Intelligent epoxy anticorrosive coating based on dual-mode early warning and preparation method thereof

Abstract

The application belongs to the field of marine corrosion protection and intelligent coating, and relates to an intelligent epoxy resin anticorrosive coating based on a dual-mode early warning and a preparation method. The coating is prepared by modifying epoxy resin (E44) and polypropylene glycol diglycidyl ether (PPGDGE) with 1,10-phenanthroline-5-amino (APhen), and then curing and cross-linking the two epoxy resin prepolymers with polyetheramine (D400) to obtain an epoxy resin anticorrosive coating with a pre-warning function. 2+ Due to the introduction of APhen, the prepared epoxy resin anticorrosive coating has fluorescence performance, can be complexed with Fe 2+ , and obvious visual coloration occurs. With the increase of the concentration of Fe , fluorescence quenching occurs. These two characteristics endow the system with a pre-warning function for local corrosion of a metal substrate. Meanwhile, the intelligent epoxy resin coating prepared based on the interpenetrating network has excellent mechanical properties and wide market prospects. The steps are simple, the operation is convenient, and the practicality is strong.

Description

Technical Field

[0001] This invention relates to a smart epoxy resin coating that can be used in the field of marine corrosion protection, and particularly to a smart epoxy resin anti-corrosion coating with dual modes of visual color development and fluorescence quenching, and its preparation method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Metal corrosion is arguably one of the major challenges facing society, especially in the harsh marine environment. This globally significant issue is not merely an industrial problem, but is also closely related to energy, safety, the environment, and the economy. For example, it severely impacts the development of industries such as storage tanks and petrochemicals; it reduces the thermal and electrical conductivity of metal materials, leading to energy waste; it weakens the cohesion of metal materials, causing equipment failure or collapse, and consequently, safety accidents; pollutants generated during corrosion pollute the ecological environment; and it damages metal materials, shortening their service life and increasing maintenance costs.

[0004] To minimize corrosion and protect metal equipment, various corrosion protection measures have been adopted. These mainly include applying organic coatings, adding corrosion inhibitors, modifying the corrosive medium, and electrochemical protection. Among these protective methods, organic coatings have attracted much attention due to their low cost, simple processing, and excellent mechanical properties, making them the most widely used and economical and effective protective method. However, traditional organic anti-corrosion coatings inevitably develop defects or suffer other damage during long-term service. These defects or minor damage can then become channels for corrosive substances to penetrate the metal substrate, causing localized corrosion in harsh environments. If this phenomenon is not detected in time and continues to develop, it may cause more serious damage to the metal substrate, such as pitting and cracking, ultimately leading to complete coating failure and loss of protective capability.

[0005] Therefore, detecting and preventing localized corrosion of metal substrates is extremely important. For example, methods such as ultrasonic testing, electromagnetic sensors, and X-ray imaging can be used to detect and prevent localized corrosion of coatings. However, these methods are technically demanding and costly, making them unsuitable for widespread use in various fields. Currently, some researchers have used microcapsules containing pH-sensitive agents, color developers, and phosphors to predict localized damage to the coating substrate, providing a warning effect. However, the inventors have found that the feasibility of current smart coatings is limited, and most only provide early warnings about the coating substrate rather than visual information about corrosion of the metal substrate. Patent CN108485496A discloses a self-detection anti-corrosion coating containing a nanocarrier, which adds 1,10-phenanthroline-5-amino as a color developer to an aqueous epoxy resin, reacting with metal ions to produce a color reaction. However, since 1,10-phenanthroline-5-amino is directly added to the resin, the durability, stability and film uniformity of the coating's warning effect are easily affected by the complex and severe marine environment, causing the release or leaching of 1,10-phenanthroline-5-amino, which leads to the failure of the coating's warning function. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a smart epoxy resin anticorrosion coating with dual-mode early warning capability and its preparation method. Using epoxy resin (E44), polypropylene glycol diglycidyl ether (PPGDGE), and 1,10-phenanthroline-5-amino (APhen) as raw materials, two epoxy resin prepolymers (EAPhen and PAPhen) with early warning capabilities were synthesized. Simultaneously, polyetheramine (D400) was used as a curing agent for crosslinking, thereby obtaining a dual-mode early warning epoxy resin anticorrosion coating with excellent mechanical properties and high adhesion.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a smart epoxy resin anti-corrosion coating based on dual-mode early warning, comprising:

[0009] Epoxy resin and polypropylene glycol diglycidyl ether were modified with 1,10-phenanthroline-5-amino to obtain a first epoxy resin prepolymer and a second epoxy resin prepolymer.

