Thermal insulation coating for aluminum material as well as preparation method and application of thermal insulation coating

Abstract

The invention discloses a thermal insulation coating for an aluminum material and a preparation method and application of the thermal insulation coating, and belongs to the technical field of functional coating preparation. 5-8 parts of a heat insulation filler; 10-15 parts of a thermal insulation filler; 6-8 parts of a coupling agent; 42 to 54 parts of resin; 8-9 parts of a modifier; and 75 to 85 parts of a solvent. The heat insulation temperature difference of the heat insulation and heat preservation coating is 20-25 DEG C, the cold insulation temperature difference can reach 8-12 DEG C, the heat insulation and heat preservation coating has good heat insulation and cold insulation performance, and the technical problem that when an existing heat insulation and heat preservation coating deals with temperature changes, bidirectional temperature insulation protection cannot be provided is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional coating preparation, and particularly relates to a heat-insulating and heat-preserving coating for aluminum materials, a preparation method thereof, and an application thereof. Background Art

[0002] Due to its excellent characteristics such as light weight, high strength, corrosion resistance, good processing performance, and strong recyclability, aluminum materials are widely used in fields such as construction, transportation, furniture manufacturing, and industrial equipment. However, the thermal conductivity of aluminum materials is relatively high, much higher than that of most metal materials, which results in poor heat-insulating and heat-preserving performance. In daily life, aluminum materials with high thermal conductivity and high emissivity also bring many inconveniences. In winter, aluminum furniture at home feels extremely cold, causing discomfort. In the fields of building doors and windows, curtain walls, and industrial equipment, the high thermal conductivity of aluminum materials easily leads to heat loss, resulting in energy waste and reduced usage efficiency. In the context of the increasing requirements for modern building energy conservation and industrial energy conservation, how to effectively improve the heat-insulating and heat-preserving performance of aluminum materials has become an important technical problem to be solved urgently.

[0003] Currently, there are mainly three methods to improve the heat-insulating performance of aluminum materials. One is the physical heat-insulating method, such as embedding a heat-insulating strip in the middle of aluminum doors and windows (commonly known as the broken bridge aluminum technology), thereby reducing heat conduction. Although this method can significantly improve the heat-insulating effect, it increases the production complexity and cost, and has relatively high requirements for the structural design of profiles. The second is the composite material method, which improves the heat-insulating performance of aluminum materials by adding non-metallic materials or composite structures to aluminum materials. However, this method often has a certain impact on the mechanical properties and processing performance of aluminum materials, restricting its wide application. The third is to coat a heat-insulating coating on the surface to achieve heat insulation by reflecting solar radiation heat or reducing the heat conduction performance. Moreover, the heat-insulating coating has advantages such as simple preparation, low cost, and wide application range.

[0004] However, the preparation technology of heat insulation and heat preservation coatings commonly applied to aluminum materials is complex, which is not conducive to large-scale industrial production. For example, in the patent "A composite coating for the surface of aluminum alloy", the application publication number is CN 209537369 U. This composite coating consists of a bottom coating, a hollow ceramic microsphere powder coating, a raw lacquer latex layer, a micro silica aerogel coating, and a top coating. The multi-coating structure means a complex production process, involving the sequential coating and curing of multiple coatings, and requires precise control of parameters such as the thickness and uniformity of each coating. The coating method is complex, which requires more advanced equipment and more manpower input, thus increasing production costs. In addition, most of the existing heat insulation and heat preservation coatings on the market only have a single heat insulation property and do not have a cold insulation property. For example, in the patent "Heat insulation coating and preparation method", the application publication number is CN 109021728 A, and the heat insulation temperature difference is only 9°C. The low heat insulation temperature difference performance is difficult to meet the stringent requirements in actual application scenarios, cannot play an effective role in heat insulation and heat preservation, and lacks a cold insulation function. When dealing with temperature changes, it cannot provide two-way temperature isolation protection and is difficult to meet the usage scenarios with certain requirements for temperature control.

[0005] In the patent "A heat insulation and radiation protection coating and its preparation method", the application publication number is CN113462272B. This coating is designed by connecting infrared reflection fillers, heat insulation fillers and resins through coupling agents, and controlling the distribution of fillers in the coating to prepare a coating with high hemispherical emissivity and solar reflectivity; good heat insulation performance, corrosion resistance, artificial aging resistance and weather resistance. However, this coating only has a single heat insulation property and does not have a cold insulation property. When dealing with temperature changes, it cannot provide two-way temperature isolation protection.

