Modified graphene oxide waterborne epoxy heavy-duty anticorrosive coating, preparation method and application thereof

Abstract

The application discloses a modified graphene oxide water-based epoxy heavy-duty anticorrosive paint as well as a preparation method and application thereof. The anticorrosive paint comprises the following components in parts by mass: modified graphene oxide 0.1-0.5 parts, AlOOH@K-CNC composite material 0.5-1.5 parts, water-based epoxy resin 80-120 parts and water-based epoxy curing agent 10-30 parts. The modified graphene oxide is modified with arginine on graphene oxide and is covalently modified. The application simultaneously adds graphene oxide and nanocellulose, overcomes the corresponding shortcomings through modification treatment, greatly improves the anticorrosive performance and is suitable for marine environment.

Description

A waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide, its preparation method and application Technical Field

[0001] This invention belongs to the field of waterborne anti-corrosion coating technology, and relates to a modified graphene oxide waterborne epoxy resin heavy-duty anti-corrosion coating, its preparation method and application. Background Technology

[0002] The main component of various transport ships, operating platforms, oil pipelines, and other equipment used in marine environments is carbon steel. However, carbon steel is exposed to the marine atmosphere for extended periods and is susceptible to damage from water vapor, oxygen, and corrosive ions (Cl-). - Corrosion of carbon steel can cause serious consequences and huge losses to the national economy, making the corrosion and protection of carbon steel particularly important.

[0003] Surface coating protection is one of the most widely used anti-corrosion methods, mainly due to its wide adaptability, simple construction, low cost, and convenient maintenance, making it the primary choice for current anti-corrosion efforts. However, traditional organic epoxy resin anti-corrosion coatings release large amounts of photochemical organic compounds (VOCs) during the application to carbon steel surfaces, causing air pollution and harming the environment and human health, thus failing to meet current coating protection needs. Waterborne epoxy resin, using water as a solvent, offers advantages such as strong adaptability, good environmental performance, and true water-based properties. However, because waterborne epoxy resins contain various dispersants and hydrophilic groups, they are prone to developing pores and defects during film formation, making them susceptible to chloride ions (Cl). - O 2- SO4 2- Corrosive factors can penetrate and reduce corrosion resistance.

[0004] Chinese patent CN 113549386 A discloses a water-based anti-corrosion coating for use in deep-sea environments, its preparation method and application, which is applicable to deep-sea environments and below the sea surface; however, the coating has poor wear resistance due to the composite titanium carbide nanosheets on the surface of nanocellulose.

[0005] Graphene is a novel material with a single-layer, two-dimensional honeycomb lattice structure of carbon atoms linked by sp² orbitals, and is a typical two-dimensional material. Graphene's excellent optical, electrical, and mechanical properties have attracted the attention of researchers; however, the tendency for graphene layers to aggregate and its poor dispersibility in solvents hinders its practical applications. Nanocellulose, as a novel anti-corrosion filler, can improve the mechanical properties and water resistance of epoxy resins. However, the hydrogen bonds and van der Waals forces on the surface of nanocellulose cause it to aggregate in the polymer matrix, and nanocellulose also has poor thermal stability. Adding either of these as fillers can actually degrade the performance of the polymer matrix. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide. Graphene oxide and nanocellulose are added and modified to overcome their respective shortcomings, significantly improving anti-corrosion performance and making it suitable for marine environments, thus solving the problems existing in the prior art.

[0007] Another objective of this invention is to provide a method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide.

[0008] A third objective of this invention is to provide an application of a waterborne epoxy resin heavy-duty anti-corrosion coating based on modified graphene oxide.

[0009] The technical solution adopted in this invention is a water-based epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide, comprising the following components in parts by weight:

[0010] The mixture comprises 0.1-0.5 parts of modified graphene oxide, 0.5-1.5 parts of AlOOH@K-CNC composite material, 80-120 parts of waterborne epoxy resin, and 10-30 parts of waterborne epoxy curing agent; wherein the modified graphene oxide is obtained by modifying graphene oxide with arginine and performing covalent bond modification.

[0011] Furthermore, the waterborne epoxy resin is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, or bisphenol S type epoxy resin.

[0012] A method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide includes the following steps:

[0013] S1, Preparation of modified graphene oxide: Graphene oxide powder and deionized water were ultrasonically treated in a water bath to obtain a GO dispersion. Arginine solution was then slowly added to the GO dispersion to react. After purification, arginine-modified graphene oxide was obtained. The mass ratio of deionized water, arginine, and graphene oxide was 150~200:2~5:0.5~1.

