A modified MXene-based composite hydrogen barrier epoxy resin coating, a preparation method and application thereof

Abstract

The application discloses a modified MXene-based composite epoxy resin hydrogen barrier coating, a preparation method and application thereof. The hydrogen barrier epoxy resin coating comprises polydopamine-modified MXene, an epoxy resin and optionally a curing agent. The dispersibility and compatibility of MXene in the epoxy resin matrix are significantly improved by surface functionalization modification of MXene by polydopamine. The coating formed by the coating has excellent hydrogen barrier performance and corrosion resistance, can effectively prolong the hydrogen permeation path and prevent the diffusion of hydrogen atoms to the metal matrix, thereby protecting the pipeline or container from hydrogen damage. The modified MXene-based composite epoxy resin hydrogen barrier coating has simple preparation process, is green and environment-friendly, and is suitable for the protection of the inner wall of a hydrogen storage or transportation container.

Description

Technical Field

[0001] This invention belongs to the field of functional coating materials and hydrogen energy technology, specifically relating to a hydrogen barrier coating based on modified MXene composite epoxy resin, its preparation method, and a container coated with the hydrogen barrier coating and its preparation method. Background Technology

[0002] Against the backdrop of continuously growing global demand for clean energy, hydrogen energy has broad development prospects, but its transportation still faces significant challenges due to hydrogen damage. To improve efficiency and transportation effectiveness, blending hydrogen with natural gas and utilizing existing pipelines has become one feasible solution for large-scale, long-distance hydrogen transportation. This approach can utilize existing facilities to reduce costs, but a key challenge lies in ensuring the compatibility of pipeline materials with hydrogen. Hydrogen damage can lead to material performance degradation, shortened lifespan, and even accidents, severely hindering the development of the hydrogen energy industry.

[0003] Therefore, developing pipeline coatings that are impermeable, corrosion-resistant, and suitable for hydrogen-rich environments is crucial for ensuring the safety and lifespan of hydrogen transportation and promoting the industrialization of hydrogen energy. Summary of the Invention

[0004] After a long period of research, the inventors unexpectedly discovered that hydrogen barrier coatings formed by modified MXene-based composite epoxy resin hydrogen barrier coatings containing the following components have excellent hydrogen barrier properties and corrosion resistance.

[0005] Therefore, based on the above findings, in a first aspect, the present invention provides a hydrogen-barrier coating based on modified MXene, comprising polydopamine-modified MXene, an epoxy resin, and optionally a curing agent.

[0006] In one embodiment, the mass ratio of polydopamine-modified MXene to epoxy resin is 1-10:1000.

[0007] In one embodiment, the mass ratio of epoxy resin to curing agent is 2-5:1.

[0008] In another aspect of the invention, a method for preparing a hydrogen-barrier coating based on modified MXene as described above is provided, comprising: providing polydopamine-modified MXene; and mixing the polydopamine-modified MXene with an epoxy resin and optionally a curing agent.

[0009] In one embodiment, providing polydopamine-modified MXene comprises: mixing MXene, dopamine hydrochloride and 3-hydroxymethylaminomethane in an aqueous solution and reacting them, followed by post-treatment to obtain polydopamine-modified MXene.

[0010] In one embodiment, the mass ratio of dopamine hydrochloride to MXene is 1-2:2; and / or, the mass ratio of dopamine hydrochloride to 3-hydroxymethylaminomethane is 1-1.5:1.

[0011] In one embodiment, the reaction conditions are: a reaction temperature of 50-60°C and a reaction time of 10-15 hours.

[0012] In another aspect of the invention, a hydrogen storage or transport container is provided, the inner wall of which is coated with a hydrogen barrier coating formed by a modified MXene-based composite epoxy resin hydrogen barrier coating as described above.

[0013] In one embodiment, the thickness of the hydrogen barrier coating is 100-120 µm.

[0014] In one implementation, the container is selected from closed containers and pipes.

