Long-acting self-repairing anticorrosive coating, preparation method and application thereof

Abstract

The present application relates to a kind of anticorrosive paint, specifically to a kind of long-acting self-repairing anticorrosive paint and its preparation method, application.The present application is first modified with polythiol epoxy resin to obtain thiol-modified epoxy resin, then thiol-modified epoxy resin is compounded with epoxy resin as main film-forming material, so that a long-acting self-repairing anticorrosive paint is obtained.The long-acting self-repairing anticorrosive paint prepared by the present application contains disulfide bond, when the coating is corroded and damaged or microcracks appear under external force, the disulfide bond in the coating rearranges and combines under heating, and the coating self-repairs.The coating provided by the present application not only meets the requirements of self-repairing effect, has good self-repairing effect, and has high adhesion and excellent corrosion resistance.

Description

Technical Field

[0001] This invention relates to an anti-corrosion coating, and more specifically, to a long-lasting self-healing anti-corrosion coating, its preparation method, and its application. Background Technology

[0002] Metals with high mechanical properties and electrical conductivity are widely used in aerospace, shipbuilding, bridge construction, automotive, and electronics industries. However, corrosion of metals in service environments not only imposes a significant economic burden but can also lead to serious safety issues and environmental hazards. Currently, using protective coatings with anti-corrosion properties is considered the most effective, economical, and convenient strategy for metal corrosion protection. When in good condition, coatings can provide excellent physical shielding against corrosive ions and water molecules. However, during transportation and service, environmental factors (UV radiation, heat, oxygen, moisture, and ions, etc.) and mechanical damage can cause the coating's shielding performance to be lost. Without timely and effective repair, these damages will create pathways for corrosive media, leading to metal corrosion. Currently, most damaged coatings require manual repair or replacement, which is both expensive and time-consuming. Therefore, the development of self-healing, long-lasting anti-corrosion coatings has become particularly important.

[0003] Patent CN101613543A discloses a functional silica nanoparticle with a surface-coated corrosion inhibitor and polyelectrolyte self-assembled composite film. These particles are then incorporated into a metal coating to achieve controlled release of corrosion inhibitor molecules, thus achieving long-term corrosion protection. Meanwhile, patent CN105727299A also discloses a method where corrosion inhibitor molecules are adsorbed within the cavities of hollow mesoporous silica and incorporated into a metal coating. When corrosion occurs in the coating, causing a change in the pH of the environment, the internal corrosion inhibitor molecules are automatically released, self-repairing the damaged coating.

[0004] The self-healing coatings disclosed above are all exogenous, meaning that encapsulated repair factors are introduced into the coating. When the coating is damaged, the encapsulation layer ruptures, and the repair factors spill out, thus polymerizing to form a protective film to achieve self-repair. However, existing nano-containers have small capacity to load repair factors, and the doping amount in metal coatings is generally less than 5%, resulting in poor repair effects and low self-repair rates. Moreover, if the repaired exogenous repair coating is damaged again, it lacks the ability to self-repair again. Summary of the Invention

[0005] To address the problems of low self-healing rate and limited self-healing cycles in existing self-healing coatings, this invention provides an intrinsic self-healing long-lasting anti-corrosion coating. The intrinsic self-healing long-lasting anti-corrosion coating provided by this invention features long anti-corrosion duration, high self-healing cycles, and excellent repair effect.

[0006] Polythiols contain disulfide bonds, which can undergo homolytic cleavage at room temperature. The resulting sulfur radicals can then undergo dynamic displacement reactions with other disulfide bonds. When polythiols are used in coatings, their dynamic and reversible changes give the coatings a self-healing function.

[0007] However, during the experiment, it was found that the coating obtained by adding polythiol to the existing anti-corrosion coating (which uses epoxy resin as the main film-forming substance) had a self-healing effect that met the requirements, but its anti-corrosion performance was significantly reduced and could not meet the anti-corrosion requirements.

