JPH01139177A - Method for coating car body - Google Patents

Abstract

PURPOSE:To obviate lack of hiding even when the external plating is painted in a low-hiding color and a partial coating film has a dark color by applying partial coating before intermediate coating, and hiding the periphery of the overlap with an intermediate and a top coating film. CONSTITUTION:In the coating of a car body including partial black coating, etc., a polyester-melamine based black paint 3 is applied on the sash and pillar parts on the surface of the external plating 1, baked, and cured. The parts are then masked with paper, etc., and the polyester-melamine based intermediate coat 4 added with a thickner such as a stearate is applied on the whole surface of the plating 1. The polyester-melamine based top coat 5 added with the same thickner is applied thereon on a wet-on-wet basis, and both coats are simultaneously baked. As a result, lack of hiding is not caused even on the overlap of the black paint and the low-hiding paint, and a car body is coated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of painting a vehicle body, and more particularly to a method of painting an outer panel of a vehicle body, including partial black painting.

[Conventional technology]

BACKGROUND ART In recent years, in the painting of automobile bodies, a method of partially applying black coating to sunshades, pillars, etc. has been adopted due to design requirements (see, for example, Japanese Patent Laid-Open No. 60-48171). The most typical car body painting process including such partial painting will now be described with reference to FIGS. 4 and 5. First, an undercoat film 2 is formed on the surface of an automobile body outer panel l by electrodeposition coating, etc., and after baking and hardening, an intermediate coat film 4 is formed on the undercoat film 2, and this intermediate coat film 4 is coated wet-on-wet on parts to be coated with black, such as sachets and pillars, without drying, and this black coating film 3 is baked and cured at the same time as the intermediate coating film 4. after that,
Masking the black painted part using a masking material,
Next, a top coat film 5 is formed on the entire outer panel 1 of the vehicle body, and after hardening by baking, the masking material is removed to complete the painting.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional method, when the topcoat film, which is the color of the exterior panel, is a clear, bright, low-hidden color such as super color, the paint film cannot be used! J! However, there was a problem in that the paint could not be sufficiently concealed, and the area around the black painted part (8 in FIG. 5) was scratched, resulting in an extremely poor appearance. Such deterioration in appearance is a fatal problem for painting exterior panels of vehicle bodies, and there is an increasing need for improvement measures.

The present invention has been made in consideration of these problems, and its purpose is to prevent the occurrence of sedges, etc. on parts of the satchel and pillar of a car body that uses a low-concealing color for the outer panel color. To provide a coating method for applying dark color coating such as black coating.

[Means for solving problems]

The method for painting a car body of the present invention includes forming an undercoat film on the surface of the outer panel of the car body and curing it by baking, forming a paint film on a partially painted area of the surface of the undercoat film and curing it by baking, Next, the partial painting area is masked, an intermediate coat containing a thickener is applied to the surface of the undercoat, and a top coat containing a thickener is further applied wet-on-wet. , the intermediate coating film and the top coating film are baked and hardened.

The formation of the undercoat film in the present invention is carried out, for example, by degreasing the surface of the outer panel of the vehicle body, subjecting it to chemical conversion treatment, and then performing electrodeposition coating.

Further, all bake hardening in the present invention is carried out by a conventional method, for example, at 140 to 180°C for 10 to 30 minutes.

Furthermore, partial coating on the surface of the undercoat film is carried out, for example, on the sash and pillar parts, and at this time, dark-colored paints such as polyester-melamine black paints can also be used.

Masking of the partially painted area is performed using a conventional masking material such as paper, aluminum foil, or tape.

In addition, the formation of an intermediate coating film and a top coating film is carried out by forming an intermediate coating film and a top coating film each containing a thickener such as bentonite, stearate, acrylate, alginate, methylcellulose, gum tragacanth, etc., such as polyester-melamine. This is done by applying a wet-on-wet paint system.

Furthermore, in the method of the present invention, performing undercoat painting, sealer painting, and asphalt laying, which are performed between the undercoating process and intermediate coating process in the usual three-coat painting method for car bodies, and special painting after the topcoating process,
This is the preferred method.

