A graphene-based epoxy zinc-rich primer and a preparation method thereof

Abstract

The application provides a graphene-based epoxy zinc-rich primer and a preparation method thereof. The epoxy zinc-rich primer is composed of a resin component and a curing agent component. The resin component comprises an epoxy resin, zinc powder and an environmentally-friendly solvent. The curing agent component comprises an amine curing agent. The resin component further comprises a graphene dispersion slurry which is composed of graphene powder, a dispersant and a dispersion solvent. The dispersant is a block copolymer of polyvinylpyrrolidone-polyphenyl sulfonic acid-polyalkyl tertiary amine acrylic ester. The graphene dispersion slurry with high stability is added to the epoxy zinc-rich primer. The excellent electron migration capacity of graphene is utilized to uniformly distribute a conductive network in the coating, improve the utilization rate of zinc powder, enhance the cathode protection effect, and the shielding effect of the graphene sheet structure can prevent the penetration of corrosive media, so that a heavy-duty anticorrosive coating with excellent corrosion resistance, environmental protection and economy is finally obtained.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a graphene-based epoxy zinc-rich primer and its preparation method. Background Technology

[0002] Statistics show that approximately 20-40% of the world's annual metal production is corroded and rusted each year, resulting in over 100 million tons of scrapped metal and economic losses of about US$1 trillion. Since steel accounts for 95% of metal usage, and 70% of that is used in rust-prone atmospheres, corrosion protection of steel is of paramount importance. Steel structure corrosion protection is one of the most important application areas in the coatings industry, and epoxy zinc-rich primer is the most widely used type of anti-corrosion coating. Through the cathodic protection of zinc powder, it provides excellent rust prevention for steel substrates and has been widely used in shipbuilding, marine engineering, bridges, storage tanks, and large steel structures. However, to ensure its anti-corrosion performance, traditional epoxy zinc-rich primers typically contain no less than 70% zinc powder by dry film mass to form an effective conductive path, thereby achieving cathodic protection. But in practical applications, the formation of non-conductive oxidation products such as zinc oxide produced by corrosion can damage the conductive path, leading to cathodic protection failure, a significant decrease in anti-corrosion performance, waste of zinc resources, and environmental pollution.

[0003] To overcome the shortcomings of traditional zinc-rich epoxy primers, adding functional conductive fillers such as graphene is considered a potential solution to extend corrosion protection time and reduce zinc powder usage. Conductive fillers like graphene enhance the conductivity between zinc powder particles, improving the cathodic protection performance of zinc-rich coatings even after localized zinc oxidation. However, the highly inert surface of structurally complete graphene, with its extremely high specific surface area, is neither hydrophilic nor oleophilic, and exhibits extremely strong van der Waals forces between graphene sheets. This makes it prone to irreversible agglomeration during preparation and application, making it difficult to maintain stable dispersion in solution for extended periods. To improve the dispersibility of graphene, much research has focused on surface modification and the introduction of foreign molecules (such as loading nanoparticles, adding surfactants, introducing polymers, and doping with aromatic macromolecules). Some studies also utilize the electrostatic repulsion of in-plane or edge oxygen-containing functional groups in reduced graphene oxide to weaken interlayer van der Waals forces and achieve stable dispersion. According to reports, surfactants used to disperse graphene include sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, polyvinyl alcohol, sodium lignosulfonate, hexadecyltrimethylammonium bromide, DNA, sodium cholate, sodium polystyrene sulfonate, polyvinylpyrrolidone, silane coupling agents, titanate coupling agents, polyoxyethylene castor oil, etc. However, the graphene dispersions prepared by these dispersants have low concentrations and poor stability, making it difficult to meet the actual application requirements of anti-corrosion coatings.

[0004] Therefore, how to achieve long-term stable dispersion of graphene in epoxy zinc-rich primer anti-corrosion coatings, and reduce zinc powder usage and improve anti-corrosion performance, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] Based on the technical problems existing in the background art, this invention proposes a graphene-based epoxy zinc-rich primer and its preparation method. By adding highly stable graphene dispersion slurry to the epoxy zinc-rich primer, the excellent electron migration ability of graphene is utilized to uniformly distribute it in the coating to form a conductive network, thereby improving the utilization rate of zinc powder and enhancing its cathodic protection effect. At the same time, the graphene sheet structure can also play a shielding role, effectively preventing the penetration of corrosive media. This significantly improves the barrier and shielding effect of the coating, resulting in a heavy-duty anti-corrosion coating that combines excellent anti-corrosion performance, environmental protection and economy.

