A smooth steel high-adhesion organic anti-corrosion coating and its preparation method

Abstract

The present invention discloses an organic anti-corrosion coating with high adhesion to smooth steel and a preparation method thereof. First, the smooth steel surface is cleaned and heat-treated to avoid the presence of carbon-based or organic components, while imparting a large number of oxygen-containing groups. Secondly, an organic coating with good mechanical properties, the ability to form chemical and physical bonds with a substrate, and high density or barrier properties is designed from three aspects: an organic epoxy resin curing system, zinc powder surface modification, and surface polyurethane formula design. A high-adhesion paint film is prepared, and the initial adhesion of the paint film meets the requirements of level 0 or level 1 in ISO2409. This solves the problem that traditional organic coatings have low adhesion on smooth steel surfaces and are prone to paint peeling during spraying or use. At the same time, the weather resistance, corrosion resistance and other properties of the coating are also correspondingly improved, better meeting the needs of complex environments.

Description

Technical Field

[0001] The present invention relates to the technical field of organic anti-corrosion coating preparation, and in particular to a smooth steel high-adhesion organic anti-corrosion coating and a preparation method thereof. Background Art

[0002] Axles are the most crucial components of a train's running system. They bear the entire weight of the train and are subject to impact and braking forces during operation and parking. At high speeds and heavy loads, the forces acting upon them are even more complex. Therefore, train axles must possess sufficient strength and impact toughness to ensure absolute safety and reliability under the highest speeds and loads. Axles are mostly manufactured from stainless steel, which is susceptible to corrosion in environments such as water, air, or chloride ions. This deteriorates the axle's mechanical properties, compromising the train's safety and stability and potentially impacting public safety and property. Therefore, achieving effective corrosion protection for train axles has become a key focus in the transportation and rail sector.

[0003] As we all know, organic coatings are currently the primary method for axle corrosion protection due to their low cost, easy application, excellent corrosion protection, and ease of maintenance and repair. However, in actual use, "paint peeling" is a common phenomenon. This is when the organic coating peels off from the train axle, forming a corrosion surface. As the corrosion surface gradually expands, the protective organic coating eventually loses its corrosion protection function. The root cause of this phenomenon is the high surface smoothness of the train axle, resulting in poor mechanical adhesion between the coating and the axle, which significantly reduces the adhesion between the coating and the metal surface.

[0004] The paint film's anti-corrosion mechanism is primarily a shielding mechanism, meaning the film can isolate corrosive media such as water, oxygen, and chloride ions from the steel surface, preventing corrosion. However, by measuring the permeability of the paint film to water and oxygen, it was found that it is difficult for the paint film to completely block the penetration of corrosive media such as aqueous solutions. When aqueous corrosive media penetrate the paint film and reach the steel surface through osmosis, if the paint film's "adhesion" is poor, the water and the dissolved oxygen or chlorine in it directly contact the anodic and cathodic areas on the steel surface, causing corrosion. As corrosion progresses, the generated ferrous and hydroxide ions generate osmotic pressure under the paint film, forcing water to further pass through the semi-permeable membrane, thereby creating a force that forces the paint film away from the substrate, causing the paint film to gradually peel off. This, in turn, increases the number of unprotected steel surfaces, creating more corroded surfaces, ultimately leading to the shedding and destruction of the organic coating, and the loss of its anti-corrosion function. Therefore, the "adhesion" of the organic coating to steel is one of the most important factors and performance indicators of its corrosion resistance.

[0005] At present, the adhesion theories or mechanisms of organic coatings mainly include mechanical twisting and bonding theory, physical bonding theory and chemical bonding theory. The mechanical twisting and bonding theory believes that the main factor affecting adhesion is the mechanical latching mechanism existing in the grooves on the substrate surface, that is, the organic coating and the rough metal surface can bite each other to form a hook-like connection. Therefore, in order to improve the adhesion of the paint film, the most common and effective method is to roughen the metal surface. From the above analysis, it can be seen that due to the lack of mechanical twisting and bonding, the adhesion of traditional organic coatings on the surface of high-smooth axles is relatively low. During spraying or use, the organic coating is easy to detach, which greatly reduces its anti-corrosion performance on high-smooth surface axles, affects its safety, and increases its repair and maintenance costs.

[0006] Therefore, the present invention provides a high-adhesion organic anti-corrosion coating for smooth steel and a preparation method thereof. On the surface of the smooth axle, a new surface treatment process is adopted, combined with a new organic coating formula, to improve the adhesion between the organic coating and the smooth surface axle from the two perspectives of physical and chemical bonding, so as to solve the problem that traditional organic coatings, including imported organic coatings, are easy to lose paint and have a short service life when used in the field of smooth axle corrosion protection. Summary of the Invention

[0007] The purpose of the present invention is to provide a smooth steel high-adhesion organic anti-corrosion coating and a preparation method thereof, so as to fill the gap in the current technology.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A method for preparing a smooth steel high-adhesion organic anti-corrosion coating comprises the following steps:

[0010] S1. Axle surface treatment:

[0011] Polish the axle surface with 80-1200 mesh SiC paper and remove surface rust. Degrease with 3 mol potassium hydroxide solution at 75-85°C for 15-18 minutes, wash with distilled water first, then with ethanol, dry at room temperature for 1-1.5 hours, and heat treat at 600-650°C for 1-3 hours to obtain a uniform and dense iron oxide layer of 5-10 microns on the smooth axle surface.

[0012] S2. Zinc powder surface treatment:

[0013] 10-12 g of original zinc powder is dispersed in 1000-1100 ml of indole-3-butyric acid aqueous solution to form a suspension, the suspension is stirred at 65-75° C. for 24-28 hours, the precipitate is filtered and washed with water, and dried in a vacuum oven at 75-85° C. for 2-2.5 days to obtain a dried powder, 10-12 g of the powder is dispersed in 100-110 ml of acetone solution, magnetically stirred under ultrasonic assistance for 1-2 hours, 3-aminopropyltriethoxysilane (APTES) is added, and the reaction is continued at room temperature for 12-16 hours. The precipitate is filtered and washed with ethanol, and dried in a vacuum oven at 55-65° C. for 24-28 hours to obtain a double-modified zinc powder;

[0014] S3. Preparation of epoxy zinc-rich primer:

[0015] Disperse the double-modified zinc powder obtained in step S2 in xylene and disperse it evenly under mechanical stirring, add E51 epoxy resin, dissolve and disperse it, continue to add defoaming agent and leveling agent, and stir until it is evenly dispersed to obtain epoxy zinc-rich primer;

[0016] Dissolving triethylenetetramine in xylene to prepare a 90% triethylenetetramine xylene solution as a curing system for the epoxy zinc-rich primer;

[0017] S4. Preparation of high-humidity and heat-resistant polyurethane topcoat:

[0018] Disperse 150-155g of titanium dioxide in xylene and disperse it evenly under mechanical stirring. Add 160-165g of NL387-6-70 polyester resin and 56-60g of PVR-102 polyester resin to the mixture and dissolve and disperse them. Then, add 1-2g of defoamer and 1-2g of leveling agent to the mixture and stir and disperse them evenly to obtain a high-humidity and heat-resistant polyurethane topcoat.

