Water-based paint for aluminum material protection and preparation method of water-based paint

Abstract

The invention provides a water-based coating for aluminum material protection and a preparation method thereof, and belongs to the technical field of coatings. The preparation method comprises the following steps: condensing maleic acid through ionic liquid to obtain a monomer A, and copolymerizing the monomer A with hexafluorobutyl acrylate hydroxyethyl ester and butyl acrylate to obtain a polymer; the preparation method comprises the following steps: stirring and mixing phosphoric acid, chromium trioxide and aluminum dihydrogen phosphate to prepare a solution, and mixing water and magnesium oxide to prepare a suspension; dropwise adding the suspension into the solution for reaction, adding the coated magnesium powder and the polymer, adding the dispersing agent and the flatting agent, and uniformly mixing to obtain the water-based coating for aluminum material protection. The prepared water-based paint for aluminum material protection has good corrosion resistance, adhesive force, mechanical property and hardness, has good antibacterial, flame-retardant and high-temperature-resistant properties, improves the leveling property and the film-forming property of the paint, reduces the film coating defects, and has wide application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a water-based coating for aluminum protection and a preparation method thereof. Background Art

[0002] Metal profiles are widely used in the construction industry for their excellent durability, decorativeness, and processability. Aluminum profiles account for more than 80% of the metal profile usage due to their excellent processability and light weight. Aluminum, as an active metal, can easily react with oxygen in the air to form aluminum oxide when extruded and heated, and a thin film will form on the surface of the aluminum, which completely isolates the aluminum profile from external oxygen and prevents it from being corroded. However, this film will react chemically with most acidic or alkaline substances, and will be dissolved and corroded. Generally, after being corroded, it can only be returned to the furnace for smelting, resulting in a large waste of resources and energy.

[0003] The application of powder coatings in aluminum profiles has grown rapidly. Compared with anodizing and electrophoretic coating surface treatment methods, aluminum profiles sprayed with powder coatings have significantly reduced the degree of water and air pollution and energy consumption; the mechanical properties of the coating, such as hardness, wear resistance, and impact resistance, have been greatly improved, and the service life is 1 times higher than that of ordinary anodized aluminum profiles. In addition, the rich colors can better reflect the diversity and individuality of the building. At present, powder electrostatic spraying has become a hot spot in the surface coating of aluminum profiles in China. Powder spraying combined with thermal transfer technology will make the profile more fashionable, giving powder-coated profiles greater room for development.

[0004] Chinese invention patent CN104559591B discloses an environmentally friendly water-based coating for aluminum profile production and its preparation method, which is composed of the following components in weight fractions: 30-40 parts of water-based metal silicone acrylic resin; 5-10 parts of amino resin; 2-3 parts of adhesion promoter; 3-5 parts of propylene glycol methyl ether; 5-12 parts of polyurethane resin; 0.5-1 parts of leveling agent; 0.5-1 parts of thickener; the components of the adhesion promoter are calculated by weight: 0.5-2 parts of methyl bentonite; 0.1-0.5 parts of water-based alkyd resin. The water-based coating of the present invention has good adaptability to the surface material of the aluminum profile, good UV resistance and salt spray resistance, strong adhesion, simple process, no need to use a large amount of water for cleaning, and the water-based coating of the present invention will not cause pollution to the environment, and is green and environmentally friendly. However, the coating used on the surface of the aluminum profile is resin paint and resin powder, which emits harmful gases during production and use, has extremely high requirements for spraying equipment, and is difficult to meet environmental protection standards.

[0005] Chinese invention patent application CN107987685A discloses a UV-curable coating for aluminum alloy surface, which is composed of raw materials such as photo-crosslinking polymer, initiator, active diluent, filler, etc. The coating effectively improves the poor adhesion, water and heat resistance, alkali resistance, and weather resistance of traditional UV-curable coatings, and has strong adhesion, excellent impact resistance, weather resistance, and easy storage. The preparation method is simple and easy to construct. However, the UV-curable coating has poor alkali resistance at a film thickness of 30-40μm and is expensive. Summary of the invention

[0006] The purpose of the present invention is to provide a water-based coating 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 coating, reduces coating defects, and has broad application prospects.

