Rust coating as well as preparation method and use method thereof

Abstract

The invention provides an on-rust coating as well as a preparation method and a use method thereof, and particularly relates to the technical field of coatings. The rusted coating comprises a first component and a second component, wherein the first component comprises the following raw materials in parts by weight: 9-14 parts of demineralized water, 0.01-0.05 part of a surfactant, 40-50 parts of an acrylic emulsion, 3-6 parts of a penetrant, 4-8 parts of a rust conversion agent and 0.1-0.5 part of a coalescing agent; the second component comprises the following raw materials in parts by weight: 1-2 parts of demineralized water, 1-2 parts of ethanol, 1-2 parts of a complexing agent, 3-7 parts of butyl acetate, 5-10 parts of polyurethane and 5-10 parts of zinc powder; the first component and the second component cooperate with each other to achieve efficient and reliable protection of the rusted steel structure.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a rust-resistant coating, its preparation method, and its application method. Background Technology

[0002] In the field of steel structure protection, painting for corrosion protection is one of the most widely used processes. To ensure the coating effectively performs its anti-corrosion function and extends the service life of the steel structure, rigorous pretreatment of the surface to be coated is essential. In existing technologies, the pretreatment process typically includes a series of continuous steps such as grinding and rust removal, sandblasting, and cleaning. The industry generally requires surface treatment quality to meet Sa2.5 or St3 standards to ensure the stability of the bond between the coating and the substrate. For steel structure areas accessible to personnel and tools, implementing surface treatment is not difficult. However, in actual engineering scenarios, there are many areas that are difficult for personnel and tools to access or high-risk work areas, such as the interior of containers, high-altitude steel towers, and gaps in steel structures. In these special areas, existing surface pretreatment processes are extremely difficult to implement, and may even be unable to achieve effective surface pretreatment. This results in the steel structures in these areas not receiving reliable paint protection, seriously affecting the overall safety and service life of the steel structure.

[0003] Currently, various types of rust-resistant coatings have emerged, which are coatings that can be applied directly without rust removal. However, in the actual promotion and application of these rust-resistant coatings, there are still many insurmountable defects: First, it is difficult to accurately control the amount of the coating itself or the amount of rust-transfer agent in it. Insufficient amount will lead to incomplete rust conversion, and the residual rust will continue to corrode the steel substrate, failing to guarantee the anti-corrosion effect; excessive amount will cause excessive corrosion to the steel substrate, damaging the integrity of the substrate structure. Second, the adhesion between the coating and the substrate is poor. Incomplete rust conversion or poor coating penetration will result in a void layer at the interface between the rust layer and the substrate. The void layer cannot provide sufficient adhesion, causing the coating to easily peel off, seriously affecting the protective reliability and durability of the rust-resistant coating.

[0004] Therefore, there is a need to provide a rust-resistant coating, its preparation method, and its application method to improve the above-mentioned problems. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a rust-resistant coating and its preparation and application methods to improve the technical problem of poor adhesion of existing coatings.

[0006] To achieve the above and other related objectives, the present invention provides a rust-resistant coating, comprising: a first component and a second component. The first component comprises the following raw materials in parts by weight: 9-14 parts demineralized water, 0.01-0.05 parts surfactant, 40-50 parts acrylic emulsion, 3-6 parts penetrant, 4-8 parts rust-transfer agent, 0.1-0.5 parts film-forming aid, and 4 parts ethanol, wherein the film-forming aid is dissolved in a mixed solvent of the demineralized water and the ethanol. The second component comprises the following raw materials in parts by weight: 1-2 parts demineralized water, 1-2 parts ethanol, 1-2 parts complexing agent, 3-7 parts butyl acetate, 5-10 parts polyurethane, and 5-10 parts zinc powder.

[0007] In one embodiment of the present invention, the surfactant is selected from sodium dodecylbenzenesulfonate or a mixture of sodium dodecylbenzenesulfonate and fatty alcohol vinyl ether.

[0008] In one embodiment of the present invention, the penetrant is selected from propylene glycol or a mixture of propylene glycol and ethanol.

[0009] In one embodiment of the present invention, the rust-reducing agent includes one or more of gallic acid, citric acid, phosphoric acid, and tannic acid.

[0010] In one embodiment of the present invention, the film-forming aid includes one or more of BYK381 and BYK3560.

[0011] In one embodiment of the present invention, the complexing agent includes one or more of sodium trimethylphosphonate and disodium ethylenediaminetetraacetate.

[0012] In one embodiment of the present invention, the solid content of the acrylic emulsion is 50% to 60%.

[0013] In one embodiment of the present invention, the conductivity of the deionized water is ≤200μs / cm, and the suspended solids in the deionized water are <50mg / kg.

[0014] In one embodiment of the present invention, the zinc powder includes zinc powder with a first particle size and zinc powder with a second particle size, wherein the mass ratio of the zinc powder with the first particle size to the zinc powder with the second particle size is (1~3):1, the particle size of the zinc powder with the first particle size is 1~3μm, and the particle size of the zinc powder with the second particle size is 0.5~1μm.

[0015] The present invention also provides a method for preparing a rust-resistant coating, the method comprising the following steps:

[0016] The raw materials of the first component are mixed in a set ratio to prepare the first component; The raw materials of the second component are mixed in a set ratio to prepare the second component.

