High-insulation high-corrosion-resistant graphene epoxy functional coating and preparation method thereof

Abstract

The application discloses a kind of high insulation high anticorrosion graphene epoxy functional coating and preparation method thereof.The application is by graphene oxide and silane coupling agent, silicon source precursor and cage polysilsesquioxane are carried out in situ hydrolysis condensation reaction under alkaline condition, the reactive composite insulating shell including silica network and polysilsesquioxane structure is constructed on graphene oxide surface;The obtained reactive composite insulating shell graphene is added in epoxy resin base material with the dispersion body of hexagonal boron nitride treated by high-speed dispersion coupling ultrasonic, after high-speed shearing dispersion, grinding and mixing with amine curing agent, high insulation high anticorrosion graphene epoxy functional coating is prepared.The application is by composite insulating shell coating to eliminate the risk of graphene conduction and introduce reactive group, simultaneously, synergistic hexagonal boron nitride forms multistage insulating shielding network, so that coating has excellent electrical insulation, corrosion resistance and adhesion, and application prospect is wide.

Description

Technical Field

[0001] This invention relates to the field of advanced petrochemical new materials technology, and in particular to a high-insulation and high-corrosion-resistant graphene epoxy functional coating and its preparation method. Background Technology

[0002] Currently, epoxy resins are widely used in the field of protective coatings for metal substrates due to their strong adhesion, good mechanical properties, and resistance to chemical corrosion. With increasingly harsh service environments in marine engineering, power equipment, rail transportation, and chemical facilities, functional coatings that combine high corrosion resistance and high insulation performance are attracting more and more attention. Graphene and its derivatives, due to their high aspect ratio and excellent shielding properties, are considered ideal nanofillers for improving the density and corrosion resistance of epoxy coatings. Therefore, graphene / epoxy composite anti-corrosion coatings have become a current research hotspot.

[0003] However, the application of graphene in epoxy systems in current technologies still has significant shortcomings. On the one hand, graphene is prone to agglomeration, resulting in poor dispersibility and interfacial compatibility in the resin, making it difficult to stably exert a shielding effect. On the other hand, graphene itself has high conductivity; if local conductive pathways are formed in the coating, it will not only reduce the coating's insulation performance but may also induce galvanic corrosion, thus affecting the long-term protective effect. In addition, existing solutions mostly focus on improving single anti-corrosion performance, and are still insufficient in synergistically addressing insulation, corrosion resistance, and system stability. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a high-insulation, high-corrosion-resistant graphene epoxy functional coating and its preparation method. By constructing a reactive composite insulating shell on the graphene surface and introducing insulating synergistic fillers such as hexagonal boron nitride, the graphene maintains its excellent shielding and barrier properties while reducing the risk of conductivity. Simultaneously, the active groups of the shell enhance the interfacial bonding between the coating and the epoxy resin network, thereby improving the dispersion stability, density, insulation, and corrosion resistance of the coating, achieving a synergistic unity of high insulation and high corrosion resistance.

[0005] This invention can be achieved through the following technical solutions: A method for preparing a high-insulation, high-corrosion-resistant graphene epoxy functional coating includes the following steps: Step 1: Add graphene oxide to an alcohol / water mixed solvent and disperse it by ultrasonication to obtain a graphene oxide dispersion. Then add silane coupling agent, silicon source precursor and cage-type polysilsesquioxane. Under alkaline conditions, carry out in-situ hydrolysis and condensation reaction to form a composite insulating shell containing a silica network and a polysilsesquioxane structure on the surface of graphene oxide, and obtain a reactive composite insulating shell graphene slurry. Step 2: Add hexagonal boron nitride to an alcohol solvent, first disperse it at high speed at 1000-5000 rpm for 10-60 min, then place it under ultrasonic frequency of 20-60 kHz and ultrasonic power of 200-1000 W for 10-90 min to obtain a hexagonal boron nitride dispersion; at the same time, mix epoxy resin, leveling agent, defoamer, wetting and dispersing agent and optional sheet insulating filler evenly to obtain epoxy material; Step 3: Add the reactive composite insulating shell graphene slurry and hexagonal boron nitride dispersion to the epoxy resin, and disperse it at high speed by shearing at 2000-6000 rpm for 20-60 min. Then grind it to obtain the functional filler composite matrix. Add an amine curing agent, mix evenly and adjust the construction viscosity to obtain a high-insulation and high-corrosion-resistant graphene epoxy functional coating.

[0006] Preferably, in step 1, the concentration of graphene oxide in the alcohol / water mixed solvent is 0.1-5 g / L, the volume ratio of alcohol to water in the alcohol / water mixed solvent is 1:(1-9), and the ultrasonic dispersion time is 0.5-3 h.

