A graphene-modified phenolic epoxy and polyurethane coating, its preparation method, and its application.

Abstract

This invention discloses a graphene-modified phenolic epoxy and polyurethane coating, its preparation method, and its application, belonging to the field of petroleum pipe corrosion and protection technology. The preparation method includes the following steps: S1: Functionalized reduced graphene oxide is added to an organic solvent and mixed evenly to obtain dispersion A; S2: A first portion of phenolic epoxy resin is added to dispersion A and dispersed evenly to obtain dispersion B; S3: A second portion of phenolic epoxy resin is added to dispersion B and mixed evenly to obtain dispersion C. Then, a dispersing agent, polyurethane resin, and pigments / fillers are added to dispersion C and mixed evenly to obtain coating a; S4: Coating a is first ground, then a coupling agent, adhesion promoter, defoamer, and leveling agent are added and mixed evenly to obtain coating b; S5: Coating b is mixed evenly with a curing agent to obtain a graphene-modified phenolic epoxy / polyurethane coating.

Description

Technical Field

[0001] This invention belongs to the field of corrosion and protection technology for oil pipelines, specifically relating to a graphene-modified phenolic epoxy and polyurethane coating, its preparation method, and its application. Background Technology

[0002] At present, oil and gas exploration and development has moved towards deep wells of 10,000 meters, which puts forward higher requirements for the corrosion resistance and high temperature resistance of oil pipe anti-corrosion coatings. The anti-corrosion coating technology used in oil fields has the following problems: (1) Insufficient high temperature resistance. Due to the limitation of resin matrix materials, the long-term service temperature of epoxy and phenolic organic coatings is difficult to exceed 120℃. The recommended service temperature of epoxy coated oil pipes used in oil field water injection wells is generally not more than 80℃, and that of phenolic epoxy coatings is generally not more than 120℃; the coating of oil drill pipes used in drilling is generally not more than 148℃. However, with the development of deep and ultra-deep wells, the service temperature of oil pipes exceeds 160℃. In ultra-deep well conditions, the coatings used in oil fields often fail due to high temperature aging. (2) Insufficient anti-corrosion performance: In formation water, in addition to corrosive media such as chloride ions, carbon dioxide, and hydrogen sulfide, the coatings are also corroded and fail. (3) Poor anti-scaling performance: In formation water, in addition to corrosive media such as chloride ions and carbon dioxide, there are also microorganisms such as sulfate-reducing bacteria, planktonic bacteria, and iron bacteria, as well as scale-forming ions such as calcium ions and magnesium ions. Microorganisms, local scale deposits, and corrosion products deposit and interact on the surface of oil pipe coatings, causing scale formation on the oil pipe surface, resulting in under-deposit corrosion and difficulties in production operations. Therefore, there is an urgent need to obtain high-end coating protection technologies that can improve the service life and performance stability of oil pipes.

[0003] In recent years, graphene-modified coatings have attracted widespread attention due to their superior anti-corrosion properties. However, the application of graphene in anti-corrosion coatings currently faces challenges such as graphene dispersion. Due to its large specific surface area, graphene is prone to aggregation, often requiring functionalization to improve its dispersibility in organic solvents. Furthermore, there is a lack of targeted fundamental research on the performance and microstructure changes of graphene coatings in user-end applications, as well as a lack of corresponding testing and evaluation standards and long-term service performance assessments under actual working conditions. This severely limits its large-scale application. Consequently, performance studies of graphene-modified coatings in high-temperature and high-pressure downhole environments are rarely reported, and there are no related large-scale engineering applications. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a graphene-modified phenolic epoxy and polyurethane coating, its preparation method and application. Oil pipes coated with the graphene-modified phenolic epoxy / polyurethane coating can be used for a long time in drilling and production conditions at 160°C, and have excellent anti-corrosion and anti-scaling properties.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] This invention provides a method for preparing graphene-modified phenolic epoxy and polyurethane coatings, comprising the following steps:

[0007] S1: Functionalized reduced graphene oxide is added to an organic solvent and mixed evenly to obtain dispersion A;

[0008] S2: Add the first phenolic epoxy resin to dispersion A and disperse it evenly to obtain dispersion B;

[0009] S3: Add the second part of phenolic epoxy resin to dispersion B and mix evenly to obtain dispersion C. Then add dispersing agent, polyurethane resin and pigments and fillers to dispersion C in sequence and mix evenly to obtain coating a.

[0010] S4: First, grind the coating a, then add the coupling agent, adhesion promoter, defoamer and leveling agent, and mix evenly to obtain coating b;

[0011] S5: Mix coating b with curing agent evenly to obtain graphene-modified phenolic epoxy / polyurethane coating.

[0012] Furthermore, in step S1, the method for preparing the functionalized reduced graphene oxide includes the following steps:

[0013] S11: Nano-yttrium stabilized zirconium oxide / yttrium oxide and isobutyltriethoxysilane are uniformly mixed in anhydrous ethanol to obtain mixed system a. Mixed system a is then kept at a certain temperature to obtain reaction solution a. The products in reaction solution a are separated, washed, and dried to obtain nano-yttrium stabilized zirconium oxide / yttrium oxide coated with isobutyltriethoxysilane.

[0014] S12: Take a portion of reduced graphene oxide and isobutyltriethoxysilane and mix them evenly in anhydrous ethanol to obtain mixed system b. Then, keep mixed system b at a certain temperature to obtain reaction solution b. After separating the product in reaction solution b, wash and dry it to obtain isobutyltriethoxysilane modified reduced graphene oxide.

[0015] S13: Isobutyltriethoxysilane-modified reduced graphene oxide is uniformly dispersed in DMF to obtain suspension a. Then, isobutyltriethoxysilane-coated nano-yttrium stabilized zirconium oxide / yttrium oxide is added to suspension a and uniformly dispersed to obtain suspension b. Finally, suspension b is kept at a certain temperature to obtain reaction solution c. The products in reaction solution c are separated, washed, and dried to obtain functionalized reduced graphene oxide.

[0016] Furthermore, in S12, the atomic ratio of C:H:O in the partially reduced graphene oxide is 7:1:1.

[0017] Furthermore, in S11, the weight ratio of the nano-yttrium stabilized zirconium oxide / yttrium oxide, isobutyltriethoxysilane, and anhydrous ethanol is (5-10):(31-50):300.

[0018] In step S12, the weight ratio of the reduced graphene oxide, isobutyltriethoxysilane, and anhydrous ethanol is (1.3-1.5):(22-28):300.

[0019] In S13, the weight ratio of the isobutyltriethoxysilane-modified reduced graphene oxide and the isobutyltriethoxysilane-coated nano-yttrium-stabilized zirconium oxide / yttrium oxide is (1.6-2.5):(5-10).

