A self-cleaning zinc-aluminum-magnesium plated steel sheet and a method for manufacturing the same

Abstract

This invention discloses a self-cleaning zinc-aluminum-magnesium coated steel sheet, comprising a substrate, a zinc-aluminum-magnesium coating deposited on the surface of the substrate, and a chemical treatment film on the surface of the zinc-aluminum-magnesium coating. The chemical treatment film contains the following components in parts by weight: a coupling agent containing acyloxysilane: 10-15 parts; an adhesive containing mercaptosiloxane: 10-15 parts; a water-based modified acrylic resin and a water-based acrylic aliphatic polyurethane copolymer: 10-12 parts; zinc dihydrogen phosphate and magnesium oxide: 3-5 parts; a water-based polyethylene wax dispersion: 4-8 parts; and a fluorosiloxane: 1-5 parts. This invention also discloses a method for manufacturing a self-cleaning zinc-aluminum-magnesium coated steel sheet, comprising the steps of: immersing a heated substrate in a plating solution for hot-dip plating, then cooling to obtain a steel sheet with a zinc-aluminum-magnesium coating; coating the zinc-aluminum-magnesium coating with a chemical treatment solution and curing it to form the chemical treatment film on the surface of the zinc-aluminum-magnesium coating.

Description

Technical Field

[0001] This invention relates to a steel plate and a method for manufacturing the same, and more particularly to a coated steel plate and a method for manufacturing the same. Background Technology

[0002] Zinc-aluminum-magnesium alloy coatings bond well with steel plates and provide excellent protection. In terms of corrosion protection, compared to pure zinc coatings of the same coating weight, zinc-aluminum-magnesium alloy coatings offer 4-5 times better corrosion resistance, with even greater improvements in special service environments (such as coastal environments with high chloride ion content). Besides the inherent corrosion resistance of its alloy components, the zinc-aluminum-magnesium alloy coating also forms a nanoscale alloy inhibition layer with the carbon steel substrate, significantly enhancing the adhesion between the coating and the substrate. Furthermore, corrosion products formed by the zinc-aluminum-magnesium alloy coating in the atmosphere migrate to damaged areas and cut edges on the steel plate surface, forming a protective layer on exposed areas of the substrate and preventing further erosion by corrosive media in the environment.

[0003] However, because the zinc-aluminum-magnesium alloy coating has a large amount of highly reactive metal elements such as Al and Mg, it is very easy to undergo surface oxidation in harsh service environments, resulting in blackening or white rust on the surface; and the exposed zinc-aluminum-magnesium alloy coating is easily contaminated in outdoor service environments, affecting material performance and visual effect.

[0004] To improve the resistance to blackening and white rust on the material surface, as well as to achieve the self-cleaning function of the coating surface, chemical treatment can be considered on the zinc-aluminum-magnesium alloy coating surface to form a functional chemical protective film, thereby further improving the material's overall protective capability.

[0005] In the prior art, existing patent literature covers the above-mentioned fields, including:

[0006] For example, Chinese patent document CN106222593A, published on December 14, 2016, entitled "A High Corrosion-Resistant Hot-Dip Zinc-Coated Steel Sheet with Aluminum-Magnesium-Nickel Rare Earth Alloy Coating and Its Production Method," discloses a high corrosion-resistant hot-dip zinc-coated steel sheet with aluminum-magnesium-nickel rare earth alloy coating and its production method. This method achieves higher corrosion resistance by adding Si, Ni, and Ce elements to the zinc-aluminum-magnesium coating. The main factors improving corrosion resistance are the increase in Al content and the addition of Si. This technical solution also involves the addition of Ce and Ni. The addition of small amounts of Ce and Ni can improve corrosion resistance to a certain extent. More importantly, increasing Ce and Ni increases the number of alloy cooling nucleation sites, thereby improving the surface finish of the coating.

