Water-based coating for aluminum material protection and preparation method thereof

Abstract

The application provides an aluminum material protection water-based paint and a preparation method thereof, and belongs to the technical field of paints. A monomer A is prepared by condensation of maleic acid through an ionic liquid, and copolymerization of hexafluorobutyl acrylate hydroxyethyl ester and butyl acrylate to obtain a polymer; a solution is prepared by stirring and mixing phosphoric acid, chromium trioxide and aluminum dihydrogen phosphate; a suspension is prepared by mixing water and magnesium oxide; the suspension is added dropwise into the solution to react, magnesium powder and the polymer are added, a dispersing agent and a leveling agent are added, and the mixture is uniformly mixed to obtain the aluminum material protection water-based paint. The aluminum material protection water-based paint prepared by the application has good corrosion resistance, good adhesion, good mechanical properties and hardness, good antibacterial, flame-retardant and high-temperature resistance, improved leveling and film-forming properties of the paint, reduced coating film defects, and a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paint technology, in particular to a water-based paint for protecting aluminum materials and a preparation method thereof. BACKGROUND

[0002] Metal profiles are widely used in the construction industry due to their excellent durability, decorative properties and processing properties. Aluminum profiles account for more than 80% of the total amount of metal profiles due to their good processing properties and light weight. As a kind of active metal, aluminum is easily chemically reacted with oxygen in the air to form aluminum oxide under heat and pressure, and a thin film is formed on the surface of the aluminum, which completely separates the aluminum profile from the external oxygen and prevents corrosion. However, this thin film is chemically reacted with most acidic or alkaline substances, which is dissolved and corroded. After corrosion, the only way is to re-melt, which causes a large amount of resource and energy waste.

[0003] The application of powder coatings in aluminum profiles has rapidly grown. Compared with anodic oxidation and electrophoretic coating surface treatment methods, the powder coated aluminum profiles have significantly reduced pollution to water and atmosphere and energy consumption; the mechanical properties of the coating film such as hardness, wear resistance and impact resistance are greatly improved, the service life is 1 times higher than that of ordinary anodized aluminum profiles, and the color is rich, which can better reflect the diversification and individualization of buildings. At present, powder electrostatic spraying has become a hot spot in the surface coating of domestic aluminum profiles. The combination of powder spraying and hot transfer printing technology will make the profiles more fashionable, and the powder sprayed profiles will have greater development space.

[0004] Chinese invention patent CN104559591B discloses an environmentally friendly water-based paint for aluminum profile production and a preparation method thereof, which is composed of the following components by weight fraction: water-based metal silicone propylene resin 30-40 parts; amino resin 5-10 parts; adhesion promoter 2-3 parts; propylene glycol methyl ether 3-5 parts; polyurethane resin 5-12 parts; leveling agent 0.5-1 part; thickening agent 0.5-1 part; the components of the adhesion promoter include methyl bentonite 0.5-2 parts and water-based alkyd resin 0.1-0.5 parts by weight. The water-based paint has good adaptability to the surface material of aluminum profiles, good resistance to ultraviolet light and salt spray, strong adhesion, simple process, no need for cleaning with a large amount of water, and no pollution to the environment. However, the paint used on the surface of aluminum profiles is resin paint and resin powder, which emits harmful gases during production and use, requires high spraying equipment, and is difficult to meet environmental protection standards.

[0005] Chinese invention patent application CN107987685A discloses a kind of for the surface of aluminum alloy ultraviolet light curing paint, is by light crosslinking type polymer, initiator, active diluent, filler etc. Raw material composition, the paint effectively improved the adhesion of traditional ultraviolet light curing paint, water resistance, heat resistance, alkali resistance, the problem of poor weather resistance, and strong adhesion, excellent impact resistance, also have weather resistance, the characteristics of being convenient to save, simple preparation method, it is convenient to construction. However, the alkali resistance of the ultraviolet light curing paint is poor under 30-40 μm film thickness, and the cost is high. SUMMARY

[0006] The purpose of the present application is to provide a water-based paint for aluminum protection and a preparation method thereof, which has good corrosion resistance, good adhesion, good mechanical properties and hardness, good antibacterial, flame retardant and high temperature resistance, improves the leveling and film forming properties of the paint, reduces the film defects, and has a wide application prospect.

