JPS63178878A - Two-tone coating method - Google Patents

Abstract

PURPOSE:To rationalize the coating process by carrying out overcoating for two tones in an intermediate coating booth, baking the coating, carrying out overcoating in an overcoating booth, and baking the coating. CONSTITUTION:After an automobile body is subjected to chemical conversion treatment A, the body is electrodeposited B, and the electrodeposited film is baked and dried P. The overcoating C for two tones is carried out in the intermediate coating booth with the use of epoxy-modified oil-free polyester melamine resin, etc., and the coated film is baked (q). The overcoating D is successively applied in the overcoating booth with the use of alkyd melamine resin, etc., and the coated film is baked (r). Since the overcoating paint imparted with an intermediate paint function is coated in the intermediate coating stage in this method, only one-time overcoating booth baking is applied in this method as compared with the conventional two-times overcoating booth baking, hence the coating process is remarkably rationalized, the productivity can be improved by approx two times as compared with the conventional method, and the heat energy and paint can be saved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a two-tone painting method, and more particularly to a two-tone painting method for creating a two-tone automobile.

(Prior art) Conventionally, for example, when painting a so-called two-tone car in which the upper and lower parts of the car body surface are painted in different colors, the paint surface of the entire car body was first subjected to chemical conversion treatment A, as shown in Figure 1. After that, apply electrodeposition coating B and baking treatment a, then apply intermediate coating C and baking treatment, apply the first top coat D to either the upper or lower part of the car body, and then bake this. It is common to apply treatment C, apply a second topcoat E, and paint the rest of the car body in a color different from the first treatment, and then apply baking treatment d (for example, 57-48
(See Publication No. 273).

(Problems to be Solved by the Invention) In the conventional method as described above, there is only one painting booth and baking oven for topcoating and baking.
When applying the second top coat and baking, the product had to go through the same coating booth and baking oven again, which reduced production capacity and required a large number of steps.

Moreover, the consumption of heat energy and paint is large, which is not desirable from the viewpoint of energy saving.

(Means for solving the problem) The present invention aims to solve the problems in the conventional painting method for two-tone specification cars as described above. After carrying out electrodeposition coating (n) and baking treatment (p), two-tone topcoat (II) is applied without intermediate coating (C) in the intermediate coating booth.
), then baked (q), then applied in the topcoat booth (■), baked (r) and applied two-tone coating, making it possible to apply two-tone paint to the conventional topcoat booth and baking furnace. By applying a topcoat that has the function of an intermediate coating in the intermediate coating process, the number of intermediate coatings is reduced, and the number of final coating booths and baking ovens is reduced to one.
This makes it possible to create a two-tone specification car by recirculating the code.

In the present invention, the two-tone top coat in step (1) is applied only to solid and solid colors, and conventional methods are applied to metallic colors.

The two-tone top coat used in the present invention is a paint whose resin composition has been changed in order to impart the function of an intermediate coat to a conventional top coat.For example, the conventional top coat has an alkyd melamine resin, The secondary intermediate coating is an epoxy-modified alkyd melamine resin, while the two-tone top coating may be an epoxy-modified oil-free polyester melamine resin or a urethane-epoxy-modified alkyd melamine resin.

In the method of the present invention, coating conditions such as coating viscosity, diluting solvent, film thickness, and coating interval are also important points, and an example thereof is shown below.

The present invention will be explained in more detail with reference to Examples below.

(Example) After the usual degreasing and chemical conversion treatment of an automobile body manufactured at a car body factory, the pre-painting treatment was completed by applying an undercoat electrodeposition coating with an epoxy resin-based methion electrodeposition paint and baking it to dry.

After applying sealer, rust prevention treatment, and soundproofing treatment, clean with white gasoline etc. at the entrance of the intermediate coating booth. Paint) is applied using equipment such as an electrostatic atomizer or a rotary atomizer to achieve a film thickness of 35 to 40 μm after baking and drying.
After about 10 minutes, dry in a drying oven for 14 hours.
Baking and drying was performed at 0° C. for 20 minutes to complete the two-tone top coat.

Masking of the topcoat for the tool was performed in front of the topcoat booth using polyester tape, die cut tape, and laminated paper.

Using the coating equipment described above, an alkyd melamine resin-based or acrylic melamine resin-based paint (top coat) was sprayed so that the film thickness after baking and drying was 40 to 50 μm.

After about 10 minutes, it was baked and dried in a drying oven at 140°C for 20 minutes, and the previous masking was removed to complete the two-tone coating.

(Effect of the invention) In a two-tone specification vehicle that requires topcoating in two different colors as described above, the present invention applies a topcoat that has the function of an intermediate coating in the intermediate coating process. By adopting this method, compared to the conventional topcoating booth baking process, which is carried out twice, the present invention only requires the topcoating booth baking to be carried out once. The paint film performance has been significantly improved by almost twice as much, and the baking process is reduced by one compared to the conventional method, which saves thermal energy and paint, resulting in cost reductions. Coupled with the fact that this method is completely comparable to that of the above method, its industrial value is extremely great.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional two-tone painting process, and FIG. 2 is a block diagram showing an example of a two-tone painting process according to the present invention.

Claims (1)

[Claims] In two-tone painting, a two-tone top coat is applied and baked in an intermediate coating booth, and then a top coat is applied in a top coat booth and then baked.