[0015] In another aspect of the invention, a method for preparing the hydrogen storage or transport container as described above is provided, comprising providing a hydrogen-barrier coating based on a modified MXene composite epoxy resin as described above; applying the coating to the inner wall of the container; and curing the coating to form a hydrogen-barrier coating on the inner wall. Wherein, when coating is required, the coating, which does not contain a curing agent, is mixed with a curing agent, and then the coating is applied.

[0016] In one embodiment, the conditions for curing the coating are: a curing temperature of 50-80°C and a curing time of 12-36 hours.

[0017] Compared with the prior art, the present invention has at least one of the following advantages:

[0018] 1. The hydrogen-blocking coating formed by the modified MXene-based composite epoxy resin hydrogen-blocking coating provided by this invention exhibits significant hydrogen barrier properties. The resulting coating can form a uniformly distributed barrier structure, which on the one hand extends the hydrogen permeation path, and on the other hand, the modification of polydopamine increases the compatibility of MXene in the epoxy resin, improves the coating density, and weakens the diffusion path of hydrogen atoms in the coating.

[0019] 2. In the modified MXene-based composite epoxy resin hydrogen barrier coating provided by the present invention, the epoxy resin-based coating has good adhesion to the substrate to be coated, is not easy to fall off, and has a significantly improved service life.

[0020] 3. In the hydrogen barrier coating formed by the modified MXene-based composite epoxy resin hydrogen barrier coating provided by the present invention, the modified MXene is uniformly dispersed in the epoxy resin, which can better improve the corrosion resistance of the coating formed by the coating. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or related technologies, the accompanying drawings used in describing this invention or related technologies will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without any inventive effort.

[0022] Figure 1 This is a comparison of the Fourier transform infrared spectra of P-MX prepared in this invention and unmodified MXene;

[0023] Figure 2 These are the X-ray diffraction patterns of P-MX and unmodified MXene prepared according to this invention;

[0024] Figure 3 These are scanning electron microscope images of P-MX and unmodified MXene prepared according to the present invention; where (a) is unmodified MXene and (b) is P-MX prepared according to the present invention. Detailed Implementation

[0025] To better illustrate the technical means and effects of the present invention, the present invention is further described below in conjunction with non-limiting embodiments. The embodiments of the present invention (including descriptions mentioned in the embodiments) are intended to describe the embodiments of the present invention and are not intended to limit the scope of any claims. According to the present invention, those skilled in the art will understand that many changes can be made to the specific embodiments disclosed without departing from the spirit and scope of the present invention, and the same or similar results can still be obtained.

[0026] Unless otherwise stated, the terms used in this specification and claims have the following meanings.

[0027] In this paper, the term "MXene" refers to a class of two-dimensional transition metal carbides, nitrides, or carbonitrides, typically having the general formula M n+1 X n T x Where M represents an early transition metal (e.g., Ti, V, Nb), X represents carbon and / or nitrogen, n is typically 1, 2, or 3, and T x These represent surface terminating groups (e.g., -OH, -O, -F, etc.). They have a graphene-like layered structure and are used as functional fillers in this invention.

[0028] In this paper, the term "polydopamine-modified MXene (P-MX)" refers to a functionalized material that alters the surface properties of MXene and improves its compatibility with the polymer matrix by using dopamine or its salts (such as dopamine hydrochloride) as precursors to undergo oxidative self-polymerization reactions on the surface and between layers of MXene to form a polydopamine coating or intercalation layer.

[0029] In this document, the term "epoxy resin" refers to a polymeric prepolymer containing two or more epoxy groups in its molecule. In this invention, aqueous epoxy resin emulsions are preferred, i.e., environmentally friendly epoxy resin systems using water as the dispersion medium.

[0030] In this document, the term "curing agent" refers to a crosslinking agent that can react with active groups such as epoxy groups in epoxy resin to form a three-dimensional network structure, causing the resin to change from a liquid state to a solid state. In specific embodiments of the present invention, a curing agent such as CA-8113, manufactured by BADF and suitable for waterborne epoxy systems, can be used.

