Metal plate surface rust-proof treatment method

Abstract

The invention belongs to the technical field of metal plate rust prevention, and particularly relates to a metal plate surface rust prevention treatment method. The invention relates to a mildew preventive. The mildew preventive is prepared by compounding monensin sodium and polyhexamethylene biguanide hydrochloride according to a mass ratio of 1: (1-7). Through cleaning and mechanical rust removal treatment in surface pretreatment, oil stains, rust and impurities on the surface of the metal plate can be effectively removed, and a good foundation is laid for subsequent mildew-proof paint coating; the metal plate treated through the method has the long service life in the severe environment such as the humid environment, the maintenance cost of the metal plate can be remarkably reduced, mold breeding can be effectively resisted, and the good appearance and performance are kept.

Description

Technical Field

[0001] This invention belongs to the field of metal sheet rust prevention technology, and specifically relates to a method for rust prevention treatment of metal sheet surface. Background Technology

[0002] Metal sheets, with their high strength, good plasticity, and processing properties, occupy a crucial position in industrial production and daily life. From steel structures and bridge frames in the construction field to car body shells and mechanical equipment parts in automobile manufacturing, and even the casings of home appliances and the panels of kitchen and bathroom products, metal sheets are ubiquitous. However, they are highly susceptible to corrosion in humid or corrosive environments. When metal sheets are exposed to humid environments, a thin film of water easily forms on the surface. This film reacts chemically with substances such as oxygen and sulfur dioxide in the air, accelerating the corrosion process. In special environments such as marine engineering and chemical workshops, corrosive media such as chloride ions and acidic or alkaline gases can cause severe erosion of metal sheets.

[0003] Rust not only affects the appearance of metal sheets, causing mottled rust spots and loss of luster, but also damages their internal structure, significantly reducing their mechanical properties. Currently, common methods for rust prevention on metal sheets include painting, electroplating, and hot-dip galvanizing. Painting is advantageous due to its relatively simple operation and low cost, but it also has significant drawbacks: the coating relies mainly on physical adsorption to bond with the metal surface, resulting in weak adhesion. Under external mechanical friction, temperature changes, or chemical corrosion, it is prone to peeling off, leading to a short duration of rust prevention.

[0004] Electroplating, through the principle of electrolysis, forms a uniform and dense metallic coating on the metal surface, effectively isolating it from external corrosive media and providing good rust prevention. However, this process not only requires large quantities of precious metals and electroplating solutions, but more importantly, it generates a large amount of wastewater and acidic waste gas containing harmful substances such as heavy metal ions and cyanides. If not properly treated, this will cause serious pollution to the soil, water bodies, and atmosphere, resulting in high environmental remediation costs.

[0005] Hot-dip galvanizing involves immersing a metal sheet in molten metal to form a thick alloy coating on its surface. This coating offers excellent rust prevention and a long service life, and is commonly used in applications with high protection requirements, such as outdoor steel structures and highway guardrails. However, this method requires heating the molten metal to a high temperature, resulting in significant energy consumption. Furthermore, for metal sheets with complex shapes, grooves, or holes, it is difficult to ensure uniform filling of the molten metal during the immersion process, which can easily lead to localized areas with insufficient coating or missed areas, affecting the overall rust prevention effect.

[0006] Furthermore, in humid environments with high relative humidity, surface-treated metal sheets also face the problem of mold growth. During their growth, mold secretes metabolic byproducts such as organic acids and enzymes, which further corrode the metal surface. Simultaneously, the presence of mold mycelium affects the appearance of the metal sheet. However, most existing rust-prevention methods focus on blocking physical and chemical corrosion, with less consideration given to mold prevention, making it difficult to meet the protection needs in complex environments.

[0007] Therefore, developing a low-cost, environmentally friendly, and effective rust and mildew-proof surface rust prevention method for metal sheets is of great practical significance for improving the performance of metal materials, reducing economic losses, and promoting the sustainable development of related industries.