[0007] The technical solution of the present invention is achieved in this way:

[0008] The invention provides a method for preparing a water-based coating for aluminum protection. The method comprises the following steps: subjecting maleic acid to condensation with an ionic liquid to obtain a monomer A, copolymerizing the monomer A with hexafluorobutyl hydroxyethyl acrylate and butyl acrylate to obtain a polymer; stirring and mixing phosphoric acid, chromium trioxide and aluminum dihydrogen phosphate to obtain a solution; mixing water and magnesium oxide to obtain a suspension; dropping the suspension into the solution for reaction, adding coated magnesium powder and the polymer, adding a dispersant and a leveling agent, and mixing the mixture uniformly to obtain the water-based coating for aluminum protection.

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

[0010] S1. Add maleic acid to water, add EDC and NHS, stir to activate, add N-(3-aminopropyl)imidazole (1-(3-aminopropyl)imidazole), stir to react, and prepare monomer A;

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

[0012] S3. Under inert gas protection, adding an initiator and water to the monomer solution, adjusting the total mass concentration of the monomer, heating and stirring the reaction, washing the product with ethanol, filtering, drying, and pulverizing to obtain a polymer;

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

[0014] S5. The magnesium powder was ball-milled, added to ethanol, graphene oxide and a silane coupling agent with a double bond were added, ultrasonically dispersed uniformly, heated and stirred for reaction, and spray-dried to obtain coated magnesium powder;

[0015] S6. Mix water and magnesium oxide to obtain a suspension;

[0016] S7. Add the suspension dropwise into 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.

[0017] As a further improvement of the present invention, the molar ratio of maleic acid, NHS, EDC, and N-(3-aminopropyl)imidazole in step S1 is 1:0.2-0.4:0.2-0.4:0.9-1, the stirring activation temperature is 0-4°C, the time is 20-40min, and the stirring reaction time is 8-10h.

[0018] As a further improvement of the present invention, in step S2, the mass ratio of monomer A, hexafluorobutyl hydroxyethyl acrylate, and butyl acrylate 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 invention, the amount of the initiator added in step S3 is 1-2wt% of the total mass of the system, the total mass concentration of the adjusted monomers is 25-30wt%, the temperature of the heated and stirred reaction is 45-55°C, 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 invention, the mass ratio of phosphoric acid, chromium trioxide and aluminum dihydrogen phosphate in step S4 is 10-15:2-3:1-2.

[0021] As a further improvement of the present invention, the ball milling time in step S5 is 1-2h, the mass ratio of the magnesium powder, graphene oxide and the silane coupling agent with double bonds is 3-5:2-4:1-2, 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 and the time is 2-4h.

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

[0023] As a further improvement of the present invention, 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°C, the time is 1-2h, the pH value of the adjusted solution is 1.8-2.2, the pore size of the filter used for filtration is 200-300μm, the leveling agent is BYK-333, and the dispersant is BYK-191.

[0024] The present invention further protects a water-based coating for aluminum protection obtained by the above-mentioned preparation method.

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

[0026] The invention 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 coating, can improve the flexibility and impact resistance of the acrylic resin, maintains a certain hardness, improves the leveling property and film-forming property of the acrylic resin, and reduces coating defects.

[0027] The product of the coating of the present invention after high-temperature curing contains aluminum phosphate and magnesium metaphosphate. After the coating is applied to aluminum, its main film-forming substance, aluminum dihydrogen phosphate, can chemically react with the aluminum during the curing process to generate a stable and dense aluminum phosphate structure. Since the generated Al-O bond structure increases the bonding force between the paint film and the aluminum substrate, the coating can adhere well to the aluminum substrate, greatly improving the adhesion of the coating and, at the same time, improving the corrosion resistance of the coating.

[0028] The present invention coats magnesium powder with a silane coupling agent with double bonds and graphene oxide. Graphene has a small size effect and can be filled into holes and defects of the coating, preventing and delaying the penetration of small molecular corrosive media into the metal matrix, which can greatly improve the corrosion resistance of the coating. At the same time, the dense physical isolation layer formed can cut off the contact between the polymer and oxygen, preventing the further spread of the fire, and has flame retardant and smoke suppression effects. The silane coupling agent with double bonds can be hydrolyzed to form a silicon oxygen layer to protect the magnesium powder, and can copolymerize with the molecular weight of the polyacrylic resin polymer to improve the dispersibility and compatibility of the coated magnesium powder and the mechanical properties of the coating.

[0029] In a corrosive liquid, the coating of the present invention will undergo a sacrificial anode protection process, giving priority to the reaction of magnesium powder. When the magnesium powder is wrapped, the difficulty of the reaction increases, inhibiting anodic oxidation for protection, thereby greatly improving the protection of the aluminum material of the coating and having excellent corrosion resistance.

