High bond energy rare earth nanometer coating, preparation method and application thereof

Abstract

This invention relates to the field of coating technology and discloses a high-bonding-energy rare-earth nano-coating, its preparation method, and its application. The coating of this invention comprises 35-52 parts by weight of silica, 12-23 parts by weight of hydroxide, 0.3-0.8 parts by weight of lanthanum complex, and 26-34 parts by weight of filler, etc. The lanthanum complex tightly bonds the metal substrate to the silicate coating, improving the bonding energy and adhesion strength between the coating and the metal substrate, making the coating less prone to peeling. The lanthanum complex contains phthalonitrile groups. During high-temperature heat treatment, phthalonitrile undergoes self-crosslinking and cyclization to generate phthalocyanine and other aromatic heterocyclic structures with high-temperature resistance, which is beneficial to improving the heat resistance of the coating. Simultaneously, the formed chemical crosslinking system enhances the crosslinking degree within the silicate coating, inhibiting the entry of corrosive media such as acids and alkalis into the coating matrix, and improving the coating's resistance to acid and alkali corrosion.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a high-bonding-energy rare-earth nano-coating, its preparation method, and its application. Background Technology

[0002] When metal materials interact chemically with media such as water, acids, and alkalis, corrosion occurs, which greatly affects the performance of the metal materials. Metal corrosion leads to the waste of resources and energy and causes huge losses to the national economy. The development of high-performance metal anti-corrosion coatings is a research hotspot. Traditional coatings are mainly organic resin coatings, but they have poor high-temperature resistance, high VOC emissions, and poor resistance to salt spray and acid and alkali corrosion, which limits their practical application.

[0003] Inorganic ceramic coatings, such as silicate coatings, carbide coatings, and alumina coatings, possess excellent high-temperature resistance, corrosion resistance, and mechanical strength, and are widely used in aerospace, chemical metallurgy, and machinery manufacturing. Silicate coatings, in particular, are inexpensive, have good wear resistance, excellent weather resistance, and strong fire retardancy. Patent application CN118993094A discloses a method for preparing rare earth silicates, which involves mixing and reacting rare earth salt solutions, alkaline solutions, and silicon dioxide, followed by calcination to obtain rare earth silicates, which can be applied to thermal barrier coating materials and ceramic materials. However, silicate coatings exhibit low interfacial bonding strength with metal substrates, poor adhesion, and are prone to peeling, thus affecting the coating's anti-corrosion performance. Summary of the Invention

[0004] (I) Technical problem to be solved: In view of the shortcomings of the existing technology, the present invention provides a method for preparing and applying a high bonding energy rare earth nano-coating, which solves the problem of low bonding strength between inorganic silicate coatings and metal substrates.

[0005] (II) The technical solution of the present invention is: a rare earth nano-coating with high bonding energy, comprising 35-52 parts by weight of silicon dioxide, 12-23 parts by weight of hydroxide, 0.3-0.8 parts by weight of lanthanum complex, 26-34 parts by weight of filler, and 0.3-0.6 parts by weight of dispersant.

[0006] The preparation method of high bonding energy rare earth nano-coatings is as follows: (1) In an ice bath, add cyanuric chloride, 3,4-dicyanophenol, sodium carbonate and water to acetone and stir for 2-3 hours. Then add disodium iminodiacetate, sodium carbonate and water, heat to 45-50℃, stir and reflux for 4-6 hours, then heat to 90-95℃ and stir for 12-18 hours. Remove acetone by rotary evaporation, add hydrochloric acid to adjust pH to 2-3, filter and recrystallize the precipitate in water to obtain 2,4-bis(iminodiacetate)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine.

[0007] (2) Add lanthanum chloride and 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine to an aqueous ethanol solution, heat to 50-65℃, stir for 2-3 hours, filter, wash the product with ice water and ethanol, and dry to obtain lanthanum complex.

[0008] (3) Add silicon dioxide and lanthanum complex to water, stir and disperse, add hydroxide, heat to 80-95℃, stir and react for 30-60 min, cool and add filler and dispersant, disperse in a shearing machine to obtain high bonding energy rare earth nano coating.

[0009] Preferably, the hydroxide is sodium hydroxide or potassium hydroxide.

[0010] Preferably, the filler is one or more of zinc powder, aluminum powder, nano titanium dioxide, nano zinc oxide, and nano aluminum oxide.

[0011] Preferably, the dispersant is one or more of sodium pyrophosphate, sodium tripolyphosphate, and sodium hexametaphosphate.

[0012] Preferably, the ratio of cyanuric chloride, 3,4-dicyanophenol, sodium carbonate, and disodium iminodiacetic acid in (1) is 1 mol: 1 mol: (3-3.3) mol: (2-2.2) mol.

