Eutectic solvent / epoxy resin composite self-repairing anticorrosive coating and preparation method thereof
By introducing hydrophobic siloxane segments and eutectic solvents into the coating, a solid-liquid composite self-healing coating suitable for multiple environments is built, which solves the problem of underwater repair failure of existing coatings and realizes the stability and autonomous self-healing ability of the coating in multiple environments.
Patent Information
- Application Number
- CN202510417641.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2025-07-22
AI Technical Summary
The existing self-healing coatings fail to repair due to water absorption problems in complex service environments, especially in underwater environments, which limits their application scope.
By introducing a hydrophobic siloxane segment modified epoxy resin network as a stationary phase and adding a hydrophobic eutectic solvent as a mobile phase, a solid-liquid composite self-healing coating suitable for multiple environments is constructed, and the hydrophobicity enhancement and self-healing ability of the coating is achieved by utilizing the flexibility of the silicone segment and the dynamic nature of the eutectic solvent.
The stability and self-repairing ability of the coating in multiple environments are achieved, the repair efficiency of the coating in the atmosphere and underwater environments is improved, and the interference of water molecules on the repair process is avoided.
Smart Images
Figure CN120349692A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of functional coatings, and particularly relates to a water environment-tolerant deep eutectic solvent / epoxy resin composite self-healing anti-corrosion coating and a preparation method thereof. Background Art
[0002] Coating technology is the core means to improve the surface protection performance of matrix materials. However, in complex service environments, coatings often suffer from accidental damage, leading to problems such as interfacial peeling, microcrack initiation, and decline of protection functions. Therefore, intelligent coating systems with damage self-healing characteristics have become the research focus in the current field of surface engineering. However, the core bottleneck of self-healing coating technology is that the strong adhesion of the substrate hinders the spontaneous contact of the damaged interface and inhibits the in-situ damage repair mechanism. Currently, although the "shape memory" effect and high-elasticity materials can assist in microcrack repair, they are limited by the inherent strain recovery threshold and have insufficient repair efficiency for large cracks. In particular, the "shape memory" effect relies on external stimuli and has significant application limitations in actual engineering scenarios, resulting in obstacles to technology promotion. Therefore, developing a new type of autonomous self-healing technology for coating damage is of great significance for practical applications.
[0003] Inspired by the design concept of solid-liquid composite materials, by introducing the dynamic, diffusive, flowing, self-healing, and adaptive characteristics of liquid materials into the solid matrix, the molecular mobility and mesoscopic fluidity of the coating microstructure can be significantly improved, thereby promoting the spontaneous contact of the damaged interface. Currently, the liquid materials widely used in solid-liquid composite material systems mainly include aqueous solutions, oil-based solutions, ionic liquids (ILs), deep eutectic solvents (DESs), and liquid metals. As a new type of emerging green solvent based on hydrogen bond interactions, DESs have low volatility, low toxicity, and designability. Their highly dynamic hydrogen bond network endows the material with the potential for self-healing at room temperature and can be used as an ideal "mobile phase" component in the construction of solid-liquid composite autonomous self-healing coatings. However, most DESs have strong hydrophilicity, resulting in varying degrees of repair failure of the dynamic physical / chemical interactions relied on during the self-healing process due to interference from water molecules in multiple aspects, limiting their applicability in multiple environments. Therefore, if we want to better expand the application of DESs, a new type of solvent with economy, environmental friendliness, and multifunctional characteristics, into the coating system, we need to focus on solving the water absorption problem faced. Summary of the Invention
[0004] The present invention provides a preparation method for a water environment-tolerant deep eutectic solvent / epoxy resin composite self-healing anti-corrosion coating. Based on the enhanced hydrophobicity design of deep eutectic solvents (DESs), the influence of water molecules on the coating repair process is shielded, ensuring the stability and self-healing property of the coating and endowing the coating with applicability in multiple environments.
[0005] The technical solution adopted by the present invention is to enhance the hydrophobicity of the solid-liquid composite self-healing coating through the synergistic strategy of "subject design" and "guest introduction", and give the coating applicability in multiple environments such as atmosphere and underwater. Specifically, "subject design" is to introduce hydrophobic segments into the resin matrix through molecular structure design. The hydrophobic segments represented by siloxane have low surface energy characteristics due to their unique chemical structure, which can give the polymer matrix excellent hydrophobicity, chemical stability, biocompatibility and mechanical flexibility, and have been widely used in the construction of functional coatings and biomedical devices. Therefore, the resin network containing siloxane segments can be used as a "stationary phase" to enhance the hydrophobicity of the solid-liquid composite self-healing coating. "Guest introduction" is to introduce hydrophobic substances into the polymer system to enhance the hydrophobicity of the coating. Designing a low eutectic solvent (HDESs) with hydrophobicity and using it as a polymerization reaction medium is a clever way to introduce hydrophobic interactions externally. More importantly, HDESs has both room temperature flow characteristics and small molecule diffusion kinetics advantages, which can effectively promote autonomous contact of the coating damage interface. Therefore, using HDESs as the "mobile phase" to construct a solid-liquid composite autonomous self-healing coating with multi-environmental applicability is a feasible solution.
