Collinear coating process for non-metal part and metal part

Abstract

The invention belongs to the technical field of automobile coating, and relates to a collinear coating process for a non-metal part and a metal part. The conductive primer is sprayed on the surface of the non-metal part in advance, so that the non-metal part has conductivity, then the non-metal part and the metal part coated with the primer are assembled, the same base paint and varnish are integrally sprayed through the electrostatic rotating cup, and therefore the color difference between the metal part and the non-metal part in the conductive assembly is reduced; finally, high-temperature baking is performed to improve the paint film quality. According to the collinear coating process for the nonmetal and metal conductive assemblies, the color difference E between the metal part and the nonmetal part in the conductive assemblies can be reduced to be smaller than 3, the color difference problem is obviously solved, the coating efficiency is high, and the coating quality is good.

Description

Technical Field

[0001] The invention relates to the technical field of automobile coating, and in particular to a co-linear coating process for non-metallic parts and metal parts. Background Art

[0002] With the development of coating technology, users' requirements for the quality of commercial vehicle paint coatings are constantly improving, and society's awareness of energy conservation and consumption reduction and environmental protection is constantly increasing. It is a development trend to use electrostatic spraying of metallic topcoat on the non-metallic parts and metal body of commercial vehicles to avoid color difference of paint film caused by electrostatic spraying of body and non-metallic parts, reduce costs and reduce VOC emissions.

[0003] Lightweight is the main characteristic of commercial vehicles and an important factor affecting vehicle energy efficiency. Non-metallic parts are increasingly used in vehicle exterior parts. There are generally about 10 non-metallic exterior parts. Compared with passenger car body exterior parts, the number of non-metallic exterior parts has increased significantly. With the improvement of automobile quality requirements, the consistency of painting quality requirements between non-metallic parts and body metal parts is more stringent. In order to ensure quality consistency and technology upgrades, research on co-linear painting of non-metallic exterior parts and body topcoat is conducted.

[0004] At present, the domestic method of separately painting metal parts and non-metal parts is adopted, and its main disadvantages are as follows: there are great differences in the coating materials and processes of the separately painted non-metallic parts and the cab body, which can easily lead to color differences between the non-metallic parts and the cab body, affecting the consistency of the appearance quality of the whole vehicle; there are great differences in the coating materials and processes of the non-metallic parts in different parts that are separately painted, which can easily lead to color differences between the non-metallic parts in different parts, affecting the consistency of the appearance quality of the whole vehicle and increasing energy consumption. Summary of the invention

[0005] The present invention provides a co-linear coating process for non-metallic parts and metal parts, so as to solve the problems in the related art such as large color difference between metal parts and non-metallic parts, low coating utilization rate, poor spraying stability, low coating efficiency, etc.

[0006] In a first aspect, the present invention provides a co-linear coating process for non-metallic parts and metal parts, comprising the following steps:

[0007] Pre-treating the non-metallic parts, applying conductive primer, and baking them to obtain non-metallic intermediate parts;

[0008] The metal parts are sequentially pre-treated, electrophoretic primer coated, and baked to obtain metal intermediate parts;

[0009] Assembling the non-metallic intermediate part and the metallic intermediate part into a conductive assembly;

[0010] Use an electrostatic rotary cup to spray the entire conductive component with base paint and varnish, and finally bake it at high temperature.

[0011] The present invention pre-sprays a conductive primer on the surface of a non-metallic part to make the non-metallic part conductive, then assembles the non-metallic part with the metal part coated with the primer, and uses an electrostatic rotary cup to spray the same base paint and varnish on the whole, thereby reducing the color difference between the metal parts and the non-metallic parts in the conductive assembly, and finally performs high-temperature baking to improve the quality of the paint film. The use of this coating process can greatly improve the coating utilization rate, spraying stability and spraying efficiency.

[0012] In some embodiments of the present invention, the surface resistance of the conductive primer is less than 10 6 Ω, when the surface resistance of the conductive primer is too high, the conductive primer has poor conductivity, the base paint is unevenly distributed on the surface of the conductive primer, and the varnish is unevenly distributed on the surface of the base paint, which ultimately leads to a large color difference between the non-metallic parts and the metal parts in the conductive component, and a large difference in the coating quality, which seriously affects the coating consistency. Preferably, the surface resistance of the conductive primer is 10 4 Ω~10 6 Ω, the conductive primer with a surface resistance within this range has good conductivity and fluidity. The good fluidity ensures the uniform color of the conductive primer itself.

