Anticorrosive metal primer and method for producing the same

Abstract

The present application relates to a kind of anticorrosive metal primer and its preparation method, belong to coating technical field, the primer A component includes modified alloy powder, Schiff base cobalt complex, barium sulfate, boron nitride, modified resin, polycyclocarbonate diluent etc.;B component includes curing agent, interface anchor promoting agent.Modified alloy powder is Fe, Cr, Ni, Mo, W metal powder sintering, is prepared by titanate coupling agent surface modification.Modified resin is bisphenol S epoxy resin, epoxy propoxy propyl terminated polydimethylsiloxane, 3-(2,2,3,3-tetrafluoropropoxy)-1,2-oxidized propylene, tetrabutylphosphonium bromide, 3-(trihydroxysilyl) propyl methyl phosphate, polycyclocarbonate diluent and propylene glycol methyl ether are prepared.The primer of the present application realizes the comprehensive performance of low temperature rapid curing, high construction tolerance, wide temperature range environmental resistance.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to an anti-corrosion metal primer and its preparation method. Background Technology

[0002] Metal substrates are prone to electrochemical corrosion in marine, industrial atmospheres, and acid / alkali corrosive environments, leading to structural failure, shortened lifespan, and safety hazards. Metal primers, as the first coating layer in a coating system, play a crucial role in substrate protection, enhancing interlayer adhesion, and blocking corrosive media, making them key materials for heavy-duty corrosion protection and long-term protection. Currently, mainstream metal primers primarily consist of epoxy zinc-rich primers, inorganic zinc silicate primers, epoxy zinc phosphate primers, polyurethane primers, and alkyd anti-rust primers. They achieve corrosion protection through three main mechanisms: physical shielding, passivation corrosion inhibition, and cathodic protection. Epoxy zinc-rich primers and inorganic zinc silicate primers form a conductive network with high zinc powder content, sacrificing the anode to protect the steel substrate. Passivating primers such as zinc phosphate and aluminum tripolyphosphate react with the metal surface to form a dense passivation film that blocks corrosion. Ordinary alkyd and epoxy iron oxide red primers achieve physical shielding through the density of the paint film.

[0003] With increasingly stringent service environments and stricter environmental standards, the performance shortcomings of traditional metal primers have become increasingly apparent, making it difficult to meet application requirements such as long-lasting performance and wide temperature range. Traditional primers struggle to form a strong bond, easily leading to blistering, peeling, and interlayer separation. Under humid heat and temperature cycling, the mismatch in thermal expansion coefficients exacerbates coating cracking and desorption. Defects exist in corrosion resistance, durability, and protective mechanisms: while high zinc content in zinc-rich primers enhances cathodic protection, it also results in brittle films with poor toughness and insufficient impact and bending resistance, making them prone to damage under impact and vibration conditions; zinc powder reacts with moisture to form zinc salts, causing whitening, chalking, and cathodic disbondment; physical shielding primers lack electrochemical protection, leading to rapid corrosion after pinholes or damage; passivating pigments react slowly under low temperatures and high salt spray conditions, creating protective blind spots. Inorganic zinc silicate primers are brittle, prone to cracking when applied thickly, and have poor adhesion for repairs, limiting their application. Imbalance in overall performance: Hardness, toughness, weather resistance, and media resistance are difficult to coordinate. High-corrosion-resistant primers often have poor flexibility and are prone to cracking. Flexible primers have insufficient corrosion protection and shielding properties and cannot adapt to complex stress and multi-factor corrosion environments.

[0004] To meet the upgrading needs of marine engineering, new energy equipment, long-distance pipelines, and high-end manufacturing, existing primers have limitations in terms of long-term corrosion protection and environmental tolerance. Therefore, it is necessary to develop high-performance anti-corrosion metal primers to meet the ever-increasing application requirements. Summary of the Invention

[0005] To address the shortcomings of existing traditional coatings, such as poor long-term corrosion resistance and environmental tolerance, which make them unsuitable for the upgrading needs of marine engineering, new energy equipment, long-distance pipelines, and high-end manufacturing, this invention provides an anti-corrosion metal primer and its preparation method. Through modified resin base design, synergistic compounding of functional fillers, hyperbranched hybrid curing agents, and precise control of auxiliary systems, the primer achieves comprehensive performance including low-temperature rapid curing, high application tolerance, and wide-temperature environmental tolerance. Simultaneously, it utilizes environmentally friendly solvents and reactive diluents, balancing performance and environmental requirements. The specific technical solution is as follows:

[0006] A corrosion-resistant metal primer is prepared by mixing component A and component B in a mass ratio of 100:(22-25), and adjusting the viscosity to 3500-5500 mPa·s with an environmentally friendly solvent. Component A comprises the following raw materials in parts by mass: 12-15 parts modified alloy powder, 3-5 parts Schiff base cobalt complex, 10-12 parts barium sulfate, 1-2 parts boron nitride, 50-55 parts modified resin, 1-1.5 parts wetting agent, 0.5-0.7 parts rheology modifier, 0.3-0.4 parts defoamer, 6-8 parts polycyclic carbonate diluent, and 6-8 parts environmentally friendly solvent. Component B comprises the following raw materials in parts by mass: 96-98 parts curing agent and 2-4 parts interface anchoring accelerator.

[0007] In the above primer, the modified alloy powder is prepared by sintering metal powder at 1250-1350℃ in a mass ratio of Fe:Cr:Ni:Mo:W=(30-35):(20-25):(20-25):(10-15):(5-8), and then surface-modifying it with a titanate coupling agent after pulverization.

[0008] In the aforementioned primer, the Schiff base cobalt complex is prepared by reacting salicylaldehyde with ethylenediamine in anhydrous ethanol at a molar ratio of 2:(1-1.2) to obtain the Schiff base ligand, and then stirring it with cobalt acetate in anhydrous ethanol at a molar ratio of 1:(1.02-1.05).

[0009] In the above primer, the modified resin is prepared by mixing bisphenol S epoxy resin, epoxypropoxypropyl-terminated polydimethylsiloxane, 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide, tetrabutylphosphine bromide, and 3-(trihydroxysilyl)propylmethyl phosphate in a ratio of (60-65):(20-25):(9-11):(0.3-0.4):(3.0-3.4), and then adjusting the solid content to 45-50 wt% with a mixture of polycyclic carbonate diluent and propylene glycol methyl ether.

[0010] In the above primer, the polycyclic carbonate diluent is a product with pH 7.0 to 7.5 prepared by a complex of propylene carbonate, propylene glycol methyl ether, and boron trifluoride ethyl ether in a mass ratio of (80-85):(20-25):(0.4-0.6).

[0011] In the above primer, the curing agent is a mixture of hyperbranched BIS-MPA polyester-4th generation-hydroxyl, AC-PEG-NHS, aminopropyl dual-terminated polydimethylsiloxane, and 4,4'-diaminodicyclohexylmethane in a mass ratio of (25-30):(35-40):(11-13):(20-25). The hyperbranched BIS-MPA polyester-4th generation-hydroxyl, AC-PEG-NHS, and aminopropyl dual-terminated polydimethylsiloxane are stirred in propylene glycol methyl ether acetate at 45-50°C, and the propylene glycol methyl ether acetate is recovered to obtain an intermediate. This intermediate is then stirred with 4,4'-diaminodicyclohexylmethane at 45-50°C to obtain the final product.

