Water-based on-rust coating for steel structure and preparation method of water-based on-rust coating

Abstract

The invention relates to the technical field of coatings, in particular to a water-based on-rust coating for a steel structure and a preparation method thereof.The water-based on-rust coating is prepared from, by weight, 40-50 parts of a base material, 10-15 parts of anti-rust pigment, 12-16 parts of a transforming agent, 2-5 parts of a penetrant, 0.1-0.5 part of a corrosion inhibitor, 0.1-2 parts of auxiliaries and 25-35 parts of water; the base material is composed of waterborne polyester resin, polyvinyl butyral resin aqueous emulsion and styrene-acrylic emulsion according to the weight ratio of (1-2): 1: (2-3); the anti-rust pigment is prepared from talcum powder, zinc phosphate, aluminum hydroxide and zinc chrome yellow; the transforming agent is composed of polyphosphoric acid, silica sol and citric acid; the penetrating agent comprises at least one of sodium dodecyl benzene sulfonate and polyoxyethylene alkylphenol ether. Through matching and combination of all the raw materials, the prepared coating is not prone to corroding the steel surface and can permeate into a rust layer of a steel structure and react with active ingredients in the rust layer to form a stable coating film, the interior of the rust layer and the surface of the steel structure are sealed, and the anti-rust performance and the mechanical strength are improved.

Description

Technical Field

[0001] This application relates to the technical field of coatings, and particularly relates to an aqueous rust-inhibiting paint for steel structures and a preparation method thereof. Background Art

[0002] Steel structure materials are important materials indispensable in various fields. To reduce the corrosion of steel structure materials, painting is a commonly used method. To reduce the peeling of the coating, the metal surface needs to be pretreated before painting. The cost of surface pretreatment of the steel structure surface before painting can account for about 45% of the total price of the entire painting project. If the surface treatment processes such as rust removal, degreasing, and water removal can be reduced or saved, the painting cost can be significantly reduced; at the same time, the painting process can be greatly simplified, thereby reducing the labor intensity and the harm of rust dust to the human body. Using rust-inhibiting paint to stably transform the rusted steel surface is an economical and convenient surface treatment technology.

[0003] Rust-inhibiting paint is a special type of paint that can be directly applied to the metal surface with residual rust, react with the rust substance, convert harmful substances into beneficial substances, and play a role in protecting the metal against corrosion.

[0004] Aqueous rust-inhibiting paint is favored by more people due to its environmental friendliness and has begun to be widely developed and used. Aqueous conversion-type rust-inhibiting paint can react with rust and form inert substances, and then convert them into chelates or complexes with certain protective effects on the substrate, so as to achieve the purpose of sealing the rust layer and isolating it from the outside. However, since the aqueous conversion-type rust-inhibiting paint contains inorganic acids and organic acids, its own acidity will damage the subsequent matching topcoat. It will not only cause the topcoat to become brittle, but also cause the topcoat to crack. In addition, the aqueous conversion-type rust-inhibiting paint is also likely to corrode the surface of the steel structure. Therefore, there is an urgent need in the industry for an aqueous rust-inhibiting paint that is more stable and not easily damaged to the steel structure and the topcoat. Summary of the Invention

[0005] This application aims to at least overcome one of the defects of the prior art, and provides an aqueous rust-inhibiting paint for steel structures and a preparation method thereof. Through the combination of various raw materials, the prepared paint is not easily corroded on the steel surface, can also penetrate into the rust layer inside the steel structure, react with the active components in the rust layer, form a stable coating film, seal the inside of the rust layer and the surface of the steel structure, and improve the rust prevention performance and mechanical strength.

[0006] In the first aspect, an embodiment of this application provides an aqueous rust-inhibiting paint for steel structures, which is realized through the following technical solutions:

[0007] An aqueous rust-inhibiting paint for steel structures, comprising the following raw materials for preparation in parts by weight:

[0008] 40 - 50 parts of base material, 10 - 15 parts of anti-rust pigment, 12 - 16 parts of conversion agent, 2 - 5 parts of penetrant, 0.1 - 0.5 parts of corrosion inhibitor, 0.1 - 2 parts of auxiliary agent, 25 - 35 parts of water;

[0009] The base material is composed of aqueous polyester resin, polyvinyl butyral resin aqueous emulsion and styrene-acrylic emulsion according to the weight ratio of (1 - 2):1:(2 - 3);

[0010] The anti-rust pigment is composed of talc powder, zinc phosphate, aluminum hydroxide, and zinc chromate yellow;

[0011] The conversion agent is composed of polyphosphoric acid, silica sol, and citric acid;

[0012] The penetrant includes at least one of sodium dodecylbenzenesulfonate and polyoxyethylene alkylphenol ether.

[0013] The waterborne rust-inhibiting paint for steel structures according to the embodiments of the present application has at least the following beneficial effects:

[0014] In the paint of the present application, the base material is combined with aqueous polyester resin, polyvinyl butyral resin aqueous emulsion and styrene-acrylic emulsion. These resins have good permeability, which can make the paint components fully penetrate into the rust layer inside the steel structure. The polyhydroxy, carboxyl and other groups present in the resin can chelate with the soluble iron ions in the rust layer, consume the active components of rust, and perform rust-inhibiting coating.

[0015] The polyvinyl butyral resin aqueous emulsion of the present application can enhance the adhesion on the surface of the steel structure, is not easy to fall off, and improves the anti-corrosion performance of the paint. The polyvinyl butyral resin has a relatively high glass transition temperature, which enhances the heat resistance and weather resistance of the paint. The polyvinyl butyral resin aqueous emulsion can also improve the fluidity and leveling property of the paint, making the paint easier to be evenly applied during construction, reducing the generation of bubbles and pinholes, and improving the quick-drying property of the paint; the polyvinyl butyral resin can form a dense protective film in the paint, isolating the direct contact between the metal and oxygen and moisture, thus playing an anti-rust role, and synergistically acting with the anti-rust pigment, which can further improve the anti-rust performance of the paint.

[0016] The styrene-acrylic emulsion of the present application introduces styrene segments, which can improve the water resistance and alkali resistance of the coating film. This is particularly important for rust-inhibiting paints used in humid environments. At the same time, it can also enhance the adhesion and film-forming property of the paint, and can form a uniform and dense protective film on the metal surface, effectively isolating the direct contact between the metal and oxygen and moisture, playing an anti-rust role; the styrene-acrylic emulsion also has good fluidity and leveling property, which is convenient for construction, reduces the generation of bubbles and pinholes, and its quick-drying property also helps to shorten the drying time of the paint and improve work efficiency.