[0013] In some embodiments of the present invention, the base paint is a metal base paint. The surface resistance of the conductive base paint affects the uniformity of the metal powder in the metal base paint. Therefore, the surface resistance of the conductive base paint is controlled within 10 4 Ω~10 6 Ω, which can avoid the aggregation of metal powder in the metallic base paint.

[0014] In some embodiments of the present invention, the metal parts are metal structural parts of the vehicle; and / or, the non-metallic parts are non-metallic exterior parts of the vehicle. Further, the metal structural parts include at least one of the following: the body shell, the engine cover, the top cover, the trunk lid, the fender, the front panel, the rear panel, the side panel, the floor, the door, the window, the spoiler, the trailer panel, the trailer floor, and the trailer roof cover; and / or, the non-metallic exterior parts include at least one of the following: the bumper, the air intake grille, the rearview mirror, the side skirt, the pillar decorative panel, the luggage rack, and the door handle.

[0015] In some embodiments of the present invention, the coating thickness of the electrophoretic primer is 18 to 30 microns; and / or the coating thickness of the conductive primer is 18 to 30 microns; and / or the coating thickness of the base paint is 15 to 25 microns.

[0016] In some embodiments of the present invention, the baking temperature of the electrophoretic primer is 175±2°C; and / or, the baking temperature of the conductive primer is 80±2°C; and / or, the baking temperature of the base color paint is 140±2°C.

[0017] In some embodiments of the present invention, the pretreatment of the metal part is a phosphating pretreatment; and / or the pretreatment of the non-metal part includes surface cleaning with an organic solvent.

[0018] In some embodiments of the present invention, the assembly is complete assembly or semi-assembly.

[0019] In some embodiments of the present invention, after spraying the base paint and the clear paint, flash drying is performed at room temperature; and / or the temperature of high-temperature baking is 140±2°C.

[0020] In a second aspect, the present invention provides a vehicle, which is coated by the above-mentioned co-linear coating process of non-metallic and metallic conductive components. The vehicle is a commercial vehicle, a passenger vehicle or a special vehicle.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] The co-linear coating process of non-metallic and metal conductive components provided by the present invention can reduce the color difference between metal parts and non-metallic parts in the conductive components to ΔE<3, significantly reducing the color difference between metal parts and non-metallic parts, and has high coating efficiency, good coating quality and high coating utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 : The connection method of metal intermediate parts and non-metallic intermediate parts with the same resistance value in the same electric field.

[0025] Figure 2 : The connection method of metal intermediate parts and non-metallic intermediate parts with different resistance values ​​in the same electric field.

[0026] Figure 3 : Shows the color difference between the metal finished product and the non-metal finished product in connection method b. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range. Similarly, any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.

[0029] It should be noted that, in the description of this article, unless otherwise specified, "above", "below" include the number, and the meaning of "multiple" in "one or more" is two or more. Relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements.

[0030] In the description of this specification, the description with reference to the terms "any embodiment / method", "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0031] The above summary of the invention of the present invention is not intended to describe each disclosed embodiment or each implementation in the present invention. The following description more specifically illustrates exemplary embodiments. These embodiments can be used in various combinations. In each example, the enumeration is only used as a representative group and should not be interpreted as exhaustive.

[0032] Unless otherwise specified, the test method used by the present invention to determine the color difference between metal parts and non-metal parts is as follows: using an X-RITE brand multi-angle colorimeter, taking the color of metal parts as the standard, the color difference value of non-metal parts is measured.

[0033] Painting process:

[0034] The present invention provides a co-linear coating process for non-metallic parts and metal parts, comprising the following steps:

[0035] Pre-treating the non-metallic parts, applying conductive primer, and baking them to obtain non-metallic intermediate parts;

[0036] The metal parts are sequentially pre-treated, electrophoretic primer coated, and baked to obtain metal intermediate parts;

[0037] Assembling the non-metallic intermediate part and the metallic intermediate part into a conductive assembly;

[0038] Use an electrostatic rotary cup to spray the entire conductive component with base paint and varnish, and finally bake it at high temperature.

