Special high-adhesion anti-stripping primer for metal base material and preparation method of special high-adhesion anti-stripping primer

Abstract

The invention relates to a high-adhesion anti-stripping primer special for a metal substrate and a preparation method thereof, and belongs to the technical field of paints.The primer comprises silane modified phosphoramidate chelating resin, graphite oxide-Schiff base zirconium-siloxane hybrid filler, a hyperbranched polyamide-siloxane bonding accelerant, an isocyanate curing agent, functional auxiliaries and the like. The silane modified phosphoramidate chelating resin is prepared by carrying out a reaction on bisphenol F epoxy resin and diethylenetriamine, and carrying out a reaction on p-toluenesulfonic acid, diethyl phosphite, KH540 and hydroquinone. The graphite oxide-Schiff base zirconium-siloxane hybrid filler is prepared from the following components: GO-SB, ZrO2-siloxane core-shell particles, zirconium n-propoxide and the like. The hyperbranched polyamide-siloxane bonding accelerator is prepared by the following steps: reacting ethylenediamine with methyl acrylate, then reacting with ethylenediamine, and then modifying with KH540 and perfluoroalkyl phosphate. The problems that a traditional primer is weak in interface bonding force, easy to peel off and insufficient in corrosion resistance are solved.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a high-adhesion, anti-peeling primer for metal substrates and its preparation method. Background Technology

[0002] Metallic materials, with their superior mechanical properties, processing performance, and structural stability, have become core substrates in equipment manufacturing, construction engineering, transportation, marine engineering, and home appliances and electronics. During service, metal components such as carbon steel, stainless steel, aluminum alloys, galvanized sheets, and magnesium alloys are susceptible to atmospheric corrosion, humidity erosion, acid and alkali media, mechanical impact, and thermal cycling, leading to rust, oxidation, and strength reduction, directly shortening equipment lifespan and increasing maintenance costs. Metal coating protection systems are a key means of inhibiting corrosion and extending service life. The primer, as the bottom layer in direct contact with the metal substrate, plays a crucial role in interface anchoring, blocking corrosive media, and enhancing interlayer adhesion, thus forming the foundation of the entire protection system.

[0003] Currently, the mainstream industrial metal substrate primers are epoxy, acrylic, alkyd, and inorganic zinc silicate primers. Epoxy primers, with their active groups such as hydroxyl and epoxy groups, form a certain degree of adhesion to the metal surface and are widely used in heavy-duty corrosion protection. Acrylic primers dry quickly and have excellent workability, making them suitable for light metals and decorative coatings. Inorganic zinc-rich primers rely on the sacrificial anode effect of zinc powder to achieve long-term corrosion protection for steel structures. However, traditional primers mostly rely on physical adsorption, mechanical intercalation, and weak polarity to achieve adhesion, and their performance shortcomings are becoming increasingly prominent under complex working conditions and long-term protection requirements.

[0004] Existing metal substrate primers still generally suffer from core problems such as insufficient adhesion, easy peeling, and poor acid and alkali resistance. Firstly, weak interfacial bonding is the primary defect: the dense passivation film and low surface energy of surfaces like stainless steel, aluminum alloys, and galvanized sheets lead to uneven wetting and spreading of the primer, making it difficult to form stable chemical bonds. Oxide scale, rust, and oil residue on carbon steel surfaces block effective contact between the coating and the substrate; physical adsorption alone cannot resist external forces and media corrosion, easily resulting in paint film peeling and curling during cross-cut tests. Secondly, insufficient resistance to peeling and temperature changes: the large difference in thermal expansion coefficients between the primer resin and the metal creates internal stress at the interface under alternating hot and cold temperatures, leading to long-term accumulation and causing paint film cracking and delamination. Some primers have insufficient cross-linking density after curing, resulting in poor toughness and easy peeling from the substrate under mechanical vibration and impact, especially in complex areas such as corners and welds. Traditional metal primers struggle to meet the stringent requirements of high-end manufacturing, marine environments with high salt spray, extreme temperature variations, and long-term corrosion protection. Insufficient adhesion and easy peeling directly restrict the reliability and durability of metal components. Therefore, developing specialized primers for metal substrates with high adhesion, peel resistance, and acid and alkali resistance, and establishing efficient and stable preparation methods, has become an urgent need in the industrial coating field. Summary of the Invention

[0005] Traditional metal substrate primers often suffer from poor adhesion, peel resistance, and acid / alkali resistance, and their performance needs improvement. This invention provides a high-adhesion, peel-resistant primer for metal substrates and its preparation method. Through molecular design involving resin modification, filler hybridization, and accelerator functionalization, along with synergistic compounding of components, a multi-layered interfacial bonding system with chemical anchoring, physical integration, and shielding protection is constructed, simultaneously forming an organic-inorganic interpenetrating cross-linked coating structure. This fundamentally solves the problems of weak interfacial adhesion, easy peeling, poor acid / alkali resistance, temperature change resistance, and insufficient corrosion resistance in traditional metal primers. It is suitable for various types of metal substrates and complex working conditions, providing long-term stable protection for metal components. The specific technical solution is as follows:

[0006] A high-adhesion, anti-stripping primer for metal substrates comprises the following raw materials in parts by weight: 400-450 parts of silane-modified amino phosphate chelating resin, 80-120 parts of graphite oxide-Schiff base zirconium-siloxane hybrid filler, 30-50 parts of hyperbranched polyamide-siloxane bonding accelerator, functional additives, 45-60 parts of isocyanate curing agent, and 260-290 parts of composite environmentally friendly solvent; The silane-modified aminophosphate chelating resin is prepared by reacting bisphenol F epoxy resin with diethylenetriamine in isopropanol and xylene solvent, then adding p-toluenesulfonic acid and diethyl phosphite, and finally adding KH540 to react with hydroquinone. The graphene oxide-Schiff base zirconium-siloxane hybrid filler is a nanoscale solid prepared by dispersing GO-SB and ZrO2-siloxane core-shell particles together in ethylene glycol methyl ether and isopropanol, and then reacting with a zirconium propoxide solution in ethylene glycol methyl ether. The nano-ZrO2-siloxane core-shell particles are prepared by dispersing nano-zirconia in anhydrous ethanol and deionized water, adjusting the pH to 4.5-5.0, adding a mixture of methyltrimethoxysilane, vinyltriethoxysilane, dilute hydrochloric acid (pH 3-4), and deionized water, and stirring. The GO-SB is prepared by dispersing multilayer graphene oxide in anhydrous ethanol, reacting with KH540 to obtain GO-NH2, then dispersing it in anhydrous ethanol, and reacting with salicylaldehyde and glacial acetic acid. The hyperbranched polyamide-siloxane bonding promoter is prepared by reacting ethylenediamine with methyl acrylate in anhydrous methanol and toluene, followed by vacuum evaporation to obtain a viscous liquid A. The viscous liquid A is dissolved in anhydrous methanol and reacted with ethylenediamine, followed by vacuum evaporation to obtain a viscous liquid B. The viscous liquid B is then reacted with KH540 in toluene and propylene glycol methyl ether acetate, followed by the addition of perfluoroalkyl phosphate and propylene glycol methyl ether acetate and stirring to obtain the final product.

[0007] In the aforementioned primer, the functional additives include 5-8 parts of thixotropic anti-sagging agent, 6-9 parts of defoamer, 3-5 parts of UV absorption stabilizer, and 10-15 parts of rust and corrosion inhibitor synergist.

[0008] In the above primer, the composite environmentally friendly solvent includes xylene, propylene glycol methyl ether acetate, isopropanol, and ethylene glycol butyl ether in a mass ratio of (3-4):(2-3):(2-2.5):(1-1.5).

[0009] Furthermore, the silane-modified aminophosphate chelating resin is prepared by reacting bisphenol F epoxy resin, diethylenetriamine, p-toluenesulfonic acid, diethyl phosphite, KH540, and hydroquinone in a mass ratio of (300-350):(80-90):(8-10):(100-120):(90-100):(1-2). The bisphenol F epoxy resin is reacted with diethylenetriamine in isopropanol and xylene solvent at 70-78°C, then p-toluenesulfonic acid and diethyl phosphite are added and reacted at 90-95°C, and finally KH540 is added and reacted with hydroquinone at 70-75°C.

[0010] Furthermore, the preparation method of the silane-modified aminophosphate chelating resin includes the following steps: 300-350 parts by mass of bisphenol F epoxy resin, 200-250 parts by mass of isopropanol, and 50-80 parts by mass of xylene are stirred and dissolved at 70-78°C; 80-90 parts by mass of diethylenetriamine are added dropwise; the mixture is stirred and reacted at 70-78°C for 3-4 hours; the temperature is lowered to 55-60°C; 8-10 parts by mass of p-toluenesulfonic acid and 100-120 parts by mass of diethyl phosphite are added; the mixture is refluxed at 90-95°C for 3.5-4.5 hours; the temperature is lowered to 50-55°C; 90-100 parts by mass of KH540 and 1-2 parts by mass of hydroquinone polymerization inhibitor are added; the mixture is reacted at 70-75°C for 2-3 hours; and the mixture is distilled under reduced pressure to obtain the silane-modified aminophosphate chelating resin.

