Thermal insulation layer coating material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of heat map model brush coating, in particular to a heat insulation layer coating material and a preparation method and application thereof.The heat insulation layer coating material is prepared from, by weight, 45-50 parts of film forming matter, 1-3 parts of filler, 42-48 parts of mixed solvent, 19-21 parts of curing agent A and 3-4 parts of curing agent B. The film forming matter comprises epoxy resin and titanium dioxide; the filler is SiO2; the mixed solvent comprises methylbenzene, acetone, ethylene glycol butyl ether acetate and butanone; the curing agent A comprises a modified aliphatic amine curing agent; the curing agent B comprises a mixed solution of tetraethylenepentamine and isopropyl-ketone. When the heat insulation layer coating material is applied to preparation of a heat map model, high-efficiency, low-cost and environment-friendly processing of the model can be realized on the premise of ensuring the measurement precision of a heat map, and four core problems of cost, period, health risk and manufacturing capability which exist in a phosphorescent heat map technology for a long time are successfully solved.

Description

Technical Field

[0001] This invention relates to the field of thermal mapping model coating technology, and in particular to a heat insulation coating material, its preparation method and application. Background Technology

[0002] Aerodynamic thermal environment measurement technology is an important tool in the aerospace field for quantitative analysis of thermal loads on aircraft surfaces. Based on different measurement methods, this technology can be mainly divided into two categories: point measurement technology and surface measurement technology. Among them, non-contact surface measurement thermal technology (such as phosphorescent thermography) exhibits significant technical advantages and broad application prospects in complex flow regions such as shock wave / boundary layer interference and shock wave / shock wave interference because it can obtain global heat flow distribution information without damaging the model surface.

[0003] The implementation of phosphorescent thermography technology places strict requirements on the preparation of experimental models. The models must meet the following key conditions: (1) conform to the one-dimensional semi-infinite assumption within the effective measurement time; (2) have a highly reflective white surface; and (3) possess isotropic materials capable of withstanding multiple wind tunnel loads. To meet these conditions, the commonly used model preparation methods mainly include the following three: (1) The model is prepared by directly using engineering ceramics. Although this method can meet the requirements of thermophysical performance, the cost of engineering ceramics is high and the processing performance is poor, which results in the processing cycle of the test model being as long as 3 to 5 months and the cost being as high as hundreds of thousands of yuan. Moreover, it is difficult to apply to models with complex shapes.

[0004] (2) Spraying a ceramic coating on the model surface. This method attempts to share the substrate with the point thermal / force test model, but there are still obvious shortcomings. For example, a high-temperature (above 200°C) curing process is required during the spraying process, which can easily cause thermal deformation of the model and cannot achieve secondary spraying; the ceramic coating has a high thermal diffusivity, and the spraying thickness is usually more than 0.4 mm, which will change the accuracy of the model surface; in addition, the coating surface is rough and has a granular feel, which may interfere with the wind tunnel flow field and limit its practical application.

[0005] (3) Spraying organic coating material onto the model surface. Although this method improves the processing performance to some extent, it generates a large amount of dust and atomized organic solvents during the spraying process, resulting in serious waste of coating material, low process efficiency, and occupational health and safety hazards.

[0006] It is evident that existing phosphorescent thermogram model preparation technologies generally suffer from problems such as long processing cycles, high costs, significant process pollution, and poor model adaptability, severely hindering the widespread application of this technology in aerodynamic thermal environment testing. Therefore, there is an urgent need to develop a novel model preparation method that can achieve efficient, low-cost, and environmentally friendly model processing while ensuring the accuracy of thermogram measurements.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] The purpose of this invention is to provide a heat insulation coating material, its preparation method and application. When applied to the preparation of thermal image models, this heat insulation coating material can achieve efficient, low-cost and environmentally friendly model processing while ensuring the accuracy of thermal image measurements.

[0009] In a first aspect, the present invention provides a heat-insulating layer coating material, comprising the following raw materials in parts by weight: The mixture consists of 45-50 parts film-forming substance, 1-3 parts filler, 42-48 parts mixed solvent, 19-21 parts curing agent A, and 3-4 parts curing agent B. The film-forming material includes epoxy resin and titanium dioxide; The filler is SiO2; The mixed solvent includes toluene, acetone, ethylene glycol butyl ether acetate, and methyl ethyl ketone; The curing agent A includes a modified fatty amine curing agent; The curing agent B comprises a mixed solution of tetraethylenepentamine and isopropanone.

