A novel rust-preventive protective coating and a method for producing the same

Abstract

The application relates to the technical field of water-based industrial coatings and metal surface corrosion and protection, and specifically discloses a novel rustproof protective coating and a manufacturing method thereof. The rustproof protective coating is mainly composed of tannic acid modified water-based polyester-polyamide interpenetrating network resin, tannic acid pre-modified magnesium-aluminum hydrotalcite-zirconium phosphate composite powder, phytic acid-organic molybdate composite passivator, imidazoline quaternary ammonium salt-organic phosphonate composite, ketone imine type composite latent curing agent and supporting additives and deionized water. The coating is prepared by respectively completing pre-preparation of the resin base material and surface modification of the filler, then pre-complexing and locking, filler liquid preparation, gradient crosslinking and paint preparation. The coating can be used for corrosion and protection of metal substrates of automobile parts and industrial mechanical equipment, can be naturally cured in a wide temperature range, has excellent substrate adhesion and long-term corrosion resistance, and solves the problems of poor interface compatibility of conventional water-based rustproof coating resins and fillers and poor long-term protection performance.

Description

Technical Field

[0001] This application relates to the field of water-based industrial coatings and metal surface anti-corrosion protection technology. More specifically, it relates to a novel anti-rust protective coating and its manufacturing method, which is particularly suitable for long-term anti-corrosion protection of metal substrates of automotive parts and industrial machinery. Background Technology

[0002] Metal corrosion is one of the main causes of failure in metal components in automotive parts, industrial machinery and equipment, steel structure engineering, and other fields. Anti-rust coatings are the most economical and widely used technical means to achieve long-term protection of metal substrates. With the continuous improvement of environmental protection requirements, water-based anti-rust coatings with low VOC emissions are gradually replacing traditional solvent-based coatings and have become the mainstream development direction in the field of metal protection. They are widely used in equipment manufacturing, automotive industry, infrastructure protection and other scenarios. At the same time, the industry has also put forward more stringent requirements for the long-term corrosion resistance, substrate adhesion and environmental adaptability of coatings.

[0003] Currently, most conventional water-based anti-rust coatings use a basic formulation system of general-purpose water-based resin matrix combined with inorganic barrier fillers and corrosion inhibitors. A common problem is insufficient interfacial compatibility between the resin matrix and the inorganic fillers. This makes it difficult to simultaneously achieve both the cross-linking density of the coating and adhesion to the metal substrate, easily leading to interfacial defects within the coating. This allows corrosive media to rapidly penetrate to the substrate surface, and the long-term corrosion resistance of the coating is insufficient to meet the long-term service requirements under complex working conditions. Existing modification schemes often use silane coupling agents to surface-modify the inorganic fillers, or only add trace amounts of natural phenolic substances such as tannic acid as corrosion inhibitors. These methods fail to optimize the overall coating structure at the root of the film-forming matrix and filler interface, making it difficult to achieve a breakthrough improvement in the coating's corrosion resistance. Summary of the Invention

[0004] To address the problems of insufficient interfacial compatibility between the resin matrix and inorganic filler in existing water-based anti-rust coatings, difficulty in simultaneously achieving coating crosslinking density and adhesion to the metal substrate, and insufficient long-term corrosion resistance, this application provides a novel anti-rust protective coating and its manufacturing method.

[0005] In a first aspect, this application provides a novel anti-rust protective coating, employing the following technical solution: A novel anti-rust protective coating, by weight, comprises the following components: 45-55 parts of tannic acid-modified waterborne polyester-polyamide interpenetrating network resin; 12-18 parts of tannic acid-premodified magnesium aluminum hydrotalcite-zirconium phosphate composite powder; 4-6 parts of phytic acid-organomolybdate composite passivating agent; 0.3-0.8 parts of sodium citrate-citric acid buffer system; 1.5-2.5 parts of imidazoline quaternary ammonium salt-organophosphonate composite; 2-3 parts of hydroxyl-terminated polydimethylsiloxane-castor oil composite; 1-2 parts of ketimine composite latent curing agent; 0.5-1.5 parts of bio-based rheology modifier; 2-4 parts of film-forming aid; and 15-25 parts of deionized water.

[0006] By adopting the above technical solution, tannic acid is used to simultaneously modify the film-forming resin and inorganic barrier filler. With the help of the polyphenolic hydroxyl structure of tannic acid, it participates in the construction of the resin interpenetrating network and the surface modification of the inorganic filler to form homologous bridging units. This optimizes the interfacial compatibility between the resin phase and the filler phase from the root, reduces interfacial defects and penetration channels inside the coating, and combines multi-dimensional corrosion-inhibiting functional components and a wide temperature range curing system to construct a dense, well-adhesive, and long-lasting protective coating system, achieving stable protection for metal substrates.

[0007] Preferably, the tannic acid-modified waterborne polyester-polyamide interpenetrating network resin is prepared by a heating crosslinking reaction of waterborne polyester resin, waterborne polyamide resin and tannic acid. The hydroxyl value of the waterborne polyester resin is 40-60 mg KOH / g, the amine value of the waterborne polyamide resin is 50-70 mg KOH / g, and the mass ratio of the waterborne polyester resin, waterborne polyamide resin and tannic acid is 28-32:18-22:4-6.

[0008] By adopting the above technical solution, waterborne resins with corresponding hydroxyl and amine values ​​are matched to provide sufficient active crosslinking sites for the film-forming matrix, ensuring that the crosslinking reaction with tannic acid can proceed stably. The polyphenolic hydroxyl groups of tannic acid can undergo crosslinking reactions with the hydroxyl and amino groups of the resin, embedding into the molecular chains of the interpenetrating network. The limited raw material mass ratio can precisely control the degree of crosslinking of the resin system, avoiding the problems of local over-crosslinking leading to coating brittleness or insufficient crosslinking leading to a decrease in coating density. After tannic acid is grafted onto the resin molecular chain, it can form a coordination anchoring effect with the surface of the metal substrate through the phenolic hydroxyl groups, further strengthening the interfacial bonding force between the coating and the substrate.

[0009] Preferably, in the tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder, the mass ratio of magnesium aluminum hydrotalcite to layered α-zirconium phosphate is 1.8-2.2:1, the magnesium-aluminum molar ratio of the magnesium aluminum hydrotalcite is 2.8-3.2:1, and the mesh size of the magnesium aluminum hydrotalcite is 500-800 mesh; in the phytic acid-organic molybdate composite passivating agent, the mass ratio of phytic acid aqueous solution to dinonylnaphthalenesulfonate molybdenum is 2.8-3.2:1, and the mass fraction of the phytic acid aqueous solution is 65%-75%.

[0010] By adopting the above technical solutions, the combination of two layered inorganic fillers can utilize the difference in sheet size to form a stacked physical barrier structure, extending the penetration path of corrosive media inside the coating. Tannic acid can be grafted onto the filler surface through complexation, introducing active sites that can bind to the resin matrix into the inorganic filler, adjusting the surface polarity of the filler to match the aqueous resin system, improving the dispersibility of the filler in the aqueous system, and preventing the filler from agglomerating and forming defect channels. The polyphosphate groups of phytic acid can form a stable chelated passivation film with metal ions, and organic molybdates can form a dense oxide passivation layer on the metal surface. The synergistic effect of the two can inhibit anodic corrosion reaction at the coating damage site and delay the spread of rust to the interior and periphery of the substrate.

[0011] Preferably, in the sodium citrate-citric acid buffer system, the mass ratio of sodium citrate to citric acid is 3.5-4.5:1; in the imidazoline quaternary ammonium salt-organophosphonate complex, the mass ratio of imidazoline quaternary ammonium salt to hydroxyethylidene diphosphonic acid is 1.8-2.2:1; in the hydroxyl-terminated polydimethylsiloxane-castor oil complex, the mass ratio of hydroxyl-terminated polydimethylsiloxane to castor oil is 0.8-1.2:1, and the hydroxyl value of the hydroxyl-terminated polydimethylsiloxane is 20-30 mg KOH / g.