[0013] Preferably, in (2), the ratio of lanthanum chloride to 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine is 1 mol: (1.6-2.4) mol.

[0014] Preferably, high-bonding-energy rare-earth nanocoatings are used in metal corrosion protection.

[0015] (III) Beneficial Technical Effects: In this invention, a lanthanum complex is added during the reaction of silicon dioxide and hydroxide to form silicates. Lanthanum can regulate the silicate network structure, forming stable Si-O-La bonds, and controllably synthesizing highly active silicate materials as the film-forming matrix for the coating, laying the foundation for high bonding energy. Simultaneously, the lanthanum complex contains a large number of carboxyl groups, forming coordination bonds with metal substrates such as tinplate, thereby tightly bonding the metal substrate to the silicate coating through the lanthanum complex, further improving the bonding energy and adhesion strength between the coating and the metal substrate, making the coating less prone to peeling off.

[0016] The lanthanum complex of the present invention contains phthalonitrile groups. During high-temperature heat treatment, phthalonitrile undergoes self-crosslinking and cyclization to generate aromatic heterocyclic structures such as phthalocyanine with high-temperature resistance, which is beneficial to improving the heat resistance of the coating. At the same time, the chemical crosslinking system formed can enhance the cohesion of the coating, improve the bonding strength, and enhance the degree of crosslinking inside the silicate coating, inhibiting corrosive media such as acids and alkalis from entering the coating matrix, thereby improving the acid and alkali corrosion resistance of the coating. Detailed Implementation

[0017] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the application will be further described in detail below with reference to embodiments. However, this should not be construed as limiting the scope of this application to the following examples. All other embodiments obtained by those skilled in the art without creative effort without departing from the above-described methodological spirit of this application are within the scope of protection of this application.

[0018] Example 1 (1) In an ice bath, 10 mmol of cyanuric chloride, 10 mmol of 3,4-dicyanophenol, 10 mmol of sodium carbonate, and 30 mL of water were added to 20 mL of acetone and stirred for 2 h. Then, 20 mmol of disodium iminodiacetate, 20 mmol of sodium carbonate, and 40 mL of water were added. The mixture was heated to 45 °C and stirred under reflux for 6 h. Then, it was heated to 95 °C and stirred for 12 h. The acetone was removed by rotary evaporation. The pH was adjusted to 2 by adding hydrochloric acid. After filtration, the precipitate was recrystallized in water to obtain 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine. The preparation reaction formula is: .

[0019] (2) Add 5 mmol of lanthanum chloride heptahydrate and 12 mmol of 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine to 60 mL of 30% ethanol aqueous solution, heat to 50 °C, stir for 3 h, filter, wash the product with ice water and ethanol, and dry to obtain lanthanum complex.

[0020] (3) Add 460g of silica micro powder and 3g of lanthanum complex to 800mL of water, stir and disperse, add 170g of sodium hydroxide, heat to 85℃, stir and react for 60min, cool and add 170g of zinc powder, 110g of aluminum powder, 19g of nano titanium dioxide (average particle size of 80nm, the same below), 11g of nano alumina (average particle size of 500nm, the same below), and 5g of sodium hexametaphosphate, disperse in a shearing machine to obtain a high bonding energy rare earth nano coating.

[0021] Example 2 (1) In an ice bath, 10 mmol of cyanuric chloride, 10 mmol of 3,4-dicyanophenol, 10 mmol of sodium carbonate and 40 mL of water were added to 20 mL of acetone and stirred for 3 h. Then, 20 mmol of disodium iminodiacetate, 20 mmol of sodium carbonate and 40 mL of water were added, heated to 50 °C, stirred and refluxed for 4 h, then heated to 90 °C and stirred for 18 h. The acetone was removed by rotary evaporation, and the pH was adjusted to 3 by adding hydrochloric acid. After filtration, the precipitate was recrystallized in water to obtain 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine.

[0022] (2) Add 5 mmol of lanthanum chloride heptahydrate and 10 mmol of 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine to 80 mL of 20% ethanol aqueous solution, heat to 60 °C, stir for 3 h, filter, wash the product with ice water and ethanol, and dry to obtain lanthanum complex.

[0023] (3) Add 350g of silica micro powder and 4.5g of lanthanum complex to 850mL of water, stir and disperse, add 120g of potassium hydroxide, heat to 80℃, stir and react for 60min, cool and add 170g of zinc powder, 120g of aluminum powder, 32g of nano titanium dioxide, 18g of nano zinc oxide (average particle size 200nm, the same below) and 5g of sodium hexametaphosphate, disperse in a shearing machine to obtain a high bonding energy rare earth nano coating.

[0024] Example 3 (1) 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine was prepared according to the method of Example 1.