[0007] For example, Chinese patent document CN105316669A, published on February 10, 2016, entitled "A High-Efficiency and Environmentally Friendly Antibacterial Passivation Solution for Stainless Steel and Its Preparation Method," discloses a high-efficiency and environmentally friendly antibacterial passivation solution for stainless steel and its preparation method. Its main components include: 10-20 parts of γ-methacryloyloxytrimethoxysilane; 10-20 parts of 1,2-bis(triethoxysilyl)ethane; 5-10 parts of hydroxypropyl methylcellulose; 5-15 parts of carbamate; 5-10 parts of hydroxypropyl chitosan; 2-5 parts of nano-titanium oxide; 10-15 parts of citric acid; 5-15 parts of sodium molybdate; 5-10 parts of sodium silicate; and 50-80 parts of deionized water. This passivation layer adheres well to the surface of the stainless steel substrate, meets the requirements for high corrosion resistance, and also exhibits photocatalytic antibacterial properties.

[0008] For example, Chinese patent document CN105688278A, published on June 22, 2016, entitled "A Method for Preparing an Antibacterial Coating on the Surface of a Titanium Implant," discloses a method for preparing an antibacterial coating on the surface of a titanium implant. This method involves alternately immersing a titanium sheet in a sodium hydroxide solution three times, followed by immersion in a polycationic solution such as chitosan, polylysine solution, and a polyanionic solution such as hyaluronic acid, sodium alginate, and polyglutamic acid solution. The treated titanium sheet is then immersed in a silver nitrate solution, followed by an immersion in a 0.1-0.5 mol / L ascorbic acid solution. This layer-by-layer self-assembly process yields an antibacterial coating on the surface of a titanium substrate with good biocompatibility and antibacterial properties. Summary of the Invention

[0009] One of the objectives of this invention is to provide a self-cleaning zinc-aluminum-magnesium coated steel sheet, wherein the zinc-aluminum-magnesium coating surface of the self-cleaning zinc-aluminum-magnesium coated steel sheet has good self-cleaning and corrosion-resistant properties.

[0010] To achieve the above objectives, the present invention provides a self-cleaning zinc-aluminum-magnesium coated steel sheet, comprising a substrate, a zinc-aluminum-magnesium coating deposited on the surface of the substrate, wherein the surface of the zinc-aluminum-magnesium coating has a chemically treated film, and the chemically treated film contains the following components in parts by weight:

[0011] Coupling agent containing acyloxysilane: 10-15 parts;

[0012] Adhesives containing mercaptosiloxane: 10-15 parts;

[0013] Waterborne modified acrylic resin and waterborne acrylic aliphatic polyurethane copolymer: 10-12 parts;

[0014] Zinc dihydrogen phosphate and magnesium oxide: 3-5 parts;

[0015] Aqueous polyethylene wax dispersion: 4-8 parts;

[0016] Fluorosiloxanes: 1 to 5 parts.

[0017] In this invention, the waterborne modified acrylic resin and waterborne acrylic aliphatic polyurethane copolymer of the above content can provide high gloss and high weather resistance, the above content of zinc dihydrogen phosphate and magnesium oxide helps to improve the adhesion between the coating and the metal plating, the waterborne polyethylene wax dispersion has good lubrication properties, and the fluorosiloxane has superhydrophobic properties.

[0018] Furthermore, in the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention, the substrate is a hot-rolled substrate.

[0019] Furthermore, in the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention, the hot-rolled substrate contains Fe and unavoidable impurities, as well as the following chemical elements in the following mass percentages:

[0020] C: 0.07-0.09%; Si: 0.05-0.15%; Mn: 0.9-1.5%.

[0021] Furthermore, in the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention, the substrate is a cold-rolled substrate.

[0022] Furthermore, in the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention, the cold-rolled substrate contains Fe and unavoidable impurities, as well as the following chemical elements in the following mass percentages:

[0023] C: 0.07-0.18%; Si: 0.05-0.08%; Mn: 0.8-1.1%.

[0024] Furthermore, in the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention, the zinc-aluminum-magnesium coating contains Zn and unavoidable impurities, and also contains the following chemical elements in the following mass percentages:

[0025] Al: 4.5-19.5wt%, Mg: 2.5-6.5wt%, Si: 0.001-0.2wt%, Ti: 0.001-0.1wt%, Ni: 0.001-0.1wt%.

[0026] Furthermore, in the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention, the coupling agent containing acyloxysilane is selected from: methacryloyloxypropyltris(2-methoxyethoxy)silane or 3-methacryloyloxytrimethoxysilane.

