A self-repairing protective coating material, a self-repairing protective coating, a preparation method thereof and a method for repairing a damaged coating

Abstract

The application provides a self-repairing protective coating material, a self-repairing protective coating and a preparation method and a damaged coating repairing method thereof, and relates to the technical field of coating. Raw materials of the self-repairing protective coating material include diisocyanate, double active functional group end-capped polysiloxane and 2,5-diamino-1,3,4-thiadiazole. The preparation method comprises the following steps: adding diisocyanate into double active functional group end-capped polysiloxane, and heating and reacting under the action of a catalyst; adding 2,5-diamino-1,3,4-thiadiazole, and heating and treating after the reaction. The self-repairing protective coating material has a high-chemical-stability polysiloxane long chain segment, which provides good aging resistance for the coating; a thiazole structure, a urethane group or a urea group structure forms various interaction forces with a base material to synergistically enhance adhesion; hydrogen bonds between the urethane group or the urea group provide excellent self-repairing performance, and the coating scratch area can be healed and repaired after short-time heating.

Description

Technical Field

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

[0002] Organic anti-corrosion coatings, due to their physical barrier function, have become an important means of protecting metals from corrosion. Although organic coatings can protect metals from corrosion for a certain period, their protective performance is often difficult to maintain under mechanical damage and long-term aging degradation. Specifically, mechanical damage directly undermines the integrity of the coating; aging caused by environmental factors such as ultraviolet radiation and water leads to the decomposition of resin segments in the coating, causing phenomena such as powdering and embrittlement; and the penetration and diffusion of corrosive media accumulates corrosion products at the coating / metal interface, leading to coating peeling and accelerating coating failure. Given the complexity of coating failure factors, improving its aging resistance and developing self-healing functions are two key strategies for extending the service life of anti-corrosion coatings.

[0003] Organosilicon materials are considered ideal for aging resistance due to the high bond energy of the Si-O bonds in their main chain (providing excellent resistance to photoaging) and their low surface energy (helping to mitigate hydrolytic aging). However, their low surface energy also leads to poor adhesion to the substrate. Commercially available polydimethylsiloxane (PDMS) typically has a strength of less than 1 MPa, while organosilicon polyurea or organosilicon polyurethane typically has a strength of less than 2 MPa. They are easily detached from the substrate under external forces, thus losing their barrier protection function. Furthermore, these organosilicon materials generally lack self-healing capabilities; once damaged, corrosive media will rapidly penetrate and exacerbate the corrosion reaction.

[0004] Therefore, there is an urgent need to develop organic anti-corrosion coatings that combine strong adhesion, excellent aging resistance, and self-healing capabilities to synergistically improve their service life. Summary of the Invention

[0005] The purpose of this application is to provide a self-healing protective coating material, a self-healing protective 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:

[0007] A self-healing protective coating material, the raw materials of which include: diisocyanate, bifunctional terminal polysiloxane and 2,5-diamino-1,3,4-thiadiazole;

[0008] 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;

[0009] The dual-functional-terminated polysiloxanes include aminopropyl-terminated polydimethylsiloxane and / or hydroxyl-terminated polydimethylsiloxane.

[0010] The molar ratio of the diisocyanate to the sum of the amounts of the bifunctionally-terminated polysiloxane and the 2,5-diamino-1,3,4-thiadiazole is 1.15:1 to 1:1; the molar ratio of the bifunctionally-terminated polysiloxane to the 2,5-diamino-1,3,4-thiadiazole is 19:1 to 15:5.

[0011] Optionally, the molar ratio of the diisocyanate to the sum of the amounts of the bifunctionally-terminated polysiloxane and the 2,5-diamino-1,3,4-thiadiazole can be any value between 1.15:1, 1.1:1, 1:1, or 1.15:1-1:1; the molar ratio of the bifunctionally-terminated polysiloxane to the 2,5-diamino-1,3,4-thiadiazole can be any value between 19:1, 18:2, 17:3, 16:4, 15:5, or 19:1-15:5.

[0012] Preferably, the self-healing protective coating material satisfies at least one of the following conditions:

[0013] (1) The diisocyanate is a mixture of isophorone diisocyanate and other types of diisocyanates, wherein the isophorone diisocyanate accounts for not less than 60% of the total molar amount of the diisocyanate;

[0014] 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%.

