Preparation method of nanometer long-acting anticorrosive coating

Abstract

The application relates to the technical field of paint, in particular to a preparation method of nano long-acting anticorrosive paint, and the specific steps are as follows: modified nano graphene, nano titanium dioxide, modified acrylic resin, 4,4'-diamino diphenyl methane, polyvinylpyrrolidone, polydimethylsiloxane and polypropylene glycol adipate are weighed; the modified nano graphene and the nano titanium dioxide are added into N-methylpyrrolidone, then the polyvinylpyrrolidone is added, and stirring is conducted to obtain nano slurry; the polypropylene glycol adipate is added dropwise into the modified acrylic resin, and stirring is conducted to obtain a mixed resin; the nano slurry is added into the mixed resin, then the polydimethylsiloxane is added dropwise, and stirring is continuously conducted; finally, the 4,4'-diamino diphenyl methane and N-methylpyrrolidone are added, and stirring is conducted to obtain the nano long-acting anticorrosive paint. In the design, the modified nano graphene significantly improves the anti-permeation performance of the coating, makes the structure of the coating more dense, and thus enhances the adhesion of the coating.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically a method for preparing a nano-long-lasting anti-corrosion coating. Background Technology

[0002] In many industrial sectors, such as marine engineering, bridge construction, and chemical equipment, metal components are exposed to harsh environments for extended periods, facing serious corrosion problems. To address this challenge, anti-corrosion coatings effectively block the contact between corrosive media such as water, oxygen, salt spray, and acids and alkalis and the metal substrate through physical shielding, chemical corrosion inhibition, or electrochemical protection mechanisms, thereby achieving long-term protection.

[0003] However, while traditional anti-corrosion coatings can provide some protection, they have significant shortcomings in terms of protection period, adhesion, and durability. For example, the coating is prone to peeling and cracking, and it cannot meet the requirements for long-term and efficient anti-corrosion. In view of this, we propose a method for preparing a nano-long-lasting anti-corrosion coating. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a nano-long-lasting anti-corrosion coating, in order to solve the problems mentioned in the background art that although traditional anti-corrosion coatings can play a certain protective role, they have obvious shortcomings in terms of protection period, adhesion and durability, such as easy peeling and cracking of the coating, and cannot meet the requirements of long-term and efficient anti-corrosion.

[0005] To achieve the above objectives, the present invention provides a method for preparing a nano-long-lasting anti-corrosion coating, comprising the following steps:

[0006] S1.1 Weigh the following raw materials respectively: modified nano-graphene, nano-titanium dioxide, modified acrylic resin, 4,4'-diaminodiphenylmethane, polyvinylpyrrolidone, polydimethylsiloxane and polypropylene adipate.

[0007] S1.2 Add modified nano-graphene and nano-titanium dioxide to N-methylpyrrolidone, add polyvinylpyrrolidone, and stir in a high-speed disperser at a speed of 2000-3000 rpm for 30-60 min to obtain nano slurry;

[0008] S1.3 Add polypropylene adipate dropwise to the modified acrylic resin and stir at 400-600 rpm for 10-15 minutes at 50-60℃ to obtain a mixed resin.

[0009] S1.4 Add the nano slurry to the mixed resin, then add polydimethylsiloxane dropwise, and stir at 800-1200 rpm for 10-20 min; finally add 4,4'-diaminodiphenylmethane and N-methylpyrrolidone, and stir at 300-500 rpm for 5-10 min to obtain a nano long-lasting anti-corrosion coating.

[0010] Preferably, in step S1.1, the following raw materials are weighed in parts by weight: 10-20 parts by weight of modified nano-graphene, 8-15 parts by weight of nano-titanium dioxide, 30-40 parts by weight of modified acrylic resin, 10-15 parts by weight of 4,4'-diaminodiphenylmethane, 3-5 parts by weight of polyvinylpyrrolidone, 2-4 parts by weight of polydimethylsiloxane, and 5-8 parts by weight of polypropylene adipate.

[0011] Preferably, in step S1.2, the modified graphene nanoparticles are prepared by surface modification of graphene nanoparticles with hydrochloric acid-doped aniline tetramers.

[0012] The modified graphene nanoparticles are prepared as follows: Graphene nanoparticles are dispersed in N-methylpyrrolidone, sodium dodecylbenzenesulfonate is added, and the mixture is sonicated at 100-200W for 20-40 minutes to obtain a graphene nanoparticle dispersion.