[0017] In one embodiment of the present invention, the step of preparing the first component includes: Take 5-10 parts of deionized water, preheat it to 40-70℃, then add 0.01-0.05 parts of surfactant, mix well, then lower the temperature of the mixed solution to 45-55℃, add 40-50 parts of acrylic emulsion to form a primer film. Mix 3-6 parts of penetrant and 4-8 parts of rust-converting agent evenly, maintain the temperature at 45-55℃, and add 5-10 parts of primer film-forming agent to form primer conversion agent; The remaining primer film-forming material and the primer rust conversion agent are mixed evenly at 45-55°C. Then, 0.1-0.5 parts of film-forming aid, which have been pre-dissolved in a mixed solution of 4 parts deionized water and 4 parts ethanol, are added and mixed to form the first component.

[0018] In one embodiment of the present invention, the step of preparing the second component includes: Mix 1-2 parts of deionized water with 1-2 parts of ethanol until homogeneous, add 1-2 parts of complexing agent and stir until dissolved, then add 1-2 parts of butyl acetate and mix until homogeneous to form a complexing agent solution. Mix 5-10 parts of polyurethane with 2-5 parts of butyl acetate until uniform, add 5-10 parts of zinc powder and stir until uniform to form a suspension resin liquid; The complexing agent solution is added to the suspended resin liquid and stirred until homogeneous to form the second component.

[0019] The present invention also provides a method for using a rust-resistant coating, the method comprising the following steps: The steel structure surface to be treated is pretreated to remove dust and loose rust. After the first component is mixed evenly with the curing agent, it is applied to the surface of the steel structure to form a primer; After the second component is mixed evenly with the curing agent, it is applied to the surface of the primer to form an intermediate coat; After the intermediate paint has cured, apply the topcoat.

[0020] In one embodiment of the present invention, the rust layer thickness of the steel structure surface to be treated is less than 0.5 mm, and 1 to 2 coats of the first component are applied; the rust layer thickness of the steel structure surface to be treated is 0.5 mm to 1 mm, and 3 to 5 coats of the first component are applied; the rust layer thickness of the steel structure surface to be treated is greater than 1 mm, and 3 to 4 coats of the first component are applied for every 1 mm, with a time interval of 2 to 3 minutes between each coat.

[0021] In one embodiment of the present invention, the film thickness of the second component is 80~160μm.

[0022] The beneficial effects of this invention: The rust-resistant coating of this invention achieves efficient and reliable protection for rust-resistant steel structures through a two-component synergistic design. This invention uses a matching coating system with a first component as a primer and a second component as an intermediate coat. In this system, the rust-converting agent in the first component reacts chemically with the rust layer on the steel structure surface, causing the loose rust layer to dissolve and generate free iron ions and other metal ions. These free metal ions can react with the complexing agent in the second component to form a stable complex that is embedded between the resins. At the same time, the zinc powder in the second component sinks to the surface of the steel structure substrate to form a sacrificial anode protective layer. The preferential corrosion of the sacrificial zinc powder itself further forms cathodic protection for the steel structure substrate. The synergistic effect of the above-mentioned rust conversion and curing and sacrificial anode protection significantly improves the coating's all-round protection capability for rust-resistant steel structures and significantly extends the service life of the steel structure.

[0023] This invention constructs a unique "underprotection" and "redundant protection" mode by precisely controlling the component ratio and mechanism of action of the two components. On the one hand, it avoids the problems of incomplete rust conversion or excessive corrosion of the substrate caused by the difficulty in controlling the amount of rust-converting agent in existing technologies, achieving "underprotection" control of the substrate and effectively avoiding substrate damage. On the other hand, through the dual protection of rust conversion complexation curing and sacrificial anode, a "redundant protection" effect is formed, ensuring that it can provide stable and long-lasting protection for steel structures even under complex working conditions. In addition, the rust-resistant coating of this invention can be directly applied to the surface of rust-resistant steel structures, eliminating the need for cumbersome surface rust removal treatment of inaccessible areas, high-risk areas, and other special parts, effectively reducing construction difficulty, saving construction costs and time. Moreover, its excellent protective performance and substrate compatibility make it widely applicable to the protection projects of various rust-resistant steel structures, possessing extremely strong practical application value. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0025] In the attached diagram: Figure 1 This is a flowchart of a method for preparing a rust-resistant coating according to an embodiment of the present invention; Figure 2 This is a flowchart of a method for preparing the first component of a rust-resistant coating according to an embodiment of the present invention; Figure 3 This is a flowchart illustrating the preparation method of the second component of a rust-resistant coating provided in one embodiment of the present invention. Figure 4 This is a flowchart illustrating the method of using a rust-resistant coating according to an embodiment of the present invention. Figure 5 These are photographs of a rusty steel structure before and after coating, provided in one embodiment of the present invention. Figure 5 (a) in the image is a photograph of the rusty steel structure before coating. Figure 5 (b) in the image is a photograph of the steel structure after coating. Detailed Implementation

[0026] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0027] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0029] The terms or phrases used in this article have the following meanings: In this article, the terms "multiple," "various," and "multiple times" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0030] In this document, terms such as “preferred,” “ideal,” “further,” “even more,” and “particularly” are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this invention.

[0031] In this document, when referring to numerical ranges, unless otherwise specified, the distribution of selectable values ​​within a numerical range is considered continuous, including the two endpoints of the range (i.e., the minimum and maximum values), and every value between these two endpoints. When multiple numerical ranges are provided to describe a feature or property, these numerical ranges can be combined.

[0032] The first aspect of the present invention provides a rust-resistant coating, which includes a first component and a second component, wherein the first component serves as a primer and the second component serves as an intermediate coat. The matching coating system of the first component and the second component can achieve efficient and reliable protection for rust-resistant steel structures.

[0033] Specifically, the first component comprises the following raw materials in parts by weight: 9-14 parts of demineralized water, 0.01-0.05 parts of surfactant, 40-50 parts of acrylic emulsion, 5-10 parts of penetrant, 4-8 parts of rust remover, and 0.1-0.5 parts of film-forming aid; the second component comprises the following raw materials in parts by weight: 1-2 parts of demineralized water, 1-2 parts of ethanol, 1-2 parts of complexing agent, 3-7 parts of butyl acetate, 5-10 parts of polyurethane, and 5-10 parts of zinc powder.