[0020] Furthermore, in S1, the weight ratio of the functionalized reduced graphene oxide to the organic solvent is (0.6-2):(9-10);

[0021] In S2, the weight ratio of the first phenolic epoxy resin to the organic solvent in dispersion A is (1-2):(9-10).

[0022] In step S3, the weight ratio of the second phenolic epoxy resin to the organic solvent in dispersion A is (6-12):(9-10).

[0023] In S3, the weight ratio of the dispersing agent, polyurethane resin, pigments and fillers in the coating a to the organic solvent in the dispersion A is (0.07-0.12):(40-42):(27-30):(9-10).

[0024] Furthermore, in S1, the organic solvent is one or a mixture of n-butanol or cyclohexanone in any ratio;

[0025] In step S3, the pigments and fillers include carbon black, talc, barium sulfate, mica iron oxide, and silicon carbide; the weight ratio of carbon black, talc, barium sulfate, mica iron oxide, and silicon carbide is 1:3:5:3:2; and the dispersing agent is BYK-163.

[0026] Furthermore, in step S4, the weight ratio of the coupling agent, adhesion promoter, defoamer, and leveling agent is 3:1.5:2:4:1;

[0027] The weight ratio of the defoamer to the organic solvent in dispersion A is (0.1-0.18):(9-10).

[0028] Furthermore, in step S5, the curing agent is a compound solution of alicyclic modified amine and isophorone diisocyanate curing agent; the weight ratio of the alicyclic modified amine to the isophorone diisocyanate curing agent is 1:4.

[0029] The present invention also discloses a graphene-modified phenolic epoxy and polyurethane coating, which comprises component A and component B by weight percentage.

[0030] Component A includes: phenolic epoxy resin, polyurethane resin, functionalized reduced graphene oxide, pigments and fillers, organic solvents and additives; Component B is a curing agent.

[0031] The composition of component A is as follows: phenolic epoxy resin: 9%–10%; polyurethane resin: 40%–42%; functionalized reduced graphene oxide: 0.6%–2%; pigments and fillers: 27%–30%; additives: 0.54%–0.97%; organic solvents: 9%–10%; and component B: 7.5%–10%.

[0032] The application of graphene-modified phenolic epoxy and polyurethane coatings prepared by any one of the methods described above in oil and gas drilling and production pipelines.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention provides a method for preparing graphene-modified phenolic epoxy and polyurethane coatings. Utilizing ultrafine YSZ and micro-particle Y2O3, their unique surface and small-size effects allow them to undergo a grafting reaction with IBTEO in an extremely unstable quasi-solid state with high surface activity. By sharing "O" atoms, IBTEO encapsulates the YSZ and Y2O3 nanoparticles, achieving efficient dispersion and organic fusion of organic materials (IBTEO) and inorganic materials (YSZ and Y2O3). Furthermore, by adding phenolic epoxy resin twice, the resin encapsulates the functionalized reduced graphene oxide, preventing agglomeration and improving the dispersibility of graphene in organic solvents.

[0035] Furthermore, by addressing the requirements for impermeability, pore filling, density design (anti-settling), and organic integration with the organic coating, the material structure was designed, inverted, and experimentally verified. Partially reduced graphene oxide (C:H:O = 7:1:1) was used as the raw material. The hydroxyl and carboxyl groups retained in the partially reduced graphene oxide were used to undergo a dehydration reaction with IBTEO to prepare IBTEO-modified b-RGO. This achieved efficient dispersion and organic integration of organic materials (IBTEO) and inorganic materials (b-RGO) while retaining the beneficial effect of the hydrophobicity of partially reduced graphene oxide.

[0036] Furthermore, IBTEO-modified b-RGO was uniformly dispersed in DMF, and then IBTEO-coated YSZ and Y2O3 were added to obtain functionalized reduced graphene oxide. This resulted in a functionalized partially reduced graphene oxide (b-RGO—IBTEO—DMF—IBTEO—YSZ / Y2O3) that combines the high impermeability, corrosion resistance, high toughness, and superhydrophobic properties of graphene with the wear resistance and corrosion resistance of Y2O3, as well as the bactericidal and anti-scaling properties of rare earth elements (Y) and rare earth oxides (Y2O3). Moreover, the average density of the organically combined components is close to that of the resin matrix, effectively solving the problems of single b-RGO floating and single YSZ / Y2O3 sinking in coatings.

[0037] This invention, based on the operational requirements of oil and gas drilling and production, and considering the functional differences of each component, precisely designs each coating composition, including the addition of high-temperature resistant phenolic epoxy resin, toughened and reinforced high-temperature resistant polyurethane resin, matched dispersants, pigments, fillers, curing agents, and precise control over coating fineness (less than 15 micrometers) and coating preparation process. This achieves unexpected long-lasting (over 5 years) effects in oil and gas drilling and production under high pressure (up to 70 MPa), high salinity (150,000 PPM), and 160°C conditions.

[0038] The coating of this invention has a temperature resistance of up to 170°C and excellent anti-corrosion and anti-scaling properties in drilling and production conditions at or below 160°C. Detailed Implementation

[0039] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0040] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0041] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0042] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0043] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0044] This invention provides a graphene-modified phenolic epoxy and polyurethane coating, its preparation method, and its application.

[0045] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0046] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0047] This invention relates to a graphene-modified phenolic epoxy / polyurethane coating, its preparation method, and its application. Specifically, it is a functionalized reduced graphene oxide-modified phenolic epoxy / polyurethane coating that can withstand high temperatures of up to 160℃ for use in oil and gas drilling and production.

[0048] A graphene-modified phenolic epoxy and polyurethane coating, comprising component A and component B by weight percentage,

[0049] Component A includes: phenolic epoxy resin, polyurethane resin, functionalized reduced graphene oxide, pigments and fillers, organic solvents and additives, and component B is a curing agent.

[0050] Component A contains: phenolic epoxy resin: 9%–10%; polyurethane resin: 40%–42%; functionalized reduced graphene oxide (F-RGO): 0.6%–2%; pigments and fillers: 27%–30%; additives: 0.54%–0.97%; and organic solvents: 9%–10%. The additives include dispersants, coupling agents, adhesion promoters, defoamers, and leveling agents.

[0051] Component B: 7.5%–10%; Component B is a curing agent, consisting of a 1:4 mixture of alicyclic modified amine and isophorone diisocyanate curing agent.

[0052] As an optional option, pigments and fillers: 27% to 30%, specifically including carbon black, talc, barium sulfate, mica iron oxide, and silicon carbide, in a weight ratio of 1:3:5:3:2;

[0053] As an optional component, the additives are 0.54% to 0.97%, specifically including dispersants, coupling agents, adhesion promoters, defoamers, and leveling agents, in a weight ratio of 3:1.5:2:4:1.

[0054] The dispersant is BYK-163, the coupling agent is H570, the adhesion promoter is 4511, the defoamer is BYK-065N, and the leveling agent is BYK-336.

