A method for preparing a high corrosion-resistant color-coated steel sheet

Abstract

This invention discloses a method for preparing a highly corrosion-resistant color-coated steel sheet, relating to the field of steel sheet coating technology. The invention first involves hot-dip galvanizing a steel substrate to form a zinc layer. Subsequently, a citric acid-based roughening modifier is used to treat the surface of the zinc layer. In the coating preparation, octenoic acid-modified epoxy resin is used as the matrix, combined with hexafunctional polyurethane acrylate, di-2-propylene 1,2-phthalic acid, and acrylic acid to constitute the main coating raw materials. An organosilicon emulsion containing multi-level fillers is introduced. The coating composition, including a curing agent, initiator, and additives, is then applied to the roughened zinc layer surface. Through the synergistic effect of interface roughening and multi-scale fillers, the coating achieves corrosion resistance and wear resistance.

Description

Technical Field

[0001] This invention relates to the field of steel plate coating technology, specifically to a method for preparing a high corrosion-resistant color-coated steel plate. Background Technology

[0002] Color-coated steel sheets, as a composite material combining decorative and protective properties, are widely used in construction, home appliances, and transportation due to their good processability, rich color performance, and certain corrosion resistance. Their conventional structure typically involves coating one or more layers of organic paint onto a substrate such as cold-rolled steel sheet, hot-dip galvanized steel sheet, or alloyed galvanized steel sheet after chemical pretreatment, followed by baking and curing. The coating not only provides rich colors and textures but, more importantly, acts as a physical barrier, preventing moisture, oxygen, and corrosive media from eroding the metal substrate, thereby extending the steel sheet's service life. For galvanized substrates, while the smooth zinc layer surface itself provides some sacrificial anode protection, its mechanical bonding with the organic coating is limited.

[0003] However, with increasingly harsh application environments and ever-increasing demands on product lifespan, existing color-coated steel sheets still exhibit some technical bottlenecks during long-term service. Firstly, the interfacial adhesion between the organic coating and the metal substrate is a critical issue. Insufficient adhesion can lead to blistering and peeling of the coating under mechanical stress, temperature and humidity changes, or the penetration of corrosive media, resulting in protective failure. Traditional methods typically rely on chemical conversion films such as phosphates or chromate passivation to enhance adhesion, but these processes may face environmental constraints, or the physical bonding strength of the resulting interfacial layer may still have room for improvement.

[0004] Secondly, organic coatings are not absolutely dense; they may contain micropores and defects, and during the curing process, factors such as solvent evaporation can easily create microscopic channels. Corrosive small molecules can gradually penetrate to the coating / metal interface through these pathways, initiating interfacial corrosion and ultimately leading to coating blistering and substrate corrosion. To improve the shielding performance of coatings, existing technologies often add various rust-inhibiting pigments or physical barrier fillers to the coatings. However, these traditional fillers often suffer from uneven particle size distribution, poor compatibility with resins, or a single anti-corrosion mechanism, making it difficult to form a long-lasting, dense composite protective network in the coating that combines physical barrier and chemical stability. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a high corrosion-resistant color-coated steel sheet, so as to solve the problems existing in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a high corrosion-resistant color-coated steel plate, wherein the steel plate substrate has a roughened structured galvanized layer on both sides, and a corrosion-resistant coating is provided on the surface of the roughened structured galvanized layer.

[0007] The corrosion-resistant coating is an epoxy resin coating, comprising the following components by weight: 30-50 parts modified epoxy resin, 5-15 parts hexafunctional polyurethane acrylate, 5-10 parts di-2-propylene 1,2-phthalic acid, 1-5 parts acrylic acid, 10-25 parts silicone emulsion containing filler, 10-15 parts propylene glycol ether solvent, 1-5 parts titanium dioxide, 0.1-0.5 parts initiator, 4-8 parts curing agent, 0.1-0.3 parts leveling agent, and 0.1-0.2 parts defoamer;

[0008] The roughened structured zinc coating is achieved by roughening the zinc coating of the steel plate using a roughening modification solution. The roughening modification solution consists of the following parts by mass: 15-20 parts citric acid, 1-3 parts stearic acid, 0.5-1.2 parts zinc oxide, 3-8 parts zinc chloride, 30-50 parts ethanol, and 20-40 parts water.

[0009] Furthermore, the thickness of the hot-dip galvanized layer is 20μm-40μm.

[0010] Furthermore, the modified epoxy resin is an octenic acid modified epoxy resin.

[0011] Furthermore, the filler includes ceramic powder with a particle size of 40-80 nm, stainless steel powder with a particle size of 300-500 nm, and mesoporous silica with a particle size of 100-300 nm.

