Preparation method of waterborne epoxy anticorrosive coating modified by amphiphilic SiO2 Janus particles

Abstract

The present application relates to the field of functional anticorrosive coating technology, and particularly relates to a preparation method of amphiphilic SiO2 Janus particle modified waterborne epoxy anticorrosive coating. The amphiphilic SiO2 Janus particle modified by a siloxane containing a hydrophobic chain and an amino group is used to modify the waterborne epoxy resin, and a waterborne anticorrosive coating with good corrosion resistance and mechanical properties is prepared. The hydrophilic side amino group of the SiO2 Janus particle is crosslinked with the waterborne epoxy resin, fills the internal defects of the coating, improves the interfacial compatibility and mechanical strength, and at the same time, introduces the hydrophobic side group of the Janus particle into the coating, effectively blocks the penetration of water molecules, and greatly improves the overall permeation resistance of the coating. After being immersed in simulated seawater for 30 days, the corrosion resistance of the SiO2 Janus particle modified coating is 2 orders of magnitude higher than that of the pure waterborne coating. The method for constructing the high corrosion resistance waterborne coating solves the shortcomings of poor water resistance, corrosion resistance and durability of the current waterborne coating, and has a wide application prospect in the field of waterborne anticorrosive coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional anticorrosive coating, and particularly relates to a preparation method of an amphiphilic SiO2 Janus particle modified waterborne epoxy anticorrosive coating. BACKGROUND

[0002] Corrosion is ubiquitous and is a common problem faced by countries around the world, and is referred to as the cancer of metal, flameless fire and hidden killer. Coating is the most commonly used method among the methods currently used to prevent, reduce or control corrosion, but volatile organic compounds (VOC) emitted into the air during the manufacture, construction, drying, curing and film formation of the coating are one of the important environmental pollutants, which pose a serious threat to human health and the environment. It is of great practical significance to use low-VOC environmentally friendly coating products to replace solvent-based coatings for anticorrosive coating. However, waterborne epoxy coatings contain hydrophilic groups, which form polar channels after curing, resulting in the formed coating being easily diffused through by water molecules, thereby reducing the anticorrosive performance. Modifying by adding hydrophobic functional materials is a relatively effective way to improve the anticorrosive performance of waterborne coatings, but the compatibility of hydrophobic functional materials with waterborne coatings is poor, which can lead to a decrease in the uniformity and compactness of the coating. Therefore, the structure and function design of the modified functional materials are a hot spot in the field of waterborne coating research.

[0003] Janus particles are particles having two or more surface regions in a single particle, which exhibit different properties and are arranged asymmetrically, and can exhibit different properties such as polarity / non-polarity, hydrophilicity / hydrophobicity, magnetism / fluorescence and positive / negative electricity in a single particle. Patent CN113980211A and CN 109233598A respectively disclose the preparation of amphiphilic SiO2 Janus microspheres and the application thereof in improving the hydrophobicity and wear resistance of leather coatings. The SiO2 Janus microsphere dispersion liquid with hydrophilic groups and hydrophobic groups is sprayed onto the polyurethane coating pre-sprayed on the surface of the leather, and the hydrophobic end is directed away from the air by the hydrophilic end to obtain superhydrophobicity and wear resistance. However, this coating preparation method uses a large amount of toxic and harmful volatile organic solvents, is not environmentally friendly, and the amphiphilic SiO2 Janus microspheres only exist on the surface of the coating matrix, and the combination with the coating matrix is very limited, which can easily destroy the rough surface structure, and therefore only short-term wear resistance and superhydrophobicity can be maintained. There is little research on the use of amphiphilic Janus particles in waterborne coatings to improve the anticorrosive performance in the prior art. How to simply design and prepare amphiphilic Janus particles to modify waterborne coatings for improving the anticorrosive performance and durability is a problem to be solved in the field.