[0017] The water-based polyester resin of the present application has good adhesion properties and can form a strong bond with a variety of substrates. In rust-containing paint, the water-based polyester resin can penetrate into the rust gaps and seal active substances such as rust in the inert resin, thereby preventing the expansion and continued generation of rust, while enhancing the adhesion between the paint and the substrate. The water-based polyester resin has high chemical stability and mechanical strength, and can improve the weather resistance and wear resistance of the paint.

[0018] The anti-rust pigment of the present application has strong reducing property and can reduce rust to a stable alkaline iron structure, passivate the rust layer, make it inactive, and inhibit the expansion of rust. The main component of talcum powder is magnesium silicate, and its flaky structure prolongs the diffusion path of the corrosive medium, which can reduce the crack sensitivity of the coating, improve the overall performance and weather resistance of the paint film, and also improve the bonding with the substrate. It can also increase the viscosity of the coating and make it thixotropic, reducing the sedimentation tendency of the pigment; zinc phosphate can dissociate and hydrolyze to generate phosphate ions, which are on the metal surface and Fe 3+ The formation of a firmly attached complex precipitation layer inhibits the polarization of the anode, and the zinc ions react with the OH - It reacts to generate zinc hydroxide or basic zinc salt with low solubility, which plays a cathodic polarization role. At the same time, it can complex with the hydroxyl and carboxyl groups in the base material to form a chemical bond between the pigment, base material and substrate, thereby improving the adhesion and impermeability of the coating and playing a role in rust prevention; aluminum hydroxide can provide aluminum ions, react with rust to dissolve the rust, and combine the iron ions with the phosphate ions provided by zinc phosphate to form a strong and stable phosphating film, thereby stabilizing the rust and playing a corrosion-resistant and passivating role on the rust layer; zinc chrome yellow can improve the adhesion of the paint film to the substrate, has good weather resistance, and can form a protective layer on the metal surface, which has an anodic protection and passivation effect.

[0019] The conversion agent of the present application is composed of polyphosphoric acid, silica sol, and citric acid. When combined with each other, it can improve the comprehensive performance of the coating. Polyphosphoric acid has strong chemical activity and can combine with ferric ions to form a protective film, which helps to enhance the rust prevention performance of the coating. In the coating, polyphosphate ions can also undergo a depolymerization reaction to generate various ions such as pyrophosphate ions to orthophosphate ions. These ions can further form a tough passivation film on the metal surface. This passivation film can effectively isolate the corrosive medium, thereby improving the anti-corrosion performance of the coating; the silanol groups in the silica sol can undergo chemical reactions with hydroxyl groups, carboxyl groups, etc. in the coating to form chemical bonding, enhancing the bonding force between the coating and the steel structure surface, making the coating more firmly attached to the metal surface and not easily peeling off or falling off. Silica sol also has good suspension and dispersion properties, which can effectively prevent the precipitation of pigments and additives in the coating, and at the same time improve the weather resistance, hardness, and wear resistance of the coating; citric acid can react with ferric ions in rust to form a stable chelate, thereby converting rust, which helps to convert harmful rust into harmless or less harmful substances, reducing the damage of rust to the coating. At the same time, citric acid interacts with the metal surface and other components in the coating to form chemical bonds or physical adsorption, improving the adhesion of the coating; citric acid can also improve the dispersibility, wettability, and leveling property of the coating, making the coating easier to apply and level.

[0020] The penetrant of the present application is combined with the resin in the base material, which can further reduce the surface tension between the coating and the rust layer, making it easier for the coating to penetrate into the micropores and cracks of the rust layer, helping the coating to tightly combine with the rust layer to form a dense protective film, thereby improving the anti-corrosion performance of the coating.

[0021] According to some embodiments of the present application, the preparation of the aqueous polyester resin includes the following steps: Mix 5 - 10 parts by weight of maleic anhydride, 20 - 25 parts by weight of 1,4-butanediol, 1 - 5 parts by weight of pentaerythritol, 5 - 10 parts by weight of glutaric acid, 10 - 20 parts by weight of terephthalic acid, and 0.01 - 0.05 parts by weight of defoamer, and then heat up to 140 - 170 °C for reaction. When the temperature is raised to 210 - 240 °C, add 1 - 5 parts by weight of acetone. The pH value of the whole reaction system is 2 - 6, and acetone is recovered under reduced pressure to -0.09 MPa; when the temperature is lowered to 170 - 180 °C, add 1 - 5 parts by weight of phenylsuccinic anhydride and keep warm. When the temperature is lowered to 140 - 160 °C, add 5 - 10 parts by weight of diethylene glycol monomethyl ether and stir. Mix 40 - 60 parts by weight of water and 0.5 - 1 part by weight of diethanolamine and add them to the mixture with stirring to obtain the aqueous polyester resin.

[0022] According to some embodiments of the present application, the preparation of the polyvinyl butyral resin aqueous emulsion includes the following steps:

[0023] S1. Slowly add polyvinyl butyral resin into the isopropanol-water mixture, stir at 60 °C for 1 - 2 hours until completely dissolved to form a transparent polyvinyl butyral resin glue solution;

[0024] S2. Mix the emulsifier and deionized water according to the weight ratio of (4 - 5):(5 - 6), heat to 50 °C, and stir until completely dissolved to obtain an emulsifier aqueous phase;

[0025] S3. Slowly drop 40 - 50 parts by weight of the transparent polyvinyl butyral resin glue solution into 50 - 60 parts by weight of the emulsifier aqueous phase, and shear at a speed of 3000 - 6000 rpm / min for 20 - 30 min;

[0026] S4. Evaporate isopropanol at a temperature of 50 - 60 °C and a vacuum degree of -0.08 MPa, add 2 - 3 parts of tributyl acetyl citrate, stir for 30 - 35 min, adjust the pH to 8 - 9 with ammonia water, and filter through a 200 - mesh sieve to obtain a polyvinyl butyral resin aqueous emulsion.

[0027] The temperature in step S4 is 50 - 60 °C. If the temperature is too high, the solvent will volatilize too fast; if the temperature is too low, the dispersion effect will be affected. A pH of 8 - 9 can enhance the storage stability of the polyvinyl butyral resin aqueous emulsion; filtration can remove undispersed particles.

[0028] Furthermore, the molecular weight of the polyvinyl butyral resin described in step S1 is 20000 - 40000, and the degree of acetalization is 70 - 80%. Selecting a polyvinyl butyral resin with low viscosity and moderate degree of acetalization can ensure its solubility and film - forming property in the coating.

[0029] Furthermore, the weight ratio of isopropanol to water described in step S1 is (5 - 7):(2 - 3).

