JP2849012B2 - Painting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method used for finishing a design of an automobile.

[0002]

2. Description of the Related Art In recent years, high-design paints containing mica-based pigments and the like have been increasingly used for coating outer panels of passenger cars. This coating differs from a conventional metallic coating containing aluminum flakes in that it provides a pearlescent luster unique to mica pigments and an interference color such as iridescence due to light interference, giving a unique sense of depth.

[0003] Incidentally, mica-based paints containing mica-based pigments have a disadvantage that they are inferior in hiding properties. Therefore, when the mica base paint is applied with a normal film thickness, the undercoat is seen through, so that the color tone of the undercoat is revealed and the paint does not have a high design. Therefore, conventionally, a color base paint having a similar color to the base is first applied, and then a mica base paint is applied thereon. A clear paint is further applied to protect the mica-based coating film.

[0004] The conventional high-design automotive coating process will be described in order. First, a steel sheet of a chemical conversion-treated automobile is first subjected to electrodeposition coating with an electrodeposition paint and baked and dried to form an electrodeposition coating film. You. Next, an intermediate coating such as an alkyd-melamine system is applied and baked and dried to form an intermediate coating film. After the intermediate coating film is subjected to water polishing, a color base coating material such as an alkyd-melamine type or an acryl-melamine type is applied and baked and dried to form a color base coating film. Then, a mica-based paint such as an acrylic-melamine-based paint and a clear paint of the same type as the mica-based paint are applied wet-on-wet, respectively, and are baked and dried integrally.

[0005]

By the way, a mica-based paint only needs to have a function of simply retaining a mica-based pigment, whereas a clear paint has various excellent coating properties such as scratch resistance, gloss and weather resistance. Film performance is required. However, in the conventional coating process, the mica base paint and the clear paint are applied wet-on-wet, so if the compatibility between the mica base paint and the clear paint is poor, the gloss of the obtained coating film will be defective. May occur. Therefore, the first condition is that the mica base paint and the clear paint have good compatibility. For this reason, the selection of materials is greatly restricted, and the degree of freedom of design is reduced. As a result, there is a case where the mica base paint becomes excessively quality or the improvement of the quality of the clear paint is restricted.

Further, since the mica base paint is applied to a dried color base coating film, dripping occurs when applied to a thick film. Therefore, it cannot be applied to a certain film thickness or more, and the improvement in the orientation of the mica-based pigment due to volume shrinkage is small, so that further improvement in flip-flop property cannot be expected. On the other hand, since the clear coating is applied to the mica-based wet coating, there is also a problem that the surface of the clear coating is wavy and the leveling property is not so good.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and alleviates restrictions on the selection of materials for a mica base paint and a clear paint, increases the degree of freedom in design, and further improves the finish. With the goal.

[0008]

According to the present invention, there is provided a coating method comprising: a first coating step of applying a baking type color base paint to form a wet color coating; A baking-type base paint containing a resin different from the resin component of the color base paint as a main component to form a wet base coating film.
A coating step, a first drying step of simultaneously baking and drying the wet color coating and the wet base coating to form a base coating, and a first drying step of applying a clear coating to the base coating surface to form a wet clear coating. 3 coating process, and a second drying process of drying the wet clear coating film to form a clear coating film,
It is characterized by consisting of.

The brilliant material refers to a mica-based pigment or an aluminum flake pigment, and a base paint containing the brilliant material generally has a low concealing property. The greatest feature of the present invention is that the color base paint and the base paint are applied wet-on-wet, baked and cured, and then a clear paint is applied. As a result, the blending of the base paint and the clear paint can be independently designed as described later, so that the degree of freedom in design is greatly increased.

[0010]

According to the coating method of the present invention, the color base paint and the base paint are applied wet-on-wet, and are integrally baked and cured. The purpose of the color base paint is simply coloring, and the purpose of the base paint is to retain the glittering material. Therefore, neither of them requires the same performance as the clear paint, and the compatibility with the clear paint does not matter. Further, even if the compatibility between the color base paint and the base paint is poor and the gloss or the like of the obtained base coat is inferior, no problem occurs because a clear coat is formed on the surface. Therefore, selection of materials for the color base paint and the base paint is not so limited as in the case of the conventional base paint and the clear paint, and there is a relatively high degree of design freedom. Further, with regard to the clear paint, since the restrictions such as compatibility with the mica-based paint are released, the degree of freedom in design becomes extremely large.

