A method for repairing a matte color of automobile coating

Abstract

The application discloses a car coating matte color repair method, comprising the following steps: pretreating the paint surface defects; then spraying color paint on the pretreated area; then rapidly drying the sprayed color paint at a high temperature of 600-650 DEG C; when the color paint is cooled to 200-250 DEG C, atomizing at least one layer of bright repair varnish on the surface of the color paint, the particle size of the varnish is 0.3-0.5 mu m; finally, drying the sprayed varnish. The application can eliminate the gloss difference between the repaired part and the unrepaired part, realize the defect repair of the matte color inner plate paint surface by the atomizing varnish method, improve the coating qualification rate, and the matte color coating defects can be repaired without re-coating, which can reduce the tact loss and reduce the single station cost of the matte color coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile painting spraying, and more particularly to a method for repairing a matte color for automobile painting. BACKGROUND

[0002] Matte color painting, also known as matte paint, is a kind of automobile painting. After spraying, the common matte paint has a glossiness of 30%-40% (60-degree angle). Spraying matte paint can improve the aesthetics and texture of a car and is favored by young consumers.

[0003] Compared with traditional bright varnish, matte paint has high extinction efficiency and high hardness. It mainly forms a rough paint film surface by adding a small amount of high specific surface area extinction powder to the original paint. Because the refractive index of the extinction powder is similar to that of the resin in the original paint, the underlying color can still be reflected. The principle of the matte paint surface is that the paint surface is rough, causing the reflected light to be evenly distributed when light is incident on the paint surface, resulting in a process of diffuse reflection. Therefore, it gives a person a low visual gloss in vision, which is commonly known as matte color.

[0004] At present, the spraying method for matte paint is to directly spray on the surface of the color paint layer. However, this spraying method generally has a 15% unqualified rate, resulting in the need for repair. The defect of the matte paint surface cannot be repaired by the traditional repair method. Generally, the entire part needs to be recoated, increasing the maintenance cost of the consumer. The reason why it is difficult to repair is that the matte paint surface is rough and uneven in order to diffuse reflection. However, the conventional repair method for paint defects requires polishing the paint surface, and then polishing after spraying the varnish, resulting in a high visual gloss of the repaired paint surface, which is visually different from the surrounding matte color painting.

[0005] In addition, because the conventional varnish does not have a significant impact on the color of the base paint, the thickness of the varnish spraying is generally not highly required or limited. However, for matte paint, the display effect of the underlying color is deteriorated with the increase in the thickness of the matte paint, that is, the thicker the matte paint, the worse the display effect of the underlying color of the car, which may cause color difference problems. Therefore, the thickness of the sprayed matte paint needs to be strictly and accurately controlled. SUMMARY

[0006] The present application aims to overcome the defect that the existing paint repair method causes the repaired paint surface to have a high visual gloss, which is visually different from the surrounding matte color painting. The present application provides a method for repairing a matte color for automobile painting, which can repair the defect of the inner plate paint surface and realize no visual difference in gloss and color phase.

[0007] To solve the above technical problems, the technical solution adopted by the present application is as follows:

[0008] The present application provides a method for repairing the dull color of a vehicle coating, comprising the following steps:

[0009] Step S1, pre-treating the paint defect area;

[0010] Step S2, spraying color paint on the area pre-treated in step S1, the sprayed color paint should be consistent with the color of the un-repaired part, and the paint surface should have no step difference;

[0011] Step S3, drying the color paint sprayed in step S2;

[0012] Step S4, when the color paint is cooled to 200-250 degrees Celsius, at least one layer of bright repair varnish is atomized on the surface of the color paint, the particle size of the varnish is 0.3-0.5 μm;

[0013] Step S5, drying the varnish sprayed in step S4.