[0011] Furthermore, the graphene oxide-Schiff base zirconium-siloxane hybrid filler is GO-SB, nano-ZrO2-siloxane core-shell particles, and an 80wt% zirconium propoxide solution in ethylene glycol methyl ether at a mass ratio of (10-20):(40-60):(15-20). GO-SB and ZrO2-siloxane core-shell particles are co-dispersed in ethylene glycol methyl ether and isopropanol, and an 80wt% zirconium propoxide solution in ethylene glycol methyl ether is added and reacted at 90-95℃ to obtain a nanoscale solid. The nano-ZrO2-siloxane core-shell particles are nano-zirconium dioxide, methyltrimethoxysilane, vinyltriethoxysilane, and pH 3-4 dilute hydrochloric acid at a mass ratio of (120-150):(80-90):(40-5). The solid was prepared by dispersing nano-zirconia in anhydrous ethanol and deionized water at a mass ratio of 0:(0.5-0.6), adjusting the pH to 4.5-5.0, adding a mixture of methyltrimethoxysilane, vinyltriethoxysilane, dilute hydrochloric acid at pH 3-4, and deionized water, and stirring. The GO-SB was prepared by dispersing multilayer graphene oxide, KH540, salicylaldehyde, and glacial acetic acid at a mass ratio of (10-20):(20-30):(20-30):(1-1.5). Multilayer graphene oxide was dispersed in anhydrous ethanol, KH540 was added, and the mixture was reacted at 65-70℃ to obtain GO-NH2, which was then dispersed in anhydrous ethanol, and salicylaldehyde and glacial acetic acid were added and reacted at 65-70℃ to obtain the solid.

[0012] Furthermore, the preparation method of the graphite oxide-Schiff base zirconium-siloxane hybrid filler includes the following steps: N1: By weight, 120-150 parts of nano-zirconia were added to 500-600 parts of anhydrous ethanol and 50-60 parts of deionized water, ultrasonically dispersed, and the pH was adjusted to 4.5-5.0 to obtain a suspension; 80-90 parts of methyltrimethoxysilane and 40-50 parts of vinyltriethoxysilane were mixed, and 1-2 parts of deionized water and 0.5-0.6 parts of dilute hydrochloric acid with pH 3-4 were added, followed by the suspension. The mixture was stirred at 55-60℃ for 6-8 hours, centrifuged, the precipitate was washed, and vacuum dried to obtain nano-ZrO2-siloxane core-shell particles; N2: By weight, 10-20 parts of multilayer graphene oxide were added to 200-250 parts of anhydrous ethanol, ultrasonically dispersed, and 20-30 parts of KH540 were added. The mixture was refluxed at 65-70℃ for 10-12 hours, filtered, and the solid was collected and vacuum dried to obtain GO-NH2. GO-NH2 was dispersed in 200-250 parts of anhydrous ethanol, and 20-30 parts of salicylaldehyde and 1-1.5 parts of glacial acetic acid catalyst were added. The mixture was refluxed at 65-70℃ for 5-6 hours to remove water, filtered, the solid was washed, and dried to obtain GO-SB. N3: By mass, 10-20 parts of GO-SB and 40-60 parts of nano ZrO2-siloxane core-shell particles are co-dispersed in 200-250 parts of ethylene glycol methyl ether and 50-60 parts of isopropanol. 15-20 parts of an 80% zirconium propoxide solution in ethylene glycol methyl ether are added dropwise. The mixture is refluxed at 90-95°C for 9-10 hours. After centrifugation, the solid is washed and vacuum dried to obtain nanoscale graphite oxide-Schiff base zirconium-siloxane hybrid filler.

[0013] Furthermore, the hyperbranched polyamide-siloxane bonding promoter is ethylenediamine and methyl acrylate in a mass ratio of (80-100):(350-400). Ethylenediamine reacts with methyl acrylate in anhydrous methanol and toluene at 25-30°C, followed by vacuum evaporation to obtain a viscous liquid A. Then, viscous liquid A and ethylenediamine are dissolved in anhydrous methanol in a mass ratio of (400-500):(80-100). The mixture was reacted with ethylenediamine at 40–45 °C and evaporated under reduced pressure to obtain viscous liquid B. Then, viscous liquid B, KH540, and perfluoroalkyl phosphate were reacted with KH540 in toluene and propylene glycol methyl ether acetate at 60–65 °C. Perfluoroalkyl phosphate and propylene glycol methyl ether acetate were then added at 40–45 °C and stirred to obtain the final product.

[0014] Furthermore, the preparation method of the hyperbranched polyamide-siloxane bonding accelerator includes the following steps: M1: Dissolve 80-100 parts by weight of ethylenediamine in 200-250 parts of anhydrous methanol and 50-60 parts of toluene, and add 350-400 parts of methyl acrylate dropwise at below 10°C; react in a sealed environment at 25-30°C for 20-24 hours; evaporate under reduced pressure to obtain viscous liquid A; M2: Dissolve 400-500 parts by weight of viscous liquid A in 200-300 parts by weight of anhydrous methanol, add 80-100 parts by weight of ethylenediamine, react in a sealed container at 40-45°C for 10-12 hours, and evaporate under reduced pressure to obtain viscous liquid B. M3: Dissolve 400-500 parts by weight of viscous liquid B in 150-200 parts of toluene and 50-60 parts of propylene glycol methyl ether acetate, add 90-100 parts of KH540, and react in a sealed container at 60-65°C for 6-7 hours. Cool to 40-45°C, add 20-30 parts of perfluoroalkyl phosphate and 40-60 parts of propylene glycol methyl ether acetate, stir for 12-14 hours, let stand, filter, and vacuum dry to obtain hyperbranched polyamide-siloxane bonding promoter.

[0015] The preparation method of the above-mentioned high-adhesion, anti-peeling primer for metal substrates includes the following steps: S1: According to the primer formula, add defoamer to the composite environmentally friendly solvent, stir, add silane-modified amino phosphate chelating resin and hyperbranched polyamide-siloxane bonding accelerator, stir, add graphite oxide-Schiff base zirconium-siloxane hybrid filler, stir, grind to a fineness of less than 30μm, add thixotropic anti-sagging agent, ultraviolet absorption stabilizer and rust inhibitor synergist, stir evenly to obtain the base material; S2: Add isocyanate curing agent to the base material, stir, let stand for aging, vacuum degas, filter, and obtain primer.

[0016] This invention provides a high-adhesion, anti-peeling primer for metal substrates and its preparation method, with the following beneficial effects: I. This invention, a high-adhesion, anti-peeling primer for metal substrates, utilizes molecular design—including resin modification, filler hybridization, and accelerator functionalization—and synergistic compounding of components to construct a multi-layered interfacial bonding system that chemically anchors, physically integrates, and provides shielding protection. Simultaneously, it forms an organic-inorganic interpenetrating cross-linked coating structure. This fundamentally solves the problems of weak interfacial bonding, easy peeling, poor acid and alkali resistance, temperature change resistance, and insufficient corrosion performance of traditional metal primers. It achieves a performance balance of high adhesion, high peeling resistance, high mechanical strength, and long-lasting corrosion protection. It is compatible with various types of metal substrates such as stainless steel, aluminum alloy, galvanized sheet, and carbon steel, meeting the stringent protection requirements of complex working conditions such as high salt spray in the ocean, extreme temperature changes, and high-end manufacturing.

[0017] II. Silane-Modified Aminophosphate Chelating Resin: Through stepwise temperature-controlled reactions of amination, phosphorylation, and silane modification, P-OH, -NH2, and Si-OR active functional groups are precisely introduced, and the proportions of each raw material are designed to achieve an optimal balance of functional group density. This resin can not only form chelate bonds, coordination bonds, and Me-O-Si covalent bonds with the metal surface, upgrading traditional physical adsorption to chemical bond-level interface anchoring, but also improve the resin crosslinking density and cohesive force, while retaining appropriate toughness and reducing the interfacial internal stress caused by the difference in thermal expansion coefficients between the resin and the metal, thus solving the problems of insufficient adhesion and temperature-induced cracking at the molecular level.

[0018] III. Graphite Oxide-Schiff Base Zirconium-Siloxane Hybrid Filler: Through stepwise modification of core-shell, Schiff base, and hybrid bridging, Zr-OC and Zr-O-Si chemical bonds of GO-SB and ZrO2-siloxane core-shell particles are bridged. The sheet-like GO-SB extends the diffusion path of the corrosive medium, the Schiff base groups complex with the corrosive metal ions to achieve surface passivation, and the nano-ZrO2 core-shell particles improve the coating hardness and disperse external stress, avoiding coating cracking and peeling caused by stress concentration. Moreover, the ultrasonic dispersion, pH adjustment, and temperature control reaction parameters in the preparation steps ensure the nanoscale dispersibility of the filler and prevent agglomeration to form coating defects.

