A paint mist pollution detection method for automobile painting

Abstract

The present application discloses a paint mist pollution detection method for automobile painting, which is used to simulate the on-site situation of automobile painting and accurately detect the paint mist pollution situation, so as to more accurately carry out product development and design and early prevention of paint mist pollution. The paint mist pollution detection method for automobile painting includes a first color paint coating step, a second color paint spraying step, and an evaluation step.

Description

Technical Field

[0001] The present application relates to the field of automobile painting, and in particular to a method for detecting paint mist pollution in automobile painting. Background Art

[0002] As an important part of automobile production, automobile painting has attracted more and more attention. The choice of automobile painting spraying method has an important impact on whether the car body is corroded during the subsequent use of the car, UV protection inside the car, and the appearance of the car. The original car paint painting process has been repeatedly discussed and studied in many literatures, but all of them are about the process of automobile outer panel painting. Few people mention or pay attention to the inner panel spraying in the automobile painting process.

[0003] However, not all of the car's inner panels are covered by interior trims, and some exposed locations also need protection and decoration. Inner panel spraying has always been an indispensable part of the car's original paint painting.

[0004] At the same time, in order to adapt to the needs of market competition and catch up with new trends, major automobile manufacturers are constantly working hard to improve the decorativeness of automobile exteriors, with automobile paint films showing high gloss, high vividness, multi-colorization, and high three-dimensional effect. The new demands on automobile exteriors have led to an increasingly obvious trend of upgrading automobile paint layers from traditional single-layer paints to double-layer paints with high vividness and three-dimensional effect.

[0005] However, during the construction of inner panel paint, on the one hand, due to the limitations of the process design of the automobile painting line, many color products do not spray the middle coating on the inner panel paint. Therefore, the inner panel paint is required to have the color appearance of the outer panel paint and provide hiding power to prevent the electrophoretic layer from being aged by light radiation. For example, a small amount of black slurry is added to the white inner panel paint to improve the hiding power of the inner panel paint; on the other hand, in order to simplify the construction process, the inner panel paint is usually designed as a single-layer paint to match the product designed as a double-layer paint for the outer panel paint. For example: the high-brightness red paint outer panel paint is: a double-layer paint of pink solid color paint and red pearlescent paint, and the matching inner panel paint is: a single-layer paint of red pearlescent and aluminum powder.

[0006] In the actual construction process, it is more common to spray the inner panel paint first, then the outer panel paint, and then apply the varnish after the inner and outer panel paint is completed. Therefore, when the outer panel paint is sprayed after the inner panel paint is sprayed, the paint mist will enter the inner panel of the car and pollute the inner panel paint. Due to the special requirements of the inner panel paint, the pigment-to-base ratio and formula structure of the coating formula may be adjusted accordingly. Therefore, the surface tension and color of the inner panel paint are different from those of the outer panel paint, so that the inner panel paint will be disturbed by the paint mist of the outer panel paint, and obvious color difference, gloss loss, particles, etc. will appear. In order to repair the contaminated inner panel paint, the inner panel paint will be sprayed after the outer panel paint is sprayed, which will cause the paint mist of the inner panel paint to pollute the outer panel paint.

[0007] Therefore, it is precisely because of the different performance requirements of the inner panel paint and the outer panel paint that there are differences in the formula design of the two. The surface tension and compatibility of the inner panel paint and the outer panel paint may be inconsistent. This difference will directly lead to paint mist pollution in the cross-spraying of the inner and outer panels during the actual construction process. The parts contaminated by the paint mist will have risks such as color difference, particles, wrinkles, and gloss loss.

[0008] Due to the design and painting requirements of the car, the interface area between the inner and outer panels is usually at the edge, and the steel plate is likely to be designed in an arc shape. The design of the measuring instrument generally has a fixed-size measurement window, and it is difficult to measure the edge of the car with the instrument. At the same time, the measurement window of the measuring instrument is generally designed in a flat plane. If the edge of the car is in an arc shape, this part cannot be measured with the instrument.

[0009] However, in the actual construction process, some coating lines for interior panel paint construction are manual spraying, while others are mechanical spraying. The same paint uses different construction methods on different coating lines, and the test methods and evaluation criteria are inconsistent. Without a unified and standard test method, it is difficult for coating developers to develop products that resist paint mist pollution and carry out early prevention. If the spraying trajectory is designed according to the arc shape of the car, the atomizer running trajectory is also designed to be an arc shape. Although the irregular trajectory of the atomizer is beneficial to automobile painting, it is not conducive to the evaluation of paint mist pollution by coating and coating developers. For many years, the evaluation of paint mist pollution has always relied on experienced coating technicians to make judgments based on visual conditions and personal experience. The results of manual evaluation are uncertain, and the visual evaluation results are not conducive to data recording, data archiving, and data analysis.

[0010] In view of this, it is necessary to develop a detection method for paint mist pollution, so as to accurately detect the paint mist pollution generated during the automobile painting process, so as to more accurately carry out product development and design and early prevention of paint mist pollution. Summary of the invention

[0011] According to one aspect of the present application, a paint mist pollution detection method for automobile painting is provided, which is used to simulate the on-site situation of automobile painting and detect the paint mist pollution situation; the paint mist pollution detection method for automobile painting includes a first color paint coating step, a second color paint spraying step, and an evaluation step; wherein, in the first color paint coating step, the first color paint is coated on a test piece under the middle and top coating process conditions to obtain a test piece coated with at least one layer of the first color paint; in the second color paint spraying step, the second color paint is sprayed on the test piece coated with at least one layer of the first color paint at least once by an electrostatic spraying device to form a paint mist contaminated area and a paint mist free area on the test piece coated with at least one layer of the first color paint; in the evaluation step, the detection data of the test piece coated with at least one layer of the first color paint in the paint mist contaminated area and the paint mist free area are obtained, and the change rate or change amount of the detection data in the paint mist contaminated area is calculated based on the detection data obtained in the paint mist free area.

[0012] In some embodiments, at least one edge of the test piece is a straight line.

[0013] In some embodiments, during the step of spraying the second color paint, the distance between the atomizer of the electrostatic spraying device and the test piece coated with at least one layer of the first color paint remains unchanged.

[0014] In some embodiments, in the step of spraying the second color paint, the running trajectory of the atomizer of the electrostatic spraying device is a straight line parallel to the test piece coated with at least one layer of the first color paint.

[0015] In some embodiments, in the step of spraying the second color paint, the running trajectory of the atomizer of the electrostatic spraying device is a straight line parallel to at least one straight edge of the test piece coated with at least one layer of the first color paint.