[0039] The present invention pre-sprays a conductive primer on the surface of a non-metallic part, thereby making the non-metallic part conductive, then assembles it with a metal part coated with the primer, and uses an electrostatic rotary cup to spray the same base paint and varnish on the whole, thereby reducing the color difference between the metal part and the non-metallic part in the conductive assembly, and finally improves the quality of the paint film by high-temperature baking. By adopting electrostatic rotary cup spraying, the paint utilization rate, spraying stability and spraying efficiency can be greatly improved.

[0040] In the prior art, non-metallic parts and metal parts are painted separately and then assembled together for overall spraying. Non-metallic parts are not conductive, so they can only be sprayed as a whole using non-electrostatic spraying. The spraying efficiency is low and the spraying uniformity is poor, resulting in poor overall coating quality.

[0041] The applicant found that the resistance of the conductive primer affects the color difference between metal parts and non-metal parts. It is speculated that there are two main factors affecting the color difference: 1. The resistance value affects the arrangement of the metal powder in the metallic paint, resulting in color difference; 2. The change in resistance value affects the color of the conductive primer itself, resulting in color difference. The resistance range of the conductive primer used in the present invention is 10 4 Ω~10 6 Ω, when the surface resistance of the conductive primer is 10 4 Ω~10 6 Ω, the color difference between the metal parts and non-metal parts in the conductive component is small; and when the surface resistance of the conductive primer is between 10 4 Ω~10 6When the conductive primer is outside the range of Ω, under the co-linear coating process of the present invention, a large color difference occurs between the non-metallic parts and the metal parts in the conductive component, which seriously affects the color consistency of the conductive component. In addition, the conductive primer should also meet the adhesion ≦1 level.

[0042] There is no need to limit the type of conductive primer, and those skilled in the art can use any conductive primer with a resistance between 10 4 Ω~10 6 The conductive primer with a resistance of 10Ω and an adhesion of ≤1 can be sprayed on non-metallic parts to make them conductive. 4 Ω~10 6 The conductive primer can be selected from graphene, carbon nanotubes, silver nanowires, titanium dioxide, etc. In the embodiment of the present invention, the same series of commercially available conductive primers with different resistances are used to discuss the effect of different resistances on the color difference between non-metallic parts and metal parts, which should not be regarded as a limitation on the types of conductive primers. Those skilled in the art can add a certain amount of carbon nanotubes to ordinary non-conductive primers to prepare conductive primers that meet different resistance requirements. For example, 0.8wt% to 1.1wt% of carbon nanotubes are added to the non-conductive primer to prepare a conductive primer with a resistance between 10 4 Ω~10 6 Conductive primer in the Ω range.

[0043] There is no need to limit the types of metal parts and non-metal parts to which the coating process of the present invention is applicable. Common metal parts and non-metal parts can all be integrally coated using the coating process of the present invention. The co-linear coating process of non-metallic and metal conductive components of the present invention is particularly suitable for fields where the conductive components are large in size, such as vehicles, ships, and airplanes. In the prior art, these conductive components are large in size and do not have suitable spraying devices, so manual spraying is often used, resulting in large differences in the coating quality of various parts of the conductive components. The present invention uses an electrostatic rotary cup method for overall spraying to optimize the coating quality and improve the coating efficiency. In some embodiments of the present invention, the metal parts are metal structural parts of the vehicle; and / or the non-metal parts are non-metallic exterior parts of the vehicle. In some embodiments of the present invention, the metal structural parts are at least one of the following: the vehicle body shell, the engine cover, the top cover, the trunk cover, the fender, the front wall, the rear wall, the side wall, the floor, the door, the window, the spoiler, the trailer wall, the trailer floor, and the trailer top cover; the non-metallic exterior parts are at least one of the following: the bumper, the air intake grille, the rearview mirror, the side skirt, the pillar decorative plate, the luggage rack, and the door handle. Those skilled in the art can apply primer to the metal parts and non-metal parts with the same target color according to the vehicle appearance design scheme, and then assemble them together for overall painting.

[0044] In some embodiments of the present invention, the coating thickness of the electrophoretic primer is 18 to 30 microns; and / or, the coating thickness of the conductive primer is 18 to 30 microns; and / or, the coating thickness of the base paint is 15 to 25 microns. The difference in film thickness between the electrophoretic primer and the conductive primer should be controlled between 0 and 12 microns, otherwise the overall coating quality of the product will be affected due to the large difference in film thickness. The coating thickness of the base paint is controlled within the range of 15 to 25 microns, which can effectively cover the colors of the electrophoretic primer and the conductive primer, and avoid the overall coating quality of the product due to the color difference between the electrophoretic primer and the conductive primer. Obviously, the electrophoretic primer and the conductive primer of the present invention should use coatings with similar colors, and those skilled in the art can make color selections based on experience.

