Modified graphene water-based anticorrosive paint and preparation method thereof

Abstract

The application discloses a modified graphene water-based anticorrosive paint and a preparation method thereof. The anticorrosive paint comprises, in mass parts, 80-120 parts of a water-based epoxy resin, 1-3 parts of modified graphene, 10-30 parts of a curing agent, 20-30 parts of a filler, 1-2 parts of a leveling agent, 0.5-1 part of a defoaming agent and 0.5-1 part of a dispersing agent. The modified graphene is surfactant-modified fluorine-doped graphene or surfactant-modified nickel oxide@fluorine-doped graphene. The fluorine-doped graphene is used as a physical barrier, the dispersibility of the fluorine-doped graphene in the paint system is enhanced due to the presence of the surfactant, further, the nanostructured nickel oxide is formed in situ on the surface of the fluorine-doped graphene, a more stable protective layer can be formed in the initial stage of corrosion of the steel material, and the anticorrosive performance and mechanical performance of the paint are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-corrosion coatings, and in particular to a modified graphene water-based anti-corrosion coating and a preparation method thereof. Background Art

[0002] Steel corrosion is a destructive erosion caused by chemical or electrochemical reactions between steel and its surroundings. Corrosion not only consumes resources but also damages the structure of infrastructure and industrial equipment, rendering them inoperable and potentially causing major accidents and disasters. The most widely used, effective, and cost-effective method for protecting steel from corrosion is to apply an anti-corrosion coating. Currently, oil-based anti-corrosion coatings contain large amounts of volatile organic compounds (VOCs), which can cause significant harm to humans and the environment. Therefore, environmentally friendly water-based anti-corrosion coatings have become a hot topic of research.

[0003] Graphene has chemical resistance, thermal stability and physical barrier properties. Adding it to coatings can effectively prevent the infiltration of gas and liquid, making it have broad prospects in the field of corrosion protection. However, the dispersibility problem of graphene in coatings has been difficult to solve. Good dispersion can enhance the corrosion resistance of coatings. If the dispersion is poor, the integrity of the original coating will be destroyed, and the corrosion rate will be accelerated. Therefore, graphene often needs to be modified. CN107805442A discloses a graphene-modified water-based anticorrosive coating and a preparation method thereof. Graphene is added to an acrylic emulsion by chemical connection, which improves the dispersibility of graphene in the coating system and its compatibility with other base materials, and changes the drawbacks of graphene oxide due to its severe damage to its lamellar structure and a significant decrease in corrosion resistance. CN115637095A discloses a modified graphene water-based anticorrosive coating and a preparation method thereof. Graphene oxide is co-modified with octadecylamine and silane, which significantly improves the adhesion of the coating and the salt and acid mist resistance.

[0004] Therefore, adding graphene to a water-based coating system after proper modification can effectively improve the overall performance of the coating. At the same time, given that the adhesion and corrosion resistance of existing water-based coatings are still not high enough, it is necessary to provide a new type of modified graphene water-based anti-corrosion coating. Summary of the Invention

[0005] In order to solve the technical problems existing in the prior art, the present invention provides a modified graphene water-based anti-corrosion coating, which comprises, by mass,

[0006] 80-120 parts of waterborne epoxy resin, 1-3 parts of modified graphene, 10-30 parts of curing agent, 20-30 parts of filler, 1-2 parts of leveling agent, 0.5-1 part of defoaming agent, 0.5-1 part of dispersant;

[0007] The modified graphene is surfactant-modified fluorine-doped graphene or surfactant-modified nickel oxide@fluorine-doped graphene.

[0008] The fluorine-doped graphene dopes fluorine elements in the carbon skeleton, and has been considered by some studies to have low surface energy and better barrier property, and may have better corrosion resistance than graphene. However, compared with graphene, fluorine-doped graphene has less research in the field of coatings. The fluorine-doped graphene can be further treated with a surfactant to further reduce the surface energy and improve the dispersion performance in the coating system. At present, some studies also consider that adding metal oxide nanoparticles to the coating system can release metal ions to form a stable barrier with early corrosion products to prevent further corrosion in the early stage of corrosion of steel. Using a hydrothermal reaction can form metal nanoparticles on the surface of fluorine-doped graphene, and using surfactant treatment, such a scheme is rarely reported, and it is necessary to study the corrosion mechanism of such a method.