[0016] In some embodiments, in the step of spraying the second color paint, the horizontal distance between the motion trajectory of the atomizer of the electrostatic spraying device and at least one straight edge of the test piece coated with at least one layer of the first color paint is between 100 mm and 300 mm. Preferably, the horizontal distance between the motion trajectory of the atomizer of the electrostatic spraying device and at least one straight edge of the test piece coated with at least one layer of the first color paint is between 150 mm and 250 mm. Most preferably, the horizontal distance between the motion trajectory of the atomizer of the electrostatic spraying device and at least one straight edge of the test piece coated with at least one layer of the first color paint is 200 mm.

[0017] In some embodiments, the vertical distance between the motion trajectory of the atomizer of the electrostatic spraying device and at least one straight edge of the test piece coated with at least one layer of the first color paint is 200 mm to 240 mm. Preferably, the vertical distance between the motion trajectory of the atomizer of the electrostatic spraying device and at least one straight edge of the test piece coated with at least one layer of the first color paint is between 200 mm and 220 mm. Most preferably, the vertical distance between the motion trajectory of the atomizer of the electrostatic spraying device and at least one straight edge of the test piece coated with at least one layer of the first color paint is 220 mm.

[0018] In the paint mist pollution detection method for automobile painting, the horizontal distance and vertical distance between the motion trajectory of the atomizer of the electrostatic spraying device and the test piece are maintained within the above-mentioned value range. The main purpose is to control the spraying within this distance range, so that the test piece coated with at least one layer of the first color paint can be kept out of the direct spraying range of the atomizer. At the same time, the paint mist in the atomization edge area can contaminate the test piece coated with at least one layer of the first color paint through factors such as air flow, thereby better simulating the actual spraying situation and forming paint mist pollution.

[0019] If the horizontal distance between the motion trajectory of the atomizer of the electrostatic spray device and the test piece is too small, the test piece coated with at least one layer of the first color paint will be directly sprayed with the second color paint, and paint mist pollution detection cannot be performed; if the horizontal or vertical distance between the motion trajectory of the atomizer of the electrostatic spray device and the test piece is too large, the test piece coated with at least one layer of the first color paint cannot be contaminated by the second color paint, and paint mist pollution detection cannot be performed either.

[0020] In some embodiments, in the step of spraying the second color paint, the coating parameters of the electrostatic spraying device for spraying the second color paint on the test piece coated with at least one layer of the first color paint include gun distance, gun speed and voltage.

[0021] In some embodiments, the gun distance is 200-240 mm, the gun speed is 500-700 mm / s, and the voltage is 50-70 kV.

[0022] In some embodiments, the voltage is any value in the range of 50 to 70 kV, for example but not limited to 50 kV, 55 kV, 60 kV, 65 kV, and 70 kV.

[0023] In some embodiments, in the step of spraying the second color paint, the coating parameters of the electrostatic spraying device spraying the second color paint on the test piece coated with at least one layer of the first color paint further include a paint discharge amount, a spraying air pressure, and a rotary cup speed. The paint discharge amount, the spraying air pressure, and the rotary cup speed are consistent with the coating parameters at the coating site.

[0024] In some embodiments, in the step of applying the first color paint, the ambient temperature for applying the first color paint is 20-25°C, and the ambient humidity is 60%-80%; in the step of spraying the second color paint, the ambient temperature for spraying the second color paint is 20-25°C, and the ambient humidity is 60%-80%.

[0025] In some embodiments, in the evaluation step, the detection data includes at least one of a DOI value, an Lw value, a Sw value, a gloss value, and a color value.

[0026] In some embodiments, the gloss value is obtained using a gloss meter.

[0027] In some embodiments, the color value is obtained using a colorimeter.

[0028] In some embodiments, the DOI value, Lw value, and Sw value are obtained using an orange peel meter.

[0029] In some embodiments, the change rate or change amount of each detection data of the paint mist contaminated area is calculated by the following formula:

[0030] The change rate of DOI value = | DOI value of the area polluted by paint mist - DOI value of the area without paint mist pollution | ÷ DOI value of the area without paint mist pollution × 100%;

[0031] The change rate of Lw value = | Lw value of the area polluted by paint mist - Lw value of the area without paint mist pollution | ÷ Lw value of the area without paint mist pollution × 100%;

[0032] The rate of change of Sw value = |Sw value of the area polluted by paint mist - Sw value of the area without paint mist pollution | ÷ Sw value of the area without paint mist pollution × 100%;

[0033] The rate of change of gloss value = | gloss value of the area polluted by paint mist - gloss value of the area without paint mist pollution | ÷ gloss value of the area without paint mist pollution × 100%;

[0034] The change in color value = the color value of the area contaminated by paint mist - the color value of the area without paint mist contamination.

[0035] In the paint mist pollution detection method for automobile painting of the present application, by rationally selecting the laboratory coating device, optimizing the spraying trajectory and spraying conditions, the paint mist pollution in the actual construction is accurately simulated by the laboratory electrostatic coating device. At the same time, the present application also replaces the traditional visual judgment results by rationally selecting specific detection data. Therefore, using the paint mist pollution detection method for automobile painting described in the present application, the paint mist pollution in the actual construction can be accurately reproduced in the laboratory with the construction process and coating conditions as reference, and then the DOI value, Lw value, Sw value, gloss value and color value obtained by the colorimeter, orange peel meter and gloss meter and other automobile painting special instruments are used as the detection results to replace the traditional visual judgment, so that the test results are more accurate, more contrasting and convincing.

[0036] The paint mist pollution detection method for automobile painting described in this application standardizes and optimizes the paint mist pollution detection method, wherein standardizing the test process is conducive to data comparison of different products or solutions; optimizing the test method changes the test results from traditional visual to standardized data collection and analysis, making the test method accurate and applicable. The paint mist pollution detection method for automobile painting described in this application strengthens the monitoring and accurate measurement of on-site painting conditions by automobile painting technicians; it also helps automobile coating developers to effectively carry out early prevention and product planning for the occurrence of paint mist pollution on-site for related products. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the relative distance between the motion trajectory of the atomizer of the electrostatic spraying device and the test piece. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0039] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein may be applied to the present invention. The preferred implementation methods and materials described herein are for demonstration purposes only and are not intended to limit the content of this application.

