Coating compositions, methods for their preparation and coatings

Abstract

The present application relates to the field of paint, disclose a kind of paint composition and its preparation method and coating, the paint composition includes dispersion, the dispersion includes graphene, epoxy resin, polyether, filler and solvent;Wherein, with 100 mass parts of dispersion as benchmark, the content of graphene is 0.5-5 mass parts, the content of epoxy resin is 5-30 mass parts, the content of polyether is 0.5-2 mass parts, the content of filler is 30-75 mass parts.The coating formed by the paint composition shows high adhesion and wear resistance under a working pressure greater than 8MPa, while having excellent acid and alkali resistance, hydrogen sulfide resistance and carbon dioxide resistance.

Description

Technical Field

[0001] This invention relates to the field of coatings, and more specifically to a coating composition, its preparation method, and a coating layer. Background Technology

[0002] During oil and gas extraction, downhole metal equipment faces corrosion from dissolved oxygen, bacteria, under-deposit corrosion, CO2, and Cl. - In addition to corrosion from chemical media such as H2S, downhole metal equipment also suffers from abrasion from high-solids sand and gravel slurry on its surface and coatings, making corrosion prevention extremely difficult. Currently, solid powder coatings are commonly used for corrosion prevention of downhole metal equipment. However, this type of coating has high hardness, and when the metal equipment undergoes significant deformation, the coating is prone to brittle fracture and detachment, leading to well blockage and causing serious economic losses and safety hazards. Liquid coatings, with their high adhesion and good toughness, have become a research hotspot in downhole corrosion prevention in recent years.

[0003] CN117363171A discloses a special coating for oil drill pipe based on polyurethane modified epoxy resin, which solves the application needs of harsh working environments such as high temperature, high pressure and strong chemical corrosion downhole. However, the invention uses highly flexible epoxy resin, which has insufficient wear resistance and limited anti-corrosion effect under gravel conditions.

[0004] CN118256130A discloses a graphene-modified phenolic epoxy / polyurethane coating, which exhibits excellent anti-corrosion and anti-scaling properties, solving the technical problem of epoxy resin coating failure at high temperatures and enabling the coating to serve for extended periods in drilling and extraction conditions at 160℃. However, this invention also does not disclose its wear resistance data, and its corrosion resistance under high-solids-content sand and gravel slurry conditions cannot be determined.

[0005] Currently, there is limited research on high wear-resistant and corrosion-resistant coatings in this field. Developing liquid corrosion-resistant coatings with excellent wear resistance, good chemical corrosion resistance, high adhesion, and high toughness is a technical challenge in this field. Summary of the Invention

[0006] To overcome the problems of low adhesion and poor toughness of existing corrosion-resistant coatings, the present invention provides a coating composition, its preparation method and coating, which has excellent wear resistance and corrosion resistance, as well as high adhesion and toughness.

[0007] To achieve the above objectives, a first aspect of the present invention provides a coating composition comprising a dispersion containing graphene, an epoxy resin, a polyether, a filler, and a solvent;

[0008] Based on 100 parts by mass of dispersion, the content of graphene is 0.5-5 parts by mass, the content of epoxy resin is 5-30 parts by mass, the content of polyether is 0.5-2 parts by mass, and the content of filler is 30-75 parts by mass.

[0009] Preferably, the coating composition does not contain elemental zinc, aluminum, or magnesium and / or alloys.

[0010] Preferably, the coating composition further includes a curing agent system, which comprises a curing agent, a curing accelerator, and a solvent;

[0011] Based on a curing agent system of 100 parts by weight, the content of the curing agent is 15-60 parts and the content of the curing accelerator is 0.5-1 parts.

[0012] When not in use, the dispersion and curing agent system exist independently.

[0013] A second aspect of the present invention provides a method for preparing the coating composition provided in the first aspect of the present invention, the method comprising mixing graphene, epoxy resin, polyether, filler and solvent to obtain a dispersion. Preferably, the method further comprises mixing a curing agent, a curing accelerator and solvent to obtain a curing agent system.