[0006] Therefore, it is of great significance to develop a coating with excellent heat insulation and heat preservation performance, simple preparation method and low cost to meet the multiple needs of building energy conservation, furniture manufacturing, industrial equipment heat preservation and low-carbon environmental protection. Summary of the Invention

[0007] In order to overcome the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a heat insulation and heat preservation coating for aluminum materials, its preparation method and application, so as to solve the technical problem that the existing heat insulation and heat preservation coatings cannot play an effective role in heat insulation and heat preservation, lack a cold insulation function, and cannot provide two-way temperature isolation protection when dealing with temperature changes.

[0008] In order to achieve the above purpose, the present invention adopts the following technical solutions: The present invention provides a heat insulation and heat preservation coating for aluminum materials, which includes the following raw materials in parts by weight: Low-emissivity filler: 25 - 27 parts; Heat insulation filler: 5 - 8 parts; Heat preservation filler: 10 - 15 parts; Coupling agent: 6 - 8 parts; Resin: 42 - 54 parts; Modifier: 8 - 9 parts; Solvent: 75 - 85 parts.

[0009] Preferably, the low - emissivity filler includes one or more of barium sulfate, titanium dioxide, zinc oxide, and zirconium oxide.

[0010] Preferably, the heat - insulating filler includes one or more of glass hollow microspheres, silica hollow microspheres, and zirconium oxide hollow microspheres.

[0011] Preferably, the heat - insulating filler includes one or more of silica, zirconium oxide, boron nitride, and titanium dioxide.

[0012] Preferably, the modifier includes tetraethyl orthosilicate.

[0013] Preferably, the coupling agent includes one of amino - silane coupling agent, epoxy - silane coupling agent, allyltrimethoxysilane coupling agent, and titanate coupling agent.

[0014] Preferably, the titanate coupling agent includes isopropyl tri(isostearoyl) titanate or isopropyl tri(dioctylpyrophosphato) titanate.

[0015] Preferably, the resin includes one of epoxy resin, acrylic resin, silicone resin, and fluorocarbon resin.

[0016] More preferably, the solvent includes ethanol.

[0017] More preferably, the size of the heat - insulating filler is 1μm - 20μm. The heat - insulating filler with a size of 1μm - 20μm can better fill the gaps in the coating, make the coating more dense, and reduce the heat transfer through pores.

[0018] More preferably, the thickness of the heat - insulating and heat - preserving coating is 30μm - 60μm. The coating is thin and has excellent heat - insulating performance at the same time.

[0019] The coating combines low-emissivity fillers and heat-insulating fillers to form a composite filler. This innovative composite structure not only combines the radiation shielding performance of low-emissivity fillers and the heat-insulating performance of heat-insulating fillers, but also enhances the interfacial bonding force between the fillers and the resin matrix through the action of modifiers and coupling agents, thereby improving the overall performance of the coating. In the composite filler, the low-emissivity filler can effectively reflect and scatter the radiation energy in sunlight, reducing the absorption and transfer of heat. At the same time, due to its unique hollow structure, the heat-insulating filler can effectively block the conduction and convection of heat, achieving a heat-insulating effect. The integration of these two fillers enables the coating to have a certain cold-insulating function while having a heat-insulating function.

[0020] Preferably, the present invention also provides a method for preparing the above heat-insulating and heat-preserving coating, which includes weighing low-emissivity fillers, heat-insulating fillers, modifiers and solvents in proportion, mixing them, adjusting the pH value of the mixed solution to 8-10, stirring, then adjusting the pH value of the mixed solution to 3-5 again, adding coupling agents, and after stirring, cooling, filtering and drying, adding heat-preserving fillers and resins, stirring to obtain a composite filler, loading the composite filler onto the surface of aluminum, and curing to obtain the heat-insulating and heat-preserving coating.

[0021] In the above technical solution, the first adjustment of the pH value is for the chemical reaction for modifying the low-emissivity fillers and heat-insulating fillers, and the second adjustment of the pH value is for the reaction of loading the heat-insulating fillers onto the composite filler.

[0022] More preferably, after adjusting the pH value of the mixed solution to 8-10, the stirring rate is 1000-1200 r / min, the stirring temperature is 70-90 °C, and the stirring time is 1.5-2 h.

[0023] More preferably, after adding the coupling agent, the stirring temperature is 70-90 °C and the stirring time is 3-4 h.

[0024] More preferably, cool to room temperature.

[0025] More preferably, after adding the heat-preserving fillers and resins, the stirring rate is 1000-1200 r / min.