[0008] Furthermore, experimental results show that coatings prepared using thiol-modified epoxy resin as the main film-forming substance (without epoxy resin) have poor film sealing properties after curing, and cannot effectively intercept corrosive agents from contacting the protected metal, thus failing to meet anti-corrosion requirements.

[0009] However, coatings obtained by compounding thiol-modified epoxy resin with epoxy resin as the main film-forming substance not only meet the requirements for self-healing effect and have a good self-healing effect, but also improve the anti-corrosion effect.

[0010] Therefore, this invention, based on existing anti-corrosion coatings that use epoxy resin as the main film-forming substance, adds thiol-modified epoxy resin as the main film-forming substance to obtain a long-lasting self-healing anti-corrosion coating.

[0011] To distinguish between epoxy resin as the main film-forming substance and epoxy resin modified with polythiol, the epoxy resin as the main film-forming substance is referred to as epoxy resin A, and the epoxy resin modified with polythiol is referred to as epoxy resin B. Epoxy resin A and epoxy resin B may be the same or different.

[0012] One of the objectives of this invention is to provide a long-lasting self-healing anti-corrosion coating.

[0013] The long-lasting self-healing anti-corrosion coating uses epoxy resin A and thiol-modified epoxy resin as the main film-forming substances; the thiol-modified epoxy resin is formed by the reaction of polythiol and epoxy resin B.

[0014] The long-lasting self-healing anti-corrosion coating is composed of component A and component B; the weight ratio of component A to component B is 100:(20-40), preferably 100:(25-30), for example 100:27;

[0015] Component A comprises the following components in parts by weight:

[0016] Epoxy resin A: 50-75 parts by weight, for example 55, 65, or 70 parts by weight, preferably 55-70 parts by weight;

[0017] 20 to 40 parts by weight of thiol-modified epoxy resin, for example 20, 25, or 35 parts by weight, preferably 20 to 35 parts by weight;

[0018] 5 to 15 parts by weight of epoxy diluent, for example, 10 parts by weight;

[0019] The total weight of epoxy resin A, thiol-modified epoxy resin and epoxy diluent is 100 parts by weight.

[0020] Component B comprises the following components in parts by weight:

[0021] 50 to 70 parts by weight of phenolic amine resin, for example 50, 60, or 70 parts by weight, preferably 45 to 55 parts by weight;

[0022] The diluent is 30 to 50 parts by weight, for example, 30, 40, or 50 parts by weight, preferably 45 to 55 parts by weight;

[0023] The total weight of phenolic amine resin and diluent is 100 parts by weight.

[0024] The epoxy resin A is selected from one or more of bisphenol F type epoxy resin, bisphenol A type epoxy resin, and phenolic epoxy resin; for example, it is selected from one or more of the following: bisphenol F-170 epoxy resin, bisphenol A type epoxy resin E-12, bisphenol A type epoxy resin E-20, bisphenol A type epoxy resin E-51, bisphenol A type epoxy resin E-44, phenolic epoxy resin F-51, phenolic epoxy resin F-44, and phenolic epoxy resin F-48.

[0025] The epoxy diluent is selected from glycidyl ethers with 12-14 carbon atoms, preferably from at least one of phenyl glycidyl ether, 1,4-cyclohexanediethanol diglycidyl ether, trimethylolpropane triglycidyl ether, neopentyl glycol diglycidyl ether, and o-tolyl glycidyl ether.

[0026] The phenolic amine resin is selected from one or more of unmodified phenolic amine resins and modified phenolic amine resins; for example, it is selected from one or more of phenolic amine 810, phenolic amine 910, phenolic amine T31, phenolic amine T33 and phenolic amine T316, and modified phenolic amine 6305; preferably, it is a modified phenolic amine resin, for example, at least one of phenolic amine 6309 and phenolic amine 6305. The introduction of modified phenolic amine enhances the acid and alkali corrosion resistance, curing performance on damp substrates, and good water resistance of the paint film.

