Tannin-based epoxy resin and anticorrosive coating

Abstract

The application discloses a tannin acid-based epoxy resin and anticorrosive paint and relates to the technical field of paint. The tannin acid and the epoxy resin are combined through chemical reaction to generate a novel tannin acid-based epoxy resin. The tannin acid-based epoxy resin retains the function of generating chelate with iron rust, meanwhile, multiple epoxy structures in the structure generate thermosetting high-density crosslinked polymer structures after curing with a curing agent, the compactness of the paint film is greatly improved, the further corrosion of the corrosion medium is hindered, and the long-term effectiveness of the low-surface-treatment anticorrosive paint is ensured. Experimental results show that the adhesion of the tannin acid-based epoxy resin to the anticorrosive paint and the base material exceeds 13 MPa, and the neutral salt spray test reaches 4500 hours.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and more particularly to a tannic acid-based epoxy resin and an anti-corrosion coating. Background Technology

[0002] Metal corrosion is an irreversible, spontaneous process. Except for a very few precious metals like gold and platinum, most metals in nature readily undergo chemical or electrochemical reactions under the corrosive influence of atmospheric media, completing the corrosion process. This includes various steel structures in the atmosphere. Metal corrosion causes two main problems: firstly, corrosion of supporting components in steel structures can lead to major safety accidents; secondly, it can cause significant economic losses. The most effective way to combat metal corrosion is to coat its surface with an anti-corrosion coating, providing effective protection and extending its service life. Traditional anti-corrosion coatings require strict surface treatment processes to remove rust from the metal surface before application. This not only increases coating costs and difficulty but also generates substantial dust pollution.

[0003] Low-surface-treatment anti-corrosion coatings effectively solve the aforementioned problems. The metal substrate surface does not need to be completely treated to rust-proof standards; simply removing the surface rust is sufficient. The main mechanism involves certain components in the coating reacting with the rust on the steel surface, converting it into stable passivating compounds. This also improves the coating's adhesion and anti-corrosion effect. Currently, low-surface-treatment anti-corrosion coatings primarily enhance adhesion by forming chelates with metal oxides using small-molecule carboxylic acids or phenols such as tannic acid, phosphoric acid, and phytic acid. However, these small molecules are water-soluble, and the chelates formed will gradually precipitate or be washed away by rainwater, leading to a gradual loss of adhesion and preventing long-term anti-corrosion effects. Summary of the Invention

[0004] In view of this, the present invention provides a tannic acid-based epoxy resin and an anti-corrosion coating. When the anti-corrosion coating containing the tannic acid-based epoxy resin provided by the present invention is applied to a metal surface, it can convert the surface rust into a dense chelate, greatly improving the density of the paint film; at the same time, it can achieve a long-term anti-corrosion effect.

[0005] The tannic acid-based epoxy resin provided by this invention is obtained by reacting tannic acid, diol compounds, and epoxy compounds.

[0006] The molar ratio of tannic acid to the diol compound is 1:10~20;

[0007] The molar ratio of tannic acid to the epoxy compound is 1:100~200.

[0008] This invention combines small-molecule tannic acid and epoxy resin through a chemical reaction to obtain a novel tannic acid-based epoxy resin. This type of tannic acid-based epoxy resin retains the function of tannic acid forming chelates with rust, which can transform rust into a dense chelate, thus solving the problem of low surface treatment. In addition, the multiple epoxy structures in its structure can be cured with a curing agent to form a thermosetting, high-density cross-linked network polymer structure, which greatly improves the density of the paint film, hinders further corrosion by corrosive media, and the network structure firmly fixes the tannic acid structure to the metal substrate, so that it is not affected by the surrounding environment, ensuring the long-term effectiveness of the low-surface-treatment anti-corrosion coating.

[0009] In some specific implementations, the tannic acid-based epoxy resin of this invention is obtained by reacting the reaction product of tannic acid and a diol compound with an epoxy compound. Specifically, tannic acid undergoes a first substitution reaction with a diol compound to obtain a tannic acid-based diol. The tannic acid-based diol obtained from the above reaction then undergoes a second substitution reaction with an epoxy compound to obtain the tannic acid-based epoxy resin.

