Anti-corrosion and anti-rust coating for aluminum alloy and preparation method thereof

Abstract

The invention belongs to the technical field of coatings, and particularly relates to an anti-corrosion and anti-rust coating for an aluminum alloy and a preparation method thereof. A product 2 is prepared through an epoxy compound ring-opening reaction and an esterification reaction in sequence, then the product 2 and hydroxyl silicone oil are used for synergistic modification of epoxy resin to obtain modified epoxy resin, and organosilicon, a benzene ring, a fluorine element and a phosphorus element are introduced into an epoxy resin structure through a three-step method. According to the invention, the modified epoxy resin and the acrylic resin are taken as substrates and are compounded with the raw materials such as the nano silica sol, the antirust agent and the organic bentonite, and the raw materials and process conditions are optimized, so that the prepared coating has excellent adhesive force, heat resistance, flame retardance, mechanical property and corrosion and rust resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to an anti-corrosion and anti-rust coating for aluminum alloy and a preparation method thereof. Background Art

[0002] Aluminum alloy is a common alloy material with advantages such as high specific strength, low density, good processing performance and heat treatment strengthening. It has good application prospects in the aerospace field, but its low corrosion resistance limits its further development and application. Anti-corrosion and anti-rust coating refers to a coating that can resist erosion from the external environment and protect the substrate from corrosion and rust. It is usually used on metal surfaces and has the characteristics of weather resistance and chemical corrosion resistance.

[0003] The patent with application number CN202110081111.X provides a solvent-free anti-corrosion coating, which mainly includes the following components: solvent-free epoxy resin, acrylic resin, anti-rust pigment, nano-silica sol, alkali metal silicate solution, filler, corrosion inhibitor, active diluent, coupling agent, anti-fouling agent, anti-settling agent. The invention avoids the use of solvents, reduces the content of toxic and harmful volatiles in VOC, has the advantages of environmental protection and safety, has good adhesion to concrete and steel structure substrates, and has the advantages of safe use, environmental protection, and good anti-corrosion performance; the patent with application number CN202210419644.9 provides a thermal insulation, heat insulation, anti-rust and anti-corrosion coating for vehicle chassis, which mainly includes the following components: acrylic modified alkyd resin, epoxy resin, nano-silica, dispersant, composite magnesium aluminum silicate, dodecyl alcohol ester, and deionized water. The invention uses acrylic modified alkyd resin and epoxy resin as the base, and by compounding with nano-silica, the water resistance, anti-rust and anti-corrosion properties and wear resistance of the coating are improved. Epoxy resin is added to the above patents. The epoxy resin molecules contain polar groups such as hydroxyl groups and ether bonds, which make the resin have strong interaction with adjacent interface molecules and excellent adhesion. The cured epoxy resin-based coating also has good acid resistance, alkali resistance and organic solvent resistance. However, the existing epoxy resin-based coatings have problems such as poor high temperature resistance, poor impact resistance, poor weather resistance, and its flame retardant properties need to be improved. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an anti-corrosion and anti-rust coating for aluminum alloys, which has excellent comprehensive performance; the present invention also provides a method for preparing the anti-corrosion and anti-rust coating for aluminum alloys.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: An anticorrosion and antirust coating for aluminum alloy comprises the following components in parts by weight: 30-40 parts of modified epoxy resin, 20-30 parts of acrylic resin, 7-13 parts of nano silica sol, 0.5-1.5 parts of surfactant, 1-3 parts of coupling agent, 0.2-0.7 parts of rust inhibitor, and 0.1-0.5 parts of organic bentonite; the preparation method of the modified epoxy resin is as follows: S1. Under stirring conditions, raise the temperature of 5,6-epoxyhexyltriethoxysilane to 65-75°C, add dibutyl phosphate dropwise, and complete the addition within 0.5-1.5 hours. Then raise the temperature to 75-85°C, continue the reaction for 3.5-4.5 hours, and cool to room temperature to obtain product 1. S2, under stirring conditions, dispersing 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid in cyclohexane, raising the temperature to 75-85° C., then sequentially adding the product 1 obtained in step S1 and p-toluenesulfonic acid, reacting under reflux for 5-8 hours, cooling to room temperature, and obtaining product 2 after purification; S3, under nitrogen atmosphere and stirring conditions, raising the temperature of the epoxy resin to 60-70°C, then adding the product 2 obtained in step S2 and dibutyltin dilaurate in sequence, reacting for 1-3h, then raising the temperature to 130-150°C, then adding hydroxy silicone oil, continuing the reaction for 4-6h, and cooling to room temperature to obtain a modified epoxy resin;

[0006] Wherein, the synthetic route of product 2 is as follows: ; .

