High chroma corrosion resistant yellow paint and method of making same

Abstract

This invention relates to the field of coatings, and discloses a high-color-ratio, corrosion-resistant yellow coating and its preparation method. The coating comprises the following components by weight: 50-60 parts by weight of waterborne epoxy-modified silicone resin, 25-35 parts by weight of modified bismuth vanadate, 1-2 parts by weight of nanocellulose, 0.3-0.8 parts by weight of dispersant, 0.2-0.5 parts by weight of defoamer, 0.2-0.5 parts by weight of leveling agent, and 2-3 parts by weight of corrosion-inhibiting pigment. The high-color-ratio, corrosion-resistant yellow coating formulation system of this invention is innovative, constructing a ternary synergistic system of waterborne epoxy-modified silicone resin-modified bismuth vanadate-nanocellulose, exhibiting excellent color and corrosion resistance. This coating utilizes microwave-induced flake-shaped bismuth vanadate, which has fewer lattice defects, achieves breakthrough color, and possesses high anti-corrosion performance.

Description

Technical Field

[0001] This invention relates to the field of coatings, specifically to a high-color, corrosion-resistant yellow coating and its preparation method. Background Technology

[0002] For marine chemical facilities operating in extremely corrosive environments (such as offshore drilling platforms, coastal petrochemical plants, storage tanks, and pipelines), highly visible yellow anti-corrosion coatings play a crucial role: First, they serve as prominent safety warning signs, ensuring the safety of personnel and equipment operation; second, as the first protective layer for the metal substrate, the anti-corrosion coating needs to withstand the combined erosion of multiple factors, including high humidity, high salinity, chemical atmospheres, and strong ultraviolet radiation, over long periods. This demanding application scenario presents significant challenges to the environmental friendliness, long-term weather resistance, and durable protective capabilities of yellow coatings.

[0003] Currently, yellow anti-corrosion coatings applicable to this field can be mainly divided into the following three categories according to their technical routes: the first-generation traditional system based on heavy metal pigments; the second-generation system based on organic pigments; and the third-generation environmentally friendly inorganic system based on bismuth vanadate pigments.

[0004] However, all three types of coatings have problems that urgently need improvement. The first-generation traditional system is now completely outdated in terms of environmental friendliness. Heavy metal pigments, represented by lead chromate yellow (PbCrO4), were once the mainstay of high-performance yellow anti-corrosion coatings. They possess excellent hiding power, chemical stability, and weather resistance. However, their inherent high toxicity and eco-accumulation fundamentally conflict with increasingly stringent environmental regulations. In today's advocacy of green manufacturing, the development and application of non-toxic and harmless alternatives has become an irreversible industrial trend, and such technologies will inevitably face elimination. The second-generation system based on organic pigments has a natural bottleneck in durability. To avoid the hazards of heavy metals, the industry has turned to organic yellow pigments. While they can provide vibrant hues, their chromophore molecular structure is highly susceptible to photo-oxidative degradation under continuous exposure to strong ultraviolet radiation in marine environments, leading to rapid chalking and fading of the coating. Simultaneously, organic molecules are prone to chemical changes under the influence of acidic and alkaline media in chemical atmospheres, further accelerating performance degradation. Its inherent weakness in durability leads to shorter maintenance cycles and high total life-cycle costs, failing to meet the core requirement of marine chemical facilities for long-term protection (typically requiring more than 15 years). The performance potential of third-generation environmentally friendly inorganic coatings based on bismuth vanadate pigments has not yet been fully realized. However, this type of coating typically faces problems such as insufficient color performance and the need to improve coating protective performance.

[0005] Overall, the existing third-generation environmentally friendly inorganic yellow coatings represent the mainstream development direction for the future, but they still have significant gaps in the two key indicators of color and corrosion resistance compared to the ideal level, indicating considerable room for improvement. Summary of the Invention

[0006] In view of the above-mentioned problems in the existing technology, the main objective of the present invention is to provide a high-color, corrosion-resistant yellow coating and its preparation method.

[0007] According to one aspect of the present invention, a high-color, corrosion-resistant yellow coating is provided, the coating comprising the following components by weight: 50-60 parts by weight of waterborne epoxy-modified silicone resin, 25-35 parts by weight of modified bismuth vanadate, 1-2 parts by weight of nanocellulose, 0.3-0.8 parts by weight of dispersant, 0.2-0.5 parts by weight of defoamer, 0.2-0.5 parts by weight of leveling agent, and 2-3 parts by weight of corrosion-inhibiting pigment.

[0008] According to one embodiment of the present invention, the modified bismuth vanadate is a sheet-like bismuth vanadate generated by microwave induction, and the sheet-like bismuth vanadate is coated with a carbon layer formed of polydopamine and an acid-resistant layer of calcium aluminum phase.

[0009] According to one embodiment of the present invention, the nanocellulose is nanocellulose that has undergone phosphorylation surface treatment, with a diameter of 5~60nm and a length of 50nm~2μm.

