Vanillin-based curing agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of coatings, and discloses a vanillin-based curing agent as well as a preparation method and application thereof. The vanillin-based curing agent is prepared from the following raw materials: vanillin, an amino monomer and an acyl chloride monomer. According to the vanillin-based curing agent provided by the invention, the vanillin from biomass is taken as a raw material, the raw material is wide in source, green and environment-friendly, the vanillin is converted into the curing agent, the additional value of a biomass material is improved, the dependence on a petroleum-based ammonia curing agent is weakened, and the pressure of a petroleum-based high polymer material is relieved. The preparation method of the vanillin-based curing agent is simple in step, mild in reaction condition, high in operability and beneficial to large-scale preparation. A coating formed by the anticorrosive paint added with the vanillin-based curing agent has the characteristics of corrosion resistance, low dielectric constant and dielectric loss and excellent antibacterial property, has a strong protection effect on metal, and can prolong the service life of the metal.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a vanillin-based curing agent and a preparation method and application thereof. Background Art

[0002] Applying an organic coating on the metal surface is an effective means to protect the metal from corrosion. Resin is a necessary component in the coating, and epoxy resin is used more. Epoxy resin has excellent thermal stability, chemical resistance, insulation, good adhesion, good wear resistance, and high hardness. However, epoxy resin itself will not solidify. Only by adding a curing agent and performing a curing reaction under certain conditions to form a three-dimensional network structure can it show excellent performance. Existing epoxy resin curing agents are mostly derived from petroleum-based products, which is not conducive to sustainable development. Conventional amine curing agents contain active hydrogen. Curing epoxy resin will produce more polar hydroxyl groups, resulting in a higher dielectric constant of the coating, which limits the application of epoxy coatings in electronic products. Summary of the invention

[0003] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, one of the objects of the present invention is to provide a vanillin-based curing agent; the second object of the present invention is to provide a method for preparing the vanillin-based curing agent; the third object of the present invention is to provide an anticorrosive coating; the fourth object of the present invention is to provide a coating; the fifth object of the present invention is to provide an application of a vanillin-based curing agent or an anticorrosive coating.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] The first aspect of the present invention provides a vanillin-based curing agent, comprising the following preparation raw materials: vanillin, amino monomer, and acyl chloride monomer.

[0006] Preferably, the amino monomer includes at least one of aliphatic amines, alicyclic amines, aromatic amines, and polyamides; further preferably, the amino monomer includes at least one of diethylenetriamine, triethylenetetramine, 1,3-cyclohexanedimethylamine, isophoronediamine, meta-phenylenediamine, meta-phenylenediamine, diaminodiphenylmethane, polyamide-6, and polyamide-66.

[0007] Preferably, the acyl chloride monomer includes at least one of benzoyl chloride, dodecyl chloride, propionyl chloride, palmitoyl chloride, octanoyl chloride, terephthaloyl chloride, acryloyl chloride and stearoyl chloride.

[0008] Preferably, the vanillin-based curing agent comprises the following raw materials, measured in parts by mass: 0.1-20 parts of vanillin, 0.1-40 parts of acyl chloride monomer, 0.1-30 parts of amino monomer, 0.1-30 parts of neutralizer, and 0.1-50 parts of alkali solution; further preferably, the vanillin-based curing agent comprises the following raw materials, measured in parts by mass: 10-20 parts of vanillin, 20-30 parts of acyl chloride monomer, 2-10 parts of amino monomer, 15-25 parts of neutralizer, and 0.1-50 parts of alkali solution.

[0009] Preferably, the neutralizing agent includes at least one of an organic base, an alkali metal hydroxide, an alkali metal carbonate, and an alkali metal bicarbonate; further preferably, the neutralizing agent includes at least one of triethylamine, sodium hydroxide, potassium hydroxide, sodium bicarbonate, and sodium carbonate.

[0010] Preferably, the alkali source of the alkali solution includes at least one of alkali metal hydroxides, alkali metal carbonates, and alkali metal bicarbonates; further preferably, the alkali source of the alkali solution includes at least one of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, and potassium bicarbonate.

[0011] The second aspect of the present invention provides a method for preparing the vanillin-based curing agent according to the first aspect of the present invention, comprising the following steps:

[0012] S1, dissolving vanillin and a neutralizing agent, adding an acyl chloride monomer, reacting, and collecting a solid product;

[0013] S2, dissolving the solid product, adding dropwise to an alkali solution, collecting the oil phase, and obtaining modified vanillin with an active ester structure;

[0014] S3, dissolving the modified vanillin with the active ester structure, adding an amino monomer, reacting, and obtaining the vanillin-based curing agent.