[0007] The invention uses 5,6-epoxyhexyltriethoxysilane and dibutyl phosphate as starting materials, and performs an epoxy compound ring-opening reaction under heating conditions to obtain product 1; then uses product 1 and 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid as raw materials, and performs an esterification reaction under the catalytic action of p-toluenesulfonic acid to obtain product 2; finally, under the catalytic action of dibutyltin dilaurate, epoxy resin is synergistically modified by using product 2 and hydroxy silicone oil to obtain modified epoxy resin.

[0008] In order to functionalize the epoxy resin, the molar ratio of 5,6-epoxyhexyltriethoxysilane and dibutyl phosphate in step S1 is 1:0.7-0.8; the molar ratio of 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid, product 1 and p-toluenesulfonic acid in step S2 is 1:0.8-1.0:0.04-0.05, and the mass volume ratio of cyclohexane and 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid is 0.15-0.20 g / mL; the mass ratio of the epoxy resin, product 2, dibutyltin dilaurate and hydroxy silicone oil in step S3 is 10:0.5-0.7:0.015-0.020:1.3-1.6.

[0009] Furthermore, the surfactant is one or more of polyoxypropylene glycerol ether, polyoxypropylene oxyethylene glycerol ether, and polydimethylsiloxane; the coupling agent is one or more of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570; and the rust inhibitor is iron phosphate or calcium fluorophosphate.

[0010] The present invention also provides a method for preparing an anticorrosion and antirust coating for aluminum alloy, comprising the following steps: uniformly mixing a modified epoxy resin and an acrylic resin, heating the mixture to 40-50°C, adding nano-silica sol and organic bentonite in sequence, continuing to stir for 5-10 minutes, then adding a coupling agent, a surfactant, and a rust inhibitor in sequence, continuing to stir for 10-20 minutes, and cooling the mixture to room temperature to obtain the coating.

[0011] The present invention has the following beneficial effects: The present invention sequentially prepares product 2 through ring-opening reaction of epoxy compounds and esterification reaction, and then uses product 2 and hydroxy silicone oil to synergistically modify epoxy resin to obtain modified epoxy resin, and introduces organosilicon, benzene ring, fluorine element and phosphorus element into the epoxy resin structure by three-step method. The siloxane segment in organosilicon has high thermal stability, which can effectively protect the thermal degradation of organic matter, thereby improving the heat resistance of epoxy resin materials; organosilicon can also improve the affinity between epoxy resin and inorganic materials, thereby giving full play to the reinforcing effect of inorganic materials and improving the chemical corrosion resistance of composite materials; organosilicon can also combine epoxy resin-based materials with substrates by chemical bonding, thereby improving the adhesion of composite coatings. Fluorine atoms have high electronegativity, and the CF bonds formed with carbon atoms are very stable and difficult to be destroyed by chemical media, which can effectively improve the chemical corrosion resistance of epoxy resin-based materials. The introduction of benzene rings provides an additional rigid structure for epoxy resin, which helps to improve the overall heat resistance of epoxy resin, thereby improving the heat resistance of composite coatings. The synergistic effect of fluorine and benzene ring can significantly improve the impact resistance of epoxy resin and thus the impact resistance of composite coatings by improving the flexibility of epoxy resin, improving the intermolecular force, and enhancing the uniformity of the cross-linking network. In addition, silicone can also work synergistically with fluorine and phosphorus to improve the flame retardant properties of epoxy resin materials, thereby improving the flame retardant properties of composite coatings.

[0012] The present invention uses modified epoxy resin and acrylic resin as the base, and compounding with nano silica sol, rust inhibitor, organic bentonite and other raw materials to prepare a coating with excellent adhesion, heat resistance, flame retardancy, mechanical properties and anti-corrosion and anti-rust properties. DETAILED DESCRIPTION