[0006] Based on this, the present invention synthesized an epoxy resin network skeleton "stationary phase" containing dynamic aromatic disulfide bonds and intrinsic hydrophobic siloxane segments through "main body design", achieving enhanced hydrophobicity of the system in the molecular structure, while the flexibility of the siloxane segments improves the elasticity of the coating. The "guest introduced" hydrophobic low eutectic solvent "mobile phase" is confined and coated in the resin network structure through physical action, further enhancing the hydrophobicity of the solid-liquid composite autonomous self-healing coating. In this way, a solid-liquid composite coating material is constructed that realizes autonomous self-healing of multiple environmental damages based on the "confined flow" characteristics at the molecular level.
[0007] The present invention provides a method for preparing a low eutectic solvent / epoxy resin composite self-repairing anti-corrosion coating, comprising the following steps: (1) stirring and mixing the hydrogen bond donor and the hydrogen bond acceptor to obtain a hydrophobic deep eutectic solvent; (2) stirring and mixing the siloxane-modified epoxy resin monomer and the curing agent to obtain a siloxane-modified epoxy resin casting solution; (3) adding a hydrophobic low eutectic solvent to the siloxane-modified epoxy resin film casting solution, stirring and mixing to obtain a hydrophobic low eutectic solvent / siloxane-modified epoxy resin coating film casting solution; (4) vacuum degassing the hydrophobic low eutectic solvent / siloxane-modified epoxy resin casting solution; (5) The vacuum degassed casting solution is applied to the protected substrate while hot, solidified, and then taken out and cooled to obtain a coating.
[0008] Among them, in step (1), the hydrogen bond donor includes any one or more of thymol, 1-naphthol, n-decanoic acid, and lidocaine, and the hydrogen bond acceptor includes any one or more of methyl salicylate, coumarin, menthol, and ibuprofen; the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1 to 3:1.
[0009] Among them, in step (1), the stirring temperature is 30-90 °C, and the stirring time is 1-2 h.
[0010] Among them, in step (2), the silicone-modified epoxy resin monomer is 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane; the curing agent is an amine curing agent containing a disulfide bond, including any one or more of 2,2'-diaminodiphenyl disulfide, 4,4'-diaminodiphenyl disulfide, and their modified products; the molar ratio of the silicone-modified epoxy resin monomer to the curing agent is 1:1; the stirring time is 1-2 h.
[0011] Among them, in step (3), the mass fraction of the hydrophobic deep eutectic solvent is 30 wt%-50 wt%, and the stirring time is 1-2 h.
[0012] Among them, in step (4), the temperature of vacuum degassing is 60-70 °C, and the time of vacuum degassing is 15-30 min.
[0013] Among them, in step (5), the coating method is preheating spraying, brushing, pouring, or dip coating; the curing time corresponds to the curing temperature, the curing temperature is 80-120 °C, and the curing time is 4-12 h.
[0014] The present invention also provides a deep eutectic solvent / epoxy resin composite self-healing anti-corrosion coating, which is prepared by the above preparation method.
[0015] Compared with the prior art, the positive and progressive effects of the present invention are as follows: (1) The present invention innovatively proposes a hydrophobicity enhancement strategy based on the synergy of "host design" and "guest introduction", and realizes the directional regulation of the hydrophobic interaction between the host and guest components of the coating and improves the underwater stability of the coating by means of modifying epoxy resin with hydrophobic silicone segments and introducing hydrophobic deep eutectic solvents at the same time. At present, there are no relevant reports on using the host-guest synergy regulation mechanism to synchronously optimize the hydrophobicity of the coating components and then improve the underwater stability.