[0015] Preferably, in step S1, the vanillin and the neutralizing agent are dissolved in a first solvent; the first solvent comprises at least one of tetrahydrofuran, chloroform, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, acetone and ethanol.

[0016] Preferably, in step S1, the solid-liquid ratio of the total mass of the vanillin and the neutralizer to the first solvent is 1 g:(2-5) mL; further preferably, the solid-liquid ratio of the total mass of the vanillin and the neutralizer to the first solvent is 1 g:(2-4) mL.

[0017] Preferably, in step S1, the dissolution process of the vanillin and the neutralizing agent is assisted by ultrasound; the ultrasound time is 10-50 min.

[0018] Preferably, in step S1, the reaction temperature is -5 to 30°C; and the reaction time is 10 to 72 hours.

[0019] Preferably, in step S1, after the reaction is completed, the first solvent is removed and the solid product is collected.

[0020] Preferably, in step S2, the solid product is dissolved in a second solvent, and the second solvent comprises at least one of ethyl acetate, dichloromethane, chloroform and toluene.

[0021] Preferably, in step S2, the solid-liquid ratio of the solid product to the second solvent is 1 g:(2-2000) mL.

[0022] Preferably, in the step S2, after collecting the oil phase, the steps of washing with deionized water and drying are also included.

[0023] Specifically, in step S2, after the solid product is dissolved, an alkali solution is added dropwise, so that the unreacted acyl chloride can be fully hydrolyzed and the generated hydrochloric acid and sodium bicarbonate can fully react.

[0024] Preferably, in step S3, the modified vanillin with an active ester structure is dissolved in a third solvent; the third solvent comprises at least one of ethanol, methanol, tetrahydrofuran, toluene and dimethyl sulfoxide.

[0025] Preferably, in step S3, the solid-liquid ratio of the modified vanillin with an active ester structure to the third solvent is 1 g:(8-12) mL; further preferably, the solid-liquid ratio of the modified vanillin with an active ester structure to the third solvent is 1 g:(9-11) mL.

[0026] Preferably, in step S3, the reaction temperature is 30-80°C; further preferably, the reaction temperature is 30-50°C.

[0027] Preferably, in step S3, the reaction time is 6-48 h; further preferably, the reaction time is 6-10 h.

[0028] Preferably, in step S3, after the reaction is completed, the steps of washing the product with a fourth solvent, filtering and drying are also included.

[0029] Preferably, the fourth solvent includes at least one of ethanol, methanol, acetone, toluene and butanone.

[0030] The third aspect of the present invention provides an anti-corrosion coating, which comprises the following raw materials, measured by mass: 0.01-10 parts of the vanillin-based curing agent described in the first aspect of the present invention, 0.01-10 parts of an amino monomer, and 0.01-50 parts of an epoxy resin.

[0031] Preferably, in the anti-corrosion coating, the molar ratio of the amino monomer to the vanillin-based curing agent is (2-9):1; further preferably, the molar ratio of the amino monomer to the vanillin-based curing agent is (2-4):1.

[0032] Preferably, the amino monomer includes at least one of aliphatic amine, alicyclic amine, aromatic amine and polyamide.

[0033] Preferably, the epoxy resin includes at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester epoxy resin, and alicyclic epoxy resin.

[0034] Preferably, the anti-corrosion coating further comprises the following preparation raw materials, measured in parts by mass: 0.01-30 parts of solvent and 0.0001-5 parts of auxiliary agent.

[0035] Preferably, the solvent includes at least one of dichloromethane, toluene, tetrahydrofuran, acetone, chloroform and ethanol.

[0036] Preferably, the auxiliary agent includes at least one of a diluent, a accelerator, a curing agent, and a catalyst; further preferably, the catalyst includes at least one of triethylamine, 4-dimethylaminopyridine, 2-methylimidazole, boron trifluoride, benzyldimethylamine, and 2-ethyl-4-methylimidazole.

[0037] Preferably, the method for preparing the anti-corrosion coating comprises the following steps:

[0038] The anti-corrosion coating is obtained by mixing a vanillin-based curing agent, an amino monomer, an auxiliary agent, an epoxy resin and a solvent.

[0039] The fourth aspect of the present invention provides a coating formed by the anti-corrosion coating described in the third aspect of the present invention.

