Antirust coating and preparation method thereof

Abstract

This invention relates to the field of rust prevention. In order to improve the safety and rust prevention performance of rust-preventive coatings, a rust-preventive coating and its preparation method are provided. The preparation method includes the following steps: (1) Sodium hydroxide is added to an aqueous solution of zinc acetate and dispersed evenly. The solution is reacted in a hydrothermal reactor at 160-180℃ for 8-14 h to obtain nano-zinc oxide with a flower cluster structure. The molar ratio of sodium hydroxide to zinc acetate is (2-5):10; (2) The nano-zinc oxide obtained in step (1) is prepared into an aqueous solution, oxalic acid is added, and the solution is reacted in a hydrothermal reactor at 140-160℃ for 10-14 h to obtain an aqueous solution of zinc oxalate; (3) An additive is added to the aqueous solution of zinc oxalate obtained in step (2) to prepare a rust-preventive coating. This invention utilizes a hydrothermal method to generate zinc oxide with a specific morphology, which is then reacted with oxalic acid to obtain zinc oxalate. The prepared coating has excellent rust prevention performance.

Description

Technical Field

[0001] This invention relates to the field of rust prevention, and in particular to a rust-preventive coating and its preparation method. Background Technology

[0002] Rust-preventive coatings protect metal surfaces from chemical or electrochemical corrosion by the atmosphere, seawater, etc. Applying rust-preventive coatings to metal surfaces effectively prevents the direct intrusion of various corrosive substances in the atmosphere, extending the service life of the metal. They can be divided into two main categories: physical and chemical rust-preventive paints. The former relies on the appropriate combination of pigments and paints to form a dense paint film to prevent the intrusion of corrosive substances, such as iron oxide red, aluminum powder, and graphite rust-preventive paints; the latter relies on the chemical rust-inhibiting effect of rust-preventive pigments, such as red lead and zinc yellow rust-preventive paints. They are used for rust prevention of metals such as bridges, ships, and pipelines.

[0003] Oxalic acid is widely used in rust prevention. Its rust-preventing principle is twofold: firstly, oxalic acid reacts with the oxide layer on the metal surface to form oxalates, thus smoothing the metal surface and preventing further oxide formation; secondly, oxalic acid reacts with moisture in the air to form stable oxalates, weakening the oxide layer on the metal surface and forming a protective film to prevent rust. However, oxalic acid is highly corrosive, 2000 times stronger than acetic acid. Improper use can corrode the skin on the hands, and in severe cases, cause burns and ulcers. Furthermore, oxalic acid can be absorbed into the body through the skin or oral mucosa; excessive intake can easily lead to poisoning, causing symptoms such as nausea, vomiting, and diarrhea.

[0004] Zinc, as a rust-preventive material, primarily works by forming a protective zinc oxide film on the metal surface. When zinc covers a metal surface, it reacts with oxygen to form zinc oxide, creating a thin film on the metal surface. This film effectively isolates the metal surface from air, preventing further oxidation and corrosion. Furthermore, zinc has a higher electrode potential than iron, allowing it to absorb electrons generated on the metal surface, creating electron holes that prevent further intrusion of external electrons, thus achieving the rust-preventive effect.

[0005] Existing technologies include the use of oxalic acid and / or zinc in rust-preventive coatings. For example, patent CN103709853A discloses a conductive rust-preventive coating and its preparation method, specifically disclosing that the conductive rust-preventive coating is made by uniformly mixing conductive graphite powder, copper powder, zinc powder, carbon nanotubes, polyvinylidene fluoride, oxalic acid, and N-methylpyrrolidone. The zinc powder in the coating acts as an anode through the conductive pathways of the conductive graphite powder and copper powder, using a sacrificial anode protection method to prevent corrosion of the copper powder and metal surfaces, thus giving the coating rust-preventive properties. The oxalic acid in the coating can eliminate the oxide layer on the surface of the copper and zinc powders, allowing them to fully exert their function. However, existing technologies do not yet include the preparation of zinc oxalate from oxalic acid and zinc for use in rust-preventive coatings. Summary of the Invention