[0027] The diluent is preferably an alcohol-based diluent, selected from at least one of glycerol, benzyl alcohol, methanol, ethanol, and ethylene glycol. Alcohol-based diluents reduce the viscosity of the modified phenolic amine, simplifying the application process.

[0028] The number average molecular weight of the thiol-modified epoxy resin is 800-1500, for example 809 or 1021, preferably 800-1100.

[0029] The thiol-modified epoxy resin is formed by reacting polythiol and epoxy resin B. The preparation method of the thiol-modified epoxy resin includes: reacting polythiol and epoxy resin B at a temperature of 50-70°C until the mercapto groups in the thiol are completely reacted, and the product obtained is the thiol-modified epoxy resin; preferably, the reaction time is 2-4 days.

[0030] The epoxy resin B is selected from at least one of bisphenol A type epoxy resin, phenolic epoxy resin, and hyperbranched epoxy resin.

[0031] The polythiol is selected from at least one of dimercaptopolythiol, trimercaptopolythiol, and tetramercaptopolythiol.

[0032] The weight ratio of the polythiol to epoxy resin B is 10:5 to 7, for example, 10:5 or 10:6.25.

[0033] The aforementioned long-lasting self-healing anti-corrosion coating may further include pigments, fillers, and / or additives in component A; based on a total of 100 parts by weight of epoxy resin A, thiol-modified epoxy resin, and epoxy diluent, the pigments and fillers are 90-100 parts by weight, for example, 97.5 parts; and the additives are 2-5 parts by weight, for example, 2.5 or 4.5 parts by weight.

[0034] The pigments and fillers can be any one or more existing pigments and fillers used in anti-corrosion coatings. Specifically, they can be selected from at least one of magnesium carbonate, talc, mica powder, barium sulfate, wollastonite, silicon carbide, silica fume, light calcium carbonate, titanium dioxide, iron oxide red, aluminum oxide, zinc oxide, and calcium oxide.

[0035] The additive is selected from at least one of wetting and dispersing agents, silane coupling agents, leveling agents, and thixotropic agents.

[0036] The wetting and dispersing agent can be any one or more existing wetting and dispersing agents used in anti-corrosion coatings; specifically, it can be selected from at least one of BYK-P 2710, BYK-P104S, BYK-9076, and MOK-5012.

[0037] The silane coupling agent can be any one or more existing silane coupling agents used in anti-corrosion coatings.

[0038] The leveling agent can be any one or more existing leveling agents used in anti-corrosion coatings; specifically, it can be selected from at least one of BYK-361N, BYK-342, and Deqian 837.

[0039] The thixotropic agent can be any one or more existing thixotropic agents used in anti-corrosion coatings; specifically, it can be selected from at least one of polyamide wax, fumed silica, and organobentonite.

[0040] The specific dosages of the wetting and dispersing agent, silane coupling agent, leveling agent, and thixotropic agent are the conventional dosages. Technicians can select and add them according to the actual situation within the dosage range specified by the additives.

[0041] In the formulation of this invention, conventional additives in the art, such as defoamers, may also be added. The dosage is the conventional dosage, and those skilled in the art can choose to add them according to the actual situation.

[0042] The second objective of this invention is to provide a method for preparing the long-lasting self-healing anti-corrosion coating as described in the first objective.

[0043] The preparation method includes: mixing and grinding the components of component A according to the weight ratio to obtain component A; mixing the components of component B according to the weight ratio to obtain component B; and mixing component A and component B according to the weight ratio to obtain the self-healing long-lasting anti-corrosion coating.