[0013] Aniline tetramer was dispersed in hydrochloric acid solution and sonicated at 200-300W for 20-30 min, followed by stirring at 300-400 rpm at 35-45℃ for 10-14 h; then the solid was collected by centrifugation at 8000-10000 rpm for 10-15 min and vacuum dried at 50-60℃ for 4-6 h to obtain hydrochloric acid-doped aniline tetramer.

[0014] Hydrochloric acid-doped aniline tetramer was added to a nano-graphene dispersion and refluxed in a water bath at 75-85℃ for 18-30 h under nitrogen protection. After the reaction was completed, the mixture was centrifuged at 8000-10000 rpm for 10-20 min, washed 2-3 times with N-methylpyrrolidone, and then washed 1-2 times with ethanol at 60℃. Finally, the mixture was vacuum dried at 60℃ for 24 h to obtain modified nano-graphene.

[0015] The two-dimensional sheet structure of modified graphene nanoparticles is stacked in parallel in the coating, forming a dense pathway that forces corrosive media such as water, oxygen, and chloride ions to take longer diffusion paths, thus significantly delaying media penetration. After modification with hydrochloric acid-doped aniline tetramers, the amino groups on the graphene surface react with other groups on the acrylic resin backbone, while the phosphate ester groups on the resin form chemical bonds with the hydroxyl groups or oxides on the metal substrate surface, thereby improving the coating-substrate interface bonding. The nanosheets are embedded in the micro-rough surface of the metal substrate, forming a structure similar to nano-anchor chains, which effectively inhibits coating peeling.

[0016] Preferably, the amount of sodium dodecylbenzenesulfonate added is 0.1-0.5% of the mass of the nanographene.

[0017] Preferably, the hydrochloric acid has a mass concentration of 0.3-0.7 mol / L.

[0018] Preferably, the mass ratio of the nanographene to the hydrochloric acid-doped aniline tetramer is 1:0.5-0.7.

[0019] Preferably, in S1.3, the modified acrylic resin is prepared by grafting acrylic resin and hydroxyethyl methacrylate phosphate.

[0020] The modified acrylic resin is prepared as follows: acrylic resin and hydroxyethyl methacrylate phosphate are mixed to obtain a mixture; dibutyltin dilaurate is then added and reacted at 70-80℃ for 1.5-3h; after the reaction is completed, vacuum distillation is carried out at 60℃ and -0.09MPa to obtain the modified acrylic resin.

[0021] By introducing hydroxyethyl methacrylate phosphate groups into the acrylic resin chain, the adhesion between the coating and the metal substrate is significantly enhanced. These phosphate groups can form chemical bonds such as PO-Fe with oxides or hydroxyl groups on the metal surface, thereby improving the bonding strength between the coating and the substrate. In addition, the crosslinking density of the modified resin is increased, forming a denser network structure that effectively blocks the penetration of water, oxygen and corrosive ions, thereby slowing down the corrosion process of the substrate.

[0022] Preferably, the amount of hydroxyethyl methacrylate phosphate added is 8-15% of the mass of the acrylic resin;

[0023] The amount of dibutyltin dilaurate added is 0.05-0.3% of the mass of the mixture.

[0024] Preferably, in step S1.3, the dropping rate of polypropylene adipate is 1.2-1.8 parts by weight / min.

[0025] Preferably, in step S1.4, the dropping rate of polydimethylsiloxane is 0.06-0.08 parts by weight / min.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] In the preparation method of this nano-long-lasting anti-corrosion coating, the modified nano-graphene is stacked in parallel with a two-dimensional sheet structure, forming a maze path in the coating, which effectively delays the penetration and diffusion of corrosive media such as water, oxygen and chloride ions, and significantly improves the coating's anti-permeability performance. At the same time, aniline tetramers are coated on the surface of graphene, which not only consume electrons through oxidation state changes, avoiding the formation of corrosion galvanic cells, but also enhance the compatibility with resins (such as modified acrylic resins) with the polar groups of aniline tetramers, solving the problem of nanomaterial aggregation, making the coating denser and defect-free, thereby significantly improving adhesion. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] First, the synthesis steps of aniline tetramer are as follows: 0.1 mol of aniline is dissolved in 200 mL of 1.0 mol / L hydrochloric acid solution, cooled to 0-5℃ in an ice-water bath, and 50 mL of 0.025 mol of ammonium persulfate aqueous solution is slowly added dropwise (controlling the adding rate: 1 mL / min), and stirring is continued for 4 hours; the pH is adjusted to 10 with sodium hydroxide solution, the precipitate is precipitated and centrifuged (8000 rpm, 10 min); the precipitate is washed with deionized water until neutral, and dried under vacuum (60℃, -0.09 MPa, 24 h) to obtain aniline tetramer.