[0045] In some embodiments of the present invention, the baking temperature of the electrophoretic primer is 175±2°C; and / or, the baking temperature of the conductive primer is 80±2°C; and / or, the baking temperature of the base paint is 140±2°C. These temperatures are related to the type of coating selected in the present invention and should not be regarded as limiting the baking temperature of the present invention. Those skilled in the art can adjust the baking temperature accordingly according to the type of coating selected.

[0046] The present invention adopts the dipping tank method for electrophoretic primer coating for some metal parts with large volume and poor inner cavity electrophoretic effect, and uses a cathode electrophoretic primer with a throwing power (volt box method) ≧ 210mm. In order to control the coating thickness of the electrophoretic primer between 18 and 30 microns, in some embodiments of the present invention, the electrophoretic voltage used for electrophoretic primer coating is 180V-300V, and the electrophoretic primer uses a cathode electrophoretic primer with a solid content of 18wt%±2wt%. After electrophoresis, the cathode electrophoretic primer is baked at a baking temperature of 175±2°C and a baking time of 20min. In addition, the electrophoretic primer used in the present invention should meet the requirements of Q / DFCVCM3958 standard.

[0047] In order to improve the adhesion of the base paint and the overall coating quality, the present invention grinds the conductive primer and the electrophoretic primer before spraying the base paint. Preferably, the conductive primer and the electrophoretic primer are grinded with sandpaper of 800 mesh or above, and then dust is removed with sticky gauze.

[0048] The spraying method of the conductive primer of the present invention is air spray gun spraying, the baking temperature is 80±2° C., and the baking time is not less than 30 minutes, preferably 30 to 40 minutes.

[0049] In some embodiments of the present invention, the pretreatment of metal parts is phosphating pretreatment, and the process of phosphating pretreatment is: degreasing → surface adjustment → phosphating, the purpose of which is to provide protection for the metal substrate, to prevent the metal substrate from being corroded to a certain extent, and to improve the adhesion of the electrophoretic primer. Preferably, the phosphating temperature is controlled at 33-40°C. The pretreatment of non-metallic parts includes surface cleaning with organic solvents, for example, wiping the surface of the parts using, including but not limited to, 120# gasoline / 92# gasoline / isopropanol, the purpose of which is to remove stains on the surface of the non-metallic parts and prevent the stains from weakening the adhesion of the conductive primer.

[0050] In some embodiments of the present invention, the assembly is a complete assembly or a semi-assembly; when the assembly is a complete assembly, the conductive components are directly coated as a whole using an electrostatic rotary cup; when the assembly is a semi-assembly, the metal parts are conductively connected to each other, and then the conductive components are treated as a whole using an electrostatic rotary cup.

[0051] The main difference between full assembly and semi-assembly lies in the method of assembly. Full assembly refers to the complete assembly of non-metallic parts and metal parts through bolts and brackets to form a complete conductive component of the product. Semi-assembly refers to the temporary assembly of non-metallic parts and metal parts using some brackets to form a temporary conductive component for painting. Taking cab painting as an example, during full assembly, non-metallic exterior parts are in direct contact with the cab body, which will cause the blocked parts of the cab to be missed during spraying. The edges of the exterior parts will also be limited in position after full assembly, which increases the difficulty of spraying, resulting in missed spraying or poor spraying effect. During semi-assembly, some temporary brackets are installed on the cab through the previous process, and the non-metallic exterior parts are installed on this bracket. The spraying space is large and will not affect the spraying of the cab body and the edges of the exterior parts.

[0052] In some embodiments of the present invention, both the base paint and the varnish are flash-dried at room temperature after spraying. In order to improve the overall quality of the paint film, the present invention uses high-temperature baking to improve the quality of the paint film after spraying and flash-drying the varnish. The temperature of the high-temperature baking is 140±2°C. At this temperature, a good quality coating effect can be obtained in a short time. Preferably, the baking time at this temperature is 20 minutes. The composite paint film obtained by the present invention has a 20° gloss of ≧90, a distinctness of image ≧0.6, and an adhesion of ≦1 level. The composite paint film is a high-gloss paint film.