[0014] S2, Preparation of modified nanocellulose: Nanocellulose is reacted with anhydrous ethanol solution by ultrasound, and a silane coupling agent is added to purify it to obtain modified nanocellulose; the mass ratio of anhydrous ethanol, silane coupling agent and nanocellulose is 50~150:2~5:0.5~1;

[0015] Preparation of S3, AlOOH@K-CNC composite material:

[0016] Modified nanocellulose was added to an acetic acid-ethanol solution, with the mass ratio of modified nanocellulose, anhydrous ethanol, deionized water, and acetic acid being 1:50~150:5~20:1~3; then, an equal mass of aluminum isopropoxide hydrolysate was slowly added dropwise to react and purify the solution; the mass ratio of aluminum isopropoxide, deionized water, and nitric acid in the nitric acid solution containing aluminum isopropoxide was 1:15~35:0.06~0.22.

[0017] S4. Mix the modified graphene oxide, AlOOH@K-CNC composite material, waterborne epoxy resin and waterborne epoxy curing agent evenly in a mass ratio of 0.1~0.5:0.5~1.5:80~120:10~30 to obtain the final product.

[0018] Furthermore, the reaction conditions for S1 are: temperature of 40~50℃, time of 18~24h, and stirring speed of 300~600rad / min.

[0019] Furthermore, the reaction conditions for S2 are: temperature of 55~70℃, time of 3~6h, and stirring speed of 300~600rad / min.

[0020] Furthermore, the reaction conditions of the modified nanocellulose and aluminum isopropoxide hydrolysate in S3 are as follows: temperature 55~70℃, time 3~6h, and stirring speed 300~600rad / min.

[0021] Furthermore, in S1, the centrifugation speed for purification is 8000~10000 rad / min, and the centrifugation time is 7~10 min; in S2~S3, the centrifugation speed for purification is 800~3000 rad / min, and the centrifugation time is 7~10 min.

[0022] Furthermore, in S2, the nanocellulose has a diameter of 5~50nm and a length of 0.2~2μm.

[0023] Furthermore, in S2, the silane coupling agent is γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, or 3-aminopropyltriethoxysilane.

[0024] Application of a modified graphene oxide waterborne epoxy resin heavy-duty anti-corrosion coating on steel structures in marine environments or power engineering steel structures.

[0025] The beneficial effects of this invention are:

[0026] (1) The dispersion effect of graphene oxide alone in waterborne epoxy resin is not good. In this invention, arginine is used to optimize its functional groups so that it can be uniformly dispersed in waterborne epoxy resin. Arginine contains a diamine structure, one of which undergoes a ring-opening reaction with the epoxy group of waterborne epoxy resin, filling the tiny gaps in the waterborne epoxy resin during the curing process, preventing corrosive media from contacting the metal matrix, increasing the crosslinking density of the waterborne epoxy resin, and thus improving the corrosion resistance of the resin. Due to its ultra-thin sheets, graphene oxide can fill the small defects in the coating during curing and can effectively form a "maze effect", so that the path of corrosive media through the coating is much longer than the coating thickness, increasing the time required for penetration, thereby improving the anti-corrosion life and effect.

[0027] (2) The addition of hydrated alumina / modified nanocellulose composite material in this invention can improve the toughness and impact strength of epoxy resin. The nano-hydrated alumina microspheres generated on the surface of nanocellulose can greatly enhance the thermal stability of nanocellulose. The introduced nano-hydrated alumina, as an inorganic filler, can also improve the barrier properties, wear resistance, and anti-aging properties of epoxy resin. Therefore, the graphene oxide modified in step S3 solves the problems of easy agglomeration and poor anti-corrosion effect.

[0028] (3) The present invention incorporates hydrated alumina (AlOOH), which enhances the high-temperature resistance and greatly increases the lifespan of the coating. The present invention functionalizes graphene and nanocellulose, enabling them to be uniformly dispersed in waterborne epoxy resin coatings. The modified graphene and nanocellulose can provide a certain shielding effect against corrosive substances and can also passivate and protect the coated metal to a certain extent, thereby further improving the anti-corrosion performance of the coating. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 is a Tafel polarization curve of the coatings prepared in Examples 2-3 of the present invention and the water-based epoxy resin coatings coated on the surface of Q355b steel in simulated seawater solution.

[0031] Figure 2 is a Nyquist diagram of the coatings prepared in Examples 2-3 of the present invention and the water-based epoxy resin coatings coated on the surface of Q355b steel in simulated seawater solution. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1,

[0034] A waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide, comprising the following components by weight:

[0035] 0.1-0.5 parts of modified graphene oxide, 0.5-1.5 parts of AlOOH@K-CNC composite material, 80-120 parts of waterborne epoxy resin and 10-30 parts of waterborne epoxy curing agent.

