A method for manufacturing a phase change heat insulation automobile coating

Abstract

The application discloses a kind of preparation methods of phase change heat insulation automobile paint, belong to coating preparation technical field, including automobile paint, automobile paint includes thermosetting hydroxyl acrylic resin, heat insulation microparticle, coating solvent, diluent, dispersing agent, rheological aid, leveling agent, ultraviolet absorber;The preparation method includes the following steps: S1, the core layer microparticle is prepared by mixing reflective microparticle and phase change material heated to molten state, S2, the oil phase of methyl methacrylate, core layer microparticle, oil phase solvent, initiator, which is mixed with the water phase of deionized water, emulsifier, is made into emulsion, and the heat insulation microparticle is obtained by heating emulsion and reacting, S3, coating solvent, diluent, thermosetting hydroxyl acrylic resin, heat insulation microparticle, dispersing agent, rheological aid, leveling agent, ultraviolet absorber are sequentially mixed and stirred uniformly to obtain automobile paint;The automobile paint of the application can improve the heat insulation effect of automobile and slow down the amplitude of the temperature rise in the automobile.

Description

Technical Field

[0001] This invention relates to the field of coating manufacturing technology, and specifically to a method for manufacturing a phase change heat-insulating automotive coating. Background Technology

[0002] As people's living standards gradually improve, cars have become increasingly common as a convenient means of transportation. With the increasing demand for cars and their inherent function as a means of transportation, people are paying more attention to driving comfort. At the same time, with global warming leading to more frequent extreme heatwaves, people are demanding higher and higher levels of heat insulation from cars. The main components of a car body are made of metal, which has good thermal conductivity and heats up quickly. When a car is driving on the road or parked outdoors, the temperature inside and outside the car rises rapidly due to sunlight. Air conditioning is usually needed to alleviate the high temperature inside the car, but this increases energy consumption. Therefore, the heat insulation performance of cars is receiving increasing attention. Currently, methods such as applying heat-insulating film and spraying heat-insulating paint are commonly used to improve the heat insulation performance of cars.

[0003] Chinese Patent Publication No. CN115838551A discloses a water-based photosensitive color-changing heat-insulating automotive coating and its preparation method, comprising the following components: water-based epoxy acrylic dispersion, pH adjuster, deionized water, heat-insulating nanoparticles, photosensitive color-changing pigment, methylated amino resin, and additives; the preparation method of the automotive coating includes: S1, weighing each component according to the ratio; S2, mixing water, water-based epoxy-modified hydroxy acrylic dispersion, pH adjuster, film-forming aid, dispersant, wetting agent, heat-insulating nanoparticles, photosensitive color-changing pigment, and flame retardant to obtain a mixture; S3, sequentially adding defoamer, amino resin, and thickener to the above mixture to adjust to a suitable viscosity and stirring until the material is uniform to obtain the automotive coating.

[0004] The aforementioned automotive coating exhibits good heat insulation performance through heat-insulating nanoparticles. It uses photosensitive color-changing pigments to alter the car body color in different environments. In high-temperature environments, the coating color lightens, reducing its efficiency in absorbing solar energy. However, the depth of the coating color has a relatively small impact on the car's heat insulation effect. Furthermore, the heat insulation effect achieved through color change depends on the depth of the car body color, making it only suitable for darker-colored cars such as black cars. Moreover, according to vehicle registration requirements, the color change of a car body cannot exceed 30%. Therefore, it is evident that this automotive coating cannot significantly improve the car's heat insulation effect through color change, and there is still room for improvement. Summary of the Invention

[0005] To address the technical deficiencies in the background art, this invention proposes a method for manufacturing a phase change heat-insulating automotive coating, which solves the aforementioned technical problems and meets practical needs. The specific technical solution is as follows:

[0006] A method for manufacturing a phase change heat-insulating automotive coating includes an automotive coating comprising the following components by mass percentage: 45%-57% thermosetting hydroxyl acrylic resin, 20%-30% heat-insulating microparticles, 10%-15% coating solvent, 3%-7% diluent, 2%-4% dispersant, 1%-3% rheology modifier, 0.5%-1% leveling agent, and 0.5%-1% ultraviolet absorber; wherein the heat-insulating microparticles consist of a microparticle shell encapsulating a phase change material and reflective microparticles, and the microparticle shell is made of an organic monomer through an interfacial free radical polymerization reaction, wherein the organic monomer is selected as methyl methacrylate;