[0019] S5. Preparation of high adhesion organic anticorrosive coating:

[0020] The epoxy zinc-rich primer curing system prepared in step S3 is added to the epoxy zinc-rich primer prepared in step S3, mechanically stirred evenly, and sprayed onto the smooth axle surface heat-treated in step S1, dried naturally for 24-28 hours, and heat-cured at 75-85° C. for 1-2 hours to obtain a high-adhesion epoxy zinc-rich primer protective coating;

[0021] Add 90% HDI xylene solution to the polyurethane topcoat prepared in step S4, stir mechanically to evenly, spray the high-adhesion epoxy zinc-rich primer protective coating surface on the above-mentioned wheel axle, and dry naturally for 48 to 56 hours to obtain a smooth steel high-adhesion organic anti-corrosion coating.

[0022] Preferably, the D50 of the original zinc powder in step S2 is 5 to 10 microns; and the concentration of the indole-3-butyric acid aqueous solution is 20 to 25 mg / ml.

[0023] Preferably, the double-modified zinc powder in step S3 accounts for 70-75% of the epoxy zinc-rich primer; and the solid content of the epoxy zinc-rich primer is 50-55%.

[0024] Preferably, the titanium dioxide in step S4 accounts for 40-45% of the high-humidity and heat-resistant polyurethane topcoat; and the solid content of the high-humidity and heat-resistant polyurethane topcoat is 50-55%.

[0025] Preferably, in step S5, the mass ratio of the epoxy zinc-rich primer curing system added to the epoxy zinc-rich primer is 1:5-6 according to the mass ratio of the triethylenetetramine to the E51 epoxy resin.

[0026] Preferably, in step S5, the mass ratio of the 90% HDI xylene solution to the polyurethane topcoat is 1:15-16.

[0027] The high adhesion mechanism and innovations of the present invention are as follows:

[0028] The metal is controlled oxidized by heat treatment to increase the concentration of oxygen groups on the smooth metal surface, avoiding the problems of high surface roughness or low oxygen groups caused by traditional chemical treatment methods, and providing conditions for forming chemical or physical bonds with the epoxy resin substrate.

[0029] Using E51 and triethylenetetramine as the base resin and curing system for the organic coating, respectively, offers improved crosslinking density compared to traditional diamine curing systems, thereby increasing coating density. Furthermore, the excess amine groups can form chemical bonds with the O groups on the metal substrate. The triethylenetetramine not only serves as a curing system for the epoxy resin but also acts as a bridge between the epoxy resin and the metal substrate, enhancing the chemical or physical bonding between the epoxy primer organic coating and the smooth metal substrate, thereby improving the adhesion of the organic coating.

[0030] The dual modification of Zn powder with indole-3-butyric acid and APTES not only improves the dispersibility and stability of Zn powder in epoxy resin solution, but also enhances its compatibility and interfacial interaction with epoxy resin, thereby improving the density, mechanical properties, and barrier properties of the coating. Furthermore, APTES imparts chemical or physical bonding between Zn powder and the metal interface, and indole-3-butyric acid inhibits steel corrosion. This improves the mechanical strength and hydrophobicity of the epoxy zinc-rich primer, enhances the bonding between the zinc powder and the resin matrix and metal substrate, and inhibits steel corrosion, further enhancing the adhesion between the primer and the substrate.

[0031] A high-humidity and heat-resistant polyurethane coating is used as the topcoat to solve the problem of low moisture and heat resistance of traditional polyurethane coatings, which is also one of the reasons why the smooth axle surface coating is prone to paint loss during use. It reduces the diffusion of water vapor and oxygen to the interface between the coating and the metal substrate, and prevents the problem of reduced adhesion caused by metal corrosion.

[0032] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0033] 1. The present invention uses E51 and triethylenetetramine as the base resin and curing system of the organic coating, respectively, which has a better cross-linking density and improves the density of the coating; at the same time, the triethylenetetramine not only serves as the curing system of the epoxy resin, but also has a bridging effect between the epoxy resin and the metal substrate;

[0034] 2. The present invention uses indole-3-butyric acid and APTES to double-modify Zn powder, improving the dispersibility and stability of Zn powder in epoxy resin solution, while also increasing the compatibility and interfacial interaction between Zn powder and epoxy resin, further enhancing the coating density while also improving mechanical and barrier properties. Furthermore, by increasing the mechanical strength and hydrophobicity of the epoxy zinc-rich primer and the bonding between the zinc powder, the resin, and the metal substrate, the adhesion between the primer and the substrate is further improved.

[0035] 3. The present invention adopts a high-humidity and heat-resistant polyurethane coating as a topcoat, which improves the moisture and heat resistance of the polyurethane coating, effectively solves the problem that the smooth axle surface coating is easy to fall off during use, and further improves the adhesion between the organic coating and the smooth surface axle. DETAILED DESCRIPTION

[0036] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, a specific implementation scheme is now described in detail.

[0037] The present invention is further described below with reference to the following examples, but the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific applications. The implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention may be combined with each other as long as they do not conflict with each other.

[0038] Example 1

[0039] This embodiment provides a smooth steel high-adhesion organic anti-corrosion coating and a preparation method thereof, comprising the following steps:

[0040] S1. Axle surface treatment:

[0041] The axle surface was polished with 80 to 1200 g SiC paper to remove surface rust. The axle was then degreased with 3 mol potassium hydroxide solution at 80°C for 15 minutes. The axle was washed with distilled water and then with ethanol. The axle was then dried at room temperature for 1 hour and heat treated at 600°C for 3 hours to obtain a uniform and dense iron oxide layer of 8 microns on the smooth axle surface.