[0030] Furthermore, the emulsifier described in step S2 is composed of polyoxyethylene sorbitan monooleate and sodium dodecyl sulfate mixed according to the weight ratio of (1 - 2):1. Polyoxyethylene sorbitan monooleate can improve the emulsion stability, and sodium dodecyl sulfate can enhance the dispersibility. The synergistic combination of the two can further improve the emulsification effect.

[0031] According to some embodiments of the present application, the dosage of talc powder, zinc phosphate, aluminum hydroxide, and zinc chromate yellow in the rust - preventive pigment is in the weight ratio of (2 - 3):2:(2 - 3):1.

[0032] According to some embodiments of the present application, the polyphosphoric acid, silica sol, and citric acid in the conversion agent are mixed according to the weight ratio of (1 - 2):(2 - 3):1.

[0033] According to some embodiments of the present application, the corrosion inhibitor includes at least two of sodium nitrite, zinc dihydrogen phosphate, and potassium dichromate. When multiple corrosion inhibitors are used in combination, after ions with a certain charge are adsorbed on the metal surface, the adsorption of another kind of ion leads to an increase in surface coverage, which promotes each other and can enhance the corrosion inhibition effect, showing a synergistic effect.

[0034] Further, the corrosion inhibitor is prepared by mixing sodium nitrite, zinc dihydrogen phosphate, and potassium dichromate in a weight ratio of (3 - 5):(2 - 3):(1 - 2).

[0035] According to some embodiments of the present application, the auxiliary agent includes graphene.

[0036] Further, the graphene is pretreated: the graphene is ultrasonically dispersed in a mixed solution of phosphoric acid and nitric acid, then refluxed at 80 °C for 4 h, and after the reaction is completed, it is dried and ground.

[0037] In a second aspect, the embodiments of the present application provide a preparation method of the above-mentioned water-based rust-converting paint for steel structures, which is realized through the following technical solutions:

[0038] A preparation method of a water-based rust-converting paint for steel structures includes the following steps:

[0039] Mix the base material, anti-rust pigment, and water by weight, stir for 20 min - 30 min, add the conversion agent, penetrant, corrosion inhibitor, and auxiliary agent, and continue to stir for 1 - 2 h to obtain the water-based rust-converting paint for steel structures.

[0040] The preparation method of the water-based rust-converting paint for steel structures according to the embodiments of the present application has at least the following beneficial effects:

[0041] The preparation method of the present application has simple steps, does not require complex production equipment, has low cost, no pollution in the manufacturing process, no emission of toxic substances, does not harm the health of operators, and is suitable for industrial production.

[0042] According to some embodiments of the present application, the rotation speed of both stirrings is 1000 - 2000 r / min. Specific Embodiments

[0043] To make the purpose, technical solutions, and advantages of the present application clearer, the following will be further described in detail with specific embodiments. The embodiments described herein are only a part of the embodiments of the present application and should not be construed as a limitation on the protection scope of the present application.

[0044] Example 1

[0045] Preparation of waterborne rust-converting coating for steel structures: Raw materials are selected by weight parts: 45 parts of binder, 12 parts of rust-inhibitive pigment, 14 parts of converter, 3 parts of sodium dodecylbenzenesulfonate, 0.3 part of corrosion inhibitor, 1 part of graphene, and 30 parts of water; The binder is composed of waterborne polyester resin, polyvinyl butyral resin aqueous emulsion and styrene-acrylic emulsion according to a weight ratio of 2:1:2.5; The rust-inhibitive pigment is composed of talc powder, zinc phosphate, aluminum hydroxide and zinc chromate yellow according to a weight ratio of 2.5:2:3:1; The converter is prepared by mixing polyphosphoric acid, silica sol and citric acid according to a weight ratio of 1.5:2.5:1; The corrosion inhibitor is prepared by mixing sodium nitrite, zinc dihydrogen phosphate and potassium dichromate according to a weight ratio of 4:2.5:1.5;

[0046] Mix the binder, rust-inhibitive pigment and water by weight parts, stir at a speed of 1500 r / min for 25 min, add the converter, sodium dodecylbenzenesulfonate, corrosion inhibitor and graphene, and continue to stir at a speed of 1500 r / min for 1.5 h to obtain the waterborne rust-converting coating for steel structures;

[0047] Among them, the graphene is pretreated: The graphene is ultrasonically dispersed in a mixed solution of phosphoric acid and nitric acid, then refluxed at 80 °C for 4 h, and dried and ground after the reaction ends;

[0048] The preparation method of waterborne polyester resin is: Mix 8 parts of maleic anhydride, 22 parts of 1,4-butanediol, 3 parts of pentaerythritol, 8 parts of glutaric acid, 15 parts of terephthalic acid and 0.03 part of defoamer by weight parts, heat up to 160 °C for reaction, add 3 parts of acetone when the temperature rises to 230 °C, the pH value of the whole reaction system is 2-6, and reduce the pressure to -0.09 MPa to recover acetone; When the temperature is reduced to 175 °C, add 3 parts of phenylsuccinic anhydride for heat preservation, when the temperature is reduced to 150 °C, add 8 parts of diethylene glycol monomethyl ether and stir, mix 50 parts of water and 0.7 part of diethanolamine and add them to stir to obtain waterborne polyester resin;

[0049] The preparation method of polyvinyl butyral resin aqueous emulsion is:

[0050] S1. Slowly add polyvinyl butyral resin to the isopropanol-water mixture, stir at 60 °C for 1.5 hours until completely dissolved to form a transparent polyvinyl butyral resin glue solution;

[0051] S2. Mix the emulsifier and deionized water according to a weight ratio of 4.5:5.5, heat up to 50 °C, and stir until completely dissolved to obtain an emulsifier aqueous phase;

[0052] S3. Slowly drop 45 parts of the transparent polyvinyl butyral resin glue solution into 55 parts of the emulsifier aqueous phase by weight parts, and shear at a speed of 5000 rpm / min for 25 min;

[0053] S4. Evaporate isopropyl alcohol at a temperature of 55°C and a vacuum degree of -0.08 MPa, add 2.5 parts of tributyl acetylcitrate, stir for 32 min, adjust the pH to 8 - 9 with ammonia water, and filter through a 200-mesh sieve to obtain a polyvinyl butyral resin aqueous emulsion;

[0054] The molecular weight of the polyvinyl butyral resin described in step S1 is 20,000 - 40,000, and the degree of acetalization is 70 - 80%;

[0055] The weight ratio of isopropyl alcohol to water described in step S1 is 6:2.5;

[0056] The emulsifier described in step S2 is composed of polyoxyethylene sorbitan monooleate and sodium dodecyl sulfate mixed according to a weight ratio of 1.5:1.