[0004] The application prepares an amphiphilic SiO2 Janus particle modified waterborne epoxy anticorrosive coating, the hydrophilic side amino group of the SiO2 Janus particle is crosslinked and combined with the waterborne epoxy resin, the internal defects of the coating are filled, the interface compatibility and mechanical strength are improved, at the same time, the hydrophobic side group of the Janus particle is introduced into the coating, the permeation of water molecules is effectively blocked, and the overall permeation resistance of the coating is greatly improved. Further, the corrosion resistance of the waterborne epoxy coating is improved, and good mechanical stability is maintained. SUMMARY

[0005] The application aims to provide a preparation method of an amphiphilic SiO2 Janus particle modified waterborne epoxy anticorrosive coating, so as to improve the corrosion resistance of metal, improve the adhesion of the coating on the substrate, and endow the waterborne epoxy coating with excellent corrosion resistance.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] A preparation method of an amphiphilic SiO2 Janus particle modified waterborne epoxy anticorrosive coating comprises the following steps:

[0008] (1) Preparation of paraffin@SiO2 colloid:

[0009] A Pickering emulsion is prepared by using a solid paraffin-water system, 1-5 g of SiO2 particles are added to a water solution containing a surfactant, and ultrasonic dispersion is performed for 10-60 min. Then 5-15 g of paraffin is added, the temperature is raised to 60-90 DEG C, and mechanical stirring is performed for 1-3 h to obtain an oil-in-water Pickering emulsion. After cooling to room temperature, filtration, deionized water washing, and vacuum drying, the paraffin@SiO2 colloid is obtained.

[0010] (2) Preparation of amphiphilic SiO2 Janus particles:

[0011] Low surface energy siloxane is added to a water / ethanol solution, magnetic stirring is performed at a speed of 200-500 rpm for 2-24 h, paraffin@SiO2 particles are added, magnetic stirring is performed at a speed of 500-1500 rpm for 1-12 h, centrifugal separation is performed at a speed of 8000-12000 rpm for 5-30 min, the solid paraffin is dissolved in chloroform by slightly heating, centrifugal separation is performed, and the chloroform is repeatedly washed, and the dried SiO2 is obtained, which is modified to be hydrophobic on one side; then the hydrophobic modified SiO2 particles are further modified, and are uniformly dispersed in a methanol solution, an amino-containing silane coupling agent is added dropwise, and the other half of the hydrophobic modified SiO2 particles is functionalized by amino groups after a certain reaction time, so as to obtain amphiphilic SiO2 Janus particles;

[0012] (3) Preparation of amphiphilic SiO2 Janus particles-aqueous epoxy coating:

[0013] The amphiphilic SiO2 Janus particles and the aqueous epoxy resin are added to a diluent, stirred and dispersed at a speed of 1500-3000 rpm for 0.5-2 h by a dispersing machine, a curing agent is added and stirred and dispersed uniformly, then air in the coating is discharged by centrifugation at a speed of 1000-2000 rpm for 1-3 min, and a uniform modified aqueous epoxy coating is prepared.

[0014] (4) Coating and curing of the amphiphilic SiO2 Janus particle modified aqueous epoxy coating:

[0015] The modified epoxy coating prepared by coating on a metal substrate material in a manner of spraying, brushing, scraping, and spin coating, is left to stand at room temperature for 24 h, then cured at a temperature of 25-120℃ for 24-48 h, and an amphiphilic SiO2 Janus particle modified aqueous epoxy anticorrosive coating is obtained after curing.

[0016] Further, in step (1), the surfactant comprises one of cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride (CTAC), and didodecylammonium bromide (DDAB); the mass concentration of the aqueous solution of the surfactant is 0.01-1 g·L -1 ; the particle size of the SiO2 particles is 100 nm-5 um; and the mass ratio of SiO2 to paraffin is 1:1-10.

[0017] Further, in step (2), the low-surface-energy siloxane is one of 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (POTS) and hexadecyltrimethoxysilane (HDTMS); the silane coupling agent with an amino group is one of 3-aminopropyltriethoxysilane (APTES) and 3-aminopropyltrimethoxysilane (APS); the volume percentage of water to ethanol in the water / ethanol solution is 0-40%; the concentration of the low-surface-energy siloxane solution is 0.05-2%; and the mass ratio of the SiO2 nanoparticles to the low-surface-energy siloxane is 10-30:1.