[0030] Nanographene CAS No.: 1034343-98-0, purchased from Zhejiang Yamei Nanotechnology Co., Ltd.

[0031] Nano titanium dioxide, CAS number: 13463-67-7, purchased from Hubei Rishengchang New Material Technology Co., Ltd.; rutile type, particle size 10-30nm.

[0032] Acrylic resin CAS No.: 9003-01-4; Polydimethylsiloxane CAS No.: 9016-006-6; Purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0033] 4,4'-Diaminodiphenylmethane CAS No.: 101-77-9; Polypropylene adipate CAS No.: 25101-03-5; Purchased from Hubei Chengfeng Chemical Co., Ltd.

[0034] Polyvinylpyrrolidone (CAS No.: 9003-39-8) was purchased from Shanghai Fangye Chemical Co., Ltd.

[0035] Example 1: A method for preparing a nano-long-lasting anti-corrosion coating, comprising the following steps:

[0036] S1.1 Weigh the following raw materials respectively: 10 parts by weight of modified nano-graphene, 8 parts by weight of nano-titanium dioxide, 30 parts by weight of modified acrylic resin, 10 parts by weight of 4,4'-diaminodiphenylmethane, 3 parts by weight of polyvinylpyrrolidone, 2 parts by weight of polydimethylsiloxane and 5 parts by weight of polypropylene adipate.

[0037] S1.2 Add modified nano-graphene and nano-titanium dioxide to N-methylpyrrolidone, add polyvinylpyrrolidone, and stir at 2000 rpm for 60 min in a high-speed disperser to obtain nano slurry;

[0038] S1.3 Add polypropylene adipate dropwise to the modified acrylic resin at a rate of 1.5 parts by weight / min, and stir at 500 rpm for 15 min at 60°C to obtain a mixed resin.

[0039] S1.4 Add the nano slurry to the mixed resin, then add polydimethylsiloxane dropwise at a rate of 0.07 parts by weight / min, and stir at 1000 rpm for 20 min; finally add 4,4'-diaminodiphenylmethane and N-methylpyrrolidone, and stir at 400 rpm for 10 min to obtain a nano long-lasting anti-corrosion coating.

[0040] Furthermore, the preparation method of modified nano-graphene is as follows: nano-graphene is dispersed in N-methylpyrrolidone, sodium dodecylbenzenesulfonate of 0.3% by mass of nano-graphene is added, and ultrasonication is performed at 200W for 30 minutes to obtain nano-graphene dispersion.

[0041] Aniline tetramer was dispersed in a 0.3 mol / L hydrochloric acid solution and sonicated at 200 W for 30 min. Then, it was stirred at 300 rpm at 40 °C for 12 h. The solid was then collected by centrifugation at 8000 rpm for 15 min and dried under vacuum at 60 °C for 6 h to obtain hydrochloric acid-doped aniline tetramer.

[0042] Hydrochloric acid-doped aniline tetramer was added to a nano-graphene dispersion (mass ratio 1:0.5), and the reaction was carried out under nitrogen protection and refluxed in a water bath at 80°C for 24 h. After the reaction was completed, the nano-graphene was centrifuged at 8000 rpm for 20 min, washed three times with N-methylpyrrolidone, and then washed twice with ethanol at 60°C. Finally, the nano-graphene was vacuum dried at 60°C for 24 h to obtain the modified nano-graphene.

[0043] The modified acrylic resin is prepared as follows: Acrylic resin and hydroxyethyl methacrylate phosphate (8% of the mass of acrylic resin) are mixed to obtain a mixture; then 0.1% of dibutyltin dilaurate is added to the mixture, and the mixture is reacted at 70℃ for 3 hours; after the reaction is completed, vacuum distillation is carried out at 60℃ and -0.09MPa to obtain the modified acrylic resin.

[0044] Example 2: A method for preparing a nano-long-lasting anti-corrosion coating, comprising the following steps:

[0045] S1.1 Weigh the following raw materials respectively: 15 parts by weight of modified nano-graphene, 12 parts by weight of nano-titanium dioxide, 35 parts by weight of modified acrylic resin, 12 parts by weight of 4,4'-diaminodiphenylmethane, 4 parts by weight of polyvinylpyrrolidone, 3 parts by weight of polydimethylsiloxane and 6 parts by weight of polypropylene adipate.