[0010] In the heat insulation coating material of this invention, epoxy resin is the main film-forming substance. Its molecular chain contains strongly polar ether bonds and hydroxyl groups, which can form strong van der Waals forces and hydrogen bonds with the metal substrate, providing strong adhesion and preventing the coating from being peeled off in high-speed airflow. Titanium dioxide, as the core functional filler, has extremely high refractive index and reflectivity, especially strong reflectivity for infrared radiation. By reflecting a large amount of infrared radiation generated by aerodynamic heating, it significantly reduces heat conduction to the metal substrate from the first line of defense. SiO2 has a very low thermal conductivity. Uniformly dispersing SiO2 particles in the epoxy resin matrix can effectively extend the heat transfer path and inhibit heat conduction. Furthermore, the amount of SiO2 used is 1-3 parts, a ratio that ensures functionality without affecting the construction process. Modified aliphatic amine curing agent, as the main curing agent, not only provides suitable application... This process ensures deep curing within the thicker coating layer. Tetraethylenepentamine is a highly active, multifunctional aliphatic amine with a very fast reaction rate. Isoacetone, as a solvent / diluent, is convenient to use and can regulate the intensity of the initial reaction. Synergistically with curing agent A, it forms a perfect curing curve from rapid surface drying to deep curing, ultimately resulting in a dense, highly cross-linked three-dimensional network structure. For the mixed solvent, acetone and butanone have extremely strong dissolving power for epoxy resin, ensuring uniform dispersion of the resin in the system with suitable initial viscosity. Toluene, as a co-solvent, can adjust the overall dissolving power, reduce costs, and regulate volatility. Finally, a high-boiling-point solvent, ethylene glycol butyl ether acetate, is added to the mixed solvent to ensure that the coating surface maintains its fluidity for a long time after brushing, allowing sufficient time for brush marks to level, thus obtaining a smooth and uniform coating surface.

[0011] As a preferred embodiment of this technical solution, the heat insulation coating material of the present invention comprises the following raw materials in parts by weight: 35 parts epoxy resin, 12 parts titanium dioxide, 2 parts SiO2 filler, 47 parts mixed solvent, 19 parts curing agent A, and 3.15 parts curing agent B (0.75 parts tetraethylenepentamine and 2.4 parts isopropyl ketone).

[0012] As a preferred embodiment of this technical solution, the SiO2 is nano-SiO2. Nano-sized SiO2 particles have a huge specific surface area and can interact strongly with epoxy resin molecular chains, thereby enhancing and toughening the coating, improving its hardness, wear resistance and thermal stability, and preventing the coating from cracking under thermal stress.

[0013] As a preferred embodiment of this technical solution, the modified aliphatic amine curing agent includes any one of polyamide 650, polyamide 651, T-31 Mannich base modified amine, and ketimine, and is preferably polyamide 650.

[0014] In a preferred embodiment of this technical solution, the content of titanium dioxide in the film-forming material is 30% to 40% of the epoxy resin content, and preferably 33%.

[0015] As a preferred embodiment of this technical solution, in the mixed solvent, the volume fraction of toluene is 55%~67%, and preferably 59%; the volume fraction of acetone is 24%~36%, and preferably 31%; the volume fraction of ethylene glycol butyl ether acetate is 4%~5%, and preferably 4%; and the volume fraction of butanone is 5%~6%, and preferably 6%.

[0016] In a preferred embodiment of this technical solution, the mass ratio of tetraethylenepentamine to isopropanone in curing agent B is (2~3):(7~8), and more preferably 2.5:8.

[0017] Secondly, the present invention also discloses a method for preparing the above-mentioned heat-insulating coating material, comprising the following steps: S1. Add SiO2 filler to the film-forming material to obtain a mixture; S2. Add the prepared mixed solvent to the mixture and stir for 12-20 min to ensure that the SiO2 filler is completely impregnated and uniformly dispersed in the resin system, and to avoid local stress concentration or uneven thermal insulation performance caused by agglomeration, so as to obtain a mixed solution. S3. Add curing agent A and curing agent B to the mixed solution and stir for 15-20 minutes to form a dense and uniform cross-linked network structure to obtain the heat insulation coating material.

