A quick self-repairing coating based on photothermal effect

Abstract

This invention discloses a rapid self-healing coating based on the photothermal effect. The rapid self-healing coating comprises: a polymer matrix, self-healing microcapsules, and photothermal conversion microcapsules; the mass ratio of the self-healing microcapsules to the photothermal conversion microcapsules is 1:0.1~1.1; the amount of photothermal conversion microcapsules added accounts for 1~10% of the polymer matrix mass; the self-healing microcapsules are prepared by an emulsification-solvent evaporation method, and the photothermal conversion microcapsules are prepared by interfacial polymerization; both types of microcapsules are then modified by adding a mixture of fatty alcohol alkoxy ether and ethylene glycol. This invention, by simultaneously adding self-healing microcapsules and photothermal conversion microcapsules to the coating, utilizes the photothermal effect to increase the local temperature, thereby accelerating the curing reaction of the self-healing agent and achieving rapid self-healing.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and specifically to a rapid self-healing coating based on the photothermal effect. Background Technology

[0002] Coating protection is currently the most widely used corrosion protection method in fields such as construction, aerospace, automotive manufacturing, and petrochemicals. However, coating materials are constantly affected by external forces, and their internal structure and properties are prone to change, leading to the formation of microcracks of varying sizes. The continuous generation and aggregation of these internal microcracks eventually result in macroscopic cracking or damage, significantly impairing the coating's mechanical properties and protective function. Furthermore, these internally generated microcracks are difficult to repair externally using existing methods. To address this issue, self-healing coating materials have emerged.

[0003] Self-healing coatings can automatically detect, identify, and repair damaged areas of materials, thereby restoring their mechanical properties, corrosion resistance, and appearance to a certain extent. Currently, self-healing coating materials are mainly divided into two categories: intrinsic self-healing coatings and exogenous self-healing coatings. Intrinsic self-healing coatings primarily achieve repair through the reversible chemical reaction molecular structure of the polymer material itself or through macromolecular diffusion. Based on the type of reversible chemical reaction, intrinsic self-healing coatings are further divided into reversible non-covalent self-healing (physical type) and reversible covalent self-healing (chemical type). However, intrinsic self-healing coatings have relatively high requirements for the material itself, thus limiting their application scope. Exogenous self-healing coatings mainly utilize certain technical means to encapsulate repair substances and add them to the polymer material. When the polymer is damaged, the repair substance diffuses to the damaged area to repair it. Compared to intrinsic self-healing coatings, exogenous self-healing coatings are becoming increasingly mature, and current research on self-healing methods mainly focuses on this type of method.

[0004] Over the past decade, research on externally assisted self-healing technologies has primarily focused on microencapsulation, hollow fiber, microvascular network, and mesoporous hollow microsphere technologies. Microcapsule-filled self-healing coatings encapsulate the repair agent within microcapsules, which are then combined with a catalyst (or curing agent) that polymerizes the repair agent within a polymer material. When the polymer coating is damaged, creating microcracks, the microcapsules rupture under the influence of the cracks. The encapsulated repair agent flows out under suction and fills the crack interior, reacting with the catalyst (or curing agent) in the matrix material to initiate polymerization, thereby repairing the cracks and restoring the coating's performance to a certain extent. Compared to other externally assisted self-healing technologies, microcapsule technology and microcapsule-composite polymer technology are relatively mature and can meet the needs of industrial production. Furthermore, considering factors such as crack response speed, ease of encapsulation of the repair material, and the preparation process of the composite coating, microcapsule-filled self-healing coatings have higher application value. However, existing microcapsule-filled self-healing coatings have a problem: the curing rate of the self-healing agent is slow after the microcapsules rupture, which affects the self-healing effect. Therefore, it is necessary to develop a fast-healing coating with a fast self-healing rate and excellent corrosion resistance to accelerate the curing reaction of the self-healing agent and achieve rapid self-healing. Summary of the Invention

[0005] In view of the above-mentioned prior art, the purpose of this invention is to provide a rapid self-healing coating based on the photothermal effect. This invention simultaneously adds self-healing microcapsules and photothermal conversion microcapsules to the coating, utilizing the photothermal effect to increase the local temperature, thereby accelerating the curing reaction of the self-healing agent and achieving rapid self-healing.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a rapid self-healing coating based on photothermal effect, the rapid self-healing coating comprising: a polymer matrix, self-healing microcapsules, and photothermal conversion microcapsules;

[0008] The mass ratio of the self-healing microcapsules to the photothermal conversion microcapsules is 1:0.1~1.1; the photothermal conversion microcapsules account for 1~10% of the polymer matrix mass.