[0014] In the above steps, the key point is that when spraying the varnish, a tool should be used to atomize the varnish, so that the particle size of the varnish is kept within the range of 0.3-0.5 μm. In this way, after spraying the varnish, the surface of the varnish will present a "granular" uneven result, achieving the effect of diffuse reflection. It should be noted that when spraying the varnish, the paint surface should be avoided to be leveled, so as to achieve the effect of diffuse reflection.

[0015] Preferably, the thickness of the varnish is 12-18 μm. Through repeated experiments by the inventor, when the thickness of the varnish is less than 12 μm, the protection effect on the primer / color paint is poor, and the thickness of the varnish is different from that of other parts, causing the paint surface to be uneven. When the thickness of the varnish is too thick, the above-mentioned "leveling" phenomenon is easy to occur, ultimately leading to the increase of gloss, so that the paint surface has no dull effect.

[0016] Further, as one of the preferred schemes, the spraying thickness of the varnish is 15 μm, and the particle size of the varnish is 0.3 μm.

[0017] Further, the pre-treatment process in step S1 comprises the following sub-steps:

[0018] Step S11, polishing the paint defect area, removing the defect by polishing, wherein the polishing depth should reach the depth of the paint defect;

[0019] Step S12, using a wiping tool to wipe off the fine debris generated by polishing, and during the wiping process, the surface dirt at the polishing position will also be partially removed, so as to improve the adhesion of the workpiece surface, and the color paint can be better adhered when spraying; the wiping tool can be cloth, paper, sponge, etc.

[0020] Step S13, using compressed air to blow the polished position of step S11, further removing the fine chips on the surface of the workpiece.

[0021] Further, in step S12, the polished position is preferably wiped using a wiping tool dipped in alcohol solvent to remove the fine chips. The purpose of dipping the alcohol solvent is to wet the wiping tool, so that the fine chips have better adhesion effect. Of course, other solvents can also be dipped, but the reason for preferring alcohol solvent is that alcohol evaporates quickly and does not leave residue on the surface of the workpiece, and alcohol does not cause physical harm to the operator after evaporation.

[0022] Further, in step S3, the temperature of the heat drying device is set to 600-650 degrees Celsius to quickly dry the color paint surface, the baking distance is 4-7 cm, and the baking time is 50-70 seconds to dry the color paint surface. The heat drying device preferably uses a heat drying gun or a handheld heat drying gun to quickly dry the color paint.

[0023] Further, in step S4, the varnish is atomized using an air spray gun, and at least one layer of atomized two-component bright finish repair varnish is sprayed on the color paint surface. The atomized varnish on the color paint surface cannot flow flat to form a film, achieving a rough paint surface effect close to a matte paint surface. The varnish preferably uses two-component bright finish repair high-temperature varnish.

[0024] Further, the compressed air pressure of the air spray gun is set to 0.6-0.8 MPa.

[0025] Further, the spraying distance between the liquid outlet of the air spray gun and the color paint surface is 15-25 cm.

[0026] Further, in step S5, the temperature of the heat drying device is set to 140-150 degrees Celsius to dry the varnish surface, the baking distance is 70-90 cm, and the varnish is completely dried.

[0027] Further, the heat drying device is a heat drying gun or a baking lamp. Since drying the varnish requires low temperature and long time drying, the baking lamp has better drying effect and energy efficiency in actual use. Of course, the same technical effect can also be achieved by using a heat drying gun.

[0028] Compared with the prior art, the beneficial effects of the present application are that the gloss difference between the repaired part and the unrepaired part can be eliminated, the matte color inner plate paint surface defect repair can be achieved by atomizing the varnish, the coating qualification rate can be improved, and the matte color coating defect can be repaired without re-coating, which can reduce the loss of beats and reduce the cost of single matte color coating. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1Flow chart of the repair method for the matt color of automobile painting;

[0030] Figure 2 Reference chart for the roughness window of the paint surface;

[0031] Figure 3 Reference chart for the thickness window of the clear paint;