[0018] Further, in step (3), the aqueous epoxy resin is EP-1705, and the aqueous epoxy curing agent is EC-1800; the mass ratio of the amphiphilic SiO2 Janus particles to the aqueous epoxy resin is 2-5:1; and the mass ratio of the diluent to the aqueous epoxy resin is 10-20:1.

[0019] Further, in step (4), the metal substrate material comprises at least one of carbon steel, copper, stainless steel, aluminum, aluminum alloy, and magnesium alloy.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] 1、 The present application utilizes the asymmetric characteristics of Janus particles to prepare amphiphilic SiO2 Janus particles, which are added to the water-based epoxy coating. The hydrophilic side of the amphiphilic SiO2 Janus particles can be well combined with the water-based epoxy coating, and the hydrophobic side is directed outward to form a hydrophobic film, which can effectively block water from penetrating the coating to contact the metal surface, thereby improving the corrosion resistance of the water-based epoxy coating.

[0022] 2、 The present application has the following advantages by using amphiphilic SiO2 Janus particles: (1) Low surface energy siloxane can be covalently combined with the hydroxyl groups on the surface of paraffin@SiO2 particles to form a hydrophobic group on half of the SiO2 particle surface; and the other half is connected with amino groups to obtain amphiphilic SiO2 Janus particles; (2) The amphiphilic SiO2 Janus particles on the surface of the water-based epoxy coating can provide the necessary roughness for constructing a hydrophobic surface, which is beneficial to improving the corrosion resistance of the water-based epoxy coating; (3) The amphiphilic SiO2 Janus particles have good compatibility with the water-based epoxy coating, which improves the adhesion between the coating and the substrate.

[0023] 3、 The water-based epoxy corrosion-resistant coating modified by the prepared amphiphilic SiO2 Janus particles has good corrosion resistance, hydrophobicity and adhesion, and has good use value and application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 SEM was used to characterize the morphology of the stable paraffin emulsion droplets of SiO2 particles in Example 3 of the present application, wherein the magnification of Figure A is 200, and the magnification of Figure B is 600.

[0025] Figure 2 FTIR was used to characterize the composition of SiO2 particles and modified amphiphilic SiO2 Janus particles in Example 1 of the present application.

[0026] Figure 3 XRD was used to study the prepared SiO2 particles and modified amphiphilic SiO2 Janus particles in Example 1 of the present application. DETAILED DESCRIPTION

[0027] The embodiments of the present application will be described in detail below with reference to the examples, and those skilled in the art will understand that the following examples are only preferred embodiments of the present application, in order to better understand the present application, but the protection scope of the present application is not limited to the following examples.

[0028] Example 1

[0029] (1) Preparation of paraffin@SiO2 colloids:

[0030] Pickering emulsion was prepared by solid paraffin-water method. 2 parts of SiO2 particles with an average particle size of 800 nm were added to a solution containing 80 parts of cetyltrimethylammonium bromide (CTAB) with a concentration of 0.1 g·L -1 After ultrasonic dispersion, 18 parts of paraffin were added, heated to 75°C, and stirred at a speed of 8000 rpm for 1 h using an emulsifier. After cooling to room temperature, filtration, deionized water washing, and vacuum drying, paraffin@SiO2 colloids were obtained.

[0031] (2) Preparation of amphiphilic SiO2 Janus particles:

[0032] 1 part of 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (POTS) was added to 90 parts of ethanol, and magnetic stirring was carried out at a speed of 200 rpm for 2 h. 9 parts of paraffin@SiO2 particles were added, and magnetic stirring was carried out at a speed of 500 rpm for 5 h for surface modification. Then, centrifugal separation was carried out at a speed of 8000 rpm for 10 min, and after drying, the solid paraffin was dissolved in chloroform by heating slightly. Centrifugal separation was carried out, and the sample was washed repeatedly with chloroform. After drying, one side of the SiO2 particles was modified to be hydrophobic. Then, the hydrophobically modified SiO2 particles were further modified by uniformly dispersing them in a methanol solution, and 1 part of 3-aminopropyltriethoxysilane (APTES) was added dropwise. After a certain period of reaction, the other half of the hydrophobically modified SiO2 particles was functionalized with amino groups to obtain amphiphilic SiO2 Janus particles, which were denoted as SiO2 Janus.