[0042] S2. Zinc powder surface treatment:

[0043] 10.0 g of original zinc powder was dispersed in 1000 ml of an indole-3-butyric acid aqueous solution with a concentration of 22 mg / ml to form a suspension. The suspension was stirred at 70°C for 24 h, and the precipitate was filtered and washed with water. The suspension was dried in a vacuum oven at 80°C for 2 days to obtain a dried powder. 10 g of the powder was dispersed in 100 ml of an acetone solution and magnetically stirred under ultrasonic assistance for 1 h. 5 g of APTES was added and the reaction was continued at room temperature for 12 h. The precipitate was filtered and washed with ethanol. The mixture was dried in a vacuum oven at 60°C for 24 h to obtain a double-modified zinc powder.

[0044] S3. Preparation of epoxy zinc-rich primer:

[0045] Disperse the double-modified zinc powder obtained in step S2 in xylene and disperse it evenly under mechanical stirring, add E51 epoxy resin, dissolve and disperse it, continue to add defoaming agent and leveling agent, and stir until it is evenly dispersed to obtain epoxy zinc-rich primer;

[0046] Dissolving triethylenetetramine in xylene to prepare a 90% triethylenetetramine xylene solution as a curing system for the epoxy zinc-rich primer;

[0047] The double-modified zinc powder accounts for 72% of the epoxy zinc-rich primer; the solid content of the epoxy zinc-rich primer is 53%;

[0048] S4. Preparation of high-humidity and heat-resistant polyurethane topcoat:

[0049] 150g of titanium dioxide was dispersed in xylene and dispersed evenly under mechanical stirring. 161g of NL387-6-70 polyester resin and 58g of PVR-102 resin were added thereto and dissolved and dispersed. 1g of defoamer and 1g of leveling agent were added thereto and stirred and dispersed evenly to obtain a high-humidity and heat-resistant polyurethane topcoat.

[0050] The titanium dioxide accounts for 40% of the high-humidity and heat-resistant polyurethane topcoat; the solid content of the high-humidity and heat-resistant polyurethane topcoat is 55%;

[0051] S5. Preparation of high adhesion organic anticorrosive coating:

[0052] The epoxy zinc-rich primer curing system prepared in step S3 is added to the epoxy zinc-rich primer prepared in step S3, with the mass ratio of the epoxy zinc-rich primer curing system to the epoxy zinc-rich primer being 1:5, and mechanically stirred to be uniform. The mixture is sprayed onto the smooth axle surface heat-treated in step S1, dried naturally for 24 hours, and heat-cured at 80° C. for 1 hour to obtain a heat-cured axle.

[0053] Add 90% HDI xylene solution to the polyurethane topcoat prepared in step S4, the mass ratio of the 90% HDI xylene solution to the polyurethane topcoat being 1:15, mechanically stir evenly, spray onto the heat-cured axle, and naturally dry for 48 hours to obtain a smooth steel high-adhesion organic anti-corrosion coating.

[0054] Example 2

[0055] This embodiment provides a smooth steel high-adhesion organic anti-corrosion coating and a preparation method thereof, comprising the following steps:

[0056] S1. Axle surface treatment:

[0057] The axle surface was polished with 80 to 1200 g SiC paper to remove surface rust. The axle was then degreased with 3 mol potassium hydroxide solution at 80°C for 15 minutes. The axle was washed with distilled water and then with ethanol. The axle was then dried at room temperature for 1 hour and heat treated at 600°C for 3 hours to obtain a uniform and dense iron oxide layer of 8 microns on the smooth axle surface.

[0058] S2. Zinc powder surface treatment:

[0059] 10.0 g of original zinc powder was dispersed in 1000 ml of an indole-3-butyric acid aqueous solution with a concentration of 22 mg / ml to form a suspension. The suspension was stirred at 70°C for 24 h, and the precipitate was filtered and washed with water. The suspension was dried in a vacuum oven at 80°C for 2 days to obtain a dried powder. 10 g of the powder was dispersed in 100 ml of an acetone solution and magnetically stirred under ultrasonic assistance for 1 h. 5 g of APTES was added and the reaction was continued at room temperature for 12 h. The precipitate was filtered and washed with ethanol. The mixture was dried in a vacuum oven at 60°C for 24 h to obtain a double-modified zinc powder.

[0060] S3. Preparation of epoxy zinc-rich primer:

[0061] Disperse the double-modified zinc powder obtained in step S2 in xylene and disperse it evenly under mechanical stirring, add E51 epoxy resin, dissolve and disperse it, continue to add defoaming agent and leveling agent, and stir until it is evenly dispersed to obtain epoxy zinc-rich primer;

[0062] Dissolving triethylenetetramine in xylene to prepare a 90% triethylenetetramine xylene solution as a curing system for the epoxy zinc-rich primer;

[0063] The double-modified zinc powder accounts for 72% of the epoxy zinc-rich primer; the solid content of the epoxy zinc-rich primer is 53%;

[0064] S4. Preparation of high-humidity and heat-resistant polyurethane topcoat:

[0065] 150g of titanium dioxide was dispersed in xylene and dispersed evenly under mechanical stirring. 161g of NL387-6-70 polyester resin and 58g of PVR-102 resin were added thereto and dissolved and dispersed. 1g of defoamer and 1g of leveling agent were added thereto and stirred and dispersed evenly to obtain a high-humidity and heat-resistant polyurethane topcoat.

[0066] The titanium dioxide accounts for 40% of the high-humidity and heat-resistant polyurethane topcoat; the solid content of the high-humidity and heat-resistant polyurethane topcoat is 55%;

[0067] S5. Preparation of high adhesion organic anticorrosive coating:

[0068] The epoxy zinc-rich primer curing system prepared in step S3 is added to the epoxy zinc-rich primer prepared in step S3, with the mass ratio of the epoxy zinc-rich primer curing system to the epoxy zinc-rich primer being 1:5, and mechanically stirred to be uniform. The mixture is sprayed onto the smooth axle surface heat-treated in step S1, dried naturally for 24 hours, and heat-cured at 80° C. for 1 hour to obtain a heat-cured axle.

[0069] Add 90% HDI xylene solution to the polyurethane topcoat prepared in step S4, the mass ratio of the 90% HDI xylene solution to the polyurethane topcoat being 1:16, mechanically stir evenly, spray onto the heat-cured axle, and naturally dry for 48 hours to obtain a smooth steel high-adhesion organic anti-corrosion coating.