[0019] IV. Hyperbranched Polyamide-Siloxane Bonding Accelerator: A functional accelerator with high branching degree and high active group density is prepared through a stepwise reaction of end-group modification, hyperbranching synthesis, and siloxane and fluorine modification. The hyperbranched structure enables it to penetrate into the micro-defects of the metal substrate to achieve physical integration. The amino, amide, and siloxane groups on the molecular chain form multiple hydrogen bonds, coordination bonds, and covalent bonds at the interface, strengthening the interfacial bonding. The introduction of perfluoroalkyl phosphate gives it ultra-low surface tension, which allows it to spread efficiently on the surface of low surface energy substrates such as stainless steel and galvanized sheet, replacing the weak adsorption layer to achieve surface activation. Temperature control and material ratio in each step ensure that the surface tension (<21mN / m) and amino content (>3.5mmol / g) of the accelerator reach the optimal values.

[0020] V. Functional Additives and Composite Environmentally Friendly Solvents: The formulation design of functional additives such as thixotropic anti-sagging agents and defoamers optimizes the application performance of the primer and reduces defects such as sagging and pinholes during application. Composite environmentally friendly solvents achieve efficient dissolution and dispersion of various materials, ensuring system compatibility, while adjusting the primer viscosity to the optimal application range to avoid coating film defects caused by poor solvent compatibility.

[0021] VI. The mixing preparation method of this invention adopts a step-by-step process of solvent dispersion, resin and accelerator compounding, filler grinding, additive addition, curing agent compounding, and degassing filtration, which ensures the film quality and performance of the primer. Adding the defoamer before dispersing the resin and accelerator avoids the inability to eliminate bubbles generated by high-speed stirring, ensuring the density of the coating film. Other additives are added after grinding to prevent thixotropic anti-sagging agents and UV absorption stabilizers from being destroyed during grinding, ensuring their functional effectiveness. The curing agent is added before application to avoid uneven local curing leading to a decrease in interfacial adhesion, while simultaneously removing bubbles from the system, further improving the density of the coating.

[0022] VII. The components of the primer of the present invention achieve a good synergistic effect through the interaction of active functional groups, the complementarity of structures, and the synergy of functions.

[0023] The P-OH, -NH2, and Si-OR groups of the resin, the Zr-O-Si and Schiff base groups of the filler, and the amino and siloxane groups of the accelerator form a multi-bonded network of chelate, coordinate, covalent, and hydrogen bonds at the metal interface, fundamentally improving interfacial adhesion, far superior to the anchoring effect of a single chemical bond. The organic polyurethane and polyurea networks formed after resin curing, the inorganic siloxane network formed with siloxanes, and the physical reinforcement network formed by hybrid fillers constitute an organic-inorganic interpenetrating cross-linked structure, which improves the mechanical strength of the coating while retaining appropriate flexibility, achieving a balance between strength and toughness. The chelating passivation of the resin phosphate groups, the corrosion inhibition effect of aluminum tripolyphosphate, the physical shielding of graphene, and the hydrophobic properties of siloxanes form a synergistic anti-corrosion system from three dimensions: inhibiting corrosion reactions, blocking corrosive media, and slowing corrosion of the metal surface, significantly improving the coating's salt spray resistance, acid and alkali resistance, and long-term corrosion resistance. The accelerator's ultra-low surface tension enables highly efficient wetting of low surface energy metal substrates, while its hyperbranched structure achieves microscopic physical integration. This, combined with the chemical anchoring of the resin and fillers, forms a dual interfacial bonding system of chemical anchoring and physical integration, solving the problems of poor wetting and weak adhesion of traditional primers on substrates such as stainless steel and aluminum alloys. Simultaneously, the isocyanate curing agent, acting as a crosslinking core, reacts with the active hydrogen groups in the resin and accelerator, crosslinking the active functional groups of the respective materials into a unified whole, further enhancing the interfacial adhesion, density, and mechanical strength of the coating. Detailed Implementation

[0024] Some embodiments are given below, but the present invention is not limited to these embodiments.

[0025] Glossary: ​​GO-NH2 is amino-modified multilayer graphene oxide; GO-SB is a multilayer graphene oxide-based Schiff base.

[0026] Example 1 A high-adhesion, anti-stripping primer for metal substrates comprises the following raw materials in parts by weight: 420 parts of silane-modified aminophosphate chelating resin, 100 parts of graphite oxide-Schiff base zirconium-siloxane hybrid filler, 40 parts of hyperbranched polyamide-siloxane bonding accelerator, functional additives, 54 parts of isocyanate curing agent, and 275 parts of composite environmentally friendly solvent. The functional additives include 6 parts of thixotropic anti-sagging agent, 7 parts of defoamer, 4 parts of UV absorption stabilizer, and 13 parts of rust and corrosion inhibitor synergist. The composite environmentally friendly solvent comprises xylene, propylene glycol methyl ether acetate, isopropanol, and ethylene glycol butyl ether in a mass ratio of 3.5:2.5:2.3:1.3. Among them, the thixotropic anti-sagging agent used is BYK-410; the defoamer used is BYK-A530; the UV absorption stabilizer used is Tinuvin 328; the rust and corrosion inhibitor synergist used is aluminum tripolyphosphate (APP); and the isocyanate curing agent used is Basonat HI 100.

[0027] The preparation method of silane-modified aminophosphate chelating resin includes the following steps: Under nitrogen protection, 320 parts by mass of bisphenol F epoxy resin, 230 parts by mass of isopropanol, and 65 parts by mass of xylene are added to a reaction vessel, a sealed reflux condenser is installed, the temperature is raised to 70-78℃, and the mixture is stirred at 400 r / min until completely dissolved; 85 parts by mass of diethylenetriamine are added dropwise at a uniform rate over 1.5 h, and the mixture is stirred at 400 r / min over 70-78℃ for 3.5 h; the temperature is lowered to 58℃, and then... Add 9 parts of p-toluenesulfonic acid and 110 parts of diethyl phosphite, stir at 400 r / min until homogeneous, then reflux at 90-95℃ for 4 h; cool to 53℃, add 95 parts of KH540 and 1.5 parts of hydroquinone polymerization inhibitor, heat to 70-75℃ and stir at 400 r / min for 2.5 h; perform vacuum distillation at 65-75℃ and -0.08 MPa to remove low-boiling substances from the system, obtaining silane-modified aminophosphate chelating resin.

[0028] The preparation method of the graphene oxide-Schiff base zirconium-siloxane hybrid filler includes the following steps: N1: By mass, 135 parts of nano-zirconia were added to 550 parts of anhydrous ethanol and 55 parts of deionized water, and ultrasonically dispersed at 300W for 40 min. The pH was adjusted to 4.8 using a glacial acetic acid-sodium acetate buffer system to activate the surface hydroxyl groups, resulting in a suspension. 85 parts of methyltrimethoxysilane and 45 parts of vinyltriethoxysilane were mixed, and 1.5 parts of deionized water and 0.55 parts of dilute hydrochloric acid at pH 3.5 were added to promote hydrolysis. The mixture was then added to the suspension and stirred in a sealed environment at 55-60℃ and 320 r / min for 7 h. After centrifugation at 8200 r / min for 18 min, the precipitate was washed three times with anhydrous ethanol and vacuum dried at 75-80℃ for 11 h to obtain nano-ZrO2-siloxane core-shell particles. N2: By mass, 15 parts of multilayer graphene oxide were added to 220 parts of anhydrous ethanol and ultrasonically dispersed at 300W for 40 min. Then, 25 parts of KH540 were added, and the mixture was refluxed at 400 r / min in a temperature range of 65–70℃ for 11 h. After filtration, the solid was collected and vacuum dried at 60–70℃ to obtain GO-NH2. GO-NH2 was dispersed in 220 parts of anhydrous ethanol, and 25 parts of salicylaldehyde and 1.2 parts of glacial acetic acid catalyst were added. A water separator was installed, and the mixture was refluxed at 400 r / min in a temperature range of 65–70℃ for 5.5 h until no water was generated. After filtration, the solid was washed twice with anhydrous ethanol and dried to obtain GO-SB. N3: By mass fraction, 15 parts of GO-SB and 50 parts of nano-ZrO2-siloxane core-shell particles were co-dispersed in 220 parts of ethylene glycol methyl ether and 55 parts of isopropanol. 18 parts of n-propoxide zirconium solution (mass concentration 80%, solvent: ethylene glycol methyl ether) were added dropwise. The mixture was refluxed at 400 r / min for 9.5 h under nitrogen protection at a temperature of 90-95 °C. After centrifugation at 8200 r / min for 18 min, the solid was washed three times with acetone and vacuum dried at 55-60 °C for 13 h to obtain nano-scale graphene oxide-Schiff base zirconium-siloxane hybrid filler.