[0007] The technical solution of the present application is as follows:

[0008] The present application provides a preparation method of a water-based paint for aluminum protection. Maleic acid is condensed with an ionic liquid to obtain monomer A, which is copolymerized with hexafluorobutyl acrylate hydroxyethyl and butyl acrylate to obtain a polymer. Phosphoric acid, chromium trioxide and aluminum dihydrogen phosphate are stirred and mixed to obtain a solution. Water and magnesium oxide are mixed to obtain a suspension. The suspension is added dropwise into the solution for reaction, and coated magnesium powder and the polymer are added. A dispersant and a leveling agent are added and uniformly mixed to obtain the water-based paint for aluminum protection.

[0009] As a further improvement of the present application, the following steps are included:

[0010] S1. Maleic acid is added to water, EDC and NHS are added, stirred and activated, N-(3-aminopropyl)imidazole (1-(3-aminopropyl)imidazole) is added, stirred and reacted to obtain monomer A;

[0011] S2. Monomer A, hexafluorobutyl acrylate hydroxyethyl and butyl acrylate in step S1 are added to water, and the total mass concentration of monomers is adjusted to obtain a monomer solution;

[0012] S3. Under the protection of inert gas, initiator and water are added to the monomer solution, the total mass concentration of monomers is adjusted, heated and stirred for reaction, the product is washed with ethanol, filtered, dried, and crushed to obtain a polymer;

[0013] S4. Phosphoric acid, chromium trioxide and aluminum dihydrogen phosphate are uniformly mixed to obtain a solution;

[0014] S5. Magnesium powder is ball milled, added into ethanol, graphene oxide and double bond containing silane coupling agent are added, ultrasonically dispersed uniformly, heated and stirred for reaction, and spray dried to obtain coated magnesium powder;

[0015] S6. The water and magnesium oxide are mixed uniformly to obtain a suspension;

[0016] S7. The suspension is added dropwise into the solution, the pH value of the solution is adjusted, the reaction is heated, the pH value of the solution is adjusted to neutral, water, magnesium powder and a polymer are added, and the mixture is stirred and mixed uniformly, a dispersing agent and a leveling agent are added, ultrasonic dispersion is performed uniformly, ball milling is performed, and filtration is performed to obtain a water-based paint for protecting aluminum materials.

[0017] As a further improvement of the present application, the molar ratio of the maleic acid, the NHS, the EDC, and the N-(3-aminopropyl)imidazole in step S1 is 1:0.2-0.4:0.2-0.4:0.9-1, the temperature of the stirring activation is 0-4℃, and the time is 20-40min.

[0018] As a further improvement of the present application, the mass ratio of the monomer A, the hexafluorobutyl acrylate hydroxyethyl ester, and the butyl acrylate in step S2 is 3-5:7-10:4-6, and the total mass concentration of the monomers is 35-40wt%.

[0019] As a further improvement of the present application, the addition amount of the initiator in step S3 is 1-2wt% of the total mass of the system, the total mass concentration of the monomers is adjusted to 25-30wt%, the temperature of the heating and stirring reaction is 45-55℃, and the time is 3-5h, and the initiator is selected from at least one of potassium persulfate, sodium persulfate, and ammonium persulfate.

[0020] As a further improvement of the present application, the mass ratio of the phosphoric acid, the chromium trioxide, and the aluminum dihydrogen phosphate in step S4 is 10-15:2-3:1-2.

[0021] As a further improvement of the present application, the time of the ball milling in step S5 is 1-2h, the mass ratio of the magnesium powder, the graphene oxide, and the double-bond-containing silane coupling agent is 3-5:2-4:1-2, the double-bond-containing silane coupling agent is selected from at least one of KH570, A151, and A171, the temperature of the heating and stirring reaction is 40-50℃, and the time is 2-4h.

[0022] As a further improvement of the present application, the mass ratio of the water and the magnesium oxide in step S6 is 100:7-10.

[0023] As a further improvement of the present application, the mass ratio of the suspension, solution, water, coated magnesium powder, polymer, dispersant and leveling agent in step S7 is 20-40:50-70:50-80:5-7:20-25:1-2:1-2, the temperature of the heating reaction is 50-60 DEG C, the time is 1-2h, the pH value of the adjusted solution is 1.8-2.2, the filter screen aperture used in the filtration is 200-300 mu m, the leveling agent is BYK-333, and the dispersant is BYK-191.