[0046] S1.2 Add modified nano-graphene and nano-titanium dioxide to N-methylpyrrolidone, add polyvinylpyrrolidone, and stir at 2000 rpm for 60 min in a high-speed disperser to obtain nano slurry;

[0047] S1.3 Add polypropylene adipate dropwise to the modified acrylic resin at a rate of 1.5 parts by weight / min, and stir at 500 rpm for 15 min at 60°C to obtain a mixed resin.

[0048] S1.4 Add the nano slurry to the mixed resin, then add polydimethylsiloxane dropwise at a rate of 0.07 parts by weight / min, and stir at 1000 rpm for 20 min; finally add 4,4'-diaminodiphenylmethane and N-methylpyrrolidone, and stir at 400 rpm for 10 min to obtain a nano long-lasting anti-corrosion coating.

[0049] Furthermore, the preparation method of modified nano-graphene is as follows: nano-graphene is dispersed in N-methylpyrrolidone, sodium dodecylbenzenesulfonate of 0.3% by mass of nano-graphene is added, and ultrasonication is performed at 200W for 30 minutes to obtain nano-graphene dispersion.

[0050] Aniline tetramer was dispersed in a hydrochloric acid solution with a mass concentration of 0.5 mol / L, sonicated at 200 W for 30 min, and then stirred at 300 rpm for 12 h at 40 °C. The solid was then collected by centrifugation at 8000 rpm for 15 min and dried under vacuum at 60 °C for 6 h to obtain hydrochloric acid-doped aniline tetramer.

[0051] Hydrochloric acid-doped aniline tetramer was added to a nano-graphene dispersion (mass ratio 1:0.6), and the reaction was carried out under nitrogen protection and refluxed in a water bath at 80°C for 24 h. After the reaction was completed, the nano-graphene was centrifuged at 8000 rpm for 20 min, washed three times with N-methylpyrrolidone, and then washed twice with ethanol at 60°C. Finally, the nano-graphene was vacuum dried at 60°C for 24 h to obtain the modified nano-graphene.

[0052] The modified acrylic resin is prepared as follows: acrylic resin and hydroxyethyl methacrylate phosphate (12% of the mass of acrylic resin) are mixed to obtain a mixture; then 0.1% of dibutyltin dilaurate is added to the mixture and reacted at 70℃ for 3 hours; after the reaction is completed, vacuum distillation is carried out at 60℃ and -0.09MPa to obtain the modified acrylic resin.

[0053] Example 3: A method for preparing a nano-long-lasting anti-corrosion coating, comprising the following steps:

[0054] S1.1 Weigh the following raw materials respectively: 20 parts by weight of modified nano-graphene, 15 parts by weight of nano-titanium dioxide, 40 parts by weight of modified acrylic resin, 15 parts by weight of 4,4'-diaminodiphenylmethane, 5 parts by weight of polyvinylpyrrolidone, 4 parts by weight of polydimethylsiloxane and 8 parts by weight of polypropylene adipate.

[0055] S1.2 Add modified nano-graphene and nano-titanium dioxide to N-methylpyrrolidone, add polyvinylpyrrolidone, and stir at 2000 rpm for 60 min in a high-speed disperser to obtain nano slurry;

[0056] S1.3 Add polypropylene adipate dropwise to the modified acrylic resin at a rate of 1.5 parts by weight / min, and stir at 500 rpm for 15 min at 60°C to obtain a mixed resin.

[0057] S1.4 Add the nano slurry to the mixed resin, then add polydimethylsiloxane dropwise at a rate of 0.07 parts by weight / min, and stir at 1000 rpm for 20 min; finally add 4,4'-diaminodiphenylmethane and N-methylpyrrolidone, and stir at 400 rpm for 10 min to obtain a nano long-lasting anti-corrosion coating.

[0058] Furthermore, the preparation method of modified nano-graphene is as follows: nano-graphene is dispersed in N-methylpyrrolidone, sodium dodecylbenzenesulfonate of 0.3% by mass of nano-graphene is added, and ultrasonication is performed at 200W for 30 minutes to obtain nano-graphene dispersion.

[0059] Aniline tetramer was dispersed in a 0.7 mol / L hydrochloric acid solution and sonicated at 200 W for 30 min. Then, it was stirred at 300 rpm at 40 °C for 12 h. The solid was collected by centrifugation at 8000 rpm for 15 min and dried under vacuum at 60 °C for 6 h to obtain hydrochloric acid-doped aniline tetramer.

