A cooling coating compound type anti-flash rust agent and a preparation method thereof

Abstract

This invention relates to the field of coating composition technology, specifically disclosing a cooling coating compound anti-flash rust agent and its preparation method. By synthesizing a novel organic corrosion inhibitor and compounding it with an inorganic corrosion inhibitor and corrosion inhibitor additives, a flash rust prevention system with a significant synergistic effect is formed. The anti-flash rust agent consists of an organic corrosion inhibitor, an inorganic corrosion inhibitor, and corrosion inhibitor additives, and is compatible with conventional water-based coatings while effectively inhibiting the electrochemical corrosion of metal substrates during coating application. Its preparation method is simple, using an ethanol solution as a medium, reacting under suitable temperature and stirring conditions to generate the target organic corrosion inhibitor, which is then compounded with inorganic salts and organic additives to obtain a clear solution. The anti-flash rust agent of this invention exhibits a corrosion inhibition efficiency of over 94% on carbon steel substrates, significantly reducing flash rust and enhancing the corrosion resistance and long-term stability of water-based epoxy coatings. This anti-flash rust agent is environmentally friendly, has excellent performance, and is suitable for water-based cooling coating protection of power equipment such as transformers and switchgear.

Description

Technical Field

[0001] This invention belongs to the field of coating composition technology, and particularly relates to the field of cooling coating rust prevention technology, specifically a cooling coating compound anti-flash rust agent and its preparation method. Background Technology

[0002] Power equipment is a core component of the safe and stable operation of power systems, including various types such as transformers, switchgear, high-voltage switches, and terminal boxes. With the continuous growth of social electricity demand, the load on the power grid continues to rise. According to statistics, the total electricity consumption of the whole society reached 9.85 trillion kilowatt-hours in 2024. The pressure on the power grid is particularly prominent under extreme environments such as high temperatures and strong sunlight in summer. Against this backdrop, the operating temperature of power equipment continues to rise, which not only leads to a decrease in operating efficiency but also accelerates the aging of insulation components and metal parts, and may even cause local overheating, failures, or even fires, posing a significant threat to the safety of power grid operation. Therefore, how to effectively manage the thermal properties of power equipment has become an important issue that the industry urgently needs to address.

[0003] In recent years, with the development of materials science and surface engineering technology, a type of cooling coating with high infrared emissivity and / or high solar reflectivity has been gradually applied to the surface of power equipment. These coatings can achieve temperature control by enhancing radiative heat dissipation or reducing light absorption, and have advantages such as simple construction, low cost, no alteration to the original equipment structure, and wide applicability. Furthermore, compared with traditional solvent-based coatings, water-based coatings, due to their low volatile organic compound (VOC) emissions and outstanding environmental performance, are gradually replacing solvent-based products and are being increasingly widely used in protective and heat dissipation coatings for power equipment. However, a prominent problem commonly found in the application of water-based coatings is flash rust. Flash rust refers to the phenomenon where, during coating application and curing, because water-based coatings use water as a dispersion medium, water evaporation is slow during film formation. The metal substrate surface is exposed to the combined effects of oxygen and moisture for a prolonged period, forming tiny corrosion cells and producing corrosion products, manifesting as black or brown rust spots on the coating surface. Flash rust not only seriously affects the appearance quality of the coating but also reduces its shielding and protective capabilities, leading to a decrease in cooling effect and ultimately shortening the service life of power equipment.

[0004] To address the problem of flash rust, existing technologies have proposed various solutions, including substrate surface pretreatment, humidity control in the coating environment, use of anti-rust primers, and adding anti-flame rust agents to the formulation. Among these, directly adding anti-flame rust agents to water-based coatings is widely used due to its simple process and flexible application. Anti-flame rust agents can form a protective layer on the surface of metal substrates, inhibiting electrochemical corrosion and thus effectively delaying the occurrence of flash rust. However, existing anti-flame rust agents still have significant shortcomings: on the one hand, conventional varieties are prone to failure in high humidity or highly corrosive environments, making it difficult to meet the stringent conditions for long-term service of power equipment; on the other hand, some varieties with good rust prevention effects, such as nitrites, have been strictly restricted or even banned due to their strong toxicity and environmental hazards.

[0005] Furthermore, existing research has shown that single-type corrosion inhibitors often have limited protective effects, while the combination of different corrosion inhibitors can produce a synergistic effect, exhibiting a "1+1>2" effect. Under certain proportions, different corrosion inhibitors can form a denser and more stable protective film on the metal surface, thereby improving overall corrosion resistance while reducing the dosage of individual components, thus improving economic efficiency and environmental friendliness. Therefore, developing an environmentally friendly compound flash rust inhibitor that maintains excellent rust-inhibiting performance under high humidity and ensures good compatibility with water-based cooling coatings is an urgent need to solve the flash rust problem in current power equipment coating applications. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of flash rust easily occurring in water-based cooling coatings in power equipment applications, insufficient protective performance of existing single flash rust inhibitors, and environmental toxicity of some varieties, and to provide a compound flash rust inhibitor that combines high-efficiency anti-corrosion performance with environmentally friendly characteristics.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A cooling coating compound anti-flash rust agent, comprising:

[0009] Organic corrosion inhibitor, selected from one or more combinations of N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propamide, N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide, N-(4-methylthiazol-3-yl)-3-(1-en-propoxy)propamide, N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(2-methacryloyloxy)propamide, and N-(4-methylthiazol-3-yl)-3-(2-methacryloyloxy)propamide;

[0010] Inorganic corrosion inhibitors are selected from one or two of sodium molybdate, sodium tungstate, sodium polyphosphate, and cerium ammonium nitrate;

[0011] The corrosion inhibitor is selected from one or two of hydroxypropyl cellulose, succinic acid, 5-sulfosalicylic acid, and tea polyphenols.

[0012] Preferably, the organic corrosion inhibitor comprises N-[1-carboxyl-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propamide.

[0013] Preferably, the organic corrosion inhibitor comprises a combination of N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propamide and N-(4-methylthiazolyl)-3-(2-methacryloyloxy)propamide, wherein the mass ratio of the two is 1:1.

[0014] Preferably, the organic corrosion inhibitor comprises a combination of N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide and N-(4-methylthiazolyl)-3-(1-en-propoxy)propamide in a mass ratio of 2:1.