[0010] According to another aspect of the present invention, a method for preparing a high-chroma, corrosion-resistant yellow coating is provided, the method being used to prepare the yellow coating as described in any of the above embodiments and comprising the following steps:

[0011] Modified bismuth vanadate was induced to form using a microwave method;

[0012] Modified bismuth vanadate, waterborne epoxy-modified silicone resin, deionized water, dispersant, and corrosion-inhibiting pigment are premixed, dispersed, and ground to obtain a pigment slurry.

[0013] Nanocellulose, defoamer and pigment paste are stirred and mixed, dispersed and ground, leveling agent is added, and the mixture is stirred and mixed to obtain the yellow coating.

[0014] According to one embodiment of the present invention, the preparation process of the modified bismuth vanadate includes the following steps:

[0015] The bismuth salt is mixed with the first solvent to form the first solution;

[0016] Vanadium salt, tartaric acid, and a second solvent are mixed to form a second solution, and the pH of the second solution is adjusted to 4.5-5.5.

[0017] The first solution and the second solution are mixed in a microwave reactor and reacted at a preset temperature to generate a bismuth vanadate precursor.

[0018] The bismuth vanadate precursor is dispersed in a third solution containing polydopamine, and a polydopamine coating layer is formed outside the bismuth vanadate precursor.

[0019] Add sodium alginate and calcium chloride solution to the third solution to form a calcium-alginate network structure on the outside of the polydopamine coating layer through ionic crosslinking.

[0020] The solution after ion crosslinking is subjected to solid-liquid separation, the solid is collected, and the solid is then thermally cured.

[0021] According to one embodiment of the present invention, the bismuth ion concentration in the first solution is 0.3~0.8 mol / L, the vanadium ion concentration in the second solution is 0.3~0.8 mol / L, the molar ratio of the vanadium salt to the tartaric acid is 1:1~1.2, and the volume ratio of the first solution to the second solution used for mixing is 1:0.9~1.

[0022] According to one embodiment of the present invention, the microwave reactor has a frequency of 2.45 GHz and a power of 800 W; the reaction temperature of the first solution and the second solution is 60~90℃ and the reaction time is 10~30 min.

[0023] According to one embodiment of the present invention, the solvent of the third solution is tris(hydroxymethyl)aminomethane hydrochloride buffer, and the concentration of polydopamine in the third solution is 1-2 mg / mL; the mass concentration of the bismuth vanadate precursor dispersed in the third solution is 100-300 g / L; after dispersing the bismuth vanadate precursor in the third solution, it is shaken at 40-60°C for 1-3 h; the mass ratio of sodium alginate to the bismuth vanadate precursor is 1.2-2:100; the concentration of the calcium chloride solution is 0.1-0.25 mol / L, and the volume ratio of the calcium chloride solution to the third solution is 0.25-3.5:100.

[0024] According to one embodiment of the present invention, the solid is thermosetting by: first heating the solid to 250-300°C at 3-7°C / min and holding it at that temperature for 20-50 min, and then heating it to 400-450°C at 7-10°C / min and holding it at that temperature for 5-20 min.

[0025] According to one embodiment of the present invention, the stirring speed of the premixing is 1200~1500 rpm and the stirring time is 10~30 min, and the stirring speed of the mixing is 400~600 rpm and the stirring time is 15~45 min.

[0026] Compared with the prior art, the high-chroma corrosion-resistant yellow coating and its preparation method of the present invention have at least one of the following beneficial effects:

[0027] (1)Innovation in formulation system: A ternary synergistic system of waterborne epoxy-modified silicone resin-modified bismuth vanadate-nanocellulose was constructed. Each component was organically combined through specific ratios and surface characteristics to jointly build a coating foundation with excellent chromaticity and corrosion resistance;

[0028] (2)Introduction of nanocellulose as a multifunctional reinforcing phase, which has a huge specific surface area and abundant surface hydroxyl groups, and realizes the triple effects of strengthening and toughening, barrier corrosion prevention, and rheology control through its three-dimensional network structure;

[0029] (3)The coating uses sheet-like bismuth vanadate induced by the microwave method, which has few lattice defects, breakthrough chromaticity, L value > 89, -5 < a value < 5, 88 < b value < 92, and realizes the high corrosion resistance of bismuth vanadate through the double protection of Ca-alginate / PDA carbon layer. Brief Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 The flowchart showing the preparation method of the high-chromaticity and corrosion-resistant yellow coating according to the embodiment of the present invention; [[ID=?]]

