Water-based environment-friendly anticorrosive paint and preparation method thereof

Abstract

The invention discloses a water-based environment-friendly anticorrosive coating and a preparation method thereof, and belongs to the field of anticorrosive coatings. The coating is formed by taking a silicon-phosphorus hybrid acrylate copolymer and a fluorine-zinc hybrid acrylate copolymer as main film-forming substances and cooperating with auxiliaries such as deionized water and ethylene glycol butyl ether and fillers such as zinc phosphate and mica iron oxide. Wherein the silicon-phosphorus hybrid acrylate copolymer is prepared by carrying out free radical copolymerization on a double-bond-containing silicon-phosphorus hybrid monomer and an acrylate monomer, and is formed through water phase precipitation and vacuum drying. The preparation method of the coating comprises the following steps: premixing the two copolymers with the deionized water and the ethylene glycol monobutyl ether, adding the dispersing agent, the defoaming agent and the flatting agent for high-speed dispersion, adding the filler for continuous dispersion, adjusting the viscosity and the pH value, adding the preservative, uniformly stirring, and filtering to obtain the coating. The coating has high weather resistance, strong corrosion resistance and good constructability, meets the environmental protection requirement, and is suitable for long-acting protection of metal substrates.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion coating technology, specifically to a water-based environmentally friendly anti-corrosion coating and its preparation method. Background Technology

[0002] Waterborne anti-corrosion coatings, as a replacement for traditional solvent-based coatings, are widely used in the protection of metal substrates due to their low volatile organic compound emissions, safe application, and good film-forming properties. However, with the increasing complexity of industrial environments and the upgrading of environmental standards, the performance limitations of traditional waterborne anti-corrosion coatings are becoming increasingly apparent. Traditional products mostly use acrylic emulsions, epoxy emulsions, or alkyd resins as film-forming substances. Their molecular structures lack highly efficient anti-corrosion active groups and weather-resistant functional groups, leading to molecular chain breakage under long-term ultraviolet radiation, resulting in yellowing, chalking, and other aging phenomena, severely shortening their service life. At the same time, the interfacial bonding with the metal substrate is weak, making it difficult to form chemical bonds, often resulting in coating peeling and blistering, failing to meet the requirements of heavy-duty anti-corrosion scenarios. In addition, the anti-corrosion performance of traditional waterborne coatings mainly relies on physical shielding, with insufficient coverage of active protection mechanisms such as corrosion inhibition and cathodic protection on metal surfaces. Their neutral salt spray test life is generally low, making them unsuitable for harsh environments such as marine and chemical plants.

[0003] Existing improvement technologies for waterborne anti-corrosion coatings mostly focus on resin modification or the addition of functional fillers. For example, some solutions use silane coupling agents to surface-treat the resin in an attempt to improve the coating's weather resistance; other studies have attempted to introduce fluorocarbon segments or zinc compounds to enhance hydrophobic properties or sacrifice anodic protection. However, such improvements still have significant drawbacks: silane modification is prone to uneven dispersion of molecular segments due to incomplete hydrolysis and condensation reactions, resulting in poor compatibility with waterborne resins, which in turn increases the system viscosity and affects film uniformity; while fluorocarbon modification can reduce surface energy and improve hydrophobicity, the high crystallinity of perfluoroalkyl segments can deteriorate the resin's processing performance, requiring the addition of large amounts of dispersants or solvents, which contradicts the initial intention of environmental protection; although the introduction of zinc compounds can provide cathodic protection, their covalent bonding ability with the resin matrix is ​​limited, and zinc ions are easily lost due to water penetration during long-term use, resulting in insufficient anti-corrosion effectiveness. In addition, traditional modification processes often rely on multi-step emulsification or high-temperature polymerization, which not only increases production energy consumption and equipment requirements, but may also lead to a decrease in product batch stability due to fluctuations in reaction conditions, making it difficult to meet the needs of large-scale industrial production.

[0004] Against this backdrop, the development of a water-based, environmentally friendly anti-corrosion coating that combines high weather resistance, strong corrosion resistance, and good workability has become an urgent industry need. The shortcomings of traditional solutions mainly stem from defects in the molecular structure design of film-forming substances. Single functional segments cannot simultaneously meet the multiple requirements of weather resistance, corrosion resistance, and film formation, and their synergistic effects with fillers have not been fully explored. Therefore, it is necessary to construct multifunctional composite film-forming substances through molecular design, organically combining weather-resistant functional groups, anti-corrosion active groups, and flexible film-forming segments to form a multi-layered protection system of "chemical bonding-physical shielding-sacrificial anode." Simultaneously, the compatibility of supporting additives and fillers should be optimized to improve the coating's ease of application and long-term stability, ultimately achieving the goal of long-term protection for water-based anti-corrosion coatings in harsh environments. Summary of the Invention

[0005] The purpose of this invention is to provide a water-based environmentally friendly anti-corrosion coating and its preparation method, which solves the technical problems of poor weather resistance, insufficient anti-corrosion performance and weak adhesion to metal substrates of existing water-based anti-corrosion coatings.

