JPH0463174A - Coating method - Google Patents

Abstract

PURPOSE:To save the space and to reduce the cost of equipment by applying a first paint and then forcedly drying the overlapping region of the coating film of the first paint and a second paint to be applied before the second paint is applied. CONSTITUTION:The tips of the automobile body 2, hood and roof, pillar, fender, lower part of the door, etc., are firstly coated with a soft chip paint. The soft chip coating film at the region to be overlapped with a hard chip paint to be applied is forcedly dried. After the forced drying, the skirt, side sill, lower part of the door, wheel apron, floor, etc., of the automobile are coated with a hard chip paint. Accordingly, a soft chip coating part 3 and a hard chip coating part 4 are provided in a lone in the traveling direction of the automobile 2 in a coating station 1, a drier 5 is furnished between the coating parts 3 and 4, and the automobile 2 placed on a truck 6 is successively passed through the coating parts.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a method for coating an exterior panel with two types of paints having different properties in a state in which the coating films formed by these paints partially overlap. Regarding.

(Prior art) For example, in a vehicle such as an automobile, the outer panel of the vehicle body is coated with an undercoat,
It is common for vehicles to have multiple layers of paint such as intermediate and top coats, but vehicles with this type of paint are susceptible to collisions with foreign objects such as flying stones thrown up by own troops or other vehicles while driving. The impact may cause the paint film to peel off.

For this reason, for example, Japanese Patent Application Laid-open No. 58-180269 discloses that after obtaining an undercoat film with an electrodeposition primer, an intermediate coat is applied, and the intermediate coat film on the outer panel is coated with black impact Mf# protection. A technique for applying paint is disclosed. According to this, even if the above-mentioned flying stones or the like collide with the outer panel part, the impact can be absorbed by the impact buffering protection paint and the peeling of the paint film can be prevented.

In addition, in recent years, after electro-deposition coating, hard chip paints have been used to repair strong chip areas that are prone to collisions with flying stones, such as the lower side of the outer panels of the car body, by using hard chip paints that have the property of absorbing the impact acting on the chain parts mainly through the thickness of the coating. This is a chip-resistant coating that uses a soft-chip paint that absorbs collision energy to coat the weak-chip areas on the general surface of the exterior panel, where collisions are relatively rare.
Painting (peel-resistant paint) is being adopted.

(Problem to be Solved by the Invention) By the way, in the above-mentioned chipping-resistant coating, hard chip paint and soft chip paint are used depending on each part of the outer panel of the car body according to the properties of these paints.
As mentioned above, in areas where the parts painted with the Barttip 7P paint and the parts painted with the Soft Chip paint are adjacent to each other, both paints are applied overlappingly. For example, when hard chip paint is applied to the lower side of the outer panel of a vehicle, the general surface of the outer panel is coated with soft chip paint, so as shown in Figure 5, the soft chip paint film A formed by soft chip paint a is Then, the hard chip coating film B formed by the hard chip paint is overlapped thickly. The level difference caused by the overlap appears as a paint separation line C on the outer surface of the vehicle body.

However, in this way, the two types of paint are oat (- When wrapping, the properties of these two types of paint are different, so 1- Soft-chip painting and 1- Tochien-pu painting are applied consecutively at the same station.) Therefore, after applying the soft chip paint a, the car body must be placed in a furnace to remove the burn-in, and then the hard chip paint must be applied on top of that.)

Or, conversely, after hard chip painting, the car body is baked and treated, and then soft chip painting is applied.

This is because the coating film A formed by soft chip coating
If it is not baked on, it will be in a semi-dry state after being painted, and its adhesion to the outer panel of the car body will be poor. On the other hand, the hard chip paint has a higher specific gravity than the soft chip paint a, and is coated thickly because the thickness of the paint film absorbs shock as described above. For this reason, half-dried soft cheese
If a hard chip paint layer is applied overlappingly on top of the bump paint film A, the soft chip paint film A on the base side does not have enough strength to support the hard chip paint layer, so the paint layer will overlap as shown in Figure 5. As a result, the paint film is not formed in the normal shape shown by the chain line, and the parting line C formed by the hard chip paint film B no longer appears in a beautiful straight line.

Therefore, as shown in Figure 6, we applied hard chip coating first.
Next, it is possible to perform soft chip painting with some overlap, but soft chip paint uses a low boiling point solvent that easily evaporates, and the solvent evaporates immediately after painting, resulting in a semi-dry state as described above. On the other hand, hard chip paint uses a high boiling point solvent as well as a low boiling point solvent, and since it is difficult for the solvent to escape in the areas where soft chip paint a overlaps, it is difficult to remove the solvent after applying both paints. When coating E is applied and baking is performed, the baking causes the solvent of the hard chip paint in the overlapping area to fly out, resulting in pinholes. For this reason, even when applying soft chip paint a first,
Even when applying the hard chip paint a first, a baking process must be added between the two painting processes, and the undercoating process is divided into two stations.

