Graphene powder compound, preparation method and sintered epoxy powder coating

Abstract

The invention provides a graphene powder compound, a preparation method and a sintered epoxy powder coating, and relates to the technical field of powder paints.The preparation method comprises the steps that a graphene material and an inorganic dispersing agent with the mass ratio being (1-4): (11-50) are stirred at a high speed and dispersed, and the graphene powder compound is obtained; wherein the inorganic dispersing agent is prepared from a first nanoscale compound, a second nanoscale compound and a micron-sized compound in a mass ratio of (1-10): (10-30): (2-10). According to the graphene powder compound prepared by utilizing the preparation process provided by the embodiment of the invention, the problems that the graphene nanosheets are difficult to uniformly disperse and easy to agglomerate in the preparation process of the sintered epoxy powder coating can be fundamentally solved, and the cathode stripping performance of the sintered epoxy powder coating is greatly improved; the obtained high-performance sintered epoxy powder coating can be used in the field of industrial heavy corrosion prevention.

Description

Technical Field

[0001] This invention relates to the field of powder coating technology, and in particular to a graphene powder composite, its preparation method, and a fusion-bonded epoxy powder coating. Background Art

[0002] Currently, fusion-bonded epoxy powder coatings are commonly used to protect industrial pipelines from corrosion. However, existing fusion-bonded epoxy powder coatings are semi-permeable materials. After long-term burial, the coating has a high water vapor permeability due to the humid environment, which easily leads to a decrease in the adhesion between the coating and the substrate. This can cause cathodic disbonding, where water, oxygen, ions, etc., penetrate the coating, gradually losing its barrier protection and causing blistering and cracking. Ultimately, this leads to underground leakage, causing corrosion of the pipeline steel and resulting in local perforation, which greatly affects the safety of fluid transportation. In addition, the fusion-bonded epoxy powder coatings commonly used in industrial pipeline anti-corrosion construction have poor scratch resistance.

[0003] Researchers have employed various techniques to improve the poor cathodic stripping performance of fusion-bonded epoxy powder coatings. These techniques include using highly active curing agents during the preparation of fusion-bonded epoxy powder coatings, improving powder coating extrusion equipment, redesigning the filler system of fusion-bonded epoxy powder coatings, and adding additional additives such as curing accelerators or adhesion promoters during preparation.

[0004] However, these continuously evolving technologies have still failed to fundamentally solve the problem of cathodic disbondment of fusion-bonded epoxy powder coatings in harsh underground environments. Summary of the Invention

[0005] To address the above problems, in a first aspect, the present invention provides a method for preparing a graphene powder composite, the method comprising:

[0006] Graphene material and an inorganic dispersant in a mass ratio of 1–4:11–50 are stirred at high speed to disperse the graphene powder composite. The inorganic dispersant is composed of a first nanoscale compound, a second nanoscale compound, and a micron-scale compound in a mass ratio of 1–10:10–30:2–10.

[0007] Preferably, the ratio of the total surface area of ​​the graphene material to the sum of the total surface areas of the remaining components in the graphene powder composite is 0.96–1.1, and the loose packing density of the graphene powder composite is 0.13 g / cm³. 3 ~0.2g / cm 3 .

[0008] Preferably, the high-speed stirring time is no more than 120 seconds, and the high-speed stirring speed is 2000 r / min to 8000 r / min.

[0009] Preferably, the graphene material is graphene oxide, hydrogenated graphene, nitrographene, or fluorinated graphene.

[0010] Preferably, the first nanoscale compound is fumed silica, and the particle size of the first nanoscale compound is 5 nm to 50 nm, with a specific surface area of ​​100 m². 2 / g~300m 2 / g.

[0011] Preferably, the second nanoscale compound is one or more of titanium dioxide, silicon carbide, zirconium oxide, and silicon nitride, and the particle size of the second nanoscale compound is 10 nm to 500 nm, with a specific surface area of ​​10 m². 2 / g~100m 2 / g.

[0012] Preferably, the micron-sized compound is one or more of boron nitride, silicon micro powder, barium sulfate, and wollastonite, and the particle size of the micron-sized compound is 0.5 μm to 10 μm.

[0013] Preferably, the high-speed stirring of the graphene material and inorganic dispersant in a mass ratio of 1-4:11-50 includes:

[0014] The graphene material and the inorganic dispersant are transported by a high-speed inert gas stream to a mixer with a built-in high-speed stirrer for high-speed stirring.

[0015] In a second aspect, the present invention provides a graphene powder composite, which is obtained by the preparation method described in the first aspect above.

[0016] Thirdly, the present invention provides a fusion-bonded epoxy powder coating comprising the following components in parts by weight: 0.5 to 5 parts of the graphene powder composite described in the second aspect above, 45 to 70 parts of epoxy resin, 8 to 30 parts of phenolic curing agent, 0.1 to 0.5 parts of pigment, 20 to 35 parts of filler, and 1 to 10 parts of other additives.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] This invention provides a graphene powder composite, a preparation method, and a fusion-bonded epoxy powder coating, relating to the field of powder coating technology. The preparation method includes: high-speed stirring of graphene material and an inorganic dispersant in a mass ratio of 1–4:11–50 to disperse the graphene powder composite; wherein the inorganic dispersant is composed of a first nanoscale compound, a second nanoscale compound, and a micron-scale compound in a mass ratio of 1–10:10–30:2–10. The graphene powder composite prepared using the preparation process provided in this invention fundamentally solves the problems of uneven dispersion and easy agglomeration of graphene nanosheets in the preparation of fusion-bonded epoxy powder coatings, greatly improving the cathodic disbonding performance of the fusion-bonded epoxy powder coating, enabling the obtained high-performance fusion-bonded epoxy powder coating to be used in industrial heavy-duty anti-corrosion applications.