[0032] Figure 4 Reference chart for the influence of the color paint surface temperature T1 on the glossiness before the clear paint spraying;

[0033] Figure 5 Reference chart for the influence of the clear paint atomization particle size C0 on the glossiness;

[0034] Figure 6 Reference chart for the influence of the clear paint film thickness C1 on the glossiness;

[0035] Figure 7 Reference chart for the influence of the color paint surface dry temperature T0 on the dehydration rate. DETAILED DESCRIPTION

[0036] The application will be further described below in connection with the specific embodiments. The accompanying drawings are only used for exemplary description and cannot be understood as a limitation to the patent; in order to better illustrate the embodiments, some components in the drawings can be omitted, enlarged or reduced, and do not represent the actual product size; for those skilled in the art, it can be understood that some well-known structures and their descriptions in the drawings can be omitted.

[0037] The same or similar reference numerals in the drawings of the embodiments of the application correspond to the same or similar components; in the description of the application, it should be understood that the orientations or positional relationships indicated by the terms "front", "back", "left", "right" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and therefore the terms describing the positional relationships in the drawings cannot be understood as a limitation to the patent, and the specific meanings of the above terms can be understood by those skilled in the art according to the specific circumstances. In addition, the description of "first", "second" and the like in the application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features.

[0038] Embodiment I:

[0039] As Figure 1As shown, the present embodiment provides a method for repairing a matte color coating of a vehicle, which includes a method for repairing defects on a matte color coating and a method for repairing defects on an inner panel of a matte color vehicle. Both methods can be applied to the repairing method provided by the present embodiment, which includes the following steps:

[0040] Step S1, pre-treating the defect on the coating;

[0041] Step S2, spraying color paint on the area pre-treated in step S1. The color paint sprayed should be consistent with the color of the un-repaired part, and the coating should have no step difference;

[0042] Step S3, drying the color paint sprayed in step S2 to make the color paint surface dry;

[0043] Step S4, when the color paint is cooled to 200-250 degrees Celsius, a layer of bright repair clear paint is atomized on the surface of the color paint. The particle size of the clear paint is 0.3-0.5 μm. In order to best achieve the effect of matte color coating and meet the standard of matte gloss, i.e. 30%-40% (60 degree angle), see Figure 2 and Figure 3 , the surface roughness of the repaired part is controlled at 0.3-0.4, and the thickness of the clear paint is controlled at 12-18 μm. In addition, when spraying the clear paint, a tool should be used to atomize the clear paint, so that the particle size of the clear paint is kept within the range of 0.3-0.5 μm. In this way, after spraying the clear paint, the surface of the clear paint will present a "granular" uneven result, achieving a diffuse reflection effect;

[0044] Step S5, drying the clear paint sprayed in step S4 to make it completely dry.

[0045] It should be noted that in step S4, when spraying the clear paint, the coating should not be leveled. The spraying amount or thickness of the clear paint should be controlled. If the spraying amount or thickness is too much, the phenomenon of "leveling" will occur, which will eventually cause the gloss to rise, resulting in no matte effect on the coating. In addition, the inventors have found that when the thickness of the clear paint is less than 12 μm, the protection effect on the base paint / color paint is poor, and the thickness of the clear paint is different from that of other parts, causing the coating to be uneven.

[0046] In the present embodiment, the components of the clear paint include acrylic resin, amino resin, polyester resin, anti-sagging resin, ultraviolet absorber, flatting agent (flatting powder) and auxiliary agent.

[0047] It should be noted that in some embodiments, the thickness of the clear paint includes but is not limited to 12 μm, 14 μm, 16 μm and 18 μm, and it can also be any value within the range of 12-18 μm.

[0048] The above implementation parameters are obtained by a design of experiment (DOE) which explores the influence of the repair process parameters on the paint film gloss, and the main influencing factors include:

[0049] the temperature of the paint surface after the color paint high-temperature surface drying and before the varnish spraying (T1, unit: degree Celsius);

[0050] the varnish atomization particle size (C0, unit: μm);

[0051] and the atomized varnish film thickness (C1, unit: μm).