[0024] The present application further protects a water-based paint for protecting aluminum materials prepared by the above preparation method.

[0025] The present application has the following beneficial effects:

[0026] The present application reacts maleic acid with N-(3-aminopropyl) imidazole through a condensation reaction, has a high thermal decomposition temperature, improves the antibacterial property and thermal stability of the polyacrylate polymer paint, can improve the flexibility and impact resistance of the acrylic resin while maintaining a certain hardness, improves the leveling property and film-forming property of the acrylic resin, and reduces coating film defects.

[0027] The product after high-temperature curing of the paint of the present application contains aluminum phosphate and magnesium metaphosphate, and after the paint is coated on an aluminum material, the main film-forming substance, aluminum dihydrogen phosphate, can react with the aluminum material to form a stable and dense aluminum phosphate structure during the curing process, and the generated Al-O bond structure increases the adhesion of the paint film to the aluminum material substrate, so the paint can be well attached to the aluminum material substrate, greatly improving the adhesion of the paint, and at the same time, improving the corrosion resistance of the paint.

[0028] The present application coats magnesium powder with a silane coupling agent with a double bond and graphene oxide, graphene has a small size effect and can fill into the pores and defects of the paint, preventing and delaying the immersion of small molecule corrosion media into the metal matrix, which can greatly improve the corrosion resistance of the coating, and the dense physical isolation layer formed can block the contact between the polymer and oxygen, preventing further spread of the fire, and has flame-retardant and smoke-suppressing effects. The silane coupling agent with a double bond can hydrolyze to form a silicon oxide layer to protect the magnesium powder, and can copolymerize with the polyacrylate polymer to improve the dispersibility and compatibility of the coated magnesium powder, and also improve the mechanical properties of the paint.

[0029] In a corrosive liquid, the paint of the present application will undergo a sacrificial anode protection process, and the magnesium powder will react preferentially, and when the magnesium powder is coated, the difficulty of the reaction increases, inhibiting anodic oxidation and providing protection, thereby greatly improving the protection of the aluminum material by the paint and having excellent corrosion resistance.

[0030] The prepared water-based coating for aluminum material protection has good corrosion resistance, good adhesion, good mechanical properties and hardness, good antibacterial, flame retardant and high temperature resistance, improves the leveling and film forming properties of the coating, reduces coating defects, and has wide application prospect. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0032] NHS, N-hydroxysuccinimide; EDC, 1-ethyl-(3-dimethylaminopropyl) carbonyl diimide; graphene oxide, purity > 99%, flake diameter 2-4 μm, thickness 1-1.5 nm, purchased from Hepufuli New Material Co., Ltd.

[0033] Embodiment 1

[0034] The present embodiment provides a preparation method of a water-based coating for aluminum material protection, comprising the following steps:

[0035] S1. 10 mmol of maleic acid was added to 100 mL of water, 2 mmol of EDC and 2 mmol of NHS were added, stirred at 0℃ for 20 min, 9 mmol of N-(3-aminopropyl) imidazole was added, stirred for 8 h, ethanol was added to the system to a content of 90 wt%, precipitated for 1 h, the solid was washed and dried to obtain monomer A;

[0036] S2. 3 g of monomer A in step S1, 7 g of hexafluorobutyl acrylate hydroxyethyl, and 4 g of butyl acrylate were added to water, and the total mass concentration of monomers was adjusted to 35 wt% to obtain a monomer solution;

[0037] S3. Under the protection of nitrogen, sodium persulfate and water were added to the monomer solution, the amount of sodium persulfate added was 1 wt% of the total mass of the system, the total mass concentration of monomers was adjusted to 25 wt%, heated to 45℃, stirred for 3 h, the product was washed with ethanol, filtered, dried, and crushed to obtain a polymer;

[0038] S4. 10 g of phosphoric acid, 2 g of chromium trioxide, and 1 g of aluminum dihydrogen phosphate were stirred and mixed for 15 min to obtain a solution;

