A self-healing and self-early warning protective coating material, coating, preparation method thereof, and repair method for damaged coating.

Abstract

This application provides a self-healing and self-early warning protective coating material, the coating itself, its preparation method, and a method for repairing damaged coatings, relating to the field of corrosion protection. The raw materials for the self-healing and self-early warning protective coating material include: diisocyanate, long-chain diamine, and curcumin-like substances; the molar ratio of diisocyanate to the sum of the amounts of long-chain diamine and curcumin-like substances is 1-1.15:1; the molar ratio of long-chain diamine to curcumin-like substances is 10-20:1. The preparation method includes: mixing diisocyanate and long-chain diamine under a protective atmosphere and heating to carry out a first reaction under the action of a catalyst; then adding curcumin-like substances and heating to carry out a second reaction; and finally, post-treatment to obtain the self-healing and self-early warning protective coating material. The self-healing and self-early warning protective coating material provided by this application has curcumin-like substances with intrinsic fluorescence properties; minor mechanical damage will cause a change in its fluorescence intensity, achieving early warning of mechanical damage.

Description

Technical Field

[0001] This application relates to the field of corrosion protection, and in particular to a self-healing and self-early warning protective coating material, the coating and its preparation method, and a method for repairing damaged coatings. Background Technology

[0002] Given the significant economic losses and potential safety risks caused by metal corrosion, developing efficient anti-corrosion technologies has always been a crucial issue in the field of materials protection. Organic anti-corrosion coatings, with their excellent physical barrier properties, are widely used in metal corrosion protection. Polyurethane / polyurea organic coatings, due to the synergistic effect of flexible and hard segments introduced into their main chain, exhibit both high strength and high toughness. However, if the coating is exposed to complex and harsh corrosive environments for extended periods, its protective effectiveness often degrades significantly due to the combined effects of mechanical and corrosive damage.

[0003] Specifically, the reduced rigidity of a coating due to immersion in corrosive media during service significantly weakens its scratch resistance and induces numerous microscopic mechanical damages. These microscopic damages are often difficult to observe and repair directly in their early stages, and are highly susceptible to gradual expansion under external stress, leading to coating failure. Early detection and self-repair of microscopic damage in the coating can significantly extend its service life. Simultaneously, the accumulation and penetration of corrosive media cause corrosion products to form at the coating-metal interface, gradually reducing the adhesion between the coating and the substrate, ultimately leading to coating peeling and exposure of the metal substrate. Real-time response and early warning of environmental changes or damage conditions in the early stages of corrosion allow for timely intervention to inhibit further damage propagation.

[0004] Therefore, there is an urgent need to develop self-healing anti-corrosion coatings with excellent adhesion that combine early warning of corrosion damage and early warning of mechanical damage, so as to extend their service life. Summary of the Invention

[0005] The purpose of this application is to provide a self-healing and self-warning protective coating material, the coating and its preparation method, and a method for repairing damaged coatings, so as to solve the above-mentioned problems.

[0006] To achieve the above objectives, this application adopts the following technical solution: A self-healing and self-early warning protective coating material, the raw materials of which include: diisocyanate, long-chain diamine and curcumin-like substances; The diisocyanate includes isophorone diisocyanate and / or other types of diisocyanate, wherein the other types of diisocyanate include one or more of aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate; The long-chain diamine includes one or more of the following: linear aliphatic long-chain diamine, branched aliphatic long-chain diamine, polyester-type long-chain diamine, and polyether amine; The curcumin-like substances include one or more of curcumin, demethoxycurcumin, and demethoxycurcumin; The molar ratio of the amount of the diisocyanate to the sum of the amounts of the long-chain diamine and the curcuminoid is 1-1.15:1; the molar ratio of the long-chain diamine to the curcuminoid is 10-20:1.

[0007] Preferably, the self-healing and self-warning protective coating material satisfies at least one of the following conditions: (1) The diisocyanate is a mixture of isophorone diisocyanate and the other types of diisocyanates, wherein the isophorone diisocyanate accounts for not less than 60% of the total molar amount of the mixture; (2) The long-chain diamine is a mixture of linear aliphatic long-chain diamine, branched aliphatic long-chain diamine, polyester-type long-chain diamine, and polyetheramine, wherein the polyetheramine accounts for not less than 80% of the total molar amount of the mixture; (3) The average molecular weight of the long-chain diamine is 230 g / mol to 2000 g / mol; (4) The curcumin-like substances are a mixture including curcumin, demethoxycurcumin and demethoxycurcumin, wherein the proportion of curcumin in the total molar amount of the mixture is not less than 80%.

[0008] This application also provides a method for preparing the self-healing and self-early warning protective coating material, comprising: Under a protective atmosphere, the diisocyanate and the long-chain diamine are mixed and heated under the action of a catalyst to carry out the first reaction; Then, the curcumin-like substances are added, heated to carry out a second reaction, and post-processed to obtain the self-healing and self-warning protective coating material.

[0009] Preferably, the preparation method of the self-healing and self-early warning protective coating material satisfies at least one of the following conditions: (1) The diisocyanate, the long-chain diamine, and the curcumin-like substances are each dissolved in a first organic solvent to obtain a corresponding solution. The first organic solvent includes one or more of chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, and tetrahydrofuran. (2) The temperature of the first reaction is 60-70℃ and the time is 1-4h; (3) The temperature of the second reaction is 60-80℃ and the time is 2-4h; (4) The catalyst includes one or more of dibutyltin dilaurate, triethylenediamine, and bismuth neodecanoate; (5) The post-processing includes rotary evaporation, water precipitation and drying performed in sequence.

