Environment-friendly anticorrosive coating for aluminum alloy parts

Abstract

The present application relates to the technical field of paint, in particular to an environment-friendly anticorrosive paint for aluminum alloy parts. Carbon nanotubes are prone to agglomeration in water-based paint systems. The anticorrosive performance of water-based paint using carbon nanotubes as anticorrosive additives needs to be further improved. In view of the above problems, the present application provides an environment-friendly anticorrosive paint for aluminum alloy parts. The arginine-modified sulfonated carbon nanotubes added in the anticorrosive paint have the following advantages: compared with traditional gas-phase corrosion inhibitors, the high specific surface area of nanomaterials can anchor and adsorb arginine, slowly release small amine molecules into the atmosphere, thereby improving the anticorrosive performance and prolonging the corrosion resistance time. Meanwhile, the introduction of two-dimensional nanometer zirconium phosphate sheets in the paint system can further increase the anticorrosive effect of the coating through the covering effect. The two-dimensional nanometer zirconium phosphate and the one-dimensional carbon nanotubes synergistically build an anticorrosive covering network, further improving the anticorrosive performance of the coating.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to an environmentally friendly anti-corrosion coating for aluminum alloy parts. Background Technology

[0002] Nanomaterials have found wide application in corrosion and fire protection technologies due to their unique physicochemical properties. Their high surface area and surface energy allow them to form a dense protective layer on material surfaces, effectively preventing the penetration of corrosive media. Furthermore, nanomaterials exhibit good dispersibility in coatings, forming a strong bond with the substrate and significantly improving the durability and protective performance of the coating.

[0003] Carbon nanotubes (CNTs) exhibit significant advantages in corrosion protection due to their excellent mechanical strength, electrical conductivity, and chemical stability. CNTs can form a network structure in coatings, enhancing their mechanical properties and durability. Furthermore, the high electrical conductivity of CNTs helps improve the antistatic and anti-corrosion properties of coatings. However, CNTs are prone to aggregation in coating systems, resulting in poor dispersion and significantly affecting their effective performance.

[0004] Arginine is an amino acid compound with a high concentration of nitrogen atoms and amino groups, and has the potential to become an inhibitor of vapor phase corrosion (VCI). Since pure arginine molecules are amino acid substances, they are prone to deterioration in atmospheric environment. Therefore, the use of arginine derivatives is expected to become an inhibitor of VCI vapor phase corrosion and be applied in the field of corrosion prevention. Summary of the Invention

[0005] A problem with existing technologies is that carbon nanotubes tend to aggregate in water-based coating systems, thus the corrosion resistance of the resulting water-based coatings needs further improvement. To address this issue, this invention provides an environmentally friendly anti-corrosion coating for aluminum alloy parts, comprising the following components by weight:

[0006] Water-based latex liquid 20-30;

[0007] Arginine-modified sulfonated carbon nanotubes 10-50;

[0008] Zirconium phosphate nanosheets 10-50;

[0009] 10-50 g / g of spherical zinc powder;

[0010] Hydroxyethyl cellulose 0.5-1;

[0011] Ethylene glycol methyl ether 0.5-1;

[0012] Propylene glycol butyl ether 0.5-1;

[0013] Dispersant 0.5-1;

[0014] Defoamer 0.5-1;

[0015] Octyl alcohol 0.5-1;

[0016] Water 15-18.

[0017] Preferably, an environmentally friendly anti-corrosion coating for aluminum alloy parts comprises, by weight, the following components:

[0018] Water-based latex liquid 20;

[0019] Arginine-modified sulfonated carbon nanotubes 20-30;

[0020] Zirconium phosphate nanosheets 10-30;

[0021] 20g of spherical zinc powder;

[0022] Hydroxyethyl cellulose 0.5-1;

[0023] Ethylene glycol methyl ether 1;

[0024] Propylene glycol butyl ether 0.5;

[0025] Dispersant 0.5;

[0026] Defoamer 0.5g;

[0027] 0.5g of n-octanol;

[0028] Water 15-18.

[0029] Preferably, the solid content of the aqueous latex is 30-55%, and the coagulation rate is 0.1-2%.