[0053] There is no need to limit the material of the non-metallic parts. The color difference between the non-metallic parts and the metal parts in the present invention depends on the surface resistance of the conductive primer. The coating quality depends on the process and is not related to the material of the non-metallic parts. In the embodiment of the present invention, the material of the non-metallic parts is glass fiber reinforced plastics. Those skilled in the art can perform co-linear coating on non-metallic parts and metal parts made of non-metallic materials such as plastic, glass fiber reinforced plastics, and ceramics according to product design.

[0054] vehicle:

[0055] The co-linear coating process of non-metallic and metallic conductive components of the present invention can be used for coating of commercial vehicle cabs after assembly and for overall coating of passenger vehicle frames.

[0056] The vehicle provided by the present invention has a portion equipped with non-metallic parts that is painted using the above-mentioned co-linear painting process for non-metallic and metal conductive components, and the color difference between the non-metallic parts and the metal parts is small.

[0057] Example:

[0058] The technical solution provided by the present invention is described in detail below in conjunction with embodiments.

[0059] Unless otherwise specified, the cathode electrophoretic paint used in the embodiments and comparative examples is HT-8000C cathode electrophoretic paint from PPG; the base paint is VS520W Chinese red metallic base paint from Wuhan Vio Environmental Protection Materials Co., Ltd.; the clear coat is VS760DF thick-coat clear coat from Wuhan Vio Environmental Protection Materials Co., Ltd.; the conductive primer is purchased from Wuhan Vio Environmental Protection Materials Co., Ltd. These conductive primers are from the same series of conductive primers, and the resistance values ​​are different only due to the different carbon nanotube content (0.8wt% to 1.1wt%).

[0060] Embodiment 1:

[0061] In order to verify the effect of using conductive primers with different resistance values ​​on the surface of non-metallic parts on the color difference between non-metallic parts and metal parts in the co-linear coating process, this embodiment determines the applicable range of the conductive primer resistance by testing the appearance quality (especially the control of color difference) of plastic test panels and metal test panels.

[0062] The non-metallic parts and metal parts co-linear coating process of this embodiment includes the following steps:

[0063] (1) Electrophoretic paint coating of metal test panels: The metal test panels are pretreated by a phosphating pretreatment method of degreasing-surface conditioning-phosphating, and the phosphating temperature is controlled at 35°C; the metal test panels are subjected to cathode electrophoresis by an immersion tank method, and the electrophoresis temperature is controlled at 30±2°C, and the electrophoresis voltage is controlled at 200V. After the electrophoresis is completed, the panels are baked, and the baking temperature is controlled at 175±2°C for 20 minutes to obtain an electrophoretic paint film; the thickness of the electrophoretic paint film is between 18 and 25 μm; the electrophoretic paint film is polished by sandpaper of 800 mesh or above, and then dust is removed by sticky gauze; and a metal intermediate is obtained.

[0064] (2) Applying conductive primer to plastic test panels: adjusting the viscosity of the conductive primer to 18-20s (measured by the 4-cup method) to obtain a conductive primer working liquid; spraying the conductive primer working liquid onto the surface of the plastic test panel using an air spray gun with a spray gun pressure of 5 atmospheres; baking after spraying at a temperature of 80±2°C for 30 minutes to obtain a conductive primer film; measuring the surface resistance of the conductive primer film; and obtaining a non-metallic intermediate component.

[0065] (3) Assembling conductive components:

[0066] Connection method a: Connect non-metallic intermediate pieces with the same resistance value Figure 1 Connect with the metal intermediate piece in the manner shown, and conduct 5 groups of tests, one group for each resistance value (10 4 Ω, 10 6 Ω, 10 9 Note: ∞ uses non-conductive primer, and no primer means the plastic test plate is directly connected to the metal intermediate piece.

[0067] Connection method b: Connect non-metallic intermediate pieces with different resistance values Figure 2 The method shown is connected with a metal intermediate piece.

[0068] Note: When connecting, the conductive primer film of the non-metallic intermediate component and the metal intermediate component substrate are connected through a wire to form a conductive component.

[0069] (4) Overall coating of conductive components: electrostatic rotary cup spraying of basecoat (two coats to form a film, with an interval of 115 seconds between the two coats) → leveling at room temperature for 5 minutes → electrostatic rotary cup spraying of clearcoat (two coats to form a film, with an interval of 115 seconds between the two coats) → leveling at room temperature for 5 minutes → drying at 80°C*30 minutes to obtain non-metallic finished products and metal finished products.