[0015] Preferably, the organic corrosion inhibitor comprises a combination of N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(2-methacryloyloxy)propamide, N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide, and N-(4-methylthiazolyl)-3-(2-methacryloyloxy)propamide, wherein the mass ratio of the three is 3:3:4.

[0016] Preferably, the organic corrosion inhibitor comprises a combination of N-(4-methylthiazol-3-yl)-3-(1-en-propoxy)propamide and N-[1-carboxyl-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propamide, wherein the mass ratio of the two is 1:2.

[0017] Preferably, the organic corrosion inhibitor comprises N-(4-methylthiazolyl-3-yl)-3-(2-methacryloyloxy)propionamide.

[0018] Preferably, the inorganic corrosion inhibitor comprises a combination of sodium tungstate and cerium ammonium nitrate.

[0019] Preferably, the corrosion inhibitors include hydroxypropyl cellulose and tea polyphenols.

[0020] Preferably, the corrosion inhibitor comprises a combination of 5-sulfosalicylic acid and sodium polyphosphate.

[0021] Preferably, the flash rust inhibitor is composed of the following components in the following mass ratios: 10-20 parts organic corrosion inhibitor, 5-15 parts inorganic corrosion inhibitor, 3-6 parts corrosion inhibitor, and the remainder is an ethanol solution.

[0022] Preferably, the amount of anti-flash rust agent added to the water-based coating is 0.6 wt% of the coating mass.

[0023] Based on the same inventive concept, the present invention also provides a method for preparing a cooling coating compound anti-flash rust agent, the method comprising the following steps:

[0024] Reactant I and reactant II in an ethanol solution to generate the organic corrosion inhibitor described above. Reactant I is selected from 5-hydroxytryptophan, (1,2,4-oxadiazol-3-yl)methylamine and 2-amino-4-methylthiazole, and reactant II is selected from allyl glycidyl ether and glycidyl methacrylate.

[0025] The obtained organic corrosion inhibitor is mixed and dissolved with the inorganic corrosion inhibitor and corrosion inhibitor auxiliaries to obtain the compound anti-flash rust agent.

[0026] Preferably, the reaction temperature of reactant I and reactant II is 75–95°C, and the reaction time is 3–6 h.

[0027] Preferably, the concentration of the ethanol solution is 30 wt%, and the resulting compound liquid is clear and transparent.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The cooling coating compound anti-flash rust agent provided by this invention has outstanding innovation and rationality in both composition and preparation method. Firstly, the selected organic corrosion inhibitors are derived from nitrogen-containing, hydroxyl-containing, or heterocyclic structural units such as 5-hydroxytryptophan, oxadiazoles, and thiazoles. These molecules can form coordination adsorption with the metal substrate surface through heterocyclic nitrogen atoms, carboxyl groups, or hydroxyl groups in an electrochemical corrosion environment, thereby generating a dense organic adsorption film on the surface of substrates such as carbon steel. This film can effectively prevent further penetration of moisture and oxygen, blocking the formation of corrosion galvanic cells. Compared with traditional small-molecule amine or alcohol corrosion inhibitors, these novel organic corrosion inhibitors simultaneously introduce polar groups and unsaturated bonds into their molecular skeleton, which not only enhances the binding force with the metal surface but also allows the molecules to align oriented on the substrate surface, improving the stability and density of the adsorption film, thus significantly improving corrosion inhibition performance.

[0030] Secondly, this invention introduces inorganic corrosion inhibitors such as sodium molybdate, sodium tungstate, sodium polyphosphate, or cerium ammonium nitrate into the organic corrosion inhibitor base. These inorganic salts can undergo anodic passivation during the electrochemical reaction on the metal surface, forming insoluble metal oxide or polyphosphate films. For example, molybdate or tungstate ions can react with iron ions to form stable molybdate or tungstate deposits, covering the micro-corrosion area and effectively slowing down the anodic dissolution rate; cerium salts can preferentially deposit at defects, playing a "self-repairing" role. Because these inorganic corrosion inhibitors themselves have good redox buffering properties, when combined with organic corrosion inhibitors, they can achieve a dual protection mechanism of organic adsorption film and inorganic passivation film. That is, organic molecules construct the first barrier through chemical adsorption, while inorganic components further fill defects and micropores through deposition passivation. The two complement each other, significantly improving the overall corrosion inhibition effect.

[0031] Furthermore, the introduction of corrosion inhibitors such as hydroxypropyl cellulose, 5-sulfosalicylic acid, or tea polyphenols further enhances the stability of the film. These additive molecules not only improve the dispersibility and film uniformity of the corrosion inhibitor in aqueous systems, but also form hydrogen bonds or coordination interactions with organic corrosion inhibitors or inorganic components, thereby enhancing the continuity and mechanical strength of the film. For example, hydroxypropyl cellulose, as a high-molecular-weight thickener, can form a flexible network structure on the substrate surface, improving the durability of the paint film; tea polyphenols contain multiple phenolic hydroxyl groups, which can capture free radicals through redox reactions, delaying the chain process of corrosion reactions. Thus, this invention establishes a triple corrosion inhibition mechanism of organic adsorption, inorganic passivation, and additive synergy in the system, achieving comprehensive protective performance that is difficult to achieve with a single corrosion inhibitor.

[0032] Based on the above mechanism, the cooling coating compound anti-flash rust agent of the present invention exhibits significant beneficial effects in practical applications. In the weight loss method experiment on carbon steel substrates, after adding the anti-flash rust agent of the present invention, the weight loss of the test pieces was significantly reduced, and the corrosion inhibition efficiency was generally higher than 94.5%, indicating that the corrosion rate was effectively suppressed. Electrochemical impedance spectroscopy and potentiodynamic polarization curves further show that in the system with the anti-flash rust agent added, the low-frequency impedance modulus was significantly improved, and the corrosion current density was reduced by more than one order of magnitude, verifying the compactness and electrochemical stability of the film. Microscopic morphology observation results show that the carbon steel surface was covered with pitting corrosion and corrosion products when no agent was added, while the surface of the test piece remained smooth after adding the anti-flash rust agent of the present invention, and even grinding marks were still visible, which directly proves the excellent protective effect of the synergistic film. The results of the paint film flash rust test and salt spray test also show that the coating maintains good appearance and protective performance under high humidity and salt spray environments, which is significantly better than the system without the compound anti-flash rust agent.