[0010] This application also provides a self-healing and self-early warning protective coating, the raw materials of which include the aforementioned self-healing and self-early warning protective coating material.

[0011] Preferably, the thickness of the self-healing and self-early warning protective coating is 50-300 μm.

[0012] This application also provides a method for preparing the self-healing and self-early warning protective coating, comprising: The self-healing and self-warning protective coating material is dissolved using a second organic solvent, then applied to the surface of the substrate and cured.

[0013] Preferably, the self-healing and self-warning protective coating satisfies one or more of the following conditions: (1) The second organic solvent includes one or more of N,N-dimethylacetamide, chloroform, and tetrahydrofuran; (2) The curing temperature is 40-80℃ and the time is 1-24h.

[0014] This application also provides a method for repairing a damaged coating, wherein the damaged coating is the self-healing and self-warning protective coating after damage, and the repair method includes: The damaged coating is heated or left at room temperature for a period of time.

[0015] Preferably, the damaged coating repair method satisfies one or more of the following conditions: (1) The heating temperature of the damaged coating is 50-80℃ and the time is 10-60min; (2) The room temperature is 25-30℃ and the placement time is 6h-24h.

[0016] Compared with the prior art, the beneficial effects of this application include: The self-healing and self-early warning protective coating and material provided in this application possess an aliphatic long-chain diamine long-chain structure, a di- or polyphenolic hydroxyl structure, and a carbamate or urea group structure formed between these two structural monomers and isocyanates. The aliphatic long-chain diamine long-chain structure, with its high chemical stability, provides the coating with excellent elasticity and toughness. The phenolic hydroxyl groups of curcumin and its derivatives form hydrogen bonds, coordination bonds, and van der Waals forces with the metal substrate surface, synergistically enhancing adhesion. Simultaneously, the phenolic hydroxyl structure undergoes electronic structure changes under the localized alkaline environment generated in the metal corrosion cathode region, and the β-diketone structure undergoes coordination reactions with various corrosion-generated metal cations. This results in significant color changes and fluorescence intensity changes, giving it corrosion sensing potential. The dynamic hydrogen bonding between the carbamate or urea groups provides excellent self-healing properties, enabling the healing and repair of scratched areas of the coating after brief heating or a period of time at room temperature. Furthermore, curcumin and its derivatives possess natural intrinsic fluorescence, allowing for early warning of both corrosion damage and minor mechanical damage. This corrosion-protective coating integrates excellent adhesion, self-healing, and self-warning functions, which can effectively extend the protection life.

[0017] The materials and preparation method of the excellent adhesion self-healing and self-early warning protective coating provided in this application have a simple preparation process. The resulting coating has strong adhesion, good self-healing performance, early warning capability for corrosion and mechanical damage, and good anti-corrosion capability, and has broad application prospects.

[0018] The method for repairing damaged coatings provided in this application is simple to operate, highly efficient and effective, and widely applicable. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0020] Figure 1 The infrared spectrum of the polymer resin prepared in Example 1; Figure 2 This study compares the adhesion performance of the polymer coating containing curcumin and its derivatives in Example 2 and the polymer coating without curcumin and its derivatives in Comparative Example 1 on magnesium sheets, carbon steel, glass sheets, and aluminum sheets. Figure 3Comparison of optical images before and after scratch repair for polymer coatings containing curcumin and its derivatives in Example 3, polymer coatings without curcumin and its derivatives in Comparative Example 2, polyurethane coatings containing curcumin and its derivatives in Comparative Example 3, rigid polyurea coatings containing curcumin and its derivatives in Comparative Example 4, and polysiloxane-polyurea copolymer coatings containing curcumin and its derivatives in Comparative Example 5. Figure 4 The corrosion warning performance and repair effect of the polymer coating with curcumin and its derivatives added in Example 4 and the polymer coating without curcumin and its derivatives in Comparative Example 6 were compared in an environmental test device placed in an artificial climate simulation environment. Figure 5 The graph shows a comparison of the mechanical damage warning performance after scratching between the polymer coating with curcumin and its derivatives added in Example 5 and the polymer coating without curcumin and its derivatives in Comparative Example 7. Detailed Implementation

[0021] To better illustrate the technical solution provided in this application, the technical solution will be described in its entirety before the embodiments, as follows: A self-healing and self-early warning protective coating material, the raw materials of which include: diisocyanate, long-chain diamine and curcumin-like substances; The diisocyanate includes isophorone diisocyanate and / or other types of diisocyanate, wherein the other types of diisocyanate include one or more of aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate; The long-chain diamine includes one or more of the following: linear aliphatic long-chain diamine, branched aliphatic long-chain diamine, polyester-type long-chain diamine, and polyether amine; The curcumin-like substances include one or more of curcumin, demethoxycurcumin, and demethoxycurcumin; The molar ratio of the amount of the diisocyanate to the sum of the amounts of the long-chain diamine and the curcuminoid is 1-1.15:1; the molar ratio of the long-chain diamine to the curcuminoid is 10-20:1.