[0010] The tannic acid-based epoxy resin described in this invention may have the following structure, but this structure does not cover all tannic acid-based epoxy resins provided by this invention, and the scope of protection of this invention is not limited by this structure.

[0011] .

[0012] This invention provides a method for preparing the above-mentioned tannic acid-based epoxy resin, comprising:

[0013] Under an inert atmosphere, tannic acid and a diol compound undergo a first reaction under alkaline conditions to yield tannic acid-based diols.

[0014] The diol compounds described in this invention are preferably diol compounds with halogen end groups, and more preferably have the following structure:

[0015] ;

[0016] a and b are independently selected from integers from 1 to 10.

[0017] The epoxy compounds described in this invention are preferably halogen-terminated epoxy compounds, and more preferably have the following structure:

[0018] ;

[0019] R is selected from C1~C1 of an epoxy-substituted compound. 10 Alkyl groups.

[0020] In some specific implementations, the molar ratio of tannic acid to the diol compound is 1:10~20, preferably 1:10~18, and more preferably 1:10~15. In some specific implementations, the alkaline condition is sodium hydroxide. In some specific implementations, the solvent for the first reaction is water. In some specific implementations, the time for the first reaction is 4~10 hours, preferably 4~8 hours, and more preferably 4~6 hours. In some specific implementations, the temperature for the first reaction is 80~120°C, preferably 85~115°C, and more preferably 90~110°C.

[0021] After obtaining the tannic acid diol, the present invention preferably purifies it to obtain a pure compound. The present invention does not limit the purification method; any purification method well known to those skilled in the art can be selected. The present invention provides a specific purification method: the obtained tannic acid diol is extracted with an organic solvent and water, the organic phase is retained, and then washed with water 5-10 times to remove water, yielding pure tannic acid diol. In some specific implementations, the water removal involves adding anhydrous magnesium sulfate to the solution, allowing it to stand for 40-60 hours, and then filtering to remove the solid.

[0022] The tannic acid-based diol obtained from the above reaction, the epoxy compound, and the catalyst undergo a second reaction under alkaline conditions to obtain the tannic acid-based epoxy resin. In some specific implementations, the second reaction is carried out under an inert atmosphere. In some specific implementations, the alkaline condition is sodium hydroxide. In some specific implementations, the catalyst can be tetrabutylammonium bromide. In some specific implementations, the time for the second reaction is 4-10 hours, preferably 4-8 hours, more preferably 4-6 hours. In some specific implementations, the temperature for the second reaction is 60-100°C, preferably 65-95°C, more preferably 60-90°C.

[0023] After obtaining the tannic acid-based epoxy resin, the present invention also preferably purifies it to obtain a pure compound. The purification method is not particularly limited and can be the same as the purification method of the tannic acid-based diol mentioned above. The present invention will not elaborate further here. Those skilled in the art can choose the purification method according to their needs.

[0024] Based on the characteristics of the tannic acid-based epoxy resin mentioned above, this invention applies it to the field of anti-corrosion coatings and provides an anti-corrosion coating comprising component A and component B.

[0025] Component A comprises the following components by weight:

[0026] The above technical solution includes 13-32 parts of tannic acid-based epoxy resin, preferably 14-32 parts, more preferably 15-32 parts; it also includes 18-65 parts of glyceryl ether-based epoxy resin, preferably 19-65 parts, more preferably 20-65 parts; it also includes 1.5-22 parts of polyaniline, preferably 1.5-21 parts, more preferably 1.5-20 parts; and it also includes 13-60 parts of talc, preferably 14-60 parts, more preferably 15-60 parts. It also includes 0.35 to 3.5 parts of dispersant, preferably 0.35 to 3.4 parts, more preferably 0.35 to 3.5 parts; it also includes 0.2 to 3 parts of defoamer, preferably 0.2 to 2.8 parts, more preferably 0.2 to 2.6 parts; it also includes 1.8 to 7 parts of antisettling agent, preferably 1.8 to 6.7 parts, more preferably 1.8 to 6.5 parts; and it also includes 35 to 100 parts of diluent, preferably 38 to 100 parts, more preferably 40 to 100 parts.