[0033] In summary, this invention establishes a comprehensive protective principle of adsorption-passivation-additive synergy through the scientific compounding of a novel organic corrosion inhibitor with a specific structure, inorganic corrosion inhibitors, and additives. This fundamentally inhibits flash rust problems in water-based cooling coatings during film formation. This mechanism not only extends the service life of the coating but also improves the long-term stability of power equipment in high-temperature and high-humidity environments, balancing environmental friendliness and ease of application. It solves the problem of insufficient performance and environmental risks inherent in existing technologies. Adding the flash rust inhibitor of this invention to water-based cooling coatings can address the issues of flash rust susceptibility in water-based cooling coatings for power equipment, insufficient protective performance of existing flash rust inhibitors, and the environmental toxicity of some varieties. Attached Figure Description

[0034] Figure 1 Examples of the present invention and Comparative Example 1 Electrochemical impedance Nyquist plot of Q235 carbon steel in hydrochloric acid solution;

[0035] Figure 2 Examples of the present invention and Comparative Example 1 Bode plot of electrochemical impedance spectroscopy for Q235 carbon steel in hydrochloric acid solution;

[0036] Figure 3 Examples of the present invention and Comparative Example 1 Potentiodynamic polarization curve of Q235 carbon steel in hydrochloric acid solution;

[0037] Figure 4 For Q235 carbon steel sheets, with or without the anti-flash rust agent described in different embodiments, 1 Optical photographs of corrosion morphology in hydrochloric acid solution;

[0038] Figure 5 The figures show the test results of the effects of the embodiments and comparative examples of the present invention on flash rust of waterborne epoxy resin coatings.

[0039] Figure 6 Images of waterborne epoxy resin coated carbon steel specimens after a 120-hour salt spray test, representing embodiments and comparative examples of the present invention.

[0040] Figure 7 Images of waterborne epoxy resin coated carbon steel specimens after a 240-hour salt spray test, representing embodiments and comparative examples of the present invention.

[0041] Where μm is the unit of length, micrometer; other notes are provided in the examples. Detailed Implementation

[0042] The technical solution will be further described below with reference to the accompanying drawings and specific embodiments to help understand the content of the present invention.

[0043] On the one hand, currently used conventional flash rust inhibitors have poor performance and are prone to failure in high humidity environments. On the other hand, flash rust inhibitors with good rust prevention effects contain sodium nitrite, which is highly toxic and does not meet environmental protection requirements, thus its use is restricted. This invention aims to first synthesize a highly efficient organic corrosion inhibitor, and then, based on this, to compound the synthesized corrosion inhibitor to develop a highly efficient and environmentally friendly water-based cooling coating flash rust inhibitor for power equipment. This flash rust inhibitor has good compatibility with conventional water-based coatings, enhancing both the flash rust prevention performance of conventional water-based coatings and improving their long-term protective capabilities.

[0044] The compound anti-flash rust agent of the present invention is used for cooling coatings, and mainly includes organic corrosion inhibitors, inorganic corrosion inhibitors and corrosion inhibitors.

[0045] The organic corrosion inhibitor is one of N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propamide, N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide, N-(4-methylthiazol-3-yl)-3-(1-en-propoxy)propamide, N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(2-methacryloyloxy)propamide, and N-(4-methylthiazol-3-yl)-3-(2-methacryloyloxy)propamide.

[0046] The inorganic corrosion inhibitor is one or two of sodium molybdate, sodium tungstate, sodium polyphosphate, and cerium ammonium nitrate;

[0047] The corrosion inhibitor is one or two of hydroxypropyl cellulose, succinic acid, 5-sulfosalicylic acid, and tea polyphenols.

[0048] The organic corrosion inhibitor is synthesized as follows: 150 mL of 60 wt% ethanol solution is first added to a three-necked flask equipped with a reflux condenser. Then, 0.1 mol of reactant I and 0.12–0.15 mol of reactant II are added to the three-necked flask in sequence. The mixture is heated to reflux at 75–95 °C and magnetically stirred at 300–600 rpm for 3–6 h. The reaction solution is then concentrated to 50 mL by vacuum distillation. The reaction solution is then placed in a refrigerator to cool and crystallize. After filtration, the solution is washed three times with anhydrous ethanol and dried under vacuum at 60 °C to obtain the organic corrosion inhibitor.

[0049] Reactant I is one of 5-hydroxytryptophan, (1,2,4-oxadiazol-3-yl)methylamine, and 2-amino-4-methylthiazole.

[0050] Reactant II is one of allyl glycidyl ether and glycidyl methacrylate.

[0051] The synthetic reaction equation for N-[1-carboxy-(5-hydroxyindol-3-yl)-propyl]-3-(1-en-propoxy)propionamide is as follows:

[0052]

[0053] The synthetic reaction equation for N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propionamide is as follows:

[0054]

[0055] The synthetic reaction equation for N-(4-methylthiazolyl)-3-(1-en-propoxy)propionamide is as follows:

[0056]

[0057] The synthetic reaction equation for N-[1-carboxy-(5-hydroxyindol-3-yl)-propyl]-3-(2-methacryloyloxy)propionamide is as follows:

[0058]

[0059] The synthetic reaction equation for N-(4-methylthiazolyl-3-yl)-3-(2-methacryloyloxy)propionamide is as follows:

[0060]

[0061] The preparation method of the compound corrosion inhibitor is as follows:

[0062] Add 10–20 g of organic corrosion inhibitor, 5.0–15.0 g of inorganic corrosion inhibitor, and 3.0–6.0 g of corrosion inhibitor to 60–80 mL of 30 wt% ethanol solution in sequence, and stir magnetically until completely dissolved to obtain a clear and transparent solution.

[0063] Example 1:

[0064] First, 150 mL of 60 wt% ethanol solution was added to a three-necked flask equipped with a reflux condenser. Then, 0.1 mol of 5-hydroxytryptophan and 0.12 mol of allyl glycidyl ether were added to the flask sequentially. The mixture was heated to reflux at 85 °C and magnetically stirred at 400 rpm for 4 h. The reaction solution was then concentrated to 50 mL by vacuum distillation. The reaction solution was then placed in a refrigerator to cool and crystallize. After filtration, the solution was washed three times with anhydrous ethanol and dried under vacuum at 60 °C to obtain the organic corrosion inhibitor N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propionamide.