[0014] A third aspect of the present invention provides a coating formed by curing a coating composition provided in the first aspect of the present invention.

[0015] The beneficial effects of this invention are as follows:

[0016] The coating composition provided by this invention contains graphene. The introduction of graphene extends the diffusion path of corrosive agents, solving the technical problem that traditional liquid coatings are not resistant to chemical corrosion under high pressure. This enables the coating to exhibit excellent acid and alkali resistance, hydrogen sulfide resistance, and carbon dioxide resistance under working pressure greater than 8 MPa.

[0017] The coating composition provided by this invention also incorporates polyether, which solves the problem of graphene dispersion in the liquid phase, increases the amount of graphene added in the high-viscosity resin system, and improves the overall corrosion resistance of the coating composition.

[0018] Compared with traditional liquid corrosion-resistant coatings containing metals such as zinc, tin, and aluminum, the coating composition provided by this invention has the advantages of good brushing performance (no bubbling, no peeling, and no sagging even at a thickness of 350μm) and simple construction process (both spraying and brushing are possible).

[0019] Furthermore, the epoxy resin in the coating composition provided by the present invention is preferably phenolic epoxy resin and bisphenol A type epoxy resin, which can further improve the high temperature resistance of the formed coating, while overcoming the defect of high coating brittleness caused by using phenolic epoxy resin alone, improving the adhesion of the coating, and ensuring the integrity of the coating under high deformation.

[0020] The coating composition provided by this invention further comprises modified mica. Modified mica and phenolic epoxy resin can significantly improve the wear resistance of the coating. The coating formed by the coating composition provided by this invention has an wear rate ≤15mg / 1000r (standard wear wheel, applied load 1kg), comparable to solid powder coatings and significantly superior to existing liquid coatings, ensuring the integrity of the coating under continuous friction from downhole sand and slurry. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] A first aspect of the present invention provides a coating composition comprising a dispersion containing graphene, an epoxy resin, a polyether, a filler, and a solvent;

[0023] Based on 100 parts by mass of dispersion, the content of graphene is 0.5-5 parts by mass, the content of epoxy resin is 5-30 parts by mass, the content of polyether is 0.5-2 parts by mass, and the content of filler is 30-75 parts by mass.

[0024] In this invention, graphene can extend the diffusion path of corrosive agents, and polyether can improve the dispersibility of graphene in the liquid phase. The two work synergistically to give the coating composition provided by this invention excellent corrosion resistance.

[0025] More preferably, based on 100 parts by mass of dispersion, the content of graphene is 0.5-2 parts by mass and the content of epoxy resin is 15-25 parts by mass.

[0026] According to a preferred embodiment of the present invention, the coating composition further includes a curing agent system, the curing agent system comprising a curing agent, a curing accelerator, and a solvent;

[0027] Based on a curing agent system of 100 parts by weight, the content of the curing agent is 15-60 parts, and the content of the curing accelerator is 0.5-5 parts.

[0028] When not in use, the dispersion and curing agent system exist independently.

[0029] In this invention, the curing agent system with the above-mentioned proportions can cure the dispersion to form a more robust and stable three-dimensional cross-linked structure, thereby further improving the chemical resistance and abrasion resistance of the coating formed by the coating composition provided by this invention.

[0030] According to the present invention, preferably, the mass ratio of the dispersion to the curing agent system is 3-10:1.

[0031] In this invention, when the mass ratio of the dispersion to the curing agent system is within the above-mentioned range, the coating composition can be better cured and crosslinked.

[0032] More preferably, the mass ratio of the dispersion to the curing agent system is 4-8:1.

[0033] According to a preferred embodiment of the present invention, the epoxy resin comprises phenolic epoxy resin and bisphenol A epoxy resin.