[0007] The method for manufacturing the automotive coating includes the following steps:

[0008] S1, reflective microparticles are added to a phase change material heated to a molten state, stirred evenly, filtered, cooled and solidified to obtain a core layer of microparticles encapsulating reflective microparticles in the phase change material;

[0009] S2, deionized water and emulsifier are mixed and stirred evenly to obtain an aqueous phase, organic monomer, core layer microparticles, oil phase solvent and initiator are mixed and stirred evenly to obtain an oil phase, the aqueous phase is added to the oil phase and stirred evenly, and then treated with ultrasound to form an emulsion, nitrogen gas is introduced into the emulsion and heated to carry out the reaction, and after the reaction is complete, it is filtered and dried to obtain heat insulation microparticles.

[0010] S3, mix the coating solvent and diluent evenly to obtain mixture A, add thermosetting hydroxy acrylic resin, heat insulation particles and dispersant to mixture A and stir evenly to obtain mixture B, add rheology modifier, leveling agent and ultraviolet absorber to mixture B and stir evenly to obtain automotive coating.

[0011] As a further technical solution of the present invention, the coating solvent is cyclohexanone.

[0012] As a further technical solution of the present invention, the diluent is selected from one or both of propylene glycol ether and ethyl acetate, the dispersant is selected from one of silicate and phosphate, the rheology modifier is selected from aromatic diurea compound, the leveling agent is selected from polyether modified organosilicon, and the ultraviolet absorber is selected from benzimidazole compound.

[0013] As a further technical solution of the present invention, the oil phase solvent is selected as n-butyl acetate, the initiator is selected as benzoyl peroxide, and the emulsifier is selected as sodium dodecyl sulfonate.

[0014] As a further technical solution of the present invention, the reflective microparticles are composed of glass microspheres and a reflective coating on the surface. The diameter of the glass microspheres is 20-40 μm, and the reflective coating is a metallic silver plating layer formed by immersing the glass microspheres in a solution containing silver ions using a chemical deposition method. The thickness of the reflective coating is 3-7 μm.

[0015] As a further technical solution of the present invention, the thickness of the phase change material on the surface of the core microparticles is 15-30 μm, the thickness of the microparticle shell is 1-4 μm, and the diameter of the heat-insulating microparticles is 50-80 μm.

[0016] As a further technical solution of the present invention, the phase change material is selected from paraffin wax, and in step S1, the temperature at which the phase change material is heated to a molten state is 50-70℃.

[0017] As a further technical solution of the present invention, in step S2, the mixture of water phase and oil phase is emulsified into an emulsion by generating high-frequency ultrasonic vibration through an ultrasonic emulsifier. The frequency of the ultrasonic emulsifier is 25-30kHz and the amplitude is 80-100μm.

[0018] As a further technical solution of the present invention, in step S2, the temperature at which the emulsion is heated to react is 40-50℃.

[0019] The beneficial effects of this invention are as follows:

[0020] The main component of the automotive coating of the present invention is thermosetting hydroxy acrylic resin. After curing, the thermosetting hydroxy acrylic resin has good transparency and bright gloss, and is preferably used as a clear coat on the surface of automobiles. The heat-insulating microparticles in the automotive coating use paraffin as a phase change material. Paraffin has a definite phase change temperature, a high latent heat of phase change and good chemical stability. During the phase change process of paraffin caused by temperature rise, paraffin can absorb a large amount of heat, reduce the energy transferred to the interior of the automobile when exposed to sunlight, thereby slowing down the rate of temperature rise inside the automobile.

[0021] The shell of the heat-insulating microparticles is composed of polymethyl methacrylate with good light transmittance. When paraffin absorbs a large amount of heat and changes from solid to liquid, its color changes from white to transparent. Sunlight can pass through the paraffin and shine on the surface of the reflective microparticles. The reflective microparticles can reflect sunlight and the energy carried by sunlight, thereby reducing the amount of sunlight directly hitting the car surface, achieving a heat insulation effect, and further slowing down the rate of temperature rise inside the car. Detailed Implementation

[0022] The embodiments of the present invention will be described below with reference to relevant examples. The embodiments of the present invention are not limited to the following examples, and the present invention relates to relevant necessary components in this technical field, which should be regarded as well-known technology in this technical field and can be known and mastered by those skilled in this technical field.