[0055] Among them, coupling agents promote the cross-linking reaction between resin and curing agent, and between functionalized reduced graphene oxide and resin; adhesion promoters can improve coating adhesion; defoamers promote the dissipation of foam in coatings; and leveling agents can improve the leveling properties of coatings and ensure a smooth coating.

[0056] As an optional option, the organic solvent is 9% to 10%, wherein the organic solvent is one or a mixture of n-butanol or cyclohexanone in any ratio, preferably a 1:1 mixture of n-butanol and cyclohexanone;

[0057] The specific preparation method of functionalized reduced graphene oxide is as follows:

[0058] Step 1: Add 5-10g of nano-yttrium stabilized zirconium oxide / yttrium oxide (YSZ / Y2O3) and 31-50g of silane coupling agent isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol. The nano-YSZ / Y2O3 particles have a diameter of less than 30nm. Mix them uniformly by ultrasonication, and then stir at 78-81℃ for 2-3h. At the same time, add 25g of distilled water to the above solution.

[0059] Finally, the mixture was filtered and washed six times with distilled water and anhydrous ethanol, and then dried in an oven at 60°C for 24 hours to obtain IBTEO-coated YSZ / Y2O3, abbreviated as IBTEO / YSZ / Y2O3.

[0060] As an optional scheme, the weight ratio of nano-yttrium stabilized zirconium oxide / yttrium oxide, isobutyltriethoxysilane (IBTEO) to anhydrous ethanol is (5-10):(31-50):300.

[0061] The particle size of the YSZ / Y2O3 mixture is less than 30 nm. Before uniform mixing, the particle size of YSZ is less than 10 nm and the particle size of Y2O3 is less than 30 nm. The weight ratio of the two is 1:1.

[0062] Step 2: Add 1.3–1.5 g of partially reduced graphene oxide (b-RGO) and 22–28 g of isobutyltriethoxysilane (IBTEO) to 300 g of anhydrous ethanol, mix them uniformly by ultrasonication, and then stir at 78–81 °C for 8–9 h. At the same time, slowly add 30 g of distilled water to the above solution.

[0063] Finally, the nanomaterials were filtered and washed 10 times with distilled water and anhydrous ethanol, and dried in an oven at 60°C for 24 hours to obtain IBTEO-modified b-RGO, abbreviated as IBTEO / b-RGO.

[0064] As an optional scheme, the weight ratio of partially reduced graphene oxide, isobutyltriethoxysilane and anhydrous ethanol is (1.3-1.5):(22-28):300.

[0065] Partially reduced graphene oxide is a commercially available product. The difference is that, apart from a very small amount of impurities, the C:H:O ratio is different. In this invention, the C:H:O ratio of the partially reduced graphene oxide is 7:1:1.

[0066] Step 3: Add 1.6–2.5 g of IBTEO / b-RGO to 1 liter of DMF to form a homogeneous suspension. Then add 5–10 g of IBTEO / YSZ / Y2O3 to the above suspension and sonicate for 0.5–1 hour to form a homogeneous suspension.

[0067] Finally, the mixture was stirred at 80–86 °C for 2–3 h. The mixture was then filtered and washed five times with distilled water and ethanol, and dried in an oven at 60 °C for 24 h to obtain functionalized reduced graphene oxide.

[0068] As an optional option, the ratio of IBTEO / b-RGO, IBTEO / YSZ / Y2O3 and DMF is (1.6~2.5)g:(5~10)g:1000mL.

[0069] The specific surface area of ​​functionalized reduced graphene oxide is 300–450 m². 2 / g, with a sheet size of 1.0~2.5μm, such thinner and smaller layers are more likely to form a labyrinth effect in the coating, resulting in a coating with better impermeability and corrosion resistance, and less functionalized reduced graphene oxide is required to achieve the same performance.

[0070] The price of functionalized reduced graphene oxide prepared by the redox method is as low as 2 yuan / gram; therefore, compared with high-end novel coatings / platings costing 300 yuan / square meter, the modified polyurethane coating formed using this functionalized reduced graphene oxide costs approximately 180 yuan / square meter, making it more economical. The specific surface area of ​​functionalized reduced graphene oxide is 300–450 m² / g. 2 / g, thus adding a small amount of functionalized reduced graphene oxide can significantly improve the performance of the coating.

[0071] The preparation method of the above-mentioned high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating is as follows.

[0072] A method for preparing graphene-modified phenolic epoxy and polyurethane coatings includes the following steps:

[0073] Step 1: Add functionalized reduced graphene oxide to an organic solvent and sonicate to obtain a functionalized reduced graphene oxide dispersion. The sonication time is 100-120 min and the sonication frequency is 9 kHz.

[0074] Step 2: Add 14.2% of the total mass of phenolic epoxy resin to the functionalized reduced graphene oxide dispersion from Step 1. After mechanical stirring until homogeneous, sonicate to obtain a functionalized reduced graphene oxide phenolic epoxy resin mixture. The phenolic epoxy resin encapsulates the graphene to prevent agglomeration. The number of functionalized reduced graphene oxide layers after dispersion is 1–5. The sonication time is 180 min, and the sonication frequency is 5 kHz.

[0075] Step 3: Add the functionalized reduced graphene oxide phenolic epoxy resin mixture prepared in Step 2 to the remaining phenolic epoxy resin and stir for 20 minutes until uniformly mixed; then add the dispersing agent and stir at high speed for 20 minutes until uniformly mixed; then add the polyurethane resin and stir for 15 minutes until uniformly mixed; finally add pigments and fillers to obtain the coating.

[0076] Step 4: Grind the coating from Step 3 for 1 hour to obtain a coating fineness of less than 15 μm. This will make the sprayed coating smoother and promote the dispersion of functionalized reduced graphene oxide. Then add coupling agent, adhesion promoter, defoamer and leveling agent, and stir at high speed for 10 minutes to obtain component A.

[0077] Step 5: Mix component A with component B to obtain a functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating that can withstand high temperatures up to 160℃.

[0078] As an optional embodiment, the weight ratio of the organic solvent, functionalized reduced graphene oxide, functionalized reduced graphene oxide phenolic epoxy resin mixture, remaining phenolic epoxy resin, dispersant, polyurethane resin, pigments and fillers, and defoamer is (9-10):(0.6-2):(1-2):(6-12):(0.07-0.12):(40-42):(27-30):(0.1-0.18).

[0079] The stirring speed in this invention is 150-180 r / min.