[0029] The preparation method of the hyperbranched polyamide-siloxane bonding accelerator includes the following steps: M1: Under nitrogen protection, 90 parts by mass of ethylenediamine were dissolved in 220 parts by mass of anhydrous methanol and 55 parts by mass of toluene. 380 parts by mass of methyl acrylate were added dropwise at a rate of 2.5 mL / min in a temperature range of 5–8 °C. After the addition was complete, the mixture was reacted in a sealed environment at 400 r / min in a temperature range of 25–30 °C for 22 h. Anhydrous methanol and methyl acrylate were removed by vacuum evaporation in a temperature range of 40–45 °C to obtain viscous liquid A. M2: Dissolve 450 parts of viscous liquid A in 250 parts of anhydrous methanol by mass, add 90 parts of ethylenediamine, react in a closed environment at 40-45℃ and 400r / min for 11h, and then evaporate under reduced pressure at 45-50℃ to remove anhydrous methanol and ethylenediamine to obtain viscous liquid B. M3: By mass, 450 parts of viscous liquid B were dissolved in 180 parts of toluene and 55 parts of propylene glycol methyl ether acetate, and 95 parts of KH540 were added. Under nitrogen protection, the mixture was reacted in a closed environment at 400 r / min for 6.5 h at a temperature of 60–65 °C. The temperature was then lowered to 40–45 °C, and 25 parts of perfluoroalkyl phosphate and 50 parts of propylene glycol methyl ether acetate were added. The mixture was stirred in a closed environment at 400 r / min for 13 h, allowed to stand, filtered to remove impurities, and vacuum dried at 60–65 °C for 22 h to remove residual toluene and methanol generated in the reaction, resulting in a hyperbranched polyamide-siloxane bonding accelerator with a surface tension of <21 mN / m and an amino content of >3.5 mmol / g in a 0.1% aqueous solution at 25 °C.

[0030] The preparation method of the above-mentioned high-adhesion, anti-peeling primer for metal substrates includes the following steps: S1: According to the primer formula, add the composite environmentally friendly solvent to the dispersion tank, stir in a closed container at 320 r / min, add defoamer, and stir and disperse for 18 min; add silane-modified amino phosphate chelating resin and hyperbranched polyamide-siloxane bonding accelerator, increase the speed to 620 r / min, and stir for 25 min until uniform; reduce the speed to 320 r / min, add graphite oxide-Schiff base zirconium-siloxane hybrid filler, increase the speed to 1100 r / min, and stir in a closed container for 35 min; transfer to a horizontal sand mill, grind to a fineness of less than 30 μm, and control the grinding temperature below 45℃; after grinding, discharge the material, add thixotropic anti-sagging agent, ultraviolet absorption stabilizer, and rust and corrosion inhibitor synergist under stirring at 320 r / min, stir evenly, and obtain the base material; S2: Before construction, transfer the base material to the paint mixing tank, add the isocyanate curing agent, stir at 450r / min for 12min, let it stand for 18min, degas under vacuum at -0.055MPa for 18min, and filter through 100 mesh to obtain the primer.

[0031] Example 2 A high-adhesion, anti-stripping primer for metal substrates comprises the following raw materials in parts by weight: 400 parts of silane-modified aminophosphate chelating resin, 80 parts of graphite oxide-Schiff base zirconium-siloxane hybrid filler, 30 parts of hyperbranched polyamide-siloxane bonding accelerator, functional additives, 45 parts of isocyanate curing agent, and 260 parts of composite environmentally friendly solvent. The functional additives include 5 parts of thixotropic anti-sagging agent, 6 parts of defoamer, 3 parts of UV absorption stabilizer, and 10 parts of rust and corrosion inhibitor synergist. The composite environmentally friendly solvent comprises xylene, propylene glycol methyl ether acetate, isopropanol, and ethylene glycol butyl ether in a mass ratio of 3:2:2:1. Specifically, the thixotropic anti-sagging agent used is BYK-410; the defoamer used is BYK-066N; the UV absorption stabilizer used is Tinuvin 328; the rust and corrosion inhibitor synergist used is aluminum tripolyphosphate (APP); and the isocyanate curing agent used is Basonat HI 100.

[0032] The preparation method of silane-modified aminophosphate chelating resin includes the following steps: Under nitrogen protection, 300 parts by mass of bisphenol F epoxy resin, 200 parts by mass of isopropanol, and 50 parts by mass of xylene are added to a reaction vessel, a sealed reflux condenser is installed, the temperature is raised to 70-78℃, and the mixture is stirred at 300 r / min until completely dissolved; 80 parts by mass of diethylenetriamine are added dropwise at a uniform rate over 1 hour, and the mixture is stirred at 300 r / min over 70-78℃ for 3 hours; the temperature is lowered to 55℃, and then... Eight parts of p-toluenesulfonic acid and 100 parts of diethyl phosphite were stirred at 300 r / min until homogeneous, and then refluxed at 90–95 °C for 3.5 h. The mixture was then cooled to 50 °C, and 90 parts of KH540 and 1 part of hydroquinone polymerization inhibitor were added. The mixture was then heated to 70–75 °C and stirred at 300 r / min for 2 h. The mixture was then subjected to vacuum distillation at 65–75 °C and a vacuum degree of -0.07 MPa to remove low-boiling substances from the system, yielding a silane-modified aminophosphate chelate resin.

[0033] The preparation method of the graphene oxide-Schiff base zirconium-siloxane hybrid filler includes the following steps: N1: By mass, 120 parts of nano-zirconia were added to 500 parts of anhydrous ethanol and 50 parts of deionized water, and ultrasonically dispersed at 300W for 30 min. The pH was adjusted to 4.5 using a glacial acetic acid-sodium acetate buffer system to activate the surface hydroxyl groups, resulting in a suspension. 80 parts of methyltrimethoxysilane and 40 parts of vinyltriethoxysilane were mixed, and 1 part of deionized water and 0.5 parts of dilute hydrochloric acid at pH 3 were added to promote hydrolysis. The mixture was then added to the suspension and stirred in a sealed environment at 55-60℃ and 300 r / min for 6 h. After centrifugation at 8000 r / min for 15 min, the precipitate was washed three times with anhydrous ethanol and vacuum dried at 75-80℃ for 10 h to obtain nano-ZrO2-siloxane core-shell particles. N2: By mass, 10 parts of multilayer graphene oxide were added to 200 parts of anhydrous ethanol, ultrasonically dispersed at 300W for 30 min, 20 parts of KH540 were added, and the mixture was refluxed at 300 r / min in a temperature range of 65-70℃ for 10 h. After filtration, the solid was collected and vacuum dried in a temperature range of 60-70℃ to obtain GO-NH2. GO-NH2 was dispersed in 200 parts of anhydrous ethanol, 20 parts of salicylaldehyde and 1 part of glacial acetic acid catalyst were added, a water separator was installed, and the mixture was refluxed at 300 r / min in a temperature range of 65-70℃ for 5 h until no water was generated. After filtration, the solid was washed twice with anhydrous ethanol and dried to obtain GO-SB. N3: By mass fraction, 10 parts of GO-SB and 40 parts of nano-ZrO2-siloxane core-shell particles were co-dispersed in 200 parts of ethylene glycol methyl ether and 50 parts of isopropanol. 15 parts of n-propoxide zirconium solution (mass concentration 80%, solvent: ethylene glycol methyl ether) were added dropwise. The mixture was refluxed at 300 r / min for 9 h under nitrogen protection at a temperature of 90-95 °C. After centrifugation at 8000 r / min for 15 min, the solid was washed three times with acetone and vacuum dried at 55-60 °C for 12 h to obtain nano-scale graphene oxide-Schiff base zirconium-siloxane hybrid filler.

[0034] The preparation method of the hyperbranched polyamide-siloxane bonding accelerator includes the following steps: M1: Under nitrogen protection, 80 parts by mass of ethylenediamine were dissolved in 200 parts of anhydrous methanol and 50 parts of toluene. 350 parts of methyl acrylate were added dropwise at a rate of 2 mL / min in a temperature range of 5–8 °C. After the addition was complete, the mixture was reacted in a sealed environment at 25–30 °C and 300 r / min for 20 h. Anhydrous methanol and methyl acrylate were removed by vacuum evaporation in a temperature range of 40–45 °C to obtain a viscous liquid A. M2: Dissolve 400 parts of viscous liquid A in 200 parts of anhydrous methanol by mass, add 80 parts of ethylenediamine, react in a closed environment at 300 r / min at 40-45℃ for 10 h, and then evaporate under reduced pressure at 45-50℃ to remove anhydrous methanol and ethylenediamine to obtain viscous liquid B. M3: By mass, 400 parts of viscous liquid B were dissolved in 150 parts of toluene and 50 parts of propylene glycol methyl ether acetate, and 90 parts of KH540 were added. The mixture was then reacted under nitrogen protection at a temperature of 60–65°C and a speed of 300 r / min for 6 h in a sealed environment. The temperature was then lowered to 40–45°C, and 20 parts of perfluoroalkyl phosphate and 40 parts of propylene glycol methyl ether acetate were added. The mixture was stirred at a speed of 300 r / min in a sealed environment for 12 h. After standing, the mixture was filtered to remove impurities and then vacuum dried at 60–65°C for 20 h to remove residual toluene and methanol generated during the reaction. This yielded a hyperbranched polyamide-siloxane bonding accelerator with a surface tension of <21 mN / m and an amino content of >3.5 mmol / g in a 0.1% aqueous solution at 25°C.