[0019] In this embodiment of the invention, a dry surface treatment process is used as a dispersion preparation process, and nanomaterials and micromaterials are used as inorganic dispersants. Since the inorganic dispersants used are nano- and micro-scale, the graphene material takes advantage of the small particle size and large specific surface area of ​​the inorganic dispersants to adsorb the inorganic dispersants and make them wrap around the graphene material. Under the action of high-speed stirring, the inorganic dispersants fully contact the surface of the graphene material to form a stable coating, thereby preventing the agglomeration of the graphene material with a large specific surface area. The graphene powder composite prepared using the preparation process provided in this invention fundamentally solves the problems of uneven dispersion and easy agglomeration of graphene materials in the preparation of fusion-bonded epoxy powder coatings. This greatly improves the cathodic disbonding performance of the fusion-bonded epoxy powder coating, thereby significantly extending the service life of pipeline equipment coatings and reducing economic losses and production safety hazards caused by the failure of steel pipeline coatings. It has huge economic and social benefits. Moreover, because the obtained fusion-bonded epoxy powder coating has excellent adhesion and cathodic disbonding performance, this coating can be used as an anti-corrosion coating for steel pipes, steel strips or other metal substrates, especially for metal substrates that may be bent after coating. Detailed Implementation

[0020] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0021] Specific experimental steps or conditions are not specified in the examples; however, they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products.

[0022] Graphene, characterized by its two-dimensional sheet structure and hydrophobicity, is a densely packed array of benzene rings (hexagonal honeycomb lattice) composed of single-layer carbon atoms, exhibiting remarkable structural stability. Graphene nanosheets, on the other hand, are nanosheets composed of graphene layers. To improve the corrosion resistance of fusion-bonded epoxy powder coatings, the inventors used graphene or graphene nanosheets as one of the raw materials. However, they found that the resulting coatings exhibited decreased corrosion resistance. This is because, firstly, due to the large specific surface area of ​​graphene or graphene nanosheets, van der Waals forces and π-π interactions exist between the graphene layers or nanosheets, easily leading to agglomeration. Once agglomerates, these aggregates are difficult to separate, which diminishes many of the nanomaterials' excellent physicochemical properties, such as corrosion resistance. Corrosion resistance and toughness decrease sharply or even disappear; on the other hand, during the process of combining graphene or graphene nanosheets with the matrix material of anti-corrosion coatings, due to the characteristics of graphene or graphene nanosheets having a large specific surface area, high specific surface energy, low density, and large polydispersity index, there will be problems with poor compatibility between graphene or graphene nanosheets and organic resins, curing agents, pigments and fillers in the coating. This will cause graphene or graphene nanosheets to agglomerate, resulting in the matrix material not being fully cured and forming coating defects. Water, oxygen, ions, etc. will corrode through these coating defects.

[0023] Therefore, the aggregation of graphene and graphene nanosheets not only affects their excellent anti-corrosion performance and toughness, but also leads to the deterioration of the matrix material properties. This results in poor anti-corrosion performance of fusion-bonded epoxy powder coatings, allowing water, oxygen, ions, etc. to penetrate the coating, causing the coating to gradually lose its barrier protection function and produce blistering and cracking. In other words, the cathodic disbonding performance of fusion-bonded epoxy powder coatings deteriorates.

[0024] To address the problem of poor cathode stripping performance in fusion-bonded epoxy powder coatings, in a first aspect, the present invention provides a method for preparing a graphene powder composite, the method comprising:

[0025] Graphene material and an inorganic dispersant in a mass ratio of 1–4:11–50 are stirred at high speed to disperse the graphene powder composite. The inorganic dispersant is composed of a first nanoscale compound, a second nanoscale compound, and a micron-scale compound in a mass ratio of 1–10:10–30:2–10.

[0026] Among them, inorganic dispersants include micron-sized and nano-sized compounds, which have the characteristics of small particle size and large specific surface area;

[0027] In this embodiment, the graphene material is graphene or graphene nanosheets; wherein, the graphene is graphene with a two-dimensional layered structure; the graphene nanosheets are nanosheets composed of graphene layers; when the number of layers in the graphene material is 1 to 2, it is graphene; when the number of layers in the graphene material is 3 to 10, it is graphene nanosheets. Since graphene nanosheets are nanosheets composed of graphene layers, the aggregation phenomenon of 3 to 10-layer graphene nanosheets is more severe compared to 1 to 2-layer graphene.

[0028] The graphene nanosheets have a thickness of 1 nm to 2 nm, a particle size of 1 μm to 50 μm, 3 to 10 layers, and a specific surface area of ​​200 m². 2 / g~700m 2 / g.

[0029] Furthermore, the preferred particle size of the graphene nanosheets is 5 μm to 15 μm, the preferred number of layers is 3 to 5, and the preferred specific surface area is 400 m². 2 / g~600m 2 / g.

[0030] Specifically, since the larger the specific surface area of ​​graphene nanosheets, the more prone they are to aggregation, the specific surface area of ​​the graphene nanosheets is limited in this embodiment. In this embodiment, when the number of graphene nanosheets is further 3 to 5 layers, their corrosion resistance and toughness are better; since when the number of layers is greater than 10 or its thickness is too large (e.g., 5 nm), it is classified as graphite, and its corrosion resistance and toughness are weakened, graphene nanosheets with more than 10 layers or too thick are not selected in this embodiment.

[0031] In this embodiment of the invention, a dry surface treatment process is used as the dispersion preparation process, and nanomaterials and micromaterials are used as inorganic dispersants. Since the inorganic dispersants used are nano- and micro-scale, the graphene / graphene nanosheets take advantage of the small particle size and large specific surface area of ​​the inorganic dispersants to adsorb the inorganic dispersants and make them wrap around the graphene / graphene nanosheets. Under the action of high-speed stirring, the inorganic dispersants fully contact the surface of the graphene layer or the surface of the graphene nanosheet layer to form a stable coating, thereby preventing the aggregation of graphene / graphene nanosheets with large specific surface area. The graphene powder composite prepared using the preparation process provided in this invention fundamentally solves the problems of uneven dispersion and easy agglomeration of graphene / graphene nanosheets in the preparation of fusion-bonded epoxy powder coatings. This greatly improves the cathodic disbonding performance of the fusion-bonded epoxy powder coating, thereby significantly extending the service life of pipeline equipment coatings and reducing economic losses and production safety hazards caused by the failure of steel pipeline coatings. It has huge economic and social benefits. Moreover, because the obtained fusion-bonded epoxy powder coating has excellent adhesion and cathodic disbonding performance, it can be used as an anti-corrosion coating for steel pipes, steel strips or other metal substrates, especially for metal substrates that may be bent after coating.

