JP2000061395A - Coating method for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method for automobiles whereby a part of an intercoat formed on an exterior panel of an automobile body is scarecely noticeable in terms of color even when the part of the intercoat is attached to a color coating film of an interior panel and whereby the incongruity of color between the interior panel and the exterior panel is eliminated. SOLUTION: In a coating method for automobiles wherein a coating material (A) for an interior panel of an automobile body is applied to the interior panel and then an intercoat material (B) and a colored topcoat (C) are applied, the color tone of the coating material (A) for an interior panel is made equal or similar to that of the colored top coat (C) and a coating material which forms a colorless transparent coating film is used as the intercoat (C).

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the color of an intermediate coating applied to an outer panel of an automobile body, even if a part of the intermediate coating adheres to a colored coating on the inner panel. The present invention relates to a method for coating an automobile body in which the inner panel portion and the outer panel portion are hardly noticeable, and the color discomfort between the inner plate portion and the outer plate portion is eliminated. 2. Description of the Related Art As a method for coating an inner plate portion and an outer plate portion of an automobile body, a color paint having the same color or a similar color as that of a top coat for the outer plate portion is applied to the inner plate portion. In many cases, a step of sequentially applying a gray intermediate coat and a target color top coat to the outer plate portion by spray coating is employed. However, a part of the gray-colored intermediate coating material spray-coated on the outer plate portion adheres to the inner coating surface of the adjacent inner plate portion, and as a result, on the inner plate portion, the already-painted colored coating film is removed. Since the color tone of the gray color for the outer panel portion adhered to the coated surface was different from that of the intermediate coating material, it was conspicuous and was not preferable in appearance. SUMMARY OF THE INVENTION [0003] The present invention provides an unpleasant color sensation even if an intermediate coating for the outer panel adheres to the already painted surface of the inner panel of the automobile. Regarding a novel coating method that does not lower the appearance without deteriorating the appearance, the present inventors have found that the feature can be achieved by using a colorless and transparent intermediate coating as the intermediate coating for the outer panel, and completed the present invention. [0004] That is, the present invention provides an automotive coating in which an inner plate of an automobile body is coated with a coating for an inner plate (A), and then an outer plate is coated with a middle coating (B) and a colored top coating (C). The method according to claim 1, wherein the color tone of the paint (A) for the inner plate is the same or similar to that of the colored top coat (C), and the intermediate paint (B) is a paint that forms a colorless and transparent coating film. The present invention relates to a coating method (hereinafter, referred to as the present method). [0005] In this method, the outer plate portion of the vehicle body is
A portion facing the outside of the vehicle body with the door, hood, hood, and the like closed, such as a hood, panel roof, trunk lid, fender, bumper, door outside, and pillar. , Apron, etc.
In addition, examples of the inner plate include a bonnet back surface, a trunk lid back surface, a door opening, and a gasoline inlet back surface. The material of the outer plate portion and the inner plate portion is often made of metal, but may be made of plastic. [0006] Before coating the above-mentioned paint, the outer plate and the inner plate are coated with an undercoat paint such as a known cationic electrodeposition paint on a metal object, and degreased with plastic. It is preferable to perform a surface treatment or the like in advance. First, the inner plate portion is coated with a paint (A) for an inner plate portion. It is preferable that the color tone of the paint (A) is the same as or similar to that of the colored overcoat paint (C) applied to the outer panel of the same vehicle body. Here, "approximately" means that the paint is applied to the coating surface of the paint (A) for the inner plate portion in the form of a spot with the spray-dust of the colored top coat paint (C) for the outer plate portion, and there is a difference between the two colors. Even if there is any difference, it means that the difference is included within a range where the user does not visually feel unnatural color. [0008] As the paint (A) for the inner plate portion, a resin composition,
Thermosetting paints containing color pigments and organic solvents are particularly preferred. As the resin composition, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, or a urethane resin having a functional group such as a hydroxyl group, a carboxyl group, or an epoxy group, and a melamine resin capable of reacting with these functional groups;
Examples of the composition include a urea resin, a (block) polyisocyanate compound, and a crosslinking agent such as a carboxyl group-containing compound. The ratio between the base resin and the crosslinker is 50 to 90%, preferably 60 to 80%, and the crosslinker is 50 to 10%, particularly 40 to 20%, based on the total weight of the two components.