[0010] The first epoxy resin prepolymer, the second epoxy resin prepolymer, and the curing agent are mixed evenly and reacted to obtain an intelligent epoxy resin anti-corrosion coating based on dual-mode early warning.

[0011] This invention modifies epoxy resin (E44) and polypropylene glycol diglycidyl ether (PPGDGE) with 1,10-phenanthroline-5-amino (APhen), and then crosslinks the two epoxy resin prepolymers with polyetheramine (D400) to obtain an epoxy resin anticorrosive coating with early warning function. Due to the introduction of APhen, the prepared epoxy resin anticorrosive coating exhibits fluorescent properties and can also react with Fe... 2+ A complexation reaction occurs, resulting in a relatively obvious visual color change, as Fe... 2+ Increased concentration leads to fluorescence quenching. These two properties endow the system with an early warning function for localized corrosion of metal substrates. Simultaneously, the synergistic effect between epoxy resin (E44) and polypropylene glycol diglycidyl ether (PPGDGE) gives the epoxy resin anti-corrosion coating a combination of rigidity and flexibility.

[0012] In some embodiments, the molar ratio of epoxy group to amino group is 0.5–2:0.5–2. The nitrogen atom in the 1,10-phenanthroline-5-amino (APhen) molecule can react with Fe... 2+ A simple complexation reaction occurs, giving the epoxy resin anti-corrosion coating a dual-mode early warning mechanism.

[0013] In some embodiments, the specific steps of the 1,10-phenanthroline-5-amino modified epoxy resin include: dissolving 1,10-phenanthroline-5-amino in N,N-dimethylacetamide under heating and ultrasonic conditions, then adding epoxy resin, and heating in an oil bath to obtain a first epoxy resin prepolymer.

[0014] In some embodiments, the reaction temperature of the 1,10-phenanthroline-5-amino with the epoxy resin is 50–150°C.

[0015] In some embodiments, the specific steps of the 1,10-phenanthroline-5-amino modified polypropylene glycol diglycidyl ether include: dissolving 1,10-phenanthroline-5-amino in N,N-dimethylacetamide under heating and ultrasonic conditions, then adding polypropylene glycol diglycidyl ether, and heating in an oil bath to obtain a second epoxy resin prepolymer.

[0016] In some embodiments, the reaction temperature of the 1,10-phenanthroline-5-amino with polypropylene glycol diglycidyl ether is 50–150°C.

[0017] In some embodiments, the curing agent is polyetheramine.

[0018] In some embodiments, the molar ratio of 1,10-phenanthroline-5-amino to the curing agent is 1–15:85–99. Polyetheramine (D400) is added to the two prepolymer solutions to obtain a cross-linked, cured three-dimensional network structure.

[0019] A second aspect of this invention provides a smart epoxy resin anti-corrosion coating based on dual-mode early warning, prepared by the above-described method. The preparation method of the smart epoxy resin anti-corrosion coating of this invention is simple and novel, possesses good mechanical properties and high substrate adhesion, and has profound research value.

[0020] A third aspect of the present invention provides the application of the above-mentioned intelligent epoxy resin anti-corrosion coating based on dual-mode early warning in the fields of construction, shipbuilding, and automobiles.

[0021] Beneficial effects of the present invention

[0022] (1) Based on the design of the interpenetrating network structure, the present invention endows the system with excellent mechanical properties, maintains the mechanical strength of epoxy resin, and at the same time makes up for its brittleness and poor toughness, thus achieving the best of both worlds.

[0023] (2) The preparation process of the present invention, due to the introduction of APhen and the easy occurrence of complexation reaction, endows the epoxy resin anti-corrosion coating with the function of visual color development and fluorescence quenching dual-mode early warning. At the same time, the system also has good barrier performance against corrosive substances, that is, it has excellent anti-corrosion effect.