[0032] [[ID=?]] Figure 2 The flowchart showing the induction of modified bismuth vanadate by the microwave method according to the embodiment of the present invention. Detailed Embodiments

[0033] In order to make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the following will further elaborate on the present invention in combination with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] In addition, referring to "embodiment" herein means that the specific features, structures or characteristics described in combination with the embodiment can be included in at least one embodiment of the present invention. The appearance of this phrase at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0035] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0036] According to one aspect of the present invention, a high-color, corrosion-resistant yellow coating is provided. The yellow coating comprises the following components by weight: 50-60 parts by weight of waterborne epoxy-modified silicone resin, 25-35 parts by weight of modified bismuth vanadate, 1-2 parts by weight of nanocellulose, 0.3-0.8 parts by weight of dispersant, 0.2-0.5 parts by weight of defoamer, 0.2-0.5 parts by weight of leveling agent, and 2-3 parts by weight of corrosion-inhibiting pigment.

[0037] The core design of the coating system of this invention lies in the fact that, through the synergistic design of components and structure, a long-lasting and dense physical and chemical composite barrier is formed to cope with the harsh marine corrosion environment while achieving high color intensity.

[0038] The waterborne epoxy-modified silicone resin serves as the film-forming substance and the basis for corrosion protection. This resin forms the film-forming matrix of the coating, combining the excellent adhesion of epoxy resin with the superior heat resistance, weather resistance, and hydrophobicity of silicone resin. The resulting coating exhibits good chemical stability and physical-mechanical strength, providing a fundamental guarantee for the coating's corrosion resistance. Specifically, the waterborne epoxy-modified silicone resin can be copolymerized from, for example, epoxy resin with γ-glycidyl etheroxypropyltrimethoxysilane, methacryloyloxyethyl phosphate, and methyl methacrylate. In some embodiments of this invention, resins prepared by cold blending or chemical grafting are preferred to ensure the stability of the system. The amount of waterborne epoxy-modified silicone resin used must be controlled within a suitable range. If the amount is too small, the resin will not fully coat the pigments and fillers, resulting in porous coatings that allow corrosive media to easily penetrate. Conversely, if the amount is too large, the coating will be too soft and not wear-resistant. Therefore, in the coating system of the present invention, the amount of waterborne epoxy-modified silicone resin is controlled at 50 to 60 parts by weight.

[0039] The modified bismuth vanadate is used as a color-developing and functional pigment in the coating system, and it has multiple functions: on the one hand, the modified bismuth vanadate is used as the core functional pigment of the coating. The bismuth vanadate induced by the microwave method has a unique flaky structure, which can enhance the specular reflection of light, and it has few lattice defects, chromaticity breakthrough, L value > 89, -5 < a value < 5, 88 < b value < 92, so as to improve the chromaticity and gloss of the coating and provide a high-saturation yellow for the coating; on the other hand, bismuth vanadate is a chemically inert inorganic substance, which can effectively block the penetration of corrosive media, and through the double protection of the Ca-alginate / PDA carbon layer, the high anti-corrosion performance of bismuth vanadate is achieved. If the proportion of the pigment used is too high, it will cause the coating to be loose and porous, and the adhesion and flexibility will be significantly reduced, and the coating is easy to powder; if the proportion of the pigment used is too low, it will cause insufficient hiding power and coloring power of the coating, unable to meet the use requirements. Therefore, in the coating system of the present invention, the amount of the modified bismuth vanadate is controlled at 25 to 35 parts by weight. In some embodiments, the modified bismuth vanadate is flaky bismuth vanadate induced by the microwave method.

[0040] Nanocellulose is used as a nano-enhancing and structure-regulating agent in the coating system. Using nanocellulose in the coating is one of the key innovative components of the present invention. Due to its huge specific surface area and abundant surface hydroxyl groups, nanocellulose can play three roles:

[0041] First, it has the function of enhancing and toughening: Nanocellulose can form a three-dimensional network structure in the resin matrix, significantly improving the hardness, wear resistance and impact resistance of the coating;

[0042] Second, it has a barrier effect: Nanocellulose can effectively extend the diffusion path of corrosive media such as water and chlorine in the coating, playing a barrier role;

[0043] Third, it has a rheology control effect: Nanocellulose can also prevent the solid particles in the coating from settling during storage and construction, improving the construction performance.

[0044] If the proportion of nanocellulose used in the coating system is too low, a network cannot be formed and its function is limited; if the proportion used is too high, serious agglomeration is likely to occur and the cost is increased. Therefore, in the coating system of the present invention, the amount of nanocellulose is controlled at 1 to 2 parts by weight. In some embodiments, the nanocellulose is nanocellulose treated by phosphoric acid esterification on the surface, and this treatment can significantly improve its compatibility with the resin and further enhance its dispersion stability. In some embodiments, the diameter of the nanocellulose can be 5 to 60 nm, and the length can be 50 nm to 2 μm.

[0045] Dispersants, defoamers, leveling agents and inhibitive pigments are auxiliary functional additives for the coating.

[0046] The dispersant can reduce the surface tension of the resin, enabling it to quickly penetrate and wet the pigment, while enhancing the dispersion effect of nanocellulose in the resin to ensure pigment stability. Specifically, dispersants such as BYK-190 can be selected.

