Preparation of phase change microcapsules with energy storage and photo-thermal conversion characteristics and application thereof in coating

Abstract

This invention discloses the preparation of phase change microcapsules with energy storage and photothermal conversion properties and their application in thermal insulation coatings. It relates to the field of microencapsulated phase change materials technology, including core-shell structured microcapsules prepared with organic phase change materials as the core and copper silicate as the shell, with a core-to-shell mass ratio of 1:0.5–1.5. This invention employs an in-situ interfacial reaction deposition method, constructing an oil-water two-phase emulsion template, and with the assistance of an emulsifier, allowing inorganic precursors to undergo a chemical precipitation reaction at the interface to form a continuous and dense inorganic copper silicate shell. These microcapsules not only utilize phase change materials such as paraffin to achieve high-density thermal energy storage, but also leverage the efficient photothermal conversion and photocatalytic degradation characteristics of the copper silicate shell to achieve an integrated design of photothermal conversion, anti-pollution, and thermal energy storage. These phase change microcapsules exhibit excellent temperature buffering and energy storage performance, demonstrating a good thermal barrier effect and active thermal regulation capability in coatings, and have broad application prospects in building energy conservation, solar thermal collection, and thermal protection.

Description

Technical Field

[0001] This invention belongs to the field of microencapsulated phase change materials technology, specifically relating to the preparation of phase change microcapsules with energy storage and photothermal conversion properties and their application in coatings. Background Technology

[0002] Phase change materials (PCMs) can absorb or release a large amount of latent heat through changes in state within a narrow temperature range, effectively regulating ambient temperature. They are widely used in building energy conservation, textile temperature regulation, electronic device heat dissipation, and solar thermal utilization. Among them, paraffin wax is one of the most widely used organic PCMs due to its high latent heat of phase change, chemical stability, absence of supercooling and phase separation, and low cost. However, in practical applications, paraffin wax suffers from liquid leakage during solid-liquid phase transitions, and its low thermal conductivity limits its thermal response rate. Furthermore, directly exposed paraffin wax is susceptible to environmental contamination or oxidation, affecting its service life.

[0003] Microencapsulation technology is an effective way to solve the above problems. This technology uses a film-forming material as an outer shell to encapsulate a phase change material (such as paraffin) within a core, forming a microcapsule with a core-shell structure. The dense outer shell not only prevents leakage of the core material in the liquid state but also provides mechanical support and physical protection, increasing the specific surface area. Among the many wall material options, polymeric organic wall materials, while having good film-forming properties, often suffer from drawbacks such as flammability, poor high-temperature resistance, low thermal conductivity, and insufficient mechanical strength. In contrast, inorganic wall materials (such as silica and calcium carbonate) have advantages such as high mechanical strength, good thermal stability, superior thermal conductivity compared to organic materials, and non-flammability, making them more promising for applications in building materials, special coatings, and high-temperature environments.

[0004] With the development of solar energy utilization technology, the single function of heat storage is no longer sufficient to meet the needs of modern multifunctional materials. In order to improve energy utilization efficiency, endowing phase change microcapsules with photothermal conversion function has become a research hotspot. Although current conventional inorganic wall materials (such as pure silica) have solved the problems of leakage prevention and strength, they usually have weak absorption capacity for visible and near-infrared light, making it difficult to directly convert light energy into heat energy and store it in the core material.

[0005] Copper silicate, as a transition metal silicate, not only inherits the excellent mechanical strength, chemical stability, and thermal stability of silicate materials, but also exhibits unique optical absorption characteristics due to its special electronic structure and the presence of copper ions. It possesses particularly good light absorption capabilities in the visible to near-infrared region, making it a potential high-efficiency photothermal conversion and photocatalytic degradation material. Currently, research on the preparation of phase change microcapsules using copper silicate as the wall material and paraffin wax as the phase change core is relatively limited. If copper silicate is used as the inorganic shell and paraffin wax as the phase change core, the prepared microcapsules can not only utilize paraffin wax to achieve high-density thermal energy storage, but also utilize the copper silicate shell to achieve efficient photothermal conversion and catalytic degradation characteristics. Simultaneously, the high mechanical strength and chemical inertness of the copper silicate shell itself allow it to be stably dispersed in the coating as a functional filler. This design overcomes the limitation of traditional phase change microcapsules having only a single function (heat storage) and solves the problem of poor interfacial compatibility when traditional photothermal materials and phase change materials are simply mixed. It provides a new technical approach and theoretical basis for developing novel, high-efficiency photothermal energy storage and anti-fouling coatings. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] To achieve the above objectives, the present invention provides the following technical solution: the core material is an organic phase change material, the shell material is copper silicate, and the mass ratio of the core material to the shell material is 1:0.5 to 1.5.

