A thermochromic composite coating with self-adaption and its preparation method and application

Abstract

This invention discloses a method for preparing a thermochromic composite coating with adaptive conductivity, comprising the following steps: The thermochromic material includes a base resin, thermochromic mixed pigments, fillers, and a solvent; the base resin, pigments, fillers, and solvent are mixed and stirred evenly to form a color paste; the color paste is then transferred to a high-speed ball mill for grinding and dispersion for 2 hours to obtain a thermochromic coating; the thermochromic coating is microencapsulated; the microencapsulated thermochromic coating and a nonlinear conductive filler are mixed and ball-milled; molten epoxy resin is added and stirred evenly; a curing agent and a diluent are added for dilution, and the mixture is thoroughly stirred to obtain a final mixture; the mixture is sprayed or brushed onto the surface of an insulating component to form a thermochromic composite coating with adaptive conductivity. The preparation method proposed in this invention is simple, feasible, and low-cost, and has broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage power equipment operation and maintenance technology, specifically relating to a thermochromic composite coating with adaptive conductivity, its preparation method and application. Background Technology

[0002] my country's load centers and energy resources are unevenly distributed, necessitating long-distance, high-capacity power transmission to address the electricity needs of these load centers. To reduce transmission costs, DC transmission projects have seen significant development. In DC power systems, equipment operates 24 / 7. With increasing years of operation, the insulation of these devices gradually ages, leading to abnormal heating. Prolonged overheating can cause equipment failures. Power systems contain numerous connection points between various types of equipment, such as the connection between high-voltage cables and GIS / transformer bushings, the connection between circuit breaker moving and stationary contacts, and switch contacts. These connection points may experience increased contact resistance due to poor contact during operation, resulting in overheating. Many DC power devices exhibit a significant temperature rise before a fault occurs. Therefore, detecting temperature changes in equipment can provide early warning of faults, allowing for proactive measures to prevent a series of adverse chain reactions caused by the fault.

[0003] Currently, commonly used temperature measurement methods in power systems mainly include infrared thermometry, thermocouple thermometry, and fiber Bragg grating (FBG) sensor thermometry. Infrared thermometry offers fast response, high sensitivity, and a wide measurable temperature range, but the equipment is relatively expensive and its application scope is narrow, suitable for measuring the external temperature of power equipment. Currently, infrared thermometry devices are only deployed on some critical power equipment. Thermocouple thermometry is a contact-type temperature measurement method with a simple structure and good stability, but it has poor noise immunity and is easily affected by changes in ambient temperature. FBG sensors offer high stability, high measurement accuracy, and good insulation and electromagnetic interference resistance, but their application involves complex optical coupling circuits, which have certain limitations. Therefore, researching temperature measurement methods suitable for large areas, multiple types, and wide ranges in power systems is of great significance for ensuring the reliable operation of power equipment and reducing failure rates.

[0004] Prior art publication number CA109135723A discloses an aerogel composite material with thermochromic function and its preparation method. The composite material consists of aerogel and a thermochromic composite coating, which comprises a transition layer, a thermochromic functional layer, and a surface protective layer. While retaining its original excellent properties, the aerogel is endowed with thermochromic functionality, meaning its optical properties are intelligently adjusted according to changes in ambient temperature. However, aerogel composite materials cannot be used in electrical equipment with heat dissipation requirements. Summary of the Invention

[0005] The technical problem to be solved by this invention is how to prepare a thermochromic composite coating with adaptive conductivity under DC environment.

[0006] The present invention solves the above-mentioned technical problems through the following technical means:

[0007] The first aspect of this invention provides a method for preparing an adaptive thermochromic composite coating, comprising the following steps:

[0008] Step 1: Preparation of thermochromic coatings

[0009] Thermochromic materials include base resin, thermochromic mixed pigment, filler and solvent; the base resin, pigment, filler and solvent are mixed and stirred evenly to make a color paste, and the color paste is transferred into a high-speed ball mill for grinding and dispersion to obtain thermochromic coating;

[0010] Step 2: Microencapsulation of thermochromic coatings

[0011] 1) Take an appropriate amount of carbamide in a beaker, add formaldehyde solution, stir magnetically until the mixture is uniform and the carbamide is completely dissolved; add ethanol solution to adjust the pH to weakly alkaline; then heat in a water bath and stir before cooling to room temperature to obtain a prepolymer solution.