[0039] S5. 3 g of magnesium powder was ball milled for 1 h, added to 100 mL of ethanol, 2 g of graphene oxide and 1 g of silane coupling agent A171 were added, ultrasonically dispersed for 10 min at 1000 W, heated to 40℃, stirred for 2 h, and spray dried to obtain coated magnesium powder;

[0040] S6. 10 mL of water, 0.7 g of magnesium oxide were stirred and mixed for 5 min to prepare a suspension;

[0041] S7. 20 g of the suspension was added dropwise into 50 g of the solution, the pH value of the solution was adjusted to 1.8, heated to 50℃, stirred and reacted for 1 h, the pH value of the solution was adjusted to neutral, 50 g of water, 5 g of the coated magnesium powder and 20 g of the polymer were added, stirred and mixed for 15 min, 1 g of dispersant BYK-191 and 1 g of leveling agent BYK-333 were added, 1000 W ultrasonic dispersion was performed for 10 min, ball milling was performed for 1 h, a filter screen with a pore size of 200 μm was used for filtration to prepare the water-based paint for aluminum protection.

[0042] Example 2

[0043] The embodiment provides a preparation method of a water-based paint for aluminum protection, comprising the following steps:

[0044] S1. 10 mmol of maleic acid was added into 100 mL of water, 4 mmol of EDC and 4 mmol of NHS were added, stirred and activated at 4℃ for 40 min, 10 mmol of N-(3-aminopropyl)imidazole was added, stirred and reacted for 10 h, ethanol was added until the ethanol content of the system was 90 wt%, precipitated for 1 h, the solid was washed and dried to prepare monomer A;

[0045] S2. 5 g of the monomer A in step S1, 10 g of hexafluorobutyl acrylate hydroxyethyl ester and 6 g of butyl acrylate were added into water, the total mass concentration of the monomers was adjusted to 40 wt% to obtain a monomer solution;

[0046] S3. Under the protection of nitrogen, potassium persulfate and water were added into the monomer solution, the addition amount of potassium persulfate was 2 wt% of the total mass of the system, the total mass concentration of the monomers was adjusted to 30 wt%, heated to 55℃, stirred and reacted for 5 h, the product was washed with ethanol, filtered, dried and crushed to prepare a polymer;

[0047] S4. 15 g of phosphoric acid, 3 g of chromium trioxide and 2 g of aluminum dihydrogen phosphate were stirred and mixed for 15 min to prepare a solution;

[0048] S5. 5 g of magnesium powder was ball milled for 2 h, added into 100 mL of ethanol, 4 g of graphene oxide and 2 g of silane coupling agent A151 were added, 1000 W ultrasonic dispersion was performed for 10 min, heated to 50℃, stirred and reacted for 4 h, and spray dried to prepare a coated magnesium powder;

[0049] S6. 10 mL of water, 1 g of magnesium oxide were stirred and mixed for 5 min to prepare a suspension;

[0050] S7. 40 g of the suspension was added dropwise into 70 g of the solution, the pH value of the solution was adjusted to 2.2, heated to 60℃, and stirred for 2 h, the pH value of the solution was adjusted to neutral, 80 g of water, 7 g of magnesium powder coated with magnesium, and 25 g of the polymer were added, and stirred for 15 min, 2 g of dispersant BYK-191 and 2 g of leveling agent BYK-333 were added, 1000 W ultrasonic dispersion was performed for 10 min, ball milling was performed for 1 h, filtration was performed using a filter screen with a pore size of 300 μm, and thus an aluminum material protective water-based paint was prepared.

[0051] Example 3

[0052] The present embodiment provides a preparation method of an aluminum material protective water-based paint, comprising the following steps:

[0053] S1. 10 mmol of maleic acid was added into 100 mL of water, 3 mmol of EDC and 3 mmol of NHS were added, and stirred for 30 min at 2℃, 9.5 mmol of N-(3-aminopropyl)imidazole was added, and stirred for 9 h, ethanol was added until the ethanol content of the system was 90 wt%, and then precipitated for 1 h, and the solid was washed and dried, thus monomer A was prepared;

[0054] S2. 4 g of monomer A in step S1, 8 g of hexafluorobutyl acrylate hydroxyethyl ester, and 5 g of butyl acrylate were added into water, and the total mass concentration of the monomers was adjusted to 37 wt%, thus a monomer solution was obtained;

