Graphene oxide water-based anticorrosive paint and preparation method thereof

Abstract

The application provides a graphene oxide water-based anticorrosive paint and a preparation method thereof, and comprises the following steps: taking an expanded graphite accumulation body as an anode, a metal conductive material as a cathode, and inserting into an electrolyte containing a modifier to perform electrochemical exfoliation; the electrolyte after reaction is subjected to suction filtration, washing and centrifugal treatment, and the supernatant is taken to obtain a graphene oxide dispersion liquid; and the modified graphene oxide dispersion liquid is fully mixed with a water-based resin emulsion and a curing agent to obtain the graphene oxide water-based anticorrosive paint. In the preparation method, the deep oxidation and modification of the expanded graphite accumulation body are realized in one step by means of electrochemical treatment; since the graphene oxide itself has a certain hydrophilicity, the hydrophilicity is further enhanced after the amino modification, and the dispersibility in a polar solvent is significantly improved. This makes the amino-modified graphene oxide more uniformly dispersed in the application field of the paint, and makes the graphene oxide and the base material better combined, thereby improving the overall performance of the composite material.

Description

Technical Field

[0001] This invention relates to the field of water-based anti-corrosion coatings and their preparation technology, and particularly to a graphene oxide water-based anti-corrosion coating and its preparation method. Background Technology

[0002] Metal corrosion is a significant problem faced by almost every industry, causing not only huge economic losses and environmental pollution but also potentially leading to major safety accidents. Using organic / inorganic or composite coatings as physical barriers is an important means of corrosion prevention, and the enhanced performance of anti-corrosion coatings mainly depends on the physicochemical properties of fillers embedded in the matrix.

[0003] Among nanoscale carbon-based fillers, graphene oxide (GO) is widely used in anti-corrosion composite coatings due to its excellent barrier properties and good compatibility with the coating substrate. The hexagonal structure within the aromatic rings of GO has a pore size of only 0.064 nm, much smaller than that of Cl. − The van der Waals radii of corrosive media such as H2O (0.181 nm), H2O (0.4 nm), and O2 (0.346 nm) can effectively block the diffusion of corrosive media.

[0004] However, due to the tendency of GO sheets to agglomerate in the coating matrix, GO cannot be uniformly dispersed and its excellent barrier properties cannot be fully utilized. Therefore, it is necessary to develop a simple and effective method to achieve tunable preparation of GO and to achieve effective bonding between graphene oxide and the coating matrix in order to improve the anti-corrosion performance of the coating. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a water-based anti-corrosion coating of graphene oxide and its preparation method, which achieves uniform dispersion of graphene oxide in the coating system and forms an effective bond with the substrate, thereby effectively improving the anti-corrosion performance of the water-based coating.

[0006] The specific details of the invention are as follows:

[0007] In a first aspect, the present invention provides a method for preparing a water-based anti-corrosion coating of graphene oxide, comprising:

[0008] Using expanded graphite deposits as the anode and a conductive metal material as the cathode, the material is inserted into an electrolyte for electrochemical stripping. The electrolyte after the reaction is filtered, washed, and centrifuged, and the supernatant is taken to obtain a graphene oxide dispersion.

[0009] The graphene oxide dispersion at a mass ratio of (0.8 ~ 1.6):1 is thoroughly mixed with an aqueous resin emulsion, and then thoroughly mixed with a curing agent to obtain the graphene oxide aqueous anti-corrosion coating.

[0010] The electrolyte is composed of a mixture of a modifier and an inorganic acid / salt, wherein the molar ratio of the modifier to the inorganic acid / salt is (0 ~ 0.5): (0.1 ~ 1).

[0011] The mass ratio of the curing agent to the aqueous resin emulsion is (0.2 ~ 1.0):1;

[0012] The modifier is an amino modifier.

[0013] Optionally, the concentration of graphene oxide in the graphene oxide dispersion is 0.5 to 3 mg / mL.

[0014] Optionally, the amino modifier is selected from one or more combinations of 2-aminobenzamide, 3,5-diaminobenzoic acid, polyaniline, 3,5-diaminobenzenesulfonic acid, and polyvinylpyrrolidone.

[0015] Optionally, the inorganic acid is selected from one or more combinations of sulfuric acid, hydrochloric acid, and phosphoric acid; and / or

[0016] The inorganic salt is selected from one or more combinations of ammonium sulfate, sodium sulfate, potassium sulfate, and sodium chloride.