[0026] More preferably, the composite filler is sprayed onto the surface of aluminum by electrostatic spraying.

[0027] More preferably, the conditions for electrostatic spraying are: voltage 70-85 kV, powder supply air pressure flow rate 0.2 MPa.

[0028] More preferably, the curing temperature is 180-220 °C and the curing time is 1.5-2 h.

[0029] The present invention also provides the application of the above heat-insulating and heat-preserving coating in aluminum.

[0030] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a heat-insulating and heat-preserving coating for aluminum materials. This coating uses low-emissivity fillers, heat-preserving fillers, and heat-insulating fillers to reduce the thermal conductivity of the material and achieve the heat-insulating effect. The low-emissivity fillers have a wide electronic bandgap and a high refractive index. The bandgap energy is higher than the energy of photons in the solar spectrum. Therefore, in the solar spectrum, the low-emissivity fillers exhibit strong scattering and negative absorption, resulting in a high solar light reflectance ratio, reducing the heat input, and achieving good heat-insulating performance. The low-emissivity fillers not only reflect sunlight but also reduce the thermal radiation on the surface of the aluminum material, thereby preventing the heat transfer on the surface of the aluminum material from entering the environment. This helps to maintain the temperature of the aluminum material in a cold environment and enables the coating to have good cold-insulating performance. The heat-preserving fillers have a low thermal conductivity, a high specific surface area, and a high porosity. Due to their excellent heat-insulating performance, they have been widely used in building heat insulation. In addition, the heat-preserving fillers exhibit a strong emissivity in the atmospheric window band due to their chemical bonding (O-Si-O-). The heat-insulating fillers have a hollow structure, which makes there be more static air inside the material. When heat passes through the microspheres, the conduction path will be blocked by the gas, which can prevent heat exchange, enabling the coating to have good heat-insulating effect. Moreover, the hollow structure of the heat-insulating fillers is equally effective in a cold environment. It reduces the heat loss by blocking the heat conduction, thereby maintaining the temperature of the aluminum material and enabling the coating to have excellent cold-insulating effect. The low-emissivity fillers, heat-insulating fillers, and heat-preserving fillers in the coating all have a low thermal conductivity, which helps to reduce the heat transfer, whether from the environment to the aluminum material or from the aluminum material to the environment. In summary, the three work together to improve the overall heat-insulating and heat-preserving performance. Through experimental verification, the heat-insulating and heat-preserving coating has excellent effects. The heat-insulating temperature difference of the heat-insulating and heat-preserving coating is 20 - 25 °C, and the cold-insulating temperature difference can reach 8 - 12 °C.

[0031] Furthermore, barium sulfate, titanium dioxide, zinc oxide, and zirconium oxide have low-emission characteristics and can reflect infrared radiation, reducing the thermal radiation transfer. These fillers form a reflective layer in the coating, effectively blocking the radiative transfer of heat and enhancing the heat-insulating performance.

[0032] Furthermore, glass hollow microspheres, silica hollow microspheres, and zirconia hollow microspheres have a low thermal conductivity and can effectively block heat conduction. The hollow structure forms an air layer in the coating, further reducing the heat conduction and enhancing the heat-insulating performance.

[0033] Furthermore, silica, zirconia, boron nitride, and titanium dioxide have a low thermal conductivity and high thermal stability, and can reduce heat convection and heat conduction. These fillers form a dense structure in the coating, blocking the heat dissipation and enhancing the cold-insulating performance.

[0034] Furthermore, tetraethyl orthosilicate, as a modifier, can improve the weather resistance and adhesion of the coating. Through modification, the coating can still maintain stable heat insulation and cold insulation properties in high-temperature or low-temperature environments.

[0035] Furthermore, amino silane coupling agent, epoxy silane coupling agent, allyltrimethoxysilane coupling agent and titanate coupling agent can enhance the interfacial bonding force between the filler and the resin. Through the coupling effect, the mechanical properties and thermal stability of the coating are improved, and the heat insulation and cold insulation effects are further optimized.

[0036] Furthermore, isopropyl tri(isostearoyl) titanate and isopropyl tri(dioctylpyrophosphato) titanate have excellent coupling properties. These titanate coupling agents can further improve the heat resistance and adhesion of the coating and enhance the heat insulation and cold insulation properties.

[0037] Furthermore, epoxy resin, acrylic resin, silicone resin and fluorocarbon resin have excellent weather resistance, adhesion and mechanical properties. As the coating matrix, these resins can effectively carry the filler and form a dense and stable coating structure, improving the heat insulation and cold insulation properties.