[0070] Table 1 Construction parameters of electrostatic rotary cup (Lang's rotary cup, model: WY-10) spraying

[0071]

[0072] Table 2 Color difference between non-metallic intermediate parts and metal intermediate parts with different resistance values

[0073]

[0074] Table 2 (continued)

[0075]

[0076]

[0077] Table 3 Color difference of conductive components connected by connection method a after overall coating

[0078]

[0079] Table 3 (continued)

[0080]

[0081] Table 4 Color difference of conductive components connected by connection method b after overall coating

[0082]

[0083] From Tables 2 to 4, it can be seen that the surface resistance of the conductive primer sprayed on non-metallic parts is 10 4 Ω~10 6 When the color difference between the finished metal parts and the finished non-metal parts is small.

[0084] Embodiment 2:

[0085] This embodiment provides a process for co-line coating of a cab and non-metallic exterior parts, comprising the following steps:

[0086] (1) The commercial vehicle cab body is pretreated by a phosphating pretreatment method of degreasing-surface conditioning-phosphating, and the phosphating temperature is controlled at 35°C.

[0087] (2) The cab body is subjected to cathode electrophoresis by a dipping tank method, the electrophoresis temperature is controlled at 30±2°C, the electrophoresis voltage is controlled at 200V, and after the electrophoresis is completed, it is baked, the baking temperature is controlled at 175±2°C, and the baking time is 20min to obtain an electrophoretic paint film; the thickness of the electrophoretic paint film is between 18-25 microns.

[0088] (3) Use sandpaper with a mesh size of 800 or above to polish the electrophoretic paint film, and then use sticky gauze to remove dust;

[0089] (4) Use 120# gasoline to wipe the fiberglass front cover clean.

[0090] (5) The viscosity of the conductive primer is adjusted to 18-20s (measured by the 4-cup coating method) to obtain a conductive primer working solution.

[0091] (6) Use an air spray gun to spray the conductive primer working liquid onto the front mask surface. The spray gun pressure is 5 atmospheres. After spraying, it is baked. The baking temperature is controlled at 80±2°C and the baking time is 30 minutes to obtain a conductive primer film. The surface resistance of the conductive primer film is measured to be 10 4 Ω.

[0092] (7) Use a temporary bracket to assemble the front cover to the cab body, with a distance of 15 cm between the front cover and the cab body. Use an electrical conductor to connect the conductive primer film of the front cover and the cab body to form a conductive assembly.

[0093] (8) Use an electrostatic rotary cup (Lans rotary cup, model: WY-10) to spray the entire conductive component with base paint. The voltage of the electrostatic rotary cup is controlled at 60KV, the speed is controlled at 35krpm, and after flashing at room temperature for 10 minutes, use an electrostatic rotary cup to spray the entire conductive component with varnish. After flashing at room temperature for 10 minutes, bake. The baking temperature is controlled at 140±2℃, and the baking time is controlled at 30 minutes. After baking, the color difference between the front mask and the cab is shown in Table 5:

[0094] Table 5 Color difference between the front mask and the cab after painting in Example 2

[0095] △E 15° 0.77 25° 0.46 45° 0.15 75° 0.35 110° 0.39

[0096] As shown in Table 5, by adopting the co-linear coating process, when the conductive primer resistance value is 10 4 Ω, the color difference between the front mask and the cab is significantly reduced, which greatly improves the appearance consistency.

[0097] Comparative Example 1

[0098] This comparative example provides a process for separately painting a cab and non-metallic exterior parts, comprising the following steps:

[0099] (1) The commercial vehicle cab body is pretreated by a phosphating pretreatment method of degreasing-surface conditioning-phosphating, and the phosphating temperature is controlled at 35°C;

[0100] (2) cathodic electrophoresis is performed on the cab body by immersion tank method, the electrophoresis temperature is controlled at 30±2°C, the electrophoresis voltage is controlled at 200V, and baking is performed after the electrophoresis is completed, the baking temperature is controlled at 175±2°C, and the baking time is 20min to obtain an electrophoretic paint film; the thickness of the electrophoretic paint film is between 18-25 microns;

[0101] (3) Use sandpaper with a mesh size of 800 or above to polish the electrophoretic paint film, and then use sticky gauze to remove dust;