[0008] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0009] The purpose of this invention is to provide a method for rust prevention treatment of metal sheet surfaces.

[0010] To achieve the above objectives, the present invention provides the following technical solution: The first objective of this invention is to provide a mildew inhibitor, which is a compound of sodium monensin and polyhexamethylene biguanide hydrochloride in a mass ratio of 1:1-7.

[0011] Furthermore, the mass ratio of sodium monensin to polyhexamethylene biguanide hydrochloride is 1:3.

[0012] A second objective of this invention is to provide a rust-proof and mildew-proof coating for metal sheets, wherein the rust-proof and mildew-proof coating for metal sheets includes the mildew inhibitor.

[0013] Furthermore, by weight percentage, the rust-proof and mildew-proof coating for metal sheets is prepared from the following raw materials: 30-45% base material, 15-20% solvent, 3-6% rust inhibitor, 2-5% mildew inhibitor, 0.5-1.5% additives, 0-7% pigment, and filler to 100%.

[0014] Furthermore, the preparation method of the base material is as follows: epoxy resin and polyvinyl alcohol are added to a reaction vessel at a mass ratio of 3:1, and then 4% of the total mass of epoxy resin and polyvinyl alcohol as initiator and 3% as crosslinking agent are added sequentially. After stirring and mixing at 300 r / min for 20 min, the mixture is stirred and reacted at 90°C and 500 r / min for 2 h to obtain the base material.

[0015] Furthermore, the solvent is xylene; the rust inhibitor is zinc molybdate; the additive is BYK-348; the pigment is titanium dioxide; and the filler is talc.

[0016] The third objective of this invention is to provide a method for preparing the aforementioned anti-rust and anti-mildew coating for metal sheets, specifically: adding a base material to a dispersion vessel, then sequentially adding a solvent, an anti-rust agent, a pigment, and a filler, and dispersing at 800 r / min for 30 min; then sequentially adding an anti-mildew agent and an additive, and stirring and dispersing at 1200 r / min for 20 min to obtain a mixed slurry; then feeding the mixed slurry into a grinding mill for grinding, and passing it through a 50 μm sieve to obtain the aforementioned anti-rust and anti-mildew coating for metal sheets.

[0017] The fourth objective of this invention is to provide a method for rust prevention treatment of metal sheet surfaces, comprising the following steps: S1. Pretreatment: After cleaning the surface of the metal sheet, sandblasting is used to remove rust; S2. Coating: Spray the rust-proof and mildew-proof coating onto the surface of the pretreated metal sheet. After spraying, let it stand at room temperature for 40-60 minutes, and then dry it at 100-120℃ for 2-3 hours. S3. Post-processing: Remove the metal sheet and allow it to cool naturally to room temperature. Polish and smooth the surface to make it flat.

[0018] Furthermore, in step S1, when sandblasting to remove rust, quartz sand with a particle size of 0.5-2mm is selected as the abrasive, the sandblasting pressure is 0.7MPa, the sandblasting distance is 150mm, and the surface of the metal plate is sandblasted at a 45° angle until the surface reveals a uniform metallic color without visible rust and oxide scale.

[0019] Furthermore, in step S2, the thickness of the anti-rust and anti-mildew coating on the metal sheet is 50-80μm, the spraying pressure is 15MPa, the spraying distance is 200mm, and the spraying angle is 75°-90°.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) The metal sheet anti-rust and anti-mildew coating of the present invention, which is made of epoxy resin and polyvinyl alcohol crosslinked in a mass ratio of 3:1, has good adhesion, salt spray resistance and damp heat resistance, and can effectively block water vapor, thereby improving the metal sheet's resistance to the external environment.

[0021] (2) The present invention uses sodium monensin and polyhexamethylene biguanide hydrochloride to form a mildew inhibitor, which can give the metal sheet anti-rust and mildew-proof coating an excellent mildew-proof effect, thereby improving the metal sheet's ability to resist mold erosion in a humid environment.