[0027] Furthermore, in the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention, the adhesive containing mercaptosiloxane is selected from: 3-mercaptopropyltrimethoxysilane or 3-mercaptopropyltriethoxysilane.

[0028] Furthermore, in the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention, the fluorinated siloxane is selected from: perfluorodecyltrimethoxysilane or perfluorooctyltriethoxysilane.

[0029] Furthermore, the surface contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet described in this invention is >150°.

[0030] Another objective of this invention is to provide a method for manufacturing a self-cleaning zinc-aluminum-magnesium coated steel sheet, which can obtain a self-cleaning zinc-aluminum-magnesium coated steel sheet with good self-cleaning and corrosion-resistant properties on the zinc-aluminum-magnesium coated surface.

[0031] To achieve the above objectives, the present invention provides a method for manufacturing a self-cleaning zinc-aluminum-magnesium coated steel sheet, comprising the following steps:

[0032] The heated substrate is immersed in the plating solution for hot-dip plating, and then cooled to obtain a steel plate with a zinc-aluminum-magnesium coating.

[0033] A chemical treatment solution is coated onto a zinc-aluminum-magnesium plating layer and cured to form the chemical treatment film on the surface of the zinc-aluminum-magnesium plating layer;

[0034] The chemical treatment solution contains the following components in parts by mass:

[0035] Coupling agent containing acyloxysilane: 10-15 parts;

[0036] Adhesives containing mercaptosiloxane: 10-15 parts;

[0037] Waterborne modified acrylic resin and waterborne acrylic aliphatic polyurethane copolymer: 10-12 parts;

[0038] Zinc dihydrogen phosphate and magnesium oxide: 3-5 parts;

[0039] Aqueous polyethylene wax dispersion: 4-8 parts;

[0040] Fluorosiloxanes: 1-5 parts;

[0041] Deionized water: 40-50 parts.

[0042] Furthermore, in the manufacturing method described in this invention, the temperature of the plating solution is 420–480°C.

[0043] Furthermore, in the manufacturing method described in this invention, the cooling rate is 15–40 °C / s.

[0044] Compared with the prior art, the self-cleaning zinc-aluminum-magnesium coated steel sheet and its manufacturing method described in this invention have the following advantages and beneficial effects:

[0045] The self-cleaning zinc-aluminum-magnesium coated steel sheet and its manufacturing method described in this invention control the selection and content of Al, Mg, Si, Ti, and Ni elements, as well as the surface chemical treatment components, so that the manufactured zinc-aluminum-magnesium alloy coated steel sheet has good self-cleaning ability on the basis of high corrosion resistance, high adhesion, and high wear resistance, avoiding the technical defects of being easily affected by various complex pollutants for a long time when used outdoors.

[0046] In some embodiments, the surface contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention is >150°. Attached Figure Description

[0047] Figure 1 The cross-sectional microstructure of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 1 of the present invention is shown.

[0048] Figure 2 The cross-sectional microstructure of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 2 of the present invention is shown.

[0049] Figure 3 The cross-sectional microstructure of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 3 of the present invention is shown.

[0050] Figure 4 The static contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 1 of the present invention is shown.

[0051] Figure 5 The static contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 2 of the present invention is shown.

[0052] Figure 6 The static contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 3 of the present invention is shown.

[0053] Figure 7 The static contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Comparative Example 1 of the present invention is shown.

[0054] Figure 8 The static contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Comparative Example 2 of the present invention is shown.

[0055] Figure 9 The static contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Comparative Example 3 of the present invention is shown.

[0056] Figure 10 A schematic diagram of the structure of the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention is shown. Detailed Implementation

[0057] The following will further explain and illustrate the self-cleaning zinc-aluminum-magnesium coated steel sheet and its manufacturing method according to the present invention with reference to specific embodiments. However, this explanation and illustration do not constitute an improper limitation on the technical solution of the present invention.

[0058] Examples 1-5 and Comparative Examples 1-3

[0059] In this invention, the self-cleaning zinc-aluminum-magnesium coated steel sheets of Examples 1-5 and the comparative steel sheets of Comparative Examples 1-3 were all prepared using the following steps:

[0060] (1) The heated substrate is immersed in the plating solution for hot-dip plating, and then cooled to obtain a steel plate with zinc, aluminum and magnesium coating.