[0006] In order to improve the safety and rust prevention performance of rust-preventive coatings, this invention provides a rust-preventive coating and its preparation method. Zinc oxide with a specific morphology is generated by hydrothermal method, and then reacted with oxalic acid to obtain zinc oxalate. The resulting coating has excellent rust prevention performance.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing an anti-rust coating includes the following steps: (1) Preparation of zinc oxide Sodium hydroxide was added to an aqueous solution of zinc acetate and dispersed evenly. The solution was then reacted in a hydrothermal reactor at 160-180℃ for 8-14 hours to obtain nano-zinc oxide with a flower cluster structure. The molar ratio of sodium hydroxide to zinc acetate was (2-5):10. (2) Preparation of zinc oxalate The nano zinc oxide obtained in step (1) is prepared into an aqueous solution, oxalic acid is added, and the solution is reacted in a hydrothermal reactor at 140-160℃ for 10-14 hours to obtain an aqueous solution of zinc oxalate. (3) Prepare coating Additives are added to the zinc oxalate aqueous solution obtained in step (2) to prepare an anti-rust coating.

[0008] Preferably, the concentration of the zinc acetate aqueous solution in step (1) is 0.05-0.08 mol / L.

[0009] Preferably, the reaction time for step (1) is 11-13 hours.

[0010] Preferably, the reaction solution obtained in step (1) is centrifuged, washed, and dried to obtain nano zinc oxide.

[0011] Preferably, in step (2), the molar ratio of nano zinc oxide to oxalic acid is (1.7-2):1.

[0012] Preferably, the concentration of the nano zinc oxide aqueous solution in step (2) is 2-4 mol / L.

[0013] Preferably, the additives in step (3) include one or more of the following: thickener, wetting agent, defoamer, formulation, acrylic emulsion, and film-forming aid. The formulation is selected from one or more of titanium dioxide, calcium titanate, and talc. The acrylic emulsion has a solids content of 49–51% (150°C, 20 min).

[0014] Preferably, step (3) includes: 1) Add thickener to zinc oxalate aqueous solution and stir, then add wetting agent and stir, then add defoamer and stir; 2) Add the formulation to the system in 1) and stir; 3) Add acrylic emulsion, defoamer II, and film-forming aid to the system in 2) and stir to obtain rust-preventive coating.

[0015] Preferably, the mass fractions of each component are: 20-33 parts zinc oxalate aqueous solution, 0.1-0.3 parts thickener, 0.3-0.5 parts wetting agent, 0.1-0.3 parts defoamer one, 9-11 parts bulk preparation, 50-70 parts acrylic emulsion, 0.1-0.3 parts defoamer two, and 0.1-0.3 parts film-forming aid.

[0016] Preferably, the stirring speed in step 1) is 800-1000 r / min, and the stirring time is 8-12 min each time; the stirring speed in step 2) is 1800-2200 r / min, and the stirring time is 20-30 min; the stirring speed in step 3) is 800-1000 r / min.

[0017] The present invention also provides an anti-rust coating prepared by the above method, which is composed of zinc oxalate, thickener, wetting agent, defoamer, bulking agent, acrylic emulsion, and film-forming aid.

[0018] Therefore, the beneficial effects of this invention are as follows: First, zinc oxide with a flower-like microstructure is generated using a hydrothermal method. Then, it is reacted with oxalic acid to obtain zinc oxalate, which, from a microscopic perspective, exhibits a flocculent structure with a rich network structure. As a major component in anti-rust coatings, it can improve the reactivity with impurities and enhance the film's opacity, resulting in excellent anti-rust performance. Attached Figure Description

[0019] Figure 1 The images show SEM images of zinc oxide prepared in Comparative Example 2, Example 1, and Example 2. In the images, (a) corresponds to Comparative Example 2, (b) corresponds to Example 1, and (c) corresponds to Example 2.

[0020] Figure 2 This is an SEM image of the zinc oxalate prepared in Example 2.

[0021] Figure 3 This is the SEM image of zinc oxalate in Comparative Example 1.

[0022] Figure 4 This is a SEM image of commercially available zinc oxalate from Comparative Example 3. Detailed Implementation

[0023] The technical solution of the present invention will be further described below through specific embodiments.

[0024] In this invention, unless otherwise specified, the raw materials and equipment used are commercially available or commonly used in the art. The methods in the embodiments, unless otherwise specified, are conventional methods in the art. Unless otherwise specified, all parts are parts by weight, temperatures are expressed in °C or at ambient temperature, and pressures are at or near atmospheric pressure. Various variations and combinations of reaction conditions (e.g., component concentrations, required solvents, solvent mixtures, temperature, pressure, and other reaction ranges) and conditions that can be used to optimize the purity and yield of the product obtained by the method exist, and only reasonable routine experiments are needed to optimize such method conditions.