[0013] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0014] Epoxy resin, model E51, density 1.2g / cm 3 , content ≥99%, brand Phoenix; hydroxy silicone oil, model SI-205, hydroxyl content 1.5%, brand Shengbang silicone; acrylic resin, active ingredient content 55%, brand 518, brand Aohui; calcium fluorophosphate, mesh number 200, purity ≥99%, brand Huaxiang; iron phosphate, density 2.74g / cm 3 , active ingredient content 98%, brand Guohua Chemical; polyoxypropylene glycerol ether, density 2.1g / cm 3, active ingredient content 99%, brand Xing Hengye; polyoxypropylene oxyethylene glycerol ether, content 99%, brand Huaxiang Kejie; polydimethylsiloxane, PEG / PPG-25 / 30 copolymer, active ingredient content 99%, brand Huaxiang Kejie; nano silica sol, particle size 8-15nm, silicon dioxide content 30±1%, pH value 9.5-11.0, brand Jikang; organic bentonite, density 1.8g / cm 3 , active ingredient content 99%, model B27, brand Haimingsi. The raw materials used in the following examples are all common commercial products.

[0015] Example 1 A method for preparing a modified epoxy resin comprises the following steps: S1. Under stirring conditions, the temperature of 5,6-epoxyhexyltriethoxysilane was raised to 70° C., and dibutyl phosphate was added dropwise. The addition was completed within 1 hour, and then the temperature was raised to 80° C., and the reaction was continued for 4 hours. The mixture was naturally cooled to room temperature to obtain product 1; wherein the molar ratio of 5,6-epoxyhexyltriethoxysilane to dibutyl phosphate was 1:0.75; S2. Under stirring conditions, 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid is dispersed in cyclohexane, the temperature is increased to 80°C, and then the product 1 obtained in step S1 and p-toluenesulfonic acid are added in sequence, the reaction is carried out under reflux for 7 hours, the mixture is naturally cooled to room temperature, filtered, the filtrate is taken, extracted with ethyl acetate, separated, the ester layer is taken, the ester layer is washed with a saturated sodium chloride solution, and then dried over anhydrous sodium sulfate, and then concentrated and dried in vacuo to constant weight to obtain product 2; wherein the molar ratio of 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid, product 1, and p-toluenesulfonic acid is 1:0.9:0.045, the mass volume ratio of cyclohexane to 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid is 0.18 g / mL, and the volume ratio of cyclohexane to ethyl acetate is 1:1; The NMR results of product 2 are: 1H NMR (300MHz, DMSO-d6) δ 8.62 (s, 2H), 6.90 (d, 1H), 6.66-6.71 (m, 2H), 4.56-4.59 (m, 1H), 4.36-4.40 (m, 1 H), 4.10-4.13 (m, 1H), 4.01 (t, 4H), 3.80-3.84 (m, 6H), 3.55 (s, 1H), 3.28 (s, 1H), 2.89-2.92 (m, 1H), 2.80-2.82 (m, 1H), 2.29-2.33 (m, 1H), 2.04-2.07 (m, 1H), 1.6 5-1.69 (m, 4H), 1.43-1.49 (m, 6H), 1.21-1.25 (m, 13H), 0.95 (t, 6H), 0.56 (t, 2H); S3. Under nitrogen atmosphere and stirring conditions, the temperature of the epoxy resin is raised to 65°C, and the product 2 obtained in step S2 and dibutyltin dilaurate are added in sequence, and the reaction is carried out for 2 hours. The temperature is then raised to 140°C, and hydroxy silicone oil is added, and the reaction is continued for 5 hours. The mixture is cooled to room temperature to obtain a modified epoxy resin; wherein the mass ratio of the epoxy resin, the product 2, the dibutyltin dilaurate and the hydroxy silicone oil is 10:0.6:0.018:1.4.

[0016] An anticorrosion and antirust coating for aluminum alloy comprises the following components in parts by weight: 35 parts of modified epoxy resin, 25 parts of acrylic resin, 11 parts of nano-silica sol, 1 part of surfactant, 2 parts of coupling agent, 0.5 parts of rust inhibitor and 0.3 parts of organic bentonite; wherein the surfactant is polydimethylsiloxane, the coupling agent is silane coupling agent KH550, and the rust inhibitor is iron phosphate.

[0017] A method for preparing an anticorrosion and antirust coating for aluminum alloy comprises the following steps: uniformly mixing a modified epoxy resin and an acrylic resin, heating the mixture to 45°C, sequentially adding nano silica sol and organic bentonite, stirring the mixture at a speed of 1500 rpm for 8 minutes, sequentially adding a coupling agent, a surfactant and a rust inhibitor, stirring the mixture at a speed of 1000 rpm for 15 minutes, and naturally cooling the mixture to room temperature to obtain the coating.