[0035] The preparation method of the above-mentioned high-adhesion, anti-peeling primer for metal substrates includes the following steps: S1: According to the primer formula, add the composite environmentally friendly solvent to the dispersion tank, stir at 300 r / min in a closed manner, add defoamer, and stir and disperse for 15 min; add silane-modified amino phosphate chelating resin and hyperbranched polyamide-siloxane bonding accelerator, increase the speed to 600 r / min, and stir for 20 min until uniform; reduce the speed to 300 r / min, add graphite oxide-Schiff base zirconium-siloxane hybrid filler, increase the speed to 1000 r / min, and stir in a closed manner for 30 min; transfer to a horizontal sand mill, grind to a fineness of less than 30 μm, and control the grinding temperature below 45℃; after grinding, discharge the material, add thixotropic anti-sagging agent, ultraviolet absorption stabilizer, and rust and corrosion inhibitor synergist under stirring at 300 r / min, stir evenly, and obtain the base material; S2: Before construction, transfer the base material to the paint mixing tank, add the isocyanate curing agent, stir at 400r / min for 10min, let it stand for 15min, degas under vacuum at -0.05MPa for 15min, and filter through 100 mesh to obtain the primer.

[0036] Example 3 A high-adhesion, anti-stripping primer for metal substrates comprises the following raw materials in parts by weight: 450 parts of silane-modified aminophosphate chelating resin, 120 parts of graphite oxide-Schiff base zirconium-siloxane hybrid filler, 50 parts of hyperbranched polyamide-siloxane bonding accelerator, functional additives, 60 parts of isocyanate curing agent, and 290 parts of composite environmentally friendly solvent. The functional additives include 8 parts of thixotropic anti-sagging agent, 9 parts of defoamer, 5 parts of UV absorption stabilizer, and 15 parts of rust and corrosion inhibitor synergist. The composite environmentally friendly solvent comprises xylene, propylene glycol methyl ether acetate, isopropanol, and ethylene glycol butyl ether in a mass ratio of 4:3:2.5:1.5. Among them, the thixotropic anti-sagging agent used is BYK-430; the defoamer used is BYK-A530; the UV absorption stabilizer used is Tinuvin 292; the rust and corrosion inhibitor synergist used is aluminum tripolyphosphate (APP); and the isocyanate curing agent used is Basonat HI 100.

[0037] The preparation method of silane-modified aminophosphate chelating resin includes the following steps: Under nitrogen protection, 350 parts by mass of bisphenol F epoxy resin, 250 parts by mass of isopropanol, and 80 parts by mass of xylene are added to a reaction vessel, a sealed reflux condenser is installed, the temperature is raised to 70-78℃, and the mixture is stirred at 500 r / min until completely dissolved; 90 parts by mass of diethylenetriamine are added dropwise at a uniform rate over 2 hours, and the mixture is stirred at 500 r / min over 4 hours at 70-78℃; the temperature is lowered to 60℃, and 1 part by mass of isopropanol is added to the reaction vessel. 0 parts of p-toluenesulfonic acid and 120 parts of diethyl phosphite were stirred at 500 r / min until homogeneous, and then refluxed at 90–95 °C for 4.5 h. The mixture was then cooled to 55 °C, and 100 parts of KH540 and 2 parts of hydroquinone polymerization inhibitor were added. The mixture was then heated to 70–75 °C and stirred at 500 r / min for 3 h. The mixture was then subjected to vacuum distillation at 65–75 °C and a vacuum degree of -0.085 MPa to remove low-boiling substances from the system, yielding a silane-modified aminophosphate chelate resin.

[0038] The preparation method of the graphene oxide-Schiff base zirconium-siloxane hybrid filler includes the following steps: N1: By mass, 150 parts of nano-zirconia were added to 600 parts of anhydrous ethanol and 60 parts of deionized water, and ultrasonically dispersed at 350W for 50 min. The pH was adjusted to 5.0 using a glacial acetic acid-sodium acetate buffer system to activate the surface hydroxyl groups, resulting in a suspension. 90 parts of methyltrimethoxysilane and 50 parts of vinyltriethoxysilane were mixed, and 2 parts of deionized water and 0.6 parts of dilute hydrochloric acid at pH 4 were added to promote hydrolysis. The mixture was then added to the suspension and stirred in a sealed environment at 55-60℃ and 350 r / min for 8 h. After centrifugation at 8500 r / min for 20 min, the precipitate was washed four times with anhydrous ethanol and vacuum dried at 75-80℃ for 12 h to obtain nano-ZrO2-siloxane core-shell particles. N2: By mass, 20 parts of multilayer graphene oxide were added to 250 parts of anhydrous ethanol and ultrasonically dispersed at 350W for 50 min. Then, 30 parts of KH540 were added, and the mixture was refluxed at 500 r / min in a temperature range of 65-70℃ for 12 h. After filtration, the solid was collected and vacuum dried at 60-70℃ to obtain GO-NH2. GO-NH2 was dispersed in 250 parts of anhydrous ethanol, and 30 parts of salicylaldehyde and 1.5 parts of glacial acetic acid catalyst were added. A water separator was installed, and the mixture was refluxed at 500 r / min in a temperature range of 65-70℃ for 6 h until no water was generated. After filtration, the solid was washed three times with anhydrous ethanol and dried to obtain GO-SB. N3: By mass fraction, 20 parts of GO-SB and 60 parts of nano-ZrO2-siloxane core-shell particles were co-dispersed in 250 parts of ethylene glycol methyl ether and 60 parts of isopropanol. 20 parts of n-propoxide zirconium solution (mass concentration 80%, solvent: ethylene glycol methyl ether) were added dropwise. The mixture was refluxed at 500 r / min for 10 h at 90-95 °C under nitrogen protection, centrifuged at 8500 r / min for 20 min, and the solid was washed 4 times with acetone and vacuum dried at 55-60 °C for 14 h to obtain nano-scale graphene oxide-Schiff base zirconium-siloxane hybrid filler.

[0039] The preparation method of the hyperbranched polyamide-siloxane bonding accelerator includes the following steps: M1: Under nitrogen protection, 100 parts by mass of ethylenediamine were dissolved in 250 parts of anhydrous methanol and 60 parts of toluene. 400 parts of methyl acrylate were added dropwise at a rate of 3 mL / min in a temperature range of 5–8 °C. After the addition was complete, the mixture was reacted in a sealed environment at 500 r / min in a temperature range of 25–30 °C for 24 h. Anhydrous methanol and methyl acrylate were removed by vacuum evaporation in a temperature range of 40–45 °C to obtain a viscous liquid A. M2: Dissolve 500 parts of viscous liquid A in 300 parts of anhydrous methanol by mass, add 100 parts of ethylenediamine, react in a closed environment at 40-45℃ and 500 r / min for 12 h, and then evaporate under reduced pressure at 45-50℃ to remove anhydrous methanol and ethylenediamine to obtain viscous liquid B. M3: By mass, 500 parts of viscous liquid B were dissolved in 200 parts of toluene and 60 parts of propylene glycol methyl ether acetate, and 100 parts of KH540 were added. Under nitrogen protection, the mixture was reacted in a closed environment at 500 r / min at a temperature of 60–65 °C for 7 h. The temperature was then lowered to 40–45 °C, and 30 parts of perfluoroalkyl phosphate and 60 parts of propylene glycol methyl ether acetate were added. The mixture was stirred in a closed environment at 500 r / min for 14 h, allowed to stand, filtered to remove impurities, and vacuum dried at 60–65 °C for 24 h to remove residual toluene and methanol generated in the reaction, resulting in a hyperbranched polyamide-siloxane bonding accelerator with a surface tension of <21 mN / m and an amino content of >3.5 mmol / g in a 0.1% aqueous solution at 25 °C.

[0040] The preparation method of the above-mentioned high-adhesion, anti-peeling primer for metal substrates includes the following steps: S1: According to the primer formula, add the composite environmentally friendly solvent to the dispersion tank, stir at 350 r / min in a closed manner, add defoamer, and stir and disperse for 20 min; add silane-modified amino phosphate chelating resin and hyperbranched polyamide-siloxane bonding accelerator, increase the speed to 650 r / min, and stir for 30 min until uniform; reduce the speed to 350 r / min, add graphite oxide-Schiff base zirconium-siloxane hybrid filler, increase the speed to 1200 r / min, and stir in a closed manner for 40 min; transfer to a horizontal sand mill, grind to a fineness of less than 30 μm, and control the grinding temperature below 45℃; after grinding, discharge the material, add thixotropic anti-sagging agent, ultraviolet absorption stabilizer, and rust and corrosion inhibitor synergist under stirring at 350 r / min, stir evenly, and obtain the base material; S2: Before construction, transfer the base material to the paint mixing tank, add the isocyanate curing agent, stir at 500r / min for 15min, let it stand for 20min, degas at -0.06MPa vacuum for 20min, and filter through 150 mesh to obtain the primer.

[0041] In the above embodiments: In the preparation of graphite oxide-Schiff base zirconium-siloxane hybrid fillers N1, N2, and N3, and in the preparation of hyperbranched polyamide-siloxane bonding promoters M1, M2, and M3, all "parts by mass" mentioned in each step are equivalent to "mass ratios." These are all implemented independently for their respective individual steps. The proportions of materials used in each step are only applicable to the material input and reaction process of that specific step and have no relation or conversion relationship with the parts by mass in other steps. Each step independently completes the material input and reaction operations according to its own part-by-part standard.