[0031] In this article, the term "hydrogen barrier performance" refers to the ability of a coating material to prevent the penetration and diffusion of hydrogen atoms or molecules. It is typically characterized by indicators such as hydrogen permeation current density, hydrogen permeation rate, or hydrogen content. The lower the value, the better the hydrogen barrier performance.

[0032] In this paper, the term "corrosion resistance" refers to the ability of a coating to protect a metal substrate from electrochemical corrosion in corrosive media (such as solutions containing chloride ions). It is typically evaluated using electrochemical testing methods such as electrochemical impedance spectroscopy (EIS) and polarization curves; generally, a larger capacitive arc radius indicates better corrosion resistance.

[0033] In this paper, the term "maze effect" refers to the phenomenon that the uniform, oriented, or random dispersion of MXene nanosheets in the coating forces hydrogen atoms or corrosive media ions to bypass these sheet-like fillers in order to advance, thereby greatly extending their penetration path and acting as a physical barrier.

[0034] The raw materials and instruments used in this invention are described in detail below:

[0035] MXene (HF etching) was purchased from Newene Technology, multi-layer accordion-shaped Ti3C2T x ;

[0036] Dopamine hydrochloride and 3-hydroxymethylaminomethane were purchased from Maclean's reagent.

[0037] The epoxy resin (nonionic modified epoxy resin MT-HY02) and epoxy resin curing agent (curing agent GF-G1 and / or CA-8113 for waterborne epoxy systems) were purchased from BADEFU Group Co., Ltd.

[0038] X-ray diffractometer, model D8 Focus;

[0039] Scanning electron microscope, purchased from Fidacom LLC, USA, model KYKY-EM6200

[0040] Infrared spectrometer, purchased from Bruker, model TENSOR27;

[0041] Electrochemical workstation, purchased from Shanghai Zhenhua Instruments Co., Ltd., model CHI660E;

[0042] The BRUKER G4 PHOENIX DH hydrogen meter was purchased from BRUKER, model G4 PHOENIX.

[0043] This invention mainly includes two core steps: the preparation of modified MXene (P-MX) and the preparation and coating of hydrogen barrier coating based on modified MXene composite epoxy resin.

[0044] 1. Preparation of P-MX

[0045] MXene and dopamine hydrochloride in a mass ratio of 2:1-2 were slowly added to deionized water simultaneously.

[0046] Use an ultrasonic device to sonicate it for 20-40 minutes to form a homogeneous mixture I.

[0047] Add 3-hydroxymethylaminomethane to the above mixture I, wherein the mass ratio of dopamine hydrochloride to 3-hydroxymethylaminomethane is 1-1.5:1, and sonicate again for 20-40 minutes to form a uniformly dispersed mixture II.

[0048] Mixture II is stirred at a constant temperature of 50-60℃ for about 8-15 hours at a stirring speed of 400-700 rpm.

[0049] After the reaction was completed, the stirred mixture II was filtered and washed multiple times with deionized water and ethanol, and finally dried to obtain polydopamine-modified MXene powder, denoted as P-MX.

[0050] 2. Preparation of hydrogen-barrier epoxy resin coatings

[0051] The P-MX prepared above is mixed with epoxy resin at a mass ratio of 1-10:1000. The mixture is first mechanically stirred to achieve initial mixing, and then ultrasonically treated for 5-15 minutes to ensure complete dispersion, resulting in a homogeneous mixture. The epoxy resin can be nonionic modified epoxy resin MT-HY02.

[0052] During coating, a curing agent is added to the above mixture, wherein the mass ratio of epoxy resin to curing agent is 2-5:1, preferably 40:7. The mixture is stirred thoroughly until homogeneous to obtain a hydrogen-barrier epoxy resin coating. The curing agent can be a nonionic epoxy curing agent such as CA-8113 or GF-G1.