[0057] Example 2

[0058] Preparation of waterborne rust-inhibiting paint for steel structures: Select raw materials by weight parts: 50 parts of binder, 10 parts of rust-inhibiting pigment, 16 parts of converter, 2 parts of polyoxyethylene alkylphenol ether, 0.5 part of corrosion inhibitor, 0.1 part of graphene, and 35 parts of water; The binder is composed of waterborne polyester resin, polyvinyl butyral resin aqueous emulsion and styrene-acrylic emulsion according to a weight ratio of 1:1:3; The rust-inhibiting pigment is composed of talc powder, zinc phosphate, aluminum hydroxide, zinc chromate yellow according to a weight ratio of 2:2:3:1; The converter is composed of polyphosphoric acid, silica sol, citric acid mixed according to a weight ratio of 1:3:1; The corrosion inhibitor is composed of sodium nitrite, zinc dihydrogen phosphate, potassium dichromate mixed according to a weight ratio of 3:3:1;

[0059] Mix the binder, rust-inhibiting pigment and water by weight parts, stir at a speed of 2000 r / min for 20 min, add the converter, polyoxyethylene alkylphenol ether, corrosion inhibitor, graphene, and continue to stir at a speed of 2000 r / min for 1 h to obtain a waterborne rust-inhibiting paint for steel structures;

[0060] Among them, graphene is pretreated: Graphene is ultrasonically dispersed in a mixed solution of phosphoric acid and nitric acid, and then refluxed at 80°C for 4 h. After the reaction, it is dried and ground;

[0061] The preparation method of waterborne polyester resin is: Mix 10 parts of maleic anhydride, 20 parts of 1,4-butanediol, 5 parts of pentaerythritol, 5 parts of glutaric acid, 20 parts of terephthalic acid and 0.01 part of defoamer by weight parts, heat up to 170°C for reaction, add 5 parts of acetone when the temperature rises to 210°C, the pH value of the whole reaction system is 2 - 6, and reduce the pressure to -0.09 MPa to recover acetone; When the temperature drops to 170°C, add 5 parts of phenyl succinic anhydride for heat preservation, when the temperature drops to 140°C, add 10 parts of diethylene glycol monomethyl ether and stir, mix 40 parts of water and 1 part of diethanolamine and add them for stirring to obtain waterborne polyester resin;

[0062] The preparation method of polyvinyl butyral resin aqueous emulsion is as follows:

[0063] S1. Slowly add polyvinyl butyral resin into the isopropanol-water mixture, stir at 60 °C for 1 hour until completely dissolved to form a transparent polyvinyl butyral resin glue solution;

[0064] S2. Mix the emulsifier and deionized water according to a weight ratio of 5:5, heat to 50 °C, and stir until completely dissolved to obtain an emulsifier aqueous phase;

[0065] S3. Slowly drop 50 parts by weight of the transparent polyvinyl butyral resin glue solution into 50 parts by weight of the emulsifier aqueous phase, and shear at a speed of 6000 rpm / min for 20 min;

[0066] S4. Evaporate isopropanol at a temperature of 60 °C and a vacuum degree of -0.08 MPa, add 2 parts of tributyl acetyl citrate, stir for 35 min, adjust the pH to 8-9 with ammonia water, and filter through a 200-mesh sieve to obtain polyvinyl butyral resin aqueous emulsion;

[0067] The molecular weight of the polyvinyl butyral resin described in step S1 is 20,000-40,000, and the degree of acetalization is 70-80%;

[0068] The weight ratio of isopropanol to water described in step S1 is 5:3;

[0069] The emulsifier described in step S2 is composed of polyoxyethylene sorbitan monooleate and sodium dodecyl sulfate according to a weight ratio of 1:1.

[0070] Example 3

[0071] Preparation of waterborne rust-inhibiting paint for steel structures: Select raw materials by weight: 40 parts of binder, 15 parts of anti-rust pigment, 12 parts of converter, 5 parts of sodium dodecylbenzenesulfonate, 0.1 part of corrosion inhibitor, 2 parts of graphene, 25 parts of water; The binder is composed of waterborne polyester resin, polyvinyl butyral resin aqueous emulsion and styrene-acrylic emulsion according to a weight ratio of 2:1:2; The anti-rust pigment is composed of talcum powder, zinc phosphate, aluminum hydroxide, zinc chromate yellow according to a weight ratio of 3:2:2:1; The converter is composed of polyphosphoric acid, silica sol, citric acid according to a weight ratio of 2:2:1; The corrosion inhibitor is composed of sodium nitrite, zinc dihydrogen phosphate, potassium dichromate according to a weight ratio of 5:2:2;

[0072] Mix the binder, anti-rust pigment and water by weight, stir at a speed of 1000 r / min for 30 min, add the converter, sodium dodecylbenzenesulfonate, corrosion inhibitor, graphene, and continue to stir at a speed of 1000 r / min for 2 h to obtain waterborne rust-inhibiting paint for steel structures;

[0073] Among them, the graphene is pretreated: the graphene is ultrasonically dispersed in a mixed solution of phosphoric acid and nitric acid, then refluxed at 80 °C for 4 h, and after the reaction is completed, it is dried and ground;

[0074] The preparation method of the waterborne polyester resin is as follows: 5 parts of maleic anhydride, 25 parts of 1,4-butanediol, 1 part of pentaerythritol, 10 parts of glutaric acid, 10 parts of terephthalic acid and 0.05 part of defoaming agent are mixed by weight and heated to 140 °C for reaction. When the temperature is raised to 240 °C, 1 part of acetone is added. The pH value of the whole reaction system is 2-6, and acetone is recovered under reduced pressure to -0.09 MPa; when the temperature is lowered to 180 °C, 1 part of phenylsuccinic anhydride is added for heat preservation, and when the temperature is lowered to 160 °C, 5 parts of diethylene glycol monomethyl ether are added and stirred. 60 parts of water and 0.5 part of diethanolamine are mixed and then added and stirred to obtain the waterborne polyester resin;

[0075] The preparation method of the polyvinyl butyral resin aqueous emulsion is as follows:

[0076] S1. Slowly add the polyvinyl butyral resin to the isopropanol-water mixed solution, stir at 60 °C for 2 hours until completely dissolved to form a transparent polyvinyl butyral resin glue solution;

[0077] S2. Mix the emulsifier and deionized water according to a weight ratio of 4:6, heat to 50 °C, and stir until completely dissolved to obtain an emulsifier aqueous phase;

[0078] S3. Slowly drop 40 parts of the transparent polyvinyl butyral resin glue solution into 60 parts of the emulsifier aqueous phase according to weight, and shear at a speed of 3000 rpm for 30 min;

[0079] S4. Evaporate isopropanol at a temperature of 50 °C and a vacuum degree of -0.08 MPa, add 3 parts of tributyl acetylcitrate, stir for 30 min, adjust the pH to 8-9 with ammonia water, and filter through a 200-mesh sieve to obtain the polyvinyl butyral resin aqueous emulsion;

[0080] The molecular weight of the polyvinyl butyral resin described in step S1 is 20000-40000, and the degree of acetalization is 70-80%;

[0081] The weight ratio of isopropanol to water described in step S1 is 7:2;

[0082] The emulsifier described in step S2 is composed of polyoxyethylene sorbitan monooleate and sodium dodecyl sulfate mixed according to a weight ratio of 2:1.