[0070] Example 3

[0071] This embodiment provides a smooth steel high-adhesion organic anti-corrosion coating and a preparation method thereof, comprising the following steps:

[0072] S1. Axle surface treatment:

[0073] The axle surface was polished with 80 to 1200 g SiC paper to remove surface rust. The axle was then degreased with 3 mol potassium hydroxide solution at 80°C for 15 minutes. The axle was washed with distilled water and then with ethanol. The axle was then dried at room temperature for 1 hour and heat treated at 600°C for 3 hours to obtain a uniform and dense iron oxide layer of 8 μm on the smooth axle surface.

[0074] S2. Zinc powder surface treatment:

[0075] 10.0 g of original zinc powder was dispersed in 1000 ml of an indole-3-butyric acid aqueous solution with a concentration of 22 mg / ml to form a suspension. The suspension was stirred at 70°C for 24 h, and the precipitate was filtered and washed with water. The suspension was dried in a vacuum oven at 80°C for 2 days to obtain a dried powder. 10 g of the powder was dispersed in 100 ml of an acetone solution and magnetically stirred under ultrasonic assistance for 1 h. 5 g of APTES was added and the reaction was continued at room temperature for 12 h. The precipitate was filtered and washed with ethanol. The mixture was dried in a vacuum oven at 60°C for 24 h to obtain a double-modified zinc powder.

[0076] S3. Preparation of epoxy zinc-rich primer:

[0077] Disperse the double-modified zinc powder obtained in step S2 in xylene and disperse it evenly under mechanical stirring, add E51 epoxy resin, dissolve and disperse it, continue to add defoaming agent and leveling agent, and stir until it is evenly dispersed to obtain epoxy zinc-rich primer;

[0078] Dissolving triethylenetetramine in xylene to prepare a 90% triethylenetetramine xylene solution as a curing system for the epoxy zinc-rich primer;

[0079] The double-modified zinc powder accounts for 72% of the epoxy zinc-rich primer; the solid content of the epoxy zinc-rich primer is 53%;

[0080] S4. Preparation of high-humidity and heat-resistant polyurethane topcoat:

[0081] 150g of titanium dioxide was dispersed in xylene and dispersed evenly under mechanical stirring. 161g of NL387-6-70 polyester resin and 58g of PVR-102 resin were added thereto and dissolved and dispersed. 1g of defoamer and 1g of leveling agent were added thereto and stirred and dispersed evenly to obtain a high-humidity and heat-resistant polyurethane topcoat.

[0082] The titanium dioxide accounts for 40% of the high-humidity and heat-resistant polyurethane topcoat; the solid content of the high-humidity and heat-resistant polyurethane topcoat is 55%;

[0083] S5. Preparation of high adhesion organic anticorrosive coating:

[0084] The epoxy zinc-rich primer curing system prepared in step S3 is added to the epoxy zinc-rich primer prepared in step S3, with the mass ratio of the epoxy zinc-rich primer curing system to the epoxy zinc-rich primer being 1:6, and mechanically stirred to be uniform. The mixture is sprayed onto the smooth axle surface heat-treated in step S1, dried naturally for 24 hours, and heat-cured at 80° C. for 1 hour to obtain a heat-cured axle.

[0085] Add 90% HDI xylene solution to the polyurethane topcoat prepared in step S4, the mass ratio of the 90% HDI xylene solution to the polyurethane topcoat being 1:15, mechanically stir evenly, spray onto the heat-cured axle, and naturally dry for 48 hours to obtain a smooth steel high-adhesion organic anti-corrosion coating.

[0086] Example 4

[0087] This embodiment provides a smooth steel high-adhesion organic anti-corrosion coating and a preparation method thereof, comprising the following steps:

[0088] S1. Axle surface treatment:

[0089] The axle surface was polished with 80 to 1200 g SiC paper to remove surface rust. The axle was then degreased with 3 mol potassium hydroxide solution at 80°C for 15 minutes. The axle was washed with distilled water and then with ethanol. The axle was then dried at room temperature for 1 hour and heat treated at 600°C for 3 hours to obtain a uniform and dense iron oxide layer of 8 μm on the smooth axle surface.

[0090] S2. Zinc powder surface treatment:

[0091] 10.0 g of original zinc powder was dispersed in 1000 ml of an indole-3-butyric acid aqueous solution with a concentration of 22 mg / ml to form a suspension. The suspension was stirred at 70°C for 24 h, and the precipitate was filtered and washed with water. The suspension was dried in a vacuum oven at 80°C for 2 days to obtain a dried powder. 10 g of the powder was dispersed in 100 ml of an acetone solution and magnetically stirred under ultrasonic assistance for 1 h. 5 g of APTES was added and the reaction was continued at room temperature for 12 h. The precipitate was filtered and washed with ethanol. The mixture was dried in a vacuum oven at 60°C for 24 h to obtain a double-modified zinc powder.

[0092] S3. Preparation of epoxy zinc-rich primer:

[0093] Disperse the double-modified zinc powder obtained in step S2 in xylene and disperse it evenly under mechanical stirring, add E51 epoxy resin, dissolve and disperse it, continue to add defoaming agent and leveling agent, and stir until it is evenly dispersed to obtain epoxy zinc-rich primer;

[0094] Dissolving triethylenetetramine in xylene to prepare a 90% triethylenetetramine xylene solution as a curing system for the epoxy zinc-rich primer;

[0095] The double-modified zinc powder accounts for 72% of the epoxy zinc-rich primer; the solid content of the epoxy zinc-rich primer is 53%;

[0096] S4. Preparation of high-humidity and heat-resistant polyurethane topcoat:

[0097] 150g of titanium dioxide was dispersed in xylene and dispersed evenly under mechanical stirring. 161g of NL387-6-70 polyester resin and 58g of PVR-102 resin were added thereto and dissolved and dispersed. 1g of defoamer and 1g of leveling agent were added thereto and stirred and dispersed evenly to obtain a high-humidity and heat-resistant polyurethane topcoat.