[0024] (3) Compared with directly adding 1,10-phenanthroline-5-amino to the resin, the APhen-modified epoxy resin of this invention is not affected by release or leaching caused by complex and harsh marine environments, which could lead to the failure of the coating's early warning effect. This invention can provide a more stable and durable modification effect. Secondly, the corrosion resistance of this invention is better than that of direct addition, mainly due to the poor stability of direct addition. Finally, the compatibility is better than that of direct addition, resulting in better film-forming properties of the coating. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. Exemplary embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Figure 1 The image shows the fluorescence spectrum of the epoxy resin anti-corrosion coating in Example 1 and a physical image of its blue-green fluorescence under 365nm ultraviolet light irradiation.

[0027] Figure 2 The epoxy resin anti-corrosion coating in Example 1 and Fe 2+ Fluorescence quenching and visual color development phenomena before and after complexation.

[0028] Figure 3 The Bode plot of the epoxy resin anti-corrosion coating in Example 1 is used to characterize the anti-corrosion performance of the coating. Detailed Implementation

[0029] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0030] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0031] Example 1

[0032] 3.49 g of epoxy resin (E44) and polypropylene glycol diglycidyl ether (PPGDGE) were dissolved in N,N-dimethylacetamide (DMAC) by ultrasonication with 0.06 g of 1,10-phenanthroline-5-amino (APhen). The solutions were then placed in a 100 ml three-necked flask, which was equipped with a condenser, thermometer, and stirrer. The flask was then placed in an oil bath at 130 °C and stirred vigorously for 3 hours. After the reaction was completed, the solution was cooled to room temperature to obtain the modified epoxy resin prepolymer.

[0033] The reaction solution was then placed in a beaker and transferred to a magnetic stirrer. 2.94 g of polyetheramine (D400) was added, and the mixture was magnetically stirred at room temperature for 0.5 hours. The mixture was then poured into a mold and coated onto a substrate. The mixture was then placed in an 80°C oven to cure and crosslink, resulting in an epoxy resin anti-corrosion coating.

[0034] Example 2

[0035] 2.33 g of epoxy resin (E44) and 0.04 g of 1,10-phenanthroline-5-amino (APhen) and 4.66 g of polypropylene glycol diglycidyl ether (PPGDGE) and 0.08 g of 1,10-phenanthroline-5-amino (APhen) were ultrasonically dissolved in N,N-dimethylacetamide (DMAC). The mixture was then placed in a 100 ml three-necked flask, which was connected to a condenser, thermometer, and stirrer. The flask was then placed in an oil bath at 130 °C and stirred vigorously for 3 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain the modified epoxy resin prepolymer.

[0036] The reaction solution was then placed in a beaker and transferred to a magnetic stirrer. 2.94 g of polyetheramine (D400) was added, and the mixture was magnetically stirred at room temperature for 0.5 hours. The mixture was then poured into a mold and coated onto a substrate. The mixture was then placed in an 80°C oven to cure and crosslink, resulting in an epoxy resin anti-corrosion coating.

[0037] Example 3

[0038] 4.66 g of epoxy resin (E44) and 0.08 g of 1,10-phenanthroline-5-amino (APhen) and 2.33 g of polypropylene glycol diglycidyl ether (PPGDGE) and 0.04 g of 1,10-phenanthroline-5-amino (APhen) were ultrasonically dissolved in N,N-dimethylacetamide (DMAC). The mixture was then placed in a 100 ml three-necked flask, which was connected to a condenser, thermometer, and stirrer. The flask was then placed in an oil bath at 130 °C and stirred vigorously for 3 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain the modified epoxy resin prepolymer.

[0039] The reaction solution was then placed in a beaker and transferred to a magnetic stirrer. 2.94 g of polyetheramine (D400) was added, and the mixture was magnetically stirred at room temperature for 0.5 hours. The mixture was then poured into a mold and coated onto a substrate. The mixture was then placed in an 80°C oven to cure and crosslink, resulting in an epoxy resin anti-corrosion coating.

[0040] Example 4

[0041] 5.2 g of epoxy resin (E44) and 0.09 g of 1,10-phenanthroline-5-amino (APhen), along with 1.75 g of polypropylene glycol diglycidyl ether (PPGDGE) and 0.03 g of 1,10-phenanthroline-5-amino (APhen), were ultrasonically dissolved in N,N-dimethylacetamide (DMAC). The solution was then placed in a 100 ml three-necked flask, which was connected to a condenser, thermometer, and stirrer. The flask was then placed in an oil bath at 130 °C and stirred vigorously for 3 hours. After the reaction was completed, the solution was cooled to room temperature to obtain the modified epoxy resin prepolymer.

