Photoresponsive self-healing MXene epoxy composite anticorrosive coating, and preparation method and application thereof

Abstract

The application discloses a kind of light response self-repairing MXene epoxy composite anticorrosion coating and its preparation method and application, preparation method includes: using solution blending method, Ti3C2T x MXene nanosheet, silane coupling agent, defoaming agent and grafting light response unit are blended with epoxy self-repairing matrix, then amine curing agent is added and mixed, the casting solution obtained is coated on the surface of pretreated substrate, and after curing and drying, a light response self-repairing MXene epoxy composite anticorrosion coating is obtained. The application synergistically couples the dual functions of MXene labyrinth barrier protection and light response self-repairing, the coating exhibits long-term and efficient corrosion medium barrier capability, while maintaining high mechanical stability and excellent self-repairing performance. The preparation process is simple, mild and suitable for long-term corrosion protection of oil pipelines, oil and gas equipment and steel structures.

Description

Technical Field

[0001] This invention relates to the field of metal corrosion protection materials, specifically to a photoresponsive self-healing MXene epoxy composite anti-corrosion coating, its preparation method, and its application; more specifically, it relates to a coating with epoxy resin as the matrix, coumarin photoresponsive units imparting self-healing function to the coating, and two-dimensional Ti3C2T... x MXene nanosheets enhance the barrier and protective performance of composite anti-corrosion coatings and their application in oil pipelines, oil and gas equipment, and metal protection of steel structures. Background Technology

[0002] Oil pipelines, oil and gas storage and transportation equipment, and marine or buried steel structures are subjected to a variety of factors during service, including oxygen, water, chloride ions, sulfides, acidic gases, salt spray, soil electrolytes, and temperature and humidity cycles. This makes the metal substrate susceptible to pitting corrosion, crevice corrosion, electrochemical corrosion, and stress corrosion cracking. Corrosion not only reduces the load-bearing capacity of pipelines or equipment but can also cause perforation leaks, production stoppages, safety accidents, and environmental pollution. Therefore, developing anti-corrosion coatings with long-lasting barrier properties, excellent adhesion, and the ability to recover from damage is crucial for ensuring the safe operation of oil and gas equipment.

[0003] Epoxy resin coatings are widely used in metal corrosion protection due to their advantages such as high adhesion, good film-forming properties, excellent chemical resistance, and convenient application. However, traditional epoxy coatings are prone to microcracks and porosity during long-term service due to curing shrinkage, mechanical impact, temperature fluctuations, or media penetration. Once the coating is partially damaged, corrosive media can quickly reach the metal / coating interface along the defects, causing interfacial corrosion and coating peeling. Furthermore, traditional epoxy coatings lack self-repair capabilities and cannot effectively block corrosion pathways, leading to a reduced protective lifespan. Additionally, currently commonly used pure epoxy coatings have relatively low corrosion protection efficiency.

[0004] Therefore, developing anti-corrosion coatings that combine long-lasting barrier properties with efficient self-healing capabilities has become a pressing technical problem to be solved in the fields of oil pipelines, oil and gas equipment, and steel structure protection. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned deficiencies in the prior art and provide a photoresponsive self-healing MXene epoxy composite anti-corrosion coating, its preparation method, and its application. The photoresponsive self-healing MXene epoxy composite anti-corrosion coating of this invention successfully constructs an epoxy self-healing matrix network structure formed by epoxy resin grafting 6,7-dihydroxycoumarin photoresponsive units, while simultaneously combining it with silane coupling agent-modified Ti3C2T... xThe labyrinthine physical barrier formed by MXene nanosheets in this invention synergistically couples the dual functions of MXene labyrinthine barrier protection and photoresponsive self-healing. The coating exhibits long-lasting and efficient corrosion barrier capabilities, while also possessing high mechanical stability and excellent self-healing performance. Furthermore, the preparation process is simple and the conditions are mild, making it suitable for long-term corrosion protection of oil pipelines, oil and gas equipment, and steel structures.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing a photoresponsive self-healing MXene epoxy composite anti-corrosion coating includes: using a solution blending method to mix Ti3C2T... x MXene nanosheets, silane coupling agent, defoamer, and epoxy self-healing matrix grafted with photoresponsive units are blended together, and then an amine curing agent is added for further mixing. The resulting casting solution is coated onto the surface of a pretreated substrate, and after curing and drying, the photoresponsive self-healing MXene epoxy composite anti-corrosion coating is obtained.

