CN117427862A

CN117427862A - Matte color repairing method for automobile coating

Info

Publication number: CN117427862A
Application number: CN202311472143.8A
Authority: CN
Inventors: 李明; 钟明强; 向微凡; 张宝林; 谢小龙; 刘杨茜雅
Original assignee: GAC Motor Co Ltd
Current assignee: GAC Motor Co Ltd
Priority date: 2023-11-06
Filing date: 2023-11-06
Publication date: 2024-01-23

Abstract

The invention discloses a matte color repairing method for automobile coating, which comprises the following steps: carrying out pretreatment on the paint surface defect; then carrying out color paint spraying on the pretreated area; then, rapidly drying the sprayed colored paint at a high temperature of 600-650 ℃; when the temperature of the colored paint is reduced to 200-250 ℃, atomizing at least one layer of bright repair varnish on the surface of the colored paint, wherein the particle size of the varnish is 0.3-0.5 mu m; finally, the sprayed varnish is dried. The invention can eliminate the glossiness difference between the repaired part and the unrepaired part, realize the defect repair of the paint surface of the matte color inner plate in a 'atomization' varnish mode, improve the coating qualification rate, and can reduce the beat loss and the single cost of the matte color coating without repainting the matte color coating defect.

Description

Matte color repairing method for automobile coating

Technical Field

The invention relates to the technical field of automobile coating and spraying, in particular to an automobile coating matte color repairing method.

Background

The matte color coating is also called as a matte paint, is one of automobile coating, and the glossiness of the common matte paint is 30% -40% (60 degrees) after being sprayed, so that the aesthetic feeling and texture of an automobile can be improved by spraying the matte paint, and the paint is deeply favored by young consumers.

Compared with the traditional varnish, the matt varnish has the characteristics of high extinction efficiency, high hardness and the like, and the matt varnish has the effect of forming the rough surface of a paint film by adding a small amount of matt powder with high specific surface area into the base varnish. The refraction index of the extinction powder is similar to that of the resin in the base paint, so that the color of the bottom layer can still be reflected. The principle of the production of the matte paint surface is mainly that the paint surface is rough, so that light irradiates on the paint surface, reflected light is uniformly distributed, and a diffuse reflection process is generated, so that a visual perception of low visual gloss is given to people, namely, a matte color is generally known.

At present, the spraying mode of the matte paint is to directly spray on the surface of the colored paint layer, but the spraying mode is generally accompanied with 15% of failure rate, so that repair is required, the defect condition of the matte paint surface cannot be repaired by the traditional repair mode, the whole part is generally required to be recoated, and the maintenance cost of consumers is increased. The repair is difficult because the matte paint surface is rough and uneven for diffuse reflection, but the conventional repair method of paint surface defects needs polishing and leveling treatment on the paint surface, and then polishing treatment is needed after the varnish is sprayed, so that the visual glossiness of the paint surface after the repair is finished is high, and the visual difference exists between the visual glossiness and the visual glossiness of the paint surface.

In addition, conventional varnishes generally do not require or define excessively high thicknesses of varnish spray coating as they do not affect how much the primer color is. However, for the matt paint, the display effect of the matt paint on the color of the primer is poor along with the increase of the thickness of the matt paint, that is, the thicker the matt paint is, the poorer the display effect of the color of the automobile primer is, which causes the problem of color difference, so that the thickness of the sprayed matt paint needs to be strictly and accurately controlled.

Disclosure of Invention

The invention aims to overcome the defect that the existing paint repair method can cause high visual glossiness of the paint after repair and has visual difference with peripheral matte color coating, and provides an automobile coating matte color repair method which can repair the defects of the inner plate paint and realize no visual difference of the glossiness and the hue of the paint.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention provides a matte color repairing method for automobile coating, which comprises the following steps:

step S1, carrying out pretreatment on paint surface defects;

s2, spraying the color paint on the area pretreated in the step S1, wherein the sprayed color paint is consistent with the color of the unrepaired part, and the paint surface has no step difference;

step S3, drying the color paint sprayed in the step S2;

s4, atomizing at least one layer of bright repair varnish on the surface of the colored paint when the colored paint is cooled to 200-250 ℃, wherein the particle size of the varnish is 0.3-0.5 mu m;

and S5, drying the varnish sprayed in the step S4.

In the above steps, the emphasis is on the fact that the varnish is atomized by using a tool when the varnish is sprayed, so that the particle size of the varnish is kept in the range of 0.3-0.5 μm. Thus, after the varnish is sprayed, the surface of the varnish is uneven in the form of "fine particles", and thus a diffuse reflection effect is achieved. It should be noted that, when the varnish is sprayed, leveling of the varnish surface is avoided, so that the diffuse reflection effect is not achieved.