[0042] The reaction solution was then placed in a beaker and transferred to a magnetic stirrer. 2.94 g of polyetheramine (D400) was added, and the mixture was magnetically stirred at room temperature for 0.5 hours. The mixture was then poured into a mold and coated onto a substrate. The mixture was then placed in an 80°C oven to cure and crosslink, resulting in an epoxy resin anti-corrosion coating.

[0043] Comparative Example 1

[0044] 3.49 g of polypropylene glycol diglycidyl ether (PPGDGE) and 0.06 g of 1,10-phenanthroline-5-amino (APhen) were ultrasonically dissolved in N,N-dimethylacetamide (DMAC), and then placed in a 100 ml three-necked flask. A condenser, thermometer, and stirrer were attached, and the flask was then placed in an oil bath at 130 °C and stirred vigorously for 3 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain the modified epoxy resin prepolymer.

[0045] The reaction solution was then placed in a beaker and transferred to a magnetic stirrer. 2.94 g of polyetheramine (D400) was added, and the mixture was magnetically stirred at room temperature for 0.5 hours. The mixture was then poured into a mold and coated onto a substrate. The mixture was then placed in an 80°C oven to cure and crosslink, resulting in an epoxy resin anti-corrosion coating.

[0046] Comparative Example 2

[0047] 2.33 g of epoxy resin (E44) and 4.66 g of polypropylene glycol diglycidyl ether (PPGDGE) were ultrasonically dissolved in N,N-dimethylacetamide (DMAC), followed by the addition of 2.94 g of polyetheramine (D400). The mixture was magnetically stirred at room temperature for 0.5 hours. Then, 1,10-phenanthroline-5-amino was directly added to the anti-corrosion coating as a colorant. The mixture was then poured into a mold and coated onto a substrate. Finally, it was cured and cross-linked in an oven at 80°C to obtain the epoxy resin anti-corrosion coating.

[0048] The fluorescence properties, color development, and anti-corrosion performance of the epoxy resin anti-corrosion coating prepared in Example 1 were tested, and the test results are as follows: Figure 1 , Figure 2 As shown.

[0049] Depend on Figure 1 It can be seen that the epoxy resin anti-corrosion coating prepared in Example 1 has photoluminescence characteristics at an excitation wavelength of 365nm, emitting blue-green fluorescence.

[0050] Depend on Figure 2 It can be seen that by preparing a 5 w / v% FeCl2˙4H2O DMAC solution and then adding this solution in different amounts (0 μL, 20 μL, 40 μL, 60 μL, 80 μL, 100 μL, 120 μL, 140 μL, 160 μL, 180 μL, 200 μL) to an epoxy resin anticorrosive solution, the effect of epoxy resin anticorrosive coatings on Fe can be studied. 2+ The fluorescence quenching and visual color development phenomena that occur during this time, without the addition of Fe 2+ At that time, under 365nm ultraviolet light irradiation, the coating exhibited a light green fluorescence. With Fe... 2+ As the amount added increases, the fluorescence intensity gradually decreases, while when Fe... 2+ When added to a concentration of 200 μL or higher, under the same irradiation conditions, the coating exhibits a phenomenon where the fluorescence effect is turned off (the area within the white dashed ellipse represents the concentrations of APhen and Fe in the coating). 2+ (This is due to the disappearance of fluorescence after the complexation reaction). Meanwhile, no Fe was added. 2+ At that time, the coating solution was light yellow, but as Fe... 2+ As the concentration increases, the solution gradually turns red.

[0051] Depend on Figure 3It can be seen that the epoxy resin anticorrosive coating prepared in Example 1 has |Z| 0.01Hz The value is as high as 1.99 × 10 11 Ω˙cm 2 This is mainly due to the fact that using APhen modified epoxy resin as the substrate for the coating can form a passivation layer on the substrate surface, which hinders the direct contact between the corrosive medium and the substrate, thereby reducing the risk of corrosion.

[0052] The mechanical strength, elongation at break, hardness, and adhesion of the epoxy resin anticorrosive coatings prepared in Examples 1-4 and Comparative Examples 1-2 were tested, and the results are shown in Table 1.

[0053] Table 1. Performance test results of the examples and comparative examples.