[0047] The defoamer is used to prevent bubble defects in the coating during production and construction. Specifically, defoamers such as BYK-024 can be selected.

[0048] The leveling agent ensures that the coating can level before curing to form a smooth and uniform coating film. Specifically, leveling agents such as BYK-331 can be selected.

[0049] As a supplement, the inhibitive pigment can release inhibitive ions when the coating is locally damaged, providing active anti-corrosion protection. Specifically, inhibitive pigments such as zinc phosphate can be selected.

[0050] Through the adoption of the above innovative formulation system, the coating of the present invention constructs a ternary synergistic system of waterborne epoxy-modified silicone resin-modified bismuth vanadate-nanocellulose. Each component is organically combined through specific ratios and surface characteristics to jointly build a coating foundation with excellent chromaticity and corrosion resistance; nanocellulose is introduced as a multifunctional reinforcing phase, which has a large specific surface area and abundant surface hydroxyl groups, and realizes the triple effects of strengthening and toughening, barrier anti-corrosion, and rheology control through its three-dimensional network structure; the coating uses sheet-like bismuth vanadate induced by the microwave method, which has few lattice defects, breakthrough chromaticity, L value > 89, -5 < a value < 5, 88 < b value < 92, and realizes the high anti-corrosion performance of bismuth vanadate through the double protection of Ca-alginate / PDA carbon layer. After testing, the bismuth vanadate coating does not change color after being immersed in 10wt% HCl / NaOH solution for 500h, and the electrochemical impedance increases by three orders of magnitude.

[0051] The present invention also provides a preparation method for the high-chromaticity and corrosion-resistant yellow coating described in the above embodiments. As Figure 1 shown, the preparation method for the high-chromaticity and corrosion-resistant yellow coating according to the embodiments of the present invention generally includes the following processes:

[0052] Step S100: Induce the formation of modified bismuth vanadate by the microwave method;

[0053] Step S​​​​​​​​Although BiVO4 has many advantages, traditional preparation techniques have several key technical bottlenecks that severely restrict its industrial application in the field of high-performance coatings.

[0057] The contradiction between chromaticity and stability is particularly prominent in BiVO4 prepared by traditional processes. BiVO4 pigments prepared by traditional solid-state methods generally suffer from insufficient chromaticity, with their yellow saturation (b-value) typically below 40, making it difficult to meet the demand for vibrant colors in high-end coatings. Although doping with elements such as tungsten (W) or molybdenum (Mo) can improve chromaticity to some extent, this doping process often significantly reduces the material's acid resistance, causing a substantial decrease in its stability in acidic environments.

[0058] Currently, the corrosion resistance of BiVO4 pigments remains insufficient. BiVO4 is a semiconductor material, and its semiconductor properties accelerate substrate corrosion at coating defects. Furthermore, its photocatalytic activity degrades surrounding organic resins, weakening the coating barrier. Most BiVO4 pigment modification techniques employ silane coupling agents or organic polymers for surface coating, which improves weather resistance to some extent. However, in extreme acidic or alkaline environments (pH < 2 or pH > 12), these coating materials are prone to interfacial delamination, leading to protective failure. This problem severely limits the application of BiVO4 coatings in harsh corrosive environments such as chemical and marine applications.

[0059] To address the above problems, this invention innovatively employs a microwave method to induce the generation of modified bismuth vanadate. For example... Figure 2 As shown, the microwave-induced generation of modified bismuth vanadate aggregates includes the following steps:

[0060] Step S110: Mix the bismuth salt with the first solvent to form a first solution;

[0061] Step S120: Mix vanadium salt, tartaric acid and a second solvent to form a second solution, and adjust the pH of the second solution to 4.5~5.5;

[0062] Step S130: The first solution and the second solution are mixed in a microwave reactor and reacted at a preset temperature to generate a bismuth vanadate precursor;

[0063] Step S140: The bismuth vanadate precursor is dispersed in a third solution containing polydopamine to form a polydopamine coating layer on the bismuth vanadate precursor.

[0064] Step S150: Add sodium alginate and calcium chloride solution to the third solution to form a calcium-alginate network structure on the outside of the polydopamine coating layer through ionic crosslinking;

[0065] Step S160: Perform solid-liquid separation on the ion-crosslinked solution, collect the solid, and then heat-cure the solid.

[0066] In step S110, the bismuth salt is mixed with a first solvent to form a first solution. The bismuth salt may be selected from at least one of Bi(NO3)3 and BiCl3. The first solvent may be a mixture of ethylene glycol and water (ethylene glycol to water volume ratio of 2:1 to 5:1), and the concentration of bismuth ions in the first solution is 0.3 to 0.8 mol / L.