[0006] The present invention proposes a graphene-based epoxy zinc-rich primer, which is composed of a resin component and a curing agent component. The resin component includes epoxy resin, zinc powder and environmentally friendly solvent, and the curing agent component includes amine curing agent. The resin component further includes a graphene dispersion slurry, which is composed of graphene powder, a dispersant, and a dispersion solvent. The dispersant is a block copolymer of polyvinylpyrrolidone-polybenzenesulfonic acid-polyalkyl tertiary amino acrylate.

[0007] In this invention, the dispersant is a block polymer of polyvinylpyrrolidone-polybenzenesulfonic acid-polyalkyl tertiary amine acrylate. The anchoring sulfonic acid groups contained in the block structure of polybenzenesulfonic acid can be tightly adsorbed on the surface of graphene powder and form an electric double layer to generate electrostatic repulsion. The block structure of polyvinylpyrrolidone can act as a steric hindrance to resist the attraction between graphene powders, thereby improving the dispersion stability of graphene powder. The block structure of polyalkyl tertiary amine acrylate also generates steric hindrance to prevent mutual entanglement and extends in the dispersion system to form a bridging network distribution, which significantly enhances the growth orientation of graphene powder in two dimensions, thereby forming a stable suspension system. During the film formation process, it can ensure that the dispersed graphene is uniformly and stably distributed in the coating.

[0008] This invention utilizes a specific dispersant to bond and disperse graphene, significantly improving the dispersibility and stability of graphene in epoxy zinc-rich primers. The two-dimensional sheet-like structure of graphene is uniformly dispersed and layered within the epoxy zinc-rich primer, complementing the zinc powder in the coating to form barrier layers. This greatly delays the entry of corrosive agents such as oxygen molecules, water molecules, and chloride ions, resulting in a coating based on this graphene that exhibits excellent water resistance and salt spray resistance, thereby improving the overall anti-corrosion performance of the coating. Furthermore, due to the addition of graphene, the zinc powder content in the anti-corrosion coating can be further reduced, significantly lowering the coating cost.

[0009] Preferably, the dispersant has the following structural formula: x, y, and z each represent the degree of aggregation.

[0010] Preferably, the dispersant is obtained by polymerizing N-vinylpyrrolidone, 4-vinylbenzaldehyde and dimethylaminoethyl acrylate under RAFT reagent, followed by Schiff base condensation reaction of the resulting intermediate block polymer and p-aminobenzenesulfonic acid. The mass ratio of N-vinylpyrrolidone, 4-vinylbenzaldehyde and dimethylaminoethyl acrylate is 1:0.2-0.8:0.5-1.

[0011] In this invention, compared to simply adding polyvinylpyrrolidone or polybenzenesulfonic acid as a dispersant, although the latter can play a role in dispersing graphene to a certain extent, it cannot effectively adhere to the surface of the dispersed graphene particles as in this invention, thereby obtaining a highly stable graphene dispersion slurry.

[0012] Preferably, the graphene powder is gas-phase synthesized graphene with a particle size of 1-20 μm and a thickness of ≤15 nm; In the graphene dispersion slurry, the weight ratio of graphene powder, dispersant, and dispersion medium is 1-10:1-10:80-98.

[0013] Preferably, the graphene dispersion slurry is obtained by pre-dispersing graphene and a dispersant in a dispersion medium, and then grinding the resulting mixture.

[0014] Preferably, the resin component comprises, by weight: 20-35 parts epoxy resin, 25-45 parts zinc powder, 1-20 parts environmentally friendly solvent, and 10-25 parts graphene dispersion slurry; the curing agent component comprises, by weight: 10-30 parts curing agent.

[0015] Preferably, the epoxy resin is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, or organosilicon epoxy resin.