[0033] (3) Preparation of waterborne epoxy coating modified by amphiphilic SiO2 Janus particles:

[0034] 76.2 parts of waterborne epoxy resin EP-1705 and 15.2 parts of waterborne epoxy curing agent EC-1800 were mixed and stirred to obtain a uniformly dispersed solution. Then, 7.6 parts of a diluent and 1 part of amphiphilic SiO2 Janus particles were added, and stirring and dispersion were carried out at a speed of 1500 rpm for 1.5 h using a disperser. After that, centrifugal separation was carried out at a speed of 1500 rpm for 3 min to remove air in the coating, and a uniformly dispersed amphiphilic SiO2 Janus particle-waterborne epoxy coating was obtained, which was denoted as SiO2 Janus / WEP-1 coating.

[0035] (4) Coating and curing of waterborne epoxy coating modified by amphiphilic SiO2 Janus particles:

[0036] The amphiphilic SiO2 Janus particle-aqueous epoxy coating prepared above was sprayed on the surface of a polished and cleaned Q215 carbon steel substrate, and then left to stand at room temperature for 24 h, and then cured at a temperature range of 60°C for 48 h. After curing, an amphiphilic SiO2 Janus particle-aqueous epoxy anticorrosive coating with a thickness of about 50 μm was obtained.

[0037] Example 2

[0038] (1) Preparation of paraffin@SiO2 colloids:

[0039] The Pickering emulsion was prepared by using the solid paraffin-water method. 1.5 parts of SiO2 particles with an average particle size of 800 nm were added to a water solution containing 83.5 parts of didodecylammonium bromide (DDAB) with a concentration of 0.05 g·L -1 After ultrasonic dispersion, 15 parts of paraffin were added, heated to 75°C, and stirred at a speed of 8000 rpm for 1 h using an emulsifier. After cooling to room temperature, filtration, deionized water washing, and vacuum drying, paraffin@SiO2 colloids were obtained.

[0040] (2) Preparation of amphiphilic SiO2 Janus particles:

[0041] This step is the same as Example 1.

[0042] (3) Preparation of amphiphilic SiO2 Janus particle modified aqueous epoxy coating:

[0043] This step is the same as Example 1. A uniform amphiphilic SiO2 Janus particle-aqueous epoxy coating was prepared, denoted as SiO2 Janus / WEP-2 coating.

[0044] (4) Coating and curing of the amphiphilic SiO2 Janus particle modified aqueous epoxy coating:

[0045] This step is the same as Example 1.

[0046] Example 3

[0047] (1) Preparation of paraffin@SiO2 colloids:

[0048] The Pickering emulsion was prepared by using the solid paraffin-water method. 2 parts of SiO2 particles with an average particle size of 3 um were added to a water solution containing 80 parts of cetyltrimethylammonium bromide (CTAB) with a concentration of 0.1 g·L -1 After ultrasonic dispersion, 18 parts of paraffin were added, heated to 75°C, and stirred at a speed of 8000 rpm for 1 h using an emulsifier. After cooling to room temperature, filtration, deionized water washing, and vacuum drying, paraffin@SiO2 colloids were obtained.

[0049] (2) Preparation of amphiphilic SiO2 Janus particles:

[0050] This step is the same as Example 1.

[0051] (3) Preparation of amphiphilic SiO2 Janus particles-aqueous epoxy coating:

[0052] 75.2 parts of aqueous epoxy resin EP-1705 and 15.4 parts of aqueous epoxy curing agent EC-1800 were mixed and stirred to obtain a uniformly dispersed solution, then 7.9 parts of diluent and 1.5 parts of amphiphilic SiO2 Janus particles were added, and then a dispersing machine was used to stir and disperse at a speed of 1500 rpm for 1.5 h, and then centrifugation was performed at a speed of 1500 rpm for 3 min to discharge the air in the coating, thereby preparing a uniform amphiphilic SiO2 Janus particle-aqueous epoxy coating, which is denoted as SiO2 Janus / WEP-3 coating.

[0053] (4) Coating and curing of the amphiphilic SiO2 Janus particle modified aqueous epoxy coating:

[0054] This step is the same as Example 1.

[0055] Example 4

[0056] (1) Preparation of paraffin@SiO2 colloids:

[0057] This step is the same as Example 1.