[0032] Since the graphene powder composite has been pre-dispersed with graphene / graphene nanosheets that have a large specific surface area, high specific surface energy, low density, and high polydispersity index, it is easy to achieve uniform dispersion and mixing even when the graphene powder composite is mixed with the matrix material of the coating. This solves the compatibility problem between graphene / graphene nanosheets and fusion-bonded epoxy powder coating, thus significantly improving the cathodic disbonding performance of the coating.

[0033] In this embodiment, an inorganic dispersant is used, thus avoiding the problem that "when using an organic dispersant to disperse and exfoliate graphene, the organic dispersant will be adsorbed into the graphene and difficult to separate, which has a significant impact on the quality of the graphene." In addition, the inorganic dispersants used in this embodiment are all acid and alkali resistant compounds and are inert compounds.

[0034] The graphene powder composite obtained after high-speed stirring in this embodiment has a stable dispersion state and high-strength dispersion. Therefore, the obtained composite material can be stored stably for a long time as a powder coating additive and can be used directly.

[0035] Specifically, by high-speed stirring, graphene / graphene nanosheets and inorganic dispersants are mixed and dispersed under high shear force within a certain time. By controlling the temperature, a pre-dispersion of graphene micro / nano composite material with fluffy, high fluidity and anti-caking properties is obtained; furthermore, the temperature does not exceed 50℃.

[0036] In this embodiment, a non-agglomerated graphene powder composite is used as the coating raw material. Utilizing the high barrier properties of graphene, it blocks the penetration of chloride ions, oxygen, and water molecules, delaying corrosion and enhancing the adhesion between the coating and the substrate. This prevents the coated substrate from being affected by the long-term damp environment underground. Specifically, the graphene material fills the pores of the coating, and the layered structure of the graphene material is stacked layer by layer in the coating to form a dense physical barrier layer. This extends the path of water molecules through the coating to the metal substrate, allowing it to be used as an additive in anti-corrosion coatings to improve the coating's anti-corrosion performance and toughness. It should also be noted that since fusion-bonded epoxy powder coatings are used in heavy-duty anti-corrosion industries, the conductivity of the graphene material must be avoided; only the anti-corrosion performance and toughness of the graphene material are utilized.

[0037] The fusion-bonded epoxy powder coating obtained in this embodiment is a single-layer coating, which has the characteristics of relatively simple process, strong feasibility and convenient processing; specifically, the fusion-bonded epoxy powder coating can be obtained by powder spraying, and no specific limitation is made here.

[0038] In some embodiments of the present invention, the ratio of the total surface area of ​​the graphene material to the sum of the total surface areas of the remaining components in the graphene powder composite is 0.96 to 1.1, and the loose packing density of the graphene powder composite is 0.13 g / cm³. 3 ~0.2g / cm 3 .

[0039] In this embodiment, the surface area ratio and the loose packing density of the graphene powder composite together constitute the characteristic values ​​of the surface treatment effect on the graphene material.

[0040] Specifically, the surface area ratio characterizes the performance of the pre-dispersion. If it is not within the range of 0.96 to 1.1, it indicates that the coating degree is insufficient or excessive. This invention obtains a composite material with good graphene / graphene nanosheet coating by an inorganic dispersant through a specific mass ratio. When the ratio of the total surface area of ​​graphene / graphene nanosheets to the sum of the total surface areas of the remaining components (inorganic dispersant) in the graphene powder composite is 1.1, it indicates that the coating degree is optimal. At this point, the inorganic dispersant coats the graphene / graphene nanosheets as much as possible without affecting the corrosion resistance and toughness of the graphene / graphene nanosheets, and the coating exhibits the best cathodic dissipation performance. It should also be noted that when the graphene / graphene nanosheets are insufficiently or excessively coated, the cathodic dissipation performance of the coating will be affected.

[0041] Specifically, the loose packing density of the graphene powder composite indicates the dispersion state of the composite; the loose packing density of the graphene powder composite is 0.13 g / cm³. 3 ~0.2g / cm 3This indicates that the complex is in a relatively loose, easily measured, and easy-to-use state, exhibiting high dispersibility.

[0042] In some embodiments of the present invention, the high-speed stirring time is no more than 120 seconds, and the high-speed stirring speed is 2000 r / min to 8000 r / min.

[0043] In this embodiment, the dry surface treatment process provided by the present invention can efficiently disperse and prepare graphene powder composites. If the dispersion time is too long, that is, the high-speed stirring time is too long, on the one hand, the particle size of the material will become larger due to the impact of the material for a long time, resulting in poor pre-dispersion effect. On the other hand, since the high shear force provided by the high stirring speed is required during the high-speed stirring process, the high-speed stirring for a long time will cause the material to heat up, and the temperature rise is not conducive to the dispersion of graphene / graphene nanosheets.

[0044] In this embodiment, graphene / graphene nanosheets and inorganic dispersants are dispersed under high shear force by a certain rotation speed. This high shear force can break down the van der Waals forces and intermolecular forces (π-π interactions) that cause agglomeration, resulting in a pre-dispersion of graphene micro / nano composite material with fluffy, high flowability and anti-caking properties. If the stirring speed is lower than 2000 r / min, high-intensity dispersion cannot be achieved. If no inorganic dispersant is added and graphene or graphene nanosheets are stirred at high speeds of 2000 r / min to 8000 r / min, the agglomeration of graphene or graphene nanosheets will be more severe. This is because if the agglomeration of graphene / graphene nanosheets is not dispersed by an inorganic dispersant, the graphene / graphene nanosheets will adsorb onto themselves during high-speed stirring, thus causing more severe agglomeration.

[0045] Furthermore, the preferred stirring speed is 3500 r / min to 5500 r / min.

[0046] In some embodiments of the present invention, the graphene material is graphene oxide, hydrogenated graphene, nitrographene, or fluorinated graphene.

[0047] In this embodiment, the graphene material can be a graphene derivative, including graphene oxide, hydrogenated graphene, nitrographene, and fluorinated graphene.

[0048] Furthermore, the graphene material can also be oxidized graphene containing hydroxyl or carboxyl groups, or reduced graphene or liquid-phase exfoliated graphene. In addition, in this embodiment, the graphene material can be graphene prepared by other methods other than "intercalation" such as redox methods, or graphene obtained by physical exfoliation methods such as intercalation methods.