[0016] Preferably, the zinc powder is silane coupling agent modified and activated zinc powder, specifically obtained by coupling zinc powder with a silane coupling agent containing haloalkanes; The zinc powder is flake zinc powder with a particle size of 400-1500 mesh, and the silane coupling agent containing haloalkanes is 3-chloropropyltriethoxysilane or 3-chloropropyltrimethoxysilane.

[0017] In this invention, after grafting modification of zinc powder surface with silane coupling agent, a haloalkane functional group is formed on the zinc powder surface. This functional group can form a quaternary ammonium salt with the poly(dimethylaminoethyl acrylate) in the dispersant of the graphene dispersion slurry. On the one hand, through this chemical bonding reaction, the graphene sheets dispersed by the dispersant are adsorbed around the zinc powder, forming an effective electrical connection between the zinc powder particles, thereby significantly improving the anti-corrosion performance of the coating. On the other hand, this quaternary ammonium salt bonding method can form electrostatic repulsion, further improving the dispersibility of zinc powder and making the connection between zinc powder and epoxy resin more compact, further improving the anti-corrosion performance.

[0018] Preferably, the environmentally friendly solvent and the dispersing solvent are each independently at least one selected from n-butanol, butyl acetate, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, or ethanol.

[0019] Preferably, the resin component further comprises, by weight, 0.5-4 parts of additives; Preferably, the additives include at least one of defoamers, leveling agents, anti-settling agents, or wetting agents; Preferably, the defoamer is at least one of an organosilicon defoamer, a polyether defoamer, or a polyether-modified organosilicon defoamer; the leveling agent is at least one of a polyether-modified silicone oil, a modified polysiloxane, or an acrylic copolymer; the anti-settling agent is at least one of fumed silica, organobentonite, or a polyamide wax; and the wetting agent is at least one of a phosphate ester wetting agent or a polycarboxylic acid wetting agent.

[0020] Preferably, the amine curing agent is at least one of aliphatic polyamines, amide amines, polyamides, cashew nut shell powder, isophorone diamine, 4,4'-diaminodiphenylmethane, m-phenylenediamine, or m-xylene-α,α'-diamine.

[0021] This invention also proposes a method for preparing the above-mentioned graphene-based epoxy zinc-rich primer, comprising: After mixing the epoxy resin and graphene dispersion slurry in the resin component, stir and disperse at 1000-1500 rpm for 20-40 min. After heating to 40-60℃, slowly add zinc powder and environmentally friendly solvent, and then stir and disperse at 1500-2000 rpm for 60-120 min. Next, add the amine curing agent in the curing agent component, and stir and disperse at 300-600 rpm for 10-20 min to obtain the graphene-based epoxy zinc-rich primer.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In the epoxy zinc-rich primer of the present invention, a dispersant with a specific molecular structure is used to disperse and modify graphene, so that graphene can be stably and uniformly dispersed in the coating to form a dense "maze" physical barrier layer, which greatly extends the penetration path of corrosive media and significantly improves the physical shielding performance of the coating. At the same time, well dispersed graphene has excellent conductivity and can "bridge" between zinc powder particles, forming a more efficient and stable three-dimensional conductive network together with zinc powder. This network ensures the smooth flow of cathodic protection current, which greatly improves the utilization rate of zinc powder. Therefore, when achieving the same or even better anti-corrosion effect, the amount of zinc powder used in the present invention can be reduced to more than 70% of the zinc content of traditional zinc-rich paint. (2) The present invention also uses a silane coupling agent containing haloalkanes to modify zinc powder by coupling. On the one hand, the zinc powder modified by the silane coupling agent can be stably and uniformly dispersed in the coating. On the other hand, the active sites of haloalkanes are grafted on the surface of the zinc powder. As a "molecular bridge", it undergoes a "quaternary ammonium salt" reaction with the tertiary amine groups in the polyacrylate block of the dispersant anchored on the graphene surface. This forms an ionic teleclaw structure composed of polymer chains between the zinc powder particles and the graphene particles, which improves the isolated connection between the zinc powder particles inside the coating. At the same time, it also optimizes the conductive network, greatly improves the anti-corrosion performance of the coating, and enables the coating to form long-term protection. Attached Figure Description