[0034] In this invention, a composite epoxy resin formulated with phenolic epoxy resin and bisphenol A epoxy resin is used, which can further improve the high temperature resistance and adhesion of the coating.

[0035] Preferably, the mass ratio of the phenolic epoxy resin to the bisphenol A epoxy resin is 0.5-2:1.

[0036] In this invention, when the mass ratio of the phenolic epoxy resin to the bisphenol A epoxy resin is within the above-mentioned range, the coating brittleness can be further improved, the coating toughness can be increased, and the impact resistance of the coating under pressure can be improved.

[0037] In this invention, when the median particle size of the graphene is within the above-mentioned range, the dispersion effect of the graphene sheet in the coating can be further improved under the action of polyether, resulting in a better shielding effect and superior chemical corrosion resistance of the constructed shielding layer; when the carbon content of the graphene is within the above-mentioned range, there are fewer defects on the graphene surface, resulting in a better shielding effect and superior corrosion resistance.

[0038] According to a preferred embodiment of the present invention, the polyether is a linear polyether.

[0039] In this invention, linear polyethers, compared to branched or cross-linked polyethers, can improve the wear resistance of the coating to a greater extent, while still maintaining a certain toughness at low temperatures and having strong hydrolysis resistance. They are also less prone to molecular chain breakage during long-term use in aquatic environments.

[0040] According to the present invention, preferably, the initiator of the polyether is 3,5,5-trimethyl-1-hexanol.

[0041] 3,5,5-Trimethyl-1-hexanol can enhance the intermolecular forces of polyether segments, thereby improving the thermal stability and chemical resistance of the polyether and thus the thermal stability and chemical resistance of the coating. 3,5,5-Trimethyl-1-hexanol can also enhance the hydrophobicity of the polyether segments, thus improving the hydrophobicity of the coating.

[0042] Preferably, the molar ratio of ethylene oxide to propylene oxide in the polyether is 1:1-1.1.

[0043] In this invention, when the molar ratio of ethylene oxide to propylene oxide in the polyether is within the above-mentioned range, the polyether can effectively improve the dispersibility of graphene while further enhancing the hydrophobicity of the coating.

[0044] According to a preferred embodiment of the present invention, the filler comprises flaky mica and contains at least one of aluminum tripolyphosphate, bentonite, talc, barium sulfate, carbon black, calcium carbonate and titanium dioxide.

[0045] According to the present invention, preferably, the content of the flaky mica is 2-8 parts by mass based on 100 parts by mass of the dispersion.

[0046] According to the present invention, preferably, the flaky mica is graphene-modified flaky mica, and the mass ratio of graphene to flaky mica is 0.1-2:100.

[0047] In this invention, the porous defects on the surface of modified sheet mica are covered by graphene, hindering the diffusion path of corrosive agents. Simultaneously, the acid and alkali resistance of the graphene-modified mica sheets is further improved, thereby enhancing the coating's pressure resistance and chemical corrosion resistance.

[0048] According to a preferred embodiment of the present invention, the curing agent is selected from at least one of phenolic amine, phenolic amide and polyamide.

[0049] In this invention, the introduction of the aforementioned curing agent improves the surface resistance of the coating, promotes rapid curing of the coating at low temperatures, and results in a light-colored appearance. Simultaneously, the curing agent imparts excellent corrosion resistance, good color stability, and extends the recoating cycle.

[0050] Preferably, the curing agent is cashew nut shell oil phenolic amine and / or cashew nut shell oil phenolic amide;

[0051] Preferably, the hydrogen equivalent of the curing agent is 120-200 g / mol.

[0052] According to a preferred embodiment of the present invention, the curing accelerator is selected from at least one of 2-aminophenol, 2,3-bis(dimethylaminomethyl)phenol and 2,4,6-tris(dimethylaminomethyl)phenol.

[0053] In this invention, the curing accelerator can synergistically enhance the crosslinking density of the coating with polyether, and, in combination with the flake mica and epoxy resin system, further improve the hardness of the coating and enhance the wear resistance of the product.