[0012] In the above primer, the wetting agent is BYK-190; the rheology modifier is BYK-410; the defoamer is BYK-1790; the environmentally friendly solvent is propylene glycol methyl ether; and the interface anchoring accelerator is a zirconate coupling agent.

[0013] Furthermore, the preparation method of the modified alloy powder includes the following steps: sintering metal powder of 30-35 parts Fe, 20-25 parts Cr, 20-25 parts Ni, 10-15 parts Mo, and 5-8 parts W at 1250-1350℃ for 2-3 hours, pulverizing it into powder, adding 8-10 times the mass of the powder to a 1.0-1.5wt% anhydrous ethanol solution of titanate coupling agent, dispersing, filtering, and drying to obtain the modified alloy powder.

[0014] Furthermore, the preparation method of the Schiff base cobalt complex includes the following steps: salicylaldehyde and ethylenediamine are added to anhydrous ethanol at a molar ratio of 2:(1-1.2), refluxed at 75-80°C for 2-2.5 h, cooled to crystallize, filtered, and the Schiff base ligand is obtained; the Schiff base ligand and cobalt acetate are added to anhydrous ethanol at a molar ratio of 1:(1.02-1.05), stirred at 65-70°C for 5-6 h, filtered, washed, and dried to obtain the Schiff base cobalt complex.

[0015] Further, the preparation method of the modified resin includes the following steps: 60-65 parts by weight of bisphenol S epoxy resin, 20-25 parts by weight of epoxypropoxypropyl-terminated polydimethylsiloxane, and 9-11 parts by weight of 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide are mixed at 130-140°C; 0.3-0.4 parts by weight of tetrabutylphosphine bromide are added at 110-120°C and stirred; 3.0-3.4 parts by weight of 3-(trihydroxysilyl)propylmethyl phosphate are added at 90-100°C and stirred; a polycyclic carbonate diluent and propylene glycol methyl ether mixed solvent with a mass ratio of 2:(1-1.5) are added at 60-70°C to adjust the solid content to 45-50 wt%, and the mixture is filtered to obtain the modified resin.

[0016] Furthermore, the preparation method of the polycyclic carbonate diluent includes the following steps: mixing 80-85 parts by weight of propylene carbonate and 20-25 parts by weight of propylene glycol methyl ether, adding 0.4-0.6 parts by weight of boron trifluoride diethyl ether complex at 55-60°C and stirring, distilling under reduced pressure, and neutralizing with triethylamine to pH 7.0-7.5 to obtain the polycyclic carbonate diluent.

[0017] Furthermore, the preparation method of the curing agent includes the following steps: by weight, 25-30 parts of hyperbranched BIS-MPA polyester-4th generation-hydroxyl are dissolved in 20-25 parts of propylene glycol methyl ether acetate to obtain solution I; 35-40 parts of AC-PEG-NHS are dissolved in 15-20 parts of propylene glycol methyl ether acetate to obtain solution II; solution I and 11-13 parts of aminopropyl double-terminated polydimethylsiloxane are stirred, solution II is added dropwise, stirred at 45-50°C for 4-5 hours, and propylene glycol methyl ether acetate is recovered by vacuum distillation to obtain an intermediate; the intermediate is stirred with 20-25 parts of 4,4'-diaminodicyclohexylmethane (HMDA) at 45-50°C for 1-1.5 hours to obtain the curing agent.

[0018] The preparation method of the above-mentioned anti-corrosion metal primer includes the following steps: S1: Mix modified alloy powder, Schiff base cobalt complex, barium sulfate and boron nitride to obtain a premix; mix modified resin, polycyclic carbonate diluent and environmentally friendly solvent, add wetting agent, rheology modifier and defoamer, add the premix and disperse, grind to fineness <15μm, filter to obtain component A; S2: Component B is prepared by mixing the curing agent and the interface anchoring accelerator; S3: When using, mix components A and B according to the formula, adjust the viscosity to 3500-5500 mPa·s with an environmentally friendly solvent, and cure to obtain an anti-corrosion metal primer.

[0019] The present invention provides an anti-corrosion metal primer and its preparation method, which have the following beneficial effects: I. The anti-corrosion metal primer of this invention, through modified resin base design, synergistic compounding of functional fillers, hyperbranched hybrid curing agent, and precise control of auxiliary system, breaks through the performance bottlenecks of traditional metal primers, such as imbalance between hardness and toughness, contradiction between corrosion prevention and adhesion, and conflict between long-term effectiveness and workability. It achieves comprehensive performance of low-temperature rapid curing, high workability tolerance, and wide temperature range environmental tolerance, and can provide long-term protection for metal components throughout their entire life cycle in harsh corrosive environments such as marine engineering and new energy equipment. At the same time, it uses environmentally friendly solvents and reactive diluents to balance performance and environmental protection requirements.

[0020] 2. Modified alloy powder is sintered with argon gas at 1250~1350℃ in a specific ratio of Fe:Cr:Ni:Mo:W to form a uniform alloy phase, achieving mild sacrificial anode cathodic protection and avoiding defects such as paint film embrittlement and zinc salt formation caused by excessive electrode potential difference of pure zinc powder in the prior art; the surface is modified with titanate coupling agent to improve the interfacial compatibility with resin, avoid powder agglomeration, reduce internal defects of paint film, and at the same time strengthen the bonding force between filler and resin, thereby improving the mechanical properties of paint film.

[0021] III. A Schiff base ligand is prepared by reflux of salicylaldehyde and ethylenediamine at a specific molar ratio, and then complexed with cobalt acetate to form a Schiff base cobalt complex with sustained-release properties. Upon intrusion of corrosive media, this complex undergoes hydrolysis, releasing Co. 2+ It forms a complex passivation film with the metal surface, achieving passivation and corrosion inhibition.

[0022] IV. In the preparation of the modified resin, bisphenol S epoxy resin, epoxy-terminated polydimethylsiloxane, fluorinated epoxy monomer, and silicone phosphate are compounded in proportion to achieve fluorosilicone-phosphorus hybrid modification: bisphenol S epoxy resin provides a high rigidity, hydrolysis resistance, and media resistance; polydimethylsiloxane introduces flexible segments to reduce internal stress and improve hydrophobicity; fluorinated epoxy monomer imparts ultra-low surface energy to the coating film, blocking the penetration of corrosive media; and silicone phosphate strengthens interfacial adhesion and provides passivation sites through Si-OM covalent bonds.

[0023] V. A reactive polycyclic carbonate diluent prepared by proportioning a complex of propylene carbonate, propylene glycol methyl ether, and boron trifluoride ethyl ether participates in the crosslinking reaction of epoxy curing, replacing traditional volatile diluents, reducing curing shrinkage and paint film defects, and improving paint film density; at the same time, it improves compatibility with modified resins.

[0024] VI. In the preparation of the hyperbranched hybrid curing agent, hyperbranched BIS-MPA polyester, AC-PEG-NHS, aminopropyl double-terminated polydimethylsiloxane, and 4,4'-diaminodicyclohexylmethane are compounded in proportion to achieve a balance between high crosslinking density and high toughness: hyperbranched polyester provides multi-point anchoring and dense film formation; AC-PEG-NHS introduces flexible segments and low-temperature reactivity; siloxane further toughens and hydrophobically repels; and 4,4'-diaminodicyclohexylmethane ensures rapid curing at room temperature and low temperature.

