Multifunctional graphene ternary composite material, preparation method and application of multifunctional graphene ternary composite material in zinc-rich coating

Abstract

The preparation method comprises the following steps: preparing a molybdenum disulfide / reduced graphene oxide composite material by adopting an in-situ hydrothermal method, modifying the molybdenum disulfide / reduced graphene oxide composite material by using a silane coupling agent with an epoxy group, and preparing the multifunctional graphene ternary composite material. And finally mixing the active factor sodium hydroxyethylidene-1, 1-diphosphonate with the graphene to obtain the multifunctional graphene ternary composite material. The graphene ternary composite material is used as a zinc-rich coating additive, the coating is cured and formed on the surface of a base material, and the obtained coating has excellent corrosion resistance.

Description

Technical Field

[0001] The invention belongs to the fields of new materials, surface interface engineering, metal corrosion and protection technology, and particularly relates to a method for preparing a multifunctional graphene ternary composite material and application thereof in a zinc-rich coating. Background Art

[0002] Epoxy zinc-rich coating has become an important choice for marine corrosion protection due to its excellent anti-corrosion performance, good mechanical strength and excellent adhesion. In addition, by introducing new technologies such as shielding agents and nanomaterials, the anti-corrosion performance of the coating can be further improved, the service life of the metal structure can be extended, the maintenance cost can be reduced, and reliable protection can be provided for marine engineering. Two-dimensional nanomaterials have unique two-dimensional structures and excellent physical and chemical properties, which can significantly improve the corrosion resistance and mechanical properties of zinc-rich coatings. Specifically, two-dimensional nanomaterials such as graphene [Han X, Sun W, Wang L, Xu K, Yang Z, Ma Y, et al. Unfolded graphene riveted on layered double hydroxide as a highly efficient enhancer for the corrosion protective performance of zinc-rich epoxy coatings. Progress in Organic Coatings. 2024; 191] have high specific surface area and excellent conductivity, which can effectively prevent the penetration of corrosive media and improve the density and corrosion resistance of the coating. At the same time, according to literature reports [Han X, Guo R, Niu B, Yan H. Enhanced corrosion resistance of epoxy resin coating via addition of CeO2 and benzotriazole. Chinese Journal of Chemical Engineering. 2024; 67: 89-96.], adding some nanomaterials with redox properties can also increase the anti-corrosion performance of zinc-rich coatings. However, these approaches still cannot solve the problem of "dead zinc" produced by the corrosion reaction of zinc-rich coatings, which greatly affects the period of its sacrificial anode protecting the cathode. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing a multifunctional graphene ternary composite material and its application in a zinc-rich coating.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] In the first aspect, the present invention provides a method for preparing a multifunctional graphene ternary composite material, comprising the following steps:

[0006] The first step is to add sodium molybdate dihydrate and thiourea to the graphene oxide dispersion, perform ultrasonication until the mixture is uniform, perform hydrothermal reaction, perform centrifugal washing, react the obtained reactant material with a silane coupling agent having an epoxy group for a period of time, perform centrifugal washing, and obtain a molybdenum disulfide / reduced graphene oxide composite material;

[0007] In the second step, the active factor sodium hydroxyethylidene diphosphonate is added to the molybdenum disulfide / reduced graphene oxide composite material, stirred evenly, and freeze-dried to obtain the sodium hydroxyethylidene diphosphonate / molybdenum disulfide / reduced graphene oxide composite material, that is, the multifunctional graphene ternary composite material.

[0008] Preferably, the molar ratio of thiourea to sodium molybdate dihydrate is (1-6):1.

[0009] Preferably, the mass ratio of sodium molybdate dihydrate to graphene oxide is (4-8):1.

[0010] Preferably, the hydrothermal reaction temperature is 180°C and the reaction time is 24h.

[0011] Preferably, the silane coupling agent with epoxy group is any one of KH-560, WD-62 and KH-791.

[0012] Preferably, the mass ratio of the active factor sodium hydroxyethylidene diphosphonate and graphene oxide is 1:1.