% Is suitable. As coloring pigments, titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chrome ero, chromium oxide, prussian bull, cobalt bull, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment And inorganic or organic pigments for solid color such as pigments, sullen pigments and perylene pigments; pigments such as aluminum, copper, mica, mica coated with metal oxides such as titanium oxide and iron oxide, and mica-like iron oxide. -Metallic pigments, but are not limited to these. By using one or more of these coloring pigments, the paint (A) for the inner plate can be finished in a solid color tone or a metallic tone, and the color tone matches the colored top coat on the outer plate portion. Or approximate. The organic solvent is for mixing and dispersing the resin composition and the color pigment, and may be a conventional coating solvent such as a hydrocarbon type, an ester type, an ether type, an alcohol type and a ketone type. The paint (A) for the inner plate can be prepared by mixing and dispersing a resin composition and a pigment in an organic solvent by an ordinary method, and has a solid content of 10 to 60% by weight and a viscosity of 10 to 10% at the time of coating. ~ 50 seconds (Ford cup # 4/20
° C), and the inner plate is coated with a cured coating film by an electrostatic method or a spray method so as to have a thickness of 5 to 40 µm. After leaving at room temperature for 1 to 20 minutes, if necessary, heating and curing at 100 to 180 ° C. for 10 to 40 minutes, then apply the intermediate coating (B) to the outer plate portion. [0013] The intermediate coating (B) is a coating applied to the outer panel of the vehicle body, and forms a colorless and transparent coating film. Specifically, a liquid paint containing a resin composition and an organic solvent, and forming a colorless transparent coating film substantially containing no color pigment is preferable, but the inner plate portion already coated on the inner plate portion is preferable. It is also possible to include a coloring pigment to such an extent that the color tone of the coating film of the coating composition (A) does not cause discomfort. As the resin composition, the coloring pigment and the organic solvent, those exemplified for the inner plate portion coating material (A) can be applied. The intermediate coating composition (B) can be prepared by mixing and dispersing the resin composition in an appropriate amount of a coloring pigment, if necessary, in an organic solvent according to a conventional method. The viscosity is adjusted to 60% by weight and the viscosity is adjusted to 10 to 50 seconds (for ford cup # 4/20 ° C.).
Paint to ~ 40μ. Leave at room temperature for 1-20 minutes, then at 10-160 ° C for 10-40
After heating and curing for a minute, a colored top coat (C) is applied to the outer plate. The outer plate portion coated with the intermediate coating material (B) is visually inspected on a surface to be coated (for example, an electrodeposition coated surface or a surface-treated plastic surface) through the coating film of the intermediate coating material (B). can do. Even when a part of the intermediate coating (B) is applied to the coating surface of the inner plate coating (A) in the form of spots or the like, since the coating is transparent, the coating is transparent. As a result, the coating surface of the coating material (A) can be easily visually observed, and the applied portion of the intermediate coating material (B) does not stand out, and the appearance does not deteriorate at all. Next, a colored top coat (C) is applied to the surface of the intermediate coat (B) on the outer panel. The colored top coat (C) is a paint for forming a coating film having a color tone to give an aesthetic effect to the outer plate portion, and includes a solid color tone or a metallic tone paint. Specifically, a thermosetting paint containing a resin composition, a color pigment and an organic solvent is suitable. As these resin compositions, coloring pigments (solid color pigments, metallic pigments) and organic solvents, those exemplified for the above-mentioned inner plate coating material (A) can be used. The colored top coat (C) can be prepared by mixing and dispersing the resin composition and the color pigment in an organic solvent by an ordinary method, and has a solid content of 10% at the time of coating.