Wherein the thickness of the varnish is preferably 12-18 μm. Through multiple experiments by the inventor, when the thickness of the varnish is smaller than 12 mu m, the protection effect on the primer/colored paint is poor, and the varnish thickness is different from that of other parts, so that the paint surface is uneven. When the thickness of the varnish is too thick, the leveling phenomenon is easy to occur, and finally the glossiness is increased, so that the paint surface has no matte effect.

Further, as one preferable embodiment, the varnish has a spray thickness of 15 μm and a particle diameter of 0.3 μm.

Further, the pretreatment process in step S1 includes the following sub-steps:

step S11, polishing the paint surface defect, and polishing and removing the defect, wherein the polishing depth reaches the depth of the defect on the paint surface;

step S12, wiping off fine scraps generated by polishing by using a wiping tool, and partially removing oil stains on the surface of a polishing position in the wiping process, so that the adhesive force of the surface of a workpiece can be improved, and the colored paint can be better adhered when the colored paint is sprayed; the wiping tool can be cloth, paper, sponge and the like;

and step S13, sweeping the polished position in the step S11 by using compressed air, and further removing fine dust on the surface of the workpiece.

Further, in step S12, the polishing position is preferably wiped with a wiping tool dipped in an alcohol solvent to remove the fine dust. The purpose of the alcohol dip is to wet the wiping tool, thereby providing better adhesion to the fines. Of course, other solvents may be used, but alcohol solvents are preferred because alcohol evaporates quickly, does not remain on the surface of the workpiece, and does not cause physical harm to the operator after evaporation.

Further, in step S3, the temperature of the thermal drying equipment is set to 600-650 ℃, the paint surface of the colored paint is dried rapidly, the baking distance is 4-7cm, and the baking time is 50-70 seconds, so that the surface of the colored paint is dried. Wherein, the hot baking equipment preferably uses a hot baking gun or a hand-held hot baking gun so as to quickly dry the colored paint.

Further, in step S4, the varnish is atomized by using an air spray gun, at least one layer of atomized two-component light repair varnish is sprayed on the surface of the colored paint, the atomized varnish on the surface of the colored paint cannot be leveled to form a film, a rough paint surface effect is achieved, and the paint surface is close to a matte paint surface. The varnish is preferably a two-component gloss repair high temperature varnish.

Further, the compressed air pressure of the air spray gun is set to be in the range of 0.6-0.8MPa.

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

Further, in step S5, the temperature of the hot baking equipment is set to be 140-150 ℃, the varnish surface is baked, and the baking distance is 70-90cm until the varnish is completely dried.

Furthermore, the baking equipment is a baking gun or a baking lamp, and the baking effect and the energy efficiency of the baking lamp are good in the actual use process because the baking varnish needs to be dried at low temperature for a long time. Of course, the same technical effects can be achieved by using a baking gun.

Compared with the prior art, the invention has the beneficial effects that the glossiness difference between the repaired part and the unrepaired part can be eliminated, the defect repair of the paint surface of the matte color inner plate can be realized by an atomization varnish mode, the coating qualification rate is improved, the defect of the matte color coating can be repaired without recoating, the beat loss can be reduced, and the single cost of the matte color coating is reduced.

Drawings

FIG. 1 is a flow chart of a method for repairing a matte color of an automobile coating;

FIG. 2 is a reference view of a paint roughness window;

FIG. 3 is a reference view of a varnish thickness window;

FIG. 4 is a reference graph of the effect of paint surface temperature T1 on gloss before varnish spraying;

FIG. 5 is a reference graph showing the influence of the atomized varnish particle diameter C0 on the gloss;

FIG. 6 is a reference graph showing the influence of varnish film thickness C1 on glossiness;

FIG. 7 is a graph showing the effect of the paint surface drying temperature T0 on the dehydration rate.

Detailed Description

The invention is further described below in connection with the following detailed description. Wherein the drawings are for illustrative purposes only and are not to be construed as limiting the present patent; for the purpose of better illustrating the embodiments, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the actual product dimensions; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numbers in the drawings of embodiments of the invention correspond to the same or similar components; in the description of the present invention, it should be understood that, if there is an azimuth or positional relationship indicated by terms such as "front", "rear", "left", "right", etc., based on the azimuth or positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, but it is not indicated or implied that the apparatus or element referred to must have a specific azimuth, be constructed and operated in a specific azimuth, and thus terms describing the positional relationship in the drawings are merely illustrative and should not be construed as limitations of the present patent, and specific meanings of the terms described above may be understood by those skilled in the art according to specific circumstances. Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature.