[0012] 2) Take an appropriate amount of gum arabic powder and deionized water, heat and stir in a constant temperature water bath, and then cool to room temperature for later use; take thermochromic paint as the core material and add it to the prepared solution, stir under water bath conditions, and continue stirring after the water bath temperature drops to form a core material solution.

[0013] 3) The prepolymer solution is gradually added dropwise to the core material solution, and acetic acid solution is added to adjust the pH of the mixed solution to medium-strong acidity; appropriate amounts of sodium chloride and silicon dioxide are added to the strong acid solution, the water bath temperature is raised, the mixture is magnetically stirred and then cooled, dried at a constant temperature, and ground into powder to obtain microencapsulated thermochromic coating.

[0014] Step 3: Composite of adaptive conductivity filler

[0015] Microencapsulated thermochromic coating and nonlinear conductive filler are mixed and ball-milled; molten epoxy resin is added and stirred to mix evenly; then curing agent and diluent are added for dilution, and the mixture is stirred thoroughly to obtain a mixture; the mixture is sprayed or brushed onto the surface of the insulating part to form an adaptive thermochromic composite coating.

[0016] Beneficial effects: This invention takes into account the operating environment of power equipment. The thermochromic material is selected as a low-cost material with a wide color change range and strong weather resistance. The thermochromic pigment is selected as having good stability and processing performance. It can be applied to the large-area and wide-range temperature measurement needs of power systems while taking into account the economy.

[0017] In order to ensure the compatibility between thermochromic coatings and adaptive conductive fillers, this invention employs microencapsulation technology to treat thermochromic coatings.

[0018] Preferably, the base resin is epoxy resin or silicone resin.

[0019] Preferably, the thermochromic mixed pigment is a mixture of nickel sulfate, manganese sulfate, cobalt sulfate, and copper sulfate, or a mixture of cobalt sulfate, copper sulfate, and manganese sulfate, or a mixture of manganese sulfate and copper sulfate; the nickel sulfate, manganese sulfate, cobalt sulfate, and copper sulfate are mixed in a mass ratio of 5:1:1:2; the cobalt sulfate, copper sulfate, and manganese sulfate are mixed in a mass ratio of 1:2:1; and the manganese sulfate and copper sulfate are mixed in a mass ratio of 2:1.

[0020] Preferably, the filler is titanium dioxide and aluminum oxide, the solvent is xylene, and the dispersion time is 2 hours.

[0021] Preferably, the base resin, thermochromic mixed pigment, filler, and solvent are mixed in a mass ratio of 3:4:3:3.

[0022] Preferably, in step 1), the carbamide and formaldehyde solution are mixed in a mass ratio of (1-4):(5-15).

[0023] Preferably, the weakly alkaline pH is 8.0-9.0; the water bath temperature is 70-80℃; and the stirring time is 1 hour.

[0024] Preferably, in step 2), gum arabic powder and deionized water are mixed at a mass ratio of (0.5-2):(9-13) and heated in a constant temperature water bath at 50-60℃.

[0025] Preferably, the pH of the strongly acidic solution is 2.0-3.0; the water bath temperature is 90°C, and the temperature is lowered to 65°C.

[0026] Preferably, in step 3), sodium chloride and silicon dioxide are added to the strong acid solution in a mass ratio of 1:1; and the water bath temperature is raised to 90°C.

[0027] Beneficial effects: This invention uses thermochromic materials as the core material, carbamide as the wall material, gum arabic as an emulsifier, acetic acid as a pH adjuster, and sodium chloride and silicon dioxide as additives to improve the hardness of the microcapsule wall.

[0028] Preferably, the nonlinear conductive filler is SiC particles, ZnO particles, or other particles whose conductivity changes positively with the electric field.

[0029] Preferably, the curing agent is polyamide and the diluent is acetone.

[0030] A second aspect of the present invention provides a thermochromic composite coating with adaptive properties prepared by the above preparation method.

[0031] Beneficial effects: The adaptive thermochromic composite coating prepared by this invention can realize the dual functions of overheat warning for power equipment and intelligent control of surface electric field distribution.

[0032] A third aspect of the present invention provides the application of the above-described adaptive thermochromic composite coating in power equipment.