[0022] (3) The present invention can effectively remove oil, rust and impurities from the surface of metal plates through cleaning and mechanical rust removal in the surface pretreatment, laying a good foundation for subsequent anti-mildew coating; the metal plates treated by the present invention not only have a long service life in humid and other harsh environments, but also significantly reduce the maintenance cost of metal plates, and can effectively resist the growth of mold, maintaining good appearance and performance. Detailed Implementation

[0023] The technical solution of this invention patent will be clearly and completely described below. Obviously, the described embodiments are some embodiments of this invention, but not all embodiments.

[0024] Example 1 An antifungal agent, wherein the antifungal agent is compounded from sodium monensin and polyhexamethylene biguanide hydrochloride in a mass ratio of 1-5:7-1, and the mass ratio of sodium monensin and polyhexamethylene biguanide hydrochloride is 1:3 for better effect.

[0025] Example 2 A rust-proof and mildew-proof coating for metal sheets, comprising, by weight percentage, the following raw materials: 42% base material, 18% xylene solvent, 5% zinc molybdate rust inhibitor, 4% mildew inhibitor, 1% BYK-348 additive, 5% titanium dioxide pigment, and talc filler to 100%; The preparation method of the base material is as follows: epoxy resin and polyvinyl alcohol are added to a reaction vessel at a mass ratio of 3:1, and then 4% of the total mass of epoxy resin and polyvinyl alcohol, triethylenetetramine initiator and 3% of the crosslinking agent hexamethylene diisocyanate are added sequentially. After stirring and mixing at 300 r / min for 20 min, the mixture is stirred and reacted at 90°C and 500 r / min for 2 h to obtain the base material. The antifungal agent is a compound of sodium monensin and polyhexamethylene biguanide hydrochloride in a mass ratio of 1:3. The preparation method of the above-mentioned anti-rust and anti-mildew coating for metal plates is as follows: the base material is added to the dispersion vessel, and the solvent xylene, the rust inhibitor zinc molybdate, the pigment titanium dioxide and the filler talc are added in sequence, and dispersed at 800 r / min for 30 min; then the anti-mildew agent and the auxiliary agent BYK-348 are added in sequence, and stirred and dispersed at 1200 r / min for 20 min to obtain a mixed slurry; then the mixed slurry is sent to a grinding mill for grinding and passed through a 50 μm sieve to obtain the anti-rust and anti-mildew coating for metal plates.

[0026] Example 3 A method for rust prevention treatment of metal sheet surface includes the following steps: S1. Preprocessing After cleaning the surface of the metal sheet, sandblasting is used to remove rust. When sandblasting, quartz sand with a particle size of 0.5-2mm is used as the abrasive, the sandblasting pressure is 0.7MPa, the sandblasting distance is 150mm, and the surface of the metal sheet is sandblasted at a 45° angle until the surface reveals a uniform metal color with no visible rust or oxide scale. S2. Coating The metal sheet anti-rust and anti-mildew coating of claim 4 is sprayed onto the surface of the pretreated metal sheet. After spraying, the surface is left to stand at room temperature for 60 minutes, and then dried at 120°C for 2.5 hours. The metal sheet anti-rust and anti-mildew coating has a spraying thickness of 80 μm, a spraying pressure of 15 MPa, a spraying distance of 200 mm, and a spraying angle of 75°. S3. Post-processing Remove the metal sheet and allow it to cool naturally to room temperature. Then, polish and smooth the surface.

[0027] Example 4: The Influence of Different Base Materials on the Performance of Rust-Proof and Mildew-Proof Coatings for Metal Sheets The effects of different base materials on the performance of anti-rust and anti-mildew coatings for metal sheets were determined by the test methods in Table 1 (Table 3), and the results are shown in Table 4.