[0009] Further, the preparation method of the surfactant-modified nickel oxide@fluorine-doped graphene is,

[0010] 0.5-1 parts of soluble nickel salt, 1-3 parts of fluorine-doped graphene, and 200-500 parts of water are stirred and mixed, and then subjected to a hydrothermal reaction at 160-200 DEG C. After the reaction, the insoluble substance is collected and calcined at 200-350 DEG C to obtain nickel oxide@fluorine-doped graphene;

[0011] 1-3 parts of nickel oxide@fluorine-doped graphene, 0.2-0.5 parts of surfactant, and 100-300 parts of water are stirred and mixed for 1-3 hours, and the insoluble substance is collected to obtain surfactant-modified nickel oxide@fluorine-doped graphene.

[0012] Further, the preparation method of the surfactant-modified fluorine-doped graphene is,

[0013] 1-3 parts of fluorine-doped graphene, 0.2-0.5 parts of surfactant, and 100-300 parts of water are stirred and mixed for 1-3 hours, and the insoluble substance is collected to obtain surfactant-modified fluorine-doped graphene.

[0014] Further, the preparation method of the fluorine-doped graphene is,

[0015] The graphene is calcined at 300-500 DEG C for 1-3 hours in an atmosphere of fluorine gas and protective gas to obtain fluorine-doped graphene.

[0016] Further, the surfactant is at least one of polyvinylpyrrolidone, sodium dodecyl benzene sulfonate, sodium dodecyl sulfonate, dodecyl amine polyoxyethylene ether double quaternary ammonium salt, and cetyl dimethyl ammonium bromide.

[0017] Further, the filler is at least one of titanium dioxide, zinc oxide, and barium sulfate with a mesh of 325-2000.

[0018] Further, the leveling agent is a modified polyether siloxane type leveling agent.

[0019] Further, the defoaming agent is a silicone type defoaming agent.

[0020] Further, the dispersing agent is at least one of an alkylol ammonium salt of an acid group-containing copolymer, a sodium salt of a polycarboxylic acid, a potassium salt of polyacrylic acid, and a sodium salt of polyacrylic acid.

[0021] The application also provides a preparation method of the modified graphene water-based anticorrosive paint, comprising,

[0022] The water-based epoxy resin and the modified graphene are stirred and mixed, and then the curing agent, the filler, the leveling agent, the defoaming agent, and the dispersing agent are added and continuously stirred and mixed to obtain the modified graphene water-based anticorrosive paint.

[0023] Compared with the prior art, the application has the following beneficial effects:

[0024] The application uses fluorine-doped graphene as a physical barrier, and the presence of a surfactant enhances the dispersibility of the fluorine-doped graphene in the paint system. Further, nanostructured nickel oxide is formed in situ on the surface of the fluorine-doped graphene, which can form a more stable protective layer in the early stage of corrosion of the steel material, thereby improving the corrosion resistance and mechanical properties of the paint and preventing deep corrosion of the steel material. DETAILED DESCRIPTION

[0025] The endpoints of the ranges and any values disclosed in the present disclosure are not to be understood as being limited to the exact values recited as the exact dimensions are not to be construed as being critical. It is to be understood that the ranges involved are also contemplated as within the scope of the application, even if the minimum and maximum values of the ranges are not expressly stated. For values having been stated as approximations, it is to be understood that the intended are also contemplated as within the scope of the application. Thus, it is to be understood that the ranges involved are also contemplated as within the scope of the application, even if the minimum and maximum values of the ranges are not expressly stated.