[0040] Materials and equipment involved in the embodiments of this application:

[0041] 1. Electrophoresis plate test piece;

[0042] 2. Nippon Paint AR200 water-based mid-coat paint;

[0043] 3. Nippon Paint AR3000 water-based interior panel paint;

[0044] 4. Nippon Paint AR3000 water-based exterior panel paint;

[0045] 5. Nippon Paint OTO oily midcoat

[0046] 6. Nippon Paint SPM-95 oil-based interior panel paint

[0047] 7. Nippon Paint SPM-95 oil-based exterior panel paint

[0048] 8. CLEARCOAT PU 2K varnish from Nippon Paint;

[0049] 9. Kawasaki robot and Lanshi atomizer;

[0050] 10. Oven;

[0051] 11. Orange peel meter, gloss meter, colorimeter

[0052] The following first combines Figure 1 The relative position between the motion trajectory of the atomizer of the electrostatic spraying device and the test piece is described.

[0053] like Figure 1 As shown, the first test piece 2, the second test piece 3, and the third test piece 4 are located on the same straight line of the same plane. The movement trajectory of the atomizer 1 is a straight line as shown by the arrow, and the horizontal distance between the atomizer 1 and the first test piece 2, the second test piece 3, and the third test piece 4 is 100-300mm, and the vertical distance is 200-240mm. That is, only when the relative distance between the atomizer 1 and the first test piece 2, the second test piece 3, and the third test piece 4 is within the above range, the test piece will be sprayed.

[0054] During the spraying operation, the paint mist sprayed by the atomizer 1 will form a paint mist center area 5 and a paint mist edge area 6. By setting the specific relative distance between the atomizer and the test piece, it can be ensured that the test piece that has been coated with at least one layer of the first color paint is not within the direct spraying range of the atomizer, that is, the paint mist in the paint mist center area 5 will not be directly coated on the test piece that has been coated with at least one layer of the first color paint. The paint mist in the paint mist edge area 6 can be coated (polluted) on the test piece that has at least one layer of the first color paint through factors such as air flow, thereby forming a paint mist contamination area 7. In this way, the actual spraying situation can be better simulated.

[0055] Example 1 Detection method

[0056] The three electrophoretic flat plate test pieces were tested using the paint mist pollution detection method for automobile painting described in the present application to simulate the on-site conditions of automobile painting and detect the paint mist pollution conditions.

[0057] The paint mist pollution detection method for automobile painting comprises:

[0058] Step 1: Apply the first color paint

[0059] Applying the first color paint to the test piece under the mid-top coating process conditions to obtain a test piece coated with at least one layer of the first color paint;

[0060] The test pieces are three electrophoresis flat plate test pieces; the ambient temperature for applying the first color paint is 20-25°C, and the ambient humidity is 60%-80%;

[0061] Step 2: Spray the second color paint

[0062] Spraying the test piece coated with at least one layer of the first color paint with the second color paint at least once by an electrostatic spraying device, so as to form a paint mist contaminated area and a paint mist free area on the test piece coated with at least one layer of the first color paint; wherein the electrostatic spraying device is a Kawasaki robot and a Lansberg atomizer;

[0063] In this step, the moving trajectory of the Langshi atomizer is a straight line, and the distance between the Langshi atomizer and the test piece coated with at least one layer of the first color paint remains unchanged, the horizontal distance is maintained at 200 mm, and the vertical distance is maintained at 220 mm;

[0064] In this step, the electrostatic spraying device sprays the test piece coated with at least one layer of the first color paint with the second color paint. The coating parameters include gun distance, gun speed and voltage; the gun distance is 220mm, the gun speed is 650mm / s, and the voltage is 60kv; the coating parameters also include the paint discharge volume, spraying air pressure and rotary cup speed. The paint discharge volume, spraying air pressure and rotary cup speed are consistent with the coating parameters at the coating site;

[0065] In this step, the ambient temperature for spraying the second color paint is 20-25°C and the ambient humidity is 60%-80%;

[0066] Step 3 Evaluation Step

[0067] Obtaining detection data of the test piece coated with at least one layer of the first color paint in the paint mist contaminated area and the paint mist free area, and calculating the change rate of the detection data in the paint mist contaminated area based on the detection data in the paint mist free area; the detection data includes DOI value, Lw value, Sw value, gloss value and color value;

[0068] Specifically, in this step, the gloss value is obtained by a gloss meter, the gloss value is obtained by a colorimeter, and the DOI value, Lw value, and Sw value are obtained by an orange peel meter.

[0069] In the paint mist pollution detection method for automobile painting, the change rate or change amount of each detection data of the paint mist pollution area is calculated by the following formula:

[0070] The change rate of DOI value = | DOI value of the area polluted by paint mist - DOI value of the area without paint mist pollution | ÷ DOI value of the area without paint mist pollution × 100%:

[0071] The change rate of Lw value = | Lw value of the area polluted by paint mist - Lw value of the area without paint mist pollution | ÷ Lw value of the area without paint mist pollution × 100%:

[0072] The change rate of Sw value = | Sw value of the area polluted by paint mist - Sw value of the area without paint mist pollution | ÷ Sw value of the area without paint mist pollution × 100%:

[0073] The rate of change of gloss value = | gloss value of the area polluted by paint mist - gloss value of the area without paint mist pollution | ÷ gloss value of the area without paint mist pollution × 100%:

[0074] The change in color value = the color value of the area contaminated by paint mist - the color value of the area without paint mist contamination.

[0075] Example 2

[0076] In this embodiment, the paint mist pollution of the outer plate paint of AR3000 system water-based red topcoat (double-layer paint) and the paint mist pollution of the inner plate paint of AR3000 system water-based red topcoat (single-layer paint) are detected by the detection method described in Example 1. Specifically, in this embodiment, three electrophoresis flat plate test pieces with a size of 300mm×150mm×(0.8±0.1)mm are prepared and vertically attached to the magnetic plate configured in the robot spray room for detection. The detection step includes the following steps.

[0077] Step 1: Apply AR3000 system water-based red topcoat (single-layer paint) and inner panel paint

[0078] Using the middle and top coating process conditions, the three electrophoretic flat plate test pieces were sprayed with AR3000 system water-based red topcoat (single-layer paint) inner plate paint using a coating robot, and left to stand at room temperature for 1.5 minutes after spraying;

[0079] The ambient temperature for coating is 23±1℃ and the ambient humidity is 70±5%;

[0080] Step 2 Spray AR3000 system water-based red topcoat BC1 and AR3000 system water-based red topcoat BC2 exterior panel paint

[0081] Using an electrostatic spraying device, at a position 200 mm away from the three electrophoretic flat plate test pieces in the horizontal direction and at a position 220 mm away from the three electrophoretic flat plate test pieces in the vertical direction, the three electrophoretic flat plate test pieces painted in step 1 are sprayed with AR3000 system water-based red topcoat BC1 and AR3000 system water-based red topcoat BC2 outer plate color paint once each, so as to form paint mist contaminated areas and paint mist-free areas on the three electrophoretic flat plate test pieces.