[0067] In step S120, vanadium salt, tartaric acid, and a second solvent are mixed to form a second solution, and the pH of the second solution is adjusted to 4.5-5.5. The vanadium salt can be selected from at least one of sodium metavanadate and ammonium metavanadate. The second solvent can be water. The concentration of vanadium ions (vanadate ions) in the second solution is 0.3-0.8 mol / L. The molar ratio of vanadium salt to tartaric acid is 1:1-1.2. Adjusting the pH to 4.5-5.5 prevents excessive polymerization of vanadate ions and allows vanadate ions to form a stable complex with tartaric acid.

[0068] In step S130, the first solution and the second solution are mixed in a microwave reactor and reacted at a preset temperature to generate a bismuth vanadate precursor. In some embodiments, the volume ratio of the first solution to the second solution is 1:0.9~1. In some embodiments, the microwave reactor has a frequency of 2.45 GHz and a power of 800 W; the reaction temperature of the first solution and the second solution is 60~90℃, and the reaction time is 10~30 min. The microwave method can generate bismuth vanadate precursors with uniform particle size in a short time, suppress lattice defects in the bismuth vanadate precursor, and help obtain high-chroma pigments. Moreover, microwave synthesis has low energy consumption.

[0069] After synthesizing the bismuth vanadate precursor, surface modification was performed to improve its corrosion resistance and suppress the photocatalytic effect of bismuth vanadate pigment on organic resin, which helped the coating maintain mechanical strength and density.

[0070] In step S140, the bismuth vanadate precursor is dispersed in a third solution containing polydopamine, forming a polydopamine (PDA) coating layer on the bismuth vanadate precursor. PDA possesses functional groups such as hydroxyl and amino groups, allowing it to be firmly anchored to the bismuth vanadate precursor. The PDA coating layer acts as a barrier, effectively preventing corrosive ions such as water, oxygen, and chlorine from directly contacting and penetrating into the bismuth vanadate. Simultaneously, the PDA coating layer also serves to connect the outer Ca-alginate layer. After thermosetting, the PDA coating layer forms a conductive network, improving the overall charge transport efficiency of the material, thereby enhancing the photoelectrochemical properties and stability of bismuth vanadate.

[0071] In some embodiments, the solvent of the third solution is tris(hydroxymethyl)aminomethane hydrochloride buffer (pH=8.5), the concentration of polydopamine in the third solution is 1~2 mg / mL, and the mass concentration of the bismuth vanadate precursor dispersed in the third solution is 100~300 g / L. The bismuth vanadate precursor is dispersed in the third solution and shaken at 40~60°C for 1~3 h.

[0072] In step S150, sodium alginate and calcium chloride solution are added to the third solution to form a calcium-alginate network structure on the outside of the polydopamine coating layer through ionic crosslinking. After high-temperature curing, an acid-resistant calcium aluminum phase can be formed, which improves the acid resistance of bismuth vanadate pigment.

[0073] In some embodiments, the mass ratio of sodium alginate to bismuth vanadate precursor is 1.2~2:100; the concentration of calcium chloride solution is 0.1~0.25mol / L; and the volume ratio of calcium chloride solution to the third solution is 0.25~3.5:100.

[0074] In step S160, the ion-crosslinked solution undergoes solid-liquid separation, the solid is collected, and then thermally cured. Thermal curing can be achieved by first heating the solid to 250-300℃ at a rate of 3-7℃ / min and holding for 20-50 min, then further heating to 400-450℃ at a rate of 7-10℃ / min and holding for 5-20 min. Holding at 250-300℃ for 20-50 min carbonizes the PDA to form a conductive network. Holding at 400-450℃ for 5-20 min induces the conversion of Ca-algite into an acid-resistant calcium aluminum phase (Ca2Al(OH)7·3H2O).

[0075] The modified bismuth vanadate pigment prepared by the above scheme has high color intensity, strong corrosion resistance, short preparation process, and low wastewater discharge.

[0076] The remaining steps of the preparation method for high-chroma, corrosion-resistant yellow coating will be introduced.

[0077] In step S200, modified bismuth vanadate, waterborne epoxy-modified silicone resin, deionized water, dispersant, and corrosion-inhibiting pigment are premixed, dispersed, and ground to obtain a pigment slurry. In this step, a high-speed disperser is used to mix the pigment and resin at a stirring speed of 1200-1500 rpm for 10-30 minutes to ensure sufficient deagglomeration and stable dispersion of the pigment particles. The mixture is then subjected to ultrafine grinding in a sand mill until the particle size D90 ≤ 5 μm.

[0078] In step S300, nanocellulose, defoamer, and pigment paste are stirred, mixed, dispersed, and ground. A leveling agent is added, and the mixture is stirred to obtain a yellow paint. In this step, other components are slowly added to the pigment paste under medium-speed stirring at 400-600 rpm to avoid introducing excessive air bubbles.