[0054] More preferably, the curing accelerator is 2-aminophenol.

[0055] According to the present invention, preferably, the solvent content in the dispersion is 10-25 parts by mass, and the solvent content in the curing agent system is 35-80 parts by mass.

[0056] In this invention, when the solvent content in the dispersion and curing agent system is within the above-mentioned range, it is more conducive to the coating composition and to improving the adhesion of the formed coating.

[0057] According to the present invention, preferably, the solvent in the dispersion and the solvent in the curing agent system are each independently selected from at least one of toluene, xylene, n-butyl acetate, propylene glycol methyl ether acetate, butanone, methyl isobutyl ketone, propylene glycol methyl ether, diethylene glycol ethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol butyl ether acetate, and ethyl acetate.

[0058] According to some specific embodiments of the present invention, the solvent is a mixed solvent of toluene, xylene, n-butyl acetate, propylene glycol methyl ether acetate, and diethylene glycol monobutyl ether.

[0059] In this invention, the above-mentioned mixed solvent can better disperse the compounded resin system and has better workability, avoiding the construction difficulties caused by the rapid volatility, poor wettability, and low viscosity of a single solvent.

[0060] According to the present invention, preferably, the coating composition does not contain elemental zinc, aluminum, or magnesium and / or alloys.

[0061] The coating composition provided by the present invention does not contain elemental zinc, aluminum, or magnesium and / or alloys, which can further improve the chemical resistance of the formed coating, especially the long-term chemical resistance.

[0062] A second aspect of the present invention provides a method for preparing the coating composition provided in the first aspect of the present invention, the method comprising mixing graphene, epoxy resin, polyether, filler and solvent to obtain a dispersion.

[0063] The specific content of the above components is as described in the first aspect of this invention.

[0064] In this invention, there is a wide range of options for the specific method of mixing graphene, epoxy resin, polyether, filler and solvent to obtain dispersion, as long as it can be fully mixed.

[0065] According to a preferred embodiment of the present invention, the method for preparing the dispersion includes the following steps:

[0066] (A-1) Mix at least one of aluminum tripolyphosphate, bentonite, talc, barium sulfate, carbon black, calcium carbonate, and titanium dioxide with graphene, polyether, and solvent, and shear and stir.

[0067] (A-2) Mix the epoxy resin with the mixture obtained in step (A-1) and grind it;

[0068] (A-3) Mix the flake mica with the mixture obtained in step (A-2) and shear and stir.

[0069] In this invention, shear stirring can efficiently and quickly mix the components in the dispersion, and can refine the component particles to make them uniformly dispersed, thereby further improving the chemical resistance of the coating.

[0070] According to the present invention, preferably, the median particle size of the graphene is 12-18 μm and the carbon content is 85-99.5 wt%.

[0071] According to the present invention, preferably, the method further includes mixing a curing agent, a curing accelerator and a solvent to obtain a curing agent system.

[0072] Preferably, the method for mixing the curing agent system is shear stirring.

[0073] In this invention, shear stirring can efficiently and quickly mix the components in the curing agent system, and can refine the component particles to make them uniformly dispersed, thereby further improving the chemical resistance of the coating.

[0074] The present invention allows for a wide range of choices regarding the specific method of shearing and stirring. According to some embodiments of the present invention, in step (A-1), the rotational speed of shearing and stirring is 800-2000 rpm, the time is 30-60 min, and the temperature is 30-50℃.

[0075] In step (A-3), the shearing and stirring speed is 800-1300 rpm, and the time is 20-30 min.

[0076] When mixing the curing agent, curing accelerator and solvent, the shear stirring speed is 800-1200 rpm and the time is 10-20 min.

[0077] According to some embodiments of the present invention, the grinding in step (A-2) is to grind to a fineness of ≤25μm using a grinding machine.

[0078] A third aspect of the present invention provides a coating formed by curing a coating composition provided in the first aspect of the present invention.