[0102] (4) Use 120# gasoline to clean the front cover of the fiberglass reinforced plastic;

[0103] (5) Use an electrostatic rotary cup to spray the base paint on the cab. The voltage of the electrostatic rotary cup is controlled at 60KV and the speed is controlled at 35krpm. After flashing at room temperature for 10 minutes, use an electrostatic rotary cup to spray the entire conductive component with varnish. After flashing at room temperature for 10 minutes, bake it. The baking temperature is controlled at 140±2℃ and the baking time is controlled at 30 minutes:

[0104] (6) Use an air spray gun to spray the FRP special primer onto the front mask surface, the spray gun pressure is 5 atmospheres, after spraying, flash dry at room temperature for 10 minutes, the baking temperature is controlled at 80±2°C, and the baking time is 30 minutes. After baking, use an air spray gun to spray the base paint onto the front mask surface, the spray gun pressure is 5 atmospheres, after spraying, flash dry at room temperature for 10 minutes, use an air spray gun to spray the varnish onto the front mask surface, flash dry for 10 minutes, and bake, the baking temperature is controlled at 80±2°C, and the baking time is 30 minutes;

[0105] (7) After the cab and the front mask are sprayed and baked, the color difference between the front mask and the cab is shown in Table 6:

[0106] Table 6 Color difference between the front mask and the cab after painting in Example 1

[0107] △E 15° 3.25 25° 1.63 45° 1.34 75° 1.87 110° 2.13

[0108] As shown in Table 6, with the separate painting process, the color difference between the front mask and the cab is large, which has a great impact on the appearance consistency.

[0109] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features invented herein.

Claims

1. A co-linear coating process for non-metallic parts and metal parts, characterized in that: The steps include: Pre-treating the non-metallic parts, applying conductive primer, and baking them to obtain non-metallic intermediate parts; The metal parts are sequentially pre-treated, electrophoretic primer coated, and baked to obtain metal intermediate parts; Assembling a non-metallic intermediate part and a metallic intermediate part into a conductive assembly; Use an electrostatic rotary cup to spray the entire conductive component with base paint and varnish, and finally bake it at high temperature.

2. The co-linear coating process of non-metallic and metallic conductive components according to claim 1, characterized in that: The surface resistance of the conductive primer is <10 6 Ω.

3. The co-linear coating process of non-metallic and metallic conductive components according to claim 2, characterized in that: The surface resistance of the conductive primer is 10 4 Ω~10 6 Ω.

4. The co-linear coating process for non-metallic and metallic conductive components according to claim 1, characterized in that: The base color paint is a metallic base color paint.

5. The co-linear coating process of non-metallic and metallic conductive components according to claim 1, characterized in that: The metal part is a metal structural part of the vehicle; and / or the non-metallic part is a non-metallic exterior part of the vehicle; The metal structural parts include at least one of a vehicle body shell, an engine cover, a roof panel, a trunk lid, a fender, a front panel, a rear panel, a side panel, a floor, a door, a window, a spoiler, a trailer panel, a trailer floor, and a trailer roof panel; and / or, The non-metallic exterior trim includes at least one of a bumper, an air intake grille, a rearview mirror, a side skirt, a pillar decorative panel, a luggage rack, and a door handle.

6. The co-linear coating process for non-metallic and metallic conductive components according to claim 1, characterized in that: The coating thickness of the electrophoretic primer is 18 to 30 microns; and / or, The coating thickness of the conductive primer is 18 to 30 microns; and / or, The basecoat film thickness is 15 to 25 microns; and / or, The baking temperature of electrophoretic primer is 175±2℃; and / or, The baking temperature of the conductive primer is 80±2℃; and / or, The baking temperature of the base paint is 140±2℃.

7. The co-linear coating process for non-metallic and metallic conductive components according to claim 1, characterized in that: The pre-treatment of the metal parts is phosphating pre-treatment; and / or, Pretreatment of non-metallic parts includes surface cleaning with organic solvents.

8. The co-linear coating process for non-metallic and metallic conductive components according to claim 1, characterized in that: The assembly is complete assembly or semi-assembly.

9. The co-linear coating process for non-metallic and metallic conductive components according to claim 1, characterized in that: After spraying the basecoat and clearcoat, both are flash dried at room temperature; and / or, The temperature of high temperature baking is 140±2℃.

10. A vehicle, characterized in that: The coating is performed by the coating process described in any one of claims 1 to 9.

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