An anticorrosive coating containing graphene components and a preparation method thereof

Abstract

The present invention discloses an anticorrosive coating containing graphene components and a preparation method thereof. The anticorrosive coating comprises, by weight parts, 80-120 parts of waterborne epoxy resin, 1-3 parts of modified graphene, 10-30 parts of curing agent, 20-30 parts of pigment filler, 1-2 parts of leveling agent, 0.5-1 part of defoaming agent, and 0.5-1 part of dispersant; the modified graphene is polydopamine / cobalt ferrite@ graphene or cobalt ferrite@ graphene. The present invention uses polydopamine / cobalt ferrite@ graphene or cobalt ferrite@ graphene to reduce the problem that graphene is prone to agglomeration in the coating system. The coating formed by the anticorrosive coating adheres more firmly, the water permeability is reduced, and the corrosion of the coated metal is prevented. In addition, the coating formed by the anticorrosive material of the present invention has a flat, bright appearance without obvious defects such as pinholes, air bubbles, inclusions, peeling, cracks, etc. that cause the physical shielding effect of the coating to fail, and the service life of the coating can be extended.

Description

Technical Field

[0001] The present invention relates to the technical field of anticorrosive coatings, and particularly relates to an anticorrosive coating containing graphene components and a preparation method thereof. Background Art

[0002] Metal corrosion is the entire process in which a metal reacts chemically and electrochemically with the medium in the environment, resulting in oxidation and the formation of metal compounds. For metal materials that pervade all aspects of modern life, corrosion often means accelerated failure and damage, ultimately leading to the damage of parts or facilities and even causing accidents. Therefore, metal corrosion not only causes a large waste of resources, but may also lead to significant economic losses, and at the same time brings great potential safety hazards to production and life. As a simple, convenient and efficient surface treatment measure, anticorrosive coatings have been widely used in the corrosion protection of metals. Currently, the more commonly used anticorrosive coatings mainly include epoxy coatings, polyurethane coatings, fluororesin coatings, silicone coatings, and inorganic zinc-rich anticorrosive coatings, etc.

[0003] Graphene itself has excellent electrical, mechanical and thermal properties, and its own sheet structure has super shielding properties, which can block corrosive media from entering the coating. Applying it to anticorrosive coatings can not only improve the properties of the coating, such as flexibility, hardness, impact resistance, etc., but also enhance its corrosion resistance. Some technologies of graphene anticorrosive coatings have achieved good results. For example, CN114921145A discloses a modified graphene anticorrosive coating, including 30 - 38 parts of waterborne polyurethane resin, 25 - 32 parts of acrylate emulsion, 15 - 23 parts of graphene oxide / ZnO / SiO2 composite material, 1 - 3 parts of polydopamine, 0.01 - 1.2 parts of penetrant, 0.01 - 1 part of emulsifier, 0 - 0.05 parts of defoamer, 0 - 10 parts of film-forming aid, and 0 - 1 part of other additives. This coating improves the dispersibility and compatibility of graphene with the substrate, and improves the anticorrosion performance of graphene added to the coating. However, the content of graphene in the formula is relatively high, and the cost of the coating is relatively high. CN110358407A discloses an environmentally friendly solvent-free graphene anticorrosive coating, including 30 - 40 parts of epoxy resin, 15 - 20 parts of reactive diluent, 0.15 - 0.2 parts of graphene, 5 - 10 parts of additives, 20 - 25 parts of iron oxide red, 10 - 15 parts of mica powder, 0.4 - 0.8 parts of fumed silica, 4 - 6 parts of barite, 6 - 10 parts of tripolyphosphate, 0.5 - 1.5 parts of silane coupling agent, and 7 - 15 parts of phenolic amine epoxy resin curing agent. Although this coating does not use organic solvents, the graphene is not modified, and the stability of the coating may not be good.

[0004] Therefore, there is still room for improvement in the improvement of the anticorrosive performance of coatings by graphene. Summary of the Invention

[0005] In order to solve the technical problems existing in the prior art, the present invention provides an anti-corrosion coating containing graphene components, which includes, by mass parts,

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

[0007] The modified graphene is polydopamine / cobalt ferrite@ graphene or cobalt ferrite@ graphene.

[0008] As a nanomaterial with excellent comprehensive properties, graphene has great potential in the preparation of functional coatings with anti-corrosion, conductivity, flame retardancy and self-healing properties, etc., and is an ideal coating modifier. However, due to its poor dispersibility and stability in the coating system, it is difficult to exert its maximum efficacy. At present, graphene is generally modified to reduce its surface energy and improve its dispersion ability. The modification methods of graphene mainly include element doping modification, organic matter modification, metal and inorganic nanoparticle modification, etc. The preparation method of cobalt ferrite is simple, and modifying it on the surface of graphene can improve the surface properties of graphene. However, there is little research on cobalt ferrite@ graphene in corrosion coatings, and it is necessary to study its properties.