[0007] Optionally, the Ti3C2T x The preparation method of MXene nanosheets includes: using MAX phase Ti3AlC2 as raw material, performing liquid phase etching treatment, and then sequentially centrifuging, washing, filtration, drying and grinding to obtain the Ti3C2T x MXene nanosheets.

[0008] Optionally, the liquid phase etching process includes: adding the MAX phase Ti3AlC2 to the etchant, stirring at a constant temperature of 30-50℃ and 1000-1500rpm for 12-24h, and then sequentially centrifuging, washing until the solution pH is neutral, filtering, vacuum drying, and grinding to obtain the Ti3C2T. x MXene nanosheets.

[0009] Optionally, the mass-to-volume ratio of the MAX phase Ti3AlC2 powder to the etchant is 1 g: 20 mL.

[0010] Optionally, the etchant is a hydrofluoric acid solution with a mass fraction of 40 wt%.

[0011] Optionally, the vacuum drying temperature is 40°C.

[0012] Optionally, the silane coupling agent is at least one of KH-550, KH-560 and KH-570.

[0013] Optionally, the amine curing agent has an amine value of 600-700 mg KOH / g.

[0014] Optionally, the preparation method of the epoxy self-healing matrix of the grafted photoresponsive unit includes: mixing epoxy resin, 6,7-dihydroxycoumarin and isophorone diisocyanate and then carrying out a grafting reaction to obtain the epoxy self-healing matrix of the grafted photoresponsive unit.

[0015] Optionally, the mass ratio of the epoxy resin, the 6,7-dihydroxycoumarin, and the isophorone diisocyanate is 6.8:0.8:0.5.

[0016] Optionally, the grafting reaction is carried out at a temperature of 60-80°C for 1-3 hours.

[0017] Optionally, the epoxy resin is epoxy resin E-51.

[0018] Optionally, the blending temperature is 50-60°C.

[0019] Optionally, the mixing temperature is 50-60°C.

[0020] Optionally, the Ti3C2T x The total mass ratio of the epoxy self-healing matrix of MXene nanosheets, the silane coupling agent, and the grafted photoresponsive unit to the mass ratio of the amine curing agent is (7.7-9.4):3.2.

[0021] Optionally, the curing temperature is room temperature; the curing time is 2-4 hours.

[0022] Optionally, the drying is vacuum drying; the temperature of the vacuum drying is 40-50℃; and the time of the vacuum drying is 3-5 hours.

[0023] Optionally, the preparation method of the pretreated substrate includes: sanding the substrate step by step with sandpaper, degreasing it with acetone or ethanol, washing it with deionized water, and then drying it to obtain the pretreated substrate.

[0024] Optionally, the substrate is X70 steel.

[0025] Optionally, in the preparation method, Ti3C2T x The blending of MXene nanosheets, silane coupling agents, defoamers, and grafted photoresponsive units into an epoxy self-healing matrix specifically includes: blending Ti3C2T... x MXene nanosheets were added to an epoxy self-healing matrix grafted with photoresponsive units and stirred at 50-60℃ for 30 min. Then, an antifoaming agent and a silane coupling agent were added and stirred at 50-60℃ for 10 min.

[0026] Optionally, the thickness of the photoresponsive self-healing MXene epoxy composite anti-corrosion coating is 10 mm.

[0027] The present invention also discloses a photoresponsive self-healing MXene epoxy composite anti-corrosion coating prepared by the preparation method described above.