[0058] (2) Preparation of amphiphilic SiO2 Janus particles:

[0059] 1.8 parts of hexadecyltrimethoxysilane (HDTMS) was added to 90 parts of ethanol, and magnetic stirring was performed at a speed of 200 rpm for 2 h, then 9 parts of paraffin@SiO2 particles were added, and magnetic stirring was performed at a speed of 500 rpm for 5 h for surface modification. Subsequently, centrifugation was performed at a speed of 8000 rpm for 10 min, and the precipitate was dissolved in chloroform after drying, and the solid paraffin was dissolved by slight heating, and the precipitate was washed repeatedly with chloroform, and then dried to obtain hydrophobically modified Janus particles, which are denoted as SiO2-HDTMS; then, the SiO2-HDTMS particles were further modified by adding 2 parts of 3-aminopropyltriethoxysilane (APTES) dropwise to 89 parts of a methanol solution, and magnetic stirring was performed at a speed of 300 rpm for 1 h, then 9 parts of SiO2-POTS particles were added, and magnetic stirring was performed at a speed of 600 rpm for 5 h for surface modification. Subsequently, centrifugation was performed at a speed of 8000 rpm for 10 min, and the precipitate was dried at 80°C under vacuum for 12 h, thereby preparing amphiphilic SiO2 Janus particles.

[0060] (3) Preparation of waterborne epoxy coating modified by amphiphilic SiO2 Janus particles:

[0061] Mix 76.2 parts of waterborne epoxy resin EP-1705 and 15.2 parts of waterborne epoxy curing agent EC-1800, obtain a uniformly dispersed liquid, then add 7.6 parts of diluent and 1 part of amphiphilic SiO2 Janus particles, and then stir and disperse using a dispersing machine at a speed of 1500 rpm for 1.5 h, and then centrifuge at a speed of 1500 rpm for 3 min to discharge air in the coating, to obtain a uniform amphiphilic SiO2 Janus particle-waterborne epoxy coating, denoted as SiO2 Janus / WEP-4 coating

[0062] (4) Coating and curing of waterborne epoxy coating modified by amphiphilic SiO2 Janus particles:

[0063] This step is the same as Example 1.

[0064] Comparative Example 1

[0065] Preparation of pure waterborne epoxy anticorrosive coating (WEP coating)

[0066] Add 15.2 parts of waterborne epoxy curing agent EC-1800 and 7.6 parts of diluent to 77.2 parts of waterborne epoxy resin EP-1705, and stir and disperse using a dispersing machine at a speed of 1500 rpm for 1.5 h, and then centrifuge at a speed of 1500 rpm for 3 min to discharge air in the coating, to obtain a uniform pure waterborne epoxy coating. The coating is coated and cured in the same manner as in Example 1, denoted as WEP coating.

[0067] Comparative Example 2

[0068] Preparation of SiO2 modified waterborne epoxy anticorrosive coating (SiO2 / WEP coating)

[0069] Mix 76.2 parts of waterborne epoxy resin EP-1705 and 15.2 parts of waterborne epoxy curing agent EC-1800, obtain a uniformly dispersed liquid, then add 7.6 parts of diluent and 1 part of SiO2 nanoparticles with an average particle size of 800 nm and stir and disperse using a dispersing machine at a speed of 1500 rpm for 1.5 h, and then centrifuge at a speed of 1500 rpm for 3 min to discharge air in the coating, to obtain a uniform SiO2 waterborne epoxy coating. The coating is coated and cured in the same manner as in Example 1, denoted as SiO2 / WEP coating.

[0070] Comparative Example 3

[0071] Preparation of amino-modified SiO2 modified waterborne epoxy anticorrosive coating (SiO2-NH2 / WEP coating)

[0072] SiO2 was modified with amino groups (SiO2-NH2), 76.2 parts of waterborne epoxy resin EP-1705 and 15.2 parts of waterborne epoxy curing agent EC-1800 were mixed and stirred to obtain a uniform dispersion, then 7.6 parts of diluent and 1 part of SiO2-NH2 were added, and then stirred and dispersed for 1.5 h at 1500 rpm using a disperser, and then centrifuged at 1500 rpm for 3 min to remove air in the paint, to obtain a uniform SiO2-NH2 waterborne epoxy paint. The coating was coated and cured in the same manner as in Example 1, and is denoted as SiO2-NH2 / WEP coating.