[0040] Preferably, during the coating formation process, the curing temperature of the anti-corrosion coating is 100-200°C; further preferably, the curing temperature of the anti-corrosion coating is 100-180°C.

[0041] Preferably, during the coating formation process, the curing time of the anti-corrosion coating is 1 to 15 hours; further preferably, the curing time of the anti-corrosion coating is 2 to 10 hours.

[0042] The fifth aspect of the present invention provides the use of the vanillin-based curing agent described in the first aspect of the present invention, or the anti-corrosion coating described in the third aspect in the anti-corrosion of the surface of metal products.

[0043] Preferably, the metal products include marine engineering facilities, electronic devices, ships, cars, and airplanes.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1) The vanillin-based curing agent provided by the present invention uses vanillin from biomass as a raw material, which has a wide source of raw materials and is green and environmentally friendly. Vanillin is converted into a curing agent, which increases the added value of biomass materials, reduces dependence on petroleum-based ammonia curing agents, and alleviates the pressure on petroleum-based polymer materials;

[0046] 2) The method for preparing the vanillin-based curing agent provided by the present invention has simple steps, mild reaction conditions, strong operability, and is conducive to large-scale production;

[0047] 3) The anti-corrosion coating provided by the present invention uses a vanillin-based curing agent containing an active ester structure to replace part of the amino curing agent to cure the epoxy resin, which can reduce the hydroxyl content in the coating and reduce the dielectric constant and dielectric loss of the coating;

[0048] 4) The coating provided by the present invention has a dense three-dimensional network structure, has the characteristics of corrosion resistance, low dielectric constant and dielectric loss, and excellent antibacterial performance, has a strong protective effect on metals, and can extend the service life of metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The reaction scheme for preparing the vanillin curing agent of the present invention is as follows;

[0050] Figure 2 The reaction scheme of the vanillin curing agent of the present invention for curing epoxy resin;

[0051] Figure 3 The infrared spectra of the vanillin, the modified vanillin containing an active ester structure and the vanillin-based curing agent in Example 1;

[0052] Figure 4 The dielectric constant results of the coatings formed by the coatings in Examples 2-4 and Comparative Example 1;

[0053] Figure 5 The dielectric loss results of the coatings formed by the coatings in Examples 2-4 and Comparative Example 1;

[0054] Figure 6 The electrochemical performance test results of the coatings formed by the coatings in Examples 2-4 and Comparative Example 1;

[0055] Figure 7 This is a diagram showing the antibacterial effect of the coating formed by the coating in Examples 2-4 and Comparative Example 1 on Staphylococcus aureus. DETAILED DESCRIPTION

[0056] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0057] Figure 1 The reaction scheme for preparing the vanillin curing agent of the present invention is as follows: Figure 1 It can be seen that the present invention first prepares modified vanillin (VAE) containing an active ester structure based on the esterification reaction between the acyl chloride group on the acyl chloride monomer and the hydroxyl group on vanillin; and then prepares the vanillin-based curing agent (VAEI) based on the amine-aldehyde condensation reaction between the amino group on the amino monomer and the aldehyde group on vanillin.

[0058] Figure 2 The reaction scheme of curing epoxy resin with the vanillin curing agent of the present invention is shown in FIG. Figure 2 It can be seen that the present invention utilizes the ring-opening reaction of the active ester group on the vanillin-based curing agent, the amino group on the amino monomer and the epoxy group on the epoxy resin to prepare the anti-corrosion coating.

[0059] The following will be combined Figure 1 and Figure 2 The preparation process of vanillin curing agent and anticorrosive coating is described:

[0060] Example 1

[0061] In this embodiment, a vanillin-based curing agent is prepared by the following steps:

[0062] S1. Add 15.20 g of vanillin, 20.20 g of triethylamine and 100.00 mL of tetrahydrofuran into a flask, dissolve under ultrasonication for 30 min, slowly drop 23.47 g of benzoyl chloride into the flask, react at room temperature for 48 h, remove tetrahydrofuran, and collect the solid product;

[0063] S2, adding 1-10 mL of ethyl acetate to dissolve the solid product, and adding it dropwise into a saturated sodium bicarbonate aqueous solution, collecting the oil phase, washing it twice with deionized water, and drying it to obtain modified vanillin containing an active ester structure;

[0064] S3. Add 10.00 g of modified vanillin containing an active ester structure and 100.00 mL of anhydrous ethanol into a flask, add 3.87 g of diaminodiphenylmethane, and react at 45°C for 8 hours. After the reaction, filter the mixture and wash it with anhydrous ethanol, dry the precipitate, and obtain a vanillin-based curing agent.