[0009] The small molecule polymer polydopamine can be formed by the polymerization of dopamine in an alkaline environment, and it has a large number of reactive groups on its surface. Forming polydopamine in situ and wrapping it on the surface of cobalt ferrite@ graphene may further improve the anti-corrosion performance.

[0010] Furthermore, the preparation method of the polydopamine / cobalt ferrite@ graphene includes, by mass parts,

[0011] Disperse 2 to 5 parts of cobalt ferrite@ graphene in 50 to 100 parts of water, adjust to the first pH, add 0.5 to 1 part of hydrochloric acid dopamine and stir for 1 to 2 h, then add 0.2 to 0.5 part of silane coupling agent and heat up, continue to stir and react for 6 to 8 h to obtain polydopamine / cobalt ferrite@ graphene.

[0012] Furthermore, the silane coupling agent is at least one of KH550, KH560, KH570, KH580.

[0013] Furthermore, the first pH is 8.0 to 9.0;

[0014] Heat up to a temperature of 60 to 75 °C.

[0015] Furthermore, the preparation method of the cobalt ferrite@ graphene includes, by mass parts,

[0016] Disperse 0.2 - 0.5 parts of graphene, 2 - 5 g of soluble cobalt salt, and 0.1 - 0.3 parts of surfactant in 50 - 100 parts of water and adjust to the second pH, then carry out hydrothermal reaction. After completion, collect the insoluble matter and calcine it in an atmosphere of protective gas to obtain cobalt ferrite @ graphene.

[0017] In some embodiments of the present invention, the soluble cobalt salt can be at least one of cobalt nitrate hexahydrate, cobalt acetate tetrahydrate, and cobalt chloride hexahydrate.

[0018] Further, the second pH is 11.0 - 13.0;

[0019] The surfactant is at least one of sodium dodecyl sulfate, polyvinylpyrrolidone, and cetyltrimethylammonium bromide.

[0020] Further, the hydrothermal reaction is maintained at 160 - 200 °C for 6 - 32 h.

[0021] Further, the calcination is maintained at 300 - 400 °C for 1 - 3 h.

[0022] In some embodiments of the present invention, the leveling agent can be a modified polyether silicone type leveling agent;

[0023] The defoaming agent can be an organosilicon defoaming agent;

[0024] The dispersant can be at least one of sodium polycarboxylate, potassium polyacrylate, and sodium polyacrylate.

[0025] Further, the pigment and filler is at least one of titanium dioxide, zinc oxide, iron oxide red, talc powder, and barium sulfate with a particle size of 300 - 1250 mesh.

[0026] The present invention also provides a preparation method of the above anti - corrosion coating containing graphene components, including,

[0027] Add the modified graphene to the curing agent to obtain a mixture;

[0028] Mix the mixture, water - borne epoxy resin, pigment and filler, leveling agent, defoaming agent, and dispersant to obtain an anti - corrosion coating containing graphene components.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention uses polydopamine / cobalt ferrite@ graphene or cobalt ferrite@ graphene to reduce the problem that graphene is prone to agglomeration in the coating system. The coating formed by the anti-corrosion coating adheres more firmly, the water permeability is reduced, and the corrosion of the coated metal is prevented. In addition, the coating formed by the anti-corrosion material of the present invention has a flat, bright appearance without obvious defects such as pinholes, air bubbles, inclusions, peeling, cracks, etc. that cause the failure of the physical shielding effect of the coating, and the service life of the coating can be extended. Detailed implementation manners

[0031] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values and individual point values of each range, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0032] The following will describe the technical solutions in the embodiments of the present invention clearly and completely in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Introduction to some raw materials used in the embodiments of the present invention:

[0034] Waterborne epoxy resin, model BC5550, purchased from Guangzhou Liangu Chemical;

[0035] Graphene, product number HGP-10, purchased from Qingdao Yanhai Carbon Materials Co., Ltd.;

[0036] Curing agent, model BC901, purchased from Banghe Chemical;

[0037] Modified polyether silicone type leveling agent, model BYK-333, purchased from BYK of Germany;

[0038] Organosilicon defoamer, model BYK-A530, purchased from BYK of Germany;

[0039] Iron oxide red, particle size 325 mesh, purchased from Hebei Jiyan Mineral Products Co., Ltd.;

[0040] Titanium dioxide, particle size 1000 mesh, purchased from Langfang Chuangge Chemical Products Co., Ltd.;

[0041] Sodium polyacrylate, product number 00084, purchased from Hubei Jiufenglong Chemical Co., Ltd.;

[0042] Polyvinylpyrrolidone, model k17, purchased from Jinan Rongzheng Chemical Co., Ltd.;

[0043] Graphene, model MSTN-PGO, Beijing Meiston Technology Development Co., Ltd.