[0009] Preferably, the polymer matrix is ​​selected from epoxy resin, polyurethane, or polyacrylate; the self-healing agent contained in the self-healing microcapsule is selected from epoxy resin, polyurethane prepolymer, or acrylate monomer; the particle size of the self-healing microcapsule is 1-20 μm; the photothermal conversion material contained in the photothermal conversion microcapsule is selected from indocyanine green, Prussian blue, or thiadiazole derivatives, and the particle size of the photothermal conversion microcapsule is 1-20 μm.

[0010] Preferably, the self-healing microcapsules are prepared by the following method:

[0011] (1) Dissolve the self-healing reagent in acetone to form an organic phase, dissolve sodium poly(ethylene-co-methacrylic acid) in water to form an aqueous phase, add the organic phase dropwise to the aqueous phase, emulsify under high speed stirring, and then remove acetone by vacuum evaporation to obtain microcapsules;

[0012] (2) Add fatty alcohol alkoxy ether to ethylene glycol to obtain a mixture, add microcapsules and sonicate, and centrifuge to obtain self-healing microcapsules.

[0013] Preferably, in step (1), the mass ratio of the self-healing reagent to acetone is 1:5~10, the mass ratio of sodium poly(ethylene-co-methacrylic acid) to water is 1:10~20, and the mass ratio of the organic phase to the aqueous phase is 1:5~10; the dropping speed is 1~5 mL / min, the temperature of the high-speed stirring is 10~35℃, and the time is 5~30 min; the speed of the high-speed stirring is 400-500 r / min.

[0014] Preferably, in step (2), the mass ratio of ethylene glycol to fatty alcohol alkoxy ether is 10~20:1; the mass ratio of microcapsules to mixture is 1:5~15; and the ultrasonic treatment time is 5~10 min.

[0015] Preferably, the photothermal conversion microcapsules are prepared by the following method:

[0016] (1) The photothermal conversion material is dissolved in dichloromethane to form an organic phase, and polyethyleneimine is dissolved in water to form an aqueous phase. The organic phase is added dropwise to the aqueous phase, and an interfacial polymerization reaction occurs under mechanical stirring to obtain microcapsules.

[0017] (2) Add fatty alcohol alkoxy ether to ethylene glycol to obtain a mixture, add microcapsules and sonicate, and centrifuge to obtain photothermal conversion microcapsules.

[0018] Preferably, in step (1), the photothermal conversion material accounts for 0.1-10% of the mass of dichloromethane, the polyethyleneimine accounts for 1-10% of the mass of water, the mass ratio of the organic phase to the aqueous phase is 1:1-10, the dropping rate is 0.1-10 mL / min, the temperature of the interfacial polymerization reaction is 20-60℃, and the time is 1-24h.

[0019] Preferably, in step (2), the mass ratio of ethylene glycol to fatty alcohol alkoxy ether is 5~15:1; the mass ratio of microcapsules to mixture is 1:10; and the ultrasonic treatment time is 5~10 min.

[0020] Preferably, the rapid self-healing coating is obtained by uniformly mixing a polymer matrix, self-healing microcapsules, and photothermal conversion microcapsules.

[0021] A second aspect of the invention provides the application of rapid self-healing coatings in improving self-healing rate and corrosion resistance.

[0022] Damaged coatings can achieve self-repair when exposed to infrared light at a wavelength of 700-900 nm for more than 30 minutes.

[0023] The beneficial effects of this invention are:

[0024] (1) This invention introduces photothermal conversion microcapsules and utilizes the photothermal effect to increase the local temperature, which can significantly improve the curing rate of the self-healing agent and achieve rapid self-healing. The coating has good corrosion resistance and weather resistance and can be widely used for corrosion protection of substrates such as metals and concrete.