[0055] S3. Under the protection of nitrogen, ammonium persulfate and water were added into the monomer solution, the addition amount of ammonium persulfate was 1.5 wt% of the total mass of the system, the total mass concentration of the monomers was adjusted to 27 wt%, heated to 50℃, and stirred for 4 h, the product was washed with ethanol, filtered, dried, and crushed, thus a polymer was prepared;

[0056] S4. 12 g of phosphoric acid, 2.5 g of chromium trioxide, and 1.5 g of aluminum dihydrogen phosphate were stirred and mixed for 15 min, thus a solution was prepared;

[0057] S5. 4 g of magnesium powder was ball milled for 1.5 h, added into 100 mL of ethanol, 3 g of graphene oxide and 1.5 g of silane coupling agent KH570 were added, 1000 W ultrasonic dispersion was performed for 10 min, heated to 45℃, and stirred for 4 h, and then spray dried, thus magnesium powder coated with magnesium was prepared;

[0058] S6. 10 mL of water and 0.85 g of magnesium oxide were stirred and mixed for 5 min, thus a suspension was prepared;

[0059] S7. 30 g of the suspension was added dropwise into 60 g of the solution, the pH value of the solution was adjusted to 2, heated to 55 °C, stirred for 1.5 h, the pH value of the solution was adjusted to neutral, 65 g of water, 6 g of magnesium powder coated with magnesium and 22 g of the polymer were added, stirred for 15 min, 1.5 g of dispersant BYK-191 and 1.5 g of leveling agent BYK-333 were added, 1000 W ultrasonic dispersion was performed for 10 min, ball milling was performed for 1 h, filtration was performed using a filter screen with a pore size of 300 μm, and an aqueous coating for aluminum was prepared.

[0060] Comparative Example 1

[0061] Compared with Example 3, the difference lies in that no monomer A is added in step S2.

[0062] The specific process is as follows:

[0063] S2. 8 g of hexafluorobutyl acrylate hydroxyethyl ester and 5 g of butyl acrylate were added into water, and the total mass concentration of the monomers was adjusted to 37 wt% to obtain a monomer solution.

[0064] Comparative Example 2

[0065] Compared with Example 3, the difference lies in that no graphene oxide is added in step S5.

[0066] The specific process is as follows:

[0067] S5. 4 g of magnesium powder was ball milled for 1.5 h, added into 100 mL of ethanol, 4.5 g of silane coupling agent KH570 was added, 1000 W ultrasonic dispersion was performed for 10 min, heated to 45 °C, stirred for 4 h, and spray dried to obtain magnesium powder coated with magnesium.

[0068] Comparative Example 3

[0069] Compared with Example 3, the difference lies in that no silane coupling agent KH570 is added in step S5.

[0070] The specific process is as follows:

[0071] S5. 4 g of magnesium powder was ball milled for 1.5 h, added into 100 mL of ethanol, 4.5 g of graphene oxide was added, 1000 W ultrasonic dispersion was performed for 10 min, heated to 45 °C, stirred for 4 h, and spray dried to obtain magnesium powder coated with magnesium.

[0072] Comparative Example 4

[0073] Compared with Example 3, the difference lies in that the magnesium powder coated with magnesium in step S7 is replaced by magnesium powder.

[0074] The specific process is as follows:

[0075] S7. 30 g of the suspension was added dropwise into 60 g of the solution, the pH value of the solution was adjusted to 2, heated to 55℃, and stirred for 1.5 h, the pH value of the solution was adjusted to neutral, 65 g of water, 6 g of magnesium powder and 22 g of the polymer were added, stirred and mixed for 15 min, 1.5 g of dispersant BYK-191 and 1.5 g of leveling agent BYK-333 were added, 1000 W ultrasonic dispersion was performed for 10 min, ball milling was performed for 1 h, filtration was performed using a filter screen with a pore size of 300 μm, and an aluminum material protective water-based paint was prepared.

[0076] Comparative Example 5

[0077] Compared with Example 3, the difference is that no suspension and solution are added in step S7, and an equal amount of water is used instead.