[0082] The spraying environment temperature is 23±1℃, and the environment humidity is 70±5%.

[0083] In this step, the coating parameters of electrostatic spraying include gun distance, gun speed and voltage; the gun distance is 220mm, the gun speed is 650mm / s, and the voltage is 60kv; the remaining coating parameters are consistent with the coating parameters at the coating site, as shown in Table 1.

[0084] Table 1. Painting parameters at the painting site

[0085]

[0086] After spraying, level or flash dry according to the corresponding mid-top coating process requirements, then spray varnish and bake;

[0087] Step 3 Evaluation Step

[0088] The gloss meter was used to obtain the gloss values ​​of the three electrophoresis flat plate test pieces obtained in step 2 in the paint mist contaminated area and the paint mist free area, and the orange peel meter was used to obtain the DOI value, Lw value and Sw value of the three electrophoresis flat plate test pieces obtained in step 2 in the paint mist contaminated area and the paint mist free area, and the change rates of the gloss value, DOI value, Lw value and Sw value were calculated by the following formulas, respectively, to obtain the test data shown in Table 2:

[0089] The change rate of DOI value = | DOI value of the area polluted by paint mist - DOI value of the area without paint mist pollution | ÷ DOI value of the area without paint mist pollution × 100%:

[0090] The change rate of Lw value = | Lw value of the area polluted by paint mist - Lw value of the area without paint mist pollution | ÷ Lw value of the area without paint mist pollution × 100%:

[0091] The rate of change of Sw value = |Sw value of the area polluted by paint mist - Sw value of the area without paint mist pollution | ÷ Sw value of the area without paint mist pollution × 100%:

[0092] The rate of change of gloss value = | gloss value of the area polluted by paint mist - gloss value of the area without paint mist pollution | ÷ gloss value of the area without paint mist pollution × 100%:

[0093] Table 2. Gloss value, DOI value, Lw value and Sw value and change rate

[0094] Test items Uncontaminated area Contaminated area Rate of change (%) Change rate requirements DOI value 93 88 5.37 <10％ Lw value 8.5 10.3 21.17 <30％ Sw value 22.5 25.6 13.78 <20％ Gloss value 95 91 4.21 <10％

[0095] In addition, the color values ​​of the three electrophoresis plate test pieces obtained in step 2 above in the paint mist contaminated area and the paint mist free area were obtained by using a colorimeter, and the change in the color value was calculated by the following formula to obtain the test data shown in Table 3:

[0096] The change of color value = the color value of the area polluted by paint mist - the color value of the area without paint mist pollution

[0097] Table 3. Color values ​​and changes

[0098]

[0099] It can be seen from Tables 2 and 3 that the AR3000 system water-based red topcoat (double-layer paint) outer plate paint is matched with the AR3000 system water-based red topcoat (single-layer paint) inner plate paint, and the situation of the outer plate paint contaminating the inner plate paint is as follows: the appearance data change rate of the contaminated area reaches the required range, the color difference value is small, and there is no obvious color difference visually, which can meet the on-site use requirements.

[0100] Example 3

[0101] In this embodiment, the paint mist pollution of the inner plate paint of the AR3000 system water-based red topcoat (single-layer paint) and the paint mist pollution of the outer plate paint of the AR3000 system water-based red topcoat (double-layer paint) are detected by the detection method described in Example 1. Specifically, in this embodiment, three electrophoresis flat plate test pieces with a size of 300mm×150mm×(0.8±0.1)mm are prepared and vertically attached to the magnetic plate configured in the robot spray room for detection. The detection step includes the following steps.

[0102] Step 1: Apply R3000 system water-based red topcoat BC1 and AR3000 system water-based red topcoat BC2 exterior panel paint

[0103] Under the conditions of the mid-top coating process, the three electrophoretic flat plate test pieces were sprayed with R3000 system water-based red topcoat BC1 and AR3000 system water-based red topcoat BC2 once each using a coating robot, and allowed to stand at room temperature for 1.5 minutes after spraying;

[0104] The ambient temperature for coating is 23±1℃ and the ambient humidity is 70±5%;

[0105] Step 2: Spray AR3000 system water-based red topcoat (single-layer paint) on the inner panel

[0106] Using an electrostatic spraying device, the three electrophoretic flat plate test pieces coated in step 1 are sprayed with AR3000 system water-based red topcoat (single-layer color paint) inner plate color paint twice back and forth at a position 200 mm away from the three electrophoretic flat plate test pieces in the horizontal direction and 220 mm away from the three electrophoretic flat plate test pieces in the vertical direction, so as to form paint mist contaminated areas and paint mist-free areas on the three electrophoretic flat plate test pieces.

[0107] The spraying environment temperature is 23±1℃, and the environment humidity is 70±5%.

[0108] In this step, the coating parameters of electrostatic spraying include gun distance, gun speed and voltage; the gun distance is 220mm, the gun speed is 650mm / s, and the voltage is 60kv; the remaining coating parameters are consistent with the coating parameters at the coating site, as shown in Table 1.

[0109] After spraying, level or flash dry according to the corresponding mid-top coating process requirements, then spray varnish and bake;

[0110] Step 3 Evaluation Step

[0111] The gloss meter was used to obtain the gloss values ​​of the three electrophoresis flat plate test pieces obtained in step 2 in the paint mist contaminated area and the paint mist free area, and the orange peel meter was used to obtain the DOI value, Lw value and Sw value of the three electrophoresis flat plate test pieces obtained in step 2 in the paint mist contaminated area and the paint mist free area, respectively. The change rates of the gloss value, DOI value, Lw value and Sw value were calculated by the following formulas, respectively, to obtain the test data shown in Table 4:

[0112] The change rate of DOI value = | DOI value of the area polluted by paint mist - DOI value of the area without paint mist pollution | ÷ DOI value of the area without paint mist pollution × 100%:

[0113] The change rate of Lw value = | Lw value of the area polluted by paint mist - Lw value of the area without paint mist pollution | ÷ Lw value of the area without paint mist pollution × 100%:

[0114] The rate of change of Sw value = |Sw value of the area polluted by paint mist - Sw value of the area without paint mist pollution | ÷ Sw value of the area without paint mist pollution × 100%:

[0115] The rate of change of gloss value = | gloss value of the area polluted by paint mist - gloss value of the area without paint mist pollution | ÷ gloss value of the area without paint mist pollution × 100%:

[0116] Table 4. Gloss value, DOI value, Lw value and Sw value and change rate

[0117] Test items Uncontaminated area Contaminated area Rate of change (%) Change rate requirements DOI value 92.9 87.6 5.7 <10％ Lw value 8.9 11.2 25.84 <30％ Sw value 23.8 27.9 17.22 <20％ Gloss value 94.8 89.2 5.91 <10％

[0118] In addition, the color values ​​of the three electrophoresis plate test pieces obtained in step 2 above in the paint mist contaminated area and the paint mist free area were obtained by using a colorimeter, and the change in the color value was calculated by the following formula to obtain the test data shown in Table 5:

[0119] The change of color value = the color value of the area polluted by paint mist - the color value of the area without paint mist pollution

[0120] Table 5. Color values ​​and changes

[0121]

[0122] It can be seen from Tables 4 and 5 that the AR3000 system water-based red topcoat (double-layer paint) outer plate paint is matched with the AR3000 system water-based red topcoat (single-layer paint) inner plate paint, and the inner plate paint contaminates the outer plate paint in the following situation: the appearance data change rate of the contaminated area reaches the required range, the color difference value is small, and there is no obvious color difference visually, which can meet the on-site use requirements.