[0061] In some embodiments, the substrate may be a hot-rolled substrate or a cold-rolled substrate.

[0062] In some embodiments, the temperature of the plating solution is 420–480°C, and the cooling rate is 15–40°C / s.

[0063] In some specific embodiments, before hot-dip plating, the steps may include: electrolytically cleaning the substrate to obtain a clean steel plate, and then annealing it.

[0064] In some specific implementations, before cooling, the step may include: scraping off excess plating solution from the surface of the steel plate using an air knife.

[0065] In some specific implementations, after cooling, the zinc-aluminum-magnesium coated steel sheet can be sequentially smoothed and straightened to obtain a flat zinc-aluminum-magnesium coated steel sheet.

[0066] (2) The chemical treatment liquid is coated onto the zinc-aluminum-magnesium coating and cured to form the chemical treatment film on the surface of the zinc-aluminum-magnesium coating.

[0067] In some specific implementations, the film can be dried and cured in a far-infrared electrically heated reaction vessel.

[0068] It should be noted that the chemical composition of the zinc-aluminum-magnesium coating of the present invention is the same as that of the hot-dip galvanizing solution, therefore the two will not be described separately.

[0069] Furthermore, it should be noted that the effective components contained in the chemical treatment membrane of the present invention are the same as those in the chemical treatment liquid, therefore the two will not be described separately.

[0070] Table 1 lists the process and chemical composition ratios of the substrates of Examples 1-5 and Comparative Examples 1-3 of the present invention.

[0071] Table 1.

[0072] serial number C(wt%) Si (wt%) Mn (wt%) substrate type Example 1 0.07 0.15 0.9 Hot rolling Example 2 0.09 0.05 1.5 Hot rolling Example 3 0.07 0.08 1.1 cold rolling Example 4 0.10 0.05 0.9 cold rolling Example 5 0.18 0.05 0.8 cold rolling Comparative Example 1 0.06 0.05 0.9 Hot rolling Comparative Example 2 0.09 0.04 0.9 cold rolling Comparative Example 3 0.09 0.15 0.8 cold rolling

[0073] *Note: The balance of the substrates in Examples 1-5 and Comparative Examples 1-3 in Table 1 above is Fe and other unavoidable impurities.

[0074] Table 2 lists the chemical composition ratios of the zinc-aluminum-magnesium coatings of Examples 1-5 and Comparative Examples 1-3 of the present invention.

[0075] Table 2. (wt%, balance Zn and other unavoidable impurities)

[0076] serial number Al Mg Si Ti Ni Example 1 4.5 2.5 0.2 0.001 0.005 Example 2 5.5 2.9 0.09 0.03 0.005 Example 3 11.0 2.9 0.001 0.002 0.001 Example 4 11.5 5.5 0.1 0.1 0.009 Example 5 19.5 6.5 0.2 0.001 0.1 Comparative Example 1 4.0 2.5 0.25 0.02 0.009 Comparative Example 2 5.5 2.0 0.001 0.1 0.1 Comparative Example 3 20 6.8 0.05 0.2 0.2

[0077] Table 3 lists the mass fractions and types of active ingredients in the chemical treatment solutions of Examples 1-5 and Comparative Examples 1-3 of the present invention.

[0078] Table 3.

[0079]

[0080]

[0081] *Note: A1 is methacryloyloxypropyltris(2-methoxyethoxy)silane, A2 is 3-methacryloyloxytrimethoxysilane; B1 is 3-mercaptopropyltrimethoxysilane, B2 is 3-mercaptopropyltriethoxysilane; F1 is perfluorodecyltrimethoxysilane, F2 is perfluorooctyltriethoxysilane.

[0082] Table 4 lists the specific process parameters for the self-cleaning zinc-aluminum-magnesium coated steel sheets of Examples 1-5 and the comparative steel sheets of Comparative Examples 1-3.

[0083] Table 4.

[0084] serial number Plating bath temperature (°C) Cooling rate (°C / s) Example 1 420 15 Example 2 430 20 Example 3 460 30 Example 4 470 35 Example 5 480 40 Comparative Example 1 410 15 Comparative Example 2 490 10 Comparative Example 3 420 45

[0085] Samples were taken from the self-cleaning zinc-aluminum-magnesium coated steel sheets of Examples 1-3, and their cross-sectional microstructure was observed using a scanning electron microscope.