[0023] Figure 1 The above is the 1H NMR spectrum of the block copolymer intermediate described in Example 1 of this invention; Figure 2 The image shows the infrared spectrum of the dispersant described in Example 1 of this invention. Detailed Implementation

[0024] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0025] Example 1 A graphene-based epoxy zinc-rich primer, comprising: a resin component and a curing agent component; The resin components include the following raw materials in parts by weight: 26 parts epoxy resin E-44, 16 parts graphene dispersion slurry, 35 parts flake zinc powder (600-1200 mesh), 1 part defoamer (BYK-066N), 1 part leveling agent (BYK-354), 0.5 parts anti-settling agent (fumed silica), 4 parts diethylene glycol dibutyl ether, and 8 parts dipropylene glycol methyl ether. The curing agent system comprises the following raw materials in parts by weight: 20 parts of polyamide 650 curing agent; The graphene dispersion slurry comprises graphene powder (average diameter 10 μm, thickness ≤ 15 nm), dispersant, and n-butanol in a weight ratio of 5:5:90. Specifically, the dispersant is added to n-butanol and stirred until uniformly dispersed. The mixture is then placed in a high-speed disperser, and graphene powder is added. The mixture is stirred and dispersed at 1500 rpm for 30 min. The resulting mixture is then transferred to a sand mill, and zirconia beads (particle size 1 mm, filling rate 70%) are added. The mixture is then ground at 1500 rpm for 120 min to obtain the graphene dispersion slurry. The dispersant is prepared by the following method: N-vinylpyrrolidone, 4-vinylbenzaldehyde, and dimethylaminoethyl acrylate are dissolved in 1,4-dioxane, and then 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid and azobisisobutyronitrile are added. The weight ratio of N-vinylpyrrolidone, 4-vinylbenzaldehyde, dimethylaminoethyl acrylate, 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropionic acid, and azobisisobutyronitrile is 1:0.5:0.75:0.05:0.02, and the mixture is stirred thoroughly. Then, under nitrogen protection, the temperature was raised to 70°C and the reaction was stirred for 12 hours. The resulting reaction solution was dialyzed in methanol for 24 hours using an 8000D dialysis bag, with the methanol being replaced every 4 hours. The solution was then precipitated with diethyl ether and dried to obtain a block copolymer intermediate. The block copolymer intermediate, p-aminobenzenesulfonic acid, and glacial acetic acid were dissolved in toluene at a mass ratio of 1:0.15:2. The solution was then heated to 100°C under nitrogen protection and stirred for 2 hours. After washing with methanol and diethyl ether sequentially, the solution was dried under vacuum to obtain the dispersant.

[0026] This embodiment also proposes a method for preparing a graphene-based epoxy zinc-rich primer, specifically including: adding epoxy resin E-44 and graphene dispersion slurry to a reaction vessel according to the weight parts of the raw materials in the resin component, stirring and dispersing at 1200 rpm for 30 min, raising the temperature to 50°C, and slowly adding flake zinc powder, defoamer, leveling agent, anti-settling agent, diethylene glycol dibutyl ether, and dipropylene glycol methyl ether under stirring conditions, continuing to stir and disperse at 1600 rpm for 90 min, then adding polyamide 650 curing agent to the reaction vessel according to the weight parts of the raw materials in the curing agent component, stirring and dispersing at 500 rpm for 15 min, thus obtaining the graphene-based epoxy zinc-rich primer.

[0027] Figure 1 The image shows the 1H NMR spectrum of the block copolymer intermediate described in this embodiment. The singlet peak at δ10.14 ppm is the elution peak of the aldehyde hydrogen atom on benzaldehyde; the multiplet peaks at δ7.96-7.53 ppm are the elution peaks of the benzene ring hydrogen atom; the multiplet peaks at δ4.28-3.89 ppm are the elution peaks of the alkyl hydrogen atom attached to the nitrogen atom on dimethylaminoethyl ester and pyrrolidone; and the multiplet peaks at δ3.34-0.76 ppm belong to the elution peaks of other alkyl hydrogen atom atom in the entire polymer chain.