[0012] By adopting the above technical solutions, the sodium citrate-citric acid buffer system can stably regulate the pH value of the coating system, precisely control the degree of dissociation of tannic acid phenolic hydroxyl groups, inhibit excessive cross-linking reaction of tannic acid during the storage stage, and ensure the stability of the coating during storage. The imidazoline quaternary ammonium salt can be directionally adsorbed in the cathode active area of ​​the metal substrate to inhibit the oxygen reduction reaction during the corrosion process. The hydroxyl-terminated polydimethylsiloxane can complex free metal ions in the system to avoid metal ions catalyzing the aging and degradation of the coating. The two work together to achieve full-process inhibition of the cathodic corrosion reaction. The active hydroxyl groups of the terminal hydroxyl polydimethylsiloxane can participate in the cross-linking reaction of the resin system, stably embedding the silicon-oxygen bond into the film-forming system and improving the surface hydrophobicity of the coating. The long flexible carbon chain of castor oil can be embedded in the resin cross-linking network to improve the impact resistance and flexibility of the coating. The two work together to solve the problem that conventional water-based coatings are difficult to balance in terms of hydrophobicity and flexibility.

[0013] Preferably, the ketimine-based latent curing agent is a compound of hexamethylenediamine ketimine capped with methyl ethyl ketone oxime and isophoronediamine ketimine capped with methyl isobutyl ketone; the bio-based rheology modifier is a compound of xanthan gum and guar gum in a mass ratio of 0.8-1.2:1; and the film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0014] By adopting the above technical solution, two ketimine complexes with different structures are combined to form a latent curing system. After coating, the system can undergo hydrolysis upon contact with ambient moisture, gradually releasing active amine groups. These groups then crosslink with the active hydrogen in the resin system. The linear hexamethylenediamine ketimine provides an early curing response, while the alicyclic isophorone diamine ketimine ensures the later crosslinking density, balancing the curing speed and film uniformity of the coating, and achieving stable curing in a wide temperature range. The bio-based rheology modifier, a combination of xanthan gum and guar gum, can adjust the thixotropic properties of the coating system, prevent filler sedimentation during storage, and adapt to the rheological requirements of different application methods such as spraying, brushing, and roller coating. 2,2,4-Trimethyl-1,3-pentanediol monoisobutyrate can effectively reduce the minimum film-forming temperature of the waterborne resin, ensuring that the coating can form a continuous and complete film even in low-temperature application environments, avoiding defects such as cracking and pinholes that occur during low-temperature film formation.

[0015] Secondly, this application provides a novel method for manufacturing an anti-rust protective coating, employing the following technical solution: A method for manufacturing a novel rust-preventive protective coating includes the following steps: S1. Base material preparation: Waterborne polyester resin and waterborne polyamide resin are added to a reaction vessel with nitrogen protection, heated and stirred until the system is uniform, tannic acid is added in batches, and the cross-linking reaction is completed by keeping warm and stirring. The material is then cooled and discharged to obtain tannic acid modified waterborne polyester-polyamide interpenetrating network resin base material. S2. Filler modification: Magnesium aluminum hydrotalcite and layered α-zirconium phosphate are mixed evenly to obtain composite powder raw material. The composite powder raw material is added to deionized water to prepare a suspension. After stirring and dispersing at room temperature, tannic acid is added. The mixture is heated and stirred to complete the surface modification of the layered filler. After filtration, washing and drying, tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder is obtained. S3. Pre-complexing and locking: Add the resin base material and part of the deionized water to the reactor according to the formula amount, stir and dilute at room temperature, add phytic acid-organic molybdate composite passivating agent and sodium citrate-citric acid buffer system, heat and stir to lock the pH value of the system, cool down and add hydroxyl-terminated polydimethylsiloxane-caster oil complex, and continue stirring to obtain pre-complexing resin base material. S4. Preparation of filler solution: Add the tannic acid premodified magnesium aluminum hydrotalcite-zirconium phosphate composite powder to the remaining deionized water according to the formula amount, and disperse at room temperature and high speed to obtain a uniform filler suspension. S5. Gradient crosslinking: The filler suspension is slowly and uniformly added to the pre-complexed resin matrix. During the addition process, the temperature is kept and the stirring is continued. After the addition is completed, the temperature is kept and the stirring is continued. The pH value of the system is adjusted to obtain the resin-filler dispersion. S6. Blending and preparing the paint: Cool the resin-filler dispersion to room temperature, add the imidazoline quaternary ammonium salt-organophosphonate complex, bio-based rheology modifier and film-forming aid, stir evenly, add the ketimine composite latent curing agent, stir at low speed to complete the mixing, and then filter through a sieve to obtain the new anti-rust protective coating product.

[0016] By adopting the above technical solution and a step-by-step preparation process, the resin matrix is ​​modified and the inorganic filler is surface-modified separately. Then, the functional components are pre-stabilized and dispersed in the resin matrix through a pre-complexation step. Finally, the orderly dispersion of the filler and the uniform cross-linking of the resin system are achieved through a gradient cross-linking process. The step-by-step feeding method can precisely control the reaction process at each stage, avoid the functional components being adsorbed and deactivated by the inorganic filler, and ensure that each component is uniformly dispersed in the system, forming a coating system with controllable structure and stable performance, thereby improving batch stability during the production process.

[0017] Preferably, in step S1, the tannic acid is added in 2-4 batches, with an interval of 8-12 minutes between each batch. The heating temperature is 75-85℃, and the reaction time is 1.5-2.5 hours with stirring. The entire reaction is carried out under a nitrogen protective atmosphere.

[0018] By adopting the above technical solution, the batch addition of tannic acid can avoid the problem of excessively high local tannic acid concentration in the system, which would lead to local rapid cross-linking and a sudden increase in system viscosity. The batch interval can ensure that the previous batch of tannic acid reacts fully with the resin, achieving uniform grafting of tannic acid in the resin system. The nitrogen protection atmosphere throughout the process can effectively inhibit the oxidation side reaction of phenolic hydroxyl groups of tannic acid during heating, preventing discoloration of the resin matrix. At the same time, it isolates moisture in the air from contact with active groups, ensuring the storage stability of the resin matrix. The limited heating temperature and holding time can precisely control the process of cross-linking reaction, ensuring the uniform formation of the interpenetrating network structure.

[0019] Preferably, in step S2, the solid content of the suspension is 15-20%, the amount of tannic acid added is 3-5% of the mass of the composite powder raw material, and the modification heating temperature is 40-45℃. In step S3, the heating temperature is 40-50℃, the pH lock value of the system is 5.5-6.0, and the cooling temperature is 35-45℃.

[0020] By adopting the above technical solutions, the solid content range of the suspension can ensure that the inorganic powder is fully dispersed in the aqueous phase, providing a uniform reaction environment for the surface modification of tannic acid and avoiding powder agglomeration that leads to uneven modification; the amount of tannic acid added can ensure the formation of a complete modified layer on the filler surface, while avoiding excessive tannic acid residue from affecting the storage stability of the coating system; the modification heating temperature can ensure that the complexation reaction between tannic acid and the hydroxyl groups on the filler surface is fully carried out; the heating temperature and pH lock value in the pre-complexation stage can ensure that the passivation component and the buffer system are uniformly dispersed in the resin matrix, forming a stable pre-complexed system and avoiding premature deactivation of functional components; the cooling temperature can ensure that the toughening hydrophobic component is stably dispersed in the system and avoid demulsification and stratification problems.

[0021] Preferably, in step S5, the dropping rate of the filler suspension is 8-12 mL / min, the system temperature is kept at 40-50℃ during the dropping process, and the pH of the system is adjusted to 7.0-7.5. After the pH adjustment is completed, the gradient locking of the degree of cross-linking of the system and the parallel directional arrangement of the layered filler are completed through the hydrogen bonding bridging effect of tannic acid.

[0022] By adopting the above technical solution, the uniform and slow dropping rate can control the dispersion process of the filler in the resin matrix. Combined with a constant insulation temperature, it avoids the agglomeration problem caused by the one-time addition of filler, and provides a uniform dispersion environment for the directional arrangement of filler. The limited pH adjustment range can further regulate the degree of dissociation of tannic acid phenolic hydroxyl groups, trigger the hydrogen bond bridging effect of tannic acid, guide the layered filler to be oriented parallel to the substrate direction during the crosslinking process, and realize the gradient crosslinking of the resin system, avoid local agglomeration of the system, and form a uniform, dense coating structure with excellent barrier properties.