[0053] Example

[0054] To further understand the present invention, the hydrogen-barrier epoxy resin coating and the hydrogen-barrier coating formed thereof are described in detail below with reference to embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0055] Example 1

[0056] (1) Take 0.5 g of MXene (purchased from Xinxi Technology, multi-layer accordion-shaped Ti3C2T) x 0.25 g of dopamine hydrochloride was slowly added to 150 ml of deionized water. The mixture was then sonicated in a 120 W sonicator for 30 minutes to form a homogeneous mixture I. 0.182 g of 3-hydroxymethylaminomethane was added to mixture I and sonicated in a 120 W sonicator for 30 minutes to form a homogeneous mixture II. Mixture II was placed in a magnetic stirrer and stirred at 600 rpm for 12 hours at 50°C. Afterward, it was filtered and washed repeatedly with deionized water and ethanol to ensure that residual dopamine hydrochloride was completely removed. The mixture was then dried to obtain P-MX.

[0057] (2) Weigh 0.02 g of P-MX obtained in step (1) and add it to 4 g of waterborne epoxy resin MT-HY02. Stir thoroughly and sonicate in a 120 W ultrasonic device for 10 minutes to ensure that P-MX is evenly dispersed in waterborne epoxy resin MT-HY02. Then add 0.7 g of waterborne epoxy resin curing agent CA-8113 and stir thoroughly until the mixture is uniform to obtain a mixed coating.

[0058] (3) Take an appropriate amount of the mixed coating obtained in step (2) and spread it evenly on the pretreated steel plate. Use a 40 μm wire bar coater to coat the coating evenly, ensuring that the coating thickness is consistent. Place the coated steel plate in an oven and cure it at a constant temperature of 60℃ for 12 hours to ensure that the coating is completely cured. Take out the cured coating and use a thickness gauge to accurately measure the coating thickness, which is 105 µm.

[0059] Example 2

[0060] The hydrogen barrier coating of Example 2 was prepared using the same method as in Example 1, except that the mass ratio of modified MXene to epoxy resin was adjusted to 1:1000.

[0061] Comparative Example 1

[0062] Take 4 g of epoxy resin MT-HY02 and 0.7 g of epoxy resin curing agent CA-8113, stir for 5 minutes to mix evenly, and then let stand for 5 minutes to remove air bubbles. Then use a 40 μm wire bar coater to evenly coat the mixture onto the steel plate, ensuring a consistent coating thickness; place the coated steel plate in an oven and cure at a constant temperature of 60℃ for 12 hours to ensure complete curing; remove the cured coating and use a thickness gauge to accurately measure the coating thickness to ensure that the coating quality meets the predetermined standards.

[0063] Comparative Example 2

[0064] Hydrogen-barrier coatings for Comparative Example 2 were prepared using the same method as in Example 1, except that P-MX was replaced with MXene, i.e., unmodified MXene was used directly.

[0065] Test Example 1

[0066] Figure 1 The Fourier transform infrared (FTIR) spectra of unmodified MXene and P-MX prepared according to this invention are shown. Figure 1 As shown, the FTIR spectrum of unmodified MXene is at 554 cm⁻¹. - ¹、1032 cm - ¹, 1634 cm - ¹ and 3424 cm - A prominent peak is observed at ¹, corresponding to the stretching vibrations of Ti-O, C=O, and OH bonds, respectively; these are typical peaks for MXene. Unlike unmodified MXene, P-MX modified with polydopamine exhibits new peaks related to aromatic and nitrogen-containing compounds, at 795 cm⁻¹. -1 The nearby peak originates from the C-OH out-of-plane bending vibration mode, 1500 cm. -1 This is then assigned to the tensile vibration of the aromatic ring in C=CC. 1620cm -1 The peak value at this location is an overlapping peak of C=O and C=N. Furthermore, the characteristic peak is located between 3200 and 3500 cm⁻¹. -1 The large absorption peak is an overlap of the OH and NH stretching vibrations. This is due to the formation of hydrogen bonds between MXene and polydopamine. These results confirm the successful modification of MXene by PDA.