[0060] Hydrochloric acid-doped aniline tetramer was added to a nano-graphene dispersion (mass ratio 1:0.7), and the reaction was carried out under nitrogen protection and refluxed in a water bath at 80°C for 24 h. After the reaction was completed, the nano-graphene was centrifuged at 8000 rpm for 20 min, washed three times with N-methylpyrrolidone, and then washed twice with ethanol at 60°C. Finally, the nano-graphene was vacuum dried at 60°C for 24 h to obtain the modified nano-graphene.

[0061] The modified acrylic resin is prepared as follows: acrylic resin and hydroxyethyl methacrylate phosphate (15% of the mass of acrylic resin) are mixed to obtain a mixture; then 0.1% of dibutyltin dilaurate is added to the mixture and reacted at 70℃ for 3 hours; after the reaction is completed, vacuum distillation is carried out at 60℃ and -0.09MPa to obtain the modified acrylic resin.

[0062] Example 4: A method for preparing a nano-long-lasting anti-corrosion coating, comprising the following steps:

[0063] S1.1 Weigh the following raw materials respectively: 20 parts by weight of modified nano-graphene, 12 parts by weight of nano-titanium dioxide, 35 parts by weight of modified acrylic resin, 12 parts by weight of 4,4'-diaminodiphenylmethane, 4 parts by weight of polyvinylpyrrolidone, 3 parts by weight of polydimethylsiloxane and 6 parts by weight of polypropylene adipate.

[0064] S1.2 Add modified nano-graphene and nano-titanium dioxide to N-methylpyrrolidone, add polyvinylpyrrolidone, and stir at 2000 rpm for 60 min in a high-speed disperser to obtain nano slurry;

[0065] S1.3 Add polypropylene adipate dropwise to the modified acrylic resin at a rate of 1.5 parts by weight / min, and stir at 500 rpm for 15 min at 60°C to obtain a mixed resin.

[0066] S1.4 Add the nano slurry to the mixed resin, then add polydimethylsiloxane dropwise at a rate of 0.07 parts by weight / min, and stir at 1000 rpm for 20 min; finally add 4,4'-diaminodiphenylmethane and N-methylpyrrolidone, and stir at 400 rpm for 10 min to obtain a nano long-lasting anti-corrosion coating.

[0067] Furthermore, the preparation method of modified nano-graphene is as follows: nano-graphene is dispersed in N-methylpyrrolidone, sodium dodecylbenzenesulfonate of 0.3% by mass of nano-graphene is added, and ultrasonication is performed at 200W for 30 minutes to obtain nano-graphene dispersion.

[0068] Aniline tetramer was dispersed in a 0.5 mol / L hydrochloric acid solution and sonicated at 200 W for 30 min. Then, it was stirred at 300 rpm at 40 °C for 12 h. The solid was collected by centrifugation at 8000 rpm for 15 min and dried under vacuum at 60 °C for 6 h to obtain hydrochloric acid-doped aniline tetramer.

[0069] Hydrochloric acid-doped aniline tetramer was added to a nano-graphene dispersion (mass ratio 1:0.6), and the reaction was carried out under nitrogen protection and refluxed in a water bath at 80°C for 24 h. After the reaction was completed, the nano-graphene was centrifuged at 8000 rpm for 20 min, washed three times with N-methylpyrrolidone, and then washed twice with ethanol at 60°C. Finally, the nano-graphene was vacuum dried at 60°C for 24 h to obtain the modified nano-graphene.

[0070] The modified acrylic resin is prepared as follows: acrylic resin and hydroxyethyl methacrylate phosphate (12% of the mass of acrylic resin) are mixed to obtain a mixture; then 0.1% of dibutyltin dilaurate is added to the mixture and reacted at 70℃ for 3 hours; after the reaction is completed, vacuum distillation is carried out at 60℃ and -0.09MPa to obtain the modified acrylic resin.

[0071] Example 5: A method for preparing a nano-long-lasting anti-corrosion coating, comprising the following steps:

[0072] S1.1 Weigh the following raw materials respectively: 25 parts by weight of modified nano-graphene, 12 parts by weight of nano-titanium dioxide, 35 parts by weight of modified acrylic resin, 12 parts by weight of 4,4'-diaminodiphenylmethane, 4 parts by weight of polyvinylpyrrolidone, 3 parts by weight of polydimethylsiloxane and 6 parts by weight of polypropylene adipate.

