Polyurea protective coating with leakage monitoring function and preparation method and application thereof

Abstract

The present invention discloses a polyurea protective coating with a leakage current monitoring function, its preparation method, and application. The coating is composed of an isocyanate component, a chain extender component, and a functional additive. The isocyanate component is synthesized from polycarbonate diol and isophorone diisocyanate. The chain extender component is composed of an electrochromic chain extender and a hydrazide chain extender. The electrochromic chain extender is a compound of an electroactive diamine monomer and a triphenylamine derivative. The functional additive is composed of a solvent, a defoamer, and a catalyst. The prepared protective coating improves the color response speed and color change efficiency of the electrochromic material, significantly enhances its stability during use, effectively solves the problem of traditional inorganic oxide electrochromic coatings being easily peeled off and failing under thermal cycling or mechanical stress, and meets the requirements of real-time leakage current monitoring for high sensitivity and fast response performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of the intersection of functional polymer materials and leakage monitoring, and relates to a polyurea protective coating with leakage monitoring function. The present invention also relates to a preparation method and application of the polyurea protective coating with leakage monitoring function. Background Art

[0002] Leakage in electronic devices can pose serious safety hazards and may also lead to serious consequences such as fires and electric shocks, resulting in economic losses and casualties. Compared to current leakage monitoring technologies that rely on leakage protectors, insulation monitoring devices, or infrared thermal imaging, electrochromic materials offer potential applications in leakage monitoring due to their ability to rapidly change color under the influence of an external electric field, high sensitivity, independence from external sensors, instant visual alarms, and low cost.

[0003] Currently, electrochromic coatings can be divided into three categories based on their composition and structure: inorganic electrochromic coatings, inorganic / organic electrochromic composite coatings, and organic electrochromic coatings. Inorganic electrochromic coatings often utilize metal oxide materials (such as WO3 and NiO) that undergo reversible ion intercalation and deintercalation reactions under the action of an electric field, causing color change. While these coatings offer good coloring efficiency, they also suffer from poor mechanical properties. Inorganic / organic electrochromic composite coatings combine the advantages of inorganic coloring efficiency and organic flexibility, but the difference in thermal expansion coefficients between their rigid fillers and the organic matrix makes them susceptible to interfacial delamination during thermal cycling or mechanical deformation. The Chinese patent application, "Method for Preparing a Stretchable, Flexible, Transparent Electrochromic Coating," with application number 201911149976.4, publication number CN110802903A, and publication date February 18, 2020, discloses a AgNW / WO3 / PDMS composite coating. However, repeated bending can cause the AgNW network to break, significantly degrading electrochromic performance. Organic electrochromic coatings, such as polyaniline (PANI) and polypyrrole (PPy), while offering excellent flexibility, typically rely on liquid electrolytes as ionic conductors, which can lead to issues such as leakage, volatilization, and moisture sensitivity. The Chinese patent "An electrochromic coating and its preparation method", application number: 202110147632.0, publication number: CN112965311A, publication date: 2021.06.15, discloses an electrochromic coating that introduces electrochromic molecules and ion conductors through a solution method. This method greatly simplifies the manufacturing process, but is easily affected by the external environment, resulting in poor performance.

[0004] Therefore, it is crucial to develop an electrochromic composite coating that combines excellent mechanical strength, high performance stability, and high durability. This will effectively address the limitations of existing technologies and meet the application requirements of leakage monitoring in high-reliability, long-life equipment. Summary of the Invention

[0005] The first object of the present invention is to provide a polyurea protective coating with leakage monitoring function, which has the characteristics of forming a stable and efficient electronic conductive channel without the need for exogenous ionic liquid;

[0006] The second object of the present invention is to provide a method for preparing the polyurea protective coating with leakage monitoring function;

[0007] The third object of the present invention is to provide the application of the polyurea protective coating with leakage monitoring function.

[0008] The first technical solution adopted by the present invention is that the polyurea protective coating with leakage monitoring function is composed of the following raw material components in terms of mass percentage:

[0009] Isocyanate component 24.4%~33.4%, chain extender component 29.7%~35.4% and functional additive 31.3%~45.9%, the total content of the above raw materials is 100%;

[0010] The isocyanate component is synthesized from polycarbonate diol and isophorone diisocyanate in a mass ratio of 3:2 to 2:1;

[0011] The chain extender component is composed of an electrochromic chain extender and a hydrazide chain extender in a mass ratio of 7:3 to 6:1, and the electrochromic chain extender is compounded by an electroactive diamine monomer and a triphenylamine derivative;

[0012] Functional additives are composed of solvents, defoamers and catalysts.

[0013] The first technical solution is also characterized by:

[0014] The molecular weight of the polycarbonate diol is any one or more of 200, 500, 1000, and 2000, and can be combined in any proportion.

[0015] The compounding ratio of the electroactive diamine monomer and the triphenylamine derivative is 1:1~1:65.

[0016] The electroactive diamine monomer is synthesized by polymerization reaction of aniline tetramer, wherein the aniline tetramer is any one of tetraaminoaniline tetramer, N,N'-diethyltetraphenylamine, and diaminoaniline tetramer; the triphenylamine derivative is any one of 4,4',4''-triaminotriphenylamine, 4,4',4''-triethoxytriphenylamine, and 4,4'-diamino-4''-methylsulfonyltriphenylamine.

[0017] The hydrazide chain extender is one of benzohydrazide, succinic hydrazide, carbohydrazide and oxalic acid dihydrazide.

[0018] Among the functional additives, by mass percentage, the solvent accounts for 98.3% to 98.8%, the defoaming agent accounts for 0.2% to 1.2%, and the catalyst accounts for 0.6% to 1.0%, and the total content of each component is 100%; the solvent is any one of n-hexane, cyclohexane, dichloromethane, chloroform, isopropyl ether, N,N-dimethylacetamide, N,N-dimethylformamide, tetrahydrofuran, and ethyl acetate; and the catalyst is any one of triethanolamine and dibutyltin dilaurate.