[0025] VII. In the overall mixing preparation method, the modified alloy powder, Schiff base cobalt complex, barium sulfate, and boron nitride are mixed in advance to ensure uniform dispersion of functional fillers and avoid local fluctuations in paint film performance caused by uneven dispersion of single components. The modified resin is mixed with diluent and environmentally friendly solvent first, then the additives are added for dispersion, and finally the premix is ​​added for dispersion and grinding to ensure nanoscale dispersion of fillers in resin, forming a dense filler network and extending the penetration path of corrosive media.

[0026] In summary, the various components of the formulation achieve multi-level synergy across four dimensions: anti-corrosion mechanism, film-forming process, interfacial bonding, and mechanical properties, ultimately resulting in simultaneous improvements in adhesion, impact resistance, flexibility, and resistance to temperature and humidity cycling. The modified resin's silanol phosphate ester, modified alloy powder, and Schiff base cobalt complex form passivation sites synergistically. The resin's passivation groups work in tandem with the filler's corrosion inhibition and cathodic protection effects, forming a dense composite passivation film on the metal surface. The resin's low surface energy, combined with the layered shielding of barium sulfate and boron nitride, forms a physical shielding synergistic effect, doubly blocking the penetration of corrosive media. The modified resin's epoxy groups and the curing agent's amino and hydroxyl groups form a cross-linking synergistic effect. The multi-point anchoring of the hyperbranched curing agent and the resin's hybrid structure form a highly dense cross-linking network, enhancing the film's resistance to media and mechanical properties. The resin's siloxane and fluorinated groups, combined with the curing agent's siloxane segments, form a hydrophobic synergistic effect, further reducing the film's surface energy and improving water resistance. Polycyclic carbonate diluents and curing agents work synergistically to form a film, participate in the crosslinking reaction to reduce curing shrinkage, and work with the grinding process to form a dense paint film. Detailed Implementation

[0027] Some embodiments are given below, but the present invention is not limited to these embodiments.

[0028] Example 1 A corrosion-resistant metal primer, comprising a mixture of component A and component B in a mass ratio of 100:23, and a viscosity adjusted to 4500 mPa·s using an environmentally friendly solvent (propylene glycol methyl ether); component A comprises the following raw materials in parts by mass: 13 parts modified alloy powder, 4 parts Schiff base cobalt complex, 11 parts barium sulfate, 1.5 parts boron nitride, 52 parts modified resin, 1.2 parts wetting agent (BYK-190), 0.6 parts rheology modifier (BYK-410), 0.35 parts defoamer (BYK-1790), 7 parts polycyclic carbonate diluent, and 7 parts environmentally friendly solvent (propylene glycol methyl ether); component B comprises the following raw materials in parts by mass: 97 parts curing agent and 3 parts interface anchoring accelerator (KEN-REACT NZ 38).

[0029] The preparation method of the modified alloy powder includes the following steps: 32 parts Fe, 23 parts Cr, 22 parts Ni, 12 parts Mo, and 6.5 parts W metal powder are mixed evenly by mass. Under an argon atmosphere, the mixture is heated to 1300℃ at 6℃ / min and sintered for 2.5h. After cooling to room temperature in the furnace, the mixture is pulverized and graded to a D50 of 3.2μm to obtain powder. The powder is then added to an anhydrous ethanol solution of 1.2wt% titanate coupling agent (NDZ-201) at 9 times its mass. The mixture is stirred and dispersed at 550rpm for 50min. After filtration, the filter cake is vacuum dried at 75-80℃ for 2h to obtain the modified alloy powder.

[0030] The preparation method of the Schiff base cobalt complex includes the following steps: Under nitrogen protection, salicylaldehyde and ethylenediamine are added to anhydrous ethanol at a molar ratio of 2:1.1 to 7 times the total mass, and the mixture is refluxed at 75-80℃ for 2 hours. After cooling and crystallization, the mixture is filtered to obtain the Schiff base ligand. The Schiff base ligand and cobalt acetate are added to anhydrous ethanol at a molar ratio of 1:1.03 to 7 times the total mass, and the mixture is stirred at 65-70℃ and 320 rpm for 5.5 hours. After filtration, the filter cake is washed twice with anhydrous ethanol and vacuum dried at 50-55℃ for 5 hours to obtain the Schiff base cobalt complex.

[0031] The preparation method of the modified resin includes the following steps: Under nitrogen protection, 62 parts by mass of bisphenol S epoxy resin, 23 parts by mass of epoxypropoxypropyl-terminated polydimethylsiloxane, and 10 parts by mass of 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide are mixed evenly in a temperature range of 130-140℃. 0.35 parts by mass of tetrabutylphosphine bromide are added in a temperature range of 110-120℃, and the mixture is stirred at 320 rpm for 3.5 h. 3.2 parts by mass of 3-(trihydroxysilyl)propylmethyl phosphate are added in a temperature range of 90-100℃, and the mixture is stirred for 1 h. The temperature is lowered to 65℃, and a mixture of polycyclic carbonate diluent and propylene glycol methyl ether in a mass ratio of 2:1.3 is added to adjust the solid content to 48 wt%. The mixture is filtered through a 250-mesh filtration to remove impurities, thus obtaining the modified resin.

[0032] The preparation method of polycyclic carbonate diluent includes the following steps: Under nitrogen protection, in a closed reaction vessel equipped with a pressure relief valve, 83 parts by mass of propylene carbonate and 22 parts by mass of propylene glycol methyl ether are mixed, heated to a temperature range of 55-60℃, 0.5 parts of boron trifluoride diethyl ether complex are added, stirred at a slight positive pressure of 0.04 MPa and 320 rpm for 5.5 h, cooled to a temperature range of 45-50℃, and distilled under reduced pressure of -0.090 MPa for 1.5 h to remove low-boiling substances, and neutralized to pH 7.3 with triethylamine to obtain polycyclic carbonate diluent.

[0033] The preparation method of the curing agent includes the following steps: by mass, 28 parts of hyperbranched BIS-MPA polyester-4th generation-hydroxyl are dissolved in 23 parts of propylene glycol methyl ether acetate to obtain solution I; 38 parts of AC-PEG-NHS are dissolved in 17 parts of propylene glycol methyl ether acetate to obtain solution II; under nitrogen protection, solution I and 12 parts of aminopropyl double-terminated polydimethylsiloxane are added to a reaction vessel, and solution II is added dropwise while stirring at 320 rpm under ice-water bath temperature control below 30°C; after the dropwise addition is completed, the temperature is raised to 45-50°C and stirred for 4.5 h, and propylene glycol methyl ether acetate is recovered by vacuum distillation to obtain an intermediate; the intermediate is stirred with 23 parts of 4,4'-diaminodicyclohexylmethane (HMDA) at 45-50°C for 1.5 h until uniform and transparent, thus obtaining the curing agent.

[0034] The preparation method of the above-mentioned anti-corrosion metal primer includes the following steps: S1: According to the formula, the modified alloy powder, Schiff base cobalt complex, barium sulfate, and boron nitride are mixed for 12 min to obtain a premix; the modified resin, polycyclic carbonate diluent, and propylene glycol methyl ether are added to the mixing tank and stirred at 550 rpm for 12 min; the wetting agent, rheology modifier, and defoamer are added and stirred at 550 rpm for 12 min; the premix is ​​added and dispersed at 820 rpm for 20 min; the material temperature is controlled below 30℃ using circulating cooling water; the material is ground to a fineness of <15 μm; and impurities are removed by 150 mesh filtration to obtain component A. S2: Stir the curing agent and interface anchoring accelerator at 350 rpm for 12 min until homogeneous to obtain component B; S3: When using, stir components A and B at 350 rpm for 9 minutes according to the formula, adjust the viscosity to 4500 mPa·s (25℃) with an environmentally friendly solvent, and let it stand for 22 minutes to obtain the anti-corrosion metal primer.