[0080] The application of graphene-modified phenolic epoxy and polyurethane coatings obtained by any one of the methods described above in oil and gas drilling and production pipelines, namely, a method for preparing an oil pipe coated with the above-mentioned high-temperature resistant (160℃) functionalized reduced graphene oxide-modified phenolic epoxy / polyurethane coating, includes the following steps:

[0081] The surface of the tubing to be coated is pretreated according to the national standard GB / T 8923.1. Thinner is added to the 160℃ high-temperature resistant functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating to adjust the viscosity to 70-90 cst. Then, it is sprayed onto the pretreated tubing and cured at medium to high temperature to obtain a tubing coated with a 160℃ high-temperature resistant graphene modified phenolic epoxy / polyurethane coating for water injection wells. The resulting coating thickness is 160-190 μm as required by industry applications.

[0082] In this invention, the medium-temperature curing temperature is 80–100°C, and the medium-temperature curing time is 1–1.5 hours; the high-temperature curing temperature is 120–140°C, and the high-temperature curing time is 2–3 hours. The invention allows for a single spray coating to achieve the desired shape.

[0083] Example 1

[0084] The specific formula for the paint is as follows:

[0085] Phenolic epoxy resin: 9%; Polyurethane resin: 41.22%; Functionalized reduced graphene oxide: 0.6%; Pigments and fillers: 30%; Additives: 0.68%; Curing agent: 9%; Organic solvent: 9.5%;

[0086] The preparation method includes the following steps:

[0087] Step 1: Add 5g of nano-sized yttrium-stabilized zirconium oxide / yttrium oxide (YSZ / Y2O3) and 31g of silane coupling agent isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol. The nano-sized YSZ / Y2O3 particles have a diameter of less than 30nm. Mix them uniformly using ultrasound, and then stir at 78℃ for 2h. Simultaneously, add 25g of distilled water to the above solution. Finally, filter and wash 6 times with distilled water and anhydrous ethanol, and then dry in an oven at 60℃ for 24 hours to obtain IBTEO-coated YSZ / Y2O3 (abbreviated as IBTEO / YSZ / Y2O3).

[0088] Step 2: Add 1.3g of partially reduced graphene oxide (b-RGO) and 22g of isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol, mix them uniformly by ultrasonication, and then stir at 78℃ for 8 hours. Simultaneously, slowly add 30g of distilled water to the solution. Finally, filter the nanomaterial and wash it 10 times with distilled water and anhydrous ethanol, then dry it in an oven at 60℃ for 24 hours to obtain IBTEO-modified b-RGO, abbreviated as IBTEO / b-RGO.

[0089] It should be noted that partially reduced graphene oxide is an existing product on the market. The difference is that, apart from a very small amount of impurities, the C:H:O ratio is different. In the partially reduced graphene oxide of this invention, the C:H:O ratio is 7:1:1.

[0090] Step 3: Add 1.6 g of IBTEO / b-RGO to 1 L of DMF to form a homogeneous suspension. Then add 5 g of IBTEO / YSZ / Y2O3 to the above suspension and sonicate for 0.5 h to form a homogeneous suspension. Finally, stir at 80 °C for 2 h. Filter the mixture and wash it five times with distilled water and ethanol, then dry it in an oven at 60 °C for 24 h to obtain functionalized reduced graphene oxide.

[0091] The specific surface area of ​​functionalized reduced graphene oxide is 300 m². 2 / g, with a sheet size of 1.0~2.5μm, such thinner and smaller layers are more likely to form a labyrinth effect in the coating, resulting in a coating with better impermeability and corrosion resistance, and less functionalized reduced graphene oxide is required to achieve the same performance.

[0092] The preparation method of the above-mentioned high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating includes the following steps, based on the above weight percentages:

[0093] Step 1: Add 6g of functionalized reduced graphene oxide to 95g of organic solvent prepared by mixing 47.5g of n-butanol and 47.5g of cyclohexanone in a 1:1 ratio, and sonicate to obtain a dispersion of functionalized reduced graphene oxide. The sonication time is 100min and the sonication frequency is 9KHZ.

[0094] Step 2: Add 14.2% (12.86g) of the total mass of 90g phenolic epoxy resin to the functionalized reduced graphene oxide dispersion from Step 1. After mechanical stirring until homogeneous, sonicate to obtain a functionalized reduced graphene oxide phenolic epoxy resin mixture. The phenolic epoxy resin encapsulates the graphene, preventing agglomeration. The number of functionalized reduced graphene oxide layers after dispersion is 1-5. The sonication time is 180min, and the sonication frequency is 5kHz.

[0095] Step 3: Add the functionalized reduced graphene oxide phenolic epoxy resin mixture prepared in Step 2 to the remaining 77.14g of phenolic epoxy resin, and stir for 20min until uniformly mixed; then add 1.77g of dispersant, and stir at high speed for 20min until uniformly mixed; then add 412.2g of polyurethane resin, and stir for 15min until uniformly mixed; finally add 300g of pigments and fillers to obtain the coating.

[0096] Step 4: Grind the coating from Step 3 for 1 hour to obtain a coating fineness of less than 15 μm. This will make the sprayed coating smoother and promote the dispersion of functionalized reduced graphene oxide. Then add 5.03 g of additives and stir at high speed for 10 minutes to obtain component A.

[0097] Step 5: Mix component A with 90g of component B, wherein the 90g of component B includes 18g of alicyclic modified amine and 72g of isophorone diisocyanate, to obtain a functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating resistant to high temperature of 160℃.

[0098] The stirring speed in this invention is 150 r / min.

[0099] A method for preparing an oil pipe coated with a high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating includes the following steps: pretreating the surface of the oil pipe to be coated according to national standard GB / T8923.1; adding thinner to the high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating to adjust the viscosity to 70 cst, then spraying it onto the pretreated oil pipe, and curing at medium to high temperature to obtain an oil pipe coated with a high-temperature resistant (160℃) graphene modified phenolic epoxy / polyurethane coating for water injection wells, with a coating thickness of 160–190 μm as required by industry applications. The medium-temperature curing temperature is 80℃ for 1 hour; the high-temperature curing temperature is 120℃ for 2 hours. This invention allows for a single coating application.

[0100] Example 2

[0101] The specific formulation of the coating is as follows: phenolic epoxy resin: 10%; polyurethane resin: 42%; functionalized reduced graphene oxide: 1.46%; pigments and fillers: 27%; additives: 0.54%; curing agent: 10%; organic solvent: 9.0%;

[0102] Step 1: Add 10g of nano-yttrium-stabilized zirconium oxide / yttrium oxide (YSZ / Y2O3) and 50g of silane coupling agent isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol. The nano-YSZ / Y2O3 particles have a diameter of less than 30nm. Mix them uniformly using ultrasound, and then stir at 81℃ for 3h. Simultaneously, add 25g of distilled water to the above solution. Finally, filter and wash 6 times with distilled water and anhydrous ethanol, and then dry in an oven at 60℃ for 24h to obtain IBTEO-coated YSZ / Y2O3 (abbreviated as IBTEO / YSZ / Y2O3).