[0009] As a preferred embodiment of the preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in this invention and their application in coatings, wherein the organic phase change material includes one or more of paraffin-based, fatty acid-based, or sugar alcohol-based materials.

[0010] As a preferred embodiment of the preparation of phase change microcapsules with energy storage and photothermal conversion characteristics described in this invention and their application in coatings, the paraffinic base comprises one or more of n-dodecane, n-tridecane, n-tetradecane, n-pentadecanane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecanane, or n-eicosane.

[0011] As a preferred embodiment of the preparation of phase change microcapsules with energy storage and photothermal conversion characteristics described in this invention and their application in coatings, the fatty acid group includes one or more of octanoic acid, nonanoic acid, capric acid, lauric acid, myristic acid, stearic acid, palmitic acid, oleic acid or erucic acid.

[0012] As a preferred embodiment of the preparation of phase change microcapsules with energy storage and photothermal conversion characteristics described in this invention and their application in coatings, the sugar alcohol group includes one or more of xylitol, D-sorbitol, erythritol, D-mannitol or galactitol.

[0013] This invention provides the following technical solution, which specifically includes the following steps:

[0014] (1) Place the beaker containing 150mL of ultrapure water into a 60℃ magnetic stirring water bath and wait for the ultrapure water to rise to the same temperature as the surrounding environment.

[0015] (2) Further, a certain amount of paraffin and emulsifier were added respectively, and emulsified at a constant stirring rate for 20 minutes to obtain an oil-in-water emulsion;

[0016] (3) Dissolve different masses of copper nitrate and dispensing instant sodium silicate in beakers containing 40 mL of ultrapure water respectively. After complete dissolution, two different precursor solutions are obtained.

[0017] (4) After the paraffin emulsification process is completed, barium nitrate solution is slowly dripped into the core material solution, and stirring is continued for 0.5 h at the same speed. The O in the hydrophilic group of the anionic emulsifier 2- With Cu 2+ When they combine, the emulsion changes from white to transparent.

[0018] (5) Further, the powdered, readily soluble sodium silicate solution was added dropwise into the beaker in the same manner, and the reaction was continued with stirring for 0.5 h. SiO3 2- With Cu 2+ A chemical precipitation reaction occurs, stabilizing the formation of CuSiO3 wall material. This material is further deposited and coated on the surface of the phase change particles to form a continuous and dense inorganic shell structure, causing the solution to gradually become turbid.

[0019] (6) After the reaction was completed, the mixed solution was allowed to stand in cold water for 1 hour. Subsequently, the product was filtered and washed several times with anhydrous ethanol and ultrapure water, and then dried in a vacuum drying oven for 48 hours to obtain white microcapsule powder.

[0020] (7) In order to determine the optimal thermal performance of the phase change microcapsule preparation conditions, a three-factor, three-level orthogonal experiment was conducted to investigate the three factors: stirring rate, sodium dodecylbenzenesulfonate emulsifier dosage, and core / shell ratio.

[0021] As a preferred embodiment of the preparation of phase change microcapsules with energy storage and photothermal conversion characteristics described in this invention and their application in coatings, in step (2): the emulsifier is sodium dodecylbenzenesulfonate.

[0022] As a preferred embodiment of the preparation of phase change microcapsules with energy storage and photothermal conversion characteristics and their application in coatings according to the present invention, in step (2): the constant stirring rate is 700 rpm.

[0023] As a preferred embodiment of the preparation of phase change microcapsules with energy storage and photothermal conversion characteristics described in this invention and their application in coatings, in step (3): the stirring temperature is 60°C.

[0024] As a preferred embodiment of the preparation of phase change microcapsules with energy storage and photothermal conversion characteristics described in this invention and their application in coatings, in step (3): the number of washing cycles is 1 to 5.