[0035] Example 2 A corrosion-resistant metal primer, comprising a mixture of component A and component B in a mass ratio of 100:22, and a viscosity adjusted to 5500 mPa·s using an environmentally friendly solvent (propylene glycol methyl ether); component A comprises the following raw materials in parts by mass: 12 parts modified alloy powder, 3 parts Schiff base cobalt complex, 10 parts barium sulfate, 1 part boron nitride, 50 parts modified resin, 1 part wetting agent (BYK-190), 0.5 parts rheology modifier (BYK-410), 0.3 parts defoamer (BYK-1790), 6 parts polycyclic carbonate diluent, and 6 parts environmentally friendly solvent (propylene glycol methyl ether); component B comprises the following raw materials in parts by mass: 96 parts curing agent and 4 parts interface anchoring accelerator (KEN-REACT NZ 38).

[0036] The preparation method of the modified alloy powder includes the following steps: 30 parts Fe, 20 parts Cr, 20 parts Ni, 10 parts Mo, and 5 parts W metal powder are mixed evenly by mass. Under an argon atmosphere, the mixture is heated to 1250℃ at 5℃ / min and sintered for 2 hours. After cooling to room temperature in the furnace, the mixture is pulverized and graded to a D50 of 4.6μm to obtain powder. The powder is then added to an anhydrous ethanol solution of 1.0wt% titanate coupling agent (NDZ-201) at 8 times its mass. The mixture is stirred and dispersed at 500rpm for 40 minutes, filtered, and the filter cake is vacuum dried at 75-80℃ for 2 hours to obtain the modified alloy powder.

[0037] The preparation method of the Schiff base cobalt complex includes the following steps: Under nitrogen protection, salicylaldehyde and ethylenediamine are added to anhydrous ethanol at a molar ratio of 2:1, and the mixture is refluxed at 75-80℃ for 2 hours. After cooling and crystallization, the mixture is filtered to obtain the Schiff base ligand. The Schiff base ligand and cobalt acetate are added to anhydrous ethanol at a molar ratio of 1:1.02, and the mixture is stirred at 65-70℃ and 300 rpm for 5 hours. After filtration, the filter cake is washed twice with anhydrous ethanol and dried under vacuum at 50-55℃ for 4 hours to obtain the Schiff base cobalt complex.

[0038] The preparation method of the modified resin includes the following steps: Under nitrogen protection, 60 parts by mass of bisphenol S epoxy resin, 20 parts by mass of epoxypropoxypropyl-terminated polydimethylsiloxane, and 9 parts by mass of 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide are mixed evenly in a temperature range of 130-140℃. 0.3 parts by mass of tetrabutylphosphine bromide are added in a temperature range of 110-120℃, and the mixture is stirred at 300 rpm for 3 hours. 3.0 parts by mass of 3-(trihydroxysilyl)propylmethyl phosphate are added in a temperature range of 90-100℃, and the mixture is stirred for 1 hour. The temperature is lowered to 60℃, and a mixture of polycyclic carbonate diluent and propylene glycol methyl ether in a mass ratio of 2:1 is added to adjust the solid content to 45 wt%. The mixture is filtered through a 250-mesh filtration to remove impurities, thus obtaining the modified resin.

[0039] The preparation method of polycyclic carbonate diluent includes the following steps: Under nitrogen protection, in a closed reaction vessel equipped with a pressure relief valve, 80 parts by mass of propylene carbonate and 20 parts by mass of propylene glycol methyl ether are mixed, heated to a temperature range of 55-60℃, 0.4 parts of boron trifluoride diethyl ether complex are added, stirred at a slight positive pressure of 0.02MPa and 300rpm for 5h, cooled to a temperature range of 45-50℃, and distilled under reduced pressure of -0.085MPa for 2h to remove low-boiling substances. The mixture is then neutralized to pH 7.0 with triethylamine to obtain the polycyclic carbonate diluent.

[0040] The preparation method of the curing agent includes the following steps: by mass, 25 parts of hyperbranched BIS-MPA polyester-4th generation-hydroxyl are dissolved in 20 parts of propylene glycol methyl ether acetate to obtain solution I; 35 parts of AC-PEG-NHS are dissolved in 15 parts of propylene glycol methyl ether acetate to obtain solution II; under nitrogen protection, solution I and 11 parts of aminopropyl double-terminated polydimethylsiloxane are added to a reaction vessel, the temperature is controlled below 30°C in an ice-water bath, and solution II is added dropwise while stirring at 300 rpm; after the dropwise addition is completed, the temperature is raised to 45-50°C and stirred for 4 hours, and propylene glycol methyl ether acetate is recovered by vacuum distillation to obtain an intermediate; the intermediate is stirred with 20 parts of 4,4'-diaminodicyclohexylmethane (HMDA) at 45-50°C for 1 hour until uniform and transparent to obtain the curing agent.

[0041] The preparation method of the above-mentioned anti-corrosion metal primer includes the following steps: S1: According to the formula, the modified alloy powder, Schiff base cobalt complex, barium sulfate, and boron nitride are mixed for 10 min to obtain a premix; the modified resin, polycyclic carbonate diluent, and propylene glycol methyl ether are added to the mixing tank and stirred at 600 rpm for 10 min; the wetting agent, rheology modifier, and defoamer are added and stirred at 600 rpm for 10 min; the premix is ​​added and dispersed at 850 rpm for 15 min; the material temperature is controlled below 30℃ using circulating cooling water; the material is ground to a fineness of <15μm; and impurities are removed by 200 mesh filtration to obtain component A. S2: Stir the curing agent and interface anchoring accelerator at 300 rpm for 15 min until homogeneous to obtain component B; S3: When using, stir components A and B at 300 rpm for 10 minutes according to the formula, adjust the viscosity to 5500 mPa·s (25℃) with an environmentally friendly solvent, and let it stand for 20 minutes to obtain the anti-corrosion metal primer.

[0042] Example 3 A corrosion-resistant metal primer, comprising a mixture of component A and component B in a mass ratio of 100:25, and a viscosity adjusted to 3500 mPa·s using an environmentally friendly solvent (propylene glycol methyl ether); component A comprises the following raw materials in parts by mass: 15 parts modified alloy powder, 5 parts Schiff base cobalt complex, 12 parts barium sulfate, 2 parts boron nitride, 55 parts modified resin, 1.5 parts wetting agent (BYK-190), 0.7 parts rheology modifier (BYK-410), 0.4 parts defoamer (BYK-1790), 8 parts polycyclic carbonate diluent, and 8 parts environmentally friendly solvent (propylene glycol methyl ether); component B comprises the following raw materials in parts by mass: 98 parts curing agent and 2 parts interface anchoring accelerator (KEN-REACT NZ 38).

[0043] The preparation method of the modified alloy powder includes the following steps: 35 parts Fe, 25 parts Cr, 25 parts Ni, 15 parts Mo, and 8 parts W metal powder are mixed evenly by mass. Under an argon atmosphere, the mixture is heated to 1350℃ at 8℃ / min and sintered for 3 hours. After cooling to room temperature in the furnace, the mixture is pulverized and graded to a D50 of 3.7μm to obtain powder. The powder is then added to an anhydrous ethanol solution of 1.5wt% titanate coupling agent (NDZ-201) at 10 times its mass. The mixture is stirred and dispersed at 600rpm for 60 minutes, filtered, and the filter cake is vacuum dried at 75-80℃ for 2.5 hours to obtain the modified alloy powder.