[0103] Step 2: Add 1.5g of partially reduced graphene oxide (b-RGO) and 28g of isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol, mix them uniformly by ultrasonication, and then stir at 81℃ for 9h. Simultaneously, slowly add 30g of distilled water to the solution. Finally, filter the nanomaterial and wash it 10 times with distilled water and anhydrous ethanol, then dry it in an oven at 60℃ for 24h to obtain IBTEO-modified b-RGO, abbreviated as IBTEO / b-RGO.

[0104] It should be noted that partially reduced graphene oxide is an existing product on the market. The difference is that, apart from a very small amount of impurities, the C:H:O ratio is different. In the partially reduced graphene oxide of this invention, the C:H:O ratio is 7:1:1.

[0105] Step 3: Add 2.5 g of IBTEO / b-RGO to 1 L of DMF to form a homogeneous suspension. Then add 10 g of IBTEO / YSZ / Y2O3 to the above suspension and sonicate for 1 h to form a homogeneous suspension. Finally, stir at 86 °C for 3 h. Filter the above mixture and wash it five times with distilled water and ethanol, then dry it in an oven at 60 °C for 24 h to obtain functionalized reduced graphene oxide.

[0106] The specific surface area of ​​functionalized reduced graphene oxide is 450 m². 2 / g, with a sheet size of 1.0~2.5μm, such thinner and smaller layers are more likely to form a labyrinth effect in the coating, resulting in a coating with better impermeability and corrosion resistance, and less functionalized reduced graphene oxide is required to achieve the same performance.

[0107] The preparation method of the above-mentioned high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating includes the following steps, based on the above weight percentages:

[0108] Step 1: Add 14.6g of functionalized reduced graphene oxide to 90g of organic solvent prepared by mixing 45g of n-butanol and 45g of cyclohexanone in a 1:1 ratio, and sonicate to obtain a functionalized reduced graphene oxide dispersion. The sonication time is 120min and the sonication frequency is 9KHZ.

[0109] Step 2: Add 14.2% of the total mass of 100g phenolic epoxy resin to the functionalized reduced graphene oxide dispersion from Step 1. After mechanical stirring until homogeneous, sonicate to obtain a functionalized reduced graphene oxide phenolic epoxy resin mixture. The phenolic epoxy resin encapsulates the graphene to prevent agglomeration. The number of functionalized reduced graphene oxide layers after dispersion is 1-5. The sonication time is 180 min, and the sonication frequency is 5 kHz.

[0110] Step 3: Add the functionalized reduced graphene oxide phenolic epoxy resin mixture prepared in Step 2 to the remaining phenolic epoxy resin and stir for 20 minutes until uniformly mixed; then add 1.4g of dispersant and stir at high speed for 20 minutes until uniformly mixed; then add 420g of polyurethane resin and stir for 15 minutes until uniformly mixed; finally add 270g of pigments and fillers to obtain the coating.

[0111] Step 4: Grind the coating from Step 3 for 1 hour to obtain a coating fineness of less than 15 μm. This will make the sprayed coating smoother and promote the dispersion of functionalized reduced graphene oxide. Then add 4 g of additives and stir at high speed for 10 minutes to obtain component A.

[0112] Step 5: Mix component A with 100g of component B, wherein 100g of component B includes 20g of alicyclic modified amine and 80g of isophorone diisocyanate, to obtain a functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating resistant to high temperature of 160℃.

[0113] The stirring speed in this invention is 170 r / min.

[0114] A method for preparing an oil pipe coated with a high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating includes the following steps: pretreating the surface of the oil pipe to be coated according to national standard GB / T8923.1; adding thinner to the high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating to adjust the viscosity to 90 cSt, then spraying it onto the pretreated oil pipe, and curing at medium to high temperature to obtain an oil pipe coated with a high-temperature resistant (160℃) graphene modified phenolic epoxy / polyurethane coating for water injection wells, with a coating thickness of 160–190 μm as required by industry applications. The medium-temperature curing temperature is 100℃ for 1.5 h; the high-temperature curing temperature is 140℃ for 3 h. This invention allows for a single coating application.

[0115] Example 3

[0116] The specific formulation of the coating is as follows: phenolic epoxy resin: 9.5%; polyurethane resin: 40%; functionalized reduced graphene oxide: 2%; pigments and fillers: 28%; additives: 0.97%; curing agent: 9.53%; organic solvent: 10%;

[0117] Step 1: Add 8g of nano-yttrium-stabilized zirconium oxide / yttrium oxide (YSZ / Y2O3) and 40g of silane coupling agent isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol. The nano-YSZ / Y2O3 particles have a diameter of less than 30nm. Mix the mixture uniformly using ultrasound, and then stir at 80℃ for 2.5h. Simultaneously, add 25g of distilled water to the solution. Finally, filter and wash 6 times with distilled water and anhydrous ethanol, and then dry in an oven at 60℃ for 24 hours to obtain IBTEO-coated YSZ / Y2O3 (abbreviated as IBTEO / YSZ / Y2O3).

[0118] Step 2: Add 1.4g of partially reduced graphene oxide (b-RGO) and 25g of isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol, mix them uniformly by ultrasonication, and then stir at 80℃ for 8.5h. Simultaneously, slowly add 30g of distilled water to the solution. Finally, filter the nanomaterial and wash it 10 times with distilled water and anhydrous ethanol, then dry it in an oven at 60℃ for 24h to obtain IBTEO-modified b-RGO, abbreviated as IBTEO / b-RGO.

[0119] It should be noted that partially reduced graphene oxide is an existing product on the market. The difference is that, apart from a very small amount of impurities, the C:H:O ratio is different. In the partially reduced graphene oxide of this invention, the C:H:O ratio is 7:1:1.

[0120] Step 3: Add 2.0 g of IBTEO / b-RGO to 1 L of DMF to form a homogeneous suspension. Then add 5-10 g of IBTEO / YSZ / Y2O3 to the above suspension and sonicate for 0.8 h to form a homogeneous suspension. Finally, stir at 84 °C for 2.5 h. Filter the above mixture and wash it five times with distilled water and ethanol, then dry it in an oven at 60 °C for 24 h to obtain functionalized reduced graphene oxide.

[0121] The specific surface area of ​​functionalized reduced graphene oxide is 400 m². 2 / g, with a sheet size of 1.0~2.5μm, such thinner and smaller layers are more likely to form a labyrinth effect in the coating, resulting in a coating with better impermeability and corrosion resistance, and less functionalized reduced graphene oxide is required to achieve the same performance.

[0122] The preparation method of the above-mentioned high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating includes the following steps, based on the above weight percentages:

[0123] Step 1: Add 20g of functionalized reduced graphene oxide to 100g of organic solvent and sonicate to obtain a functionalized reduced graphene oxide dispersion. The sonication time is 110min and the sonication frequency is 9KHZ.