[0023] A method for manufacturing a phase change heat-insulating automotive coating includes an automotive coating comprising the following components by mass percentage: 45%-57% thermosetting hydroxy acrylic resin, 20%-30% heat-insulating microparticles, 10%-15% coating solvent, 3%-7% diluent, 2%-4% dispersant, 1%-3% rheology modifier, 0.5%-1% leveling agent, and 0.5%-1% ultraviolet absorber; the heat-insulating microparticles consist of a microparticle shell encapsulating a phase change material and reflective microparticles, the microparticle shell being made of an organic monomer through an interfacial free radical polymerization reaction, the organic monomer being methyl methacrylate;

[0024] The method for manufacturing automotive paint includes the following steps:

[0025] S1, reflective microparticles are added to a phase change material heated to a molten state, stirred evenly, filtered, cooled and solidified to obtain a core layer of microparticles encapsulating reflective microparticles in the phase change material;

[0026] S2, deionized water and emulsifier are mixed and stirred evenly to obtain an aqueous phase, organic monomer, core layer microparticles, oil phase solvent and initiator are mixed and stirred evenly to obtain an oil phase, the aqueous phase is added to the oil phase and stirred evenly and then treated with ultrasound to form an emulsion, nitrogen gas is introduced into the emulsion and heated to carry out the reaction, and after the reaction is complete, it is filtered and dried to obtain heat insulation microparticles.

[0027] S3, mix the coating solvent and diluent evenly to obtain mixture A, add thermosetting hydroxy acrylic resin, heat insulation particles and dispersant to mixture A and stir evenly to obtain mixture B, add rheology modifier, leveling agent and ultraviolet absorber to mixture B and stir evenly to obtain automotive coating.

[0028] The automotive coating of the present invention comprises the following components by mass percentage: 51% thermosetting hydroxy acrylic resin, 25% heat-insulating microparticles, 12.5% ​​coating solvent, 5% diluent, 3% dispersant, 2% rheology modifier, 0.75% leveling agent, and 0.75% ultraviolet absorber; wherein, the coating solvent is cyclohexanone, the diluent is a mixture of propylene glycol ether and ethyl acetate in a 1:1 mass ratio, the dispersant is sodium metasilicate, the rheology modifier is an aromatic diurea compound, the leveling agent is a polyether-modified organosilicon, and the ultraviolet absorber is a benzimidazole compound.

[0029] The automotive coating of this invention is mainly based on thermosetting hydroxy acrylic resin. The coating prepared by thermosetting hydroxy acrylic resin has excellent chemical resistance and high temperature resistance. It can work stably in harsh chemical environments such as acids, alkalis, and solvents, as well as in high temperature environments, thereby ensuring that the automotive coating maintains good performance under various environmental conditions. It is mainly used as an automotive clear coat. After the automotive coating is applied to the surface of the car and heated and cured, it serves as the outermost protective layer of the car paint, which can protect the car's color paint and maintain its color and gloss for a long time.

[0030] Cyclohexanone, as a solvent in automotive coatings, has good environmental friendliness and solubility. It can effectively dissolve thermosetting hydroxyl acrylic resins to form solution-like coatings. Cyclohexanone has characteristics such as stable molecular structure, low volatility, and non-flammability. It can also increase the gloss and transparency of automotive coatings, making the car paint appear brighter. At the same time, cyclohexanone may also act as a diluent, reducing the viscosity of automotive coatings and improving their fluidity, making them easier to apply.

[0031] Propylene glycol ethers and ethyl acetate are used as diluents for automotive coatings. Propylene glycol ethers can improve the coatability, flowability, adhesion, flexibility, and extensibility of automotive coatings, as well as improve coating performance, making it easier for automotive coatings to cover the automotive surface and form a coating. Ethyl acetate may play a role in dissolving and mixing other components in automotive coatings, helping automotive coatings maintain a uniform texture, and may help improve the leveling and coatability of automotive coatings.

[0032] Sodium metasilicate, as a dispersant in automotive coatings, possesses excellent dispersion stability, high-temperature stability, and a large specific surface area and adsorption capacity. It can be effectively adsorbed onto the surface of heat-insulating microparticles, forming a stable film on the surface of the microparticles to prevent agglomeration and uniformly disperse in the automotive coating. This reduces the aggregation tendency of the heat-insulating microparticles and improves the anti-settling and rheological properties of the automotive coating.