[0017] Optionally, the expanded graphite deposit is obtained by the following method:

[0018] Under ice bath conditions, graphite raw materials are mixed evenly with concentrated sulfuric acid and hydrogen peroxide, and then allowed to stand at room temperature for 4 to 8 hours to obtain highly cross-linked expanded graphite aggregates.

[0019] Optionally, the graphite raw material is selected from one or more combinations of natural flake graphite, microcrystalline graphite, artificial graphite, and Kish graphite.

[0020] Optionally, the aqueous resin emulsion is selected from one or more combinations of aqueous epoxy resin, aqueous acrylate and aqueous polyurethane.

[0021] Optionally, the curing agent is selected from one or more combinations of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and polyamide.

[0022] Optionally, the graphene oxide waterborne anti-corrosion coating is sprayed onto the surface of a metal substrate, cured at room temperature for 2 to 3 hours, and then transferred to an oven at 40 to 80 ℃ to dry for 6 to 48 hours to form a 20 to 50 micrometer thick anti-corrosion protective coating.

[0023] In the anti-corrosion protective coating, the graphene oxide accounts for 0.05 to 0.5 wt.% by mass.

[0024] In a second aspect, the present application provides a graphene oxide waterborne anticorrosive coating prepared by the method of the first aspect.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] The present application provides a method for preparing graphene oxide waterborne anticorrosive coating, comprising: taking an expanded graphite accumulation body as an anode, a metal conductive material as a cathode, and inserting into an electrolyte containing a modifier to perform electrochemical exfoliation; the electrolyte after reaction is subjected to suction filtration, washing and centrifugal treatment, and the supernatant is taken to obtain a graphene oxide dispersion; the graphene oxide dispersion and a waterborne resin emulsion are fully mixed in a mass ratio of (0.8 ~ 1.6): 1, and then a curing agent is fully mixed to obtain the graphene oxide waterborne anticorrosive coating; wherein the electrolyte is composed of a mixed system of a modifier and an inorganic acid / salt, the molar ratio of the modifier to the inorganic acid / salt is (0 ~ 0.5):(0.1 ~ 1), the mass ratio of the curing agent to the waterborne resin emulsion is (0.2 ~ 1.0): 1, and the modifier is an amino-modified agent.

[0027] In the preparation method provided by the present application, the deep oxidation and modification of the expanded graphite accumulation body are realized in one step by constructing an electrolytic cell and using electrochemical treatment. Since graphene oxide itself has a certain hydrophilicity, its hydrophilicity is further enhanced after amino modification, and its dispersibility in water or polar solvents is significantly improved. This enables the amino-modified graphene oxide to be more uniformly dispersed in the application field of coatings, and good dispersibility can make the graphene oxide better combined with the matrix material, thereby improving the overall performance of the composite material. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0029] Figure 1 A flow chart of the method for preparing graphene oxide waterborne anticorrosive coating provided by the embodiments of the present application is shown;

[0030] Figure 2 A Raman surface scanning graph of the graphene oxide waterborne anticorrosive coating provided by the embodiments of the present application is shown;

[0031] Figure 3 A scanning electron microscope graph of the cross section of the graphene oxide waterborne anticorrosive coating provided by the embodiments of the present application is shown;

[0032] Figure 4 A cross-sectional scanning electron microscope image of another graphene oxide waterborne anticorrosive coating provided by an embodiment of the present application is shown;

[0033] Figure 5 A cross-sectional scanning electron microscope image of another graphene oxide waterborne anticorrosive coating provided by an embodiment of the present application is shown;

[0034] Figure 6 A cross-sectional scanning electron microscope image of an anticorrosive coating provided by a comparative example of the present application is shown. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way limiting on the application or its applications or uses. Based on the embodiments in the present application, any person skilled in the art, under the inspiration of the present application or by combining the present application with other prior art features, obtains any product same or similar to the present application, which falls within the protection scope of the present application. In addition, all other embodiments obtained by those of ordinary skill in the art without carrying out creative labor are within the protection scope of the present application.

[0036] The specific experimental steps or conditions not mentioned in the embodiments can be carried out according to the conventional experimental steps or conditions described in the prior art in the field. The reagents and other instruments not mentioned by the manufacturer are all conventional reagent products that can be obtained by purchase. In addition, the drawings are only schematic illustrations of the embodiments of the present application, and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and thus repeated description thereof will be omitted. Some block diagrams shown in the drawings are functional entities, which do not necessarily correspond to physically or logically independent entities.