[0023] Preferably, in step S6, the finished coating is applied to the surface of a rust-removed metal substrate by spraying, brushing, or roller coating, and then naturally cured in an environment of -10 to 55°C and relative humidity ≤90%, with the dry film thickness of a single coating controlled at 20-60 μm.

[0024] By adopting the above technical solutions, multiple coating methods can be adapted to the construction needs of metal components with different shapes and working conditions. The wide temperature range curing conditions can cover different on-site construction environments such as low temperature in winter and high temperature in summer, ensuring that the coating can be uniformly cross-linked and cured in complex environments. The limited dry film thickness range can balance the protective performance and construction efficiency of the coating, ensuring that a single coating can form a continuous and complete protective film layer, avoiding the decrease in construction efficiency caused by multiple coatings, and adapting to the on-site rapid construction needs of industrial equipment and automotive parts.

[0025] In summary, this application has the following beneficial effects: 1. This application uses tannic acid-modified waterborne polyester-polyamide interpenetrating network resin and magnesium aluminum hydrotalcite-zirconia phosphate composite powder to construct a stable interface between the resin phase and the filler phase through homologous bridging units, thereby improving the cross-linking density of the coating and the adhesion to the metal substrate. At the same time, it achieves the orderly arrangement of layered fillers, extends the penetration path of corrosive media, and significantly improves the long-term corrosion resistance and protection performance of the coating.

[0026] 2. In this application, a full-electrode blocking corrosion inhibition system constructed from phytic acid-organomolybdate and imidazoline quaternary ammonium salt-organophosphonate is preferred. Through the synergistic effect of anodic passivation and cathodic inhibition, the corrosion process is blocked from the entire electrochemical reaction process. Combined with the dense structure of the film-forming substrate, the corrosion resistance at the damaged part of the coating is improved.

[0027] 3. This application uses a compound curing agent consisting of methyl ethyl ketone oxime-terminated hexamethylenediamine ketone imine and methyl isobutyl ketone-terminated isophoronediamine ketone imine. Through a moisture-triggered hydrolytic crosslinking mechanism, the coating achieves uniform curing in a wide temperature range environment, solving the problem of incomplete curing at room temperature with conventional curing agents and improving the environmental adaptability of on-site construction.

[0028] 4. The preparation method of this application, through stepwise pre-complexation locking and gradient cross-linking molding process, combined with stepwise precise control of the pH value of the system, controls the gradual cross-linking reaction of tannic acid, avoids the problem of local over-cross-linking or filler agglomeration in the system, and effectively ensures the uniformity of the coating structure and the stability of production batches. Attached Figure Description

[0029] Figure 1 This is a flowchart of a novel rust-proof protective coating manufacturing method provided in this application. Detailed Implementation

[0030] The present application will be further described in detail below with reference to embodiments and comparative examples. Unless otherwise specified, the experimental methods used below are conventional methods. Unless otherwise specified, the materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art, which can be obtained by those skilled in the art through commercial channels or prepared according to literature methods.

[0031] Technical Concept: Metal corrosion is a core cause of failure in automotive parts and industrial machinery components. Water-based anti-rust coatings represent the mainstream development direction for metal protection. However, existing technologies generally suffer from insufficient interfacial compatibility between the resin matrix and inorganic fillers, making it difficult for the coating to simultaneously achieve cross-linking density and adhesion to the metal substrate. Consequently, its long-term corrosion resistance cannot meet the requirements of long-term service under complex operating conditions. The core reason for this problem lies in the significant difference in surface polarity between the resin and filler in conventional water-based anti-rust coatings, which easily leads to interfacial defects and corrosion penetration channels. Existing modification schemes only modify the filler with coupling agents, and the industry only uses tannic acid as a trace corrosion inhibitor, failing to explore its core role in interfacial bridging modification.

[0032] To address the aforementioned core issues, this solution adopts tannic acid homologous bridging modification as its core design concept. By simultaneously participating in resin crosslinking and filler surface modification, a stable bridging structure is formed between the resin and filler phases, fundamentally optimizing interfacial compatibility. A stepwise preparation process is employed, controlling the gradual crosslinking of tannic acid through pre-complexation locking and gradient crosslinking steps, guiding the directional arrangement of layered fillers, and extending the penetration path of corrosive media. Combined with a synergistic corrosion inhibition system and a wide-temperature-range curing system, the coating's substrate adhesion and long-term corrosion resistance are ultimately improved simultaneously.

[0033] Preparation Example 1: The preparation method of ketimine-based composite latent curing agent is as follows: 1 part by weight of hexamethylenediamine and 3 parts by weight of methyl ethyl ketone oxime are added to a sealed reactor equipped with a reflux condenser, a water separator, and a nitrogen protection device. Stirring is started, and nitrogen is introduced to replace the air in the reactor. The temperature is raised to 80°C at a rate of 2°C / min, and the reaction is maintained at this temperature with stirring for 4 hours. The byproduct water generated during the reaction is continuously separated through the water separator. After the reaction is completed, the temperature is raised to 90°C, and excess methyl ethyl ketone oxime in the system is removed by vacuum distillation. The temperature is then lowered to room temperature to obtain methyl ethyl ketone oxime-terminated hexamethylenediamine ketimine. Separately, 1 part by weight of isophorone diamine and 3.5 parts by weight of methyl isobutyl ketone are added to a reactor of the same specifications. Under nitrogen protection, the temperature is raised to 90°C at a rate of 2°C / min. The reaction was carried out at ℃ and stirred for 5 hours, with water continuously separated. After the reaction was completed, excess methyl isobutyl ketone was removed by vacuum distillation, and the mixture was cooled to room temperature to obtain methyl isobutyl ketone-terminated isophorone diamine ketimide. Subsequently, the methyl ethyl ketone oxime-terminated hexamethylene diamine ketimide and the methyl isobutyl ketone-terminated isophorone diamine ketimide obtained above were added to a stirred tank in an anhydrous environment at a mass ratio of 0.9:1. The mixture was stirred at 300 r / min for 15 min under nitrogen protection at room temperature until the system was completely mixed and homogeneous. A ketimide composite latent curing agent that can be hydrolyzed by water vapor at 15-25℃ to produce active amines and crosslink with the active hydrogen of the resin system was obtained. The finished product was stored in an anhydrous sealed container away from light.

[0034] The following are the main raw materials and reagents used in the preparation examples, embodiments, and comparative examples, and their sources and specifications are as follows; unless otherwise specified, all reagents are commercially available analytical grade or higher products: 1. Tannic acid was purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: T25393; 2. The water-based polyester resin was purchased from Wuhan Jushun Chemical Co., Ltd., item number: js2025010216; 3. The waterborne polyamide resin was purchased from Guangzhou Hanju Polymer Materials Co., Ltd., brand: Hanju Chemical; 4. Hydroxyethylidene diphosphonic acid was purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: S45434; 5. Hydroxyl-terminated polydimethylsiloxane was purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd., item number: PB42760; 6. Castor oil was purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: S24344; 7. Hexamethylenediamine was purchased from Shandong Xinheng Chemical Co., Ltd., CAS: 124-09-4; 8. Methyl ethyl ketone oxime was purchased from Wuhan Jiyesheng Chemical Co., Ltd., CAS: 96-29-7; 9. Isophorone diamine was purchased from Hubei Kewode Chemical Co., Ltd., CAS: 2855-13-2; 10. Methyl isobutyl ketone was purchased from Shandong Chaoyue Chemical Co., Ltd., CAS: 108-10-1; 11. Xanthan gum was purchased from Zhengzhou Rongyuan Chemical Products Co., Ltd., CAS: 11138-66-2; 12. Guar gum was purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: S30550; 13. 2,2,4-Trimethyl-1,3-pentanediol monoisobutyrate was purchased from Shanghai Yuanye Biotechnology Co., Ltd., product number: S45128.