[0065] The synthetic reaction equation for N-[1-carboxy-(5-hydroxyindol-3-yl)-propyl]-3-(1-en-propoxy)propionamide is as follows:

[0066]

[0067] Then, add 10.0g of N-[1-carboxy-(5-hydroxyindol-3-yl)-propyl]-3-(1-en-propoxy)propamide, 8.0g of sodium molybdate, and 4.0g of tea polyphenols to 70mL of 30wt% ethanol solution in sequence, and stir magnetically until completely dissolved to obtain a transparent and clear anti-flash rust solution.

[0068] Example 2:

[0069] First, add 150 mL of 60 wt% ethanol solution to a three-necked flask equipped with a reflux condenser. Then, add 0.1 mol (1,2,4-oxadiazol-3-yl)methylamine and 0.15 mol allyl glycidyl ether to the three-necked flask in sequence. Heat under reflux at 90 °C and stir magnetically at 300 rpm for 5 h. Then, concentrate the reaction solution to 50 mL by vacuum distillation. Place the reaction solution in a refrigerator to cool and crystallize. Filter, wash three times with anhydrous ethanol, and dry under vacuum at 60 °C to obtain the organic corrosion inhibitor N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide.

[0070] The synthetic reaction equation for N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propionamide is as follows:

[0071]

[0072] Then, add 15.0g N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide, 5.0g sodium tungstate, 2.0g hydroxypropyl cellulose and 1.0g succinic acid to 60mL of 30wt% ethanol solution in sequence, and stir magnetically until completely dissolved to obtain a transparent and clear anti-flash rust solution.

[0073] Example 3:

[0074] First, add 150 mL of 60 wt% ethanol solution to a three-necked flask equipped with a reflux condenser. Then, add 0.1 mol of 2-amino-4-methylthiazole and 0.13 mol of allyl glycidyl ether to the three-necked flask in sequence. Heat under reflux at 80 °C and stir magnetically at 500 rpm for 3 h. Then, concentrate the reaction solution to 50 mL by vacuum distillation. Place the reaction solution in a refrigerator to cool and crystallize. Filter, wash three times with anhydrous ethanol, and dry under vacuum at 60 °C to obtain the organic corrosion inhibitor N-(4-methylthiazole-3-yl)-3-(1-en-propoxy)propamide.

[0075] The synthetic reaction equation for N-(4-methylthiazolyl)-3-(1-en-propoxy)propionamide is as follows:

[0076]

[0077] Then, add 15.0g N-(4-methylthiazolyl-3-yl)-3-(1-en-propoxy)propamide, 8.0g sodium molybdate, 2.0g sodium polyphosphate and 6.0g 5-sulfosalicylic acid sequentially to 80mL of 30wt% ethanol solution, and stir magnetically until completely dissolved to obtain a transparent and clear flash rust inhibitor solution.

[0078] Example 4:

[0079] First, add 150 mL of 60 wt% ethanol solution to a three-necked flask equipped with a reflux condenser. Then, add 0.1 mol 5-hydroxytryptophan and 0.14 mol glycidyl methacrylate to the three-necked flask in sequence. Heat under reflux at 75 °C and stir magnetically at 600 rpm for 6 h. Then, concentrate the reaction solution to 50 mL by vacuum distillation. Place the reaction solution in a refrigerator to cool and crystallize. Filter, wash three times with anhydrous ethanol, and dry under vacuum at 60 °C to obtain the organic corrosion inhibitor N-[1-carboxyl-(5-hydroxyindol-3-yl)-propyl]-3-(2-methacryloyloxy)propionamide.

[0080] The synthetic reaction equation for N-[1-carboxy-(5-hydroxyindol-3-yl)-propyl]-3-(2-methacryloyloxy)propionamide is as follows:

[0081]

[0082] Then, add 12.0g N-[1-carboxy-(5-hydroxyindol-3-yl)-propyl]-3-(2-methacryloyloxy)propionamide, 10.0g sodium tungstate, 5.0g cerium ammonium nitrate, 3.0g hydroxypropyl cellulose and 2.0g tea polyphenols sequentially to 70mL of 30wt% ethanol solution, and stir magnetically until completely dissolved to obtain a transparent and clear anti-flash rust solution.

[0083] Example 5:

[0084] First, add 150 mL of 60 wt% ethanol solution to a three-necked flask equipped with a reflux condenser. Then, add 0.1 mol of 2-amino-4-methylthiazole and 0.12 mol of glycidyl methacrylate to the three-necked flask in sequence. Heat under reflux at 85 °C and stir magnetically at 400 rpm for 5 h. Then, concentrate the reaction solution to 50 mL by vacuum distillation. Place the reaction solution in a refrigerator to cool and crystallize. Filter, wash three times with anhydrous ethanol, and dry under vacuum at 60 °C to obtain the organic corrosion inhibitor N-(4-methylthiazole-3-yl)-3-(2-methacryloyloxy)propionamide.

[0085] The synthetic reaction equation for N-(4-methylthiazolyl-3-yl)-3-(2-methacryloyloxy)propionamide is as follows:

[0086]

[0087] Then, add 15.0 g of N-(4-methylthiazolyl)-3-(2-methyl) to 80 mL of 30 wt% ethanol solution.

[0088] A transparent and clear anti-flash rust solution can be obtained by magnetically stirring 8.0g of acryloxypropylamide, 8.0g of sodium polyphosphate, and 6.0g of hydroxypropyl cellulose until completely dissolved.

[0089] The verification process for the technical effect of this invention is as follows:

[0090] (1) Weightlessness test

[0091] The static weight loss experiment was conducted according to the following steps: 100 mL of 1.0... Hydrochloric acid solution was used as the corrosive medium. The compound anti-flash rust agent prepared in different embodiments was added to the corrosive medium to obtain the test solution. The concentration of the anti-flash rust agent was 0.6 wt%. Q235 carbon steel test pieces with specifications of 5cm×4cm×0.1cm were first carefully polished with metallographic sandpaper of 400, 800, 1000 and 1500 grit in sequence. Then, they were ultrasonically cleaned with anhydrous ethanol for 5 min for degreasing, rinsed with deionized water, dried with cold air and accurately weighed and recorded. The carbon steel test pieces that had undergone the above pretreatment were suspended and immersed in different test solutions. After 12h and 24h, they were taken out, the corrosion products on their surface were removed, rinsed with deionized water and dried with cold air and accurately weighed. Three parallel test pieces were made for each group. The average weight loss value was calculated and the corrosion inhibition efficiency (η) was calculated according to formula (1).