[0015] (2) The dual-functional group-terminated polysiloxane is a mixture of aminopropyl-terminated polydimethylsiloxane and hydroxyl-terminated polydimethylsiloxane, wherein the aminopropyl-terminated polydimethylsiloxane accounts for no less than 50% of the total molar amount of the dual-functional group-terminated polysiloxane;

[0016] Optionally, the proportion of the aminopropyl-terminated polydimethylsiloxane to the total molar amount of the dual-functional-group-terminated polysiloxane can be any value of 50%, 60%, 70%, 80%, 90%, 95%, or not less than 50%.

[0017] (3) The average molecular weight of the dual-functional group-terminated polysiloxane is 1000 g / mol to 6000 g / mol.

[0018] Optionally, the average molecular weight of the dual-functional-terminated polysiloxane can be any value between 1000 g / mol, 2000 g / mol, 3000 g / mol, 4000 g / mol, 5000 g / mol, 6000 g / mol, or 1000 g / mol to 6000 g / mol.

[0019] Preferably, the other type of diisocyanate is dicyclohexylmethane-4,4'-diisocyanate and / or diphenylmethane diisocyanate.

[0020] This application also provides a method for preparing the self-healing protective coating material, comprising:

[0021] Under a protective atmosphere, diisocyanate was added to a polysiloxane with two active functional groups and heated to carry out a first reaction in the presence of a catalyst; then 2,5-diamino-1,3,4-thiadiazole was added and heated to carry out a second reaction, and the self-healing protective coating material was obtained after post-treatment.

[0022] Preferably, the preparation method of the self-healing protective coating material satisfies at least one of the following conditions:

[0023] (1) The diisocyanate and the dual-functional group-terminated polysiloxane are dissolved in a first organic solvent to obtain a corresponding solution. The first organic solvent includes one or more of chloroform, toluene, and tetrahydrofuran.

[0024] (2) The 2,5-diamino-1,3,4-thiadiazole was first dissolved in N,N-dimethylformamide to obtain the corresponding solution;

[0025] (3) The temperature of the first reaction is 50-70℃ and the time is 1-4h;

[0026] Optionally, the temperature of the first reaction can be any value between 50°C, 60°C, 70°C or 50-70°C, and the time can be any value between 1h, 2h, 3h, 4h or 1-4h.

[0027] (4) The temperature of the second reaction is 60-80℃ and the time is 12-36h;

[0028] 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 12h, 18h, 24h, 30h, 36h or 12-36h.

[0029] (5) The catalyst includes one or more of dibutyltin dilaurate, triethylenediamine, and bismuth neodecanoate;

[0030] (6) The post-processing includes rotary evaporation, water precipitation and drying performed sequentially.

[0031] This application also provides a self-healing protective coating, the raw materials of which include the self-healing protective coating material.

[0032] Preferably, the thickness of the self-healing protective coating is 50-300 μm.

[0033] Optionally, the thickness of the self-healing protective coating can be any value between 50μm, 100μm, 150μm, 200μm, 250μm, 300μm or 50-300μm.

[0034] This application also provides a method for preparing the self-healing protective coating, comprising:

[0035] The self-healing protective coating material is dissolved in a second organic solvent and then applied to the surface of the substrate, and cured at 40-80°C for 1-24 hours.

[0036] The second organic solvent includes one or more of butyl acetate, chloroform, and tetrahydrofuran.

[0037] The application methods include, but are not limited to, scraping, spin coating, dip coating, or spraying.

[0038] 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.

[0039] This application also provides a method for repairing a damaged coating, wherein the damaged coating includes the aforementioned self-healing protective coating material, and the method for repairing the damaged coating includes:

[0040] The damaged coating is heated.

[0041] Preferably, the heating temperature of the damaged coating is 50-100℃, and the heating time is 10-60 min.

[0042] Optionally, the heating temperature of the damaged coating can be any value between 50°C, 60°C, 70°C, 80°C, 90°C, 100°C or 50-100°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.