[0054]

[0055]

[0056] The stress-strain of the epoxy resin anticorrosive coating was tested according to GB / T 1731-2020 to obtain the mechanical strength and elongation at break of the coating. The hardness of the epoxy resin anticorrosive coating was tested using a GS-702N(TYPE D) Shore hardness tester. Samples were prepared into films with a thickness of 6-7 mm, and 10 measurements were taken, with the average value recorded. The adhesion of the epoxy resin anticorrosive coating was evaluated using the cross-cut adhesion test according to ASTM D 3359-09.

[0057] A comparison of Examples 1-4 and Comparative Example 1 shows that the epoxy resin anticorrosion coatings prepared in Examples 1-4 have significantly higher mechanical strength and hardness than the epoxy resin anticorrosion coating prepared in Comparative Example 1. Furthermore, the elongation at break of the epoxy resin anticorrosion coatings prepared in Examples 1-4 is mostly superior to that of Comparative Example 1. This is mainly attributed to the synergistic effect between the two modified epoxy resin prepolymers. Based on the strategy of "rigid when encountering hard materials and flexible when encountering soft materials," the rigid benzene ring structure in the epoxy resin (E44) main chain endows the system with superior mechanical strength and hardness. Simultaneously, the flexible aliphatic long chains in the polypropylene glycol diglycidyl ether (PPGDGE) molecular structure endow the system with flexibility. The mechanical properties of the system are controlled through an interpenetrating network, avoiding complex process design and thus enabling broader application prospects.

[0058] As can be seen from the comparison between Example 2 and Comparative Example 2, the anti-corrosion coating prepared by APhen modified epoxy resin has better mechanical properties.

[0059] Both the coatings prepared in Example 2 and Comparative Example 2 were simultaneously immersed in seawater. The effective duration of the early warning effect of the coating in Example 2 was significantly longer than that of the coating in Comparative Example 2. Meanwhile, with prolonged immersion time, the amount of APhen in the coating of Comparative Example 2 decreased, resulting in a more pronounced weakening trend in fluorescence intensity, making it impossible to distinguish whether the fluorescence quenching was caused by localized corrosion or by the precipitation of this substance. In contrast, the fluorescence intensity of the coating in Example 2 showed a slow weakening trend during this period, providing an early warning function.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an intelligent epoxy resin anti-corrosion coating based on dual-mode early warning, characterized in that, include: (1) Epoxy resin E44 and polypropylene glycol diglycidyl ether were modified with 1,10-phenanthroline-5-amino to obtain a first epoxy resin prepolymer and a second epoxy resin prepolymer. The specific steps of the 1,10-phenanthroline-5-amino modified epoxy resin include: dissolving 1,10-phenanthroline-5-amino in N,N-dimethylacetamide under heating and ultrasonic conditions, then adding epoxy resin, and heating in an oil bath to obtain the first epoxy resin prepolymer. The specific steps of the 1,10-phenanthroline-5-amino modified polypropylene glycol diglycidyl ether include: dissolving 1,10-phenanthroline-5-amino in N,N-dimethylacetamide under heating and ultrasonic conditions, then adding polypropylene glycol diglycidyl ether, and heating in an oil bath to obtain a second epoxy resin prepolymer. (2) The first epoxy resin prepolymer, the second epoxy resin prepolymer and the curing agent are mixed evenly and reacted to obtain a smart epoxy resin anti-corrosion coating based on dual-mode early warning. The curing agent is polyetheramine; The molar ratio of 1,10-phenanthroline-5-amino to the curing agent is 1~15:85~99.

2. The preparation method of the intelligent epoxy resin anti-corrosion coating based on dual-mode early warning as described in claim 1, characterized in that, The reaction temperature of the 1,10-phenanthroline-5-amino with the epoxy resin is 50~150℃.

3. The preparation method of the intelligent epoxy resin anti-corrosion coating based on dual-mode early warning as described in claim 1, characterized in that, The reaction temperature of the 1,10-phenanthroline-5-amino with polypropylene glycol diglycidyl ether is 50~150℃.

4. The intelligent epoxy resin anti-corrosion coating based on dual-mode early warning prepared by the method according to any one of claims 1-3.

5. The application of the intelligent epoxy resin anti-corrosion coating based on dual-mode early warning as described in claim 4 in the fields of construction, shipbuilding, and automobiles.

Images