[0034] Demineralized water refers to water that has undergone physical and chemical water treatment processes to remove various dissolved salt ions, suspended solids, colloids, silt, organic matter, and other harmful impurities. It is the most widely used basic purified water in industrial production. In this application, demineralized water serves as a dispersion and dissolution carrier in the system, effectively dissolving and dispersing components such as acrylic acid solution, penetrant, rust remover, and film-forming aid. The conductivity of the demineralized water in this application is ≤200 μm / cm, and the suspended solids in the demineralized water are <500 mg / kg. The proportions of demineralized water in each component can be adjusted adaptively according to the amount of other raw materials used. For example, the first component may contain 9, 12, or 14 parts of demineralized water, etc. The second component may contain 1, 1.5, or 2 parts of demineralized water, etc.

[0035] Rust remover, as a core functional component in primer, mainly functions to react chemically with the loose rust layer on the surface of steel structure, fully dissolving the rust layer and releasing free iron ions and other metal ions.

[0036] In some embodiments, the rust-reducing agent includes one or more of gallic acid, citric acid, phosphoric acid, and tannic acid. These rust-reducing agents can be used alone or in combination. For example, the rust-reducing agent may be citric acid, gallic acid, a mixture of phosphoric acid and tannic acid, or a mixture of citric acid, phosphoric acid, and tannic acid, etc. Further, the rust-reducing agent may be a mixture of phosphoric acid and tannic acid, and the mass ratio of phosphoric acid to tannic acid in the mixture is (2~4):1, for example, 2:1, 3:1, or 4:1, etc. The purity of these rust-reducing agents is chemically pure or higher.

[0037] Acrylic emulsion, as the core film-forming substance of the primer, can complete film formation and curing after coating by the evaporation of moisture, forming a continuous, dense primer film with excellent adhesion on the rusted surface of the steel structure. In this application, the solid content of the acrylic emulsion is 50%~60%, exemplarily it can be 50%, 55%, or 60%, etc., and its purity is industrial grade or higher. In one embodiment, the number of parts of the acrylic emulsion can be 40 parts, 45 parts, or 50 parts, etc.

[0038] Surfactants are mainly used to modify acrylic emulsions to prevent agglomeration when rust-converting agents are added. In some optional embodiments, the surfactant is selected from anionic surfactants. Anionic surfactants can adsorb onto the surface of latex particles in acrylic emulsions and align themselves, with their hydrophilic groups facing the aqueous phase and their hydrophobic groups facing the interior of the latex particles, forming a stable negatively charged double layer and a steric hindrance protective layer on the surface of the latex particles. When the system becomes acidic due to the addition of an acidic rust-converting agent, the anionic surfactant can prevent charged latex particles from agglomerating by its own charge repulsion. At the same time, the steric hindrance effect of its molecular chains can further prevent collisional agglomeration of latex particles, maintaining the dispersion stability of latex particles in the acidic aqueous system.

[0039] In one embodiment, the surfactant is sodium dodecylbenzenesulfonate (LAS). Preferably, the surfactant is a mixture of sodium dodecylbenzenesulfonate (LAS) and fatty alcohol polyoxyethylene ether (AEO), wherein the mass ratio of LAS to AEO in the mixture is (2~3):1, for example 2:1, 2.5:1 or 3:1, etc. AEO is a neutral nonionic surfactant that can further form a dense steric hindrance protective layer on the surface of latex particles. Combined with the charge repulsion effect of LAS, it forms a dual protection system of charge stability and steric hindrance stability, fundamentally preventing emulsion aggregation. Furthermore, AEO is neutral and will not react with acidic rust-converting agents, nor will it interfere with the core chemical reactions of rust conversion and complexation within the system. It can also improve the dispersibility and wetting properties of the emulsion in aqueous systems, and enhance the overall leveling properties of the coating. Therefore, the combined use of LAS and AEO can further enhance the comprehensive stability of waterborne acrylic emulsions in acidic environments, high-solids systems, and under conditions where rust-converting agents are added, ensuring that the emulsion always maintains a uniform and stable dispersion, providing a reliable guarantee for the film-forming effect and rust conversion reaction efficiency of the coating system.

[0040] In some embodiments, the amount of surfactant may be 0.01 parts, 0.03 parts, 0.1 parts, 0.3 or 0.5 parts, etc.

[0041] Film-forming aids can lower the minimum film-forming temperature of aqueous acrylic emulsions, promote emulsion fusion and cross-linking to form a continuous and dense primer film, and prevent defects such as incomplete film formation, cracking, chalking, and powdering caused by insufficient film-forming temperature. This improves the flexibility, adhesion, and density of the coating, thus providing basic corrosion protection. In some embodiments, the film-forming aid includes one or more of BYK381 and BYK3560. Exemplarily, the film-forming aid is BYK381, BYK3560, or a mixture of BYK381 and BYK3560. In this application, the amount of film-forming aid can be 0.1 parts, 0.3 parts, or 0.5 parts, etc. Furthermore, when adding the film-forming aid, it is first stirred evenly with a mixed solution of ethanol and demineralized water before being added to the first component. This ensures that the film-forming aid is fully dissolved and evenly dispersed, avoiding agglomeration and coating defects. It also significantly improves the compatibility of the film-forming aid with the components of the system, ensuring the stability of the primer system and preventing emulsion demulsification. At the same time, the concentration of the aid can be precisely controlled to ensure that it exerts a uniform film-forming synergistic effect, improving the density and leveling properties of the coating.

