Aqueous coating for metallic materials and process of preparation

Abstract

The present application relates to the technical field of water-based coating, and particularly relates to a water-based coating for metal material and a preparation process. The water-based coating for metal material comprises the following raw materials in parts by mass: bisphenol A diglycidyl ether 20-40, trimethylolpropane 1-5, boron trifluoride ether complex 0.1-0.5, polyethylene glycol monomethyl ether 4000 5-15, water-based hydroxyl acrylic resin 30-50, barium sulfate 4-5, nano zinc oxide 1-5, titanium white powder 1-3, polycarboxylate dispersant 0.5-1, activated boron nitride 1-3, water-based amino resin 1-5, defoaming agent 0.5-1.5, anti-settling agent 1-2, ultraviolet light absorber 1-2, acrylate leveling agent 0.1-1, thixotropic agent 1-2, and dimethyl ethanolamine 0.5-1.2. The present application realizes high adhesion of the coating to the metal substrate and long-term corrosion prevention.

Description

Technical Field

[0001] This invention relates to the field of water-based coating technology, and in particular to a water-based coating for metallic materials and its preparation process. Background Technology

[0002] Metallic materials are widely used in industry, but they are prone to electrochemical corrosion when exposed to corrosive environments such as humidity, salt spray, and acids and alkalis, leading to structural failure and safety risks. Water-based coatings are widely used due to their advantages such as low VOCs and environmental friendliness. However, the cross-linked network formed by the curing of traditional epoxy water-based coatings is usually not dense enough, making it difficult to effectively block the penetration of corrosive media such as water and chloride ions. At the same time, the interfacial bonding between the coating and the metal substrate is weak, making it easy to peel off and reducing the protective life.

[0003] Existing waterborne epoxy systems often incorporate active fillers such as zinc powder. However, these fillers are prone to agglomeration, leading to uneven film thickness and the formation of corrosion channels. Furthermore, the poor interfacial compatibility between the resin and inorganic fillers can cause microcracks due to thermal expansion mismatch during long-term service, accelerating aging and failure. Additionally, traditional systems are susceptible to defects such as sagging, pinholes, and bubbles during application, affecting coating continuity and surface integrity.

[0004] Currently, there is great potential in researching how to provide a water-based coating with high adhesion and long-lasting anti-corrosion capabilities to achieve efficient protection of metal substrates. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a water-based coating for metallic materials and its preparation process.

[0006] A water-based coating for metallic materials comprises, by weight, the following raw materials: 20-40 parts bisphenol A diglycidyl ether, 1-5 parts trimethylolpropane, 0.1-0.5 parts boron trifluoride ethyl ether complex, 5-15 parts polyethylene glycol monomethyl ether 4000, 30-50 parts water-based hydroxyl acrylic resin, 4-5 parts barium sulfate, 1-5 parts nano zinc oxide, 1-3 parts titanium dioxide, 0.5-1 part polycarboxylate dispersant, 1-3 parts activated boron nitride, 1-5 parts water-based amino resin, 0.5-1.5 parts defoamer, 1-2 parts anti-settling agent, 1-2 parts ultraviolet absorber, 0.1-1 part acrylate leveling agent, 1-2 parts thixotropic agent, and 0.5-1.2 parts dimethylethanolamine.

[0007] Preferably, the ultraviolet absorber is a benzotriazole ultraviolet absorber.

[0008] Preferably, the anti-settling agent is at least one of organic bentonite and fumed silica.

[0009] Preferably, the acrylate leveling agent is a polyacrylate copolymer solution.

[0010] Preferably, the defoamer is a polyether-modified silicone defoamer.

[0011] Preferably, the thixotropic agent is a polyurethane associative thickener.

[0012] Preferably, activated boron nitride is prepared by the following steps: adding boron nitride nanosheets to an ethanol aqueous solution and stirring for 10-30 min; adding tetraethyl orthosilicate while stirring; continuing to stir for 5-15 min; adjusting the pH of the system to 9-10; stirring at 40-60℃ for 1-3 h; centrifuging; washing; and vacuum drying.