[0013] In a second aspect, the present invention provides a multifunctional graphene ternary composite material prepared by the method described in the first aspect.

[0014] In a third aspect, the present invention provides a zinc-rich coating, which at least includes an additive, an epoxy resin, zinc powder, and a curing agent, wherein the additive is a multifunctional graphene ternary composite material prepared by the method described in the first aspect.

[0015] Preferably, the zinc powder is spherical zinc powder particles with a particle size of 5-10 μm, and the solid content of the zinc powder in the zinc-rich coating is 40% to 80%.

[0016] Preferably, the solid content of the additive in the zinc-rich coating is 0.5% to 5%.

[0017] In a fourth aspect, the present invention provides a zinc-rich coating, which is formed by coating the zinc-rich coating described in the third aspect on a substrate.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] The present invention uses an in-situ hydrothermal synthesis method and a silane coupling agent to modify the surface of the composite material, so that the molybdenum disulfide / reduced graphene oxide composite material is grafted with oxygen-containing functional groups, which is easy to disperse in the resin system and can anchor active factors. The flaky molybdenum disulfide is evenly loaded on the surface of the graphene, which inhibits the agglomeration of the molybdenum disulfide nanosheets and forms a typical "graphene-molybdenum disulfide-graphene" sandwich structure. This multi-layer stacking has an excellent physical shielding effect. At the same time, the high conductivity of the graphene can connect the conductive path and enhance the cathode protection effect of the zinc powder. At the same time, due to the successful grafting of the silane coupling agent, the agglomeration phenomenon of the composite material in the resin matrix is ​​reduced, and the interface compatibility of the nanomaterial and the epoxy resin is enhanced. In addition, the synergistic effect of the active factor sodium hydroxyethylidene diphosphonate can improve the activity of zinc in the coating, increase the utilization rate of zinc, and enhance the cathodic protection process of zinc. At the same time, its reaction products with iron further repair coating defects, have a self-repairing effect, effectively protect the metal substrate, and slow down the corrosion rate of the metal substrate. The prepared multifunctional graphene ternary composite material modified zinc-rich coating has excellent corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a process flow chart for the preparation of multifunctional graphene ternary composite materials.

[0021] Figure 2 This is a transmission electron microscope image of the multifunctional graphene ternary composite material in Example 1.

[0022] Figure 3 This is a comparison chart of the low-frequency impedance values ​​of the composite coatings of Examples 1 to 5 of the present invention and Comparative Examples 1 to 6 after immersion for 30 days. DETAILED DESCRIPTION

[0023] The present application is further described below in conjunction with specific embodiments.

[0024] It should be noted that the terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for the convenience of description and are not used to limit the scope of implementation. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of this application without substantially changing the technical content.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0026] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0027] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement or value. The degree of flexibility for a particular variable can be easily determined by one skilled in the art.

[0028] As used herein, the term "at least one of" is intended to be synonymous with "one or more of." For example, "at least one of A, B, and C" expressly includes only A, only B, only C, and combinations of each thereof.

[0029] Concentration, amount and other numerical data can be presented in range format herein.It should be understood that such range format is only used for convenience and simplicity, and should be flexibly interpreted as not only including the numerical value clearly described as range limit, but also including all single numerical values ​​or sub-ranges contained in the range, just as each numerical value and sub-range are clearly described.For example, the numerical range of about 1 to about 4.5 should be interpreted as not only including the limit value of 1 to about 4.5 clearly described, but also including single numerals (such as 2,3,4) and sub-ranges (such as 1 to 3,2 to 4, etc.).The same principle is applicable to the scope of only narrating a numerical value, such as "less than about 4.5", which should be interpreted as including all the above-mentioned values ​​and ranges.In addition, no matter how the breadth of the described range or feature is, this explanation should be applicable.