[0025] A preferred embodiment of the preparation of phase change microcapsules with energy storage and photothermal conversion characteristics and their application in coatings, wherein in step (6): the temperature of the vacuum drying oven is 30℃~50℃.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention innovatively uses copper silicate as the shell material for microcapsules. Unlike traditional transparent / white inorganic wall materials such as silica or calcium carbonate, copper silicate possesses excellent optical absorption properties, effectively absorbing visible and near-infrared light and converting it into heat energy. After heat energy is generated, it is rapidly transferred to the internally encapsulated paraffin phase change core material for latent heat storage. This integrated design of "photothermal conversion-heat energy storage" significantly improves the utilization efficiency of solar energy and solves the problem that traditional phase change materials cannot actively utilize light energy. Furthermore, utilizing natural light can endow the coating with active temperature regulation capabilities, showing broad application prospects in building energy conservation, solar thermal collector coatings, and special insulation fields.

[0028] Synthesis principle of this invention:

[0029] This invention employs an in-situ interfacial reactive deposition method to prepare copper silicate / paraffin phase change microcapsules with a core-shell structure. The basic principle is to utilize an immiscible oil-water two-phase system to construct a stable reaction template with the assistance of an emulsifier. The encapsulation of the phase change core material is achieved through the directional adsorption and reaction of inorganic precursors at the interface. Specifically, the process includes: construction of an O / W type emulsion template, adsorption and enrichment of the precursor, in-situ reaction and shell growth, and structural regulation mechanisms. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0031] Figure 1 This is a scanning electron microscope image of the phase change microcapsules prepared in Comparative Example 1 of the present invention;

[0032] Figure 2 This is the UV-Vis spectrum of the phase change microcapsules prepared in Comparative Example 1 of this invention.

[0033] Figure 3 This is a test diagram of the photocatalytic degradation performance of the phase change microcapsules prepared in Comparative Example 1 of this invention;

[0034] Figure 4 This is a photothermal conversion test diagram of the phase change microcapsules prepared in Comparative Example 1 of this invention;

[0035] Figure 5 This is a test image of the photocatalytic degradation performance of the coating prepared in Example 10 of the present invention;

[0036] Figure 6 This is a test graph of the thermal conductivity of the coating obtained in Example 10 of the present invention;

[0037] Figure 7 This is a test diagram of the thermal insulation performance of the coating obtained in Example 10 of the present invention. Detailed Implementation

[0038] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0039] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0040] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0041] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0042] Example 1

[0043] This embodiment provides a method for preparing phase change microcapsules with energy storage and photothermal conversion properties and their application in coatings, specifically:

[0044] Place the beaker containing 150mL of ultrapure water into a 60℃ magnetically stirred water bath and wait for the ultrapure water to reach the same temperature as the surrounding environment.

[0045] Further, 0.3g of sodium dodecylbenzenesulfonate emulsifier and 3g of paraffin were added, and the mixture was emulsified at a stirring rate of 700rpm for 20min to obtain an oil-in-water emulsion;

[0046] Furthermore, 2.01g of copper nitrate and 1.31g of powdered instant sodium silicate were dissolved in beakers containing 40mL of ultrapure water, respectively, and stirred at 60℃ for 10min. After complete dissolution, two different precursor solutions were obtained.

[0047] Furthermore, after the emulsification process is completed, barium chloride solution is slowly dripped into the core material solution, and stirring is continued for 0.5 hours at the same speed. The emulsion changes from white to transparent.

[0048] Further, sodium tungstate solution was added dropwise to the beaker in the same manner, and the reaction was continued with stirring for 0.5 hours. As the reaction continued, the solution gradually became cloudy.

[0049] Further, after the reaction was completed, the mixed solution was allowed to stand in cold water for 60 minutes. Subsequently, the product was filtered and washed three times each with anhydrous ethanol and ultrapure water, and then dried in a vacuum drying oven at 40°C for 48 hours to obtain white microcapsule powder.