[0027] Component B comprises the following components by mass:

[0028] The curing agent comprises 28 to 50 parts, preferably 28 to 47 parts, more preferably 28 to 45 parts; and also comprises 18 to 40 parts, preferably 18 to 37 parts, more preferably 18 to 35 parts, of a diluent.

[0029] The anti-corrosion coating provided by this invention only requires the removal of surface rust from the metal substrate before application; it does not require complete treatment to meet anti-rust standards. Furthermore, the tannic acid-based epoxy resin in the coating is tightly fixed within the network structure by chemical bonds within the epoxy structure, thus solving the problem of precipitation or loss of small-molecule tannic acid in traditional coatings and improving the long-lasting effectiveness of the anti-corrosion coating.

[0030] In some specific implementations, the mass ratio of component A to component B is 3 to 5:1.

[0031] The curing agent promotes rapid hardening of the coating surface, thereby accelerating drying; it also significantly improves the hardness of the coating, making it more durable and wear-resistant. After the coating application is complete, the curing agent continues to function, enhancing the hardness and toughness of the coating surface, thus strengthening the coating's protective capabilities. In some specific implementations, the curing agent is selected from at least one of polyamide curing agent 650, polyamide curing agent 651, NX-2015, NX-2040, NX-2041, and NX-2045, preferably one or more of polyamide curing agents 650, NX-2015, NX-2040, and NX-2045. The present invention does not impose any particular limitation on the proportions of these substances.

[0032] Glyceryl ether-based epoxy resins provide corrosion protection in anti-corrosion coatings and also enhance the coating's adhesion, hardness, and abrasion resistance. Due to their water solubility and water dispersibility, the coatings do not require organic solvents during use, which is beneficial to environmental protection and health. In some specific implementations, the glyceryl ether-based epoxy resin is selected from one or more of bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl ether. This invention does not impose any special restrictions on the proportions of these substances.

[0033] Dispersants effectively prevent the aggregation of particles in anti-corrosion coatings, thereby ensuring the formation of a uniform and dense protective film on the metal surface. This not only improves the anti-corrosion performance of the coating but also extends the service life of the metal material. In some specific implementations, the dispersant is selected from at least one of Disperbyk-103, Disperbyk-108, Disperbyk-115, Disperbyk-130, Disperbyk-111, Disperbyk-180, Disperbyk-160, Disperbyk-162, Disperbyk-164, and Disperbyk-182, preferably one or more of Disperbyk-103, Disperbyk-108, Disperbyk-130, and Disperbyk-160. The present invention does not impose any particular limitation on the proportions of the various substances.

[0034] Anti-settling agents maintain the uniform dispersion of pigment particles in coatings, preventing pigment settling during storage and application, thus preserving the uniformity and stability of the coating and extending its service life. In some specific implementations, the anti-settling agent is selected from at least one of BYK RHEOBYK-420, BYK RHEOBYK-410, BYK RHEOBYK-405, BYK RHEOBYK-425, and BYK RHEOBYK-430, preferably one or more of BYK RHEOBYK-405 and RHEOBYK-430. This invention does not impose any particular limitation on the proportions of the various substances.

[0035] Defoamers can disperse rapidly in coating systems, effectively reduce liquid tension, disrupt foam stability, achieve rapid defoaming and prevent foam regeneration, significantly improve the application performance of coatings, make the coating surface smooth and bubble-free, and enhance corrosion resistance. In some specific implementations, the defoamer is selected from at least one of BYK-052, BYK-088, BYK-1752, BYK-053, BYK-051, BYK-057, BYK-077, BYK-066N, BYK-392, BYK-333, BYK-141, and BYK-1790, preferably at least one of BYK-052, BYK-088, BYK-1752, BYK-053, BYK-051, BYK-057, BYK-077, BYK-066N, and BYK-392, more preferably one or more of BYK-052, BYK-088, BYK-1752, BYK-057, and BYK-392. The present invention does not impose any special restrictions on the proportion of each substance.