[0123] By comparing the data change rate of Table 4 with Table 2, it can be seen that the impact of AR3000 system inner plate paint contaminating AR3000 system outer plate paint is greater than that of AR3000 system outer plate paint contaminating AR3000 system inner plate paint. By comparing the data of Table 5 with Table 3, it can be seen that the outer plate paint contaminating the inner plate paint will increase the color L value, a value, and b value of the inner plate paint; the inner plate paint contaminating the outer plate paint will reduce the color L value, a value, and b value of the outer plate paint.

[0124] Example 4

[0125] In this embodiment, the paint mist pollution of the outer plate paint of AR3000 system water-based white topcoat (double-layer paint) and the paint mist pollution of the inner plate paint of AR3000 system water-based white topcoat (single-layer paint) are detected by the detection method described in Example 1. Specifically, in this embodiment, three electrophoresis flat plate test pieces with a size of 300mm×150mm×(0.8±0.1)mm are prepared and vertically attached to the magnetic plate configured in the robot spray room for detection. The detection step includes the following steps.

[0126] Step 1: Apply AR3000 system water-based white topcoat (single-layer paint) and inner panel paint

[0127] Using the middle and top coating process conditions, the three electrophoretic flat plate test pieces were sprayed with AR3000 system water-based white topcoat (single-layer paint) inner plate paint once using a coating robot, and allowed to stand at room temperature for 1.5 minutes after spraying;

[0128] The ambient temperature for coating is 23±1℃ and the ambient humidity is 70±5%;

[0129] Step 2 AR3000 system water-based white topcoat BC1, AR3000 system water-based white topcoat BC2 exterior panel paint

[0130] Using an electrostatic spraying device, at a position 200 mm away from the three electrophoretic flat plate test pieces in the horizontal direction and at a position 220 mm away from the three electrophoretic flat plate test pieces in the vertical direction, the three electrophoretic flat plate test pieces coated in step 1 are sprayed with AR3000 system water-based white topcoat BC1 and AR3000 system water-based white topcoat BC2 once each, so as to form paint mist contaminated areas and paint mist-free areas on the three electrophoretic flat plate test pieces.

[0131] The spraying environment temperature is 23±1℃, and the environment humidity is 70±5%.

[0132] In this step, the electrostatic spraying painting parameters include gun distance, gun speed and voltage; the gun distance is 220mm, the gun speed is 650mm / s, and the voltage is 60kv; the remaining painting parameters are consistent with the painting parameters at the painting site, as shown in Table 6.

[0133] Table 6. Painting parameters at the painting site

[0134]

[0135] After spraying, level or flash dry according to the corresponding mid-top coating process requirements, then spray varnish and bake;

[0136] Step 3 Evaluation Step

[0137] The gloss meter was used to obtain the gloss values ​​of the three electrophoresis flat plate test pieces obtained in step 2 in the paint mist contaminated area and the paint mist free area, and the orange peel meter was used to obtain the DOI value, Lw value and Sw value of the three electrophoresis flat plate test pieces obtained in step 2 in the paint mist contaminated area and the paint mist free area, respectively. The change rates of the gloss value, DOI value, Lw value and Sw value were calculated by the following formulas, respectively, to obtain the test data shown in Table 7:

[0138] The change rate of DOI value = | DOI value of the area polluted by paint mist - DOI value of the area without paint mist pollution | ÷ DOI value of the area without paint mist pollution × 100%:

[0139] The change rate of Lw value = | Lw value of the area polluted by paint mist - Lw value of the area without paint mist pollution | ÷ Lw value of the area without paint mist pollution × 100%:

[0140] The change rate of Sw value = | Sw value of the area polluted by paint mist - Sw value of the area without paint mist pollution | ÷ Sw value of the area without paint mist pollution × 100%:

[0141] The rate of change of gloss value = | gloss value of the area polluted by paint mist - gloss value of the area without paint mist pollution | ÷ gloss value of the area without paint mist pollution × 100%:

[0142] Table 7. Gloss value, DOI value, Lw value and Sw value and change rate

[0143] Test items Uncontaminated area Contaminated area Rate of change (%) Change rate requirements DOI value 92.6 87.8 5.18 <10％ Lw value 8.7 10.9 25.28 <30％ Sw value 22.8 26.6 16.67 <20％ Gloss value 95.3 90.2 5.35 <10％

[0144] In addition, the color values ​​of the three electrophoresis plate test pieces obtained in step 2 above in the paint mist contaminated area and the paint mist free area were obtained by using a colorimeter, and the change in the color value was calculated by the following formula to obtain the test data shown in Table 8:

[0145] The change of color value = the color value of the area polluted by paint mist - the color value of the area without paint mist pollution

[0146] Table 8. Color values ​​and changes

[0147]

[0148]

[0149] It can be seen from Tables 7 and 8 that the AR3000 system water-based white topcoat (double-layer paint) outer plate paint is matched with the AR3000 system water-based white topcoat (single-layer paint) inner plate paint, and the outer plate paint contaminates the inner plate paint in the following cases: the appearance data change rate reaches the required range, the color difference value is small, and there is no obvious color difference visually, which can meet the on-site use requirements.

[0150] Example 5

[0151] In this embodiment, the paint mist pollution of the outer plate paint of the SPM-95 system oily white topcoat (double-layer paint) and the paint mist pollution of the inner plate paint of the SPM-95 system oily white topcoat (single-layer paint) are detected by the detection method described in Example 1. Specifically, in this embodiment, three electrophoresis flat plate test pieces with a size of 300mm×150mm×(0.8±0.1)mm are prepared and vertically attached to the magnetic plate configured in the robot spray room for detection. The detection step includes the following steps.