[0035] Example 1: This example provides a novel anti-rust protective coating comprising the following components in parts by weight: 50 parts of tannic acid-modified waterborne polyester-polyamide interpenetrating network resin; 15 parts of tannic acid-premodified magnesium aluminum hydrotalcite-zirconium phosphate composite powder; 5 parts of phytic acid-organomolybdate composite passivating agent; 0.55 parts of sodium citrate-citric acid buffer system; 2 parts of imidazoline quaternary ammonium salt-organophosphonate composite; 2.5 parts of hydroxyl-terminated polydimethylsiloxane-castor oil composite; 1.5 parts of ketimine composite latent curing agent; 1 part of bio-based rheology modifier; 3 parts of film-forming aid; and 20 parts of deionized water.

[0036] Among them, the tannic acid modified waterborne polyester-polyamide interpenetrating network resin is prepared by waterborne polyester resin, waterborne polyamide resin and tannic acid through heating crosslinking reaction. The hydroxyl value of waterborne polyester resin is 50mgKOH / g, the amine value of waterborne polyamide resin is 60mgKOH / g, and the mass ratio of waterborne polyester resin, waterborne polyamide resin and tannic acid is 30:20:5. In the tannic acid-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder, the mass ratio of magnesium aluminum hydrotalcite to layered α-zirconium phosphate is 2:1, the magnesium-aluminum molar ratio of magnesium aluminum hydrotalcite is 3:1, and the mesh size of magnesium aluminum hydrotalcite is 650 mesh; in the phytic acid-organic molybdate composite passivator, the mass ratio of phytic acid aqueous solution to molybdenum dinonylnaphthalenesulfonate is 3:1, and the mass fraction of phytic acid aqueous solution is 70%. In the sodium citrate-citric acid buffer system, the mass ratio of sodium citrate to citric acid is 4:1; in the imidazoline quaternary ammonium salt-organophosphonate complex, the mass ratio of imidazoline quaternary ammonium salt to hydroxyethylidene diphosphonic acid is 2:1; in the hydroxyl-terminated polydimethylsiloxane-castor oil complex, the mass ratio of hydroxyl-terminated polydimethylsiloxane to castor oil is 1:1, and the hydroxyl value of hydroxyl-terminated polydimethylsiloxane is 25 mg KOH / g. The ketimine-based latent curing agent is a compound of hexamethylenediamine ketimine capped with methyl ethyl ketone oxime and isophorone diamine ketimine capped with methyl isobutyl ketone at a mass ratio of 0.9:1. The compound can be hydrolyzed by water vapor at 15-25℃ to produce active amines, which undergo crosslinking reactions with active hydrogen in the resin system. The preparation process is carried out according to the specific preparation example. The bio-based rheology modifier is a compound of xanthan gum and guar gum at a mass ratio of 1:1. The film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0037] The manufacturing method of the above-mentioned novel anti-rust protective coating includes the following steps: S1. Base Material Pre-preparation: Waterborne polyester resin and waterborne polyamide resin are added to a reaction vessel under nitrogen protection. The mixture is heated and stirred until homogeneous. Tannic acid is added in batches, and the crosslinking reaction is completed by maintaining the temperature and stirring. The mixture is then cooled and discharged to obtain a tannic acid-modified waterborne polyester-polyamide interpenetrating network resin base material. The heating and stirring process employed a uniform heating rate of 3℃ / min. Before heating, 99.9% pure nitrogen was introduced to replace the air in the reactor, and this process was repeated three times. Throughout the process, the nitrogen flow rate was maintained at 0.5L / min, and the reactor was kept under a slight positive pressure of 0.03MPa to prevent resin oxidation and discoloration. Tannic acid was added in three batches, with each batch spaced 10 minutes apart. The stirring speed was 400r / min, the heating temperature was 80℃, and the reaction time was 2 hours. The entire reaction was carried out under a nitrogen protective atmosphere. The cooling process employed a uniform cooling rate of 2℃ / min. During the cooling process, the stirring speed was reduced to 200r / min. Stirring was stopped and the material was discharged when the temperature reached 25℃.

[0038] S2. Filler modification: Magnesium aluminum hydrotalcite and layered α-zirconium phosphate were mixed evenly to obtain a composite powder raw material. The composite powder raw material was added to deionized water to prepare a suspension. After dispersion by stirring at room temperature, tannic acid was added, and the mixture was heated and stirred to complete the surface modification of the layered filler. After filtration, washing, and drying, tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder was obtained. The solid content of the suspension is 17.5%, the stirring speed at room temperature is 800 r / min, the stirring time is 10 min, the amount of tannic acid added is 4% of the mass of the composite powder raw material, the heating temperature is 42.5℃, the stirring speed at the holding temperature is 500 r / min, and the stirring time is 25 min. The mixing process involved using a high-speed mixer under ambient temperature and dry conditions at a speed of 3000 rpm for 5 minutes to ensure no agglomeration or stratification of the two powders. Filtration was performed using a 200-mesh polyester filter cloth under vacuum at a vacuum level of -0.08 MPa. Washing was conducted three times with room temperature deionized water, using twice the mass of the composite powder raw materials for each wash. Washing was stopped when the pH of the filtrate reached 6.5-7.5. Drying was performed using a vacuum low-temperature forced-air drying process at 40℃ and a vacuum level of -0.08 MPa. The powder was turned over every 2 hours during drying, and drying was stopped when the powder weight loss was ≤0.5%. After drying, the powder was ground and sieved through a 650-mesh sieve before being sealed and stored. S3. Pre-complexing and locking: Add the resin base material and half of the formula amount of deionized water to the reactor according to the formula amount, stir and dilute at room temperature, add phytic acid-organic molybdate composite passivating agent and sodium citrate-citric acid buffer system, heat and stir to lock the pH value of the system, cool down and add hydroxyl-terminated polydimethylsiloxane-caster oil complex, and continue stirring to obtain pre-complexing resin base material. The stirring speed for dilution at room temperature was 300 r / min for 5 min; the stirring speed for heating was 500 r / min for 15 min, and the pH of the system was locked at 5.75; the stirring speed for cooling was 300 r / min for 10 min after adding the hydroxyl-terminated polydimethylsiloxane-castor oil complex at 40℃. S4. Preparation of filler solution: Add the tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder to the remaining half of the formula amount of deionized water according to the formula amount, and disperse at room temperature and high speed to obtain a uniform filler suspension. The high-speed dispersion rotation speed was 800 r / min, and the dispersion time was 10 min. S5. Gradient crosslinking: The filler suspension is slowly and uniformly added to the pre-complexed resin matrix. During the addition process, the temperature is kept and the stirring is continued. After the addition is completed, the temperature is kept and the stirring is continued. The pH value of the system is adjusted to obtain the resin-filler dispersion. The dropping rate of the filler suspension was 10 mL / min, the system temperature was kept at 45℃ during the dropping process, the stirring speed was 600 r / min, the stirring time after the dropping was completed was 20 min, the pH of the system was adjusted to 7.25, and after the pH was adjusted, the system was stirred at 400 r / min for 5 min. The gradient locking of the cross-linking degree of the system and the parallel orientation of the layered filler were achieved through the hydrogen bonding bridging effect of tannic acid. S6. Blending and preparing the paint: Cool the resin-filler dispersion to room temperature, add imidazoline quaternary ammonium salt-organophosphonate complex, bio-based rheology modifier and film-forming aid, stir evenly, add ketimine composite latent curing agent, stir at low speed to complete the mixing, and after sieving and filtering, a new type of anti-rust protective coating is obtained. The stirring speed after adding the imidazoline quaternary ammonium salt-organophosphonate complex was 400 r / min, and the stirring time was 10 min; the stirring speed after adding the ketimine composite latent curing agent was 200 r / min, and the stirring time was 5 min; filtration was performed using a 200-mesh sieve, and the finished coating was stored in a sealed, light-proof manner; the finished coating was applied to the surface of a rust-removed metal substrate by spraying, brushing, or roller coating, and naturally cured at 22.5℃ and relative humidity ≤90%, with the dry film thickness of a single coating controlled at 40 μm.

[0039] Example 2: This example provides a novel anti-rust protective coating comprising the following raw materials in parts by weight: 45 parts of tannic acid modified waterborne polyester-polyamide interpenetrating network resin; 12 parts of tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder; 4 parts of phytic acid-organomolybdate composite passivating agent; 0.3 parts of sodium citrate-citric acid buffer system; 1.5 parts of imidazoline quaternary ammonium salt-organophosphonate composite; 2 parts of hydroxyl-terminated polydimethylsiloxane-castor oil composite; 1 part of ketimine composite latent curing agent; 0.5 parts of bio-based rheology modifier; 2 parts of film-forming aid; and 15 parts of deionized water.