[0025] (2) Add 5 mmol of lanthanum chloride heptahydrate and 8 mmol of 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine to 60 mL of 35% ethanol aqueous solution, heat to 60 °C, stir for 3 h, filter, wash the product with ice water and ethanol, and dry to obtain lanthanum complex.

[0026] (3) Add 520g of silica micro powder and 6g of lanthanum complex to 800mL of water, stir and disperse, add 230g of sodium hydroxide, heat to 90℃, stir and react for 40min, cool and add 130g of zinc powder, 90g of aluminum powder, 25g of nano titanium dioxide, 15g of nano zinc oxide and 3g of sodium tripolyphosphate, disperse in a shearing machine to obtain a high bonding energy rare earth nano coating.

[0027] Example 4 (1) 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine was prepared according to the method of Example 1.

[0028] (2) Add 5 mmol of lanthanum chloride heptahydrate and 10 mmol of 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine to 80 mL of 20% ethanol aqueous solution, heat to 65 °C, stir for 2 h, filter, wash the product with ice water and ethanol, and dry to obtain lanthanum complex.

[0029] (3) Add 430g of silica micro powder and 8g of lanthanum complex to 800mL of water, stir and disperse, add 156g of sodium hydroxide, heat to 95℃, stir and react for 30min, cool and add 160g of zinc powder, 100g of aluminum powder, 20g of nano titanium dioxide, 10g of nano alumina and 6g of sodium pyrophosphate, disperse in a shearing machine to obtain a high bonding energy rare earth nano coating.

[0030] Comparative Example 1 (1) Add 460g of silica micro powder and 3g of lanthanum chloride to 800mL of water, stir and disperse, add 170g of sodium hydroxide, heat to 85℃, stir and react for 60min, cool and add 170g of zinc powder, 110g of aluminum powder, 19g of nano titanium dioxide, 11g of nano alumina and 5g of sodium hexametaphosphate, disperse in a shearing machine to obtain nano coating.

[0031] Comparative Example 2 (1) 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine was prepared according to the method of Example 1.

[0032] (2) Add 460g of silica micro powder and 3g of 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine to 800mL of water, stir and disperse, add 170g of sodium hydroxide, heat to 85℃, stir and react for 60min, cool and add 170g of zinc powder, 110g of aluminum powder, 19g of nano titanium dioxide, 11g of nano alumina and 5g of sodium hexametaphosphate, disperse in a shearing machine to obtain nano coating.

[0033] Comparative Example 3 (1) In an ice bath, 10 mmol of cyanuric chloride, 10 mmol of phenol, 10 mmol of sodium carbonate, and 30 mL of water were added to 20 mL of acetone and stirred for 2 h. Then, 20 mmol of disodium iminodiacetate, 20 mmol of sodium carbonate, and 40 mL of water were added. The mixture was heated to 45 °C and stirred under reflux for 6 h. The mixture was then heated to 95 °C and stirred for 12 h. The acetone was removed by rotary evaporation, and the pH was adjusted to 2 by adding hydrochloric acid. After filtration, the precipitate was recrystallized in water to obtain 2,4-bis(iminodiacetate)-6-phenoxy-1,3,5-triazine, with the structural formula [insert structural formula here]. .

[0034] (2) Add 5 mmol of lanthanum chloride heptahydrate and 12 mmol of 2,4-bis(iminodiacetic acid)-6-phenoxy-1,3,5-triazine to 60 mL of 30% ethanol aqueous solution, heat to 50 °C, stir for 3 h, filter, wash the product with ice water and ethanol, and dry to obtain lanthanum complex.

[0035] (3) Add 460g of silica micro powder and 3g of lanthanum complex to 800mL of water, stir and disperse, add 170g of sodium hydroxide, heat to 85℃, stir and react for 60min, cool and add 170g of zinc powder, 110g of aluminum powder, 19g of nano titanium dioxide, 11g of nano alumina and 5g of sodium hexametaphosphate, disperse in a shearing machine to obtain nano coating.

[0036] The coating is applied to the surface of the tinplate and then heat-treated sequentially at 120℃ for 30 min, 180℃ for 2 h, 260℃ for 2 h, and 350℃ for 30 min to form a coating.

[0037] The adhesive strength of the coating was tested according to ASTM C-633.

[0038] The high-temperature oxidation resistance of the coating was tested using the oxidation weight gain method. The coating sample was weighed (m0), placed in a muffle furnace, and kept at 400℃ for 7 days. The coating sample was then removed, cooled to room temperature, and weighed (m1). The oxidation weight gain Δm = m1 - m0. The smaller the Δm, the better the high-temperature oxidation resistance.

[0039] The corrosion resistance of the coating was tested using the corrosion loss method. The coating sample was weighed (M0) and suspended in 65% concentrated nitric acid and 40% sodium hydroxide aqueous solution for 7 days. The coating sample was then removed, washed with water, dried, and weighed (M1). The corrosion change ΔM = M0 - M1. The smaller the ΔM, the better the corrosion resistance.