[0025] Example A method for preparing an anti-rust coating includes the following steps: Step 1: Preparation of nano-zinc oxide via hydrothermal method Zinc acetate was added to deionized water and stirred until dissolved to obtain an aqueous solution of zinc acetate with a molar concentration of 0.05-0.08 mol / L. Sodium hydroxide was then added to the zinc acetate aqueous solution and stirred until dissolved to obtain a mixed solution. The molar ratio of sodium hydroxide to zinc acetate was (2-5):10. The mixed solution was transferred to a hydrothermal reactor and reacted at 160-180℃ for 8-14 hours to obtain a reaction solution, preferably for 11-13 hours. The reaction solution was centrifuged, washed, and dried to obtain a flower-like structured nano-zinc oxide product.

[0026] Step 2: Preparation of zinc oxalate by hydrothermal method The nano-zinc oxide obtained in step one is prepared into an aqueous solution with a molar concentration of 2-4 mol / L. Oxalic acid is then added to the solution to obtain a mixed solution with a molar ratio of nano-zinc oxide to oxalic acid of (1.7-2):1. The mixed solution is then transferred to a hydrothermal reactor and reacted at 140-160℃ for 10-14 h to obtain an aqueous solution of zinc oxalate.

[0027] Step 3: Prepare anti-rust coating 1) By weight, take 20-33 parts of the zinc oxalate aqueous solution obtained in step two. Under stirring conditions of 800-1000 r / min, add 0.1-0.3 parts of thickener and stir for 8-12 min, add 0.3-0.5 parts of wetting agent and stir for 8-12 min, and add 0.1-0.3 parts of defoamer and stir for 8-12 min. The thickener is one or more of TCP-936 and RT-1035. The wetting agent is one or more of ND-4070 and ND-805. The defoamer is one or more of RT-10 and NXZ-A.

[0028] 2) Increase the stirring speed to 1800-2200 r / min, add 9-11 parts of the formulation to the system in 1) and stir for 20-30 min; the formulation is selected from one or more of titanium dioxide, calcium titanate, and talc.

[0029] 3) Adjust the stirring speed back to 800-1000 r / min, and add 50-70 parts of acrylic emulsion with a solid content of 49-51% (150℃, 20min), 0.1-0.3 parts of defoamer II, and 0.1-0.3 parts of film-forming aid to the system in step 2), and stir to obtain the anti-rust coating. The defoamer II is one or more of RT-10 and NXZ-A, and the film-forming aid is one or more of K-54 and DMP-30.

[0030] Example 1 A method for preparing an anti-rust coating, comprising the following steps: (1) Preparation of nano zinc oxide by hydrothermal method First, 10 mmol of zinc acetate was weighed and dissolved in 150 mL of deionized water and stirred for 30 minutes. Then, 3 mmol of sodium hydroxide was weighed and added to the above solution, and stirring was continued for 30 minutes to obtain a mixed solution. The mixed solution was then transferred to a hydrothermal reactor and reacted at 170°C for 8 hours to obtain a reaction solution. Finally, the reaction solution was centrifuged, washed, and dried to obtain a flower-shaped nano zinc oxide product.

[0031] (2) Preparation of zinc oxalate by hydrothermal method Take 5g of the nano zinc oxide obtained in step one and add it to 20mL of deionized water. Stir for 30 minutes at a speed of 1000r / min. Then add 3g of oxalic acid to obtain a mixed solution. Transfer the mixed solution to a hydrothermal reactor and react at 150℃ for 12 hours to obtain an aqueous solution of zinc oxalate.

[0032] (3) Preparation of anti-rust coating (3.1) Take 25 parts of the zinc oxalate aqueous solution obtained in step 2 by mass, and add 0.2 parts of thickener TCP-936 and stir for 10 minutes under stirring conditions of 1000 r / min, add 0.4 parts of wetting agent ND-4070 and stir for 10 minutes, and add 0.2 parts of defoamer RT-10 and stir for 10 minutes.

[0033] (3.2) Increase the stirring speed to 2000 r / min, add 10 parts of the preparation titanium dioxide to the system in 1) and stir for 30 minutes.

[0034] (3.3) Adjust the stirring speed back to 1000 r / min, add 60 parts of acrylic emulsion with a solid content of 50% (150℃, 20min), 0.2 parts of defoamer RT-10, and 0.2 parts of film-forming aid K-54 to the system in step 2) and stir to obtain the anti-rust coating.