[0083] Example 4

[0084] Preparation of waterborne rust-inhibiting paint for steel structures: Select raw materials by weight parts: 45 parts of binder, 12 parts of rust-inhibiting pigment, 13 parts of converter, 4 parts of sodium dodecylbenzenesulfonate, 0.2 part of corrosion inhibitor, 0.5 part of graphene, and 30 parts of water; The binder is composed of waterborne polyester resin, polyvinyl butyral resin aqueous emulsion and styrene-acrylic emulsion according to the weight ratio of 1:1:2; The rust-inhibiting pigment is composed of talcum powder, zinc phosphate, aluminum hydroxide, and zinc chromate yellow according to the weight ratio of 3:2:3:1; The converter is prepared by mixing polyphosphoric acid, silica sol, and citric acid according to the weight ratio of 2:3:1; The corrosion inhibitor is prepared by mixing sodium nitrite, zinc dihydrogen phosphate, and potassium dichromate according to the weight ratio of 3:2:1;

[0085] Mix the binder, rust-inhibiting pigment and water by weight parts, stir at a speed of 1500 r / min for 25 min, add the converter, sodium dodecylbenzenesulfonate, corrosion inhibitor, and graphene, and continue to stir at a speed of 1500 r / min for 2 h to obtain the waterborne rust-inhibiting paint for steel structures;

[0086] Among them, the graphene is pretreated: The graphene is ultrasonically dispersed in a mixed solution of phosphoric acid and nitric acid, then refluxed at 80 °C for 4 h, and dried and ground after the reaction ends;

[0087] The preparation method of waterborne polyester resin is: Mix 7 parts of maleic anhydride, 22 parts of 1,4-butanediol, 3 parts of pentaerythritol, 7 parts of glutaric acid, 16 parts of terephthalic acid, and 0.04 part of defoamer by weight parts, heat up to 150 °C for reaction, add 4 parts of acetone when the temperature rises to 230 °C, the pH value of the whole reaction system is 2-6, and reduce the pressure to -0.09 MPa to recover acetone; When the temperature is reduced to 175 °C, add 3 parts of phenyl succinic anhydride for heat preservation, when the temperature is reduced to 150 °C, add 7 parts of diethylene glycol monomethyl ether and stir, mix 50 parts of water and 0.8 part of diethanolamine and add them for stirring to obtain waterborne polyester resin;

[0088] The preparation method of polyvinyl butyral resin aqueous emulsion is:

[0089] S1. Slowly add polyvinyl butyral resin to the isopropanol-water mixed solution, stir at 60 °C for 1.5 hours until completely dissolved to form a transparent polyvinyl butyral resin glue solution;

[0090] S2. Mix the emulsifier and deionized water according to the weight ratio of 4:5, heat to 50 °C, and stir until completely dissolved to obtain the emulsifier aqueous phase;

[0091] S3. Slowly drop 45 parts of the transparent polyvinyl butyral resin glue solution into 58 parts of the emulsifier aqueous phase by weight parts, and shear at a speed of 4000 rpm / min for 25 min;

[0092] S4. Evaporate isopropyl alcohol at a temperature of 55°C and a vacuum degree of -0.08 MPa, add 2.5 parts of tributyl acetylcitrate, stir for 33 min, adjust the pH to 8 - 9 with ammonia water, and filter through a 200-mesh sieve to obtain a polyvinyl butyral resin aqueous emulsion;

[0093] The molecular weight of the polyvinyl butyral resin described in step S1 is 20,000 - 40,000, and the degree of acetalization is 70 - 80%;

[0094] The weight ratio of isopropyl alcohol to water described in step S1 is 7:3;

[0095] The emulsifier described in step S2 is composed of polyoxyethylene sorbitan monooleate and sodium dodecyl sulfate mixed in a weight ratio of 2:1.

[0096] Comparative Example 1

[0097] Preparation of waterborne rust-inhibiting paint for steel structures: Select raw materials by weight parts: 45 parts of base material, 12 parts of rust-inhibiting pigment, 14 parts of converter, 3 parts of sodium dodecylbenzenesulfonate, 0.3 part of corrosion inhibitor, 1 part of graphene, and 30 parts of water; The base material is composed of a polyvinyl butyral resin aqueous emulsion and a styrene-acrylic emulsion in a weight ratio of 1:2.5; The rust-inhibiting pigment is composed of talc powder, zinc phosphate, aluminum hydroxide, and zinc chromate yellow in a weight ratio of 2.5:2:3:1; The converter is composed of polyphosphoric acid, silica sol, and citric acid mixed in a weight ratio of 1.5:2.5:1; The corrosion inhibitor is composed of sodium nitrite, zinc dihydrogen phosphate, and potassium dichromate mixed in a weight ratio of 4:2.5:1.5;

[0098] Mix the base material, rust-inhibiting pigment, and water by weight parts, stir at a speed of 1500 r / min for 25 min, add the converter, sodium dodecylbenzenesulfonate, corrosion inhibitor, and graphene, and continue to stir at a speed of 1500 r / min for 1.5 h to obtain a waterborne rust-inhibiting paint for steel structures;

[0099] Among them, graphene is pretreated: Graphene is ultrasonically dispersed in a mixed solution of phosphoric acid and nitric acid, and then refluxed at 80°C for 4 h. After the reaction is completed, it is dried and ground;

[0100] The preparation method of the polyvinyl butyral resin aqueous emulsion is as follows:

[0101] S1. Slowly add polyvinyl butyral resin to the isopropyl alcohol-water mixture, stir at 60°C for 1.5 hours until completely dissolved to form a transparent polyvinyl butyral resin colloidal solution;

[0102] S2. Mix the emulsifier and deionized water in a weight ratio of 4.5:5.5, heat to 50°C, and stir until completely dissolved to obtain an emulsifier aqueous phase;

[0103] S3. Slowly drop 45 parts by weight of the transparent polyvinyl butyral resin glue into 55 parts by weight of the emulsifier aqueous phase at a shearing speed of 5000 rpm for 25 min;

[0104] S4. Evaporate isopropyl alcohol at a temperature of 55 °C and a vacuum degree of -0.08 MPa, add 2.5 parts by weight of tributyl acetyl citrate, stir for 32 min, adjust the pH to 8 - 9 with ammonia water, and filter through a 200-mesh sieve to obtain a polyvinyl butyral resin aqueous emulsion;

[0105] The molecular weight of the polyvinyl butyral resin described in step S1 is 20,000 - 40,000, and the degree of acetalization is 70 - 80%;

[0106] The weight ratio of isopropyl alcohol to water described in step S1 is 6:2.5;

[0107] The emulsifier described in step S2 is composed of polyoxyethylene sorbitan monooleate and sodium dodecyl sulfate mixed according to a weight ratio of 1.5:1.