[0026] Part of the raw materials used in the embodiments of the application are introduced as follows:

[0027] The water-based epoxy resin is Model E51128, which is purchased from Shandong Kaipuole Biotechnology Co., Ltd.

[0028] The graphene is Model MSTN-PGO, which is purchased from Beijing Meisitong Science and Technology Development Co., Ltd.

[0029] The dodecylamine polyoxyethylene ether double-quaternary ammonium salt is Model CY-302, which is purchased from Hubei Changyao Biotechnology Co., Ltd.

[0030] Polyvinylpyrrolidone, model K30 Powder, was purchased from BASF AG, Germany;

[0031] Aromatic amine curing agent, brand CYDHD-113, purchased from Henan Huineng Resin Co., Ltd.

[0032] Titanium dioxide, particle size 1000 mesh, was purchased from Hebei Laiyi New Material Technology Co., Ltd.

[0033] Modified polyether siloxane leveling agent, model BYK-320, purchased from BYK, Germany;

[0034] Silicone defoamer, model BYK-028, purchased from BYK, Germany;

[0035] Alkylhydroxyl ammonium salt dispersant containing acidic group copolymer, model VOK-N 21938, Volker, Germany;

[0036] The preparation method of fluorine-doped graphene used in the embodiment is as follows: 0.5 g of graphene is placed in an atmosphere of fluorine and nitrogen (the volume ratio of fluorine and nitrogen is 1:5), calcined at 350° C. for 2 h, naturally cooled to room temperature, washed and dried to obtain fluorine-doped graphene.

[0037] The preparation method of nickel oxide @ fluorine-doped graphene used in the embodiment is as follows: 1g of nickel nitrate hexahydrate, 1g of fluorine-doped graphene, and 300ml of water are stirred and mixed, and then placed in a hydrothermal reaction at 180°C for 18h. After the reaction, the insoluble matter is filtered and collected, washed three times with ethanol and water respectively, and then dried. Then, it is placed in a nitrogen atmosphere muffle furnace and calcined at 350°C to obtain nickel oxide @ fluorine-doped graphene.

[0038] In the embodiments, the methods for modification using surfactant are as follows: 2 g of fluorine-doped graphene or nickel oxide @ fluorine-doped graphene, 0.3 g of surfactant (selected according to the specific embodiment), and 300 g of water are stirred and mixed at 500 rpm for 2 h. After the mixture is filtered, washed three times with water, and then dried to obtain surfactant-modified fluorine-doped graphene or surfactant-modified nickel oxide @ fluorine-doped graphene.

[0039] Other raw materials not mentioned are common raw materials in this field and will not be described in detail.

[0040] The following will be combined with specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] Example 1

[0042] A method for preparing a modified graphene water-based anti-corrosion coating comprises the following steps:

[0043] 1. Weigh 1 kg of waterborne epoxy resin, 0.02 kg of fluorine-doped graphene modified with diquaternary ammonium salt of dodecylamine polyoxyethylene ether, 0.2 kg of aromatic amine curing agent, 0.2 kg of titanium dioxide, 0.01 kg of modified polyether siloxane type leveling agent, 0.005 kg of silicone defoaming agent, and 0.005 kg of alkylhydroxyl ammonium salt type dispersant of acidic group copolymer;

[0044] 2. The water-based epoxy resin and the fluorine-doped graphene modified with diquaternary ammonium salt of dodecylamine polyoxyethylene ether were stirred at 500 rpm for 30 min to mix evenly, and then an aromatic amine curing agent, titanium dioxide, a modified polyether siloxane type leveling agent, a silicone defoaming agent, and an alkylhydroxyl ammonium salt dispersant of an acidic group copolymer were added, and the stirring was continued for 1 h to obtain the modified graphene water-based anti-corrosion coating.