[0006] The present invention achieves the above objectives through the following technical solutions: A water-based environmentally friendly anti-corrosion coating, comprising the following raw materials in parts by weight: Silicon-phosphorus hybrid acrylate copolymer: 300-500 parts by weight; Fluoro-zinc hybrid acrylate copolymer: 200-400 parts by weight; Deionized water: 150-250 parts by weight; Ethylene glycol butyl ether: 30-80 parts by weight; Polycarboxylate dispersant: 20-50 parts by weight; Organosilicon defoamer: 1-5 parts by weight; Acrylic leveling agent: 3-10 parts by weight; Zinc phosphate: 50-100 parts by weight; Mica iron oxide: 80-150 parts by weight; Iron oxide red: 30-60 parts by weight; Polyurethane thickener: 5-20 parts by weight; Isothiazolinone preservative: 1-3 parts by weight; The preparation method of the silicon-phosphorus hybrid acrylate copolymer includes: A1, adding γ-methacryloyloxypropyltrimethoxysilane and diethyl allyl phosphate to deionized water, adding ammonium persulfate aqueous solution dropwise under stirring, and reacting at 74-76℃; then adding butyl acrylate and methyl methacrylate, and continuing the reaction at 80-84℃; A2, after the reaction is completed, precipitating the product with ethanol, filtering, and vacuum drying at 50-52℃.

[0007] In this invention, the preparation mechanism of the silicon-phosphorus hybrid acrylate copolymer originates from the synergistic effect of free radical copolymerization and molecular segment design. First, γ-methacryloyloxypropyltrimethoxysilane and allyl phosphate diethyl ester undergo free radical polymerization in an aqueous system using ammonium persulfate as an initiator. The vinyl double bond in the γ-methacryloyloxypropyltrimethoxysilane molecule is attacked by free radicals generated from the decomposition of the initiator, forming an active center. This center copolymerizes with the double bond of allyl phosphate diethyl ester, generating a primary copolymer containing siloxane and phosphate segments. Subsequently, butyl acrylate and methyl methacrylate are added as flexible segment monomers. Their double bonds continue to react with the active center of the primary copolymer, forming a triblock copolymer with a "siloxane hard segment - phosphate polar segment - acrylate soft segment" structure through free radical chain growth and termination. During the reaction, the aqueous environment provides good dissolution and diffusion conditions for the monomers. The sulfate radicals generated by the decomposition of ammonium persulfate act as initiators, ensuring the controllability of the polymerization reaction. The temperature is controlled in the range of 74-76℃ and 80-84℃, which not only ensures the effective decomposition rate of the initiator, but also avoids chain transfer side reactions caused by high temperature. Finally, through ethanol precipitation and vacuum drying, a silicon-phosphorus hybrid acrylate copolymer with regular molecular chain structure and uniform functional group distribution is obtained.

[0008] According to a preferred embodiment of the present invention, in step A1, the reaction time at 74-76°C is 2-4 hours; the reaction time at 80-84°C is continued for 4-6 hours.

[0009] According to a preferred embodiment of the present invention, in step A2, the vacuum drying time at 50-52°C is 12-14 hours.

[0010] According to a preferred embodiment of the present invention, the preparation method of the fluorozinc hybrid acrylate copolymer includes: B1, adding perfluorooctyl acrylate and zinc acrylate to N-methylpyrrolidone, purging with nitrogen to remove oxygen, then adding dropwise an acetone solution of 2,2'-azobisisobutyronitrile, and reacting at 64-66°C; then adding hydroxyethyl acrylate, and heating to 74-76°C to continue the reaction; B2, after the reaction is completed, pouring the product into acetone to precipitate, centrifuging to separate, and vacuum drying at 60-64°C.

[0011] In this invention, the preparation of fluorozinc hybrid acrylate copolymers is based on a controlled free radical polymerization mechanism and the directional introduction of functional groups. Perfluorooctyl acrylate and zinc acrylate are free radical copolymerized in N-methylpyrrolidone solvent using 2,2'-azobisisobutyronitrile as an initiator. Due to its strong electronegativity and hydrophobicity, the perfluoroalkyl segments of perfluorooctyl acrylate have low double bond reactivity and require slow initiation by free radicals generated from the decomposition of the initiator to copolymerize with the double bonds of zinc acrylate, forming a copolymer intermediate containing fluorocarbon segments and zinc ion segments. Subsequently, hydroxyethyl acrylate is added as a hydroxyl-containing crosslinking monomer, whose double bonds continue to react with the active centers of the intermediate, forming a gradient structure copolymer through gradual free radical chain growth. During the reaction, nitrogen deoxygenation avoids the quenching effect of oxygen on free radicals, ensuring the continuity of the polymerization reaction. The design of raising the temperature from 64-66℃ to 74-76℃ takes into account the slow initiation characteristics of perfluoroalkyl monomers and the fast reaction activity of hydroxyethyl acrylate. Finally, through acetone precipitation and centrifugation, a fluorozinc hybrid acrylate copolymer with gradient molecular chain distribution and synergistic effect of functional groups is obtained.

[0012] According to a preferred embodiment of the present invention, in step B1, the reaction time is 3-5 hours at 64-66°C; the reaction time is continued at 74-76°C for 2-4 hours.

[0013] According to a preferred embodiment of the present invention, in step B2, the vacuum drying time at 60-64°C is 8-10 hours.