[0007] Preferably, in step 1, the silane coupling agent is selected from one or more of 3-glycidoxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and methacryloyloxypropyltrimethoxysilane; the silicon source precursor is selected from one or more of tetraethyl orthosilicate, methyl silicate, and water glass; and the cage-type polysilsesquioxane is selected from one or more of amino POSS, epoxy POSS, and vinyl POSS.

[0008] Preferably, in step 1, the pH of the in-situ hydrolysis-condensation reaction is 8-11, the reaction temperature is 25-70℃, and the reaction time is 2-12h; based on the mass of graphene oxide, the amount of the silane coupling agent is 10-80wt%, the amount of the silicon source precursor is 20-200wt%, and the amount of the cage-type polysilsesquioxane is 5-80wt%.

[0009] Preferably, in step 2, the hexagonal boron nitride is sheet-like hexagonal boron nitride or exfoliated hexagonal boron nitride nanosheets with an average sheet diameter of 0.2-20 μm and a thickness of 5-500 nm; the hexagonal boron nitride dispersion further contains 1-20 wt% of a silane coupling agent or a polyether-modified dispersant.

[0010] Preferably, in step 2, the epoxy resin is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin, and organosilicon modified epoxy resin; the sheet-like insulating filler is selected from one or more of mica powder, glass flakes, sheet-like alumina, and sheet-like silicates.

[0011] Preferably, in the epoxy functional coating, the amount of reactive composite insulating shell graphene added is 0.05-3 wt%, the amount of hexagonal boron nitride added is 1-20 wt%, and the amount of sheet insulating filler added is 0-25 wt%, and the mass ratio of reactive composite insulating shell graphene to hexagonal boron nitride is 1:(2-30).

[0012] Preferably, in step 3, the amine curing agent is selected from one or more of alicyclic amines, modified aliphatic amines, polyamide curing agents, and phenolic amine curing agents; the epoxy resin and the amine curing agent are mixed in a ratio of epoxy equivalent to active hydrogen equivalent of 1:(0.8-1.2).

[0013] Preferably, in step 4, the room temperature pre-curing temperature is 20-35℃ and the time is 2-24h; the heating curing temperature is 60-120℃ and the time is 1-6h; the dry film thickness of the resulting epoxy functional coating is 50-300μm.

[0014] The beneficial effects of this invention are: This invention constructs a composite insulating shell containing a silica network and a polysilsesquioxane structure through in-situ hydrolysis and condensation on the surface of graphene oxide. This effectively encapsulates the intrinsic conductive sites of graphene while introducing a large number of reactive functional groups. This eliminates the risk of graphene forming conductive pathways in the coating and, through the chemical bonding between the shell's active groups and the epoxy resin network, significantly enhances the interfacial bonding strength and dispersion stability between graphene and the resin matrix. Furthermore, high aspect ratio hexagonal boron nitride, treated with high-speed dispersion coupled with ultrasonication, is introduced as a synergistic insulating filler. This filler forms a multi-level insulating shielding network structure with the reactive composite insulating shell graphene. The two work synergistically to exert physical shielding and interfacial reinforcement effects, significantly improving the coating's density and impermeability. The resulting epoxy functional coating possesses excellent electrical insulation properties, resistance to media corrosion, and adhesion, with an electrical strength exceeding 40 kV / mm and a volume resistivity of 10¹. 5 With an Ω·cm level, no change after more than 2000 hours of salt spray testing, and an adhesion of over 8MPa by pull-out method, it can meet the synergistic requirements of high insulation and high corrosion resistance of coatings in harsh environments such as marine engineering, power equipment, and rail transportation. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This refers to the electrical strength and adhesion of epoxy functional coatings. Detailed Implementation

