 62-68mgKOH / g, a melt viscosity of 7800-8000mPa·s at 200℃, and a glass transition temperature of 45-55℃.

[0010] The “acid value” refers to the number of milligrams of potassium hydroxide required to neutralize the free acid in 1 gram of resin. The glass transition temperature can be determined by dynamic thermomechanical analysis (DMA) using a TA Instruments Q800 instrument with the following parameters: frequency 10 Hz, amplitude 5 mm, temperature ramp -100℃ to 250℃, and Tg determined as the peak value of the tanδ curve according to ASTM D7028.

[0011] As a further technical solution, the polyester resin comprises the following raw materials in parts by weight: 30-34 parts of 1,6-hexanediol, 50-54 parts of isophthalic acid, 1-1.2 parts of silane coupling agent KH560, 8-15 parts of adipic acid, 0.05-0.15 parts of dihydroxybutyltin chloride, and 0.03-0.06 parts of tetraethylammonium bromide.

[0012] As a further technical solution, the preparation method of the polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 260-265℃ at a rate of 3-4℃ / min in a nitrogen atmosphere and holding at the temperature, adding adipic acid when the acid value reaches 25-30mgKOH / g and performing acid desealing at a temperature of 245-255℃; when the acid value of the polyester resin reaches 74-80mgKOH / g, cooling to 215-225℃ at a rate of 1-2℃ / min and performing polycondensation at -0.1MPa to achieve an acid value of 62-68mgKOH / g; then cooling to 190-200℃, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 15-25min to obtain the final product.

[0013] As a further technical solution, the curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant includes at least one of BYK-163, 5040, and BYK-194.

[0014] As a further technical solution, the preparation method of the modified nano-silica includes: dissolving the nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing it for 10-15 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 30-40 min, adding styrene at a temperature of 85-90℃, continuing the reaction for 9-10 h, and then purifying to obtain the final product.

[0015] As a further technical solution, the method for treating the nano-silica with the silane coupling agent is as follows: the nano-silica is placed in a constant temperature drying oven at 100℃ and dried until its weight no longer changes. The dried silica is added to a 95% ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred and reacted at 65℃-75℃ for 4-6 hours. After centrifugation, washing, and drying, the product is obtained.

[0016] As a further technical solution, the weight ratio of the nano-silica, ethanol solution and γ-glycidoxypropyltrimethoxysilane is (8-10):(100-120):(0.25-0.35).

[0017] As a further technical solution, the purification method is as follows: the dried product is extracted with ethanol for 2-3 hours, with methanol for 4-6 hours, and with acetone for 15-17 hours, and then vacuum dried at 60-70°C.

[0018] Secondly, this invention proposes a method for preparing a high-hardness anti-corrosion powder coating, the steps of which include:

[0019] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 110-116℃ and the extruder screw temperature is 84-90℃;

[0020] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 135-145℃ and the extruder screw temperature is 90-100℃. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0021] The working principle and beneficial effects of this invention are as follows:

[0022] 1. In this invention, the bisphenol A epoxy resin has an epoxy equivalent of 420-440 g / mol and a softening point of 65-75℃. The appropriate epoxy equivalent and the appropriate softening point work together to give the cured coating higher hardness and wear resistance, and it can resist external mechanical wear and scratches.

[0023] 2. In this invention, the polyester resin has specific solid content, acid value, melt viscosity and glass transition temperature. The precise control of these performance parameters enables the polyester resin to form good compatibility and interfacial bonding with the base materials such as bisphenol A epoxy resin, thereby enhancing the adhesion of the coating.

[0024] 3. In this invention, the nano-silica treated with a silane coupling agent is further modified to form a nano-silica core-shell structure. This significantly improves the hardness and wear resistance of epoxy powder coatings, as well as their adhesion and aesthetics. Due to its inherent properties, nano-silica particles have extremely small particle size and high specific surface area, enabling them to form uniformly dispersed nanoscale structures in coatings. This nanostructure significantly enhances the hardness and wear resistance of coatings because the nanoparticles fill the tiny pores and defects in the coating, forming a denser and more robust coating structure.

[0025] 4. Through treatment with silane coupling agents, the surface of nano-silica is coated with organic groups, forming a core-shell structure. This structure not only improves the compatibility between nanoparticles and organic resins but also enhances the stability and dispersibility of nanoparticles in the coating. The organic shell layer in the core-shell structure increases the interaction force between nanoparticles and the resin matrix, thereby improving the hardness and wear resistance of the coating. The organic groups formed on the surface of nano-silica by the silane coupling agent can chemically react with the functional groups in the resin matrix to form chemical bonds. These chemical bonds increase the crosslinking density of the coating, further improving hardness and wear resistance.