[0013] More preferably, the mass ratio of boron nitride nanosheets to tetraethyl orthosilicate is 5-10:1-3.

[0014] The above-mentioned process for preparing water-based coatings for metallic materials includes the following steps: S1. Under nitrogen protection, bisphenol A diglycidyl ether, trimethylolpropane, and boron trifluoride diethyl ether complex are mixed and stirred at 100-120℃ for 5-15 hours under anhydrous conditions. Polyethylene glycol monomethyl ether 4000 is added, and the mixture is stirred at 130-135℃ for 2-4 hours. The temperature is then lowered to 40-50℃, and triethylamine is added to adjust the system to neutral. Aqueous hydroxyl acrylic resin is added, and the mixture is subjected to high-speed shearing for 5-12 minutes. During the shearing process, water is added to adjust the solid content of the system to 40-48.5%. The mixture is then homogenized and emulsified for 5-10 minutes to obtain the mixture. S2. Barium sulfate, nano zinc oxide, titanium dioxide, polycarboxylate dispersant, activated boron nitride, and water are stirred for 1-2 hours and then ground to obtain a pre-prepared slurry. S3. In sequence, mix the mixture, pre-made slurry, water-based amino resin, defoamer, anti-settling agent, ultraviolet absorber, acrylate leveling agent, thixotropic agent, and dimethylethanolamine evenly, and add water; after coating, cure at 130-145℃ for 20-30 minutes.

[0015] Preferably, in S3, water is added to adjust the viscosity of the system to 2200-2800 mPa•s.

[0016] Compared with existing technologies, the present invention has the following advantages: This invention constructs a branched epoxy system by compounding bisphenol A diglycidyl ether with trimethylolpropane. The branched structure not only effectively reduces chain entanglement and lowers emulsion viscosity, forming a waterborne epoxy emulsion with excellent stability, but also significantly increases the crosslinking density when compounded with waterborne hydroxyl acrylic resin, effectively blocking the penetration of corrosive media. At the same time, it can increase the contact area with the metal substrate, and significantly enhance the interfacial force after curing, effectively solving the problem of interfacial peeling in traditional waterborne epoxy.

[0017] The activated boron nitride used in this invention utilizes tetraethyl orthosilicate to hydrolyze and deposit nano-silica particles on the surface of the sheet-like boron nitride. This process retains the two-dimensional sheet structure while imparting hydrophilicity, effectively improving compatibility and interfacial bonding with the branched epoxy system. Furthermore, it is compounded with nano-zinc oxide, and the sheet structure guides the distribution of zinc oxide to form a composite shielding layer, further hindering the diffusion of corrosive media. Combined with the action of polycarboxylate dispersant, it avoids localized insufficient film thickness and corrosion channels caused by filler agglomeration.

[0018] This invention significantly improves the weather resistance and surface smoothness of the coating, while taking into account environmental protection and construction safety. It achieves high adhesion of the coating to metal substrates, long-term corrosion protection, and stable service performance in complex environments. Moreover, the preparation method is simple, environmentally friendly, and safe, making it suitable for large-scale promotion of industrial metal protection. Attached Figure Description

[0019] Figure 1 This is a comparison chart showing the rate of mass change of the water-based coatings obtained in Example 5 and Comparative Examples 1-2 before and after immersion in water.