[0014] This invention also provides a method for preparing the aforementioned water-based environmentally friendly anti-corrosion coating, comprising the following steps: S1. Add the silicon-phosphorus hybrid acrylate copolymer, the fluorine-zinc hybrid acrylate copolymer, the ethylene glycol butyl ether, and deionized water to a high-speed disperser for premixing; S2. Add polycarboxylate dispersant, silicone defoamer, and acrylate leveling agent, and disperse after increasing the rotation speed; S3. Finally, add zinc phosphate, mica iron oxide, and iron oxide red, and continue to disperse; add polyurethane thickener, and adjust the pH to 8.0-8.2 with ammonia; then add isothiazolinone preservative and stir until uniform; finally, filter.

[0015] In this invention, the preparation mechanism of the water-based environmentally friendly anti-corrosion coating is a synergistic process of film-forming substances, fillers, and additives, forming a multi-protective system through physical mixing and chemical cross-linking. In the premixing stage, silicon-phosphorus hybrid acrylate copolymer and fluorine-zinc hybrid acrylate copolymer serve as the main film-forming components, dispersed into a uniform emulsion with the assistance of deionized water and ethylene glycol butyl ether. Ethylene glycol butyl ether reduces the surface tension of the system, promoting the wetting compatibility of the copolymer with water. In the high-speed dispersion stage, polycarboxylate dispersant stabilizes filler particles through electrostatic adsorption and steric hindrance, organosilicon defoamer eliminates bubbles in the system, and acrylate leveling agent adjusts the surface tension, ensuring the leveling and uniformity of the coating during application. In the final dispersion stage, fillers such as zinc phosphate, mica iron oxide, and iron oxide red are uniformly dispersed in the copolymer matrix through mechanical shearing. Polyurethane thickener adjusts the system viscosity through intermolecular hydrogen bonding and association. Ammonia water neutralizes the carboxyl groups in the copolymer, adjusting the pH to a weakly alkaline environment. Isothiazolinone preservative inhibits microbial growth, ensuring the storage stability of the coating. During film formation, hydroxyl and carboxyl groups in the copolymer molecular chains form hydrogen bonds with water. After water evaporates, the molecular chains intertwine to form a continuous film. The siloxane segments of the silicon-phosphorus hybrid copolymer hydrolyze to generate silanol groups, which further condense to form a -Si-O-Si- three-dimensional crosslinked network, improving the coating's density. The zinc ions (Zn) in the fluorine-zinc hybrid copolymer... 2+ The coating, along with phosphate ester groups (derived from the -P(O)(OH)-O- structure of silicon-phosphorus hybrid acrylate copolymers), synergistically acts on the hydroxyl groups (M-OH) on the metal surface, forming a MOP composite chemical bond and passivation film. Specifically, the oxygen atoms of the phosphate ester groups (such as P=O or P-OH) and the O atoms of M-OH are bonded through hydrogen bonds (M-OH…O=P-) or coordination bonds (MOP). Simultaneously, zinc ions are adsorbed near the M-OH through electrostatic adsorption and form a complex (MO-Zn-OP) with the oxygen atoms of the phosphate ester groups. The synergistic effect of both ultimately constructs an "MOP" composite bonding system on the metal surface. The MOP bonds strengthen the adhesion between the coating and the substrate, while the complexation effect of zinc ions and the passivation effect of the phosphate ester groups together form a passivation film that inhibits electrochemical corrosion. Filler particles fill the pores of the film layer, blocking the penetration of corrosive media. Multiple mechanisms work together to construct a multi-layered protection system of "chemical bonding-physical shielding-sacrificial anode," giving the coating both long-lasting corrosion protection, weather resistance, and ease of application.

[0016] According to a preferred embodiment of the present invention, in step S1, the premixing speed is 500-540 r / min, and the premixing time is 10-20 min.

[0017] According to a preferred embodiment of the present invention, in step S2, the rotation speed is increased to 1500-1600 r / min, and the dispersion time is 30-40 min.

[0018] According to a preferred embodiment of the present invention, in step S3, the dispersion time is 25-30 min and the stirring time is 5-10 min.

[0019] The beneficial effects of this invention are as follows: This invention's water-based environmentally friendly anti-corrosion coating achieves significant improvements in weather resistance, corrosion resistance, and environmental friendliness during application through molecular structure design and component synergy. Its core film-forming substances, a silicon-phosphorus hybrid acrylate copolymer and a fluorine-zinc hybrid acrylate copolymer, respectively construct a dual weather-resistant system of "chemical crosslinking-hydrophobic protection" through a three-dimensional crosslinked network formed by the hydrolysis of siloxane groups and the low surface energy characteristics of fluorocarbon segments. This effectively blocks UV attack and water vapor penetration, significantly delaying yellowing and chalking of the coating and improving long-term outdoor stability. In terms of the anti-corrosion mechanism, the phosphate groups of the silicon-phosphorus hybrid copolymer react with the hydroxyl groups on the metal surface to form stable chemical bonds, simultaneously generating a passivation film to inhibit initial corrosion; the zinc ions of the fluorine-zinc hybrid copolymer are released through chelation, providing passive protection; combined with the dense physical barrier formed by fillers such as zinc phosphate and mica iron oxide, a synergistic "active-passive" protection is achieved, greatly enhancing corrosion resistance in harsh environments. In terms of application, the flexible acrylate segments of the two copolymers give the coating good film-forming properties, while ethylene glycol butyl ether adjusts the viscosity of the system. Combined with polyurethane thickener, the application viscosity is precisely controlled to ensure the smoothness of brushing, spraying and other processes. Water is used as the only solvent, with no volatile organic compounds or heavy metals added. There is no irritating odor during application, and the storage stability is excellent, meeting the requirements of green construction and environmental protection. Detailed Implementation

[0020] The following detailed embodiments are only used to further illustrate this application and should not be construed as limiting the scope of protection of this application. Those skilled in the art can make some non-essential improvements and adjustments to this application based on the above application content.