[0044] A third objective of this invention is to provide an application of the long-lasting self-healing anti-corrosion coating described in one objective. Specifically, the long-lasting self-healing anti-corrosion coating described in one objective is applied in the field of metal coatings, especially in the field of metal coatings where microcracks are easily formed.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] The long-lasting self-healing anti-corrosion coating developed in this invention contains disulfide bonds, which can undergo homolytic cleavage at room temperature. The resulting sulfur free radicals can undergo dynamic displacement reactions with other disulfide bonds. When the coating is corroded or develops microcracks under external force, specific chemical bonds within the coating rearrange and recombine under heating, resulting in self-repair of the coating with high sensitivity. In other words, the disulfide bonds endow the coating with self-healing properties, enabling it to repair damaged areas at high temperatures, and the healed areas significantly block corrosive substances from reaching the metal surface.

[0047] Compared to existing self-healing coatings, the long-lasting self-healing anti-corrosion coating of this invention does not rely on nano-containers to load repair factors, thus overcoming the problem of small capacity of repair factors loaded by nano-containers, resulting in better self-healing effect and higher self-healing efficiency. Existing products require the consumption of repair factors during self-healing, limiting the number of self-healing cycles; while the long-lasting self-healing anti-corrosion coating of this invention can theoretically self-heal multiple times.

[0048] The long-lasting self-healing anti-corrosion coating developed in this invention has high adhesion and excellent anti-corrosion performance. Its self-healing function can prevent further corrosion.

[0049] The long-lasting self-healing anti-corrosion coating developed in this invention has mild reaction conditions, simple and easy-to-control process, no pollution, low cost, and is suitable for industrial production.

[0050] The long-lasting self-healing anti-corrosion coating developed in this invention can be applied to the long-lasting anti-corrosion of various engineering equipment and facilities. Detailed Implementation

[0051] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0052] All raw materials used in the following examples and comparative examples are commercially available, and the sources of each raw material are shown in Table 1.

[0053] Table 1

[0054] name Brand factory Epoxy Resin E51 E51 Nantong Xingchen Polythiol G4 G4 Noryon Defoamer BYK-085 BYK Additives Factory Wetting and dispersing agents BYK-9076 BYK Additives Factory Leveling agent BYK-354 BYK Additives Factory Alicyclic amine curing agent 3895L Adico Chemicals Modified phenolic amine Cardolite Epoxy diluent 5748 Shanghai Resin Factory Alcohol diluents benzyl alcohol Shanghai test mica powder GA-4 Chuzhou Gree Chemical aluminum powder ZLG101 Jinan Zhangqiu Pigment Factory Bisphenol F-170 epoxy resin EF-170 Nan Ya Resin Factory

[0055] Example 1

[0056] 160g of bisphenol A type epoxy resin E51 was added to a three-necked flask, followed by 100g of polythiol G4. The mixture was heated to 50℃ with constant stirring and reacted for 3 days. Fourier transform infrared spectroscopy was used to observe the thiol content. The reaction was considered complete when the thiol groups had fully reacted, yielding a thiol-modified epoxy resin. Molecular weight analysis showed that the number-average molecular weight of the prepared thiol-modified epoxy resin was 1021.

[0057] Example 2

[0058] 160g of bisphenol A type epoxy resin E51 was added to a three-necked flask, followed by 80g of polythiol G4. The mixture was heated to 50℃ with constant stirring and reacted for 3 days. Fourier transform infrared spectroscopy was used to observe the thiol content. The reaction was considered complete when the thiol groups had fully reacted, yielding a thiol-modified epoxy resin. Molecular weight analysis showed that the number-average molecular weight of the prepared thiol-modified epoxy resin was 809.

[0059] Example 3

[0060] (1) 30 parts by weight of bisphenol F-170 epoxy resin and 20 parts by weight of polythiol modified epoxy resin prepared in Example 1 were added to 40 parts by weight of bisphenol A epoxy resin E51. While stirring, 10 parts by weight of phenyl glycidyl ether was added. After mixing evenly, 67.5 parts by weight of mica powder, 10 parts by weight of aluminum powder, 20 parts by weight of modified calcium phosphate, 1 part by weight of leveling agent, 0.5 parts by weight of defoamer, 2 parts by weight of silane coupling agent and 1 part by weight of thixotropic agent were added. The mixture was then dispersed by a three-roll mill to obtain component A.