[0035] Example 2 The difference from Example 1 is that the reaction time in step (1) is 12 hours. Specifically: A method for preparing an anti-rust coating, comprising the following steps: (1) Preparation of nano zinc oxide by hydrothermal method First, 10 mmol of zinc acetate was weighed and dissolved in 150 mL of deionized water and stirred for 30 minutes. Then, 3 mmol of sodium hydroxide was weighed and added to the above solution, and stirring was continued for 30 minutes to obtain a mixed solution. The mixed solution was then transferred to a hydrothermal reactor and reacted at 170°C for 12 hours to obtain a reaction solution. Finally, the reaction solution was centrifuged, washed, and dried to obtain a flower-shaped nano zinc oxide product.

[0036] (2) Preparation of zinc oxalate by hydrothermal method Take 5g of the nano zinc oxide obtained in step one and add it to 20mL of deionized water. Stir for 30 minutes at a speed of 1000r / min. Then add 3g of oxalic acid to obtain a mixed solution. Transfer the mixed solution to a hydrothermal reactor and react at 150℃ for 12 hours to obtain an aqueous solution of zinc oxalate.

[0037] (3) Preparation of anti-rust coating (3.1) Take 25 parts of the zinc oxalate aqueous solution obtained in step 2 by mass, and add 0.2 parts of thickener TCP-936 and stir for 10 minutes under stirring conditions of 1000 r / min, add 0.4 parts of wetting agent ND-4070 and stir for 10 minutes, and add 0.2 parts of defoamer RT-10 and stir for 10 minutes.

[0038] (3.2) Increase the stirring speed to 2000 r / min, add 10 parts of the preparation titanium dioxide to the system in 1) and stir for 30 minutes.

[0039] (3.3) Adjust the stirring speed back to 1000 r / min, add 60 parts of acrylic emulsion with a solid content of 50% (150℃, 20min), 0.2 parts of defoamer RT-10, and 0.2 parts of film-forming aid K-54 to the system in step 2) and stir to obtain the anti-rust coating.

[0040] Example 3 The difference from Example 2 is that in step (2), the molar ratio of nano-zinc oxide to oxalic acid is 2.5:1. Specifically: A method for preparing an anti-rust coating, comprising the following steps: (1) Preparation of nano zinc oxide by hydrothermal method First, 10 mmol of zinc acetate was weighed and dissolved in 150 mL of deionized water and stirred for 30 minutes. Then, 3 mmol of sodium hydroxide was weighed and added to the above solution, and stirring was continued for 30 minutes to obtain a mixed solution. The mixed solution was then transferred to a hydrothermal reactor and reacted at 170°C for 12 hours to obtain a reaction solution. Finally, the reaction solution was centrifuged, washed, and dried to obtain a flower-shaped nano zinc oxide product.

[0041] (2) Preparation of zinc oxalate by hydrothermal method Take 5g of the nano zinc oxide obtained in step one and add it to 20mL of deionized water. Stir for 30 minutes at a speed of 1000r / min. Then add 2.2g of oxalic acid to obtain a mixed solution. Transfer the mixed solution to a hydrothermal reactor and react at 150℃ for 12 hours to obtain an aqueous solution of zinc oxalate.

[0042] (3) Preparation of anti-rust coating (3.1) Take 25 parts of the zinc oxalate aqueous solution obtained in step 2 by mass, and add 0.2 parts of thickener TCP-936 and stir for 10 minutes under stirring conditions of 1000 r / min, add 0.4 parts of wetting agent ND-4070 and stir for 10 minutes, and add 0.2 parts of defoamer RT-10 and stir for 10 minutes.

[0043] (3.2) Increase the stirring speed to 2000 r / min, add 10 parts of the preparation titanium dioxide to the system in 1) and stir for 30 minutes.

[0044] (3.3) Adjust the stirring speed back to 1000 r / min, add 60 parts of acrylic emulsion with a solid content of 50% (150℃, 20min), 0.2 parts of defoamer RT-10, and 0.2 parts of film-forming aid K-54 to the system in step 2) and stir to obtain the anti-rust coating.

[0045] Example 4 A method for preparing an anti-rust coating, comprising the following steps: (1) Preparation of nano zinc oxide by hydrothermal method First, 7.5 mmol of zinc acetate was weighed and dissolved in 150 mL of deionized water and stirred for 30 minutes. Then, 1.5 mmol of sodium hydroxide was weighed and added to the above solution, and stirring was continued for 30 minutes to obtain a mixed solution. The mixed solution was then transferred to a hydrothermal reactor and reacted at 160 °C for 14 hours to obtain a reaction solution. Finally, the reaction solution was centrifuged, washed, and dried to obtain a flower-shaped nano zinc oxide product.