[0021] The following is information on domestic suppliers of the relevant equipment and materials: γ-Methacryloxypropyltrimethoxysilane was purchased from Chenguang New Materials Co., Ltd. Diethyl allyl phosphate was purchased from Hubei Xingfa Chemical Group Co., Ltd. Ammonium persulfate was purchased from Tianjin Jinniu Power Materials Co., Ltd. Butyl acrylate was purchased from Zibo Qixiang Tengda Chemical Co., Ltd. Methyl methacrylate was purchased from Wanhua Chemical Group Co., Ltd. Ethanol was purchased from COFCO Biotechnology Co., Ltd. The deionized water was purchased from Shanghai Yili Pure Water Equipment Co., Ltd. Ethylene glycol butyl ether was purchased from Jiangsu Yida Chemical Co., Ltd. The polycarboxylate dispersant was purchased from Jiangsu Hehai Nanotechnology Co., Ltd. The silicone defoamer was purchased from Nanjing Sixin Technology Application Research Institute Co., Ltd. Acrylic leveling agent was purchased from Shanghai Yuanhe Chemical Co., Ltd. Zinc phosphate was purchased from Yunnan Tin Industry Co., Ltd. Mica iron oxide was purchased from Lingshou County Jinyuan Mining Co., Ltd. Iron oxide red was purchased from Shanghai Yipin Pigment Co., Ltd. The polyurethane thickener was purchased from Shanghai Baolijia New Materials Co., Ltd. The isothiazolinone preservative was purchased from Jiangsu Kangtai Environmental Protection Technology Co., Ltd. Perfluorooctyl acrylate was purchased from Zhejiang Juhua Co., Ltd. Zinc acrylate was purchased from Jiangsu Huangma Technology Co., Ltd. N-methylpyrrolidone was purchased from Shenzhen Capchem Technology Co., Ltd. Nitrogen was purchased from Yingde Gas Investment Co., Ltd. 2,2'-Azobisisobutyronitrile was purchased from Jiangsu Hehai Nanotechnology Co., Ltd. Acetone was purchased from Jiangsu Huachang Chemical Co., Ltd. Hydroxyethyl acrylate was purchased from Shanghai Huayi Acrylic Acid Co., Ltd. The high-speed disperser was purchased from Shanghai Rute Electromechanical Equipment Co., Ltd. The acrylic emulsion coating was purchased from Beijing Dongfang Chennuo Chemical Technology Co., Ltd.

[0022] Example 1

[0023] Preparation of silicon-phosphorus hybrid acrylate copolymer: 100g of γ-methacryloxypropyltrimethoxysilane and 50g of allyl phosphate were added to 150g of deionized water and placed in a water bath equipped with a magnetic stirrer. The mixture was stirred at a rate of 200r / min until homogeneous. After the materials were completely dissolved, the water temperature was raised to 75℃ and kept stable. 10g of a 20% ammonium persulfate aqueous solution was added dropwise at a uniform rate over 1 hour, with continuous stirring during the addition to ensure uniform reaction. After the addition was completed, the reaction was maintained at 75℃ for 2.5 hours, during which the reaction temperature was recorded every 30 minutes and the water bath temperature was adjusted to maintain a constant temperature. Subsequently, the reaction system temperature was raised to 82℃, and 80g of butyl acrylate and 20g of methyl methacrylate were added at a uniform rate over 30 minutes. The reaction was maintained at 82℃ for 5 hours, with the stirring rate maintained at 300r / min to ensure thorough mixing of the materials. After the reaction was completed, the product was transferred to a beaker, 200g of ethanol was added, and the mixture was stirred for 10 minutes and then allowed to stand for 30 minutes to allow the copolymer to precipitate fully. The precipitate was then collected by filtering with qualitative filter paper and placed in a vacuum drying oven. The precipitate was dried for 13 hours at 51°C and a vacuum of -0.09MPa to obtain a solid silicon-phosphorus hybrid acrylate copolymer.