[0050] Example 2

[0051] The difference between this embodiment and Example 1 is that when the sodium dodecylbenzenesulfonate emulsifier and the core-shell ratio are adjusted to 0.5g and 1:1 respectively, the amount of barium nitrate added is 4.03g and the amount of powdered instant sodium silicate added is 2.62g. The rest of the preparation process is the same as in Example 1, and multifunctional phase change microcapsules are prepared.

[0052] Example 3

[0053] The difference between this embodiment and Example 1 is that when the ratio of sodium dodecylbenzenesulfonate emulsifier to core-shell is adjusted to 0.7g and 1:1.5 respectively, the amount of barium nitrate added is 6.04g and the amount of powdered instant sodium silicate added is 3.93g. The rest of the preparation process is the same as in Example 1, and multifunctional phase change microcapsules are prepared.

[0054] Example 4

[0055] The difference between this embodiment and Example 1 is that when the stirring rate and the core-shell ratio are adjusted to 700 rpm and 1:1 respectively, the amount of barium nitrate added is 4.03 g, and the amount of powdered instant sodium silicate added is 2.62 g. The rest of the preparation process is the same as in Example 1, and multifunctional phase change microcapsules are prepared.

[0056] Example 5

[0057] The difference between this embodiment and Example 4 is that when the sodium dodecylbenzenesulfonate emulsifier and the core-shell ratio are adjusted to 0.5g and 1:1.5 respectively, the amount of barium nitrate added is 6.04g and the amount of powdered instant sodium silicate added is 3.93g. The rest of the preparation process is the same as in Example 4, and multifunctional phase change microcapsules are prepared.

[0058] Example 6

[0059] The difference between this embodiment and Example 4 is that when the ratio of sodium dodecylbenzenesulfonate emulsifier to core shell is adjusted to 0.7g and 1:0.5 respectively, the amount of barium nitrate added is 2.01g and the amount of powdered instant sodium silicate added is 1.31g. The rest of the preparation process is the same as in Example 4, and multifunctional phase change microcapsules are prepared.

[0060] Example 7

[0061] The difference between this embodiment and Example 1 is that when the stirring rate and the core-shell ratio are adjusted to 800 rpm and 1:1.5 respectively, the amount of barium nitrate added is 6.04 g and the amount of powdered instant sodium silicate added is 3.93 g. The rest of the preparation process is the same as in Example 1, and multifunctional phase change microcapsules are prepared.

[0062] Example 8

[0063] The difference between this embodiment and Example 7 is that when the sodium dodecylbenzenesulfonate emulsifier and the core-shell ratio are adjusted to 0.5g and 1:0.5 respectively, the amount of barium nitrate added is 2.01g, and the amount of powdered instant sodium silicate added is 1.31g. The rest of the preparation process is the same as in Example 7, and multifunctional phase change microcapsules are prepared.

[0064] Example 9

[0065] The difference between this embodiment and Example 7 is that when the sodium dodecylbenzenesulfonate emulsifier and the core-shell ratio are adjusted to 0.7g and 1:1 respectively, the amount of barium nitrate added is 4.03g and the amount of powdered instant sodium silicate added is 2.62g. The rest of the preparation process is the same as in Example 7, and multifunctional phase change microcapsules are prepared.

[0066] Example 10

[0067] The prepared phase change microcapsules were added to the coating. First, 30 parts of ultrapure water, 1 part of dispersant, 0.35 parts of wetting agent (acetylenic diol: polyether-modified polytrisiloxane in a weight ratio of 2:1) and 0.25 parts of defoamer were added to a beaker and stirred at high speed for 5 minutes. Then, according to the material density from high to low, 20 parts of rutile TiO2 and 7.5 parts of anatase TiO2 were added sequentially and dispersed for 25 minutes until the slurry fineness met the requirements and stabilized.

[0068] Next, slowly add 100 parts of water-based fluorocarbon resin and 2 parts of film-forming aid, keeping the slurry uniformly mixed for 10 minutes. This is because rapid addition of the resin emulsion can cause localized impact and demulsification. Once the resin and grinding slurry are completely and uniformly mixed, with no streaks or color differences, add 25 parts of the prepared phase change microcapsule sample and 10 parts of hollow glass microspheres sequentially at a low speed, with a stirring time of 15 minutes. The low stirring rate prevents the two materials from breaking, which could lead to coating failure. Subsequently, slowly increase the speed to 500 rpm and add 1 part of thickener (HEUR:ASE60 weight ratio of 7:3) to the slurry to adjust to a suitable viscosity. Maintain this process for 8 minutes, as the thickener needs time to fully associate and establish a stable viscosity network. Finally, add the remaining 0.25 parts of defoamer, maintaining a low speed and continuously stirring for 20 minutes to remove air bubbles. After coating the test plate, allow it to stand and mature for 24 hours before use.