[0028] Figure 2 The infrared spectrum of the dispersant described in this embodiment is shown, where 3400-3300 cm⁻¹ -1 The peak at 3100-2900 cm⁻¹ represents the stretching vibration of the OH group on the sulfonic acid group. -1 The peaks at 1650 cm⁻¹ represent the stretching vibrations of CH on the benzene ring and the -CH₂- stretching vibrations on pyrrole. -1 The peak of the stretching vibration at 1450 cm⁻¹ is the C=N peak. -1 The peak at 1400 cm⁻¹ represents the stretching vibration peak of CN on pyrrole. -1 The peak at this location represents the S=O asymmetric stretching vibration of the sulfonic acid group.

[0029] Example 2 A graphene-based epoxy zinc-rich primer, comprising: a resin component and a curing agent component; The resin components include the following raw materials in parts by weight: 20 parts epoxy resin E-20, 10 parts graphene dispersion slurry, 25 parts flake zinc powder (600-1200 mesh), 0.5 parts defoamer (BYK-051), 0.5 parts anti-settling agent (organic bentonite), 5 parts diethylene glycol dibutyl ether, and 5 parts dipropylene glycol methyl ether. The curing agent system comprises the following raw materials in parts by weight: 10 parts of polyamide 650 curing agent; The graphene dispersion slurry was prepared according to the method described in Example 1; This embodiment also proposes a method for preparing a graphene-based epoxy zinc-rich primer, specifically including: adding epoxy resin E-20 and graphene dispersion slurry to a reaction vessel according to the weight parts of the raw materials in the resin component, stirring and dispersing at 1000 rpm for 40 min, raising the temperature to 40°C, and slowly adding flake zinc powder, defoamer, anti-settling agent, diethylene glycol dibutyl ether, and dipropylene glycol methyl ether under stirring conditions, continuing to stir and disperse at 2000 rpm for 60 min, then adding polyamide 650 curing agent to the reaction vessel according to the weight parts of the raw materials in the curing agent component, stirring and dispersing at 600 rpm for 10 min, thus obtaining the graphene-based epoxy zinc-rich primer.

[0030] Example 3 A graphene-based epoxy zinc-rich primer, comprising: a resin component and a curing agent component; The resin component comprises the following raw materials in parts by weight: 35 parts epoxy resin E-44, 25 parts graphene dispersion slurry, 45 parts flake zinc powder (600-1200 mesh), 2 parts defoamer (BYK-066N), 1 part leveling agent (BYK-354), 1 part anti-settling agent (polyamide wax), 10 parts butyl acetate, and 10 parts dipropylene glycol methyl ether. The curing agent system comprises the following raw materials in parts by weight: 30 parts cashew phenol curing agent; The graphene dispersion slurry was prepared according to the method described in Example 1; This embodiment also proposes a method for preparing a graphene-based epoxy zinc-rich primer, specifically including: adding epoxy resin E-44 and graphene dispersion slurry to a reaction vessel according to the weight parts of the raw materials in the resin component, stirring and dispersing at 1500 rpm for 20 min, raising the temperature to 60°C, and slowly adding flake zinc powder, defoamer, leveling agent, anti-settling agent, butyl acetate, and dipropylene glycol methyl ether under stirring conditions, continuing to stir and disperse at 1500 rpm for 120 min, then adding cashew phenol curing agent to the reaction vessel according to the weight parts of the raw materials in the curing agent component, stirring and dispersing at 300 rpm for 20 min, thus obtaining the graphene-based epoxy zinc-rich primer.