[0022] Optionally, the molar ratio of the diisocyanate to the sum of the amounts of the long-chain diamine and the curcuminoid can be any value between 1:1, 1.05:1, 1.10:1, 1.15:1, or 1-1.15:1; the molar ratio of the long-chain diamine to the curcuminoid can be any value between 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, or 10-20:1.

[0023] In an optional implementation, the self-healing and self-warning protective coating material satisfies at least one of the following conditions: (1) The diisocyanate is a mixture of isophorone diisocyanate and the other types of diisocyanates, wherein the isophorone diisocyanate accounts for not less than 60% of the total molar amount of the mixture; Optionally, the proportion of the isophorone diisocyanate to the total molar amount of the diisocyanate can be any value of 60%, 70%, 80%, 90%, 95% or not less than 60%. (2) The long-chain diamine is a mixture of linear aliphatic long-chain diamine, branched aliphatic long-chain diamine, polyester-type long-chain diamine, and polyetheramine, wherein the polyetheramine accounts for not less than 80% of the total molar amount of the mixture; Optionally, the proportion of the polyetheramine to the total molar amount of the aliphatic long-chain diamine can be any value of 80%, 85%, 90%, 95%, or not less than 80%. (3) The average molecular weight of the long-chain diamine is 230 g / mol to 2000 g / mol; Optionally, the average molecular weight of the long-chain diamine can be any value between 230 g / mol, 300 g / mol, 500 g / mol, 1000 g / mol, 1500 g / mol, 2000 g / mol, or 230 g / mol-2000 g / mol. (4) The curcumin-like substances are a mixture including curcumin, demethoxycurcumin and demethoxycurcumin, wherein the proportion of curcumin in the total molar amount of the mixture is not less than 80%.

[0024] Optionally, the proportion of curcumin to the total molar amount of curcumin and its derivatives can be any value of 80%, 85%, 90%, 95% or not less than 80%. This application also provides a method for preparing the self-healing and self-early warning protective coating material, comprising: Under a protective atmosphere, the diisocyanate and the long-chain diamine are mixed and heated under the action of a catalyst to carry out the first reaction; Then, the curcumin-like substances are added, heated to carry out a second reaction, and post-processed to obtain the self-healing and self-warning protective coating material.

[0025] In an optional embodiment, the method for preparing the self-healing and self-warning protective coating material satisfies at least one of the following conditions: (1) The diisocyanate, the long-chain diamine, and the curcumin-like substances are each dissolved in a first organic solvent to obtain a corresponding solution. The first organic solvent includes one or more of chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, and tetrahydrofuran. (2) The temperature of the first reaction is 60-70℃ and the time is 1-4h; Optionally, the temperature of the first reaction can be any value between 60°C, 65°C, 70°C or 60-70°C, and the time can be any value between 1h, 2h, 3h, 4h or 1-4h. (3) The temperature of the second reaction is 60-80℃ and the time is 2-4h; Optionally, the temperature of the second reaction can be any value between 60°C, 70°C, 80°C or 60-80°C, and the time can be any value between 2h, 3h, 4h or 2-4h. (4) The catalyst includes one or more of dibutyltin dilaurate, triethylenediamine, and bismuth neodecanoate; (5) The post-processing includes rotary evaporation, water precipitation and drying performed in sequence.

[0026] This application also provides a self-healing and self-early warning protective coating, the raw materials of which include the aforementioned self-healing and self-early warning protective coating material.

[0027] In one optional embodiment, the thickness of the self-healing and self-warning protective coating is 50-300 μm.

[0028] Optionally, the thickness of the self-healing and self-warning protective coating can be any value between 50μm, 100μm, 150μm, 200μm, 250μm, 300μm or 50-300μm.

[0029] This application also provides a method for preparing the self-healing and self-early warning protective coating, comprising: The self-healing and self-warning protective coating material is dissolved using a second organic solvent, then applied to the surface of the substrate and cured.

[0030] In one optional implementation, the self-healing and self-warning protective coating satisfies one or more of the following conditions: (1) The second organic solvent includes one or more of N,N-dimethylacetamide, chloroform, and tetrahydrofuran; (2) The curing temperature is 40-80℃ and the time is 1-24h.

[0031] Optionally, the curing temperature can be any value between 40℃, 50℃, 60℃, 70℃, 80℃ or 40-80℃, and the time can be any value between 1h, 6h, 12h, 18h, 24h or 1-24h.

[0032] This application also provides a method for repairing a damaged coating, wherein the damaged coating is the self-healing and self-warning protective coating after damage, and the repair method includes: The damaged coating is heated or left at room temperature for a period of time.

[0033] In one optional implementation, the damaged coating repair method satisfies one or more of the following conditions: (1) The heating temperature of the damaged coating is 50-80℃ and the time is 10-60min; Optionally, the heating temperature of the damaged coating can be any value between 50°C, 60°C, 70°C, 80°C or 50-80°C, and the heating time can be any value between 10 min, 20 min, 30 min, 40 min, 50 min, 60 min or 10-60 min.

[0034] (2) The room temperature is 25-30℃ and the placement time is 6h-24h.

[0035] Optionally, the room temperature can be any value between 25℃, 26℃, 27℃, 28℃, 29℃, 30℃ or 25-30℃, and the placement time can be any value between 6h, 12h, 18h, 24h or 6h-24h.