[0042] The raw materials used in the above embodiments are as follows: Aluminum tripolyphosphate (APP) is from Wuhan Jiyesheng Chemical Co., Ltd., 1250 mesh. Bisphenol F epoxy resin is from Nantong Runfeng Petrochemical Co., Ltd., liquid resin with an epoxy value ranging from 0.56 to 0.63 Eq / 100g. KH540 is γ-aminopropyltrimethoxysilane, from Hubei Xinjiecheng Chemical Technology Co., Ltd. The average particle size of nano-zirconia is 40nm to 50nm, monoclinic phase, from Hangzhou Jiupeng New Materials Co., Ltd. The multilayer graphene oxide has fewer than 10 layers and is from Shanghai Jiadeer Chemical Technology Co., Ltd. Zirconium n-propoxide is from Hubei Chengfeng Chemical Co., Ltd., with a purity of 99%. Perfluoroalkyl phosphate is from Guangdong Wengjiang Chemical Reagent Co., Ltd. The purity of other substances is above 99%.

[0043] Comparative Example 1 The difference from Example 1 is that the graphite oxide-Schiff base zirconium-siloxane hybrid filler is changed to 150 parts and the hyperbranched polyamide-siloxane bonding promoter is changed to 10 parts.

[0044] Comparative Example 2 The difference from Example 1 is that the silane-modified aminophosphate chelating resin is replaced by 320 parts of bisphenol F epoxy resin with 65 parts of xylene, that is, no chelation or modification is performed.

[0045] Comparative Example 3 The difference from Example 1 is that the preparation method of silane-modified aminophosphate chelating resin omits the steps of "cooling down to 53°C, adding 95 parts of KH540 and 1.5 parts of hydroquinone polymerization inhibitor, heating up to 70-75°C and stirring at 400 r / min for 2.5 h".

[0046] Comparative Example 4 The difference from Example 1 is that the preparation method of silane-modified aminophosphate chelating resin omits the steps of "adding 85 parts of diethylenetriamine at a uniform rate for 1.5 hours, stirring at 400 r / min for 3.5 hours in a temperature range of 70-78℃; cooling to 58℃, adding 9 parts of p-toluenesulfonic acid and 110 parts of diethyl phosphite, stirring evenly at 400 r / min, and then refluxing at a temperature range of 90-95℃ for 4 hours".

[0047] Comparative Example 5 The difference from Example 1 is that in the preparation method of graphene oxide-Schiff base zirconium-siloxane hybrid filler, steps N1 and N2 are omitted, nano ZrO2-siloxane core-shell particles in N3 are replaced by nano zirconium dioxide, and GO-SB is replaced by multilayer graphene oxide.

[0048] Comparative Example 6 The difference from Example 1 is that the graphene oxide-Schiff base zirconium-siloxane hybrid filler is directly replaced by a mixture of multilayer graphene oxide and nano zirconium dioxide in a mass ratio of 15:50.

[0049] Comparative Example 7 The difference from Example 1 is that in the preparation method of hyperbranched polyamide-siloxane bonding promoter, step M2 is omitted, and viscous liquid B in M3 is directly replaced by viscous liquid A.

[0050] Comparative Example 8 The difference from Example 1 is that in the preparation method of hyperbranched polyamide-siloxane bonding promoter, perfluoroalkyl phosphate is not added to M3.

[0051] I. Cross-cut adhesion test: Sample specifications: The substrate is 304 stainless steel plate, 5052 aluminum alloy plate, galvanized plate, Q235 carbon steel plate. The surface is polished with 400-grit sandpaper and cleaned to remove oil. The dry film thickness is 30±2μm. Three parallel samples are prepared for each group.

[0052] Test parameters: Conducted according to GB / T 9286 "Cross-cut test for paints and varnishes", using a multi-blade cutter with 1mm spacing to cut horizontally and vertically through to the substrate to form 25 small squares; using 3M 600 tape, peel off at a uniform speed of approximately 60° within 0.5 seconds after application within 90 seconds; observe the paint film peeling, grade and evaluate according to the standard, and record the grade (grade 0 is the best).

[0053] II. Cupping test (resistance to deformation and spalling): Sample specifications: Q235 carbon steel plate, dry film thickness 30±2μm, 3 parallel samples were prepared for each group.

[0054] Test parameters: The test shall be conducted in accordance with GB / T 9753 "Cupping test for paints and varnishes". The paint-coated side of the test plate shall be clamped between the mold and the punch with the paint-coated side facing up. The test plate shall be pressed at a constant speed of 0.2 mm / s until the indentation depth is 5.0 mm. The paint film shall be observed with a 4x magnifying glass to see if cracks, splits or peeling occur, and the results shall be recorded.

[0055] III. Temperature Cyclic Impact Adhesion Test: Sample specifications: sandblasted Q235 carbon steel plate (Sa2.5 grade), dry film thickness 85±2μm. At the same time, blank control group (without temperature cycling) and test group were prepared for the pull-off adhesion test, and 5 parallel samples were prepared for each group.

[0056] Test parameters: Tests were conducted according to GB / T 1735 "Determination of heat resistance of paints and varnishes", ASTM D4541-17, and GB / T 5210 "Paints and varnishes - Pull-off adhesion test", using a thermal shock test chamber and a pull-off adhesion tester. The cycle program was: -40℃ for 2 hours, then switching to 80℃ for 2 hours within 5 minutes, for a total of 20 cycles. After the cycles, the test plates were placed in a 23℃ environment for 2 hours to recover, and then immediately subjected to the pull-off adhesion test according to GB / T 5210, with a loading rate of 1.0 MPa / s. Adhesion retention rate (%) = (average breaking strength of test group / average breaking strength of blank group) × 100%.

[0057] IV. Impact resistance test: Sample specifications: tinplate (compliant with GB / T 9271 standard), dry film thickness 30±2μm, 3 parallel samples prepared for each group.

[0058] Test parameters: The test shall be conducted in accordance with GB / T 1732 "Test Method for Impact Resistance of Paint Film". The paint film impact tester shall be placed with the painted surface facing up on the anvil. A 1kg hammer shall be dropped from a height of 50cm to impact the center of the test plate. The paint film in the impact area shall be observed with a 4x magnifying glass to see if cracks, wrinkles or peeling occur, and the results shall be recorded.

[0059] V. Flexibility (bending test): Sample specifications: tinplate (compliant with GB / T 9271 standard), dry film thickness 30±2μm, 3 parallel samples prepared for each group.

[0060] Test parameters: The test shall be conducted in accordance with GB / T 1731 "Determination of Flexibility of Paint Film and Putty Film". A cylindrical shaft bending tester shall be used. The painted side of the test board shall be placed on a 2mm shaft and bent around the shaft 180°. The paint film shall be observed with a 4x magnifying glass to see if cracks or peeling occur, and the results shall be recorded.

[0061] VI. Paint film hardness (pencil method) test: Sample specifications: Q235 carbon steel plate, dry film thickness 30±2μm, 3 parallel samples were prepared for each group.

[0062] Test parameters: The test shall be conducted in accordance with GB / T 6739 "Determination of Hardness of Paints and Varnishes by Pencil Method". A pencil of known hardness and a load of 750g shall be used. The pencil shall be held at a 45° angle to the test plate and shall be drawn forward at a speed of 1 mm / s for at least 7 mm. Starting from the hardest pencil, each pencil level shall be drawn 5 times until at least 4 of the 5 consecutive pencil levels show visible defects (scratches, abrasions). The hardness of the previous pencil level that does not cause defects in the coating shall be recorded as the hardness of the paint film.

[0063] VII. Neutral Salt Spray Resistance Test: Sample specifications: sandblasted Q235 carbon steel plate (Sa2.5 grade), dry film thickness 85±2μm, the sample plate was scribbled through one side to the substrate, the edge was sealed with paraffin, and 3 parallel samples were prepared for each group.

[0064] Test parameters: The test was conducted according to GB / T 1771 "Determination of resistance to neutral salt spray of paints and varnishes", using a salt spray test chamber, 5wt% NaCl solution, test temperature 35℃, continuous spraying for 1000h; after the test, the salt frost was gently rinsed with clean water and dried at room temperature for 2h; the blistering and rusting of the paint film were observed, the maximum width of corrosion spread on one side of the cross-cut was measured, and the cross-cut adhesion test was conducted according to GB / T 9286.

[0065] 8. Acid and alkali resistance (media resistance) test: Sample specifications: Q235 carbon steel plate, dry film thickness 30±2μm, edges sealed with paraffin, 3 parallel samples prepared for each group.

[0066] Test parameters: According to GB / T 9274 "Determination of resistance to liquid media for paints and varnishes", the paints and varnishes were immersed in 5wt% H2SO4 solution and 5wt% NaOH solution for 168h at 23±2℃ respectively. After being removed and allowed to recover for 2h, the cross-cut adhesion test was performed according to GB / T 9286. The results were recorded and compared with the original adhesion.

[0067] Table 1 Average values ​​of test results Note: Example 2, with a salt spray resistance rating of 1000h and a cross-cut test grade of 1, shows a slight warping on one side of the substrate, which is superior to Comparative Example 8.

[0068] Table 1 (continued) Average values ​​of test results The primers prepared in Examples 1 to 3, through the synergistic effect of molecular design and component compounding, constructed a multi-layer interface bonding system with chemical anchoring, physical integration, and shielding protection, and all performance indicators showed excellent performance.