[0046] (2) Preparation of zinc oxalate by hydrothermal method 0.04 mol of the nano-zinc oxide obtained in step one was added to 20 mL of deionized water and stirred for 30 minutes at a speed of 1000 r / min. Then, 0.02 mol of oxalic acid was added to obtain a mixed solution. The mixed solution was transferred to a hydrothermal reactor and reacted at 140 °C for 14 hours to obtain an aqueous solution of zinc oxalate.

[0047] (3) Preparation of anti-rust coating (3.1) Take 20 parts by mass of the zinc oxalate aqueous solution obtained in step 2, and add 0.1 parts of thickener RT-1035 and stir for 12 minutes under stirring conditions of 800 r / min, add 0.3 parts of wetting agent ND-805 and stir for 12 minutes, and add 0.1 parts of defoamer NXZ-A and stir for 12 minutes.

[0048] (3.2) Increase the stirring speed to 1800 r / min, add 9 parts of the preparation calcium titanate to the system in 1) and stir for 20 minutes.

[0049] (3.3) Adjust the stirring speed back to 800 r / min, add 50 parts of acrylic emulsion with a solid content of 49% (150℃, 20min), 0.1 parts of defoamer NXZ-A, and 0.1 parts of film-forming aid DMP-30 to the system in step 2) and stir to obtain the anti-rust coating.

[0050] Example 5 A method for preparing an anti-rust coating, comprising the following steps: (1) Preparation of nano zinc oxide by hydrothermal method First, 12 mmol of zinc acetate was weighed and dissolved in 150 mL of deionized water and stirred for 30 minutes. Then, 6 mmol of sodium hydroxide was weighed and added to the above solution, and stirring was continued for 30 minutes to obtain a mixed solution. The mixed solution was then transferred to a hydrothermal reactor and reacted at 180°C for 11 hours to obtain a reaction solution. Finally, the reaction solution was centrifuged, washed, and dried to obtain a flower-shaped nano zinc oxide product.

[0051] (2) Preparation of zinc oxalate by hydrothermal method 0.08 mol of the nano-zinc oxide obtained in step one was added to 20 mL of deionized water and stirred for 30 minutes at a speed of 1000 r / min. Then, 0.47 mol of oxalic acid was added to obtain a mixed solution. The mixed solution was transferred to a hydrothermal reactor and reacted at 160 °C for 10 hours to obtain an aqueous solution of zinc oxalate.

[0052] (3) Preparation of anti-rust coating (3.1) Take 33 parts by mass of the zinc oxalate aqueous solution obtained in step 2, and add 0.3 parts of thickener RT-1035 and stir for 8 minutes under stirring conditions of 1000 r / min, add 0.3 parts of wetting agent ND-805 and stir for 8 minutes, and add 0.3 parts of defoamer NXZ-A and stir for 8 minutes.

[0053] (3.2) Increase the stirring speed to 2200 r / min, add 11 parts of the talc preparation to the system in step 1) and stir for 30 minutes.

[0054] (3.3) Adjust the stirring speed back to 1000 r / min, add 70 parts of acrylic emulsion with a solid content of 51% (150℃, 20min), 0.3 parts of defoamer NXZ-A, and 0.3 parts of film-forming aid DMP-30 to the system in step 2) and stir to obtain the anti-rust coating.

[0055] Comparative Example 1 The difference from Example 1 is that zinc oxide and oxalic acid are mixed at room temperature. Specifically: A method for preparing an anti-rust coating, comprising the following steps: (1) Preparation of nano zinc oxide by hydrothermal method First, 10 mmol of zinc acetate was weighed and dissolved in 150 mL of deionized water and stirred for 30 minutes. Then, 3 mmol of sodium hydroxide was weighed and added to the above solution, and stirring was continued for 30 minutes to obtain a mixed solution. The mixed solution was then transferred to a hydrothermal reactor and reacted at 170°C for 8 hours to obtain a reaction solution. Finally, the reaction solution was centrifuged, washed, and dried to obtain a flower-shaped nano zinc oxide product.

[0056] (2) Preparation of zinc oxalate at room temperature Take 5g of the nano zinc oxide obtained in step one and add it to 20mL of deionized water. Stir for 30 minutes at a speed of 1000r / min. Then add 3g of oxalic acid to obtain a mixed solution. Stir the mixed solution at room temperature for 12 hours to obtain an aqueous solution of zinc oxalate.

