A steel plate passivation solution, preparation method thereof and method for passivating coated steel plate

Abstract

The invention discloses a steel plate passivation solution, its preparation method and a method for passivating a coated steel plate. The steel plate passivation solution is composed of solid matter and water, wherein the solid matter contains the following components in weight percentage: 10-40% of amino-containing silicone resin; 10-70% of silane; 0.1-5% of fluorine compound; 15-50% of silica sol, and the mass ratio of the solid matter to water is 1:4-95. The passivation solution does not contain phosphorus and heavy metals. The passivation solution is roller-coated on the surface of the coated steel plate, and forms a dense passivation film after baking. The passivation film has excellent corrosion resistance and high temperature resistance. It does not change color after baking at a high temperature of more than 400°C for 3 hours, and still has certain corrosion resistance after baking. It can effectively extend the service life of the coated steel plate in a long-term high temperature environment, and is suitable for aluminum-zinc-plated, zinc-aluminum-magnesium-plated, and aluminum-silicon-plated steel plates.

Description

Technical Field

[0001] The invention relates to a steel plate surface passivation technology, and more specifically to a steel plate passivation solution, a preparation method thereof and a method for passivating a coated steel plate. Background Art

[0002] Chromium-free passivation technology can further improve the corrosion resistance of hot-dip coated steel plates, such as aluminum-zinc, zinc-aluminum-magnesium, and aluminum-silicon coated steel plates, and extend the service life of the steel plates. It has been widely used.

[0003] As environmental protection requirements become increasingly stringent, phosphorus and heavy metal ion emissions are subject to stricter control, especially for materials in contact with food, which have higher requirements for heavy metal elements. In September 2005, Germany's new Food and Dietary Supplies Act LFGB replaced the Food and Daily Necessities Act LMBG (Lebensmittel-und Futtermittelgesetzbuches), and made clear provisions on the migration of heavy metal elements.

[0004] Although the chromium-free passivation solution currently on the market does not contain chromium, its main components are silane composite zirconate, vanadate, molybdate or phosphate. For example, the main components of the existing passivation solution are: 10% to 20% silane, 5%-15% silica sol, 5%-15% zirconium oxide or fluorozirconate, 1%-10% phosphoric acid or phosphate, and 1%-10% vanadate. These acidic substances cause relatively high pressure on wastewater treatment. Therefore, the development of phosphorus-free and heavy metal-free passivation solution has a broad market prospect and is also a problem that needs to be solved urgently in this field.

[0005] Moreover, for coated steel plates used in high temperature environments, such as temperatures above 400°C, conventional passivation films cannot withstand high temperatures for a long time and will turn black or yellow, affecting product appearance and service life. Passivation films may even decompose at high temperatures and cause pollution. Therefore, a passivation film that can withstand high temperatures for a long time is needed.

[0006] Therefore, it is of great practical significance to provide an environmentally friendly steel plate passivation solution that is corrosion-resistant, high-temperature-resistant, phosphorus-free, and heavy metal-free. Summary of the invention

[0007] In view of the defects of the existing steel plate passivation coating technology, an object of the present invention is to provide a steel plate passivation solution, which is composed of solid matter and water, and the solid matter contains the following components in percentage by weight:

[0008]

[0009] The amino-containing silicone resin has a structure shown in the following general formula I:

[0010]

[0011] wherein n=3-10, m=1-8, p=1-6, R1 and R2 are each independently selected from alkanes containing 1 to 10 carbon atoms,

[0012] The mass ratio of the solid matter to water is 1:4-98.

[0013] In another preferred embodiment of the present invention, in the general formula I, n=5-8, m=2-5, p=1-5, R1 and R2 are each independently selected from alkanes containing 1 to 6 carbon atoms, for example, R1 and R2 are each independently selected from methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butanol, pentanol, and p=2-4.

[0014] In another preferred embodiment of the present invention, in the general formula I, R1 is selected from methyl, R2 is selected from methyl, p=2, and the structure of the amino silicone resin is:

[0015]

[0016] In another preferred embodiment of the present invention, the method for preparing the amino-containing silicone resin comprises the following steps:

[0017] The amino-containing silicone resin is obtained by condensing gamma-aminopropylmethyldimethoxysilane and methyltrimethoxysilane in an acidic aqueous solution and then end-capping with hexamethyldisiloxane.