[0038] The present invention also provides a preparation method of the above heat-insulating and heat-preserving coating. The preparation is convenient, only requiring simple mixing of the raw materials and heating at a certain temperature for reaction. Therefore, the present invention has the characteristics of being easy to scale up production, low cost, wide sources of preparation raw materials, and cheap prices. Another inventive point of the present invention lies in the use of traditional inorganic materials for preparation, with cheap and wide sources of raw materials and a long service life. The process design of the present invention is reasonable. By compounding three heat-insulating materials and combining low-emissivity fillers with heat-preserving fillers, it reasonably improves the situation that the low-emissivity fillers precipitate in the coating due to their relatively large density and poor compatibility with the resin, and improves the phenomenon that the heat-preserving fillers are too light in mass and will float on the surface, making the heat-insulating fillers in the coating evenly distributed and greatly improving the heat-insulating performance. The low-emissivity fillers and heat-insulating fillers are modified with a modifier so that their surfaces are coated with silicon-oxygen bonds, improving the dispersibility of the low-emissivity fillers and heat-insulating fillers. The silicon-oxygen bond has a low thermal conductivity, further enhancing the heat insulation of the coating. The prepared heat-insulating and heat-preserving coating mainly functions to block the heat transfer from the environment to the aluminum surface. The combination of the low-emissivity fillers and heat-insulating fillers improves the dispersion effect of the fillers in the coating, and at the same time plays a role in reducing the thermal radiation performance of the aluminum surface, preventing the heat transfer from the aluminum surface from entering the environment and improving the heat preservation effect; the heat-preserving fillers are mainly used to reduce the thermal conductivity of the coating, and none of the three fillers can be absent. The present invention has important theoretical value and practical significance for solving the poor heat-insulating performance of aluminum in different fields or different scenarios.

[0039] The present invention also provides that the above heat-insulating and heat-preserving coating is applicable to the surface of aluminum materials, which can significantly improve the heat-insulating and cold-insulating properties of aluminum materials. In the fields of construction, transportation, etc., it can effectively reduce energy consumption and improve the service performance of aluminum materials. Description of the Drawings

[0040] Figure 1 It is the heat-insulating temperature difference curve graph of the heat-insulating and heat-preserving coating in Example 1 of the present invention; Figure 2 It is the cold-insulating temperature difference curve graph of the heat-insulating and heat-preserving coating in Example 1 of the present invention. Detailed Embodiments

[0041] To enable those skilled in the art to understand the features and effects of the present invention, the following is only a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art regarding the present invention. In case of conflict, the definition in this specification shall prevail.

[0042] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0043] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0044] In this article, unless otherwise specified, "comprising", "including", "containing", "having" or similar expressions cover the meanings of "consisting of" and "mainly consisting of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A only comprises a".

[0045] In this article, for the sake of concise description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0046] The present invention discloses a preparation method of a heat-insulating and heat-preserving coating, which specifically includes the following steps: 1) Preparation of composite filler First, weigh 25 - 27 parts of low - emissivity filler, 5 - 8 parts of heat - insulating filler, 8 - 9 parts of modifier, and 75 - 85 parts of solvent. After mixing, adjust the pH value of the mixed solution to 8 - 10, and react at 70 - 90 °C with a stirring rate of 1000 - 1200 r / min for 1.5 - 2 h to obtain the modified low - emissivity filler and heat - insulating filler. Secondly, adjust the pH value of the above reaction solution to 3 - 5, add 6 - 8 parts of coupling agent, and continue to react at 70 - 90 °C with stirring for 3 - 4 h. Finally, after cooling the reaction solution to room temperature, carry out suction filtration and drying to obtain the composite filler of heat - insulating filler loaded with radiation filler.

[0047] 2) Preparation of heat - insulating and heat - preserving coating First, mix the prepared composite filler with 10 - 15 parts of heat - preserving filler and 42 - 54 parts of resin evenly at a rate of 1000 - 1200 r / min. Secondly, spray the evenly - mixed raw materials onto the aluminum surface by electrostatic spraying at a voltage of 70 - 85 kV and a powder - supplying air pressure flow rate of 0.2 MPa. Finally, cure at 180 - 220 °C for 1.5 - 2 h to obtain an aluminum - based coating with a heat - insulating and heat - preserving function and a thickness of 30 - 60 μm.

[0048] In step 1), preferably, the low - emissivity filler includes one or more of barium sulfate, titanium dioxide, zinc oxide, and zirconium oxide.