[0019] The second technical solution adopted by the present invention is a method for preparing a polyurea protective coating with a leakage monitoring function. The preparation of the polyurea protective coating with a leakage monitoring function is specifically carried out according to the following steps:

[0020] Step 1: heating and stirring the dehydrated polycarbonate diol under a nitrogen atmosphere, while slowly adding isophorone diisocyanate dropwise to synthesize an isocyanate component;

[0021] Step 2, synthesizing an electrochromic chain extender;

[0022] Step 3: Take the raw materials in proportion, heat and stir the isocyanate component, electrochromic chain extender and functional additive under a nitrogen atmosphere until the reaction is complete; then add the hydrazide chain extender and continue heating and stirring until the reaction is complete;

[0023] Step 4: removing part of the solvent to obtain the electrochromic polyurea protective coating.

[0024] The second technical solution is also characterized by:

[0025] In step 1: the reaction temperature is 60°C to 80°C, the stirring speed is 500rpm to 700rpm, the dropping rate of isophorone diisocyanate is 3mL / min, and the reaction time is 4h to 6h;

[0026] In step 3: the reaction temperature is 70°C to 90°C, the reaction time is 4h to 6h; the temperature of the hydrazide chain extension reaction is 40°C to 60°C, the chain extension time is 4h to 6h, and the stirring speed is 200rpm to 500rpm;

[0027] In step 4: the solvent is removed by rotary evaporation at a temperature of 80°C to 100°C for 2 hours to 3 hours; the amount of solvent removed by rotary evaporation is 30% to 70% of the total volume of the prepared solution.

[0028] The specific steps of step 2 are:

[0029] Step 2-1, synthesizing an electroactive diamine precursor;

[0030] The specific operation is as follows: 20.63% to 29.25% by weight of aniline tetramer, 23.81% to 26.25% by weight of 2,6-difluorobenzoyl chloride, and 46.94% to 53.12% by weight of a solvent are mixed, with the total of the above components being 100%; then, the mixture is heated to 65 to 80°C under a nitrogen atmosphere and stirred at a speed of 300 to 500 rpm, reacted for 6 to 8 hours, and then heated to remove the solvent;

[0031] The specific operation of removing the solvent is: continuous heating at 95-110°C for 2-3 hours;

[0032] Step 2-2, synthesizing an electroactive diamine monomer;

[0033] The specific operation is as follows: 22.50% to 29.55% by weight of an electroactive diamine precursor, 24.43% to 27.00% by weight of 4-aminophenol, 2.84% to 4.00% by weight of anhydrous potassium carbonate, and 43.18% to 46.50% by weight of a solvent are mixed, and the total of the above components is 100%; then, the mixture is heated to 120° C. to 140° C. under a nitrogen atmosphere and stirred at a speed of 300 rpm to 600 rpm, reacted for 4 h to 6 h, and then cooled to room temperature. Finally, the mixture is added to water for precipitation separation, and the resulting precipitate is vacuum dried to obtain an electroactive diamine monomer powder, wherein the vacuum drying temperature is 60° C. to 80° C. and the drying time is 20 h to 24 h.

[0034] Step 2-3: mixing the electroactive diamine monomer and the triphenylamine derivative in a mass ratio of 1:1 to 1:1.65 to form an electrochromic chain extender.

[0035] The third technical solution adopted by the present invention is the application of a polyurea protective coating with a leakage monitoring function. The polyurea protective coating with a leakage monitoring function is sprayed on the surface of the substrate using a high-pressure mixing spray device. After spraying and heat curing, a polyurea protective coating with a leakage monitoring function is obtained. The spraying device is set to spray process parameters: air pressure of 0.3MPa~0.5MPa, spraying distance of 15cm~25cm, spraying volume of 10mL / m 2 ~15mL / m 2 ; The thermal curing temperature is 60℃~70℃, the curing time is 2h~3h, and the final coating thickness is 20μm~100μm.

[0036] The beneficial effects of the present invention are:

[0037] The polyurea protective coating with leakage current monitoring function of the present invention improves the color response speed and color change efficiency of electrochromic materials by compounding electroactive diamine monomers and triphenylamine derivatives, constructing stable and efficient self-assembled conductive channels, and regulating molecular chain configuration. This effectively solves the problem of traditional inorganic oxide electrochromic coatings being easily peeled and failing under thermal cycling or mechanical stress, meets the requirements of real-time leakage current monitoring for high sensitivity and fast response performance, significantly improves the adaptability and reliability of the coating in complex environments, further enhances the mechanical properties and structural stability of the material, and meets the requirements of high-intensity application scenarios for coating toughness and durability. Therefore, the electrochromic polyurea coating prepared by the present invention overcomes the shortcomings of traditional electrochromic coatings, realizes real-time visual alarm, and is particularly suitable for the field of high-reliability, long-life leakage current monitoring, and has broad application prospects. DETAILED DESCRIPTION

[0038] The present invention is described in detail below with reference to specific embodiments.

[0039] The polyurea protective coating with leakage monitoring function of the present invention is composed of the following raw material components by mass percentage:

[0040] Isocyanate component 24.4%~33.4%, chain extender component 29.7%~35.4% and functional additive 31.3%~45.9%, the total content of the above components is 100%;

[0041] The isocyanate component is synthesized from polycarbonate diol and isophorone diisocyanate in a mass ratio of 3:2 to 2:1; the chemical formula of polycarbonate diol is HO-(R-OCOO) n -R-OH is any one or more of molecular weight 200, 500, 1000, 2000 in any proportion;

[0042] The chain extender component is composed of an electrochromic chain extender and a hydrazide chain extender. Both of them have active groups that react with isocyanate and participate in the construction of the polyurea main chain. The mass ratio of the electrochromic chain extender to the hydrazide chain extender is 7:3 to 6:1.