[0030] Preferably, the aqueous latex includes aqueous acrylic emulsion, aqueous methacrylate emulsion, aqueous styrene-acrylic emulsion, or aqueous styrene-acrylic core-shell emulsion.

[0031] Preferably, the preparation method of the arginine-modified sulfonated carbon nanotubes is as follows:

[0032] Arginine and sulfonated carbon nanotubes were added to a mixed solution of ethanol and water at a volume ratio of 50-100:100-50 and a mass ratio of 50-100:50-100, respectively. The mass concentration of arginine in the mixed solution was 10wt%-50wt%. The mixture was stirred and ultrasonically reacted at 50-100℃ for 12-48 hours. Subsequently, DC5700 solution was added to the reaction system, and the mixture was stirred and ultrasonically reacted at 50-100℃ for 12-48 hours. After the reaction was completed, the obtained reaction solution was subjected to solid-liquid separation. The obtained solid product was washed with tetrahydrofuran and then dried to obtain arginine-modified sulfonated carbon nanotubes. The mass ratio of DC5700 solution to arginine added to the reaction system was 50-100:50-100.

[0033] Preferably, the sulfonated carbon nanotubes have an average particle size of 10-20 nm and a length of 500-1000 nm.

[0034] Preferably, the DC5700 solution is octadecyl dimethylsilyl ammonium chloride dissolved in anhydrous methanol, with a mass concentration of 40-60 wt%.

[0035] Preferably, the zirconium phosphate nanosheets have an average particle size of 100-300 nm and a diameter of 1000-1500 nm.

[0036] Preferably, the preparation method of the environmentally friendly anti-corrosion coating for aluminum alloy parts includes the following steps:

[0037] (1) According to the formula amount, arginine-modified sulfonated carbon nanotubes, zirconium phosphate nanosheets, spherical zinc powder and hydroxyethyl cellulose are mixed evenly and ground until there are no particles. Then water is added and stirred and ground until uniform and there are no obvious particles. Then defoamer and dispersant are added and stirred and ground evenly.

[0038] (2) Finally, add the remaining amount of raw materials to the reaction system obtained in step (1), grind and mix evenly to obtain the final product. This invention has the following beneficial effects:

[0039] (1) The anti-corrosion coating obtained by the present invention has good anti-corrosion and fireproof properties, good weather resistance, and long service life;

[0040] (2) Compared with traditional vapor phase corrosion inhibitors, the arginine-modified sulfonated carbon nanotubes added to the anti-corrosion coating obtained by the present invention can anchor and adsorb arginine with high specific surface area nanomaterials, which can slowly release amine molecules into the atmosphere, thereby improving the anti-corrosion performance and extending the corrosion resistance time. Moreover, the introduction of carbon nanotubes also helps to improve the conductivity of the coating and reduce its impedance, and the synergistic effect further improves the anti-corrosion performance of the coating.

[0041] (3) The introduction of two-dimensional nano-zirconium phosphate sheets into the coating system can further enhance the anti-corrosion effect of the coating through the coverage effect. The two-dimensional nano-zirconium phosphate works in synergy with one-dimensional carbon nanotubes to build an anti-corrosion coverage network, which helps to further reduce the release of amine molecules into the air, thereby further improving the anti-corrosion performance of the coating. Attached Figure Description

[0042] Figure 1 The images shown are Nyquist spectra of the coatings obtained in Example 1 and Comparative Example 3 after being immersed in a 3.5% NaCl aqueous solution for 7 days.

[0043] Figure 2 The images shown are Bode spectra of the coatings obtained in Example 1 and Comparative Example 3 after being immersed in a 3.5% NaCl aqueous solution for 7 days.

[0044] Figure 3 : These are surface microstructure images of Example 1 (Figure a) and Comparative Example 3 (Figure b) after salt spray corrosion experiments. Detailed Implementation

[0045] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0046] The sulfonated carbon nanotubes in the following embodiments of the present invention have an average particle size of 20 nm and a length of 500 nm, and were purchased from Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences.

[0047] The zirconium phosphate nanosheets in the following embodiments of the present invention have an average particle size of 300 nm and a diameter of 1000 nm, and were purchased from Aladdin Reagent (Shanghai) Co., Ltd.