[0049] In step 1), preferably, the heat - insulating filler includes one or more of glass hollow microspheres, silica hollow microspheres, and zirconia hollow microspheres.

[0050] In step 1), preferably, the size of the heat - insulating filler is 1 μm - 20 μm.

[0051] In step 1), preferably, the coupling agent includes one of amino - silane coupling agent, epoxy - silane coupling agent, allyl - trimethoxysilane coupling agent, isopropyl tri(isostearoyl) titanate (TCA - KTTS), and isopropyl tri(dioctylpyrophosphato) titanate (TCA - K38S).

[0052] In step 1), preferably, the modifier is tetraethyl orthosilicate.

[0053] In step 2), preferably, the heat - preserving filler includes one or more of silica, zirconia, boron nitride, and titanium dioxide.

[0054] In step 2), preferably, the low - emissivity filler is loaded on the heat - preserving filler by a chemical method.

[0055] In step 2), preferably, the resin includes one of epoxy resin, acrylic resin, silicone resin, and fluorocarbon resin.

[0056] In step 2), preferably, the curing temperature is 180-220 °C.

[0057] Preferably, the preparation process of the heat insulation coating is simple.

[0058] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0059] Conventional instrument equipment in the art is used in the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, “%” represents weight percentage, “parts” represents weight parts, and the ratio represents weight ratio.

[0060] Example 1 1) Preparation of composite filler First, weigh 26 parts of low-emissivity filler barium sulfate, 5 parts of heat insulation filler glass hollow microspheres, 8 parts of tetraethyl orthosilicate and 75 parts of ethanol. After mixing, adjust the pH value of the mixed solution to 8.2, and stir and react at 75 °C with a stirring rate of 1000 r / min for 1.5 h to obtain modified low-emissivity filler and heat insulation filler. Secondly, adjust the pH value of the above reaction solution to 3.4, add 7 parts of epoxy silane coupling agent, and continue to react at 90 °C with stirring for 3 h. Finally, after cooling the reaction solution to room temperature, carry out suction filtration and drying to obtain the composite filler with glass hollow microspheres loaded on barium sulfate.

[0061] 2) Preparation of heat insulation and thermal insulation coating First, mix the prepared composite filler with 10 parts of silicon dioxide and 52 parts of epoxy resin evenly by stirring at 1000 r / min. Secondly, spray the uniformly mixed raw materials on the aluminum surface by electrostatic spraying at a voltage of 80 kV and a powder supply air pressure flow rate of 0.2 MPa. Finally, cure at 180 °C for 2 h to obtain an aluminum-based coating with heat insulation and thermal insulation functions.

[0062] Performance test of the prepared 40-μm-thick aluminum-based coating with heat insulation and heat preservation functions shows that the average heat insulation temperature difference is 23 °C after heating on a 70 °C hot plate for 5 minutes, and the cold insulation temperature difference measured on the ice surface reaches 10 °C. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties - Calibration and Guarded-Hot-Box Methods", the thermal conductivity of the coating after a 200 °C test is 0.04 W / (m·K).

[0063] As Figures 1 to 2 shown, through the coordinated action of heat insulation fillers loading radiation fillers and heat preservation fillers, the coating has good heat insulation performance within a certain period of time and excellent cold insulation effect.

[0064] Example 2 1) Preparation of composite fillers First, weigh 25 parts of low-emissivity filler titanium dioxide, 7 parts of heat insulation filler glass hollow microspheres, 8 parts of tetraethyl orthosilicate and 80 parts of ethanol. After mixing, adjust the pH value of the mixed solution to 8.9, and stir and react at 85 °C with a stirring rate of 1000 r / min for 1.5 h to obtain modified low-emissivity filler and heat insulation filler. Secondly, adjust the pH value of the above reaction solution to 4.2, add 6 parts of isopropyl tri(isostearoyl) titanate, and continue to react at 80 °C with stirring for 4 h. Finally, after cooling the reaction solution to room temperature, carry out suction filtration and drying to obtain the composite filler with glass hollow microspheres loaded on titanium dioxide.

[0065] 2) Preparation of heat insulation and heat preservation coating First, mix the prepared composite filler with 12 parts of zirconia and 50 parts of fluorocarbon resin evenly by stirring at 1100 r / min. Secondly, spray the evenly mixed raw materials on the aluminum surface by electrostatic spraying at a voltage of 80 kV and a powder supply gas flow rate of 0.2 MPa. Finally, cure at 180 °C for 2 h to obtain the aluminum-based coating with heat insulation and heat preservation functions.