[0037] The techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as part of the authorized description under appropriate circumstances.

[0038] In the description of the present application, it should be understood that the use of the words "first", "second", and the like to qualify elements is only for the convenience of distinguishing the corresponding elements, and the above words have no special meaning unless otherwise stated, and therefore cannot be understood as limiting the scope of protection of the present application.

[0039] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0040] The embodiment of the present application is as follows:

[0041] In a first aspect, the present application provides a preparation method of graphene oxide water-based anticorrosive paint, Figure 1 The preparation method of the graphene oxide water-based anticorrosive paint is shown in the flow chart of the embodiment of the present application, as shown in the figure, comprising the following steps: Figure 1

[0042] S1, taking the expanded graphite accumulation body as the anode and the metal conductive material as the cathode, inserting into the electrolyte containing the modifier, and performing electrochemical exfoliation, and then the electrolyte after the reaction is subjected to suction filtration, washing and centrifugal treatment, and the supernatant is taken to obtain the graphene oxide dispersion liquid;

[0043] In the specific implementation of this step, the graphite material participating in the electrochemical exfoliation is the expanded graphite accumulation body, and the expanded graphite accumulation body is specifically the graphite raw material treated by concentrated sulfuric acid and hydrogen peroxide. After the treatment of concentrated sulfuric acid and hydrogen peroxide, the graphite raw material is converted into graphene oxide, which has rich oxygen-containing functional groups such as carboxyl, hydroxyl and epoxy groups on the structure, and the interlayer spacing is also increased compared with the original graphite. These changes lay an important foundation for the subsequent electrolysis process. For example, the increased interlayer spacing makes the electrolyte more easily enter the material inside, so as to better participate in the electrolysis reaction; and the existence of oxygen-containing functional groups changes the electrical properties of the material, so that it has different reactivity and behavior in electrolysis than the original graphite. In addition, the graphene oxide has good dispersion effect in water or suitable electrolyte solution due to the hydrophilicity brought by the surface functional groups, which makes it more uniformly distributed in the electrolyte during electrolysis compared with the difficult dispersion of the original graphite, ensures that the entire electrolysis process can be carried out more evenly in each part, avoids the abnormal local reaction caused by agglomeration and other problems, and is more conducive to realizing stable and predictable electrolysis reaction, which helps to improve the uniformity of the product.

[0044] In some embodiments, the graphite raw material can be selected from one or more combinations of natural flake graphite, microcrystalline graphite, artificial graphite, Kish graphite, and preferably natural flake graphite.

[0045] In the specific implementation of this step, first, the highly cross-linked expanded graphite accumulation body is transferred to a container with small holes uniformly opened on the periphery, and the material of the container is preferably plastic material, and then the conductive metal is inserted into the graphite accumulation body to complete the assembly of the anode; the metal material as the cathode can be selected from platinum wire or platinum sheet, so that the electrode formed in this way ensures that the expanded graphite accumulation body located in the anode only exists in the anode area of the electrochemical reaction, so that the graphite accumulation body can fully participate in the electrochemical intercalation and exfoliation reaction; at the same time, the exfoliated graphene oxide can escape from the reaction area through the side wall through hole of the container, ensuring the normal progress of the subsequent electrochemical exfoliation and improving the yield of graphene oxide.

[0046] ​In some embodiments, the electrolyte is composed of a mixture of a modifier and an inorganic acid / salt, with a molar ratio of (0 ~ 0.5):(0.1 ~ 1). The amino modifier is selected from one or more combinations of 2-aminobenzamide, 3,5-diaminobenzoic acid, polyaniline, 3,5-diaminobenzenesulfonic acid, and polyvinylpyrrolidone. The presence of the amino modifier in the electrolyte allows the graphite aggregate to be further electrolytically oxidized into graphene oxide. The introduction of amino groups also increases the chemical affinity of graphene oxide with other materials, thereby improving the processing performance of amino-modified graphene oxide. For example, in the preparation of anti-corrosion coatings, amino-modified graphene oxide is easier to mix evenly with other matrix materials and can better maintain its dispersion state during processing, which is beneficial to improving processing efficiency and product quality. In addition, amino-modified graphene oxide can interact with the active groups on the polymer molecular chains in coatings to form hydrogen bonds, covalent bonds, etc., thereby enhancing the interfacial bonding force between graphene oxide and polymers. This enhanced interfacial bonding force helps to improve the overall mechanical properties of coatings, such as tensile strength and impact strength, and enhances their durability.