[0061] (2) Add 30 parts by weight of benzyl alcohol to 70 parts by weight of phenolic amine resin and stir thoroughly with a mixer to obtain component B.

[0062] (3) When using, mix components A and B at a weight ratio of 100:35 to obtain a long-lasting self-healing epoxy anti-corrosion coating.

[0063] Example 4

[0064] (1) 30 parts by weight of bisphenol F-170 epoxy resin and 20 parts by weight of polythiol modified epoxy resin prepared in Example 2 were added to 40 parts by weight of bisphenol A epoxy resin E51. While stirring, 10 parts by weight of phenyl glycidyl ether was added. After mixing evenly, 67.5 parts by weight of mica powder, 10 parts by weight of aluminum powder, 20 parts by weight of modified calcium phosphate, 1 part by weight of leveling agent, 0.5 parts by weight of defoamer, 2 parts by weight of silane coupling agent and 1 part by weight of thixotropic agent were added. The mixture was then dispersed by a three-roll mill to obtain component A.

[0065] (2) Add 50 parts by weight of benzyl alcohol to 50 parts by weight of phenolic amine resin and stir thoroughly with a mixer to obtain component B.

[0066] (3) When using, mix components A and B at a weight ratio of 100:38 until homogeneous to obtain a long-lasting self-healing epoxy anti-corrosion coating.

[0067] Example 5

[0068] (1) 45 parts by weight of bisphenol F-170 epoxy resin and 35 parts by weight of polysulfide modified epoxy resin prepared in Example 1 were added to 10 parts of epoxy resin E51, 10 parts by weight of phenyl glycidyl ether were added, and the mixture was stirred continuously to make it uniform. Then, 67.5 parts by weight of mica powder, 10 parts by weight of aluminum powder, 20 parts by weight of modified calcium phosphate, 0.5 parts by weight of defoamer, 1 part by weight of leveling agent and 1 part by weight of thixotropic agent were added and dispersed by three-roll mill to obtain component A.

[0069] (2) Add 40 parts by weight of benzyl alcohol to 60 parts by weight of phenolic amine resin and stir thoroughly with a mixer to obtain component B.

[0070] (3) When using, mix components A and B at a weight ratio of 100:25 to obtain a long-lasting self-healing epoxy anti-corrosion coating.

[0071] Example 6

[0072] (1) 45 parts by weight of bisphenol F-170 epoxy resin and 35 parts by weight of polysulfide modified epoxy resin prepared in Example 2 were added to 10 parts of epoxy resin E51, 10 parts by weight of phenyl glycidyl ether were added, and the mixture was stirred continuously to make it uniform. Then, 67.5 parts by weight of mica powder, 10 parts by weight of aluminum powder, 20 parts by weight of modified calcium phosphate, 0.5 parts by weight of defoamer, 1 part by weight of leveling agent and 1 part by weight of thixotropic agent were added and dispersed by three-roll mill to obtain component A.

[0073] (2) Add 40 parts by weight of benzyl alcohol to 60 parts by weight of phenolic amine resin and stir thoroughly with a mixer to obtain component B.

[0074] (3) When using, mix components A and B at a weight ratio of 100:29 to obtain a long-lasting self-healing epoxy anti-corrosion coating.

[0075] Example 7

[0076] (1) 30 parts by weight of bisphenol F-170 epoxy resin and 25 parts by weight of polysulfide modified epoxy resin prepared in Example 1 were added to 35 parts by weight of E51 epoxy resin, 10 parts by weight of phenyl glycidyl ether were added, and the mixture was stirred continuously to make it uniform. Then, 67.5 parts by weight of mica powder, 10 parts by weight of aluminum powder, 20 parts by weight of modified calcium phosphate, 0.5 parts by weight of defoamer, 1 part by weight of leveling agent and 1 part by weight of thixotropic agent were added and dispersed by three-roll mill to obtain component A.