[Effect]

In the car body painting method of the present invention, partial painting is performed before the intermediate coating, so that the peripheral area of the partial coating where the partial coating and the top coating overlap, is coated with the intermediate coating. and is hidden by the top coat. Therefore, even if the exterior color is a low-hidden color such as a super color and the partial coating is a dark coating such as a black coating, there will be no scaling in the overlapped area between the partial coating and the top coat. etc. will not occur.

In addition, since a thickener is added to the intermediate and top coats, coating defects such as sagging and flaking do not occur even when these are applied wet-on-wet.

〔Example〕

Next, the present invention will be explained based on Examples, but the present invention is not limited thereto.

1 to 3 relate to one embodiment of the present invention, and will be described below with reference to these.

First, the outer panel 1 of the vehicle body is immersed in a weak alkaline degreaser, and the degreaser is sprayed onto the outer panel 1 to remove dirt and rust preventive from the surface of the outer panel 1.

Next, after being immersed in a zinc phosphate treatment agent and subjected to a chemical conversion treatment, a conventional electrodeposition coating was applied, and this was baked and cured in a drying oven at 180°C for 20 minutes to form an undercoat film with a thickness of about 15 μm. form 2.

Next, polyester-melamine black paint (Kansai Paints TP-37) was applied to a thickness of 20 μm on the sash 6 and pillar 7 portions on the surface of the outer panel 1 and their surroundings, and baked and cured at 140°C for 20 minutes. do.

Next, the sachet 6 and pillar 7 portions are masked with a masking agent or the like.

Then, a polyester-melamine intermediate coating (gray, TP-37 modified by Kansai Paint Co., Ltd.) containing a thickener such as stearate is applied to the entire surface of the outer panel 1 to a thickness of 20 μm.

Next, wet-on-wet polyester-melamine topcoat paint (Super Red, Kansai Paint Co., Ltd. TM-13RC) with the same thickener added as above was applied.
) to a thickness of 30 μm.

Thereafter, the intermediate coating film 4 and the top coating film 5 are baked and cured at the same time under conditions of 140 DEG C. Cl2O for minutes.

Then, when the masking material is removed, the coating on the vehicle body outer panel l, in which only the sash 6 and the pillar 7 are partially painted black, is completed.

The compositions of the black paint, intermediate coat paint, and top coat paint used in the above steps are shown in the table below.

Table Composition of each paint (% by weight) The parts of the paint film thus formed that have been painted black are shown in Figure 2. Undercoat paint film 2 consisting of a chemical conversion treatment layer and an electrodeposition coating layer on the outer panel l. is formed thereon, and a black coating film 3 is partially formed thereon, and an intermediate coating film 4 and a top coating film 5 are formed on the other parts.

In the painting performed by the above process, no paint defects such as scratches occurred in the black painted peripheral area 8, even though the outer panel color was a super color. In addition, in this method, the intermediate coating and top coating are performed wet-on-wet, and as a result, there were no defects such as sagging or undercoat, which normally occur.

〔Effect of the invention〕

As explained in detail above, the car body painting method of the present invention can be applied even when a black paint and a paint with poor concealment properties are overlaid.
This makes it possible to paint without causing scratches. For this reason, it is possible to use super colors, which have been in increasing demand as exterior paint colors in recent years, in combination with partial black paint.

Furthermore, since this method can be carried out using conventional coating equipment, the above-mentioned effects can be obtained without requiring any special equipment.

[Brief explanation of the drawing]

Fig. 1 is a process diagram of a car body painting method according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of a coating film obtained in an embodiment of the present invention, and Fig. 3 is a process diagram of a method of painting a car body according to an embodiment of the present invention. A perspective view of the outer skin of the car body used, Figure 4 is a process diagram of the conventional car body painting method, and Figure 5 is
1 is a cross-sectional view of a coating film obtained by a conventional car body coating method. In the diagram, 1... Vehicle body outer panel 2... Undercoat film 3...
・Black paint film 4...Intermediate coating film 5...Top coating film 6...Sun Chef...Pillar Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] An undercoat film is formed on the surface of the outer panel of the vehicle body and cured by baking, a paint film is formed on the partially painted areas on the surface of the undercoat film and this is baked hardened, and then the partially painted areas are masked. Then, an intermediate coating containing a thickener is applied to the surface of the undercoat, and a topcoat containing a thickener is further applied wet-on-wet, and then the intermediate coating and the topcoat are applied. A car body painting method characterized by baking and hardening a film.