[0012] Furthermore, the ceramic powder is at least one of alumina ceramic powder, zirconia ceramic powder, chromium oxide ceramic powder, titanium oxide ceramic powder, and silicon oxide ceramic powder.

[0013] Furthermore, the filler-containing silicone emulsion is prepared by the following steps: water, nonionic emulsifier, octamethylcyclotetrasiloxane, and coupling agent KH570 are reacted under nitrogen protection, ceramic powder and stainless steel powder are added and ground, small molecule fluorinated siloxane is added and ground, and finally mesoporous silica is added and ground.

[0014] Furthermore, the small molecule fluorinated siloxane is at least one selected from trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, hexafluorobutylpropyltrimethoxysilane, dodecafluoroheptylpropyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, and heptadecafluorodecyltriethoxysilane.

[0015] On the other hand, the present invention provides a method for preparing a high corrosion-resistant color-coated steel sheet, comprising the following steps:

[0016] (1) The steel plate is subjected to rust removal, galvanizing and hot-dip galvanizing treatment to obtain a hot-dip galvanized steel plate;

[0017] (2) The hot-dip galvanized steel sheet is immersed in a roughening modification solution for soaking treatment to obtain a hot-dip galvanized steel sheet with a roughening treatment layer.

[0018] (3) The coating composition containing modified epoxy resin, hexafunctional polyurethane acrylate, di-2-propylene 1,2-phthalic acid, acrylic acid, silicone emulsion containing filler, propylene glycol ether solvent, titanium dioxide, initiator, curing agent, leveling agent and defoamer is mixed and applied to the surface of the hot-dip galvanized steel plate after step (2), and dried and cured to form the corrosion-resistant colored coating.

[0019] Furthermore, in step (3), the curing temperature is 150-210℃ and the dry film thickness of the coating is 10-20μm.

[0020] Furthermore, the curing agent in step (3) is at least one of 5,5'-methylenefurfuralamine, 5,5'-isopropyldifurfuralamine, and 5,5'-ethylfurfuralamine; the initiator is an azo initiator or a peroxide initiator.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0022] 1. This invention roughens the galvanized layer of steel plate. Citric acid, sodium nitrate, and stearic acid in the roughening modification solution have a synergistic corrosion effect on the zinc layer surface, forming a composite rough structure. This can improve the adhesion of the corrosion-resistant coating, thereby increasing the service life of the steel plate and the surface coating. Furthermore, the presence of stearic acid in the roughening modification solution can improve the hydrophobicity of the rough structure, effectively blocking the water and oxygen penetration path and improving the corrosion resistance of the steel plate coating surface.

[0023] 2. This invention incorporates mesoporous silica into the corrosion-resistant coating. This silica has a large specific surface area and small size effect, allowing it to fill the pores in the coating and prevent and delay the entry of corrosive small-molecule media into the metal substrate, providing excellent physical barrier properties. Simultaneously, it exhibits good compatibility with the coating itself, thus significantly improving the corrosion resistance of the steel plate. Furthermore, the addition of nano-ceramic powder and nano-stainless steel powder allows them to participate in the curing of the corrosion-resistant coating and form a special shielding layer, effectively isolating corrosive media and further enhancing the corrosion resistance of the coated steel plate. The nano-ceramic powder and nano-stainless steel powder can also fill the rough structure of the galvanized layer, resulting in a smooth surface for the corrosion-resistant coating and improving the wear resistance of the steel plate coating. In addition, the mesoporous silica, nano-ceramic powder, and nano-stainless steel have a certain particle size distribution gradient, enabling them to fill pores together. The synergistic use of these various anti-corrosion components demonstrates corrosion resistance far exceeding that of a single anti-corrosion filler, and can make the coating more compact, effectively reducing coating porosity and improving the coating's mechanical properties.

[0024] 3. This invention uses octenic acid modified epoxy resin as the main resin, which is thermally crosslinked with 1,2-di-2-propenyl phthalate, acrylic acid, and fluorinated silicone emulsion to form a dense coating, improving the corrosion resistance of the steel plate coating. The addition of 1,2-di-2-propenyl phthalate introduces a large number of benzene rings into the coating, giving it good hardness and wear and scratch resistance. The fluorinated silicone emulsion also contains a large number of CF bonds. CF bonds not only have high bond energy, which can further improve its mechanical properties and stability, significantly improving its corrosion resistance, but also reduce the attraction between molecules, resulting in good lubricity and reducing its coefficient of friction. In addition, the introduction of acrylic acid can chelate with the zinc plating layer and rust ions, so that an oxide layer can be formed on the outer surface of the coating, which has the effect of corrosion resistance and adhesion. Detailed Implementation

[0025] 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.