Embodiment one:

as shown in fig. 1, the present embodiment provides a repair method for a matte color of an automotive coating, where the repair method includes a repair method for a defect of a paint surface of a matte color and a repair method for a defect of an inner plate of a matte color automotive, and the repair method provided by the present embodiment is applicable, and the method includes the following steps:

step S1, carrying out pretreatment on paint surface defects;

step S3, drying the colored paint sprayed in the step S2 to dry the surface of the colored paint;

s4, atomizing a layer of bright repair varnish on the surface of the colored paint when the colored paint is cooled to 200-250 ℃, wherein the particle size of the varnish is 0.3-0.5 mu m, and in order to best realize the matte color paint surface effect, the varnish meets the matte glossiness standard, namely 30-40% (60 DEG angle), the surface roughness of the repaired part is controlled to be 0.3-0.4, and the thickness of the varnish is controlled to be 12-18 mu m, referring to fig. 2 and 3; in addition, when the varnish is sprayed, a tool is required to atomize the varnish to keep the particle size of the varnish within the range of 0.3-0.5 mu m, so that after the varnish is sprayed, the surface of the varnish can show the uneven result of 'fine particles', and the diffuse reflection effect is realized;

and S5, drying the varnish sprayed in the step S4 to completely dry the varnish.

In step S4, the leveling of the paint surface is avoided when the varnish is sprayed, and the amount or thickness of the varnish is controlled. If the spraying amount is too much or the thickness is too thick, the leveling phenomenon is easy to occur, and finally the glossiness is increased, so that the paint surface has no matte effect. In addition, the inventors have found that when the thickness of the varnish is less than 12 μm during the test, the protective effect on the primer/paint is poor, and the varnish thickness is different from that of other parts, resulting in uneven paint surface.

In this embodiment, the varnish comprises the following components: acrylic resin, amino resin, polyester resin, sag resistant resin, ultraviolet absorber, matting agent (matting powder) and auxiliary agent.

It should be noted that in some embodiments, the thickness of the varnish includes, but is not limited to, 12 μm, 14 μm, 16 μm, and 18 μm, which may also be any number in the range of 12-18 μm.

The implementation parameters are obtained through a test Design (DOE), the test design explores the influence of the repair process parameters on the glossiness of the paint film, and the main influence factors are obtained by the following steps:

the temperature (T1, unit: centigrade) of the paint surface after the high-temperature surface drying of the colored paint and before the varnish spraying;

atomized particle diameter (C0, unit: μm) of varnish;

and an atomized varnish film thickness (C1, unit: μm).

The three main influencing factors are subjected to orthogonal tests, and the results are shown in the following table:

as can be seen from the above table, the repairing process parameters of the scheme 4 are better, that is, the temperature t1=200 ℃ before the varnish is sprayed after the surface of the colored paint is dried, the atomized particle size c0=0.3 μm, the thickness c1=15 μm of the varnish, the glossiness of the repaired paint surface is 35, and the standard glossiness g60° =30-40 is met. Also, it is apparent from the table that when the temperature of T1 is low (=100 ℃), the glossiness is high, and when the temperature of T1 is high, the glossiness is low.

Based on the above, the implementation window of the T1, C0 and C1 repairing process parameters is further explored by adopting a control variable method in the embodiment, and the following conclusion is obtained:

(1) And under the premise that the surface drying temperature is 600 ℃, the surface drying time is 1min, the atomized particle size of varnish is C0=0.3 mu m, and the thickness of varnish is C1=15 mu m, the surface of the surface is cooled by adopting compressed air blowing, and the influence of a repair parameter T1 on the glossiness of the paint surface is explored. As a result, as shown in FIG. 4, the higher the surface temperature (T1) of the colored paint before the varnish is sprayed, the gloss of the paint surface after repair is reduced and then tends to be unchanged, and the optimal range of T1 is 200-250 ℃.

(2) On the premise that the surface drying temperature is 600 ℃, the surface drying time is 1min, T1=230 ℃, and the varnish thickness C1=15 μm, the spray gun parameters are adjusted, the atomization particle size is measured by using a spray laser particle size analyzer, and the influence of the repair parameter C0 on the gloss of the varnish surface is explored. As a result, as shown in FIG. 5, the larger the atomized particle diameter (C0) of the varnish, the gloss of the paint surface after repair tends to be unchanged after the decrease, and the optimal range of C0 is 0.3 to 0.5. Mu.m.