[0028] Table 1 Test Items, Methods and Descriptions

[0029] Table 2. Rating Criteria for Resistance to Damp Heat

[0030] Table 3 Formulation of anti-rust and anti-mildew coatings for metal sheets

[0031] Note: The preparation methods of the base material (except for the mass ratio of epoxy resin to polyvinyl alcohol) and the preparation methods of the coating are the same as in Example 2.

[0032] Table 4. Effects of different base materials on the performance of anti-rust and anti-mildew coatings for metal sheets

[0033] As shown in Table 4, the coatings using epoxy resin and polyvinyl alcohol crosslinked as the base material exhibit superior performance due to the crosslinking of epoxy resin or polyvinyl alcohol itself. In particular, the coatings using a base material crosslinked with epoxy resin and polyvinyl alcohol at a 3:1 mass ratio show significantly better performance than those in other groups. This indicates that the coatings of this invention, using an epoxy resin and polyvinyl alcohol crosslinked at a 3:1 mass ratio, possess better adhesion, salt spray resistance, and damp heat resistance, and can effectively block water vapor, thereby improving the metal sheet's resistance to the external environment.

[0034] Example 5: Effect of different mildew inhibitors on the mildew-proof effect of anti-rust and mildew-proof coatings for metal sheets 5.1 Test molds See Table 4.

[0035] Table 4 Test molds

[0036] 5.2 Test Anti-mildew Coatings See Table 5.

[0037] Table 5 Formulation of Rust-proof and Mildew-proof Coatings for Metal Sheets

[0038] Note: The preparation methods for the base material and the coating are the same as in Example 2.

[0039] 5.3 Test Methods The test molds were inoculated onto PDA medium (formulation: 300g peeled potato, 20g glucose, 20g agar, sterile water to a final volume of 1000mL, natural pH) and incubated at 28℃ for 7-10 days. After the test molds had fully sporulated, the sporozoites were washed away with sterile water, filtered through double-layer medical gauze to obtain the spore stock solution, and the spore concentration was diluted to 1×10⁻⁶ with sterile water. 6 CFU / mL was used to obtain a spore suspension; equal volumes of the spore suspensions of each test mold were mixed evenly to obtain a mixed mold spore solution.

[0040] A 50mm × 50mm aluminum plate with a thickness of 1mm was processed according to the method in Example 3 to obtain test samples, with 50mm × 50mm sterile fiber filter paper as the control sample. Three samples of each type were used. The mold resistance grade was then determined according to the petri dish method in 7.4.1 of GB / T 1741-2020 "Test Method for Mold Resistance of Coatings". The amount of mixed mold spore solution sprayed was 0.5mL per sample; the constant temperature and humidity incubator conditions were 28℃ and 90% relative humidity; and the incubation time was 28 days. The grading standard for mold resistance is shown in Table 6, and the test results are shown in Table 7.

[0041] Table 6 Grading Standards for Mold Resistance

[0042] Table 7. Effect of mildew inhibitors on the mildew-proofing effect of anti-rust and mildew-proof coatings for metal sheets.

[0043] Table 7 shows that the anti-mold effect of anti-mold coatings is limited when polyhexamethylene biguanide hydrochloride or sodium monensin is used alone. Although the anti-mold effect of polyhexamethylene biguanide hydrochloride alone is better than that of sodium monensin, it is significantly lower than that of the compound anti-mold agent. In coatings with compound anti-mold agents, the anti-mold effect is optimal when the mass ratio of sodium monensin to polyhexamethylene biguanide hydrochloride is 1:3. Therefore, the anti-mold agent composed of sodium monensin and polyhexamethylene biguanide hydrochloride can impart excellent anti-mold effects to the coating, thereby resisting the corrosion of metal sheets by mold in humid environments.

[0044] In summary, this invention, through cleaning and mechanical rust removal in surface pretreatment, can effectively remove oil, rust, and impurities from the surface of metal sheets, laying a good foundation for subsequent anti-mildew coating application. Metal sheets treated by this invention not only have a longer service life in humid and other harsh environments, significantly reducing the maintenance cost of metal sheets, but also effectively resist mold growth, maintaining good appearance and performance.