[0092] (1)

[0093] In the formula, and These represent the average weight loss of carbon steel specimens before and after the addition of anti-flash rust agent.

[0094] (2) Electrochemical testing

[0095] Electrochemical impedance spectroscopy and potentiodynamic polarization curves were performed using a three-electrode system on an electrochemical workstation. The test solution was the aforementioned 1.0% solution with added compound anti-flashover agent. Hydrochloric acid solution. The working electrode is a cylindrical carbon steel sheet with a diameter of 1.13 cm and a height of 1 cm. Except for the working surface, the rest is encapsulated with epoxy resin. Before testing, the working surface is polished to a mirror finish with metallographic sandpaper, ultrasonically degreased with anhydrous ethanol, rinsed with deionized water, and dried with cold air. The reference electrode and auxiliary electrode are a calomel electrode equipped with a Luggin capillary salt bridge and a 2.0 cm × 2.0 cm platinum sheet, respectively. During testing, the working electrode is immersed in the test solution to first determine the open circuit potential E. OCP After scanning and waiting for the open-circuit potential to stabilize, electrochemical impedance spectroscopy and potentiodynamic polarization curve tests were performed sequentially. The sinusoidal scan frequency range for electrochemical impedance spectroscopy was 10 Hz. 5 ~10 -2 The frequency was Hz, and the amplitude was 5mV. The scan rate of the potentiodynamic polarization curve was 0.5 Hz. The scanning range is E OCP ±250mV.

[0096] (3) Analysis of the surface morphology of carbon steel

[0097] Carbon steel test pieces were subjected to treatments with and without 0.6 wt% of a compound anti-flash rust agent at a concentration of 1.0 g / L. The carbon steel specimen was immersed in hydrochloric acid solution for 24 hours, and the corrosion morphology on the surface was observed using an optical microscope.

[0098] (4) Test for resistance to flash rust of paint film

[0099] The flash rust resistance test of the paint film was conducted using the drop plate method. A water-based epoxy resin emulsion was taken, a curing agent was added, and then the anti-flash rust agent described in different embodiments was slowly added drop by drop. The amount added was controlled at 0.6 wt%. After stirring and dispersing evenly, an epoxy resin varnish was prepared. The epoxy resin varnish was dropped onto the surface of a carbon steel test piece for flash rust resistance test. Then, the carbon steel test piece was placed in a closed environment, using a closed space made of saturated ammonium sulfate aqueous solution to control the humidity at 95%, and left for 24 hours to observe the degree of rust.

[0100] (5) Salt spray resistance test of paint film

[0101] 0.6 wt% of anti-flash rust agent was added to the water-based epoxy resin coating solution. Epoxy resin coatings were prepared on the surface of carbon steel test pieces that had been polished, cleaned, and degreased using this epoxy resin. The salt spray resistance of the coating film was tested according to GB / T1771-2007 standard. Before the test, the steel plate to be tested was sealed at the edges. The corrosion degree of the carbon steel test piece was observed and recorded every 12 hours. The performance of the anti-flash rust agent was evaluated based on the corrosion degree of the carbon steel test piece.

[0102] Table 1. Q235 carbon steel sheets in 1% solution containing 0.6% flash rust inhibitor Weight loss test data in hydrochloric acid solution

[0103]

[0104] As shown in Table 1, the flash rust inhibitors described in Examples 1-5 are at 1.0 The anti-flash rust agent exhibits good corrosion inhibition properties in hydrochloric acid solutions, with an inhibition efficiency of over 94.5%, indicating that the anti-flash rust agent described in this invention can effectively suppress the flash rust problem of the substrate during the application of water-based cooling coatings.

[0105] 1 without or with the anti-flash rust agent described in different embodiments Electrochemical impedance spectroscopy (Nyquist plot) of Q235 carbon steel in hydrochloric acid solution (e.g.) Figure 1 (as shown) and Bode diagram (as shown) Figure 2 (As shown). The effectiveness of corrosion inhibitors can usually be qualitatively characterized by the size of the arc on the Nyquist plot. The larger the arc on the Nyquist plot, the denser the film formed by the corrosion inhibitor on the sample surface, and the better the protective effect. Figure 1 The addition of the anti-flash rust agent significantly improved the corrosion resistance of carbon steel. The low-frequency (0.01 Hz) impedance modulus in the Bode plot allows for quantitative comparison of the protective performance of the sample film. In hydrochloric acid solution without the anti-flash rust agent, the electrochemical low-frequency impedance modulus |Z| of the carbon steel was only 1.30. However, after adding the anti-flash rust agent described in Examples 1-5, the electrochemical impedance modulus |Z| increased to 12.0, 11.5, 10.8, 11.7, and 12.1, respectively. This indicates that the addition of the anti-flash rust agent described in this invention can effectively inhibit the corrosion of Q235 substrate.

[0106] exist Figure 1 In the Nyquist electrochemical impedance spectroscopy (EIS) plot, / and / These are two core parameters that describe the impedance characteristics of an electrode system; (Real part of impedance) characterizes the resistance properties, the pure opposition of the system to current. (Imaginary part of impedance) characterizes the reactance characteristics, the energy storage characteristics of a system (such as capacitors and inductors), causing the current phase to lag or lead. It is a unit of measurement called "ohm-square centimeter". Figure 2 In the Bode plot of electrochemical impedance spectroscopy (EIS), the vertical axis Z / This represents the impedance magnitude normalized to the electrode area, in units of... "Ohm-square centimeter" reflects the impedance of the electrode / electrolyte system to AC signals. The horizontal axis log(Freq) Hz represents the logarithm of the frequency (in Hz), and logarithmic coordinates are usually used to show the impedance variation across different frequency bands.