[0018] In another preferred embodiment of the present invention, the acidic aqueous solution is a hydrochloric acid solution with a mass fraction of 14-18%.

[0019] In another preferred embodiment of the present invention, the temperature of the condensation reaction is 40-60° C., and the reaction time is 4-6 hours.

[0020] In another preferred embodiment of the present invention, the end-capping reaction time is 1 to 2 hours.

[0021] In another preferred embodiment of the present invention, the preparation method of the amino-containing silicone resin comprises the following steps:

[0022] (1) adding 0.4-0.5 mol of γ-aminopropylmethyldimethoxysilane and 0.1-0.5 mol of methyltrimethoxysilane to a 14-18% mass fraction hydrochloric acid solution, stirring and heating to 40-60° C. for a reaction time of 4-6 hours;

[0023] (2) adding 0.01-0.03 mol of hexamethyldisiloxane to the reaction solution of step (2) and reacting for 1-2 hours to perform end-capping;

[0024] (3) adding sodium carbonate to the reaction solution of step (2) to neutralize the reaction solution to a weak alkaline state, cooling and filtering, washing with deionized water, and vacuum drying at 80 to 120° C. to obtain an amino silicone resin.

[0025] In another preferred embodiment of the present invention, the silane is selected from γ-glycidyloxypropyltriethoxysilane, ethyl orthosilicate, γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane or a combination thereof.

[0026] In another preferred embodiment of the present invention, the fluorine compound is selected from titanium fluoride, zirconium fluoride, silicon fluoride, hydrofluoric acid, ammonium fluoride, ammonium bifluoride, or a combination thereof.

[0027] In another preferred embodiment of the present invention, the silica sol is an acidic silica sol with a pH of 2 to 5.

[0028] In another preferred embodiment of the present invention, the particle size of the acidic silica sol is 5 to 100 nm, and Na2O is less than 600 ppm.

[0029] The present invention also provides a method for preparing the above steel plate passivation solution, which comprises the following steps:

[0030] (1) Add amino silicone resin into deionized water and stir evenly for 5 to 20 minutes;

[0031] (2) adding silane and stirring until it is completely hydrolyzed;

[0032] (3) Add fluorine compound and silica sol in sequence, continue stirring for 25 to 40 minutes, and let stand.

[0033] The present invention also provides a method for passivating a coated steel plate, the method comprising the steps of directly applying the steel plate passivation solution to the surface of the coated steel plate, baking until the surface temperature of the steel plate reaches 70-150°C, and maintaining it for 2-10 seconds to form a passivation film on the surface of the steel plate.

[0034] In another preferred embodiment of the present invention, the thickness of the passivation film is 50-500 nm.

[0035] The steel plate passivation solution provided by the invention can be well adapted to aluminum-zinc-plated, zinc-aluminum-magnesium-plated and aluminum-silicon-plated steel plates. DETAILED DESCRIPTION

[0036] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific examples.

[0037] In view of the shortcomings of existing steel plate passivation coatings, the inventors of the present application have conducted in-depth research and developed a steel plate passivation liquid, which contains amino silicone resin, silane, fluorine compounds and silica sol, and does not contain phosphorus and heavy metals (such as chromium, vanadium, cobalt, nickel and other heavy metals). The passivation film formed by the passivation liquid can achieve surface passivation of the coated steel plate.

[0038] The steel plate passivation solution of the present invention is composed of solid matter and water, wherein the solid matter comprises the following components in percentage by weight:

[0039]

[0040] The amino-containing silicone resin has a structure shown in the following general formula I:

[0041]

[0042] wherein n=5-8, m=2-5, p=1-5, R1 and R2 are each independently selected from C 1～5 Alkanes,

[0043] The mass ratio of the solid matter to water is 1:4-98.

[0044] The amount of water used is such that the viscosity of the steel plate passivation liquid is such that when the steel plate passivation liquid is applied on the surface of the steel plate, the solid components are evenly distributed on the surface of the steel plate and are not easy to drip from the surface of the steel plate.