[0043] The electrochromic chain extender is compounded by electroactive diamine monomer and triphenylamine derivative, with the mass compounding ratio being 1:1~1:65;

[0044] The electroactive diamine monomer is synthesized by polymerization of aniline tetramer, wherein the aniline tetramer is any one of tetraaminoaniline tetramer, N,N'-diethyltetraphenylamine, and diaminoaniline tetramer;

[0045] The triphenylamine derivative is any one of 4,4',4''-triaminotriphenylamine, 4,4',4''-triethoxytriphenylamine, and 4,4'-diamino-4''-methanesulfonyltriphenylamine.

[0046] The hydrazide chain extender is one of benzohydrazide, succinic hydrazide, carbohydrazide and oxalic acid dihydrazide.

[0047] The functional additive is composed of a solvent, a defoaming agent, and a catalyst. In the functional additive, by mass percentage, the solvent is 98.3% to 98.8%, the defoaming agent is 0.2% to 1.2%, and the catalyst is 0.6% to 1.0%, and the total content of each component is 100%.

[0048] The solvent is any one of n-hexane, cyclohexane, dichloromethane, chloroform, isopropyl ether, N,N-dimethylacetamide, N,N-dimethylformamide, tetrahydrofuran, and ethyl acetate;

[0049] The defoamer is Tego ® Airex900;

[0050] The catalyst is any one of triethanolamine and dibutyltin dilaurate.

[0051] The functions of the components of the polyurea protective coating with leakage monitoring function of the present invention are as follows:

[0052] Polycarbonate diol, a flexible soft segment, is copolymerized with a hard segment composed of isophorone diisocyanate and a multi-chain extender monomer, resulting in a distinct microphase-separated structure. This structure not only facilitates the targeted enrichment of polar groups within the material but also forms continuous polar channels that facilitate ion migration. Due to the steric hindrance of the aromatic rings, while disrupting the regular packing of the hard segments, it introduces intersegmental gaps and localized free volume between molecules, forming an electronic network structure with dynamic regulation capabilities. This enables the formation of stable and efficient electronic conductive channels without the need for exogenous ionic liquids.

[0053] The electroactive diamine monomer has the ability to transfer charge and is compounded with triphenylamine derivatives to form The stack-driven charge migration pathway not only improves the efficiency of electron migration in the channel but also provides a structural foundation for the subsequent electrochromic response. By compounding electroactive diamine monomers with triphenylamine derivatives, the color response speed and color change efficiency of the electrochromic material are improved, significantly enhancing its stability during use. This effectively solves the problem of traditional inorganic oxide electrochromic coatings being prone to peeling and failure under thermal cycling or mechanical stress, meeting the requirements of high sensitivity and fast response performance for real-time leakage monitoring.

[0054] The highly polar hydrazine group introduced by the hydrazide chain extender can form a stable hydrogen bond network with the amino and carbonyl groups in the material, and enhance the electron hopping migration ability between chain segments through the electronic conjugation effect of hydrogen bonds.

[0055] The polyether soft segment itself has good chain segment flexibility and polar coordination ability, which further promotes the electron migration behavior within and between chains under the regulation of dynamic hydrogen bonds.

[0056] By using a block copolymer structure to regulate the microphase separation of the coating and introducing a compounding strategy for electrochromic elements, a stable and efficient self-assembled conductive channel is constructed. This avoids the problems of leakage, volatilization, and moisture sensitivity caused by traditional liquid electrolytes, significantly improving the adaptability and reliability of the coating in complex environments. By precisely constructing a polyurea network with synergistic microphase separation structures and functional groups, a highly synergistic "polarity enrichment-dynamic gap-charge migration-hydrogen bond-assisted" composite conductive channel system is constructed within the material. While ensuring the material's mechanical strength and environmental stability, it achieves excellent electronic conductivity and electrochromic response, making it suitable for leakage monitoring applications.

[0057] By introducing chain extenders and cross-linkers, regulating the molecular chain configuration, and constructing a multi-level hydrogen bond energy-consuming network structure, the mechanical properties and structural stability of the material are further enhanced, meeting the requirements of high-intensity application scenarios for coating toughness and durability.

[0058] Through intermolecular interactions and self-assembly in the polyurea matrix, a conductive network is formed for electrons to pass through, which allows the compounded electrochromic elements to undergo stable electron exchange and form a stable electrochromic structure.

[0059] The method for preparing the polyurea protective coating with a leakage current monitoring function of the present invention is to prepare the polyurea protective coating with a leakage current monitoring function, specifically by following the steps below:

[0060] Step 1: heating and stirring the dehydrated polycarbonate diol under a nitrogen atmosphere, while slowly adding isophorone diisocyanate dropwise to synthesize an isocyanate component;

[0061] The dehydration steps of the polycarbonate diol are as follows: dehydration at 120°C in a vacuum drying oven at -0.10 MPa for 2 to 3 hours;

[0062] The mass ratio of polycarbonate diol to isophorone diisocyanate is 3:2~2:1, the dropping speed of isophorone diisocyanate is 3 mL / min, the stirring speed is 500 rpm~700 rpm; the reaction temperature is 60°C~80°C, and the reaction time is 4h~6h;

[0063] The reaction principle of polycarbonate diol and isophorone diisocyanate is as follows:

[0064] .