[0124] Step 2: Add 14.2% of the total mass of 95g phenolic epoxy resin to the functionalized reduced graphene oxide dispersion from Step 1. After mechanical stirring until homogeneous, sonicate to obtain a functionalized reduced graphene oxide phenolic epoxy resin mixture. The phenolic epoxy resin encapsulates the graphene to prevent agglomeration. The number of functionalized reduced graphene oxide layers after dispersion is 1-5. The sonication time is 180 min, and the sonication frequency is 5 kHz.

[0125] Step 3: Add the functionalized reduced graphene oxide phenolic epoxy resin mixture prepared in Step 2 to the remaining phenolic epoxy resin and stir for 20 minutes until uniformly mixed; then add 2.53g of dispersant and stir at high speed for 20 minutes until uniformly mixed; then add 400g of polyurethane resin and stir for 15 minutes until uniformly mixed; finally add 280g of pigments and fillers to obtain the coating.

[0126] Step 4: Grind the coating from Step 3 for 1 hour to obtain a coating fineness of less than 15 μm. This will make the sprayed coating smoother and promote the dispersion of functionalized reduced graphene oxide. Then add 7.17 g of additives and stir at high speed for 10 min to obtain component A.

[0127] Step 5: Mix component A with 95.3g of component B to obtain a high-temperature resistant functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating that can withstand temperatures up to 160℃.

[0128] The stirring speed in this invention is 160 r / min.

[0129] A method for preparing an oil pipe coated with a high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating includes the following steps: pretreating the surface of the oil pipe to be coated according to national standard GB / T8923.1; adding thinner to the high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating to adjust the viscosity to 80 cSt, then spraying it onto the pretreated oil pipe, and curing at medium to high temperature to obtain an oil pipe coated with a high-temperature resistant (160℃) graphene modified phenolic epoxy / polyurethane coating for water injection wells, with a coating thickness of 160–190 μm as required by industry applications. The medium-temperature curing temperature is 90℃ for 1.2 h; the high-temperature curing temperature is 130℃ for 2.5 h. This invention allows for a single coating application.

[0130] Example 4

[0131] The specific formulation of the coating is as follows: phenolic epoxy resin: 9.0%; polyurethane resin: 42%; functionalized reduced graphene oxide: 1%; pigments and fillers: 29%; additives: 0.6%; curing agent: 9.4%; organic solvent: 9%;

[0132] Step 1: Add 8g of nano-yttrium-stabilized zirconium oxide / yttrium oxide (YSZ / Y2O3) and 40g of silane coupling agent isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol. The nano-YSZ / Y2O3 particles have a diameter of less than 30nm. Mix the mixture uniformly using ultrasound, and then stir at 80℃ for 2.5h. Simultaneously, add 25g of distilled water to the solution. Finally, filter and wash 6 times with distilled water and anhydrous ethanol, and then dry in an oven at 60℃ for 24 hours to obtain IBTEO-coated YSZ / Y2O3 (abbreviated as IBTEO / YSZ / Y2O3).

[0133] Step 2: Add 1.4g of partially reduced graphene oxide (b-RGO) and 25g of isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol, mix them uniformly by ultrasonication, and then stir at 80℃ for 8.5h. Simultaneously, slowly add 30g of distilled water to the solution. Finally, filter the nanomaterial and wash it 10 times with distilled water and anhydrous ethanol, then dry it in an oven at 60℃ for 24h to obtain IBTEO-modified b-RGO, abbreviated as IBTEO / b-RGO.

[0134] It should be noted that partially reduced graphene oxide is an existing product on the market. The difference is that, apart from a very small amount of impurities, the C:H:O ratio is different. In the partially reduced graphene oxide of this invention, the C:H:O ratio is 7:1:1.

[0135] Step 3: Add 2.0 g of IBTEO / b-RGO to 1 L of DMF to form a homogeneous suspension. Then add 5-10 g of IBTEO / YSZ / Y2O3 to the above suspension and sonicate for 0.8 h to form a homogeneous suspension. Finally, stir at 84 °C for 2.5 h. Filter the above mixture and wash it five times with distilled water and ethanol, then dry it in an oven at 60 °C for 24 h to obtain functionalized reduced graphene oxide.

[0136] The specific surface area of ​​functionalized reduced graphene oxide is 400 m². 2 / g, with a sheet size of 1.0~2.5μm, such thinner and smaller layers are more likely to form a labyrinth effect in the coating, resulting in a coating with better impermeability and corrosion resistance, and less functionalized reduced graphene oxide is required to achieve the same performance.

[0137] The preparation method of the above-mentioned high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating includes the following steps, based on the above weight percentages:

[0138] Step 1: Add 10g of functionalized reduced graphene oxide to 90g of organic solvent and sonicate to obtain a functionalized reduced graphene oxide dispersion. The sonication time is 110min and the sonication frequency is 9KHZ.

[0139] Step 2: Add 14.2% of the total mass of 90g phenolic epoxy resin to the functionalized reduced graphene oxide dispersion from Step 1. After mechanical stirring until homogeneous, sonicate to obtain a functionalized reduced graphene oxide phenolic epoxy resin mixture. The phenolic epoxy resin encapsulates the graphene to prevent agglomeration. The number of functionalized reduced graphene oxide layers after dispersion is 1-5. The sonication time is 180 min, and the sonication frequency is 5 kHz.

[0140] Step 3: Add the functionalized reduced graphene oxide phenolic epoxy resin mixture prepared in Step 2 to the remaining phenolic epoxy resin and stir for 20 minutes until uniformly mixed; then add 1.57g of dispersant and stir at high speed for 20 minutes until uniformly mixed; then add 420g of polyurethane resin and stir for 15 minutes until uniformly mixed; finally add 290g of pigments and fillers to obtain the coating.

[0141] Step 4: Grind the coating from Step 3 for 1 hour to obtain a coating fineness of less than 15 μm. This will make the sprayed coating smoother and promote the dispersion of functionalized reduced graphene oxide. Then add 4.43 g of additives and stir at high speed for 10 min to obtain component A.

[0142] Step 5: Mix component A with 94g of component B to obtain a high-temperature resistant functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating with a temperature of 160℃.

[0143] The stirring speed in this invention is 160 r / min.

[0144] A method for preparing an oil pipe coated with a high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating includes the following steps: pretreating the surface of the oil pipe to be coated according to national standard GB / T8923.1; adding thinner to the high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating to adjust the viscosity to 80 cSt, then spraying it onto the pretreated oil pipe, and curing at medium to high temperature to obtain an oil pipe coated with a high-temperature resistant (160℃) graphene modified phenolic epoxy / polyurethane coating for water injection wells, with a coating thickness of 160–190 μm as required by industry applications. The medium-temperature curing temperature is 90℃ for 1.2 h; the high-temperature curing temperature is 130℃ for 2.5 h. This invention allows for a single coating application.