[0040] Among them, the tannic acid modified waterborne polyester-polyamide interpenetrating network resin is prepared by waterborne polyester resin, waterborne polyamide resin and tannic acid through heating crosslinking reaction. The hydroxyl value of waterborne polyester resin is 40mgKOH / g, the amine value of waterborne polyamide resin is 50mgKOH / g, and the mass ratio of waterborne polyester resin, waterborne polyamide resin and tannic acid is 28:18:4. In the tannic acid-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder, the mass ratio of magnesium aluminum hydrotalcite to layered α-zirconium phosphate is 1.8:1, the magnesium-aluminum molar ratio of magnesium aluminum hydrotalcite is 2.8:1, and the mesh size of magnesium aluminum hydrotalcite is 500 mesh; in the phytic acid-organic molybdate composite passivator, the mass ratio of phytic acid aqueous solution to molybdenum dinonylnaphthalenesulfonate is 2.8:1, and the mass fraction of phytic acid aqueous solution is 65%. In the sodium citrate-citric acid buffer system, the mass ratio of sodium citrate to citric acid is 3.5:1; in the imidazoline quaternary ammonium salt-organophosphonate complex, the mass ratio of imidazoline quaternary ammonium salt to hydroxyethylidene diphosphonic acid is 1.8:1; in the hydroxyl-terminated polydimethylsiloxane-castor oil complex, the mass ratio of hydroxyl-terminated polydimethylsiloxane to castor oil is 0.8:1, and the hydroxyl value of hydroxyl-terminated polydimethylsiloxane is 20 mg KOH / g. The ketimine-based latent curing agent is a compound of hexamethylenediamine ketimine capped with methyl ethyl ketone oxime and isophorone diamine ketimine capped with methyl isobutyl ketone at a mass ratio of 0.8:1. The compound can be hydrolyzed by water vapor at 15-25℃ to produce active amines, which undergo cross-linking reactions with active hydrogen in the resin system. The preparation process is carried out according to the specific preparation example. The bio-based rheology modifier is a compound of xanthan gum and guar gum at a mass ratio of 0.8:1. The film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0041] The manufacturing method of the above-mentioned novel anti-rust protective coating includes the following steps: S1. Base Material Pre-preparation: Waterborne polyester resin and waterborne polyamide resin are added to a reaction vessel under nitrogen protection. The mixture is heated and stirred until homogeneous. Tannic acid is added in batches, and the crosslinking reaction is completed by maintaining the temperature and stirring. The mixture is then cooled and discharged to obtain a tannic acid-modified waterborne polyester-polyamide interpenetrating network resin base material. The heating and stirring process employed a uniform heating rate of 2℃ / min. Before heating, 99.9% pure nitrogen was introduced to replace the air in the reactor twice. Throughout the process, the nitrogen flow rate was maintained at 0.3L / min, and the reactor was kept under a slight positive pressure of 0.02MPa to prevent resin oxidation and discoloration. Tannic acid was added in two batches, with an 8-minute interval between each batch. The stirring speed was 300r / min, the heating temperature was 75℃, and the reaction time was 1.5h. The entire reaction was carried out under a nitrogen protective atmosphere. The cooling process employed a uniform cooling rate of 1.5℃ / min. During the cooling process, the stirring speed was reduced to 150r / min. Stirring was stopped and the material was discharged when the temperature reached 25℃.

[0042] S2. Filler modification: Magnesium aluminum hydrotalcite and layered α-zirconium phosphate were mixed evenly to obtain a composite powder raw material. The composite powder raw material was added to deionized water to prepare a suspension. After dispersion by stirring at room temperature, tannic acid was added, and the mixture was heated and stirred to complete the surface modification of the layered filler. After filtration, washing, and drying, tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder was obtained. The solid content of the suspension is 15%, the stirring speed at room temperature is 700 r / min, the stirring time is 8 min, the amount of tannic acid added is 3% of the mass of the composite powder raw material, the heating temperature is 40℃, the stirring speed at the holding temperature is 400 r / min, and the stirring time is 20 min. The mixing process involved using a high-speed mixer under ambient temperature and dry conditions at a speed of 2500 rpm for 3 minutes to ensure no agglomeration or stratification of the two powders. Filtration was performed using a 150-mesh polyester filter cloth under vacuum at a vacuum level of -0.07 MPa. Washing was done twice with room temperature deionized water, using 1.5 times the mass of the composite powder raw material for each wash, stopping when the pH of the filtrate reached 6.0-7.0. Drying was performed using a vacuum low-temperature forced-air drying process at 38℃ and a vacuum level of -0.07 MPa, with the material turned over every 3 hours during drying. Drying was stopped when the powder weight loss was ≤0.8%. After drying, the powder was ground and sieved through a 500-mesh sieve before being sealed and stored. S3. Pre-complexing and locking: Add the resin base material and half of the formula amount of deionized water to the reactor according to the formula amount, stir and dilute at room temperature, add phytic acid-organic molybdate composite passivating agent and sodium citrate-citric acid buffer system, heat and stir to lock the pH value of the system, cool down and add hydroxyl-terminated polydimethylsiloxane-caster oil complex, and continue stirring to obtain pre-complexing resin base material. The stirring speed for dilution at room temperature was 200 r / min, and the stirring time was 3 min; the heating temperature was 40℃, the stirring speed was 400 r / min, and the stirring time was 10 min, with the pH locked at 5.5; the cooling temperature was 35℃, and the stirring speed after adding the hydroxyl-terminated polydimethylsiloxane-castor oil complex was 200 r / min, and the stirring time was 8 min. S4. Preparation of filler solution: Add the tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder to the remaining half of the formula amount of deionized water according to the formula amount, and disperse at room temperature and high speed to obtain a uniform filler suspension. The high-speed dispersion rotation speed was 700 r / min, and the dispersion time was 8 min. S5. Gradient crosslinking: The filler suspension is slowly and uniformly added to the pre-complexed resin matrix. During the addition process, the temperature is kept and the stirring is continued. After the addition is completed, the temperature is kept and the stirring is continued. The pH value of the system is adjusted to obtain the resin-filler dispersion. The dropping rate of the filler suspension was 8 mL / min, the system temperature was kept at 40℃ during the dropping process, the stirring speed was 500 r / min, the stirring time after the dropping was completed was 15 min, the pH of the system was adjusted to 7.0, and after the pH was adjusted, the system was stirred at 300 r / min for 3 min. The gradient locking of the cross-linking degree of the system and the parallel orientation of the layered filler were achieved through the hydrogen bonding bridging effect of tannic acid. S6. Blending and preparing the paint: Cool the resin-filler dispersion to room temperature, add imidazoline quaternary ammonium salt-organophosphonate complex, bio-based rheology modifier and film-forming aid, stir evenly, add ketimine composite latent curing agent, stir at low speed to complete the mixing, and after sieving and filtering, a new type of anti-rust protective coating is obtained. The stirring speed after adding the imidazoline quaternary ammonium salt-organophosphonate complex was 300 r / min, and the stirring time was 8 min; the stirring speed after adding the ketimine composite latent curing agent was 150 r / min, and the stirring time was 3 min; filtration was performed using a 150-mesh sieve, and the finished coating was stored in a sealed, light-proof manner; the finished coating was applied to the surface of a rust-removed metal substrate by spraying, brushing, or roller coating, and naturally cured at -10℃ and relative humidity ≤90%, with the dry film thickness of a single coating controlled at 20 μm.

[0043] Example 3; This example provides a novel anti-rust protective coating comprising the following raw materials in parts by weight: 55 parts of tannic acid modified waterborne polyester-polyamide interpenetrating network resin; 18 parts of tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder; 6 parts of phytic acid-organomolybdate composite passivating agent; 0.8 parts of sodium citrate-citric acid buffer system; 2.5 parts of imidazoline quaternary ammonium salt-organophosphonate composite; 3 parts of hydroxyl-terminated polydimethylsiloxane-castor oil composite; 2 parts of ketimine composite latent curing agent; 1.5 parts of bio-based rheology modifier; 4 parts of film-forming aid; and 25 parts of deionized water.