[0065] Step 2, synthesizing an electrochromic chain extender;

[0066] The specific steps are:

[0067] Step 2-1, synthesizing an electroactive diamine precursor;

[0068] The specific operation is as follows: 20.63% to 29.25% by weight of aniline tetramer, 23.81% to 26.25% by weight of 2,6-difluorobenzoyl chloride, and 46.94% to 53.12% by weight of a solvent are mixed, with the total of the above components being 100%; then, the mixture is heated to 65 to 80°C under a nitrogen atmosphere and stirred at a speed of 300 to 500 rpm, reacted for 6 to 8 hours, and then heated to remove the solvent;

[0069] The specific operation of removing the solvent is: continuous heating at 95-110°C for 2-3 hours;

[0070] The reaction principle is as follows:

[0071] ;

[0072] Step 2-2, synthesizing an electroactive diamine monomer;

[0073] The specific operation is as follows: 22.50% to 29.55% by weight of an electroactive diamine precursor, 24.43% to 27.00% by weight of 4-aminophenol, 2.84% to 4.00% by weight of anhydrous potassium carbonate, and 43.18% to 46.50% by weight of a solvent are mixed, and the total of the above components is 100%; then, the mixture is heated to 120° C. to 140° C. under a nitrogen atmosphere and stirred at a speed of 300 rpm to 600 rpm, reacted for 4 h to 6 h, and then cooled to room temperature. Finally, the mixture is added to water for precipitation separation, and the resulting precipitate is vacuum dried to obtain an electroactive diamine monomer powder, wherein the vacuum drying temperature is 60° C. to 80° C. and the drying time is 20 h to 24 h.

[0074] The reaction principle is as follows:

[0075] ;

[0076] Step 2-3, mixing the electroactive diamine monomer and the triphenylamine derivative in a mass ratio of 1:1 to 1:1.65 to form an electrochromic chain extender;

[0077] Step 3: Take the raw materials in proportion, heat and stir the isocyanate component, electrochromic chain extender and functional additive under a nitrogen atmosphere until the reaction is complete; then add the hydrazide chain extender and continue heating and stirring until the reaction is complete;

[0078] The isocyanate component is 24.4% to 33.4%, the chain extender component is 29.7% to 35.4%, and the functional additive is 31.3% to 45.9%. The total content of the above raw materials is 100%. The chain extender component is composed of an electrochromic chain extender and a hydrazide chain extender in a mass ratio of 7:3 to 6:1.

[0079] The reaction temperature is 70°C~90°C, the reaction time is 4h~6h, and the stirring speed is 200rpm~500rpm;

[0080] The temperature of the hydrazide chain extension reaction is 40°C~60°C, and the chain extension time is 4h~6h.

[0081] Step 4: removing part of the solvent to obtain an electrochromic polyurea protective coating;

[0082] The solvent is removed by rotary evaporation at a temperature of 80°C to 100°C for 2h to 3h; the amount of solvent removed by rotary evaporation is 30% to 70% of the total volume of the prepared solution.

[0083] The polyurea protective coating with leakage monitoring function of the present invention is applied by spraying the polyurea protective coating with leakage monitoring function on the surface of a substrate using a high-pressure mixing spray device. After spraying and heat curing, a polyurea protective coating with leakage monitoring function is obtained.

[0084] The spraying device sets the spraying process parameters: air pressure is 0.3MPa~0.5MPa, spraying distance is 15cm~25cm, spraying volume is 10mL / m 2 ~15mL / m 2 ;

[0085] The thermal curing temperature is 60℃~70℃, the curing time is 2h~3h, and the final coating thickness is 20μm~100μm.

[0086] When the substrate of the polyurea protective coating with leakage monitoring function leaks electricity and the coating is exposed to a current of no less than 0.5V, brown color will appear, indicating that leakage occurs at that location.

[0087] Example 1

[0088] In this embodiment, a polyurea protective coating with a leakage monitoring function is prepared by specifically following the steps below:

[0089] Step 1: 3.7 g of dehydrated polycarbonate diol (molecular weight 500) was heated to 60°C under a nitrogen atmosphere and stirred at 500 rpm. Subsequently, 5.5 g of isophorone diisocyanate was slowly added dropwise at a rate of 3 mL / min. The mixture was reacted for 4 h to obtain an isocyanate component.

[0090] The dehydration steps were as follows: dehydration at 120 °C for 2 h in a vacuum drying oven at -0.10 MPa;

[0091] Step 2, synthesizing an electrochromic chain extender;

[0092] The specific steps are:

[0093] Step 2-1, Synthesis of an Electroactive Diamine Precursor: 4.3 g of aniline tetramer, 3.5 g of 2,6-difluorobenzoyl chloride, 5 g of cyclohexane, and 1.9 g of dichloromethane were heated to 65° C. under a nitrogen atmosphere and stirred at 300 rpm. After reacting for 6 h, the mixture was heated to 95° C. and heated continuously for 2 h to remove the solvent in the system to obtain an electroactive diamine precursor;

[0094] Step 2-2, Synthesis of an Electroactive Diamine Monomer: 5.2 g of an electroactive diamine precursor, 4.3 g of 4-aminophenol, 0.5 g of anhydrous potassium carbonate, and 7.6 g of N,N-dimethylacetamide were heated to 120° C. under a nitrogen atmosphere and stirred at 300 rpm. After reacting for 4 h, the mixture was cooled to room temperature and poured into water for precipitation. The resulting solid was vacuum dried at 60° C. for 20 h to obtain an electroactive diamine monomer.

[0095] Step 2-3, mixing 2.5 g of an electroactive diamine monomer and 3.6 g of a triphenylamine derivative to obtain an electrochromic chain extender;

[0096] Step 3: 9.2 g of isocyanate component, 6.1 g of electrochromic chain extender and functional additive were heated to 70° C. and stirred at 200 rpm under a nitrogen atmosphere for 4 h; then 2.5 g of hydrazide chain extender was added and continued to heat to 40° C. and stir for 4 h;

[0097] The functional additives are composed of 9.6g of N,N-dimethylacetamide, 0.02g of dibutyltin dilaurate catalyst, and 0.1g of Tego®Airex900 defoaming agent;

[0098] Step 4: removing 30% of the solvent by volume of the solution by rotary evaporation at 80° C. for 2 h to obtain an electrochromic polyurea protective coating;

[0099] Step 5: spraying to obtain a protective coating;

[0100] The electrochromic polyurea protective coating was sprayed on the substrate surface using a high-pressure mixing spray device. After spraying and thermal curing, an electrochromic polyurea protective coating was obtained. The process parameters were as follows: the spraying equipment pressure was 0.3 MPa, the spraying distance was 15 cm, and the spraying flow rate was 10 mL / m 2 ; The thermal curing temperature is 60℃, the curing time is 2h, and the final coating thickness is 20μm.