[0036] Among them, the waterborne epoxy resin is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin or bisphenol S type epoxy resin; the modified graphene oxide is made by modifying arginine on graphene oxide and performing covalent bond modification.

[0037] Example 2,

[0038] A method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide includes the following steps:

[0039] S1, Preparation of modified graphene oxide (La-GO):

[0040] One part by weight of graphene oxide powder was ultrasonically treated for 30 minutes in a water bath and uniformly dispersed in 200 parts by weight of deionized water to obtain a graphene oxide (GO) dispersion. Four parts by weight of arginine were dissolved in 50 parts by weight of NaOH solution (4.13 mg / ml) to provide an alkaline environment for the arginine to be fully grafted onto the graphene oxide. When m(arginine):m(GO) < 3, the GO reaction was incomplete, resulting in poor dispersibility in epoxy resin after purification. The arginine solution was slowly added dropwise to the GO dispersion, stirred and ultrasonicated for 30 minutes at a stirring speed of 300 rad / min. The resulting mixture was reacted at 40℃ for 24 h. Then, 150 parts by weight of anhydrous ethanol was added to the mixture and allowed to stand for 4 h. The mixture was washed with deionized water and centrifuged three times to remove unreacted arginine and ethanol. The product obtained after centrifugation was freeze-dried at -60℃ for 24 h to obtain modified graphene oxide. The purification centrifugation speed was 8000 rpm. rad / min, centrifugation time was 10 min.

[0041] S2, 1 part by mass of nanocellulose was added to 100 parts by mass of ethanol solution (ethanol:deionized water mass ratio = 8:2), and the mixture was sonicated for 30 minutes to disperse it evenly, thus obtaining a CNC dispersion. 2 parts by mass of KH550 (γ-aminopropyltriethoxysilane) solution was slowly added dropwise to the CNC dispersion, and the mixture was reacted at 65℃ with stirring for 4 hours at a stirring speed of 300 rad / min. The mixture was centrifuged three times with deionized water, and the purified product was centrifuged at 800 rad / min for 10 minutes to remove unreacted KH550 and ethanol. The product obtained after centrifugation was freeze-dried at -60℃ for 24 hours to obtain modified nanocellulose K-CNC.

[0042] Preparation of S3, AlOOH@K-CNC composite material:

[0043] One part by mass of the obtained modified nanocellulose K-CNC was added to a glacial acetic acid mixture, which consisted of 80 parts by mass of anhydrous ethanol, 20 parts by mass of deionized water, and 2 parts by mass of glacial acetic acid. One part by mass of aluminum isopropoxide powder was added to 20 parts by mass of deionized water and hydrolyzed in an 85°C water bath for 2 hours with thorough stirring. Then, 0.06 parts by mass of HNO3 was added dropwise and hydrolyzed for 1 hour. The fully hydrolyzed solution was then slowly added dropwise to the glacial acetic acid mixture containing the modified nanocellulose. The reaction was carried out at 65°C with stirring for 4 hours at a stirring speed of 300 rad / min. After standing for 2 hours, the mixture was centrifuged with deionized water until the pH was neutral at a centrifugation speed of 800 rad / min for 10 minutes. The product obtained after centrifugation was freeze-dried at -60°C for 12 hours to obtain the AlOOH@K-CNC composite material.

[0044] S4. Add 0.3 parts by mass of modified graphene oxide and 1 part by mass of modified nanocellulose composite material (AlOOH@K-CNC composite material) to 10 parts by mass of DMF (N,N-dimethylformamide), ultrasonically disperse for 30 min, then add 100 parts by mass of bisphenol A type epoxy resin E51, and magnetically stir evenly in an oil bath at 140℃ until all DMF evaporates to obtain modified graphene oxide heavy-duty anti-corrosion coating.

[0045] Example 3,

[0046] A method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide includes the following steps:

[0047] Except for step S4, in which the amount of modified graphene oxide added is 0.1 parts by mass and the amount of modified nanocellulose composite material (AlOOH@K-CNC composite material) added is 0.5 parts by mass; the remaining steps are the same as in Example 2.

[0048] In Example S2 of this invention, the silane coupling agent can modify nanocellulose, so that silane groups are attached to the groups of nanocellulose, and nanocellulose can be uniformly dispersed in epoxy resin. If the nanocellulose content is too high or the temperature is too high, the nanocellulose will decompose, thereby reducing its corrosion resistance.