[0024] Preparation of fluorozinc hybrid acrylate copolymer: 80g of perfluorooctyl acrylate and 30g of zinc acrylate were added to 120g of N-methylpyrrolidone and placed in a reaction vessel equipped with a mechanical stirrer and a reflux condenser. The mixture was stirred at 150r / min until homogeneous. High-purity nitrogen was first purged for 15 minutes to remove air from the vessel. Then, under nitrogen protection, the reaction vessel was heated to 65℃ and kept stable. 5g of a 0.1% (w / w) acetone solution of 2,2'-azobisisobutyronitrile was added dropwise at a rate of 2 drops / second using a constant-pressure dropping funnel. After the addition was complete, the reaction was maintained at 65℃ for 4 hours, with the stirring rate kept at 200r / min. Then, the reaction temperature was raised to 75℃, and 20g of hydroxyethyl acrylate was added uniformly over 30 minutes. The reaction was maintained at 75℃ for another 3 hours. Samples were taken every hour to observe the material state and record the reaction progress. After the reaction was completed, the product was poured into 100g of acetone, stirred for 5 minutes, and then allowed to stand for 20 minutes to allow the copolymer to precipitate. The product was then centrifuged at 4000r / min for 10 minutes, and the lower precipitate was collected and placed in a vacuum drying oven. The product was dried at 62℃ and a vacuum of -0.08MPa for 9 hours to obtain the solid fluorozinc hybrid acrylate copolymer.

[0025] Preparation of water-based environmentally friendly anti-corrosion coating: 400g of the prepared silicon-phosphorus hybrid acrylate copolymer, 300g of fluorine-zinc hybrid acrylate copolymer, 200g of deionized water, and 50g of ethylene glycol butyl ether were added sequentially to a high-speed disperser. The mixture was premixed at a speed of 520r / min for 15 minutes to ensure that the components were initially dispersed evenly. Then, 30g of polycarboxylate dispersant, 2g of silicone defoamer, and 5g of acrylate leveling agent were added. The speed of the disperser was increased to 1550r / min, and dispersion was continued for 35 minutes. During this period, the system status was observed, and the speed was adjusted as needed to ensure that there were no residual bubbles and that the filler was evenly dispersed. Finally, 80g of zinc phosphate, 120g of mica iron oxide, and 40g of iron oxide red were added to the dispersion system in three portions. After each addition, the dispersion was maintained at 1550r / min for 10 minutes. After all the ingredients were added, the dispersion was continued for 28 minutes. Then, 10g of polyurethane thickener was diluted with a small amount of deionized water and added slowly while stirring at 300r / min for 10 minutes to adjust the viscosity of the system to 60s at a Forte 4 cup (25℃). The pH was adjusted dropwise to 8.1 with ammonia water. After stirring for 5 minutes, the mixture was filtered through a 100-mesh filter cloth, and the filtrate was collected to obtain the water-based environmentally friendly anti-corrosion coating.

[0026] Example 2

[0027] The specific implementation method is the same as in Example 1, except that the preparation of the silicon-phosphorus hybrid acrylate copolymer is as follows: 120g of γ-methacryloxypropyltrimethoxysilane and 60g of allyl phosphate are added to 180g of deionized water, and 12g of 20% ammonium persulfate aqueous solution is added dropwise under stirring. The reaction is carried out at 75°C for 3h. Then, 90g of butyl acrylate and 25g of methyl methacrylate are added, and the reaction is continued at 82°C for 5.5h. After the reaction is completed, the product is precipitated with 220g of ethanol, filtered, and vacuum dried at 51°C for 13h to obtain the silicon-phosphorus hybrid acrylate copolymer. Preparation of fluorozinc hybrid acrylate copolymer: 90g of perfluorooctyl acrylate and 35g of zinc acrylate were added to 130g of N-methylpyrrolidone. After purging with nitrogen for 15min to remove oxygen, 6g of 0.1% acetone solution of 2,2'-azobisisobutyronitrile was added dropwise, and the reaction was carried out at 65℃ for 4.5h. Then, 25g of hydroxyethyl acrylate was added, and the temperature was raised to 75℃ to continue the reaction for 3.5h. After the reaction was completed, the product was poured into 110g of acetone to precipitate, centrifuged, and dried under vacuum at 62℃ for 9h to obtain the fluorozinc hybrid acrylate copolymer. Preparation of water-based environmentally friendly anti-corrosion coating: 450g of silicon-phosphorus hybrid acrylate copolymer, 350g of fluorine-zinc hybrid acrylate copolymer, 220g of deionized water, and 60g of ethylene glycol butyl ether were added to a high-speed disperser and premixed at 530r / min for 18min; 40g of polycarboxylate dispersant, 3g of silicone defoamer, and 7g of acrylate leveling agent were added, and the speed was increased to 1580r / min for dispersion for 38min; finally, 90g of zinc phosphate, 130g of mica iron oxide, and 50g of iron oxide red were added, and dispersion was continued for 29min; 15g of polyurethane thickener was added to adjust the viscosity to Forte 4 cup (25℃) for 60s, the pH was adjusted to 8.1 with ammonia water, and the coating was obtained by filtration through a 100-mesh filter.

