Composite coating structure capable of improving appearance of paint surface and automobile

Abstract

The utility model provides a composite coating structure for improving the paint surface appearance and an automobile, and relates to the technical field of paint surface appearance spraying. The utility model discloses a composite coating structure for improving the appearance of a paint surface. The composite coating structure comprises an electrophoresis layer, a middle coating, a first varnish layer, a colored paint layer and a second varnish layer which are sequentially arranged, the first varnish layer is arranged between the floating coat and the colored paint layer, and the first varnish layer is directly sprayed on the floating coat. According to the composite coating structure, the varnish layer is added between the intermediate coating and the colored paint layer, so that the defects of the surface of the intermediate coating can be made up, the flatness of the intermediate coating is improved, and the appearance of a paint surface is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paint appearance spraying technology, in particular, relates to a composite coating structure for improving paint appearance and a vehicle. BACKGROUND

[0002] In the field of automobile and industrial coating, traditional spraying processes (such as 3C2B, 3C1B and B1B2) have been widely used in paint preparation. These processes form a protective and decorative paint surface through the layer-by-layer spraying and baking of an electrophoretic layer, a basecoat layer, a color paint layer and a clearcoat layer. Specifically: 3C2B process: electrophoresis, drying, basecoat, drying, BC color paint (two-station spraying), flash drying, clearcoat and baking are performed in sequence; 3C1B process: electrophoresis, drying, BC1 basecoat, flash drying, BC2 color paint (two-station spraying), flash drying, clearcoat and baking are performed in sequence; B1B2 process: electrophoresis, drying, BC1 basecoat, BC2 color paint (two-station spraying), flash drying, clearcoat and baking are performed in sequence.

[0003] Although the above processes are relatively mature in terms of paint protection and decoration, they face significant bottlenecks in further improving the appearance quality of the paint surface (common evaluation indicators are LW, SW and DOI). Specifically: 1. Insufficient flatness of the basecoat layer: after the basecoat layer is sprayed, due to the unevenness of the substrate itself and the Benard vortex formed during the leveling and drying of the basecoat paint surface, microscopic defects exist on the surface of the basecoat layer. These defects are amplified after the subsequent color paint and clearcoat are sprayed, affecting the overall appearance of the paint surface. 2. Difficulty in improving appearance indicators: under existing process conditions, key appearance indicators such as long wave (LW), short wave (SW) and image clarity (DOI) of the paint surface have reached the limit of materials and processes, and further optimization through traditional methods is difficult. For example, it is difficult to further reduce the values of LW and SW, and it is difficult to further improve the value of DOI, resulting in the inability of the paint surface appearance to meet the needs of the high-end market. CONTENT OF THE UTILITY MODEL

[0004] The purpose of the present application is to provide a composite coating structure for improving the appearance of the paint surface, to compensate for the defects on the surface of the basecoat layer, improve the flatness of the basecoat layer, and further improve the appearance of the paint surface.

[0005] In a first aspect, the embodiments of the present application provide a composite coating structure for improving the appearance of the paint surface, having the following coating layers arranged in sequence: an electrophoretic layer, a basecoat layer, a first clearcoat layer, a color paint layer and a second clearcoat layer; the first clearcoat layer is arranged between the basecoat layer and the color paint layer, and the first clearcoat layer is directly sprayed on the basecoat layer.

[0006] After the midcoat spraying, due to the unevenness of the substrate (such as the electrophoretic layer), the formation of the Benard vortex, and the limitations of the spraying process, etc., there are often microscopic defects on the surface, which will directly affect the flatness of the subsequent color paint layer and varnish layer, leading to the decline of the appearance quality of the paint surface, which is manifested as high long wave (LW) and short wave (SW) values, and low image definition (DOI). Spraying the first varnish layer on the midcoat layer can effectively fill the microscopic concave-convex and Benard vortex on the surface of the midcoat layer; the varnish material forms a smooth and uniform surface through leveling after spraying, which can significantly reduce the influence of the defects of the bottom layer on the upper layer; moreover, the low surface tension characteristics of the varnish enable it to better wet the surface of the midcoat layer, reducing problems such as orange peel and shrinkage caused by the difference in surface tension, and by reducing the surface tension, the varnish layer can form a more uniform film thickness distribution, further improving the flatness of the midcoat layer. Therefore, through the filling and optimization of the first varnish layer, the appearance quality of the paint surface can be significantly improved (reducing LW and SW values, and increasing DOI value).

[0007] In a possible implementation manner, the thickness of the first varnish layer is 35-45 μm.