[0101] Example 2

[0102] In this embodiment, a polyurea protective coating with a leakage monitoring function is prepared by specifically following the steps below:

[0103] Step 1: 2.1 g of dehydrated polycarbonate diol (molecular weight 2000) was heated to 80°C under a nitrogen atmosphere and stirred at 700 rpm. Subsequently, 3.6 g of isophorone diisocyanate was slowly added dropwise at a rate of 3 mL / min. The mixture was reacted for 6 h to obtain an isocyanate component.

[0104] The dehydration steps were as follows: dehydration at 120°C for 3 h in a vacuum drying oven at -0.10 MPa;

[0105] Step 2, synthesizing an electrochromic chain extender;

[0106] The specific steps are:

[0107] Step 2-1, Synthesis of an electroactive diamine precursor: 3.3 g of aniline tetramer, 4.2 g of 2,6-difluorobenzoyl chloride, 5.9 g of n-hexane, and 2.6 g of chloroform were heated to 80° C. under a nitrogen atmosphere and stirred at 500 rpm. After reacting for 8 h, the mixture was heated to 110° C. and continuously heated for 3 h to remove the solvent in the system to obtain an electroactive diamine precursor;

[0108] Step 2-2, Synthesis of an Electroactive Diamine Monomer: 4.5 g of an electroactive diamine precursor, 5.4 g of 4-aminophenol, 0.8 g of anhydrous potassium carbonate, and 9.3 g of N,N-dimethylformamide were heated to 140° C. under a nitrogen atmosphere and stirred at 600 rpm. After reacting for 6 h, the mixture was cooled to room temperature and poured into water for precipitation separation. The resulting solid was vacuum dried at 80° C. for 24 h to obtain an electroactive diamine monomer;

[0109] Step 2-3, mixing 4.5 g of an electroactive diamine monomer and 4.7 g of a triphenylamine derivative to obtain an electrochromic chain extender;

[0110] Step 3: 5.7 g of isocyanate component, 9.2 g of electrochromic chain extender and functional additive were heated to 90° C. and stirred at 500 rpm under nitrogen atmosphere for 6 h; then 1.5 g of succinylhydrazide chain extender was added and continued to heat to 60° C. and stir for 6 h;

[0111] The functional additives are composed of 6.8g of N,N-dimethylacetamide, 0.08g of triethanolamine catalyst, and 0.04g of Tego® Airex900 defoaming agent;

[0112] Step 4, removing 70% of the solvent by volume of the solution by rotary evaporation at 100° C. for 3 h to obtain an electrochromic polyurea protective coating;

[0113] Step 5: spraying to obtain a protective coating;

[0114] The electrochromic polyurea protective coating was sprayed on the substrate surface using a high-pressure mixing spray device. After spraying and thermal curing, an electrochromic polyurea protective coating was obtained. The process parameters were as follows: the spraying equipment pressure was 0.5 MPa, the spraying distance was 25 cm, and the spraying flow rate was 15 mL / m 2 ; The thermal curing temperature is 70℃, the curing time is 3h, and the final coating thickness is 100μm.

[0115] Example 3

[0116] In this embodiment, a polyurea protective coating with a leakage monitoring function is prepared by specifically following the steps below:

[0117] Step 1: 2.4 g of dehydrated polycarbonate diol (molecular weight 1000) was heated to 70°C under a nitrogen atmosphere and stirred at 600 rpm. Subsequently, 3.92 g of isophorone diisocyanate was slowly added dropwise at a rate of 3 mL / min. The mixture was reacted for 5 h to obtain an isocyanate component.

[0118] The dehydration steps were as follows: dehydration at 120 °C for 2 h in a vacuum drying oven at -0.10 MPa;

[0119] Step 2, synthesizing an electrochromic chain extender;

[0120] The specific steps are:

[0121] Step 2-1, Synthesis of an Electroactive Diamine Precursor: 4.26 g of aniline tetramer, 3.65 g of 2,6-difluorobenzoyl chloride, 5.32 g of dichloromethane, and 2 g of isopropyl ether were heated to 70° C. under a nitrogen atmosphere and stirred at 400 rpm. After reacting for 7 h, the mixture was heated to 105° C. and heated continuously for 2 h to remove the solvent in the system to obtain an electroactive diamine precursor;

[0122] Step 2-2, Synthesis of an Electroactive Diamine Monomer: 4.28 g of an electroactive diamine precursor, 5.04 g of 4-aminophenol, 0.74 g of anhydrous potassium carbonate, and 8.62 g of tetrahydrofuran were heated to 130° C. under a nitrogen atmosphere and stirred at 450 rpm. The mixture was reacted for 5 h, cooled to room temperature, poured into water for precipitation, and the resulting solid was vacuum dried at 70° C. for 22 h to obtain an electroactive diamine monomer.

[0123] Step 2-3, mixing 2.7 g of an electroactive diamine monomer and 4.46 g of a triphenylamine derivative to obtain an electrochromic chain extender;

[0124] Step 3: 6.32 g of isocyanate component, 7.16 g of electrochromic chain extender and functional additive were heated to 80° C. and stirred at 350 rpm under a nitrogen atmosphere for 5 h; then 1.65 g of succinylhydrazide chain extender was added and continued to heat to 50° C. and stir for 5 h;

[0125] The functional additives are composed of 7.3g of N,N-dimethylacetamide, 0.07g of triethanolamine catalyst, and 0.06g of Tego® Airex900 defoaming agent;

[0126] Step 4: removing 45% of the solvent by volume of the solution by rotary evaporation at 90° C. for 3 h to obtain an electrochromic polyurea protective coating;

[0127] Step 5: spraying to obtain a protective coating;

[0128] The electrochromic polyurea protective coating was sprayed on the substrate surface using a high-pressure mixing spray device. After spraying and thermal curing, an electrochromic polyurea protective coating was obtained. The process parameters were as follows: the spraying equipment pressure was 0.4 MPa, the spraying distance was 20 cm, and the spraying flow rate was 12 mL / m 2 ; The thermal curing temperature is 65℃, the curing time is 3h, and the final coating thickness is 60μm.