[0033] Aromatic diurea compounds, as rheology modifiers in automotive coatings, can adjust the flowability of automotive coatings, making the coating more uniform and smooth during the application process and reducing sagging, thereby improving the coating performance of automotive coatings. Rheology modifiers can also prevent the sedimentation and stratification of solid particles such as heat-insulating microparticles in automotive coatings, improving the stability and reliability of automotive coatings.

[0034] Polyether-modified silicone is used as a leveling agent in automotive coatings. Leveling agents can reduce the viscosity and surface tension of automotive coatings, reduce the formation of pores in the coating after application, and prevent defects such as pinholes, orange peel, and ripples on the coating surface, thereby making the coating surface smoother and more even. Leveling agents can also improve the stability of automotive coatings, enabling them to maintain better performance during storage and use, and avoiding problems such as delamination and deterioration that may occur during storage.

[0035] Benzimidazole compounds, as ultraviolet absorbers in automotive coatings, can effectively inhibit material degradation caused by ultraviolet rays, oxygen, high temperature and other environmental factors, and improve the anti-aging performance and durability of the coating formed after automotive coating is applied.

[0036] In step S1, after the reflective microparticles are added to the phase change material heated to a molten state, the phase change material will coat the surface of the reflective microparticles. Then, the excess phase change material is removed by passing it through a filter with a pore size smaller than the diameter of the reflective microparticles. Next, the obtained solid product is passed through a filter with a pore size larger than the diameter of the reflective microparticles to disperse the core layer microparticles coated with the phase change material. After the phase change material on the surface of the core layer microparticles solidifies, the core layer microparticles can be added to the phase change material heated to a molten state again. The above operation is repeated to ensure that the phase change material coats the surface of the reflective microparticles. After the above operation is completed, the core layer microparticles coated with the phase change material are obtained.

[0037] In step S2, the aqueous phase and oil phase are mixed and stirred evenly, and then the mixture is emulsified into an emulsion by generating high-frequency ultrasonic vibration through an ultrasonic emulsifier. The frequency of the ultrasonic emulsifier is 25-30kHz and the amplitude is 80-100μm. In this process, the organic monomers and the oil phase solvent form oil droplets that coat the surface of the core layer microparticles to form emulsion droplets. The emulsion droplets are evenly dispersed in the two-phase mixture to form an emulsion. When nitrogen gas is introduced into the emulsion and heated to 40-50℃, the initiator generates free radicals at the interface between the oil phase and the aqueous phase, which initiates the polymerization reaction of the organic monomers, namely, the polymerization of methyl methacrylate to form polymethyl methacrylate. This forms a microparticle shell composed of polymethyl methacrylate on the surface of the core layer microparticles. After the reaction is complete, the microparticles are filtered and dried to obtain heat-insulating microparticles with the microparticle shell coating the core layer microparticles.

[0038] In step S3, the coating solvent and diluent are mixed and stirred evenly to obtain mixture A. Mixture A is used to dissolve the various components in the automotive coating and serves as a carrier for dispersing heat-insulating microparticles. After adding thermosetting hydroxy acrylic resin, heat-insulating microparticles, and dispersant to mixture A, the thermosetting hydroxy acrylic resin and dispersant dissolve in mixture A, while the heat-insulating microparticles are uniformly dispersed in mixture A under the action of the dispersant, thus obtaining mixture B. Finally, rheology modifiers, leveling agents, and ultraviolet absorbers are added to mixture B and stirred evenly to obtain the automotive coating. Rheology modifiers and leveling agents can improve the coating performance, stability, reliability, and other properties of automotive coatings, while ultraviolet absorbers can improve the anti-aging performance and durability of the coating formed after the automotive coating is applied.

[0039] The automotive coating produced through the above steps is mainly composed of thermosetting hydroxyl acrylic resin. After curing, the thermosetting hydroxyl acrylic resin exhibits good transparency and a bright gloss, making it ideal for use as a clear coat on automotive surfaces. It can also be used as a heat-insulating coating for transparent materials such as glass. The thickness of the heat-insulating coating formed on the automotive surface is typically 100-200 μm. The automotive coating contains 20%-30% heat-insulating microparticles, with paraffin wax serving as the phase change material. Paraffin wax possesses a defined phase change temperature, high latent heat of phase change, and good chemical stability. During the phase change process caused by temperature increases, paraffin wax absorbs a large amount of heat. When a car is exposed to sunlight in an open-air environment, the heat-insulating coating can absorb a large amount of energy from sunlight, reducing the energy transferred to the car's interior and thus slowing down the rate of temperature rise inside the car. The shell of the heat-insulating microparticles is composed of polymethyl methacrylate (PMMA), which has good light transmittance. When paraffin absorbs heat and changes from a solid to a liquid state, its color changes from white to transparent. Sunlight can pass through the paraffin and shine on the surface of the reflective microparticles. The reflective microparticles can reflect sunlight and the energy carried by sunlight, thereby reducing the amount of sunlight directly hitting the car's surface, achieving a heat insulation effect, and further slowing down the rate of temperature rise inside the car.