[0073] S1.2 Add modified nano-graphene and nano-titanium dioxide to N-methylpyrrolidone, add polyvinylpyrrolidone, and stir at 2000 rpm for 60 min in a high-speed disperser to obtain nano slurry;

[0074] S1.3 Add polypropylene adipate dropwise to the modified acrylic resin at a rate of 1.5 parts by weight / min, and stir at 500 rpm for 15 min at 60°C to obtain a mixed resin.

[0075] S1.4 Add the nano slurry to the mixed resin, then add polydimethylsiloxane dropwise at a rate of 0.07 parts by weight / min, and stir at 1000 rpm for 20 min; finally add 4,4'-diaminodiphenylmethane and N-methylpyrrolidone, and stir at 400 rpm for 10 min to obtain a nano long-lasting anti-corrosion coating.

[0076] Furthermore, the preparation method of modified nano-graphene is as follows: nano-graphene is dispersed in N-methylpyrrolidone, sodium dodecylbenzenesulfonate of 0.3% by mass of nano-graphene is added, and ultrasonication is performed at 200W for 30 minutes to obtain nano-graphene dispersion.

[0077] Aniline tetramer was dispersed in a 0.5 mol / L hydrochloric acid solution and sonicated at 200 W for 30 min. Then, it was stirred at 300 rpm at 40 °C for 12 h. The solid was collected by centrifugation at 8000 rpm for 15 min and dried under vacuum at 60 °C for 6 h to obtain hydrochloric acid-doped aniline tetramer.

[0078] Hydrochloric acid-doped aniline tetramer was added to a nano-graphene dispersion (mass ratio 1:0.6), and the reaction was carried out under nitrogen protection and refluxed in a water bath at 80°C for 24 h. After the reaction was completed, the nano-graphene was centrifuged at 8000 rpm for 20 min, washed three times with N-methylpyrrolidone, and then washed twice with ethanol at 60°C. Finally, the nano-graphene was vacuum dried at 60°C for 24 h to obtain the modified nano-graphene.

[0079] The modified acrylic resin is prepared as follows: acrylic resin and hydroxyethyl methacrylate phosphate (12% of the mass of acrylic resin) are mixed to obtain a mixture; then 0.1% of dibutyltin dilaurate is added to the mixture and reacted at 70℃ for 3 hours; after the reaction is completed, vacuum distillation is carried out at 60℃ and -0.09MPa to obtain the modified acrylic resin.

[0080] Comparative Example 1: Using the method of Example 2, in the preparation method of a nano-long-lasting anti-corrosion coating, no modified nano-graphene was used, and nano-graphene was used directly.

[0081] Comparative Example 2: Using the method of Example 2, in the preparation method of modified graphene nanoparticles, hydrochloric acid-doped aniline tetramers were not used, and aniline tetramers were directly used to modify the surface of graphene nanoparticles.

[0082] Comparative Example 3: Using the method of Example 2, in the preparation method of a nano long-lasting anti-corrosion coating, no modified acrylic resin was used, and acrylic resin was used directly.

[0083] This invention relates to a method for preparing a nano-long-lasting anti-corrosion coating by adding modified nano-graphene. The performance indicators and testing standards for the prepared nano-long-lasting anti-corrosion coating are as follows:

[0084] The metal substrate was sandblasted to Sa2.5 grade to ensure surface cleanliness met anti-corrosion requirements. A nano-long-lasting anti-corrosion coating was then sprayed to a dry film thickness of 80±5μm and cured at room temperature for 7 days. Two intersecting lines, each at least 50mm long, were drawn on the coating surface using a single-edged cutting tool with a 30° angle. The scratches must completely penetrate the coating to the substrate and maintain a distance of at least 20mm from the edge of the sample. The sample was then placed in a salt spray test chamber for salt spray exposure. The chamber temperature was set at 35±1℃, and the salt spray deposition rate was controlled at 1.5±0.5mL / (h·80cm). 2 The sample should be tilted at 15±5° to the vertical plane to prevent droplet accumulation. After the salt spray test, the maximum single-sided corrosion width of the scratch edge should be measured to evaluate the corrosion resistance of the coating.

[0085] The metal substrate was sandblasted to Sa2.5 grade, followed by spraying with a nano long-lasting anti-corrosion coating. The dry film thickness was controlled at 100±10μm and cured at 25℃ for 7 days. The coating surface was lightly sanded with P220 sandpaper, cleaned with acetone, and then the adhesive was evenly applied to the end face. It was then pressed vertically onto the coating surface using a hydraulic adhesion tester and cured at 25℃ for 24 hours. During the test, the coating was pulled apart at a rate of 1.0±0.1MPa / s, and the adhesion was recorded to evaluate the bonding strength between the coating and the substrate.