[0057] (3) Preparation of anti-rust coating (3.1) Take 25 parts of the zinc oxalate aqueous solution obtained in step 2 by mass, and add 0.2 parts of thickener TCP-936 and stir for 10 minutes under stirring conditions of 1000 r / min, add 0.4 parts of wetting agent ND-4070 and stir for 10 minutes, and add 0.2 parts of defoamer RT-10 and stir for 10 minutes.

[0058] (3.2) Increase the stirring speed to 2000 r / min, add 10 parts of the preparation titanium dioxide to the system in 1) and stir for 30 minutes.

[0059] (3.3) Adjust the stirring speed back to 1000 r / min, add 60 parts of acrylic emulsion with a solid content of 50% (150℃, 20min), 0.2 parts of defoamer RT-10, and 0.2 parts of film-forming aid K-54 to the system in step 2) and stir to obtain the anti-rust coating.

[0060] Comparative Example 2 The difference from Example 1 is that the reaction time in step (1) is 4 hours. Specifically: A method for preparing an anti-rust coating, comprising the following steps: (1) Preparation of nano zinc oxide by hydrothermal method First, 10 mmol of zinc acetate was weighed and dissolved in 150 mL of deionized water and stirred for 30 minutes. Then, 3 mmol of sodium hydroxide was weighed and added to the above solution, and stirring was continued for 30 minutes to obtain a mixed solution. The mixed solution was then transferred to a hydrothermal reactor and reacted at 170°C for 4 hours to obtain a reaction solution. Finally, the reaction solution was centrifuged, washed, and dried to obtain a flower-shaped nano zinc oxide product.

[0061] (2) Preparation of zinc oxalate by hydrothermal method Take 5g of the nano zinc oxide obtained in step one and add it to 20mL of deionized water. Stir for 30 minutes at a speed of 1000r / min. Then add 3g of oxalic acid to obtain a mixed solution. Transfer the mixed solution to a hydrothermal reactor and react at 150℃ for 12 hours to obtain an aqueous solution of zinc oxalate.

[0062] (3) Preparation of anti-rust coating (3.1) Take 25 parts of the zinc oxalate aqueous solution obtained in step 2 by mass, and add 0.2 parts of thickener TCP-936 and stir for 10 minutes under stirring conditions of 1000 r / min, add 0.4 parts of wetting agent ND-4070 and stir for 10 minutes, and add 0.2 parts of defoamer RT-10 and stir for 10 minutes.

[0063] (3.2) Increase the stirring speed to 2000 r / min, add 10 parts of the preparation titanium dioxide to the system in 1) and stir for 30 minutes.

[0064] (3.3) Adjust the stirring speed back to 1000 r / min, add 60 parts of acrylic emulsion with a solid content of 50% (150℃, 20min), 0.2 parts of defoamer RT-10, and 0.2 parts of film-forming aid K-54 to the system in step 2) and stir to obtain the anti-rust coating.

[0065] Comparative Example 3 The difference from Example 1 is that step (2) directly uses commercially available zinc oxalate. Specifically: A method for preparing an anti-rust coating, comprising the following steps: (1) Prepare an aqueous solution of commercially available zinc oxalate (concentration same as in Example 1) by mass parts. Under stirring conditions of 1000 r / min, add 0.2 parts of thickener TCP-936 and stir for 10 minutes, add 0.4 parts of wetting agent ND-4070 and stir for 10 minutes, and add 0.2 parts of defoamer RT-10 and stir for 10 minutes.

[0066] (2) Increase the stirring speed to 2000 r / min, add 10 parts of the preparation titanium dioxide to the system in (1) and stir for 30 minutes.

[0067] (3) Adjust the stirring speed back to 1000 r / min, add 60 parts of acrylic emulsion with a solid content of 50% (150℃, 20min), 0.2 parts of defoamer RT-10, and 0.2 parts of film-forming aid K-54 to the system in step 2) and stir to obtain the anti-rust coating.

[0068] Comparative Example 4 The difference from Example 2 is that in step (1), the molar ratio of sodium hydroxide to zinc acetate is 6:10. Specifically: A method for preparing an anti-rust coating, comprising the following steps: (1) Preparation of nano zinc oxide by hydrothermal method First, weigh 10 mmol of zinc acetate and dissolve it in 150 mL of deionized water and stir for 30 minutes. Then, weigh 6 mmol of sodium hydroxide and add it to the above solution, and continue stirring for 30 minutes to obtain a mixed solution. Then, transfer the mixed solution to a hydrothermal reactor and react at 170°C for 12 hours to obtain a reaction solution. Finally, centrifuge, wash, and dry the reaction solution to obtain nano zinc oxide product.