[0040] In one of the preferred embodiments of the present invention, the oil phase solvent is selected as n-butyl acetate, the initiator is selected as benzoyl peroxide, and the emulsifier is selected as sodium dodecyl sulfonate.

[0041] In step S2 of this invention, the emulsion uses n-butyl acetate as the solvent of the oil phase, and sodium dodecyl sulfonate is mixed with water to form the aqueous phase. Sodium dodecyl sulfonate can dissolve in water and reduce the interfacial tension of water. N-butyl acetate can dissolve methyl methacrylate without being miscible with water. In the emulsion, under the action of sodium dodecyl sulfonate, the oil phase is uniformly dispersed to form small droplets, which are then mixed with the aqueous phase to form the emulsion. When the temperature of the emulsion rises, the initiator generates free radicals at the interface between the small droplets and the aqueous phase to promote the polymerization reaction of organic monomers and form a microparticle shell.

[0042] As one of the preferred embodiments of the present invention, the reflective microparticles are composed of glass microspheres and a reflective coating on the surface. The diameter of the glass microspheres is 20-40 μm, and the reflective coating is a metallic silver plating layer formed by chemical deposition of the glass microspheres in a solution containing silver ions. The thickness of the reflective coating is 3-7 μm.

[0043] The glass microspheres preferably have a hollow structure, which can reduce the density of the core microparticles and allow them to be better suspended and dispersed in the oil phase. The glass microspheres are immersed in a solution containing silver ions and a smooth metallic silver coating is formed by chemical deposition. This metallic silver coating is a reflective coating, which can form a reflective mirror on the surface of the glass microspheres, thereby reflecting the incoming light.

[0044] As one of the preferred embodiments of the present invention, the thickness of the phase change material on the surface of the core microparticles is 15-30 μm, the thickness of the microparticle shell is 1-4 μm, and the diameter of the heat-insulating microparticles is 50-80 μm.

[0045] The core layer microparticle surface phase change material is made by adding reflective microparticles into a phase change material heated to a molten state, stirring evenly, filtering, cooling and solidifying. In order to ensure the content and thickness of the phase change material in the heat insulation microparticles, it is usually necessary to repeatedly immerse the reflective material in the molten phase change material. The diameter of the heat insulation microparticles is about 30%-50% of the thickness of the heat insulation coating to avoid the heat insulation microparticles being too large and affecting the coating of automotive paint.

[0046] As one of the preferred embodiments of the present invention, paraffin wax is selected as the phase change material, and in step S1, the temperature at which the phase change material is heated to a molten state is 50-70°C.

[0047] The phase change material used in this invention is paraffin wax. Solid paraffin wax is white and opaque. Paraffin wax begins to undergo a phase change at temperatures above approximately 28°C, absorbing a large amount of heat. Paraffin wax needs to be heated to 50-60°C to transform into a molten state. Molten paraffin wax is transparent. In the heat-insulating microparticles of this invention, paraffin wax is used as the phase change material because it is an opaque solid in its normal state. In low-temperature environments such as at night, light will not pass through the phase change material and shine on the surface of the reflective microparticles, thus preventing the heat-insulating microparticles from reflecting light. Specifically, when a car is driving at night, the heat-insulating coating on the car surface will not excessively reflect the lights of other vehicles or other lights due to the reflective microparticles, thereby ensuring the driving safety of other vehicles.

[0048] It should be noted that the reflective particles are spherical. In environments with strong sunlight during the day, the reflective particles will reflect sunlight in the form of scattering. However, in well-lit environments during the day, this form of reflection will not affect the vision of other drivers.

[0049] The present invention will be further illustrated below through examples and comparative examples.