[0042] Penetrating agents can enhance the gradient penetration ability of primer components in crevices, enabling rust-removing agents, acrylic emulsions, and other components to deeply penetrate the rust layer, improving the efficiency and thoroughness of the rust-removing reaction, while also improving the wettability and leveling properties of the coating on the substrate surface. For example, the penetrating agent is propylene glycol, or a mixture of propylene glycol and ethanol. When the penetrating agent is a mixture of propylene glycol and ethanol, the mass ratio of propylene glycol to ethanol is (1~2):1, for example, 1:1, 1.5:1, or 2:1, etc. The propylene glycol is of chemical purity or higher, and the ethanol is industrial grade. In some embodiments, the number of parts of the penetrating agent can be 5 parts, 7 parts, 9 parts, or 10 parts, etc.

[0043] The complexing agent in the second component reacts chemically with the rust-removing agent on the steel structure surface, causing the loose rust layer to dissolve and generate free iron ions and other metal ions. The complexing agent then undergoes a complexation reaction with these free metal ions to form a stable complex that is embedded between the resin particles, thereby removing the rust layer from the steel structure surface. In some embodiments, the complexing agent includes one or more of pentasodium aminotrimethylphosphonate (AMTP·Na5) and disodium ethylenediaminetetraacetate (EDTA·2Na). For example, it can be pentasodium aminotrimethylphosphonate, disodium ethylenediaminetetraacetate, or a mixture of pentasodium aminotrimethylphosphonate and disodium ethylenediaminetetraacetate. Preferably, the complexing agent is pentasodium aminotrimethylphosphonate. This complexing agent can, on the one hand, undergo a highly efficient complexing reaction with the free metal ions generated by the rust conversion reaction to form a structurally stable complex. This complex can be uniformly embedded in the resin matrix to achieve the curing and sealing of the rust layer, thus blocking the spread of rust at its source. On the other hand, it also possesses excellent corrosion inhibition properties, adhering tightly to the surface of the steel structure substrate through chemical adsorption to form a dense corrosion-inhibiting adsorption film. This effectively blocks the contact between water, oxygen, and corrosive ions and the substrate, simultaneously providing reliable corrosion inhibition protection for the steel structure. In some embodiments, the amount of the complexing agent in the second component can be 1 part, 1.5 parts, or 2 parts.

[0044] Zinc powder, as a core anti-corrosion component in coating systems, can play a dual role of cathodic protection as a sacrificial anode and physical shielding protection. Firstly, zinc has a much higher metallic activity than iron, and can preferentially undergo oxidation corrosion before steel structure substrates. Through its own sacrificial consumption, it provides long-term cathodic protection for steel structures, completely blocking the rust reaction process of the substrate from an electrochemical level. At the same time, after zinc powder is oxidized, it can generate a dense zinc salt passivation protective film. This protective film can adhere tightly to the surface of the steel structure substrate, further sealing the micropores and rust layer gaps on the substrate surface, forming a stable passivation protective barrier, and significantly delaying the re-corrosion of the substrate. Furthermore, zinc powder can be uniformly dispersed in the coating system and closely adhered to the substrate surface by means of the penetrant and butyl acetate in the system, ensuring the uniformity of the sacrificial anode protection effect. In addition, zinc powder can enhance the mechanical strength, wear resistance and adhesion of the coating, improve the interlayer bonding between the coating film and the steel structure substrate, primer and second component, avoid defects such as peeling and flaking of the coating, and at the same time, it can synergistically improve the weather resistance and salt spray resistance of the coating, significantly extend the long-term protection period of the coating for steel structures, and meet the protection needs of steel structures in outdoor and industrial corrosive environments.

[0045] In one embodiment, the weight percentage of zinc powder in the second component can be 5 parts, 8 parts, or 10 parts, etc. Further, the zinc powder includes zinc powder with a first particle size and zinc powder with a second particle size, wherein the particle size of the first particle size zinc powder is 1~3 μm, for example, 1 μm, 2 μm, or 3 μm, etc.; and the particle size of the second particle size zinc powder is 0.5~1 μm, for example, 0.5 μm, 0.8 μm, or 1 μm, etc. The mass ratio of the first particle size zinc powder to the second particle size zinc powder is (1~3):1, exemplarily, it can be 1:1, 2:1, or 3:1, etc. By using zinc powders of varying particle sizes in combination, a dense packing effect can be achieved through particle size distribution. Larger particle sizes form the coating skeleton and macroscopic cathodic protection network, while smaller particle sizes fill gaps and penetrate minute areas to form microscale protection. Together, they achieve comprehensive physical shielding and sacrificial anode protection without blind spots, significantly improving coating density and corrosion resistance. Simultaneously, it optimizes zinc powder dispersion stability, avoiding the agglomeration and sedimentation problems of single-particle-size particles, and balances coating mechanical strength, adhesion, and application smoothness, comprehensively enhancing the long-term corrosion protection performance of the coating. The purity of the zinc powder is 99% or higher.

[0046] Polyurethane can form a dense and stable coating film on the surface of zinc powder, effectively isolating the zinc powder from direct contact with free iron ions in the system and avoiding unnecessary displacement side reactions. This prevents the zinc powder from being prematurely consumed by free iron ions and losing the core protective performance of the sacrificial anode, while also avoiding the interference of impurities generated by side reactions on the efficient complexation reaction of the rust-converting agent. At the same time, it can avoid the problem of increased porosity and impurity sites inside the coating caused by side reaction products, ensuring the density of the coating and the complexation curing effect.

[0047] In some embodiments, the weight percentage of polyurethane in the second component may be 5 parts, 8 parts, or 10 parts, etc.