[0028] Optionally, the composite anti-corrosion coating includes: The epoxy self-healing matrix network is a cross-linked network structure formed by grafting 6,7-dihydroxycoumarin photoresponsive units onto epoxy resin. Silane coupling agent modified Ti3C2T x MXene nanosheets, for Ti3C2T x MXene nanosheets are formed after modification with a silane coupling agent; The epoxy self-healing matrix network enables the coating to undergo reversible cross-linking and local network reconstruction under light conditions, thus achieving self-healing capabilities.

[0029] Optionally, the composite anti-corrosion coating achieves a scratch repair efficiency of over 97% after being exposed to simulated sunlight for 180 minutes.

[0030] Optionally, the surface water contact angle of the composite anti-corrosion coating is 120° to 125°.

[0031] Optionally, the electrochemical impedance spectroscopy of the composite anti-corrosion coating in 3.5wt% NaCl solution shows that it has excellent long-term anti-corrosion performance.

[0032] The present invention also discloses the application of a photoresponsive self-healing MXene epoxy composite anti-corrosion coating prepared by the above preparation method in the anti-corrosion protection of oil pipelines, oil and gas equipment, and steel structures.

[0033] Implementing the embodiments of the present invention will have the following beneficial effects: (1) The present invention utilizes two-dimensional Ti3C2T with excellent mechanical strength, layered structure, high specific surface area and structural stability. x MXene nanosheets are introduced into the epoxy coating system. Their layered structure forms multiple layers of barriers and a labyrinth effect inside the coating, which significantly prolongs the diffusion path of corrosive media and reduces the penetration rate of water, oxygen and chloride ions into the metal substrate, thereby improving the long-term anti-corrosion performance of the coating.

[0034] (2) In this invention, 6,7-dihydroxycoumarin photoresponsive units are grafted into the epoxy resin network, so that the coating can undergo photoresponsive reversible cross-linking and local network reconstruction under light conditions, thereby achieving the closure of microcracks or scratches and the coating’s excellent self-healing ability, and improving the coating’s protective recovery ability after damage.

[0035] (3) This invention uses a silane coupling agent to improve the dispersibility of MXene, enhance the mechanical stability and interfacial adhesion of the coating, and adapt to the complex service environment of oil pipelines. The preparation process of this invention is simple, the reaction conditions are mild, and it can be formed using conventional coating and curing processes, showing good prospects for engineering application. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating the preparation process of the composite anti-corrosion coating in Example 1 of the present invention.

[0037] Figure 2 FTIR spectra of EP, DDm, EP-DDm, and EP-DDm / MXene.

[0038] Figure 3 The figure shows the static water contact angle test results for coatings with different MXene contents.

[0039] Figure 4 This is an evaluation chart showing the adhesion and wear resistance of the EP-DDm / MX-4 anti-corrosion coating to the substrate.

[0040] Figure 5 Electrochemical impedance spectroscopy for coatings with different MXene contents.

[0041] Figure 6a Photoresponsive self-healing optical micrograph of a coating with 1.6% MXene addition; Figure 6b This is an optical micrograph of the photoresponsive self-healing coating of EP-DDm / MX-4 in Example 1. Detailed Implementation

[0042] The following embodiments are merely some, not all, of the embodiments of the present invention. Therefore, the detailed descriptions of the embodiments provided below are not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0043] In this invention, unless otherwise specified, all equipment and raw materials are commercially available or commonly used in the industry. The methods described in the following embodiments are conventional methods in the art, unless otherwise specified.

[0044] Example 1 The method for preparing the photoresponsive self-healing MXene epoxy composite anti-corrosion coating in this embodiment includes: (a) Preparation of Ti3C2T x MXene nanosheets Step 1: Add 20 mL of 40 wt% hydrofluoric acid solution to the polytetrafluoroethylene reactor; Step 2: Weigh 1g of MAX phase Ti3AlC2 and slowly add it to the reactor in small amounts. Place the reactor in an oil bath and stir magnetically at 1000rpm and 40℃ for 24 hours. Step 3: Pour the obtained solution into a centrifuge tube, centrifuge at 8000 rpm for 5 min, add deionized water, and centrifuge and wash until the pH of the filtrate is neutral; Step 4: Filter the product, dry it in a vacuum drying oven at 40℃, and grind it into powder.