[0036] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0037] Coating adhesion testing methods include: using the pull-out adhesion test to record the maximum pull-out force when the coating peels off.

[0038] The testing equipment includes a pull-off adhesion tester, with a test temperature of 25-35℃ and a constant increase in load at a speed of 0.5 ~ 2.0 mm / min until the coating detaches from the pull-off head.

[0039] Early warning methods for damaged coatings include placing the damaged coating in an environmental test device that simulates artificial climate or in a constant temperature static immersion test device for a period of time.

[0040] The testing equipment includes a salt spray chamber and a salt water immersion device. The testing temperature is 20-35℃ and the time is 10min-24h.

[0041] Example 1 This embodiment provides a self-healing and self-warning protective coating material with excellent adhesion, and its preparation method is as follows: 1. Dissolve 1.0 mmol of isophorone diisocyanate completely in 12 mL of tetrahydrofuran.

[0042] 2. Dissolve 0.75 mmol of polyetheramine D400 (average molecular weight 400 g / mol, purchased from Anhui Zesheng Technology Co., Ltd., Anaiji brand) and 0.2 mmol of polyetheramine D2000 (average molecular weight 2000 g / mol, purchased from Anhui Zesheng Technology Co., Ltd., Anaiji brand) in 12 mL of tetrahydrofuran.

[0043] 3. Under nitrogen protection, the isocyanate solution was gradually added dropwise to the continuously stirred polyetheramine solution. After adding the catalyst dibutyltin dilaurate, the mixture was heated and stirred at 60°C for 3 hours.

[0044] 4. Dissolve 0.05 mmol of curcumin in 10 mL of N,N-dimethylacetamide and gradually add it dropwise to the above solution. Heat and stir at 60°C for 4 h. Obtain a solid polymer resin containing specific natural polyphenol compounds by rotary evaporation, precipitation with excess water, and vacuum heating and drying. This is a self-healing and self-warning protective coating material with excellent adhesion.

[0045] Figure 1 The image shows the infrared spectrum of the polymer resin prepared in Example 1. (The image is not visible at 2230 cm⁻¹.) -1 The presence of an absorption peak nearby indicates that the -NCO group of the isocyanate was completely consumed (1640 cm⁻¹). -1 and 1568cm -1 The formation of the urea group was confirmed by the stretching vibration of the -C=O group and the bending vibration of the -NH group in the urea group, respectively. (1100 cm⁻¹) -1 and 2900cm -1 The bending vibrations attributed to the -CH2 group and the COC group, respectively, confirmed the presence of the polyetheramine backbone, 1230 cm⁻¹. -1 This corresponds to the stretching vibration of the CO (phenolic hydroxyl) group after the synthesis of curcumin and isocyanate. These results demonstrate the successful synthesis of the polymer resin.

[0046] Example 2 This embodiment provides a self-healing and self-warning protective coating material with excellent adhesion, and its preparation method is as follows: 1. Dissolve 1.0 mmol of isophorone diisocyanate completely in 12 mL of chloroform.

[0047] 2. Dissolve 0.725 mmol of decanediamine C10 (molecular weight 172.31 g / mol) completely in 12 mL of chloroform.

[0048] 3. Under nitrogen protection, the isocyanate solution was gradually added dropwise to a continuously stirred linear aliphatic long-chain diamine solution. After adding the catalyst dibutyltin dilaurate, the mixture was heated and stirred at 65°C for 3 hours.

[0049] Dissolve 0.075 mmol of curcumin in 10 mL of N,N-dimethylacetamide and gradually add it dropwise to the above solution. Heat and stir at 65 °C for 3 h. Obtain the polymer resin in solid state by rotary evaporation, precipitation with excess water, and vacuum heating and drying.

[0050] This embodiment also provides a self-healing and self-warning protective coating with excellent adhesion, the preparation method of which is as follows: The polymer resin prepared by dissolving in tetrahydrofuran was adjusted to a suitable viscosity, and then the resin solution was coated onto the surface of pure magnesium substrate, carbon steel substrate, pure aluminum substrate and glass plate using a doctor blade coater. After curing at 50°C for 24 hours, an organic protective coating containing curcumin and its derivatives was obtained with a thickness of 100±5μm.

[0051] Comparative Example 1 Unlike Example 2, curcumin was not added. The relevant experimental parameters were the same as those in Example 2. 1.0 mmol of isophorone diisocyanate and 1.0 mmol of decanediamine C10 (molecular weight 172.31 g / mol) were used for the reaction. After the catalyst was added, the reaction was completed. After the reaction was completed, a solid polymer resin without specific plant polyphenol compounds was obtained by rotary evaporation, precipitation with excess water, and vacuum heating and drying. After adjusting to a suitable viscosity, it was coated onto the surface of pure magnesium substrate, carbon steel substrate, pure aluminum substrate, and glass sheet in the same way. After curing, an organic protective coating without curcumin and its derivatives was obtained with a thickness of 100±5 μm.

[0052] Figure 2 This study compares the adhesion properties of the polymer resin containing curcumin and its derivatives in Example 2 and the polymer resin without curcumin and its derivatives in Comparative Example 1 on pure copper, carbon steel, and epoxy resin sheet substrates. It can be observed that the adhesion of the polymer resin coating containing curcumin and its derivatives is approximately 2 MPa higher than that without curcumin and its derivatives, indicating that the prepared polymer resin with added curcumin and its derivatives exhibits good adhesion to substrates such as metal substrates and glass surfaces.