[0086] Figure 1 The cross-sectional microstructure of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 1 of the present invention is shown.

[0087] Figure 2 The cross-sectional microstructure of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 2 of the present invention is shown.

[0088] Figure 3 The cross-sectional microstructure of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 3 of the present invention is shown.

[0089] like Figure 1-3 The figure shows the cross-sectional microstructure of three types of self-cleaning zinc-aluminum-magnesium coated steel sheets. Figure 1 The microstructure of Example 1 (Mg content 2.0%) shows that different small pieces of tissue are randomly interspersed and evenly distributed. Figure 2 The microstructure of Example 2 (Mg content 2.9%) shows that different mesomasses are randomly dispersed. Figure 3 The tissue morphology of Example 3 (Al content is 11%) shows that different large tissue blocks are randomly distributed.

[0090] The self-cleaning zinc-aluminum-magnesium coated steel sheets obtained in Examples 1-3 were sampled again, and their surface contact angles were tested. The test results are listed in Table 5. Among them:

[0091] Surface contact angle: The contact angle was tested using a contact angle tester (Kruss DSA100). During the test, the sample was placed horizontally at 180° on the sample stage, the liquid volume was 5μL, and 3 points were randomly selected from each sample for testing. The average value was taken as the sample contact angle value.

[0092] Table 5.

[0093] serial number Surface contact angle (°) Example 1 154 Example 2 155 Example 3 161 Example 4 150 Example 5 151 Comparative Example 1 103 Comparative Example 2 109 Comparative Example 3 104

[0094] As can be seen from Table 5 above, the surface contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheets of Examples 1-5 prepared by the method of the present invention is greater than 150°, and they have good self-cleaning ability.

[0095] Figure 4 The static contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 1 of the present invention is shown.

[0096] Figure 5 The static contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 2 of the present invention is shown.

[0097] Figure 6 The static contact angle of the self-cleaning zinc-aluminum-magnesium coated steel sheet of Embodiment 3 of the present invention is shown.

[0098] Figure 7 The static contact angle of the comparative steel plate of Comparative Example 1 of the present invention is shown.

[0099] Figure 8 The static contact angle of the comparative steel plate of Comparative Example 2 of the present invention is shown.

[0100] Figure 9 The static contact angle of the comparative steel plate of Comparative Example 3 of the present invention is shown.

[0101] like Figure 4-9 As shown, the static contact angles of the self-cleaning zinc-aluminum-magnesium coated steel sheets of Examples 1-3 of the present invention are all greater than 150°, and they are in a superhydrophobic state. In contrast, the static contact angles of the comparative steel sheets of Comparative Examples 1-3 are all less than 150°.

[0102] Figure 10 A schematic diagram of the structure of the self-cleaning zinc-aluminum-magnesium coated steel sheet of the present invention is shown.

[0103] like Figure 10 As shown, the self-cleaning zinc-aluminum-magnesium coated steel sheet includes a substrate L0, a zinc-aluminum-magnesium alloy coating L1 coated on the surface of the substrate, and a chemical treatment layer L2 on the surface of the zinc-aluminum-magnesium alloy coating.

[0104] Furthermore, the antibacterial adhesion performance of the embodiments and comparative examples was evaluated. The experimental results showed that the comparative examples exhibited a higher number of adhering bacteria (visible colonies greater than 50). In contrast, the chemically treated film formed on the zinc-aluminum-magnesium coated steel plate in the embodiments of the present invention effectively modifies the surface of the steel plate hydrophobically, thus providing good resistance to bacterial adhesion with fewer adhering bacteria (visible colonies less than 10).

[0105] In summary, the self-cleaning zinc-aluminum-magnesium coated steel sheet and its manufacturing method described in this invention, by controlling the selection and content of Al, Mg, Si, Ti, and Ni elements, as well as the surface chemical treatment components, enable the manufactured zinc-aluminum-magnesium alloy coated steel sheet to possess excellent self-cleaning ability while having high corrosion resistance, high adhesion, and high wear resistance. This avoids the technical defects of being easily affected by various complex pollutants over a long period of time when used outdoors.