[0069] Comparative Example 1

[0070] This embodiment provides a method for preparing phase change microcapsules with energy storage and photothermal conversion properties and their application in coatings, specifically:

[0071] Place the beaker containing 150mL of ultrapure water into a 60℃ magnetically stirred water bath and wait for the ultrapure water to reach the same temperature as the surrounding environment.

[0072] Further, 0.5g of sodium dodecylbenzenesulfonate emulsifier and 3g of paraffin were added, and emulsification was carried out at a stirring rate of 700rpm for 20min to obtain an oil-in-water emulsion;

[0073] Furthermore, 4.03 g of copper nitrate and 2.62 g of powdered instant sodium silicate were dissolved in beakers containing 40 mL of ultrapure water, respectively, and stirred at 60 °C for 10 min to obtain two different precursor solutions after complete dissolution.

[0074] Furthermore, after the emulsification process is completed, barium chloride solution is slowly dripped into the core material solution, and stirring is continued for 0.5 hours at the same speed. The emulsion changes from white to transparent.

[0075] Further, sodium tungstate solution was added dropwise to the beaker in the same manner, and the reaction was continued with stirring for 0.5 hours. As the reaction continued, the solution gradually became cloudy.

[0076] Further, after the reaction was completed, the mixed solution was allowed to stand in cold water for 60 minutes. Subsequently, the product was filtered and washed three times each with anhydrous ethanol and ultrapure water, and then dried in a vacuum drying oven at 40°C for 48 hours to obtain white microcapsule powder.

[0077] Test Example 1

[0078] The thermophysical properties of the paraffin wax, the phase change microcapsules prepared in Examples 1 to 9, and Comparative Example 1 were tested, and the results are shown in Table 1.

[0079] Table 1. Thermophysical data of phase change microcapsules

[0080] serial number Phase transition temperature (°C) Enthalpy (J / g) Coverage rate (%) paraffin 49.34 154.59 / Example 1 50.24 60.78 39.32 Example 2 51.95 94.48 61.12 Example 3 45.54 75.40 48.77 Example 4 51.81 76.30 49.36 Example 5 52.02 95.35 61.68 Example 6 46.55 70.99 45.92 Example 7 46.83 66.26 42.86 Example 8 49.19 71.10 45.99 Example 9 51.89 86.60 56.02 Comparative Example 1 50.13 103.50 66.95

[0081] Analysis of the thermophysical data in Table 1 shows that, compared to pure paraffin, the enthalpy values ​​of the phase change microcapsule samples in the orthogonal experiments of Examples 1 to 9 were all lower than those of paraffin. This is due to the increased proportion of the outer shell mass in the composite material. Furthermore, the optimal combination of process parameters for the phase change microcapsule samples was determined to be: sodium dodecylbenzenesulfonate emulsifier mass, core / shell ratio, and stirring rate of 700 rpm, 0.5 g, and 1:1, respectively. Insufficient emulsification or supersaturation leading to micelle formation affects the interfacial reaction, both of which are detrimental to efficient encapsulation.

[0082] A 1:1 ratio results in a complete and dense encapsulation. Changing this ratio leads to either insufficient shell material (1:0.5) for complete paraffin encapsulation or excessive shell material (1:1.5) resulting in ineffective copper silicate particles. A stirring speed of 700 rpm strikes a balance, providing sufficient shear force to form fine and uniform emulsion droplets without compromising the structural integrity of the microcapsules due to excessive shear force. Furthermore, the amount of sodium dodecylbenzenesulfonate emulsifier, exhibiting the largest range of results, replaced the traditionally considered critical core / shell ratio as the decisive factor affecting encapsulation efficiency. This result highlights that in interfacial reaction-based synthetic systems, the stability of the initial emulsion may be a critical rate-limiting step for successfully constructing a complete core-shell structure.