[0067] Test Example 2

[0068] Figure 2 The XRD patterns of MXene and P-MX prepared according to this invention are shown. Figure 2In the P-MX spectrum, the peaks at 8.5° and 27.96° originate from the 002 and 008 crystal planes of MXene. Furthermore, the peaks at 18.1° and 60.5° likely originate from the 004 and 110 crystal planes of the unmodified MXene phase. The spectra of P-MX are quite similar to those of MXene, indicating that the crystal structure of MXene itself was not altered during the modification process. Additionally, the 002 peak of MXene shifted from 8.5° to 8.8°. This is due to the increased interlayer spacing of the P-MX coating after PDA modification. This indicates that PDA successfully polymerized between the MXene layers, and the increased interlayer spacing indirectly reflects the successful modification by PDA.

[0069] Test Example 3

[0070] The changes in the microstructure of the filler were observed using SEM images at different magnifications, such as... Figure 3 As shown. From Figure 3 (a) It can be seen that unmodified MXene exhibits a characteristic multilayered "accordion-like" structure with a smooth surface, presenting a typical appearance of a two-dimensional layered structure. From Figure 3 (b) It can be seen that after modification with polydopamine, the surface of P-MX becomes rougher, and substances of a certain shape are clearly observed to be synthesized in the layers. This is due to the in-situ polymerization of polydopamine in the MXene layers. In addition, it can be observed that the interlayer polymerization of polydopamine leads to an increase in the interlayer spacing compared to MXene, which helps to avoid the layered stacking of MXene. The observation of the microstructure further illustrates the successful modification of MXene by polydopamine.

[0071] Test Example 4

[0072] The adhesion of the coatings prepared in Examples 1-2 and Comparative Examples 1-2 was tested using a DeFelsko PosiTest AT-M adhesion tester according to GB / T 5210-2006 standard. The results are shown in Table 1 below. Table 1 shows that the adhesion of the epoxy resin coating in Comparative Example 1 was 20.71 MPa, indicating that pure epoxy resin itself possesses excellent adhesion. As in Examples 1-2, the addition of P-MX resulted in hydrogen bonds between the amino and hydroxyl functional groups on its surface and the epoxy resin, which is beneficial for enhancing the compatibility within the coating. However, this consumed the hydroxyl groups of the epoxy resin itself, potentially reducing the number of chemical bonds between the coating and the substrate. Therefore, the adhesion of the coating was slightly lower than that of the epoxy resin after the addition of P-MX, but it still maintained high adhesion.

[0073] Test Example 5

[0074] The electrochemical impedance spectroscopy results of the hydrogen-barrier coatings prepared in Examples 1-2 and Comparative Examples 1-2 after immersion in a 3.5 wt% NaCl solution are shown in Table 1 below. A higher electrochemical impedance spectroscopy indicates better corrosion resistance of the coating. As shown in Table 1, the impedance of Comparative Example 1 reaches 2.6 × 10⁻⁶. 10 Ω·cm 2 The impedance of Example 1 is as high as 2.66 × 10⁻⁶. 11 Ω·cm 2 This represents an improvement of approximately one order of magnitude compared to the pure epoxy resin coating in Comparative Example 1. This is because the unique structure of MXene can generate a "maze effect," extending the penetration path of corrosive media and blocking their penetration. On the other hand, the modification of polydopamine enables P-MX and epoxy resin to achieve good compatibility, inhibiting the aggregation of MXene nanosheets and reducing the likelihood of galvanic corrosion.