６０60% by weight, viscosity for 10 to 50 seconds (Ford Cup #
(4/20 ° C), and the thickness of the cured coating film on the outer plate of the car body is 5 by the electrostatic method or the spray method.
Paint to ~ 40μ. This method is achieved by leaving the mixture to stand at room temperature for 1 to 20 minutes and then heating and curing at 100 to 160 ° C. for 10 to 40 minutes. Even if a part of the colored top coat (C) is applied to the coating surface of the inner plate portion paint (A) of the adjacent inner plate portion, the color tone of both paints is similar or coincident, so that it is conspicuous. And no deterioration in appearance. In the present method, the clear paint (D) is applied to the painted surface of the colored top coat (C) of the outer plate and the paint (B) of the inner plate of the inner plate which are coated as described above. be able to. The clear paint (D) is a paint that forms a colorless or colored transparent coating film. Through this coating film, the coated surface of the adjacent lower layer colored top coating material (C) and the inner plate portion coating material (B) is coated. You can see it. Specifically, a transparent coating film is formed by containing a resin composition and an organic solvent as essential components. As the resin composition and the organic solvent, those described for the inner plate portion coating material (A) are suitable. The solid content at the time of coating is 10 to 60% by weight, and the viscosity is 10 to 50 seconds.
Cup # 4/20 ° C), and cured or uncured colored top coat (C) and inner plate so that the thickness of the cured coating film is 5 to 40μ by electrostatic method or spray method. Paint on the painted surface of paint (A) for
After standing for 10 minutes, the mixture is cured by heating at 100 to 170 ° C. for 10 to 40 minutes. Since the intermediate coating (B) applied to the outer plate of the vehicle body forms a colorless and transparent coating film, a part of the inner coating is spot-like like spray dust. Even when it was applied to the coating surface of the coating (A) for the inner plate part of the part, it was hardly noticeable, and the color discomfort in the inner plate part could be eliminated. That is, the outer plate portion coated with the intermediate paint (B) is
Through the coating film, the surface to be coated (for example, an electrodeposition coated surface or a surface-treated plastic surface) can be seen, and a part thereof can be applied to the coating surface of an adjacent inner plate. Also, since it is transparent, the painted surface of the inner plate portion paint (A) can be easily seen, and there is almost no color difference between the portion and the color tone of the paint film of the inner plate portion paint (A). It was resolved. Examples of the present invention and comparative examples will be described below. Parts and percentages are based on weight, and the film thickness of the coating is for the cured coating. 1. Sample 1) Coated steel sheet (400 × 150 × 0.8 mm) with cationic electrodeposition paint (“ELECRON 9800” Kansai Paint Co., Ltd.)
(Trade name, polyamine-modified epoxy resin, block polyisocyanate) was applied and cured by heating. The upper part was assumed to be the outer plate part, and the lower part was assumed to be the inner plate part. 2) Paint for inner plate part (A) a): An organic solvent type intermediate paint of polyester resin (number average molecular weight 10,000, hydroxyl value 70, acid value 7) and butylated melamine resin. The color is white. A diluting solvent consisting of ethyl acetate / toluene = 50/50 (weight ratio) was used to adjust the solid content at the time of coating to 40% and the viscosity to 30 seconds (for ford cup # 4/20 ° C.). B): polyester resin (number average molecular weight 8
500, hydroxyl value 60, acid value 5). Butylated melamine resin organic solvent type intermediate coating. The color tone is silver metallic. A diluting solvent consisting of ethyl acetate / toluene = 50/50 (weight ratio) was adjusted to a coating solid content of 40% and a viscosity of 30 seconds (for ford cup # 4/20 ° C.). 3) Intermediate coating (B) a): A polyester resin (number average molecular weight 15,000, hydroxyl value 80, acid value 10) / butylated melamine resin organic solvent type intermediate coating. Contains no color pigments and is colorless and transparent. A diluting solvent consisting of ethyl acetate / toluene = 50/50 (weight ratio) was adjusted to a coating solid content of 40% and a viscosity of 30 seconds (for ford cup # 4/20 ° C.). B): polyester resin (number average molecular weight 1)
5000, hydroxyl value 80, acid value 10). Butylated melamine resin-based organic solvent type intermediate coating. The color is gray. Ethyl acetate / toluene = 50/50 (weight ratio) solvent, solid content at coating 40%, viscosity 3
It was adjusted to 0 seconds (for ford cup # 4/20 ° C). 4) Colored top coat (C) a): Acrylic resin containing hydroxyl group (number average molecular weight 1500)
0, hydroxyl value 50, acid value 4).