[0043] Compared with the prior art, the beneficial effects of this application include:

[0044] The self-healing protective coating material and coating provided in this application are composed of polysiloxane long-chain segments, thiadiazole structures, and urethane or urea groups formed between these two structural monomers and isocyanates. The highly chemically stable polysiloxane long-chain segments provide excellent aging resistance to the coating; the thiadiazole, urethane, or urea groups form various interactions with the substrate, synergistically enhancing adhesion; and the hydrogen bonds between the urethane or urea groups provide excellent self-healing properties, enabling the coating to heal scratched areas after brief heating. This self-healing protective coating integrates aging resistance, corrosion resistance, and self-healing functions, effectively extending its protective lifespan.

[0045] The self-healing protective coating material and the preparation method of the self-healing protective coating provided in this application have a simple preparation process, and the resulting coating has strong adhesion, excellent anti-corrosion and aging resistance, and good self-healing properties, and has broad application prospects.

[0046] The method for repairing damaged coatings provided in this application is simple to operate. Attached Figure Description

[0047] 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.

[0048] Figure 1 The infrared spectrum of the organosilicon resin prepared in Example 1;

[0049] Figure 2 This study compares the adhesion performance of the thiadiazole-containing silicone resin in Example 2, the thiadiazole-free silicone resin in Comparative Example 1, and the commercial PDMS anti-corrosion coating in Comparative Example 2 on pure copper, carbon steel, and epoxy resin sheet substrates.

[0050] Figure 3 Comparison of optical images before and after repair of scratches on the high-adhesion silicone anti-corrosion coating in Example 3;

[0051] Figure 4 The image shows the changes in the optical image of the high-adhesion silicone anti-corrosion coating in Example 4 and the commercially available epoxy coating in Comparative Example 3 before and after 30 days of aging on the patterned substrate. Detailed Implementation

[0052] 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.

[0053] Example 1

[0054] This embodiment provides a self-healing protective coating material, the preparation method of which is as follows:

[0055] 1. Dissolve 1.0 mmol of isophorone diisocyanate completely in 12 mL of toluene.

[0056] 2. Dissolve 0.75 mmol of aminopropyl-terminated polydimethylsiloxane (average molecular weight 4000 g / mol, purchased from Anhui Zesheng Technology Co., Ltd., Anaiji brand) in 12 mL of toluene.

[0057] 3. Under nitrogen protection, the isocyanate solution was gradually added dropwise to the continuously stirred polysiloxane solution. After adding the catalyst, the mixture was heated and stirred at 55°C for 3 hours.

[0058] 4. Dissolve 0.25 mmol of 2,5-diamino-1,3,4-thiadiazole in 10 mL of N,N-dimethylformamide, and gradually add it dropwise to the above solution. Heat and stir at 55°C for 24 h. Obtain a solid organosilicon resin containing thiadiazole structure by rotary evaporation, precipitation with excess water, and vacuum heating and drying. This is a high-adhesion, aging-resistant, self-healing protective coating material.

[0059] Figure 1 The image shows the infrared spectrum of the silicone 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. (1031 cm⁻¹) -1 and 789cm -1 The bending vibrations attributed to the O-Si-O group and the Si-CH3 group, respectively, confirmed the existence of the organosiloxane backbone, 1515 cm⁻¹. -1 This corresponds to the stretching vibration of the C=N group within the thiadiazole ring. These results demonstrate the successful synthesis of the organosilicon resin.

[0060] Example 2

[0061] This embodiment provides a self-healing protective coating material, the preparation method of which is as follows:

[0062] 1. Dissolve 1.0 mmol of isophorone diisocyanate completely in 12 mL of chloroform.

[0063] 2. Dissolve 0.85 mMol of aminopropyl-terminated polydimethylsiloxane (average molecular weight 3000 g / Mol) in 12 mL of chloroform.

[0064] 3. Under nitrogen protection, the isocyanate solution was gradually added dropwise to the continuously stirred polysiloxane solution. After adding the catalyst, the mixture was heated and stirred at 60°C for 2 hours.

[0065] 4. Dissolve 0.15 mmol of 2,5-diamino-1,3,4-thiadiazole in 10 mL of N,N-dimethylformamide, and gradually add it dropwise to the above solution. Heat and stir at 60 °C for 24 h, and obtain solid organosilicon resin by rotary evaporation, precipitation with excess water, and vacuum heating and drying.