[0152] Step 1: Apply SPM-95 system oily white topcoat (single-layer paint) and inner panel paint

[0153] Under the process conditions of the middle and top coating, the three electrophoretic flat plate test pieces were sprayed with SPM-95 system oily white topcoat (single-layer paint) inner plate paint once using a coating robot, and after spraying, they were allowed to stand at room temperature for 1.5 minutes;

[0154] The ambient temperature for coating is 23±1℃ and the ambient humidity is 70±5%;

[0155] Step 2 SPM-95 system oily white topcoat BC1, SPM-95 system oily white topcoat BC2 plate color paint

[0156] Using an electrostatic spraying device, spray the three electrophoretic flat plate test pieces coated in step 1 with SPM-95 system oily white topcoat BC1 and SPM-95 system oily white topcoat BC2 once at a position 200 mm away from the three electrophoretic flat plate test pieces in the horizontal direction and 220 mm away from the three electrophoretic flat plate test pieces in the vertical direction, so as to form paint mist contaminated areas and paint mist-free areas on the three electrophoretic flat plate test pieces.

[0157] The spraying environment temperature is 23±1℃, and the environment humidity is 70±5%.

[0158] In this step, the electrostatic spraying painting parameters include gun distance, gun speed and voltage; the gun distance is 220mm, the gun speed is 650mm / s, and the voltage is 60kv; the remaining painting parameters are consistent with the painting parameters at the painting site, as shown in Table 9.

[0159] Table 9. Painting parameters at the painting site

[0160]

[0161]

[0162] After spraying, level or flash dry according to the corresponding mid-top coating process requirements, then spray varnish and bake;

[0163] Step 3 Evaluation Step

[0164] The gloss meter was used to obtain the gloss values ​​of the three electrophoresis flat plate test pieces obtained in step 2 in the paint mist contaminated area and the paint mist free area, and the orange peel meter was used to obtain the DOI value, Lw value and Sw value of the three electrophoresis flat plate test pieces obtained in step 2 in the paint mist contaminated area and the paint mist free area, respectively. The change rates of the gloss value, DOI value, Lw value and Sw value were calculated by the following formulas, respectively, to obtain the test data shown in Table 10:

[0165] The change rate of DOI value = | DOI value of the area polluted by paint mist - DOI value of the area without paint mist pollution | ÷ DOI value of the area without paint mist pollution × 100%:

[0166] The change rate of Lw value = | Lw value of the area polluted by paint mist - Lw value of the area without paint mist pollution | ÷ Lw value of the area without paint mist pollution × 100%:

[0167] The rate of change of Sw value = |Sw value of the area polluted by paint mist - Sw value of the area without paint mist pollution | ÷ Sw value of the area without paint mist pollution × 100%:

[0168] The rate of change of gloss value = | gloss value of the area polluted by paint mist - gloss value of the area without paint mist pollution | ÷ gloss value of the area without paint mist pollution × 100%:

[0169] Table 10. Gloss value, DOI value, Lw value and Sw value and change rate

[0170] Test items Uncontaminated area Contaminated area Rate of change (%) Change rate requirements DOI value 93.2 89.3 4.18 <10％ Lw value 8.2 9.9 20.73 <30％ Sw value 19.8 22.5 13.64 <20％ Gloss value 95.6 92.1 3.66 <10％

[0171] In addition, the color values ​​of the three electrophoresis plate test pieces obtained in step 2 above in the paint mist contaminated area and the paint mist free area were obtained by using a colorimeter, and the change in the color value was calculated by the following formula to obtain the test data shown in Table 11:

[0172] The change of color value = the color value of the area polluted by paint mist - the color value of the area without paint mist pollution

[0173] Table 11. Color values ​​and changes

[0174]

[0175] It can be seen from Tables 10 and 11 that the SPM-95 system oily white topcoat (double-layer paint) outer plate paint is matched with the SPM-95 system oily white topcoat (single-layer paint) inner plate paint, and the outer plate paint contaminates the inner plate paint in the following cases: the appearance data change rate reaches the required range, the color difference value is small, and there is no obvious color difference visually, which can meet the on-site use requirements.

[0176] By comparing the appearance data change rate between Table 10 and Table 7, the paint mist pollution data of the SPM-95 oily system is relatively small compared with the AR3000 water-based system; by comparing the color difference data between Table 11 and Table 8, the paint mist pollution data of the SPM-95 oily system is relatively small compared with the AR3000 water-based system.

[0177] Example 6

[0178] In this embodiment, AR3000 system water-based red topcoat (double-layer paint) outer plate paint 1# and AR3000 system water-based red topcoat (double-layer paint) outer plate paint 2# are respectively contaminated with paint mist pollution of AR3000 system water-based red topcoat (single-layer paint) inner plate paint, and paint mist pollution detection is performed using the detection method described in Example 1. Specifically, in this embodiment, 3 electrophoresis flat plate test pieces with a size of 300mm×150mm×(0.8±0.1)mm are prepared and vertically attached to the magnetic plate configured in the robot spray room for detection. The detection step includes the following steps.

[0179] Step 1: Apply AR3000 system water-based red topcoat (single-layer paint) and inner panel paint

[0180] Under the conditions of the mid-top coating process, the six electrophoretic flat plate test pieces were sprayed with R3000 system water-based red topcoat BC1 and AR3000 system water-based red topcoat BC2 once each using a coating robot, and allowed to stand at room temperature for 1.5 minutes after spraying;

[0181] The ambient temperature for coating is 23±1℃ and the ambient humidity is 70±5%;

[0182] Step 2.1 Spray AR3000 system water-based red topcoat exterior panel paint 1# scheme exterior panel paint

[0183] Using an electrostatic spraying device, at a position 200 mm away from three of the six electrophoretic flat plate test pieces in the horizontal direction and at a position 220 mm away from the three electrophoretic flat plate test pieces in the vertical direction, the three electrophoretic flat plate test pieces coated in step 1 are sprayed with AR3000 system water-based red topcoat exterior plate color paint 1# solution to form paint mist contaminated areas and paint mist-free areas on the three electrophoretic flat plate test pieces.

[0184] The spraying environment temperature is 23±1℃, and the environment humidity is 70±5%.

[0185] In this step, the coating parameters of electrostatic spraying include gun distance, gun speed and voltage; the gun distance is 220mm, the gun speed is 650mm / s, and the voltage is 60kv; the remaining coating parameters are consistent with the coating parameters at the coating site, as shown in Table 1.