[0107] like Figure 3 As shown, in 1 without or with the addition of the anti-flash rust agent described in different embodiments Potentiodynamic polarization curves of Q235 carbon steel in hydrochloric acid solution. Corrosion current density value i of carbon steel in hydrochloric acid solution without added flash rust inhibitor. c 4.68×10 -4 However, after adding the anti-flash rust agent described in Examples 1-5, the electrochemical corrosion current density value... Reduced to 2.46×10 -5 1.60×10 -5 2.05×10 -5 1.50×10 -5 and 2.37×10 -5 According to the formula The corrosion inhibition efficiency η of the corrosion inhibitors described in Examples 1-5 was calculated. The corrosion inhibition efficiency η of the anti-flash rust agents described in Examples 1-5 can reach 94.7%, 96.6%, 95.6%, 96.8% and 94.9% respectively, indicating that the addition of the anti-flash rust agents described in this invention can effectively inhibit the corrosion of the substrate in hydrochloric acid solution.

[0108] exist Figure 3 In the potentiodynamic polarization curve diagram, the vertical axis lgi c / The current density, normalized to the effective electrode area, reflects the magnitude of the electrode reaction rate at different potentials and is an important parameter for studying corrosion rates and the kinetics of anodic or cathodic processes. The horizontal axis, E / V (vs. SCE), represents the electrode potential measured with a saturated calomel electrode (SCE) as a reference electrode, in volts, indicating the energy state of the electrode under an applied electric field. In other words, the horizontal axis describes the change in electrode potential, and the vertical axis reflects the response to the corresponding current density; the relationship between the two outlines the electrochemical behavior of the system during polarization.

[0109] like Figure 4 The figure shows 1 with or without the anti-flash rust agent described in different embodiments. Optical images showing the corrosion morphology of Q235 carbon steel specimens in hydrochloric acid solution, where (a) is a blank specimen; (b) a specimen with the anti-flash rust agent described in Example 1 added; (c) a specimen with the anti-flash rust agent described in Example 2 added; (d) a specimen with the anti-flash rust agent described in Example 3 added; (e) a specimen with the anti-flash rust agent described in Example 4 added; (f) a specimen with the anti-flash rust agent described in Example 5 added; and (g) a specimen without the anti-flash rust agent added. Observation and comparison show that the carbon steel in the hydrochloric acid solution without the anti-flash rust agent is severely corroded, with an uneven surface, large corrosion holes, and a large amount of corrosion products still distributed. However, after adding the anti-flash rust agents described in Examples 1-5, although the surface of the carbon steel specimen shows slight corrosion and corrosion products, its surface remains smooth, and grinding marks can still be observed, further demonstrating that the anti-flash rust agent described in this invention can effectively inhibit the corrosion of the carbon steel substrate.

[0110] like Figure 5 The figures shown are test results of the effects of the anti-flash rust agents described in different embodiments on flash rust of water-based epoxy resin coatings. (a) shows no anti-flash rust agent added; (b) shows the anti-flash rust agent described in Example 1 added; (c) shows the anti-flash rust agent described in Example 2 added; (d) shows the anti-flash rust agent described in Example 3 added; (e) shows the anti-flash rust agent described in Example 4 added; and (f) shows the anti-flash rust agent described in Example 5 added. Observation and comparison show that the epoxy resin coating without anti-flash rust agent showed multiple rust spots at the interface with the carbon steel substrate, indicating severe flash rust. After adding the anti-flash rust agents described in Examples 1-5, no rust or only a very small number of rust spots appeared on the surface of the carbon steel substrate. The influence of the water-based paint on the substrate was suppressed, indicating that the anti-flash rust agents described in Examples 1-5 have a good anti-flash rust effect on the carbon steel substrate.

[0111] like Figure 6 The images shown are photographs of water-based epoxy resin coatings with and without the anti-flash rust agent described in this invention after a 120-hour salt spray resistance test. Figure 7The images shown are photographs of water-based epoxy resin coatings after a 240-hour salt spray test with and without the anti-flash rust agent described in this invention. (a) No anti-flash rust agent added; (b) Anti-flash rust agent added as described in Example 1; (c) Anti-flash rust agent added as described in Example 2; (d) Anti-flash rust agent added as described in Example 3; (e) Anti-flash rust agent added as described in Example 4; (f) Anti-flash rust agent added as described in Example 5. Observation and comparison show that the water-based epoxy resin coating without the anti-flash rust agent exhibited severe corrosion on the surface and scratches after the salt spray test. However, the corrosion was significantly reduced after adding 0.6 wt% of the anti-flash rust agent, with only a small amount of corrosion visible at the scratches. This indicates that the anti-flash rust agent described in this invention has a good anti-flash rust effect. This may be because the anti-flash rust agent of this invention forms a dense protective film on the carbon steel substrate surface, preventing corrosive media from penetrating to the steel plate surface and inhibiting corrosion, thereby achieving excellent anti-corrosion effects.

[0112] Example 6:

[0113] 0.1 mol of (1,2,4-oxadiazol-3-yl)methylamine was reacted with 0.13 mol of glycidyl methacrylate to prepare the organic corrosion inhibitor N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(2-methacryloyloxy)propionamide; then 10 g of this organic corrosion inhibitor was compounded and dissolved with 10 g of sodium molybdate and 4 g of hydroxypropyl cellulose to obtain a clear and transparent solution. Other necessary technical details not mentioned above are provided in the foregoing examples.

[0114] Example 7:

[0115] 0.1 mol of 2-amino-4-methylthiazole was reacted with 0.14 mol of glycidyl methacrylate to prepare the organic corrosion inhibitor N-(4-methylthiazole-3-yl)-3-(2-methacryloyloxy)propionamide; then 12 g of this organic corrosion inhibitor was compounded with 8 g of cerium ammonium nitrate, 5 g of sodium polyphosphate, and 3 g of tea polyphenols to obtain a clear and transparent solution. Other necessary technical details not mentioned above are provided in the foregoing examples.

[0116] Example 8:

[0117] 0.1 mol of 5-hydroxytryptophan was reacted with 0.12 mol of allyl glycidyl ether to prepare the organic corrosion inhibitor N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propionamide; then 15 g of this organic corrosion inhibitor was compounded with 5 g of sodium tungstate, 2 g of hydroxypropyl cellulose, and 3 g of 5-sulfosalicylic acid to obtain a clear and transparent solution. Other necessary technical details not mentioned above are described in the foregoing examples.

