JPS59160572A - Local chip resistance painting film of car body of automobile - Google Patents

Abstract

PURPOSE:To improve a chip resistance by placing a power or a painting film by a slurry painting between an electrodeposition painting film and an intermediate painting film. CONSTITUTION:A body which is degreased and chemically treated is brought to an electrodeposition painting, and therefore, washed with water, and by utilizing a small space before reaching a baking furnace, a powder paint or a slurry paint is blown to the hood tip and the front end panel so that a film thickness 8 after heating and hardening becomes 100-200mu. Thereafter, an intermediate painting film 9 and a finished painting film 10 are formed. In this way, the smoothness and chipping resistance are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a localized chip-resistant coating film for parts of an automobile body where chip-resistant performance is required.

While the car is running, pebbles and gravel from the road bounce off the car body and damage the paint film. Chip-resistant paint has been used for balance panels, rocker panels, etc.

The chip-resistant paint used is, for example, a polyvinyl chloride plastisol with calcium carbonate added thereto, or a two-component polyurethane, which has high viscosity and can easily form a thick coating. However, the tip of the slant-nose type hood shown in Figure 1, the front end panel 2, the quarters, and the lower part of the doors are easily hit by pebbles and gravel thrown by the vehicle in front, resulting in significant chipping damage. On the other hand, since smoothness is important for the coating film in such areas, it is not possible to use the above-mentioned chip-resistant paints, so we have no choice but to use intermediate coatings.
There is a problem in that it is difficult to obtain a smooth coating even if covered with a top coat.

On the other hand, with existing automotive coating systems that mainly use solvent-based paints, it is not possible to obtain a coating film with a thickness of more than 50 μm due to problems with sagging and undercoating, and it is impossible to apply a coating thick enough to satisfy chip resistance.

The object of the present invention is to provide a localized chip-resistant coating film having a structure that can improve chip resistance without damaging the appearance of the slant nose portion of an automobile body.

That is, the local chip-resistant coating film of the present invention is applied on the base material of the object to be coated.
Electrodeposition coatings, thermosetting coatings made of powder or slurry paints, intermediate coatings, and top coatings, which are not coated in this order, and thermosetting coatings made from the above powder or slurry paints. is 100
It is characterized by having a thickness of 200 μm to 200 μm.

Automobile bodies manufactured at auto body shops are subjected to normal degreasing and chemical conversion treatment, and are then electrocoated with an undercoat of, for example, cationic epoxy resin paint, followed by sealer application, rust prevention treatment, and soundproofing treatment, followed by polyester undercoat paint. can be sprayed onto the outer panel surface. Next, spray a polyester resin topcoat paint in a similar body color to the interior of the second engine compartment, trunk compartment, and fuel inlet, and let it dry. After that, the surface of the body is wet-sanded to complete the pre-painting treatment.
Start painting the top coat in the paint booth.

The coating film of the present invention is obtained by spraying a thermosetting resin powder coating or slurry coating between the electrodeposition coating and the intermediate coating, and then heating and curing the coating. The thickness is 100 to 200 μ, preferably 10 to 15
It is 0μ. If it is less than 100μ, the chip resistance is insufficient, and if it is more than 200μ, there is a limit in terms of adhesion and efficiency.

The cationic resin aqueous solution used to form the coating film of the present invention is not particularly limited, but includes epoxy resins, aminoacrylic resins,
An aqueous solution obtained by partially neutralizing a basic synthetic resin such as a polyamide resin with an acidic compound such as lactic acid, propionic acid, formic acid, or acetic acid is suitable. Thermosetting powder coatings are mixtures of epoxy, polyester, polyurethane, and epoxy-acrylic resins and curing agents that can be used as general powder coatings, and various additives may be added as necessary. can be added.

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment FIG. 1 shows the process of obtaining the coating film of the present invention, in which a body that has been degreased and chemically treated is electrodeposited in an electrodeposition bath 3. The electrodeposition paint is prepared as follows.

Sokuchi, 100 parts of epoxy resin, 15 parts of jetanolamine
1 part and 30 parts of isopropylamine were reacted at 80'C for 5 hours under reflux to obtain a liquid aminoepochine resin. Next, this resin liquid is neutralized with glacial acetic acid, and deionized water is added to prepare a cationic resin aqueous solution having a solid content of 20 inches.

After electrodeposition coating, it is washed with water and, conventionally, it is immediately baked and hardened through a baking oven 4, but in order to obtain the coating film of the present invention, the powder is Paint 5 or slurry paint is sprayed onto the hood tip 1 and front end panel 2 so that the film thickness after heating and curing is 100 to 200 μm. An example of the composition of the powder coating 5 is as follows.

Polyester resin 20 parts Epoxy resin 80〃 Surface conditioner 1〃 Titanium oxide 50〃 Carbon black 1〃 Next, keep it at 180 to 200° for 20 minutes in baking oven 4, and apply uncured electrodeposition coating to the above-mentioned painted area. The area is heated and cured at the same time, and then the predetermined intermediate coating and top coating processes are carried out. In addition, when applying powder or slurry coating to an area to be painted, spray heated air only on that area and drain the water to avoid foaming in the coating to avoid the effects of moisture adhering to the body during electrodeposition. Can be done.

The coating film thus obtained is coated on the base material 6 as shown in FIG.
It is composed of an electrodeposition coating film 7, a powder coating film 8, an intermediate coating film 9, and a top coating film 10, with a total coating thickness of 150 to 250.
It has a film thickness of μ, and is smooth, and the film thickness changes continuously as shown in FIG. 2, and there are no visible defects such as unevenness. Further, as a result of testing the chip resistance by varying the thickness of the powder coating film 8, results were shown to be superior to conventional chip resistant paints within the scope of the present invention. Next, the test method and results are shown.

■ Gravelo test After spraying 1 kg of crushed granite particles with an outer diameter of approximately 3 to 521111+ onto 100 d of the top-coated painted surface using air at a pressure of 5% (P), a salt water spray test was conducted for 240 hours. The rust condition is indicated by the rating number.

■ Nut test A painted panel that had been immersed in hot water for 240 hours and deteriorated was tilted at an angle of approximately 45 degrees, and then the nuts were continuously dropped from a height of approximately 1.5 m. show.

*Based on Nirating NOASTM standard.

"10" indicates that there is no scratch on the base material and no rust.

As mentioned above, the coating film of the present invention has both smoothness and chipping resistance by sandwiching a powder or slurry coating between the electrodeposition coating and the intermediate coating. It is possible to use the small space between the electrodeposition coating equipment and the intermediate coating equipment without making major changes to the existing painting line, thereby minimizing painting equipment and costs. Since it is sufficient, the effect of improving the quality of the product is large.

[Brief explanation of drawings]

FIG. 1 shows a process diagram for obtaining the coating film of the present invention, FIG. 2 represents a cross-sectional view of the coating film of the present invention. In the figure,

Claims (1)

[Claims] The above-mentioned powder or slurry paint is coated on the base material of the object to be coated in the following order: electrodeposition coating, thermosetting coating of powder or slurry coating, intermediate coating, and top coating. A local chip-resistant coating film for an automobile body, characterized in that the thermosetting coating film has a thickness of 100 to 200μ.