[0069] The P-OH, -NH2, and Si-OR functional groups in silane-modified aminophosphate chelating resin form stable chelate bonds, coordination bonds, and covalent bonds (Me-O-Si) with hydroxyl groups and oxides on the metal surface, respectively. This upgrades the physical adsorption of traditional coatings to interface anchoring at the level of chemical bonds, thereby improving adhesion from the root. At the same time, after amine chain extension, phosphorylation, and silane coupling, the crosslinking density and cohesive force of the resin are significantly improved, while retaining moderate toughness and reducing interfacial stress caused by differences in thermal expansion coefficients.

[0070] The graphene oxide-Schiff base zirconium-siloxane hybrid filler achieves three-phase chemical bonding between the filler, resin, and substrate through Zr-OC and Zr-O-Si bridging structures; the lamellar structure of GO-SB extends the diffusion path of corrosive media, and the Schiff base groups can also complex with metal ions generated by corrosion to achieve surface passivation; nano-ZrO2-siloxane core-shell particles improve the coating hardness and disperse external stress, preventing the coating from cracking and peeling due to stress concentration.

[0071] Hyperbranched polyamide-siloxane bonding accelerators enhance the wetting and spreading ability of metal substrates, penetrating to the micro-defects of the substrate to achieve physical integration; the high density of amino, amide and siloxane groups on the molecular chain form multiple hydrogen bonds, coordination bonds and covalent bonds at the interface, further strengthening the interfacial bonding; perfluoroalkyl phosphate esters endow the accelerator with ultra-low surface tension, enabling efficient spreading on the surface of low surface energy substrates such as stainless steel and galvanized sheet, replacing the weak adsorption layer to achieve surface activation.

[0072] Under the action of isocyanate curing agents, the active functional groups in resins, fillers, and accelerators form an interpenetrating cross-linked structure of organic polyurethane, polyurea networks, inorganic siloxane networks, and metal chelate networks. This endows the coating with high density, high mechanical strength, and high chemical stability, achieving a balance of adhesion, impact resistance, flexibility, and chemical corrosion resistance. The chelating passivation of phosphate groups, the corrosion inhibition effect of aluminum tripolyphosphate, the physical shielding of graphene, and the hydrophobic properties of siloxanes work synergistically to achieve long-term corrosion protection from multiple dimensions, including inhibiting corrosion reactions, blocking corrosive media, and slowing down the corrosion of metal surfaces, significantly improving the coating's resistance to salt spray and media.

[0073] Comparative Example 1 (Excessive Filler, Insufficient Bonding Accelerator): An excessively high proportion of nanoscale hybrid fillers increases their specific surface area, leading to the adsorption of large amounts of resin, resulting in increased system viscosity, decreased wettability, and the formation of micro-defects at the interface. Insufficient bonding accelerators, on the other hand, result in the absence of chemical bridging sites between the resin, filler, and substrate, weakening the interfacial bonding force and making the filler a stress concentration point. Under external forces and corrosion, the weaker interfaces fail first, leading to a decrease in adhesion, impact resistance, and media resistance.

[0074] Comparative Example 2 (using unmodified ordinary epoxy resin): Ordinary bisphenol F epoxy resin relies solely on hydroxyl groups and ether bonds to form weak polar interactions and hydrogen bonds with metals, without chemical chelation or covalent bonding, resulting in extremely weak interfacial bonding. Furthermore, pure epoxy resin has low crosslinking density and insufficient cohesive force, lacking weather resistance and anti-corrosion design. Therefore, its adhesion on all substrates is significantly reduced, and its mechanical properties and resistance to media are comprehensively deteriorated, with performance failure being particularly significant on low surface energy substrates.

[0075] Comparative Example 3 (silane modification step of resin omitted): The absence of KH540 causes the resin to lose Si-OR functional groups, making it unable to form Me-O-Si covalent bonds with the metal surface, and also unable to build an inorganic-organic hybrid siloxane network inside the coating. The interface anchoring relies solely on amino and phosphate groups, resulting in a significant weakening of the bonding force. At the same time, the absence of the siloxane network leads to a decrease in coating density, manifested as a decrease in adhesion to low surface energy substrates and a significant decrease in media resistance.

[0076] Comparative Example 4 (omitting the amination and phosphate esterification steps of the resin): The absence of diethylenetriamine and diethyl phosphite causes the resin to lose the amino groups that form coordination bonds with the metal and the phosphate groups that form chelate bonds. These are the core groups for interfacial chemical anchoring. The resin has only a small amount of siloxane functional groups remaining, resulting in extremely low crosslinking density, insufficient cohesion, and incomplete curing of the paint film. This leads to weak interfacial bonding, poor bulk strength, and a significant decrease in mechanical properties such as cupping, impact, and bending, as well as corrosion resistance.

[0077] Comparative Example 5 (filler modification pretreatment omitted): Unmodified nano-ZrO2 and multilayer graphene oxide are prone to agglomeration in the resin, with extremely poor dispersibility, and are only physically blended with the resin without chemical bonding bridging; GO cannot achieve metal passivation through Schiff base, ZrO2 is only a rigid particle and cannot disperse stress, the filler becomes a defect channel inside the coating, corrosive media can easily penetrate, adhesion, impact resistance and corrosion resistance are significantly reduced, and stress concentration can easily cause coating peeling.

[0078] Comparative Example 6 (filler is a direct physical mixture of GO and ZrO2): Compared with Comparative Example 5, this comparative example has no chemical bonding treatment, there is no bridging structure between GO and ZrO2, they agglomerate and the interface is incompatible, resulting in a large number of structural defects inside the coating; the function of the hybrid filler is completely lost, not only failing to play a reinforcing role, but also deteriorating the coating structure, resulting in its performance being worse than that of Comparative Example 5, with more significant interface failure and corrosion propagation.

[0079] Comparative Example 7 (omitting the hyperbranching intermediate step of the accelerator): The omission of the M2 step results in the accelerator being only a first-generation linear product with insufficient branching, low molecular weight, and a significant reduction in the density of terminal active amino functional groups. Its wetting and spreading ability decreases, it cannot effectively penetrate the micro-defects of the substrate, the number of hydrogen bonds and chemical bonds formed at the interface is insufficient, and the molecular flexibility is poor and the stress release ability is weak, which leads to a decrease in the coating's resistance to deformation, temperature cycling, and impact resistance, and a decrease in the adhesion of low surface energy substrates.

[0080] Comparative Example 8 (Perfluoroalkyl phosphate modification with accelerator omitted): The absence of perfluoroalkyl phosphate significantly increases the surface tension of the accelerator, making it impossible to achieve complete spreading on low surface energy substrates such as stainless steel, aluminum alloy, and galvanized sheet. This results in the formation of craters and unbonded areas at the interface, constituting a weak boundary layer. Although the hyperbranched structure and siloxane groups can still provide a certain degree of interfacial bonding force, making the overall performance of the coating better than other comparative examples, water molecules can easily penetrate from the weak boundary layer during the erosion process, leading to a decrease in adhesion to low surface energy substrates, and slightly lower resistance to media and long-term durability compared to the examples.

Claims

1. A high-adhesion, anti-peeling primer for metal substrates, characterized in that, The raw materials include the following parts by weight: 400-450 parts of silane-modified aminophosphate chelating resin, 80-120 parts of graphite oxide-Schiff base zirconium-siloxane hybrid filler, 30-50 parts of hyperbranched polyamide-siloxane bonding accelerator, functional additives, 45-60 parts of isocyanate curing agent, and 260-290 parts of composite environmentally friendly solvent; The silane-modified aminophosphate chelating resin is prepared by reacting bisphenol F epoxy resin with diethylenetriamine in isopropanol and xylene solvent, then adding p-toluenesulfonic acid and diethyl phosphite, and finally adding KH540 to react with hydroquinone. The graphene oxide-Schiff base zirconium-siloxane hybrid filler is a nanoscale solid prepared by dispersing GO-SB and ZrO2-siloxane core-shell particles together in ethylene glycol methyl ether and isopropanol, and then reacting with a zirconium propoxide solution in ethylene glycol methyl ether. The nano-ZrO2-siloxane core-shell particles are prepared by dispersing nano-zirconia in anhydrous ethanol and deionized water, adjusting the pH to 4.5-5.0, adding a mixture of methyltrimethoxysilane, vinyltriethoxysilane, dilute hydrochloric acid (pH 3-4), and deionized water, and stirring. The GO-SB is prepared by dispersing multilayer graphene oxide in anhydrous ethanol, reacting with KH540 to obtain GO-NH2, then dispersing it in anhydrous ethanol, and reacting with salicylaldehyde and glacial acetic acid. The hyperbranched polyamide-siloxane bonding promoter is prepared by reacting ethylenediamine with methyl acrylate in anhydrous methanol and toluene, followed by vacuum evaporation to obtain a viscous liquid A. The viscous liquid A is dissolved in anhydrous methanol and reacted with ethylenediamine, followed by vacuum evaporation to obtain a viscous liquid B. The viscous liquid B is then reacted with KH540 in toluene and propylene glycol methyl ether acetate, followed by the addition of perfluoroalkyl phosphate and propylene glycol methyl ether acetate and stirring to obtain the final product.