[0026] 5. The good compatibility of bisphenol A epoxy resin with polyester resin and other base materials in this invention, combined with the modifying effect of silane coupling agent on inorganic nanoparticles, results in better dispersibility of modified nano-silica and titanium dioxide raw materials in the coating, preventing the aggregation and precipitation of nanoparticles. This good dispersibility helps to form a smooth and flat coating surface, improving the aesthetics of the coating and ensuring a strong bond between the coating and the substrate. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] This embodiment provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 90 parts of bisphenol A epoxy resin, 210 parts of polyester resin, 22 parts of curing agent, 11 parts of leveling agent, 6 parts of dispersant, 36 parts of modified nano silica, 6 parts of benzoin, and 3.5 parts of titanium dioxide.

[0030] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-163.

[0031] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 430 g / mol and a softening point of 70℃; the polyester resin has a solid content of 50 wt%, an acid value of 65 mgKOH / g, a melt viscosity of 7900 mPa·s at 200℃, and a glass transition temperature of 50℃.

[0032] The polyester resin comprises the following raw materials in parts by weight: 32 parts of 1,6-hexanediol, 52 parts of isophthalic acid, 1.1 parts of silane coupling agent KH560, 11 parts of adipic acid, 0.1 parts of dihydroxybutyltin chloride, and 0.05 parts of tetraethylammonium bromide.

[0033] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 262°C at a rate of 3.5°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 27 mgKOH / g and performing acid desealing at a temperature of 250°C; when the acid value of the polyester resin reaches 77 mgKOH / g, cooling to 220°C at a rate of 1.5°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 65 mgKOH / g; then cooling to 195°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 20 min to obtain the final product;

[0034] The preparation method of modified nano-silica includes: dissolving nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing for 12 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 35 min, then adding styrene at a temperature of 87℃, and continuing the reaction for 9.5 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 2.5 h, extracting with methanol for 5 h, and extracting with acetone for 16 h, followed by vacuum drying at 65℃;

[0035] The method for treating nano-silica with silane coupling agent is as follows: nano-silica is dried in a constant temperature drying oven at 100℃ until its weight no longer changes. The dried silica is added to a 95% ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred at 70℃ for 5 hours, centrifuged, washed, and dried to obtain the final product. The weight ratio of nano-silica, ethanol solution, and γ-glycidoxypropyltrimethoxysilane is 9:110:0.3.

[0036] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0037] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 113℃ and the extruder screw temperature is 87℃;

[0038] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 140°C and the extruder screw temperature is 95°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0039] Example 2

[0040] This embodiment provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 80 parts of bisphenol A epoxy resin, 200 parts of polyester resin, 20 parts of curing agent, 10 parts of leveling agent, 5 parts of dispersant, 34 parts of modified nano silica, 5 parts of benzoin, and 3 parts of titanium dioxide.

[0041] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-163.

[0042] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 420 g / mol and a softening point of 65℃; the polyester resin has a solid content of 45 wt%, an acid value of 62 mg KOH / g, a melt viscosity of 7800 mmPa·s at 200℃, and a glass transition temperature of 45℃.

[0043] The polyester resin comprises the following raw materials in parts by weight: 30 parts of 1,6-hexanediol, 50 parts of isophthalic acid, 1 part of silane coupling agent KH560, 8 parts of adipic acid, 0.05 parts of dihydroxybutyltin chloride, and 0.03 parts of tetraethylammonium bromide.

[0044] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 260°C at a rate of 3°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 25 mgKOH / g and performing acid desealing at a temperature of 245°C; when the acid value of the polyester resin reaches 74 mgKOH / g, cooling to 215°C at a rate of 1°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 62 mgKOH / g; then cooling to 190°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 15 min to obtain the final product;

[0045] The preparation method of modified nano-silica includes: dissolving nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing it for 10 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 30 min, adding styrene at a temperature of 85℃, and continuing the reaction for 9 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 2 h, extracting with methanol for 4 h, and extracting with acetone for 15 h, followed by vacuum drying at 60℃;

[0046] The method for treating nano-silica with silane coupling agent is as follows: Nano-silica is dried in a 100℃ constant temperature drying oven until its weight no longer changes. The dried silica is then added to a 95% (w / w) ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred at 65℃ for 4 hours, centrifuged, washed, and dried to obtain the final product. The weight ratio of nano-silica, ethanol solution, and γ-glycidoxypropyltrimethoxysilane is 8:100:0.25.