[0036] In anti-corrosion coatings, the thinner plays a role in adjusting the viscosity of the coating, making it easier to apply and spray, while ensuring the smoothness and uniformity of the coating. In some specific implementations, the thinner is selected from one or more of toluene, xylene, propylene glycol methyl ether acetate, propylene glycol methyl ether, ethylene glycol butyl ether, isopropanol, butyl acetate, and n-butanol. This invention does not impose any particular restrictions on the proportions of these substances.

[0037] Polyaniline possesses excellent chemical stability and electroactivity, enabling it to form a dense protective film in harsh corrosive environments. This effectively isolates the corrosive medium from direct contact with the substrate, thereby significantly extending the service life of the coated object. In some specific implementations, the polyaniline described in this invention is phosphate-doped polyaniline. This invention does not impose any special restrictions on its source; it can be purchased or synthesized independently. For example, it can be prepared using the method provided in invention patent CN102108241A: intrinsic polyaniline, phosphate ester, and water are mixed in a molar ratio of 1:(0.1~0.5):(40~5), and the mixture is reacted for 2~6 hours to obtain the phosphate-doped polyaniline.

[0038] Based on this, the present invention also provides a method for preparing the above-mentioned anti-corrosion coating, specifically including:

[0039] The above-mentioned tannic acid-based epoxy resin, glycerol ether-based epoxy resin, polyaniline, precipitated barium sulfate, talc, dispersant, defoamer and diluent are thoroughly mixed and dispersed evenly, and then mixed with anti-settling agent to obtain component A;

[0040] Mix the curing agent and diluent to obtain component B;

[0041] Component A and component B are mixed to obtain the anti-corrosion coating.

[0042] In some specific implementations, the dispersion operation is as follows: each component is added to a high-speed disperser and dispersed at a speed of 1000~1500 rpm for 15~45 min, then added to a sand mill and sand-milled for 1~3 hours, filtered with a 75~85 mesh filter, and the filtrate is retained.

[0043] This invention combines small-molecule tannic acid with epoxy resin to obtain a tannic acid-based epoxy resin. This substance retains the function of tannic acid forming chelates with rust, converting rust into dense chelates. Simultaneously, the tannic acid-based epoxy resin can form a high-density cross-linked coating with a curing agent. The tannic acid groups are tightly fixed within the cross-linked network structure by the epoxy structure, thus solving the problem of precipitation or loss of traditional small-molecule tannic acid and improving the long-term anti-corrosion performance of the coating. Experimental results show that the tannic acid-based epoxy resin provided by this invention, when used as an anti-corrosion coating, exhibits adhesion to the substrate exceeding 13 MPa and a neutral salt spray test duration of 4500 hours, demonstrating excellent anti-corrosion performance. Attached Figure Description

[0044] Figure 1 The photos show the anti-corrosion coating before the salt spray test and its adhesion in Example 2.

[0045] Figure 2 The images show the salt spray test results and adhesion of the anti-corrosion coating in Example 3.

[0046] Figure 3 Comparative Example 4: Photos of the anti-corrosion coating before salt spray testing and its adhesion.

[0047] Figure 4 The image shows photos and adhesion of the anti-corrosion coating after salt spray testing, as shown in Comparative Example 4. Detailed Implementation

[0048] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0049] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0050] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0051] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0052] Furthermore, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless explicitly stated otherwise, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately". Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0053] This invention provides a tannic acid-based epoxy resin obtained by reacting tannic acid, diol compounds, and epoxy compounds;

[0054] The molar ratio of tannic acid to the diol compound is 1:10~20;

[0055] The molar ratio of tannic acid to the epoxy compound is 1:100~200.

[0056] This invention combines small-molecule tannic acid and epoxy resin through a chemical reaction to obtain a novel tannic acid-based epoxy resin. This type of tannic acid-based epoxy resin retains the function of tannic acid forming chelates with rust, which can transform rust into a dense chelate, thus solving the problem of low surface treatment. In addition, the multiple epoxy structures in its structure can be cured with a curing agent to form a thermosetting, high-density cross-linked network polymer structure, which greatly improves the density of the paint film, hinders further corrosion by corrosive media, and the network structure firmly fixes the tannic acid structure to the metal substrate, so that it is not affected by the surrounding environment, ensuring the long-term effectiveness of the low-surface-treatment anti-corrosion coating.