[0008] In the above technical solution, by controlling the thickness of the first varnish layer to be 35-45 μm, the microscopic concave-convex and Benard vortex on the surface of the midcoat layer can be effectively filled, the defects caused by the unevenness of the bottom layer can be improved, and the quality of the appearance of the paint surface can be further improved.

[0009] In a possible implementation manner, the thickness of the second varnish layer is 50-65 μm.

[0010] The second varnish layer is sprayed on the surface of the color paint, which is the outermost layer, and spraying 50-65 μm of varnish can effectively enhance the wear resistance and scratch resistance of the coating, protecting the bottom layer from physical damage; it can also better resist the erosion of chemical substances and protect the stability of the coating in various environments. Moreover, the second varnish within the above thickness range can provide better gloss and definition, enhancing the aesthetic appearance of the paint surface.

[0011] In a possible implementation manner, the thickness of the electrophoretic layer is 15-25 μm.

[0012] In the above technical solution, by controlling the thickness of the electrophoretic layer to be between 15-25 μm, the corrosion resistance of the coating can be effectively improved, and the substrate (such as metal) can be protected from environmental factors (such as moisture and chemical substances); the adhesion between the electrophoretic layer and the substrate can also be improved, providing a stable foundation for the subsequent midcoat layer and varnish layer. Moreover, the electrophoretic coating usually has good fluidity, and controlling the thickness within the range of 15-25 μm can make the coating uniformly distributed, thereby providing a good base color for the subsequent midcoat layer and first varnish layer, and enhancing the overall appearance of the coating.

[0013] In a possible implementation, the thickness of the intermediate coating layer is 15-35 μm.

[0014] In the above technical solution, by controlling the thickness of the intermediate coating layer to be 15-35 μm, the micro defects on the surface of the base layer (such as the electrophoretic layer) can be effectively filled, and the overall surface flatness can be improved; the adhesion between the base layer and the upper coating layer can be improved, and the stability of the overall coating layer can be enhanced; the gloss and clarity of the subsequent first varnish layer can be enhanced, and the paint surface can be more attractive.

[0015] In a possible implementation, the materials of the first varnish layer and the second varnish layer are consistent.

[0016] In a possible implementation, no other layer structure is arranged between the electrophoretic layer and the intermediate coating layer.

[0017] In a possible implementation, no other layer structure is arranged between the intermediate coating layer and the first varnish layer.

[0018] In a possible implementation, no other layer structure is arranged between the first varnish layer and the color paint layer.

[0019] In a possible implementation, no other layer structure is arranged between the first varnish layer and the color paint layer.

[0020] The composite coating structure adds a varnish layer between the color paint layer and the intermediate coating layer, so that the paint surface of the vehicle body has higher flatness, gloss, and image clarity (DOI), and the long-wave (LW) and short-wave (SW) values are reduced, so that the appearance of the vehicle body is more beautiful. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0022] Figure 1 The structural schematic diagram of the composite coating structure provided by the embodiments of the present application;

[0023] Figure 2 The structural schematic diagram of the composite coating structure under the traditional process.

[0024] Legend: 100-electrophoretic layer; 200-intermediate coating layer; 300-first varnish layer; 400-color paint layer; 500-second varnish layer. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0027] It should be noted that similar reference numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0028] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, or the orientations or positional relationships in which the products of the present application are usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third", etc. are only used for differentiation in description and cannot be understood as indicating or implying relative importance.

[0029] In addition, the terms "horizontal", "vertical", "overhanging", etc. do not mean that the components must be absolutely horizontal or overhanging, but can be slightly inclined. For example, "horizontal" only means that it is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0030] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "arrange", "mount", "connect", "connect" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0031] The conventional spraying process of 3C2B is: electrophoresis → drying → spraying middle coating → drying → spraying BC color paint → flash drying → spraying varnish → drying.

[0032] The traditional 3C1B spraying process is: electrophoresis → drying → spraying BC1 intermediate coating → flash drying → spraying BC2 color paint → flash drying → spraying varnish → drying.

[0033] The traditional B1B2 spraying process is: electrophoresis → drying → spraying BC1 intermediate coating → spraying BC2 color paint → flash drying → spraying varnish → drying.

[0034] Please refer to Figure 1 and Figure 2 , Figure 1 a structure diagram of a composite coating structure provided by the embodiment of the application; Figure 2 a structure diagram of a composite coating structure under a traditional process.

[0035] The embodiment provides a composite coating structure for improving the appearance of a paint surface, which has the following coating layers arranged in sequence: an electrophoresis layer 100, an intermediate coating layer 200, a first varnish layer 300, a color paint layer 400 and a second varnish layer 500; the first varnish layer 300 is arranged between the intermediate coating layer 200 and the color paint layer 400, and the first varnish layer 300 is directly sprayed on the intermediate coating layer 200.