[0049] In some embodiments of the present invention, the first nanoscale compound is fumed silica, and the particle size of the first nanoscale compound is 5 nm to 50 nm, with a specific surface area of ​​100 m². 2 / g~300m 2 / g.

[0050] Furthermore, the preferred particle size is 10 nm to 20 nm, and the preferred specific surface area is 100 m². 2 / g~200m 2 / g.

[0051] In some embodiments of the present invention, the second nanoscale compound is one or more of titanium dioxide, silicon carbide, zirconium oxide, and silicon nitride, and the particle size of the second nanoscale compound is 10 nm to 500 nm, with a specific surface area of ​​10 m². 2 / g~100m 2 / g.

[0052] Furthermore, the preferred particle size is 50 nm to 300 nm, and the preferred specific surface area is 10 m². 2 / g~50m 2 / g.

[0053] The titanium dioxide, silicon carbide, zirconium oxide, and silicon nitride selected in this embodiment not only have good insulation properties but also good wear resistance.

[0054] In some embodiments of the present invention, the micron-sized compound is one or more of boron nitride, silicon micropowder, barium sulfate, and wollastonite, and the particle size of the micron-sized compound is 0.5 μm to 10 μm.

[0055] Furthermore, the preferred particle size is 0.5 μm to 5 μm.

[0056] Among them, the particle size of graphene nanosheets > the particle size of micron-sized compounds > the particle size of second-nano-sized compounds > the particle size of first-nano-sized compounds;

[0057] In this embodiment, by setting an inorganic dispersant that matches the graphene nanosheets, the graphene nanosheets are better coated by the inorganic dispersant, and the graphene nanosheets are less likely to agglomerate when the graphene powder composite is mixed with the coating powder.

[0058] Specifically, large-surface-area, sheet-like, micron-sized graphene nanosheets are first dispersed using a smaller-sized first nanoscale compound. This first nanoscale compound fills the pores on the surface of the graphene nanosheets. Because the particle size of the first nanoscale compound is relatively fine, it can fill even the finer edges of the sheets, resulting in a more compact filling. Then, the slightly larger pores on the surface of the graphene nanosheets are filled with a second nanoscale compound. Finally, the largest pores are filled with a larger micron-sized compound. Through the synergy of the first, second, and micron-sized compounds, the entire graphene nanosheet is encapsulated. Therefore, in the industrial implementation of the preparation method provided by this invention, the compounds can be added sequentially: first the first nanoscale compound, then the second nanoscale compound, and finally the micron-sized compound. Since the amount of each raw material is small in laboratory preparation, they can all be mixed with the graphene nanosheets at once.

[0059] It should also be noted that if large, micron-sized compounds are used for filling first, on the one hand, since graphene nanosheets are sheet-like while micron-sized compounds are spherical, there will be areas that the micron-sized compounds cannot cover. On the other hand, directly filling the large pores first will result in the small pores of the graphene nanosheets not being filled, thus making the coverage or encapsulation of the graphene nanosheets insufficient. This will fail to prevent the graphene nanosheets from agglomerating and will not improve the cathodic stripping performance of the fusion-bonded epoxy powder coating.

[0060] In this embodiment, the first nanoscale compound, the second nanoscale compound, and the micron-scale compound cannot be amphoteric oxides or calcium carbonate. Amphoteric oxides include iron oxide, zinc oxide, aluminum oxide, etc. Specifically, since the performance test of the fusion-bonded epoxy powder coating is carried out in a mixed acid of concentrated sulfuric acid, 10% hydrochloric acid, and 30% phosphoric acid, if calcium carbonate is used, the resulting fusion-bonded epoxy powder coating will not be resistant to strong acids.

[0061] In some embodiments of the present invention, the high-speed stirring of graphene material and inorganic dispersant in a mass ratio of 1-4:11-50 includes:

[0062] The graphene material and the inorganic dispersant are transported by a high-speed inert gas stream to a mixer with a built-in high-speed stirrer for high-speed stirring.

[0063] In this embodiment, the mixer has a built-in high-speed agitator, which is composed of a dispersion disc and a paddle. By adjusting the stirring speed of the high-speed agitator, the material is mixed and dispersed under high shear force within a certain time to obtain a pre-dispersion of graphene micro-nano composite material.

[0064] Furthermore, the bottom of the high-speed mixer is a turbine-type dispersion disc, and the upper middle part is composed of three sets of propeller blades with different diameters. The diameter of the mixer is 0.2m to 0.8m.

[0065] Furthermore, since the present invention employs a dry surface treatment process, the dispersed phase medium is a solid, and the mixing and dispersion are carried out in a gas flow state, thus eliminating the need for processing methods such as filtration, drying, and pulverization.

[0066] It should also be noted that the wet surface treatment process involves soaking the raw materials in an appropriate diluent, followed by stirring and dispersion under controlled temperature conditions, and then filtering and drying to remove moisture before further use. Therefore, if the wet surface treatment process is used to disperse and prepare graphene powder composites, the filtering and drying process in the wet surface treatment process causes the graphene material, which is well dispersed in the liquid phase, to be compressed during the subsequent filtering and drying process, resulting in a further deterioration in the dispersion of the well dispersed graphene material. That is, the dispersion of graphene material in the solid composite obtained after filtering and drying deteriorates again, leading to partial agglomeration of graphene material. In addition, the wet surface treatment process cannot obtain a loose, fluffy powder composite, requiring further processing such as pulverization. Using the graphene powder composite preparation method provided by this invention, a loose powder composite can be obtained without filtering and drying, thus avoiding the partial agglomeration of graphene material caused by filtering and drying.

[0067] In a second aspect, the present invention provides a graphene powder composite, which is obtained by the preparation method described in the first aspect above.

[0068] In this embodiment of the invention, the graphene powder composite prepared by the preparation process provided by the present invention can fundamentally solve the problems of uneven dispersion and easy agglomeration of graphene / graphene nanosheets in the preparation process of fusion-bonded epoxy powder coatings.

[0069] Thirdly, the present invention provides a fusion-bonded epoxy powder coating comprising the following components in parts by weight: 0.5 to 5 parts of the graphene powder composite described in the second aspect above, 45 to 70 parts of epoxy resin, 8 to 30 parts of phenolic curing agent, 0.1 to 0.5 parts of pigment, 20 to 35 parts of filler, and 1 to 10 parts of other additives.