[0057] The present invention is further illustrated below with reference to the embodiments. The scope of protection of the present invention is not limited to the following embodiments.

[0058] Example 1

[0059] (1) Under nitrogen protection, 24 g of sodium hydroxide and 75.1 g of tannic acid were dissolved in 176 g of deionized water and stirred at 100 °C for 1 h to form a clear liquid. Then 66.3 g of 3-chloro-1,2-propanediol was added and the reaction was allowed to proceed for 4 h. After the reaction was completed, 450 ml of toluene was added to extract the reaction liquid, and the organic phase was retained. 200 ml of deionized water was added for washing. This washing process was repeated 8 times. Anhydrous magnesium sulfate was added to the organic phase, and the mixture was left at room temperature for 48 hours. The mixture was then filtered and the filtrate was collected.

[0060] (2) Under nitrogen protection, 577.3 g of epichlorohydrin was added to the filtrate obtained in the first step, and the mixture was stirred at 80°C for 30 min. Then, tetrabutylammonium bromide, 38 g of sodium hydroxide and 180 g of deionized water were added, and the reaction was continued for 5 h. After the reaction was completed, 200 g of xylene was added, the aqueous phase was separated, and the organic phase was retained. 150 g of deionized water was added to the organic phase, and the mixture was stirred at room temperature for 20 min. The aqueous phase was separated, and the organic phase was retained. This process was repeated 8 times. Anhydrous magnesium sulfate was added to the organic phase, and the mixture was filtered to obtain the filtrate. The solvent was removed from the filtrate under negative pressure to obtain tannic acid-based epoxy resin.

[0061] Example 2

[0062] (1) 15g of tannic acid-based epoxy resin (prepared in Example 1), 20g of bisphenol A diglycidyl ether, 1.5g of polyaniline, 25g of precipitated barium sulfate, 15g of talc, 0.35g of Disperbyk-103, 0.2g of BYK-052 and 50g of xylene were mixed and added to a high-speed disperser and dispersed at 1000rpm for 30min. Then the mixture was added to a sand mill and sand milled for 1.5 hours. The mixture was filtered through an 80-mesh filter and the filtrate was added to a disperser. 1.8g of BYK RHEOBYK-420 was added and the mixture was stirred for 15min to obtain component A.

[0063] (2) Add 45g of polyamide curing agent 650 and 10g of xylene to a mixing tank and stir for 15min to obtain component B;

[0064] (3) Mix component A and component B at a weight ratio of 3:1 to obtain a low surface treatment anti-corrosion coating.

[0065] Example 3

[0066] (1) 32g of tannic acid-based epoxy resin (prepared in Example 1), 65g of hydrogenated bisphenol A diglycidyl ether, 15g of polyaniline, 55g of precipitated barium sulfate, 60g of talc, 3.1g of Disperbyk-108, 2.6g of BYK-088 and 85g of toluene were mixed and added to a high-speed disperser and dispersed at 1500rpm for 30min. Then the mixture was added to a sand mill and sand milled for 1.5 hours. The mixture was filtered through an 80-mesh filter and the filtrate was added to a disperser. 6.5g of BYK RHEOBYK-410 was added and the mixture was stirred for 15min to obtain component A.

[0067] (2) Add 42g of curing agent NX-2015 and 26g of toluene diluent to a mixing tank and stir for 15 minutes to obtain component B;

[0068] (3) Mix component A and component B at a weight ratio of 5:1 to obtain a low surface treatment anti-corrosion coating.

[0069] Example 4

[0070] (1) 26g of tannic acid-based epoxy resin (prepared in Example 1), 45g of bisphenol F diglycidyl ether, 3.5g of polyaniline, 32g of precipitated barium sulfate, 24g of talc, 1.2g of Disperbyk-130, 0.8g of BYK-1752, 40g of xylene and 10g of isopropanol were mixed and added to a high-speed disperser and dispersed at 1200rpm for 30min. Then the mixture was added to a sand mill and sand milled for 1.5 hours. The mixture was filtered through an 80-mesh filter and the filtrate was added to a disperser. 3.5g of BYK RHEOBYK-405 was added and the mixture was stirred for 15min to obtain component A.