[0079] According to the present invention, preferably, the coating thickness is 80-300 μm.

[0080] Preferably, the coating composition is applied within 2 hours after the dispersion and curing agent system are mixed.

[0081] In this invention, the adhesion of the coating is 8-12 MPa, and the abrasion loss is ≤15 mg / 1000 rpm.

[0082] In this invention, the wear of the coating was measured using a Taber abrasion tester, in accordance with ASTM D4060, using a Taber CS-17Calibrase standard grinding wheel with a load of 1 kg.

[0083] The hydrogen sulfide resistance was determined according to GB / T4157-2006;

[0084] Salt spray resistance was tested according to GB / T1771-2007;

[0085] Coating adhesion was determined in accordance with GB / T1720-1979;

[0086] Before applying the coating, the substrate should be cleaned in accordance with GB / T8923.1-2011.

[0087] The present invention will be described in detail below through embodiments.

[0088] In the following examples, the graphene was prepared in-house, with a median particle size of 18 μm and a carbon content of 99.5 wt%.

[0089] The phenolic epoxy resin was purchased from Nan Ya Resin, brand name NPPN-631.

[0090] The bisphenol A type epoxy resin was purchased from Nan Ya Resin, brand name NPEL128.

[0091] The graphene-modified sheet mica was prepared in-house. It was obtained by acidifying graphene with nitric acid at pH=2, mixing it with sheet mica at a mass ratio of 0.3:100, shearing and stirring, and then filtering to remove the nitric acid.

[0092] The cashew nut shell oil phenolic amide was purchased from Cardläne, brand name LITE-3117, with a hydrogen equivalent of 150 g / mol.

[0093] Polyurethane additive, purchased from BYK, Germany, brand name BYK-163.

[0094] The preparation method of polyether A is as follows:

[0095] (1) Add 1g of 3,5,5-trimethyl-1-hexanol and 2g of potassium hydroxide to a high-temperature and high-pressure reactor, and seal the reactor. Before heating, purge and replace with nitrogen gas, then evacuate. Repeat this process at least twice. Start stirring and heat to 125°C. Add 40g of ethylene oxide to carry out the first polymerization reaction (the molar ratio of ethylene oxide to initiator is approximately 130:1). Control the reaction temperature at 140-150°C and the reaction pressure at 0.3-0.4 MPa. Continue stirring for 40 minutes until the pressure drops to 0 MPa.

[0096] (2) Heat the high-temperature and high-pressure reactor to 125°C, add 40g of propylene oxide to carry out the second polymerization reaction (the molar ratio of ethylene oxide to propylene oxide is 1:1), control the reaction temperature at 140-150°C, and control the reaction pressure at 0.3-0.4MPa. Stir for 30min to reduce the pressure to 0MPa.

[0097] (3) Turn on the vacuum pump and maintain it for 20 minutes to remove unreacted monomers and small molecules from the system. After the temperature of the reactor drops below 50°C, remove potassium hydroxide through neutralization, adsorption, and filtration to obtain polyether A.

[0098] The structure of polyether A was determined by nuclear magnetic resonance (NMR) 1H NMR spectroscopy, NMR 1H NMR spectroscopy, and NMR HMBC two-dimensional carbon-hydrogen correlation spectroscopy as follows:

[0099]

[0100] The molecular weight of polyether A was determined to be 480 g / mol using gas chromatography-mass spectrometry.

[0101] Polyether B was purchased from BASF, with the brand name PN-80.

[0102] The preparation method of polyether C is as follows:

[0103] Polyether A was prepared according to the following method, except that an equal amount of 1-pentanol was used to replace 3,5,5-trimethyl-1-hexanol to obtain polyether C, with the structure shown in the following formula:

[0104]

[0105] Wherein, R is -CH2CH2CH2CH2CH3, m=8, n=4, M=670g / mol.

[0106] All other raw materials and reagents were purchased commercially.