[0070] In this embodiment of the invention, by utilizing the graphene powder composite provided by the present invention, the cathodic disbonding performance of the fusion-bonded epoxy powder coating is greatly improved. This not only significantly extends the service life of the coating on pipeline equipment and reduces the economic losses and production safety hazards caused by the failure of the steel pipeline coating, but also has great economic and social benefits. Moreover, because the obtained fusion-bonded epoxy powder coating has excellent adhesion and cathodic disbonding performance, the coating can be used as an anti-corrosion coating for steel pipes, steel strips or other metal substrates, especially for metal substrates that may need to be bent after coating.

[0071] Furthermore, coupling agents or liquid resins can be atomized and sprayed onto the surface of graphene powder composites and then used as one of the coating components.

[0072] Specifically, the epoxy resin is one or more of phenolic epoxy resin, isocyanate modified epoxy resin, bisphenol A type epoxy resin, and hydrogenated bisphenol A type epoxy resin, and the epoxy equivalent of the epoxy resin is 400 g / eq to 900 g / eq, and more preferably 550 g / eq to 700 g / eq.

[0073] The phenolic hydroxyl equivalent of the phenolic curing agent is 200 g / eq to 400 g / eq, and more preferably 200 g / eq to 300 g / eq;

[0074] The pigment is selected from at least one of phthalocyanine blue, phthalocyanine green, and mixed-phase metal oxides (such as cobalt blue or titanium cobalt green);

[0075] The filler is selected from one or more of barium sulfate, silica fume, wollastonite, sericite, and titanium dioxide. The function of the filler is to fill the gaps in the powder preparation or spraying process to prevent chloride ions, oxygen, and water molecules from penetrating into the coating substrate through the gaps. When barium sulfate is selected as the filler, and barium sulfate is also selected in the micron-sized compound, the compatibility of the graphene powder composite is better.

[0076] Other additives include mixtures of curing accelerators, leveling agents, degassing agents, wetting accelerators, defoamers, and loosening agents; among them, the curing accelerator is a mixture of imidazole and its derivatives, such as 2-methylimidazolium, 2-heptadecylimidazolium, or 1-cyanoethyl-2-methylimidazolium; the leveling agent is an acrylic copolymer or acrylate copolymer, such as Resiflow PV88 and GLP588 leveling agents; the degassing agent is crystalline benzoin; and the wetting accelerator is a copolymer of butyl acrylate and methyl methacrylate, such as WK701.

[0077] To enable those skilled in the art to better understand the present invention, the preparation method provided by the present invention will be described below through several specific embodiments.

[0078] The graphene nanosheets used in all embodiments and comparative embodiments had a thickness of 1 nm to 2 nm, a particle size of 1 μm to 50 μm, 3 to 10 layers, and a specific surface area of ​​200 m². 2 / g~700m 2 / g; The first nanoscale compound is fumed silica, with a particle size of 5nm to 50nm and a specific surface area of ​​100m². 2 / g~300m 2 / g; The particle size of the second nanoscale compound is in the range of 10nm to 500nm, and the specific surface area is 10m². 2 / g~100m 2 The particle size of micron-sized compounds is in the range of 0.5 μm to 10 μm within the range of / g.

[0079] Example 1

[0080] (1) Graphene nanosheets and inorganic dispersant (composed of fumed silica, titanium dioxide and barium sulfate) with a mass ratio of 3:50 were stirred at high speed and dispersed for a certain period of time to obtain a pre-dispersed graphene micro-nano composite material; wherein, the mass ratio of graphene nanosheets, fumed silica, titanium dioxide and barium sulfate was 1.2:1:17:2.

[0081] Specifically, the preparation method of graphene micro / nano composite material predispersants includes:

[0082] Graphene nanosheets and fumed silica are mixed and transported to a premixer by a high-speed inert gas stream for thorough contact and mixing, and then metered into the main mixer.

[0083] Meanwhile, titanium dioxide and barium sulfate are metered and enter the main mixer through delivery pipelines L1 and L2, respectively.

[0084] The high-speed stirrer of the mixer was set to a speed of 4500 r / min, and the mixing time was 15 seconds. After processing according to the above method, the loose bulk density of the graphene micro / nano composite pre-dispersion was 0.159 g / cm³. 3 The ratio of the total surface area of ​​graphene nanosheets to the total surface area of ​​other components is 0.96.

[0085] (2) Preparation of anti-corrosion graphene fusion-bonded epoxy powder coating, comprising the following components in parts by weight: 2.5 parts graphene micro-nano composite pre-dispersion, 50 parts epoxy resin, 17.8 parts phenolic curing agent, 0.1 parts pigment, 11 parts filler (precipitated barium sulfate), 0.4 parts curing accelerator, 0.3 parts degassing agent, 0.9 parts leveling agent, 16 parts wollastonite, 1 part wetting accelerator, and 0.2 parts loosening agent; wherein, the epoxy equivalent of the epoxy resin is 635 g / eq, and the phenolic hydroxyl equivalent of the phenolic curing agent is 240 g / eq;

[0086] Weigh each component raw material according to the formula, place them in a high-speed mixer and mix and crush for 3 minutes, with the speed set at 1000 r / min;

[0087] This homogeneous mixture was then fed into a twin-screw extruder (length-to-diameter ratio 16:1) for extrusion. The melting zone temperature was 97°C, and the mixing zone temperature was 112°C.

[0088] The extrudate is compressed into tablets using a cooling tablet press, then air-cooled and crushed.

[0089] The collected flaky crushed material is fed into an ACM pulverizer, where pulverization and classification occur simultaneously. The main grinding frequency of the pulverizer is set to 45Hz, the auxiliary grinding frequency to 25Hz, and the feeding frequency to 25Hz. The chiller operating temperature is set to 7℃, and the pulverizer screen is 180 mesh. Then, a cyclone separator separates the excessively fine powder, and a bag filter collects the ultrafine powder. The product collected by the cyclone separator is then passed through a high-frequency vibrating screen to obtain an anti-corrosion graphene fused epoxy powder coating.