[0048] Butyl acetate and polyurethane exhibit good miscibility. Butyl acetate effectively dissolves and uniformly disperses the polyurethane within the system, preventing agglomeration and ensuring the formation of a continuous and dense coating on both large and small-particle zinc powders. This effectively isolates the zinc powder from free iron ions, preventing premature zinc powder loss and ensuring optimal cathodic protection. Furthermore, this miscible system exhibits excellent compatibility with all coating components, without interfering with core reactions such as rust conversion and complexation. Butyl acetate also contributes to solubilization, leveling, and film-forming enhancement, improving the stability of the coating system and its long-term protective effect. In some embodiments, the weight percentage of butyl acetate can be 3 parts, 5 parts, or 7 parts, etc. Both the polyurethane and butyl acetate mentioned above are of industrial grade purity.

[0049] The ethanol in the second component can be combined with demineralized water to form a solubilizing system, improving the dissolution and dispersion of the complexing agent, ensuring efficient complexation reaction, regulating system viscosity, optimizing application leveling, alleviating zinc powder settling issues, reducing system surface tension, and enhancing the interlayer adhesion between the second component and the primer. In some embodiments, the weight parts of ethanol can be 1 part, 1.5 parts, or 2 parts, etc.

[0050] In summary, the rust-resistant coating of the present invention employs a matching coating system with a first component as a primer and a second component as an intermediate coat. The rust-transforming agent in the first component chemically reacts with the rust layer on the steel structure surface, causing the loose rust layer to dissolve and generate free iron ions and other metal ions. These free metal ions can then react with the complexing agent in the second component to form stable complexes that are embedded within the resin. Simultaneously, the zinc powder in the second component sinks to the surface of the steel structure substrate, forming a sacrificial anode protective layer. The preferential corrosion of the sacrificial zinc powder further provides cathodic protection to the steel structure substrate. The synergistic effect of rust conversion and curing with sacrificial anode protection significantly enhances the coating's all-around protection capability for rust-resistant steel structures and significantly extends the service life of the steel structure.

[0051] Please see Figures 1 to 3 The present invention also provides a method for preparing the above-mentioned rust-resistant coating. The preparation method includes at least the steps of preparing a first component and preparing a second component. It should be noted that the types of materials of each raw material in the preparation method are as described in the previous description of the rust-resistant coating, and will not be repeated here.

[0052] Please see Figure 1 and Figure 2 S1. Mix the raw materials of the first component according to the set ratio to prepare the first component, specifically including steps S11 to S13.

[0053] S11. Prepare the primer film-forming material: Take 5-10 parts of deionized water, preheat it to 40-70℃, then add 0.01-0.05 parts of surfactant, mix well, then lower the temperature of the mixed solution to 45-55℃, add 40-50 parts of acrylic emulsion to form a primer film.

[0054] In this step, the preheating temperature of the demineralized water can be 40℃, 50℃, 60℃, or 70℃, etc.; when adding the acrylic emulsion, the temperature of the mixed solution can be 45℃, 50℃, or 55℃, etc. The proportions of the above raw materials can be selected within the above range according to actual needs. Preferably, the proportions of the raw materials are: 7.5 parts demineralized water, 0.03 parts surfactant, and 50 parts acrylic emulsion with a solid content of 50%, and the surfactant ratio is LAS:AEO = 2.5:1.

[0055] S12. Prepare the primer rust converter: Mix 5-10 parts of penetrant with 4-8 parts of rust-converting agent evenly, maintain the temperature at 45-55℃, and add 5-10 parts of primer film-forming agent to form primer conversion agent.

[0056] In this step, the weight proportions of the penetrant, rust-converting agent, and primer film-forming agent can be arbitrarily selected within the above-mentioned range. In one embodiment, the penetrant is 7.5 parts, and further, the penetrant is a mixture of propylene glycol and ethanol, wherein the weight ratio of propylene glycol to ethanol is 4.5:3; the rust-converting agent is 7 parts, and the rust-converting agent is a mixture of phosphoric acid and tannic acid, wherein the weight ratio of phosphoric acid to tannic acid is 5:2. The mixing temperature of the penetrant and the rust-converting agent can be 45°C, 50°C, or 55°C. After the two are mixed evenly, the primer film-forming agent obtained in step S1 is slowly added, and the weight proportions added can be, for example, 5 parts, 8 parts, or 10 parts, to form a primer conversion agent.

[0057] S13, Mixed primer film-forming agent and primer rust-converting agent: After mixing the remaining primer film-forming material and primer rust conversion agent evenly at a temperature of 45~55℃, add 0.1~0.5 parts of film-forming aid to form the first component (primer component).

[0058] This step involves mixing the remaining primer film-forming material from step S11 with the primer conversion agent obtained in step S12 at a temperature of 45°C, 50°C, or 55°C until homogeneous. Then, a film-forming aid is added, and the mixture is allowed to stand for at least 2 hours. The amount of film-forming aid added by weight can be, for example, 0.1 parts, 0.3 parts, or 0.5 parts, etc.

[0059] Preferably, before adding the film-forming aid, it is first dissolved in a mixed solution of ethanol and demineralized water. Then, the solution containing the film-forming aid is added dropwise to the mixed solution of the primer film-forming agent and the primer conversion agent. This ensures the full dissolution and uniform dispersion of the film-forming aid, preventing agglomeration and coating defects, significantly improving the compatibility of the film-forming aid with the components of the system, ensuring the stability of the primer system and preventing emulsion demulsification. Simultaneously, the concentration of the aid can be precisely controlled to ensure its uniform film-forming synergistic effect, improving coating density and leveling properties. In one embodiment, the film-forming aid is 0.3 parts by weight, and the ethanol and demineralized water used to dissolve the film-forming aid are each 4 parts.