[0030] The present invention adopts an in-situ hydrothermal method, uses a silane coupling agent to modify a molybdenum disulfide / reduced graphene oxide composite material, and finally prepares a multifunctional graphene ternary composite material by reacting with an active factor. The composite material is added to a coating including an epoxy resin, zinc powder, a curing agent and an organic solvent to obtain a mixed solution, and the mixed solution is coated on the surface of a substrate, cured and formed to obtain a modified epoxy zinc-rich coating. The flaky molybdenum disulfide is uniformly loaded on the surface of the graphene, suppresses the agglomeration of the molybdenum disulfide nanosheets, and forms a typical "graphene-molybdenum disulfide-graphene" sandwich structure. This multilayer stacking has an excellent physical shielding effect, and the good electrical conductivity of the reduced graphene oxide can significantly improve the conductive path between the zinc particles and enhance the cathodic protection of the zinc powder. At the same time, due to the successful grafting of the silane coupling agent, the agglomeration phenomenon of the composite material in the resin matrix is ​​reduced, and the interface compatibility of the nanomaterial and the epoxy resin is enhanced. In addition, the synergistic effect of active factors can improve the activity of zinc, increase the utilization rate of zinc, and enhance the cathodic protection process of zinc. At the same time, under the synergistic effect of active factors, the competitive reaction between active factors and corrosive media and zinc ions can significantly improve the activity of zinc. In addition, active factors can form stable protective compounds with iron ions in the metal substrate, which further increases the physical shielding effect of the zinc-rich coating. Insoluble zinc / iron corrosion products block the pores of the coating and play a self-repairing role, thereby effectively prolonging the anti-corrosion process of the epoxy zinc-rich coating.

[0031] Electrochemical performance test: The electrochemical test was carried out using the three-electrode system of the Donghua electrochemical workstation, with the coating sample as the working electrode and the test area of ​​1cm 2 , Ag / AgCl (0.197 V vs. SHE) was used as the reference electrode and platinum was used as the counter electrode. After reaching a stable open circuit potential, the frequency range of 10 5 ~10 -2 Hz EIS test. The polarization curve between -250mV and +250mV and OCP was measured, and the potential scanning rate was 0.6mV / s.

[0032] Figure 1 The preparation process of the multifunctional graphene ternary composite material of the present invention is given.

[0033] Embodiment 1:

[0034] (1) First, graphene oxide was used as the raw material to prepare 20 mL of 10 mg / mL graphene oxide aqueous dispersion. 0.7258 g Na2MoO4·2H2O and 1.1418 g CH4N2S were dissolved in 50 ml of deionized water by a magnetic stirrer. Then, they were added to the above graphene oxide dispersion, stirred for 1 hour, and evenly dispersed and transferred to a reactor, reacted at 180°C for 24 hours, cooled naturally, centrifuged and washed, and dispersed in deionized water. 80 mL of anhydrous ethanol was added to the above 80 mL, 2.5 mg / mL dispersion, and ultrasonically dispersed for 1 hour. 0.2 g KH560 was taken and added dropwise to the above mixture, stirred at room temperature for 30 minutes, and the mixture was transferred to a three-necked flask, and placed in a water bath at 80°C for 2 hours. After cooling to room temperature, it was centrifuged and washed with deionized water to obtain a molybdenum disulfide / reduced graphene oxide composite material.

[0035] (2) 0.2 g of the active factor sodium hydroxyethylidene diphosphonate was added to the above molybdenum disulfide / reduced graphene oxide composite material, stirred evenly, and freeze-dried to obtain a multifunctional graphene ternary composite material, the transmission electron microscopy image of which is as follows: Figure 1 As shown, flaky molybdenum disulfide is uniformly loaded on the surface of graphene, which inhibits the agglomeration of molybdenum disulfide nanosheets and forms a typical "graphene-molybdenum disulfide-graphene" sandwich structure, with the active factor sodium hydroxyethylidene diphosphonate on its surface.