[0047] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0048] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 110℃ and the extruder screw temperature is 84℃;

[0049] (2) After crushing the first tablet, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 135°C and the extruder screw temperature is 90°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to form a powder coating.

[0050] Example 3

[0051] This embodiment provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 220 parts of polyester resin, 24 parts of curing agent, 12 parts of leveling agent, 7 parts of dispersant, 38 parts of modified nano silica, 7 parts of benzoin, and 4 parts of titanium dioxide.

[0052] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is 5040.

[0053] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 440 g / mol and a softening point of 75℃; the polyester resin has a solid content of 55 wt%, an acid value of 68 mgKOH / g, a melt viscosity of 8000 mmPa·s at 200℃, and a glass transition temperature of 55℃.

[0054] The polyester resin comprises the following raw materials in parts by weight: 34 parts of 1,6-hexanediol, 54 parts of isophthalic acid, 1.2 parts of silane coupling agent KH560, 15 parts of adipic acid, 0.15 parts of dihydroxybutyltin chloride, and 0.06 parts of tetraethylammonium bromide.

[0055] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 265°C at a rate of 4°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 30 mg KOH / g and performing acid desealing at a temperature of 255°C; when the acid value of the polyester resin reaches 80 mg KOH / g, cooling to 225°C at a rate of 2°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 68 mg KOH / g; then cooling to 200°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 25 min to obtain the final product;

[0056] The preparation method of modified nano-silica includes: dissolving nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing it for 15 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 40 min, adding styrene at a temperature of 90℃, and continuing the reaction for 10 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 3 h, extracting with methanol for 6 h, and extracting with acetone for 17 h, followed by vacuum drying at 70℃;

[0057] The method for treating nano-silica with silane coupling agent is as follows: Nano-silica is dried in a 100℃ constant temperature drying oven until its weight no longer changes. The dried silica is then added to a 95% (w / w) ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred at 75℃ for 6 hours, centrifuged, washed, and dried to obtain the final product. The weight ratio of nano-silica, ethanol solution, and γ-glycidoxypropyltrimethoxysilane is 10:120:0.35.

[0058] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0059] (1) Weigh the raw materials according to the proportion, and mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin evenly in a high-speed mixer; extrude the first tablet using a twin-screw extruder, with the extruder barrel temperature at 116°C and the extruder screw temperature at 90°C.

[0060] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 145°C and the extruder screw temperature is 100°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0061] Example 4

[0062] This embodiment provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 200 parts of polyester resin, 24 parts of curing agent, 10 parts of leveling agent, 7 parts of dispersant, 34 parts of modified nano silica, 7 parts of benzoin, and 3 parts of titanium dioxide.

[0063] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-194.

[0064] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 440 g / mol and a softening point of 65℃; the polyester resin has a solid content of 55 wt%, an acid value of 62 mgKOH / g, a melt viscosity of 8000 mmPa·s at 200℃, and a glass transition temperature of 45℃.

[0065] The polyester resin comprises the following raw materials in parts by weight: 34 parts of 1,6-hexanediol, 50 parts of isophthalic acid, 1.2 parts of silane coupling agent KH560, 8 parts of adipic acid, 0.15 parts of dihydroxybutyltin chloride, and 0.03 parts of tetraethylammonium bromide.

[0066] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 260°C at a rate of 4°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 30 mg KOH / g and performing acid desealing at a temperature of 245°C; when the acid value of the polyester resin reaches 80 mg KOH / g, cooling to 225°C at a rate of 1°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 62 mg KOH / g; then cooling to 200°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 15 min to obtain the final product;

[0067] The preparation method of modified nano-silica includes: dissolving nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing it for 10 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 40 min, adding styrene at a temperature of 85℃, and continuing the reaction for 10 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 2 h, extracting with methanol for 6 h, and extracting with acetone for 15 h, followed by vacuum drying at 70℃;

[0068] The method for treating nano-silica with silane coupling agent is as follows: Nano-silica is dried in a 100℃ constant temperature drying oven until its weight no longer changes. The dried silica is then added to a 95% (w / w) ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred at 75℃ for 4 hours, centrifuged, washed, and dried to obtain the final product. The weight ratio of nano-silica, ethanol solution, and γ-glycidoxypropyltrimethoxysilane is 10:100:0.35.