[0045] (II) Preparation of EP-DDm self-healing matrix Step 1: Mix 6.8g of epoxy resin E-51, 0.8g of 6,7-dihydroxycoumarin, and 0.5g of isophorone diisocyanate; Step 2: Place the mixture in a 70℃ oil bath and stir for 2 h to allow the coumarin units to be grafted onto the epoxy resin molecular chain or network precursor via isocyanate linkage, thereby obtaining the EP-DDm self-healing matrix grafted with photoresponsive coumarin units.

[0046] (III) Preparation of photoresponsive self-healing MXene epoxy composite anti-corrosion coating Step 1: Add 0.2 g Ti3C2T x MXene nanosheets were added to 8.1g of EP-DDm self-healing matrix and stirred at 60℃ for 30 min. Then, 0.6g of defoamer and 0.3g of 3-aminopropyltriethoxysilane (KH-550) were added and stirred at 60℃ for 10 min.

[0047] Step 2: Add 3.2 g of amine curing agent (amine value 600-700 mg KOH / g, Shanghai Maclean) to the above dispersion system, and continue stirring at 60°C until the system is uniform and free of obvious agglomerates; polish the X70 steel sheet step by step with sandpaper, degrease it with acetone or ethanol, clean it with deionized water and dry it to obtain the pretreated metal substrate; Step 3: Apply the coating obtained in Step 2 evenly to the pretreated X70 steel surface, cure at room temperature for 3 hours, and then vacuum dry at 40℃ for 4 hours to obtain a 10mm thick photoresponsive self-healing MXene epoxy composite anti-corrosion coating (EP-DDm / MX-4).

[0048] Examples 2-8: To investigate Ti3C2T x The effect of MXene nanosheet addition on coating performance: keeping other conditions consistent with Example 1, only the Ti3C2T content was changed. x The amounts of MXene nanosheets added were used to prepare the following: Example 2: Ti3C2T x The amount of MXene nanosheets added was 0.05g, denoted as EP-DDm / MX-1; Example 3: Ti3C2T x The amount of MXene nanosheets added was 0.1g, denoted as EP-DDm / MX-2; Example 4: Ti3C2T x The amount of MXene nanosheets added was 0.15g, denoted as EP-DDm / MX-3; Example 5: Ti3C2T x The amount of MXene nanosheets added was 0.25g, denoted as EP-DDm / MX-5; Example 6: Ti3C2T x The amount of MXene nanosheets added was 0.3g, denoted as EP-DDm / MX-6; Example 7: Ti3C2T x The amount of MXene nanosheets added was 0.35g, denoted as EP-DDm / MX-7; Example 8: Ti3C2T x The amount of MXene nanosheets added was 0.4g, denoted as EP-DDm / MX-8.

[0049] Performance testing (1) The Fourier transform infrared spectra of DDm, EP, EP-DDm and EP-DDm / MXene in Example 1 are shown in [reference needed]. Figure 2 As can be seen from the figure: The EP-DDm / MXene coating, formed by solution blending EP-DDm and MXene, exhibits better performance at 1600 cm⁻¹ compared to EP. - ¹ A distinct aromatic ring characteristic absorption peak appears near 1500 cm⁻¹, and at the same time, a peak appears at 1500 cm⁻¹. - ¹and 1250~1300 cm - The absorption peak intensity at ¹ is significantly enhanced, and it reaches 3300 cm⁻¹. - A relatively broad absorption band appears near ¹, which is attributed to the NH stretching vibration. The characteristic absorption peak of DDm mentioned above still exists in the EP-DDm / MXene composite coating, indicating that DDm has not been destroyed in the composite system and still maintains its chemical structure.