[0025] (2) The self-healing microcapsules and photothermal conversion microcapsules of the present invention are prepared by emulsification-solvent evaporation method and interfacial polymerization method, and the process is simple and controllable. The coating is compatible with various polymer matrices, pigments, fillers, additives and other common coating components, and has good versatility. Attached Figure Description

[0026] Figure 1 Infrared spectrum of self-healing microcapsules;

[0027] Figure 2 Infrared spectrum of photothermal conversion microcapsules;

[0028] Figure 3 Electron micrographs of the scratch morphology before (A) and after (B) repair of the self-healing coating prepared in Example 1. Detailed Implementation

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

[0030] As described in the background section, existing microcapsule-filled self-healing coatings have a problem: the curing rate of the self-healing agent is slow after the microcapsules rupture, which affects the self-healing effect.

[0031] Based on this, the purpose of this invention is to provide a rapid self-healing coating based on the photothermal effect. The rapid self-healing coating of this invention contains self-healing microcapsules and photothermal conversion microcapsules. The self-healing microcapsules are prepared using an emulsification-solvent evaporation method, while the photothermal conversion microcapsules are prepared using an interfacial polymerization method. Both types of microcapsules are compatible with various polymer matrices, pigments, fillers, additives, and other common coating components, exhibiting good versatility. This invention utilizes the photothermal effect to increase local temperature, thereby accelerating the curing reaction of the self-healing reagent and achieving rapid self-healing. The raw materials and methods for synthesizing the wall material of this invention are simple, environmentally friendly, and easily scaled up and controlled. The photothermal conversion material and the self-healing reagent are encapsulated inside the microcapsules. When the material ruptures, the microcapsules rupture, releasing the internal material. Research has shown that treating the self-healing microcapsules and photothermal conversion microcapsules with ethylene glycol containing fatty alcohol alkoxy ethers before mixing them with the resin matrix significantly improves the dispersibility of the microcapsules in the resin, reducing the likelihood of microcapsule aggregation. This further enhances the repair effect of the rapid self-healing coating.

[0032] To enable those skilled in the art to better understand the technical solution of this application, the technical solution of this application will be described in detail below with reference to specific embodiments.

[0033] Unless otherwise specified, all water used in this invention is distilled water.

[0034] The test materials used in the embodiments of this invention are all conventional test materials in the art and can be purchased through commercial channels.

[0035] Example 1

[0036] (1) Preparation of self-healing microcapsules: 10g of epoxy resin E51 was dissolved in 75g of acetone to form an organic phase. 10g of sodium poly(ethylene-co-methacrylate) (CAS: 25608-26-8) was dissolved in 150g of distilled water to form an aqueous phase. 10g of the organic phase was slowly added dropwise to 75g of the aqueous phase at a rate of 5mL / min, and stirred at high speed (500r / min) at room temperature (25℃). After the organic phase was added, emulsification continued for 20min. Then, acetone was removed by vacuum evaporation to obtain self-healing microcapsules with a diameter of 1-20μm. The infrared spectrum of the self-healing microcapsules is shown in [reference needed]. Figure 1 .

[0037] (2) Preparation of photothermal conversion microcapsules: 0.5 g indocyanine green was dissolved in 10 g dichloromethane to form an organic phase. 5 g polyethyleneimine was dissolved in 100 g distilled water to form an aqueous phase. 10 g of the organic phase was slowly added dropwise to 75 g of the aqueous phase at a rate of 5 mL / min. Interfacial polymerization was carried out at 40 °C for 3 h under mechanical stirring (400 r / min). After the reaction was completed, the microcapsules with a diameter of 1-20 μm were obtained by filtration. The infrared spectrum of the photothermal conversion microcapsules is shown below. Figure 2 .

[0038] (3) First, add 1g of fatty alcohol alkoxy ether to 10g of ethylene glycol and mix well to obtain a mixture. Then add 1.0g of self-healing microcapsules to 10g of the mixture, sonicate for 5min, and centrifuge to obtain modified self-healing microcapsules.

[0039] 1g of fatty alcohol alkoxy ether was added to 10g of ethylene glycol and mixed evenly to obtain a mixture. 0.1g of photothermal conversion microcapsules were added to 1g of the mixture, sonicated for 5min, and centrifuged to obtain modified photothermal conversion microcapsules.

[0040] 1 g of modified self-healing microcapsules, 0.1 g of modified photothermal conversion microcapsules, and 10 g of epoxy resin E44 were mixed and mechanically stirred to obtain a rapid self-healing coating based on the photothermal effect.