[0030] The aluminum material protective water-based coating prepared by the present invention 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 broad application prospects. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] NHS, N-hydroxysuccinimide; EDC, 1-ethyl-(3-dimethylaminopropyl)carbodiimide; graphene oxide, purity>99%, sheet diameter 2-4 μm, thickness 1-1.5 nm, purchased from Hepfill New Materials Co., Ltd.

[0033] Example 1

[0034] This embodiment provides a method for preparing a water-based coating for aluminum 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, and the mixture was stirred and activated at 0°C for 20 min, 9 mmol of N-(3-aminopropyl)imidazole was added, and the mixture was stirred and reacted for 8 h, and ethanol was added until the ethanol content of the system was 90 wt %, and the mixture was 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 hydroxyethyl acrylate, and 4 g of butyl acrylate were added to water to adjust the total mass concentration of the monomers to 35 wt % to obtain a monomer solution;

[0037] S3. Under nitrogen protection, sodium persulfate and water were added to the monomer solution, the amount of sodium persulfate added was 1wt% of the total mass of the system, the total mass concentration of the monomer was adjusted to 25wt%, heated to 45°C, stirred for reaction for 3h, 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 at 1000 W for 10 min, heated to 40 ° C, stirred for reaction for 2 h, and spray-dried to obtain coated magnesium powder;

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

[0041] S7. Add 20g of the suspension dropwise into 50g of the solution, adjust the pH value of the solution to 1.8, heat to 50°C, stir and react for 1h, adjust the pH value of the solution to neutral, add 50g of water, 5g of coated magnesium powder and 20g of polymer, stir and mix for 15min, add 1g of dispersant BYK-191 and 1g of leveling agent BYK-333, ultrasonically disperse at 1000W for 10min, ball mill for 1h, filter with a filter with a pore size of 200μm, and obtain a water-based coating for aluminum protection.

[0042] Example 2

[0043] This embodiment provides a method for preparing a water-based coating for aluminum protection, comprising the following steps:

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

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

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

[0048] S5. 5 g of magnesium powder was ball-milled for 2 h, added to 100 mL of ethanol, 4 g of graphene oxide and 2 g of silane coupling agent A151 were added, ultrasonically dispersed at 1000 W for 10 min, heated to 50 ° C, stirred for 4 h, and spray-dried to obtain coated magnesium powder;

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

[0050] S7. Add 40g of the suspension dropwise into 70g of the solution, adjust the pH value of the solution to 2.2, heat to 60°C, stir and react for 2h, adjust the pH value of the solution to neutral, add 80g of water, 7g of coated magnesium powder and 25g of polymer, stir and mix for 15min, add 2g of dispersant BYK-191 and 2g of leveling agent BYK-333, ultrasonically disperse at 1000W for 10min, ball mill for 1h, filter with a filter with a pore size of 300μm, and obtain a water-based coating for aluminum protection.

[0051] Example 3

[0052] This embodiment provides a method for preparing a water-based coating for aluminum protection, comprising the following steps:

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

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

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

[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 to obtain a solution;

[0057] S5. 4 g of magnesium powder was ball-milled for 1.5 h, added to 100 mL of ethanol, 3 g of graphene oxide and 1.5 g of silane coupling agent KH570 were added, ultrasonically dispersed at 1000 W for 10 min, heated to 45 ° C, stirred for 4 h, and spray-dried to obtain coated magnesium powder;

[0058] S6. 10 mL of water and 0.85 g of magnesium oxide were stirred and mixed for 5 min to obtain a suspension;

[0059] S7. Add 30g of the suspension dropwise into 60g of the solution, adjust the pH value of the solution to 2, heat to 55°C, stir and react for 1.5h, adjust the pH value of the solution to neutral, add 65g of water, 6g of coated magnesium powder and 22g of polymer, stir and mix for 15min, add 1.5g of dispersant BYK-191 and 1.5g of leveling agent BYK-333, ultrasonically disperse at 1000W for 10min, ball mill for 1h, filter with a filter with a pore size of 300μm, and obtain a water-based coating for aluminum protection.

[0060] Comparative Example 1

[0061] Compared with Example 3, the difference is that monomer A is not added in step S2.

[0062] The details are as follows:

[0063] S2. Add 8 g of hexafluorobutyl hydroxyethyl acrylate and 5 g of butyl acrylate into water and adjust the total mass concentration of the monomers to 37 wt % to obtain a monomer solution.

[0064] Comparative Example 2

[0065] Compared with Example 3, the difference is that graphene oxide is not added in step S5.