[0053] Example 3 This embodiment provides a self-healing and self-warning protective coating material with excellent adhesion, and its preparation method is as follows: 1. Dissolve 1 mmol of isophorone diisocyanate and 0.1 mmol of diphenylmethane-4,4'-diisocyanate completely in 12 mL of tetrahydrofuran.

[0054] 2. Dissolve 1.05 mmol of trimethylhexanediamine (molecular weight 158.3 g / mol) completely in 12 mL of tetrahydrofuran.

[0055] 3. Under nitrogen protection, the isocyanate solution was gradually added dropwise to a continuously stirred branched aliphatic long-chain diamine solution. After adding the catalyst dibutyltin dilaurate, the mixture was heated and stirred at 60°C for 4 hours.

[0056] 4. Dissolve 0.05 mmol of demethoxycurcumin in 10 mL of N,N-dimethylacetamide and gradually add it dropwise to the above solution. Heat and stir at 70 °C for 2.5 h. Obtain the polymer resin in solid state by rotary evaporation, precipitation with excess water, and vacuum heating and drying.

[0057] This embodiment also provides a self-healing and self-warning protective coating with excellent adhesion, the preparation method of which is as follows: The polymer resin prepared by dissolving in tetrahydrofuran was adjusted to a suitable viscosity and then coated onto the surface of a low-carbon steel substrate using a doctor blade coater. After curing at 60°C for 18 hours, an organic protective coating containing curcumin and its derivatives was obtained with a thickness of 300±5μm.

[0058] Artificial scratches 3 cm long and 50 μm wide were applied to the surface of the prepared coating using a scalpel, and the damaged coating was repaired at room temperature for 12 hours at 25°C.

[0059] Figure 3 Image (a) in Example 3 shows a comparison of optical images before and after the repair of scratches on the organic protective coating containing curcumin and its derivatives. It can be seen that the scratches on the coating almost completely disappeared after repair, indicating that the prepared organic protective coating containing curcumin and its derivatives has good self-healing properties.

[0060] Comparative Example 2 Unlike Example 3, demethoxycurcumin was not added. The experimental parameters were the same as in Example 3. A mixture of 1.0 mmol isophorone diisocyanate, 0.1 mmol diphenylmethane-4,4'-diisocyanate, and 1.1 mmol trimethylhexanediamine (molecular weight 158.3 g / mol) was used for the reaction. After the catalyst was added, the reaction was completed. The resulting solid polymer resin, free of curcumin and its derivatives, was obtained by rotary evaporation, precipitation with excess water, and vacuum heating and drying. The polymer resin was dissolved in tetrahydrofuran, and after adjusting to a suitable viscosity, the resin solution was coated onto a low-carbon steel substrate using a doctor blade coater. The coating was cured at 60°C for 18 hours to obtain an organic protective coating free of curcumin and its derivatives, with a thickness of 300 ± 5 μm.

[0061] Artificial scratches 3 cm long and 50 μm wide were applied to the surface of the prepared coating using a scalpel, and the damaged coating was repaired at room temperature for 12 hours at 25°C.

[0062] Figure 3 Image (b) in Comparative Example 2 shows a comparison of optical images before and after the repair of scratches on the organic protective coating that does not contain curcumin or its derivatives. It can be observed that slight traces of the scratch remain on the repaired coating, indicating that the polymer resin containing curcumin and its derivatives can improve the self-healing performance of the coating.

[0063] Comparative Example 3 Unlike Example 3, instead of adding aliphatic long-chain diamine, short-chain polyester polyol was added. The experimental parameters were the same as in Example 3. A mixture of 1.0 mmol isophorone diisocyanate, 0.1 mmol diphenylmethane-4,4'-diisocyanate, and 1.05 mmol 1,4-butanediol BG (molecular weight 90.12 g / mol) was used for the reaction. A catalyst was added to generate a prepolymer, and then demethoxycurcumin was added to continue the reaction. After the reaction was completed, a solid polymer resin containing curcumin and its derivatives was obtained by rotary evaporation, precipitation with excess water, and vacuum heating and drying. The polymer resin prepared by dissolving it in tetrahydrofuran was adjusted to a suitable viscosity, and then the resin solution was coated onto the surface of a low-carbon steel substrate using a doctor blade coater. The coating was cured at 60°C for 18 hours to obtain a polyurethane coating containing curcumin and its derivatives with a thickness of 300±5 μm.

[0064] Artificial scratches 3 cm long and 50 μm wide were applied to the surface of the prepared coating using a scalpel, and the damaged coating was repaired by heating at 25°C for 12 hours.

[0065] Figure 3Image (c) in Comparative Example 3 shows a comparison of optical images before and after the repair of scratches on the polyurethane coating containing curcumin and its derivatives. It can be observed that the scratch marks on the repaired coating are still clearly visible, indicating that the polymer resin coating with added polyester polyol has poor room temperature self-healing ability.