[0045] Example 2

[0046] A method for preparing a modified graphene water-based anti-corrosion coating comprises the following steps:

[0047] 1. Weigh 1 kg of waterborne epoxy resin, 0.02 kg of sodium dodecylbenzenesulfonate-modified nickel oxide @ fluorine-doped graphene, 0.2 kg of aromatic amine curing agent, 0.2 kg of titanium dioxide, 0.01 kg of modified polyether siloxane leveling agent, 0.005 kg of silicone defoaming agent, and 0.005 kg of alkylhydroxyl ammonium salt dispersant of acidic group copolymer;

[0048] 2. The water-based epoxy resin and sodium dodecylbenzenesulfonate-modified nickel oxide @ fluorine-doped graphene were stirred at 500 rpm for 30 min to mix evenly, and then an aromatic amine curing agent, titanium dioxide, modified polyether siloxane type leveling agent, silicone defoaming agent, and alkylhydroxyl ammonium salt dispersant of an acidic group copolymer were added, and the stirring was continued for 1 h to obtain the modified graphene water-based anti-corrosion coating.

[0049] Example 3

[0050] A method for preparing a modified graphene water-based anti-corrosion coating comprises the following steps:

[0051] 1. Weigh 1 kg of waterborne epoxy resin, 0.02 kg of polyvinylpyrrolidone-modified nickel oxide @ fluorine-doped graphene, 0.2 kg of aromatic amine curing agent, 0.2 kg of titanium dioxide, 0.01 kg of modified polyether siloxane leveling agent, 0.005 kg of silicone defoaming agent, and 0.005 kg of alkylhydroxyl ammonium salt dispersant of acidic group copolymer;

[0052] 2. The water-based epoxy resin and polyvinyl pyrrolidone-modified nickel oxide @ fluorine-doped graphene were stirred at 500 rpm for 30 minutes to mix evenly, and then an aromatic amine curing agent, titanium dioxide, modified polyether siloxane type leveling agent, silicone defoaming agent, and alkylhydroxyl ammonium salt dispersant of an acidic group copolymer were added, and the stirring was continued for 1 hour to obtain the modified graphene water-based anti-corrosion coating.

[0053] Example 4

[0054] A method for preparing a modified graphene water-based anti-corrosion coating comprises the following steps:

[0055] 1. Weigh 1 kg of waterborne epoxy resin, 0.02 kg of hexadecyldimethylammonium bromide-modified nickel oxide @ fluorine-doped graphene, 0.2 kg of aromatic amine curing agent, 0.2 kg of titanium dioxide, 0.01 kg of modified polyether siloxane leveling agent, 0.005 kg of silicone defoaming agent, and 0.005 kg of alkylhydroxyl ammonium salt dispersant of acidic group copolymer;

[0056] 2. The water-based epoxy resin and hexadecyldimethylammonium bromide-modified nickel oxide @ fluorine-doped graphene were stirred at 500 rpm for 30 minutes to mix evenly, and then an aromatic amine curing agent, titanium dioxide, modified polyether siloxane type leveling agent, silicone defoaming agent, and alkylhydroxyl ammonium salt dispersant of an acidic group copolymer were added, and the stirring was continued for 1 hour to obtain the modified graphene water-based anti-corrosion coating.

[0057] Example 5

[0058] A method for preparing a modified graphene water-based anti-corrosion coating comprises the following steps:

[0059] 1. Weigh 1 kg of waterborne epoxy resin, 0.02 kg of dodecylamine polyoxyethylene ether diquaternary ammonium salt-modified nickel oxide @ fluorine-doped graphene, 0.2 kg of aromatic amine curing agent, 0.2 kg of titanium dioxide, 0.01 kg of modified polyether siloxane type leveling agent, 0.005 kg of silicone defoaming agent, and 0.005 kg of alkylhydroxyl ammonium salt type dispersant of acidic group copolymer;

[0060] 2. The water-based epoxy resin and dodecylamine polyoxyethylene ether diquaternary ammonium salt-modified nickel oxide @ fluorine-doped graphene were stirred at 500 rpm for 30 minutes to mix evenly, and then aromatic amine curing agent, titanium dioxide, modified polyether siloxane type leveling agent, silicone defoaming agent, and alkylhydroxyl ammonium salt dispersant of acidic group copolymer were added, and stirring was continued for 1 hour to obtain the modified graphene water-based anti-corrosion coating.