[0026] Example 1: (1) The steel plate was derusted with 15% hydrochloric acid by mass, and then rinsed with water. Then, a mixed solution of 150g / L NH4Cl and 150g / L ZnCl2 was used to flux the rinsed steel plate at 60°C for 60s, and then the fluxed steel plate was dried. Then, the steel plate was immersed in zinc ingots at 450°C for 60s to perform hot-dip galvanizing. Finally, it was placed in cold water to obtain a hot-dip galvanized steel plate with a coating thickness of 30μm.

[0027] (2) Immerse the hot-dip galvanized steel sheet in the roughening modification solution for 30 minutes to obtain a roughened hot-dip galvanized material; the roughening modification solution is composed of the following parts by mass: 18 parts citric acid, 2 parts stearic acid, 0.8 parts zinc oxide, 5.5 parts zinc chloride, 40 parts ethanol, and 30 parts water.

[0028] (3) 15 parts of E-51 epoxy resin, 1.5 parts of EPG217 polypropylene glycol diglycidyl ether and 6 parts of octenic acid were added to the reaction vessel in sequence, and nitrogen gas was introduced to replace the air in the reaction vessel. The mixture was mechanically stirred and heated to 95°C. Then, 0.01 parts of triethylenediamine catalyst were added and the temperature was raised to 140°C. The mixture was stirred and reacted for 3 hours under the heat preservation condition. After cooling, the modified epoxy resin was obtained.

[0029] (4) Dissolve 0.5 parts of hexadecyltrimethylammonium bromide and 0.5 parts of sodium dodecyl sulfate in water, then adjust the pH of the solution to 11, add 3 parts of tetraethyl orthosilicate dropwise and react for 4 hours, then carry out hydrothermal reaction at 130°C for 20 hours, wash and dry to obtain mesoporous silica.

[0030] (5) 120 parts of water, 7 parts of alkylphenol polyoxyethylene ether, 23 parts of octamethylcyclotetrasiloxane, and 13 parts of coupling agent KH570 were added to the reactor and reacted at 80°C for 7 hours under nitrogen protection. Then, 27.5 parts of zirconium oxide ceramic powder with a particle size of 60 nm and 20 parts of stainless steel powder with a particle size of 400 nm were added and ground for 30 minutes. Then, 25 parts of tridecafluorooctyltriethoxysilane were added and ground at 80°C for 6 hours. Finally, 40 parts of mesoporous silica with a particle size of 200 nm were added and ground for 15 minutes to obtain an organosilicon emulsion containing filler.

[0031] (6) Take 40 parts by weight of modified epoxy resin, 10 parts of Guangzhou Boxin B619W hexafunctional polyurethane acrylate, 7.5 parts of 1,2-di-2-propenyl 1,2-phthalic acid, 3 parts of acrylic acid, 17.5 parts of silicone emulsion containing filler, 12.5 parts of propylene glycol methyl ether, 3 parts of titanium dioxide, 0.3 parts of azobisisobutyronitrile, 6 parts of 5,5'-methylene furfural, 0.2 parts of BYK-333, and 0.15 parts of BYK-065, mix them, coat them with a corrosion-resistant layer with a thickness of 15 μm, and dry and cure at 180℃.

[0032] Example 2: (1) The steel plate was derusted with 15% hydrochloric acid and rinsed with water. Then, a mixed solution of 150g / L NH4Cl and 150g / L ZnCl2 was used to galvanize the rinsed steel plate at 80°C for 45s. The galvanized steel plate was then dried. The steel plate was then immersed in zinc ingots at 420°C for 45s to perform hot-dip galvanizing. Finally, it was placed in cold water to obtain a hot-dip galvanized steel plate with a coating thickness of 30μm.

[0033] (2) Immerse the hot-dip galvanized steel sheet in the roughening modification solution for 30 minutes to obtain a roughened hot-dip galvanized material; the roughening modification solution is composed of the following parts by mass: 15 parts citric acid, 1 part stearic acid, 0.5 parts zinc oxide, 8 parts zinc chloride, 30 parts ethanol, and 40 parts water.

[0034] (3) 10 parts of E-51 epoxy resin, 1 part of EPG217 polypropylene glycol diglycidyl ether and 2 parts of octenic acid were added to the reaction vessel in sequence, and nitrogen gas was introduced to replace the air in the reaction vessel. The mixture was mechanically stirred and heated to 95°C. Then, 0.01 parts of triethylenediamine catalyst were added and the temperature was raised to 140°C. The mixture was stirred and reacted for 3 hours under the heat preservation condition. After cooling, the modified epoxy resin was obtained.