[0107] Examples and Comparative Examples

[0108] (1) Add graphene, polyether, filler and solvent to a shear mixer, set the speed to 1200 rpm, stir for 30 min, and control the temperature to 40℃.

[0109] (2) Mix the epoxy resin with the mixture obtained in step (1), transfer it to a sand mill, set the speed to 700 rpm, grind for 30 min, grind until the fineness is ≤25 μm, and the fineness is measured by a hanging plate fineness meter;

[0110] (3) Add the graphene-modified sheet mica and the mixture obtained in step (2) into a shear mixer, set the speed to 1200 rpm, and stir for 20 min to obtain a dispersion;

[0111] (4) Add the curing agent, curing accelerator and solvent to the shear mixer, set the speed to 1000 rpm and stir for 15 min to obtain the curing agent system. The dispersion and the curing agent system are combined to obtain the coating composition A1-A12 and D1-D6.

[0112] The specific types and contents of each component in the dispersion and curing agent system, as well as the formulation of the dispersion and curing agent system, are shown in Table 1. The solvent is a mixed solvent composed of toluene, xylene, n-butyl acetate, propylene glycol methyl ether acetate, and diethylene glycol monobutyl ether in a volume ratio of 1:1:1:0.5:1.

[0113] Table 1

[0114]

[0115] Table 1 (continued)

[0116]

[0117] Table 1 (continued)

[0118]

[0119] Example 13

[0120] The coating was prepared in accordance with the method of Example 1, except that flake mica was used instead of graphene-modified flake mica to obtain coating composition A13.

[0121] Example 14

[0122] The coating was prepared in accordance with the method of Example 1, except that polyether B was used instead of polyether A to obtain coating composition A14.

[0123] Example 15

[0124] The coating was prepared in accordance with the method of Example 1, except that polyether C was used instead of polyether A to obtain coating composition A15.

[0125] Comparative Example 7

[0126] The coating was prepared according to Example 1, except that polyurethane additive BYK-163 was used instead of polyether A to obtain coating composition D7.

[0127] Test case

[0128] After mixing the dispersion and curing agent system in the coating compositions obtained in the above examples and comparative examples, the mixture was sprayed onto the surface of a cleaned carbon steel substrate. Two coats were applied with a 2-hour interval between the two coats. The spraying pressure was 0.6 MPa, resulting in a 250 μm coating.

[0129] Referring to the method described in the specific embodiments of the present invention, the adhesion, abrasion loss, hydrogen sulfide resistance, and neutral salt spray resistance of the coating were measured, and the results are shown in Table 2.

[0130] Table 2

[0131] Adhesion (MPa) Wear rate (mg / 1000r) Hydrogen sulfide resistance (h) Neutral salt spray resistance (h) A1 12 8 1000 3000 A2 5 45 220 450 A3 10 6 880 2750 A4 12 8 820 2700 A5 10 10 780 2550 A6 6 14 720 2640 A7 11 10 850 2850 A8 12 13 950 2860 A9 12 5 960 2820 A10 10 20 840 2560 A11 12 8 720 2530 A12 11 15 830 2760 A13 12 27 980 2855 A14 12 13 750 2610 A15 12 8 820 2670 D1 12 8 120 300 D2 1 200 20 40 D3 12 9 980 2880 D4 11 15 850 2620 D5 12 6 905 2910 D6 8 23 450 2320 D7 10 15 550 2310

[0132] As can be seen from the results in Table 2, the coating formed by the coating composition provided by the present invention has stronger adhesion and lower abrasion, while also having better resistance to hydrogen sulfide and neutral salt spray.

[0133] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A coating composition, characterized in that, The coating composition includes a dispersion comprising graphene, epoxy resin, polyether, filler, and solvent; Based on 100 parts by mass of dispersion, the content of graphene is 0.5-5 parts by mass, the content of epoxy resin is 5-30 parts by mass, the content of polyether is 0.5-2 parts by mass, and the content of filler is 30-75 parts by mass.