[0016] The following provides a detailed description of the embodiments of the present invention: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0017] Example 1: A method for preparing a high-insulation, high-corrosion-resistant graphene epoxy functional coating, comprising the following steps: Step 1: Taking the preparation of 1 kg of epoxy functional coating as an example, weigh 0.370 g of graphene oxide and add 3704 mL of ethanol / deionized water mixed solvent, where the volume ratio of ethanol to water is 1:9. Disperse under ultrasonic conditions for 0.5 h to obtain a graphene oxide dispersion with a concentration of 0.1 g / L. Then add 0.037 g of 3-glycidyl etheroxypropyltrimethoxysilane, 0.074 g of tetraethyl orthosilicate, and 0.0185 g of epoxy POSS to the dispersion, adjust the pH of the system to 8, and react at 25 °C for 12 h to form a composite insulating shell on the surface of graphene oxide. After the reaction is completed, concentrate and remove most of the solvent to obtain a reactive composite insulating shell graphene slurry. Step 2: Take 10.0g of hexagonal boron nitride flakes with an average flake diameter of 0.2μm and a thickness of 5nm, add them to 50.0g of epoxy reactive diluent, and add 0.10g of polyether modified dispersant. Disperse at 1000pm for 60min, and then ultrasonically disperse at 20kHz ultrasonic frequency and 200W ultrasonic power for 90min to obtain a hexagonal boron nitride dispersion. At the same time, take 772.0g of bisphenol A type epoxy resin, 5.0g of leveling agent, 3.0g of defoamer and 5.0g of wetting and dispersing agent, mix them evenly to obtain an epoxy material. Step 3: Add the reactive composite insulating shell graphene slurry and hexagonal boron nitride dispersion to the epoxy resin, shear and disperse at 2000 rpm for 60 min, then grind, and then add 154.4 g of modified fatty amine curing agent to make the ratio of epoxy content to active hydrogen equivalent 1:0.8. Mix evenly, adjust the construction viscosity, and obtain a high-insulation and high-corrosion-resistant graphene epoxy functional coating.

[0018] Example 2: A method for preparing a high-insulation, high-corrosion-resistant graphene epoxy functional coating, comprising the following steps: Step 1: Taking the preparation of 1 kg of epoxy functional coating as an example, weigh 6.522 g of graphene oxide and add 1304 mL of ethanol / deionized water mixed solvent, where the volume ratio of ethanol to water is 1:1. Disperse under ultrasonic conditions for 3 h to obtain a graphene oxide dispersion with a concentration of 5.0 g / L. Then add 5.218 g of 3-glycidyl etheroxypropyltrimethoxysilane, 13.044 g of tetraethyl orthosilicate, and 5.218 g of epoxy POSS to the dispersion, adjust the pH of the system to 11, and react at 70 °C for 12 h to form a composite insulating shell on the surface of graphene oxide. After the reaction is completed, concentrate and remove most of the solvent to obtain a reactive composite insulating shell graphene slurry. Step 2: Take 105.0g of sheet-like hexagonal boron nitride with an average sheet diameter of 10.1μm and a thickness of 252.5nm, add it to 50.0g of epoxy reactive diluent, and add 11.025g of polyether modified dispersant. Disperse at 3000pm for 35min, and then ultrasonically disperse at 40kHz ultrasonic frequency and 600W ultrasonic power for 50min to obtain a hexagonal boron nitride dispersion. At the same time, take 544.58g of bisphenol A type epoxy resin, 125.0g of mica powder, 5.0g of leveling agent, 3.0g of defoamer and 5.0g of wetting and dispersing agent, mix them evenly to obtain an epoxy material. Step 3: Add the reactive composite insulating shell graphene slurry and hexagonal boron nitride dispersion to the epoxy resin, shear and disperse at 4000 rpm for 40 min, then grind, and then add 136.15g of alicyclic amine curing agent to make the ratio of epoxy monomer to active hydrogen equivalent 1:1, mix evenly, adjust the construction viscosity, and obtain a high-insulation and high-corrosion-resistant graphene epoxy functional coating.

[0019] Example 3: A method for preparing a high-insulation, high-corrosion-resistant graphene epoxy functional coating, comprising the following steps: Step 1: Taking the preparation of 1 kg of epoxy functional coating as an example, weigh 0.370 g of graphene oxide and add 3704 mL of ethanol / deionized water mixed solvent, where the volume ratio of ethanol to water is 1:9. Disperse under ultrasonic conditions for 0.5 h to obtain a graphene oxide dispersion with a concentration of 0.1 g / L. Then add 0.037 g of 3-glycidyl etheroxypropyltrimethoxysilane, 0.074 g of tetraethyl orthosilicate, and 0.0185 g of epoxy POSS to the dispersion, adjust the pH of the system to 8, and react at 25 °C for 2 h to form a composite insulating shell on the surface of graphene oxide. After the reaction is completed, concentrate and remove most of the solvent to obtain a reactive composite insulating shell graphene slurry. Step 2: Take 200.0g of sheet-like hexagonal boron nitride with an average flake diameter of 20μm and a thickness of 500nm, add it to 50.0g of epoxy reactive diluent, and add 40.0g of polyether modified dispersant. Disperse at 5000pm for 10min, and then ultrasonically disperse at 60kHz ultrasonic frequency and 1000W ultrasonic power for 10min to obtain a hexagonal boron nitride dispersion. At the same time, take 320.77g of bisphenol A type epoxy resin, 250.0g of glass flakes, 5.0g of leveling agent, 3.0g of defoamer and 5.0g of wetting and dispersing agent, mix them evenly to obtain an epoxy-based material. Step 3: Add the reactive composite insulating shell graphene slurry and hexagonal boron nitride dispersion to the epoxy resin, shear and disperse at 6000 rpm for 20 min, then grind, and then add 96.23g of phenolic amine curing agent to make the ratio of epoxy monomer to active hydrogen equivalent 1:1.2, mix evenly, adjust the construction viscosity, and obtain a high-insulation and high-corrosion-resistant graphene epoxy functional coating.