[0044] The preparation method of the Schiff base cobalt complex includes the following steps: Under nitrogen protection, salicylaldehyde and ethylenediamine are added to anhydrous ethanol at a molar ratio of 2:1.2, and the mixture is refluxed at 75-80℃ for 2.5 h. After cooling and crystallization, the mixture is filtered to obtain the Schiff base ligand. The Schiff base ligand and cobalt acetate are added to anhydrous ethanol at a molar ratio of 1:1.05, and the mixture is stirred at 65-70℃ and 350 rpm for 6 h. After filtration, the filter cake is washed three times with anhydrous ethanol and vacuum dried at 50-55℃ for 6 h to obtain the Schiff base cobalt complex.

[0045] The preparation method of the modified resin includes the following steps: Under nitrogen protection, 65 parts by mass of bisphenol S epoxy resin, 25 parts by mass of epoxypropoxypropyl-terminated polydimethylsiloxane, and 11 parts by mass of 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide are mixed evenly in a temperature range of 130-140℃. 0.4 parts by mass of tetrabutylphosphine bromide are added in a temperature range of 110-120℃, and the mixture is stirred at 350 rpm for 4 hours. 3.4 parts by mass of 3-(trihydroxysilyl)propylmethyl phosphate are added in a temperature range of 90-100℃, and the mixture is stirred for 1.5 hours. The temperature is then lowered to 70℃, and a mixture of polycyclic carbonate diluent and propylene glycol methyl ether in a mass ratio of 2:1.5 is added to adjust the solid content to 50 wt%. The mixture is then filtered through a 300-mesh filtration to remove impurities, thus obtaining the modified resin.

[0046] The preparation method of polycyclic carbonate diluent includes the following steps: Under nitrogen protection, in a closed reaction vessel equipped with a pressure relief valve, 85 parts by mass of propylene carbonate and 25 parts by mass of propylene glycol methyl ether are mixed, heated to a temperature range of 55-60℃, 0.6 parts of boron trifluoride diethyl ether complex are added, stirred at a slight positive pressure of 0.05MPa and 350rpm for 6 hours, cooled to 45-50℃, and distilled under reduced pressure of -0.095MPa for 1.5 hours to remove low-boiling substances, and neutralized to pH 7.5 with triethylamine to obtain polycyclic carbonate diluent.

[0047] The preparation method of the curing agent includes the following steps: by mass, 30 parts of hyperbranched BIS-MPA polyester-4th generation-hydroxyl are dissolved in 25 parts of propylene glycol methyl ether acetate to obtain solution I; 40 parts of AC-PEG-NHS are dissolved in 20 parts of propylene glycol methyl ether acetate to obtain solution II; under nitrogen protection, solution I and 13 parts of aminopropyl double-terminated polydimethylsiloxane are added to a reaction vessel, and solution II is added dropwise while stirring at 350 rpm under ice-water bath temperature control below 30°C; after the dropwise addition is completed, the temperature is raised to 45-50°C and stirred for 5 hours, and propylene glycol methyl ether acetate is recovered by vacuum distillation to obtain an intermediate; the intermediate is stirred with 25 parts of 4,4'-diaminodicyclohexylmethane (HMDA) at 45-50°C for 1.5 hours until uniform and transparent to obtain the curing agent.

[0048] The preparation method of the above-mentioned anti-corrosion metal primer includes the following steps: S1: According to the formula, the modified alloy powder, Schiff base cobalt complex, barium sulfate, and boron nitride are mixed for 15 min to obtain a premix; the modified resin, polycyclic carbonate diluent, and propylene glycol methyl ether are added to the mixing tank and stirred at 500 rpm for 15 min; the wetting agent, rheology modifier, and defoamer are added and stirred at 500 rpm for 15 min; the premix is ​​added and dispersed at 800 rpm for 30 min; the material temperature is controlled below 30℃ using circulating cooling water; the material is ground to a fineness of <15 μm; and impurities are removed by 150 mesh filtration to obtain component A. S2: Stir the curing agent and interface anchoring accelerator at 400 rpm for 10 min until homogeneous to obtain component B; S3: When using, stir components A and B at 400 rpm for 8 minutes according to the formula, adjust the viscosity to 3500 mPa·s (25℃) with an environmentally friendly solvent, and let it stand for 25 minutes to obtain the anti-corrosion metal primer.

[0049] The raw materials used in the above embodiments are sourced as follows: wetting agent BYK-190, rheology modifier BYK-410, and defoamer BYK-1790, all from the German brand BYK. The interface anchoring accelerator is zirconate coupling agent (KEN-REACT NZ 38), sourced from Guangdong Shengke Biochemical Technology Co., Ltd. The titanate coupling agent (NDZ-201) is sourced from Dongguan Kangjin New Material Technology Co., Ltd. Salicylic acid aldehyde is sourced from Kandis Chemical (Hubei) Co., Ltd., with a purity of 99%. Cobalt acetate is sourced from Nantong Zhonghe Chemical New Material Co., Ltd., with a purity of 99%. Bisphenol S epoxy resin is sourced from Hubei Langbowan Biomedical Co., Ltd., with an epoxy equivalent (g / eq): 263; epoxy value (eq / 100g): 0.38; softening point (°C): 62. The epoxypropoxypropyl-terminated polydimethylsiloxane is sourced from Hubei Xinmingtai Chemical Co., Ltd., with a purity of 98%. Boron trifluoride diethyl ether complex is boron trifluoride diethyl ether, sourced from Shandong Yinglang Chemical Co., Ltd., with a purity of 99%. Hyperbranched BIS-MPA polyester-4th generation-hydroxyl is sourced from Hubei Shixing Chemical Co., Ltd., with a purity of 99%. AC-PEG-NHS is sourced from Xi'an Kaixin Biotechnology Co., Ltd. Aminopropyl double-terminated polydimethylsiloxane is sourced from Wuhan Jushun Chemical Co., Ltd., with a purity of 99%. Boron nitride is hexagonal boron nitride nanosheets, sourced from Zhejiang Yamei Nanotechnology Co., Ltd. Barium sulfate is 2000 mesh, with a purity of over 97%. Fe (iron powder), Cr (chromium powder), Ni (nickel powder), Mo (molybdenum powder), and W (tungsten powder) all have a D50 of less than 3μm. 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propene oxide is sourced from Henan Alpha Chemical Co., Ltd., with a purity of 98%. Tetrabutylphosphine bromide is sourced from Shanghai Mairui Biochemical Technology Co., Ltd., with a purity of 98%. 3-(trihydroxysilyl)propylmethyl phosphate was sourced from Hubei Xinrunde Chemical Co., Ltd., with a purity of 97%. 4,4'-Diaminodicyclohexylmethane (HMDA) was sourced from Hubei Xinjiecheng Chemical Technology Co., Ltd., with a purity of 99%. The purity of all other substances was above 99%.

[0050] Recommended application methods for the anti-corrosion metal primers prepared in the above embodiments: Dry film thickness should be controlled at 40–50 μm, applied by brush, roller, or spray. Natural curing: Surface dry in 1.5–2 hours at temperatures above 15°C, fully cured in 24–26 hours. Low-temperature baking curing: Baking at 50–60°C, surface dry in 25–35 minutes, fully cured in 12–14 hours. Recoating interval: 2.5–3 hours.