Therefore, the present invention provides a coating method in which two types of paints with different properties can be applied at the same station in such a way that the coating films formed by these paints partially overlap. The challenge is to provide the following.

(Means for solving the problem) That is, the invention according to claim 1 of the present invention (hereinafter, the first
The invention is a method of applying two types of paints having different properties to an exterior panel so that the coating films formed by these paints partially overlap, and after applying the first paint, the first paint is applied. The present invention is characterized in that a portion of a coating film formed with one coating material that overlaps with a second coating material is subjected to forced drying treatment prior to coating with the second coating material.

Furthermore, the invention according to claim 2 of the present invention (hereinafter referred to as the second invention) is characterized in that, in the above-mentioned painting method, the first paint is a soft chip paint and the second paint is a hard chip paint. do.

(Function) According to the above-mentioned method, the first invention, after applying the first paint, applies the paint to the part of the paint film formed by the first paint that overlaps the paint film formed by the second paint. Since forced drying treatment is performed prior to application of the second paint, the first paint is a soft chip paint containing a low boiling point solvent and the second paint is a hard chip paint containing a high boiling point solvent, as in the second invention. In the case of paint, the soft chip paint film formed on the outer panel is forcedly dried to quickly remove the solvent from the paint film, dry the paint film, and then dry the soft chip paint film. A hard chip paint will be applied on top. Therefore, since the hard chip paint is overcoated on the soft chip paint film that is firmly adhered to the outer panel, the hard chip paint is supported by the soft chip paint film, and as a result, the hard chip paint will not slip in the overlapping area. No more peeling, and hard chip paint can be applied immediately without any additional treatment to prevent soft chip paint from baking.

(Example> Next, embodiments of the present invention will be described based on the drawings.

The embodiment shown in the drawings is one in which the painting method of the present invention is applied to the undercoating of a car body, and a car body 2 is carried into the painting station 1 shown in Fig. 1 from the right side of the drawing, and is transported to the left side. During this time, painting with the soft chip paint and painting with the hard chip paint are performed successively. and,
In that case, the tip of the car body, hood tip, roof tip, pillar fender, lower part of the door, etc. are first coated with soft chip paint, and then the following parts of the soft tip painted parts are painted: When painting with hard chip paint, a forced drying process is performed on the soft chip paint film in areas where the hard chip paint overlaps, and after this forced drying, the hard chip paint is applied to the skirts of the car body, side sills, lower parts of doors, and wheels. It is applied to aprons, floors, etc.

For this reason, the coating station 1 is provided with a soft chip coating section 3 and a hard chip coating section 4 arranged side by side in the car body transport direction, and a drying device 5 is provided between the two sections 3.4. The vehicle body 2 is configured to pass through these in order. Note that the cart 6 moves along a rail 7 laid at the coating station 1.

A gate-shaped pedestal 8 that surrounds the vehicle body 2 to be transported is installed in the soft chip coating section 3, and a coating gun 9 is installed on the pedestal 8 to apply soft chip paint mainly to the upper surface of the exterior panel of the vehicle body from above.
and a paint gun 10 that applies soft chip paint to the side surface of the vehicle body from the side, and these paint guns 9, 1
Of 0, 10 are paint guns that target the outer side of the car body.
are arranged on both sides of the vehicle body 2.

Also, in the hard chip painting section 4, there is a paint gun 11 that applies hard chip paint to both sides of the transported vehicle body 2.
is provided. The paint gun 11 is configured to apply hard chip paint to the soft chip paint film formed on the outer panel of the vehicle body in a soft chip coating section 3 so as to partially overlap the hard chip paint film on the vehicle body skirt portion and the like.

Furthermore, the drying device 5 is disposed on both sides of the vehicle body 2 being transported, and applies the hard chip paint over and over again to the soft chip coating formed on the outer panel of the vehicle body by passing through the soft chip coating section 3. Force dry the area. As a means for this forced drying, an air nozzle 12.12 is attached to the support stand 13, and room temperature air or warm air (hereinafter abbreviated as drying air) is supplied from the heat exchanger 14 to the air nozzle 12.12 to dry the vehicle body. I try to spray it on. That is, while introducing outside air into the heat exchanger 14, water or air is selectively supplied to exchange heat with the outside air,
The air or hot air thus obtained is supplied as drying air to the air nozzles 12.12 by the pump 15. Please note that switching between air and hot air is done at painting station 1.
Depending on the ambient temperature and coating conditions, conditions are selected that will suitably dry the soft chip coating.

Here, to explain some of the properties of soft-chip paint and hard-chip paint, soft-chip paint (soft-chip primer) prevents the paint film from peeling off due to impact from flying stones thrown up by other cars while driving. Something,
As mentioned earlier, it is a low-viscosity paint because it is applied to exterior parts that require high image clarity, such as the tips of car bodies.
In addition, resins such as PVC, urethane, polyester, and pigments are added to easily volatile low-boiling solvents.
Paint with a film thickness of about 50 μm.