[0020] Comparative Example 1: The difference between this comparative example and Example 1 is that no reactive composite insulating shell graphene slurry is added; the remaining steps are the same as in Example 1.

[0021] Comparative Example 2: The difference between this comparative example and Example 1 is that the graphene oxide was not modified with a composite insulating shell, while the other steps are the same as in Example 1.

[0022] A method for preparing a high-insulation, high-corrosion-resistant graphene epoxy functional coating includes the following steps: Step 1: Taking the preparation of 1kg epoxy functional coating as an example, weigh 0.370g graphene oxide, add 3704mL of ethanol / deionized water mixed solvent, wherein the volume ratio of ethanol to water is 1:9, disperse under ultrasonic conditions for 0.5h to obtain graphene oxide dispersion with a concentration of 0.1g / L. Step 2: Take 10.0g of hexagonal boron nitride flakes with an average flake diameter of 0.2μm and a thickness of 5nm, add them to 50.0g of epoxy reactive diluent, and add 0.10g of polyether modified dispersant. Disperse at 1000pm for 60min, and then ultrasonically disperse at 20kHz ultrasonic frequency and 200W ultrasonic power for 90min to obtain a hexagonal boron nitride dispersion. At the same time, take 772.0g of bisphenol A type epoxy resin, 5.0g of leveling agent, 3.0g of defoamer and 5.0g of wetting and dispersing agent, mix them evenly to obtain an epoxy material. Step 3: Add the graphene oxide dispersion and hexagonal boron nitride dispersion to the epoxy resin, shear and disperse at 2000 rpm for 60 min, then grind, and then add 154.4 g of modified fatty amine curing agent to make the ratio of epoxy monomer to active hydrogen equivalent 1:0.8. Mix evenly, adjust the construction viscosity, and obtain a high-insulation and high-corrosion-resistant graphene epoxy functional coating.

[0023] Comparative Example 3: The difference between this comparative example and Example 1 is that no hexagonal boron nitride dispersion is added; the remaining steps are the same as in Example 1.

[0024] Performance testing 1 Electrical insulation performance test The electrical strength of epoxy functional coatings was tested according to GB / T 1408.1-2016 standard. The volume resistivity and surface resistivity of epoxy functional coatings were tested according to GB / T31838.2-2019 standard.

[0025] 2. Corrosion resistance test The corrosion resistance of epoxy functional coatings was tested in accordance with GB / T 31588.1-2015 standard.

[0026] 3. Adhesion Test The adhesion of epoxy functional coatings was tested in accordance with GB / T 5210-2006 standard.

[0027] Table 1 Performance test results of epoxy functional coatings

[0028] As shown in Table 1, the coatings prepared in all examples exhibit significant advantages in electrical insulation, corrosion resistance, and adhesion. Examples 1-3 show electrical strength exceeding 40 kV / mm, volume resistivity and surface resistivity on the order of 10¹⁵ Ω·cm and 10¹⁵ Ω respectively, and show no change after more than 1200 hours of neutral salt spray testing, with adhesion exceeding 8 Pma. In contrast, Comparative Example 1, lacking the reactive composite insulating shell of graphene, lacks the shielding effect of graphene, resulting in insufficient coating density. Therefore, it exhibits the worst insulation and corrosion resistance, with an electrical strength of only 21.4 kV / mm, a volume resistivity dropping to the order of 10¹² Ω·cm, and blistering after 400 hours of salt spray testing. Comparative Example 2 used unmodified graphene oxide. Because graphene itself is conductive and has poor dispersion and weak interfacial bonding in the resin, localized conductive pathways may form in the coating, reducing its density and interfacial bonding strength. Therefore, its insulation and corrosion resistance are still far lower than the examples, with an electrical strength of only 28.5 kV / mm and rust appearing after 600 hours of salt spray testing. Comparative Example 3 did not add hexagonal boron nitride, lacking the role of insulating synergistic filler. Although the graphene composite insulating shell can improve performance to some extent, it is difficult to form a multi-level insulating shielding network. The coating's insulation and corrosion resistance are significantly lower than the examples, with an electrical strength of 35.2 kV / mm and slight blistering appearing after 800 hours of salt spray testing.