[0129] Example 4

[0130] In this embodiment, a polyurea protective coating with a leakage monitoring function is prepared by specifically following the steps below:

[0131] Step 1: 2.7 g of dehydrated polycarbonate diol (molecular weight 2000) was heated to 60°C under a nitrogen atmosphere and stirred at 600 rpm. Subsequently, 4.3 g of isophorone diisocyanate was slowly added dropwise at a rate of 3 mL / min. The mixture was reacted for 6 h to obtain an isocyanate component.

[0132] The dehydration steps were as follows: dehydration at 120°C for 3 h in a vacuum drying oven at -0.10 MPa;

[0133] Step 2, synthesizing an electrochromic chain extender;

[0134] The specific steps are:

[0135] Step 2-1, Synthesis of an electroactive diamine precursor: 3.7 g of aniline tetramer, 3.8 g of 2,6-difluorobenzoyl chloride, 5.2 g of n-hexane, and 2.4 g of chloroform were heated to 70° C. under a nitrogen atmosphere and stirred at 400 rpm. After reacting for 7 h, the mixture was heated to 100° C. and continuously heated for 2 h to remove the solvent in the system to obtain an electroactive diamine precursor;

[0136] Step 2-2, Synthesis of an Electroactive Diamine Monomer: 4.3 g of an electroactive diamine precursor, 5 g of 4-aminophenol, 0.7 g of anhydrous potassium carbonate, and 8.54 g of N,N-dimethylformamide were heated to 120° C. under a nitrogen atmosphere and stirred at 500 rpm. After reacting for 5 h, the mixture was cooled to room temperature and poured into water for precipitation separation. The resulting solid was vacuum dried at 60° C. for 24 h to obtain an electroactive diamine monomer;

[0137] Step 2-3, mixing 3.2 g of an electroactive diamine monomer and 4.2 g of a triphenylamine derivative to obtain an electrochromic chain extender;

[0138] Step 3: 7 g of isocyanate component, 7.4 g of electrochromic chain extender and functional additive were heated to 80° C. and stirred at 500 rpm under a nitrogen atmosphere for 5 h; then 1.8 g of succinylhydrazide chain extender was added and continued to heat to 50° C. and stir for 6 h;

[0139] The functional additives are composed of 7.8g of N,N-dimethylacetamide, 0.04g of triethanolamine catalyst, and 0.07g of Tego® Airex900 defoaming agent;

[0140] Step 4: removing 40% of the solvent by volume of the solution by rotary evaporation at 90° C. for 2 h to obtain an electrochromic polyurea protective coating;

[0141] Step 5: spraying to obtain a protective coating;

[0142] The electrochromic polyurea protective coating was sprayed on the substrate surface using a high-pressure mixing spray device. After spraying and thermal curing, an electrochromic polyurea protective coating was obtained. The process parameters were as follows: the spraying equipment pressure was 0.3 MPa, the spraying distance was 20 cm, and the spraying flow rate was 14 mL / m 2 ; The thermal curing temperature is 70℃, the curing time is 2h, and the final coating thickness is 30μm.

[0143] Example 5

[0144] In this embodiment, a polyurea protective coating with a leakage monitoring function is prepared by specifically following the steps below:

[0145] Step 1: 3.2 g of dehydrated polycarbonate diol (molecular weight 1000) was heated to 70°C under a nitrogen atmosphere and stirred at 500 rpm. Subsequently, 4.92 g of isophorone diisocyanate was slowly added dropwise at a rate of 3 mL / min. The mixture was reacted for 5 h to obtain an isocyanate component.

[0146] The dehydration steps were as follows: dehydration at 120 °C for 2 h in a vacuum drying oven at -0.10 MPa;

[0147] Step 2, synthesizing an electrochromic chain extender;

[0148] The specific steps are:

[0149] Step 2-1, Synthesis of an electroactive diamine precursor: 3.84 g of aniline tetramer, 4.15 g of 2,6-difluorobenzoyl chloride, 5.53 g of n-hexane, and 2.36 g of chloroform were heated to 75° C. under a nitrogen atmosphere and stirred at 500 rpm. After reacting for 7 h, the mixture was heated to 100° C. and continuously heated for 2 h to remove the solvent in the system to obtain an electroactive diamine precursor;

[0150] Step 2-2, Synthesis of an Electroactive Diamine Monomer: 4.32 g of an electroactive diamine precursor, 4.8 g of 4-aminophenol, 0.65 g of anhydrous potassium carbonate, and 8.2 g of N,N-dimethylformamide were heated to 130° C. under a nitrogen atmosphere and stirred at 450 rpm. The mixture was reacted for 5 h, cooled to room temperature, poured into water for precipitation, and the resulting solid was vacuum dried at 70° C. for 24 h to obtain an electroactive diamine monomer.

[0151] Step 2-3, mixing 3.8 g of an electroactive diamine monomer and 3.8 g of a triphenylamine derivative to obtain an electrochromic chain extender;

[0152] Step 3: 8.12 g of isocyanate component, 7.6 g of electrochromic chain extender and functional additive were heated to 70° C. and stirred at 350 rpm under a nitrogen atmosphere for 4 h; then 2.04 g of succinylhydrazide chain extender was added and continued to heat to 45° C. and stir for 6 h;

[0153] The functional additives are composed of 8.4g of N,N-dimethylacetamide, 0.06g of triethanolamine catalyst, and 0.08g of Tego® Airex900 defoaming agent;

[0154] Step 4: removing 60% of the solvent by volume of the solution by rotary evaporation at 90° C. for 3 h to obtain an electrochromic polyurea protective coating;

[0155] Step 5: spraying to obtain a protective coating;

[0156] The electrochromic polyurea protective coating was sprayed on the substrate surface using a high-pressure mixing spray device. After spraying and thermal curing, an electrochromic polyurea protective coating was obtained. The process parameters were as follows: the spraying equipment pressure was 0.5 MPa, the spraying distance was 15 cm, and the spraying flow rate was 10 mL / m 2 ; The thermal curing temperature is 60℃, the curing time is 2h, and the final coating thickness is 70μm.