[0186] After spraying, level or flash dry according to the corresponding mid-top coating process requirements, then spray varnish and bake;

[0187] Step 2.2 Spray AR3000 system water-based red topcoat exterior panel paint 2# scheme exterior panel paint

[0188] Using an electrostatic spraying device, at a position 200 mm away from the other three of the six electrophoretic flat plate test pieces in the horizontal direction and at a position 220 mm away from the three electrophoretic flat plate test pieces in the vertical direction, the three electrophoretic flat plate test pieces coated in step 1 are sprayed with AR3000 system water-based red topcoat exterior panel color paint 2# solution, so as to form paint mist contaminated areas and paint mist-free areas on the three electrophoretic flat plate test pieces.

[0189] The spraying environment temperature is 23±1℃, and the environment humidity is 70±5%.

[0190] In this step, the coating parameters of electrostatic spraying include gun distance, gun speed and voltage; the gun distance is 220mm, the gun speed is 650mm / s, and the voltage is 60kv; the remaining coating parameters are consistent with the coating parameters at the coating site, as shown in Table 1.

[0191] After spraying, level or flash dry according to the corresponding mid-top coating process requirements, then spray varnish and bake;

[0192] Step 3 Evaluation Step

[0193] The gloss meter was used to obtain the gloss values ​​of the electrophoresis flat plate test pieces obtained in the above steps 2.1 and 2.2 in the paint mist contaminated area and the paint mist free area, respectively. The orange peel meter was used to obtain the DOI value, Lw value and Sw value of the electrophoresis flat plate test pieces obtained in the above steps 2.1 and 2.2 in the paint mist contaminated area and the paint mist free area, respectively. The change rates of the gloss value, DOI value, Lw value and Sw value were calculated by the following formulas, respectively, to obtain the test data shown in Table 12:

[0194] The change rate of DOI value = | DOI value of the area polluted by paint mist - DOI value of the area without paint mist pollution | ÷ DOI value of the area without paint mist pollution × 100%:

[0195] The change rate of Lw value = | Lw value of the area polluted by paint mist - Lw value of the area without paint mist pollution | ÷ Lw value of the area without paint mist pollution × 100%:

[0196] The change rate of Sw value = | Sw value of the area polluted by paint mist - Sw value of the area without paint mist pollution | ÷ Sw value of the area without paint mist pollution × 100%:

[0197] The rate of change of gloss value = | gloss value of the area polluted by paint mist - gloss value of the area without paint mist pollution | ÷ gloss value of the area without paint mist pollution × 100%:

[0198] Table 12. Gloss value, DOI value, Lw value and Sw value and change rate

[0199]

[0200]

[0201] In addition, the color values ​​of the electrophoresis plate test piece obtained in the above steps 2.1 and 2.2 in the paint mist contaminated area and the paint mist free area were obtained by using a colorimeter, and the change in the color value was calculated by the following formula to obtain the test data shown in Table 13:

[0202] The change of color value = the color value of the area polluted by paint mist - the color value of the area without paint mist pollution

[0203] Table 13. Color values ​​and changes

[0204]

[0205] It can be seen from Table 12 and Table 13 that AR3000 system water-based red topcoat exterior panel paint 1# scheme has better anti-paint mist pollution performance than 2# scheme matching AR3000 system water-based red topcoat interior panel paint. AR3000 system water-based red topcoat exterior panel paint 1# scheme meets the requirements for all indicators and is qualified in the test; AR3000 system water-based red topcoat exterior panel paint 2# scheme has a DOI value, Lw value, and Sw value change rate greater than the required value, the visual color difference is not obvious, but the test color difference value is too large, and 2# scheme cannot be used.

[0206] Comparative Example 1

[0207] In this comparative example, all steps are the same as those in Example 2, and the only difference between the two is that in this comparative example 1, step 2 is constructed by a manual spray gun instead of an electrostatic spray device as described in Example 2.

[0208] Comparative Example 2

[0209] In this comparative example, all steps are the same as those in Example 2, and the difference between the two is that in this comparative example 2, an electrostatic spraying device is not used in step 2, but a general spraying device is used.

[0210] By the same evaluation steps as step 3 of Example 2, the test data of Comparative Implementation 1 and Comparative Example 2 were obtained, as shown in Table 14 and Table 15, respectively.

[0211] Table 14. Gloss value, DOI value, Lw value and Sw value and change rate

[0212]

[0213] Table 15. Color values ​​and changes

[0214]

[0215]

[0216] It can be seen from the data in Tables 14 and 15 that Comparative Example 1 does not use an electrostatic spray device but adopts manual spraying. Due to the poor atomization of the manual spray gun, the construction conditions cannot correspond to the actual construction conditions on site. The appearance change rate and color difference value of the paint mist pollution experiment are large. The test results are inconsistent with the actual situation on site and cannot achieve the effect of preparing to test the paint mist pollution.

[0217] In the construction process of Comparative Example 2, the high-voltage electrostatic spraying device is not used, the paint mist is too dispersed, and exists in the spraying environment for a long time, and the test piece coated with the first color paint is repeatedly contaminated. Therefore, the construction conditions cannot be consistent with the on-site painting conditions, the appearance change rate and color difference value of the paint mist pollution experiment are large, the test results are inconsistent with the actual situation on site, and the effect of preparing to test the paint mist pollution cannot be achieved.

[0218] Comparative Example 3

[0219] In this comparative example, all steps are the same as those in Example 2, and the only difference between the two is that in this comparative example 3, the electrostatic spraying device (atomizer) in step 2 is only 50 mm away from the three electrophoretic flat plate test pieces in the horizontal direction, instead of the electrostatic spraying device (atomizer) described in Example 2 being 200 mm away from the three electrophoretic flat plate test pieces in the horizontal direction.

[0220] Comparative Example 4

[0221] In this comparative example, all steps are the same as those in Example 2, and the only difference between the two is that in this comparative example 4, the electrostatic spraying device (atomizer) in step 2 is located 400 mm away from the three electrophoretic flat plate test pieces in the horizontal direction, instead of the electrostatic spraying device (atomizer) as described in Example 2 being located 200 mm away from the three electrophoretic flat plate test pieces in the horizontal direction.

[0222] By the same evaluation steps as step 3 of Example 2, the test data of Comparative Implementation 3 and Comparative Example 4 were obtained, as shown in Table 16 and Table 17, respectively.

[0223] Table 16. Gloss value, DOI value, Lw value and Sw value and change rate

[0224]

[0225] Table 17. Color values ​​and changes

[0226]

[0227]

[0228] It can be seen from the data in Tables 16 and 17 that the electrostatic spraying device (atomizer) in step 2 of comparative example 3 is only 50 mm away from the three electrophoretic flat plate test pieces in the horizontal direction, rather than the electrostatic spraying device (atomizer) recorded in Example 2, which is 200 mm away from the three electrophoretic flat plate test pieces in the horizontal direction. Therefore, in step 2, the color paint is directly sprayed on the test piece coated with the inner plate color paint. From the data analysis alone, the appearance value changes little, and the color difference is more obvious than that in Example 2. However, in comparative example 4, the color paint in step 2 is directly sprayed on the test piece coated with the inner plate color paint, and the paint mist of the outer plate color paint does not pollute the inner plate color paint. The test data does not match the situation that the outer plate color paint mist pollutes the inner plate color paint in actual construction, and the data cannot be used as the detection data for testing paint mist pollution.