[0098] The titanium dioxide accounts for 40% of the high-humidity and heat-resistant polyurethane topcoat; the solid content of the high-humidity and heat-resistant polyurethane topcoat is 55%;

[0099] S5. Preparation of high adhesion organic anticorrosive coating:

[0100] The epoxy zinc-rich primer curing system prepared in step S3 is added to the epoxy zinc-rich primer prepared in step S3, with the mass ratio of the epoxy zinc-rich primer curing system to the epoxy zinc-rich primer being 1:6, and mechanically stirred to be uniform. The mixture is sprayed onto the smooth axle surface heat-treated in step S1, dried naturally for 24 hours, and heat-cured at 80° C. for 1 hour to obtain a heat-cured axle.

[0101] Add 90% HDI xylene solution to the polyurethane topcoat prepared in step S4, the mass ratio of the 90% HDI xylene solution to the polyurethane topcoat being 1:16, mechanically stir evenly, spray onto the heat-cured axle, and naturally dry for 48 hours to obtain a smooth steel high-adhesion organic anti-corrosion coating.

[0102] Comparative Example 1

[0103] This embodiment provides a smooth steel high-adhesion organic anti-corrosion coating and a preparation method thereof, comprising the following steps:

[0104] S1. Axle surface treatment:

[0105] The axle surface was polished with 80 to 1200 g SiC paper to remove surface rust. The axle was then degreased with 3 mol potassium hydroxide solution at 80°C for 15 minutes. The axle was washed with distilled water and then with ethanol. The axle was then dried at room temperature for 1 hour and heat treated at 600°C for 3 hours to obtain a uniform and dense iron oxide layer of 8 μm on the smooth axle surface.

[0106] S2. Zinc powder surface treatment:

[0107] 10.0 g of original zinc powder was dispersed in 1000 ml of an indole-3-butyric acid aqueous solution with a concentration of 22 mg / ml to form a suspension. The suspension was stirred at 70°C for 24 h, and the precipitate was filtered and washed with water. The suspension was dried in a vacuum oven at 80°C for 2 days to obtain a dried powder. 10 g of the powder was dispersed in 100 ml of an acetone solution and magnetically stirred under ultrasonic assistance for 1 h. 5 g of APTES was added and the reaction was continued at room temperature for 12 h. The precipitate was filtered and washed with ethanol. The mixture was dried in a vacuum oven at 60°C for 24 h to obtain a double-modified zinc powder.

[0108] S3. Preparation of epoxy zinc-rich primer:

[0109] Disperse the double-modified zinc powder obtained in step S2 in xylene and disperse it evenly under mechanical stirring, add E51 epoxy resin, dissolve and disperse it, continue to add defoaming agent and leveling agent, and stir until it is evenly dispersed to obtain epoxy zinc-rich primer;

[0110] Dissolving triethylenetetramine in xylene to prepare a 90% triethylenetetramine xylene solution as a curing system for the epoxy zinc-rich primer;

[0111] The double-modified zinc powder accounts for 72% of the epoxy zinc-rich primer; the solid content of the epoxy zinc-rich primer is 53%;

[0112] S4. Preparation of high-humidity and heat-resistant polyurethane topcoat:

[0113] 150g of titanium dioxide was dispersed in xylene and dispersed evenly under mechanical stirring. 161g of NL387-6-70 polyester resin and 58g of PVR-102 resin were added thereto and dissolved and dispersed. 1g of defoamer and 1g of leveling agent were added thereto and stirred and dispersed evenly to obtain a high-humidity and heat-resistant polyurethane topcoat.

[0114] The titanium dioxide accounts for 40% of the high-humidity and heat-resistant polyurethane topcoat; the solid content of the high-humidity and heat-resistant polyurethane topcoat is 55%;

[0115] S5. Preparation of high adhesion organic anticorrosive coating:

[0116] The epoxy zinc-rich primer curing system prepared in step S3 is added to the epoxy zinc-rich primer prepared in step S3, with the mass ratio of the epoxy zinc-rich primer curing system to the epoxy zinc-rich primer being 1:5, and mechanically stirred to be uniform. The mixture is sprayed onto the smooth axle surface heat-treated in step S1, dried naturally for 24 hours, and heat-cured at 80° C. for 1 hour to obtain a heat-cured axle.

[0117] Add 90% HDI xylene solution to the polyurethane topcoat prepared in step S4, the mass ratio of the 90% HDI xylene solution to the polyurethane topcoat being 1:14, mechanically stir evenly, spray onto the heat-cured axle, and naturally dry for 48 hours to obtain a smooth steel high-adhesion organic anti-corrosion coating.

[0118] Comparative Example 2

[0119] This embodiment provides a smooth steel high-adhesion organic anti-corrosion coating and a preparation method thereof, comprising the following steps:

[0120] S1. Axle surface treatment:

[0121] The axle surface was polished with 80 to 1200 g SiC paper to remove surface rust. The axle was then degreased with 3 mol potassium hydroxide solution at 80°C for 15 minutes. The axle was washed with distilled water and then with ethanol. The axle was then dried at room temperature for 1 hour and heat treated at 600°C for 3 hours to obtain a uniform and dense iron oxide layer of 8 μm on the smooth axle surface.

[0122] S2. Zinc powder surface treatment:

[0123] 10.0 g of original zinc powder was dispersed in 1000 ml of an indole-3-butyric acid aqueous solution with a concentration of 22 mg / ml to form a suspension. The suspension was stirred at 70°C for 24 h, and the precipitate was filtered and washed with water. The suspension was dried in a vacuum oven at 80°C for 2 days to obtain a dried powder. 10 g of the powder was dispersed in 100 ml of an acetone solution and magnetically stirred under ultrasonic assistance for 1 h. 5 g of APTES was added and the reaction was continued at room temperature for 12 h. The precipitate was filtered and washed with ethanol. The mixture was dried in a vacuum oven at 60°C for 24 h to obtain a double-modified zinc powder.

[0124] S3. Preparation of epoxy zinc-rich primer:

[0125] Disperse the double-modified zinc powder obtained in step S2 in xylene and disperse it evenly under mechanical stirring, add E51 epoxy resin, dissolve and disperse it, continue to add defoaming agent and leveling agent, and stir until it is evenly dispersed to obtain epoxy zinc-rich primer;

[0126] Dissolving triethylenetetramine in xylene to prepare a 90% triethylenetetramine xylene solution as a curing system for the epoxy zinc-rich primer;

[0127] The double-modified zinc powder accounts for 72% of the epoxy zinc-rich primer; the solid content of the epoxy zinc-rich primer is 53%;

[0128] S4. Preparation of high-humidity and heat-resistant polyurethane topcoat:

[0129] 150g of titanium dioxide was dispersed in xylene and dispersed evenly under mechanical stirring. 161g of NL387-6-70 polyester resin and 58g of PVR-102 resin were added thereto and dissolved and dispersed. 1g of defoamer and 1g of leveling agent were added thereto and stirred and dispersed evenly to obtain a high-humidity and heat-resistant polyurethane topcoat.