[0118] Example 9:

[0119] 0.1 mol of (1,2,4-oxadiazol-3-yl)methylamine was reacted with 0.15 mol of allyl glycidyl ether to prepare the organic corrosion inhibitor N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propionamide; then 10 g of this organic corrosion inhibitor was compounded with 5 g of sodium molybdate, 5 g of sodium tungstate, and 3 g of succinic acid to obtain a clear and transparent solution. Other necessary technical details not mentioned herein are described in the foregoing examples.

[0120] Example 10:

[0121] 0.1 mol of 2-amino-4-methylthiazole was reacted with 0.12 mol of allyl glycidyl ether to prepare the organic corrosion inhibitor N-(4-methylthiazole-3-yl)-3-(1-en-propoxy)propionamide; then 15 g of this organic corrosion inhibitor was compounded with 8 g of sodium polyphosphate, 5 g of cerium ammonium nitrate, and 4 g of tea polyphenols to obtain a clear and transparent solution. Other necessary technical details not mentioned above are provided in the foregoing examples.

[0122] Example 11

[0123] In a three-necked flask, 150 mL of 60 wt% ethanol solution was added, followed by the sequential addition of 0.1 mol 5-hydroxytryptophan, 0.12 mol allyl glycidyl ether, 0.1 mol 2-amino-4-methylthiazole, and 0.12 mol glycidyl methacrylate. The mixture was refluxed at 85 °C for 5 h. After concentration under reduced pressure, crystallization, washing, and drying, a mixture of two organic corrosion inhibitors (a combination of N-[1-carboxy-(5-hydroxyindol-3-yl)-propyl]-3-(1-allyloxy)propionamide and N-(4-methylthiazol-3-yl)-3-(2-methacryloyloxy)propionamide) was obtained. Subsequently, 12 g of this combined organic corrosion inhibitor (mass ratio 1:1), 8 g of sodium molybdate, and 4 g of 5-sulfosalicylic acid were added to 70 mL of 30 wt% ethanol solution. The mixture was stirred until clear to obtain a flash rust inhibitor solution.

[0124] Example 12

[0125] N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide and N-(4-methylthiazolyl)-3-(1-en-propoxy)propamide were synthesized in a three-necked flask in a parallel reaction ratio of 0.1 mol + 0.1 mol of reactants to obtain two organic corrosion inhibitors. The two were mixed at a mass ratio of 2:1, and 15 g of the mixture was added to 80 mL of 30wt% ethanol solution. Then, 6 g of sodium tungstate, 4 g of sodium polyphosphate, and 3 g of tea polyphenols were added, and the mixture was stirred to dissolve, yielding a flash rust inhibitor solution.

[0126] Example 13

[0127] Three organic corrosion inhibitors were simultaneously synthesized in a three-necked flask: N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(2-methacryloyloxy)propionamide, N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propionamide, and N-(4-methylthiazolyl)-3-(2-methacryloyloxy)propionamide. After drying, they were mixed. A total of 15 g of the three inhibitors was dissolved in 70 mL of 30 wt% ethanol solution at a mass ratio of 3:3:4. Then, 5 g of cerium ammonium nitrate, 3 g of hydroxypropyl cellulose, and 2 g of succinic acid were added, and the mixture was stirred until clear to obtain a flash rust inhibitor solution.

[0128] Example 14

[0129] N-(4-methylthiazolyl-3-yl)-3-(1-en-propoxy)propamide and N-[1-carboxy-(5-hydroxyindol-3-yl)-propyl]-3-(1-en-propoxy)propamide (total 10 g, ratio 1:2) were mixed and dissolved in 60 mL of 30wt% ethanol solution. Then, 5 g of sodium molybdate, 5 g of sodium polyphosphate and 3 g of tea polyphenols were added and stirred until clear to obtain a flash rust inhibitor solution.

[0130] Table 2. Q235 carbon steel sheets with different compound anti-flash rust agents (0.6%) Weight loss test data in hydrochloric acid solution

[0131]

[0132] In further corrosion prevention experiments in Examples 11-14, we conducted compound application experiments of various organic corrosion inhibitors to verify their performance advantages in preventing flash rust in cooling coatings for power equipment. Taking the combination of N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propamide and N-(4-methylthiazolyl)-3-(2-methacryloyloxy)propamide as an example, after mixing the two in equal proportions, sodium molybdate and 5-sulfosalicylic acid were added as auxiliary components, which could form a denser adsorption film structure on the steel substrate surface. The weight loss test showed that the corrosion inhibition efficiency of this compound system exceeded 96% at both 12 hours and 24 hours, which was significantly higher than the effect of a single organic corrosion inhibitor. Electrochemical impedance spectroscopy results showed that its low-frequency impedance modulus was further improved, indicating that the protective layer constructed by the compound combination on the metal surface was more stable and could effectively inhibit the corrosion process.

[0133] Further experiments showed that N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide and N-(4-methylthiazolyl)-3-(1-en-propoxy)propamide were compounded in a 2:1 ratio and applied to an epoxy waterborne coating system. Results showed that no obvious rust spots were observed on the coating surface under high humidity conditions, and the flash rust level was controlled within the range of 0–1, demonstrating a significant advantage over the control single-agent formulation. Simultaneously, accelerated salt spray testing showed that the compounded system still exhibited only slight rust traces after 240 hours, demonstrating long-term stable protective performance. This indicates that the compounded corrosion inhibitor can function simultaneously at both anodic and cathodic reaction sites, significantly reducing the corrosion current density and creating a synergistic effect of dual anodic and cathodic polarization.

[0134] In the compounding experiment of three organic corrosion inhibitors, indole, thiazole, and oxadiazole compounds were selected and used in a 3:3:4 ratio, working synergistically with components such as ceric ammonium nitrate and hydroxypropyl cellulose. Test results showed that the corrosion inhibition efficiency remained above 96.5%. Compared with single organic corrosion inhibitors, this multi-component compound system can simultaneously form a protective layer at both defective and smooth areas of the steel surface, preventing the formation of localized corrosion pits, resulting in more uniform overall coverage and superior protective effect. In the electrochemical polarization curve test, the corrosion current density value of this compound system was further reduced, proving that the compounding significantly enhances the electrochemical stability of the system.