[0069] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0070] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 110℃ and the extruder screw temperature is 90℃;

[0071] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 135°C and the extruder screw temperature is 100°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0072] Comparative Example 1

[0073] This comparative example provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 90 parts of bisphenol A epoxy resin, 210 parts of polyester resin, 22 parts of curing agent, 11 parts of leveling agent, 6 parts of dispersant, 36 parts of modified nano silica, 6 parts of benzoin, and 3.5 parts of titanium dioxide.

[0074] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-163.

[0075] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 500 g / mol and a softening point of 80℃; the polyester resin has a solid content of 50 wt%, an acid value of 65 mgKOH / g, a melt viscosity of 7900 mmPa·s at 200℃, and a glass transition temperature of 50℃.

[0076] The polyester resin comprises the following raw materials in parts by weight: 32 parts of 1,6-hexanediol, 52 parts of isophthalic acid, 1.1 parts of silane coupling agent KH560, 11 parts of adipic acid, 0.1 parts of dihydroxybutyltin chloride, and 0.05 parts of tetraethylammonium bromide.

[0077] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 262°C at a rate of 3.5°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 27 mgKOH / g and performing acid desealing at a temperature of 250°C; when the acid value of the polyester resin reaches 77 mgKOH / g, cooling to 220°C at a rate of 1.5°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 65 mgKOH / g; then cooling to 195°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 20 min to obtain the final product;

[0078] The preparation method of modified nano-silica includes: dissolving nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing it for 12 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 35 min, adding styrene at a temperature of 87℃, and continuing the reaction for 9.5 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 2.5 h, extracting with methanol for 5 h, and extracting with acetone for 16 h, followed by vacuum drying at 65℃;

[0079] The method for treating nano-silica with silane coupling agent is as follows: Nano-silica is dried in a 100℃ constant temperature drying oven until its weight no longer changes. The dried silica is then added to a 95% (w / w) ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred at 70℃ for 5 hours, centrifuged, washed, and dried to obtain the final product. The weight ratio of nano-silica, ethanol solution, and γ-glycidoxypropyltrimethoxysilane is 9:110:0.3.

[0080] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0081] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 113℃ and the extruder screw temperature is 87℃;

[0082] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 140°C and the extruder screw temperature is 95°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0083] Comparative Example 2

[0084] This comparative example provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 90 parts of bisphenol A epoxy resin, 210 parts of polyester resin, 22 parts of curing agent, 11 parts of leveling agent, 6 parts of dispersant, 36 parts of modified nano silica, 6 parts of benzoin, and 3.5 parts of titanium dioxide.

[0085] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-163.

[0086] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 430 g / mol and a softening point of 70℃; the polyester resin has a solid content of 60 wt%, an acid value of 75 mgKOH / g, a melt viscosity of 7000 mPa·s at 200℃, and a glass transition temperature of 60℃.

[0087] The polyester resin comprises the following raw materials in parts by weight: 32 parts of 1,6-hexanediol, 52 parts of isophthalic acid, 1.1 parts of silane coupling agent KH560, 11 parts of adipic acid, 0.1 parts of dihydroxybutyltin chloride, and 0.05 parts of tetraethylammonium bromide.

[0088] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 262°C at a rate of 3.5°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 27 mgKOH / g and performing acid desealing at a temperature of 250°C; when the acid value of the polyester resin reaches 77 mgKOH / g, cooling to 220°C at a rate of 1.5°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 75 mgKOH / g; then cooling to 195°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 20 min to obtain the final product;

[0089] The preparation method of modified nano-silica includes: dissolving nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing it for 12 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 35 min, adding styrene at a temperature of 87℃, and continuing the reaction for 9.5 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 2.5 h, extracting with methanol for 5 h, and extracting with acetone for 16 h, followed by vacuum drying at 65℃;

[0090] The method for treating nano-silica with silane coupling agent is as follows: Nano-silica is dried in a 100℃ constant temperature drying oven until its weight no longer changes. The dried silica is then added to a 95% (w / w) ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred at 70℃ for 5 hours, centrifuged, washed, and dried to obtain the final product. The weight ratio of nano-silica, ethanol solution, and γ-glycidoxypropyltrimethoxysilane is 9:110:0.3.