[0051] Comparative Example 1 The difference from Example 1 is that no interface anchoring promoter is added to component B.

[0052] Comparative Example 2 The difference from Example 1 is that the modified alloy powder is replaced by a mixed metal powder of 32 parts Fe, 23 parts Cr, 22 parts Ni, 12 parts Mo, and 6.5 parts W.

[0053] Comparative Example 3 The difference from Example 1 is that 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propene oxide is not added in the preparation of the modified resin.

[0054] Comparative Example 4 The difference from Example 1 is that in the coating and modified resin, the polycyclic carbonate diluent is completely replaced by propylene glycol methyl ether.

[0055] Comparative Example 5 The difference from Example 1 is that hyperbranched BIS-MPA polyester-4th generation-hydroxyl is not added in the preparation of the curing agent.

[0056] Comparative Example 6 The difference from Example 1 is that AC-PEG-NHS is not added in the preparation of the curing agent.

[0057] Comparative Example 7 The difference from Example 1 is that the curing agent is replaced by Baxxodur EC331 (BASF alicyclic amine curing agent).

[0058] I. Pencil Hardness: Test standard: GB / T 6739 "Determination of Hardness of Paints and Varnishes by Pencil Method".

[0059] Substrate and film thickness: Carbon steel plate, dry film thickness 40μm (natural curing). Three parallel samples per group.

[0060] Test method: Pencil hardness tester, 750g constant load, pencil at 45° to the board surface, push the pencil at the same position of the paint film three times at a uniform speed, and record the highest pencil hardness without obvious scratches or exposure of the base material.

[0061] II. Flexibility: Test standard: GB / T 1731 "Test method for flexibility of paint film and putty film".

[0062] Substrate and film thickness: Standard flexible test plate, dry film thickness 40μm (natural curing). Three parallel samples per group.

[0063] Test method: Using a shaft, the paint film is bent outward 180°, and the minimum shaft diameter without cracks, peeling, or wrinkling is recorded.

[0064] III. Impact Resistance: Test standard: GB / T 1732 "Test method for impact resistance of paint film".

[0065] Substrate and film thickness: Tinplate, dry film thickness 40μm (natural curing). Three parallel samples per group.

[0066] Test method: The test panel is placed flat on an anvil with the paint film facing upwards; a 1kg hammer is dropped from a height of 50cm for free frontal impact, with each test panel impacted three times at different locations; the appearance of the paint film is observed using a 4x magnifying glass. Evaluation grades: Grade 0: No cracks, no peeling, no exposed substrate, no wrinkling; Grade 1: Slight cracks, no peeling; Grade 2: Obvious cracks, localized small-area peeling; Grade 3: Severe cracking, large-area peeling, exposed substrate.

[0067] IV. Cross-cut adhesion: Test standard: GB / T 9286 "Cross-cut test for paints and varnishes".

[0068] Substrate and film thickness: Carbon steel plate, galvanized plate, and aluminum alloy plate, with a uniform dry film thickness of 40μm (natural curing). Three parallel samples were prepared for each substrate.

[0069] Test Method: Using a 1mm spacing cross-cutting tool, cut a 10×10 cross grid to the substrate; gently brush away loose debris with a soft brush, apply special adhesion test tape, let stand for 5 minutes, and then quickly peel it off at a 60° angle in one go; observe the appearance of the paint film with a magnifying glass. Evaluation Grades: Grade 0: The cut edges are completely smooth, with no peeling within the grid; Grade 1: Small area peeling at the cut intersections, peeling area ≤5%; Grade 2: Peeling area 5% < and ≤15%; Grade 3: Peeling area 15% < and ≤35%; Grade 4: Peeling area 35% < and ≤65%; Grade 5: Peeling area >65%.

[0070] V. Resistance to damp heat: Test standard: GB / T 1740 "Determination of resistance to damp heat of paint film".

[0071] Substrate and film thickness: Carbon steel plate, dry film thickness 40μm (natural curing). Three parallel samples per group.

[0072] Test conditions: Constant temperature and humidity chamber: 47℃, relative humidity 96%RH, continuous test for 1000h. After the test, the room temperature was allowed to recover for 2h, and the appearance of the paint film was observed.

[0073] Appearance evaluation levels: Level 0: No bubbling, no rust, no cracking, no peeling, no powdering, no loss of gloss or discoloration; Level 1: Very few microbubbles (diameter < 0.5 mm), no peeling; Level 2: A few small bubbles, slight yellowing in some areas; Level 3: Obvious bubbling, slight peeling; Level 4: Large-area bubbling, large-scale peeling, powdering.

[0074] VI. Resistant to immersion in chemical media: Test standard: GB / T 1763 "Determination of chemical resistance of paint film".

[0075] Substrate and film thickness: Carbon steel plate, dry film thickness 40μm (natural curing); the edges and back of the test plate were completely sealed with a paraffin-rosin mixture. A cross-shaped scratch was made on the coating surface with a scribe bar, penetrating the coating and exposing the substrate. Three parallel samples were used for each group of tests for each medium.

[0076] Test conditions: 25℃ constant temperature full immersion, with the following media and immersion times: 3.5wt% NaCl solution, immersion for 1000h; 5wt% H2SO4 solution, immersion for 168h; 5% NaOH solution, immersion for 168h. Observe the appearance of the paint film, and rate it the same as the "5. Moisture and Heat Resistance" appearance evaluation level, and measure the single-sided corrosion spread width (mm) at the scribing line.

[0077] VII. Temperature and humidity circulation / high and low temperature alternation: Substrate and film thickness: Carbon steel plate, dry film thickness 40μm (natural curing). Three parallel samples per group.

[0078] Cyclic procedure: -20℃ for 2 hours, 25℃ for 30 minutes, 60℃ and 90%RH for 4 hours, 25℃ for 30 minutes; a total of 20 cycles. After the test, observe the appearance of the paint film and rate it the same as the "5. Moisture and Heat Resistance" appearance evaluation level.

[0079] Table 1 Test Results Table 1 (continued) Test Results Note 1: The above data are average values, and the data range of parallel samples is statistically significant.

[0080] Note 2: Although the ratings of the comparative examples are the same as those of the examples, the appearance of the paint film is relatively worse than that of the examples.