[0020] Figure 2 The graph shows a comparison of the adhesion and charge transfer resistance of the water-based coatings obtained in Example 5 and Comparative Examples 1-2. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0023] The following bisphenol A diglycidyl ether (CAS: 1675-54-3) was purchased from Sigma-Aldrich (Shanghai) Trading Co., Ltd. The following trimethylolpropane (CAS: 77-99-6) was purchased from Shanghai Kangtuo Chemical Co., Ltd. The following boron trifluoride diethyl ether complex (CAS: 109-63-7) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The following polyethylene glycol monomethyl ether 4000 (CAS: 9004-74-4, molecular weight 4000) was purchased from Beijing Mairuida Technology Co., Ltd. The following water-based hydroxyl acrylic resin (hydroxyl content 3.9%, non-volatile content 44±2%) was purchased from Guangdong Bangtai New Material Technology Co., Ltd. The following water-based amino resin (MH-7485) was purchased from Jining Tangyi Chemical Co., Ltd., with a solid content of 85±2% and a viscosity of 1000-4000 cps. The following polycarboxylate dispersant was purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd. The Dow Corning 65 Additive used below is from Dow Corning and is used as a polyether-modified silicone defoamer. The UV absorber UV-1130 used below was purchased from Wuhan Shuer Biotechnology Co., Ltd. The BYK-381 used below is from BYK (Germany) and is used as an acrylic leveling agent. The associative polyurethane thickener 7800 used below was purchased from Nanjing Dahai New Material Technology Co., Ltd. and is used as a thixotropic agent.

[0024] Example 1: A water-based coating for metallic materials, comprising the following raw materials: 20g bisphenol A diglycidyl ether, 1g trimethylolpropane, 0.1g boron trifluoride ethyl ether complex, 5g polyethylene glycol monomethyl ether 4000, 30g water-based hydroxyl acrylic resin, 4g barium sulfate, 1g nano zinc oxide, 1g titanium dioxide, 0.5g polycarboxylate dispersant, 1g activated boron nitride, 1g water-based amino resin, 0.5g Dow Corning 65 Additive, 1g organobentonite, 1g UV absorber UV-1130, 0.1g BYK-381, 1g associative polyurethane thickener 7800, and 0.5g dimethylethanolamine.

[0025] Activated boron nitride was prepared by the following steps: 5g of boron nitride nanosheets were added to 40g of 60% ethanol aqueous solution and stirred for 10min at a stirring speed of 200r / min. 1g of tetraethyl orthosilicate was added while stirring, and stirring was continued for 5min. The pH of the system was adjusted to 9-10 using 20% ​​ammonia water. The mixture was stirred at 200r / min for 1h at a stirring temperature of 40℃. After centrifugation, washing, and vacuum drying, the product was prepared.

[0026] The above-mentioned process for preparing water-based coatings for metallic materials includes the following steps: S1. Under nitrogen protection, bisphenol A diglycidyl ether, trimethylolpropane, and boron trifluoride diethyl ether complex were mixed and stirred at 100℃ for 5 hours. Polyethylene glycol monomethyl ether 4000 was added and stirred at 130℃ for 2 hours. The temperature was then lowered to 40℃, and triethylamine was added to adjust the system to neutral. Aqueous hydroxyl acrylic resin was added and the mixture was sheared at 1000 r / min for 5 minutes. Water was added while stirring to adjust the solid content of the system to 40%. The mixture was then emulsified using a homogenizer for 5 minutes to obtain the mixture. S2. Add barium sulfate, nano zinc oxide, titanium dioxide, polycarboxylate dispersant, activated boron nitride, and deionized water to a mixer and stir for 1 hour at a stirring speed of 100 r / min. Grind until the slurry fineness is ≤15 μm to obtain the pre-prepared slurry. S3. In sequence, mix the mixture, pre-made slurry, water-based amino resin, Dow Corning 65 Additive, organic bentonite, UV absorber UV-1130, BYK-381, associative polyurethane thickener 7800, and dimethylethanolamine evenly. Add deionized water to adjust the viscosity of the system to 2200 mPa•s. After coating the metal material surface, cure at 130℃ for 20 min.