[0157] Example 6

[0158] In this embodiment, a polyurea protective coating with a leakage monitoring function is prepared by specifically following the steps below:

[0159] Step 1: 2.24 g of dehydrated polycarbonate diol (molecular weight 500) was heated to 70°C under a nitrogen atmosphere and stirred at 500 rpm. Subsequently, 3.83 g of isophorone diisocyanate was slowly added dropwise at a rate of 3 mL / min. The mixture was reacted for 4 h to obtain an isocyanate component.

[0160] The dehydration steps were as follows: dehydration at 120°C for 3 h in a vacuum drying oven at -0.10 MPa;

[0161] Step 2, synthesizing an electrochromic chain extender;

[0162] The specific steps are:

[0163] Step 2-1, Synthesis of an Electroactive Diamine Precursor: 4.22 g of aniline tetramer, 3.5 g of 2,6-difluorobenzoyl chloride, 5.4 g of n-hexane, and 2.1 g of dichloromethane were heated to 70° C. under a nitrogen atmosphere and stirred at 450 rpm. After reacting for 7 h, the mixture was heated to 105° C. and continuously heated for 2 h to remove the solvent in the system to obtain an electroactive diamine precursor;

[0164] Step 2-2, Synthesis of an Electroactive Diamine Monomer: 5.4 g of an electroactive diamine precursor, 4.7 g of 4-aminophenol, 0.6 g of anhydrous potassium carbonate, and 8.4 g of N,N-dimethylformamide were heated to 130° C. under a nitrogen atmosphere and stirred at 500 rpm. After reacting for 6 h, the mixture was cooled to room temperature and poured into water for precipitation separation. The resulting solid was vacuum dried at 70° C. for 23 h to obtain an electroactive diamine monomer;

[0165] Step 2-3, mixing 2.6 g of an electroactive diamine monomer and 4.3 g of a triphenylamine derivative to obtain an electrochromic chain extender;

[0166] Step 3: 6.07 g of isocyanate component, 6.9 g of electrochromic chain extender and functional additive were heated to 85° C. and stirred at 250 rpm under a nitrogen atmosphere for 4 h; then 1.75 g of succinylhydrazide chain extender was added and continued to heat to 55° C. and stir for 6 h;

[0167] The functional additives are composed of 7.2g of N,N-dimethylacetamide, 0.06g of triethanolamine catalyst, and 0.05g of Tego® Airex900 defoaming agent;

[0168] Step 4: removing 50% of the solvent by volume of the solution by rotary evaporation at 80° C. for 2 h to obtain an electrochromic polyurea protective coating;

[0169] Step 5: spraying to obtain a protective coating;

[0170] The electrochromic polyurea protective coating was sprayed on the substrate surface using a high-pressure mixing spray device. After spraying and thermal curing, an electrochromic polyurea protective coating was obtained. The process parameters were as follows: the spraying equipment pressure was 0.4 MPa, the spraying distance was 20 cm, and the spraying flow rate was 13 mL / m 2 ; The thermal curing temperature is 65℃, the curing time is 3h, and the final coating thickness is 80μm.

[0171] Comparative Example

[0172] Tables 1 and 2 compare the durability, mechanical properties and electrochromic stability of PDMS-based AgNW / WO3 electrochromic coatings, polyaniline electrochromic coatings, Ti-doped porous WO3 electrochromic coatings and the electrochromic polyurea coatings for leakage monitoring prepared in Examples 1 and 2.

[0173] As can be seen from the table, the Ti-doped porous WO3 electrochromic coating has good salt spray resistance, but poor flexibility and impact resistance, and is prone to cracking and damage. Its electrochromic response is slow, but the chromaticity and charge retention rates are high; the polyaniline electrochromic coating is prone to corrosion in a salt spray environment, has poor flexibility and impact resistance, and although the color change response is fast, the chromaticity and charge retention rates are low; the PDMS-based AgNW / WO3 electrochromic coating has improved salt spray resistance, flexibility, and impact resistance, and has a faster color change response and good chromaticity and charge retention, showing better overall performance.

[0174] Compared with the above coatings, the electrochromic polyurea coatings prepared in Examples 1 and 2 exhibited superior performance in terms of corrosion resistance, mechanical properties, and electrochromic stability, and had higher durability and application potential.

[0175] Table 1 compares the corrosion resistance and mechanical properties of PDMS-based AgNW / WO3 electrochromic coatings, polyaniline electrochromic coatings, Ti-doped porous WO3 electrochromic coatings, and the electrochromic polyurea coatings for leakage monitoring prepared in Examples 1 and 2;

[0176] Table 1

[0177]

[0178] Table 2 compares the electrochromic stability of PDMS-based AgNW / WO3 electrochromic coatings, polyaniline electrochromic coatings, Ti-doped porous WO3 electrochromic coatings, and the electrochromic polyurea coatings for leakage monitoring prepared in Examples 1 and 2;

[0179] Table 2

[0180]

[0181] Anti-corrosion performance test: Salt spray resistance is tested in accordance with GB / T1771-2007.

[0182] Mechanical properties test: Use a constant temperature and humidity test chamber, set the temperature to -25°C, place the test sample in a low temperature environment for 3 hours, and then test the impact resistance according to the method specified in GB / T1732-2020; the flexibility is tested according to the method specified in GB / T1731-1993.

[0183] Response stability test: Cyclic voltammetry was used according to ASTM E1184-17.