[0033] The advantages of this invention are:

[0034] This invention takes into account the operating environment of power equipment, and selects low-cost, wide color change range, and strong weather resistance materials for thermochromic materials, and selects thermochromic pigments with good stability and processing performance.

[0035] In order to ensure the compatibility between thermochromic coatings and adaptive conductivity fillers, this invention employs microencapsulation technology to treat thermochromic coatings.

[0036] This invention uses thermochromic materials as the core material, carbamide as the wall material, gum arabic as an emulsifier, acetic acid as a pH adjuster, and sodium chloride and silicon dioxide as additives to improve the hardness of the microcapsule wall.

[0037] The adaptive thermochromic composite coating prepared by this invention can realize the dual functions of overheat warning for power equipment and intelligent control of surface electric field distribution. Attached Figure Description

[0038] Figure 1 This is a flowchart of the preparation process of the adaptive thermochromic composite coating of the present invention;

[0039] Figure 2 The color change of the adaptive thermochromic composite material prepared in Example 1 at different temperatures;

[0040] Figure 3 The color change of the adaptive thermochromic composite material prepared in Example 2 at different temperatures;

[0041] Figure 4 The conductivity distribution of the adaptive thermochromic composite material prepared in Example 2 under different electric fields;

[0042] Figure 5 The electric field distribution of the adaptive thermochromic composite coating insulator in Example 2;

[0043] Figure 6Here are scanning electron microscope images of the particles before and after microencapsulation in Example 2;

[0044] Figure 7 The insulator surface flashover voltage before and after microencapsulation in Example 2 is shown. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0047] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0048] Example 1

[0049] The adaptive thermochromic composite coating preparation method of this embodiment includes the following steps:

[0050] Step 1: Preparation of thermochromic coatings

[0051] The base resin is silicone resin, the thermochromic pigment is a mixture of manganese sulfate and copper sulfate, the filler is titanium oxide and aluminum oxide, and the solvent is xylene. 9g of silicone resin, 12g of pigment (4g manganese sulfate and 8g copper sulfate), 6g of filler, and 6g of solvent were weighed. The solid particles were first ground and pulverized, then mixed and stirred until homogeneous to form a color paste. The color paste was then transferred to a high-speed spherical graphite mill for grinding and dispersion for 2 hours to obtain the thermochromic coating. The particle size of the coating was measured and controlled to be below 30μm.

[0052] Step 2: Microencapsulation of thermochromic coatings

[0053] 1) Take 8g of carbamide in a beaker, add 30g of formaldehyde solution, and stir magnetically until the mixture is homogeneous; add an appropriate amount of ethanol solution to adjust the pH to 8.0; then heat in a 70℃ water bath, stir for 1 hour, and cool to room temperature to obtain the prepolymer solution;

[0054] 2) Take 4g of gum arabic powder and 50g of deionized water, heat and stir in a constant temperature water bath at 60℃, and then cool to room temperature for later use; take 5g of thermochromic paint as the core material and add it to the prepared solution, stir for 10min in a water bath at 90℃, and then stir for another 10min in a water bath at 65℃ to form the core material solution.

[0055] 3) The prepolymer solution is gradually added dropwise to the core material solution, and an appropriate amount of acetic acid solution is added until the pH value is 2.0; 5g of sodium chloride and 5g of silicon dioxide are added to the strong acid solution, the water bath temperature is raised to 90℃, magnetically stirred for 1h, cooled, and dried at a constant temperature for 24h, and ground into powder of 10-100μm to obtain microencapsulated thermochromic coating.

[0056] Step 3: Composite of adaptive conductivity fillers

[0057] Weigh 10g of microencapsulated thermochromic coating and 5g of nonlinear conductive filler ZnO particles, mix them, and grind them in a ball mill for 1 hour. Add 12g of molten silicone resin and stir magnetically for 30 minutes to obtain a homogeneous mixture. Spray or brush the mixture onto the surface of the insulating part to form an adaptive thermochromic composite coating. The molten silicone resin is obtained by heating and stirring in a water bath at 50-60℃.