[0049] In Example S3 of this invention, glacial acetic acid is primarily used as a hydrolysis catalyst. By adjusting the pH value to between 3.5 and 5.5, the added silane coupling agent KH550 is fully hydrolyzed, thereby aminosilanizing the nanocellulose. If the amount of acetic acid added exceeds this range, KH550 cannot be fully hydrolyzed, leading to modification failure and the nanocellulose failing to disperse uniformly in the epoxy resin.

[0050] The modified graphene oxide heavy-duty anti-corrosion coating (0.3% modified graphene oxide + 1% modified nanocellulose composite material) prepared in Example 2 was coated onto Q355b carbon steel sheets and cured. The modified graphene oxide heavy-duty anti-corrosion coating (0.1% modified graphene oxide + 0.5% modified nanocellulose composite material) prepared in Example 3 was coated onto Q355b carbon steel sheets and cured. Pure E51 epoxy resin (without modified fillers) was then coated onto Q355b carbon steel sheets. The Q355b carbon steel sheet cured on the carbon steel sheet and the Q355b carbon steel sheet (without anti-corrosion coating) were respectively placed in simulated seawater for corrosion for 3 days; the electrochemical test results are shown in Figures 1-2. As can be seen from Figure 1, the corrosion current densities of the Q355b carbon steel sheet, the Q355b carbon steel coated with pure E51 epoxy resin, the Q355b carbon steel coated with the anti-corrosion coating prepared in Example 2, and the Q355b carbon steel coated with the anti-corrosion coating prepared in Example 3 are respectively 2.859 × 10 -3 A, 1.145×10 -4 A, 5.016×10 -5 A, 2.704×10 -5 A. The lower the corrosion current density, the stronger the corrosion resistance. The corrosion current density of the heavy-duty anti-corrosion coatings prepared in Examples 2 and 3 of this invention is significantly lower than that of the uncoated carbon steel sheet by two orders of magnitude, indicating that the corrosion rate of Q355b steel coated with the heavy-duty anti-corrosion coatings of this invention is slower. This shows that the modification of arginine significantly improves the compatibility between graphene oxide and epoxy resin, and the well-dispersible La-GO significantly improves the barrier properties of the coating.

[0051] As shown in Figure 2, the coating capacitances of Q355b carbon steel sheet (uncoated), pure E51 epoxy resin (without modified filler), the anti-corrosion coating prepared in Example 2, and the anti-corrosion coating prepared in Example 3 are 20.92Ω, 256.6Ω, 782.3Ω, and 844.3Ω, respectively. The increase in the semi-circular diameter of the capacitance is positively correlated with the increase in polarization resistance, indicating a decrease in corrosion rate. The anti-corrosion coating prepared in Example 2 has a larger semi-circular diameter than Q355 and E51, indicating that the addition of the uniformly distributed modified graphene oxide and nanocellulose composite material in Example 2 significantly reduced the corrosion rate of the epoxy resin coating and improved its corrosion resistance. The coating capacitance reflects the shielding performance of the coating; a higher impedance value indicates better corrosion resistance. The added graphene oxide, with its layered structure, hinders oxygen diffusion and increases the coating's anti-corrosion performance. Adding hydrated alumina / modified nanocellulose composite material to coatings can fill the small defects in the coating during curing and effectively form a "maze effect". This allows the corrosive medium to pass through the coating much beyond the coating thickness, increasing the time required for penetration and thus improving the barrier properties, wear resistance and anti-aging properties of epoxy resin.

[0052] Example 4,

[0053] A method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide includes the following steps:

[0054] S1, Preparation of modified graphene oxide (La-GO):

[0055] 0.5 parts by mass of graphene oxide powder were ultrasonically treated for 30 minutes in a water bath and uniformly dispersed in 150 parts by mass of deionized water to obtain a graphene oxide (GO) dispersion. 5 parts by mass of arginine were weighed and dissolved in NaOH solution to provide an alkaline environment, allowing the arginine to be fully grafted onto the graphene oxide. The arginine solution was slowly added dropwise to the GO dispersion, stirred and ultrasonicated for 30 minutes at a stirring speed of 600 rad / min. The resulting mixture was reacted at 50℃ for 18 h. Then, 150 parts by mass of anhydrous ethanol was added to the mixture and allowed to stand for 4 h. The mixture was washed with deionized water and centrifuged three times to remove unreacted arginine and ethanol. The product obtained after centrifugation was freeze-dried at -60℃ for 24 h to obtain modified graphene oxide. The purification centrifugation speed was 10000 rad / min and the centrifugation time was 7 min.