[0078] The specific process is as follows:

[0079] S1. 10 mmol of maleic acid was added into 100 mL of water, 3 mmol of EDC and 3 mmol of NHS were added, 2℃ stirring was performed for 30 min, 9.5 mmol of N-(3-aminopropyl)imidazole was added, stirring reaction was performed for 9 h, ethanol was added until the ethanol content of the system was 90 wt%, precipitation was performed for 1 h, the solid was washed and dried, and monomer A was prepared;

[0080] S2. 4 g of monomer A in step S1, 8 g of hexafluorobutyl acrylate hydroxyethyl ester and 5 g of butyl acrylate were added into water, the total mass concentration of the monomers was adjusted to 37 wt%, and a monomer solution was obtained;

[0081] S3. Under the protection of nitrogen, ammonium persulfate and water were added into the monomer solution, the addition amount of ammonium persulfate was 1.5 wt% of the total mass of the system, the total mass concentration of the monomers was adjusted to 27 wt%, heated to 50℃, and stirring reaction was performed for 4 h, the product was washed with ethanol, filtered, dried, and crushed, and a polymer was prepared;

[0082] S4. 4 g of magnesium powder was ball milled for 1.5 h, added into 100 mL of ethanol, 3 g of graphene oxide and 1.5 g of silane coupling agent KH570 were added, 1000 W ultrasonic dispersion was performed for 10 min, heated to 45℃, and stirring reaction was performed for 4 h, and spray drying was performed, and coated magnesium powder was prepared;

[0083] S5. 155 g of water, 6 g of coated magnesium powder and 22 g of the polymer were stirred and mixed for 15 min, 1.5 g of dispersant BYK-191 and 1.5 g of leveling agent BYK-333 were added, 1000 W ultrasonic dispersion was performed for 10 min, ball milling was performed for 1 h, filtration was performed using a filter screen with a pore size of 300 μm, and an aluminum material protective water-based paint was prepared.

[0084] Test Example 1

[0085] The water-based coating for aluminum material protection prepared from Examples 1-3 and Comparative Examples 1-5 was sprayed on aluminum material plates according to the requirements of GB / T1727-2021. The following tests were conducted, and the results are shown in Table 1.

[0086] The neutral salt spray resistance test was conducted on a JD-120 (600L) type salt spray tester according to the provisions of GB / T1771-2007 "Determination of the Resistance to Neutral Salt Spray of Paints and Varnishes", with a sodium chloride solution having a mass concentration of (50±5) g / L and a pH of 6.5-7.0.

[0087] The acid resistance was tested according to the immersion method specified in GB / T9274-1988 "Determination of the Resistance to Liquid Media of Paints and Varnishes", with a sulfuric acid mass fraction of 5%, and defects were observed after immersion for 24 h.

[0088] The organic solvent resistance test was conducted according to the manual rubbing method specified in GB / T23989-2009 "Determination of the Resistance to Solvent Rubbing of Coatings", with a degreasing cotton wrapped finger rubbing back and forth for 25 times, and whether the coating was damaged to expose the substrate was observed.

[0089] The seawater resistance test was conducted according to GB / T 1733-1993 "Determination of the Resistance to Water of Paint Films", with water replaced by seawater.

[0090] Table 1

[0091]

[0092]

[0093] As can be seen from the above table, the water-based coating for aluminum material protection prepared from Examples 1-3 has good corrosion resistance.

[0094] Test Example 2

[0095] The water-based coating for aluminum material protection prepared from Examples 1-3 and Comparative Examples 1-5 was sprayed on aluminum material plates according to the requirements of GB / T1727-2021. The following tests were conducted, and the results are shown in Table 2.

[0096] The adhesion test was conducted according to GB / T5210-2006 "Test Method for Adhesion of Coatings (Pull-Off Method)".

[0097] The flexibility test was conducted according to GB / T1731-2020.

[0098] The impact resistance test was conducted according to GB / T1732-2020, with a weight of (1000±1) g, and the film was observed for damage at 4 times magnification. The maximum weight drop height at which the film was not damaged was taken as the measurement result.

[0099] The limiting oxygen index of the coating was tested using an oxygen index instrument.