[0066] This application also provides a self-healing protective coating, the preparation method of which is as follows:

[0067] The silicone resin prepared by dissolving butyl acetate was adjusted to a suitable viscosity, and then the resin solution was coated onto the surface of a pure copper substrate, a carbon steel substrate, and an epoxy resin sheet using a doctor blade coater. After curing at 60°C for 24 hours, a silicone anti-corrosion coating containing a thiadiazole structure was obtained with a thickness of 100±5μm.

[0068] Comparative Example 1

[0069] Unlike Example 2, 2,5-diamino-1,3,4-thiadiazole was not added. Instead, 1.0 mMol of isophorone diisocyanate and 0.85 mMol of aminopropyl-terminated polydimethylsiloxane (average molecular weight 3000 g / Mol) were reacted. After the reaction was completed, a solid organosilicon resin without thiadiazole structure 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 copper substrate, carbon steel substrate, and epoxy resin sheet in the same manner. After curing, an organosilicon anti-corrosion coating without thiadiazole structure was obtained with a thickness of 100±5 μm.

[0070] Comparative Example 2

[0071] In contrast, commercial Dow Corning Sylgard 184 PDMS and curing agent were mixed evenly, and the viscosity was adjusted to a suitable level with butyl acetate. The mixture was then applied to the surfaces of pure copper substrate, carbon steel substrate, and epoxy resin sheet substrate in the same manner. After curing, a commercial PDMS anti-corrosion coating with a thickness of 100±5μm was obtained.

[0072] The adhesion of the high-adhesion silicone anti-corrosion coating prepared in the examples and the coating prepared in the comparative examples was determined according to ISO 4624:2016 standard.

[0073] Figure 2 This study compares the adhesion performance of the thiadiazole-containing silicone resin in Example 2, the silicone resin without a thiadiazole structure in Comparative Example 1, and the commercial PDMS anti-corrosion coating in Comparative Example 2 on pure copper, carbon steel, and epoxy resin sheet substrates. It can be observed that the adhesion of the silicone resin coating containing the thiadiazole structure is approximately 2 MPa higher than that of the silicone resin without the thiadiazole structure, and approximately 3 MPa higher than that of the commercial PDMS anti-corrosion coating. This indicates that the prepared silicone resin containing the thiadiazole structure exhibits good adhesion to both metal substrates and primer substrates such as epoxy resin.

[0074] Example 3

[0075] This embodiment provides a self-healing protective coating material, the preparation method of which is as follows:

[0076] 1. Dissolve 0.6 mmol of isophorone diisocyanate and 0.4 mmol of dicyclohexylmethane-4,4'-diisocyanate completely in 12 mL of chloroform.

[0077] 2. Dissolve 0.95 mmol of aminopropyl-terminated polydimethylsiloxane (average molecular weight 6000 g / mol) in 12 mL of chloroform.

[0078] 3. Under nitrogen protection, the isocyanate solution was gradually added dropwise to the continuously stirred polysiloxane solution. After adding the catalyst, the mixture was heated and stirred at 50°C for 4 hours.

[0079] 4. Dissolve 0.05 mmol of 2,5-diamino-1,3,4-thiadiazole in 10 mL of N,N-dimethylformamide, and gradually add it dropwise to the above solution. Heat and stir at 70 °C for 12 h, and obtain solid organosilicon resin by rotary evaporation, precipitation with excess water, and vacuum heating and drying.

[0080] This application also provides a self-healing protective coating, the preparation method of which is as follows:

[0081] The silicone resin prepared by dissolving butyl acetate 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 40°C for 12 hours, a high-adhesion silicone anti-corrosion coating with a thickness of 300±5μm was obtained.

[0082] Artificial scratches 5 mm 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 it at 100°C for 20 minutes.

[0083] Figure 3 A comparison of optical images before and after repair of scratches on the high-adhesion silicone anti-corrosion coating in Example 3 is shown. It can be observed that the scratches on the coating almost completely disappeared after heat repair, indicating that the prepared silicone anti-corrosion coating has excellent self-healing properties.

[0084] Example 4

[0085] This embodiment provides a self-healing protective coating material, the preparation method of which is as follows:

[0086] 1. Dissolve 1.0 mMol of isophorone diisocyanate and 0.15 mMol of dicyclohexylmethane-4,4'-diisocyanate completely in 12 mL of chloroform.