[0040] Table 1 Performance of the coating After testing, compared with Comparative Examples 1-3, Example 1 showed higher bonding strength, lower oxidation weight gain, and lower corrosion changes from nitric acid and sodium hydroxide. It exhibited better adhesion, high-temperature oxidation resistance, and acid and alkali corrosion resistance. This was mainly due to the addition of lanthanum complex. When silica and hydroxide react to form silicates, lanthanum can regulate the silicate network structure, forming stable Si-O-La bonds. This allows for the controllable synthesis of highly active silicates as the film-forming matrix for the coating, laying the foundation for high bonding energy. Meanwhile, the lanthanum complex contains a large number of carboxyl groups, which form coordination bonds with metal substrates such as tinplate, thereby tightly bonding the metal substrate to the silicate coating through the lanthanum complex. This further improves the bonding energy and adhesion strength between the coating and the metal substrate. Furthermore, the lanthanum complex contains phthalonitrile groups, which, during high-temperature heat treatment, undergo self-crosslinking and cyclization to generate aromatic heterocyclic structures such as phthalocyanines with high-temperature resistance, which is beneficial for improving the heat resistance of the coating. Simultaneously, the formed chemical crosslinking system can enhance the cohesive force of the coating, improve the adhesion strength, and increase the degree of crosslinking within the silicate coating, inhibiting the entry of corrosive media such as acids and alkalis into the coating matrix, thereby improving the coating's resistance to acid and alkali corrosion. Examples 2-4, by adjusting different amounts of raw materials such as silica, hydroxide, and lanthanum complex, also prepared silicate coatings with excellent adhesion, high-temperature oxidation resistance, and acid and alkali corrosion resistance.

[0041] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A high-bonding-energy rare-earth nano-coating, characterized in that, The coating comprises 35-52 parts by weight of silica, 12-23 parts by weight of hydroxide, 0.3-0.8 parts by weight of lanthanum complex, 26-34 parts by weight of filler, and 0.3-0.6 parts by weight of dispersant; The lanthanum complex was prepared as follows: Lanthanum chloride and 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine were added to an aqueous ethanol solution, the mixture was stirred and reacted, then filtered, the product was washed, and dried to obtain the lanthanum complex.

2. The high bonding energy rare earth nano-coating according to claim 1, characterized in that, The hydroxide is sodium hydroxide or potassium hydroxide.

3. The high bonding energy rare earth nano-coating according to claim 1, characterized in that, The filler is one or more of zinc powder, aluminum powder, nano titanium dioxide, nano zinc oxide, and nano aluminum oxide.

4. The high bonding energy rare earth nanocoating according to claim 1, characterized in that, The dispersant is one or more of sodium pyrophosphate, sodium tripolyphosphate, and sodium hexametaphosphate.

5. The high bonding energy rare earth nano-coating according to claim 1, characterized in that, The reaction is carried out at a temperature of 50-65℃ for 2-3 hours.

6. The high bonding energy rare earth nanocoating according to claim 1, characterized in that, The ratio of lanthanum chloride to 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine is 1 mol: (1.6-2.4) mol.

7. The high bonding energy rare earth nanocoating according to claim 6, characterized in that, The preparation method of 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine is as follows: In an ice bath, cyanuric chloride, 3,4-dicyanophenol, sodium carbonate, and water are added to acetone and stirred for 2-3 hours. Then, disodium iminodiacetic acid, sodium carbonate, and water are added, and the mixture is heated to 45-50°C and stirred under reflux for 4-6 hours. The mixture is then heated to 90-95°C and stirred for 12-18 hours. The acetone is removed by rotary evaporation, and hydrochloric acid is added dropwise to adjust the pH to 2-3. After filtration, the precipitate is recrystallized to obtain 2,4-bis(iminodiacetic acid)-6-(4-phenoxyphthalonitrile)-1,3,5-triazine.

8. The high bonding energy rare earth nano-coating according to claim 7, characterized in that, The ratio of cyanuric chloride, 3,4-dicyanophenol, sodium carbonate, and disodium iminodiacetic acid is 1 mol: 1 mol: (3-3.3) mol: (2-2.2) mol.

9. A method for preparing a high-bonding-energy rare-earth nano-coating as described in any one of claims 1-8, characterized in that, The preparation method is as follows: add silicon dioxide and lanthanum complex to water, stir and disperse, add hydroxide, heat to 80-95℃, stir and react for 30-60 minutes, cool and add filler and dispersant, disperse in a shearing machine to obtain high bonding energy rare earth nano-coating.

10. The application of a high-bonding-energy rare-earth nanocoating obtained by the preparation method as described in claim 9 in metal corrosion protection.

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