[0056] S2, 0.5 parts by mass of nanocellulose were added to 150 parts by mass of anhydrous ethanol solution and sonicated for 30 minutes to achieve uniform dispersion, thus obtaining CNC dispersion; 5 parts by mass of γ-(2,3-epoxypropoxy)propyltrimethoxysilane solution were slowly added dropwise to CNC dispersion, and then reacted at 70℃ with stirring for 3 hours at a stirring speed of 600 rad / min. The mixture was centrifuged three times with deionized water, and the purification centrifugation speed was 3000 rad / min for 7 minutes to remove unreacted γ-(2,3-epoxypropoxy)propyltrimethoxysilane and ethanol. The product obtained after centrifugation was freeze-dried at -60℃ for 24 hours to obtain modified nanocellulose K-CNC.

[0057] Preparation of S3, AlOOH@K-CNC composite material:

[0058] One part by mass of the obtained modified nanocellulose K-CNC was added to a glacial acetic acid mixture, which consisted of 150 parts by mass of anhydrous ethanol, 5 parts by mass of deionized water, and 3 parts by mass of glacial acetic acid. One part by mass of aluminum isopropoxide powder was added to 35 parts by mass of deionized water and hydrolyzed thoroughly in an 85°C water bath for 2 hours. Then, 0.22 parts by mass of HNO3 was added dropwise, and hydrolysis was continued for another hour. The fully hydrolyzed solution was then slowly added dropwise to the glacial acetic acid mixture containing the modified nanocellulose and reacted at 70°C with stirring for 3 hours at a stirring speed of 600 rad / min. After standing for 2 hours, the mixture was centrifuged with deionized water until the pH was neutral at a centrifugation speed of 3000 rad / min for 7 minutes. The product obtained after centrifugation was freeze-dried at -60°C for 12 hours to obtain the AlOOH@K-CNC composite material.

[0059] S4. Add 0.5 parts by mass of modified graphene oxide and 1.5 parts by mass of modified nanocellulose composite material (AlOOH@K-CNC composite material) to 20 parts by mass of DMF (N,N-dimethylformamide), ultrasonically disperse for 30 min, then add 80 parts by mass of bisphenol A type epoxy resin E51, and magnetically stir evenly in an oil bath at 140℃ until all DMF evaporates to obtain modified graphene oxide heavy-duty anti-corrosion coating.

[0060] Example 5,

[0061] A method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide includes the following steps:

[0062] S1, Preparation of modified graphene oxide (La-GO):

[0063] 0.8 parts by weight of graphene oxide powder were ultrasonically treated for 30 minutes in a water bath and uniformly dispersed in 170 parts by weight of deionized water to obtain a graphene oxide (GO) dispersion. 2 parts by weight of arginine were weighed and dissolved in NaOH solution to provide an alkaline environment, allowing the arginine to be fully grafted onto the graphene oxide. The arginine solution was slowly added dropwise to the GO dispersion, stirred and ultrasonicated for 30 minutes at a stirring speed of 400 rad / min. The resulting mixture was reacted at 45℃ for 20 h. Then, 150 parts by weight of anhydrous ethanol was added to the mixture and allowed to stand for 4 h. The mixture was washed with deionized water and centrifuged three times to remove unreacted arginine and ethanol. The product obtained after centrifugation was freeze-dried at -60℃ for 24 h to obtain modified graphene oxide. The purification centrifugation speed was 9000 rad / min and the centrifugation time was 8 min.

[0064] S2, 0.8 parts by mass of nanocellulose were added to 50 parts by mass of anhydrous ethanol solution and sonicated for 30 minutes to achieve uniform dispersion, thus obtaining CNC dispersion; 3 parts by mass of 3-aminopropyltriethoxysilane solution were slowly added dropwise to CNC dispersion, and then reacted at 55℃ with stirring for 6 hours at a stirring speed of 500 rad / min. The mixture was centrifuged three times with deionized water, and the purification centrifugation speed was 2000 rad / min for 8 minutes to remove unreacted 3-aminopropyltriethoxysilane and ethanol. The product obtained after centrifugation was freeze-dried at -60℃ for 24 hours to obtain modified nanocellulose K-CNC.

[0065] Preparation of S3, AlOOH@K-CNC composite material:

[0066] One part by mass of the modified nanocellulose K-CNC was added to a glacial acetic acid mixture, which consisted of 50 parts by mass of anhydrous ethanol, 15 parts by mass of deionized water, and 1 part by mass of glacial acetic acid. One part by mass of aluminum isopropoxide powder was added to 15 parts by mass of deionized water and hydrolyzed thoroughly in an 85°C water bath for 2 hours. Then, 0.06 parts by mass of HNO3 was added dropwise, and hydrolysis was continued for another hour. The fully hydrolyzed solution was then slowly added dropwise to the glacial acetic acid mixture containing the modified nanocellulose and reacted at 55°C with stirring for 6 hours at a stirring speed of 500 rad / min. After standing for 2 hours, the mixture was centrifuged with deionized water until the pH was neutral at a centrifugation speed of 2000 rad / min for 8 minutes. The product obtained after centrifugation was freeze-dried at -60°C for 12 hours to obtain the AlOOH@K-CNC composite material.