[0065] Example 2

[0066] This embodiment prepares an anti-corrosion coating, and the steps are as follows:

[0067] 0.128 g of vanillin-based curing agent and 0.455 g of diaminodiphenylmethane were dissolved in 0.8 g of dichloromethane, wherein the molar ratio of diaminodiphenylmethane to the vanillin-based curing agent was 9:1, and then 2 g of aliphatic glycidyl ether epoxy resin was added to obtain an anti-corrosion coating.

[0068] Example 3

[0069] This embodiment prepares an anti-corrosion coating, and the steps are as follows:

[0070] 0.256 g of vanillin-based curing agent and 0.40 g of diaminodiphenylmethane were dissolved in 1.0 g of dichloromethane, wherein the molar ratio of diaminodiphenylmethane to the vanillin-based curing agent was 8:2, and then 2 g of aliphatic glycidyl ether epoxy resin was added to obtain an anti-corrosion coating.

[0071] Example 4

[0072] This embodiment prepares an anti-corrosion coating, and the steps are as follows:

[0073] 0.384 g of vanillin-based curing agent and 0.353 g of diaminodiphenylmethane were dissolved in 1.0 g of dichloromethane, wherein the molar ratio of diaminodiphenylmethane to the vanillin-based curing agent was 7:3, and then 2 g of aliphatic glycidyl ether epoxy resin was added to obtain an anti-corrosion coating.

[0074] Comparative Example 1

[0075] This comparative example prepares an anticorrosive coating, which differs from Example 1 in that no vanillin-based curing agent is added, and the steps are as follows:

[0076] 0.445 g of diaminodiphenylmethane was dissolved in 0.8 g of dichloromethane, and then 2 g of aliphatic glycidyl ether epoxy resin was added to obtain an anticorrosive coating.

[0077] Characterization and performance testing

[0078] 1. The vanillin, modified vanillin containing an active ester structure and vanillin-based curing agent in Example 1 were characterized by infrared spectroscopy:

[0079] The characteristic functional groups of the samples were characterized by using a German Nicolet iS10 Fourier transform infrared spectrometer. Figure 3 is the infrared spectra of the vanillin, the modified vanillin containing an active ester structure and the vanillin-based curing agent in Example 1. Figure 3It can be seen that vanillin is first modified with acyl chloride monomer to obtain the intermediate product modified vanillin (VAE) containing an active ester structure. The main functional group of vanillin is detected on VAE, at 3145 cm -1 No hydroxyl characteristic peak was detected nearby, but at 1737 cm -1 A new characteristic peak of ester functional group appeared at 1668cm, indicating that this step mainly utilized the esterification reaction between the acyl chloride group of the acyl chloride monomer and the hydroxyl group of vanillin. The modified vanillin containing active ester structure was then modified by amino monomer, and the main characteristic peak of VAE was detected on the vanillin-based curing agent (VAEI). However, the peak at 1668cm -1 The characteristic peak of aldehyde group at 1580cm -1 and 1340cm -1 The characteristic peaks of C=N and CN were detected at , indicating that this step mainly utilized the amine-aldehyde condensation reaction between the amino group of the amino monomer and the aldehyde group of vanillin, and also indicating that the vanillin-based curing agent (VAEI) in Example 1 was successfully prepared.

[0080] 2. Coating performance test:

[0081] 1) Preparation of coating: The anti-corrosion coatings prepared in Examples 2-4 and Comparative Example 1 were spread on the surface of the steel plate using a coater, first placed in an oven at 60°C for 20 min to remove the solvent, and then placed in ovens at 100°C, 130°C, 160°C and 180°C for deep curing for 2h, 3h, 2h and 2h, respectively, to obtain coatings.

[0082] 2) Electrochemical test: The electrochemical impedance spectroscopy (EIS) of the coating was tested using an electrochemical workstation (CHI-660E). During the test, the corrosive medium was 3.5 wt% salt water, the Ag / AgCl electrode was used as the reference electrode, and the platinum plate was used as the counter electrode.

[0083] 3) Antibacterial test: Use sterile PBS buffer to dilute the Staphylococcus aureus bacterial solution to 10 6 CFU / mL, then add 5mL of diluted bacterial solution to the sterilized anticorrosive coating sample and mix evenly (the final concentration of the sample is 1.28mg / mL). Add an equal amount of bacterial solution to a blank bacterial culture tube as a control group. Incubate in a constant temperature oscillator (37°C) for 6h. After incubation, dilute the bacterial solution 10 times continuously with sterile PBS buffer, evenly apply 100μL of the diluted solution on the LB solid culture medium, and place it in a 37°C constant temperature incubator for 18h. Finally, take it out and take a picture, and record the number of colonies.