[0077] (2) Add 50 parts by weight of benzyl alcohol to 50 parts by weight of phenolic amine resin and stir thoroughly with a mixer to obtain component B.

[0078] (3) When using, mix components A and B at a weight ratio of 100:30 to obtain a long-lasting self-healing epoxy anti-corrosion coating.

[0079] Comparative Example 1

[0080] (2) 30 parts by weight of bisphenol F-170 epoxy resin and 20 parts by weight of polythiol G4 were added to 40 parts by weight of bisphenol A epoxy resin E51, and 10 parts by weight of phenyl glycidyl ether were added. The mixture was stirred continuously until it was homogeneous. Then, 67.5 parts by weight of mica powder, 10 parts by weight of aluminum powder, 20 parts by weight of modified calcium phosphate, 0.5 parts by weight of defoamer, 1 part by weight of leveling agent and 1 part by weight of thixotropic agent were added and dispersed by three-roll milling to obtain component A.

[0081] (3) Add 30 parts by weight of benzyl alcohol to 70 parts by weight of phenolic amine resin and stir thoroughly with a mixer to obtain component B.

[0082] (4) When using, mix components A and B at a weight ratio of 100:30 to obtain epoxy anti-corrosion coating.

[0083] Comparative Example 2

[0084] (1) 90 parts by weight of the polysulfide modified epoxy resin prepared in Example 1 were mixed with 10 parts by weight of phenyl glycidyl ether and stirred continuously until they were evenly mixed. Then, 67.5 parts by weight of mica powder, 10 parts by weight of aluminum powder, 20 parts by weight of modified calcium phosphate, 0.5 parts by weight of defoamer, 1 part by weight of leveling agent and 1 part by weight of thixotropic agent were added and dispersed by three-roll mill to obtain component A.

[0085] (2) Add 30 parts by weight of benzyl alcohol to 70 parts by weight of phenolic amine resin and stir thoroughly with a mixer to obtain component B.

[0086] (3) When using, mix components A and B at a weight ratio of 100:20 to obtain epoxy anti-corrosion coating.

[0087] Comparative Example 3

[0088] (1) 45 parts by weight of bisphenol F-170 epoxy resin and 45 parts by weight of bisphenol A epoxy resin E51 were mixed with 10 parts by weight of phenyl glycidyl ether and stirred continuously until they were evenly mixed. Then, 67.5 parts by weight of mica powder, 10 parts by weight of aluminum powder, 20 parts by weight of modified calcium phosphate, 0.5 parts by weight of defoamer, 1 part by weight of leveling agent and 1 part by weight of thixotropic agent were added and dispersed by three-roll mill to obtain component A.

[0089] (2) Add 30 parts by weight of benzyl alcohol to 70 parts by weight of phenolic amine resin and stir thoroughly with a mixer to obtain component B.

[0090] (3) When using, mix components A and B at a weight ratio of 100:35 to obtain epoxy anti-corrosion coating.

[0091] Performance testing

[0092] Verifying the repair efficiency of self-healing coatings is a key technical indicator characterizing the active protective function of coatings. Higher self-healing efficiency indicates a stronger ability for the coating to self-repair after damage, providing long-term protection to the underlying metal. Key information about the coating's self-healing efficiency can be obtained by calculating the change in the coating's impedance modulus.

[0093] The coatings prepared in Examples 3-7 and Comparative Examples 1-3 were tested for self-healing time and self-healing efficiency according to GB / T 39482.3-2020 electrochemical impedance spectroscopy. Self-healing efficiency test: The self-healing efficiency of the coating was calculated by observing the change in the low-frequency impedance modulus (|Z|0.01Hz) after the damaged coating was immersed for a certain period.

[0094] The coatings prepared in Examples 3-7 and Comparative Examples 1-3 were tested for film adhesion according to the national standard GB / T 5210-2006.