Claims

1. A polyurea protective coating with leakage monitoring function, characterized in that: It is composed of the following raw materials in percentage by mass: Isocyanate component 24.4%~33.4%, chain extender component 29.7%~35.4% and functional additive 31.3%~45.9%, the total content of each raw material is 100%; The isocyanate component is synthesized from polycarbonate diol and isophorone diisocyanate in a mass ratio of 3:2 to 2:1; The chain extender component is composed of an electrochromic chain extender and a hydrazide chain extender in a mass ratio of 7:3 to 6:1, and the electrochromic chain extender is compounded by an electroactive diamine monomer and a triphenylamine derivative; The functional additives are composed of solvents, defoamers and catalysts; The preparation method of the electrochromic chain extender is as follows: Step 2-1, synthesizing an electroactive diamine precursor; The specific operation is as follows: 20.63% to 29.25% by weight of aniline tetramer, 23.81% to 26.25% by weight of 2,6-difluorobenzoyl chloride, and 46.94% to 53.12% by weight of a solvent are mixed, with the total of the three components being 100%; then, the mixture is heated to 65 to 80°C under a nitrogen atmosphere and stirred at a speed of 300 to 500 rpm. After reacting for 6 to 8 hours, the solvent is removed by heating; The specific operation of removing the solvent is: continuous heating at 95-110°C for 2-3 hours; Step 2-2, synthesizing an electroactive diamine monomer; The specific operation is as follows: 22.50% to 29.55% by weight of an electroactive diamine precursor, 24.43% to 27.00% by weight of 4-aminophenol, 2.84% to 4.00% by weight of anhydrous potassium carbonate, and 43.18% to 46.50% by weight of a solvent are mixed, and the total of the four components is 100%; then, the mixture is heated to 120°C to 140°C under a nitrogen atmosphere and stirred at a speed of 300 rpm to 600 rpm. After reacting for 4 h to 6 h, the mixture is cooled to room temperature and finally added to water for precipitation separation. The resulting precipitate is vacuum dried to obtain an electroactive diamine monomer powder, wherein the vacuum drying temperature is 60°C to 80°C and the drying time is 20 h to 24 h. Step 2-3: mixing the electroactive diamine monomer and the triphenylamine derivative in a mass ratio of 1:1 to 1:1.65 to form an electrochromic chain extender.

2. The polyurea protective coating with leakage monitoring function according to claim 1, characterized in that: The molecular weight of the polycarbonate diol is any one or more of 200, 500, 1000, and 2000 in any proportion.

3. The polyurea protective coating with leakage monitoring function according to claim 1, characterized in that: The composite mass ratio of the electroactive diamine monomer and the triphenylamine derivative is 1:1 to 1:

65.

4. The polyurea protective coating with leakage monitoring function according to claim 3, characterized in that: The aniline tetramer is any one of tetraaminoaniline tetramer, N,N'-diethyltetraaniline, and diaminoaniline tetramer; The triphenylamine derivative is any one of 4,4',4''-triaminotriphenylamine, 4,4',4''-triethoxytriphenylamine, and 4,4'-diamino-4''-methanesulfonyltriphenylamine.

5. The polyurea protective coating with leakage monitoring function according to claim 1, characterized in that: The hydrazide chain extender is any one of benzohydrazide, succinic hydrazide, carbohydrazide and oxalic acid dihydrazide.

6. The polyurea protective coating with leakage monitoring function according to claim 1, characterized in that: In the functional additive, by mass percentage, the solvent is 98.3% to 98.8%, the defoamer is 0.2% to 1.2%, and the catalyst is 0.6% to 1.0%, and the total content of each component is 100%; The solvent is any one of n-hexane, cyclohexane, dichloromethane, chloroform, isopropyl ether, N,N-dimethylacetamide, N,N-dimethylformamide, tetrahydrofuran, and ethyl acetate; The catalyst is any one of triethanolamine and dibutyltin dilaurate.

7. A method for preparing a polyurea protective coating with a leakage monitoring function, characterized in that: The polyurea protective coating with leakage monitoring function according to any one of claims 1 to 6 is prepared by specifically following the steps below: Step 1: heating and stirring the dehydrated polycarbonate diol under a nitrogen atmosphere, while slowly adding isophorone diisocyanate dropwise to synthesize an isocyanate component; Step 2, synthesizing an electrochromic chain extender; Step 3: Take the raw materials in proportion, heat and stir the isocyanate component, electrochromic chain extender and functional additive under a nitrogen atmosphere until the reaction is complete; then add the hydrazide chain extender and continue heating and stirring until the reaction is complete; Step 4: removing part of the solvent to obtain the electrochromic polyurea protective coating.

8. The method for preparing a polyurea protective coating with a leakage monitoring function according to claim 7, characterized in that: In the step 1, the reaction temperature is 60° C. to 80° C., the stirring speed is 500 rpm to 700 rpm, the dropping rate of isophorone diisocyanate is 3 mL / min, and the reaction time is 4 h to 6 h; In step 3: the reaction temperature is 70°C to 90°C, the reaction time is 4h to 6h; the temperature of the hydrazide chain extension reaction is 40°C to 60°C, the chain extension time is 4h to 6h, and the stirring speed is 200rpm to 500rpm; In step 4: the solvent is removed by rotary evaporation at a temperature of 80°C to 100°C for 2 hours to 3 hours; the amount of solvent removed by rotary evaporation is 30% to 70% of the total volume of the prepared solution.

9. Application of polyurea protective coating with leakage monitoring function, characterized in that: Using the polyurea protective coating with leakage monitoring function according to any one of claims 1 to 6, spraying it on the surface of the substrate using a high-pressure mixing spray device, and obtaining a polyurea protective coating with leakage monitoring function after spraying and heat curing treatment; The spraying process parameters of the spraying device are: air pressure of 0.3MPa~0.5MPa, spraying distance of 15cm~25cm, spraying volume of 10mL / m 2 ~15mL / m 2 ; The temperature of the heat curing treatment is 60° C. to 70° C., the curing time is 2 h to 3 h, and the final coating thickness is 20 μm to 100 μm.

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