[0067] S4. 0.1 parts by mass of modified graphene oxide and 0.5 parts by mass of modified nanocellulose composite material (AlOOH@K-CNC composite material) were added to 30 parts by mass of DMF (N,N-dimethylformamide), ultrasonically dispersed for 30 min, and then 120 parts by mass of bisphenol A type epoxy resin E51 were added. The mixture was magnetically stirred in an oil bath at 140℃ until all DMF was volatilized to obtain the modified graphene oxide heavy-duty anti-corrosion coating.

[0068] Electrochemical analysis showed that the self-corrosion potential of the mixture (0.5 parts by mass of modified graphene oxide + 1.5 parts by mass of modified nanocellulose composite material) added in Example 4 was -0.4675V, and the corrosion current density was 3.065 × 10⁻⁶. -4 A. The corrosion current density is increased by 1.1 orders of magnitude compared to Q355b carbon steel sheet. The AC impedance capacitance is 455.83Ω, which is increased by 2.1 orders of magnitude compared to Q355b carbon steel sheet.

[0069] In Example 5, the self-corrosion potential of the mixture containing (0.1 parts by mass of modified graphene oxide + 0.5 parts by mass of modified nanocellulose composite material) was -0.4885V, and the corrosion current density was 1.264 × 10⁻⁶. -4 A. The corrosion current density is increased by 0.5 orders of magnitude compared to Q355b carbon steel sheet. The AC impedance capacitance is 374.52Ω, which is increased by 1.8 orders of magnitude compared to Q355b carbon steel sheet.

[0070] Example 6,

[0071] Except for step S4, where the amount of modified graphene oxide added is 0.1% of the mass of epoxy resin and the amount of modified nanocellulose composite material (AlOOH@K-CNC composite material) added is 1% of the mass of epoxy resin, the remaining steps are the same as in Example 2.

[0072] Example 7,

[0073] Except for step S4, where the amount of modified graphene oxide added is 0.3% of the mass of epoxy resin and the amount of modified nanocellulose composite material (AlOOH@K-CNC composite material) added is 0.5% of the mass of epoxy resin, the remaining steps are the same as in Example 2.

[0074] Electrochemical tests showed that the corrosion potentials of Examples 6 and 7 were 2.704 × 10⁻⁶, respectively. -5 A, 5.016×10 -5 A, the capacitances of the AC impedance are 782.3Ω and 844.3Ω respectively.

[0075] Example 8,

[0076] Except for step S3, where the amount of nitric acid added is changed, and the mass ratio of nitric acid to aluminum isopropoxide (m(HNO3):m(aluminum isopropoxide)) is 0.06~0.22, the remaining steps are the same as in Example 2. When the mass ratio of nitric acid to aluminum isopropoxide is 0.06, the average diameter of AlOOH particles is 66.69 nm; when the mass ratio is 0.22, the average diameter of AlOOH particles is 138.8 nm. The increase in particle size of AlOOH particles is not due to particle agglomeration, but rather because nitric acid increases the reaction constant of aluminum isopropoxide hydrolysis. Excessive nitric acid will lower the Zeta potential, and the distance between sol particles will decrease due to reduced repulsive force, making the particles more prone to agglomeration. In this case, the AlOOH generated, when combined with modified nanocellulose and added to the resin, does not offer much potential for improving the resin's thermal stability.

[0077] In this embodiment of the invention, the nanocellulose has a diameter of 5-50 nm and a length of 0.2-2 μm. The aspect ratio can reflect the strength of the reinforcing material. If the aspect ratio is too small, the strength and hardness of the resin will be not improved much. If the aspect ratio is large, the addition of nanocellulose to epoxy resin can effectively improve its strength and hardness, giving it better mechanical properties.

[0078] In this embodiment of the invention, the main function of the silane coupling agent γ-aminopropyltriethoxysilane (KH550) is as follows: First, KH550 hydrolyzes to form silanol, which then reacts with the hydroxyl groups on the surface of nanocellulose and AlOOH particles to form hydrogen bonds and condense. Simultaneously, the silanol molecules of the silane associate and aggregate to form a network structure film covering the surface of the powder particles, thus organicating the inorganic powder surface and enabling uniform dispersion in the epoxy resin. KH560 (γ-(2,3-epoxypropoxy)propyltrimethoxysilane), γ-methacryloyloxypropyltrimethoxysilane, and APTES (3-aminopropyltriethoxysilane) can also be used. The principle is the same as KH550, which also functionalizes the filler silane through hydrolysis to form silanol and uniformly disperse it in the epoxy resin.