[0100] Table 2

[0101] Group Adhesion (grade) Flexibility (mm) Impact strength (kg-cm) Limiting oxygen index (%) Example 1 0 0.15 87 32.8 Example 2 0 0.13 88 33.2 Example 3 0 0.12 90 33.9 Comparative Example 1 0 0.29 77 30.1 Comparative Example 2 0 0.22 80 28.6 Comparative Example 3 1 0.24 75 30.8 Comparative Example 4 1 0.27 72 30.1 Comparative Example 5 2 0.20 84 31.2

[0102] From the above table, it can be seen that the water-based paint for protecting aluminum material prepared by the embodiments 1-3 of the present application has good adhesion, flexibility, mechanical properties and flame retardant properties.

[0103] The above description is merely preferred embodiments of the present application, but not to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a water-based protective coating for aluminum materials, characterized in that, Includes the following steps: S1. Maleic acid is added to water, EDC and NHS are added, the mixture is stirred to activate the mixture, N-(3-aminopropyl)imidazole is added, and the mixture is stirred to react, thereby obtaining monomer A; the molar ratio of maleic acid, NHS, EDC and N-(3-aminopropyl)imidazole is 1:0.2-0.4:0.2-0.4:0.9-1. S2. Add monomer A, hexafluorobutyl hydroxyethyl acrylate, and butyl acrylate from step S1 to water, adjust the total mass concentration of monomers, and obtain a monomer solution; the mass ratio of monomer A, hexafluorobutyl hydroxyethyl acrylate, and butyl acrylate is 3-5:7-10:4-6. S3. Under inert gas protection, an initiator and water are added to the monomer solution to adjust the total mass concentration of the monomer. The mixture is heated and stirred to react. The product is washed with ethanol, filtered, dried, and pulverized to obtain the polymer. The amount of initiator added is 1-2 wt% of the total mass of the system, and the total mass concentration of the monomer is adjusted to 25-30 wt%. S4. Phosphoric acid, chromium trioxide, and aluminum dihydrogen phosphate are mixed evenly to prepare a solution; the mass ratio of phosphoric acid, chromium trioxide, and aluminum dihydrogen phosphate is 10-15:2-3:1-2. S5. The magnesium powder is ball-milled, added to ethanol, graphene oxide and silane coupling agent with double bonds are added, ultrasonically dispersed evenly, heated and stirred to react, and spray-dried to obtain coated magnesium powder; the mass ratio of the magnesium powder, graphene oxide and silane coupling agent with double bonds is 3-5:2-4:1-2. S6. Mix water and magnesium oxide evenly to obtain a suspension; the mass ratio of water to magnesium oxide is 100:7-10; S7. Add the suspension droplets to the solution, adjust the pH value of the solution, heat the reaction, adjust the pH value of the solution to neutral, add water, coated magnesium powder and polymer, stir and mix evenly, add dispersant and leveling agent, ultrasonically disperse evenly, ball mill, filter, and obtain a water-based coating for aluminum protection; the mass ratio of the suspension, solution, water, coated magnesium powder, polymer, dispersant and leveling agent is 20-40:50-70:50-80:5-7:20-25:1-2:1-2.

2. The preparation method according to claim 1, characterized in that, The temperature for stirring activation in step S1 is 0-4℃, the time is 20-40 min, and the stirring reaction time is 8-10 h.

3. The preparation method according to claim 1, characterized in that, The total mass concentration of the monomers mentioned in step S2 is 35-40 wt%.

4. The preparation method according to claim 1, characterized in that, The heating and stirring reaction in step S3 is carried out at a temperature of 45-55°C for 3-5 hours, and the initiator is selected from at least one of potassium persulfate, sodium persulfate, and ammonium persulfate.

5. The preparation method according to claim 2, characterized in that, The ball milling time in step S5 is 1-2 hours, the silane coupling agent with double bonds is selected from at least one of KH570, A151, and A171, and the heating and stirring reaction temperature is 40-50°C for 2-4 hours.

6. The preparation method according to claim 2, characterized in that, The heating reaction in step S7 is carried out at a temperature of 50-60℃ for 1-2 hours. The pH value of the solution is adjusted to 1.8-2.

2. The filter screen used for filtration has a pore size of 200-300μm. The leveling agent is BYK-333 and the dispersant is BYK-191.

7. A water-based protective coating for aluminum materials prepared by the preparation method according to any one of claims 1-6.

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