[0081] The primers in Examples 1 to 3, through the compounding of fluorosilicone-phosphorus hybrid modified resin, synergistic functional fillers, hyperbranched hybrid curing agents, and interface anchoring systems, construct a physical shielding and passivation corrosion inhibition mechanism. Bisphenol S epoxy resin provides high rigidity, hydrolysis resistance, and media resistance as the main chain; epoxy-terminated polydimethylsiloxane introduces flexible segments, reducing internal stress and improving hydrophobicity; tetrafluoropropoxypropylene oxide imparts ultra-low surface energy to the coating film, blocking the penetration of corrosive media; silicon-based phosphate strengthens interfacial adhesion through Si-OM covalent bonds, while also providing passivation sites, achieving multiple effects of structural toughness, media resistance, low surface energy, and interface anchoring. Sintered modified Fe-Cr-Ni-Mo-W alloy powder provides mild and long-lasting protection, avoiding the rapid reaction defects of pure zinc powder; Schiff base cobalt complexes in corrosive media H... + Cl -Upon invasion, the organic ligands undergo hydrolysis to achieve Co 2+ Slow-release, Co 2+ It forms a complex passivation film on the metal surface to inhibit corrosion; Fe-Cr-Ni-Mo-W alloy powder is sintered at high temperature to form a uniform alloy phase with an electrode potential lower than that of the steel substrate, achieving mild sacrificial anode cathodic protection and avoiding the rapid reaction caused by excessive electrode potential difference of pure zinc powder. Barium sulfate and hexagonal boron nitride construct a layered physical shielding network, extending the penetration path of corrosive media and simultaneously improving the hardness and scratch resistance of the paint film. Hyperbranched BIS-MPA polyester provides high crosslinking density and dense film formation; AC-PEG-NHS introduces flexible segments and low-temperature reactivity; aminopropyl polydimethylsiloxane further toughens and hydrophobizes; HMDA alicyclic amine ensures rapid curing at room temperature and low temperature, achieving an overall balance of high crosslinking and high toughness, avoiding the performance imbalance of traditional epoxy. Polycyclic carbonate diluent is a reactive diluent with low VOC and participates in crosslinking, reducing curing shrinkage and defects; zirconate interface anchoring accelerator achieves bidirectional chemical bonding between the substrate and the coating, eliminating weak interfacial layers; BYK's additive system precisely controls wetting, dispersion, and defoaming to ensure a continuous and defect-free paint film.

[0082] Comparative Example 1 lacked an interface anchoring accelerator. The absence of the interface anchoring accelerator directly eliminated the bidirectional chemical bonding between the coating and the substrate, failing to break the dense, inert oxide film on the aluminum and galvanized sheet surfaces. The low surface energy substrate and coating relied solely on physical adsorption and hydrogen bonding, resulting in a noticeably weak transition layer at the interface. Water molecules easily penetrated along the interface in humid, hot, and salt spray environments, causing interface debonding and water phase aggregation, leading to performance degradation. Although some performance indicators were the same as in the examples, the overall film condition was inferior.

[0083] In Comparative Example 2, the modified alloy powder was replaced with unsintered, uncoupled original mixed metal powder. The loss of the uniform alloy phase structure formed by high-temperature sintering and the surface modification effect of the titanate coupling agent is the core reason for the performance degradation. The large differences in electrode potentials among the individual elements of the simply physically mixed metal powder lead to uncontrolled and uneven cathodic protection, which in turn accelerates localized corrosion of the substrate. The loose structure of the unsintered powder, after combining with the resin, forms numerous interfacial voids. The uncoupled powder has high surface energy, is prone to agglomeration, and is unevenly dispersed, not only increasing internal defects in the paint film and significantly reducing physical shielding, but also creating stress concentration points, resulting in a comprehensive decline in the paint film's flexibility, impact resistance, hardness, and other mechanical properties. The filler-resin interface becomes a rapid penetration channel for corrosive media, allowing water and ions to easily penetrate, significantly deteriorating resistance to media, damp heat, and temperature and humidity cycling, with a greater degree of corrosion propagation at the scribing points.

[0084] The modified resin in Comparative Example 3 lacked 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propene oxide. This absence caused the paint film to lose the ultra-low surface energy, high hydrophobicity, and high bond energy CF bond structure imparted by fluorine. The surface energy of the paint film increased significantly, and its hydrophilicity was greatly enhanced. The adsorption and penetration rates of water molecules, chloride ions, and acid / alkali media on the paint film surface and inside the film were significantly increased, rendering the physical shielding effect essentially ineffective. Without the protection of strong CF bonds, the resin's resistance to hydrolysis, acids and alkalis, salt spray, and damp heat significantly decreased, and the molecular chains were prone to degradation and breakage. Simultaneously, the wettability and compatibility of the paint film with low surface energy substrates decreased, and the adhesion to light metal substrates worsened. Under temperature and humidity cycling, the synergistic effect of media intrusion and resin degradation exacerbated blistering, cracking, and peeling of the paint film, and the corrosion spread at the scribing points expanded.

[0085] In Comparative Example 4, the polycyclic carbonate diluent was completely replaced with propylene glycol methyl ether. The reactivity, low shrinkage, high compatibility, and film-forming properties of polycyclic carbonate were lost. The pure volatile solvent evaporated rapidly and completely during curing, leading to a significant increase in the film's curing shrinkage rate, generating substantial internal stress, microcracks, and pinholes, resulting in a complete collapse of the film's density. Without the internal plasticizing and toughening effects of polycyclic carbonate, the film's hardness was lower, brittleness increased, and impact resistance and flexibility decreased. The channels formed after solvent evaporation became rapid penetration defects for corrosive media, allowing water and ions to easily diffuse into the film, resulting in a comprehensive deterioration in resistance to media, humidity, and temperature cycling. Simultaneously, the compatibility between the resin and filler decreased, filler dispersion became uneven, and interfacial defects increased, ultimately leading to a simultaneous deterioration in the film's adhesion and anti-corrosion performance.

[0086] Comparative Example 5's curing agent lacked hyperbranched BIS-MPA polyester-4th generation-hydroxyl groups. This absence caused the curing system to lose its structural advantages of high crosslinking density, low viscosity, dense film formation, and multi-point anchoring. The crosslinking point density decreased significantly, resulting in a loose film structure, increased porosity, and a marked weakening of physical shielding ability. The curing reaction was dominated by linear crosslinking, leading to high internal stress and insufficient toughness, resulting in poor flexibility, impact resistance, and crack resistance of the film. Reduced curing reactivity resulted in incomplete curing at low temperatures, leaving a large number of unreacted groups in the film, which easily absorb water and degrade, thus reducing resistance to media and damp heat. The discontinuous crosslinking network could not effectively block corrosive media, allowing them to easily penetrate the film, leading to increased corrosion spread at the scribing points. After temperature and humidity cycling, the film was prone to powdering and peeling.

[0087] Comparative Example 6 did not contain AC-PEG-NHS as a curing agent. The lack of flexibility, hydrophilic-hydrophobic balance, low-temperature reactivity, and stress relaxation capabilities imparted by the polyether segments resulted in a significant increase in the rigidity of the cured system, and a decrease in the film's flexibility and impact resistance. Under high and low temperature cycling, it was prone to microcracks due to stress concentration. The hydrophilic-hydrophobic balance of the film was disrupted, leading to decreased stability in aqueous media and reduced resistance to salt spray and damp heat. The activity and cross-linking uniformity of the curing reaction decreased, resulting in incomplete curing in localized areas, forming weak interfaces and internal defects. Simultaneously, the interfacial compatibility of the film with the substrate decreased, leading to poor adhesion to light metal substrates. Furthermore, during cyclic aging, the degradation of adhesion and film appearance was further exacerbated.

[0088] In Comparative Example 7, the curing agent was replaced with a commercially available alicyclic amine curing agent (Baxxodur EC331). Commercially available alicyclic amine curing agents lack the hyperbranched, polyether, and siloxane hybrid customized structure of the self-made curing agent, and cannot achieve the multifunctional synergistic effect of hyperbranched polyester, polyether segments, siloxane, and alicyclic amine. The commercial curing agent has a linear structure and a single crosslinking form, failing to achieve a balance between high density and high toughness, resulting in a hard and brittle film. Without the modification of siloxane and polyether segments, the hydrophobicity, media resistance, hydrolysis resistance, and low shrinkage of the film are far lower than those of the self-made curing system. It also exhibits poor compatibility and interfacial adaptability with fluorosilicone-phosphorus hybrid resins, resulting in weak interfacial bonding between the coating and the substrate, and decreased adhesion to light metal substrates. The internal stress generated during curing is relatively large, making the film prone to cracking, delamination, and blistering under temperature and humidity cycling and acid / alkali / salt corrosion environments. Its long-term anti-corrosion performance and durability are far lower than those of the self-made hybrid curing agent.