[0035] (4) Dissolve 0.5 parts of hexadecyltrimethylammonium bromide and 0.5 parts of sodium dodecyl sulfate in water, then adjust the pH of the solution to 11, add 3 parts of tetraethyl orthosilicate dropwise and react for 4 hours, then carry out hydrothermal reaction at 130°C for 20 hours, wash and dry to obtain mesoporous silica.

[0036] (5) Add 80 parts of water, 4 parts of polyoxyethylene alkyl ether, 6 parts of octamethylcyclotetrasiloxane, and 6 parts of coupling agent KH570 to the reactor. Under nitrogen protection, react at 60°C for 10 h. Add 20 parts of alumina ceramic powder with a particle size of 40 nm and 10 parts of stainless steel powder with a particle size of 500 nm and grind for 40 min. Then add 10 parts of hexafluorobutylpropyltrimethoxysilane and grind at 65°C for 10 h. Finally, add 30 parts of mesoporous silica with a particle size of 100 nm and grind for 20 min to obtain an organosilicon emulsion containing filler.

[0037] (6) Take 30 parts by weight of modified epoxy resin, 5 parts of Agisyn242 hexafunctional polyurethane acrylate, 5 parts of di-2-propylene 1,2-phthalic acid, 1 part of acrylic acid, 10 parts of silicone emulsion containing filler, 10 parts of dipropylene glycol methyl ether, 1 part of titanium dioxide, 0.1 part of benzoyl peroxide, 4 parts of 5,5'-isopropyl difurfurylamine, 0.1 part of BYK-333, and 0.1 part of BYK-065, mix them, coat them with a corrosion-resistant layer with a thickness of 15 μm, and dry and cure at 150℃.

[0038] Example 3: (1) The steel plate was derusted with 15% hydrochloric acid by mass, and then rinsed with water. Then, a mixed solution of 150g / L NH4Cl and 150g / L ZnCl2 was used to flux the rinsed steel plate at 70°C for 50s, and then the fluxed steel plate was dried. Then, the steel plate was immersed in zinc ingots at 440°C for 55s for hot-dip galvanizing, and finally placed in cold water to obtain a hot-dip galvanized steel plate with a coating thickness of 30μm.

[0039] (2) Immerse the hot-dip galvanized steel sheet in the roughening modification solution for 30 minutes to obtain a roughened hot-dip galvanized material; the roughening modification solution is composed of the following parts by mass: 20 parts citric acid, 3 parts stearic acid, 1.2 parts zinc oxide, 3 parts zinc chloride, 50 parts ethanol, and 20 parts water.

[0040] (3) 20 parts of E-51 epoxy resin, 2 parts of EPG217 polypropylene glycol diglycidyl ether and 10 parts of octenic acid were added to the reaction vessel in sequence, and nitrogen gas was introduced to replace the air in the reaction vessel. The mixture was mechanically stirred and heated to 95°C. Then, 0.01 parts of triethylenediamine catalyst were added and the temperature was raised to 140°C. The mixture was stirred and reacted for 3 hours under the heat preservation condition. After cooling, the modified epoxy resin was obtained.

[0041] (4) Dissolve 0.5 parts of hexadecyltrimethylammonium bromide and 0.5 parts of sodium dodecyl sulfate in water, then adjust the pH of the solution to 11, add 3 parts of tetraethyl orthosilicate dropwise and react for 4 hours, then carry out hydrothermal reaction at 130°C for 20 hours, wash and dry to obtain mesoporous silica.

[0042] (5) 160 parts of water, 10 parts of polyoxyethylene sorbitan stearate, 40 parts of octamethylcyclotetrasiloxane, and 20 parts of coupling agent KH570 were added to the reactor and reacted at 90°C for 4 hours under nitrogen protection. Then, 35 parts of chromium oxide ceramic powder with a particle size of 80 nm and 30 parts of stainless steel powder with a particle size of 300 nm were added and ground for 20 minutes. Then, 40 parts of heptadecafluorodecyltriethoxysilane were added and ground at 90°C for 2 hours. Finally, 50 parts of mesoporous silica with a particle size of 100 nm were added and ground for 10 minutes to obtain an organosilicon emulsion containing filler.