[0058] Example 2

[0059] The adaptive thermochromic composite coating preparation method of this embodiment includes the following steps:

[0060] Step 1: Preparation of thermochromic coatings

[0061] The base resin is epoxy resin, the thermochromic mixed pigments are nickel sulfate, manganese sulfate, cobalt sulfate, and copper sulfate, the fillers are titanium oxide and aluminum oxide, and the solvent is xylene. 9g of epoxy resin, 12g of pigments (6.70g nickel sulfate, 1.34g manganese sulfate, 1.34g cobalt sulfate, and 2.62g copper sulfate), 9g of filler, and 9g of solvent were weighed. The solid particles were first ground and pulverized, then mixed and stirred until homogeneous to form a color paste. The color paste was then transferred to a high-speed spherical graphite mill for grinding and dispersion for 2 hours to obtain the thermochromic coating. The particle size of the coating was measured and controlled to be below 30μm.

[0062] Step 2: Microencapsulation of thermochromic coatings

[0063] 2) Take 5g of carbamide in a beaker, add 25g of formaldehyde solution, and stir magnetically until the mixture is homogeneous; add 2.5g of ethanol solution to adjust the pH to 8.5; then heat in a 75℃ water bath, stir for 1 hour, and cool to room temperature to obtain the prepolymer solution;

[0064] 2) Take 2.5g of gum arabic powder and 45g of deionized water, heat and stir in a constant temperature water bath at 50℃, and then cool to room temperature for later use; take 5g of thermochromic paint as the core material and add it to the prepared solution, stir for 10min in a water bath at 90℃, and then stir for another 10min in a water bath at 65℃ to form the core material solution.

[0065] 3) The prepolymer solution is gradually added dropwise to the core material solution, and an appropriate amount of acetic acid solution is added until the pH value is 2.5; 2.5g of sodium chloride and 2.5g of silicon dioxide are added to the strong acid solution, the water bath temperature is raised to 90℃, magnetically stirred for 1h, cooled, and dried at a constant temperature for 24h, and ground into powder of 10-100μm to obtain microencapsulated thermochromic coating.

[0066] Step 3: Composite of adaptive conductivity fillers

[0067] Weigh 10g of the microencapsulated thermochromic coating and 5g of SiC particles, mix them, and grind them in a ball mill for 1 hour. Add 10g of molten epoxy resin and stir magnetically for 30 minutes to ensure thorough mixing. Then add 5g of polyamide ester curing agent and stir for 30 minutes. Add 5g of acetone diluent and stir thoroughly to obtain a mixture. Spray or brush the mixture onto the surface of the insulating part to form an adaptive thermochromic composite coating. The molten epoxy resin was obtained by heating and stirring in a 60°C water bath.

[0068] according to Figure 3 When the temperature reached 110℃, the color of the adaptive thermochromic composite coating changed significantly, and the color gradually deepened as the temperature continued to rise. The temperature range for common overheating faults in power equipment is 100-120℃; therefore, the adaptive thermochromic composite coating proposed in this invention can be applied to overheating early warning systems for most power equipment. Furthermore, the conductivity of the adaptive thermochromic composite coating as a function of an electric field was measured, such as... Figure 4 As shown, it can be seen that with the increase of the electric field, the conductivity of the adaptive thermochromic composite coating also gradually exhibits a nonlinear increasing characteristic. The coating of this invention is applied to surfaces such as... Figure 5 On the insulators shown, the surface electric field distribution along the radial direction of the uncoated and coated insulators was calculated. It can be seen that the electric field distribution of the coated insulator is lower than that of the uncoated insulator, indicating that the adaptive thermochromic composite coating has the function of intelligently regulating the surface electric field. According to Figure 6 The thermochromic coating of the present invention, after microencapsulation, has more regular particles and is coated with a capsule wall material, which can improve the stability of the thermochromic coating. Figure 7The thermochromic coating of this invention exhibits a significantly higher flashover voltage in insulators after microencapsulation compared to before microencapsulation, further demonstrating that microencapsulation can improve the compatibility between the two fillers. In summary, the adaptive thermochromic composite coating proposed in this invention can achieve both overheat warning and intelligent regulation of the electric field distribution.

[0069] The method for preparing the adaptive thermochromic composite coating proposed in this invention is simple, feasible, and low in cost, and has broad application prospects.

[0070] This invention takes into account the operating environment of power equipment, and selects low-cost, wide color change range, and strong weather resistance materials for thermochromic materials, and selects thermochromic pigments with good stability and processing performance.

[0071] In order to ensure the compatibility between thermochromic coatings and adaptive conductivity fillers, this invention employs microencapsulation technology to treat thermochromic coatings.