[0027] Example 2: A water-based coating for metallic materials, comprising the following raw materials: 40g bisphenol A diglycidyl ether, 5g trimethylolpropane, 0.5g boron trifluoride ethyl ether complex, 15g polyethylene glycol monomethyl ether 4000, 50g water-based hydroxyl acrylic resin, 5g barium sulfate, 5g nano zinc oxide, 3g titanium dioxide, 1g polycarboxylate dispersant, 3g activated boron nitride, 5g water-based amino resin, 1.5g Dow Corning 65 Additive, 2g organobentonite, 2g UV absorber UV-1130, 1g BYK-381, 2g associative polyurethane thickener 7800, and 1.2g dimethylethanolamine.

[0028] Activated boron nitride was prepared using the following steps: 10g of boron nitride nanosheets were added to 60g of a 70% ethanol aqueous solution and stirred for 30min at a stirring speed of 600r / min. While stirring, 3g of tetraethyl orthosilicate was added, and stirring was continued for 15min. The pH of the system was adjusted to 9-10 using 22% ammonia water, and the mixture was stirred at 500r / min for 3h at a stirring temperature of 60℃. The mixture was then centrifuged, washed, and vacuum dried.

[0029] The above-mentioned process for preparing water-based coatings for metallic materials includes the following steps: S1. Under nitrogen protection, bisphenol A diglycidyl ether, trimethylolpropane, and boron trifluoride diethyl ether complex were mixed and stirred at 120°C for 15 hours. Polyethylene glycol monomethyl ether 4000 was added, and the mixture was stirred at 135°C for 4 hours. The temperature was then lowered to 50°C, and triethylamine was added to adjust the system to neutral. Aqueous hydroxyl acrylic resin was added, and the mixture was sheared at 3000 r / min for 12 minutes. Water was added while stirring to adjust the solid content of the system to 48.5%. The mixture was then emulsified using a homogenizer for 10 minutes to obtain the mixture. S2. Add barium sulfate, nano zinc oxide, titanium dioxide, polycarboxylate dispersant, activated boron nitride, and deionized water to a mixer and stir for 2 hours at a stirring speed of 500 r / min. Grind until the slurry fineness is ≤15 μm to obtain the pre-prepared slurry. S3. In sequence, mix the mixture, pre-made slurry, water-based amino resin, Dow Corning 65 Additive, organic bentonite, UV absorber UV-1130, BYK-381, associative polyurethane thickener 7800, and dimethylethanolamine evenly. Add deionized water to adjust the viscosity of the system to 2800 mPa•s. After coating the metal material surface, cure at 145℃ for 30 min.

[0030] Example 3: A water-based coating for metallic materials, comprising the following raw materials: 30g bisphenol A diglycidyl ether, 4g trimethylolpropane, 0.2g boron trifluoride ethyl ether complex, 12g polyethylene glycol monomethyl ether 4000, 45g water-based hydroxyl acrylic resin, 4.2g barium sulfate, 4g nano zinc oxide, 1.5g titanium dioxide, 0.9g polycarboxylate dispersant, 1.5g activated boron nitride, 4g water-based amino resin, 0.8g Dow Corning 65 Additive, 1.8g fumed silica, 1.2g UV-1130 ultraviolet absorber, 0.8g BYK-381, 1.2g associative polyurethane thickener 7800, and 1g dimethylethanolamine.

[0031] Activated boron nitride was prepared using the following steps: 7g of boron nitride nanosheets were added to 55g of a 62% ethanol aqueous solution and stirred for 25min at a stirring speed of 300r / min. While stirring, 2.5g of tetraethyl orthosilicate was added, and stirring was continued for 8min. The pH of the system was adjusted to 9-10 using 21% ammonia water, and the mixture was stirred at 400r / min for 1.5h at a stirring temperature of 55℃. The mixture was then centrifuged, washed, and vacuum dried.