[0087] 2. Dissolve 0.65 mmol of aminopropyl-terminated polydimethylsiloxane (average molecular weight 1000 g / mol) and 0.1 mmol of hydroxyl-terminated polydimethylsiloxane (average molecular weight 2000 g / mol) in 12 mL of chloroform.

[0088] 3. Under nitrogen protection, the isocyanate solution was gradually added dropwise to the continuously stirred polysiloxane solution. After adding the catalyst, the mixture was heated and stirred at 70°C for 1 hour.

[0089] 4. Dissolve 0.25 mmol of 2,5-diamino-1,3,4-thiadiazole in 10 mL of N,N-dimethylformamide, and gradually add it dropwise to the above solution. Heat and stir at 50 °C for 36 h, and obtain solid organosilicon resin by rotary evaporation, precipitation with excess water, and vacuum heating and drying.

[0090] This application also provides a self-healing protective coating, the preparation method of which is as follows:

[0091] The silicone resin prepared by dissolving butyl acetate was adjusted to a suitable viscosity and then coated onto the surface of a glass substrate using a doctor blade coater. After curing at 80°C for 1 hour, a high-adhesion silicone anti-corrosion coating with a thickness of 100±5μm was obtained.

[0092] Comparative Example 3

[0093] In comparison, a commercially available bisphenol A type epoxy resin coating was applied to the surface of a glass substrate, and the thickness after curing was 100±5μm.

[0094] A 30-day ultraviolet aging test was conducted according to GB / T1865-2009 standard, with an irradiation wavelength of 300 nm-400 nm and an average irradiation intensity of 65 W / cm². 2 .

[0095] Figure 4The optical image changes of the high-adhesion silicone anti-corrosion coating and the commercially available epoxy coating on the patterned substrate before and after 30 days of aging in Example 4 can be seen. It can be found that the appearance of the silicone anti-corrosion coating did not change significantly, but the epoxy coating changed color significantly and its transparency decreased significantly.

[0096] Example 5

[0097] This embodiment provides a self-healing protective coating material, the preparation method of which is as follows:

[0098] 1. Dissolve 0.9 mmol of isophorone diisocyanate and 0.1 mmol of dicyclohexylmethane-4,4'-diisocyanate completely in 12 mL of chloroform.

[0099] 2. Dissolve 0.65 mmol of aminopropyl-terminated polydimethylsiloxane (average molecular weight 1000 g / mol) and 0.1 mmol of hydroxyl-terminated polydimethylsiloxane (average molecular weight 2000 g / mol) in 12 mL of chloroform.

[0100] 3. Under nitrogen protection, the isocyanate solution was gradually added dropwise to the continuously stirred polysiloxane solution. After adding the catalyst, the mixture was heated and stirred at 70°C for 1 hour.

[0101] 4. Dissolve 0.25 mmol of 2,5-diamino-1,3,4-thiadiazole in 10 mL of N,N-dimethylformamide, and gradually add it dropwise to the above solution. Heat and stir at 50 °C for 36 h, and obtain solid organosilicon resin by rotary evaporation, precipitation with excess water, and vacuum heating and drying.

[0102] This application also provides a self-healing protective coating, the preparation method of which is as follows:

[0103] The silicone resin prepared by dissolving butyl acetate was adjusted to a suitable viscosity and then coated onto the surface of a glass substrate using a doctor blade coater. After curing at 80°C for 1 hour, a high-adhesion silicone anti-corrosion coating with a thickness of 100±5μm was obtained.

[0104] A 30-day ultraviolet aging test was conducted according to GB / T1865-2009 standard, with an irradiation wavelength of 300 nm-400 nm and an average irradiation intensity of 65 W / cm². 2 .

[0105] Table 1 shows the changes in water contact angle, color difference, and transmittance at 550nm of the high-adhesion silicone anti-corrosion coating in Example 5 during 30 days of aging. It can be seen that no significant changes were found in the various properties of the coating, indicating that the prepared silicone anti-corrosion coating has excellent aging resistance.

[0106] Table 1. Performance comparison of the coating obtained in Example 5 during 30 days of aging.