[0083] Test Example 2

[0084] Figure 1The image shown is a scanning electron microscope image of the sample in Comparative Example 1. Analysis reveals that the prepared phase change microcapsule sample exhibits a regular and uniform spherical structure with an average particle size of approximately 300 nm, indicating that the interface deposition process can achieve good dispersion and shaping of the core material. Furthermore, experimental results show that the phase change enthalpy and encapsulation efficiency of the phase change microcapsules are closely related to their morphology. When process parameters such as the core / shell mass ratio or stirring speed deviate from the optimal range, both the phase change enthalpy and encapsulation efficiency decrease significantly, demonstrating the incompleteness of the core-shell structure. This proves that process parameters play a decisive role in constructing high-quality microcapsule structures.

[0085] Test Example 3

[0086] The material's ability to respond to sunlight directly determines its practical application potential; relevant test results are as follows: Figures 2 to 4 As shown in Figure 2, the UV-Vis absorption spectrum indicates that the phase change microcapsule sample possesses a wide-bandwidth and robust absorption characteristic in the visible light region. This characteristic is mainly attributed to the dd electron transitions of copper ions in the copper silicate shell. This not only compensates for the limitation of traditional wide-bandgap semiconductors that can only respond to ultraviolet light, but also enables them to effectively capture the visible light portion of solar radiation with the highest energy density, thus laying a solid foundation for subsequent efficient photothermal conversion and photocatalytic reactions.

[0087] As shown in Figure 3, the sample of Comparative Example 1 exhibited excellent catalytic efficiency during the illumination phase. Notably, even after illumination ceased, the system continued to exhibit catalytic degradation behavior, confirming the material's excellent ability to maintain catalytic activity. Furthermore, Figure 4 The temperature-time response curve of Comparative Example 1 under simulated light irradiation is further presented. Experiments show that the sample temperature rapidly increases from 23.6 °C after the onset of light irradiation, reaching 45.6 °C within 50 seconds, confirming that the copper silicate shell, as a high-performance photothermal material, can effectively capture photons and convert them into heat energy. In the 300–600 s range, a distinct temperature plateau appears (approximately 55.2 °C), a typical thermal characteristic of the solid-liquid phase transition of the internally encapsulated paraffin, indicating that the microcapsule possesses excellent temperature buffering and latent heat storage capabilities. After 1200 s of irradiation, the sample reaches thermal equilibrium at 60.4 °C, exhibiting a controlled heat release process after the light source is removed. Calculations show that the photothermal conversion efficiency of this microcapsule sample is as high as 89.4%, significantly better than common titanium dioxide and black titanium dioxide materials prepared by hydrogenation or defect creation, demonstrating excellent potential for solar energy utilization.

[0088] Test Example 5

[0089] This test aims to evaluate the comprehensive performance of the composite coating prepared in this invention in terms of photocatalytic self-cleaning and active thermal management. The relevant test results are as follows: Figures 5 to 7As shown. In terms of photocatalytic purification performance, the methylene blue (MB) degradation experiment revealed that, under visible light irradiation, after eliminating the influence of dark adsorption, the coating exhibited significant organic pollutant degradation efficiency, proving that it can effectively degrade pollutants under visible light-driven conditions, thus endowing the material with excellent self-cleaning function.

[0090] Regarding the intelligent thermal barrier effect, the coating's thermal conductivity test showed that as the ambient temperature increased from 25 °C to 80 °C, the average thermal conductivity of the coating gradually decreased from 0.4189 W / (m·K) to 0.3468 W / (m·K). This characteristic of decreasing thermal conductivity with increasing temperature is attributed to the phonon scattering effect and the material structure differences caused by phase transition. This intelligent thermal barrier effect can significantly delay the impact of external heat waves on the substrate and effectively mitigate temperature fluctuations in the indoor environment or on the surface of equipment.