[0130] The titanium dioxide accounts for 40% of the high-humidity and heat-resistant polyurethane topcoat; the solid content of the high-humidity and heat-resistant polyurethane topcoat is 55%;

[0131] S5. Preparation of high adhesion organic anticorrosive coating:

[0132] The epoxy zinc-rich primer curing system prepared in step S3 is added to the epoxy zinc-rich primer prepared in step S3, with the mass ratio of the epoxy zinc-rich primer curing system to the epoxy zinc-rich primer being 1:5, and mechanically stirred to be uniform. The mixture is sprayed onto the smooth axle surface heat-treated in step S1, dried naturally for 24 hours, and heat-cured at 80° C. for 1 hour to obtain a heat-cured axle.

[0133] Add 90% HDI xylene solution to the polyurethane topcoat prepared in step S4, the mass ratio of the 90% HDI xylene solution to the polyurethane topcoat being 1:17, mechanically stir evenly, spray onto the heat-cured axle, and naturally dry for 48 hours to obtain a smooth steel high-adhesion organic anti-corrosion coating.

[0134] Comparative Example 3

[0135] This embodiment provides a smooth steel high-adhesion organic anti-corrosion coating and a preparation method thereof, comprising the following steps:

[0136] S1. Axle surface treatment:

[0137] The axle surface was polished with 80 to 1200 g SiC paper to remove surface rust. The axle was then degreased with 3 mol potassium hydroxide solution at 80°C for 15 minutes. The axle was washed with distilled water and then with ethanol. The axle was then dried at room temperature for 1 hour and heat treated at 600°C for 3 hours to obtain a uniform and dense iron oxide layer of 8 μm on the smooth axle surface.

[0138] S2. Zinc powder surface treatment:

[0139] 10.0 g of original zinc powder was dispersed in 1000 ml of an indole-3-butyric acid aqueous solution with a concentration of 22 mg / ml to form a suspension. The suspension was stirred at 70°C for 24 h, and the precipitate was filtered and washed with water. The suspension was dried in a vacuum oven at 80°C for 2 days to obtain a dried powder. 10 g of the powder was dispersed in 100 ml of an acetone solution and magnetically stirred under ultrasonic assistance for 1 h. 5 g of APTES was added and the reaction was continued at room temperature for 12 h. The precipitate was filtered and washed with ethanol. The mixture was dried in a vacuum oven at 60°C for 24 h to obtain a double-modified zinc powder.

[0140] S3. Preparation of epoxy zinc-rich primer:

[0141] Disperse the double-modified zinc powder obtained in step S2 in xylene and disperse it evenly under mechanical stirring, add E51 epoxy resin, dissolve and disperse it, continue to add defoaming agent and leveling agent, and stir until it is evenly dispersed to obtain epoxy zinc-rich primer;

[0142] Dissolving triethylenetetramine in xylene to prepare a 90% triethylenetetramine xylene solution as a curing system for the epoxy zinc-rich primer;

[0143] The double-modified zinc powder accounts for 72% of the epoxy zinc-rich primer; the solid content of the epoxy zinc-rich primer is 53%;

[0144] S4. Preparation of high-humidity and heat-resistant polyurethane topcoat:

[0145] 150g of titanium dioxide was dispersed in xylene and dispersed evenly under mechanical stirring. 161g of NL387-6-70 polyester resin and 58g of PVR-102 resin were added thereto and dissolved and dispersed. 1g of defoamer and 1g of leveling agent were added thereto and stirred and dispersed evenly to obtain a high-humidity and heat-resistant polyurethane topcoat.

[0146] The titanium dioxide accounts for 40% of the high-humidity and heat-resistant polyurethane topcoat; the solid content of the high-humidity and heat-resistant polyurethane topcoat is 55%;

[0147] S5. Preparation of high adhesion organic anticorrosive coating:

[0148] The epoxy zinc-rich primer curing system prepared in step S3 is added to the epoxy zinc-rich primer prepared in step S3, with the mass ratio of the epoxy zinc-rich primer curing system to the epoxy zinc-rich primer being 1:4, and mechanically stirred to be uniform. The mixture is sprayed onto the smooth axle surface heat-treated in step S1, dried naturally for 24 hours, and heat-cured at 80° C. for 1 hour to obtain a heat-cured axle.

[0149] Add 90% HDI xylene solution to the polyurethane topcoat prepared in step S4, the mass ratio of the 90% HDI xylene solution to the polyurethane topcoat being 1:15, mechanically stir evenly, spray onto the heat-cured axle, and naturally dry for 48 hours to obtain a smooth steel high-adhesion organic anti-corrosion coating.

[0150] Comparative Example 4

[0151] This embodiment provides a smooth steel high-adhesion organic anti-corrosion coating and a preparation method thereof, comprising the following steps:

[0152] S1. Axle surface treatment:

[0153] The axle surface was polished with 80 to 1200 g SiC paper to remove surface rust. The axle was then degreased with 3 mol potassium hydroxide solution at 80°C for 15 minutes. The axle was washed with distilled water and then with ethanol. The axle was then dried at room temperature for 1 hour and heat treated at 600°C for 3 hours to obtain a uniform and dense iron oxide layer of 8 μm on the smooth axle surface.

[0154] S2. Zinc powder surface treatment:

[0155] 10.0 g of original zinc powder was dispersed in 1000 ml of an indole-3-butyric acid aqueous solution with a concentration of 22 mg / ml to form a suspension. The suspension was stirred at 70°C for 24 h, and the precipitate was filtered and washed with water. The suspension was dried in a vacuum oven at 80°C for 2 days to obtain a dried powder. 10 g of the powder was dispersed in 100 ml of an acetone solution and magnetically stirred under ultrasonic assistance for 1 h. 5 g of APTES was added and the reaction was continued at room temperature for 12 h. The precipitate was filtered and washed with ethanol. The mixture was dried in a vacuum oven at 60°C for 24 h to obtain a double-modified zinc powder.