[0084] 4) Dielectric property test: The dielectric properties of the samples were measured on a dielectric meter (Agilent 4294A) at a temperature of 25° C. The sample size was 10 mm×10 mm×1 mm.

[0085] Table 1 below shows the performance test results of the coatings formed by the anti-corrosion coatings prepared in Examples 2-4 and Comparative Example 1.

[0086] Table 1 Performance test results of the coating formed by the anticorrosive coatings prepared in Examples 2-4 and Comparative Example 1

[0087]

[0088] As shown in Table 1, the coating in Comparative Example 1 does not contain a vanillin-based curing agent. Although diaminodiphenylmethane can provide a certain curing effect, the dielectric constant of the formed coating at 10 MHz is relatively high, which is 4.16. The antibacterial rate against Staphylococcus aureus is 4.8%. The impedance modulus of the coating after immersion in salt water for 150 days is 3.16×10 7 Ω·cm 2 . In Examples 2-4, vanillin-based curing agents were added to the anti-corrosion coatings, and the dielectric constant of the formed coatings at 10 MHz was 3.64-3.72. Compared with Comparative Example 1, the dielectric constant of the coating at 10 MHz was reduced. It can be seen that adding the vanillin-based curing agent provided by the present invention to the coating can effectively reduce the dielectric constant of the coating, and as the amount of vanillin-based curing agent in the coating increases, the dielectric constant of the coating gradually decreases. This is mainly because the use of the vanillin-based curing agent reduces the hydroxyl content generated in the epoxy resin curing process, indicating that the vanillin-based curing agent and anti-corrosion coating provided by the present invention can be used for metal surface corrosion protection of electronic products.

[0089] Figure 4 The dielectric constant results of the coatings formed by the coatings in Examples 2-4 and Comparative Example 1 are: Figure 5 The dielectric loss results of the coatings formed by the coatings in Examples 2-4 and Comparative Example 1 are as follows: Figure 4 and Figure 5 It can be seen that the dielectric constant and dielectric loss of the coatings formed by the anticorrosive coatings in Examples 2-4 and Comparative Example 1 show the same change trend, the dielectric constant decreases with the increase of frequency, and the dielectric loss increases with the increase of frequency. The dielectric constant and dielectric loss of the coating in Comparative Example 1 are the highest. For the coatings formed by the coatings in Examples 2-4, the dielectric constant and dielectric loss of the coatings decrease with the increase of the content of the vanillin-based curing agent in the coatings, indicating that the introduction of vanillin containing an active ester structure into the resin can improve the dielectric properties of the coating to a certain extent, and its properties are adjustable.

[0090] The impedance modulus of the coating formed by the anticorrosive coating in Example 2-4 after being immersed in salt water for 150 days is 5.01×107 -1.0×10 9 Ω·cm 2 , compared with comparative example 1, the impedance modulus increases. Figure 6 The electrochemical performance test results of the coatings formed by the coatings in Examples 2-4 and Comparative Example 1 are as follows: Figure 6 (a) is the electrochemical performance test result of the coating formed by the coating of Comparative Example 1, Figure 6 (b) is the electrochemical performance test result of the coating formed by the coating of Example 2, Figure 6 (c) is the electrochemical performance test result of the coating formed by the coating of Example 3, Figure 6 (d) is the electrochemical performance test result of the coating formed by the coating of Example 4. Figure 6 It can be seen that as the immersion time of the coating in salt water increases, the impedance modulus value of the coating shows a downward trend, indicating that the anti-corrosion performance of the coating weakens with the increase of the immersion time. Among them, the impedance modulus value of the coating formed by the coating in Comparative Example 1 is the lowest, indicating that its anti-corrosion performance is the worst, and the impedance modulus of the coating formed by the coating in Examples 2-4 is higher than that in Comparative Example 1, indicating that adding a vanillin-based curing agent to the coating can improve the anti-corrosion performance of the coating, and as the content of the vanillin-based curing agent in the coating increases, the anti-corrosion performance of the coating gradually increases.