[0045] In the steel plate passivation solution of the present invention, the silane (B) and the amino-containing silicone resin (A) are hydrolyzed during heating, and then undergo a cross-linking reaction to form a dense passivation film network structure, which constitutes a passivation film skeleton. The silane that can be used in the present invention includes but is not limited to γ-glycidyloxypropyltriethoxysilane, ethyl orthosilicate, γ-methacryloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0046] In the steel plate passivation solution of the present invention, the fluorine compound (C) has the function of forming a slow release effect, thereby improving the corrosion resistance of the passivation film. The fluorine compounds that can be used in the present invention include but are not limited to titanium fluoride, zirconium fluoride, silicon fluoride, hydrofluoric acid, ammonium fluoride, and ammonium bifluoride.

[0047] In the steel plate passivation solution of the present invention, the silica sol (D) is used as a filler and a sealant, thereby improving the compactness of the passivation film and improving the corrosion resistance. The silica sol (D) that can be used in the present invention includes but is not limited to acidic silica sol, pH = 2 to 5, its particle size is 5-100nm, and Na2O < 600ppm.

[0048] The preparation method of the steel plate passivation solution of the present invention comprises the following steps:

[0049] (1) Adding amino silicone resin (A) into deionized water and stirring for 5-20 minutes;

[0050] (2) adding silane (B) and stirring until completely hydrolyzed;

[0051] (3) Add fluorine compound (C) and silica sol (D) in sequence, stir for 25-40 minutes, and let stand.

[0052] The steel plate passivation solution prepared in this way can be well applied to the passivation treatment of aluminum zinc, zinc aluminum magnesium, aluminum silicon plated steel plates, etc. The aluminum zinc, zinc aluminum magnesium, and aluminum silicon plated steel plates are specifically used in high temperature environments.

[0053] The method for passivating a coated steel plate of the present invention comprises the steps of directly coating (for example, by roller coating) the steel plate passivation solution on the surface of the coated steel plate, baking until the surface temperature of the steel plate reaches 70 to 150° C., and maintaining it for 2 to 10 seconds to form a passivation film on the surface of the steel plate.

[0054] The thickness of the passivation film can be 50 to 500 nm. As an example, the thickness of the passivation film is controlled by using coating rods of different numbers, and the specific thickness value can be measured by using GDS.

[0055] When the steel plate passivation liquid of the present invention is used to passivate the surface of the steel plate, the steel plate passivation liquid is roller-coated on the surface of the steel plate, and during baking, the amino silicone resin and silane are hydrolyzed, and the hydrolyzed amino silicone resin and silane undergo a cross-linking reaction to form a dense passivation film skeleton on the surface of the coated steel plate, and the nano-silica sol is embedded in the gaps and holes of the passivation film skeleton, further improving the density of the passivation film skeleton. In addition, the amino silicone resin and silane generate a large number of hydroxyl reaction groups after hydrolysis during the heating process, which are tightly adsorbed on the coating surface of the steel plate, so that the passivation film and the coating of the steel plate are connected as a whole, producing a good barrier effect, and there is no need to rely on phosphates and metal ions to provide corrosion resistance.

[0056] At the same time, the amino silicone resin used in the present invention itself has excellent high temperature resistance. After film formation, it does not change color after being baked at a high temperature of more than 400°C for 3 hours. After baking, the amino silicone resin does not decompose into small molecules, so it still has certain corrosion resistance, which can effectively extend the service life of the coated steel plate in a long-term high temperature environment.

[0057] The steel plate passivation solution of the present invention is suitable for aluminum-zinc-plated, zinc-aluminum-magnesium-plated and aluminum-silicon-plated steel plates. The thickness of the passivation film formed on the surface of the steel plate ranges from 50 to 500 nm, so the consumption is low.

[0058] Compared with the existing passivation solution, the steel plate passivation solution of the present invention has the following advantages:

[0059] (1) The steel plate passivation liquid of the present invention is roller-coated on the surface of the coated steel plate and forms a dense passivation film after baking. The passivation film has excellent corrosion resistance and excellent high temperature resistance. It does not change color after being baked at a high temperature of more than 400°C for 3 hours. It still has certain corrosion resistance after baking, which can effectively extend the service life of the coated steel plate in a long-term high temperature environment and is suitable for aluminum-zinc, zinc-aluminum-magnesium, and aluminum-silicon coated steel plates.