[0016] (2) The present invention realizes the construction of a multi-environment (atmospheric / underwater) autonomous self-healing coating based on the synergistic mechanism of the hydrophobic low eutectic solvent and the dynamically reversible siloxane-modified epoxy resin network. The resin molecular chains are driven to migrate to the defective area by the small molecule diffusion of the hydrophobic low eutectic solvent, and the elastic recovery properties of the coating are endowed with the flexibility of the siloxane chain segments, which synergistically promotes the spontaneous contact of the damaged interface without external stimulation. At the same time, under the joint action of the hydrophobicity and the dynamically reversible bonds in the system, the coating cracks can be autonomously self-repaired in multiple environments (atmospheric / underwater). At present, there are no reports on the one-step construction of a multi-environment autonomous self-healing coating using a hydrophobic low eutectic solvent mobile phase combined with a dynamically reversible hydrophobic siloxane-modified epoxy resin network fixation. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which: Figure 1 Infrared spectra of HDES and SiEP-SS / HDES coatings; Figure 2 The change of water absorption rate of SiEP-SS / HDES coating before and after immersion in water; Figure 3 This is a graph showing the elastic recovery test results of SiEP-SS / HDES coating; Figure 4 Microscopic comparison of SiEP-SS / HDES coating before and after self-repair in multiple environments (atmosphere / underwater); Figure 5 This is the case of SiEP-SS / HDES coating being resistant to salt spray. DETAILED DESCRIPTION
[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1
[0019] This embodiment provides a method for preparing a low eutectic solvent / epoxy resin composite self-repairing anti-corrosion coating, comprising the following steps: (1) Weigh 1 kg of thymol and 1.01 kg of methyl salicylate and put them into a reaction kettle. Set the temperature of the reaction kettle to 30 °C and stir for 2 h under the condition of a stirrer to obtain a transparent and uniform hydrophobic deep eutectic solvent; (2) Weigh 2 kg of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane and 1.5 kg of 2,2'-diaminodiphenyl disulfide curing agent. Set the temperature of the reaction kettle to 60 °C and stir thoroughly for 1 h to obtain a silicone-modified epoxy resin casting solution; (3) Add the hydrophobic deep eutectic solvent to the silicone-modified epoxy resin / curing agent mixed solution, and the mass fraction of the hydrophobic deep eutectic solvent is 40 wt%. Stir thoroughly for 1 h; (4) Set the temperature of the reaction kettle to 60 °C and conduct vacuum degassing for 20 min to obtain a yellow and uniform casting solution; (5) Brush the obtained casting solution onto the surface of a carbon steel substrate while it is hot, and then cure it in an oven at 80 °C for 12 h; finally, cool it naturally to obtain a hydrophobic deep eutectic solvent / silicone-modified epoxy resin self-healing coating. Example 2
[0020] This example provides a preparation method for a deep eutectic solvent / epoxy resin composite self-healing anti-corrosion coating, which includes the following steps: (1) Weigh 1.57 kg of lidocaine and 0.49 kg of coumarin and put them into a reaction kettle. Set the temperature of the reaction kettle to 60 °C and stir for 1.5 h under the condition of a stirrer to obtain a transparent and uniform hydrophobic deep eutectic solvent; (2) Weigh 1.5 kg of 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane and 0.98 kg of 4,4'-diaminodiphenyl disulfide curing agent. Set the temperature of the reaction kettle to 60 °C and stir thoroughly for 1 h to obtain a silicone-modified epoxy resin casting solution; (3) Add the hydrophobic deep eutectic solvent to the silicone-modified epoxy resin / curing agent mixed solution, and the mass fraction of the hydrophobic deep eutectic solvent is 30 wt%. Stir thoroughly for 2 h; (4) Set the temperature of the reaction kettle to 70 °C and conduct vacuum degassing for 15 min to obtain a yellow and uniform casting solution; (5) Spray the obtained casting solution onto the surface of a carbon steel substrate through a preheated nozzle with a diameter of 1 mm, and place it in an oven at 120 °C for 4 h; finally, cool it naturally to obtain a hydrophobic deep eutectic solvent / silicone-modified epoxy resin self-healing coating. Example 3
[0021] This example provides a preparation method for a deep eutectic solvent / epoxy resin composite self-healing anti-corrosion coating, which includes the following steps: (1) Weigh 2.88 kg of 1-naphthol and 1.04 kg of menthol and put them into the reaction kettle. Set the temperature of the reaction kettle to 90 °C and stir for 1 h under the condition of a stirrer to obtain a transparent and uniform hydrophobic eutectic solvent; (2) Weigh 1.5 kg of 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane and 1.1 kg of 2,2'-diaminodiphenyl disulfide curing agent. Set the temperature of the reaction kettle to 60 °C and stir thoroughly for 2 h to obtain a silicone-modified epoxy resin casting solution; (3) Add the hydrophobic eutectic solvent to the silicone-modified epoxy resin / curing agent mixed solution. The mass fraction of the hydrophobic eutectic solvent is 50 wt%, and stir thoroughly for 1 h; (4) Set the temperature of the reaction kettle to 60 °C and degas under vacuum for 30 min to obtain a yellow and uniform casting solution; (5) Pour the obtained casting solution onto the surface of the carbon steel substrate while it is hot, and then cure it in an oven at 100 °C for 8 h; finally, cool it naturally to obtain a hydrophobic eutectic solvent / silicone-modified epoxy resin self-healing coating.