[0029] 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 method for preparing a high-insulation, high-corrosion-resistant graphene epoxy functional coating, characterized in that, Includes the following steps: Step 1: Add graphene oxide to an alcohol / water mixed solvent and disperse it by ultrasonication to obtain a graphene oxide dispersion. Then add silane coupling agent, silicon source precursor and cage-type polysilsesquioxane. Under alkaline conditions, carry out in-situ hydrolysis and condensation reaction to form a composite insulating shell containing a silica network and a polysilsesquioxane structure on the surface of graphene oxide, and obtain a reactive composite insulating shell graphene slurry. Step 2: Add hexagonal boron nitride to an alcohol solvent, first disperse it at high speed at 1000-5000 rpm for 10-60 min, then place it under ultrasonic frequency of 20-60 kHz and ultrasonic power of 200-1000 W for 10-90 min to obtain a hexagonal boron nitride dispersion; at the same time, mix epoxy resin, leveling agent, defoamer, wetting and dispersing agent and optional sheet insulating filler evenly to obtain epoxy material; Step 3: Add the reactive composite insulating shell graphene slurry and hexagonal boron nitride dispersion to the epoxy resin, and disperse it at high speed by shearing at 2000-6000 rpm for 20-60 min. Then grind it to obtain the functional filler composite matrix. Add an amine curing agent, mix evenly and adjust the construction viscosity to obtain a high-insulation and high-corrosion-resistant graphene epoxy functional coating.

2. The preparation method of the high-insulation and high-corrosion-resistant graphene epoxy functional coating according to claim 1, characterized in that, In step 1, the concentration of graphene oxide in the alcohol / water mixed solvent is 0.1-5 g / L, the volume ratio of alcohol to water in the alcohol / water mixed solvent is 1:(1-9), and the ultrasonic dispersion time is 0.5-3 h.

3. The preparation method of the high-insulation and high-corrosion-resistant graphene epoxy functional coating according to claim 1, characterized in that, In step 1, the silane coupling agent is selected from one or more of 3-glycidoxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and methacryloyloxypropyltrimethoxysilane; the silicon source precursor is selected from one or more of tetraethyl orthosilicate, methyl silicate, and water glass; and the cage-type polysilsesquioxane is selected from one or more of amino POSS, epoxy POSS, and vinyl POSS.

4. The preparation method of the high-insulation and high-corrosion-resistant graphene epoxy functional coating according to claim 1, characterized in that, In step 1, the in-situ hydrolysis-condensation reaction has a pH of 8-11, a reaction temperature of 25-70℃, and a reaction time of 2-12h. Based on the mass of graphene oxide, the amount of silane coupling agent is 10-80wt%, the amount of silicon source precursor is 20-200wt%, and the amount of cage-type polysilsesquioxane is 5-80wt%.

5. The preparation method of the high-insulation and high-corrosion-resistant graphene epoxy functional coating according to claim 1, characterized in that, In step 2, the hexagonal boron nitride is in the form of sheet-like hexagonal boron nitride or exfoliated hexagonal boron nitride nanosheets, with an average sheet diameter of 0.2-20 μm and a thickness of 5-500 nm; the hexagonal boron nitride dispersion further contains 1-20 wt% of a silane coupling agent or a polyether-modified dispersant.

6. The preparation method of the high-insulation and high-corrosion-resistant graphene epoxy functional coating according to claim 1, characterized in that, In step 2, the epoxy resin is selected from one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic epoxy resin, and organosilicon modified epoxy resin; the sheet-like insulating filler is selected from one or more of mica powder, glass flakes, sheet-like alumina, and sheet-like silicates.

7. The preparation method of the high-insulation and high-corrosion-resistant graphene epoxy functional coating according to claim 1, characterized in that, In the epoxy functional coating, by total mass, the amount of reactive composite insulating shell graphene added is 0.05-3wt%, the amount of hexagonal boron nitride added is 1-20wt%, the amount of sheet insulating filler added is 0-25wt%, and the mass ratio of reactive composite insulating shell graphene to hexagonal boron nitride is 1:(2-30).

8. The preparation method of the high-insulation and high-corrosion-resistant graphene epoxy functional coating according to claim 1, characterized in that, In step 3, the amine curing agent is selected from one or more of alicyclic amines, modified aliphatic amines, polyamide curing agents, and phenolic amine curing agents; the epoxy resin and the amine curing agent are mixed in a ratio of epoxy equivalent to active hydrogen equivalent of 1:(0.8-1.2).

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