2. The coating composition according to claim 1, characterized in that, The coating composition further includes a curing agent system, which comprises a curing agent, a curing accelerator, and a solvent; Based on a curing agent system of 100 parts by weight, the content of the curing agent is 15-60 parts, and the content of the curing accelerator is 0.5-5 parts. In the non-use state, the dispersion and curing agent system exist independently; Preferably, the mass ratio of the dispersion to the curing agent system is 3-10:

1.

3. The coating composition according to claim 1 or 2, characterized in that, The epoxy resin includes phenolic epoxy resin and bisphenol A epoxy resin; Preferably, the mass ratio of the phenolic epoxy resin to the bisphenol A epoxy resin is 0.5-2:

1.

4. The coating composition according to any one of claims 1-3, characterized in that, The polyether is a linear polyether; Preferably, the initiator of the polyether is 3,5,5-trimethyl-1-hexanol; Preferably, the molar ratio of ethylene oxide to propylene oxide in the polyether is 1:1-1.

1.

5. The coating composition according to any one of claims 1-4, characterized in that, The filler comprises flaky mica and at least one of aluminum tripolyphosphate, bentonite, talc, barium sulfate, carbon black, calcium carbonate, and titanium dioxide. Preferably, based on 100 parts by weight of dispersion, the content of the flaky mica is 2-8 parts by weight; Preferably, the flaky mica is graphene-modified flaky mica, and the mass ratio of graphene to flaky mica is 0.1-2:

100.

6. The coating composition according to any one of claims 2-5, characterized in that, The curing agent is selected from at least one of phenolic amine, phenolic amide and polyamide; Preferably, the curing agent is cashew nut shell oil phenolic amine and / or cashew nut shell oil phenolic amide; Preferably, the hydrogen equivalent of the curing agent is 120-200 g / mol.

7. The coating composition according to any one of claims 2-6, wherein the curing accelerator is selected from at least one of 2-aminophenol, 2,3-bis(dimethylaminomethyl)phenol and 2,4,6-tris(dimethylaminomethyl)phenol; Preferably, the solvent content in the dispersion is 10-25 parts by mass, and the solvent content in the curing agent system is 35-80 parts by mass; Preferably, the solvent in the dispersion and the solvent in the curing agent system are each independently selected from at least one of toluene, xylene, n-butyl acetate, propylene glycol methyl ether acetate, butanone, methyl isobutyl ketone, propylene glycol methyl ether, diethylene glycol ethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol butyl ether acetate, and ethyl acetate.

8. The coating composition according to any one of claims 1-7, characterized in that, The coating composition does not contain elemental zinc, aluminum, or magnesium and / or alloys thereof.

9. A method for preparing a coating composition according to any one of claims 1-8, characterized in that, The method involves mixing graphene, epoxy resin, polyether, filler and solvent to obtain a dispersion.

10. The method according to claim 9, characterized in that, The method for preparing the dispersion includes the following steps: (A-1) Mix at least one of aluminum tripolyphosphate, bentonite, talc, barium sulfate, carbon black, calcium carbonate, and titanium dioxide with graphene, polyether, and solvent, and shear and stir. (A-2) Mix the epoxy resin with the mixture obtained in step (A-1) and grind it; (A-3) Mix the flake mica with the mixture obtained in step (A-2) and shear and stir.

11. The method according to claim 10, characterized in that, The method further includes mixing a curing agent, a curing accelerator, and a solvent to obtain a curing agent system; Preferably, the graphene has a median particle size of 12-18 μm and a carbon content of 85-99.5 wt%.

12. A coating, characterized in that, The coating is formed by curing the coating composition according to any one of claims 1-8; Preferably, the coating thickness is 80-300 μm; Preferably, the adhesion of the coating is 8-12 MPa; Preferably, the abrasion rate of the coating is ≤15mg / 1000 rpm.

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