[0047] S2. The modified graphene dispersion with a mass ratio of (0.8 ~ 1.6):1 is thoroughly mixed with the aqueous resin emulsion, and then thoroughly mixed with the curing agent to obtain the graphene oxide aqueous anti-corrosion coating.

[0048] In this specific implementation step, the modified graphene dispersion obtained from step S1 above exhibits good dispersibility and chemical affinity with other materials. As a component of the anti-corrosion coating, it is thoroughly mixed with an aqueous resin emulsion at a mass ratio of (0.8 ~ 1.6): 1. The resulting mixture is then thoroughly mixed with a certain amount of curing agent to obtain an aqueous graphene oxide anti-corrosion coating. The concentration of the graphene oxide dispersion involved in the mixing is 0.5 ~ 3 mg / m³. The aqueous resin emulsion is selected from one or more combinations of aqueous epoxy resin, aqueous acrylate, and aqueous polyurethane. The curing agent is selected from one or more combinations of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and polyamide.

[0049] Furthermore, an aqueous anti-corrosion coating of graphene oxide is sprayed onto the surface of a metal substrate and cured at room temperature for 2–3 hours. Then, it is transferred to an oven at 40–80 °C and dried for 6–48 hours to form a 20–50 micrometer-thick anti-corrosion protective coating. The graphene oxide content in the anti-corrosion protective coating is 0.05–0.5 wt.%.

[0050] In a second aspect, the present invention provides an aqueous anti-corrosion coating of graphene oxide obtained by the preparation method described in the first aspect above.

[0051] In order to make the person skilled in the art more clearly understand the present application, the present application is described in detail by the following examples.

[0052] Example 1

[0053] 0.5 g of natural flake graphite (100 mesh) was uniformly mixed with 7 mL of concentrated sulfuric acid and 3.6 mL of hydrogen peroxide under ice bath conditions, and was left to stand at room temperature for 4 h to obtain intercrosslinked worm-like expanded graphite; the expanded graphite was transferred to a container with uniformly distributed small holes on the wall as an electrochemical anode, a platinum wire as a cathode, and 0.5 mol / L ammonium sulfate solution as an electrolyte for electrochemical exfoliation; the product after reaction was filtered, washed and centrifuged to obtain an oxidized graphene dispersion of 1 mg / mL;

[0054] 8 g of the oxidized graphene dispersion was mixed with 10 g of an aqueous epoxy resin emulsion, stirred for 30 min, and then 5 g of a curing agent diethylenetriamine was added and stirred for another 30 min to obtain an oxidized graphene composite coating (the content of oxidized graphene was 0.1 wt.%);

[0055] The composite coating prepared above was sprayed onto the surface of a polished Q235 steel, and after being cured to dry at room temperature for 2 h, it was placed in a 40 ℃ oven for drying for 48 h to obtain an anti-corrosion coating with a thickness of 42 microns.

[0056] Figure 2 The Raman mapping of the aqueous anti-corrosion coating of graphene oxide provided by the embodiment of the present application is shown in FIG. 1. Figure 2 As shown in FIG. 1, the D band of graphene oxide (GO) at 1350 cm −1 and the peak intensity ratio of the epoxy resin at 1100 cm −1 The normalized distribution diagram shows that the electrochemically exfoliated graphene oxide can be uniformly dispersed in the aqueous epoxy coating.

[0057] Figure 3 The cross-sectional scanning electron microscope image of the aqueous anti-corrosion coating of graphene oxide provided by the embodiment of the present application is shown in FIG. 2. Figure 3 As shown in FIG. 2, the addition of 0.1 wt.% of graphene oxide reduces the voids and cracks generated during the curing process of the coating, and improves the physical barrier properties of the coating.