[0032] The above-mentioned process for preparing water-based coatings for metallic materials includes the following steps: S1. Under nitrogen protection, bisphenol A diglycidyl ether, trimethylolpropane, and boron trifluoride diethyl ether complex were mixed and stirred at 105℃ for 12 hours. Polyethylene glycol monomethyl ether 4000 was added and stirred at 132℃ for 3.5 hours. The temperature was then lowered to 42℃, and triethylamine was added to adjust the system to neutral. Aqueous hydroxyl acrylic resin was added and the mixture was sheared at 2500 r / min for 6 minutes. Water was added while stirring to adjust the solid content of the system to 46%. The mixture was then emulsified using a homogenizer for 7 minutes to obtain the mixture. S2. Add barium sulfate, nano zinc oxide, titanium dioxide, polycarboxylate dispersant, activated boron nitride, and deionized water to a mixer and stir for 100 min at a stirring speed of 200 r / min. Grind until the slurry fineness is ≤15 μm to obtain the pre-prepared slurry. S3. In sequence, mix the mixture, pre-made slurry, water-based amino resin, Dow Corning 65 Additive, fumed silica, UV absorber UV-1130, BYK-381, associative polyurethane thickener 7800, and dimethylethanolamine evenly. Add deionized water to adjust the viscosity of the system to 2600 mPa•s. After coating the metal material surface, cure at 135℃ for 28 min.

[0033] Example 4: A water-based coating for metallic materials, comprising the following raw materials: 35g bisphenol A diglycidyl ether, 2g trimethylolpropane, 0.4g boron trifluoride ethyl ether complex, 8g polyethylene glycol monomethyl ether 4000, 35g water-based hydroxyl acrylic resin, 4.8g barium sulfate, 2g nano zinc oxide, 2.5g titanium dioxide, 0.7g polycarboxylate dispersant, 2.5g activated boron nitride, 2g water-based amino resin, 1.2g Dow Corning 65 Additive, 1.2g fumed silica, 1.8g UV absorber UV-1130, 0.2g BYK-381, 1.8g associative polyurethane thickener 7800, and 0.6g dimethylethanolamine.

[0034] Activated boron nitride was prepared using the following steps: 9g of boron nitride nanosheets were added to 45g of a 68% ethanol aqueous solution and stirred for 15min at a stirring speed of 500r / min. While stirring, 1.5g of tetraethyl orthosilicate was added, and stirring was continued for 12min. The pH of the system was adjusted to 9-10 using 21% ammonia water, and the mixture was stirred at 300r / min for 2.5h at a stirring temperature of 45℃. The mixture was then centrifuged, washed, and vacuum dried.

[0035] The above-mentioned process for preparing water-based coatings for metallic materials includes the following steps: S1. Under nitrogen protection, bisphenol A diglycidyl ether, trimethylolpropane, and boron trifluoride diethyl ether complex were mixed and stirred at 115℃ for 8 hours. Polyethylene glycol monomethyl ether 4000 was added, and the mixture was stirred at 134℃ for 2.5 hours. The temperature was then lowered to 48℃, and triethylamine was added to adjust the system to neutral. Aqueous hydroxyl acrylic resin was added, and the mixture was sheared at 1500 r / min for 10 minutes. Water was added while stirring to adjust the solid content of the system to 42%. The mixture was emulsified using a homogenizer for 9 minutes to obtain the mixture. S2. Add barium sulfate, nano zinc oxide, titanium dioxide, polycarboxylate dispersant, activated boron nitride, and deionized water to a mixer and stir for 80 minutes at a stirring speed of 400 r / min. Grind until the slurry fineness is ≤15 μm to obtain the pre-prepared slurry. S3. In sequence, mix the mixture, pre-made slurry, water-based amino resin, Dow Corning 65 Additive, fumed silica, UV absorber UV-1130, BYK-381, associative polyurethane thickener 7800, and dimethylethanolamine evenly. Add deionized water to adjust the viscosity of the system to 2400 mPa•s. After coating the metal material surface, cure at 140℃ for 22 min.