Melamine resin based telluride. The color is white. The solvent content of ethyl acetate / toluene = 50/50 (weight ratio) was adjusted so that the solid content at the time of coating was 40% and the viscosity was 30 seconds (for ford cup # 4/20 ° C.). B): Hydroxyl group-containing acrylic resin (number average molecular weight 15,000, hydroxyl value 50, acid value 4) / methyl / butyl mixed etherified melamine resin paint. The color is silver-metallic. The solvent content of ethyl acetate / toluene = 50/50 (weight ratio) was adjusted so that the solid content at the time of coating was 40% and the viscosity was 30 seconds (for ford cup # 4/20 ° C.). 5) Clear paint (D) a): Acrylic resin having hydroxyl group (number average molecular weight 1500)
0, hydroxyl value 50, acid value 4).
Melamine resin clear paint based on telluride. Ethyl acetate / toluene = 50/50 (weight ratio) solvent, solid content at coating 40%, viscosity 2
It was adjusted to 0 seconds (for ford cup # 4/20 ° C). 2. EXAMPLES AND COMPARATIVE EXAMPLES Paint (A) for the inner plate was spray-coated on the lower part of the object which was cationically electrodeposited and heat-cured, and was left at room temperature for 5 minutes. The intermediate coating (B) was spray-coated, left at room temperature for 5 minutes, and heated to cure both coatings. Then, only the upper part was spray-painted with the colored top coat (C) and left at room temperature for 5 minutes. Then, the clear paint (D) was spray-coated, left at room temperature for 5 minutes, and then heated. To cure both coatings. Table 1 shows the coating process and the performance of the obtained coating film. [Table 1] The coating film performance test method in Table 1 is as follows. Color discomfort: A paint (A) for the inner plate is applied to the lower part of the object to be coated, and an intermediate paint (B) is spray-coated on the upper part so as to be adjacent to the object, and then heated to heat the two coatings. Then, only the upper portion is spray-coated with a colored top coating (C) and a clear coating (D), and the coating is cured by heating to cure both coatings, in particular, the coating corresponding to the inner plate portion. The lower part of the coating was visually observed. ○ indicates that the application of the spray-dust of the intermediate coating (B) was observed, but was hardly confirmed visually, and there was no color discomfort at all. Δ indicates that the application of the spray-dust of the intermediate coating (B) was visually observed. X indicates that the application of the spray dust of the intermediate coating composition (B) can be visually confirmed, and the color has an unusual feeling. Water resistance: The coated plate was immersed in warm water of 40 ° C. for 10 days, dried at room temperature, and then cut with a cutter to make a cut line.
Make individual pieces and stick an adhesive cellophane tape on the surface.
The presence or absence of peeling of the coated film after abrupt peeling at a temperature of ° C was examined. ○ indicates that no peeling of the paint film was observed.

Claims (1)

Claims: 1. An inner plate portion of an automobile body is coated with an inner plate paint (A), and then an outer plate portion is coated with a middle coat paint (B) and a colored top coat (C). In the automobile painting method,
An automobile coating method, wherein the color tone of the paint (A) for the inner plate is the same or similar to that of the colored top coat (C), and the middle coat (B) is a paint that forms a colorless and transparent coating film.