(3) And under the premise that the surface drying temperature is 600 ℃, the surface drying time is 1min, T1=230 ℃, and the atomized varnish particle diameter C0=0.4 mu m, measuring the film thickness of the dried varnish by adopting a layered film thickness meter, and exploring the influence of the repairing parameter C1 on the glossiness of the paint surface. As a result, as shown in FIG. 6, the smaller the varnish thickness (C1), the higher the gloss of the paint surface after repair, and the optimum range of C1 is 12 to 18. Mu.m.

In summary of the above control experiments, the following results: when the temperature of the colored paint is reduced to 200-250 ℃, a layer of bright repair varnish is atomized on the surface of the colored paint, the thickness of the varnish is controlled to be 12-18 mu m, and the particle size of the varnish is 0.3-0.5 mu m, so that the matte color paint surface effect can be best realized, and the matte gloss standard is met.

Embodiment two:

referring to fig. 1, the present embodiment provides another method for repairing a matte color of an automotive coating, which is different from the first embodiment in that the method includes the following steps:

step S11, polishing the paint defect part, and polishing and removing the defect; the polishing can be performed by a robot or manual, and after polishing, the part to be painted can have certain roughness, so that the adhesive force of the colored paint is effectively improved, and the quality of a product is further improved; the polishing depth reaches the depth of the defect on the paint surface, and the polishing tool adopts sand paper with the number more than 1500# because the sand paper with higher mesh number is used for polishing, so that sand paper lines can be avoided on the premise of increasing the adhesive force of the primer, and the attractiveness of the product is improved;

step S12, wiping off fine scraps generated by polishing by using a wiping tool, and partially removing oil stains on the surface of a polishing position in the wiping process, so that the adhesive force of the surface of a workpiece can be improved, and the colored paint can be better adhered when the colored paint is sprayed; the wiping tool can be cloth, paper, sponge and the like; the wiping tool can also dip alcohol to wipe the grinding position, so that the fine scraps can be removed, the wiping tool is moistened by the purpose of dipping the alcohol solvent, so that the fine scraps have better adhesion effect, the alcohol volatilizes quickly, no residue is caused on the surface of a workpiece, and no harm is caused to the body of an operator after the alcohol volatilizes;

step S13, spraying compressed air by using an air spray gun to sweep the polished position in the step S11, and further removing fine scraps on the surface of the workpiece;

step S14, if necessary, cooling the workpiece to 23+/-2 ℃ to prevent the workpiece from being too high in temperature and the volatilization speed of the primer spraying solvent from being increased;

s2, carrying out colored paint spraying on the area subjected to the pretreatment in the steps S11-S14, wherein the sprayed colored paint is consistent with the color of the unrepaired part, and the painted surface has no step difference;

s4, atomizing a layer of bright repair varnish on the surface of the colored paint when the colored paint is cooled to 200-250 ℃, wherein the particle size of the varnish is 0.3-0.5 mu m, and the thickness of the varnish is controlled to be 12-18 mu m;

In the step S4, the varnish is preferably sprayed uniformly for a plurality of times, and the range of the reciprocating times is 3-15 times; more preferably, the reciprocation number range value is 6 to 10 times; particularly, the phenomenon of uneven paint thickness caused by excessive spraying once in the spraying process is avoided, and the local thickness of the varnish exceeds 18 mu m easily due to excessive spraying once, so that the final visual effect is affected.

Embodiment III:

in this embodiment, a hand-held baking gun is used to finish the step of baking the colored paint in step S3. Step S3 is a high-temperature baking procedure, specifically, the air outlet temperature of the hand-held hot baking gun is adjusted to 600-650 ℃, and the surface of the colored paint is retraced to dry. The distance between the air outlet of the hand-held hot baking gun and the colored paint surface is controlled to be about 5cm, and the baking time is about 1 minute. The purpose of using high temperature and quick drying is to dry the colored paint, but the deep colored paint is still in a flowing or semi-flowing state, so that after standing, the colored paint can generate a leveling effect due to the gravity and the tension effect of liquid, and the colored paint at the repaired position is consistent with the original factory paint in visual sense and sense.

It is noted that in some embodiments, the temperature of the high temperature bake includes, but is not limited to, 600 ℃, 610 ℃, 620 ℃, 630 ℃, 640 ℃, and 650 ℃, which may also be any point value or range of values in the range of 600-650 ℃.