[0060] Please see Figure 1 and Figure 3 S2. Mix the raw materials of the second component according to the set ratio to prepare the second component, specifically including steps S21 to S23.

[0061] S21. Mix 1-2 parts of deionized water with 1-2 parts of ethanol evenly, add 1-2 parts of complexing agent and stir until dissolved, then add 1-2 parts of butyl acetate and mix evenly to form a complexing agent solution.

[0062] In this step, the amounts of demineralized water, ethanol, complexing agent, and butyl acetate added can be arbitrarily selected within the range of their respective weight parts. In one embodiment, the weight ratio of demineralized water, ethanol, complexing agent, and butyl acetate is 1.5:1.5:1.5:1.5, that is, each raw material is 1.5 parts.

[0063] S22. Mix 5-10 parts of polyurethane with 2-5 parts of butyl acetate evenly, add 5-10 parts of zinc powder and stir to form a suspension resin liquid.

[0064] In this step, the amounts of polyurethane, butyl acetate, and zinc powder can be arbitrarily selected within the aforementioned weight ratio ranges. In one embodiment, the weight ratio of polyurethane to butyl acetate is 8:4, i.e., 8 parts of polyurethane and 4 parts of butyl acetate. A total of 7 parts of zinc powder are used, with 3.5 parts each of the first-size zinc powder (large-size zinc powder) and the second-size zinc powder (small-size zinc powder). The small-size zinc powder can fill the surface voids of the large-size zinc powder, making the zinc powder sacrificial anode protection area a continuous whole. It should be noted that the zinc powder needs to be uniformly dispersed in the suspension resin solution for at least 10-20 minutes to prevent sedimentation during use, which would lead to uneven coating. If stirring is available during use, the usage time can be appropriately extended. The polyurethane used in this embodiment is oil-based polyurethane. In other embodiments, water-based polyurethane can also be used. In this case, an appropriate amount of surfactant suitable for water-based polyurethane needs to be added, and the ethanol content in the second component needs to be adjusted so that the first and second components can be directly and uniformly mixed before use.

[0065] S23. Add the complexing agent solution to the suspension resin liquid and stir evenly to form the second component (intermediate paint).

[0066] This step simply requires adding the complexing agent solution to the suspended resin solution and stirring until homogeneous.

[0067] The method for preparing the rust-resistant coating provided by this invention is simple and easy to operate. The first and second components are used separately. The first component is applied first, and before it reaches a surface-dry state, the second component is applied over it. This allows the complexing agent to penetrate the primer and react with metal ions, while simultaneously allowing zinc powder to settle onto the steel structure surface, forming a sacrificial anode to further protect the steel structure. It should be noted that neither the acrylic emulsion in the first component nor the polyurethane in the second component contains a curing agent. Therefore, before coating, corresponding curing agents must be added to the first and second components. The type and amount of curing agent added to the first component are selected based on the acrylic emulsion, and the type and amount of curing agent added to the second component are selected based on the polyurethane.

[0068] Please see Figure 4 The present invention also provides a method for using the above-mentioned rust-resistant coating, the method comprising at least the following steps: S41. Pre-treat the steel structure surface to be treated to remove dust and loose rust. S42. After mixing the first component with the curing agent evenly, apply it to the surface of the steel structure to form a primer; S43. After mixing the second component with the curing agent evenly, apply it to the surface of the primer to form an intermediate coat; S44. After the intermediate paint has cured, apply the topcoat.

[0069] Specifically, the pretreatment in step S41 involves blowing or wiping the surface of the steel structure to be treated to remove dust and large pieces of loose rust, so as to prevent the primer from not adhering firmly.

[0070] Step S42: First, add an appropriate amount of acrylic resin curing agent to the first component according to the recommended ratio of acrylic emulsion. After mixing evenly, apply it to the pretreated steel structure surface to form a primer. The coating method includes, but is not limited to, brushing or roller coating. The coating thickness is selected according to the thickness of the rust layer on the steel structure surface. For example, if the rust layer thickness is less than 0.5 mm, apply 1-2 coats of primer; if the rust layer thickness is between 0.5 and 1 mm, apply 3-5 coats of primer; if the rust layer thickness is greater than 1 mm, apply 3-4 coats of primer per 1 mm. The thickness of each primer coat is approximately 80 μm, and the time interval between each coat is 2-3 minutes.

[0071] Step S43 involves applying the second component while the primer is still slightly damp (i.e., the primer surface is not completely dry and can still flow; typically, this occurs within 3-5 minutes after primer application at 35°C). The second component must be used within 10 minutes of preparation and completely used within 20 minutes to prevent zinc powder settling. Before application, add an appropriate amount of polyurethane curing agent to the second component according to the recommended polyurethane ratio, mix thoroughly, and then apply to the primer surface to form an intermediate coat. Leveling is required during application, and the second component film thickness should reach 80-160 μm (preferably 160 μm), i.e., 1-2 coats with a 2-3 minute interval between each coat.

[0072] Step S44: After the intermediate paint has completely cured, apply the topcoat. There are no restrictions on the topcoat; any topcoat that achieves good compatibility and adhesion with the intermediate paint (second component) is acceptable.

[0073] The rust-resistant coating of the present invention can be used on any steel structure with a rust layer, including but not limited to the surface of rusted steel materials such as railways, power plants, chemical plants, and ships.

[0074] The technical solution of the present invention will be described in detail below through several specific embodiments and comparative examples. Unless otherwise stated, the raw materials and reagents used in the following embodiments are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the embodiments are all commercially available.