[0079] In this embodiment of the invention, modified nanocellulose is prepared by acid hydrolysis of nanocellulose, using acetic acid as a catalyst and KH550 as a modifier. The modified nanocellulose can be uniformly dispersed in resin. Then, the modified nanocellulose is further modified by adhering hydrated alumina microspheres to the surface, thereby improving its thermal stability.

[0080] This invention relates to the hydrolysis of aluminum isopropoxide to obtain AlOOH (hydrated alumina). By exploring different amounts of nitric acid, nano-sized hydrated alumina, i.e., hydrated alumina colloid, was obtained. Aluminum isopropoxide hydrolyzes incompletely in deionized water. Nitric acid acts as a colloidal solvent, ensuring the uniform dispersion of the hydrolyzed AlOOH into a colloidal system. Nitric acid also acts as a catalyst to promote the hydrolysis reaction, increasing the reaction rate and promoting the crystal growth of the hydrolysis product AlOOH. When the amount of nitric acid is too small, hydrolysis is incomplete, and unhydrolyzed aluminum isopropoxide precipitates at the bottom of the beaker. If the amount of nitric acid is excessive, the prepared sol is unstable and prone to gelation.

[0081] The addition of hydrated alumina / modified nanocellulose composite material in this invention can improve the toughness and impact strength of epoxy resin. The nano-hydrated alumina microspheres generated on the surface of nanocellulose can greatly enhance the thermal stability of nanocellulose. The introduced nano-hydrated alumina, as an inorganic filler, can also improve the barrier properties, wear resistance and anti-aging properties of epoxy resin.

[0082] Both graphene and cellulose nanoparticles contain a large number of hydroxyl groups on their surfaces, giving them strong hydrophilicity. However, this high hydrophilicity limits their dispersibility in nonpolar polymer matrices. Graphene oxide and cellulose nanoparticles readily aggregate in resins, thus requiring chemical modification. By grafting arginine onto the surface of graphene oxide and functionalizing cellulose nanoparticles with the silane coupling agent KH550, their dispersibility in epoxy resins is improved, thereby enhancing their corrosion resistance.

[0083] Comparative Example 1,

[0084] In step S2, unmodified nanocellulose is used directly, and the remaining steps are the same as in Example 2. In this case, the nanocellulose in the resin will agglomerate, settle to the bottom, and separate into layers, without improving the resin's corrosion resistance whatsoever.

[0085] Comparative Example 2,

[0086] Step S3 is omitted; the remaining steps are the same as in Example 2. The combined effect of modified graphene oxide and modified nanocellulose in the resin can improve its corrosion resistance. However, the coating applied to the steel surface is exposed to sunlight for extended periods, with surface temperatures reaching over 100 degrees Celsius. This causes the modified nanocellulose in the anti-corrosion coating to decompose under high temperatures, reducing the resin's lifespan.

[0087] Comparative Example 3,

[0088] Except for step S3, where the total mass of modified nanocellulose and hydrated alumina added is 0.5%, 1%, and 1.5% of the mass of epoxy resin E51, respectively, and the modified nanocellulose and hydrated alumina are added in a 1:1 ratio; the remaining steps are the same as in Example 2. Electrochemical testing showed that the corrosion potential was 2.704 × 10⁻⁶. -5 A, 5.016×10 -5 A, 3.065×10 -4 A. The capacitance values ​​of the AC impedance are 782.3Ω, 844.3Ω, and 455.8Ω respectively, indicating that the amount added is too large (1.5%), and the corrosion resistance of the coating has decreased.

[0089] In this embodiment of the invention, a composite material is formed by physical blending. The amount of modified nanocellulose and hydrated alumina added is difficult to determine. The presence of hydrated alumina can enhance the thermal stability and strength of the resin. If the amount added is too small, there will be too few AlOOH microspheres adhering to the surface of nanocellulose, and the performance improvement of the resin will be limited. If the amount added is too large, AlOOH will coat the surface of nanocellulose, and the toughness of the resin will decrease.

[0090] In this invention, the proportion of graphene oxide added is limited. When the content exceeds a certain threshold, graphene / metal / graphene connectors will be randomly generated at the epoxy resin / metal interface, leading to micro-electrochemical corrosion of the graphene metal at coating defects, thereby reducing the corrosion resistance of the epoxy resin. When the graphene oxide content is too high, it will form micro-batteries with the metal matrix, thereby accelerating corrosion.