Based on the requirements of the spraying process, the surface drying dehydration rate of the water-based paint is required to be greater than 85%, the surface drying time is verified to be 1min (in order to ensure the repairing efficiency) by adopting a variable control method, and the influence of the surface drying temperature of the paint on the dehydration rate is shown in fig. 7, wherein the surface drying dehydration rate of the paint is increased along with the temperature and then the surface drying time of the paint is reduced. The method mainly comprises the steps that when the temperature is low (100-600 ℃), the surface drying temperature is higher, the moisture evaporates faster, and when the temperature is too high (650-750 ℃), the moisture on the surface of the paint volatilizes too fast, so that the internal moisture cannot be removed in time, and the surface drying dehydration rate is low. Therefore, on the premise that the surface drying time is 1min, the optimal window of the surface drying temperature of the color paint is 600-650 ℃.

Embodiment four:

based on the first embodiment or the second embodiment, in this embodiment, the air spray gun is used to atomize the varnish, at least one layer of atomized two-component light repair varnish is sprayed on the surface of the colored paint, the atomized varnish on the surface of the colored paint cannot be leveled to form a film, so as to achieve a rough paint surface effect and approach to a matte paint surface. The varnish is preferably a two-component gloss repair high temperature varnish.

Preferably, the compressed air pressure of the air lance, i.e. the pressure regulation value of the air lance, is set in the range of 0.6-0.8MPa.

Preferably, the spraying distance between the liquid outlet of the air spray gun and the colored paint surface is 20+/-5 cm.

Fifth embodiment:

in this embodiment, a baking lamp is used to finish the step of baking varnish in step S5. Step S5 is a low-temperature and long-time baking procedure, specifically, the temperature of the baking lamp is set to 140-150 ℃, and the baking lamp is adjusted to be 70-90cm away from the surface of the varnish, so that the heating range of the baking lamp can be completely covered at the repairing position. And fixing the baking lamp to slowly bake the varnish at low temperature for a long time until the varnish is completely dried.

It is noted that in some embodiments, the low temperature bake temperature includes, but is not limited to, 140 ℃, 142 ℃, 144 ℃, 146 ℃, 148 ℃, and 150 ℃, which may also be any point value or range of values in the range of 140-150 ℃.

In the specific content of the above embodiment, any combination of the technical features may be performed without contradiction, and for brevity of description, all possible combinations of the technical features are not described, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

It is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.

Claims

1. The matte color repairing method for the automobile coating is characterized by comprising the following steps of:

step S1, carrying out pretreatment on paint surface defects;

s2, carrying out colored paint spraying on the area pretreated in the step S1;

step S3, drying the color paint sprayed in the step S2;

s4, atomizing at least one layer of bright repair varnish on the surface of the colored paint when the colored paint is cooled to 200-250 ℃, wherein the spraying thickness of the varnish is 12-18 mu m, and the particle size of the varnish is 0.3-0.5 mu m;

and S5, drying the varnish sprayed in the step S4.

2. The method for repairing a matte color for automotive coating according to claim 1, wherein the thickness of the varnish is 15 μm and the particle size of the varnish is 0.3 μm.

3. The method for repairing a matte color of an automotive paint according to claim 1, wherein the pretreatment process in step S1 comprises the following sub-steps:

step S11, polishing the paint defect part, and polishing and removing the defect;

step S12, wiping off fine scraps generated by polishing by using a wiping tool;

step S13, sweeping the polished position in step S11 by using compressed air.

4. The method for repairing a matte color of automotive paint according to claim 3, wherein in step S12, a wiping tool is further used to dip in an alcohol solvent to wipe the polished position, thereby removing the fine dust.

5. The method for repairing the matte color of the automobile coating according to claim 1, wherein in the step S3, the temperature of the hot baking equipment is set to 600-650 ℃, the paint surface of the paint is baked, the baking distance is 4-7cm, and the baking time is 50-70 seconds, so that the paint surface is dried.

6. The method for repairing a matte color of an automotive coating according to claim 1, wherein in step S4, the varnish is atomized by using an air spray gun, and at least one layer of atomized two-component gloss repair varnish is sprayed on the surface of the paint.

7. The method for repairing a matte color for automotive coating according to claim 6, wherein the compressed air pressure of the air spray gun is set to be in the range of 0.6 to 0.8MPa.

8. The method for repairing a matte color for automotive coating according to claim 6, wherein the spraying distance between the liquid outlet of the air spray gun and the paint surface is 15-25cm.

9. The method for repairing a matte color for automotive coating according to claim 1, wherein in step S5, the temperature of the hot baking equipment is set to 140-150 ℃, the varnish paint surface is baked, and the baking distance is 70-90cm until the varnish is completely dried.

10. The method for repairing a matte color of an automotive coating according to claim 9, wherein the baking equipment is a baking gun or a baking lamp.