[0071] (2) Add 35g of curing agent NX-2040 and 26g of butyl acetate to a mixing tank and stir for 15min to obtain component B;

[0072] (3) Mix component A and component B at a weight ratio of 4:1 to obtain a low surface treatment anti-corrosion coating.

[0073] Example 5

[0074] (1) 24g of tannic acid-based epoxy resin (prepared in Example 1), 49g of bisphenol S diglycidyl ether, 3.7g of polyaniline, 36g of precipitated barium sulfate, 43g of talc, 1.35g of Disperbyk-180, 1.4g of BYK-057 and 48g of xylene were mixed and added to a high-speed disperser and dispersed at 1200rpm for 30min. Then the mixture was added to a sand mill and sand milled for 1.5 hours. The mixture was filtered through an 80-mesh filter and the filtrate was added to a disperser. 5.1g of BYK RHEOBYK-425 was added and the mixture was stirred for 15min to obtain component A.

[0075] (2) Add 32g of NX-2045 and 28g of xylene to a mixing tank and stir for 15min to obtain component B;

[0076] (3) Mix component A and component B at a weight ratio of 3.5:1 to obtain a low surface treatment anti-corrosion coating.

[0077] Example 6

[0078] (1) 30.5g of tannic acid-based epoxy resin (prepared in Example 1), 27.3g of bisphenol F diglycidyl ether, 6.8g of polyaniline, 32.8g of precipitated barium sulfate, 45.8g of talc, 2.3g of Disperbyk-160, 1.35g of BYK-392, 41g of n-butanol and 18g of xylene were mixed and added to a high-speed disperser and dispersed at 1000rpm for 30min. Then the mixture was added to a sand mill and sand milled for 1.5 hours. The mixture was filtered through an 80-mesh filter and the filtrate was added to the disperser. 4.7g of BYK RHEOBYK-420 was added and the mixture was stirred for 15min to obtain component A.

[0079] (2) Add 34.6g of NX-2015 and 27g of xylene to a mixing tank and stir for 15min to obtain component B;

[0080] (3) Mix component A and component B at a weight ratio of 4.5:1 to obtain a low surface treatment anti-corrosion coating.

[0081] Comparative Example 1

[0082] Compared with Example 2, the difference is that in step (1), 15g of phytic acid is used instead of 15g of tannic acid-based epoxy resin, while the rest are the same.

[0083] Comparative Example 2

[0084] Compared with Example 2, the difference is that in step (1), 15g of tannic acid is used instead of 15g of tannic acid-based epoxy resin, while the rest are the same.

[0085] Comparative Example 3

[0086] Compared with Example 2, the difference is that polyaniline is not included in step (1), but everything else is the same.

[0087] Comparative Example 4

[0088] Compared with Example 2, the difference is that step (1) does not include tannic acid-based epoxy resin, but the rest is the same.

[0089] Experimental Example 1

[0090] The anti-corrosion coatings of Examples 2-6 and Comparative Examples 1-5 were brushed onto steel plates with surface treatment up to St2 or Sa2 grade, and their performance was tested after drying at room temperature for 7 days.

[0091] Coating adhesion test: The Positest AT-M20mm pull tester was used to test the coating adhesion according to the GB / T5210 pull test method. At least 3 points were tested on each sample, and the adhesion data was taken as the average value of the 3 points.

[0092] Impact resistance test of coating: Tested in accordance with GB / T 1732 standard.

[0093] Coating bending resistance test: Tested in accordance with GB / T 6742 standard.

[0094] Coating resistance to neutral salt spray test: An F-90 salt spray corrosion resistance tester (Qingdao Yitai Instrument Co., Ltd.) was used, and the test was conducted according to the national standard GB10125-2012. The concentration of sodium chloride solution in the salt spray chamber was 50 g / L, the pH value was 6.5~7.2, and the test temperature was fixed at (35±2)℃. Salt spray resistance performance requirements: no blistering, no cracking, no peeling, and no rust.