[0036] Example 5: A water-based coating for metallic materials, comprising the following raw materials: 33g bisphenol A diglycidyl ether, 3g trimethylolpropane, 0.3g boron trifluoride ethyl ether complex, 10g polyethylene glycol monomethyl ether 4000, 40g water-based hydroxyl acrylic resin, 4.5g barium sulfate, 3g nano zinc oxide, 2g titanium dioxide, 0.8g polycarboxylate dispersant, 2g activated boron nitride, 3g water-based amino resin, 1g Dow Corning 65 Additive, 1.5g fumed silica, 1.5g UV absorber UV-1130, 0.5g BYK-381, 1.5g associative polyurethane thickener 7800, and 0.8g dimethylethanolamine.

[0037] Activated boron nitride was prepared using the following steps: 5g of boron nitride nanosheets were added to 50g of a 65% ethanol aqueous solution and stirred for 20min at a stirring speed of 400r / min. While stirring, 2g of tetraethyl orthosilicate was added, and stirring was continued for 10min. The pH of the system was adjusted to 9-10 using 21% ammonia water, and the mixture was stirred at 350r / min for 2h at a stirring temperature of 50℃. After centrifugation, washing, and vacuum drying, the product was prepared.

[0038] The above-mentioned process for preparing water-based coatings for metallic materials includes the following steps: S1. Under nitrogen protection, bisphenol A diglycidyl ether, trimethylolpropane, and boron trifluoride diethyl ether complex were mixed and stirred at 110℃ for 10 hours. Polyethylene glycol monomethyl ether 4000 was added and stirred at 133℃ for 3 hours. The temperature was then lowered to 45℃, and triethylamine was added to adjust the system to neutral. Aqueous hydroxyl acrylic resin was added and the mixture was sheared at 2000 r / min for 8 minutes. Water was added while stirring to adjust the solid content of the system to 45%. The mixture was then emulsified using a homogenizer for 8 minutes to obtain the mixture. S2. Add barium sulfate, nano zinc oxide, titanium dioxide, polycarboxylate dispersant, activated boron nitride, and deionized water to a mixer and stir for 90 minutes at a stirring speed of 300 r / min. Grind until the slurry fineness is ≤15 μm to obtain the pre-prepared slurry. S3. In sequence, mix the mixture, pre-made slurry, water-based amino resin, Dow Corning 65 Additive, fumed silica, UV absorber UV-1130, BYK-381, associative polyurethane thickener 7800, and dimethylethanolamine evenly. Add deionized water to adjust the viscosity of the system to 2500 mPa•s. After coating the surface of the metal material (Q195 steel plate), cure at 138℃ for 25 min.

[0039] Comparative Example 1: A water-based coating for metallic materials, comprising the following raw materials: 46.3g water-based epoxy resin, 40g water-based hydroxyl acrylic resin, 4.5g barium sulfate, 3g nano zinc oxide, 2g titanium dioxide, 0.8g polycarboxylate dispersant, 2g activated boron nitride, 3g water-based amino resin, 1g Dow Corning 65 Additive, 1.5g fumed silica, 1.5g UV absorber UV-1130, 0.5g BYK-381, 1.5g associative polyurethane thickener 7800, and 0.8g dimethylethanolamine.

[0040] Activated boron nitride was prepared using the following steps: 5g of boron nitride nanosheets were added to 50g of a 65% ethanol aqueous solution and stirred for 20min at a stirring speed of 400r / min. While stirring, 2g of tetraethyl orthosilicate was added, and stirring was continued for 10min. The pH of the system was adjusted to 9-10 using 21% ammonia water, and the mixture was stirred at 350r / min for 2h at a stirring temperature of 50℃. After centrifugation, washing, and vacuum drying, the product was prepared.