[0075] Test Example 6

[0076] Electrochemical hydrogen permeation tests were conducted on the hydrogen barrier coatings prepared in Examples 1-2 and Comparative Examples 1-2 according to ISO 16773-2-2016 to determine the hydrogen barrier performance of the coatings. The results are shown in Table 1 below. A lower hydrogen permeation current density indicates a stronger ability of the coating to block the permeation and diffusion of hydrogen atoms, and thus superior performance. As can be clearly seen from the test results in Table 1, overall, the permeation current density of the examples is lower than that of the comparative examples. The hydrogen permeation current density of Comparative Example 1 is 3.64 μA / cm². 2 This demonstrates that pure epoxy resin itself has a certain hydrogen barrier effect. However, in Example 1, the addition of P-MX significantly reduced the hydrogen permeation current density of the coating, with a steady-state hydrogen permeation current density of 0.72 μA / cm. 2 This indicates that the addition of P-MX can significantly enhance the hydrogen barrier effect of epoxy resin coating.

[0077] Test Example 7

[0078] The hydrogen permeation of the hydrogen-blocking coatings prepared in Examples 1-2 and Comparative Examples 1-2 was tested according to ISO 17081:2014, and the results are shown in Table 1 below. The lower the hydrogen content, the better the hydrogen barrier effect. The hydrogen content of the pure epoxy resin coating in Comparative Example 1 was 2.71 ppm, demonstrating a basic hydrogen barrier effect. The hydrogen content of Comparative Example 2, with the addition of unmodified MXene, was further reduced to 1.27 ppm. However, the coating prepared in Example 1 with added P-MX further reduced the hydrogen content to 1.02 ppm. This trend is completely consistent with the hydrogen permeation test results, indicating that the addition of P-MX can effectively inhibit hydrogen atoms from entering the metal matrix and reduce hydrogen permeation.

[0079] Table 1 Performance test results of hydrogen barrier coatings obtained in Examples 1-2 and Comparative Examples 1-2

[0080]

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A hydrogen-barrier coating based on modified MXene, comprising polydopamine-modified MXene, an epoxy resin, and optionally a curing agent.

2. The hydrogen-barrier coating according to claim 1, wherein the mass ratio of the polydopamine-modified MXene to the epoxy resin is 1-10:1000.

3. The hydrogen-barrier coating according to claim 1, wherein the mass ratio of the epoxy resin to the curing agent is 2-5:

1.

4. A method for preparing a hydrogen-barrier composite epoxy resin coating based on modified MXene according to any one of claims 1 to 3, comprising: Provides polydopamine-modified MXene; The polydopamine-modified MXene is mixed with an epoxy resin and optionally a curing agent.

5. The method of claim 4, wherein the polydopamine-modified MXene comprises: MXene, dopamine hydrochloride, and 3-hydroxymethylaminomethane were mixed in an aqueous solution and reacted. After post-treatment, polydopamine-modified MXene was obtained.

6. The method according to claim 5, wherein the mass ratio of dopamine hydrochloride to MXene is 1-2:2; and / or, The mass ratio of dopamine hydrochloride to 3-hydroxymethylaminomethane is 1-1.5:

1.

7. The method according to claim 5, wherein the reaction conditions are: a reaction temperature of 50-60°C and a reaction time of 10-15 hours.

8. A hydrogen storage or transport container, wherein the inner wall is coated with a hydrogen barrier coating formed by a hydrogen barrier coating based on a modified MXene composite epoxy resin according to any one of claims 1 to 3.

9. The hydrogen storage or transport container according to claim 8, wherein the thickness of the hydrogen barrier coating is 100-120 µm.

10. The hydrogen storage or transport container according to claim 8, wherein the container is selected from closed containers and pipelines.

11. A method for preparing a hydrogen storage or transport container according to any one of claims 8 to 10, comprising: Provide a hydrogen-barrier composite epoxy resin coating based on modified MXene according to any one of claims 1 to 3; The coating is applied to the inner wall of the container; The coating is cured to form a hydrogen-barrier coating on the inner wall. When coating is required, the coating, which does not contain a curing agent, is mixed with a curing agent, and then the coating is applied.

12. The method according to claim 11, wherein the conditions for curing the coating are: a curing temperature of 50-80°C and a curing time of 12-36 hours.

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