[0044] Other raw materials not mentioned are common raw materials in this field.

[0045] Example 1

[0046] A method for preparing an anti-corrosion coating containing a graphene component, the steps are as follows:

[0047] Step 1: Weigh 1 kg of waterborne epoxy resin, 0.02 kg of cobalt tetroxide@graphene, 0.2 kg of curing agent, 0.1 kg of iron oxide red, 0.1 kg of titanium dioxide, 0.01 kg of modified polyether siloxane leveling agent, 0.005 kg of silicone defoamer, 0.005 kg of sodium polyacrylate;

[0048] Step 2: Add cobalt tetroxide@graphene to the curing agent to obtain a mixture;

[0049] Step 3: Mix the mixture, waterborne epoxy resin, iron oxide red, titanium dioxide, modified polyether siloxane leveling agent, silicone defoamer, and sodium polyacrylate at 100 rpm to obtain an anti-corrosion coating containing a graphene component.

[0050] Among them, the preparation method of cobalt tetroxide@graphene is as follows

[0051] Disperse 0.2 g of graphene, 3.5 g of cobalt nitrate hexahydrate, 0.1 g of polyvinylpyrrolidone, and 0.1 g of sodium dodecyl sulfate in 100 g of water by stirring at 300 rpm for 30 min. Then add sodium hydroxide to adjust the pH to 12.0. Then carry out hydrothermal treatment at 180 °C for 18 h. After completion, filter, wash, and dry, collect the insoluble matter, and then calcine in a nitrogen atmosphere at 350 °C for 2 h to obtain cobalt tetroxide@graphene.

[0052] Example 2

[0053] A method for preparing an anti-corrosion coating containing a graphene component, the steps are as follows:

[0054] Step 1: Weigh 1 kg of waterborne epoxy resin, 0.02 kg of polydopamine / cobalt tetroxide@graphene, 0.2 kg of curing agent, 0.1 kg of iron oxide red, 0.1 kg of titanium dioxide, 0.01 kg of modified polyether siloxane leveling agent, 0.005 kg of silicone defoamer, 0.005 kg of sodium polyacrylate;

[0055] Step 2: Add polydopamine / cobalt tetroxide@graphene to the curing agent to obtain a mixture;

[0056] Step 3: Mix the mixture, waterborne epoxy resin, iron oxide red, titanium dioxide, modified polyether silicone leveling agent, silicone defoamer, and sodium polyacrylate by stirring at 100 rpm to obtain an anti-corrosion coating containing graphene components.

[0057] Among them, the preparation method of polydopamine / cobalt ferrite@ graphene is as follows:

[0058] Disperse 3 g of cobalt ferrite@ graphene in 80 g of water by stirring at 500 rpm for 30 min, then add ammonia water to adjust the pH to 8.5, add 0.5 g of dopamine hydrochloride and stir for 1.5 h, then add 0.3 g of KH550 and heat to 70 °C, continue to stir and react for 6 h, filter, wash, and dry to obtain polydopamine / cobalt ferrite@ graphene.

[0059] The preparation method of cobalt ferrite@ graphene is the same as that in Example 1.

[0060] Examples 3 to 4

[0061] It is basically the same as Example 2, and the only difference is that in Step 1, 0.01 kg and 0.03 kg of polydopamine / cobalt ferrite@ graphene are weighed respectively.

[0062] Comparative Example 1

[0063] A preparation method of an anti-corrosion coating containing graphene components is as follows:

[0064] Step 1: Weigh 1 kg of waterborne epoxy resin, 0.02 kg of graphene, 0.2 kg of curing agent, 0.1 kg of iron oxide red, 0.1 kg of titanium dioxide, 0.01 kg of modified polyether silicone leveling agent, 0.005 kg of silicone defoamer, and 0.005 kg of sodium polyacrylate;

[0065] Step 2: Add graphene to the curing agent to obtain a mixture;

[0066] Step 3: Mix the mixture, waterborne epoxy resin, iron oxide red, titanium dioxide, modified polyether silicone leveling agent, silicone defoamer, and sodium polyacrylate by stirring at 100 rpm to obtain an anti-corrosion coating containing graphene components.