[0041] The above-mentioned process for preparing water-based coatings for metallic materials includes the following steps: S1. Add waterborne hydroxyl acrylic resin to waterborne epoxy resin, shear at 2000 r / min for 8 min, add water while stirring to adjust the solid content of the system to 45%, and emulsify with a homogenizer for 8 min to obtain a mixture. S2. Add barium sulfate, nano zinc oxide, titanium dioxide, polycarboxylate dispersant, activated boron nitride, and deionized water to a mixer and stir for 90 minutes at a stirring speed of 300 r / min. Grind until the slurry fineness is ≤15 μm to obtain the pre-prepared slurry. S3. In sequence, mix the mixture, pre-made slurry, water-based amino resin, Dow Corning 65 Additive, fumed silica, UV absorber UV-1130, BYK-381, associative polyurethane thickener 7800, and dimethylethanolamine evenly. Add deionized water to adjust the viscosity of the system to 2500 mPa•s. After coating the surface of the metal material (Q195 steel plate), cure at 138℃ for 25 min.

[0042] Comparative Example 2: A water-based coating for metallic materials, comprising the following raw materials: 33g bisphenol A diglycidyl ether, 3g trimethylolpropane, 0.3g boron trifluoride ethyl ether complex, 10g polyethylene glycol monomethyl ether 4000, 40g water-based hydroxyl acrylic resin, 4.5g barium sulfate, 3g nano zinc oxide, 2g titanium dioxide, 0.8g polycarboxylate dispersant, 2g boron nitride nanosheets, 3g water-based amino resin, 1g Dow Corning 65 Additive, 1.5g fumed silica, 1.5g UV absorber UV-1130, 0.5g BYK-381, 1.5g associative polyurethane thickener 7800, and 0.8g dimethylethanolamine.

[0043] The above-mentioned process for preparing water-based coatings for metallic materials includes the following steps: S1. Under nitrogen protection, bisphenol A diglycidyl ether, trimethylolpropane, and boron trifluoride diethyl ether complex were mixed and stirred at 110℃ for 10 hours. Polyethylene glycol monomethyl ether 4000 was added and stirred at 133℃ for 3 hours. The temperature was then lowered to 45℃, and triethylamine was added to adjust the system to neutral. Aqueous hydroxyl acrylic resin was added and the mixture was sheared at 2000 r / min for 8 minutes. Water was added while stirring to adjust the solid content of the system to 45%. The mixture was then emulsified using a homogenizer for 8 minutes to obtain the mixture. S2. Add barium sulfate, nano zinc oxide, titanium dioxide, polycarboxylate dispersant, boron nitride nanosheets, and deionized water to a mixer and stir for 90 minutes at a stirring speed of 300 r / min. Grind until the slurry fineness is ≤15 μm to obtain the pre-prepared slurry. S3. In sequence, mix the mixture, pre-made slurry, water-based amino resin, Dow Corning 65 Additive, fumed silica, UV absorber UV-1130, BYK-381, associative polyurethane thickener 7800, and dimethylethanolamine evenly. Add deionized water to adjust the viscosity of the system to 2500 mPa•s. After coating the surface of the metal material (Q195 steel plate), cure at 138℃ for 25 min.

[0044] The thickness of the water-based coatings obtained in Example 5 and Comparative Examples 1-2 was tested. The average thickness of the water-based coating obtained in Example 5 was 75 ± 10 μm.

[0045] The steel plates coated with water-based coatings obtained in Example 5 and Comparative Examples 1-2 were completely immersed in distilled water for 240 hours, then removed, the surface moisture was wiped dry, and the crosslinking density was characterized by the rate of change in mass before and after immersion.

[0046] like Figure 1 As shown, Example 5 exhibited the smallest mass change rate before and after immersion in water, significantly outperforming the comparative example, indicating that it had the highest crosslinking density.

[0047] The adhesion of the water-based coatings obtained in Example 5 and Comparative Examples 1-2 was determined in accordance with GB / T 5210-2006 "Paints and Varnishes - Adhesion Test by Pull-Off Method".

[0048] Referring to GB / T 9274-1988 "Determination of Resistance to Liquid Media for Paints and Varnishes", the resistance of the water-based coatings obtained in Example 5 and Comparative Examples 1-2 to artificial seawater corrosion was tested. The temperature was 40°C, and a 5% (w / w) sodium chloride solution was used as the liquid medium. The samples were immersed in the 5% (w / w) sodium chloride solution for 2 weeks, and EIS data were obtained using an electrochemical workstation (P3000A). A higher charge transfer resistance indicates better corrosion resistance.