[0066] Performance test of the prepared 30-μm-thick aluminum-based coating with heat insulation and heat preservation functions shows that the average heat insulation temperature difference is 20 °C after heating on a 70 °C hot plate for 5 minutes, and the cold insulation temperature difference measured on the ice surface reaches 9 °C. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties - Calibration and Guarded-Hot-Box Methods", the thermal conductivity of the coating after a 200 °C test is 0.043 W / (m·K).

[0067] Example 3 1) Preparation of composite fillers First, weigh a total of 27 parts of low-emissivity fillers barium sulfate and titanium dioxide, 5 parts of heat-insulating filler silica hollow microspheres, 8 parts of tetraethyl orthosilicate, and 85 parts of ethanol. After mixing, adjust the pH value of the mixed solution to 10, and stir and react at 1200 r / min for 2 h at 90 °C to obtain the modified low-emissivity filler and heat-insulating filler. Secondly, adjust the pH value of the above reaction solution to 3.6, add 8 parts of isopropyltri(isostearoyl) titanate, and continue to react at 80 °C, with stirring for 4 h. Finally, after cooling the reaction solution to room temperature, perform suction filtration and drying to obtain the composite filler with silica hollow microspheres loaded on titanium dioxide and barium sulfate.

[0068] 2) Preparation of heat-insulating and heat-preserving coating First, mix the prepared composite filler evenly with 13 parts of boron nitride and 47 parts of acrylic resin under stirring at 1000 r / min. Secondly, spray the uniformly mixed raw materials electrostatically on the aluminum surface at a voltage of 80 kV and a powder supply gas flow rate of 0.2 MPa. Finally, cure at 180 °C for 1.5 h to obtain an aluminum-based coating with heat-insulating and heat-preserving functions.

[0069] The performance of the prepared 40-μm-thick aluminum-based coating with heat-insulating and heat-preserving functions was tested. The results showed that the average heat-insulating temperature difference was 22 °C after heating on a 70 °C hot plate for 5 min, and the cold-insulating temperature difference measured on an ice surface reached 8 °C. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties - Guarded Hot Box Method", the thermal conductivity of the coating after a 200 °C test was 0.041 W / (m·K).

[0070] Example 4 1) Preparation of composite filler First, weigh 27 parts of low-emissivity filler barium sulfate, a total of 7 parts of heat-insulating fillers glass hollow microspheres and silica hollow microspheres, 9 parts of tetraethyl orthosilicate, and 80 parts of ethanol. After mixing, adjust the pH value of the mixed solution to 9.3, and stir and react at 1100 r / min for 1.5 h at 80 °C to obtain the modified low-emissivity filler and heat-insulating filler. Secondly, adjust the pH value of the above reaction solution to 5, add 8 parts of epoxy silane coupling agent, and continue to react at 90 °C, with stirring for 4 h. Finally, after cooling the reaction solution to room temperature, perform suction filtration and drying to obtain the composite filler with glass hollow microspheres and silica hollow microspheres loaded on barium sulfate.

[0071] 2) Preparation of heat-insulating and heat-preserving coating First, the prepared composite filler is stirred and mixed evenly with 11 parts of titanium dioxide and 47 parts of silicone resin at 1200 r / min. Secondly, the evenly mixed raw materials are electrostatically sprayed on the aluminum surface at a voltage of 80 kV and a powder supply air pressure flow rate of 0.2 MPa. Finally, it is cured at 180 °C for 2 h to obtain an aluminum-based coating with heat insulation and heat preservation functions.

[0072] The performance of the prepared 60-μm-thick aluminum-based coating with heat insulation and heat preservation functions was tested. The results showed that the average heat insulation temperature difference was 24 °C after heating on a 70 °C hot plate for 5 min, and the cold insulation temperature difference measured on the ice surface was 12 °C. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties Calibration and Guarded Hot Box Method", the thermal conductivity of the coating after a 200 °C test was 0.038 W / (m·K).

[0073] Example 5 1) Preparation of composite filler First, weigh 27 parts of low-emissivity filler zirconia, 6 parts of heat-insulating filler silica hollow microspheres, 8 parts of tetraethyl orthosilicate and 85 parts of ethanol. After mixing, adjust the pH value of the mixed solution to 8, and stir and react at 1200 r / min at 80 °C for 2 h to obtain modified low-emissivity filler and heat-insulating filler. Secondly, adjust the pH value of the above reaction solution to 4.2, add 6 parts of allyltrimethoxysilane coupling agent, and continue to react at 70 °C, stirring and reacting for 4 h. Finally, after cooling the reaction solution to room temperature, it is filtered by suction and dried to obtain a composite filler with silica hollow microspheres loaded on zirconia.