[0060] (2) It does not contain phosphorus and heavy metals (such as chromium, vanadium, cobalt, nickel, etc.), and fully complies with LFGB regulations.

[0061] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then proceed according to general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0062] Unless otherwise defined or indicated, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the method of the present invention.

[0063] Preparation of amino-containing silicone resin A1:

[0064] Step (1), adding 15% by mass hydrochloric acid solution into a three-necked flask;

[0065] Step (2), 0.5 mol of γ-aminopropylmethyldimethoxysilane (Shin-Etsu KBM904) and 0.5 mol of methyltrimethoxysilane (Evonik Degussa Dynasylan MTMS) were added to the solution of step (1) in sequence, and the mixture was heated to 50° C. with stirring for 5 hours;

[0066] Step (3), adding 0.01 mol of hexamethyldisiloxane (purchased from Tangshan Coupling Silicon Industry Co., Ltd.) to the reaction solution of step (2), reacting for 1 hour to cap the silane.

[0067] Step (4), adding sodium carbonate to the reaction solution of step (3) to neutralize the reaction solution to make it weakly alkaline, cooling and filtering, washing with deionized water and vacuum drying at 100° C. to obtain an amino silicone resin (A1) having a polymerization degree of n=5 and m=5.

[0068] Preparation of amino-containing silicone resin A2:

[0069] Step (1), adding 15% by mass hydrochloric acid solution into a three-necked flask.

[0070] Step (2), 0.4 mol of γ-aminopropylmethyldimethoxysilane (Shin-Etsu KBM904) and 0.1 mol of methyltrimethoxysilane (Evonik Degussa Dynasylan MTMS) were added to the solution of step (1) in sequence, and the mixture was heated to 50° C. with stirring for 5 hours;

[0071] Step (3), adding 0.01 mol of hexamethyldisiloxane (purchased from Tangshan Coupling Silicon Industry Co., Ltd.) to the mixture of step (2), reacting for 1 hour to cap the silane;

[0072] Step (4), adding sodium carbonate to the mixture of step (3) to neutralize the reaction solution to weak alkalinity, cooling and filtering, washing with deionized water and vacuum drying at 100° C. to obtain an amino silicone resin (A2) with a degree of polymerization of n=8 and m=2.

[0073] The preparation process of the steel plate passivation solution of Examples 1-9 and Comparative Examples 1-7 is as follows:

[0074] Step (1) Add amino silicone resin according to the ratio into deionized water and stir for 10 minutes.

[0075] Step (2) adding γ-glycidyloxypropyltriethoxysilane according to the ratio and stirring until it is completely hydrolyzed;

[0076] Step (3) Add fluorotitanic acid and silica sol in proportion, stir for 25-40 minutes and then leave for 30 minutes.

[0077] During the preparation of the steel plate passivation solution of Examples 1-9 and Comparative Examples 1-7, the mass ratio of solid matter to water is 1:4-98, preferably 1:20-50.

[0078] The preparation process of the steel plate passivation solution of Comparative Examples 8-11 is as follows:

[0079] Step (1) adding amino silicone resin into deionized water according to the ratio and stirring for 10 minutes;

[0080] Step (2) adding γ-glycidyloxypropyltriethoxysilane according to the ratio and stirring until it is completely hydrolyzed;

[0081] Step (3) adding fluorotitanic acid and silica sol in proportion and stirring for 10 minutes;

[0082] In step (4), the corresponding nickel sulfate (Comparative Example 8), or dichromic acid (Comparative Example 9), or sodium metavanadate (Comparative Example 10), or cobalt nitrate (Comparative Example 11) is added, stirred for 25-40 minutes, and then allowed to stand for 30 minutes.

[0083] The mass ratio of solid matter to water in the preparation process of the steel plate passivation solution of Comparative Examples 8-11 is 1:4-98, preferably 1:20-50.