[0050] (2) The water contact angle test results of EP-DDm and EP-DDm / MXene in Examples 1-9 are shown in Figure 3 As can be seen from the figure: The water contact angle of the pure epoxy resin E-51 (EP) coating is only about 94°, and water droplets on its surface are flat, indicating weak hydrophobicity. The contact angle of the EP-DDm coating grafted with coumarin units increases to about 99.8°, and the hydrophobicity is slightly improved. With the introduction of MXene nanosheets, the contact angle of the EP-DDm / MX coating first increases and then decreases with the increase of MXene content, and then tends to stabilize. The contact angle finally stabilizes between 120° and 125°, indicating that the EP-DDm / MXene nanocomposite anti-corrosion coating can be uniformly dispersed in corrosive media, significantly blocking water penetration and improving anti-corrosion performance.

[0051] (3) Mechanical performance testing The adhesion and abrasion resistance of the prepared EP-DDm / MXene-4 anti-corrosion coating to the substrate were evaluated using loaded tape peeling and sandpaper abrasion tests. The evaluation results are as follows: Figure 4 As shown; The initial contact angle of the sample was 125.93°, exhibiting good hydrophobic properties. During the initial testing phase (0-20 cycles), the contact angle remained above 125°, and even increased slightly, regardless of tape peeling or sandpaper rubbing. This indicates that the coating structure remained intact under slight mechanical action without significant damage.

[0052] With increasing cycle count (>30 cycles), the contact angle in both tests showed a decreasing trend, but the decrease was relatively gradual. Notably, the tape peel test exhibited slightly better stability than the sandpaper abrasion test. After 45 cycles, the contact angle of the tape peel sample remained around 120°, while the contact angle of the sandpaper abrasion sample decreased to approximately 117°. Despite undergoing multiple mechanical abrasion cycles, the contact angle of the samples consistently remained above 115° (far exceeding the hydrophobic critical value of 90°), strongly demonstrating the excellent mechanical robustness and long-term hydrophobic stability of the material surface, enabling it to withstand relatively harsh physical abrasion environments.

[0053] (4) Anti-corrosion effect test Test Example 1: This test compares and evaluates the anti-corrosion effect of the anti-corrosion coatings prepared in Example 1 on X70 steel substrate. The evaluation standard is in accordance with GB / T 39482.3-2020. Test conditions: The coating was applied to the surface of X70 steel and tested in a 3.5 wt% NaCl solution. The evaluation results are as follows. Figure 5 As shown; Depend on Figure 5 It can be seen that the impedance modulus |Z| of the unprotected X70 bare steel substrate is 0 in the low-frequency region (f=0.01Hz). 01Hz Only ~10 3 Ω·cm 2This indicates that it is in an activated state of rapid corrosion. In contrast, the |Z| of all coating samples... 0.01HZ The values ​​all increased by 5 to 8 orders of magnitude, demonstrating that the epoxy coating provides excellent protection to the substrate. Specifically, the 1.6% MXene composite coating showed a significant improvement in |Z|. 0.01HZ Values ​​exceeding 10 10 Ω·cm 2 It performed best among all samples, outperforming pure DDM coatings (~10). 9 Ω·cm 2 It is nearly two orders of magnitude higher.

[0054] Experimental Example 2: This experiment compares and evaluates the self-healing performance (optical microscopy) of the anti-corrosion coating prepared in Example 1 on X70 steel substrate.

[0055] Test conditions: Artificial scratches were applied to the coating surface, and the surface was exposed to simulated sunlight for 180 minutes. The evaluation results are shown in Figure 6. The anti-corrosion coating provided in Example 1 achieved a scratch repair efficiency of 97% after photo-repair. However, at 1.6% MXene, the coating's self-healing performance abnormally decreased. Excessive MXene addition also led to excessively high coating stability temperatures, which could cause reverse reactions or substrate damage. Furthermore, the longer the isothermal time, the worse the repair effect. Experimental results indicate that the EP-DDm / MXene composite material can significantly improve the coating's anti-corrosion performance and self-healing efficiency.