[0156] S3. Preparation of epoxy zinc-rich primer:

[0157] Disperse the double-modified zinc powder obtained in step S2 in xylene and disperse it evenly under mechanical stirring, add E51 epoxy resin, dissolve and disperse it, continue to add defoaming agent and leveling agent, and stir until it is evenly dispersed to obtain epoxy zinc-rich primer;

[0158] Dissolving triethylenetetramine in xylene to prepare a 90% triethylenetetramine xylene solution as a curing system for the epoxy zinc-rich primer;

[0159] The double-modified zinc powder accounts for 72% of the epoxy zinc-rich primer; the solid content of the epoxy zinc-rich primer is 53%;

[0160] S4. Preparation of high-humidity and heat-resistant polyurethane topcoat:

[0161] 150g of titanium dioxide was dispersed in xylene and dispersed evenly under mechanical stirring. 161g of NL387-6-70 polyester resin and 58g of PVR-102 resin were added thereto and dissolved and dispersed. 1g of defoamer and 1g of leveling agent were added thereto and stirred and dispersed evenly to obtain a high-humidity and heat-resistant polyurethane topcoat.

[0162] The titanium dioxide accounts for 40% of the high-humidity and heat-resistant polyurethane topcoat; the solid content of the high-humidity and heat-resistant polyurethane topcoat is 55%;

[0163] S5. Preparation of high adhesion organic anticorrosive coating:

[0164] The epoxy zinc-rich primer curing system prepared in step S3 is added to the epoxy zinc-rich primer prepared in step S3, with the mass ratio of the epoxy zinc-rich primer curing system to the epoxy zinc-rich primer being 1:7, and mechanically stirred to be uniform. The mixture is sprayed onto the smooth axle surface heat-treated in step S1, dried naturally for 24 hours, and heat-cured at 80° C. for 1 hour to obtain a heat-cured axle.

[0165] Add 90% HDI xylene solution to the polyurethane topcoat prepared in step S4, the mass ratio of the 90% HDI xylene solution to the polyurethane topcoat being 1:15, mechanically stir evenly, spray onto the heat-cured axle, and naturally dry for 48 hours to obtain a smooth steel high-adhesion organic anti-corrosion coating.

[0166] Comparative Example 5

[0167] This comparative example is carried out on the basis of the above-mentioned Example 1, and the similarities with the above-mentioned Example 1 are not repeated here.

[0168] In this comparative example, a traditional polyamide resin curing agent was used as the curing system.

[0169] Comparative Example 6

[0170] This comparative example is carried out on the basis of the above-mentioned Example 1, and the similarities with the above-mentioned Example 1 are not repeated here.

[0171] In this comparative example, unmodified zinc powder was added with a dispersant.

[0172] Comparative Example 7

[0173] This comparative example is carried out on the basis of the above-mentioned Example 1, and the similarities with the above-mentioned Example 1 are not repeated here.

[0174] In this comparative example, the metal surface was not subjected to high temperature treatment.

[0175] The test results of the smooth steel high-adhesion organic anti-corrosion coatings prepared in the above examples and comparative examples are listed in Table 1.

[0176] Table 1

[0177]

[0178] Adhesion was evaluated by the pull-off method; corrosion resistance was evaluated by the electrochemical method; and heat and humidity resistance was evaluated by the cross-hatch method (0 to 4 levels, with lower levels increasing adhesion) under the test conditions of 90% humidity and 80°C for 48 hours.

[0179] As can be seen from the above table, Example 1 and Comparative Example 1 and Comparative Example 2 show that the mass ratio of 90% HDI xylene solution to polyurethane topcoat will affect the performance of the high-adhesion organic anti-corrosion coating for smooth steel. When the curing system in the polyurethane topcoat is too much or too little, not only its corrosion resistance is reduced, but also its resistance to moisture and heat is greatly reduced. This is attributed to the fact that too much curing system does not participate in the reaction, and the small molecule curing agent reacts with water, causing the coating to be damaged. Too little curing system leads to too low a cross-linking density of the resin, and the molecular chain is easy to move at high temperature, causing water or water vapor to easily penetrate the organic coating and damage the epoxy primer coating, thereby causing damage to the organic coating; Example 1 and Comparative Example 3 and Comparative Example 4 It can be seen that the epoxy zinc-rich primer curing system and the mass ratio of the epoxy zinc-rich primer will affect the performance of the high-adhesion organic anti-corrosion coating on smooth steel. When the curing system of the epoxy primer is too much or too little, the adhesion, corrosion resistance and moisture and heat resistance will be greatly reduced. Too much curing system will form small molecule doping in the epoxy primer. These free small molecules will not only reduce the mechanical properties of the organic coating, but also reduce its barrier properties, thereby causing various performance degradations; too little curing system will lead to a low cross-linking density of the epoxy resin curing, which will also lead to a reduction in the mechanical and barrier properties of the organic coating, and reduce the interfacial force between the coating and the metal substrate, thereby affecting its various performances. Further by comparing Example 1 with Comparative Examples 3 to 5, although too much or too little use of the triethylenetetramine curing system will cause the performance of the organic coating to deteriorate, it has better comprehensive performance than the traditional zinc-rich epoxy primer with polyamide resin curing agent. This is attributed to the fact that the triethylenetetramine multi-group can form multi-dimensional cross-linking and has the effect of an interface promoter (in which a large number of amino groups react with the epoxy resin and can also react with the oxygen groups on the surface of the oxidized metal substrate to form an interface bridging effect). Comparison between Example 1 and Comparative Example 6 shows that the surface modification of zinc powder will also affect the performance of the high-adhesion organic anti-corrosion coating for smooth steel. The results show that the comprehensive performance of the unmodified zinc powder-doped organic coating is similar to that of the existing commercial or reported ones, while after double modification, the corrosion resistance and adhesion are greatly improved, especially the moisture and heat resistance (this performance is rarely reported in traditional organic anti-corrosion coatings). The unmodified zinc powder-doped organic coating that was unqualified (>Grade 1) becomes excellent in moisture and heat resistance (Grade 0, the highest level). This result is attributed to the fact that the double-modified zinc powder can greatly improve the interfacial force between the zinc powder and the resin substrate and the metal substrate, thereby improving the density, mechanical stability and adhesion of the coating. In particular, the hydrophobicity is improved after modification, combined with the high density and cross-linking degree, thereby greatly improving its moisture and heat resistance. This phenomenon is difficult to see in traditional organic protective coatings.Comparison between Example 1 and Comparative Example 7 shows that high-temperature treatment of a smooth metal surface after cleaning will also affect the performance of the high-adhesion organic anti-corrosion coating on smooth steel. The results show that the adhesion, corrosion resistance, and moisture and heat resistance of the surface organic coating of metals that have not been subjected to high-temperature treatment are relatively low, especially the moisture and heat resistance performance is reduced to level 3. This result is attributed to the reduced oxygen content of the untreated metal surface, which cannot form a large amount of physical or chemical bonding between the organic coating and the metal substrate.