[0044] Among them, the tannic acid modified waterborne polyester-polyamide interpenetrating network resin is prepared by waterborne polyester resin, waterborne polyamide resin and tannic acid through heating crosslinking reaction. The hydroxyl value of the waterborne polyester resin is 60mgKOH / g, the amine value of the waterborne polyamide resin is 70mgKOH / g, and the mass ratio of waterborne polyester resin, waterborne polyamide resin and tannic acid is 32:22:6. In the tannic acid-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder, the mass ratio of magnesium aluminum hydrotalcite to layered α-zirconium phosphate is 2.2:1, the magnesium-aluminum molar ratio of magnesium aluminum hydrotalcite is 3.2:1, and the mesh size of magnesium aluminum hydrotalcite is 800 mesh; in the phytic acid-organic molybdate composite passivator, the mass ratio of phytic acid aqueous solution to molybdenum dinonylnaphthalenesulfonate is 3.2:1, and the mass fraction of phytic acid aqueous solution is 75%. In the sodium citrate-citric acid buffer system, the mass ratio of sodium citrate to citric acid is 4.5:1; in the imidazoline quaternary ammonium salt-organophosphonate complex, the mass ratio of imidazoline quaternary ammonium salt to hydroxyethylidene diphosphonic acid is 2.2:1; in the hydroxyl-terminated polydimethylsiloxane-castor oil complex, the mass ratio of hydroxyl-terminated polydimethylsiloxane to castor oil is 1.2:1, and the hydroxyl value of hydroxyl-terminated polydimethylsiloxane is 30 mg KOH / g. The ketimine-based latent curing agent is a compound of hexamethylenediamine ketimine capped with methyl ethyl ketone oxime and isophorone diamine ketimine capped with methyl isobutyl ketone at a mass ratio of 1.0:1. The compound can be hydrolyzed by water vapor at 15-25℃ to produce active amines, which undergo crosslinking reactions with active hydrogen in the resin system. The preparation process is carried out according to the specific preparation example. The bio-based rheology modifier is a compound of xanthan gum and guar gum at a mass ratio of 1.2:1. The film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0045] The manufacturing method of the above-mentioned novel anti-rust protective coating includes the following steps: S1. Base Material Pre-preparation: Waterborne polyester resin and waterborne polyamide resin are added to a reaction vessel under nitrogen protection. The mixture is heated and stirred until homogeneous. Tannic acid is added in batches, and the crosslinking reaction is completed by maintaining the temperature and stirring. The mixture is then cooled and discharged to obtain a tannic acid-modified waterborne polyester-polyamide interpenetrating network resin base material. The heating and stirring process employed a uniform heating rate of 4℃ / min. Before heating, 99.99% pure nitrogen was introduced to replace the air in the reactor, repeating this process four times. Throughout the process, the nitrogen flow rate was maintained at 0.8L / min, and the reactor was kept under a slight positive pressure of 0.05MPa to prevent resin oxidation and discoloration. Tannic acid was added in four batches, with each batch spaced 12 minutes apart. The stirring speed was 500r / min, the heating temperature was 85℃, and the reaction time was 2.5h. The entire reaction was carried out under a nitrogen protective atmosphere. The cooling process employed a uniform cooling rate of 3℃ / min. During the cooling process, the stirring speed was reduced to 250r / min. Stirring was stopped and the material was discharged when the temperature reached 30℃.

[0046] S2. Filler modification: Magnesium aluminum hydrotalcite and layered α-zirconium phosphate were mixed evenly to obtain a composite powder raw material. The composite powder raw material was added to deionized water to prepare a suspension. After dispersion by stirring at room temperature, tannic acid was added, and the mixture was heated and stirred to complete the surface modification of the layered filler. After filtration, washing, and drying, tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder was obtained. The solid content of the suspension is 20%, the stirring speed at room temperature is 900 r / min, the stirring time is 12 min, the amount of tannic acid added is 5% of the mass of the composite powder raw material, the heating temperature is 45℃, the stirring speed at the heat preservation stirring speed is 600 r / min, and the stirring time is 30 min. The mixing process involved using a plow-type mixer under ambient temperature and dry conditions at a speed of 3500 rpm for 7 minutes to ensure no agglomeration or stratification of the two powders. Filtration was performed using a plate and frame filter press with a 250-mesh polypropylene filter cloth at a pressure of 0.3 MPa. Washing was conducted four times with room temperature deionized water, using 2.5 times the mass of the composite powder raw material for each wash, stopping when the pH of the filtrate reached 7.0-8.0. Drying was carried out using vacuum low-temperature static drying at 45℃ and a vacuum of -0.09 MPa, with the material turned over every 1.5 hours during the drying process. Drying was stopped when the powder weight loss was ≤0.3%. After drying, the powder was ground and sieved through an 800-mesh sieve before being sealed and stored. S3. Pre-complexing and locking: Add the resin base material and half of the formula amount of deionized water to the reactor according to the formula amount, stir and dilute at room temperature, add phytic acid-organic molybdate composite passivating agent and sodium citrate-citric acid buffer system, heat and stir to lock the pH value of the system, cool down and add hydroxyl-terminated polydimethylsiloxane-caster oil complex, and continue stirring to obtain pre-complexing resin base material. The stirring speed for dilution at room temperature was 400 r / min, and the stirring time was 7 min; the heating temperature was 50℃, the stirring speed was 600 r / min, and the stirring time was 20 min, with the pH locked at 6.0; the cooling temperature was 45℃, and the stirring speed after adding the hydroxyl-terminated polydimethylsiloxane-castor oil complex was 400 r / min, and the stirring time was 12 min. S4. Preparation of filler solution: Add the tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder to the remaining half of the formula amount of deionized water according to the formula amount, and disperse at room temperature and high speed to obtain a uniform filler suspension. The high-speed dispersion rotation speed was 900 r / min, and the dispersion time was 12 min. S5. Gradient crosslinking: The filler suspension is slowly and uniformly added to the pre-complexed resin matrix. During the addition process, the temperature is kept and the stirring is continued. After the addition is completed, the temperature is kept and the stirring is continued. The pH value of the system is adjusted to obtain the resin-filler dispersion. The dropping rate of the filler suspension was 12 mL / min, the system temperature was kept at 50℃ during the dropping process, the stirring speed was 700 r / min, the stirring time after the dropping was completed was 25 min, the pH of the system was adjusted to 7.5, and after the pH was adjusted, the system was stirred at 500 r / min for 7 min. The gradient locking of the cross-linking degree of the system and the parallel orientation of the layered filler were achieved through the hydrogen bonding bridging effect of tannic acid. S6. Blending and preparing the paint: Cool the resin-filler dispersion to room temperature, add imidazoline quaternary ammonium salt-organophosphonate complex, bio-based rheology modifier and film-forming aid, stir evenly, add ketimine composite latent curing agent, stir at low speed to complete the mixing, and after sieving and filtering, a new type of anti-rust protective coating is obtained. The stirring speed after adding the imidazoline quaternary ammonium salt-organophosphonate complex was 500 r / min, and the stirring time was 12 min; the stirring speed after adding the ketimine composite latent curing agent was 250 r / min, and the stirring time was 7 min; filtration was performed using a 250 mesh sieve, and the finished coating was stored in a sealed, light-proof manner; the finished coating was applied to the surface of a rust-removed metal substrate by spraying, brushing, or roller coating, and naturally cured at 55℃ and relative humidity ≤90%, with the dry film thickness of a single coating controlled at 60 μm.

[0047] Comparative Example 1: The only difference between this comparative example and Example 1 is that the tannic acid modified waterborne polyester-polyamide interpenetrating network resin is replaced with an equal mass of unmodified waterborne polyester-polyamide interpenetrating network resin, and the tannic acid premodified magnesium aluminum hydrotalcite-zirconia phosphate composite powder is replaced with an equal mass of unmodified magnesium aluminum hydrotalcite-zirconia phosphate composite powder. All other raw material types, weight parts and preparation steps are completely consistent with Example 1.