[0048] The spherical zinc powder in the following embodiments of the present invention was purchased from Guangdong Haozhisheng New Materials Co., Ltd., and has an average particle size of 5 μm.

[0049] In the following embodiments of the present invention, the arginine is L-arginine.

[0050] In the following embodiments of the present invention, the dispersant used is wetting and dispersing agent 5040, and the defoamer is silicone defoamer 470.

[0051] The aqueous latex in the following embodiments of the present invention is a core-shell structured aqueous acrylic ester-based emulsion, and the preparation method is as follows:

[0052] (1) Dissolve 1.0g alkylphenol polyoxyethylene ether and 2.0g sodium dodecyl sulfate in 90mL of deionized water to prepare an emulsifier aqueous solution, and divide it into three portions of 35mL, 30mL and 25mL;

[0053] (2) Add 50g of n-butyl acrylate and 10g of methyl methacrylate to 35mL of emulsifier aqueous solution, stir and mix at room temperature, pre-emulsify for 1h to obtain the core pre-emulsion;

[0054] (3) Add 10g of n-butyl acrylate, 30g of methyl methacrylate and 2.4g of methacrylic acid to 30mL of emulsifier aqueous solution, stir and mix at room temperature, pre-emulsify for 2h to obtain shell pre-emulsion;

[0055] (4) Dissolve 0.3g of sodium bicarbonate in 25mL of emulsifier aqueous solution and stir to dissolve to obtain buffer aqueous solution; add 0.5g of potassium persulfate to 30mL of deionized water and stir to dissolve to obtain initiator aqueous solution;

[0056] (5) In the reaction vessel, while stirring, add the buffer aqueous solution, 1 / 3 volume of the initiator aqueous solution and 1 / 2 volume of the nuclear pre-emulsion in sequence, heat to 70°C, and when a large amount of blue light appears in the emulsion, keep it at the temperature for 0.5 h to obtain the seed emulsion;

[0057] (3) When the seed emulsion is kept warm, slowly drip the remaining pre-emulsion of the kernel and 1 / 3 of the initiator aqueous solution into the seed emulsion, and finish dripping them all within 1 hour. Control the temperature to 80°C and keep warm for 0.5 hours to obtain the kernel layer emulsion.

[0058] (4) When the core layer emulsion is kept warm, add the remaining initiator aqueous solution and the formula amount of shell pre-emulsion, and finish adding it within 1.5h. Then raise the temperature to 85℃ and keep it warm for 0.5h. Then cool it naturally to 40℃, adjust the pH value to 8, and pass it through a 200-mesh sieve to obtain an acrylic ester-based emulsion (core-shell structure) with a solid content of 41% and a coagulation rate of 0.34%.

[0059] The arginine-modified sulfonated carbon nanotubes in the following embodiments of the present invention are prepared by the following method:

[0060] Arginine and sulfonated carbon nanotubes were added to a mixed solution of ethanol and water at a mass ratio of 50:100 (1:1). The arginine concentration in the mixed solution was 13 wt%. After thorough mixing, the mixture was ultrasonically reacted at 80°C for 12 hours with an ultrasonic power of 200 W. Subsequently, a DC5700 solution with a mass ratio of 50:64 to arginine was added, and the mixture was ultrasonically reacted again for 12 hours with an ultrasonic power of 200 W. After the reaction was completed, the mixture was centrifuged at 6000 rpm. The obtained solid product was washed with tetrahydrofuran and dried at 80°C to obtain the final product. The DC5700 solution was prepared by dissolving octadecyldimethylsilylammonium chloride in anhydrous methanol, with a mass concentration of 60 wt%. Example

[0061] An environmentally friendly anti-corrosion coating for aluminum alloy parts, with the following composition by weight:

[0062] Water-based latex liquid 20;

[0063] Arginine-modified sulfonated carbon nanotubes 20;

[0064] Zirconium phosphate nanosheets 20;

[0065] 20g of spherical zinc powder;

[0066] Hydroxyethyl cellulose 0.5;

[0067] Ethylene glycol methyl ether 1;

[0068] Propylene glycol butyl ether 0.5;

[0069] Dispersant 0.5;

[0070] Defoamer 0.5g;

[0071] 0.5g of n-octanol;

[0072] Water 17.