[0028] Example 3

[0029] The specific implementation method is the same as in Example 1, except that the preparation of the silicon-phosphorus hybrid acrylate copolymer is as follows: 80g of γ-methacryloxypropyltrimethoxysilane and 40g of allyl phosphate are added to 120g of deionized water, and 8g of 20% ammonium persulfate aqueous solution is added dropwise under stirring. The reaction is carried out at 75°C for 2h. Then, 70g of butyl acrylate and 15g of methyl methacrylate are added, and the reaction is continued at 82°C for 4.5h. After the reaction is completed, the product is precipitated with 180g of ethanol, filtered, and vacuum dried at 51°C for 13h to obtain the silicon-phosphorus hybrid acrylate copolymer. Preparation of fluorozinc hybrid acrylate copolymer: 70g of perfluorooctyl acrylate and 25g of zinc acrylate were added to 110g of N-methylpyrrolidone. After purging with nitrogen for 15min to remove oxygen, 4g of 0.1% acetone solution of 2,2'-azobisisobutyronitrile was added dropwise, and the reaction was carried out at 65℃ for 3.5h. Then, 15g of hydroxyethyl acrylate was added, and the temperature was raised to 75℃ to continue the reaction for 2.5h. After the reaction was completed, the product was poured into 90g of acetone to precipitate, centrifuged, and dried under vacuum at 62℃ for 9h to obtain the fluorozinc hybrid acrylate copolymer. Preparation of water-based environmentally friendly anti-corrosion coating: 350g of silicon-phosphorus hybrid acrylate copolymer, 250g of fluorine-zinc hybrid acrylate copolymer, 180g of deionized water, and 40g of ethylene glycol butyl ether were added to a high-speed disperser and premixed at 510r / min for 12min; 25g of polycarboxylate dispersant, 1g of silicone defoamer, and 4g of acrylate leveling agent were added, and the speed was increased to 1520r / min for dispersion for 32min; finally, 70g of zinc phosphate, 110g of mica iron oxide, and 30g of iron oxide red were added, and dispersion was continued for 26min; 8g of polyurethane thickener was added to adjust the viscosity to 60s at Forte 4 cup (25℃), the pH was adjusted to 8.1 with ammonia water, and the coating was obtained by filtration through a 100-mesh filter.

[0030] Comparative Example 1 The specific implementation method is the same as in Example 1, except that the preparation of the water-based environmentally friendly anti-corrosion coating is as follows: 300g of fluorine-zinc hybrid acrylate copolymer, 200g of deionized water, and 50g of ethylene glycol butyl ether are added to a high-speed disperser and premixed at 520r / min for 15min; 30g of polycarboxylate dispersant, 2g of silicone defoamer, and 5g of acrylate leveling agent are added, and the speed is increased to 1550r / min for dispersion for 35min; finally, 80g of zinc phosphate, 120g of mica iron oxide, and 40g of iron oxide red are added, and dispersion is continued for 28min; 10g of polyurethane thickener is added to adjust the viscosity to 60s at Forte 4 cup (25℃), the pH is adjusted to 8.1 with ammonia water, and the coating is obtained by filtration through a 100-mesh filter (the control sample is a coating containing only fluorine-zinc hybrid copolymer).

[0031] Comparative Example 2 The specific implementation method is the same as in Example 1, except that the preparation of the water-based environmentally friendly anti-corrosion coating is as follows: 400g of silicon-phosphorus hybrid acrylate copolymer, 200g of deionized water, and 50g of ethylene glycol butyl ether are added to a high-speed disperser and premixed at 520r / min for 15min; 30g of polycarboxylate dispersant, 2g of silicone defoamer, and 5g of acrylate leveling agent are added, and the speed is increased to 1550r / min for dispersion for 35min; finally, 80g of zinc phosphate, 120g of mica iron oxide, and 40g of iron oxide red are added, and dispersion is continued for 28min; 10g of polyurethane thickener is added to adjust the viscosity to 60s at Forte 4 cup (25℃), the pH is adjusted to 8.1 with ammonia water, and the coating is obtained by filtration through a 100-mesh filter (the control sample is a coating containing only silicon-phosphorus hybrid copolymer).

[0032] Comparative Example 3 The specific implementation method is the same as in Example 1, except that the preparation of the water-based environmentally friendly anti-corrosion coating is as follows: 400g of ordinary acrylic emulsion (replacing the two modified copolymers), 200g of deionized water, and 50g of ethylene glycol butyl ether are added to a high-speed disperser and premixed at 520r / min for 15min; 30g of polycarboxylate dispersant, 2g of silicone defoamer, and 5g of acrylic ester leveling agent are added, and the speed is increased to 1550r / min for dispersion for 35min; finally, 80g of zinc phosphate, 120g of mica iron oxide, and 40g of iron oxide red are added, and dispersion is continued for 28min; 10g of polyurethane thickener is added to adjust the viscosity to 60s at Forte 4 cup (25℃), the pH is adjusted to 8.1 with ammonia water, and the coating is obtained by filtration through a 100-mesh filter (the control sample is an ordinary acrylic emulsion coating).

[0033] Performance testing The water-based environmentally friendly anti-corrosion coatings prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests according to the following methods: Adhesion Test: According to GB / T 9286-2021 "Paints and Varnishes - Cross-cut Test", the coating was applied to a clean steel plate (surface treated with Sa2.5 grade sandblasting to remove rust). After curing for 7 days, a cross-cut tester (blade spacing 2mm, blade angle 30°±2°) was used to draw a grid on the coating surface. During the cross-cut test, the blade should be kept perpendicular to the test plate surface, and uniform pressure (approximately 5N) should be applied to ensure the grid lines are clear and non-overlapping. After the cross-cut test is completed, a 25mm wide transparent tape (adhesive strength ≥20N / 25mm) was applied perpendicularly along the grid lines, covering the entire cross-cut area. After holding for 10±2 seconds, the tape was quickly removed at a 45° angle. Observe and measure the area of ​​coating peeling: Level 0 is no peeling; Level 1 is peeling area <5%; Level 2 is 5%~15%; Level 3 is 15%~35%; Level 4 is 35%~65%; Level 5 is >65% (the percentage of peeling area is calculated by accumulating the peeling surface of a single grid).