[0048] Comparative Example 2: The only difference between this comparative example and Example 1 is that tannic acid is added only as a trace corrosion inhibitor, with a dosage of 0.5 parts, which is the industry standard dosage. The resin system is replaced with an equal mass of unmodified waterborne polyester-polyamide interpenetrating network resin. The filler is unmodified magnesium aluminum hydrotalcite-zirconium phosphate composite powder. All other raw material total mass, preparation steps and process parameters are completely consistent with Example 1.

[0049] Comparative Example 3: The only difference between this comparative example and Example 1 is that in the S5 gradient crosslinking step, the filler suspension is slowly added to the pre-complexed resin matrix at a uniform rate of 10 mL / min, instead of the filler suspension being added to the pre-complexed resin matrix all at once. All other raw material types, weight parts and preparation steps are completely consistent with Example 1.

[0050] Comparative Example 4: The only difference between this comparative example and Example 1 is that the phytic acid-organomolybdate composite passivating agent and the imidazoline quaternary ammonium salt-organophosphonate complex were removed, and the system was made up with an equal total mass of deionized water. All other raw material types, weight parts and preparation steps were completely consistent with Example 1.

[0051] Comparative Example 5: The only difference between this comparative example and Example 1 is that the ketimine composite latent curing agent is replaced with an equal mass of conventional methyl ethyl ketone oxime blocked HDI trimer curing agent. All other raw material types, weight parts and preparation steps are completely consistent with Example 1.

[0052] Comparative Example 6: The only difference between this comparative example and Example 1 is that a commercially available conventional water-based acrylic anti-rust primer was used. Its main components are water-based acrylic emulsion, zinc phosphate anti-rust pigment, talc, organic bentonite, film-forming aid and water-based curing agent. All other test conditions, dry film thickness and curing environment are completely consistent with Example 1.

[0053] I. Neutral Salt Spray Corrosion Performance Test: The test standard is GB / T10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test". All coating samples from Examples 1 to 3 and Comparative Examples 1 to 6 were coated using air spraying onto the surface of Q235 low-carbon steel samples that had been sandblasted to Sa2.5 grade. The sample dimensions were 150mm × 70mm × 1mm, and the dry film thickness of a single coat was uniformly controlled at 40μm. After coating, the samples were allowed to cure naturally for 7 days at 22.5℃ and relative humidity ≤90%. After curing, a cross-scratch with a length of 80mm and a width of 0.5mm was made on the surface of the coating, penetrating the coating to the metal substrate. All samples were then placed parallel to each other in the salt spray test. Inside the test chamber, the test conditions were set as follows: sodium chloride solution concentration of 50 g / L, solution pH value controlled between 6.5 and 7.2, test chamber temperature constant at 35℃, continuous spraying cycle of 1500 h, sample surface condition observed every 240 h during the test, residual salt spray on the sample surface gently rinsed with deionized water after the test, and after cold air drying, the bubbling level of the sample coating was observed and recorded using a magnifying glass, where level 0 was no bubbling, level 1 was very slight bubbling, level 2 was slight bubbling, level 3 was moderate bubbling, level 4 was heavy bubbling, and level 5 was dense bubbling. The maximum rust expansion width at the scratched area and the rust area ratio of the non-scratched area were also recorded to comprehensively evaluate the salt spray corrosion resistance of each coating sample.

[0054] II. Cross-cut adhesion test and adhesion retention rate under corrosive conditions. The test standard is GB / T9286-2021 "Cross-cut test for paints and varnishes". All coating samples of Examples 1 to 3 and Comparative Examples 1 to 6 were divided into two groups for testing. The first group was the initial adhesion test group. The sample preparation method was the same as that used in the neutral salt spray test. The substrate was a 150mm×70mm×1mm Q235 low carbon steel plate. The dry film thickness was uniformly controlled at 40μm. After natural curing for 7 days at 22.5℃ and relative humidity ≤90%, a 6×6 grid pattern was cut on the coating surface using a cross-cut tester with a grid spacing of 1mm. The cutting depth penetrates the coating to the metal substrate. Then, a soft brush is used to gently sweep back and forth 5 times along the diagonal of the grid. Pressure-sensitive tape that meets the standard requirements is applied and then smoothly removed. The initial adhesion level is determined based on the degree of peeling off the coating grid edge, and the level is divided into 0 to 5, with level 0 being the best. The second group is the adhesion retention rate test group after corrosion. Samples from the same batch that have completed 1500h of neutral salt spray test are used. After rinsing and drying, the adhesion level after corrosion is tested using the same cross-cut test method. At the same time, the adhesion retention rate of each coating sample is calculated based on the initial adhesion level to evaluate the interfacial bonding stability of the coating in the corrosive environment.

[0055] III. Impact Resistance and Pencil Hardness Testing of Coatings After Wide Temperature Range Curing: The testing standards are GB / T1732-2020 "Determination of Impact Resistance of Paint Films" and GB / T6739-2006 "Determination of Hardness of Paint Films by Pencil Method". To meet the wide temperature range environmental requirements of on-site construction in automotive and industrial machinery, all coating samples from Examples 1 to 3 and Comparative Examples 1 to 6 were coated and cured at three typical construction temperature environments: -10℃, 22.5℃, and 55℃. The samples used were 120mm×50mm×1mm tinplate, and the dry film thickness was uniformly controlled at 40μm. After curing naturally for 7 days at the corresponding temperature, performance tests were conducted. The impact resistance test used a 1kg hammer, which was dropped freely from different heights onto the sample coating. The highest impact height from which the coating did not crack or peel off was taken as the test result, and the unit was cm. The pencil hardness test used a high-grade Chinese drawing pencil with a known hardness rating, which was pushed at a 45-degree angle and moved at a constant speed across the coating surface. The highest pencil hardness rating from which the coating did not show any scratches was taken as the test result. By combining the impact resistance performance and pencil hardness data at different curing temperatures, the wide temperature range application adaptability and mechanical stability after curing of each coating sample were comprehensively evaluated.

[0056] IV. Coating resistance to damp heat aging test: The test standard is GB / T1740-2007 "Determination of Damp Heat Resistance of Coating Film". All coating samples of Examples 1 to 3 and Comparative Examples 1 to 6 were coated on the surface of 120mm×50mm×0.8mm tinplate by air spraying. The dry film thickness was uniformly controlled at 40μm. After natural curing for 7 days in an environment of 22.5℃ and relative humidity ≤90%, they were suspended in a temperature and humidity control test chamber. The test conditions were set as follows: constant temperature of 47℃±1℃ and constant relative humidity of 96%±2%. The continuous test cycle was 1000h. During the test, the coating condition of the sample was observed every 200h. After the test, the sample was taken out and the defects of the coating such as blistering, rusting, loss of gloss, and cracking were observed and recorded. The damp heat aging resistance of each coating sample was graded according to the grade evaluation method specified in the standard. The grade was divided into 0 to 5, with grade 0 being the best. The adhesion and hardness change rate were also tested at the same time.

[0057] Table 1: Results of Neutral Salt Spray Corrosion Performance Test Table 2: Test results of cross-cut adhesion and adhesion retention rate of coatings under corrosive conditions Table 3: Results of Impact Resistance and Pencil Hardness Tests for Coatings After Wide Temperature Range Curing Table 4: Test Results of Coating Resistance to Damp Heat Aging As can be seen from Examples 1-3 and Comparative Example 1, and Tables 1-4, tannic acid can be used simultaneously for resin crosslinking modification and filler surface modification to form a stable bridging network between the resin phase and the filler phase, effectively improving the crosslinking density, interfacial bonding force and long-term service stability of the coating, which is the core foundation for ensuring the comprehensive protective performance of the coating.

[0058] As can be seen from Examples 1-3 and Comparative Example 2, and Tables 1-4, the systematic application of tannic acid as the core bridging functional unit can simultaneously improve coating performance from multiple dimensions, including film-forming substrate, filler interface, and substrate anchoring, compared to the industry's conventional use of trace corrosion inhibitors, thus breaking through the performance bottleneck of conventional application modes.