[0145] Example 5

[0146] The specific formulation of the coating is as follows: phenolic epoxy resin: 10%; polyurethane resin: 41%; functionalized reduced graphene oxide: 2%; pigments and fillers: 28%; additives: 0.55%; curing agent: 9.45%; organic solvent: 9.0%;

[0147] Step 1: Add 10g of nano-yttrium-stabilized zirconium oxide / yttrium oxide (YSZ / Y2O3) and 50g of silane coupling agent isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol. The nano-YSZ / Y2O3 particles have a diameter of less than 30nm. Mix them uniformly using ultrasound, and then stir at 81℃ for 3h. Simultaneously, add 25g of distilled water to the above solution. Finally, filter and wash 6 times with distilled water and anhydrous ethanol, and then dry in an oven at 60℃ for 24h to obtain IBTEO-coated YSZ / Y2O3 (abbreviated as IBTEO / YSZ / Y2O3).

[0148] Step 2: Add 1.5g of partially reduced graphene oxide (b-RGO) and 28g of isobutyltriethoxysilane (IBTEO) to 300g of anhydrous ethanol, mix them uniformly by ultrasonication, and then stir at 81℃ for 9h. Simultaneously, slowly add 30g of distilled water to the solution. Finally, filter the nanomaterial and wash it 10 times with distilled water and anhydrous ethanol, then dry it in an oven at 60℃ for 24h to obtain IBTEO-modified b-RGO, abbreviated as IBTEO / b-RGO.

[0149] It should be noted that partially reduced graphene oxide is an existing product on the market. The difference is that, apart from a very small amount of impurities, the C:H:O ratio is different. In the partially reduced graphene oxide of this invention, the C:H:O ratio is 7:1:1.

[0150] Step 3: Add 2.5 g of IBTEO / b-RGO to 1 L of DMF to form a homogeneous suspension. Then add 10 g of IBTEO / YSZ / Y2O3 to the above suspension and sonicate for 1 h to form a homogeneous suspension. Finally, stir at 86 °C for 3 h. Filter the above mixture and wash it five times with distilled water and ethanol, then dry it in an oven at 60 °C for 24 h to obtain functionalized reduced graphene oxide.

[0151] The specific surface area of ​​functionalized reduced graphene oxide is 450 m². 2 / g, with a sheet size of 1.0~2.5μm, such thinner and smaller layers are more likely to form a labyrinth effect in the coating, resulting in a coating with better impermeability and corrosion resistance, and less functionalized reduced graphene oxide is required to achieve the same performance.

[0152] The preparation method of the above-mentioned high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating includes the following steps, based on the above weight percentages:

[0153] Step 1: Add 20g of functionalized reduced graphene oxide to 90g of organic solvent prepared by mixing 45g of n-butanol and 45g of cyclohexanone in a 1:1 ratio, and sonicate to obtain a dispersion of functionalized reduced graphene oxide. The sonication time is 120min and the sonication frequency is 9KHZ.

[0154] Step 2: Add 14.2% of the total mass of 100g phenolic epoxy resin to the functionalized reduced graphene oxide dispersion from Step 1. After mechanical stirring until homogeneous, sonicate to obtain a functionalized reduced graphene oxide phenolic epoxy resin mixture. The phenolic epoxy resin encapsulates the graphene to prevent agglomeration. The number of functionalized reduced graphene oxide layers after dispersion is 1-5. The sonication time is 180 min, and the sonication frequency is 5 kHz.

[0155] Step 3: Add the functionalized reduced graphene oxide phenolic epoxy resin mixture prepared in Step 2 to the remaining phenolic epoxy resin and stir for 20 minutes until uniformly mixed; then add 1.43g of dispersant and stir at high speed for 20 minutes until uniformly mixed; then add 410g of polyurethane resin and stir for 15 minutes until uniformly mixed; finally add 280g of pigments and fillers to obtain the coating.

[0156] Step 4: Grind the coating from Step 3 for 1 hour to obtain a coating fineness of less than 15 μm. This will make the sprayed coating smoother and promote the dispersion of functionalized reduced graphene oxide. Then add 4.07 g of additives and stir at high speed for 10 minutes to obtain component A.

[0157] Step 5: Mix component A with 94.5g of component B to obtain a high-temperature resistant functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating with a temperature of 160℃.

[0158] The stirring speed in this invention is 170 r / min.

[0159] A method for preparing an oil pipe coated with a high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating includes the following steps: pretreating the surface of the oil pipe to be coated according to national standard GB / T8923.1; adding thinner to the high-temperature resistant (160℃) functionalized reduced graphene oxide modified phenolic epoxy / polyurethane coating to adjust the viscosity to 90 cSt, then spraying it onto the pretreated oil pipe, and curing at medium to high temperature to obtain an oil pipe coated with a high-temperature resistant (160℃) graphene modified phenolic epoxy / polyurethane coating for water injection wells, with a coating thickness of 160–190 μm as required by industry applications. The medium-temperature curing temperature is 100℃ for 1.5 h; the high-temperature curing temperature is 140℃ for 3 h. This invention allows for a single coating application.

[0160] Coating performance test:

[0161] (1) Thickness: The coating thickness was measured using a coating thickness gauge. The average value was taken from 6 points. The test results are shown in Table 1.

[0162] (2) Adhesion: The adhesion of the coating was measured according to the requirements of SY / T6717-2016 standard. The test results are shown in Table 1.

[0163] (3) Surface roughness: The surface roughness of the coating was measured using a surface roughness meter. The average value was taken at 6 points. The test results are shown in Table 1.

[0164] (4) Anti-scaling performance test at room temperature: The samples were immersed for 150 days in a simulated formation water environment with a mineralization of less than 150,000 mg / L and a bacterial content of less than 100,000 CFU / ml at room temperature and pressure. After removal, the samples were rinsed with clean water, and the scale area on the surface of the samples was evaluated. The test results are shown in Table 1.

[0165] (5) High-temperature anti-scaling performance test: The test was conducted for 240 hours in a solution with a test temperature of 100℃, a pressure of 15MPa, a CO2 partial pressure of 1MPa, a mineralization of less than 150,000 mg / L, and a bacterial content of less than 100,000 CFU / ml. After removal, the samples were rinsed with clean water, and the scale area on the sample surface was evaluated. The test results are shown in Table 1.

[0166] (6) High temperature resistance: The sample was immersed in a 10% NaCl solution at 170℃ and 10MPa for 240h. After rinsing with clean water, the bubbling on the sample surface was evaluated. The test results are shown in Table 1.