[0073] Comparative Example 4

[0074] Preparation of hydrophobically modified SiO2 modified waterborne epoxy anticorrosive coating (SiO2-F / WEP coating)

[0075] SiO2 was hydrophobically modified with 1H, 1H, 2H, 2H- perfluorooctyltriethoxysilane (POTS) (SiO2-F), 76.2 parts of waterborne epoxy resin EP-1705 and 15.2 parts of waterborne epoxy curing agent EC-1800 were mixed and stirred to obtain a uniform dispersion, then 7.6 parts of diluent and 1 part of SiO2-NH2 were added, and then stirred and dispersed for 1.5 h at 1500 rpm using a disperser, and then centrifuged at 1500 rpm for 3 min to remove air in the paint, to obtain a uniform SiO2-F waterborne epoxy paint. The coating was coated and cured in the same manner as in Example 1, and is denoted as SiO2-F / WEP coating.

[0076] The properties of the coatings prepared in Examples 1-4 and Comparative Examples 1-4 were measured, including hardness, adhesion, and corrosion resistance.

[0077] The hardness of the coatings of the examples and comparative examples was tested by PPH-750 pencil hardness tester. The pencil was sharpened to expose the lead, and was polished to a complete circle, and was pushed at a speed of 0.5-1 mm / s for at least 7 mm, and the hardness of the paint film was indicated by the hardest pencil without 3 mm or more scratches.

[0078] The adhesion was measured by the crosshatch method, as follows: a crosshatch with a side length of 1 mm was drawn on the coating with a crosshatch tool, then 3M tape was attached and pressed tightly, and then quickly pulled off, and the coating was observed for peeling under a magnifying glass.

[0079] The corrosion resistance was tested as follows: Q215 electrodes and electrodes coated with various coatings were placed in a 3.5% NaCl solution, and were measured at room temperature by electrochemical impedance spectroscopy.

[0080] The hardness and adhesion test results of the coatings of the examples and comparative examples are shown in Table 1.

[0081] Table 1 Hardness, adhesion test results of examples and comparative examples

[0082]

[0083]

[0084] From the test results in the table, the hardness of comparative example 1 is obviously smaller than that of the coating of examples and comparative examples, which shows that the addition of SiO2 particles can improve the hardness of the coating; the adhesion of examples 1-4 is significantly improved compared with the coating of comparative examples 1, 2 and 4, mainly because the amino groups grafted in the SiO2 Janus particles crosslink and combine with the water-based epoxy resin, improve the interfacial compatibility, and increase the adhesion of the coating.

[0085] The scanning electron microscope image of the SiO2 stabilized paraffin emulsion in example 3 is shown in Figure 1 . From Figure 1 A, it can be observed that the surface of the colloidal body is not smooth, but a concave-convex spherical surface; from Figure 1 B, it can be seen that the surface of the colloidal body is covered with SiO2 particles, and a monolayer arrangement is formed by the accumulation and stacking of paraffin on the surface, even after cooling to room temperature (including some destructive volume shrinkage of the wax phase), the monolayer surface coverage is still very high. Almost all SiO2 particles continue to remain on the interface, which shows that there is a strong adsorption between SiO2 particles and the surface of paraffin, which provides conditions for the preparation of amphiphilic Janus particles below.

[0086] The composition of SiO2 particles and modified amphiphilic SiO2 Janus particles (example 1) is characterized by Fourier transform infrared spectroscopy (FTIR), as shown in Figure 2 . By comparing the unmodified SiO2 particles with the modified amphiphilic SiO2 Janus particles, new absorption peaks appear in the amphiphilic SiO2 Janus particles, the stretching vibration of C-F causes the absorption peaks at 1210 cm -1 and 1250 cm -1 ; the absorption peaks at 557 cm -1 , 651 cm -1 , 746 cm -1 , 898 cm -1 are the existing forms of CF, CF2 and CF3 of C-F bond; the absorption peaks at 2921 cm -1 and 2852 cm -1 are the anti-symmetrical stretching vibration peak and symmetrical stretching vibration absorption peak of methylene (-CH2-) after APTES grafting. The results of FTIR show the success of SiO2 modification by POTS and APTES.