[0018] Example 2 A method for preparing a modified epoxy resin comprises the following steps: S1. Under stirring conditions, the temperature of 5,6-epoxyhexyltriethoxysilane was raised to 65° C., and dibutyl phosphate was added dropwise. The addition was completed within 1.5 hours, and then the temperature was raised to 75° C., and the reaction was continued for 4.5 hours. The mixture was naturally cooled to room temperature to obtain product 1; wherein the molar ratio of 5,6-epoxyhexyltriethoxysilane to dibutyl phosphate was 1:0.7; S2. Under stirring conditions, 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid is dispersed in cyclohexane, the temperature is raised to 75°C, and then the product 1 obtained in step S1 and p-toluenesulfonic acid are added in sequence, the reaction is carried out under reflux for 8 hours, the mixture is naturally cooled to room temperature, filtered, the filtrate is taken, extracted with ethyl acetate, separated, the ester layer is taken, the ester layer is washed with a saturated sodium chloride solution, and then dried over anhydrous sodium sulfate, and then concentrated and dried in vacuo to constant weight to obtain product 2; wherein the molar ratio of 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid, product 1, and p-toluenesulfonic acid is 1:0.8:0.04, the mass volume ratio of cyclohexane to 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid is 0.2 g / mL, and the volume ratio of cyclohexane to ethyl acetate is 1:1; S3. Under nitrogen atmosphere and stirring conditions, the temperature of the epoxy resin is raised to 60°C, and the product 2 obtained in step S2 and dibutyltin dilaurate are added in sequence, and the reaction is carried out for 3 hours. The temperature is then raised to 130°C, and hydroxy silicone oil is added, and the reaction is continued for 6 hours. The mixture is cooled to room temperature to obtain a modified epoxy resin; wherein the mass ratio of the epoxy resin, the product 2, the dibutyltin dilaurate and the hydroxy silicone oil is 10:0.5:0.015:1.3.

[0019] An anticorrosion and antirust coating for aluminum alloy comprises the following components in parts by weight: 30 parts of modified epoxy resin, 30 parts of acrylic resin, 13 parts of nano-silica sol, 1.5 parts of surfactant, 1 part of coupling agent, 0.7 parts of rust inhibitor and 0.1 parts of organic bentonite; wherein the surfactant is polyoxypropylene glycerol ether, the coupling agent is silane coupling agent KH560, and the rust inhibitor is iron phosphate.

[0020] A method for preparing an anticorrosion and antirust coating for aluminum alloy comprises the following steps: uniformly mixing a modified epoxy resin and an acrylic resin, heating the mixture to 40°C, sequentially adding nano silica sol and organic bentonite, stirring the mixture at a speed of 1500 rpm for 10 min, sequentially adding a coupling agent, a surfactant and a rust inhibitor, stirring the mixture at a speed of 1000 rpm for 20 min, and naturally cooling the mixture to room temperature to obtain the coating.

[0021] Example 3 A method for preparing a modified epoxy resin comprises the following steps: S1. Under stirring conditions, the temperature of 5,6-epoxyhexyltriethoxysilane was raised to 75° C., and dibutyl phosphate was added dropwise. The addition was completed within 0.5 h, and then the temperature was raised to 85° C., and the reaction was continued for 3.5 h. The mixture was naturally cooled to room temperature to obtain product 1; wherein the molar ratio of 5,6-epoxyhexyltriethoxysilane to dibutyl phosphate was 1:0.8; S2. Under stirring conditions, 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid is dispersed in cyclohexane, the temperature is raised to 85°C, and then the product 1 obtained in step S1 and p-toluenesulfonic acid are added in sequence, the reaction is carried out under reflux for 5 hours, the mixture is naturally cooled to room temperature, filtered, the filtrate is taken, and extracted with ethyl acetate, the liquid is separated, the ester layer is taken, the ester layer is washed with a saturated sodium chloride solution, and then dried over anhydrous sodium sulfate, and then concentrated and dried in vacuo to constant weight to obtain product 2; wherein the molar ratio of 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid, product 1, and p-toluenesulfonic acid is 1:1:0.05, the mass volume ratio of cyclohexane to 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid is 0.15 g / mL, and the volume ratio of cyclohexane to ethyl acetate is 1:1; S3. Under nitrogen atmosphere and stirring conditions, the temperature of the epoxy resin is raised to 70°C, and the product 2 obtained in step S2 and dibutyltin dilaurate are added in sequence, and the reaction is carried out for 1 hour. Then the temperature is raised to 150°C, and hydroxy silicone oil is added, and the reaction is continued for 4 hours. The mixture is cooled to room temperature to obtain a modified epoxy resin; wherein the mass ratio of the epoxy resin, the product 2, the dibutyltin dilaurate and the hydroxy silicone oil is 10:0.7:0.02:1.6.