[0043] (6) Take 50 parts by weight of modified epoxy resin, 15 parts of Bayer U400 hexafunctional polyurethane acrylate, 10 parts of di-2-propylene 1,2-phthalic acid, 5 parts of acrylic acid, 25 parts of silicone emulsion containing filler, 15 parts of propylene glycol butyl ether, 5 parts of titanium dioxide, 0.5 parts of dicumyl peroxide, 8 parts of 5,5'-ethylenoxide furfural amine, 0.3 parts of BYK-333, and 0.2 parts of BYK-065, mix them, coat them with a corrosion-resistant layer with a thickness of 15 μm, and dry and cure at 210℃.

[0044] Example 4: (1) The steel plate was derusted with 15% hydrochloric acid and rinsed with water. Then, a mixed solution of 150g / L NH4Cl and 150g / L ZnCl2 was used to galvanize the rinsed steel plate at 65°C for 55s. The galvanized steel plate was then dried. The steel plate was then immersed in zinc ingots at 430°C for 50s for hot-dip galvanizing. Finally, it was placed in cold water to obtain a hot-dip galvanized steel plate with a coating thickness of 30μm.

[0045] (2) Immerse the hot-dip galvanized steel sheet in the roughening modification solution for 30 minutes to obtain a roughened hot-dip galvanized material; the roughening modification solution is composed of the following parts by mass: 16 parts citric acid, 1.5 parts stearic acid, 0.7 parts zinc oxide, 4 parts zinc chloride, 35 parts ethanol, and 35 parts water.

[0046] (3) 12 parts of E-51 epoxy resin, 1.2 parts of EPG217 polypropylene glycol diglycidyl ether and 4 parts of octenic acid were added to the reaction vessel in sequence, and nitrogen gas was introduced to replace the air in the reaction vessel. The mixture was mechanically stirred and heated to 95°C. Then, 0.01 parts of triethylenediamine catalyst were added and the temperature was raised to 140°C. The mixture was stirred and reacted for 3 hours under the heat preservation condition. After cooling, the modified epoxy resin was obtained.

[0047] (4) Dissolve 0.5 parts of hexadecyltrimethylammonium bromide and 0.5 parts of sodium dodecyl sulfate in water, then adjust the pH of the solution to 11, add 3 parts of tetraethyl orthosilicate dropwise and react for 4 hours, then carry out hydrothermal reaction at 130°C for 20 hours, wash and dry to obtain mesoporous silica.

[0048] (5) Add 100 parts of water, 6 parts of alkylphenol polyoxyethylene ether, 15 parts of octamethylcyclotetrasiloxane, and 10 parts of coupling agent KH570 to the reactor. Under nitrogen protection, react at 70°C for 8 hours. Add 25 parts of titanium dioxide ceramic powder with a particle size of 50 nm and 15 parts of stainless steel powder with a particle size of 450 nm and grind for 35 minutes. Then add 20 parts of trifluoropropyltrimethoxysilane and grind at 75°C for 8 hours. Finally, add 35 parts of mesoporous silica with a particle size of 150 nm and grind for 18 minutes to obtain an organosilicon emulsion containing filler.

[0049] (6) Take 35 parts by weight of modified epoxy resin, 8 parts of Guangzhou Boxin B615 hexafunctional polyurethane acrylate, 6 parts of 1,2-di-2-propenyl 1,2-phthalic acid, 2 parts of acrylic acid, 15 parts of silicone emulsion containing filler, 11 parts of propylene glycol propyl ether, 2 parts of titanium dioxide, 0.2 parts of azobisisobutyronitrile, 5 parts of 5,5'-methylenefurfuralamine, 0.15 parts of BYK-333, and 0.12 parts of BYK-065, mix them, coat them with a corrosion-resistant layer with a thickness of 15 μm, and dry and cure at 190℃.

[0050] Example 5: (1) The steel plate was derusted with 15% hydrochloric acid and rinsed with water. Then, a mixed solution of 150g / L NH4Cl and 150g / L ZnCl2 was used to flux the rinsed steel plate at 75°C for 40s. The fluxed steel plate was then dried. The steel plate was then immersed in zinc ingots at 460°C for 65s for hot-dip galvanizing. Finally, it was placed in cold water to obtain a hot-dip galvanized steel plate with a coating thickness of 30μm.

[0051] (2) Immerse the hot-dip galvanized steel sheet in the roughening modification solution for 30 minutes to obtain a roughened hot-dip galvanized material; the roughening modification solution is composed of the following parts by mass: 19 parts citric acid, 2.5 parts stearic acid, 1.0 part zinc oxide, 7 parts zinc chloride, 45 parts ethanol, and 25 parts water.