[0031] Example 4 A graphene-based epoxy zinc-rich primer, comprising: a resin component and a curing agent component; The resin components include the following raw materials in parts by weight: 26 parts epoxy resin E-44, 16 parts graphene dispersion slurry, 35 parts silane coupling agent modified activated zinc powder, 1 part defoamer (BYK-066N), 1 part leveling agent (BYK-354), 0.5 parts anti-settling agent (fumed silica), 4 parts diethylene glycol dibutyl ether, and 8 parts dipropylene glycol methyl ether. The curing agent system comprises the following raw materials in parts by weight: 20 parts of polyamide 650 curing agent; The graphene dispersion slurry was prepared according to the method described in Example 1; the silane coupling agent modified activated zinc powder was prepared by the following method: 3-chloropropyltriethoxysilane was dissolved in a mixed solvent of ethanol and water (volume ratio of 9:1), the pH was adjusted to 5, and flake zinc powder (600-1200 mesh) was added under stirring. The mass ratio of 3-chloropropyltriethoxysilane to flake zinc powder was 1:30. The mixture was heated to 70°C and stirred for 2 hours. After filtration and drying, the silane coupling agent modified activated zinc powder was obtained. This embodiment also proposes a method for preparing a graphene-based epoxy zinc-rich primer, specifically including: adding epoxy resin E-44 and graphene dispersion slurry to a reaction vessel according to the weight parts of the raw materials in the resin component, stirring and dispersing at 1200 rpm for 30 min, raising the temperature to 50°C, and slowly adding silane coupling agent modified activated zinc powder, defoamer, leveling agent, anti-settling agent, diethylene glycol dibutyl ether, and dipropylene glycol methyl ether under stirring conditions, continuing to stir and disperse at 1600 rpm for 90 min, and then adding polyamide 650 curing agent to the reaction vessel according to the weight parts of the raw materials in the curing agent component, stirring and dispersing at 500 rpm for 15 min to obtain the graphene-based epoxy zinc-rich primer.

[0032] Comparative Example 1 A graphene-based epoxy zinc-rich primer, which is based on Example 1, except that the dispersant in the graphene dispersion slurry is sodium dodecylbenzenesulfonate.

[0033] Comparative Example 2 A graphene-based epoxy zinc-rich primer, which is based on Example 1, except that the dispersant in the graphene dispersion slurry is polyvinylpyrrolidone.

[0034] Comparative Example 3 A graphene-based epoxy zinc-rich primer, which is based on Example 1, except that the dispersant in the graphene dispersion slurry is selected as polyvinylpyrrolidone and sodium dodecylbenzenesulfonate in a weight ratio of 1:0.5.

[0035] Comparative Example 4 A graphene-based epoxy zinc-rich primer, which is based on Example 1, except that the dispersant in the graphene dispersion slurry is selected as the block copolymer intermediate.

[0036] Comparative Example 5 An epoxy zinc-rich primer based on graphene, which is described in Example 4, except that ethyl acrylate is used instead of dimethylaminoethyl acrylate as the dispersant in the graphene dispersion slurry during the preparation process.

[0037] Comparative Example 6 A graphene-based epoxy zinc-rich primer, which is based on Example 4, except that 3-aminopropyltriethoxysilane is used instead of 3-chloropropyltriethoxysilane in the preparation process of the silane coupling agent modified activated zinc powder.

[0038] The epoxy zinc-rich primers obtained in the examples and comparative examples were brushed onto the surface of Q235 steel plates and allowed to air dry at room temperature. The thickness of the coating was 50 μm. Performance tests were conducted according to the provisions of GB / T3668 2009 Zinc-Rich Primers, and the results are shown in Table 1.

[0039] The performance testing methods shall be conducted in accordance with the following standards: Adhesion was tested according to GB / T 5210 2006 "Paints and Varnishes - Pull-off Adhesion Test"; impact resistance was tested according to GB / T1732 1993 "Paint Film Impact Resistance"; salt spray resistance was tested according to GB1771 2007 "Paints and Varnishes - Determination of Neutral Salt Spray Resistance".

[0040] Table 1. Performance test results of graphene-based zinc-rich epoxy primers obtained in the examples and comparative examples.

[0041] As shown in Table 1, using a dispersant with a specific molecular structure to modify the dispersion of graphene can significantly improve the adhesion and long-term anti-corrosion performance of epoxy zinc-rich paint. Specifically, compared with the use of conventional dispersants such as sodium dodecyl sulfonate and polyvinylpyrrolidone in Comparative Examples 1-3, the adhesion and long-term anti-corrosion performance of the epoxy zinc-rich paint obtained by using a dispersant with a specific molecular structure to stably disperse graphene in Example 1 are significantly improved. In Comparative Example 4, the block copolymer intermediate is used directly as a dispersant. Due to the lack of benzenesulfonic acid groups in its molecular chain segments, the adhesion and long-term anti-corrosion performance of its epoxy zinc-rich paint are significantly insufficient. In Comparative Examples 5-6, the dispersant and silane coupling agent cannot form a "quaternary ammonium salt" reaction, so the goal of further optimizing the adhesion and long-term anti-corrosion performance of epoxy zinc-rich paint cannot be achieved.