[0036] (3) Taking the solid content of the coating as 100wt%, the multifunctional graphene ternary composite material (additive) accounts for 0.5wt%, the spherical zinc powder accounts for 60wt%, the epoxy resin E51 accounts for 19.75wt% and the polyamide 650 curing agent 650 accounts for 19.75wt%. The specific process is: take 0.025g of the multifunctional graphene ternary composite material in (2) and dissolve it in 1g of xylene solution, and stir it ultrasonically for 1h. Then, add 1g of epoxy resin E51 and 3.0g of zinc powder, stir for 2h, add 1g of curing agent and stir for 10min, and set aside. Pre-treat the tinplate substrate with a size of 10×20mm, use a roughness of 600 mesh, grind the substrate to remove the oxide layer, put the polished substrate into anhydrous ethanol and ultrasonically remove the surface oil and impurities, and after drying, apply the above coating on the surface of the substrate, and the coating thickness is controlled to be 50μm (±10μm). The curing process is: curing at 70℃ for 6h.

[0037] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0038] Embodiment 2:

[0039] The other processes are the same as those of Example 1, except that in step (3), the multifunctional graphene ternary composite material is changed to 0.15 g, that is, the solid content of the additive is 3 wt %.

[0040] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0041] Embodiment three:

[0042] The other processes are the same as those of Example 1, except that in step (3), the multifunctional graphene ternary composite material is changed to 0.25 g, that is, the solid content of the additive is 5 wt %.

[0043] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0044] Embodiment 4:

[0045] The other processes are the same as those of Example 2, except that in step (3), the spherical zinc powder is changed to 2 g, that is, the solid content of the zinc powder is 40 wt%.

[0046] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0047] Embodiment five:

[0048] The other processes are the same as those of Example 2, except that in step (3), the spherical zinc powder is changed to 4 g, that is, the solid content of the zinc powder is 80 wt%.

[0049] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0050] Comparative Example 1:

[0051] As a comparison, a coating without the multifunctional graphene ternary composite material additive was prepared. The process for preparing the coating was the same as step (3) of Example 1, except that the multifunctional graphene ternary composite material was changed to 0 g.

[0052] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0053] Comparative Example 2:

[0054] For comparison, a coating was prepared using a molybdenum disulfide / reduced graphene oxide composite material as an additive. The process for preparing the coating was the same as step (3) of Example 2, except that the multifunctional graphene ternary composite material was replaced with the molybdenum disulfide / reduced graphene oxide composite material prepared in step (1).

[0055] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0056] Comparative Example 3:

[0057] For comparison, a coating was prepared using sodium hydroxyethylidene diphosphonate as an active factor as an additive. The process for preparing the coating was the same as step (3) of Example 2, except that the multifunctional graphene ternary composite material was replaced with sodium hydroxyethylidene diphosphonate as the active factor.

[0058] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0059] Comparative Example 4:

[0060] 0.7258 g Na2MoO4·2H2O and 1.1418 g CH4N2S were dissolved in 70 ml of deionized water by a magnetic stirrer and transferred to a reactor. The mixture was reacted at 180° C. for 24 h. After natural cooling, the mixture was centrifuged and washed, and freeze-dried to obtain molybdenum disulfide.

[0061] For comparison, a coating was prepared using molybdenum disulfide as an additive. The process for preparing the coating was the same as step (3) of Example 2, except that the multifunctional graphene ternary composite material was replaced with molybdenum disulfide.

[0062] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0063] Comparative Example 5:

[0064] 70 mL, 10 mg / mL graphene oxide was stirred evenly and transferred to a reactor, reacted at 180° C. for 24 h, naturally cooled, centrifuged and washed, and freeze-dried to obtain reduced graphene oxide.

[0065] For comparison, a coating with reduced graphene oxide as an additive was prepared. The process for preparing the coating was the same as step (3) of Example 2, except that the multifunctional graphene ternary composite material was replaced with reduced graphene oxide.