[0045] Finally, it should be noted that in the above embodiments, the epoxy resin is EP137 waterborne epoxy resin (purchased from Shanghai Yantai E-commerce Co., Ltd.), with an epoxy equivalent of 460-630 g / mol.

[0046] The polyvinyl alcohol was purchased from Hefei Tianyi New Materials Co., Ltd. as Wanwei polyvinyl alcohol PVA 24-99 (L).

[0047] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A mildew inhibitor, characterized in that, The antifungal agent is a compound of sodium monensin and polyhexamethylene biguanide hydrochloride in a mass ratio of 1:1-7.

2. The antifungal agent according to claim 1, characterized in that, The mass ratio of sodium monensin to polyhexamethylene biguanide hydrochloride is 1:

3.

3. A rust-proof and mildew-proof coating for metal sheets, characterized in that, The rust-proof and mildew-proof coating for metal sheets includes the mildew-proof agent as described in claim 1.

4. The anti-rust and anti-mildew coating for metal sheets according to claim 3, characterized in that, The metal sheet anti-rust and anti-mildew coating is prepared from the following raw materials by weight percentage: base material 30-45%, solvent 15-20%, rust inhibitor 3-6%, mildew inhibitor 2-5%, additives 0.5-1.5%, pigment 0-7%, and filler to 100%.

5. The anti-rust and anti-mildew coating for metal sheets according to claim 4, characterized in that, The preparation method of the base material is as follows: epoxy resin and polyvinyl alcohol are added to a reaction vessel at a mass ratio of 3:1, and then 4% of the total mass of epoxy resin and polyvinyl alcohol as initiator and 3% as crosslinking agent are added sequentially. After stirring and mixing at 300 r / min for 20 min, the mixture is stirred and reacted at 90℃ and 500 r / min for 2 h to obtain the base material.

6. The anti-rust and anti-mildew coating for metal sheets according to claim 4, characterized in that, The solvent is xylene; the rust inhibitor is zinc molybdate; the additive is BYK-348; the pigment is titanium dioxide; and the filler is talc.

7. A method for preparing the anti-rust and anti-mildew coating for metal sheets according to claim 4, characterized in that, Specifically, the base material is added to a dispersion vessel, followed by the addition of solvent, rust inhibitor, pigment, and filler, and dispersed at 800 r / min for 30 min. Then, the mildew inhibitor and additives are added sequentially, and the mixture is stirred and dispersed at 1200 r / min for 20 min to obtain a mixed slurry. The mixed slurry is then fed into a grinding mill for grinding and passed through a 50 μm sieve to obtain the rust-proof and mildew-proof coating for metal plates.

8. A method for rust prevention treatment of metal sheet surface, characterized in that, Includes the following steps: S1. Pretreatment: After cleaning the surface of the metal sheet, sandblasting is used to remove rust; S2. Coating: Spray the anti-rust and anti-mildew coating of claim 4 onto the surface of the pretreated metal sheet. After spraying, let it stand at room temperature for 40-60 minutes, and then dry it at 100-120℃ for 2-3 hours. S3. Post-processing: Remove the metal sheet and allow it to cool naturally to room temperature. Polish and smooth the surface to make it flat.

9. The method for rust prevention treatment of metal sheet surface according to claim 8, characterized in that, In step S1, when sandblasting to remove rust, quartz sand with a particle size of 0.5-2mm is selected as the abrasive, the sandblasting pressure is 0.7MPa, the sandblasting distance is 150mm, and the surface of the metal plate is sandblasted at a 45° angle until the surface reveals a uniform metal color without visible rust and oxide scale.

10. The method for rust prevention treatment of metal sheet surface according to claim 8, characterized in that, In step S2, the thickness of the anti-rust and anti-mildew coating on the metal sheet is 50-80μm, the spraying pressure is 15MPa, the spraying distance is 200mm, and the spraying angle is 75°-90°.

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