[0229] It can be seen from the data in Tables 16 and 17 that the electrostatic spraying device (atomizer) in step 2 of comparative example 4 is 400 mm away from the three electrophoretic flat plate test pieces in the horizontal direction, rather than the electrostatic spraying device (atomizer) recorded in Example 2, which is 200 mm away from the three electrophoretic flat plate test pieces in the horizontal direction. Therefore, the edge paint mist of the color paint in step 2 cannot effectively contaminate the test piece sprayed with the inner plate color paint. From the data analysis alone, the appearance change rate and color difference data are both good. However, in comparative example 4, the edge paint mist of the color paint in step 2 cannot effectively contaminate the test piece sprayed with the inner plate color paint. The test data is inconsistent with the situation that the outer plate color paint mist contaminates the inner plate color paint in actual construction, and the data cannot be used as the detection data for testing paint mist pollution.

[0230] As described above, in the paint mist pollution detection method for automobile painting of the present application, by rationally selecting the laboratory coating device, optimizing the spraying trajectory and spraying conditions, the paint mist pollution in the actual construction is accurately simulated by the laboratory electrostatic coating device. At the same time, the present application also replaces the traditional visual judgment result by rationally selecting specific detection data. Therefore, using the paint mist pollution detection method for automobile painting described in the present application, the paint mist pollution in the actual construction can be accurately reproduced in the laboratory with the construction process and coating conditions as a reference, and then the DOI value, Lw value, Sw value, gloss value and color value obtained by the colorimeter, orange peel meter and gloss meter and other automobile painting special instruments are used as the detection results to replace the traditional visual judgment, so that the test results are more accurate, more contrasting and convincing.

[0231] The above is a detailed introduction to a paint mist pollution detection method for automobile painting provided by the embodiment of the present application. This article uses specific examples to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiment of the present application.

Claims

1. A method for detecting paint mist pollution of automobile painting, which is used to simulate the on-site situation of automobile painting and detect the paint mist pollution, characterized in that: The paint mist pollution detection method for automobile painting comprises a first color paint coating step, a second color paint spraying step, and an evaluation step; wherein, In the step of applying the first color paint, the test piece is coated with the first color paint under the middle and top coating process conditions to obtain a test piece coated with at least one layer of the first color paint; In the step of spraying the second color paint, the second color paint is sprayed at least once on the test piece coated with at least one layer of the first color paint by an electrostatic spraying device, so as to form a paint mist contaminated area and a paint mist free area on the test piece coated with at least one layer of the first color paint; In the evaluation step, the detection data of the test piece coated with at least one layer of the first color paint in the paint mist contaminated area and the paint mist free area are obtained, and the change amount or change rate of the detection data in the paint mist contaminated area is calculated based on the obtained detection data in the paint mist free area; Among them, in the step of spraying the second color paint, the horizontal distance between the movement trajectory of the atomizer of the electrostatic spraying device and at least one straight line edge of the test piece coated with at least one layer of the first color paint is 100mm~300mm, and the vertical distance between the movement trajectory of the atomizer of the electrostatic spraying device and at least one straight line edge of the test piece coated with at least one layer of the first color paint is 200mm~240mm.

2. The paint mist pollution detection method for automobile painting according to claim 1, characterized in that: At least one edge of the test piece is a straight line.

3. The paint mist pollution detection method for automobile painting according to claim 1, characterized in that: In the step of spraying the second color paint, the distance between the atomizer of the electrostatic spraying device and the test piece coated with at least one layer of the first color paint remains unchanged.

4. The paint mist pollution detection method for automobile painting as claimed in claim 1, characterized in that: In the step of spraying the second color paint, the running track of the atomizer of the electrostatic spraying device is a straight line parallel to the test piece coated with at least one layer of the first color paint.

5. The paint mist pollution detection method for automobile painting as claimed in claim 3, characterized in that: In the step of spraying the second color paint, the movement trajectory of the atomizer of the electrostatic spraying device always maintains the same vertical distance and horizontal distance from the test piece coated with at least one layer of the first color paint.

6. The paint mist pollution detection method for automobile painting as claimed in claim 4, characterized in that: In the step of spraying the second color paint, the horizontal distance between the motion trajectory of the atomizer of the electrostatic spraying device and at least one straight line edge of the test piece coated with at least one layer of the first color paint is 150 mm to 250 mm.

7. The paint mist pollution detection method for automobile painting as claimed in claim 6, characterized in that: In the step of spraying the second color paint, the horizontal distance between the motion trajectory of the atomizer of the electrostatic spraying device and at least one straight line edge of the test piece coated with at least one layer of the first color paint is 200 mm.

8. The paint mist pollution detection method for automobile painting as claimed in claim 6, characterized in that: In the step of spraying the second color paint, the vertical distance between the motion trajectory of the atomizer of the electrostatic spraying device and at least one straight line edge of the test piece coated with at least one layer of the first color paint is 200-220 mm.

9. The paint mist pollution detection method for automobile painting as claimed in claim 8, characterized in that: In the step of spraying the second color paint, the vertical distance between the motion trajectory of the atomizer of the electrostatic spraying device and at least one straight line edge of the test piece coated with at least one layer of the first color paint is 220 mm.

10. The paint mist pollution detection method for automobile painting according to claim 1, characterized in that: In the step of spraying the second color paint, the coating parameters of the electrostatic spraying device for spraying the second color paint on the test piece coated with at least one layer of the first color paint include at least one of the gun distance, gun speed and voltage; wherein the gun distance is 200-240mm, the gun speed is 500-800mm / s, and the voltage is 50-70kv.

11. The paint mist pollution detection method for automobile painting according to any one of claims 1 to 10, characterized in that: In the step of applying the first color paint, the ambient temperature for applying the first color paint is 20-25° C. and the ambient humidity is 60%-80%; in the step of spraying the second color paint, the ambient temperature for spraying the second color paint is 20-25° C. and the ambient humidity is 60%-80%.

12. The method for detecting paint mist pollution in automobile painting according to any one of claims 1 to 10, characterized in that: In the evaluation step, the detection data includes at least one of a DOI value, an Lw value, a Sw value, a gloss value, and a color value.

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