[0091] The antibacterial rate of the coating formed by the coating in Examples 2-4 against Staphylococcus aureus is 5.7-19.6%. Compared with Comparative Example 1, the antibacterial rate of the coating against Staphylococcus aureus is significantly increased, indicating that the introduction of vanillin-based curing agent into the coating can improve the antibacterial performance of the coating against Staphylococcus aureus, and as the amount of vanillin-based curing agent in the coating increases, the antibacterial performance of the coating gradually increases. Figure 7 The antibacterial effect of the coating formed by the coating in Examples 2-4 and Comparative Example 1 on Staphylococcus aureus is shown, wherein: Figure 7 (a) is the Staphylococcus aureus control group, Figure 7 (b) is the antibacterial effect of the coating formed by the coating of Comparative Example 1 on Staphylococcus aureus, Figure 7 (c) is the antibacterial effect of the coating formed by the coating of Example 2 on Staphylococcus aureus, Figure 7 (d) is the antibacterial effect of the coating formed by the coating of Example 3 on Staphylococcus aureus, Figure 7 (e) is the antibacterial effect of the coating formed by the coating of Example 4 on Staphylococcus aureus, Figure 7 It can be seen that in Examples 2-4, vanillin-based curing agents were added to the coatings. After the culture was completed, the number of colonies on the culture medium decreased, indicating that the introduction of vanillin-based curing agents into the coatings enhanced the antibacterial ability of the imine groups on the coatings against Staphylococcus aureus, and the antibacterial ability was enhanced with the increase of the content of vanillin-based curing agents.

[0092] The present invention uses vanillin as a main raw material to prepare a vanillin-based curing agent. Vanillin, as a biomass material, has the characteristics of wide source, renewable, environmental protection, etc., and also has active sites such as hydroxyl, aldehyde and methoxy groups on the surface. The present invention is modified so that the vanillin-based curing agent contains active ester and imine groups, which is conducive to the curing of epoxy resin by the vanillin-based curing agent, and gives the cured coating anticorrosive, antibacterial and low dielectric properties, so that the coating can be applied to electronic products, enhance the protective effect on metals, and meet the coating requirements of metal products such as marine engineering facilities, electronic devices, ships, automobiles, airplanes, etc.

Claims

1. A vanillin-based curing agent, characterized in that The invention comprises the following preparation raw materials: vanillin, amino monomer and acyl chloride monomer.

2. The vanillin-based curing agent according to claim 1, characterized in that The amino monomer includes at least one of aliphatic amines, alicyclic amines, aromatic amines, and polyamides; And / or, the acyl chloride monomer includes at least one of benzoyl chloride, dodecyl chloride, propionyl chloride, palmitoyl chloride, octanoyl chloride, terephthaloyl chloride, acryloyl chloride and stearoyl chloride.

3. The vanillin-based curing agent according to claim 1 or 2, characterized in that The vanillin-based curing agent comprises the following raw materials by weight: 0.1-20 parts of vanillin, 0.1-40 parts of acyl chloride monomer, 0.1-30 parts of amino monomer, 0.1-30 parts of neutralizer, and 0.1-50 parts of alkali solution.

4. The method for preparing the vanillin-based curing agent according to claim 3, characterized in that: The following steps are involved: S1, dissolving vanillin and a neutralizing agent, adding an acyl chloride monomer, reacting, and collecting a solid product; S2, dissolving the solid product, adding dropwise to an alkaline solution, collecting the oil phase, and obtaining modified vanillin with an active ester structure; S3, dissolving the modified vanillin with the active ester structure, adding an amino monomer, reacting, and obtaining the vanillin-based curing agent.

5. The preparation method according to claim 4, characterized in that: In the step S1, the reaction temperature is -5 to 30°C; The reaction time is 10-72h.

6. The preparation method according to claim 4, characterized in that: In step S3, the reaction temperature is 30-80°C; The reaction time is 6-48h.

7. An anti-corrosion coating, characterized in that: The preparation method comprises the following raw materials, in parts by mass: 0.01-10 parts of the vanillin-based curing agent according to any one of claims 1 to 3, 0.01-10 parts of the amino monomer, and 0.01-50 parts of the epoxy resin.

8. A coating, characterized in that The invention is formed by the anti-corrosion coating according to claim 7.

9. The coating according to claim 8, characterized in that During the coating formation process, the curing temperature of the anti-corrosion coating is 100 to 200° C. and the curing time is 1 to 15 hours.

10. Use of the vanillin-based curing agent according to any one of claims 1 to 3, or the anti-corrosion coating according to claim 7 in the anti-corrosion of metal product surfaces.

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