[0022] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that it does not contain a hydrophobic eutectic solvent and includes the following steps: (1) Stir and mix 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane and 2,2'-diaminodiphenyl disulfide curing agent with a molar ratio of 1:1 under the stirring condition of a temperature of 60 °C and a stirring time of 1 h to obtain a coating casting solution; (2) Perform vacuum degassing treatment on the coating casting solution. The vacuum degassing conditions are: a temperature of 60 °C and a degassing time of 20 min; (3) Coat the vacuum-degassed casting solution onto the protected substrate while it is hot by spraying, brushing, pouring or dipping methods, and cure it. The curing temperature is 120 °C and the curing time is 6 h, and then take it out and cool it to obtain a coating.
[0023] Property Test 1. Infrared test: Use a Bruker INVENIO S Fourier transform infrared spectrometer (FTIR) equipped with an attenuated total reflection (ATR) detector to monitor the change of functional groups, with a scanning range of 4000–500 cm -1 , and a resolution of 4 cm -1 .
[0024] 2. Water absorption test: Immerse the SiEP-SS / HDES coating in water for 7 days and monitor the change of the coating mass every 1 day.
[0025] 3. Elastic recovery rate test: The elastic recovery ability of the coating surface was tested using an Anton Paar UNHT nanoindentation instrument with an indentation depth of 2500 nm and a dwell time of 0.5 s.
[0026] 4. Electron microscopy observation before and after self-healing: The coating was scratched with a blade until it contacted the substrate, and an Olympus BX53-P optical microscope was used to monitor the self-healing process of the coating damage.
[0027] 5. Coating salt spray test: An accelerated corrosion experiment (5.0 wt% NaCl, pH = 7.0) was used to further evaluate the effect of the self-healing performance of the coating on the salt spray resistance performance. The coated sample (3 × 5 cm) on the Q235 carbon steel substrate was cross-scratched with a blade (scratch length 3 cm) and exposed to salt spray for 720 h (placement angle 45°), and the corrosion condition of the substrate at the scratched position was recorded.
[0028] Results: The infrared spectrum of HDES ( Figure 1 (a)) shows that the carbonyl peak (C=O) of the hydrogen bond acceptor moves from 1672 cm −1 to 1676 cm −1 , and the hydroxyl peak (O−H) of the hydrogen bond donor moves from 3195 cm −1 to 3454 cm −1 , confirming the formation of hydrogen bond interactions between the components of HDES. The infrared spectrum of the SiEP-SS / HDES coating ( Figure 1 (b)) shows that the characteristic epoxy group peak at 909 cm −1 disappears and the characteristic S-S bond peak at 746 cm −1 appears, indicating that the curing agent and the epoxy group have undergone a ring-opening addition reaction, confirming the successful synthesis of the coating. In addition, the C=O of HDES moves from 1676 cm −1 to 1682 cm −1 , indicating that there is an intermolecular interaction between HDES and the epoxy resin network, so that HDES is stably encapsulated in the epoxy resin network as a "mobile phase".
[0029] Through the 7-day water absorption test ( Figure 2 ), it was found that the water absorption rate of the SiEP-SS / HDES system was only 1.24%, which was lower than that of the SiEP-SS (1.41%) control group. This is attributed to the hydrophobic barrier formed by the siloxane segments and HDES effectively blocking the diffusion of water molecules, and the complete reaction of the amino group of the curing agent with the epoxy group of the silane-modified epoxy resin to form a dense cross-linked structure, reducing the penetration of water molecules.
[0030] Meanwhile, the flexibility of the siloxane segments improves the elastic recovery ability of the coating surface ( Figure 3 ). The elastic recovery ability of the SiEP-SS / HDES coating surface was measured by nanoindentation. The elastic recovery rate of the SiEP-SS / HDES coating was calculated to be 71.4% based on the load-displacement curve. The hydrophobicity and unique interfacial spreading characteristics of the coating endow it with extremely rapid damage self-healing ability in multiple environments (atmosphere / underwater).