[0106] It should be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A self-cleaning zinc-aluminum-magnesium coated steel sheet, comprising a substrate and a zinc-aluminum-magnesium coating plated on the surface of the substrate, characterized in that, The zinc-aluminum-magnesium coating has a chemically treated film on its surface, and the chemically treated film contains the following components in parts by weight: Coupling agent containing acyloxysilane: 10-15 parts; Adhesives containing mercaptosiloxane: 10-15 parts; Waterborne modified acrylic resin and waterborne acrylic aliphatic polyurethane copolymer: 10-12 parts; Zinc dihydrogen phosphate and magnesium oxide: 3-5 parts; Aqueous polyethylene wax dispersion: 4-8 parts; Fluorosiloxanes: 1 to 5 parts.

2. The self-cleaning zinc-aluminum-magnesium coated steel sheet as described in claim 1, characterized in that, The substrate is a hot-rolled substrate.

3. The self-cleaning zinc-aluminum-magnesium coated steel sheet as described in claim 2, characterized in that, The hot-rolled substrate contains Fe and unavoidable impurities, as well as the following chemical elements in the following mass percentages: C: 0.07-0.09%; Si: 0.05-0.15%; Mn: 0.9-1.5%.

4. The self-cleaning zinc-aluminum-magnesium coated steel sheet as described in claim 1, characterized in that, The substrate is a cold-rolled substrate.

5. The self-cleaning zinc-aluminum-magnesium coated steel sheet as described in claim 4, characterized in that, The cold-rolled substrate contains Fe and unavoidable impurities, as well as the following chemical elements in the following mass percentages: C: 0.07-0.18%; Si: 0.05-0.08%; Mn: 0.8-1.1%.

6. The self-cleaning zinc-aluminum-magnesium coated steel sheet as described in claim 1, characterized in that, The zinc-aluminum-magnesium coating contains Zn and unavoidable impurities, as well as the following chemical elements in the following mass percentages: Al: 4.5-19.5wt%, Mg: 2.5-6.5wt%, Si: 0.001-0.2wt%, Ti: 0.001-0.1wt%, Ni: 0.001-0.1wt%.

7. The self-cleaning zinc-aluminum-magnesium coated steel sheet as described in claim 1, characterized in that, The coupling agent containing acyloxysilane is selected from: methacryloyloxypropyltris(2-methoxyethoxy)silane or 3-methacryloyloxytrimethoxysilane.

8. The self-cleaning zinc-aluminum-magnesium coated steel sheet as described in claim 1, characterized in that, The adhesive containing mercaptosiloxane is selected from 3-mercaptopropyltrimethoxysilane or 3-mercaptopropyltriethoxysilane.

9. The self-cleaning zinc-aluminum-magnesium coated steel sheet as described in claim 1, characterized in that, The fluorinated siloxane is selected from: perfluorodecyltrimethoxysilane or perfluorooctyltriethoxysilane.

10. The self-cleaning zinc-aluminum-magnesium coated steel sheet as described in claim 1, characterized in that, Its surface contact angle is >150°.

11. The method for manufacturing the self-cleaning zinc-aluminum-magnesium coated steel sheet according to any one of claims 1-10, characterized in that, Including the following steps: The heated substrate is immersed in the plating solution for hot-dip plating, and then cooled to obtain a steel plate with a zinc-aluminum-magnesium coating. A chemical treatment solution is coated onto a zinc-aluminum-magnesium plating layer and cured to form the chemical treatment film on the surface of the zinc-aluminum-magnesium plating layer; The chemical treatment solution contains the following components in parts by mass: Coupling agent containing acyloxysilane: 10-15 parts; Adhesives containing mercaptosiloxane: 10-15 parts; Waterborne modified acrylic resin and waterborne acrylic aliphatic polyurethane copolymer: 10-12 parts; Zinc dihydrogen phosphate and magnesium oxide: 3-5 parts; Aqueous polyethylene wax dispersion: 4-8 parts; Fluorosiloxanes: 1-5 parts; Deionized water: 40-50 parts.

12. The manufacturing method as described in claim 11, characterized in that, The temperature of the plating solution is 420–480°C.

13. The manufacturing method as described in claim 11, characterized in that, The cooling rate is 15–40 °C / s.

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