[0022] An anticorrosion and antirust coating for aluminum alloy comprises the following components in parts by weight: 40 parts of modified epoxy resin, 20 parts of acrylic resin, 7 parts of nano-silica sol, 0.5 parts of surfactant, 3 parts of coupling agent, 0.2 parts of rust inhibitor and 0.5 parts of organic bentonite; wherein the surfactant is polyoxypropylene oxyethylene glycerol ether, the coupling agent is silane coupling agent KH570, and the rust inhibitor is calcium fluorophosphate.

[0023] A method for preparing an anticorrosion and antirust coating for aluminum alloy comprises the following steps: uniformly mixing a modified epoxy resin and an acrylic resin, heating the mixture to 50°C, sequentially adding nano silica sol and organic bentonite, stirring the mixture at a speed of 1500 rpm for 5 minutes, sequentially adding a coupling agent, a surfactant and a rust inhibitor, stirring the mixture at a speed of 1000 rpm for 10 minutes, and naturally cooling the mixture to room temperature to obtain the coating.

[0024] Example 4 A method for preparing a modified epoxy resin is prepared according to the method described in Example 1.

[0025] An anticorrosion and antirust coating for aluminum alloy comprises the following components in parts by weight: 33 parts of modified epoxy resin, 28 parts of acrylic resin, 10 parts of nano-silica sol, 1.2 parts of surfactant, 2 parts of coupling agent, 0.6 parts of rust inhibitor and 0.4 parts of organic bentonite; wherein the surfactant is polydimethylsiloxane, the coupling agent is silane coupling agent KH550, and the rust inhibitor is iron phosphate.

[0026] A method for preparing an anti-corrosion and anti-rust coating for aluminum alloy is prepared according to the method described in Example 1.

[0027] Comparative Example 1 An anticorrosion and antirust coating for aluminum alloy comprises the following components in parts by weight: 15 parts of modified epoxy resin prepared in Example 1, 45 parts of acrylic resin, 10 parts of nano-silica sol, 2 parts of surfactant, 3 parts of coupling agent, 1 part of rust inhibitor, and 0.5 parts of organic bentonite; wherein the surfactant is polydimethylsiloxane, the coupling agent is silane coupling agent KH550, and the rust inhibitor is iron phosphate.

[0028] A method for preparing an anti-corrosion and anti-rust coating for aluminum alloy is prepared according to the method described in Example 1.

[0029] Comparative Example 2 An anti-corrosion and anti-rust coating for aluminum alloy and a preparation method thereof are prepared according to the method described in Example 1, except that the modified epoxy resin is replaced by epoxy resin.

[0030] Relevant tests were conducted on the anti-corrosion and anti-rust coatings for aluminum alloys prepared in Examples 1-4 and Comparative Examples 1-2. The coating was evenly applied to the surface of the aluminum alloy with a coating thickness of 25 μm, dried at 55°C for 3 hours, and the performance was tested. The heat resistance test was carried out in accordance with GB / T 1735-2009 "Determination of Heat Resistance of Paints and Varnishes", and the test conditions were: placed at 250°C for 120 hours; the adhesion test was carried out in accordance with GB / T 1720-2020 "Paint Film Scratch Test"; the impact resistance test was carried out in accordance with GB / T 1732-2020 "Paint Film Impact Resistance Determination Method", and the test conditions were: 60kg·cm forward and reverse impact; the flame retardancy test was carried out by burning the sample with a flame for 30S and observing the state of the sample; the salt spray resistance test was carried out in accordance with GB / T 10125-2012 "Artificial atmosphere corrosion test - salt spray test" provisions; acid resistance test, the sample is placed in a 10wt% sulfuric acid aqueous solution for 750h, and the surface state of the sample before and after immersion is observed; alkali resistance test, the sample is placed in a 15wt% sodium hydroxide aqueous solution for 750h, and the surface state of the sample before and after immersion is observed; rust resistance test, the sample is placed at a temperature of 50℃ and a humidity of 65% for 50h, and the rust area on the surface of the sample is measured; the above tests are repeated three times to take the average value, and the test results are shown in Table 1. It can be seen from the data in Table 1 that compared with comparative examples 1-2, the anti-corrosion and anti-rust coating for aluminum alloy prepared in Examples 1-4 maintains good rust resistance and adhesion, and also has excellent heat resistance, impact resistance, flame retardancy and chemical corrosion resistance. The anti-corrosion and anti-rust coating for aluminum alloy prepared in Examples 1-4 does not have peeling phenomenon after being placed at 250℃ for 120h, and the surface state of the sample is good under 60kg·cm forward and reverse impact conditions, and no cracking phenomenon occurs. It can be seen from the data of Example 1 and Comparative Example 2 that modifying the epoxy resin and compounding the modified epoxy resin with raw materials such as acrylic resin and nano-silica sol can significantly improve the comprehensive performance of the coating.