[0052] (3) 18 parts of E-51 epoxy resin, 1.8 parts of EPG217 polypropylene glycol diglycidyl ether and 8 parts of octenic acid were added to the reaction vessel in sequence, and nitrogen gas was introduced to replace the air in the reaction vessel. The mixture was mechanically stirred and heated to 95°C. Then, 0.01 parts of triethylenediamine catalyst were added and the temperature was raised to 140°C. The mixture was stirred and reacted for 3 hours under the heat preservation condition. After cooling, the modified epoxy resin was obtained.

[0053] (4) Dissolve 0.5 parts of hexadecyltrimethylammonium bromide and 0.5 parts of sodium dodecyl sulfate in water, then adjust the pH of the solution to 11, add 3 parts of tetraethyl orthosilicate dropwise and react for 4 hours, then carry out hydrothermal reaction at 130°C for 20 hours, wash and dry to obtain mesoporous silica.

[0054] (5) 140 parts of water, 8 parts of polyoxyethylene alkyl ether, 30 parts of octamethylcyclotetrasiloxane, and 17 parts of coupling agent KH570 were added to the reactor and reacted at 85°C for 5 hours under nitrogen protection. Then, 30 parts of silica ceramic powder with a particle size of 70 nm and 25 parts of stainless steel powder with a particle size of 350 nm were added and ground for 25 minutes. Then, 30 parts of tridecafluorooctyltrimethoxysilane were added and ground at 85°C for 4 hours. Finally, 45 parts of mesoporous silica with a particle size of 250 nm were added and ground for 12 minutes to obtain an organosilicon emulsion containing filler.

[0055] (6) Take 45 parts by weight of modified epoxy resin, 12 parts of Agisyn242 hexafunctional polyurethane acrylate, 8 parts of di-2-propylene 1,2-phthalic acid, 4 parts of acrylic acid, 20 parts of silicone emulsion containing filler, 14 parts of propylene glycol methyl ether, 4 parts of titanium dioxide, 0.4 parts of tert-butyl peroxide, 7 parts of 5,5'-isopropyl difurfurylamine, 0.25 parts of BYK-333, and 0.18 parts of BYK-065, mix them, coat them with a corrosion-resistant layer with a thickness of 15 μm, and dry and cure at 200℃.

[0056] Example 6: (1) The steel plate was derusted with 15% hydrochloric acid by mass, and then rinsed with water. Then, a mixed solution of 150g / L NH4Cl and 150g / L ZnCl2 was used to flux the rinsed steel plate at 55°C for 70s, and then the fluxed steel plate was dried. Then, the steel plate was immersed in zinc ingots at 410°C for 70s to perform hot-dip galvanizing. Finally, it was placed in cold water to obtain a hot-dip galvanized steel plate with a coating thickness of 30μm.

[0057] (2) Immerse the hot-dip galvanized steel sheet in the roughening modification solution for 30 minutes to obtain a roughened hot-dip galvanized material; the roughening modification solution is composed of the following parts by mass: 17 parts citric acid, 1.2 parts stearic acid, 0.6 parts zinc oxide, 6 parts zinc chloride, 32 parts ethanol, and 38 parts water.

[0058] (3) 13 parts of E-51 epoxy resin, 1.3 parts of EPG217 polypropylene glycol diglycidyl ether and 3 parts of octenic acid were added to the reaction vessel in sequence, and nitrogen gas was introduced to replace the air in the reaction vessel. The mixture was mechanically stirred and heated to 95°C. Then, 0.01 parts of triethylenediamine catalyst were added and the temperature was raised to 140°C. The mixture was stirred and reacted for 3 hours under the heat preservation condition. After cooling, the modified epoxy resin was obtained.

[0059] (4) Dissolve 0.5 parts of hexadecyltrimethylammonium bromide and 0.5 parts of sodium dodecyl sulfate in water, then adjust the pH of the solution to 11, add 3 parts of tetraethyl orthosilicate dropwise and react for 4 hours, then carry out hydrothermal reaction at 130°C for 20 hours, wash and dry to obtain mesoporous silica.

[0060] (5) Add 90 parts of water, 5 parts of polyoxyethylene sorbitan stearate, 10 parts of octamethylcyclotetrasiloxane, and 8 parts of coupling agent KH570 to the reactor. Under nitrogen protection, react at 65°C for 9 hours. Add 22 parts of zirconium oxide ceramic powder with a particle size of 45 nm and 12 parts of stainless steel powder with a particle size of 480 nm and grind for 38 minutes. Then add 15 parts of heptadecafluorodecyltrimethoxysilane and grind at 70°C for 9 hours. Finally, add 32 parts of mesoporous silica with a particle size of 120 nm and grind for 16 minutes to obtain an organosilicon emulsion containing filler.