[0095] The coatings prepared in Examples 3-7 and Comparative Examples 1-3 were tested for corrosion resistance according to the national standard GB / T 10125-2021. The test results are shown in Table 2.

[0096] Table 2

[0097] Group Self-repair time (h) Self-repair efficiency (%) Adhesion performance Corrosion resistance Example 3 2 85.13 8.6 very good Example 4 2 87.28 8.9 very good Example 5 2 85.56 7.9 very good Example 6 2 86.91 8.4 very good Example 7 2 85.04 8.5 better Comparative Example 1 2 87.09 6.5 generally Comparative Example 2 2 86.4 5.7 generally Comparative Example 3 none 0 9.1 good

[0098] The following conclusions can be drawn from the data in Table 2.

[0099] The epoxy anti-corrosion coating prepared in Comparative Example 1 uses epoxy resin and polythiol as the main film-forming substances in component A. The coating film has good self-healing ability, but the coating film is relatively soft and cannot effectively isolate corrosive agents from corroding the substrate. Its adhesion performance and anti-corrosion effect are average.

[0100] The epoxy anti-corrosion coating prepared in Comparative Example 2 uses only thiol-modified epoxy resin as the main film-forming substance of component A; its viscosity is relatively high, which increases the difficulty of construction. Although it has excellent self-healing ability, it still has the disadvantages of soft paint film and poor adhesion and anti-corrosion performance.

[0101] The epoxy anti-corrosion coating prepared in Comparative Example 3 uses only epoxy resin as the main film-forming substance of component A. After curing, the coating film has high hardness, resistance to cathodic disbondment, salt spray, and excellent adhesion performance. It can effectively isolate corrosive agents from corroding the substrate, but it does not have self-healing ability.

[0102] The long-lasting self-healing epoxy anti-corrosion coatings prepared in Examples 3-7 exhibit self-healing properties, and when the self-healing time of Examples 3-7 is 2 hours, the self-healing efficiency can reach over 85%. Simultaneously, the long-lasting self-healing epoxy anti-corrosion coatings prepared in Examples 3-7 also demonstrate excellent adhesion and anti-corrosion performance.

[0103] Compared to Comparative Example 1, Example 3 used thiol-modified epoxy resin instead of polythiol. The self-healing efficiency of Example 3 was comparable to that of Comparative Example 1; however, the adhesion and anti-corrosion properties of Example 3 were significantly better than those of Comparative Example 1. This indicates that, compared to the combination of polythiol and epoxy resin, the combination of thiol-modified epoxy resin and epoxy resin not only produces a self-healing effect but also improves adhesion and anti-corrosion properties.

[0104] Compared to Comparative Example 2, Example 3 used a compound of thiol-modified epoxy resin and epoxy resin instead of thiol-modified epoxy resin. The self-healing efficiency of Example 3 was comparable to that of Comparative Example 2; however, the adhesion and anti-corrosion properties of Example 3 were significantly better than those of Comparative Example 2. Note: Compared to thiol-modified epoxy resin, the compound of thiol-modified epoxy resin and epoxy resin not only produces a self-healing effect but also improves adhesion and anti-corrosion properties.

[0105] Examples 3-7 use film-forming substances compounded from those used in Comparative Examples 2 and 3. Compared to Comparative Examples 2 and 3, Examples 3-7 show no significant shortcomings in self-healing and corrosion resistance, exhibiting excellent overall performance. This demonstrates that compounding thiol-modified epoxy resin with epoxy resin in a specific ratio can produce a coating film with excellent self-healing, adhesion, and corrosion resistance.