[0050] Example 1

[0051] S1, the reflective microparticles are added to the molten paraffin wax and stirred evenly, then filtered and cooled to solidify. The reflective microparticles are then repeatedly added to the molten paraffin wax for impregnation. Finally, the particles are filtered and cooled to solidify to obtain the core layer microparticles of the reflective microparticles encapsulated in paraffin wax.

[0052] S2, 20 parts of deionized water and 3 parts of sodium dodecyl sulfonate are mixed and stirred evenly to obtain an aqueous phase. 20 parts of methyl methacrylate, 30 parts of core layer microparticles, 20 parts of n-butyl acetate and 0.6 parts of benzoyl peroxide are mixed and stirred evenly to obtain an oil phase. The aqueous phase is added to the oil phase and stirred evenly. An emulsion is formed by ultrasonic treatment. Nitrogen gas is introduced into the emulsion and heated to 50°C to carry out the reaction. After the reaction is complete, the mixture is filtered and dried to obtain heat-insulating microparticles.

[0053] S3, mix 13 parts cyclohexanone, 3 parts propylene glycol ether, and 3 parts ethyl acetate to obtain mixture A. Add 50 parts thermosetting hydroxy acrylic resin, 25 parts heat-insulating microparticles, and 3 parts dispersant to mixture A and stir to obtain mixture B. Add 2 parts rheology modifier, 0.7 parts leveling agent, and 0.7 parts ultraviolet absorber to mixture B and stir to obtain automotive coating.

[0054] S4. Coat the surface of the metal plate with a layer of commercially available white automotive paint. After the automotive paint has cured, apply the automotive coating from step S3 onto the surface of the automotive paint and heat it to cure the automotive coating.

[0055] Example 2

[0056] The difference between this embodiment and the above embodiment 1 is that in step S4, the white car paint is replaced with black car paint, while the other operation steps remain unchanged.

[0057] Comparative Example 1

[0058] Referring to Chinese Patent No. CN115838551A, a water-based photosensitive color-changing heat-insulating automotive coating and its preparation method, the automotive coating obtained according to Example 4 in the patent specification was applied to the surface of a metal plate. After the automotive coating was cured, a layer of commercially available transparent automotive clear coat was applied to the surface, and the clear coat was heated to cure.

[0059] Comparative Example 2

[0060] The difference between this comparative example and Comparative Example 1 above is that the photochromic pigment in the automotive coating is replaced with ordinary white pigment, while the other operating steps remain unchanged.

[0061] Comparative Example 3

[0062] The difference between this comparative example and Comparative Example 1 above is that the photochromic pigment in the automotive coating is replaced with a regular black pigment, while the other operating steps remain unchanged.

[0063] The metal plates obtained in Examples 1 and 2 and Comparative Examples 1, 2, and 3 were used to construct 1m*1m*1m test spaces. All six sides of the test space were composed of metal plates, with the side coated with automotive paint facing outwards. A thermometer was placed in the center of the test space, and the test space was placed in an open outdoor environment and exposed to sunlight. The temperature readings of the thermometers were recorded over time, as shown in Table 1 below.

[0064]

[0065] Table 1

[0066] Based on the data in Table 1, the temperature data of Examples 1 and 2, and Comparative Examples 2 and 3 were compared. The highest temperature difference in the test space between the black paint and the white paint was 1-2℃, and the highest temperature in the test space of the black paint was higher. In addition, during the test, the color of the metal plate of Comparative Example 1 gradually changed from close to black to close to white. Combining the temperature data of Comparative Examples 1, 2, and 3, the highest temperature in the test space of Comparative Example 1 was between that of Comparative Examples 2 and 3. It can be seen that the depth of the color of the metal plate surface affects the temperature in the test space, and the darker the color, the higher the temperature in the test space. Compared with black pigment, photosensitive color-changing pigment can reduce the highest temperature in the test space to a certain extent through color change. However, the cooling effect of photosensitive color-changing pigment is not as good as that of white pigment. Furthermore, according to the requirements for automobile registration, the color change of the automobile body cannot exceed 30%, while the color change of Comparative Example 1 in the above test has far exceeded 30%. The effect of photosensitive color-changing pigment that meets the requirements on temperature will only be lower. Therefore, the effect of improving the heat insulation performance of automobiles through the color-changing characteristics of photosensitive color-changing pigment is not ideal.