[0095] Figure 1 The image shows a photograph of the anti-corrosion coating formed by the coating prepared in Example 2 and the results of its adhesion test. Figure 2 The image shows a photograph of the anti-corrosion coating prepared in Example 3 after 4500 hours of salt spray testing and the adhesion test results. Figure 3 The image shows a photograph of the anti-corrosion coating formed by the coating prepared in Comparative Example 4 and the adhesion test results. Figure 4 The images shown are photographs of the anti-corrosion coating prepared in Comparative Example 4 after a 200-hour salt spray test and the adhesion test results. It is clearly evident that the anti-corrosion coatings prepared in Examples 2 and 3 exhibit superior integrity and adhesion compared to Comparative Example 4.

[0096] The performance test data of the anti-corrosion coatings of Examples 2-6 and Comparative Examples 1-4 are summarized in Table 1.

[0097] Table 1. Test data on the anti-corrosion coating performance of Examples 2-6 and Comparative Examples 1-4

[0098]

[0099] As shown in Table 1, Comparative Examples 1 and 2 used small-molecule tannic acid and phytic acid as the reactants with rust, and found that they could not achieve long-term corrosion protection. However, their corrosion protection performance was better than that of the example without polyaniline, because polyaniline itself can provide excellent long-term corrosion protection. Comparative Example 3 did not contain polyaniline, so its long-term corrosion protection performance was significantly affected. The results of Comparative Example 4 showed that it did not have a good surface treatment effect, had very low adhesion, and the loose coating allowed corrosive media to easily penetrate the coating, resulting in poor corrosion protection performance as polyaniline could not be demonstrated. This was because it lacked components that could react with rust.

[0100] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A tannic acid-based epoxy resin, characterized in that, It is obtained by reacting tannic acid, diol compounds, and epoxy compounds; The diol compounds have the following structures: ； a and b are independently selected from integers from 1 to 10; The epoxy compounds have the following structures: ； R is selected from C1~C1 of an epoxy-substituted compound. 10 Alkyl groups; The molar ratio of tannic acid to the diol compound is 1:10~20; The molar ratio of tannic acid to the epoxy compound is 1:100~200.

2. The tannic acid-based epoxy resin according to claim 1, characterized in that, It is obtained by reacting the reaction products of tannic acid and diols with epoxy compounds.

3. An anti-corrosion coating, characterized in that, Includes component A and component B; Component A comprises the following components by weight: The composition of the epoxy resin, tannic acid-based epoxy resin, glycerol ether-based epoxy resin, polyaniline, talc, dispersant, defoamer, anti-settling agent, and diluent as described in any one of claims 1 to 2 is as follows: 13 to 32 parts; 18 to 65 parts; 1.5 to 22 parts; talc, dispersant, defoamer, anti-settling agent, and diluent, 35 to 100 parts. Component B comprises the following components by weight: 28-50 parts curing agent and 18-40 parts diluent.

4. The anti-corrosion coating according to claim 3, characterized in that, The mass ratio of component A to component B is 3~5:

1.

5. The anti-corrosion coating according to claim 3, characterized in that, The curing agent is selected from at least one of polyamide curing agent 650, polyamide curing agent 651, NX-2015, NX-2040, NX-2041 and NX-2045.

6. The anti-corrosion coating according to claim 3, characterized in that, The glycerol ether-based epoxy resin is selected from at least one of bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl ether.

7. The anti-corrosion coating according to claim 3, characterized in that, The dispersant is selected from at least one of Disperbyk-103, Disperbyk-108, Disperbyk-115, Disperbyk-130, Disperbyk-111, Disperbyk-180, Disperbyk-160, Disperbyk-162, Disperbyk-164 and Disperbyk-182.

8. The anti-corrosion coating according to claim 3, characterized in that, The anti-settling agent is selected from at least one of BYK RHEOBYK-420, BYK RHEOBYK-410, BYK RHEOBYK-405, BYK RHEOBYK-425 and BYK RHEOBYK-430.

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