[0066] The details are as follows:

[0067] S5. Ball-mill 4 g of magnesium powder for 1.5 h, add it to 100 mL of ethanol, add 4.5 g of silane coupling agent KH570, ultrasonically disperse it at 1000 W for 10 min, heat it to 45 ° C, stir it for 4 h, and spray dry it to obtain coated magnesium powder.

[0068] Comparative Example 3

[0069] Compared with Example 3, the difference is that the silane coupling agent KH570 is not added in step S5.

[0070] The details are as follows:

[0071] S5. Ball-mill 4 g of magnesium powder for 1.5 h, add it to 100 mL of ethanol, add 4.5 g of graphene oxide, ultrasonically disperse it at 1000 W for 10 min, heat it to 45 ° C, stir it for 4 h, and spray dry it to obtain coated magnesium powder.

[0072] Comparative Example 4

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

[0074] The details are as follows:

[0075] S7. Add 30g of the suspension dropwise into 60g of the solution, adjust the pH value of the solution to 2, heat to 55°C, stir and react for 1.5h, adjust the pH value of the solution to neutral, add 65g of water, 6g of magnesium powder and 22g of polymer, stir and mix for 15min, add 1.5g of dispersant BYK-191 and 1.5g of leveling agent BYK-333, ultrasonically disperse at 1000W for 10min, ball mill for 1h, filter with a filter with a pore size of 300μm, and obtain a water-based coating for aluminum protection.

[0076] Comparative Example 5

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

[0078] The details are as follows:

[0079] S1. 10 mmol of maleic acid was added to 100 mL of water, 3 mmol of EDC and 3 mmol of NHS were added, and the mixture was stirred and activated at 2°C for 30 min, 9.5 mmol of N-(3-aminopropyl)imidazole was added, and the mixture was stirred and reacted for 9 h, ethanol was added until the ethanol content of the system was 90 wt %, and the mixture was precipitated for 1 h, the solid was washed, and dried to obtain monomer A;

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

[0081] S3. Under nitrogen protection, ammonium persulfate and water were added to the monomer solution, the amount of ammonium persulfate added was 1.5wt% of the total mass of the system, the total mass concentration of the monomer was adjusted to 27wt%, heated to 50°C, stirred for 4h, the product was washed with ethanol, filtered, dried, and crushed to obtain a polymer;

[0082] S4. 4 g of magnesium powder was ball-milled for 1.5 h, added to 100 mL of ethanol, 3 g of graphene oxide and 1.5 g of silane coupling agent KH570 were added, ultrasonically dispersed at 1000 W for 10 min, heated to 45 ° C, stirred for 4 h, and spray-dried to obtain coated magnesium powder;

[0083] S5. 155g of water, 6g of coated magnesium powder and 22g of polymer were stirred and mixed for 15 minutes, 1.5g of dispersant BYK-191 and 1.5g of leveling agent BYK-333 were added, ultrasonic dispersion was performed at 1000W for 10 minutes, ball milling was performed for 1 hour, and the mixture was filtered through a filter with a pore size of 300μm to obtain a water-based coating for aluminum protection.

[0084] Test Example 1

[0085] The aluminum protective water-based coatings prepared in Examples 1-3 and Comparative Examples 1-5 were sprayed on aluminum plates according to the requirements of GB / T1727-2021. The following tests were performed, and the results are shown in Table 1.

[0086] The neutral salt spray resistance test was carried out in accordance with the provisions of GB / T1771-2007 "Determination of neutral salt spray resistance of paints and varnishes" on a JD-120 (600L) salt spray tester. The mass concentration of the sodium chloride solution was (50±5) g / L and the pH was 6.5-7.0.

[0087] The acid resistance is tested according to the immersion method specified in GB / T9274-1988 "Determination of resistance of paints and varnishes to liquid media", with a sulfuric acid mass fraction of 5%. Defects are observed after immersion for 24 hours.

[0088] The organic solvent resistance test is carried out according to the manual wiping method specified in GB / T23989-2009 "Determination of Solvent Resistance of Coatings by Wiping". Wipe back and forth 25 times with a finger wrapped in absorbent cotton to observe whether it is damaged and the base material is exposed.

[0089] The seawater resistance test was carried out in accordance with GB / T 1733-1993 “Determination of water resistance of paint films”, with water replaced by seawater.

[0090] Table 1

[0091]

[0092]

[0093] It can be seen from the above table that the aluminum protective water-based coatings prepared in Examples 1-3 of the present invention have good corrosion resistance.