[0084] The preparation process of the steel plate passivation solution of Comparative Example 12 is as follows:

[0085] Step (1) adding N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane into deionized water according to the ratio and stirring for 10 minutes;

[0086] Step (2) adding γ-glycidyloxypropyltriethoxysilane according to the ratio and stirring until it is completely hydrolyzed;

[0087] Step (3) Add fluorotitanic acid and silica sol in proportion, stir for 25-40 minutes and then leave for 30 minutes.

[0088] In the steel plate passivation solution preparation process of Comparative Example 12, the mass ratio of solid matter to water is 1:4-98, preferably 1:20-50.

[0089] The above steel plate passivation liquid was directly coated on the surface of the coated steel plate with a 1.5# wire rod, baked until the surface temperature of the steel plate reached 100°C and maintained for 5 seconds. After a dry film was formed on the surface of the steel plate, it was placed for 24 hours and tested.

[0090] In order to verify the environmental friendliness of the passivation solution provided by the solution of the present invention, nickel sulfate, dichromic acid, sodium metavanadate and cobalt nitrate were added to the passivation solutions of Comparative Examples 8-10 respectively.

[0091] The symbols in Table 1 have the following meanings:

[0092] A1: the amino-containing silicone resin prepared above (degree of polymerization n=5, m=5);

[0093] A2: the amino-containing silicone resin prepared above (degree of polymerization n=8, m=2);

[0094] A3: N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane (KBM-602, Shin-Etsu, Japan)

[0095] B: γ-glycidyloxypropyltriethoxysilane (Evonik Degussa Dynasylan GLYEO);

[0096] C: Fluotitanic acid (industrial grade, Nantong Jinxing Fluorine Chemical Co., Ltd.);

[0097] D: silica sol (Grace Davison LUDOX HAS);

[0098] E1: nickel sulfate (chemically pure from Sinopharm Chemical Reagent Company);

[0099] E2: dichromic acid (chemically pure from Sinopharm Chemical Reagent Company);

[0100] E3: sodium metavanadate (chemically pure from Sinopharm Chemical Reagent Company);

[0101] E4: Cobalt nitrate (chemically pure from Sinopharm Chemical Reagent Company).

[0102] The passivation solutions of the above embodiments and comparative examples were coated on the surfaces of aluminum-zinc-plated, zinc-aluminum-magnesium-plated, and aluminum-silicon-plated steel sheets, and the following test items were performed:

[0103] 1. Corrosion resistance: The neutral salt spray test is carried out according to the conditions in GB / T10125, and then the corrosion results are evaluated according to the provisions of GB12335-90; the corrosion resistance of the passivated plated steel plate is evaluated by the white rust area after 120 hours of salt spray time. The corrosion resistance of the passivated plated steel plate after high temperature baking at 400℃ is evaluated according to the provisions of GB12335-90, and the white rust area after 72 hours of salt spray time is evaluated.

[0104] 2. High temperature resistance: The color difference change is measured after baking at 400℃ for 3 hours in a heating furnace. If the color difference value △E≤3, it means that the high temperature resistance is good.

[0105] 3. The environmental protection test is verified by the heavy metal extraction method of the German Food and Daily Necessities Act (LFGB), and the entrusted testing agency is SGS.

[0106] Table 1 shows the components and contents (weight percentage) of the solid content of the passivation solutions of Examples 1-9 and Comparative Examples 1-12, as well as the types of coated steel sheets.

[0107]

[0108]

[0109] Table 2 Performance evaluation of passivation coated steel sheets of Examples 1-9 and Comparative Examples 1-12

[0110]

[0111]

[0112] Corrosion resistance evaluation:

[0113] Excellent white rust area ≤ 5% Good 5%<white rust area ≤ 8% Unqualified white rust area>8%;

[0114] High temperature resistance evaluation:

[0115] Excellent △E≤3 Good 3<△E≤5 Unqualified △E>5.

[0116] According to the data in Table 1 and Table 2, we can see that:

[0117] The mass ratio of each component of the passivation solution of Examples 1-9 to the total solid mass of the passivation solution is within the scope of the invention, and has qualified corrosion resistance and high temperature resistance.

[0118] In Comparative Examples 1 and 3, the mass contents of amino silicone resin and silane are lower than the content range requested for protection (the weight content of amino silicone resin is 10-40%; the weight content of silane is 10-70%), resulting in insufficient cross-linking reaction of the film, affecting the integrity of the film, and causing unqualified corrosion resistance.