Further, the resin component of the base paint is a resin different from the resin component of the color base paint. Therefore, when the base paint is applied to the surface of the wet color coating film in a wet-on-wet manner, the base paint is prevented from being mixed with the wet color coating film and the color is prevented from being mixed into the wet base coating film. As a result, the color component and the brilliant component have independent functions, and the sharpness of the obtained base coating film is not impaired.

The mica base paint is applied to the surface of a wet color coating film in a wet state. At this time, when the coating particles of the mica base paint adhere to the surface of the wet color coating film, the solvent usually transfers from the coating particles of the mica base coating to the wet color coating film due to the difference in the concentration of the contained solvent. Therefore, the viscosity of the mica-based coating particles increases instantaneously, and the viscosity of the applied wet base coating film becomes higher than before, so that it is possible to apply a thicker film than before. . When the wet base coating film becomes thick as described above, the volume shrinkage at the time of baking increases, and the orientation of the brilliant contained therein improves. Thereby, the glitter and flip-flop property of the mica base coating film obtained are increased, and the design can be further enhanced.

Since the clear coating is applied to the surface of the cured base coating, the original leveling property of the clear coating is exhibited without any adverse effect by the base coating, and the surface of the clear coating is extremely smooth.

[0014]

The present invention will be specifically described below with reference to examples. (Example) First, a test plate which had been coated with an intermediate coating film and subjected to water polishing was prepared. Further, a color base paint, a mica base paint and a clear paint shown in the table were prepared.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3] Using a “μμ Bell electrostatic coating machine” (manufactured by Ransberg),
Apply the color base paint on the surface of the test plate with a dry film thickness of 3
It was applied so as to have a thickness of 0 to 35 μm.

After a flash time of 5 minutes, the mica-based paint is applied to the surface of the wet base coating film to a dry film thickness of 15 to 20 μm using a “REA electrostatic coating machine” (manufactured by Ransburg). Was applied. Thereafter, a setting time was taken for 10 minutes, and baked and dried at 140 ° C. for 30 minutes in a drying oven for overcoating to integrally form a color base coating film and a mica base coating film.

After the test plate has cooled to room temperature, the above clear paint is applied to the surface of the mica-based coating film using a “μμ Bell electrostatic coating machine” (manufactured by Ransburg) so that the dry film thickness becomes 30 to 35 μm. did. And set time 10
And dried in a drying oven for overcoating at 140 ° C. for 30 minutes to form a clear coating film. (Conventional example) Using the above three types of paints, the following paints were applied. First, a color base paint was applied in the same manner as in the above example, and after setting time was set for 10 minutes, baking and drying were performed at 140 ° C. for 30 minutes in a drying oven for overcoating to form a color base coating film.

Next, after the test plate was cooled down to room temperature, a mica-based paint was applied to the surface of the color base coating film in the same manner as in the example, and a flash time of 5 minutes was taken. It was applied to the surface of the coating film. Then, a setting time was taken for 10 minutes, and baked and dried at 140 ° C. for 30 minutes in a drying oven for overcoating to form a mica base coating film and a clear coating film integrally. (Evaluation) The finished appearance and the flip-flop feeling of the coated plates obtained in the examples and the conventional examples were visually judged, and the results are shown in Table 4.

From Table 4, it can be seen that the coated plates obtained in the examples are excellent in smoothness and glossiness, strong in flip-flop feeling, and exhibit high design properties. This is apparently due to the application of the clear paint after the color-based paint and the mica-based paint were applied wet-on-wet and baked. In addition, normal coating film property tests such as water resistance, pencil hardness, adhesion, and weather resistance were also performed, but no difference was found between the coating films of the examples and the conventional example.

[0022]

[Table 4]

[0023]

According to the coating method of the present invention, the design can be improved with the same man-hour as in the prior art. In addition, the degree of freedom in designing the composition of each coating material is increased, and it is possible to obtain an optimum composition without the need for excessive quality as in the related art. Thereby, cost can be reduced.

Further, curing and drying can be carried out by using the overcoat drying oven twice as in the conventional case. Therefore, there is no increase in man-hours, and there is no problem that dust or the like adheres to the painted surface during drying.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B05D 7/14 B05D 1/38 B05D 5/06 101

Claims (1)

(57) [Claims] 1. A first coating step of applying a baking-type color base paint to form a wet color coating, and comprising a glittering material on the surface of the wet color coating and a resin different from the resin component of the color base coating. A second coating step of applying a baking type base coating material as a component to form a wet base coating film; and a first drying step of simultaneously baking and drying the wet color coating film and the wet base coating film to form a base coating film. A third coating step of applying a clear coating on the surface of the base coating film to form a wet clear coating film; and drying the wet clear coating film to form a clear coating film.
A drying step.