[0058] Example 2

[0059] 0.5 g natural flake graphite (100 mesh) was uniformly mixed with 7 mL concentrated sulfuric acid and 3.6 mL hydrogen peroxide under ice bath condition, and was left to stand at room temperature for 4 h to obtain intercrosslinked worm-like expanded graphite; the expanded graphite was transferred into a container with uniformly distributed small holes on the wall as an electrochemical anode, a platinum wire as a cathode, and an electrolyte of 0.5 mol / L ammonium sulfate solution for electrochemical exfoliation; the product after reaction was centrifuged after being washed by suction filtration to obtain a graphene oxide dispersion of 1.5 mg / mL;

[0060] 10 g of the graphene oxide dispersion was mixed with 10 g of water-based epoxy resin emulsion, and 5 g of curing agent diethylene triamine was added after stirring for 30 min, and the stirring was continued for 30 min to obtain a graphene oxide composite coating (graphene oxide content of 0.2 wt.%);

[0061] The above prepared composite coating was sprayed onto the surface of polished Q235 steel, and was left to stand at room temperature for 2 h to be surface-dried, and was then placed in a 40 ℃ oven for drying for 48 h to obtain a corrosion-resistant coating with a thickness of 44 microns.

[0062] (The process of this example is the same as that of Example 1. The difference is that 10 g of the graphene oxide dispersion with a concentration of 1.5 mg / mL was mixed with water-based epoxy resin emulsion, and the coating thickness after curing was 44 microns.)

[0063] Example 3

[0064] 0.5 g natural flake graphite (100 mesh) was uniformly mixed with 7 mL concentrated sulfuric acid and 3.6 mL hydrogen peroxide under ice bath condition, and was left to stand at room temperature for 4 h to obtain intercrosslinked worm-like expanded graphite; the expanded graphite was transferred into a container with uniformly distributed small holes on the wall as an electrochemical anode, a platinum wire as a cathode, and an electrolyte of 0.5 mol / L ammonium sulfate solution for electrochemical exfoliation; the product after reaction was centrifuged after being washed by suction filtration to obtain a graphene oxide dispersion of 1.5 mg / mL;

[0065] 10 g of the graphene oxide dispersion was mixed with 10 g of water-based epoxy resin emulsion, and 5 g of curing agent diethylene triamine was added after stirring for 30 min, and the stirring was continued for 30 min to obtain a graphene oxide composite coating (graphene oxide content of 0.2 wt.%);

[0066] The above prepared composite coating was sprayed onto the surface of polished Q235 steel, and was left to stand at room temperature for 2 h to be surface-dried, and was then placed in a 40 ℃ oven for drying for 48 h to obtain a corrosion-resistant coating with a thickness of 44 microns.

[0067] Figure 4A cross-sectional scanning electron microscope image of another graphene oxide waterborne anticorrosive coating provided by the embodiment of the present application is shown in FIG. 4. As shown in FIG. 4, the graphene oxide added in an amount of 0.15 wt.% makes the coating matrix more compact, effectively filling the gaps and defects of the coating matrix, and is conducive to improving the corrosion resistance of the coating. Figure 4 As shown in FIG. 4, the graphene oxide added in an amount of 0.15 wt.% makes the coating matrix more compact, effectively filling the gaps and defects of the coating matrix, and is conducive to improving the corrosion resistance of the coating.

[0068] Example 4

[0069] Under ice bath conditions, 0.5 g of natural flake graphite (100 mesh) was uniformly mixed with 7 mL of concentrated sulfuric acid and 3.6 mL of hydrogen peroxide, and was left to stand at room temperature for 4 h to obtain intercrosslinked worm-like expanded graphite; the expanded graphite was transferred into a container with small holes on the wall as an electrochemical anode, a platinum wire as a cathode, and a mixed system of 0.5 mol / L ammonium sulfate solution and 0.1 mol / L 3,5-diamino benzoic acid as an electrolyte, and electrochemical exfoliation was performed; the product after reaction was extracted, washed, and centrifuged to obtain an oxidized graphene dispersion of 0.5 mg / mL;

[0070] 10 g of the graphene oxide dispersion was weighed and mixed with 10 g of waterborne epoxy resin emulsion, and after stirring for 60 min, 2 g of a curing agent, polyamide, was added, and stirring was continued for 60 min to obtain a graphene oxide composite coating;

[0071] The composite coating prepared above was sprayed onto the surface of a polished Q235 steel, and after curing to tack-free at room temperature for 2 h, it was placed in an 80 °C oven for drying for 12 h to obtain an anticorrosive coating with a thickness of 41 microns (graphene oxide content of 0.05 wt.%).

[0072] (The process of this example is the same as that of Example 3. The difference is that the electrolyte used is a mixed system of 0.5 mol / L ammonium sulfate and 0.1 mol / L 3,5-diamino benzoic acid; the modified graphene dispersion prepared has a concentration of 0.5 mg / mL, and the composite coating has a thickness of 41 microns.)