[0031] Table 1 Test results of relevant properties of anti-corrosion and anti-rust coatings for aluminum alloy

[0032] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An anticorrosion and antirust coating for aluminum alloy, characterized in that: The invention comprises the following components in parts by weight: 30-40 parts of modified epoxy resin, 20-30 parts of acrylic resin, 7-13 parts of nano silica sol, 0.5-1.5 parts of surfactant, 1-3 parts of coupling agent, 0.2-0.7 parts of rust inhibitor and 0.1-0.5 parts of organic bentonite; the preparation method of the modified epoxy resin is as follows: S1. Under stirring conditions, raise the temperature of 5,6-epoxyhexyltriethoxysilane to 65-75°C, add dibutyl phosphate dropwise, and complete the addition within 0.5-1.5 hours. Then raise the temperature to 75-85°C, continue the reaction for 3.5-4.5 hours, and cool to room temperature to obtain product 1. S2. Disperse 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid in cyclohexane under stirring, raise the temperature to 75-85° C., then sequentially add the product 1 obtained in step S1 and p-toluenesulfonic acid, react under reflux for 5-8 hours, cool to room temperature, and purify to obtain product 2. The structural formula of product 2 is: ； S3. In a nitrogen atmosphere and under stirring conditions, the temperature of the epoxy resin is raised to 60-70°C, and the product 2 obtained in step S2 and dibutyltin dilaurate are added in sequence, and the reaction is carried out for 1-3 hours. The temperature is then raised to 130-150°C, and hydroxy silicone oil is added, and the reaction is continued for 4-6 hours. The reaction is cooled to room temperature to obtain a modified epoxy resin.

2. The anticorrosion and antirust coating for aluminum alloy according to claim 1, characterized in that: The molar ratio of 5,6-epoxyhexyltriethoxysilane to dibutyl phosphate in step S1 is 1:0.7-0.

8.

3. The anticorrosion and antirust coating for aluminum alloy according to claim 1, characterized in that: The molar ratio of 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid, product 1, and p-toluenesulfonic acid in step S2 is 1:0.8-1.0:0.04-0.

05.

4. The anticorrosion and antirust coating for aluminum alloy according to claim 1, characterized in that: The mass volume ratio of cyclohexane to 2-amino-6-fluoro-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid in step S2 is 0.15-0.20 g / mL.

5. The anticorrosion and antirust coating for aluminum alloy according to claim 1, characterized in that: The mass ratio of the epoxy resin, product 2, dibutyltin dilaurate and hydroxy silicone oil in step S3 is 10:0.5-0.7:0.015-0.020:1.3-1.

6.

6. The anticorrosion and antirust coating for aluminum alloy according to claim 1, characterized in that: The surfactant is one or more of polyoxypropylene glyceryl ether, polyoxypropylene oxyethylene glyceryl ether, and polydimethylsiloxane.

7. The anticorrosion and antirust coating for aluminum alloy according to claim 1, characterized in that: The coupling agent is one or more of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570.

8. The anticorrosion and antirust coating for aluminum alloy according to claim 1, characterized in that: The rust inhibitor is iron phosphate or calcium fluorophosphate.

9. The method for preparing the anticorrosion and antirust coating for aluminum alloy according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: uniformly mixing modified epoxy resin and acrylic resin, heating to 40-50°C, adding nano silica sol and organic bentonite in sequence, continuing stirring for 5-10 minutes, then adding coupling agent, surfactant and rust inhibitor in sequence, continuing stirring for 10-20 minutes, and cooling to room temperature to obtain the product.

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