[0059] As can be seen from Examples 1-3 and Comparative Example 3, and Tables 1-4, the gradient crosslinking process of uniformly and slowly adding the filler suspension can work with the tannic acid in the system to achieve the orderly arrangement of the layered filler, effectively extend the penetration path of the corrosive medium, and at the same time ensure the uniformity of the coating crosslinking structure, which has a significant impact on the long-term protective performance and mechanical stability of the coating.

[0060] Based on Examples 1-3 and Comparative Example 4, and in conjunction with Tables 1, 2, and 4, it can be seen that the all-electrode blocking corrosion inhibition system, which combines anodic passivation with cathodic inhibition, can form a synergistic protective effect with the film-forming substrate, blocking the corrosion process from the entire electrochemical reaction of corrosion, and significantly improving the corrosion resistance of the coating and the interface stability in corrosive environments.

[0061] As can be seen from Examples 1-3 and Comparative Example 5, and Tables 1-4, the ketimine composite latent curing agent can achieve uniform cross-linking and curing of the coating in a wide temperature range, solving the problem of incomplete curing at room temperature of conventional closed isocyanate curing agents. This is the key to ensuring that the coating can achieve stable performance under different construction environments.

[0062] As can be seen from Examples 1-3 and Comparative Example 6, and Tables 1-4, the systematic design of this application has significantly improved corrosion resistance, interfacial adhesion, wide temperature range application adaptability and long-term aging stability compared with commercially available conventional water-based anti-rust coatings, and can better adapt to the complex service environment requirements of automobiles and industrial machinery.

[0063] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A novel anti-rust protective coating, characterized in that: By weight, it consists of the following components: 45-55 parts of tannic acid modified waterborne polyester-polyamide interpenetrating network resin; 12-18 parts of tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder; 4-6 parts of phytic acid-organomolybdate composite passivating agent; 0.3-0.8 parts of sodium citrate-citric acid buffer system; 1.5-2.5 parts of imidazoline quaternary ammonium salt-organophosphonate composite; 2-3 parts of hydroxyl-terminated polydimethylsiloxane-castor oil composite; 1-2 parts of ketimine composite latent curing agent; 0.5-1.5 parts of bio-based rheology modifier; 2-4 parts of film-forming aid; and 15-25 parts of deionized water.

2. The novel anti-rust protective coating according to claim 1, characterized in that: The tannic acid-modified waterborne polyester-polyamide interpenetrating network resin is prepared by a heating crosslinking reaction of waterborne polyester resin, waterborne polyamide resin and tannic acid. The hydroxyl value of the waterborne polyester resin is 40-60 mg KOH / g, the amine value of the waterborne polyamide resin is 50-70 mg KOH / g, and the mass ratio of the waterborne polyester resin, waterborne polyamide resin and tannic acid is 28-32:18-22:4-6.

3. The novel anti-rust protective coating according to claim 1, characterized in that: In the tannic acid pre-modified magnesium aluminum hydrotalcite-zirconia phosphate composite powder, the mass ratio of magnesium aluminum hydrotalcite to layered α-zirconia phosphate is 1.8-2.2:1, the magnesium-aluminum molar ratio of the magnesium aluminum hydrotalcite is 2.8-3.2:1, and the mesh size of the magnesium aluminum hydrotalcite is 500-800 mesh; in the phytic acid-organic molybdate composite passivating agent, the mass ratio of phytic acid aqueous solution to dinonylnaphthalenesulfonate molybdenum is 2.8-3.2:1, and the mass fraction of the phytic acid aqueous solution is 65%-75%.

4. The novel anti-rust protective coating according to claim 1, characterized in that: In the sodium citrate-citric acid buffer system, the mass ratio of sodium citrate to citric acid is 3.5-4.5:1; in the imidazoline quaternary ammonium salt-organophosphonate complex, the mass ratio of imidazoline quaternary ammonium salt to hydroxyethylidene diphosphonic acid is 1.8-2.2:1; in the hydroxyl-terminated polydimethylsiloxane-castor oil complex, the mass ratio of hydroxyl-terminated polydimethylsiloxane to castor oil is 0.8-1.2:1, and the hydroxyl value of the hydroxyl-terminated polydimethylsiloxane is 20-30 mg KOH / g.

5. The novel anti-rust protective coating according to claim 1, characterized in that: The ketimine-based latent curing agent is a compound of hexamethylenediamine ketimine capped with methyl ethyl ketone oxime and isophoronediamine ketimine capped with methyl isobutyl ketone; the bio-based rheology modifier is a compound of xanthan gum and guar gum in a mass ratio of 0.8-1.2:1; the film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

6. A method for manufacturing a novel anti-rust protective coating, characterized in that, A novel rust-preventive protective coating according to any one of claims 1-5 comprises the following steps: S1. Base material preparation: Waterborne polyester resin and waterborne polyamide resin are added to a reaction vessel with nitrogen protection, heated and stirred until the system is uniform, tannic acid is added in batches, and the cross-linking reaction is completed by keeping warm and stirring. The material is then cooled and discharged to obtain tannic acid modified waterborne polyester-polyamide interpenetrating network resin base material. S2. Filler modification: Magnesium aluminum hydrotalcite and layered α-zirconium phosphate are mixed evenly to obtain composite powder raw material. The composite powder raw material is added to deionized water to prepare a suspension. After stirring and dispersing at room temperature, tannic acid is added. The mixture is heated and stirred to complete the surface modification of the layered filler. After filtration, washing and drying, tannic acid pre-modified magnesium aluminum hydrotalcite-zirconium phosphate composite powder is obtained. S3. Pre-complexing and locking: Add the resin base material and part of the deionized water to the reactor according to the formula amount, stir and dilute at room temperature, add phytic acid-organic molybdate composite passivating agent and sodium citrate-citric acid buffer system, heat and stir to lock the pH value of the system, cool down and add hydroxyl-terminated polydimethylsiloxane-caster oil complex, and continue stirring to obtain pre-complexing resin base material. S4. Preparation of filler solution: Add the tannic acid premodified magnesium aluminum hydrotalcite-zirconium phosphate composite powder to the remaining deionized water according to the formula amount, and disperse at room temperature and high speed to obtain a uniform filler suspension. S5. Gradient crosslinking: The filler suspension is slowly and uniformly added to the pre-complexed resin matrix. During the addition process, the temperature is kept and the stirring is continued. After the addition is completed, the temperature is kept and the stirring is continued. The pH value of the system is adjusted to obtain the resin-filler dispersion. S6. Blending and preparing the paint: Cool the resin-filler dispersion to room temperature, add the imidazoline quaternary ammonium salt-organophosphonate complex, bio-based rheology modifier and film-forming aid, stir evenly, add the ketimine composite latent curing agent, stir at low speed to complete the mixing, and then filter through a sieve to obtain the new anti-rust protective coating product.

7. The method for manufacturing a novel anti-rust protective coating according to claim 6, characterized in that: In step S1, the tannic acid is added in 2-4 batches, with an interval of 8-12 minutes between each batch. The temperature is raised to 75-85℃, and the reaction time is 1.5-2.5 hours with stirring. The entire reaction is carried out under a nitrogen protective atmosphere.

8. The method for manufacturing a novel anti-rust protective coating according to claim 6, characterized in that: In step S2, the solid content of the suspension is 15-20%, the amount of tannic acid added is 3-5% of the mass of the composite powder raw material, and the modification heating temperature is 40-45℃. In step S3, the heating temperature is 40-50℃, the pH lock value of the system is 5.5-6.0, and the cooling temperature is 35-45℃.

9. The method for manufacturing a novel anti-rust protective coating according to claim 6, characterized in that: In step S5, the dropping rate of the filler suspension is 8-12 mL / min, the system temperature is kept at 40-50℃ during the dropping process, and the pH of the system is adjusted to 7.0-7.

5. After the pH adjustment is completed, the gradient locking of the degree of cross-linking of the system and the parallel orientation of the layered filler are completed through the hydrogen bond bridging effect of tannic acid.

10. The method for manufacturing a novel anti-rust protective coating according to claim 6, characterized in that: In step S6, the obtained coating product is applied to the surface of the rust-removed metal substrate by spraying, brushing or roller coating, and naturally cured in an environment of -10 to 55°C and relative humidity ≤90%. The thickness of the dry film of a single coating is controlled at 20-60μm.

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