[0018] The preparation method of the thermal insulation coating material of this invention takes only 30-40 minutes from the start of feeding to the final material preparation. In the research and development environment of wind tunnel testing, this characteristic means that it can be prepared "as needed" according to the test progress, which greatly improves the flexibility of test preparation and avoids the problems of shelf life and performance degradation that may be caused by the early preparation of materials.

[0019] Thirdly, the present invention also discloses the application of the above-mentioned heat insulation coating material in the wind tunnel test thermal model, which should also fall under the protection of the present invention, specifically including the following steps: Apply a heat-insulating coating material to the surface of the metal model; Dry or air-dry the metal model coated with the heat-insulating material to allow the surface coating to cure. The metal model is then polished and shaped after the surface coating has cured.

[0020] The brushing and curing processes of this invention are carried out at room temperature or low temperature, completely avoiding the risk of model substrate deformation caused by traditional metal cutting or ceramic sintering thermal processing. This ensures the original accuracy and strength of the substrate, and the preparation process is dust-free, with no significant atomization of organic matter, effectively reducing occupational health hazards. Furthermore, the fluid characteristics of the brushing process give it unique coverage capabilities, enabling the preparation of large-scale thermal model images with various complex shapes and dimensions exceeding 1.5 meters. The coating can be removed using paint remover or physical methods and can be re-brushed. The brushed model can be quickly de-painted and used for other experiments, making the preparation of large-scale thermal model images simple and economical.

[0021] As a preferred embodiment of this technical solution, when brushing, a brush with a width smaller than the brushing surface is used, the brush tilt angle is not greater than 45°, and the brush only passes through an area once, and the amount of heat insulation coating material applied in each layer is less than 100 g. After each coat is applied, allow it to cure at room temperature and let the surface dry before applying the next coat. Repeat the brushing process until the entire surface of the metal model is covered with the heat-insulating coating material.

[0022] As a preferred embodiment of this technical solution, the drying temperature is not greater than 75 ℃; The air-drying temperature is 15~25℃.

[0023] As a preferred embodiment of this technical solution, after the coating is cured, a milky white smooth surface is formed on the surface of the metal model.

[0024] As a preferred embodiment of this technical solution, during the polishing process, fine sandpaper is used to polish the metal model after the coating has been cured, removing burrs on the surface and reverse airflow steps at the model connection points to compensate for thickness errors, ensure aerodynamic shape accuracy, optimize surface quality, and reduce thermal data noise.

[0025] The heat insulation coating material of the present invention has at least the following beneficial effects: In the thermal insulation coating material of this invention, a composite thermal insulation barrier is constructed using "epoxy resin-titanium dioxide-SiO2". The rigid skeleton of the epoxy resin supports the highly reflective titanium dioxide and the high thermal resistance SiO2, forming a highly efficient thermal insulation layer with both heat reflection and heat barrier mechanisms. A modified aliphatic amine main curing agent ensures the pot life and deep curing, while tetraethylenepentamine auxiliary curing agent achieves rapid surface drying and low-temperature reactivity, ensuring that the coating quickly builds strength and eventually cures completely within the application window. The compounding of high and low boiling point solvents such as toluene, acetone, ethylene glycol butyl ether acetate, and methyl ethyl ketone ensures suitable viscosity during brushing and excellent leveling properties through the delayed evaporation of the high-boiling-point solvent, ultimately facilitating the obtaining of a uniform and defect-free coating, laying the foundation for high-precision thermal mapping measurements. Therefore, this invention, through a composite structure design of a metal substrate and a polymer thermal insulation coating, along with a matching special coating material and a simple brushing process, successfully solves the four core problems that have long existed in phosphorescent thermal imaging technology: cost, cycle, health risks, and manufacturing capability. It achieves rapid and high-quality processing of thermal imaging models, thereby shortening the experimental cost and cycle. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is the preparation process of the wind tunnel test thermal image model of the present invention. Detailed Implementation

[0028] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1 Figure 1 This is the preparation process of the wind tunnel test thermal image model of the present invention.