[0042] 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 graphene-based epoxy zinc-rich primer, comprising a resin component and a curing agent component, wherein the resin component includes epoxy resin, zinc powder and environmentally friendly solvent, and the curing agent component includes an amine curing agent; Its features are, The resin component also includes a graphene dispersion slurry, which is composed of graphene powder, a dispersant, and a dispersion solvent; The dispersant is obtained by polymerizing N-vinylpyrrolidone, 4-vinylbenzaldehyde and dimethylaminoethyl acrylate under RAFT reagent, followed by Schiff base condensation reaction of the resulting intermediate product and p-aminobenzenesulfonic acid. The zinc powder is silane coupling agent modified and activated zinc powder, specifically obtained by coupling zinc powder with a silane coupling agent containing haloalkanes. After the zinc powder surface is modified by grafting with a silane coupling agent, a haloalkane functional group is formed on the zinc powder surface, which forms a quaternary ammonium salt with the tertiary amine group of the dispersant.

2. The graphene-based zinc-rich epoxy primer according to claim 1, characterized in that, The mass ratio of N-vinylpyrrolidone, 4-vinylbenzaldehyde and dimethylaminoethyl acrylate is 1:0.2-0.8:0.5-1.

3. The graphene-based zinc-rich epoxy primer according to claim 1, characterized in that, The graphene powder is gas-phase synthesized graphene with a particle size of 1-20 μm and a thickness of ≤15 nm. In the graphene dispersion slurry, the weight ratio of graphene powder, dispersant, and dispersion solvent is 1-10:1-10:80-98.

4. The graphene-based epoxy zinc-rich primer according to any one of claims 1-3, characterized in that, The resin component, by weight, includes: 20-35 parts epoxy resin, 25-45 parts zinc powder, 1-20 parts environmentally friendly solvent, and 10-25 parts graphene dispersion slurry; the curing agent component, by weight, includes: 10-30 parts curing agent.

5. The graphene-based zinc-rich epoxy primer according to claim 4, characterized in that, The epoxy resin is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, or organosilicon epoxy resin. The environmentally friendly solvent and the dispersing solvent are each independently at least one of n-butanol, butyl acetate, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, or ethanol.

6. The graphene-based zinc-rich epoxy primer according to claim 4, characterized in that, The zinc powder is flake-shaped zinc powder with a particle size of 400-1500 mesh; the silane coupling agent containing haloalkanes is 3-chloropropyltriethoxysilane or 3-chloropropyltrimethoxysilane.

7. The graphene-based zinc-rich epoxy primer according to claim 4, characterized in that, The resin component further includes, by weight, 0.5-4 parts of additives; The additives include at least one of defoamers, leveling agents, antisettling agents, or wetting agents; The defoamer is at least one of an organosilicon defoamer or a polyether defoamer; the leveling agent is at least one of a modified polysiloxane or an acrylic copolymer; the anti-settling agent is at least one of fumed silica, organobentonite, or polyamide wax; and the wetting agent is at least one of a phosphate ester wetting agent or a polycarboxylic acid wetting agent.

8. The graphene-based zinc-rich epoxy primer according to claim 4, characterized in that, The amine curing agent is at least one of polyamide, isophorone diamine, 4,4'-diaminodiphenylmethane, m-phenylenediamine, or m-xylene-α,α'-diamine.

9. A method for preparing a graphene-based epoxy zinc-rich primer according to any one of claims 1-8, characterized in that, include: After mixing the epoxy resin and graphene dispersion slurry in the resin component, stir and disperse at 1000-1500 rpm for 20-40 min. After heating to 40-60℃, slowly add zinc powder and environmentally friendly solvent, and then stir and disperse at 1500-2000 rpm for 60-120 min. Next, add the curing agent component and stir and disperse at 300-600 rpm for 10-20 min to obtain the graphene-based epoxy zinc-rich primer.

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