[0036] The composite coating structure provided by the application fills the surface defects of the intermediate coating layer 200 by adding the first varnish layer 300 between the traditional intermediate coating layer 200 and the color paint layer 400, improves the flatness of the bottom layer, and significantly improves the appearance quality of the paint surface in combination with the synergistic effect of multiple layers. Specifically, the intermediate coating layer 200 is prone to form Bernhard vortex or concave-convex caused by uneven substrate during the drying process, and the first varnish layer 300 covers and fills these defects due to high flow leveling, forming a smooth transition surface. The smooth intermediate coating-varnish composite layer provides a uniform substrate for the color paint, reduces the problems such as orange peel and shrinkage of the color paint layer 400 caused by uneven bottom layer, and improves the gloss and consistency of the final paint surface. It is shown that: after the combination of the first varnish layer 300 and the color paint layer 400, the image clarity of the paint surface is improved (DOI value is increased by 1-2 points) by reducing light scattering; the flatness of the bottom layer is improved, which significantly optimizes the long wave (LW value is reduced by 1-2 points) and short wave (SW value is reduced by 2-5 points) of the paint surface, and reduces the visual corrugation feeling.

[0037] The thickness of the first varnish layer 300 is 35-45 μm. As an example, the thickness of the first varnish layer 300 includes but is not limited to 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm.

[0038] By controlling the thickness of the first varnish layer 300 within the above range, the first varnish layer 300 is facilitated to form a smooth and uniform surface after spraying through leveling effect, significantly reducing the influence of the underlying defects on the subsequent coating, thereby improving the overall flatness. The thickness of 35-45 μm can enable the varnish to better wet the surface of the intermediate coating 200, reduce problems such as orange peel and shrinkage caused by differences in surface tension, and improve the appearance quality of the coating.

[0039] The thickness of the second varnish layer 500 is 50-65 μm. As an example, the thickness of the second varnish layer 500 includes but is not limited to 50 μm, 51 μm, 52 μm, 53 μm, 54 μm, 5 μm, 56 μm, 57 μm, 58 μm, 59 μm, 60 μm, 61 μm, 62 μm, 63 μm, 64 μm, 65 μm.

[0040] The second varnish layer 500 as the outermost layer directly affects the gloss, smoothness and clarity of the paint surface. Controlling the thickness within 50-65 μm can enable the paint surface to have sufficient gloss and clarity, while reducing the long wave (LW) and short wave (SW) values, and improving the image clarity (DOI). One of the main functions of the second varnish layer 500 is to protect the underlying coating (such as the color paint layer 400 and the intermediate coating 200) from external environment (such as ultraviolet light, chemicals, physical wear, etc.). Therefore, the second varnish layer 500 of 50-65 μm can provide sufficient protection and prolong the durability of the paint surface. The second varnish layer 500 forms a smooth and uniform surface after spraying through leveling effect, and controlling the thickness within the range of 50-65 μm can enable the second varnish layer 500 to be uniformly distributed, reduce surface defects such as orange peel and shrinkage, and further improve the flatness and appearance quality of the paint surface.

[0041] In this application, the material of the first varnish layer 300 is consistent with the material of the second varnish layer 500, and the existing varnish layer material can be sprayed.

[0042] Optionally, the first varnish layer 300 and the second varnish layer 500 are both made of existing varnish materials with a surface tension of 34-36 dyn / cm and a leveling time of 8-15 min; the electrophoretic layer 100 is made of epoxy resin and adhesive; the intermediate coating 200 is made of one or more of polyurethane resin, alkyd resin and amino resin.

[0043] The varnish material with a surface tension of 34-36 dyn / cm can better wet the surface of the intermediate coating layer 200 or the color paint layer 400, reduce the problem of poor wetting caused by the difference in surface tension (such as orange peel, shrinkage, etc.), and facilitate the uniform coverage of the varnish layer on the bottom layer to form a smooth and continuous film layer, thereby improving the adhesion between the coating layers. The varnish material with a leveling time of 8-15 min has enough time to flow and form a smooth surface after spraying, which helps to reduce the microscopic concave-convex and defects of the paint surface and significantly improve the flatness and gloss of the paint surface. That is, the lower surface tension (34-36 dyn / cm) enables the varnish to better fill the microscopic defects (such as Bernhard vortex, orange peel, etc.) of the bottom coating layer, and the moderate leveling time (8-15 min) ensures that the varnish can be fully leveled before curing to form a uniform film thickness distribution, thereby reducing the long wave (LW) and short wave (SW) values of the paint surface and improving the image clarity (DOI). The thickness of the electrophoretic layer 100 is 15-25 μm. As an example, the thickness of the electrophoretic layer 100 includes but is not limited to 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm.