[0069] (2) Preparation of zinc oxalate by hydrothermal method Take 5g of the nano zinc oxide obtained in step one and add it to 20mL of deionized water. Stir for 30 minutes at a speed of 1000r / min. Then add 3g of oxalic acid to obtain a mixed solution. Transfer the mixed solution to a hydrothermal reactor and react at 150℃ for 12 hours to obtain an aqueous solution of zinc oxalate.

[0070] (3) Preparation of anti-rust coating (3.1) Take 25 parts of the zinc oxalate aqueous solution obtained in step 2 by mass, and add 0.2 parts of thickener TCP-936 and stir for 10 minutes under stirring conditions of 1000 r / min, add 0.4 parts of wetting agent ND-4070 and stir for 10 minutes, and add 0.2 parts of defoamer RT-10 and stir for 10 minutes.

[0071] (3.2) Increase the stirring speed to 2000 r / min, add 10 parts of the preparation titanium dioxide to the system in 1) and stir for 30 minutes.

[0072] (3.3) Adjust the stirring speed back to 1000 r / min, add 60 parts of acrylic emulsion with a solid content of 50% (150℃, 20min), 0.2 parts of defoamer RT-10, and 0.2 parts of film-forming aid K-54 to the system in step 2) and stir to obtain the anti-rust coating.

[0073] Performance testing Rust-preventive performance tests were conducted on the rust-preventive coatings prepared in each embodiment and comparative example. The test methods are as follows: (1) First, the coating was uniformly sprayed onto the rusted substrate using a spray gun. After natural drying, a salt spray corrosion test was conducted according to the national standard GB / T10125-1997 "Test Method for Fume Corrosion". A 5% salt water (NaCl) solution was used as the corrosion medium. The pH value of the environment was adjusted to 6.8-7.1 using a continuous spraying method. The test temperature was room temperature (30℃), and the test period was 240h. (2) The coating adhesion was determined according to the national standard ASTM D 3359-2002 "Adhesion Test by Tape Method". (3) The drying time was determined according to the national standard GB / T 1728-1979. The results are shown in the table below. Example 1 A small amount of dotted red rust 3-4 25 Example 2 Bright and rust-free 3-4 30 Example 3 A small amount of dotted red rust 3-4 28 Example 4 Bright and rust-free 3 34 Example 5 Bright and rust-free 3 32 Comparative Example 1 flaky red rust 3 41 Comparative Example 2 Numerous spots of red rust 3-4 35 Comparative Example 3 flaky red rust 2-3 38 Comparative Example 4 Numerous spots of red rust 3 34

[0074] As can be seen from the table above, the rust-preventive coatings prepared in the various embodiments of the present invention have excellent rust-preventive properties, and the coatings also have strong adhesion and short drying time. Example 2 is the optimal embodiment. Compared with Example 2: (1) Comparative Example 2: Hydrothermal zinc oxide preparation reaction for 4 hours; Example 1: Hydrothermal zinc oxide preparation reaction for 8 hours; Example 2: Hydrothermal zinc oxide preparation reaction for 12 hours. The SEM images of the three are shown below. Figure 1 As shown in the figure, from left to right, they represent water glass 2, Example 1, and Example 2. It can be seen that the morphology of zinc oxide changes significantly with the extension of the hydrothermal reaction time. After 4 hours, only a small amount of zinc oxide nanosheets are obtained. After 8 hours, the morphology of zinc oxide changes from nanosheets to a flower-like structure assembled from nanosheets, but the flower-like structure is not uniform. After 12 hours, a large number of uniform zinc oxide flower-like structures can be obtained. The uniform zinc oxide flower-like structure is beneficial for reacting with oxalic acid to obtain uniform flocculent zinc oxalate, thus improving the rust-preventive performance.

[0075] (2) In Comparative Example 4, when zinc oxide was prepared by the hydrothermal method, the amount of sodium hydroxide used exceeded the optimal range, making it impossible to form zinc oxide with a flower-like morphology, and ultimately the anti-rust performance of the coating decreased significantly.