[0079] The prepared high-chroma, corrosion-resistant yellow coating can be applied using electrostatic spraying and a stepped temperature curing process. Specifically, the prepared coating is adjusted to a suitable application viscosity and applied using electrostatic spraying equipment under a high voltage of 40-60kV. This process allows charged coating particles to be uniformly and densely adsorbed onto the surface of a grounded substrate under the influence of an electric field. Especially for workpieces with complex structures, it achieves seamless coverage, forming a uniformly thick wet film. After spraying, the workpiece is first held at 80-90℃ for 5 minutes to allow the coating to slowly level and initially remove moisture and some solvent. Then, it is held at 130-160℃ for 15-25 minutes for primary curing. During this stage, the resin undergoes a full cross-linking reaction, forming a dense three-dimensional network structure. Precise control of temperature and time ensures optimal mechanical properties and chemical resistance of the coating film, while avoiding color differences or insufficient curing caused by excessively high or low temperatures.

[0080] The method of the present invention will be further described and illustrated below with reference to embodiments. The coating application and performance testing operations in the following embodiments are as follows: Electrostatic spraying equipment is used for application under a high voltage of 40~60kV. The substrate is marine steel plate, and the wet film thickness is 40μm. After spraying, the coating is first held in a preheating zone at 85℃ for 5 minutes, and then held in a main curing zone at 145℃ for 20 minutes. Colorimetric testing is performed according to CIE Lab D65 standard; salt spray resistance testing is performed according to the test combination for C5-M level environments in ISO 9227; and adhesion testing is performed according to the cross-cut test combination in GB / T 9286.

[0081] Example 1

[0082] Microwave-induced generation of modified bismuth vanadate: (1) Synthesis of bismuth vanadate precursor: Bismuth nitrate was dissolved in a ethylene glycol-water mixed solvent (ethylene glycol and water volume ratio 3:1) to form a 0.5 mol / L solution A; sodium metavanadate and tartaric acid (molar ratio 1:1.1) were dissolved in water to prepare a vanadate concentration of 0.5 mol / L solution B, and the pH was adjusted to 4.5~5.5 to form a stable vanadate complex; in a microwave reactor (2.45 GHz, 800 W), solutions A and B were mixed (volume ratio 1:1) and reacted at 75 °C for 20 min to obtain a bright yellow precursor; (2) Modification of bismuth vanadate precursor: The precursor was dispersed in a PDA solution (1.5 mg / mL, Tris-HCl buffer, pH=8.5). ), Bismuth vanadate precursor is dispersed in PDA solution with a mass concentration of 200 g / L, shaken at 50℃ for 2 h to form PDA coating layer; sodium alginate and CaCl2 solution (0.2 mol / L) are added, the amount of sodium alginate is 1.6% of the mass of bismuth vanadate precursor, the volume ratio of calcium chloride solution to PDA solution is 1.8:100, and Ca-alginate grid structure is constructed on the outside of PDA layer through ionic crosslinking; (3) Bismuth vanadate thermal curing: the modified powder is placed in a programmable temperature controlled furnace, first raised to 300℃ at 5℃ / min and held for 35 min to carbonize PDA to form a conductive network; then rapidly heated to 450℃ at 8℃ / min for 15 min to induce Ca-alginate to transform into acid-resistant calcium aluminum phase.

[0083] Preparation of high-color, corrosion-resistant yellow coating: 30 parts by weight of modified bismuth vanadate, 55 parts by weight of waterborne epoxy-modified silicone resin, 10 parts by weight of deionized water, 0.5 parts by weight of dispersant, and 2.5 parts by weight of corrosion-inhibiting pigment are premixed and dispersed in a high-speed disperser (1200~1500 rpm) for 20 min, and then ultra-finely ground in a sand mill (particle size D90≤5μm) to obtain a pigment slurry; 1.5 parts by weight of nanocellulose and 0.3 parts by weight of defoamer are slowly added to the pigment slurry under medium-speed stirring (500 rpm), stirred and mixed, dispersed and ground for 30 min, and then 0.4 parts by weight of leveling agent are added and stirred to obtain a yellow coating.

[0084] The prepared yellow coating was electrostatically sprayed onto marine steel plates, and its performance was tested. The test results are shown in Table 1 below:

[0085] Table 1. Results of coating performance testing in Example 1

[0086]