[0091] The main component of steel used in oil pipelines and petrochemical pipe racks in marine environments is carbon steel. However, carbon steel exposed to the marine atmosphere for extended periods is susceptible to damage from atmospheric water vapor, oxygen, and corrosive ions (Cl-) in the ocean. - Corrosion from wind and air can damage steel structures, reducing their lifespan and potentially causing disastrous consequences. For petrochemical pipeline steel structures in harsh marine environments, applying organic epoxy resin anti-corrosion coatings results in the release of large amounts of photochemical organic compounds (VOCs), posing a significant threat to worker health. Water-based epoxy resin anti-corrosion coatings, on the other hand, offer poor corrosion resistance. The modified graphene oxide water-based epoxy resin heavy-duty anti-corrosion coating prepared in this invention, when applied to petrochemical pipeline steel structures in marine environments, effectively overcomes these problems. Furthermore, the modified graphene oxide water-based epoxy resin heavy-duty anti-corrosion coating prepared in this invention exhibits excellent wear resistance and thermal stability, making it suitable for application in power engineering and overcoming the problem of wind-borne particles rubbing against steel structures.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide, characterized in that, The process includes the following steps: S1, preparation of modified graphene oxide: graphene oxide powder and deionized water are ultrasonically treated in a water bath to obtain a GO dispersion. Arginine solution is then slowly added to the GO dispersion to react. After purification, arginine-modified graphene oxide is obtained. The mass ratio of deionized water, arginine, and graphene oxide is 150~200:2~5:0.5~1; arginine is dissolved in NaOH solution to obtain arginine solution, providing an alkaline environment to allow arginine to be fully grafted onto graphene oxide; S2, preparation of modified nanocellulose: nanocellulose is ultrasonically dispersed in anhydrous ethanol solution, a silane coupling agent is added for reaction, and the modified nanocellulose is purified. The mass ratio of anhydrous ethanol, silane coupling agent, and nanocellulose was 50-150:2-5:0.5-1; Preparation of S3, AlOOH@K-CNC composite material: Modified nanocellulose was added to a mixed solution of glacial acetic acid, which served as a hydrolysis catalyst. The pH was adjusted to between 3.5 and 5.5 to ensure complete hydrolysis of the silane coupling agent; the mass ratio of modified nanocellulose, anhydrous ethanol, deionized water, and glacial acetic acid was 1:50-150:5-20:1-3; then, a solution containing... The modified nanocellulose is reacted with an equal mass of aluminum isopropoxide hydrolysate to generate nano-hydrated alumina microspheres on the surface of the nanocellulose, which are then purified to obtain the final product. The mass ratio of aluminum isopropoxide, deionized water, and nitric acid in the nitric acid solution containing aluminum isopropoxide is 1:15~35:0.06~0.

22. In step S4, the modified graphene oxide, AlOOH@K-CNC composite material, waterborne epoxy resin, and waterborne epoxy curing agent are mixed evenly in a mass ratio of 0.1~0.5:0.5~1.5:80~120:10~30 to obtain the final product. The reaction conditions for step S1 are: temperature 40~45℃, time 18~24h, and stirring speed 300~600rad / min.

2. The method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide according to claim 1, characterized in that, The waterborne epoxy resin is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, or bisphenol S type epoxy resin.

3. The method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide according to claim 1, characterized in that, The reaction conditions for S2 are: temperature 55~70℃, time 3~6h, and stirring speed 300~600rad / min.

4. The method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide according to claim 1, characterized in that, The reaction conditions for the modified nanocellulose and aluminum isopropoxide hydrolysate in S3 are: temperature 55~70℃, time 3~6h, and stirring speed 300~600rad / min.

5. The method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide according to claim 1, characterized in that, In step S1, the centrifugation speed for purification is 8000~10000 rad / min, and the centrifugation time is 7~10 min; in steps S2~S3, the centrifugation speed for purification is 800~3000 rad / min, and the centrifugation time is 7~10 min.

6. The method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide according to claim 1, characterized in that, In S2, the nanocellulose has a diameter of 5~50nm and a length of 0.2~2μm.

7. The method for preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide according to claim 1, characterized in that, In S2, the silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, or 3-aminopropyltriethoxysilane.

8. The application of the heavy-duty anti-corrosion coating prepared by the method of preparing a waterborne epoxy resin heavy-duty anti-corrosion coating with modified graphene oxide as described in claim 1 on steel structures in marine environments or steel structures in power engineering.

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