[0087] To further determine the structural characteristics of the prepared material, the prepared SiO2 particles and modified amphiphilic SiO2 Janus particles (Example 1) were studied by X-ray diffractometer (XRD), and the XRD spectrum is shown in Figure 3 Compared with the unmodified SiO2 particles, the modified amphiphilic SiO2 Janus particles did not produce other diffraction peaks, indicating that the crystal structure of the SiO2 particles did not change after modification by POTS.

[0088] The coating corrosion resistance test results are shown in Table 2, the low-frequency impedance modulus data after 30 days of immersion in 3.5% NaCl aqueous solution. In the same corrosion environment, the impedance modulus of the coating at low frequency (|Z| 0.01Hz ) can be used to evaluate the corrosion resistance of the coating, and the greater the value, the better the corrosion resistance. The order of the low-frequency impedance modulus |Z| 0.01Hz ) of the coating of each example in the table is: Example 1, 2, 3, 4 > Comparative Example 4 > Comparative Examples 2, 3 > Comparative Example 1, and the impedance modulus of the water-based coating in the examples is in the order of 10 8 , which is 2 orders of magnitude higher than the corrosion resistance of the WEP coating in Comparative Example 1, and 1 order of magnitude higher than the corrosion resistance of the SiO2 / WEP, SiO2-NH2 / WEP, SiO2-F / WEP coatings in Comparative Examples 2, 3, and 4. The main reason is that the hydrophilic amino groups of the SiO2 Janus particles in the coating are cross-linked and combined with the water-based epoxy resin, filling the internal defects of the coating, improving the interfacial compatibility and mechanical strength, while introducing the hydrophobic side groups of the Janus particles into the coating, effectively blocking the penetration of water molecules, and greatly improving the overall permeability resistance of the coating. The method for constructing a high corrosion-resistant water-based coating solves the shortcomings of poor water resistance, corrosion resistance and durability of current water-based coatings, and has a broad application prospect in the field of water-based corrosion-resistant coatings.

[0089] Table 2 Comparison of low-frequency impedance modulus results of examples and comparative examples after different salt water immersion times

[0090] 1d 7d 15d 22d 30d Example 1 7.4 x 10 8 Ω·cm 2 ]]> 1.8 x 10 8 Ω·cm 2 ]]> 6.1 x 10 7 Ω·cm 2 ]]> 2.5 x 10 7 Ω·cm 2 ]]> 7.8 x 10 6 Ω·cm 2 ]]> Example 2 8.6 x 10 8 Ω·cm 2 ]]> 2.3 x 10 8 Ω·cm 2 ]]> 7.5 x 10 7 Ω·cm 2 ]]> 3.2 x 10 7 Ω·cm 2 ]]> 7.9 x 10 6 Ω·cm 2 ]]> Example 3 7.3 x 10 8 Ω·cm 2 ]]> 1.6 x 10 8 Ω·cm 2 ]]> 5.8 x 10 7 Ω·cm 2 ]]> 2.4 x 10 7 Ω·cm 2 ]]> 6.3 x 10 6 Ω·cm 2 ]]> Example 4 6.9 x 10 8 Ω·cm 2 ]]> 1.1 x 10 8 Ω·cm 2 ]]> 5.5 x 10 7 Ω·cm 2 ]]> 1.8 x 10 7 Ω·cm 2 ]]> 6.4 x 10 6 Ω·cm 2 ]]> Comparative Example 1 8.9 x 10 6 Ω·cm 2 ]]> 8.3 x 10 5 Ω·cm 2 ]]> 1.2 x 10 5 Ω·cm 2 ]]> 7.7 x 10 4 Ω·cm 2 ]]> 1.2 x 10 4 Ω·cm 2 ]]> Comparative Example 2 1.3 x 10 7 Ω·cm 2 ]]> 7.3 x 10 6 Ω·cm 2 ]]> 6.4 x 10 5 Ω·cm 2 ]]> 1.5 x 10 5 Ω·cm 2 ]]> 8.1 x 10 4 Ω·cm 2 ]]> Comparative Example 3 1.7 x 10 7 Ω·cm 2 ]]> 7.9 x 10 6 Ω·cm 2 ]]> 5.5 x 10 5 Ω·cm 2 ]]> 1.3 x 10 5 Ω·cm 2 ]]> 7.7 x 10 4 Ω·cm 2 ]]> Comparative Example 4 6.9 x 10 7 Ω·cm 2 ]]> 1.5 x 10 7 Ω·cm 2 ]]> 4.2 x 10 6 Ω·cm 2 ]]> 8.5 x 10 5 Ω·cm 2 ]]> 1.6 x 10 5 Ω·cm 2 ]]>