[0091] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0092] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 113℃ and the extruder screw temperature is 87℃;

[0093] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 140°C and the extruder screw temperature is 95°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0094] Comparative Example 3

[0095] This comparative example provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 90 parts of bisphenol A epoxy resin, 210 parts of polyester resin, 22 parts of curing agent, 11 parts of leveling agent, 6 parts of dispersant, 36 parts of modified nano silica, 6 parts of benzoin, and 3.5 parts of titanium dioxide.

[0096] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-163.

[0097] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 430 g / mol and a softening point of 70℃; the polyester resin has a solid content of 60 wt%, an acid value of 65 mgKOH / g, a melt viscosity of 7500 mmPa·s at 200℃, and a glass transition temperature of 40℃.

[0098] The polyester resin comprises the following raw materials in parts by weight: 32 parts of 1,6-hexanediol, 52 parts of isophthalic acid, 1.1 parts of silane coupling agent KH560, 11 parts of adipic acid, 0.1 parts of dihydroxybutyltin chloride, and 0.045 parts of tetraethylammonium bromide.

[0099] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 262°C at a rate of 3.5°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 27 mgKOH / g and performing acid desealing at a temperature of 250°C; when the acid value of the polyester resin reaches 77 mgKOH / g, cooling to 220°C at a rate of 1.5°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 65 mgKOH / g; then cooling to 195°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 20 min to obtain the final product;

[0100] The preparation method of modified nano-silica includes: dissolving nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing it for 12 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 35 min, adding styrene at a temperature of 87℃, and continuing the reaction for 9.5 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 2.5 h, extracting with methanol for 5 h, and extracting with acetone for 16 h, followed by vacuum drying at 65℃;

[0101] The method for treating nano-silica with silane coupling agent is as follows: Nano-silica is dried in a 100℃ constant temperature drying oven until its weight no longer changes. The dried silica is then added to a 95% (w / w) ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred at 70℃ for 5 hours, centrifuged, washed, and dried to obtain the final product. The weight ratio of nano-silica, ethanol solution, and γ-glycidoxypropyltrimethoxysilane is 9:110:0.3.

[0102] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0103] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 113℃ and the extruder screw temperature is 87℃;

[0104] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 140°C and the extruder screw temperature is 95°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0105] Comparative Example 4

[0106] This comparative example provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 90 parts of bisphenol A epoxy resin, 210 parts of polyester resin, 22 parts of curing agent, 11 parts of leveling agent, 6 parts of dispersant, 36 parts of modified nano silica, 6 parts of benzoin, and 3.5 parts of titanium dioxide.

[0107] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-163.

[0108] Among them, the epoxy equivalent of bisphenol A epoxy resin is 430 g / mol, and the softening point is 70℃;

[0109] The polyester resin is a commercially available polyester resin, model HR-8309C, and the preferred manufacturer is Changzhou Huarun Composite Materials Co., Ltd.

[0110] The preparation method of modified nano-silica includes: dissolving nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing it for 12 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 35 min, adding styrene at a temperature of 87℃, and continuing the reaction for 9.5 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 2.5 h, extracting with methanol for 5 h, and extracting with acetone for 16 h, followed by vacuum drying at 65℃;

[0111] The method for treating nano-silica with silane coupling agent is as follows: Nano-silica is dried in a 100℃ constant temperature drying oven until its weight no longer changes. The dried silica is then added to a 95% (w / w) ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred at 70℃ for 5 hours, centrifuged, washed, and dried to obtain the final product. The weight ratio of nano-silica, ethanol solution, and γ-glycidoxypropyltrimethoxysilane is 9:110:0.3.

[0112] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0113] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 113℃ and the extruder screw temperature is 87℃;

[0114] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 140°C and the extruder screw temperature is 95°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0115] Comparative Example 5

[0116] This comparative example provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 90 parts of bisphenol A epoxy resin, 210 parts of polyester resin, 22 parts of curing agent, 11 parts of leveling agent, 6 parts of dispersant, 36 parts of modified nano silica, 6 parts of benzoin, and 3.5 parts of titanium dioxide.

[0117] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-163.

[0118] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 430 g / mol and a softening point of 70℃; the polyester resin has a solid content of 50 wt%, an acid value of 65 mgKOH / g, a melt viscosity of 7900 mmPa·s at 200℃, and a glass transition temperature of 50℃.