[0061] (6) Take 32 parts by weight of modified epoxy resin, 6 parts of Guangzhou Boxin B619W hexafunctional polyurethane acrylate, 5.5 parts of di-2-propylene 1,2-phthalic acid, 1.5 parts of acrylic acid, 12 parts of silicone emulsion containing filler, 10.5 parts of dipropylene glycol methyl ether, 1.5 parts of titanium dioxide, 0.15 parts of azobisisobutyronitrile, 4.5 parts of 5,5'-ethylene furfural amine, 0.12 parts of BYK-333, and 0.11 parts of BYK-065, mix them, coat them with a corrosion-resistant layer with a thickness of 15 μm, and dry and cure at 160℃.

[0062] Comparative Example 1: The difference between Comparative Example 1 and Example 3 is that the E-51 epoxy resin is not modified. Instead, E-51 epoxy resin is used instead of modified epoxy resin. The remaining steps are the same as in Example 3.

[0063] Comparative Example 2: The difference between Comparative Example 2 and Example 3 is that the hot-dip galvanized steel sheet is not immersed in the roughening modification liquid, and the other steps are the same as in Example 3.

[0064] Comparative Example 3: The difference between Comparative Example 3 and Example 3 is that mesoporous silica and ceramic powder are not added, while the other steps are the same as in Example 3.

[0065] Comparative Example 4: The difference between Comparative Example 4 and Example 3 is that ceramic powder and stainless steel powder are not added, while the other steps are the same as in Example 3.

[0066] Comparative Example 5: The difference between Comparative Example 5 and Example 3 is that stainless steel powder and mesoporous silica are not added, while the other steps are the same as in Example 3.

[0067] Comparative Example 6: The difference between Comparative Example 6 and Example 3 is that 1,2-dipropene 1,2-phthalic acid is not added, and the other steps are the same as in Example 3.

[0068] Comparative Example 7: The difference between Comparative Example 7 and Example 3 is that acrylic acid is not added, but the rest of the steps are the same as in Example 3.

[0069] Comparative Example 8: The difference between Comparative Example 8 and Example 3 is that step (5) is omitted, and step (6) is changed to: taking 50 parts of modified epoxy resin, 15 parts of Bayer U400 hexafunctional polyurethane acrylate, 10 parts of 1,2-di-2-propenyl 1,2-phthalic acid, 5 parts of acrylic acid, 25 parts of filler, 15 parts of propylene glycol butyl ether, 5 parts of titanium dioxide, 0.5 parts of dicumyl peroxide, 8 parts of 5,5'-ethylenoxide furfural amine, 0.3 parts of BYK-333, and 0.2 parts of BYK-065 by mass, mixing them, coating a corrosion-resistant layer with a thickness of 15 μm, and drying and curing at 210°C; the filler is composed of chromium oxide ceramic powder with a particle size of 80 nm, stainless steel powder with a particle size of 300 nm, and mesoporous silica with a particle size of 100 nm in a mass ratio of 35:30:50; the remaining steps are the same as in Example 3.

[0070] Comparative Example 9: The difference between Comparative Example 9 and Example 3 is that the particle size of chromium oxide ceramic powder, stainless steel powder, and mesoporous silica is uniformly 80nm, while the other steps are the same as in Example 3.

[0071] Comparative Example 10: The difference between Comparative Example 10 and Example 3 is that the particle size of chromium oxide ceramic powder, stainless steel powder, and mesoporous silica is uniformly 300 nm, while the other steps are the same as in Example 3.

[0072] Comparative Example 11: The difference between Comparative Example 11 and Example 3 is that the particle size of chromium oxide ceramic powder, stainless steel powder, and mesoporous silica is uniformly 100 nm, while the other steps are the same as in Example 3.

[0073]

[0074]

[0075] The test results are shown in Tables 1 and 2. As can be seen from Table 1, all embodiments of the present invention performed excellently in all tests, with adhesion at grade 1. After tests of hot water, salt spray, acid, and alkali, the coatings showed no blistering, peeling, or corrosion, and exhibited good wear resistance. This indicates that through the roughening treatment of the zinc plating layer, the synergistic effect of the filler, and the design of the corrosion-resistant layer formulation, the coating possesses good adhesion, corrosion resistance, and wear resistance. Comparative Example 1, without modified epoxy resin, showed a significant decrease in resistance to hot water, salt spray, acids, alkalis, and abrasion. Comparative Example 2, without roughening treatment, experienced a drop in adhesion to level 2 and severely deteriorated corrosion resistance. Comparative Examples 3-5 lacked specific fillers, resulting in varying degrees of performance degradation in salt spray, acid, and abrasion resistance. Comparative Examples 6-7 lacked key reactive monomers, leading to defects in corrosion resistance or adhesion. The filler in Comparative Example 8, without silicone emulsion coating treatment, also performed worse than the examples. The filler in Comparative Examples 9-11 had a single particle size, resulting in inferior corrosion resistance, adhesion, and abrasion resistance compared to the multi-level particle size synergistic effect of this invention. In summary, this invention, through zinc layer roughening, filler synergy, and corrosion-resistant layer formulation design, achieves a synergistic improvement in coating adhesion, corrosion resistance, and abrasion resistance, making it suitable for long-term use in harsh environments.