[0091] The above examples are only used to further describe the invention content of the present application, but should not be understood as limiting the scope of the above-mentioned subject matter of the present application to only the above examples. Various substitutions and changes made according to ordinary technical knowledge and common means in the art without departing from the above technical idea of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing an amphiphilic SiO2 Janus particle modified waterborne epoxy anticorrosive coating, characterized in that, Comprising the following steps: (1) The low surface energy siloxane is added to the water / ethanol solution, and magnetic stirring is carried out. After adding the paraffin / SiO2 particles, magnetic stirring is continued. After centrifugation and drying, the product is dissolved in chloroform. The solid paraffin is dissolved by heating slightly. After centrifugation and repeated washing with chloroform, the product is dried to obtain hydrophobic modified SiO2. Then the hydrophobic modified SiO2 particles are further modified. The product is uniformly dispersed in a methanol solution. The amino-containing silane coupling agent is added dropwise. After a certain reaction time, the other half of the hydrophobic modified SiO2 particles is functionalized with amino groups to obtain amphiphilic SiO2 Janus particles; The preparation method of the paraffin@SiO2 particles comprises the following steps: preparing a Pickering emulsion by using a solid paraffin-water system, adding SiO2 particles into a water solution containing a surfactant, ultrasonic dispersion for 10-60 min; then adding paraffin, heating to 60-90 DEG C, mechanical stirring for 1-3 h, to obtain an oil-in-water Pickering emulsion; after cooling to room temperature, filtering, deionized water washing, vacuum drying, the paraffin@SiO2 colloidal can be obtained; the surfactant comprises one of cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride, didodecyl ammonium bromide; the mass concentration of the water solution of the surfactant is 0.01-1 g / L -1 ; the particle size of the SiO2 particles is 500 nm -5 ; the mass ratio of SiO2 to paraffin is 1:1-10. (2) The modified waterborne epoxy coating is prepared using the amphiphilic SiO2 Janus particles; Specifically comprising the following steps: The amphiphilic SiO2 Janus particles and waterborne epoxy resin are added to a diluent. The product is dispersed by a dispersing machine at a speed of 1500-3000 rpm for 0.5-2 h. The curing agent is added and dispersed uniformly. Then the product is centrifuged at a speed of 1000-2000 rpm for 1-3 min to remove air in the coating. A uniform modified waterborne epoxy coating is prepared. The mass ratio of the amphiphilic SiO2 Janus particles to the waterborne epoxy resin is 2-5:

1. (3) The amphiphilic SiO2 Janus particle modified waterborne epoxy anticorrosive coating is prepared using the modified waterborne epoxy coating.

2. The production method according to claim 1, characterized by, The low surface energy siloxane in step (1) is one of 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane and hexadecyltrimethoxysilane.

3. The production method according to claim 1, characterized by, The preparation of the amphiphilic SiO2 Janus particle modified waterborne epoxy anticorrosive coating using the modified waterborne epoxy coating in step (3) specifically comprises the following steps: The prepared amphiphilic SiO2 Janus particle-waterborne epoxy coating is coated on a metal substrate material. After standing at room temperature for 24 h, the product is cured at a temperature of 25-120℃ for 24-48 h. The amphiphilic SiO2 Janus particle modified waterborne epoxy anticorrosive coating is obtained after curing.

4. The method of claim 3, wherein; The metal substrate material includes at least one of carbon steel, copper, stainless steel, aluminum, aluminum alloy, and magnesium alloy.

Images