JPH0367753B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an improvement on a two-color coating method used particularly for automobiles and the like.

In an automobile assembly factory, the painting process is performed in the following order: undercoating → baking drying → intermediate coating → baking drying → top coating → baking drying. In such a painting process, when the upper and lower halves of the car body are painted in different colors, for example, in the top coating process, the color of the upper half is applied to the entire car body, and then baked and dried.
Next, the above car body is taken out from the assembly line, the upper half of the car body is masked, the lower half is painted in color in a repair booth, the masking is removed and it is baked and dried in a repair oven, and then the above painting process is completed again. It was back on the assembly line.

However, since the top coat is baked and dried twice, a large amount of energy is used and costs are high. In addition, the lower half color is applied in the repair booth and repair furnace, but the repair booth and repair furnace are originally used to repair car bodies with paint defects, and therefore, the paint baking ability is small. , it was not possible to process a large amount of two-color painted car bodies, and furthermore, it was interfering with the original work of the repair booth and repair furnace.

The present invention solves the above-mentioned problems by applying a first top coat, which is a mixture of the same resin as the intermediate coat and a first color pigment, to the base-coated workpiece in a wet-on-wet manner after applying the base coat. The present invention relates to a two-color coating method characterized in that the coating material is baked and dried, and then a second top coat is applied to a part of the object to be coated, and the article is baked and dried. Therefore, the first top coat is baked and dried at the same time as the intermediate coat, and compared to the conventional method in which only the first top coat is baked and dried independently, the number of baking times is reduced by one, resulting in energy savings and cost reduction. Furthermore, there is no need to provide an independent baking oven for baking the first top coat, resulting in space savings and equipment cost reductions.

The essential element of the present invention is that the first top coat, which is the same resin as the intermediate coat mixed with the first color pigment, is applied wet-on-wet to the base-coated surface. Even if the two paints are mixed and an inversion occurs, both paints are the same, so
The paints have good adhesion to each other, and when applied to a vehicle body, the effect is that a vehicle body having a painted surface without roughness can be obtained.

Hereinafter, one embodiment of the present invention will be specifically described.

The car body formed by welding is pretreated, and then an undercoat is electrodeposited onto the car body in an electrodeposition tank to provide an undercoat, and then the undercoat is baked and dried in an undercoat baking oven. Next, at the intermediate coating booth, an intermediate coating of oil-free polyester resin with gray pigment is sprayed on the car body under the following conditions.

Intermediate coating conditions Paint viscosity: 17 seconds (FC#4, 20℃) Coating film thickness: 25 to 35μ Next, pigments of the color of the lower half of the car body were mixed with oil-free polyester resin on the entire car body under the following conditions. The first top coat is applied with a spray gun in the intermediate coat booth.

The reason why the resin in the intermediate coat and the first top coat are the same is that when both paints are applied wet-on-wet, they mix and a reversal occurs, but even if this reversal occurs, both paints are the same. Therefore, there is no so-called rough skin, the paints have good adhesion to each other, and the finished appearance does not deteriorate. Furthermore, since the oil-free polyester resin used as the intermediate coating has good weather resistance, it is suitable as an exterior coating for a finished vehicle.

First top coat coating conditions Paint viscosity: 25 to 30 seconds (FC#4, 20℃) Coating film thickness: 25 to 30μ Next, the car body with the above intermediate coat and first top coat was heated to 150℃ in an intermediate coating baking oven. , baked dry for 20 minutes.

Here, after masking the lower half of the car body in the storage line between the intermediate coating furnace and the top coating booth,
A second top coat, which is a mixture of melamine alkyd resin and a pigment of the color of the top half of the car body, is applied to the top half of the car body in a top coat booth under the following conditions.

2nd top coat coating conditions Paint viscosity: 25-30 seconds (FC#4, 20℃) Coating film thickness: 30-35μ Next, peel off in the masking topcoat booth and bake for 20 minutes at 150℃ in a topcoat baking oven. dry,
A two-color car body is completed, with the lower half painted with the first top coat and the upper half painted with the second top coat, and this car body is sent to the outfitting process.

Therefore, the first top coat is baked in the intermediate coating drying oven at the same time as the intermediate coating, and both coatings are applied in the intermediate coating booth, improving work efficiency. In addition, two top and bottom coats can be applied in the intermediate coating booth, intermediate coating baking furnace, top coating booth, and top coating baking oven, which do not interfere with the work on the repeller line. This can be done in the same order as the main body.

In the above embodiments, the first top coat paint is applied to the entire vehicle body, but it may be applied only to the lower half of the vehicle body.

When applying a metallic color to a vehicle body, a metallic paint is used as the first and second top coats, and after the second top coat is applied, a clear lacquer is applied and then baked and dried in a top coat baking oven.

Further, in the case of a high quality solid color, after applying the second top coat, a clear lacquer is applied and baked and dried in a top coat baking oven.

Claims (1)

[Claims] 1 After applying the base coat, apply a first top coat, which is a mixture of the same resin as the intermediate coat and a pigment of the first color, to the base coated object using a wet-on-wet method, bake it to dry, and then apply the first top coat to the base coat. A two-color painting method characterized by applying a second top coat to a portion of the object to be painted and baking and drying it.