[0076] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A high corrosion-resistant color-coated steel sheet, characterized in that, The steel plate substrate has a roughened structured zinc plating layer on both sides, and a corrosion-resistant coating is provided on the surface of the roughened structured zinc plating layer. The corrosion-resistant coating is an epoxy resin coating, which comprises the following components by weight: 30-50 parts modified epoxy resin, 5-15 parts hexafunctional polyurethane acrylate, 5-10 parts di-2-propylene 1,2-phthalic acid, 1-5 parts acrylic acid, 10-25 parts silicone emulsion containing filler, 10-15 parts propylene glycol ether solvent, 1-5 parts titanium dioxide, 0.1-0.5 parts initiator, 4-8 parts curing agent, 0.1-0.3 parts leveling agent, and 0.1-0.2 parts defoamer; The roughened structured zinc coating is achieved by roughening the zinc coating of the steel plate using a roughening modification solution. The roughening modification solution consists of the following parts by mass: 15-20 parts citric acid, 1-3 parts stearic acid, 0.5-1.2 parts zinc oxide, 3-8 parts zinc chloride, 30-50 parts ethanol, and 20-40 parts water. The modified epoxy resin is an octenic acid modified epoxy resin; The filler-containing silicone emulsion is prepared by the following steps: water, nonionic emulsifier, octamethylcyclotetrasiloxane, and coupling agent KH570 are reacted under nitrogen protection, ceramic powder and stainless steel powder are added and ground, then small molecule fluorinated siloxane is added and ground, and finally mesoporous silica is added and ground.

2. The high corrosion-resistant color-coated steel sheet according to claim 1, characterized in that, The thickness of the roughened structured zinc plating layer is 20μm-40μm.

3. The high corrosion-resistant color-coated steel sheet according to claim 1, characterized in that, The filler includes ceramic powder with a particle size of 40-80 nm, stainless steel powder with a particle size of 300-500 nm, and mesoporous silica with a particle size of 100-300 nm.

4. The high corrosion-resistant color-coated steel sheet according to claim 3, characterized in that, The ceramic powder is at least one of alumina ceramic powder, zirconia ceramic powder, chromium oxide ceramic powder, titanium oxide ceramic powder, and silicon oxide ceramic powder.

5. The high corrosion-resistant color-coated steel sheet according to claim 1, characterized in that, The small molecule fluorinated siloxane is at least one of trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, hexafluorobutylpropyltrimethoxysilane, dodecafluoroheptylpropyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, and heptadecafluorodecyltriethoxysilane.

6. A method for preparing a high corrosion-resistant color-coated steel sheet as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) The steel plate is subjected to rust removal, galvanizing and hot-dip galvanizing treatment to obtain a hot-dip galvanized steel plate; (2) The hot-dip galvanized steel sheet is immersed in a roughening modification solution for soaking treatment to obtain a hot-dip galvanized steel sheet with a roughening treatment layer. (3) The coating composition containing modified epoxy resin, hexafunctional polyurethane acrylate, di-2-propylene 1,2-phthalic acid, acrylic acid, silicone emulsion containing filler, propylene glycol ether solvent, titanium dioxide, initiator, curing agent, leveling agent and defoamer is mixed and applied to the surface of the hot-dip galvanized steel plate after step (2), and dried and cured to form the corrosion-resistant colored coating.

7. The method for preparing a high corrosion-resistant color-coated steel sheet according to claim 6, characterized in that, In step (3), the curing temperature is 150-210℃ and the dry film thickness of the coating is 10-20μm.

8. The method for preparing a high corrosion-resistant color-coated steel sheet according to claim 6, characterized in that, The curing agent in step (3) is at least one of 5,5'-methylenefurfuralamine, 5,5'-isopropyldifurfuralamine, and 5,5'-ethylfurfuralamine; the initiator is an azo initiator or a peroxide initiator.

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