[0067] Comparative Example 2

[0068] An anti-corrosion coating is as follows:

[0069] Step 1: Weigh 1 kg of waterborne epoxy resin, 0.2 kg of curing agent, 0.1 kg of iron oxide red, 0.1 kg of titanium dioxide, 0.01 kg of modified polyether silicone leveling agent, 0.005 kg of silicone defoamer, and 0.005 kg of sodium polyacrylate;

[0070] Step 2: Stir and mix waterborne epoxy resin, curing agent, iron oxide red, titanium dioxide, modified polyether silicone leveling agent, silicone defoamer, and sodium polyacrylate at 100 rpm to obtain an anticorrosive coating containing graphene components.

[0071] Test Example

[0072] The coatings of the above examples and comparative examples were evenly coated on the surface of polished Q235 steel using a spray gun, the coating thickness was controlled to be 100 μm, and then completely cured at room temperature. A series of properties of the coatings were tested:

[0073] The adhesion of the coating comes from the adhesion force between the coating and the metal substrate and the cohesive force of the coating itself. The basic condition for the coating to function is that the coating can firmly adhere to the metal substrate. Therefore, the coating adhesion is one of the important indicators for evaluating the coating performance. Referring to the national standard GB / T9286-2021 "Cross-Cut Test for Coatings and Varnishes", the coating adhesion was measured and rated. The results are shown in Table 1. The lower the grade number, the higher the adhesion.

[0074] Table 1 Coating Adhesion Results

[0075] Coating Adhesion (Grade) Example 1 1 Example 2 0 Example 3 1 Example 4 1 Comparative Example 1 1 Comparative Example 2 2

[0076] The adhesion of Comparative Example 1 is better than that of Comparative Example 2, which shows that the addition of graphene can fill the pores of the coating, increase the contact area between the coating and the substrate, and improve the coating adhesion. However, the adhesion grades of Example 1 and Comparative Example 1 are both 1, the adhesion grades of Example 3 and Example 4 are also 1, and only the coating adhesion grade of Example 2 is 0. This shows that the poly dopamine / wrapped cobalt ferrite@graphene formed by the encapsulation of cobalt ferrite@graphene by poly dopamine can further increase the contact area between the coating and the substrate, and also benefit from the groups of poly dopamine, thus significantly improving the coating adhesion. Excessive poly dopamine / cobalt ferrite@graphene will form agglomerates in the coating system, resulting in a decrease in adhesion.

[0077] The higher the hardness of the coating, the better its resistance to external forces, and the substrate can be better protected. It is one of the important physical performance indicators of the coating. Referring to the national standard GB / T 6739-2022 "Pencil Method for Determining Film Hardness of Paints and Varnishes", the coating hardness was measured. The results are shown in Table 2.

[0078] Table 2 Coating Hardness Results

[0079]

[0080]

[0081] As can be seen from the results in Table 2, the coating hardness of Example 2 reached a maximum of 4H.

[0082] The corrosion resistance of the samples was measured with reference to the national standard GB / T 1771-2007 "Determination of Resistance of Paints and Varnishes to Neutral Salt Spray". After the test surface of the specimen was cross-scored, the specimen was placed in a salt spray test chamber at an angle of 30° to the vertical direction. The experimental corrosion solution was 7wt.% NaCl solution, the laboratory temperature was 35 ± 2 °C, the pressure barrel temperature was 47 ± 2 °C, the pH value was 6.5 - 7.2, and continuous spraying was carried out for 600 h. The results showed that large-scale coating peeling occurred in Comparative Example 2, indicating that corrosive media such as water and chloride ions in the solution had penetrated into the interface between the coating and the substrate in large amounts, exacerbating the corrosion reaction of the iron substrate. There was a certain improvement in Comparative Example 1 with the addition of graphene, but relatively deep corrosion pits also appeared. A large number of air bubbles were generated in the coatings of Example 1 and Example 4, indicating that these two coatings had basically failed. There were some small air bubbles in the coating of Example 3, while there were basically no air bubbles in the coating of Example 2. These results indicate that the addition of graphene can improve the corrosion resistance of the coating, and the coating with the appropriate proportion of polydopamine / cobalt ferrite@graphene has the best corrosion resistance. This may be because cobalt ferrite is evenly distributed on graphene, which can effectively prevent the agglomeration of cobalt ferrite. At the same time, the loading of cobalt ferrite causes a steric hindrance effect, preventing the stacking and agglomeration of graphene and promoting the dispersion of graphene itself. The inclusion of polydopamine further improves the dispersion performance and binding performance.