[0119] The polyester resin comprises the following raw materials in parts by weight: 32 parts of 1,6-hexanediol, 52 parts of isophthalic acid, 1.1 parts of silane coupling agent KH560, 11 parts of adipic acid, 0.1 parts of dihydroxybutyltin chloride, and 0.05 parts of tetraethylammonium bromide.

[0120] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 262°C at a rate of 3.5°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 27 mgKOH / g and performing acid desealing at a temperature of 250°C; when the acid value of the polyester resin reaches 77 mgKOH / g, cooling to 220°C at a rate of 1.5°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 65 mgKOH / g; then cooling to 195°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 20 min to obtain the final product;

[0121] The preparation method of modified nano-silica includes: dissolving nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing it for 12 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 35 min, adding styrene at a temperature of 87℃, and continuing the reaction for 9.5 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 2.5 h, extracting with methanol for 5 h, and extracting with acetone for 16 h, followed by vacuum drying at 65℃;

[0122] The method for treating nano-silica with silane coupling agent is as follows: nano-silica is added to a 95% (w / w) ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred at 70°C for 5 hours, centrifuged, washed, and dried to obtain the final product. The weight ratio of nano-silica, ethanol solution, and γ-glycidoxypropyltrimethoxysilane is 9:110:0.3.

[0123] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0124] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 113℃ and the extruder screw temperature is 87℃;

[0125] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 140°C and the extruder screw temperature is 95°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0126] Comparative Example 6

[0127] This comparative example provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 90 parts of bisphenol A epoxy resin, 210 parts of polyester resin, 22 parts of curing agent, 11 parts of leveling agent, 6 parts of dispersant, 36 parts of modified nano silica, 6 parts of benzoin, and 3.5 parts of titanium dioxide.

[0128] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-163.

[0129] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 430 g / mol and a softening point of 70℃; the polyester resin has a solid content of 50 wt%, an acid value of 65 mgKOH / g, a melt viscosity of 7900 mmPa·s at 200℃, and a glass transition temperature of 50℃.

[0130] The polyester resin comprises the following raw materials in parts by weight: 32 parts of 1,6-hexanediol, 52 parts of isophthalic acid, 1.1 parts of silane coupling agent KH560, 11 parts of adipic acid, 0.1 parts of dihydroxybutyltin chloride, and 0.045 parts of tetraethylammonium bromide.

[0131] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 262°C at a rate of 3.5°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 27 mgKOH / g and performing acid desealing at a temperature of 250°C; when the acid value of the polyester resin reaches 77 mgKOH / g, cooling to 220°C at a rate of 1.5°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 65 mgKOH / g; then cooling to 195°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 20 min to obtain the final product;

[0132] The preparation method of modified nano-silica includes: drying nano-silica in a constant temperature drying oven at 100℃ until its weight no longer changes; adding the dried silica to a 95% ethanol solution; ultrasonically dispersing the silica; adding γ-glycidoxypropyltrimethoxysilane; stirring and reacting at 70℃ for 5 hours; centrifuging; washing; and drying to obtain the modified nano-silica; the weight ratio of nano-silica, ethanol solution, and γ-glycidoxypropyltrimethoxysilane is 9:110:0.3.

[0133] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0134] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 113℃ and the extruder screw temperature is 87℃;

[0135] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 140°C and the extruder screw temperature is 95°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0136] Comparative Example 7

[0137] This comparative example provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 90 parts of bisphenol A epoxy resin, 210 parts of polyester resin, 22 parts of curing agent, 11 parts of leveling agent, 6 parts of dispersant, 36 parts of modified nano silica, 6 parts of benzoin, and 3.5 parts of titanium dioxide.

[0138] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-163.

[0139] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 430 g / mol and a softening point of 70℃; the polyester resin has a solid content of 50 wt%, an acid value of 65 mgKOH / g, a melt viscosity of 7900 mmPa·s at 200℃, and a glass transition temperature of 50℃.

[0140] The polyester resin comprises the following raw materials in parts by weight: 32 parts of 1,6-hexanediol, 52 parts of isophthalic acid, 1.1 parts of silane coupling agent KH560, 11 parts of adipic acid, 0.1 parts of dihydroxybutyltin chloride, and 0.045 parts of tetraethylammonium bromide.