[0180] In summary, the present invention combines alkaline solution and heat treatment processes to increase the oxygen atom content of traditional smooth metal surfaces, thereby improving the chemical and physical bonding between the organic coating and the metal substrate, avoiding the strategy of traditional organic coatings using mechanical twisting and bonding to improve adhesion, and solving the problem that traditional organic anti-corrosion coatings cannot be used for the protection of smooth metal surfaces; at the same time, E51 and triethylenetetramine are used as the base resin and curing system of the organic coating, respectively, to have a better cross-linking density and improve the density of the coating; at the same time, the triethylenetetramine not only serves as the curing system of the epoxy resin, but also has a bridging effect between the epoxy resin and the metal substrate; the present invention uses indole-3-butyric acid and APTE S double-modified Zn powder improves the dispersibility and stability of Zn powder in epoxy resin solution, while improving the compatibility and interfacial force between Zn powder and epoxy resin, further improving the density of the coating while also improving the mechanical properties and barrier properties; and by improving the mechanical strength and hydrophobicity of the epoxy zinc-rich primer, and the bonding effect between zinc powder and the metal substrate, further improving the adhesion between the primer and the substrate; the present invention adopts a high-humidity and heat-resistant polyurethane coating as a topcoat, which improves the moisture and heat resistance of the polyurethane coating, effectively solving the problem that the paint on the smooth wheel axle surface is easily peeled off during use, and further improving the adhesion between the organic coating and the smooth-surface wheel axle.

[0181] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a smooth steel high-adhesion organic anti-corrosion coating, characterized in that: The steps include: S1. Axle surface treatment: The axle surface is polished with 80-1200 mesh SiC paper to remove surface rust. The axle is then degreased with 3 mol potassium hydroxide solution at 75-85°C for 15-18 minutes. The axle is then washed with distilled water and then with ethanol. The axle is then dried at room temperature for 1-1.5 hours and heat treated at 600-650°C for 1-3 hours to obtain a uniform, dense iron oxide layer of 5-10 microns on the smooth axle surface. S2. Zinc powder surface treatment: 10-12 g of original zinc powder was dispersed in 1000-1100 ml of indole-3-butyric acid aqueous solution to form a suspension. The suspension was stirred at 65-75° C. for 24-28 h, the precipitate was filtered and washed with water, and dried in a vacuum oven at 75-85° C. for 2-2.5 d to obtain a dried powder. 10-12 g of the powder was dispersed in 100-110 ml of acetone solution and magnetically stirred under ultrasound assistance for 1-2 h. 3-aminopropyltriethoxysilane was added and the reaction was continued at room temperature for 12-16 h. The precipitate was filtered and washed with ethanol, and dried in a vacuum oven at 55-65° C. for 24-28 h to obtain a double-modified zinc powder. S3. Preparation of epoxy zinc-rich primer: Disperse the double-modified zinc powder obtained in step S2 in xylene and disperse it evenly under mechanical stirring, add E51 epoxy resin, dissolve and disperse it, continue to add defoaming agent and leveling agent, and stir until it is evenly dispersed to obtain epoxy zinc-rich primer; Dissolve triethylenetetramine in xylene to prepare a 90% triethylenetetramine xylene solution, which is used as the epoxy zinc-rich primer curing system; S4. Preparation of high-humidity and heat-resistant polyurethane topcoat: Disperse 150-155g of titanium dioxide in xylene and disperse evenly under mechanical stirring. Add 160-165g of NL387-6-70 polyester resin and 56-60g of PVR-102 polyester resin to the mixture and dissolve and disperse them. Then, add 1-2g of defoamer and 1-2g of leveling agent to the mixture and stir and disperse evenly to obtain a high-humidity and heat-resistant polyurethane topcoat. S5. Preparation of high adhesion organic anticorrosive coating: The epoxy zinc-rich primer curing system prepared in step S3 is added to the epoxy zinc-rich primer prepared in step S3, mechanically stirred evenly, and sprayed onto the smooth wheel axle surface heat-treated in step S1, naturally dried for 24-28 hours, and heat-cured at 75-85°C for 1-2 hours to obtain a high-adhesion epoxy zinc-rich primer protective coating; Add 90% HDI xylene solution to the polyurethane topcoat prepared in step S4, stir mechanically to evenly mix, spray the high-adhesion epoxy zinc-rich primer protective coating surface on the above-mentioned axle, and dry naturally for 48-56 hours to obtain a smooth steel high-adhesion organic anti-corrosion coating; The mass ratio of the epoxy zinc-rich primer curing system added to the epoxy zinc-rich primer in step S5 is the mass ratio of triethylenetetramine to the E51 epoxy resin, and the mass ratio is 1:5-6; The mass ratio of the 90% HDI xylene solution to the polyurethane topcoat in step S5 is 1:15-16.

2. The method for preparing a smooth steel high-adhesion organic anti-corrosion coating according to claim 1, characterized in that: The D50 of the original zinc powder in step S2 is 5-10 microns; the concentration of the indole-3-butyric acid aqueous solution is 20-25 mg / ml.

3. The method for preparing a smooth high-adhesion organic anti-corrosion coating for steel according to claim 1, characterized in that: The double-modified zinc powder in step S3 accounts for 70-75% of the epoxy zinc-rich primer; the solid content of the epoxy zinc-rich primer is 50-55%.

4. The method for preparing a smooth high-adhesion organic anti-corrosion coating for steel according to claim 1, wherein: In step S4, the titanium dioxide accounts for 40-45% of the high-humidity and heat-resistant polyurethane topcoat; and the solid content of the high-humidity and heat-resistant polyurethane topcoat is 50-55%.

5. The smooth steel high-adhesion organic anti-corrosion coating prepared by the preparation method of the smooth steel high-adhesion organic anti-corrosion coating as described in any one of claims 1 to 4.

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