[0090] Example 2

[0091] (1) Graphene nanosheets and inorganic dispersant (composed of fumed silica, titanium dioxide and barium sulfate) with a mass ratio of 3:50 were stirred at high speed and dispersed for a certain period of time to obtain a pre-dispersed graphene micro-nano composite material; wherein, the mass ratio of graphene nanosheets, fumed silica, titanium dioxide and barium sulfate was 1.2:2:13:5.

[0092] Specifically, the preparation method of graphene micro / nano composite material predispersants includes:

[0093] Graphene nanosheets and fumed silica are mixed and transported to a premixer by a high-speed inert gas stream for thorough contact and mixing, and then metered into the main mixer.

[0094] Meanwhile, titanium dioxide and barium sulfate are metered and enter the main mixer through delivery pipelines L1 and L2, respectively.

[0095] The high-speed stirrer of the mixer was set to a speed of 4500 r / min, and the mixing time was 15 seconds. After processing according to the above method, the loose bulk density of the graphene micro / nano composite pre-dispersion was 0.131 g / cm³. 3 The ratio of the total surface area of ​​graphene nanosheets to the total surface area of ​​other components is 0.96.

[0096] (2) Preparation of anti-corrosion graphene fusion-bonded epoxy powder coating, comprising the following components in parts by weight: 2.5 parts graphene micro-nano composite pre-dispersion, 50 parts epoxy resin, 13.4 parts phenolic curing agent, 0.1 parts pigment, 10 parts filler (precipitated barium sulfate), 0.4 parts curing accelerator, 0.3 parts degassing agent, 0.9 parts leveling agent, 15 parts wollastonite, 1 part wetting accelerator, and 0.2 parts loosening agent; wherein, the epoxy equivalent of the epoxy resin is 635 g / eq, and the phenolic hydroxyl equivalent of the phenolic curing agent is 200 g / eq;

[0097] Weigh each component raw material according to the formula, place them in a high-speed mixer and mix and crush for 3 minutes, with the speed set at 1000 r / min;

[0098] This homogeneous mixture was then fed into a twin-screw extruder (length-to-diameter ratio 16:1) for extrusion. The melting zone temperature was 97°C, and the mixing zone temperature was 112°C.

[0099] The extrudate is compressed into tablets using a cooling tablet press, then air-cooled and crushed.

[0100] The collected flaky crushed material is fed into an ACM pulverizer, where pulverization and classification occur simultaneously. The main grinding frequency of the pulverizer is set to 45Hz, the auxiliary grinding frequency to 25Hz, and the feeding frequency to 25Hz. The chiller operating temperature is set to 7℃, and the pulverizer screen is 180 mesh. Then, a cyclone separator separates the excessively fine powder, and a bag filter collects the ultrafine powder. The product collected by the cyclone separator is then passed through a high-frequency vibrating screen to obtain an anti-corrosion graphene fused epoxy powder coating.

[0101] Example 3

[0102] (1) Graphene nanosheets and inorganic dispersant (composed of fumed silica, titanium dioxide and barium sulfate) with a mass ratio of 3:50 were stirred at high speed and dispersed for a certain period of time to obtain a pre-dispersed graphene micro-nano composite material; wherein, the mass ratio of graphene nanosheets, fumed silica, titanium dioxide and barium sulfate was 2.4:1.5:30:8.5;

[0103] Specifically, the preparation method of graphene micro / nano composite material predispersants includes:

[0104] Graphene nanosheets and fumed silica are mixed and transported to a premixer by a high-speed inert gas stream for thorough contact and mixing, and then metered into the main mixer.

[0105] Meanwhile, titanium dioxide and barium sulfate are metered and enter the main mixer through delivery pipelines L1 and L2, respectively.

[0106] The high-speed stirrer of the mixer was set to a speed of 4500 r / min, and the mixing time was 15 seconds. After processing according to the above method, the loose bulk density of the graphene micro / nano composite pre-dispersion was 0.165 g / cm³. 3 The ratio of the total surface area of ​​graphene nanosheets to the total surface area of ​​other components is 1.1.

[0107] (2) Preparation of anti-corrosion graphene fusion-bonded epoxy powder coating, comprising the following components in parts by weight: 5 parts graphene micro-nano composite pre-dispersion, 50 parts epoxy resin, 17.2 parts phenolic curing agent, 0.1 parts pigment, 10 parts filler (precipitated barium sulfate), 0.4 parts curing accelerator, 0.3 parts degassing agent, 0.9 parts leveling agent, 14 parts wollastonite, 1 part wetting accelerator, and 0.2 parts loosening agent; wherein, the epoxy equivalent of the epoxy resin is 625 g / eq, and the phenolic hydroxyl equivalent of the phenolic curing agent is 240 g / eq;

[0108] Weigh each component raw material according to the formula, place them in a high-speed mixer and mix and crush for 3 minutes, with the speed set at 1000 r / min;

[0109] This homogeneous mixture was then fed into a twin-screw extruder (length-to-diameter ratio 16:1) for extrusion. The melting zone temperature was 97°C, and the mixing zone temperature was 112°C.

[0110] The extrudate is compressed into tablets using a cooling tablet press, then air-cooled and crushed.

[0111] The collected flaky crushed material is fed into an ACM pulverizer, where pulverization and classification occur simultaneously. The main grinding frequency of the pulverizer is set to 45Hz, the auxiliary grinding frequency to 25Hz, and the feeding frequency to 25Hz. The chiller operating temperature is set to 7℃, and the pulverizer screen is 180 mesh. Then, a cyclone separator separates the excessively fine powder, and a bag filter collects the ultrafine powder. The product collected by the cyclone separator is then passed through a high-frequency vibrating screen to obtain an anti-corrosion graphene fused epoxy powder coating.

[0112] Comparative Example 1

[0113] (1) Graphene nanosheets and inorganic dispersant (composed of fumed silica, titanium dioxide and barium sulfate) with a mass ratio of 3:50 were stirred at high speed and dispersed for a certain period of time to obtain a pre-dispersed graphene micro-nano composite material; wherein, the mass ratio of graphene nanosheets, fumed silica, titanium dioxide and barium sulfate was 1.2:1:8:11.

[0114] The preparation method of the graphene micro / nano composite predispersant was the same as in Example 1, and the loose bulk density of the prepared graphene micro / nano composite predispersant was 0.17 g / cm³. 3 The ratio of the total surface area of ​​graphene nanosheets to the sum of the total surface areas of other components is 1.58.