[0061] Comparative Example 1

[0062] It is basically the same as Example 1, with the only difference being that fluorine-doped graphene is used instead of dodecylamine polyoxyethylene ether diquaternary ammonium salt to modify the fluorine-doped graphene.

[0063] Comparative Example 2

[0064] It is basically the same as Example 1, with the only difference being that it does not contain fluorine-doped graphene modified with dodecylamine polyoxyethylene ether diquaternary ammonium salt.

[0065] Test Case

[0066] In order to test the performance of the coatings of the examples and comparative examples, these coatings were evenly coated on a polished Q235 steel surface using a spray gun, with the coating thickness controlled to be 150 μm, and then completely cured at room temperature to form a coating for performance testing.

[0067] The coating adhesion was measured and rated according to the standard GB / T 9286-2021 "Paint and varnish - Cross-cut test for paint films". The results are shown in Table 1. The lower the grade number, the higher the adhesion, and 0 is the highest grade. The impact resistance of the coating was measured according to the standard GB / T1732-2020 "Determination of impact resistance of paint films". The hardness of the coating was tested according to ISO 15184-2020 "Paints and varnishes. Determination of film hardness by pencil test".

[0068] Table 1 Coating adhesion results

[0069]

[0070] As can be seen from the coating adhesion test results in Table 1, Comparative Example 2, which does not contain graphene material, has the lowest adhesion, while Comparative Example 1 has greater adhesion than Comparative Example 2. This indicates that fluorine-doped graphene increases the contact area between the coating and the substrate, thereby improving coating adhesion. The adhesion of Examples 1 to 5 all reached the highest level, demonstrating that modifying fluorine-doped graphene with dodecylamine polyoxyethylene ether diquaternary ammonium salt can enhance coating adhesion. The nickel oxide @ fluorine-doped graphene and a series of surfactant systems have good properties and can improve coating adhesion. As can be seen from the coating impact resistance test results in Table 1, Examples 2 to 5, which have fluorine-doped graphene with nickel oxide on the surface, have better impact resistance, especially Example 5. This is because the structure of nickel oxide particles and fluorine-doped graphene absorbs energy when the coating is impacted, thereby improving the coating's impact resistance. Furthermore, compared to other surfactants, the modification of nickel oxide @ fluorine-doped graphene with dodecylamine polyoxyethylene ether diquaternary ammonium salt and its addition to the coating system can form a denser coating on the metal surface. From the test results of the coating hardness, it can be seen that Examples 2 to 5 of the fluorine-doped graphene with nickel oxide on the surface also have better hardness.

[0071] The corrosion resistance of coating samples was tested according to the standard GB / T 1771-2007, "Paints and varnishes - Determination of resistance to neutral salt spray." After cross-scribing the test surface, the specimen was tilted at a 30° angle to the vertical in a salt spray test chamber. The corrosion solution consisted of a 5 wt.% NaCl solution, maintained at a chamber temperature of 35 ± 2°C, a pressure vessel temperature of 47 ± 2°C, and a pH of 6.5 to 7.2. The spray was applied continuously for 600 hours. Table 2 summarizes the coating sample's performance after the salt spray test.

[0072] Table 2 Status of coating samples after salt spray test

[0073]

[0074] From the test results in Table 2, it can be seen that after the fluorine-doped graphene surface is formed into nickel oxide particles, the use of different surfactants to treat can effectively improve the corrosion resistance of the coating, especially the gemini surfactant dodecylamine polyoxyethylene ether diquaternary ammonium salt. This may be because in the early stage of the corrosion reaction, dodecylamine polyoxyethylene ether diquaternary ammonium salt can promote the formation of a more stable structure between nickel ions and iron corrosion products, thereby inhibiting the further progress of the corrosion reaction.