[0032] In this embodiment, the heat insulation coating material includes the following raw materials in parts by weight: Film-forming substances (35g epoxy resin and 2g titanium dioxide), 2g SiO2, 47 mL mixed solvent (59% vol toluene, 31% vol acetone, 4% vol ethylene glycol butyl ether acetate, 6% vol methyl ethyl ketone), 19 g curing agent A (polyamide 650), and 3.15 parts curing agent B (0.75 g tetraethylenepentamine and 2.4 g isopropyl ketone).

[0033] The method for preparing the heat insulation coating material in this embodiment includes the following steps: S1. Add SiO2 filler to epoxy resin and titanium dioxide to obtain a mixture; S2. Add the prepared mixed solvent to the mixture and stir for 12-20 minutes to obtain a mixed solution; S3. Add curing agent A and curing agent B to the mixed solution and stir for 15-20 minutes to form a dense and uniform cross-linked network structure to obtain the heat insulation coating material.

[0034] The application of the thermal insulation coating material in the wind tunnel test thermal model in this embodiment includes the following steps: Apply the heat insulation coating material to the surface of the metal model using a brush with a width smaller than the brushing area. The brush tilt angle should not exceed 45°, and the brush should only pass through an area once. After each coat is applied, allow it to cure at room temperature and let the surface dry before applying the next coat. Repeat the brushing process until the entire surface of the metal model is covered with the heat-insulating coating material. Dry or air-dry the metal model coated with the heat-insulating material to allow the surface coating to cure. The metal model is then polished and shaped after the surface coating has cured.

[0035] Example 2 This embodiment is basically the same as embodiment 1, except that: In this embodiment, the heat insulation coating material includes the following raw materials in parts by weight: Film-forming substances (33 g epoxy resin and 13.2 g titanium dioxide), 1 g SiO2, 42 mL mixed solvent (55% vol toluene, 36% vol acetone, 5% vol ethylene glycol butyl ether acetate, 5% vol butanone), 19 g curing agent A (polyamide 650), and 0.6 g tetraethylenepentamine and 2.4 g isopropyl ketone.

[0036] Example 3 This embodiment is basically the same as embodiment 1, except that: In this embodiment, the heat insulation coating material includes the following raw materials in parts by weight: Film-forming substances (38 g epoxy resin and 11.4 g titanium dioxide), 2 g SiO2, 45 mL mixed solvent (67% vol toluene, 24% vol acetone, 4% vol ethylene glycol butyl ether acetate, 6% vol methyl ethyl ketone), 20 g curing agent A (polyamide 650), and 2.8 g curing agent B (1.2 g tetraethylenepentamine and 2.8 g isopropyl ketone).

[0037] Example 4 This embodiment is basically the same as embodiment 1, except that: In this embodiment, the heat insulation coating material includes the following raw materials in parts by weight: Film-forming substances (35 g epoxy resin and 14 g titanium dioxide), 3 g SiO2, 50 mL mixed solvent (60% vol toluene, 30% vol acetone, 4% vol ethylene glycol butyl ether acetate, 5% vol methyl ethyl ketone), 21 g curing agent A (polyamide 650), and 0.8 g tetraethylenepentamine and 3.2 g isopropyl ketone.

[0038] Compare with Example 1 This embodiment is basically the same as Embodiment 1, except that SiO2 filler is not added to the heat insulation coating material in this embodiment.

[0039] Compare with Example 2 This embodiment is basically the same as Embodiment 1, except that curing agent B is not added to the heat insulation coating material in this embodiment.

[0040] Compare with Example 3 This embodiment is basically the same as Embodiment 1, except that ethylene glycol butyl ether acetate is not used in the mixed solvent of the heat insulation coating material in this embodiment.

[0041] Compare with Example 4 This embodiment is basically the same as Embodiment 1, except that: in this embodiment, the amount of SiO2 filler in the heat insulation coating material is greatly increased to 10 g, while the amount of film-forming material is reduced by the same amount.

[0042] Compare with Example 5 This embodiment is basically the same as embodiment 1, except that the coating material prepared in embodiment 1 is applied to the surface of the metal model using a spraying process.

[0043] The roughness, thermal conductivity, and thermal diffusivity of the wind tunnel test thermal map models obtained in Examples 1-4 and Comparative Examples 1-5 were tested in this invention. The test results are shown in Table 1.