[0115] (2) The preparation and formulation of the anti-corrosion graphene fusion bonded epoxy powder coating are the same as in Example 1, with the epoxy equivalent of the epoxy resin being 635 g / eq and the phenolic hydroxyl equivalent of the phenolic curing agent being 240 g / eq.

[0116] Example 4

[0117] (1) The preparation method and mass ratios of the graphene micro / nano composite predispersant were the same as in Example 1, and the loose density of the prepared graphene micro / nano composite predispersant was 0.159 g / cm³. 3 The ratio of the total surface area of ​​graphene nanosheets to the total surface area of ​​other components is 0.96.

[0118] (2) Preparation of anti-corrosion graphene fusion-bonded epoxy powder coating, comprising the following components in parts by weight: 2.5 parts graphene micro-nano composite pre-dispersion, 50 parts epoxy resin, 16.2 parts phenolic curing agent, 0.1 parts pigment, 10 parts filler (precipitated barium sulfate), 0.4 parts curing accelerator, 0.3 parts degassing agent, 0.9 parts leveling agent, 15 parts wollastonite, 1 part wetting accelerator, and 0.2 parts loosening agent; wherein, the epoxy equivalent of the epoxy resin is 726 g / eq, and the phenolic hydroxyl equivalent of the phenolic curing agent is 220 g / eq;

[0119] The preparation of the corrosion-resistant graphene fusion-bonded epoxy powder coating is the same as in Example 1.

[0120] Comparative Example 2

[0121] (1) Graphene nanosheets and inorganic dispersant (composed of fumed silica, titanium dioxide and barium sulfate) with a mass ratio of 3:50 were stirred at high speed and dispersed for a certain period of time to obtain a pre-dispersed graphene micro-nano composite material; wherein, the mass ratio of graphene nanosheets, fumed silica, titanium dioxide and barium sulfate was 1.2:4:15:1.

[0122] The preparation method of the graphene micro / nano composite predispersant was the same as in Example 1, and the loose bulk density of the prepared graphene micro / nano composite predispersant was 0.072 g / cm³. 3 The ratio of the total surface area of ​​graphene nanosheets to the total surface area of ​​other components is 0.67.

[0123] (2) The preparation and formulation of the anti-corrosion graphene fusion bonded epoxy powder coating are the same as in Example 1, with the epoxy equivalent of the epoxy resin being 635 g / eq and the phenolic hydroxyl equivalent of the phenolic curing agent being 240 g / eq.

[0124] Comparative Example 3

[0125] (1) Graphene nanosheets and inorganic dispersant (composed of fumed silica, titanium dioxide and barium sulfate) with a mass ratio of 1:40 were stirred at high speed and dispersed for a certain period of time to obtain a pre-dispersed graphene micro-nano composite material; wherein the mass ratio of graphene nanosheets, fumed silica, titanium dioxide and barium sulfate was 1:1:11:28.

[0126] The preparation method of the graphene micro / nano composite predispersant was the same as in Example 1, and the loose bulk density of the prepared graphene micro / nano composite predispersant was 0.351 g / cm³. 3 The ratio of the total surface area of ​​graphene nanosheets to the total surface area of ​​other components is 0.96.

[0127] (2) Preparation of anti-corrosion graphene fusion-bonded epoxy powder coating, comprising the following components in parts by weight: 5.7 parts graphene micro-nano composite pre-dispersion, 50 parts epoxy resin, 17.8 parts phenolic curing agent, 0.1 parts pigment, 10 parts filler (precipitated barium sulfate), 0.4 parts curing accelerator, 0.3 parts degassing agent, 0.9 parts leveling agent, 14 parts wollastonite, 1 part wetting accelerator, and 0.2 parts loosening agent; wherein, the epoxy equivalent of the epoxy resin is 635 g / eq, and the phenolic hydroxyl equivalent of the phenolic curing agent is 240 g / eq;

[0128] The preparation of the corrosion-resistant graphene fusion-bonded epoxy powder coating is the same as in Example 1.

[0129] Comparative Example 4

[0130] (1) The graphene nanosheets were not treated with a dry surface treatment process and were directly mixed with other components of the powder coating. The loose bulk density of the graphene nanosheets was approximately 0.06 g / cm³. 3 .

[0131] (2) Preparation of anti-corrosion graphene fusion bonded epoxy powder coating, comprising the following components in parts by weight: 0.14 parts graphene nanosheets, 50 parts epoxy resin, 17.8 parts phenolic curing agent, 0.1 parts pigment, 11 parts filler (precipitated barium sulfate), 0.4 parts curing accelerator, 0.3 parts degassing agent, 0.9 parts leveling agent, 16 parts wollastonite, 1 part wetting accelerator, and 0.2 parts loosening agent; wherein, the epoxy equivalent of the epoxy resin is 635 g / eq, and the phenolic hydroxyl equivalent of the phenolic curing agent is 240 g / eq;

[0132] The preparation of the corrosion-resistant graphene fusion-bonded epoxy powder coating is the same as in Example 1.

[0133] Comparative Example 5

[0134] (1) Graphene nanosheets and inorganic dispersant (composed of fumed silica, titanium dioxide and barium sulfate) with a mass ratio of 3:50 were stirred at high speed and dispersed for a certain period of time to obtain a pre-dispersed graphene micro-nano composite material; wherein, the mass ratio of graphene nanosheets, fumed silica, titanium dioxide and barium sulfate was 1:1:11:28.

[0135] The preparation method of the graphene micro / nano composite pre-dispersion is the same as in Example 1, except that the rotation speed is set to 6000 r / min and the mixing time is 15 seconds in this comparative example; the loose bulk density of the prepared graphene micro / nano composite pre-dispersion is 0.14 g / cm³. 3 The ratio of the total surface area of ​​graphene nanosheets to the sum of the total surface areas of other components is 1.58.

[0136] (2) The preparation and formulation of the anti-corrosion graphene fusion bonded epoxy powder coating are the same as in Example 1, with the epoxy equivalent of the epoxy resin being 635 g / eq and the phenolic hydroxyl equivalent of the phenolic curing agent being 240 g / eq.