[0119] If the amino-containing silicone resin is higher than the content range requested for protection (such as Comparative Example 2), too many unreacted amino groups remain, affecting the high temperature resistance.

[0120] The silica sol content is lower than the claimed range (such as Comparative Example 4), and the filling and sealing effects are insufficient, resulting in unqualified corrosion resistance.

[0121] The content of silica sol is higher than the content range requested for protection (such as Comparative Example 5), the proportion of amino silicone resin and silane is reduced, the cross-linking degree of the film is reduced, and the corrosion resistance is unqualified.

[0122] The content of the fluorine compound is lower than the content range required for protection (the weight content of the fluorine compound is 0.1 to 5%) (such as Comparative Example 5), and the corrosion inhibitor is insufficient, resulting in unqualified corrosion resistance.

[0123] The fluorine compound content is higher than the requested range (such as Comparative Example 6), which affects the bonding between the film and the substrate, resulting in unqualified corrosion resistance.

[0124] Compared with Example 2, the addition of heavy metal ions in Comparative Examples 8-10 does not significantly improve the corrosion resistance and high temperature resistance, indicating that the passivation solution of the present invention can achieve good high temperature resistance and corrosion resistance even without adding heavy metals, and complies with LFGB regulations.

[0125] Comparing Comparative Example 12 with Example 5, the high temperature resistance and corrosion resistance are significantly reduced by replacing the amino-containing silicone resin with conventional amino-containing silane.

[0126] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A steel plate passivation solution, consisting of solid matter and water, characterized in that: The solid content includes the following components in percentage by weight: The amino-containing silicone resin has a structure shown in the following general formula I: wherein n=3-10, m=1-8, p=1-6, R1 and R2 are each independently selected from alkanes containing 1 to 10 carbon atoms, The mass ratio of the solid matter to water is 1:4-98; In the general formula I, R1 is selected from methyl, R2 is selected from methyl, p=2, and the structure of the amino silicone resin is: The preparation of the amino-containing silicone resin comprises the following steps: γ-aminopropylmethyldimethoxysilane and methyltrimethoxysilane are subjected to condensation reaction in an acidic aqueous solution and then end-capped with hexamethyldisiloxane to obtain the amino-containing silicone resin; The acidic aqueous solution is a hydrochloric acid solution with a mass fraction of 14 to 18%; The condensation reaction temperature is 40-60° C., and the reaction time is 4-6 hours.

2. The steel plate passivation solution according to claim 1, characterized in that: In the general formula I, n=5-8, m=2-5, p=1-5, R1 and R2 are each independently selected from alkanes containing 1 to 6 carbon atoms.

3. The steel plate passivation solution according to claim 1 or 2, characterized in that: The silane is selected from γ-glycidyloxypropyltriethoxysilane, ethyl orthosilicate, γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane or a combination thereof.

4. The steel plate passivation solution according to claim 1 or 2, characterized in that: The fluorine compound is selected from titanium fluoride, zirconium fluoride, silicon fluoride, hydrofluoric acid, ammonium fluoride, ammonium bifluoride, or a combination thereof.

5. The steel plate passivation solution according to claim 1 or 2, characterized in that: The silica sol is acidic silica sol, with a pH value of 2-5, a particle size of 5-100 nm, and Na2O < 600 ppm.

6. The method for preparing a steel plate passivation solution according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) Add amino silicone resin into deionized water and stir for 5 to 20 minutes; (2) adding silane and stirring until it is completely hydrolyzed; (3) Add fluorine compound and silica sol in sequence, continue stirring for 25 to 40 minutes, and let stand.

7. A method for passivating a coated steel sheet, characterized in that: The method comprises the steps of: The steel plate passivation solution according to any one of claims 1 to 5 is directly coated on the surface of the coated steel plate, and baked until the surface temperature of the steel plate reaches 70 to 150° C. and maintained for 2 to 10 seconds to form a passivation film on the surface of the steel plate.

8. The method for passivating a coated steel sheet according to claim 7, characterized in that: The thickness of the passivation film is 50-500 nm.

Images