[0108] Comparative Example 2

[0109] Preparation of a waterborne rust-inhibiting paint for steel structures: Select raw materials by weight: 45 parts of a base material, 12 parts of an anti-rust pigment, 14 parts of a conversion agent, 3 parts of sodium dodecylbenzenesulfonate, 0.3 parts of a corrosion inhibitor, 1 part of graphene, and 30 parts of water; the base material is composed of an aqueous polyester resin and a styrene-acrylic emulsion according to a weight ratio of 2:2.5; the anti-rust pigment is composed of talc powder, zinc phosphate, aluminum hydroxide, and zinc chromate according to a weight ratio of 2.5:2:3:1; the conversion agent is composed of polyphosphoric acid, silica sol, and citric acid mixed according to a weight ratio of 1.5:2.5:1; the corrosion inhibitor is composed of sodium nitrite, zinc dihydrogen phosphate, and potassium dichromate mixed according to a weight ratio of 4:2.5:1.5;

[0110] Mix the base material, anti-rust pigment, and water by weight, stir at a speed of 1500 r / min for 25 min, add the conversion agent, sodium dodecylbenzenesulfonate, corrosion inhibitor, and graphene, and continue to stir at a speed of 1500 r / min for 1.5 h to obtain a waterborne rust-inhibiting paint for steel structures;

[0111] Among them, graphene is pretreated: Graphene is ultrasonically dispersed in a mixed solution of phosphoric acid and nitric acid, then refluxed at 80 °C for 4 h, and dried and ground after the reaction ends;

[0112] The preparation method of the waterborne polyester resin is as follows: Mix 8 parts of maleic anhydride, 22 parts of 1,4-butanediol, 3 parts of pentaerythritol, 8 parts of glutaric acid, 15 parts of terephthalic acid and 0.03 part of defoamer by weight, then heat up to 160 °C for reaction. When the temperature is raised to 230 °C, add 3 parts of acetone. The pH value of the whole reaction system is 2 - 6, and reduce the pressure to -0.09 MPa to recover acetone. When the temperature is lowered to 175 °C, add 3 parts of phenylsuccinic anhydride for heat preservation. When the temperature is lowered to 150 °C, add 8 parts of diethylene glycol monomethyl ether and stir. Mix 50 parts of water and 0.7 part of diethanolamine and then add them for stirring to obtain the waterborne polyester resin.

[0113] Comparative Example 3

[0114] Preparation of the waterborne rust-inhibiting paint for steel structures: Select raw materials by weight: 45 parts of binder, 12 parts of anti-rust pigment, 14 parts of converter, 3 parts of sodium dodecylbenzenesulfonate, 0.3 part of corrosion inhibitor, 1 part of graphene, 30 parts of water; The binder is composed of waterborne polyester resin, polyvinyl butyral resin aqueous emulsion and styrene-acrylic emulsion according to the weight ratio of 2:1:2.5; The anti-rust pigment is composed of talcum powder, zinc phosphate and zinc chromate yellow according to the weight ratio of 2.5:2:1; The converter is prepared by mixing polyphosphoric acid, silica sol and citric acid according to the weight ratio of 1.5:2.5:1; The corrosion inhibitor is prepared by mixing sodium nitrite, zinc dihydrogen phosphate and potassium dichromate according to the weight ratio of 4:2.5:1.

[0115] Mix the binder, anti-rust pigment and water by weight, stir at a speed of 1500 r / min for 25 min, add the converter, sodium dodecylbenzenesulfonate, corrosion inhibitor and graphene, and continue to stir at a speed of 1500 r / min for 1.5 h to obtain the waterborne rust-inhibiting paint for steel structures;

[0116] Among them, the graphene is pretreated as follows: The graphene is placed in a mixed solution of phosphoric acid and nitric acid for ultrasonic dispersion, and then refluxed at 80 °C for 4 h. After the reaction is completed, it is dried and ground;

[0117] The preparation method of the waterborne polyester resin is as follows: Mix 8 parts of maleic anhydride, 22 parts of 1,4-butanediol, 3 parts of pentaerythritol, 8 parts of glutaric acid, 15 parts of terephthalic acid and 0.03 part of defoamer by weight, then heat up to 160 °C for reaction. When the temperature is raised to 230 °C, add 3 parts of acetone. The pH value of the whole reaction system is 2 - 6, and reduce the pressure to -0.09 MPa to recover acetone. When the temperature is lowered to 175 °C, add 3 parts of phenylsuccinic anhydride for heat preservation. When the temperature is lowered to 150 °C, add 8 parts of diethylene glycol monomethyl ether and stir. Mix 50 parts of water and 0.7 part of diethanolamine and then add them for stirring to obtain the waterborne polyester resin;

[0118] The preparation method of the polyvinyl butyral resin aqueous emulsion is as follows:

[0119] S1. Slowly add polyvinyl butyral resin into the isopropanol-water mixture, stir at 60 °C for 1.5 hours until completely dissolved to form a transparent polyvinyl butyral resin glue solution;

[0120] S2. Mix the emulsifier and deionized water according to a weight ratio of 4.5:5.5, heat to 50 °C, and stir until completely dissolved to obtain an emulsifier aqueous phase;

[0121] S3. Slowly drop 45 parts by weight of the transparent polyvinyl butyral resin glue solution into 55 parts by weight of the emulsifier aqueous phase, and shear at a speed of 5000 rpm for 25 min;

[0122] S4. Evaporate isopropanol at a temperature of 55 °C and a vacuum degree of -0.08 MPa, add 2.5 parts by weight of tributyl acetylcitrate, stir for 32 min, adjust the pH to 8 - 9 with ammonia water, and filter through a 200-mesh sieve to obtain a polyvinyl butyral resin aqueous emulsion;

[0123] The molecular weight of the polyvinyl butyral resin described in step S1 is 20000 - 40000, and the degree of acetalization is 70 - 80%;

[0124] The weight ratio of isopropanol to water described in step S1 is 6:2.5;

[0125] The emulsifier described in step S2 is composed of polyoxyethylene sorbitan monooleate and sodium dodecyl sulfate according to a weight ratio of 1.5:1.