[0031] In addition, the resilience of the coating surface and the dynamic reversible disulfide bonds contribute to the reconstruction of the epoxy resin network ( Figure 4 a). The scratch on the SiEP-SS / HDES coating closed within 1 h at room temperature. It is worth noting that due to the hydrophobicity of the siloxane segments in HDES and SiEP-SS, the SiEP-SS / HDES coating still exhibited significant self-healing ability even in 3.5 wt% NaCl solution, which confirmed that the hydrophobic interaction effectively inhibited the interference of water penetration on the dynamic bond recombination. However, the cracks on the SiEP-SS coating were still obvious and not repaired at room temperature / underwater ( Figure 4 b).
[0032] To verify the long-term protection performance of the coating, an accelerated corrosion experiment was carried out. After 720 h of continuous exposure in a 5 wt% NaCl salt spray environment, no obvious local corrosion expansion occurred on the scratched SiEP-SS / HDES coating, while the corrosion area of the scratched SiEP-SS in the control group expanded significantly ( Figure 5 ).
[0033] In this invention, an epoxy resin network skeleton (SiEP-SS) containing siloxane segments and disulfide cross-linking points is designed as the "stationary phase" of the coating through "host design", and a hydrophobic deep eutectic solvent (HDES) is introduced as the "mobile phase" through "guest introduction", effectively enhancing the hydrophobicity and stability of the coating. It further confirms the excellent multiple-environment autonomous self-healing ability of the SiEP-SS / HDES coating, which has the advantages of rapid and controllable response, diverse application scenarios, etc., and shows great potential in the field of practical engineering applications.
[0034] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A preparation method of a deep eutectic solvent / epoxy resin composite self-healing anti-corrosion coating, characterized in that The steps include: (1) stirring and mixing the hydrogen bond donor and the hydrogen bond acceptor to obtain a hydrophobic deep eutectic solvent; (2) stirring and mixing the siloxane-modified epoxy resin monomer and the curing agent to obtain a siloxane-modified epoxy resin casting solution; (3) adding a hydrophobic low eutectic solvent to the siloxane-modified epoxy resin film casting solution, stirring and mixing to obtain a hydrophobic low eutectic solvent / siloxane-modified epoxy resin coating film casting solution; (4) vacuum degassing the hydrophobic low eutectic solvent / siloxane-modified epoxy resin casting solution; (5) The vacuum degassed casting solution is applied to the protected substrate while hot, solidified, and then taken out and cooled to obtain a coating.
2. The preparation method of a deep eutectic solvent / epoxy resin composite self-healing anti-corrosion coating according to claim 1, characterized in that: In step (1), the hydrogen bond donor includes any one or more of thymol, 1-naphthol, decanoic acid, and lidocaine, and the hydrogen bond acceptor includes any one or more of methyl salicylate, coumarin, menthol, and ibuprofen; and the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is 1:1 to 3:
1.
3. The preparation method of a eutectic solvent / epoxy resin composite self-healing anti-corrosion coating according to claim 1, characterized in that: In step (1), the stirring temperature is 30-90°C and the stirring time is 1-2h.
4. The preparation method of a eutectic solvent / epoxy resin composite self-healing anti-corrosion coating according to claim 1, characterized in that: In step (2), the siloxane-modified epoxy resin monomer is 1,3-bis(3-glycidyloxypropyl)-1,1,3,3-tetramethyldisiloxane; the curing agent is an amine curing agent containing a disulfide bond, including any one or more of 2,2'-diaminodiphenyl disulfide, 4,4'-diaminodiphenyl disulfide and their modified products; the molar ratio of the siloxane-modified epoxy resin monomer to the curing agent is 1:1; and the stirring time is 1-2 hours.
5. The preparation method of a eutectic solvent / epoxy resin composite self-healing anti-corrosion coating according to claim 1, characterized in that: In step (3), the mass fraction of the hydrophobic low eutectic solvent is 30wt%-50wt%, and the stirring time is 1-2h.
6. The preparation method of a deep eutectic solvent / epoxy resin composite self-healing anti-corrosion coating according to claim 1, characterized in that: In step (4), the vacuum degassing temperature is 60-70°C, and the vacuum degassing time is 15-30 min.
7. The preparation method of a eutectic solvent / epoxy resin composite self-healing anti-corrosion coating according to claim 1, characterized in that: In step (5), the coating method is preheating spraying, brushing, pouring or dipping; the curing time corresponds to the curing temperature, the curing temperature is 80-120°C, and the curing time is 4-12h.
8. A low eutectic solvent / epoxy resin composite self-repairing anti-corrosion coating, which is prepared by the preparation method according to any one of claims 1 to 7.