[0073] Example 2 is the same as Example 1, except that the anti-corrosion coating in Example 2 has the following composition by mass ratio:

[0074] Water-based latex liquid 20;

[0075] Arginine-modified sulfonated carbon nanotubes 30;

[0076] Zirconium phosphate nanosheets 10;

[0077] 20g of spherical zinc powder;

[0078] Hydroxyethyl cellulose 1;

[0079] Ethylene glycol methyl ether 1;

[0080] Propylene glycol butyl ether 0.5;

[0081] Dispersant 0.5;

[0082] Defoamer 0.5g;

[0083] 0.5g of n-octanol;

[0084] Water 15.

[0085] Example 3 is the same as Example 1, except that the anti-corrosion coating in Example 3 has the following composition by mass ratio:

[0086] Water-based latex liquid 20;

[0087] Arginine-modified sulfonated carbon nanotubes 30;

[0088] Zirconium phosphate nanosheets 30;

[0089] 20g of spherical zinc powder;

[0090] Hydroxyethyl cellulose 0.5;

[0091] Ethylene glycol methyl ether 1;

[0092] Propylene glycol butyl ether 0.5;

[0093] Dispersant 0.5;

[0094] Defoamer 0.5g;

[0095] 0.5g of n-octanol;

[0096] Water 18.

[0097] Comparative Example 1 is the same as Example 1, except that no zirconium phosphate nanosheets were added in Comparative Example 1.

[0098] Comparative Example 2 is the same as Example 1, except that the mass fraction of spherical zinc powder added in Comparative Example 2 is 40.

[0099] Comparative Example 3 is the same as Example 1, except that Comparative Example 3 uses the same amount of arginine-modified carbon nanotubes instead of the arginine-modified sulfonated carbon nanotubes in Example 1. The arginine-modified carbon nanotubes are prepared according to the method disclosed in Example 1 of Chinese Invention Patent CN 116082869 A.

[0100] One part by mass of carbon nanotubes was dispersed in a mixture of 100 parts by mass of water and ethanol in a mass ratio of 10:1. The pH was then adjusted to 1 using hydrochloric acid. Ten parts by mass of arginine were added to the reaction system, and the mixture was refluxed at 60°C for 1 hour. After filtration and drying, arginine-modified carbon nanotubes were obtained.

[0101] Performance testing

[0102] The anti-corrosion coatings obtained in Examples 1-3 and Comparative Examples 1-3 of the present invention were subjected to relevant performance tests, and the test results are shown in Table 1.

[0103] Salt spray corrosion resistance: Tested according to the national standard GB / T 10125-2021. A 5% sodium chloride solution was used, the salt spray temperature was 35±2℃, and the test sample was placed at an angle of 15° to 30°. The test duration was 72 hours.

[0104] Storage stability: After standing at room temperature, observe and record the time (in months) it takes for the paint to begin to separate.

[0105] Surface morphology after salt spray corrosion: Check the rust condition of the coating surface according to the requirements of GB / T 1766-2008 "Rating method for aging of paint and varnish coatings".

[0106] The evaluation criteria are as follows:

[0107] Ri0: 0% rust area, no rust.

[0108] Ri1: 0.05% rust area, very slight rust.

[0109] Ri2: 0.5% rust area, slight rust.

[0110] Ri3: 1% rust area, obvious rust.

[0111] Ri4: 8% rust area, relatively large rust.

[0112] Ri5: 40%-50% rusted area, severely rusted.

[0113] Among them, the surface microstructure images (magnification 500x) of Example 1(a) and Comparative Example 3(b) after salt spray corrosion test are shown in the appendix to the instruction manual. Figure 3 As shown in the results, the carbon nanotube aggregates in Example 1 were significantly lower than those in Comparative Example 3, and the dispersion was more uniform.

[0114] Table 1

[0115] ,

[0116] Barrier properties were tested in Example 1 and Comparative Example 3. The coatings obtained in Example 1 and Comparative Example 3 were cured at room temperature to obtain coatings with a thickness of 500 μm. These coatings were then immersed in a 3.5% NaCl aqueous solution for 7 days, followed by electrochemical impedance spectroscopy characterization. The test results are shown in the appendix to the specification. Figure 1 Included with instruction manual Figure 2 As shown.