[0126] Comparative Example 4

[0127] Preparation of waterborne rust-inhibiting paint for steel structures: Select raw materials by weight: 45 parts of binder, 12 parts of rust-inhibiting pigment, 14 parts of converter, 3 parts of sodium dodecylbenzenesulfonate, 0.3 part of corrosion inhibitor, 1 part of graphene, 30 parts of water; The binder is composed of waterborne polyester resin, polyvinyl butyral resin aqueous emulsion and styrene-acrylic emulsion according to a weight ratio of 2:1:2.5; The rust-inhibiting pigment is composed of talc powder, zinc phosphate, aluminum hydroxide, zinc chromate yellow according to a weight ratio of 2.5:2:3:1; The converter is composed of polyphosphoric acid and silica sol according to a weight ratio of 1.5:2.5; The corrosion inhibitor is composed of sodium nitrite, zinc dihydrogen phosphate, potassium dichromate according to a weight ratio of 4:2.5:1.5;

[0128] Mix the binder, rust-inhibiting pigment and water by weight, stir at a speed of 1500 r / min for 25 min, add the converter, sodium dodecylbenzenesulfonate, corrosion inhibitor, graphene, and continue to stir at a speed of 1500 r / min for 1.5 h to obtain a waterborne rust-inhibiting paint for steel structures;

[0129] Among them, the graphene is pretreated: the graphene is ultrasonically dispersed in a mixed solution of phosphoric acid and nitric acid, then refluxed at 80 °C for 4 h, and dried and ground after the reaction ends;

[0130] The preparation method of the waterborne polyester resin is as follows: 8 parts of maleic anhydride, 22 parts of 1,4-butanediol, 3 parts of pentaerythritol, 8 parts of glutaric acid, 15 parts of terephthalic acid and 0.03 parts of defoamer are mixed according to weight parts and heated to 160 °C for reaction. When the temperature is raised to 230 °C, 3 parts of acetone are added. The pH value of the whole reaction system is 2-6, and acetone is recovered under reduced pressure to -0.09 MPa; when the temperature is lowered to 175 °C, 3 parts of phenylsuccinic anhydride are added for heat preservation, and when the temperature is lowered to 150 °C, 8 parts of diethylene glycol monomethyl ether are added and stirred. 50 parts of water and 0.7 parts of diethanolamine are mixed and then added and stirred to obtain the waterborne polyester resin;

[0131] The preparation method of the polyvinyl butyral resin aqueous emulsion is as follows:

[0132] S1. Slowly add the polyvinyl butyral resin into the isopropanol-water mixed solution, stir at 60 °C for 1.5 hours until completely dissolved to form a transparent polyvinyl butyral resin glue solution;

[0133] S2. Mix the emulsifier and deionized water according to a weight ratio of 4.5:5.5, heat to 50 °C, and stir until completely dissolved to obtain an emulsifier aqueous phase;

[0134] S3. Slowly drop 45 parts of the transparent polyvinyl butyral resin glue solution into 55 parts of the emulsifier aqueous phase according to weight parts, and shear at a speed of 5000 rpm for 25 min;

[0135] S4. Evaporate isopropanol at a temperature of 55 °C and a vacuum degree of -0.08 MPa, add 2.5 parts of tributyl acetylcitrate, stir for 32 min, adjust the pH to 8-9 with ammonia water, and filter through a 200-mesh sieve to obtain the polyvinyl butyral resin aqueous emulsion;

[0136] The molecular weight of the polyvinyl butyral resin described in step S1 is 20000-40000, and the degree of acetalization is 70-80%;

[0137] The weight ratio of isopropanol to water described in step S1 is 6:2.5;

[0138] The emulsifier described in step S2 is composed of polyoxyethylene sorbitan monooleate and sodium dodecyl sulfate mixed according to a weight ratio of 1.5:1.

[0139] The waterborne rusty steel structure coatings prepared in Examples 1-4 and Comparative Examples 1-4 are respectively coated on the rusty steel structure sheets, and the relevant properties of the coatings are tested. The test methods are as follows:

[0140] The adhesion force is tested according to the standard of GB / T 9286.

[0141] The salt spray resistance is tested according to the standard of GB / T 6458-86.

[0142] The corrosion resistance is measured and calculated by using an LK3200A electrochemical workstation to measure the corrosion rate on the surface of the steel structure sheet.

[0143] The test method for wear resistance is as follows: using a friction tester with a left-right swing method, and the test conditions are 4 pounds / 50 back-and-forth. The test evaluation standard for wear resistance is: it is divided into 1-5 levels from poor to excellent in turn.

[0144] The performance test data are shown in Table 1 below:

[0145] Table 1

[0146]

[0147] It can be seen from Table 1 that the waterborne rust-converting coatings for steel structures in Examples 1-4 of this application have good performance in all aspects. With the mutual combination of specific raw material ratios, the adhesion force, salt spray resistance, corrosion resistance, and wear resistance of the prepared coatings can all reach a relatively high level.

[0148] In Comparative Example 1, the waterborne polyester resin was not used in the binder of the raw materials, and the rest were the same as in Example 1. The adhesion force, salt spray resistance, corrosion resistance, and wear resistance of the coating prepared in Comparative Example 1 all decreased, indicating that the waterborne polyester resin of this application has good adhesion performance and can form a firm bond with various substrates. In the rust-converting coating, the waterborne polyester resin can penetrate into the rust gaps, enclose the active substances such as rust in the inert resin, thereby preventing the expansion and continuous generation of rust, and at the same time enhancing the adhesion force between the coating and the substrate. The waterborne polyester resin has high chemical stability and mechanical strength, which can improve the weather resistance and wear resistance of the coating.