[0087] Example 2

[0088] Microwave-induced generation of modified bismuth vanadate: (1) Synthesis of bismuth vanadate precursor: Bismuth nitrate was dissolved in a mixed solvent of ethylene glycol and water (volume ratio of ethylene glycol to water 2:1) to form a 0.3 mol / L solution A; sodium metavanadate and tartaric acid (molar ratio 1:1) were dissolved in water to prepare a solution B with a vanadate concentration of 0.3 mol / L, and the pH was adjusted to 4.5~5.5 to form a stable vanadium complex; in a microwave reactor (2.45 GHz, 800 W), solutions A and B were mixed (volume ratio 1:0.9) and reacted at 60 °C for 30 min to obtain a bright yellow precursor; (2) Modification of bismuth vanadate precursor: The precursor was dispersed in a PDA solution (1 mg / mL, Tris-HCl buffer, pH=8.5) Bismuth vanadate precursor is dispersed in PDA solution with a mass concentration of 100 g / L, shaken at 40℃ for 3 h to form PDA coating layer; sodium alginate and CaCl2 solution (0.1 mol / L) are added, the amount of sodium alginate is 1.2% of the mass of bismuth vanadate precursor, the volume ratio of calcium chloride solution to PDA solution is 0.25:100, and Ca-alginate grid structure is constructed on the outside of PDA layer through ionic crosslinking; (3) Bismuth vanadate thermal curing: the modified powder is placed in a programmable temperature controlled furnace, first raised to 300℃ at 3℃ / min and held for 20 min to carbonize PDA to form conductive network; then rapidly raised to 450℃ at 7℃ / min for 5 min to induce Ca-alginate to transform into acid-resistant calcium aluminum phase.

[0089] Preparation of high-color, corrosion-resistant yellow coating: 25 parts by weight of modified bismuth vanadate, 50 parts by weight of waterborne epoxy-modified silicone resin, 8 parts by weight of deionized water, 0.3 parts by weight of dispersant, and 2 parts by weight of corrosion-inhibiting pigment are premixed and dispersed in a high-speed disperser (1200~1500 rpm) for 10 min, and then ultra-finely ground in a sand mill (particle size D90≤5μm) to obtain a pigment slurry; 1 part by weight of nanocellulose and 0.2 parts by weight of defoamer are slowly added to the pigment slurry under medium-speed stirring (400 rpm), stirred and mixed, dispersed and ground for 45 min, and then 0.2 parts by weight of leveling agent are added and stirred to obtain a yellow coating.

[0090] The prepared yellow coating was electrostatically sprayed onto marine steel plates, and its performance was tested. The test results are shown in Table 2 below:

[0091] Table 2. Results of coating performance testing in Example 2

[0092]

[0093] Example 3

[0094] Microwave-induced generation of modified bismuth vanadate: (1) Synthesis of bismuth vanadate precursor: Bismuth chloride was dissolved in a mixed solvent of ethylene glycol and water (volume ratio of ethylene glycol to water 5:1) to form a 0.8 mol / L solution A; ammonium metavanadate and tartaric acid (molar ratio 1:1.2) were dissolved in water to prepare a solution B with a vanadate concentration of 0.8 mol / L, and the pH was adjusted to 4.5~5.5 to form a stable vanadate complex; in a microwave reactor (2.45 GHz, 800 W), solutions A and B were mixed (volume ratio 1:1) and reacted at 90 °C for 10 min to obtain a bright yellow precursor; (2) Modification of bismuth vanadate precursor: The precursor was dispersed in a PDA solution (2 mg / mL, Tris-HCl buffer, pH=8.5) Bismuth vanadate precursor is dispersed in PDA solution with a mass concentration of 300 g / L, shaken at 60℃ for 1 h to form PDA coating layer; sodium alginate and CaCl2 solution (0.25 mol / L) are added, the amount of sodium alginate is 2% of the mass of bismuth vanadate precursor, the volume ratio of calcium chloride solution to PDA solution is 3.5:100, and Ca-alginate grid structure is constructed on the outside of PDA layer through ionic crosslinking; (3) Bismuth vanadate thermal curing: the modified powder is placed in a programmable temperature controlled furnace, first raised to 250℃ at 7℃ / min and held for 50 min to carbonize PDA to form a conductive network; then rapidly heated to 400℃ at 10℃ / min for 20 min to induce Ca-alginate to transform into acid-resistant calcium aluminum phase.

[0095] Preparation of high-color, corrosion-resistant yellow coating: 35 parts by weight of modified bismuth vanadate, 60 parts by weight of waterborne epoxy-modified silicone resin, 12 parts by weight of deionized water, 0.8 parts by weight of dispersant, and 3 parts by weight of corrosion-inhibiting pigment are premixed and dispersed in a high-speed disperser (1200~1500 rpm) for 30 min, and then ultra-finely ground in a sand mill (particle size D90≤5μm) to obtain a pigment slurry; 2 parts by weight of nanocellulose and 0.5 parts by weight of defoamer are slowly added to the pigment slurry under medium-speed stirring (600 rpm), stirred and mixed, dispersed and ground for 15 min, and then 0.5 parts by weight of leveling agent are added and stirred to obtain a yellow coating.

[0096] The prepared yellow coating was electrostatically sprayed onto marine steel plates, and its performance was tested. The test results are shown in Table 3 below:

[0097] Table 3. Results of Coating Performance Testing in Example 3

[0098]

[0099] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the disclosed embodiments of the present invention is limited to these examples; within the framework of the embodiments of the present invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of the present invention should be included within the protection scope of the embodiments of the present invention.