[0056] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a photoresponsive self-healing MXene epoxy composite anti-corrosion coating, characterized in that, The preparation method includes: Using solution blending, Ti3C2T x MXene nanosheets, silane coupling agent, defoamer, and epoxy self-healing matrix grafted with photoresponsive units are blended together, and then an amine curing agent is added for further mixing. The resulting casting solution is coated onto the surface of a pretreated substrate, and after curing and drying, the photoresponsive self-healing MXene epoxy composite anti-corrosion coating is obtained.

2. The method for preparing the photoresponsive self-healing MXene epoxy composite anti-corrosion coating according to claim 1, characterized in that, The Ti3C2T x Methods for preparing MXene nanosheets include: Using MAX phase Ti3AlC2 as raw material, liquid phase etching was performed, followed by centrifugation, washing, filtration, drying, and grinding to obtain the Ti3C2T. x MXene nanosheets.

3. The method for preparing the photoresponsive self-healing MXene epoxy composite anti-corrosion coating according to claim 2, characterized in that, The liquid phase etching process includes: adding the MAX phase Ti3AlC2 to the etchant, stirring at a constant temperature of 30-50℃ and 1000-1500rpm for 12-24 hours, and then sequentially centrifuging, washing until the solution pH is neutral, filtering, vacuum drying, and grinding to obtain the Ti3C2T. x MXene nanosheets; The mass-to-volume ratio of the MAX phase Ti3AlC2 powder to the etchant is 1g:20mL; The etchant is a hydrofluoric acid solution with a mass fraction of 40 wt%. The vacuum drying temperature is 40°C.

4. The method for preparing the photoresponsive self-healing MXene epoxy composite anti-corrosion coating according to claim 1, characterized in that, The silane coupling agent is at least one of KH-550, KH-560 and KH-570; The amine value of the amine curing agent is 600-700 mg KOH / g.

5. The method for preparing the photoresponsive self-healing MXene epoxy composite anti-corrosion coating according to claim 1, characterized in that, The preparation method of the epoxy self-healing matrix of the grafted photoresponsive unit includes: mixing epoxy resin, 6,7-dihydroxycoumarin and isophorone diisocyanate and then carrying out a grafting reaction to obtain the epoxy self-healing matrix of the grafted photoresponsive unit. The mass ratio of the epoxy resin, the 6,7-dihydroxycoumarin, and the isophorone diisocyanate is 6.8:0.8:0.

5. The grafting reaction is carried out at a temperature of 60-80℃ for 1-3 hours. The epoxy resin is epoxy resin E-51.

6. The method for preparing the photoresponsive self-healing MXene epoxy composite anti-corrosion coating according to claim 1, characterized in that, The blending temperature is 50-60℃; The mixing temperature is 50-60℃; The Ti3C2T x The total mass ratio of the epoxy self-healing matrix of MXene nanosheets, the silane coupling agent, and the grafted photoresponsive unit to the amine curing agent is (7.7-9.4):3.2; The curing temperature is room temperature; the curing time is 2-4 hours. The drying process is vacuum drying; the vacuum drying temperature is 40-50℃; and the vacuum drying time is 3-5 hours.

7. The method for preparing the photoresponsive self-healing MXene epoxy composite anti-corrosion coating according to claim 1, characterized in that, The thickness of the photoresponsive self-healing MXene epoxy composite anti-corrosion coating is 10 mm.

8. The method for preparing the photoresponsive self-healing MXene epoxy composite anti-corrosion coating according to claim 1, characterized in that, The method for preparing the pretreated substrate includes: sequentially sanding the substrate with sandpaper, degreasing it with acetone or ethanol, cleaning it with deionized water, and then drying it to obtain the pretreated substrate; wherein the substrate is X70 steel.

9. A photoresponsive self-healing MXene epoxy composite anti-corrosion coating prepared by the preparation method according to any one of claims 1-8.

10. The application of a photoresponsive self-healing MXene epoxy composite anti-corrosion coating prepared by the preparation method according to any one of claims 1-8 in the anti-corrosion protection of oil pipelines, oil and gas equipment, and steel structures.

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