[0072] This invention uses thermochromic materials as the core material, carbamide as the wall material, gum arabic as an emulsifier, acetic acid as a pH adjuster, and sodium chloride and silicon dioxide as additives to improve the hardness of the microcapsule wall.

[0073] The adaptive thermochromic composite coating prepared by this invention can realize the dual functions of overheat warning for power equipment and intelligent control of surface electric field distribution.

[0074] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a thermochromic composite coating with adaptive conductivity, characterized in that, Includes the following steps: Step 1: Preparation of thermochromic coatings Thermochromic materials include base resin, thermochromic mixed pigments, fillers, and solvents; the base resin, pigments, fillers, and solvents are mixed and stirred evenly to form a color paste, and the color paste is transferred into a high-speed spherical ink mill for grinding and dispersion to obtain a thermochromic coating; the thermochromic mixed pigments are a mixture of nickel sulfate, manganese sulfate, cobalt sulfate, and copper sulfate, or a mixture of cobalt sulfate, copper sulfate, and manganese sulfate, or a mixture of manganese sulfate and copper sulfate; Step 2: Microencapsulation of thermochromic coatings 1) Take an appropriate amount of carbamide in a beaker, add formaldehyde solution, stir magnetically until the mixture is uniform and the carbamide is completely dissolved; add ethanol solution to adjust the pH to weakly alkaline; then heat in a water bath and stir before cooling to room temperature to obtain a prepolymer solution; 2) Take an appropriate amount of gum arabic powder and deionized water, heat and stir in a constant temperature water bath, and then cool to room temperature for later use; take thermochromic paint as the core material and add it to the prepared solution, stir under water bath conditions, and continue stirring after the water bath temperature drops to form a core material solution. 3) The prepolymer solution is gradually added dropwise to the core material solution, and acetic acid solution is added to adjust the pH of the mixed solution to strong acidity; an appropriate amount of sodium chloride and silicon dioxide are added to the strong acid solution, the water bath temperature is raised, the mixture is magnetically stirred and then cooled, dried at a constant temperature, and ground into powder to obtain microencapsulated thermochromic coating. Step 3: Composite of adaptive conductivity fillers Microencapsulated thermochromic coating and nonlinear conductive filler are mixed and ball-milled; molten epoxy resin is added and stirred to mix evenly; then curing agent and diluent are added and diluted, and the mixture is stirred thoroughly to obtain a mixture; the mixture is sprayed or brushed onto the surface of the insulating part to form a thermochromic composite coating with adaptive conductivity; The nonlinear conductive filler is ZnO particles.

2. The preparation method according to claim 1, characterized in that, The base resin is epoxy resin or silicone resin, the filler is titanium oxide and aluminum oxide, and the solvent is xylene; the dispersion time is 2 hours.

3. The preparation method according to claim 1, characterized in that, The base resin, thermochromic mixed pigment, filler, and solvent are mixed in a mass ratio of 3:4:3:3; nickel sulfate, manganese sulfate, cobalt sulfate, and copper sulfate are mixed in a mass ratio of 5:1:1:2; cobalt sulfate, copper sulfate, and manganese sulfate are mixed in a mass ratio of 1:2:1; and manganese sulfate and copper sulfate are mixed in a mass ratio of 2:

1.

4. The preparation method according to claim 1, characterized in that, In step 1), the carbamide and formaldehyde solution are mixed at a mass ratio of (1-4):(5-15); the weakly alkaline pH is 8.0-9.0; the water bath temperature is 70-80℃; and the stirring time is 1h.

5. The preparation method according to claim 1, characterized in that, In step 2), gum arabic powder and deionized water are mixed at a mass ratio of (0.5-2):(9-13) and heated in a constant temperature water bath at 50-60℃.

6. The preparation method according to claim 1, characterized in that, In step 3), the pH of the strong acid is 2.0-3.0; sodium chloride and silicon dioxide are added to the strong acid solution in a mass ratio of 1:1; and the water bath temperature is raised to 90°C.

7. The preparation method according to claim 1, characterized in that, The curing agent is polyamide, and the diluent is acetone.

8. A thermochromic composite coating with adaptive conductivity is prepared by the preparation method according to any one of claims 1-7.

9. The application of the thermochromic composite coating with adaptive conductivity as described in claim 8 in power equipment.

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