[0066] Comparative Example 4 Unlike Example 3, this time aliphatic short-chain diamine was added instead of dealiphatic long-chain diamine. The relevant experimental parameters were the same as in Example 3. A mixture of 1.0 mmol isophorone diisocyanate, 0.1 mmol diphenylmethane-4,4'-diisocyanate, and 1.05 mmol 1,4-butanediamine (molecular weight 88.15 g / mol) was used to react to obtain a prepolymer. Then, a catalyst was added and demethoxycurcumin was added again to continue the reaction. After the reaction was completed, a rigid polyurea resin containing curcumin and its derivatives was obtained in a solid state by rotary evaporation, precipitation with excess water, and vacuum heating and drying. The polymer resin prepared by dissolving it in tetrahydrofuran was adjusted to a suitable viscosity and then coated onto the surface of a low-carbon steel substrate using a doctor blade coater. The coating was cured at 60°C for 18 h to obtain a rigid polyurea coating containing curcumin and its derivatives with a thickness of 300±5 μm.

[0067] Artificial scratches 3 cm long and 50 μm wide were applied to the surface of the prepared coating using a scalpel, and the damaged coating was repaired at room temperature for 12 hours at 25°C.

[0068] Figure 3 Image (d) in Comparative Example 4 shows a comparison of optical images before and after the repair of scratches on the rigid polyurea coating containing curcumin and its derivatives. It can be observed that the scratch marks on the repaired coating are still clearly visible, indicating that the coating with the addition of short-chain aliphatic diamines has poor room-temperature self-healing ability.

[0069] Comparative Example 5 Unlike Example 3, instead of adding aliphatic long-chain diamine, a polysiloxane with dual active functional groups was added. The experimental parameters were the same as in Example 3. A mixture of 1.0 mmol isophorone diisocyanate, 0.1 mmol diphenylmethane-4,4'-diisocyanate, and 1.05 mmol aminopropyl-terminated polydimethylsiloxane (average molecular weight 1000 g / mol) was used for the reaction. After adding a catalyst, demethoxycurcumin was added to continue the reaction. After the reaction was completed, a solid polysiloxane-polyurea copolymer resin containing curcumin and its derivatives was obtained by rotary evaporation, precipitation with excess water, and vacuum heating and drying. The polymer resin prepared by dissolving it in tetrahydrofuran was adjusted to a suitable viscosity, and the resin solution was coated onto the surface of a low-carbon steel substrate using a doctor blade coater. The coating was cured at 60°C for 18 hours to obtain a polysiloxane-polyurea copolymer coating containing curcumin and its derivatives with a thickness of 300 ± 5 μm.

[0070] Artificial scratches 3 cm long and 50 μm wide were applied to the surface of the prepared coating using a scalpel, and the damaged coating was repaired at room temperature for 12 hours at 25°C.

[0071] Figure 3 Image (f) shows a comparison of optical images before and after the repair of scratches on the polysiloxane-polyurea copolymer coating containing curcumin and its derivatives in Comparative Example 5. It can be observed that the scratch marks on the repaired coating are still clearly visible. This indicates that although the coating with polysiloxane end-capped with dual active functional groups contains urea bonds and urethane bonds, the strong hydrogen bond network of the polysiloxane-polyurea copolymer is difficult to dissociate due to its highly microphase separation characteristics. Thermal stimulation is required to activate chain segment movement, thus it lacks room-temperature self-healing ability.

[0072] Example 4 This embodiment provides a self-healing and self-warning protective coating material with excellent adhesion, and its preparation method is as follows: 1. Dissolve 1.0 mmol of isophorone diisocyanate and 0.15 mmol of dicyclohexylmethane-4,4'-diisocyanate completely in 12 mL of tetrahydrofuran.

[0073] 2. Dissolve 1.1 mmol of 2-methyl-1,5-pentanediamine (average molecular weight 116.2 g / mol) in 12 mL of tetrahydrofuran.

[0074] 3. Under nitrogen protection, the isocyanate solution was gradually added dropwise to the continuously stirred polyester-type long-chain diamine solution. After adding the catalyst dibutyltin dilaurate, the mixture was heated and stirred at 70°C for 1 hour.

[0075] 4. Dissolve 0.05 mmol of curcumin in 10 mL of N,N-dimethylacetamide and gradually add it dropwise to the above solution. Heat and stir at 70 °C for 2 h. Obtain the polymer resin in solid state by rotary evaporation, precipitation with excess water, and vacuum heating and drying.

[0076] This embodiment also provides a self-healing and self-warning protective coating with excellent adhesion, the preparation method of which is as follows: The polymer resin prepared by dissolving in tetrahydrofuran was adjusted to a suitable viscosity and then coated onto the surface of a low-carbon steel substrate using a doctor blade coater. After curing at 80°C for 6 hours, an organic protective coating containing curcumin and its derivatives was obtained with a thickness of 100±5μm.

[0077] The prepared coating was artificially scratched with a 3cm long and 50μm wide cross-shaped incision using a scalpel. The damaged coating was then placed in an environmental test device with artificial climate at 25°C for 30 minutes before being removed.

[0078] Figure 4 Image (a) shows macroscopic photographs taken under sunlight and 365 nm ultraviolet light after an environmental test was conducted on the excellent adhesion self-healing and self-warning protective coating of Experiment 4, following an artificial climate simulation. It can be observed that the coating color changed from yellow to red at the scratched area under sunlight, and the fluorescence intensity at the scratched location darkened under ultraviolet light, indicating that the polymer resin containing curcumin and its derivatives possesses corrosion damage warning properties.