[0034] Neutral salt spray test: The coating is applied to Q235 steel plate (surface treatment is sandblasting and rust removal Sa2.5 grade), cured for 7 days, and then placed in a salt spray chamber (temperature 35℃±2℃, salt spray deposition 1.0-2.0mL / (80cm²·h)). After continuous spraying for 2000 hours, the coating condition (blistering, peeling, and rust) is observed.

[0035] Ultraviolet aging test: conducted according to GB / T 1865-2009 "Artificial climate aging and artificial radiation exposure of paints and varnishes". The coating was applied to an aluminum plate (surface treatment was anodized), cured for 7 days, and then placed in an ultraviolet aging chamber (UVB-313 lamp, irradiance 0.51W / m², temperature 60℃±2℃, 4h light exposure + 4h condensation cycle). After 500 hours of testing, the coating gloss retention rate (ratio to initial gloss value) and color difference ΔE (measured using a colorimeter) were tested.

[0036] VOC content determination: According to GB / T 23986.2-2023 "Determination of Volatile Organic Compounds (VOCs) in Paints and Varnishes - Gas Chromatography", take 10g of paint sample (accurate to 0.1g), add 50mL of carbon disulfide (chromatographic grade), and ultrasonically extract in an ultrasonic cleaner for 30 minutes (temperature 25℃, power 200W), shaking once every 10 minutes during extraction. After extraction, filter (0.45μm organic phase filter membrane), and collect the filtrate as the sample solution. Use a gas chromatograph (equipped with an FID detector), a DB-5MS capillary column (60m×0.25mm×1.0μm), an injection port temperature of 200℃, a detector temperature of 250℃, and a programmed temperature increase (initial 50℃, hold for 2 minutes; increase to 200℃ at 10℃ / min, hold for 10 minutes). The carrier gas is nitrogen (purity ≥99.999%), and the flow rate is 1.0mL / min. The injection volume was 1 μL (splitless injection). The total VOC content (as carbon, in g / L) was calculated using the external standard method.

[0037] Storage stability test: Conducted according to GB / T 6753.3-1986 "Test Method for Storage Stability of Coatings". Seal the coating sample and place it in a constant temperature chamber at (25℃±2℃). After standing for 30 days, observe whether there is any layering, clumping or thickening, and evaluate the stability (pass: no abnormality; fail: layering or clumping occurs).

[0038] Performance test results: Table 1: Performance test results of each embodiment and comparative example

[0039] As can be seen from Table 1, Examples 1-3 effectively solved the technical problems of poor weather resistance, insufficient anti-corrosion performance and weak adhesion to metal substrates of existing waterborne anti-corrosion coatings through the synergistic design of two modified copolymers (silicon-phosphorus hybrid acrylate copolymer and fluorine-zinc hybrid acrylate copolymer).

[0040] Regarding adhesion, the cross-cut adhesion test results of Examples 1-3 were all grade 0 (no peeling), significantly better than Comparative Example 1 (fluorine-zinc hybrid copolymer only, grade 1), Comparative Example 2 (silicon-phosphorus hybrid copolymer only, grade 1), and Comparative Example 3 (ordinary acrylic emulsion, grade 2). This is because the phosphate ester groups in the silicon-phosphorus hybrid copolymer molecular chain can undergo a condensation reaction with the hydroxyl groups on the surface of the metal substrate to form stable MOP chemical bonds, enhancing the interfacial bonding force; at the same time, the zinc ions in the fluorine-zinc hybrid copolymer bind to the copolymer molecular chain through chelation, forming an "anchoring" structure between the coating and the substrate, further improving adhesion. The synergistic effect of both makes the coating and the metal substrate bond more tightly.

[0041] Regarding corrosion resistance, the neutral salt spray test (2000h) results of Examples 1-3 showed no blistering or peeling, significantly superior to Comparative Example 1 (fluorine-zinc hybrid copolymer only, slight surface blistering <2%), Comparative Example 2 (silicon-phosphorus hybrid copolymer only, local surface peeling <3%), and Comparative Example 3 (ordinary acrylic emulsion, large-area blistering >10%). The siloxane segments of the silicon-phosphorus hybrid copolymer form a three-dimensional cross-linked network after hydrolysis, improving the coating's density and blocking the penetration of corrosive media. Zinc ions in the fluorine-zinc hybrid copolymer are released at coating damage sites, acting as sacrificial anodes to protect the metal substrate, overcoming the limitations of traditional physical shielding corrosion protection. Fillers such as zinc phosphate and mica iron oxide further fill the coating pores, forming a multi-layered protection system of "chemical bonding-physical shielding-sacrificial anode," collectively enhancing the corrosion resistance over time.