[0074] 2) Preparation of heat insulation and heat preservation coating First, the prepared composite filler is stirred and mixed evenly with a total of 14 parts of silica and boron nitride and 47 parts of acrylic resin at 1000 r / min. Secondly, the evenly mixed raw materials are electrostatically sprayed on the aluminum surface at a voltage of 80 kV and a powder supply air pressure flow rate of 0.2 MPa. Finally, it is cured at 180 °C for 2 h to obtain an aluminum-based coating with heat insulation and heat preservation functions.

[0075] The performance of the prepared 60-μm-thick aluminum-based coating with heat insulation and heat preservation functions was tested. The results showed that the average heat insulation temperature difference was 25 °C after heating on a 70 °C hot plate for 5 min, and the cold insulation temperature difference measured on the ice surface reached 11 °C. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties Calibration and Guarded Hot Box Method", the thermal conductivity of the coating after a 200 °C test was 0.037 W / (m·K).

[0076] Example 6 1) Preparation of composite filler First, weigh 25 parts of low-emissivity fillers barium sulfate, zinc oxide, and titanium dioxide, 5 parts of heat-insulating filler glass hollow microspheres, 8 parts of tetraethyl orthosilicate, and 80 parts of ethanol. After mixing, adjust the pH value of the mixed solution to 9.2, and stir and react at 90 °C with a stirring rate of 1200 r / min for 2 h to obtain modified low-emissivity fillers and heat-insulating fillers. Secondly, adjust the pH value of the above reaction solution to 4.6, add 6 parts of epoxy silane coupling agent, and continue to react at 70 °C with stirring for 3 h. Finally, after cooling the reaction solution to room temperature, perform suction filtration and drying to obtain composite fillers with glass hollow microspheres loaded on barium sulfate, zinc oxide, and titanium dioxide.

[0077] 2) Preparation of heat-insulating and heat-preserving coating First, mix 12 parts of prepared composite fillers silicon dioxide and zirconium oxide and 52 parts of fluorocarbon resin evenly by stirring at 1000 r / min. Secondly, spray the evenly mixed raw materials onto the aluminum surface by electrostatic spraying at a voltage of 80 kV and a powder supply gas flow rate of 0.2 MPa. Finally, cure at 180 °C for 1.5 h to obtain an aluminum-based coating with heat-insulating and heat-preserving functions.

[0078] The performance of the prepared 40-μm-thick aluminum-based coating with heat-insulating and heat-preserving functions was tested. The results showed that the average heat-insulating temperature difference was 22 °C after heating on a 70 °C hot plate for 5 min, and the cold-insulating temperature difference measured on the ice surface reached 9 °C. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties Calibration and Guarded Hot Box Method", the thermal conductivity of the coating after a 200 °C test was 0.04 W / (m·K).

[0079] Example 7 1) Preparation of composite fillers First, weigh 27 parts of low-emissivity filler barium sulfate, 8 parts of heat-insulating filler zirconia hollow microspheres, 9 parts of tetraethyl orthosilicate, and 85 parts of ethanol. After mixing, adjust the pH value of the mixed solution to 8.6, and stir and react at 70-90 °C with a stirring rate of 1000 r / min for 2 h to obtain modified low-emissivity fillers and heat-insulating fillers. Secondly, adjust the pH value of the above reaction solution to 3.1, add 8 parts of amino silane coupling agent, and continue to react at 70 °C with stirring for 3 h. Finally, after cooling the reaction solution to room temperature, perform suction filtration and drying to obtain composite fillers with zirconia hollow microspheres loaded with barium sulfate.

[0080] 2) Preparation of heat-insulating and heat-preserving coating First, mix the prepared composite filler with 15 parts of titanium dioxide and 42 parts of silicone resin evenly under the condition of 1100 r / min. Secondly, spray the evenly mixed raw materials electrostatically on the aluminum surface at a voltage of 80 kV and a powder supply gas flow rate of 0.2 MPa. Finally, cure at 180 °C for 2 h to obtain an aluminum-based coating with heat insulation and heat preservation functions.