[0067] Furthermore, the time it took for the test space in Example 1 to reach its maximum temperature was between 2400-3000 s, the time it took for the test space in Example 2 to reach its maximum temperature was between 1800-2400 s, the time it took for the test space in Comparative Example 1 to reach its maximum temperature was between 1500-1800 s, the time it took for the test space in Comparative Example 2 to reach its maximum temperature was between 1500-1800 s, and the time it took for the test space in Comparative Example 3 to reach its maximum temperature was between 1200-1500 s. It can be seen that Examples 1 and 2 using the technical solution of the present invention can reduce the rate of temperature rise in the test space and have a better heat insulation effect. The maximum temperature data obtained by testing with the same color paint is 6-7℃ lower than that of the comparative examples. It can be seen that in the technical solution of the present invention, the heat absorption of phase change materials can slow down the rate of temperature rise, and the reflection of sunlight by reflective particles can achieve a good heat insulation effect.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for manufacturing a phase change heat-insulating automotive coating, characterized in that, The automotive coating comprises the following components by weight percentage: 45%-57% thermosetting hydroxy acrylic resin, 20%-30% heat-insulating microparticles, 10%-15% coating solvent, 3%-7% diluent, 2%-4% dispersant, 1%-3% rheology modifier, 0.5%-1% leveling agent, and 0.5%-1% UV absorber; the heat-insulating microparticles consist of a microparticle shell encapsulating a phase change material and reflective microparticles, the microparticle shell being made from an organic monomer through an interfacial free radical polymerization reaction, wherein the organic monomer is selected as methyl methacrylate; The reflective microparticles consist of glass microspheres and a reflective coating on the surface. The diameter of the glass microspheres is 20-40 μm, and the reflective coating is a metallic silver plating formed by immersing the glass microspheres in a solution containing silver ions and using a chemical deposition method. The thickness of the reflective coating is 3-7 μm. The method for manufacturing the automotive coating includes the following steps: S1, reflective microparticles are added to a phase change material heated to a molten state, stirred evenly, filtered, cooled and solidified to obtain a core layer of microparticles encapsulating reflective microparticles in the phase change material; S2, deionized water and emulsifier are mixed and stirred evenly to obtain an aqueous phase, organic monomer, core layer microparticles, oil phase solvent and initiator are mixed and stirred evenly to obtain an oil phase, the aqueous phase is added to the oil phase and stirred evenly, and then treated with ultrasound to form an emulsion, nitrogen gas is introduced into the emulsion and heated to carry out the reaction, and after the reaction is complete, it is filtered and dried to obtain heat insulation microparticles. The thickness of the phase change material on the surface of the core microparticles is 15-30 μm, the thickness of the microparticle shell is 1-4 μm, and the diameter of the heat-insulating microparticles is 50-80 μm. S3, mix the coating solvent and diluent evenly to obtain mixture A, add thermosetting hydroxy acrylic resin, heat insulation particles and dispersant to mixture A and stir evenly to obtain mixture B, add rheology modifier, leveling agent and ultraviolet absorber to mixture B and stir evenly to obtain automotive coating.

2. The method for manufacturing the phase change heat-insulating automotive coating according to claim 1, characterized in that, The solvent used in the coating is cyclohexanone.

3. The method for manufacturing the phase change heat-insulating automotive coating according to claim 1, characterized in that, The diluent is selected from one or both of propylene glycol ether and ethyl acetate; the dispersant is selected from one of silicate and phosphate; the rheology modifier is selected from aromatic diurea compounds; the leveling agent is selected from polyether-modified organosilicon; and the ultraviolet absorber is selected from benzimidazole compounds.

4. The method for manufacturing the phase change heat-insulating automotive coating according to claim 1, characterized in that, The oil phase solvent is selected as n-butyl acetate, the initiator is selected as benzoyl peroxide, and the emulsifier is selected as sodium dodecyl sulfonate.

5. The method for manufacturing the phase change heat-insulating automotive coating according to claim 1, characterized in that, The phase change material is selected from paraffin wax. In step S1, the phase change material is heated to a molten state at a temperature of 50-70°C.

6. The method for manufacturing the phase change heat-insulating automotive coating according to claim 1, characterized in that, In step S2, the mixture of water and oil phases is emulsified into an emulsion by generating high-frequency ultrasonic vibrations using an ultrasonic emulsifier. The ultrasonic emulsifier has a frequency of 25-30 kHz and an amplitude of 80-100 μm.

7. The method for manufacturing the phase change heat-insulating automotive coating according to claim 1, characterized in that, In step S2, the temperature at which the emulsion is heated to react is 40-50°C.

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