[0094] Test Example 2

[0095] The aluminum protective water-based coatings prepared in Examples 1-3 and Comparative Examples 1-5 were sprayed on aluminum plates according to the requirements of GB / T1727-2021. The following tests were performed, and the results are shown in Table 2.

[0096] Adhesion test: The adhesion is tested according to GB / T5210-2006 coating adhesion test method (pull-off method).

[0097] Flexibility test refers to GB / T1731-2020.

[0098] The impact resistance test refers to GB / T1732-2020. The mass of the heavy hammer is (1000±1)g. The paint film is magnified 4 times to observe whether it is damaged. The maximum height of the heavy hammer falling when there is no damage is the measurement result.

[0099] Use an oxygen index meter to test the limiting oxygen index of the coating.

[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] It can be seen from the above table that the aluminum protection water-based coatings prepared in Examples 1-3 of the present invention have good adhesion, flexibility, mechanical properties and flame retardant properties.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a water-based coating for aluminum protection, characterized in that: The monomer A is prepared by condensing maleic acid with ionic liquid, and copolymerized with hexafluorobutyl hydroxyethyl acrylate and butyl acrylate to prepare a polymer; phosphoric acid, chromium trioxide and aluminum dihydrogen phosphate are stirred and mixed to prepare a solution, and water and magnesium oxide are mixed to prepare a suspension; the suspension is dropped into the solution for reaction, and coated magnesium powder and polymer are added, and a dispersant and a leveling agent are added and mixed evenly to prepare a water-based coating for aluminum protection.

2. The preparation method according to claim 1, characterized in that: The following steps are involved: S1. Add maleic acid to water, add EDC and NHS, stir to activate, add N-(3-aminopropyl)imidazole (1-(3-aminopropyl)imidazole), stir to react, and prepare monomer A; S2. The monomer A, hexafluorobutyl hydroxyethyl acrylate and butyl acrylate in step S1 are added to water, and the total mass concentration of the monomers is adjusted to obtain a monomer solution; S3. Under inert gas protection, adding an initiator and water to the monomer solution, adjusting the total mass concentration of the monomer, heating and stirring the reaction, washing the product with ethanol, filtering, drying, and pulverizing to obtain a polymer; S4. The phosphoric acid, chromium trioxide and aluminum dihydrogen phosphate are mixed to obtain a solution; S5. The magnesium powder was ball-milled, added to ethanol, graphene oxide and a silane coupling agent with a double bond were added, ultrasonically dispersed uniformly, heated and stirred for reaction, and spray-dried to obtain coated magnesium powder; S6. Mix water and magnesium oxide to obtain a suspension; S7. Add the suspension dropwise into 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.

3. The preparation method according to claim 2, characterized in that: In step S1, 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, the stirring activation temperature is 0-4°C, the time is 20-40min, and the stirring reaction time is 8-10h.

4. The preparation method according to claim 2, characterized in that: In step S2, the mass ratio of monomer A, hexafluorobutyl hydroxyethyl acrylate, and butyl acrylate is 3-5:7-10:4-6, and the total mass concentration of the monomers is 35-40wt%.

5. The preparation method according to claim 2, characterized in that: In step S3, the amount of the initiator added is 1-2wt% of the total mass of the system, the total mass concentration of the adjusted monomer is 25-30wt%, the temperature of the heated and stirred reaction is 45-55°C, the time is 3-5h, and the initiator is selected from at least one of potassium persulfate, sodium persulfate, and ammonium persulfate.

6. The preparation method according to claim 2, characterized in that: The mass ratio of phosphoric acid, chromium trioxide and aluminum dihydrogen phosphate in step S4 is 10-15:2-3:1-2.

7. The preparation method according to claim 2, characterized in that: The ball milling time in step S5 is 1-2h, the mass ratio of the magnesium powder, graphene oxide and the silane coupling agent with a double bond is 3-5:2-4:1-2, the silane coupling agent with a double bond is selected from at least one of KH570, A151, and A171, and the heating and stirring reaction temperature is 40-50°C and the time is 2-4h.

8. The preparation method according to claim 2, characterized in that: The mass ratio of water to magnesium oxide in step S6 is 100:7-10.

9. The preparation method according to claim 2, characterized in that: 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°C, the time is 1-2h, the pH value of the adjusted solution is 1.8-2.2, the pore size of the filter used for filtration is 200-300μm, the leveling agent is BYK-333, and the dispersant is BYK-191.

10. A water-based coating for aluminum protection obtained by the preparation method according to any one of claims 1 to 9.

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