[0079] Figure 4 (c) shows an environmental test conducted under simulated climate conditions after the excellent adhesion self-healing and self-warning protective coating in Experiment 4 was scratched. Scanning electron microscope (SEM) images and Fourier transform infrared (FTIR) tests were performed on the damage warning location. The SEM images show that the scratch disappeared at the damage warning location, and the FTIR spectrum was within the range of 460 cm⁻¹. -1 A new characteristic peak representing the Fe-O coordination bond appeared, indicating that curcumin not only played a corrosion early warning role in environmental experiments with artificially simulated climates, but also interacted with Fe... 3+ The chelation process generates metal-ligand coordination bonds, which facilitates the diffusion and entanglement of molecular chains on both sides of the fracture surface, accelerating the repair speed and effect.

[0080] Comparative Example 6 Unlike Example 4, no curcumin or its derivatives were added. The experimental parameters were the same as in Example 3. A mixture of 1.0 mmol of isophorone diisocyanate and 0.15 mmol of dicyclohexylmethane-4,4'-diisocyanate, along with 1.15 mmol of 2-methyl-1,5-pentanediamine (average molecular weight 116.2 g / mol), was reacted. A catalyst was added to complete the reaction. After the reaction was complete, a solid polymer resin free of curcumin and its derivatives was obtained by rotary evaporation, precipitation with excess water, and vacuum heating and drying. The polymer resin was dissolved in tetrahydrofuran, and after adjusting to a suitable viscosity, the resin solution was coated onto a low-carbon steel substrate using a doctor blade coater. The coating was cured at 80°C for 6 hours to obtain an organic protective coating free of curcumin and its derivatives, with a thickness of 300 ± 5 μm.

[0081] The prepared coating was artificially scratched with a 3cm long and 50μm wide cross-shaped incision using a scalpel. The damaged coating was then placed in an environmental test device with artificial climate at 25°C for 30 minutes before being removed.

[0082] Figure 4 (b) shows macroscopic photographs taken under sunlight and 365 nm ultraviolet light after the organic protective coating without curcumin and its derivatives in Comparative Example 6 was scratched, following an environmental test under simulated climate conditions. It can be observed that the color and fluorescence intensity of the coating at the scratched area did not change significantly under sunlight and ultraviolet light, indicating that the polymer resin containing curcumin and its derivatives can enable the coating to possess corrosion damage warning properties.

[0083] Figure 4 (d) in the comparison example 6 shows an environmental test conducted under simulated climate conditions after the organic protective coating without curcumin and its derivatives was scratched. Scanning electron microscope images and Fourier transform infrared (FTIR) tests were performed on the damage warning locations. It can be found that the scanning electron microscope images show that the scratches at the damage warning locations still have obvious unrepaired traces, and no new characteristic peaks appeared in the infrared spectrum. This indicates that the addition of curcumin and its derivatives is beneficial to accelerating the repair speed and effect during the coating corrosion process.

[0084] Experimental Example 5 This embodiment provides a self-healing and self-warning protective coating material with excellent adhesion, and its preparation method is as follows: 1. Dissolve 0.9 mmol of isophorone diisocyanate and 0.1 mmol of dicyclohexylmethane-4,4'-diisocyanate completely in 12 mL of tetrahydrofuran.

[0085] 2. Dissolve 0.775 mmol of polyetheramine D400 (average molecular weight 400 g / mol) and 0.2 mmol of polyetheramine D2000 (average molecular weight 2000 g / mol) in 12 mL of tetrahydrofuran.

[0086] 3. Under nitrogen protection, the isocyanate solution was gradually added dropwise to the continuously stirred polyurethane solution. After adding the catalyst dibutyltin dilaurate, the mixture was heated and stirred at 70°C for 1 hour.

[0087] 4. Dissolve 0.025 mmol of curcumin in 10 mL of N,N-dimethylacetamide and gradually add it dropwise to the above solution. Heat and stir at 80 °C for 1 h. Obtain the polymer resin in solid state by rotary evaporation, precipitation with excess water, and vacuum heating and drying.

[0088] This embodiment also provides a self-healing and self-warning protective coating with excellent adhesion, the preparation method of which is as follows: The polymer resin prepared by dissolving in tetrahydrofuran was adjusted to a suitable viscosity and then coated onto the surface of a low-carbon steel substrate using a doctor blade coater. After curing at 50°C for 24 hours, an organic protective coating containing curcumin and its derivatives was obtained with a thickness of 100±5μm.

[0089] The prepared coating was artificially scratched with a cross shape, 3 cm long and 50 μm wide, using a scalpel. The damaged coating was then placed under ultraviolet light at a wavelength of 365 nm to observe its fluorescence. After the coating was repaired, it was placed under ultraviolet light at a wavelength of 365 nm again to observe its fluorescence.

[0090] Figure 5 Image (a) shows a macroscopic photograph taken under 36nm ultraviolet light after scratching the organic protective coating containing curcumin and its derivatives in Experiment 5. It can be observed that the fluorescence intensity at the scratched location of the coating increases under ultraviolet light, and the fluorescence intensity of the repaired coating recovers, indicating that the polymer resin containing curcumin and its derivatives possesses mechanical damage early warning properties.