[0066] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0067] Comparative Example 6:

[0068] (1) First, add 20 mL of anhydrous ethanol to 20 mL of 10 mg / mL graphene oxide dispersion and disperse it by ultrasonic for 1 h. Take 0.2 g of KH560 and add it dropwise to the above mixture, stir it at room temperature for 30 min, transfer the mixture to a three-necked flask, place it in a water bath at 80 ° C for 2 h, centrifuge and wash it with deionized water after cooling to room temperature. Dissolve it with 0.7258 g of Na2MoO4·2H2O and 1.1418 g of CH4N2S in 70 ml of deionized water by a magnetic stirrer, stir for 1 h, disperse it evenly and transfer it to a reactor, react at 180 ° C for 24 h, cool it naturally, and then centrifuge and wash it to obtain a molybdenum disulfide / reduced graphene oxide composite material, named molybdenum disulfide / reduced graphene oxide composite material-0.

[0069] Step (2) and step (3) are the same as those in Example 2, except that the molybdenum disulfide / reduced graphene oxide composite material in Example 2 is replaced with molybdenum disulfide / reduced graphene oxide composite material-0.

[0070] The low-frequency impedance modulus of the electrochemical impedance spectrum of the coating after immersion for 30 days is shown in Figure 3 The test results are given in Table 1.

[0071] Table 1 Bode (frequency-mode value) data of Examples 1 to 5 and Comparative Examples 1 to 6 soaked for 30 days

[0072]

[0073]

[0074] The above content only includes some implementation cases of the present invention, and does not limit the present invention in any form. Although the present invention has a better implementation case disclosed as above, it is not used to limit the present invention. Any technician familiar with this profession can use the above structure and technical content to modify or optimize it into an equivalent implementation case without departing from the scope of the technical solution of the present invention. However, any modification, equivalent change or modification made to the above implementation case based on the technical essence of the present invention without departing from the content of the technical solution of the present invention belongs to the scope of the technical solution of the present invention.

Claims

1. A method for preparing a multifunctional graphene ternary composite material, characterized in that: The following steps are involved: The first step is to add sodium molybdate dihydrate and thiourea to the graphene oxide dispersion, perform ultrasonication until the mixture is uniform, perform hydrothermal reaction, perform centrifugal washing, react the obtained reactant material with a silane coupling agent having an epoxy group for a period of time, perform centrifugal washing, and obtain a molybdenum disulfide / reduced graphene oxide composite material; In the second step, the active factor sodium hydroxyethylidene diphosphonate is added to the molybdenum disulfide / reduced graphene oxide composite material, stirred evenly, and freeze-dried to obtain the sodium hydroxyethylidene diphosphonate / molybdenum disulfide / reduced graphene oxide composite material, that is, the multifunctional graphene ternary composite material.

2. The method according to claim 1, characterized in that The molar ratio of thiourea to sodium molybdate dihydrate is (1-6):

1.

3. The method according to claim 1, characterized in that The mass ratio of sodium molybdate dihydrate to graphene oxide is (4-8):

1.

4. The method according to claim 1, characterized in that The hydrothermal reaction temperature was 180°C and the reaction time was 24 h.

5. The method according to claim 1, characterized in that The silane coupling agent having an epoxy group is any one of KH-560, WD-62 and KH-791.

6. The method according to claim 1, characterized in that The mass ratio of active factor sodium hydroxyethylidene diphosphonate and graphene oxide is 1:

1.

7. A multifunctional graphene ternary composite material prepared by the method according to any one of claims 1 to 6.

8. A zinc-rich coating, comprising at least an additive, an epoxy resin, zinc powder, and a curing agent, characterized in that: The additive is a multifunctional graphene ternary composite material prepared by the method described in any one of claims 1-6.

9. The zinc-rich coating according to claim 8, characterized in that: The zinc powder is spherical zinc powder particles with a particle size of 5-10 μm. The solid content of the zinc powder in the zinc-rich paint is 40% to 80%; the solid content of the additive in the zinc-rich paint is 0.5% to 5%.

10. A zinc-rich coating, characterized in that: The zinc-rich coating is formed by coating the zinc-rich coating as claimed in claim 8 or 9 on a substrate.

Images