[0149] In Comparative Example 2, the polyvinyl butyral resin aqueous emulsion was not used in the binder of the raw materials, and the rest were the same as in Example 1. The adhesion force, salt spray resistance, corrosion resistance, and wear resistance of the coating prepared in Comparative Example 2 all decreased, indicating that the polyvinyl butyral resin aqueous emulsion of this application can enhance the adhesion force on the surface of the steel structure, is not easy to fall off, and improves the anti-corrosion performance of the coating. The polyvinyl butyral resin has a relatively high glass transition temperature, which enhances the heat resistance and weather resistance of the coating. The polyvinyl butyral resin aqueous emulsion can also improve the fluidity and leveling property of the coating, making the coating easier to be evenly applied during construction, reducing the generation of bubbles and pinholes, and improving the quick-drying property of the coating; the polyvinyl butyral resin can form a dense protective film in the coating, isolating the direct contact between the metal and oxygen and moisture, thereby playing an anti-rust role, and cooperating with the anti-rust pigment, it can further improve the anti-rust performance of the coating.

[0150] In the anti-rust pigment of the raw materials of Comparative Example 3, aluminum hydroxide was not used, and the rest were the same as those in Example 1. The adhesion and corrosion resistance of the coating prepared in Comparative Example 3 decreased, indicating that aluminum hydroxide can provide aluminum ions, react with rust, dissolve the rust, combine the iron ions with the phosphate ions provided by zinc phosphate to form a firm and stable phosphating film, thereby stabilizing the rust and playing a role in corrosion inhibition and passivation of the rust layer; zinc chromate yellow can improve the adhesion of the paint film to the substrate, has good weather resistance, and can form a protective layer on the metal surface, having anodic protection and passivation effects.

[0151] In the conversion agent of the raw materials of Comparative Example 4, citric acid was not used, and the rest were the same as those in Example 1. The adhesion and corrosion resistance of the coating prepared in Comparative Example 4 decreased, indicating that citric acid can react with the iron ions in the rust to form a stable chelate, thereby converting the rust, helping to convert the harmful rust into harmless or less harmful substances, reducing the destructive effect of the rust on the coating. At the same time, citric acid interacts with the metal surface and other components in the coating to form chemical bonds or physical adsorption, improving the adhesion of the coating; citric acid can also improve the dispersibility, wettability and leveling property of the coating, making the coating easier to apply and level.

[0152] Although the embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions or variations can be made to these embodiments without departing from the principle and spirit of the present application, and the technical solutions after these changes, modifications, substitutions or variations will fall within the protection scope of the present application.

Claims

1. A water-based rust-resistant paint for steel structures, characterized in that: The preparation comprises the following raw materials in parts by weight: 40-50 parts of base material, 10-15 parts of anti-rust pigment, 12-16 parts of conversion agent, 2-5 parts of penetrant, 0.1-0.5 parts of corrosion inhibitor, 0.1-2 parts of additive, 25-35 parts of water; The base material is composed of water-based polyester resin, polyvinyl butyral resin aqueous emulsion and styrene acrylic emulsion in a weight ratio of (1-2):1:(2-3); The anti-rust pigment is composed of talcum powder, zinc phosphate, aluminum hydroxide and zinc chrome yellow; The conversion agent consists of polyphosphoric acid, silica sol and citric acid; The penetrant includes at least one of sodium dodecylbenzene sulfonate and polyoxyethylene alkylphenol ether.

2. The water-based rust-resistant paint for steel structure according to claim 1, characterized in that: The preparation of the water-based polyester resin comprises the following steps: mixing 5-10 parts of maleic anhydride, 20-25 parts of 1,4-butanediol, 1-5 parts of pentaerythritol, 5-10 parts of glutaric acid, 10-20 parts of terephthalic acid and 0.01-0.05 parts of a defoamer according to weight parts, heating to 140-170° C. for reaction, adding 1-5 parts of acetone when the temperature is raised to 210-240° C., the pH value of the whole reaction system is 2-6, reducing the pressure to -0.09 MPa to recover the acetone; adding 1-5 parts of phenylsuccinic anhydride when the temperature is lowered to 170-180° C. for heat preservation, adding 5-10 parts of diethylene glycol monomethyl ether when the temperature is lowered to 140-160° C., stirring, mixing 40-60 parts of water and 0.5-1 part of diethanolamine, adding and stirring to obtain the water-based polyester resin.

3. The water-based rust-resistant paint for steel structure according to claim 1, characterized in that: The preparation of the polyvinyl butyral resin aqueous emulsion comprises the following steps: S1. Slowly add the polyvinyl butyral resin to the isopropanol-water mixture and stir at 60°C for 1-2 hours until it is completely dissolved to form a transparent polyvinyl butyral resin glue; S2. The emulsifier and deionized water were mixed in a weight ratio of (4-5): (5-6), heated to 50 ° C, and stirred until completely dissolved to obtain an emulsifier aqueous phase; S3. According to parts by weight, 40-50 parts of a transparent polyvinyl butyral resin glue is slowly dripped into 50-60 parts of an aqueous emulsifier phase and sheared at a speed of 3000-6000 rpm / min for 20-30min; S4. Evaporate isopropanol at a temperature of 50-60°C and a vacuum degree of -0.08 MPa, add 2-3 parts of acetyl tributyl citrate, stir for 30-35 minutes, adjust the pH to 8-9 with aqueous ammonia, and filter through a 200-mesh sieve to obtain a polyvinyl butyral resin aqueous emulsion.

4. The water-based rust-resistant paint for steel structure according to claim 3, characterized in that: The molecular weight of the polyvinyl butyral resin in step S1 is 20000-40000, and the degree of acetalization is 70-80%.

5. The water-based rust-resistant paint for steel structure according to claim 3, characterized in that: The weight ratio of isopropanol to water in step S1 is (5-7):(2-3), and / or the emulsifier in step S2 is a mixture of polyoxyethylene sorbitan monooleate and sodium lauryl sulfate in a weight ratio of (1-2):

1.

6. The water-based rust-resistant paint for steel structure according to claim 1, characterized in that: The weight ratio of talc, zinc phosphate, aluminum hydroxide and zinc chrome yellow in the anti-rust pigment is (2-3):2:(2-3):

1.

7. The water-based rust-resistant paint for steel structure according to claim 1, characterized in that: The polyphosphoric acid, silica sol and citric acid in the conversion agent are mixed in a weight ratio of (1-2):(2-3):

1.

8. The water-based rust-resistant paint for steel structure according to claim 1, characterized in that: The corrosion inhibitor includes at least two of sodium nitrite, zinc dihydrogen phosphate and potassium dichromate.

9. The water-based rust-resistant paint for steel structure according to claim 1, characterized in that: The auxiliary agent includes graphene.

10. A method for preparing a water-based rust-resistant paint for steel structure according to any one of claims 1 to 9, characterized in that: The following steps are involved: Mix the base material, anti-rust pigment and water according to parts by weight, stir for 20-30 minutes, add the conversion agent, penetrant, corrosion inhibitor and additive, and continue stirring for 1-2 hours to obtain a water-based rust-resistant coating for steel structures.

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