[0075] Example 1 This embodiment provides a rust-resistant coating, the composition and preparation process of which are as follows: Step 1: Take 7.5 parts of deionized water, preheat to 60°C, then add 0.03 parts of surfactant (LAS:AEO=2.5:1) and mix well; then, lower the temperature of the mixed solution to 50°C, take 50 parts of acrylic emulsion (50% solid content) and slowly add it to the above mixed solution. Stirring is required during the addition of acrylic emulsion until a primer film is formed. Step 2: Take 7.5 parts of penetrant (4.5 parts of propylene glycol and 3 parts of ethanol) and 7 parts of rust-converting agent (5 parts of phosphoric acid and 2 parts of tannic acid) and mix them evenly. Keep the temperature at 50°C, and then slowly add 8 parts of primer film-forming agent to form primer rust-converting agent. Step 3: Mix the remaining primer film-forming material and primer rust conversion agent evenly at 50°C, then add 0.3 parts of film-forming aid (BYK381) and let stand for more than 2 hours to form the first component; wherein, the 0.3 parts of film-forming aid are first stirred in a mixed solution of 4 parts ethanol and 4 parts deionized water until completely dissolved, and then added dropwise to the mixed solution.

[0076] Step 4: Take 1.5 parts of deionized water, add 1.5 parts of ethanol and mix well. Then add 1.5 parts of complexing agent (AMTP·Na5) and continue to mix well. Finally, add 1.5 parts of butyl acetate and mix well to form a complexing agent solution.

[0077] Step 5: Mix 8 parts of polyurethane with 4 parts of butyl acetate evenly, then add 7 parts of zinc powder (3.5 parts each of 1~3μm zinc powder and 0.5~1μm zinc powder) and stir to form a suspension resin liquid.

[0078] Step 6: Add the complexing agent solution to the suspended resin solution and continue stirring until homogeneous to form the second component.

[0079] After configuration, apply the rust-resistant coating of this embodiment to the surface such as... Figure 5 As shown in (a) of the figure, the Q235 carbon steel surface clearly has a rust layer (0.8 mm thick) before coating. The first and second components were sequentially coated onto the Q235 carbon steel surface; the effect after coating is shown in [reference needed]. Figure 5 In (b), the coating process is as follows: (1) Wipe the surface of Q235 carbon steel to remove dust and large pieces of loose rust; (2) After the first component is mixed evenly with the acrylic resin curing agent, it is brushed onto the surface of Q235 carbon steel. Four coats are applied with a 2-minute interval between each coat to form a primer. (3) Before the primer reaches a surface dry state (at 35℃, 4 min interval), mix the second component with the polyurethane curing agent evenly, and then brush it onto the primer surface. Apply two coats (160 μm thick), with a 2 min interval between each coat, to form an intermediate coat. Figure 5 As can be seen from (b), the rust layer on the surface of Q235 carbon steel has been completely transformed, and there is no obvious rust layer.

[0080] (4) After the intermediate paint has fully cured, apply the topcoat PEC3000PU to its surface.

[0081] Example 2 The difference between this embodiment and Embodiment 1 is that the raw material ratios of the first component and the second component are different. First component: 9 parts demineralized water, 0.01 parts surfactant, 40 parts acrylic emulsion, 5 parts penetrant, 4 parts rust remover, 0.1 parts film-forming aid, and 4 parts ethanol. Among them, 4 parts of the demineralized water and 4 parts of ethanol are mixed to dissolve the film-forming aid, and then added to the mixture to form the first component. Second component: 1 part deionized water, 1 part ethanol, 1 part complexing agent, 3 parts butyl acetate, 5 parts polyurethane, and 5 parts zinc powder.

[0082] Example 3 The difference between this embodiment and Embodiment 1 is that the raw material ratios of the first component and the second component are different. First component: 14 parts demineralized water, 0.05 parts surfactant, 45 parts acrylic emulsion, 10 parts penetrant, 8 parts rust remover, 0.5 parts film-forming aid, and 4 parts ethanol; wherein, 4 parts of the demineralized water and 4 parts of ethanol are mixed to dissolve the film-forming aid, and then added to the mixture to form the first component; Second component: 2 parts deionized water, 2 parts ethanol, 2 parts complexing agent, 7 parts butyl acetate, 10 parts polyurethane, and 10 parts zinc powder.

[0083] Comparative Example 1 The difference between this comparative example and Example 1 is that a commercially available rust-converting coating was used to treat the rust layer on the surface of Q235 carbon steel. The commercially available rust-converting coating is a two-component system: Component A consists of 4% propylene glycol methyl ether, 0.8% dodecyl alcohol ester, and the remainder is water; Component B consists of 4% tannic acid, 2% 5-flavonoid salicylic acid, 0.8% citric acid, and the remainder is acrylic hybrid emulsion. Components A and B are mixed and applied to the rust layer on the surface of Q235 carbon steel, with a coating thickness of 30 μm. This rust-converting coating is a water-based primer, therefore an intermediate coat and a topcoat are also required. The intermediate coat is PEC2000XY, and the topcoat is PEC3000PU, with the same application amount as in Example 1. After applying the intermediate coat and topcoat according to the recommended combination, the maximum adhesion was measured to be 3.75 MPa, and the minimum adhesion was 3.20 MPa.

[0084] In this application, the coatings of Examples 1-3 and Comparative Example 1 were tested for adhesion according to the standard test method of ASTM D4541 for determining the pull-off strength of coatings using a portable adhesion tester. To improve the accuracy of the test, four locations were randomly selected for testing for each sample. The test results are shown in Table 1.

[0085] Table 1: Adhesion test results of Examples 1-3 and Comparative Example 1

[0086] The test results show that the adhesion of the coatings in Examples 1-3 is greater than that of the coating in Comparative Example 1, indicating that the rust-resistant coating of this application can effectively improve the problem of poor coating adhesion.