[0042] In terms of weather resistance, Examples 1-3 exhibited a gloss retention rate >80% and a color difference ΔE <2 after UV aging (500h), significantly superior to Comparative Example 1 (fluorine-zinc hybrid copolymer only, gloss retention rate 70%, color difference ΔE = 3.2), Comparative Example 2 (silicon-phosphorus hybrid copolymer only, gloss retention rate 75%, color difference ΔE = 2.8), and Comparative Example 3 (ordinary acrylic emulsion, gloss retention rate 55%, color difference ΔE = 6.5). The siloxane segments of the silicon-phosphorus hybrid copolymer form a stable -Si-O-Si- network through hydrolysis and condensation, effectively resisting the attack of UV light on the resin backbone and inhibiting molecular chain breakage and yellowing. The fluorocarbon segments of the fluorine-zinc hybrid copolymer have extremely low surface energy, forming a hydrophobic barrier on the coating surface, reducing the penetration of water vapor and oxygen, and lowering the photoaging rate. The synergistic effect of both allows the coating to maintain good color stability and surface integrity even under long-term light exposure.

[0043] Furthermore, the VOC content of Examples 1-3 (32-38 g / L) and their storage stability (no stratification or clumping after 30 days) are superior to Comparative Example 3 (ordinary acrylic emulsion, slight stratification after 30 days), further demonstrating their environmental friendliness and ease of application. In summary, Examples 1-3, through the molecular design and synergistic effect of the two modified copolymers, comprehensively solve the core defects of existing water-based anti-corrosion coatings, achieving a synergistic improvement in weather resistance, corrosion resistance, and application performance.

[0044] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A water-based environmentally friendly anti-corrosion coating, characterized in that, Including the following parts by weight of raw materials: Silicon-phosphorus hybrid acrylate copolymer: 300-500 parts by weight; Fluoro-zinc hybrid acrylate copolymer: 200-400 parts by weight; Deionized water: 150-250 parts by weight; Ethylene glycol butyl ether: 30-80 parts by weight; Polycarboxylate dispersant: 20-50 parts by weight; Organosilicon defoamer: 1-5 parts by weight; Acrylic leveling agent: 3-10 parts by weight; Zinc phosphate: 50-100 parts by weight; Mica iron oxide: 80-150 parts by weight; Iron oxide red: 30-60 parts by weight; Polyurethane thickener: 5-20 parts by weight; Isothiazolinone preservative: 1-3 parts by weight; The preparation method of the silicon-phosphorus hybrid acrylate copolymer includes: A1, adding γ-methacryloyloxypropyltrimethoxysilane and diethyl allyl phosphate to deionized water, adding ammonium persulfate aqueous solution dropwise under stirring, and reacting at 74-76℃; then adding butyl acrylate and methyl methacrylate, and continuing the reaction at 80-84℃; A2, after the reaction is completed, precipitating the product with ethanol, filtering, and vacuum drying at 50-52℃.

2. The water-based environmentally friendly anti-corrosion coating according to claim 1, characterized in that, In step A1, the reaction time is 2-4 hours at 74-76℃; the reaction time continues at 80-84℃ for 4-6 hours.

3. The water-based environmentally friendly anti-corrosion coating according to claim 1, characterized in that, In step A2, the vacuum drying time at 50-52℃ is 12-14 hours.

4. The water-based environmentally friendly anti-corrosion coating according to claim 1, characterized in that, The preparation method of the fluorozinc hybrid acrylate copolymer includes: B1, adding perfluorooctyl acrylate and zinc acrylate to N-methylpyrrolidone, purging with nitrogen to remove oxygen, then adding dropwise an acetone solution of 2,2'-azobisisobutyronitrile, and reacting at 64-66℃; then adding hydroxyethyl acrylate, and heating to 74-76℃ to continue the reaction; B2, after the reaction is completed, pouring the product into acetone to precipitate, centrifuging to separate, and vacuum drying at 60-64℃.

5. The water-based environmentally friendly anti-corrosion coating according to claim 4, characterized in that, In step B1, the reaction time is 3-5 hours at 64-66℃; the reaction time is continued at 74-76℃ for another 2-4 hours.

6. The water-based environmentally friendly anti-corrosion coating according to claim 4, characterized in that, In step B2, the vacuum drying time at 60-64℃ is 8-10 hours.

7. A method for preparing a water-based environmentally friendly anti-corrosion coating according to any one of claims 1-6, characterized in that, step include: S1. Add the silicon-phosphorus hybrid acrylate copolymer, the fluorine-zinc hybrid acrylate copolymer, the ethylene glycol butyl ether, and deionized water to a high-speed disperser for premixing; S2. Add polycarboxylate dispersant, silicone defoamer, and acrylate leveling agent, and disperse after increasing the rotation speed; S3. Finally, add zinc phosphate, mica iron oxide, and iron oxide red, and continue to disperse; add polyurethane thickener, and adjust the pH to 8.0-8.2 with ammonia; then add isothiazolinone preservative and stir until uniform; finally, filter.

8. The preparation method according to claim 7, characterized in that, In step S1, the premixing speed is 500-540 r / min, and the premixing time is 10-20 min.

9. The preparation method according to claim 7, characterized in that, In step S2, the rotation speed is increased to 1500-1600 r / min, and the dispersion time is 30-40 min.

10. The preparation method according to claim 7, characterized in that, In step S3, the dispersion time is 25-30 minutes, and the stirring time is 5-10 minutes.

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