[0141] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 262°C at a rate of 3.5°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 27 mgKOH / g and performing acid desealing at a temperature of 250°C; when the acid value of the polyester resin reaches 77 mgKOH / g, cooling to 220°C at a rate of 1.5°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 65 mgKOH / g; then cooling to 195°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 20 min to obtain the final product;

[0142] The preparation method of modified nano-silica includes: dissolving nano-silica treated with silane coupling agent in deionized water and ultrasonically dispersing it for 12 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 35 min, adding styrene at a temperature of 87℃, and continuing the reaction for 9.5 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 2.5 h, extracting with methanol for 5 h, and extracting with acetone for 16 h, followed by vacuum drying at 65℃;

[0143] The method for treating nano-silica with silane coupling agent is as follows: Nano-silica is dried in a 100℃ constant temperature drying oven until its weight no longer changes. The dried silica is then added to a 95% (w / w) ethanol solution, ultrasonically dispersed, and then γ-aminopropyltriethoxysilane is added. The mixture is stirred at 70℃ for 5 hours, centrifuged, washed, and dried to obtain the final product. The weight ratio of nano-silica, ethanol solution, and γ-aminopropyltriethoxysilane is 9:110:0.3.

[0144] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0145] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 113℃ and the extruder screw temperature is 87℃;

[0146] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 140°C and the extruder screw temperature is 95°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0147] Comparative Example 8

[0148] This comparative example provides a high-hardness anti-corrosion powder coating, which is composed of the following raw materials in parts by weight: 90 parts of bisphenol A epoxy resin, 210 parts of polyester resin, 22 parts of curing agent, 11 parts of leveling agent, 6 parts of dispersant, 36 parts of modified nano silica, 6 parts of benzoin, and 3.5 parts of titanium dioxide.

[0149] The curing agent is DyhardOTB; the leveling agent is BYK-307; and the dispersant is BYK-163.

[0150] Among them, the bisphenol A epoxy resin has an epoxy equivalent of 430 g / mol and a softening point of 70℃; the polyester resin has a solid content of 50 wt%, an acid value of 65 mgKOH / g, a melt viscosity of 7900 mmPa·s at 200℃, and a glass transition temperature of 50℃.

[0151] The polyester resin comprises the following raw materials in parts by weight: 32 parts of 1,6-hexanediol, 52 parts of isophthalic acid, 1.1 parts of silane coupling agent KH560, 11 parts of adipic acid, 0.1 parts of dihydroxybutyltin chloride, and 0.045 parts of tetraethylammonium bromide.

[0152] The preparation method of polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 262°C at a rate of 3.5°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 27 mgKOH / g and performing acid desealing at a temperature of 250°C; when the acid value of the polyester resin reaches 77 mgKOH / g, cooling to 220°C at a rate of 1.5°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 65 mgKOH / g; then cooling to 195°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 20 min to obtain the final product;

[0153] The preparation method of modified nano-silica includes: drying nano-silica in a constant temperature drying oven at 100℃ until its weight no longer changes, dissolving it in deionized water and ultrasonically dispersing it for 12 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring, stirring and dispersing for 35 min, adding styrene at 87℃, and continuing the reaction for 9.5 h, followed by purification; the purification method is as follows: extracting the dried product with ethanol for 2.5 h, extracting with methanol for 5 h, and extracting with acetone for 16 h, followed by vacuum drying at 65℃;

[0154] The preparation method of this high-hardness anti-corrosion powder coating includes the following steps:

[0155] (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin in a high-speed mixer; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 113℃ and the extruder screw temperature is 87℃;

[0156] (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 140°C and the extruder screw temperature is 95°C. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

[0157] Experimental Example 1: The powder coatings prepared in Examples 1-4 and Comparative Examples 1-8 were respectively sprayed onto ferrite magnetic rings preheated in an oven at 200℃ using high-voltage electrostatic spraying. The coating thickness was 100μm, the curing temperature was 200℃, and the curing time was 10min. The samples to be tested were obtained, and their performance was investigated. The prepared powder coatings were tested as follows:

[0158] Coating appearance: Visually inspect the appearance of the coating;

[0159] Pencil hardness: The hardness of the coating was determined according to the pencil test method (GB / T 6739-2022).

[0160] Resistance to nail scratching: Visually inspect the coating after scratching it with a nail.

[0161] Adhesion: Tested according to GB / T 9286-2021 standard. The results are judged in 5 levels: 0: The cut edge is completely smooth, with no cells peeling off; 1: A small amount of coating peels off at the intersection of cuts, but the affected area of ​​the intersection cannot be significantly greater than 5%; 2: The coating peels off at the intersection of cuts or the cut edge, and the affected area of ​​the intersection is significantly greater than 5% but less than 15%; 3: The coating peels off in large fragments along the cut edge, and on different parts of the cells, it peels off partially or completely, and the affected area of ​​the intersection is significantly greater than 15% but less than 35%; 4: The coating peels off in large fragments along the cut edge, and some cells peel off partially or completely, and the affected area of ​​the intersection is significantly greater than 35% but less than 65%; 5: The affected area of ​​the intersection is significantly greater than 65%.