[0044] Table 1 Test Results

[0045] As shown in Table 1, this invention successfully prepared a heat-insulating coating that simultaneously meets the requirements of "low thermal conductivity", "high smoothness" and "strong adhesion" by selecting specific components and matching them with a brushing process. This enables rapid, low-cost, and high-quality processing of thermal models, fundamentally solving the core pain points of traditional technologies, such as long cycles, high costs, and high risks.

[0046] Among them, the thermal conductivity of control example 1 deteriorated significantly, further proving that SiO2 is the key thermal insulation filler. Its absence caused the coating to lose its effective thermal barrier function, and the thermal conductivity and thermal diffusion capacity increased significantly.

[0047] In contrast to Example 2, which did not use curing agent B, the initial curing was slow, which may lead to sagging, sticky surface, or dust contamination, resulting in excessive roughness.

[0048] In contrast, Example 3 did not use a high-boiling-point solvent, which caused the solvent to evaporate too quickly, preventing the brush marks from leveling out. As a result, the surface roughness was severely exceeded.

[0049] Although the high filler content in Comparative Example 4 further reduced the thermal conductivity, it made the coating too brittle, and it was easy to produce particle peeling and scratches during sanding, resulting in extremely high roughness and potentially reduced adhesion.

[0050] In contrast to Example 5, the spraying process resulted in a large amount of solvent atomization and evaporation, which led to poor leveling properties of the paint droplets when they reached the surface. At the same time, overspraying reduced material utilization.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heat insulation coating material, characterized in that, The ingredients include the following parts by weight: The mixture consists of 45-50 parts film-forming substance, 1-3 parts filler, 42-48 parts mixed solvent, 19-21 parts curing agent A, and 3-4 parts curing agent B. The film-forming material includes epoxy resin and titanium dioxide; The filler is SiO2; The mixed solvent includes toluene, acetone, ethylene glycol butyl ether acetate, and methyl ethyl ketone; The curing agent A includes a modified fatty amine curing agent; The curing agent B comprises a mixed solution of tetraethylenepentamine and isopropanone.

2. The heat insulation coating material according to claim 1, characterized in that, The titanium dioxide content in the film-forming material is 30% to 40% of the epoxy resin content.

3. The heat insulation coating material according to claim 1, characterized in that, In the mixed solvent, the volume fraction of toluene is 55%~67%, the volume fraction of acetone is 24%~36%, the volume fraction of ethylene glycol butyl ether acetate is 4%~5%, and the volume fraction of butanone is 5%~6%.

4. The heat insulation coating material according to claim 1, characterized in that, In the curing agent B, the mass ratio of tetraethylenepentamine to isopropyl ketone is (2~3):(7~8).

5. A method for preparing the heat-insulating coating material according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Add SiO2 filler to the film-forming material to obtain a mixture; S2. Add the prepared mixed solvent to the mixture and stir for 12-20 min to obtain a mixed solution; S3. Add curing agent A and curing agent B to the mixed solution and stir for 15-20 minutes to obtain the heat insulation coating material.

6. The application of the thermal insulation coating material according to any one of claims 1-4 in a wind tunnel test thermal model, characterized in that, Includes the following steps: Apply a heat-insulating coating material to the surface of the metal model; Dry or air-dry the metal model coated with the heat-insulating material to allow the surface coating to cure. The metal model is then polished and shaped after the surface coating has cured.

7. The application according to claim 6, characterized in that, When applying the coating, a brush with a width smaller than the surface to be coated is used, the brush tilt angle is no more than 45°, and the brush passes through an area only once. The amount of heat insulation coating material applied in each layer is less than 100 g. After each coat is applied, allow it to cure at room temperature and let the surface dry before applying the next coat. Repeat the brushing process until the entire surface of the metal model is covered with the heat-insulating coating material.

8. The application according to claim 6, characterized in that, During the drying process, the temperature shall not exceed 75°C; The air-drying temperature is 15~25℃.

9. The application according to claim 6, characterized in that, After the coating cures, a milky white, smooth surface is formed on the metal model.

10. The application according to claim 6, characterized in that, During the polishing process, fine sandpaper is used to polish the metal model after the coating has cured, removing burrs from the surface and airflow steps at the model joints.

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