[0086] The nano-long-lasting anti-corrosion coatings prepared in Examples 1-5 and Comparative Examples 1-3 were tested according to the above standards, and the data obtained are shown in Table 1:

[0087] Table 1 Test data of Examples 1-5 and Comparative Examples 1-3

[0088]

[0089] As can be seen from Examples 2 and 4-5: when other components in the nano-long-lasting anti-corrosion coating remain unchanged, the salt spray corrosion width of the nano-long-lasting anti-corrosion coating continuously increases and the adhesion continuously decreases when the weight of modified nano-graphene increases; when an appropriate amount of modified nano-graphene forms a layered labyrinth structure in the coating, it forces corrosive media such as water, oxygen, and chloride ions to take longer diffusion paths, significantly delaying penetration; at this time, the corrosion width narrows and the salt spray tolerance is improved; after modification with hydrochloric acid-doped aniline tetramer, the conductivity of graphene is suppressed, avoiding the formation of electrochemical corrosion channels and reducing local corrosion diffusion; however, excessive addition of graphene (Example 5) will cause the graphene sheets to stack and agglomerate, forming micropores and stress concentration points in the coating, and the corrosive media will rapidly penetrate along the edges of the agglomerates, expanding the corrosion width.

[0090] An appropriate amount of graphene forms chemical bonds with the resin through surface-active groups (such as residual oxygen-containing groups) and fills the resin micropores, thereby improving the mechanical interlocking force between the coating and the substrate. The nanosheets are uniformly dispersed and act as a "skeleton" to support the polymer network, enhancing the cohesive strength of the coating. However, excessive graphene (Example 4) easily forms rigid agglomerates in the resin, leading to local stress concentration in the coating, which is easily peeled off from the agglomeration interface when subjected to external force. In addition, when the proportion of graphene is too high, the film-forming continuity of the resin is destroyed, weakening the wettability and adhesion of the matrix to the substrate.

[0091] Based on the above test experiments, Example 2 is considered the optimal example.

[0092] A comparison of Example 2 and Comparative Example 1 shows that when no modified graphene was used and graphene was used directly, the salt spray corrosion width of the nano long-lasting anti-corrosion coating increased significantly and the adhesion decreased significantly.

[0093] Due to the presence of numerous van der Waals forces on its surface, virgin graphene nanoparticles are prone to aggregation, forming micron-sized particles. This creates pores and cracks in the coating, allowing corrosive media to penetrate more easily into the metal substrate and significantly increasing the corrosion width. Furthermore, virgin graphene exhibits high conductivity, acting as a cathode to form a microcouple with the metal substrate, accelerating the anodic dissolution of the metal. In contrast, modified graphene reduces conductivity, blocking the corrosion current path. Simultaneously, its layered structure creates a labyrinth effect in the coating, extending the diffusion path of the corrosive media and effectively inhibiting corrosion. Moreover, the poor interfacial bonding between unmodified graphene and the resin matrix (such as epoxy resin) leads to stress concentration within the coating, reducing adhesion.

[0094] A comparison of Example 2 and Comparative Example 2 shows that when aniline tetramer is directly modified with aniline tetramer without hydrochloric acid doping, the salt spray corrosion width of the nano-long-lasting anti-corrosion coating increases significantly. Hydrochloric acid doping puts the aniline tetramer in a conductive state, giving it redox activity, which can induce the formation of a dense passivation film on the metal surface, thereby effectively blocking corrosion propagation. In contrast, the undoped aniline tetramer is in an insulating state, losing its passivation ability, leading to direct erosion of the substrate by the corrosive medium, and thus expanding the salt spray corrosion width. In addition, hydrochloric acid doping can also improve the interfacial bonding strength between aniline tetramer and graphene, forming a denser physical barrier layer. In the undoped state, the interfacial bonding between the two is weak, and the coating is prone to microcracks, accelerating the penetration of the corrosive medium.

[0095] A comparison of Example 2 and Comparative Example 3 shows that when acrylic resin is used directly without modification, the salt spray corrosion width of the nano-long-lasting anti-corrosion coating increases significantly and the adhesion decreases significantly. Modified acrylic resin significantly improves the compatibility with nanofillers by introducing active groups (such as phosphate groups). Without modification, the acrylic resin has low polarity, making it difficult to effectively disperse nanoparticles, leading to filler agglomeration, decreased coating density, and easier penetration of corrosive media into the substrate through coating defects, accelerating corrosion diffusion. In addition, the interfacial bonding between the unmodified resin and the nanofillers is weak, and stress concentration is easily generated inside the coating, accelerating delamination.