[0041] Example 2

[0042] (1) Preparation of self-healing microcapsules: 5g of polyurethane varnish (Chongqing Three Gorges brand, specification S01-1) was dissolved in 50g of acetone to form an organic phase. 5g of sodium poly(ethylene-co-methacrylic acid) was dissolved in 50g of water to form an aqueous phase. 10g of the organic phase was slowly added dropwise to 50g of the aqueous phase at a rate of 3mL / min. The mixture was stirred at high speed (400r / min) at room temperature (25℃), and emulsification was continued for 10min after the organic phase was completely added. Then, the acetone was removed by vacuum evaporation to obtain self-healing microcapsules with a diameter of 1-20μm. The infrared spectrum of the self-healing microcapsules is shown in [reference needed]. Figure 1 .

[0043] (2) Preparation of photothermal conversion microcapsules: 1g of benzo[1,2- c ;4,5- c '] Bis[1,2,5]thiadiazole-4,7-bis(5-(2-ethylhexyl)thiophene (according to "A narrow-bandgap benzobisthiadiazole derivative with high near-infrared photothermal conversion efficiency and robust photostability for cancer therapy") Chemical communicationsThe photothermal conversion microcapsules were synthesized using the method described in (2015, 51, 4223-4226). The organic phase was formed by dissolving 10g of polyethyleneimine in 100g of distilled water. The organic phase was then slowly added dropwise to 25g of the aqueous phase at a rate of 10mL / min. Interfacial polymerization was carried out at 60℃ for 1.5h under mechanical stirring (300 r / min). After the reaction was completed, the microcapsules were filtered to obtain photothermal conversion microcapsules with a diameter of 1-20μm. The infrared spectrum of these photothermal conversion microcapsules is shown in [reference needed]. Figure 2 .

[0044] (3) First, add 1g of fatty alcohol alkoxy ether to 20g of ethylene glycol and mix well to obtain a mixture. Then add 1.0g of self-healing microcapsules to 15g of the mixture, sonicate for 10min, and centrifuge to obtain modified self-healing microcapsules.

[0045] 1g of fatty alcohol alkoxy ether was added to 5g of ethylene glycol and mixed evenly to obtain a mixture. 1.1g of photothermal conversion microcapsules were added to 5.5g of the mixture, sonicated for 10min, and centrifuged to obtain modified photothermal conversion microcapsules.

[0046] 1 g of modified self-healing microcapsules, 1.1 g of modified photothermal conversion microcapsules, and 11 g of epoxy resin E44 were mixed and mechanically stirred to obtain a rapid self-healing coating based on the photothermal effect.

[0047] Comparative Example 1

[0048] The difference from Example 1 is that in step (3), 1 g of self-healing microcapsules obtained in step (1) of Example 1, 0.1 g of modified photothermal conversion microcapsules obtained in step (2) of Example 1, and 10 g of epoxy resin E44 are mixed and mechanically stirred to obtain a rapid self-healing coating based on photothermal effect.

[0049] Comparative Example 2

[0050] The difference from Example 1 is that no fatty alcohol alkoxy ethers are added. The final product is a rapid self-healing coating based on the photothermal effect.

[0051] Comparative Example 3

[0052] The difference from Example 1 is that ethylene glycol was replaced with an equal amount of distilled water. The final product is a rapid self-healing coating based on the photothermal effect.

[0053] Test case

[0054] The coatings prepared in Examples 1-2 and Comparative Examples 1-3 were applied to Q235 steel plates by a doctor blade coating method, and after curing, a coating with a thickness of 120 μm was formed.

[0055] The coatings of each group were scratched through with a blade, and then irradiated with 700-900nm infrared light for 30 minutes. Afterwards, they were immersed in a 3.5% NaCl solution for corrosion testing. Electrochemical impedance spectroscopy (EIS) was performed after 24 hours. The fitted data are shown in Table 1. A higher charge transfer resistance and a lower corrosion current density indicate better self-healing and corrosion-resistant performance of the coating. The normative testing standard refers to GB / T 39482.3-2020 "Electrochemical Impedance Spectroscopy (EIS) of Painted and Unpainted Metal Samples".

[0056] Table 1. Charge transfer resistance of each coating scratch after immersion in 3.5% NaCl solution for 24 hours.