[0052] Among them, orthogonal test is conducted on the three main influencing factors, and the results are shown in the following table:

[0053]

[0054] As can be seen from the above table, the repair process parameters of scheme 4 are relatively optimal, that is, the temperature T1 of the paint surface after the color paint surface drying and before the varnish spraying is 200°C, the varnish atomization particle size C0 is 0.3 μm, the varnish film thickness C1 is 15 μm, and the gloss of the paint surface after the repair is 35, which meets the standard gloss G60° = 30-40. Moreover, it can be obviously seen from the table that when the T1 temperature is relatively low (= 100°C), the gloss is relatively high, and when the T1 temperature is relatively high, the gloss is relatively low.

[0055] On this basis, the control variable method is further used to explore the implementation window of the T1, C0 and C1 repair process parameters, and the following conclusions are obtained:

[0056] (1) On the premise that the surface drying temperature is 600 degrees Celsius, the surface drying time is 1 min, the varnish atomization particle size C0 is 0.3 μm, and the varnish film thickness C1 is 15 μm, the influence of the repair parameter T1 on the gloss of the paint surface is explored by using compressed air to blow and cool the surface drying surface. The results are shown in Figure 4 , the higher the temperature (T1) of the paint surface before the varnish spraying, the gloss of the paint surface after the repair presents a trend of first decreasing and then being constant, and the optimal range of T1 is 200-250 degrees Celsius.

[0057] (2) On the premise that the surface drying temperature is 600 degrees Celsius, the surface drying time is 1 min, T1 is 230 degrees Celsius, and the varnish film thickness C1 is 15 μm, the influence of the repair parameter C0 on the gloss of the paint surface is explored by adjusting the spray gun parameters and using a spray laser particle size analyzer to measure the atomization particle size. The results are shown in Figure 5 , the larger the varnish atomization particle size (C0), the gloss of the paint surface after the repair presents a trend of first decreasing and then being constant, and the optimal range of C0 is 0.3-0.5 μm.

[0058] (3)Under the condition of surface drying temperature 600℃, surface drying time 1min, T1=230℃, varnish atomized particle size C0=0.4μm, the varnish film thickness after drying is determined by using the layered film thickness gauge, and the influence of the repair parameter C1 on the paint surface gloss is explored. The results are shown in Table 2. Figure 6 As shown in Table 2, the smaller the varnish film thickness (C1), the higher the paint surface gloss after repair, and the optimal range of C1 is 12-18μm.

[0059] According to the above contrast test, it is concluded that: when the color paint is cooled to 200-250℃, a layer of bright repair varnish is atomized on the surface of the color paint, the thickness of the varnish is controlled in the range of 12-18μm, and the particle size of the varnish is 0.3-0.5μm, so that the matt color paint surface effect can be best achieved, and the matt gloss standard can be met.

[0060] Example Two

[0061] Referring to Figure 1 , the embodiment provides another repair method for matt color paint of automobile coating, which is different from example one and includes the following steps:

[0062] Step S11, polishing treatment is performed on the paint surface defect, and the defect is polished and removed; wherein, the polishing can be robot polishing or manual polishing, after polishing, the part to be painted has a certain roughness, effectively improving the adhesion of the color paint, and thus improving the quality of the product; the polishing depth should reach the depth of the defect on the paint surface, and the polishing tool uses sandpaper with a mesh number of more than 1500, because using sandpaper with a higher mesh number for polishing can avoid the appearance of sandpaper lines under the premise of increasing the adhesion of the primer, and improve the aesthetics of the product;