[0137] Comparative Example 6

[0138] (1) The preparation method and mass ratios of the graphene micro / nano composite pre-dispersion were the same as in Example 1, except that the rotation speed was set to 4500 r / min and the mixing time to 1800 seconds. The loose density of the prepared graphene micro / nano composite pre-dispersion was 0.27 g / cm³. 3 The ratio of the total surface area of ​​graphene nanosheets to the total surface area of ​​other components is 0.96.

[0139] (2) Preparation of anti-corrosion graphene fusion-bonded epoxy powder coating, comprising the following components in parts by weight: 2.5 parts graphene micro-nano composite pre-dispersion, 50 parts epoxy resin, 16.2 parts phenolic curing agent, 0.1 parts pigment, 10 parts filler (precipitated barium sulfate), 0.4 parts curing accelerator, 0.3 parts degassing agent, 0.9 parts leveling agent, 15 parts wollastonite, 1 part wetting accelerator, and 0.2 parts loosening agent; wherein, the epoxy equivalent of the epoxy resin is 726 g / eq, and the phenolic hydroxyl equivalent of the phenolic curing agent is 220 g / eq; it should also be noted that, due to the different epoxy resins used in the examples, their corresponding epoxy equivalents are different; and the different phenolic curing agents used have different corresponding phenolic hydroxyl equivalents.

[0140] The preparation of the corrosion-resistant graphene fusion-bonded epoxy powder coating is the same as in Example 1.

[0141] The following describes the preparation of coating samples and the performance testing of 10 graphene fusion-bonded epoxy powder coatings. The samples were made of ordinary carbon steel plates measuring 150mm*150mm*6mm. Before surface treatment, oil stains were removed from the surface of the samples, followed by sandblasting to control the surface cleanliness to Sa2.5 level, with the anchor pattern depth controlled between 40 and 100 μm. After sandblasting, the samples were preheated at 225–230℃ for half an hour, and then the powder coating was applied to the sample surface using electrostatic spraying to the specified film thickness (controlled at 300–350 μm). The samples were then placed in a 230℃ oven for curing for 2–3 minutes, and cooled before testing.

[0142] According to the national standard "GB / T39636~2020 Technical Specification for Fusion-Bonded Epoxy Powder Coating of Steel Pipes", performance tests were conducted on the powder-coated samples of Examples 1-3 and Comparative Examples 1-7. The test results are shown in the table below:

[0143] Table 1 Performance test results of graphene fusion-bonded epoxy powder coating

[0144]

[0145] The following conclusions can be drawn from the analysis of the test results:

[0146] Comparative analysis of Examples 1-3 and Comparative Example 4 shows that the compatibility of the graphene micro / nano composite pre-dispersion obtained by the dry surface treatment process with the fusion-bonded epoxy powder coating is significantly improved, and the cathodic stripping performance of the coating is enhanced.

[0147] The ratio of the total surface area of ​​graphene nanosheets to the sum of the total surface areas of other components characterizes the coverage or encapsulation degree of graphene nanosheets, and together with the loose packing density, constitutes a characteristic value for evaluating the surface treatment effect. The comparison between Example 1 and Comparative Examples 1, 2, and 3 shows that when the coverage of graphene nanosheets is between 0.96 and 1.1, the surface treatment effect of graphene nanosheets is better, that is, graphene is better dispersed in the dispersant and is better mixed with the powder coating, avoiding the agglomeration of graphene nanosheets. The sheet-like shielding effect of graphene is maximized, blocking or delaying the metal corrosion reaction. If the loose packing density of the graphene nanosheet composite material is too high or too low, it is not conducive to mixing and dispersing with other materials. High-density graphene nanosheet composite materials are characterized by being non-fluid and having poor flowability.

[0148] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0149] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0150] The foregoing has provided a detailed description of the graphene powder composite, its preparation method, and the fusion-bonded epoxy powder coating provided by this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for preparing a graphene powder composite, characterized in that, The preparation method includes: Graphene material and an inorganic dispersant in a mass ratio of 1–4:11–50 are stirred at high speed to disperse the graphene powder composite. The inorganic dispersant is composed of a first nanoscale compound, a second nanoscale compound, and a micron-scale compound in a mass ratio of 1–10:10–30:2–10.

2. The preparation method according to claim 1, characterized in that, The ratio of the total surface area of ​​the graphene material to the sum of the total surface areas of the remaining components in the graphene powder composite is 0.96–1.1, and the loose packing density of the graphene powder composite is 0.13 g / cm³. 3 ~0.2g / cm 3 .

3. The preparation method according to claim 1, characterized in that, The high-speed stirring time is no more than 120 seconds, and the high-speed stirring speed is 2000 r / min to 8000 r / min.

4. The preparation method according to claim 1, characterized in that, The graphene material is graphene oxide, hydrogenated graphene, nitrographene, or fluorinated graphene.

5. The preparation method according to claim 1, characterized in that, The first nanoscale compound is fumed silica, with a particle size of 5 nm to 50 nm and a specific surface area of ​​100 m². 2 / g~300m 2 / g.

6. The preparation method according to claim 1, characterized in that, The second nanoscale compound is one or more of titanium dioxide, silicon carbide, zirconium oxide, and silicon nitride, and the particle size of the second nanoscale compound is 10 nm to 500 nm, with a specific surface area of ​​10 m². 2 / g~100m 2 / g.

7. The preparation method according to claim 1, characterized in that, The micron-sized compound is one or more of boron nitride, silicon micro powder, barium sulfate, and wollastonite, and the particle size of the micron-sized compound is 0.5 μm to 10 μm.

8. The preparation method according to claim 1, characterized in that, The high-speed stirring of graphene material and inorganic dispersant in a mass ratio of 1-4:11-50 includes: The graphene material and the inorganic dispersant are transported by a high-speed inert gas stream to a mixer with a built-in high-speed stirrer for high-speed stirring.

9. A graphene powder composite, characterized in that, The graphene powder composite is obtained by the preparation method described in any one of claims 1-8.

10. A fusion-bonded epoxy powder coating, characterized in that, The fusion-bonded epoxy powder coating comprises the following components in parts by weight: 0.5 to 5 parts of the graphene powder composite as described in claim 9 above, 45 to 70 parts of epoxy resin, 8 to 30 parts of phenolic curing agent, 0.1 to 0.5 parts of pigment, 20 to 35 parts of filler, and 1 to 10 parts of other additives.

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