[0057]

[0058] As can be seen from Table 1, the charge transfer resistance of the self-healing coatings prepared in Examples 1 and 2 is greater than that of Comparative Examples 1-3, and the corrosion current density is less than that of Comparative Examples 1-3. This indicates that after modification, the self-healing microcapsules and photothermal conversion microcapsules can be uniformly dispersed in the polymer matrix, thereby achieving self-healing through light irradiation.

[0059] Figure 3 The electron microscope images of the coating prepared in Example 1 before and after light exposure show that light exposure causes the coating to begin to self-repair.

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

Claims

1. A rapid self-healing coating based on photothermal effect, characterized in that, The rapid self-healing coating comprises: a polymer matrix, self-healing microcapsules, and photothermal conversion microcapsules; The mass ratio of the self-healing microcapsules to the photothermal conversion microcapsules is 1:0.1~1.1; the photothermal conversion microcapsules account for 1~10% of the polymer matrix mass. The polymer matrix is ​​selected from epoxy resin, polyurethane or polyacrylate; the photothermal conversion material contained in the photothermal conversion microcapsule is selected from indocyanine green, Prussian blue or thiadiazole derivative. The self-healing microcapsules are prepared by the following method: (1) The self-healing reagent is dissolved in acetone to form an organic phase, and sodium poly(ethylene-co-methacrylic acid) is dissolved in water to form an aqueous phase. The organic phase is added dropwise to the aqueous phase, emulsified under high-speed stirring, and then the acetone is removed by vacuum evaporation to obtain microcapsules; the self-healing reagent contained in the self-healing microcapsules is selected from epoxy resin, polyurethane prepolymer or acrylate monomer. (2) Add fatty alcohol alkoxy ether to ethylene glycol to obtain a mixture, add microcapsules and sonicate, and centrifuge to obtain self-healing microcapsules; The photothermal conversion microcapsules were prepared by the following method: (a) The photothermal conversion material is dissolved in dichloromethane to form an organic phase, and polyethyleneimine is dissolved in water to form an aqueous phase. The organic phase is added dropwise to the aqueous phase, and an interfacial polymerization reaction occurs under mechanical stirring to obtain microcapsules. (b) Add fatty alcohol alkoxy ether to ethylene glycol to obtain a mixture, add microcapsules and sonicate, and centrifuge to obtain photothermal conversion microcapsules.

2. The rapid self-healing coating according to claim 1, characterized in that, The self-healing microcapsules have a particle size of 1-20 μm; the photothermal conversion microcapsules have a particle size of 1-20 μm.

3. The rapid self-healing coating according to claim 1, characterized in that, In step (1), the mass ratio of the self-healing reagent to acetone is 1:5~10, the mass ratio of sodium poly(ethylene-co-methacrylic acid) to water is 1:10~20, and the mass ratio of the organic phase to the aqueous phase is 1:5~10; the dropping speed is 1~5 mL / min, the temperature of the high-speed stirring is 10~35℃, and the time is 5~30 min; the speed of the high-speed stirring is 400-500 r / min.

4. The rapid self-healing coating according to claim 1, characterized in that, In step (2), the mass ratio of ethylene glycol to fatty alcohol alkoxy ether is 10-20:1; the mass ratio of microcapsules to mixture is 1:5-15; and the ultrasonic treatment time is 5-10 min.

5. The rapid self-healing coating according to claim 1, characterized in that, In step (a), the photothermal conversion material accounts for 0.1-10% of the mass of dichloromethane, the polyethyleneimine accounts for 1-10% of the mass of water, the mass ratio of the organic phase to the aqueous phase is 1:1-10, the dropping rate is 0.1-10 mL / min, the temperature of the interfacial polymerization reaction is 20-60℃, and the time is 1-24h.

6. The rapid self-healing coating according to claim 1, characterized in that, In step (b), the mass ratio of ethylene glycol to fatty alcohol alkoxy ether is 5-15:1; the mass ratio of microcapsules to mixture is 1:10; and the ultrasonic treatment time is 5-10 min.

7. The rapid self-healing coating according to claim 1, characterized in that, The rapid self-healing coating is obtained by uniformly mixing a polymer matrix, self-healing microcapsules, and photothermal conversion microcapsules.

8. The application of the rapid self-healing coating according to any one of claims 1 to 7 in improving self-healing rate and corrosion resistance.

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