[0096] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a nano-long-lasting anti-corrosion coating, characterized in that, Includes the following steps: S1.1 Weigh the following raw materials in parts by weight: 10-20 parts by weight of modified nano-graphene, 8-15 parts by weight of nano-titanium dioxide, 30-40 parts by weight of modified acrylic resin, 10-15 parts by weight of 4,4'-diaminodiphenylmethane, 3-5 parts by weight of polyvinylpyrrolidone, 2-4 parts by weight of polydimethylsiloxane, and 5-8 parts by weight of polypropylene adipate. S1.2 Add modified nano-graphene and nano-titanium dioxide to N-methylpyrrolidone, add polyvinylpyrrolidone, and stir in a high-speed disperser at a speed of 2000-3000 rpm for 30-60 min to obtain nano slurry; S1.3 Add polypropylene adipate dropwise to the modified acrylic resin and stir at 400-600 rpm for 10-15 minutes at 50-60℃ to obtain a mixed resin. S1.4 Add the nano slurry to the mixed resin, then add polydimethylsiloxane dropwise, and stir at 800-1200 rpm for 10-20 min; finally add 4,4'-diaminodiphenylmethane and N-methylpyrrolidone, and stir at 300-500 rpm for 5-10 min to obtain a nano long-lasting anti-corrosion coating. In step S1.2, the modified graphene nanoparticles are prepared by surface modification of graphene nanoparticles with hydrochloric acid-doped aniline tetramers. The preparation method of the modified graphene nanoparticles is as follows: Graphene nanoparticles are dispersed in N-methylpyrrolidone, sodium dodecylbenzenesulfonate is added, and the mixture is ultrasonicated at 100-200W for 20-40 min to obtain a graphene nanoparticle dispersion; aniline tetramers are dispersed in hydrochloric acid solution, ultrasonicated at 200-300W for 20-30 min, and then stirred at 300-400 rpm for 10-14 h at 35-45℃; then stirred at 8... The solid was collected by centrifugation at 000-10000 rpm for 10-15 min and dried under vacuum at 50-60℃ for 4-6 h to obtain hydrochloric acid-doped aniline tetramer. The hydrochloric acid-doped aniline tetramer was added to a nano-graphene dispersion and refluxed in a water bath at 75-85℃ under nitrogen protection for 18-30 h. After the reaction was completed, the mixture was centrifuged at 8000-10000 rpm for 10-20 min, washed 2-3 times with N-methylpyrrolidone, and then washed 1-2 times with ethanol at 60℃. Finally, it was dried under vacuum at 60℃ for 24 h to obtain modified nano-graphene. In S1.3, the modified acrylic resin is prepared by grafting acrylic resin and hydroxyethyl methacrylate phosphate. The preparation method of the modified acrylic resin is as follows: acrylic resin and hydroxyethyl methacrylate phosphate are mixed to obtain a mixture; dibutyltin dilaurate is added and reacted at 70-80℃ for 1.5-3h; after the reaction is completed, vacuum distillation is carried out at 60℃ and -0.09MPa to obtain the modified acrylic resin.

2. The method for preparing the nano-long-lasting anti-corrosion coating according to claim 1, characterized in that, The amount of sodium dodecylbenzenesulfonate added is 0.1-0.5% of the mass of the nanographene.

3. The method for preparing the nano-long-lasting anti-corrosion coating according to claim 1, characterized in that, The mass concentration of the hydrochloric acid is 0.3-0.7 mol / L.

4. The method for preparing the nano-long-lasting anti-corrosion coating according to claim 1, characterized in that, The mass ratio of the nano-graphene to the hydrochloric acid-doped aniline tetramer is 1:0.5-0.

7.

5. The method for preparing the nano-long-lasting anti-corrosion coating according to claim 1, characterized in that, The amount of hydroxyethyl methacrylate phosphate added is 8-15% of the mass of acrylic resin; the amount of dibutyltin dilaurate added is 0.05-0.3% of the mass of the mixture.

6. The method for preparing the nano-long-lasting anti-corrosion coating according to claim 1, characterized in that, In step S1.3, the dropping rate of polypropylene adipate is 1.2-1.8 parts by weight / min.

7. The method for preparing the nano-long-lasting anti-corrosion coating according to claim 1, characterized in that, In step S1.4, the dropping rate of polydimethylsiloxane is 0.06-0.08 parts by weight / min.

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