[0081] The performance of the prepared 50-μm-thick aluminum-based coating with heat insulation and heat preservation functions was tested. The results showed that the average heat insulation temperature difference was 21 °C after heating on a 70 °C hot plate for 5 min, and the cold insulation temperature difference measured on the ice surface reached 8 °C. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties - Guarded Hot Box Method", the thermal conductivity of the coating after a 200 °C test was 0.041 W / (m·K).

[0082] Example 8 1) Preparation of composite filler First, weigh 27 parts of low-emissivity filler zirconia, 8 parts of heat insulation filler silica hollow microspheres, 9 parts of tetraethyl orthosilicate and 85 parts of ethanol. After mixing, adjust the pH value of the mixed solution to 9.6, and stir and react at 90 °C with a stirring rate of 1000 r / min for 2 h to obtain modified low-emissivity filler and heat insulation filler. Secondly, adjust the pH value of the above reaction solution to 3.8, add 6 parts of isopropyl tri(isostearoyl) titanate, and continue to react at 90 °C with stirring for 4 h. Finally, after cooling the reaction solution to room temperature, perform suction filtration and drying to obtain a composite filler of silica hollow microspheres loaded with zirconia.

[0083] 2) Preparation of heat insulation and heat preservation coating First, mix the prepared composite filler with a total of 11 parts of zirconia and boron nitride and 48 parts of acrylic resin evenly under the condition of 1000 r / min. Secondly, spray the evenly mixed raw materials electrostatically on the aluminum surface at a voltage of 80 kV and a powder supply gas flow rate of 0.2 MPa. Finally, cure at 180 °C for 1.5 h to obtain an aluminum-based coating with heat insulation and heat preservation functions.

[0084] The performance of the prepared 30-μm-thick aluminum-based coating with heat insulation and heat preservation functions was tested. The results showed that the average heat insulation temperature difference was 20 °C after heating on a 70 °C hot plate for 5 min, and the cold insulation temperature difference measured on the ice surface reached 10 °C. According to the relevant regulations of GB / T 13475-2008 "Determination of Steady-State Heat Transfer Properties - Guarded Hot Box Method", the thermal conductivity of the coating after a 200 °C test was 0.042 W / (m·K).

[0085] The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution in accordance with the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A thermal insulation coating for aluminum material, characterized in that: The following raw materials are included in parts by weight: Low-radiative filler: 25-27 parts; Thermal insulation filler: 5~8 parts; Thermal insulation filler: 10~15 parts; Coupling agent: 6~8 parts; Resin: 42~54 parts; Modifier: 8~9 parts; Solvent: 75~85 parts.

2. The heat insulation coating for aluminum material according to claim 1, characterized in that: The low-radiative filler includes one or more of barium sulfate, titanium dioxide, zinc oxide and zirconium oxide.

3. The heat insulation coating for aluminum material according to claim 1, characterized in that: The heat-insulating filler includes one or more of glass hollow microspheres, silicon dioxide hollow microspheres and zirconium oxide hollow microspheres.

4. The heat insulation coating for aluminum material according to claim 1, characterized in that: The thermal insulation filler includes one or more of silicon dioxide, zirconium oxide, boron nitride and titanium dioxide.

5. The heat insulation coating for aluminum material according to claim 1, characterized in that: The modifier includes tetraethyl orthosilicate.

6. The heat insulation coating for aluminum material according to claim 1, characterized in that: The coupling agent includes one of an aminosilane coupling agent, an epoxysilane coupling agent, an allyltrimethoxysilane coupling agent and a titanate coupling agent.

7. The heat insulation coating for aluminum material according to claim 6, characterized in that: The titanate coupling agent includes isopropyl tri(isostearoyl) titanate or isopropyl tri(dioctyl pyrophosphoryl) titanate.

8. The heat insulation coating for aluminum material according to claim 1, characterized in that: The resin includes one of epoxy resin, acrylic resin, silicone resin and fluorocarbon resin.

9. The method for preparing a heat-insulating coating for aluminum materials according to any one of claims 1 to 8, characterized in that: The method comprises weighing low-radiation filler, thermal insulation filler, modifier and solvent in proportion, mixing the mixture, adjusting the pH value of the mixed solution to 8-10 to obtain modified low-radiation filler and thermal insulation filler, stirring, adjusting the pH value of the obtained low-radiation filler and thermal insulation filler to 3-5, adding a coupling agent, stirring, cooling, filtering and drying, adding thermal insulation filler and resin, stirring to obtain composite filler, loading the composite filler onto the surface of aluminum material, and obtaining thermal insulation coating after curing.

10. Use of the thermal insulation coating for aluminum materials as claimed in any one of claims 1 to 8 in aluminum materials.

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