[0087] The rust-resistant coating provided by this invention achieves efficient and reliable protection for rusted steel structures through a two-component synergistic design: the rust-transforming agent in the first component chemically reacts with the rust layer on the steel structure surface, causing the loose rust layer to dissolve and generate free iron ions and other metal ions. These free metal ions can then react with the complexing agent in the second component to form stable complexes that are embedded between resin particles. Simultaneously, the zinc powder in the second component sinks to the surface of the steel substrate, forming a sacrificial anodic protective layer. The preferential corrosion of the sacrificial zinc powder itself further provides cathodic protection to the steel substrate. The synergistic effect of rust conversion and curing and sacrificial anodic protection significantly enhances the coating's all-around protection capability for rusted steel structures and significantly extends the service life of the steel structure. Therefore, this invention effectively overcomes some practical problems in the prior art, thus possessing high utilization value and practical significance.

[0088] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A rust-resistant coating, characterized in that, include: The first component comprises the following raw materials in parts by weight: 9-14 parts of demineralized water, 0.01-0.05 parts of surfactant, 40-50 parts of acrylic emulsion, 5-10 parts of penetrant, 4-8 parts of rust remover, 0.1-0.5 parts of film-forming aid, and 4 parts of ethanol, wherein the film-forming aid is dissolved in a mixed solvent of the demineralized water and the ethanol; The second component comprises the following raw materials in parts by weight: 1-2 parts deionized water, 1-2 parts ethanol, 1-2 parts complexing agent, 3-7 parts butyl acetate, 5-10 parts polyurethane, and 5-10 parts zinc powder.

2. The rust-resistant coating according to claim 1, characterized in that, Includes one or more of the following: The surfactant is selected from sodium dodecylbenzenesulfonate or a mixture of sodium dodecylbenzenesulfonate and fatty alcohol vinyl ether; The penetrant is selected from propylene glycol or a mixture of propylene glycol and ethanol; The rust-removing agent includes one or more of gallic acid, citric acid, phosphoric acid, and tannic acid; The film-forming aid includes one or more of BYK381 and BYK3560; The complexing agent includes one or more of aminotrimethylphosphonate pentasodium and ethylenediaminetetraacetic acid disodium.

3. The rust-resistant coating according to claim 1, characterized in that, The acrylic emulsion has a solid content of 50% to 60%; the deionized water has a conductivity of ≤200 μs / cm and suspended solids in the deionized water are <50 mg / kg.

4. The rust-resistant coating according to claim 1, characterized in that, The zinc powder includes zinc powder with a first particle size and zinc powder with a second particle size. The mass ratio of the zinc powder with the first particle size to the zinc powder with the second particle size is (1~3):

1. The particle size of the zinc powder with the first particle size is 1~3μm, and the particle size of the zinc powder with the second particle size is 0.5~1μm.

5. A method for preparing a rust-resistant coating according to any one of claims 1 to 4, characterized in that, Includes the following steps: The raw materials of the first component are mixed in a set ratio to prepare the first component; The raw materials of the second component are mixed in a set ratio to prepare the second component.

6. The method for preparing the rust-resistant coating according to claim 5, characterized in that, The step of preparing the first component includes: Take 5-10 parts of deionized water, preheat it to 40-70℃, then add 0.01-0.05 parts of surfactant, mix well, then lower the temperature of the mixed solution to 45-55℃, add 40-50 parts of acrylic emulsion to form a primer film. Mix 5-10 parts of penetrant with 4-8 parts of rust-converting agent evenly, maintain the temperature at 45-55℃, and add 5-10 parts of primer film-forming agent to form primer conversion agent; The remaining primer film-forming material and the primer rust conversion agent are mixed evenly at 45-55°C. Then, 0.1-0.5 parts of film-forming aid, which have been pre-dissolved in a mixed solution of 4 parts deionized water and 4 parts ethanol, are added and mixed to form the first component.

7. The method for preparing the rust-resistant coating according to claim 5, characterized in that, The step of preparing the second component includes: Mix 1-2 parts of deionized water with 1-2 parts of ethanol until homogeneous, add 1-2 parts of complexing agent and stir until dissolved, then add 1-2 parts of butyl acetate and mix until homogeneous to form a complexing agent solution; Mix 5-10 parts of polyurethane with 2-5 parts of butyl acetate until uniform, add 5-10 parts of zinc powder and stir until uniform to form a suspension resin liquid; The complexing agent solution is added to the suspended resin liquid and stirred until homogeneous to form the second component.

8. A method of using the rust-resistant coating as described in any one of claims 1 to 4, characterized in that, Includes the following steps: The steel structure surface to be treated is pretreated to remove dust and loose rust. After the first component is mixed evenly with the curing agent, it is applied to the surface of the steel structure to form a primer; After the second component is mixed evenly with the curing agent, it is applied to the surface of the primer to form an intermediate coat; After the intermediate paint has cured, apply the topcoat.

9. The method of using the rust-resistant coating according to claim 8, characterized in that, The rust layer thickness of the steel structure surface to be treated is less than 0.5 mm, and 1 to 2 coats of the first component are applied; the rust layer thickness of the steel structure surface to be treated is 0.5 mm to 1 mm, and 3 to 5 coats of the first component are applied; the rust layer thickness of the steel structure surface to be treated is greater than 1 mm, and 3 to 4 coats of the first component are applied for every 1 mm, with a time interval of 2 to 3 minutes between each coat.

10. The method of using the rust-resistant coating according to claim 8, characterized in that, The coating thickness of the second component is 80~160μm.

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