[0162] Impact resistance test: The test was conducted according to GB / T1732-2020, and the average value was taken from three parallel tests.

[0163] The test results are shown in Table 1 below:

[0164] Table 1

[0165]

[0166] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-hardness anti-corrosion powder coating, characterized in that, It is composed of the following raw materials in parts by weight: 80-100 parts of bisphenol A epoxy resin, 200-220 parts of polyester resin, 20-24 parts of curing agent, 10-12 parts of leveling agent, 5-7 parts of dispersant, 34-38 parts of modified nano-silica, 5-7 parts of benzoin, and 3-4 parts of titanium dioxide; the bisphenol A epoxy resin has an epoxy equivalent of 420-440 g / mol and a softening point of 65-75℃; the polyester resin has a solid content of 45wt%-55wt%, an acid value of 62-68 mgKOH / g, a melt viscosity of 7800-8000 mPa·s at 200℃, and a glass transition temperature of 45-55℃; The preparation method of the polyester resin includes: mixing 1,6-hexanediol, isophthalic acid and dihydroxybutyltin chloride in the prescribed amounts, heating to 260-265°C at a rate of 3-4°C / min in a nitrogen atmosphere and holding at that temperature, adding adipic acid when the acid value reaches 25-30 mgKOH / g and performing acid desealing at a temperature of 245-255°C; when the acid value of the polyester resin reaches 74-80 mgKOH / g, cooling to 215-225°C at a rate of 1-2°C / min and performing polycondensation at -0.1 MPa to achieve an acid value of 62-68 mgKOH / g; then cooling to 190-200°C, adding tetraethylammonium bromide and silane coupling agent KH560 and maintaining for 15-25 min to obtain the final product; The method for preparing the modified nano-silica includes: dissolving the nano-silica treated with a silane coupling agent in deionized water and ultrasonically dispersing it for 10-15 min; adding emulsifier TX-10 and initiator benzoyl peroxide under stirring conditions, stirring and dispersing for 30-40 min, adding styrene at a temperature of 85-90℃, continuing the reaction for 9-10 h, and then purifying to obtain the product. The silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

2. The high-hardness anti-corrosion powder coating according to claim 1, characterized in that, The polyester resin comprises the following raw materials in parts by weight: 30-34 parts of 1,6-hexanediol, 50-54 parts of isophthalic acid, 1-1.2 parts of silane coupling agent KH560, 8-15 parts of adipic acid, 0.05-0.15 parts of dihydroxybutyltin chloride, and 0.03-0.06 parts of tetraethylammonium bromide.

3. The high-hardness anti-corrosion powder coating according to claim 1, characterized in that, The method for treating the nano-silica with the silane coupling agent is as follows: the nano-silica is placed in a constant temperature drying oven at 100℃ and dried until its weight no longer changes. The dried silica is added to a 95% ethanol solution, ultrasonically dispersed, and then γ-glycidoxypropyltrimethoxysilane is added. The mixture is stirred and reacted at 65℃-75℃ for 4-6 hours. After centrifugation, washing, and drying, the nano-silica is obtained.

4. The high-hardness anti-corrosion powder coating according to claim 3, characterized in that, The weight ratio of the nano-silica, ethanol solution and γ-glycidoxypropyltrimethoxysilane is (8-10):(100-120):(0.25-0.35).

5. A method for preparing a high-hardness anti-corrosion powder coating as described in any one of claims 1-4, characterized in that, step... include: (1) Weigh the raw materials according to the proportion, mix the bisphenol A epoxy resin, polyester resin, curing agent, leveling agent, dispersant and benzoin evenly; extrude the first tablet using a twin-screw extruder, the extruder barrel temperature is 110-116℃, and the extruder screw temperature is 84-90℃; (2) After the first tablet is crushed, it is mixed with modified nano silica and titanium dioxide and extruded again using a twin-screw extruder. The extruder barrel temperature is 135-145℃ and the extruder screw temperature is 90-100℃. The tablets are then crushed, ground, and passed through a 200-mesh sieve to make powder coating.

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