[0073] Example 5

[0074] Under ice bath conditions, 0.5 g of natural flake graphite (100 mesh) was uniformly mixed with 7 mL of concentrated sulfuric acid and 3.6 mL of hydrogen peroxide, and was left to stand at room temperature for 4 h to obtain intercrosslinked worm-like expanded graphite; the expanded graphite was transferred into a container with small holes on the wall as an electrochemical anode, a platinum wire as a cathode, and a mixed system of 0.5 mol / L ammonium sulfate solution and 0.1 mol / L 3,5-diamino benzoic acid as an electrolyte, and electrochemical exfoliation was performed; the product after reaction was extracted, washed, and centrifuged to obtain an oxidized graphene dispersion of 0.5 mg / mL;

[0075] Take 10 g of the above graphene oxide dispersion liquid, mix with 10 g of water-based epoxy resin emulsion, stir for 60 min, then add 5 g of curing agent diethylene triamine, continue to stir for 60 min, to obtain a modified graphene composite coating (graphene oxide content is 0.3 wt.% wt.%);

[0076] The above prepared composite coating is sprayed on the polished surface of Q235 steel, and after curing at room temperature for 2 h to surface dry, it is placed in an 80℃ oven for drying for 12 h to obtain a corrosion-resistant coating with a thickness of 38 microns.

[0077] (The process of this example is the same as that of Example 4. The difference is that the concentration of the prepared modified graphene dispersion liquid is 3 mg / mL, and the thickness of the composite coating is 38 microns.)

[0078] Figure 5 A cross-sectional scanning electron microscope image of another graphene oxide water-based corrosion-resistant coating provided by an embodiment of the application is shown. Figure 5 As shown, the modified graphene with an addition amount of 0.3 wt.% still has good dispersibility in the coating matrix, almost no defects and gain, and exhibits excellent corrosion resistance.

[0079] Example 6

[0080] Under ice bath conditions, 0.5 g of natural flake graphite (100 mesh) is uniformly mixed with 7 mL of concentrated sulfuric acid and 3.6 mL of hydrogen peroxide, and is left to stand at room temperature for 4 h to obtain intercrosslinked worm-like expanded graphite; the expanded graphite is transferred to a container with small holes on the wall as an electrochemical anode, a platinum wire as a cathode, and a mixed system of 0.5 mol / L ammonium sulfate solution and 0.1 mol / L 3,5-diamino benzoic acid as an electrolyte, and electrochemical exfoliation is carried out; the product after reaction is extracted, washed and centrifuged to obtain a 3 mg / mL graphene oxide dispersion liquid;

[0081] Take 14 g of the above graphene oxide dispersion liquid and mix with 10 g of water-based epoxy resin emulsion, stir for 60 min, then add 5 g of curing agent diethylene triamine, continue to stir for 60 min, to obtain a graphene oxide corrosion-resistant coating (graphene oxide content is 0.6 wt.% wt.%);

[0082] The above prepared composite coating is sprayed on the polished surface of Q235 steel, and after curing at room temperature for 2 h to surface dry, it is placed in an 80℃ oven for drying for 12 h to obtain a composite coating with a thickness of 42 microns.

[0083] (The process of this example is the same as that of Example 3. The difference is that 14 g of the graphene oxide dispersion liquid with a concentration of 3 mg / mL is mixed with the epoxy resin emulsion, and the thickness of the composite coating is 42 microns.)

[0084] Comparative Example 1

[0085] In this example, 10 g of an aqueous epoxy resin emulsion was mixed with 10 g of deionized water, 5 g of a curing agent diethylene triamine and stirred for 10 min to obtain an aqueous coating without graphene oxide; the above coating was sprayed onto a previously polished Q235 steel surface, and after curing to tack-free at room temperature, it was placed in a 60℃ oven for 24 h to dry, obtaining a blank coating with a thickness of 40 microns.

[0086] Figure 6 A cross-sectional scanning electron microscope image of the corrosion-resistant coating provided by the comparative example of the present application is shown in Figure 2. Figure 6 As shown in Figure 2, the corrosion-resistant coating shows obvious pores and defects, which are caused by solvent volatilization during the curing process of the epoxy resin matrix, providing a path for the penetration of corrosive media, and the corrosion resistance is poor.