[0107]

[0108] Comparative Example 4

[0109] Unlike Example 5, 0.9 mmol diphenylmethane diisocyanate was used instead of 0.9 mmol isophorone diisocyanate in the reaction with polysiloxane. After the reaction was completed, a solid organosilicon resin without thiadiazole structure was obtained by rotary evaporation, precipitation with excess water, and vacuum heating and drying. After adjusting to a suitable viscosity, the resin solution was coated onto the surface of a glass substrate using a doctor blade coater and cured at 80°C for 1 hour to obtain an organosilicon anti-corrosion coating with a thickness of 100±5 μm. A 30-day ultraviolet aging test was then conducted according to GB / T1865-2009 standard, with an irradiation wavelength of 300 nm-400 nm and an average irradiation intensity of 65 W / cm². 2 .

[0110] Table 2 shows the changes in water contact angle, color difference, and transmittance at 550 nm of the silicone anti-corrosion coating in Comparative Example 4 during 30 days of aging. It can be seen that the water contact angle of the coating decreased, the color difference value increased significantly, and the transmittance decreased significantly, indicating that the silicone anti-corrosion coating prepared in the comparative example has insufficient aging resistance.

[0111] Table 2. Performance comparison of the coatings obtained in Comparative Example 4 during 30 days of aging.

[0112]

[0113] Comparative Example 5

[0114] Polysiloxanes without aminopropyl or hydroxyl-terminated groups do not react with diisocyanates and cannot form resins. They have poor aging resistance and adhesion, and no self-healing function.

[0115] 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 material for a self-healing protective coating, characterized in that, Its raw materials include: diisocyanate, polysiloxane with dual active functional groups and 2,5-diamino-1,3,4-thiadiazole; The diisocyanate is a mixture of isophorone diisocyanate and other types of diisocyanates, wherein the isophorone diisocyanate accounts for not less than 60% of the total molar amount of the diisocyanate; the other types of diisocyanates include one or more of aliphatic diisocyanates and aromatic diisocyanates; The dual-functionalized end-capped polysiloxane is a mixture of aminopropyl-terminated polydimethylsiloxane and hydroxyl-terminated polydimethylsiloxane, wherein the aminopropyl-terminated polydimethylsiloxane accounts for no less than 50% of the total molar amount of the dual-functionalized end-capped polysiloxane. The molar ratio of the diisocyanate to the sum of the amounts of the bifunctionally-terminated polysiloxane and the 2,5-diamino-1,3,4-thiadiazole is 1.15:1 to 1:1; the molar ratio of the bifunctionally-terminated polysiloxane to the 2,5-diamino-1,3,4-thiadiazole is 19:1 to 15:

5. The average molecular weight of the dual-functional-terminated polysiloxane is 1000 g / mol to 6000 g / mol; The method for preparing the material for the self-healing protective coating includes: Under a protective atmosphere, diisocyanate was added to a polysiloxane with two active functional groups and heated to carry out a first reaction in the presence of a catalyst; then 2,5-diamino-1,3,4-thiadiazole was added and heated to carry out a second reaction, and the material for self-healing protective coating was obtained after post-treatment. The diisocyanate and the bifunctional terminal polysiloxane are pre-dissolved in a first organic solvent to obtain corresponding solutions, wherein the first organic solvent includes one or more of chloroform, toluene, and tetrahydrofuran; The 2,5-diamino-1,3,4-thiadiazole was first dissolved in N,N-dimethylformamide to obtain the corresponding solution; The temperature of the first reaction is 50-70℃, and the time is 1-4 hours; The second reaction is carried out at a temperature of 60-80℃ for a time of 12-36 hours. The catalyst includes one or more of dibutyltin dilaurate, triethylenediamine, and bismuth neodecanoate. The post-processing includes rotary evaporation, water precipitation, and drying performed sequentially.

2. A self-healing protective coating, characterized in that, Its raw materials include the material for self-healing protective coatings as described in claim 1.

3. The self-healing protective coating according to claim 2, characterized in that, The thickness of the self-healing protective coating is 50-300 μm.

4. A method for preparing the self-healing protective coating according to claim 2 or 3, characterized in that, include: The material for the self-healing protective coating is dissolved in a second organic solvent and then applied to the surface of the substrate, and cured at 40-80°C for 1-24 hours. The second organic solvent includes one or more of butyl acetate, chloroform, and tetrahydrofuran.

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