[0117] In the Nyquist plot, a larger radius of the capacitive arc in the high-frequency region indicates better barrier properties of the coating, corresponding to better corrosion resistance. (See attached instruction manual.) Figure 1 As shown, the order of the high-frequency region capacitance arc radius is that Example 1 is larger than Comparative Example 3, indicating that the shielding performance of the coating obtained in Example 1 is better than that in Comparative Example 3.

[0118] In Bode spectra, the low-frequency impedance modulus (|Z| 0.01 Hz) in electrochemical impedance spectroscopy is a semi-quantitative indicator of the penetration of corrosive media (water, oxygen, and chloride ions, etc.) by the corresponding coating. A higher impedance modulus indicates stronger penetration performance of the corresponding shielding corrosive material. (See attached instruction manual.) Figure 2 As shown, the low-frequency impedance modulus of the coating obtained in Example 1 is obviously greater than that in Comparative Example 3, and therefore its shielding effect against corrosive media is better.

[0119] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. An environmentally friendly anti-corrosion coating for aluminum alloy parts, characterized in that, By mass ratio, comprising the following components: Water-based latex 20-30; Arginine modified sulfonated carbon nanotubes 10-50; Zirconium phosphate nanosheets 10-50; Spherical zinc powder 10-20; Hydroxyethyl cellulose 0.5-1; Ethylene glycol methyl ether 0.5-1; Propylene glycol butyl ether 0.5-1; Dispersing agent 0.5-1; Defoaming agent 0.5-1; n-Octanol 0.5-1; Water 15-18; The preparation method of the arginine modified sulfonated carbon nanotubes is as follows: In a mixed solution formed by ethanol and water in a volume ratio of 50-100:100-50, arginine and sulfonated carbon nanotubes are added in a mass ratio of 50-100:50-100, the mass concentration of the arginine in the mixed solution is 10-50wt%, then the reaction is stirred and ultrasonically treated at a temperature of 50-100℃ for 12-48h, then DC5700 solution is added to the reaction system, and then the reaction is stirred and ultrasonically treated at a temperature of 50-100℃ for 12-48h, after the reaction is completed, the obtained reaction liquid is subjected to solid-liquid separation, the obtained solid product is washed with tetrahydrofuran, and then is dried, thereby arginine modified sulfonated carbon nanotubes are obtained, the mass ratio of the DC5700 solution to the arginine added to the reaction system is 50-100:50-100; The DC5700 solution is octadecyl dimethyl ammonium chloride dissolved in anhydrous methanol, and the mass concentration is 40-60wt%.

2. The environment-friendly anticorrosive paint for aluminum alloy parts according to claim 1, characterized in that, The solid content of the water-based latex is 30-55%, and the coagulation rate is 0.1-2%.

3. The environment-friendly anticorrosive paint for aluminum alloy parts according to claim 2, characterized in that, The water-based latex is a water-based acrylate emulsion.

4. The environment-friendly anticorrosive paint for aluminum alloy parts according to claim 1, characterized in that, The average particle size of the sulfonated carbon nanotubes is 10-20nm, and the length is 500-1000nm.

5. The environment-friendly anticorrosive paint for aluminum alloy parts according to claim 1, characterized in that, The average particle size of the zirconium phosphate nanosheets is 100-300nm, and the diameter is 1000-1500nm.

6. The environmentally friendly anticorrosive paint for aluminum alloy parts according to any one of claims 1 to 5, characterized by, The preparation method comprises the following steps: (1) The arginine modified sulfonated carbon nanotubes, zirconium phosphate nanosheets, spherical zinc powder, and hydroxyethyl cellulose are uniformly mixed according to the formula amount, ground to a particle-free powder, then water is added and stirred and ground until uniform and no obvious particulate matter exists, then the defoaming agent and the dispersing agent are added, and the stirring and grinding are continued until uniform; (2) Finally, the remaining formula amount of raw materials is added to the reaction system obtained in step (1) and is ground and mixed uniformly.

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