[0087] Experimental Example

[0088] The corrosion-resistant coatings prepared in Examples 1-6 and Comparative Example 1 above were simultaneously immersed in a 3.5 wt.% sodium chloride solution for 48 h, and the corrosion rate of the metal substrate protected by the coating was calculated according to the Tafel electrochemical test, and the test results are shown in Table 1:

[0089] Table 1 Performance parameters of the coating

[0090]

[0091] As can be seen from the test data in Table 1, the corrosion-resistant coating provided by the examples of the present application exhibits a lower corrosion rate compared to the blank coating of the comparative example, which indicates that the graphene oxide prepared by electrochemical exfoliation can be uniformly dispersed in the coating matrix, effectively filling the voids formed inside the coating, prolonging the path of the corrosive medium through the coating, and improving the corrosion resistance of the coating.

[0092] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification.

[0093] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0094] The above provides a detailed description of the graphene oxide waterborne anti-corrosion coating and its preparation method provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing an aqueous anticorrosive graphene oxide coating, characterized by, Comprising: An expanded graphite accumulation body is used as an anode, a metal conductive material is used as a cathode, and it is inserted into an electrolyte to perform electrochemical exfoliation. The electrolyte after the reaction is subjected to suction filtration, washing and centrifugal treatment, and the supernatant is taken to obtain a graphene oxide dispersion liquid; The graphene oxide dispersion liquid with a mass ratio of (0.8 ~ 1.6):1 is mixed with a water-based resin emulsion, and then mixed with a curing agent to obtain the graphene oxide water-based anticorrosive coating; The electrolyte is composed of a modifier and a mixed system of inorganic acid / inorganic salt, the molar ratio of the modifier to the inorganic acid / inorganic salt is (0 ~ 0.5):(0.1 ~ 1), and the value of the modifier in the molar ratio is not 0; The mass ratio of the curing agent to the water-based resin emulsion is (0.2 ~ 1.0):1; The modifier is an amino modifier; The amino modifier is selected from one or more combinations of 2-aminobenzamide, 3,5-diaminobenzoic acid, polyaniline, 3,5-diaminobenzenesulfonic acid and polyvinylpyrrolidone; The inorganic salt is selected from one or more combinations of ammonium sulfate, sodium sulfate, potassium sulfate and sodium chloride.

2. The method for preparing the waterborne anticorrosive coating of graphene oxide according to claim 1, characterized in that, The concentration of graphene oxide in the graphene oxide dispersion liquid is 0.5 ~ 3 mg / mL.

3. The method for preparing the graphene oxide waterborne anti-corrosion coating according to claim 1, characterized in that, The inorganic acid is selected from one or more combinations of sulfuric acid, hydrochloric acid and phosphoric acid.

4. The method for preparing the waterborne anticorrosive coating of graphene oxide according to claim 1, characterized in that, The expanded graphite accumulation body is obtained by the following method: Under ice bath conditions, the graphite raw material is uniformly mixed with concentrated sulfuric acid and hydrogen peroxide, and after standing at room temperature for 4 ~ 8 h, a highly cross-linked expanded graphite accumulation body is obtained.

5. The method for preparing the graphene oxide waterborne anticorrosive coating according to claim 4, characterized in that, The graphite raw material is selected from one or more combinations of natural flake graphite, microcrystalline graphite, artificial graphite and Kish graphite.

6. The method for preparing the waterborne anticorrosive coating of graphene oxide according to claim 1, characterized in that, The water-based resin emulsion is selected from one or more combinations of water-based epoxy resin, water-based acrylate and water-based polyurethane.

7. The method for preparing the waterborne anticorrosive coating of graphene oxide according to claim 1, characterized in that, The curing agent is selected from one or more combinations of diethylene triamine, triethylene tetramine, tetraethylene pentamine and polyamide.

8. The method for preparing the waterborne anticorrosive coating of graphene oxide according to claim 1, characterized in that, The graphene oxide water-based anticorrosive coating is sprayed onto the surface of a metal substrate, and after curing at room temperature for 2-3 h, it is transferred to a 40-80 ℃ oven for drying for 6-48 h to form a 20-50 micron thick anticorrosive protective coating; In the anticorrosive protective coating, the mass fraction of graphene oxide is 0.05-0.5 wt.%.

9. A graphene oxide water-based anticorrosive coating obtained by the preparation method of any one of claims 1-8.

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