[0135] The principle behind the effectiveness of compound corrosion inhibitors lies in the complementary adsorption mechanisms of organic corrosion inhibitor molecules with different structures on metal surfaces. Indole molecules possess a large π-conjugated system, easily covering smooth areas of the steel surface to form an electron cloud barrier; thiazole and oxadiazole molecules are smaller and more polar, enabling them to penetrate deep into surface micropores and defects for passivation. The synergistic effect of these two types of inhibitors not only increases the thickness of the coating on the metal surface but also improves its density, significantly enhancing its ability to block corrosive media penetration. Furthermore, the simultaneous presence of multiple corrosion inhibitors allows them to exert inhibitory effects at different reaction sites on the anolyte and cathodic sides, forming a comprehensive inhibition mechanism with dual polarization. This mechanism comprehensively blocks the corrosion reaction pathway, resulting in improved overall corrosion inhibition efficiency and long-term maintenance of protective performance.

[0136] Experimental data and mechanistic analysis from the above-mentioned various compound formulations show that the compound system of organic corrosion inhibitors exhibits superior performance in corrosion inhibition efficiency, flash rust resistance, and long-term salt spray resistance compared to single formulations. Its advantages are not only reflected in its highly efficient corrosion inhibition in the short term, but also in its stability and durability in long-term service environments. More importantly, the introduction of the compound system reduces the amount of single corrosion inhibitor required while achieving excellent corrosion inhibition, thereby reducing the environmental burden and aligning with the development direction of green environmental protection. Therefore, compound anti-flash rust agents using a combination of multiple organic corrosion inhibitors demonstrate significant synergistic advantages and broad application prospects in water-based cooling coatings.

[0137] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention.

Claims

1. A cooling coating compound anti-flash rust agent, characterized in that, include: Organic corrosion inhibitor, selected from one or more combinations of N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propamide, N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide, N-(4-methylthiazol-3-yl)-3-(1-en-propoxy)propamide, N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(2-methacryloyloxy)propamide, and N-(4-methylthiazol-3-yl)-3-(2-methacryloyloxy)propamide; Inorganic corrosion inhibitors are selected from one or two of sodium molybdate, sodium tungstate, sodium polyphosphate, and cerium ammonium nitrate; The corrosion inhibitor is selected from one or two of hydroxypropyl cellulose, succinic acid, 5-sulfosalicylic acid, and tea polyphenols.

2. The compound anti-flash rust agent according to claim 1, characterized in that, The organic corrosion inhibitor is N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propamide.

3. The cooling coating compound anti-flash rust agent according to claim 1, characterized in that, The organic corrosion inhibitor comprises a combination of N-[1-carboxy-(5-hydroxyindol-3-yl)-propyl]-3-(1-en-propoxy)propamide and N-(4-methylthiazolyl)-3-(2-methacryloyloxy)propamide, in a mass ratio of 1:

1.

4. The cooling coating compound anti-flash rust agent according to claim 1, characterized in that, The organic corrosion inhibitor comprises a combination of N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide and N-(4-methylthiazolyl)-3-(1-en-propoxy)propamide in a mass ratio of 2:

1.

5. The cooling coating compound anti-flash rust agent according to claim 1, characterized in that, The organic corrosion inhibitor comprises a combination of N-[1-carboxy-(5-hydroxyindole-3-yl)-propyl]-3-(2-methacryloyloxy)propamide, N-[(1,2,4-oxadiazol-3-yl)methyl]-3-(1-en-propoxy)propamide, and N-(4-methylthiazolyl)-3-(2-methacryloyloxy)propamide, in a mass ratio of 3:3:

4.

6. The cooling coating compound anti-flash rust agent according to claim 1, characterized in that, The organic corrosion inhibitor comprises a combination of N-(4-methylthiazolyl-3-yl)-3-(1-en-propoxy)propamide and N-[1-carboxyl-(5-hydroxyindole-3-yl)-propyl]-3-(1-en-propoxy)propamide, with a mass ratio of 1:

2.

7. The cooling coating compound anti-flash rust agent according to claim 1, characterized in that, The inorganic corrosion inhibitor comprises a combination of sodium molybdate and tea polyphenols.

8. The cooling coating compound anti-flash rust agent according to claim 1, characterized in that, Corrosion inhibitors include a combination of 5-sulfosalicylic acid and sodium polyphosphate.

9. The cooling coating compound anti-flash rust agent according to claim 1, characterized in that, The flash rust inhibitor is composed of the following components in the following mass ratios: 10-20 parts organic corrosion inhibitor, 5-15 parts inorganic corrosion inhibitor, 3-6 parts corrosion inhibitor, and the remainder is an ethanol solution.

10. The cooling coating compound anti-flash rust agent according to claim 1, characterized in that, The amount of anti-flash rust agent added to water-based coatings is 0.6 wt% of the coating mass.

11. The cooling coating compound anti-flash rust agent according to claim 1, characterized in that, The inorganic corrosion inhibitor includes a combination of sodium tungstate and cerium ammonium nitrate.

12. The cooling coating compound anti-flash rust agent according to claim 1, characterized in that, Corrosion inhibitors include hydroxypropyl cellulose and tea polyphenols.

13. A method for preparing a cooling coating compound anti-flash rust agent, characterized in that, Includes the following steps: Reactant I and reactant II in an ethanol solution to generate an organic corrosion inhibitor as described in any one of claims 1-12, wherein reactant I is selected from 5-hydroxytryptophan, (1,2,4-oxadiazol-3-yl)methylamine and 2-amino-4-methylthiazole, and reactant II is selected from allyl glycidyl ether and glycidyl methacrylate. The obtained organic corrosion inhibitor is mixed and dissolved with any one of the inorganic corrosion inhibitors and corrosion inhibitors described in claims 1-12 to obtain the compound anti-flash rust agent.

14. The preparation method according to claim 13, characterized in that, The reaction temperature between reactant I and reactant II is 75–95°C, and the reaction time is 3–6 h.

15. The preparation method according to claim 13, characterized in that, The concentration of the ethanol solution is 30 wt%, and the resulting compound liquid is clear and transparent.

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