[0063] Step S12, using a wiping tool to wipe off the fine particles generated by polishing, and part of the surface oil at the polishing position is also removed during the wiping process, so as to improve the adhesion of the workpiece surface and make the color paint adhere better when spraying the color paint; the wiping tool can be cloth, paper, sponge, etc.; the wiping tool can also be dipped in alcohol to wipe the polishing position to remove the fine particles, the purpose of dipping in alcohol is to wet the wiping tool, so as to have better adhesion effect on the fine particles, and alcohol volatilizes quickly and will not be left on the workpiece surface, and alcohol volatilization will not cause physical harm to the operator;

[0064] Step S13, using an air spray gun to spray compressed air to blow the position polished in step S11, to further remove the fine particles on the surface of the workpiece;

[0065] Step S14, if necessary, the workpiece can also be cooled to 23±2℃ to prevent the temperature of the workpiece from being too high, which will cause the volatilization speed of the primer spraying solvent to increase;

[0066] Step S2, color paint is sprayed on the area after the pre-treatment of steps S11-S14, the sprayed color paint should be consistent with the color of the un-repaired part, and the paint surface has no step difference;

[0067] Step S3, the color paint sprayed in step S2 is dried to make the color paint surface dry;

[0068] Step S4, when the color paint is cooled to 200-250 degrees Celsius, a layer of bright repair varnish is atomized on the surface of the color paint, the particle size of the varnish is 0.3-0.5 μm, and the thickness of the varnish is controlled to be 12-18 μm;

[0069] Step S5, the varnish sprayed in step S4 is dried.

[0070] It should be noted that in step S4, the varnish is preferably sprayed in multiple uniform spraying ways, and the reciprocating frequency range is 3-15 times; more preferably, the reciprocating frequency range is 6-10 times; in particular, the spraying process avoids too much spraying at one time, which causes uneven thickness of the paint surface, and too much spraying at one time easily makes the local thickness of the varnish exceed 18 μm, affecting the final visual effect.

[0071] Example Three:

[0072] On the basis of example one or example two, in this embodiment, a handheld hot air gun is used to complete the drying process of the color paint in step S3. Step S3 is a high-temperature baking process, specifically, the air outlet temperature of the handheld hot air gun is adjusted to 600-650 degrees Celsius, and the color paint surface is swept back and forth to make it dry. The distance between the air outlet of the handheld hot air gun and the color paint surface is controlled to be about 5 cm, and the baking time is about 1 minute. The purpose of using high temperature and fast drying is to make the color paint dry, but the deep layer of the color paint is still in a flowing or semi-flowing state. After standing, due to the action of gravity and the tension of the liquid, the color paint will have a "leveling" effect, so that the color paint of the repaired part is consistent with the original factory paint in visual sense.

[0073] It should be noted that in some embodiments, the high-temperature baking temperature includes but is not limited to 600℃, 610℃, 620℃, 630℃, 640℃ and 650℃, and it can also be any point value or range value in the range of 600-650℃.

[0074] Based on the spraying process requirements, the water-based color paint surface drying rate must be greater than 85%, the variable control method is used to verify that the surface drying time is 1 min (to ensure the repair efficiency), and the effect of color paint surface drying temperature on the dehydration rate is as follows: Figure 7As shown, the surface dryness rate of the color paint increases with the increase of temperature, and then decreases. This is mainly because when the temperature is low (100-600 degrees Celsius), the higher the surface dryness temperature, the faster the water evaporation. When the temperature is too high (650-750 degrees Celsius), the water in the surface of the color paint volatilizes too fast, causing the internal water to be unable to dry out in time, resulting in a low surface dryness rate. Therefore, under the premise that the surface dry time is 1 min, the optimal window of the color paint surface dry temperature is 600-650 degrees Celsius.

[0075] Embodiment Four:

[0076] On the basis of Embodiment One or Embodiment Two, in this embodiment, the air spray gun is used to atomize the varnish, and at least one layer of atomized two-component bright repair varnish is sprayed on the surface of the color paint. The varnish atomized on the surface of the color paint cannot be leveled to form a film, achieving a rough paint surface effect close to a matte paint surface. The varnish preferably uses a two-component bright repair high-temperature varnish.