[0083] Using an electrochemical workstation, with a saturated calomel electrode as the reference electrode, a platinum electrode as the auxiliary electrode, and the electrode with the coating as the working electrode, the polarization curve was obtained to calculate the corrosion current density. The test area was 0.785 cm 2 , and the test solution was 3.5wt.% NaCl solution. After the specimen was in a stable state under open-circuit voltage test, the open-circuit voltage value was obtained, and then the scanning voltage range was set to open-circuit voltage ± 500 mV, the potential scanning rate was 1 mV / s, and the frequency range was 10 -2 ~10 5 Hz. The corrosion current density results are shown in Table 3.

[0084] Table 3 Corrosion current density results

[0085] <![CDATA[Corrosion current density (μA / cm 2 )]]> Example 1 7.62 Example 2 3.86 Example 3 6.91 Example 4 9.66 Comparative Example 1 23.95 Comparative Example 2 36.14

[0086] As can be seen from the results in Table 3, consistent with the corrosion resistance test results, the coating of Example 2 has the lowest corrosion current density and the best anti-corrosion performance.

[0087] In summary, the present invention uses polydopamine / cobalt ferrite@ graphene or cobalt ferrite@ graphene to reduce the problem of easy agglomeration of graphene in the coating system. The coating formed by the anticorrosive coating adheres more firmly, the water permeability is reduced, and the corrosion of the coated metal is prevented. In addition, the coating formed by the anticorrosive material of the present invention has a flat, bright appearance without obvious defects such as pinholes, air bubbles, inclusions, peeling, cracks, etc. that cause the failure of the physical shielding effect of the coating, and the service life of the coating can be extended.

[0088] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An anti-corrosion coating containing graphene components, characterized in that, Comprising, by weight parts, 80 - 120 parts of waterborne epoxy resin, 1 - 3 parts of modified graphene, 10 - 30 parts of curing agent, 20 - 30 parts of pigment and filler, 1 - 2 parts of leveling agent, 0.5 - 1 part of defoaming agent, 0.5 - 1 part of dispersant; The modified graphene is polydopamine / cobalt ferrite @ graphene; The preparation method of the polydopamine / cobalt ferrite @ graphene comprises, by mass parts, Disperse 2 - 5 parts of cobalt ferrite @ graphene in 50 - 100 parts of water, adjust to the first pH, add 0.5 - 1 part of dopamine hydrochloride and stir for reaction for 1 - 2 h, then add 0.2 - 0.5 part of silane coupling agent and heat up, continue to stir for reaction for 6 - 8 h to obtain polydopamine / cobalt ferrite @ graphene; The preparation method of the cobalt ferrite @ graphene comprises, by mass parts, Disperse 0.2 - 0.5 part of graphene, 2 - 5 g of soluble cobalt salt, 0.1 - 0.3 part of surfactant in 50 - 100 parts of water and adjust to the second pH, then carry out hydrothermal reaction, after completion, collect the insoluble matter and calcine it in an inert gas atmosphere to obtain cobalt ferrite @ graphene.

2. The anti-corrosion coating containing graphene components according to claim 1, wherein The silane coupling agent is at least one of KH550, KH560, KH570, KH580; 3. The anti-corrosion coating containing graphene components according to claim 1, characterized in that, The first pH is 8.0 - 9.0; Heat up to a temperature of 60 - 75 °C.

4. The anti-corrosion coating containing graphene component according to claim 1, characterized in that, The second pH is 11.0 - 13.0; The surfactant is at least one of sodium dodecyl sulfate, polyvinylpyrrolidone, cetyltrimethylammonium bromide; 5. The anti-corrosion coating containing a graphene component according to claim 1, characterized in that, The hydrothermal reaction is maintained at 160 - 200 °C for 6 - 32 h.

6. The anti-corrosion coating containing a graphene component according to claim 1, characterized in that, The calcination is maintained at 300 - 400 °C for 1 - 3 h.

7. The anti-corrosion coating containing graphene components according to claim 1, wherein The pigment and filler is at least one of titanium dioxide, zinc oxide, iron oxide red, talc powder, barium sulfate with a particle size of 300 - 1250 mesh; 8. A method for preparing an anti-corrosion coating containing a graphene component according to any one of claims 1 to 7, characterized in that, Comprising Add the modified graphene into the curing agent to obtain a mixture; Mix the mixture, waterborne epoxy resin, pigment and filler, leveling agent, defoaming agent, dispersant to obtain an anti - corrosion coating containing graphene component.

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