2. The high-adhesion, anti-peeling primer for metal substrates according to claim 1, characterized in that, The functional additives include 5-8 parts of thixotropic anti-sagging agent, 6-9 parts of defoamer, 3-5 parts of ultraviolet absorption stabilizer, and 10-15 parts of rust and corrosion inhibitor synergist.

3. The high-adhesion, anti-peeling primer for metal substrates according to claim 1, characterized in that, The composite environmentally friendly solvent includes xylene, propylene glycol methyl ether acetate, isopropanol, and ethylene glycol butyl ether in a mass ratio of (3-4):(2-3):(2-2.5):(1-1.5).

4. The high-adhesion, anti-peeling primer for metal substrates according to claim 1, characterized in that, The silane-modified aminophosphate chelating resin is prepared by reacting bisphenol F epoxy resin, diethylenetriamine, p-toluenesulfonic acid, diethyl phosphite, KH540, and hydroquinone in a mass ratio of (300-350):(80-90):(8-10):(100-120):(90-100):(1-2). The bisphenol F epoxy resin is reacted with diethylenetriamine in isopropanol and xylene solvent at 70-78°C, then p-toluenesulfonic acid and diethyl phosphite are added and reacted at 90-95°C, and finally KH540 is added and reacted with hydroquinone at 70-75°C.

5. The high-adhesion, anti-peeling primer for metal substrates according to claim 4, characterized in that, The preparation method of the silane-modified aminophosphate chelating resin includes the following steps: 300-350 parts by mass of bisphenol F epoxy resin, 200-250 parts by mass of isopropanol, and 50-80 parts by mass of xylene are dissolved by stirring at 70-78°C; 80-90 parts by mass of diethylenetriamine are added dropwise; the mixture is stirred and reacted at 70-78°C for 3-4 hours; the temperature is lowered to 55-60°C; 8-10 parts by mass of p-toluenesulfonic acid and 100-120 parts by mass of diethyl phosphite are added; the mixture is refluxed at 90-95°C for 3.5-4.5 hours; the temperature is lowered to 50-55°C; 90-100 parts by mass of KH540 and 1-2 parts by mass of hydroquinone polymerization inhibitor are added; the mixture is reacted at 70-75°C for 2-3 hours; and the mixture is distilled under reduced pressure to obtain the silane-modified aminophosphate chelating resin.

6. The high-adhesion, anti-peeling primer for metal substrates according to claim 1, characterized in that, The graphene oxide-Schiff base zirconium-siloxane hybrid filler is prepared by dispersing GO-SB, nano-ZrO2-siloxane core-shell particles, and 80wt% zirconium propoxide in ethylene glycol methyl ether solution at a mass ratio of (10-20):(40-60):(15-20). GO-SB and ZrO2-siloxane core-shell particles are co-dispersed in ethylene glycol methyl ether and isopropanol, and then reacted with 80wt% zirconium propoxide in ethylene glycol methyl ether solution at 90-95℃ to obtain a nanoscale solid. The nano-ZrO2-siloxane core-shell particles are prepared by dispersing nano-zirconium dioxide, methyltrimethoxysilane, vinyltriethoxysilane, and pH 3-4 dilute hydrochloric acid at a mass ratio of (120-150):(80-90):(40-50). The solid was prepared by dispersing nano-zirconia in anhydrous ethanol and deionized water at a mass ratio of (0.5-0.6), adjusting the pH to 4.5-5.0, adding a mixture of methyltrimethoxysilane, vinyltriethoxysilane, dilute hydrochloric acid at pH 3-4, and deionized water, and stirring. The GO-SB was prepared by dispersing multilayer graphene oxide, KH540, salicylaldehyde, and glacial acetic acid at a mass ratio of (10-20):(20-30):(20-30):(1-1.5). Multilayer graphene oxide was dispersed in anhydrous ethanol, KH540 was added, and the mixture was reacted at 65-70℃ to obtain GO-NH2, which was then dispersed in anhydrous ethanol. Salicylaldehyde and glacial acetic acid were added, and the mixture was reacted at 65-70℃ to obtain the solid.

7. The high-adhesion, anti-peeling primer for metal substrates according to claim 6, characterized in that, The preparation method of the graphite oxide-Schiff base zirconium-siloxane hybrid filler includes the following steps: N1: By weight, 120-150 parts of nano-zirconia were added to 500-600 parts of anhydrous ethanol and 50-60 parts of deionized water, ultrasonically dispersed, and the pH was adjusted to 4.5-5.0 to obtain a suspension; 80-90 parts of methyltrimethoxysilane and 40-50 parts of vinyltriethoxysilane were mixed, and 1-2 parts of deionized water and 0.5-0.6 parts of dilute hydrochloric acid with pH 3-4 were added, followed by the suspension. The mixture was stirred at 55-60℃ for 6-8 hours, centrifuged, the precipitate was washed, and vacuum dried to obtain nano-ZrO2-siloxane core-shell particles; N2: By weight, 10-20 parts of multilayer graphene oxide were added to 200-250 parts of anhydrous ethanol, ultrasonically dispersed, and 20-30 parts of KH540 were added. The mixture was refluxed at 65-70℃ for 10-12 hours, filtered, and the solid was collected and vacuum dried to obtain GO-NH2. GO-NH2 was dispersed in 200-250 parts of anhydrous ethanol, and 20-30 parts of salicylaldehyde and 1-1.5 parts of glacial acetic acid catalyst were added. The mixture was refluxed at 65-70℃ for 5-6 hours to remove water, filtered, the solid was washed, and dried to obtain GO-SB. N3: By mass, 10-20 parts of GO-SB and 40-60 parts of nano ZrO2-siloxane core-shell particles are co-dispersed in 200-250 parts of ethylene glycol methyl ether and 50-60 parts of isopropanol. 15-20 parts of an 80% zirconium propoxide solution in ethylene glycol methyl ether are added dropwise. The mixture is refluxed at 90-95°C for 9-10 hours. After centrifugation, the solid is washed and vacuum dried to obtain nanoscale graphite oxide-Schiff base zirconium-siloxane hybrid filler.

8. The high-adhesion, anti-peeling primer for metal substrates according to claim 1, characterized in that, The hyperbranched polyamide-siloxane bonding promoter is ethylenediamine and methyl acrylate in a mass ratio of (80-100):(350-400). Ethylenediamine is reacted with methyl acrylate in anhydrous methanol and toluene at 25-30°C, and the mixture is evaporated under reduced pressure to obtain viscous liquid A. Then, viscous liquid A and ethylenediamine are reacted in anhydrous methanol in a mass ratio of (400-500):(80-100). Viscous liquid A is dissolved in anhydrous methanol and reacted with ethylenediamine at 40-45°C. The mixture is evaporated under reduced pressure to obtain viscous liquid B. Then, viscous liquid B, KH540, and perfluoroalkyl phosphate are reacted in anhydrous methanol in a mass ratio of (400-500):(90-100):(20-30). Viscous liquid B is reacted with KH540 in toluene and propylene glycol methyl ether acetate at 60-65°C. Perfluoroalkyl phosphate and propylene glycol methyl ether acetate are added at 40-45°C and stirred to obtain the final product.

9. A high-adhesion, anti-peeling primer for metal substrates according to claim 8, characterized in that, The preparation method of the hyperbranched polyamide-siloxane bonding accelerator includes the following steps: M1: Dissolve 80-100 parts by weight of ethylenediamine in 200-250 parts of anhydrous methanol and 50-60 parts of toluene, and add 350-400 parts of methyl acrylate dropwise at below 10°C; react in a sealed environment at 25-30°C for 20-24 hours; evaporate under reduced pressure to obtain viscous liquid A; M2: Dissolve 400-500 parts by weight of viscous liquid A in 200-300 parts by weight of anhydrous methanol, add 80-100 parts by weight of ethylenediamine, react in a sealed container at 40-45°C for 10-12 hours, and evaporate under reduced pressure to obtain viscous liquid B. M3: Dissolve 400-500 parts by weight of viscous liquid B in 150-200 parts of toluene and 50-60 parts of propylene glycol methyl ether acetate, add 90-100 parts of KH540, and react in a sealed container at 60-65°C for 6-7 hours. Cool to 40-45°C, add 20-30 parts of perfluoroalkyl phosphate and 40-60 parts of propylene glycol methyl ether acetate, stir for 12-14 hours, let stand, filter, and vacuum dry to obtain hyperbranched polyamide-siloxane bonding promoter.

10. The method for preparing a high-adhesion, anti-peeling primer for metal substrates according to claim 1, characterized in that, Includes the following steps: S1: According to the primer formula, add defoamer to the composite environmentally friendly solvent, stir, add silane-modified amino phosphate chelating resin and hyperbranched polyamide-siloxane bonding promoter, stir, add graphite oxide-Schiff base zirconium-siloxane hybrid filler, stir, grind to a fineness of less than 30μm, add thixotropic anti-sagging agent, ultraviolet absorption stabilizer and rust inhibitor synergist, stir evenly to obtain the base material; S2: Add isocyanate curing agent to base material, stir, let stand for aging, vacuum degas, filter, and obtain primer.

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