[0076] (3) Example 2: Zinc oxide and oxalic acid underwent a hydrothermal reaction, and the resulting zinc oxalate SEM image is shown below. Figure 2 As shown in the figure. In Comparative Example 1, zinc oxide and oxalic acid were directly mixed at room temperature, resulting in a low degree of reaction. The SEM image of the obtained zinc oxalate is shown in the figure. Figure 3 As shown. Comparative Example 3 used commercially available zinc oxalate, and the SEM image is shown below. Figure 4 As shown.

[0077] The unique structure and diverse coordination of oxalate ions allow them to act as monodentate or polydentate ligands, coordinating with metal ions to form one-dimensional or multi-dimensional network coordination polymers. This invention reacts zinc oxide with a flower cluster structure and oxalic acid to obtain, for example... Figure 2The flocculent zinc oxalate shown possesses a rich network structure. As a major component in anti-rust coatings, it enhances both the reactivity with impurities and the film's density, thereby improving both anti-rust performance and adhesion. Commercially available zinc oxalate, however, is granular and cannot achieve the same anti-rust effect as the zinc oxalate of this invention. Furthermore, mixing zinc oxide and oxalic acid at room temperature results in a low degree of reaction, also failing to achieve the same anti-rust effect.

[0078] (4) In Example 3, the reaction molar ratio of nano zinc oxide and oxalic acid exceeded the preferred range, that is, the nano zinc oxide was in excess, exceeding the coordination amount of oxalate. As a result, the uniformity of the microstructure of the obtained zinc oxalate decreased, and the rust prevention performance of the final coating also decreased.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing an anti-rust coating, characterized in that, Includes the following steps: (1) Preparation of zinc oxide Sodium hydroxide was added to an aqueous solution of zinc acetate and dispersed evenly. The solution was then reacted in a hydrothermal reactor at 160-180 °C for 8-14 h to obtain nano-zinc oxide with a flower cluster structure. The molar ratio of sodium hydroxide to zinc acetate was (2-5):

10. (2) Preparation of zinc oxalate The nano zinc oxide obtained in step (1) is prepared into an aqueous solution, oxalic acid is added, and the solution is reacted in a hydrothermal reactor at 140-160 °C for 10-14 h to obtain an aqueous solution of zinc oxalate. (3) Prepare the coating Acrylic emulsion and additives are added to the zinc oxalate aqueous solution obtained in step (2) to prepare an anti-rust coating.

2. The method for preparing an anti-rust coating according to claim 1, characterized in that, Step (1) The concentration of the zinc acetate aqueous solution is 0.05-0.08 mol / L.

3. A method for preparing an anti-rust coating according to claim 1 or 2, characterized in that, The reaction time for step (1) is 11-13 h.

4. The method for preparing an anti-rust coating according to claim 1, characterized in that, In step (2), the molar ratio of nano zinc oxide to oxalic acid is (1.7-2):

1.

5. A method for preparing an anti-rust coating according to claim 1 or 4, characterized in that, In step (2), the concentration of the nano zinc oxide aqueous solution is 2-4 mol / L.

6. The method for preparing an anti-rust coating according to claim 1, characterized in that, The additives in step (3) include one or more of the following: thickeners, wetting agents, defoamers, formulations, and film-forming aids.

7. The method for preparing an anti-rust coating according to claim 6, characterized in that, Step (3) includes: 1) Add thickener to zinc oxalate aqueous solution and stir, then add wetting agent and stir, then add defoamer and stir; 2) Add the formulation to the system in 1) and stir; 3) Add acrylic emulsion, defoamer II, and film-forming aid to the system in 2) and stir to obtain rust-preventive coating.

8. A method for preparing an anti-rust coating according to claim 6 or 7, characterized in that, The mass fractions of each component are as follows: 20-33 parts zinc oxalate aqueous solution, 0.1-0.3 parts thickener, 0.3-0.5 parts wetting agent, 0.1-0.3 parts defoamer one, 9-11 parts bulk preparation, 50-70 parts acrylic emulsion, 0.1-0.3 parts defoamer two, and 0.1-0.3 parts film-forming aid.

9. A method for preparing an anti-rust coating according to claim 7, characterized in that, The stirring speed for step 1) is 800-1000 r / min, and the stirring time for each step is 8-12 min; the stirring speed for step 2) is 1800-2200 r / min, and the stirring time is 20-30 min; the stirring speed for step 3) is 800-1000 r / min.

10. The anti-rust coating prepared by any one of the preparation methods described in claims 1-9, characterized in that, It consists of zinc oxalate, acrylic emulsion, and additives.

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