Claims

1. A high-color, corrosion-resistant yellow coating, characterized in that, The product comprises the following components by weight: 50-60 parts by weight of waterborne epoxy-modified silicone resin, 25-35 parts by weight of modified bismuth vanadate, 1-2 parts by weight of nanocellulose, 0.3-0.8 parts by weight of dispersant, 0.2-0.5 parts by weight of defoamer, 0.2-0.5 parts by weight of leveling agent, and 2-3 parts by weight of corrosion inhibitor pigment. The modified bismuth vanadate is a flake-shaped bismuth vanadate induced by microwave method. The preparation process of the modified bismuth vanadate includes the following steps: mixing bismuth salt with a first solvent to form a first solution; mixing vanadium salt, tartaric acid, and a second solvent to form a second solution; adjusting the pH of the second solution to 4.5-5.5; mixing the first solution and the second solution in a microwave reactor and reacting at a preset temperature to generate a bismuth vanadate precursor. The bismuth vanadate precursor is dispersed in a third solution containing polydopamine, and a polydopamine coating layer is formed outside the bismuth vanadate precursor. Sodium alginate and calcium chloride solution are added to the third solution to form a calcium-alginate network structure on the outside of the polydopamine coating layer through ionic crosslinking; the ionicly crosslinked solution is subjected to solid-liquid separation, the solid is collected, and the solid is thermally cured.

2. The high-colorability, corrosion-resistant yellow coating according to claim 1, characterized in that, The nanocellulose is nanocellulose that has undergone phosphorylation surface treatment, with a diameter of 5~60nm and a length of 50nm~2μm.

3. A method for preparing a high-color, corrosion-resistant yellow coating, characterized in that, The method is used to prepare the yellow paint as described in claim 1 or 2 and includes the following steps: Modified bismuth vanadate was induced to form using a microwave method. The modified bismuth vanadate was in flake form and the preparation process included the following steps: mixing bismuth salt with a first solvent to form a first solution; mixing vanadium salt, tartaric acid, and a second solvent to form a second solution; adjusting the pH of the second solution to 4.5-5.5; mixing the first solution and the second solution in a microwave reactor and reacting at a preset temperature to generate a bismuth vanadate precursor. The bismuth vanadate precursor is dispersed in a third solution containing polydopamine, and a polydopamine coating layer is formed outside the bismuth vanadate precursor. Sodium alginate and calcium chloride solution are added to the third solution to form a calcium-alginate network structure on the outside of the polydopamine coating layer through ionic crosslinking; the ionicly crosslinked solution is subjected to solid-liquid separation, the solid is collected and the solid is thermally cured. Modified bismuth vanadate, waterborne epoxy-modified silicone resin, deionized water, dispersant, and corrosion-inhibiting pigment are premixed, dispersed, and ground to obtain a pigment slurry. Nanocellulose, defoamer and pigment paste are stirred and mixed, dispersed and ground, leveling agent is added, and the mixture is stirred and mixed to obtain the yellow coating.

4. The method for preparing the high-chroma corrosion-resistant yellow coating according to claim 3, characterized in that, The concentration of bismuth ions in the first solution is 0.3~0.8 mol / L, the concentration of vanadium ions in the second solution is 0.3~0.8 mol / L, the molar ratio of the vanadium salt to the tartaric acid is 1:1~1.2, and the volume ratio of the first solution to the second solution used for mixing is 1:0.9~1.

5. The method for preparing the high-chroma corrosion-resistant yellow coating according to claim 3, characterized in that, The microwave reactor has a frequency of 2.45 GHz and a power of 800 W; the reaction temperature of the first solution and the second solution is 60~90℃ and the reaction time is 10~30 min.

6. The method for preparing the high-chroma corrosion-resistant yellow coating according to claim 3, characterized in that, The solvent of the third solution is tris(hydroxymethyl)aminomethane hydrochloride buffer, and the concentration of polydopamine in the third solution is 1-2 mg / mL; the mass concentration of the bismuth vanadate precursor dispersed in the third solution is 100-300 g / L; after dispersing the bismuth vanadate precursor in the third solution, it is shaken at 40-60°C for 1-3 h; the mass ratio of sodium alginate to the bismuth vanadate precursor is 1.2-2:100; the concentration of the calcium chloride solution is 0.1-0.25 mol / L, and the volume ratio of the calcium chloride solution to the third solution is 0.25-3.5:

100.

7. The method for preparing the high-chroma corrosion-resistant yellow coating according to claim 3, characterized in that, The solid is heat-cured by first heating it to 250-300℃ at a rate of 3-7℃ / min and holding it at that temperature for 20-50 minutes, and then heating it to 400-450℃ at a rate of 7-10℃ / min and holding it at that temperature for 5-20 minutes.

8. The method for preparing the high-chroma corrosion-resistant yellow coating according to claim 3, characterized in that, The premixing process involves stirring at a speed of 1200-1500 rpm for 10-30 minutes, while the mixing process involves stirring at a speed of 400-600 rpm for 15-45 minutes.

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