[0167] (7) Resistance to corrosion by acidic oil and gas media under high temperature and high pressure: The test temperature was 160℃, the pressure was 10MPa, the CO2 partial pressure was 0.5MPa, the produced water from a certain oil field had an oil content of 1%, and the test lasted for 72 hours. After taking it out, it was rinsed with clean water, and the blistering on the sample surface was evaluated. The test results are shown in Table 1.

[0168] (8) Resistance to high temperature and high pressure alkaline corrosion: The test temperature was 160℃, the pressure was 70MPa, the solution was NaOH, the pH value was 12.5, and the test lasted for 16 hours. After taking it out, it was rinsed with clean water, and the blistering on the sample surface was evaluated. The test results are shown in Table 1.

[0169] Table 1

[0170]

[0171] This invention, based on the operational requirements of oil and gas drilling and production, and considering the functional differences of each component, precisely designs each coating composition, including the addition of high-temperature resistant phenolic epoxy resin, toughened and reinforced high-temperature resistant polyurethane resin, matched dispersants, pigments, fillers, curing agents, and precise control over coating fineness (less than 15 micrometers) and coating preparation process. This achieves unexpected long-lasting (over 5 years) effects in oil and gas drilling and production under high pressure (up to 70 MPa), high salinity (150,000 PPM), and 160°C conditions.

[0172] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a graphene-modified novolac epoxy and polyurethane coating, characterized by, The method comprises the following steps: S1: uniformly mixing the functionalized reduced graphene oxide into an organic solvent to obtain dispersion liquid A; S2: uniformly dispersing the first portion of phenolic epoxy resin into the dispersion liquid A to obtain dispersion liquid B; S3: uniformly mixing the second portion of phenolic epoxy resin into the dispersion liquid B to obtain dispersion liquid C, and then sequentially adding dispersion aids, polyurethane resin and pigments and fillers into the dispersion liquid C to obtain coating a; S4: grinding the coating a, and then adding coupling agents, adhesion promoters, defoaming agents and leveling agents to obtain coating b; S5: uniformly mixing the coating b with a curing agent to obtain a graphene-modified phenolic epoxy / polyurethane coating; In the S1, the method for preparing the functionalized reduced graphene oxide comprises the following steps: S11: uniformly mixing nano yttrium-stabilized zirconium oxide / yttrium oxide and isobutyl triethoxysilane in anhydrous ethanol to obtain a mixed system a, and then obtaining a reaction liquid a by heat preservation, and then separating, washing and drying the product in the reaction liquid a to obtain nano yttrium-stabilized zirconium oxide / yttrium oxide coated with isobutyl triethoxysilane; S12: uniformly mixing part of reduced graphene oxide and isobutyl triethoxysilane in anhydrous ethanol to obtain a mixed system b, and then obtaining a reaction liquid b by heat preservation, and then separating, washing and drying the product in the reaction liquid b to obtain reduced graphene oxide modified by isobutyl triethoxysilane; S13: uniformly dispersing the reduced graphene oxide modified by isobutyl triethoxysilane in DMF to obtain a suspension a, and then uniformly dispersing nano yttrium-stabilized zirconium oxide / yttrium oxide coated with isobutyl triethoxysilane in the suspension a to obtain a suspension b, and finally obtaining a reaction liquid c by heat preservation, and then separating, washing and drying the product in the reaction liquid c to obtain functionalized reduced graphene oxide.

2. The method of preparing graphene-modified novolac epoxy and polyurethane coating according to claim 1, characterized in that, In the S12, the atomic ratio of C:H:O in the part of reduced graphene oxide is 7:1:

1.

3. The method of preparing graphene-modified novolac epoxy and polyurethane coating according to claim 1, characterized in that, In the S11, the weight ratio of the nano yttrium-stabilized zirconium oxide / yttrium oxide, the isobutyl triethoxysilane and the anhydrous ethanol is (5-10):(31-50):300; In the S12, the weight ratio of the part of reduced graphene oxide, the isobutyl triethoxysilane and the anhydrous ethanol is (1.3-1.5):(22-28):300; In the S13, the weight ratio of the reduced graphene oxide modified by isobutyl triethoxysilane and the nano yttrium-stabilized zirconium oxide / yttrium oxide coated with isobutyl triethoxysilane is (1.6-2.5):(5-10).

4. The method of preparing graphene-modified novolac epoxy and polyurethane coating according to claim 1, characterized in that, In the S1, the weight ratio of the functionalized reduced graphene oxide and the organic solvent is (0.6-2):(9-10); In the S2, the weight ratio of the first portion of phenolic epoxy resin and the organic solvent in the dispersion liquid A is (1-2):(9-10); In the S3, the weight ratio of the second portion of phenolic epoxy resin and the organic solvent in the dispersion liquid A is (6-12):(9-10); The weight ratio of the dispersing aid, polyurethane resin, pigment and filler and organic solvent in the coating a in S3 is (0.07-0.12):(40-42):(27-30):(9-10).

5. The method of preparing graphene-modified novolac epoxy and polyurethane coating according to claim 1, characterized in that, In S1, the organic solvent is one of n-butanol or cyclohexanone or a mixture thereof in any ratio; In S3, the pigment and filler include carbon black, talcum powder, barium sulfate, mica iron oxide and silicon carbide; the weight ratio of the carbon black, talcum powder, barium sulfate, mica iron oxide and silicon carbide is 1:3:5:3:2; the type of the dispersing aid is BYK-163.

6. The method of preparing graphene-modified novolac epoxy and polyurethane coating according to claim 1, characterized in that, In S4, the weight ratio of the dispersing aid, coupling agent, adhesion promoter, defoaming agent and leveling agent is 3:1.5:2:4:1; The weight ratio of the defoaming agent and organic solvent in the dispersion A is (0.1-0.18):(9-10).

7. The method of preparing graphene-modified novolac epoxy and polyurethane coating according to claim 1, characterized in that, In S5, the curing agent is a compounded solution of alicyclic modified amine and isophorone diisocyanate curing agent; the weight ratio of the alicyclic modified amine and isophorone diisocyanate curing agent is 1:

4.

8. The graphene-modified novolac epoxy and polyurethane coating prepared by the method according to any one of claims 1 to 7, characterized in that, The A component and the B component are included in a weight percentage; The A component includes phenolic epoxy resin, polyurethane resin, functionalized reduced graphene oxide, pigment and filler, organic solvent and additives, and the B component is a curing agent; In the A component, the phenolic epoxy resin is 9%-10%, the polyurethane resin is 40%-42%, the functionalized reduced graphene oxide is 0.6%-2%, the pigment and filler are 27%-30%, the additives are 0.54%-0.97%, the organic solvent is 9%-10%, and the B component is 7.5%-10%.

9. The application of the graphene modified phenolic epoxy and polyurethane coating obtained by the preparation method of the graphene modified phenolic epoxy and polyurethane coating according to any one of claims 1-7 in oil and gas drilling and production pipes.

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