[0091] Comparative Example 7 Unlike Example 5, no curcumin or its derivatives were added. The experimental parameters were the same as in Example 3. A mixture of 0.9 mmol isophorone diisocyanate and 0.1 mmol dicyclohexylmethane-4,4'-diisocyanate, and a mixture of 0.8 mmol polyetheramine D400 (average molecular weight 400 g / mol) and 0.2 mmol polyetheramine D2000 (average molecular weight 2000 g / mol) were reacted. A catalyst was added to complete the reaction. After the reaction was complete, a solid polymer resin free of curcumin and its derivatives was obtained by rotary evaporation, precipitation with excess water, and vacuum heating and drying. The polymer resin prepared by dissolving it in tetrahydrofuran was adjusted to a suitable viscosity, and the resin solution was coated onto the surface of a low-carbon steel substrate using a doctor blade coater. The coating was cured at 50°C for 24 hours to obtain an organic protective coating free of curcumin and its derivatives, with a thickness of 300 ± 5 μm.

[0092] The prepared coating was artificially scratched with a cross shape, 3 cm long and 50 μm wide, using a scalpel. The damaged coating was then placed under ultraviolet light at a wavelength of 365 nm to observe its fluorescence. After the coating was repaired, it was placed under ultraviolet light at a wavelength of 365 nm again to observe its fluorescence.

[0093] Figure 5 (b) shows a macroscopic photograph taken under 36nm ultraviolet light after scratching the organic protective coating containing curcumin and its derivatives in Comparative Example 7. It can be seen that the fluorescence intensity of the scratched coating and the repaired coating is the same under ultraviolet light, indicating that the polymer resin containing curcumin and its derivatives can enable the coating to have mechanical damage early warning performance.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A self-healing and self-early warning protective coating material, characterized in that, Its raw materials include: diisocyanates, long-chain diamines, and curcumin-like substances; The diisocyanate includes isophorone diisocyanate and / or other types of diisocyanate, wherein the other types of diisocyanate include one or more of aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate; The long-chain diamine includes one or more of the following: linear aliphatic long-chain diamine, branched aliphatic long-chain diamine, polyester-type long-chain diamine, and polyether amine; The curcumin-like substances include one or more of curcumin, demethoxycurcumin, and demethoxycurcumin; The molar ratio of the amount of the diisocyanate to the sum of the amounts of the long-chain diamine and the curcuminoid is 1-1.15:1; the molar ratio of the long-chain diamine to the curcuminoid is 10-20:

1.

2. The self-healing and self-early warning protective coating material according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The diisocyanate is a mixture of isophorone diisocyanate and the other types of diisocyanates, wherein the isophorone diisocyanate accounts for not less than 60% of the total molar amount of the mixture; (2) The long-chain diamine is a mixture of linear aliphatic long-chain diamine, branched aliphatic long-chain diamine, polyester-type long-chain diamine, and polyetheramine, wherein the polyetheramine accounts for not less than 80% of the total molar amount of the mixture; (3) The average molecular weight of the long-chain diamine is 230 g / mol to 2000 g / mol; (4) The curcumin-like substances are a mixture including curcumin, demethoxycurcumin and demethoxycurcumin, wherein the proportion of curcumin in the total molar amount of the mixture is not less than 80%.

3. A method for preparing the self-healing and self-early warning protective coating material according to claim 1 or 2, characterized in that, include: Under a protective atmosphere, the diisocyanate and the long-chain diamine are mixed and heated under the action of a catalyst to carry out the first reaction; Then, the curcumin-like substances are added, heated to carry out a second reaction, and post-processed to obtain the self-healing and self-warning protective coating material.

4. The method for preparing the self-healing and self-early warning protective coating material according to claim 3, characterized in that, At least one of the following conditions must be met: (1) The diisocyanate, the long-chain diamine, and the curcumin-like substances are each dissolved in a first organic solvent to obtain a corresponding solution. The first organic solvent includes one or more of chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, and tetrahydrofuran. (2) The temperature of the first reaction is 60-70℃ and the time is 1-4h; (3) The temperature of the second reaction is 60-80℃ and the time is 2-4h; (4) The catalyst includes one or more of dibutyltin dilaurate, triethylenediamine, and bismuth neodecanoate; (5) The post-processing includes rotary evaporation, water precipitation and drying performed in sequence.

5. A self-healing and self-early warning protective coating, characterized in that, Its raw materials include the self-healing and self-early warning protective coating material as described in claim 1 or 2.

6. The self-healing and self-early warning protective coating according to claim 5, characterized in that, The thickness of the self-healing and self-early warning protective coating is 50-300μm.

7. A method for preparing the self-healing and self-early warning protective coating as described in claim 5 or 6, characterized in that, include: The self-healing and self-warning protective coating material is dissolved using a second organic solvent, then applied to the surface of the substrate and cured.

8. The self-healing and self-early warning protective coating according to claim 7, characterized in that, One or more of the following conditions must be met: (1) The second organic solvent includes one or more of N,N-dimethylacetamide, chloroform, and tetrahydrofuran; (2) The curing temperature is 40-80℃ and the time is 1-24h.

9. A method for repairing damaged coatings, characterized in that, The damaged coating is the self-healing and self-warning protective coating as described in claim 5 or 6 after damage, and the repair method includes: The damaged coating is heated or left at room temperature for a period of time.

10. The method for repairing damaged coatings according to claim 9, characterized in that, One or more of the following conditions must be met: (1) The heating temperature of the damaged coating is 50-80℃ and the time is 10-60min; (2) The room temperature is 25-30℃ and the placement time is 6h-24h.

Images