[0106] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A long-lasting self-healing anti-corrosion coating, characterized in that, The long-lasting self-healing anti-corrosion coating is composed of component A and component B; the weight ratio of component A to component B is 100:(20-40). Component A comprises the following components in parts by weight: Epoxy resin A: 50-75 parts by weight; 20-40 parts by weight of thiol-modified epoxy resin; 5-15 parts by weight of epoxy diluent; The thiol-modified epoxy resin is formed by reacting polythiol and epoxy resin B. The epoxy resin B is selected from at least one of bisphenol A type epoxy resin, phenolic epoxy resin and hyperbranched epoxy resin. The polythiol is selected from at least one of dimercaptopolythiol, trimercaptopolythiol, and tetramercaptopolythiol; The total weight of epoxy resin A, thiol-modified epoxy resin and epoxy diluent is 100 parts by weight. Component B comprises the following components in parts by weight: 50-70 parts by weight of phenolic amine resin; 30-50 parts by weight of diluent; The total weight of phenolic amine resin and diluent is 100 parts by weight.

2. The long-lasting self-healing anti-corrosion coating as described in claim 1, characterized in that, The weight ratio of component A to component B is 100:(25-30); Component A comprises the following components in parts by weight: Epoxy resin A: 55-70 parts by weight; 20-35 parts by weight of thiol-modified epoxy resin; 5-15 parts by weight of epoxy diluent; The total weight of epoxy resin A, thiol-modified epoxy resin and epoxy diluent is 100 parts by weight. Component B comprises the following components in parts by weight: 50-60 parts by weight of phenolic amine resin; 40-50 parts by weight of diluent; The total weight of phenolic amine resin and diluent is 100 parts by weight.

3. The long-lasting self-healing anti-corrosion coating as described in claim 1, characterized in that, The epoxy resin A is selected from one or more of bisphenol F type epoxy resin, bisphenol A type epoxy resin, and phenolic epoxy resin; or / and The epoxy diluent is selected from at least one of phenyl glycidyl ether, 1,4-cyclohexanediethanol diglycidyl ether, trimethylolpropane triglycidyl ether, neopentyl glycol diglycidyl ether, and o-tolyl glycidyl ether; or / and, The phenolic amine resin is selected from one or more of unmodified phenolic amine resins and modified phenolic amine resins; or / and, The diluent is an alcohol-based diluent.

4. The long-lasting self-healing anti-corrosion coating as described in claim 1, characterized in that, The phenolic amine resin is a modified phenolic amine resin; or / and, The diluent is selected from at least one of glycerol, benzyl alcohol, methanol, ethanol, and ethylene glycol.

5. The long-lasting self-healing anti-corrosion coating as described in claim 1, characterized in that, The number average molecular weight of the thiol-modified epoxy resin is 800–1500.

6. The long-lasting self-healing anti-corrosion coating as described in claim 1, characterized in that, The number average molecular weight of the thiol-modified epoxy resin is 800–1100.

7. The long-lasting self-healing anti-corrosion coating as described in claim 1, characterized in that, The preparation method of the thiol-modified epoxy resin includes: reacting polythiol and epoxy resin B at a temperature of 50-70°C until the mercapto groups in the thiol are completely reacted to obtain the thiol-modified epoxy resin.

8. The long-lasting self-healing anti-corrosion coating as described in claim 7, characterized in that, The reaction time is 2-4 days.

9. The long-lasting self-healing anti-corrosion coating as described in claim 7, characterized in that, The weight ratio of the polythiol to epoxy resin B is 10:5 to 7.

10. The long-lasting self-healing anti-corrosion coating as described in claim 1, characterized in that, Component A also includes pigments, fillers, and / or additives; Based on a total of 100 parts by weight of epoxy resin A, thiol-modified epoxy resin, and epoxy diluent, 90-100 parts by weight of pigments and fillers, and 2-5 parts by weight of additives.

11. A method for preparing a long-lasting self-healing anti-corrosion coating as described in any one of claims 1-10, characterized in that, The preparation method includes: mixing and grinding the components of component A according to the weight ratio to obtain component A; mixing the components of component B according to the weight ratio to obtain component B; and mixing component A and component B according to the weight ratio to obtain the long-lasting self-healing anti-corrosion coating.

12. The application of a long-lasting self-healing anti-corrosion coating as described in any one of claims 1-10 in metal coatings.