[0075] Using an electrochemical workstation, a saturated calomel electrode was used as the reference electrode, a platinum electrode was used as the auxiliary electrode, and the electrode with the coating was used as the working electrode. The polarization curve was obtained to calculate the corrosion current density. The test area was 0.785 cm 2 The test solution is 3.5wt.% NaCl solution. After the sample is in a stable state under the open circuit voltage test, the open circuit voltage value is obtained, and then the scanning voltage range is set to open circuit voltage ± 500mV, the potential scanning rate is 1mV / s, and the frequency range is 10 -2 ~10 5 Hz. The corrosion current density and corrosion potential results are shown in Table 3.

[0076] Table 3 Corrosion current density and corrosion potential results

[0077]

[0078] From the test results in Table 3, it can be seen that the use of dodecylamine polyoxyethylene ether diquaternary ammonium salt to modify nickel oxide @ fluorine-doped graphene in the present invention can significantly improve the corrosion performance of the coating.

[0079] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A modified graphene water-based anti-corrosion coating, characterized in that: In parts by mass, 80-120 parts of waterborne epoxy resin, 1-3 parts of modified graphene, 10-30 parts of curing agent, 20-30 parts of filler, 1-2 parts of leveling agent, 0.5-1 parts of defoaming agent, 0.5-1 parts of dispersant; The modified graphene is surfactant-modified fluorine-doped graphene or surfactant-modified nickel oxide@fluorine-doped graphene; The preparation method of the surfactant-modified nickel oxide @ fluorine-doped graphene is calculated by weight: 0.5-1 parts of soluble nickel salt, 1-3 parts of fluorine-doped graphene, and 200-500 parts of water were stirred and mixed, and then subjected to a hydrothermal reaction at 160-200°C. After the reaction, the insoluble matter was collected and calcined at 200-350°C to obtain nickel oxide @ fluorine-doped graphene; 1-3 parts of nickel oxide @ fluorine-doped graphene, 0.2-0.5 parts of a surfactant, and 100-300 parts of water were stirred and mixed for 1-3 hours, and the insoluble matter was collected to obtain surfactant-modified nickel oxide @ fluorine-doped graphene; The preparation method of the surfactant-modified fluorine-doped graphene is calculated by weight as follows: 1-3 parts of fluorine-doped graphene, 0.2-0.5 parts of a surfactant, and 100-300 parts of water were stirred and mixed for 1-3 hours, and the insoluble matter was collected to obtain surfactant-modified fluorine-doped graphene; The surfactant is dodecylamine polyoxyethylene ether diquaternary ammonium salt.

2. The modified graphene water-based anti-corrosion coating according to claim 1, characterized in that The preparation method of the fluorine-doped graphene is: The graphene is placed in an atmosphere of fluorine gas and protective gas and calcined at 300-500° C. for 1-3 hours to obtain fluorine-doped graphene.

3. The modified graphene water-based anti-corrosion coating according to claim 1, characterized in that The filler is at least one of 325-2000 mesh titanium dioxide, zinc oxide, and barium sulfate.

4. The modified graphene water-based anti-corrosion coating according to claim 1, characterized in that The leveling agent is a modified polyether siloxane leveling agent.

5. The modified graphene water-based anti-corrosion coating according to claim 1, characterized in that, The defoaming agent is an organosilicon defoaming agent.

6. The modified graphene water-based anti-corrosion coating according to claim 1, characterized in that: The dispersant is at least one of alkylhydroxyl ammonium salts of acidic group-containing copolymers, sodium salts of polycarboxylates, potassium polyacrylates, and sodium polyacrylates.

7. A method for preparing a modified graphene water-based anti-corrosion coating according to any one of claims 1 to 6, characterized in that: include, The water-based epoxy resin and modified graphene are stirred and mixed, and then a curing agent, a filler, a leveling agent, a defoaming agent, and a dispersant are added and continued to be stirred and mixed to obtain a modified graphene water-based anti-corrosion coating.

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