[0077] Preferably, the compressed air pressure of the air spray gun, that is, the set range of the pressure adjustment value of the air spray gun, is 0.6-0.8 MPa.

[0078] Preferably, the spraying distance between the liquid outlet of the air spray gun and the color paint surface is 20±5 cm.

[0079] Embodiment Five:

[0080] On the basis of Embodiment One or Embodiment Two, in this embodiment, the baking lamp is used to complete the varnish drying process in step S5. Step S5 is a low-temperature, long-time baking process. Specifically, the temperature of the baking lamp is set to 140-150 degrees Celsius, and it is adjusted to be 70-90 cm away from the surface of the varnish, ensuring that the heating range of the baking lamp can completely cover the repaired position. The baking lamp is fixedly arranged to slowly bake the varnish at a low temperature for a long time until the varnish is completely dry.

[0081] It should be noted that in some embodiments, the low-temperature baking temperature includes but is not limited to 140℃, 142℃, 144℃, 146℃, 148℃ and 150℃, and it can also be any point value or range value in the range of 140-150℃.

[0082] In the specific content of the above specific embodiments, any combination of technical features can be combined without contradiction. In order to make the description concise, not all possible combinations of the above technical features are described, but as long as the combination of these technical features does not exist contradiction, it should be considered as the scope of the description.

[0083] Obviously, the above embodiments of the present application are merely exemplary but not intended to limit the embodiments of the present application. Based on the above description, any other variations or changes can be made by those skilled in the art without departing from the spirit and principles of the present application. It is not necessary to list all the embodiments here. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall fall within the scope of the claims of the present application.

Claims

1. A method for repairing a matte color of an automobile coating, characterized by, The method comprises the following steps: Step S1, pre-treating the paint defect area; Step S2, spraying color paint on the area pre-treated in step S1; Step S3, drying the color paint sprayed in step S2, setting the temperature of the heat drying equipment to 600-650 degrees Celsius, drying the color paint surface, the baking distance being 4-7 cm, the baking time being 50-70 seconds, and drying the color paint surface; Step S4, when the color paint is cooled to 200-250 degrees Celsius, atomizing at least one layer of bright repair varnish on the color paint surface, the spraying thickness of the varnish being 12-18 μm, and the particle size of the varnish being 0.3-0.5 μm; Step S5, drying the varnish sprayed in step S4, setting the temperature of the heat drying equipment to 140-150 degrees Celsius, drying the varnish surface, the baking distance being 70-90 cm, and completely drying the varnish.

2. The automobile painting matte color repair method according to claim 1, characterized by, The thickness of the varnish is 15 μm, and the particle size of the varnish is 0.3 μm.

3. The automobile painting matte color repair method according to claim 1, characterized by, The pre-treatment procedure in step S1 comprises the following sub-steps: Step S11, polishing the paint defect area to remove the defect; Step S12, wiping off the fine particles generated by polishing using a wiping tool; Step S13, blowing the polished position in step S11 using compressed air.

4. The automobile painting matte color repair method according to claim 3, characterized by, In step S12, the fine particles are removed by using a wiping tool to dip alcohol solvent and wipe the polished position.

5. The automobile painting matte color repair method according to claim 1, characterized by, In step S4, the varnish is atomized using an air spray gun, and at least one layer of atomized two-component bright repair varnish is sprayed on the color paint surface.

6. The automobile painting matte color repair method according to claim 5, characterized by, The compressed air pressure of the air spray gun is set to 0.6-0.8 MPa.

7. The automobile painting matte color repair method according to claim 5, characterized by, The spraying distance between the liquid outlet of the air spray gun and the color paint surface is 15-25 cm.

8. The automobile painting matte color repair method according to claim 1, characterized by, The heat drying equipment is a heat drying gun or a baking lamp.

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