Claims

1. A corrosion-resistant metal primer, characterized in that, The primer is made by mixing component A and component B in a mass ratio of 100:(22-25), and adjusting the viscosity to 3500-5500 mPa·s with an environmentally friendly solvent. Component A includes the following raw materials in parts by mass: 12-15 parts modified alloy powder, 3-5 parts Schiff base cobalt complex, 10-12 parts barium sulfate, 1-2 parts boron nitride, 50-55 parts modified resin, 1-1.5 parts wetting agent, 0.5-0.7 parts rheology modifier, 0.3-0.4 parts defoamer, 6-8 parts polycyclic carbonate diluent, and 6-8 parts environmentally friendly solvent. Component B includes the following raw materials in parts by mass: 96-98 parts curing agent and 2-4 parts interface anchoring accelerator. The modified alloy powder is prepared by sintering metal powder at 1250-1350℃ in a mass ratio of Fe:Cr:Ni:Mo:W = (30-35):(20-25):(20-25):(10-15):(5-8), followed by surface modification with a titanate coupling agent after pulverization. The Schiff base cobalt complex is prepared by reacting salicylaldehyde with ethylenediamine in anhydrous ethanol at a molar ratio of 2:(1-1.2) to obtain a Schiff base ligand, and then reacting it with cobalt acetate in anhydrous ethanol at a molar ratio of 1:(1.02-1.05) with stirring. The modified resin is prepared by mixing bisphenol S epoxy resin, epoxypropoxypropyl-terminated polydimethylsiloxane, 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propene oxide, tetrabutylphosphine bromide, and 3-(trihydroxysilyl)propylmethyl phosphate in a ratio of (60-65):(20-25):(9-11):(0.3-0.4):(3.0-3.4), and then adjusting the solid content to 45-50 wt% with a mixture of polycyclic carbonate diluent and propylene glycol methyl ether. The polycyclic carbonate diluent is a product with pH 7.0 to 7.5 prepared from a complex of propylene carbonate, propylene glycol methyl ether, and boron trifluoride ethyl ether at a mass ratio of (80-85):(20-25):(0.4-0.6). The curing agent is a hyperbranched BIS-MPA polyester-4th generation-hydroxyl, AC-PEG-NHS, aminopropyl dual-terminated polydimethylsiloxane: 4,4'-diaminodicyclohexylmethane in a mass ratio of (25-30):(35-40):(11-13):(20-25). The hyperbranched BIS-MPA polyester-4th generation-hydroxyl, AC-PEG-NHS and aminopropyl dual-terminated polydimethylsiloxane are stirred in propylene glycol methyl ether acetate at 45-50°C, and the propylene glycol methyl ether acetate is recovered to obtain an intermediate. Then, it is stirred with 4,4'-diaminodicyclohexylmethane at 45-50°C to obtain the final product.

2. The anti-corrosion metal primer according to claim 1, characterized in that, The wetting agent is BYK-190; the rheology modifier is BYK-410; the defoamer is BYK-1790; the environmentally friendly solvent is propylene glycol methyl ether; and the interface anchoring promoter is a zirconate coupling agent.

3. The anti-corrosion metal primer according to claim 1, characterized in that, The preparation method of the modified alloy powder includes the following steps: sintering metal powder of 30-35 parts Fe, 20-25 parts Cr, 20-25 parts Ni, 10-15 parts Mo, and 5-8 parts W at 1250-1350℃ for 2-3 hours by mass, pulverizing into powder, adding 8-10 times the mass of the powder to an anhydrous ethanol solution of titanate coupling agent of 1.0-1.5wt%, dispersing, filtering, and drying to obtain the modified alloy powder.

4. The anti-corrosion metal primer according to claim 1, characterized in that, The preparation method of the Schiff base cobalt complex includes the following steps: salicylaldehyde and ethylenediamine are added to anhydrous ethanol at a molar ratio of 2:(1-1.2), refluxed at 75-80°C for 2-2.5 h, cooled to crystallize, filtered, and the Schiff base ligand is obtained; the Schiff base ligand and cobalt acetate are added to anhydrous ethanol at a molar ratio of 1:(1.02-1.05), stirred at 65-70°C for 5-6 h, filtered, washed, and dried to obtain the Schiff base cobalt complex.

5. The anti-corrosion metal primer according to claim 1, characterized in that, The preparation method of the modified resin includes the following steps: 60-65 parts by weight of bisphenol S epoxy resin, 20-25 parts by weight of epoxypropoxypropyl-terminated polydimethylsiloxane, and 9-11 parts by weight of 3-(2,2,3,3-tetrafluoropropoxy)-1,2-propylene oxide are mixed at 130-140°C; 0.3-0.4 parts by weight of tetrabutylphosphine bromide are added at 110-120°C and stirred; 3.0-3.4 parts by weight of 3-(trihydroxysilyl)propylmethyl phosphate are added at 90-100°C and stirred; a mixture of polycyclic carbonate diluent and propylene glycol methyl ether in a mass ratio of 2:(1-1.5) is added at 60-70°C to adjust the solid content to 45-50 wt%, and the mixture is filtered to obtain the modified resin.

6. The anti-corrosion metal primer according to claim 1 or 5, characterized in that, The preparation method of the polycyclic carbonate diluent includes the following steps: 80-85 parts by weight of propylene carbonate and 20-25 parts by weight of propylene glycol methyl ether are mixed, 0.4-0.6 parts by weight of boron trifluoride diethyl ether complex are added at 55-60°C and stirred, followed by vacuum distillation, and neutralization with triethylamine to pH 7.0-7.5 to obtain the polycyclic carbonate diluent.

7. The anti-corrosion metal primer according to claim 1, characterized in that, The preparation method of the curing agent includes the following steps: Dissolve 25-30 parts by weight of hyperbranched BIS-MPA polyester-4th generation-hydroxyl in 20-25 parts by weight of propylene glycol methyl ether acetate to obtain solution I; dissolve 35-40 parts by weight of AC-PEG-NHS in 15-20 parts by weight of propylene glycol methyl ether acetate to obtain solution II; stir solution I and 11-13 parts by weight of aminopropyl double-terminated polydimethylsiloxane, add solution II dropwise, stir at 45-50°C for 4-5 hours, and recover propylene glycol methyl ether acetate by vacuum distillation to obtain an intermediate; stir the intermediate with 20-25 parts by weight of 4,4'-diaminodicyclohexylmethane at 45-50°C for 1-1.5 hours to obtain the curing agent.

8. The method for preparing an anti-corrosion metal primer according to claim 1, characterized in that, Includes the following steps: S1: Mix modified alloy powder, Schiff base cobalt complex, barium sulfate and boron nitride to obtain a premix; mix modified resin, polycyclic carbonate diluent and environmentally friendly solvent, add wetting agent, rheology modifier and defoamer, add the premix and disperse, grind to fineness <15μm, filter to obtain component A; S2: Component B is prepared by mixing the curing agent and the interface anchoring accelerator; S3: When using, mix components A and B according to the formula, adjust the viscosity to 3500-5500 mPa·s with an environmentally friendly solvent, and cure to obtain an anti-corrosion metal primer.

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