[0091] Regarding active thermal management performance, the coating surface temperature remains consistently lower than the heat source temperature, with a temperature difference of approximately 7.15 °C, indicating excellent passive thermal insulation performance. In particular, the brief temperature plateau around 50 °C in the heating curve confirms that the coating utilizes the solid-liquid phase change characteristics of typical phase change materials, possessing active heat absorption and temperature regulation capabilities during dynamic heating. In summary, the coating constructed in this invention achieves passive thermal insulation by reducing thermal conductivity and introduces active thermal regulation functionality by combining a phase change mechanism, realizing an integrated technical solution of passive thermal insulation and active thermal management, demonstrating significant application potential in the field of thermal protection.

Claims

1. Preparation of phase change microcapsules with energy storage and photothermal conversion properties and their application in heat-insulating coatings, characterized in that: The phase change microcapsules have a regular core / shell structure, wherein the core material is an organic phase change material, the shell material is copper silicate, and the mass ratio of the core material to the shell material is 1:0.5 to 1.

5.

2. The preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in claim 1 and their application in heat-insulating coatings, characterized in that: The organic phase change material includes one or more of paraffin-based, fatty acid-based, or sugar alcohol-based materials.

3. The preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in claim 2 and their application in heat-insulating coatings, characterized in that: The paraffinic group includes one or more of n-dodecane, n-tridecane, n-tetradecane, n-pentadecanane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecanane, or n-eicosane.

4. The preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in claim 2 and their application in heat-insulating coatings, characterized in that: The fatty acid group includes one or more of the following: caprylic acid, nonanoic acid, capric acid, lauric acid, myristic acid, stearic acid, palmitic acid, oleic acid, or erucic acid.

5. The preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in claim 2 and their application in heat-insulating coatings, characterized in that: The sugar alcohol group includes one or more of xylitol, D-sorbitol, erythritol, D-mannitol, or galactitol.

6. The preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in claim 5 and their application in heat-insulating coatings, characterized in that, Specifically, the following steps are included: (1) Place the beaker containing 150mL of ultrapure water into a 60℃ magnetic stirring water bath and wait for the ultrapure water to rise to the same temperature as the surrounding environment. (2) Further, a certain amount of paraffin and emulsifier were added respectively, and emulsified at a constant stirring rate for 20 minutes to obtain an oil-in-water emulsion; (3) Dissolve different masses of copper nitrate and dispensing instant sodium silicate in beakers containing 40 mL of ultrapure water respectively. After complete dissolution, two different precursor solutions are obtained. (4) After the paraffin emulsification process is completed, barium nitrate solution is slowly dripped into the core material solution, and stirring is continued for 0.5 h at the same speed. The O in the hydrophilic group of the anionic emulsifier 2- With Cu 2+ When they combine, the emulsion changes from white to transparent. (5) Further, the powdered, readily soluble sodium silicate solution was added dropwise into the beaker in the same manner, and the reaction was continued with stirring for 0.5 h. SiO3 2- With Cu 2+ A chemical precipitation reaction occurs, stabilizing the formation of CuSiO3 wall material. This material is further deposited and coated on the surface of the phase change particles to form a continuous and dense inorganic shell structure, causing the solution to gradually become turbid. (6) After the reaction was completed, the mixed solution was allowed to stand in cold water for 1 hour. Subsequently, the product was filtered and washed several times with anhydrous ethanol and ultrapure water, and then dried in a vacuum drying oven for 48 hours to obtain white microcapsule powder. (7) In order to determine the optimal thermal performance of the phase change microcapsule preparation conditions, a three-factor, three-level orthogonal experiment was conducted to investigate the three factors: stirring rate, sodium dodecylbenzenesulfonate emulsifier dosage, and core / shell ratio.

7. The preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in claim 6 and their application in heat-insulating coatings, characterized in that, In step (2): the emulsifier is sodium dodecylbenzenesulfonate.

8. The preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in claim 6 and their application in heat-insulating coatings, characterized in that, In step (2): the constant stirring rate is 700 rpm.

9. The preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in claim 6 and their application in heat-insulating coatings, characterized in that, In step (3): the stirring temperature is 60℃.

10. The preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in claim 6 and their application in heat-insulating coatings, characterized in that, In step (3): the number of washing cycles is 1 to 5.

11. The preparation of phase change microcapsules with energy storage and photothermal conversion characteristics as described in claim 6 and their application in heat-insulating coatings, characterized in that, In step (6): the temperature of the vacuum drying oven is 30℃~50℃.

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