[0044] The electrophoretic layer 100 is the coating layer closest to the substrate in the coating structure, and its main function is to provide corrosion protection. The thickness controlled at 15-25 μm can enable the electrophoretic layer 100 to uniformly cover the substrate and form a dense protective film, effectively preventing the penetration of moisture, oxygen and corrosive substances, thereby prolonging the service life of the substrate. As a bottom coating layer, the electrophoretic layer 100 needs to have good adhesion with the substrate and other coating layers (such as the intermediate coating layer 200). The thickness of 15-25 μm can form a firm bond between the electrophoretic layer 100 and the substrate, while providing a good adhesion basis for the intermediate coating layer 200, reducing the peeling or delamination of the coating layer. In addition, the electrophoretic layer 100 is formed by electrophoretic deposition during the coating process, which can uniformly cover the surface of the substrate and fill the microscopic unevenness of the substrate. The thickness of 15-25 μm can improve the corrosion resistance while providing a relatively flat basis for the subsequent coating layer (such as the intermediate coating layer 200), reducing the defects of the subsequent coating layer. Therefore, the thickness of 15-25 μm can provide a smooth and uniform surface for the intermediate coating layer 200, reduce the defects (such as orange peel, shrinkage, etc.) of the subsequent coating layer, and ultimately improve the appearance quality of the paint surface.

[0045] In this application, the material of the electrophoretic layer 100 is not improved, and the existing material of the electrophoretic layer 100 can be used for spraying.

[0046] The thickness of the intermediate coating layer 200 is 15-35 μm. For example, the thickness of the intermediate coating layer 200 includes but is not limited to 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm.

[0047] The intermediate coating layer 200 is located between the electrophoretic layer 100 and the color paint layer 400, one of its main functions is to fill the micro defects of the electrophoretic layer 100 and provide a flat base for the color paint layer 400. The thickness of 15-35 μm can effectively cover the uneven surface of the electrophoretic layer 100, reduce the defects (such as orange peel, shrinkage, etc.) of the subsequent color paint layer 400 and varnish layer, thereby improving the overall flatness and appearance quality of the paint surface. The intermediate coating layer 200 needs to have good adhesion with the electrophoretic layer 100 and the color paint layer 400, so the thickness of 15-35 μm can make the intermediate coating layer 200 form a firm bond with the upper and lower coating layers, reduce the peeling or delamination of the coating, and improve the overall durability of the coating. The intermediate coating layer 200 plays a certain buffering role in the coating structure, which can absorb the energy of external impact (such as stone impact) and protect the underlying electrophoretic layer 100 and the substrate. The thickness of 15-35 μm can ensure flexibility while providing sufficient stone impact resistance, prolonging the service life of the paint surface.

[0048] In this application, the material of the intermediate coating layer 200 is not improved, and the existing material of the intermediate coating layer 200 can be sprayed.

[0049] For example, the spraying method of each layer of the present application is air spray or robot spray.

[0050] Embodiment

[0051] The composite coating structure provided by the present application is suitable for 3C2B, 3C1B or B1B2 spraying process for preparation, and the preparation of the composite coating structure will be described in detail below using 3C2B, 3C1B or B1B2 spraying process.

[0052] Embodiment 1. 3C2B spraying process

[0053] S1. Spray the electrophoretic layer 100 with a thickness of 20 μm, and bake at 170°C for 20 min to cure the electrophoretic layer 100.

[0054] S2. Use a one-station robot to spray the intermediate coating layer 200 with a thickness of 31 μm, and bake the intermediate coating layer 200 at 150°C for 20 min to promote curing.

[0055] S3. Sand the midcoat 200 using 600# or finer sandpaper to remove surface defects.

[0056] S4. Spray the first clearcoat layer 300 over the sanded midcoat 200, with a thickness of 42 pm, and bake at 140 °C for 20 min. Then sand the first clearcoat layer 300 again to improve the surface smoothness.

[0057] S5. Sand the first clearcoat layer 300 using 600# or finer sandpaper to remove surface defects.

[0058] S6. Spray the colorcoat using a two-station spray process.

[0059] S7. Flash dry the colorcoat layer 400 at 85 °C for 3 min to quickly evaporate the solvent, resulting in a colorcoat layer 400 with a thickness of 15 pm.