[0049] like Figure 2 As shown, the water-based coating obtained in Example 5 has the highest adhesion and charge transfer resistance, which is significantly better than the comparative example.

[0050] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A water-based coating for metallic materials, characterized in that, The raw materials, by weight, include: 20-40 parts bisphenol A diglycidyl ether, 1-5 parts trimethylolpropane, 0.1-0.5 parts boron trifluoride ethyl ether complex, 5-15 parts polyethylene glycol monomethyl ether 4000, 30-50 parts waterborne hydroxyl acrylic resin, 4-5 parts barium sulfate, 1-5 parts nano zinc oxide, 1-3 parts titanium dioxide, 0.5-1 part polycarboxylate dispersant, 1-3 parts activated boron nitride, 1-5 parts waterborne amino resin, 0.5-1.5 parts defoamer, 1-2 parts anti-settling agent, 1-2 parts ultraviolet absorber, 0.1-1 part acrylate leveling agent, 1-2 parts thixotropic agent, and 0.5-1.2 parts dimethylethanolamine.

2. The water-based coating for metallic materials according to claim 1, characterized in that, The ultraviolet absorber is a benzotriazole ultraviolet absorber.

3. The water-based coating for metallic materials according to claim 1, characterized in that, The anti-settling agent is at least one of organic bentonite and fumed silica.

4. The water-based coating for metallic materials according to claim 1, characterized in that, Acrylic leveling agents are polyacrylate copolymer solutions.

5. The water-based coating for metallic materials according to claim 1, characterized in that, The defoamer is a polyether-modified silicone defoamer.

6. The water-based coating for metallic materials according to claim 1, characterized in that, The thixotropic agent is a polyurethane associative thickener.

7. The water-based coating for metallic materials according to claim 1, characterized in that, Activated boron nitride is prepared by the following steps: add boron nitride nanosheets to an ethanol aqueous solution and stir for 10-30 min. While stirring, add tetraethyl orthosilicate and continue stirring for 5-15 min. Adjust the pH of the system to 9-10, stir at 40-60℃ for 1-3 h, centrifuge, wash, and vacuum dry.

8. The water-based coating for metallic materials according to claim 7, characterized in that, The mass ratio of boron nitride nanosheets to tetraethyl orthosilicate is 5-10:1-3.

9. A process for preparing an aqueous coating for a metallic material as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Under nitrogen protection, bisphenol A diglycidyl ether, trimethylolpropane, and boron trifluoride diethyl ether complex are mixed and stirred at 100-120℃ for 5-15 hours. Polyethylene glycol monomethyl ether 4000 is added, and the mixture is stirred at 130-135℃ for 2-4 hours. The temperature is then lowered to 40-50℃, and triethylamine is added to adjust the system to neutral. Aqueous hydroxyl acrylic resin is added, and the mixture is subjected to high-speed shearing for 5-12 minutes. During the shearing process, water is added to adjust the solid content of the system to 40-48.5%. The mixture is then homogenized and emulsified for 5-10 minutes to obtain a mixture. S2. Barium sulfate, nano zinc oxide, titanium dioxide, polycarboxylate dispersant, activated boron nitride, and water are stirred for 1-2 hours and then ground to obtain a pre-prepared slurry. S3. In sequence, mix the mixture, pre-made slurry, water-based amino resin, defoamer, anti-settling agent, ultraviolet absorber, acrylate leveling agent, thixotropic agent, and dimethylethanolamine evenly, and add water; after coating, cure at 130-145℃ for 20-30 minutes.

10. The preparation process of the water-based coating for metallic materials according to claim 9, characterized in that, In S3, water is added to adjust the viscosity of the system to 2200-2800 mPa•s.

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