[0060] S8. Flash dry at 85 °C for 3 min, and spray the second clearcoat layer 500 over the colorcoat layer 400, with a thickness of 60 pm, then bake at 140 °C for 20 min.

[0061] Example 2. 3C1B spray process

[0062] S1. Spray the electrophoretic layer 100 with a thickness of 20 pm, and bake at 170 °C for 20 min to cure the electrophoretic layer 100.

[0063] S2. Spray the midcoat 200 using a one-station robot, with a thickness of 22 pm, and bake at 150 °C for 20 min to promote curing.

[0064] S3. Spray the first clearcoat layer 300 over the midcoat 200, with a thickness of 40 pm, and bake at 140 °C for 20 min, then sand the first clearcoat layer 300 again to improve the surface smoothness.

[0065] S4. Sand the first clearcoat layer 300 using 600# or finer sandpaper to remove surface defects.

[0066] S5. Spray the colorcoat using a two-station spray process.

[0067] S6. Flash dry the colorcoat layer 400 at 85 °C for 3 min to quickly evaporate the solvent, resulting in a colorcoat layer 400 with a thickness of 15 pm.

[0068] S7. Flash dry at 85 °C for 3 min, and spray the second clearcoat layer 500 over the colorcoat layer 400, with a thickness of 60 pm, then bake at 140 °C for 20 min.

[0069] Example 3. B1B2 spray process

[0070] S1. Spray the electrophoretic layer 100 with a thickness of 20 μm, and bake at 170°C for 20 min to cure the electrophoretic layer 100.

[0071] S2. Use a one-station robot to spray the intermediate coating layer 200 with a thickness of 22 μm, and bake at 150°C for 20 min to promote curing.

[0072] S3. Spray the first varnish layer 300 on the surface of the intermediate coating layer 200 with a thickness of 40 μm, and bake at 140°C for 20 min, and then polish the first varnish layer 300 again to improve the surface smoothness.

[0073] S4. Use sandpaper with a particle size of 600# or above to polish the first varnish layer 300 throughout the vehicle to eliminate surface defects.

[0074] S5. Use a two-station spraying process to spray the color paint.

[0075] S6. Flash dry the color paint layer 400 at 85°C for 3 min to quickly evaporate the solvent, and obtain a color paint layer 400 with a thickness of 15 μm.

[0076] S7. Flash dry at 85°C for 3 min, spray the second varnish layer 500 on the color paint layer 400 with a thickness of 60 μm, and then bake at 140°C for 20 min.

[0077] Experimental Example

[0078] In this experimental example, the paint appearance effects of the composite coating structures provided in the above embodiments (prepared using 3C2B, 3C1B and B1B2 spraying processes, respectively) and the coating structures prepared using traditional 3C2B, 3C1B and B1B2 spraying processes were determined, including long wave (LW) value, short wave (SW) value and image clarity (DOI) value. The determination results of the above items are shown in Tables 1, 2 and 3.

[0079] Table 1

[0080]

[0081] Table 2

[0082]

[0083] Table 3

[0084]

[0085] From the results of Table 1, Table 2 and Table 3 above, it can be seen that the present application can significantly reduce the LW value, the SW value, and improve the DOI value by adding a layer of varnish between the midcoat 200 and the color paint layer 400.

[0086] The above description is merely the preferred embodiments of the present application, and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, and the like made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A composite coating structure for improving the appearance of a paint film, characterized by, The coating has the following coating layers arranged in sequence: an electrophoretic layer, a middle coating layer, a first varnish layer, a color paint layer and a second varnish layer. The first varnish layer is arranged between the middle coating layer and the color paint layer, and the first varnish layer is directly sprayed on the middle coating layer.

2. The composite coating structure of claim 1, wherein The thickness of the first varnish layer is 35-45 microns.

3. The composite coating structure of claim 2, wherein, The thickness of the second varnish layer is 50-65 microns.

4. The composite coating structure of claim 1, wherein, The thickness of the electrophoretic layer is 15-25 microns.

5. The composite coating structure of claim 1, wherein, The thickness of the middle coating layer is 15-35 microns.

6. The composite coating structure of claim 1, wherein, The materials of the first varnish layer and the second varnish layer are consistent.

7. The composite coating structure of claim 6, wherein, No other layer structure is arranged between the electrophoretic layer and the middle coating layer.

8. The composite coating structure of claim 7, wherein, No other layer structure is arranged between the middle coating layer and the first varnish layer.

9. The composite coating structure of claim 1, wherein, No other layer structure is arranged between the first varnish layer and the color paint layer.

10. An automobile characterized by comprising: The body surface of the automobile is sprayed with the composite coating structure according to any one of claims 1-9.

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