On the other hand, hard chip paint (hard chip primer)
This prevents the paint film from peeling off due to the strong impact caused by stones thrown up by own troops or other vehicles while driving.For this reason, it is necessary to apply a thick film to the skirt parts, so the paint is made with high viscosity. Resins such as polyolefins and polyesters and pigments are added to low-boiling point solvents and high-boiling point solvents. and 100 μm to 50 μm to the outer plate.
Paint with a film thickness of 0 μm.

Next, to explain the painting operation, the car body 2 carried into the painting station 1 first passes through the soft chip coating section 3, and is coated on each predetermined outer panel part of the car body with a paint gun 9.10 as shown in Fig. 2. The soft chip paint film 1 formed on the vehicle body outer panel 17 is coated with the soft chip paint 16a and then passed through the drying device 5.
6, drying air 19 is blown from air nozzles 12, 12 onto the area where the hard chip paint 18a is applied in an overlapping manner, and the coating area is forcibly dried.

Then, in the hard chip coating section 4, a predetermined portion of the outer panel including the forcibly dried soft chip coating portion is coated with the hard chip paint 18a.
As shown in the figure, the undercoating is completed with the soft chip coating 16 and the hard chip coating 18 partially overlapping. Then, an intermediate coat is applied,
At the same time, burn-in processing is added.

Since the drying air 19 is blown onto the soft chip coating 16 prior to hard chip painting, the low boiling point solvent contained in the soft chip paint 16a is quickly volatilized and the soft chip coating 16 is dried. is strongly promoted, and the coating film 16 is strongly fixed to the vehicle body outer panel 17. Therefore, when the hard chip paint 18a is overlapped,
The hard chip paint 18a is supported by the soft chip paint film 16, so that the hard chip paint 18a
There will be no misalignment or slippage, and the parting line 20 at the paint overlap portion will come out cleanly.

Further, there is no need for a baking process between soft chip painting and hard chip painting, and both can be performed at the same painting station 1, saving space and reducing the cost of painting-related equipment.

In addition to using drying air as shown in FIG. 1, the drying device also uses a control circuit 22 for electric heaters 21 to 21 as shown in FIG.
Alternatively, as shown by the chain line in FIG. 4, an air nozzle for blowing drying air may be installed in the vicinity of the soft-chip paint gun 9.10. 23.23, it is possible to perform forced drying on the coated film surface almost simultaneously with the painting with these paint guns 9.10. In that case, an independent drying device 5.25 is installed between the soft chip coating section 3 and the hard chip coating section 3. There is no need to provide it between the coating part 4 and the coating part 4.

(Effects of the Invention) As is clear from the above description, the first invention provides a method for overlapping the coating film formed by the first coating material with the coating film formed by the second coating material after coating the first coating material. Since a forced drying treatment is applied to the part to be exposed to the paint prior to painting with the second paint, the first paint is applied as in the second invention.
If the paint is a soft-chip paint and the second paint is a hard-chip paint, the hard-chip paint will be overcoated on the soft-chip paint film that is firmly fixed to the outer panel by the above-mentioned forced drying process. Since the hard chip paint is supported by the soft chip paint film, the hard chip paint does not slip off in the overlapped area. As a result, hard chip coating can be applied immediately to soft chip paint without any additional processing, and both coatings can be done at the same painting station, making it possible to eliminate the need for equipment for intermediate baking. Saves space and reduces equipment costs.

[Brief explanation of drawings]

The drawings show an example in which the coating method according to the present invention is applied to car body undercoat painting on an automobile production line, and Fig. 1 is a schematic configuration diagram of a coating station, and Fig. 2 is a cross section showing forced drying treatment for a soft chip coating film. Fig. 3 is a cross-sectional view of a state in which a hard chip coating film is overlapped with a soft chip coating film, and Fig. 4 is a schematic configuration diagram showing a modified example of a forced drying device.6 Fig. 5 is a diagram of a prior art The cross-sectional view, FIG. 6, is a cross-sectional view of a different prior art. 3...Soft chip coating section, 4...Hard chip coating section, 5.25...Drying device, 16...Soft chip coating film, 16a...Soft chip paint, 17...Outer panel , 18... Soft chip coating film, 18a... Soft chip paint. Fig. fig.

Claims (2)

[Claims] (1) A method in which two types of paints with different properties are applied to an exterior panel so that the coating films formed by these paints partially overlap, and after applying the first paint, the first paint is A coating method characterized in that a portion of the coating film formed in the step 1 that overlaps with the second coating material is subjected to forced drying treatment prior to coating with the second coating material. (2) A method in which two types of paint, soft chip paint and hard chip paint, which have different properties, are applied to the exterior panel so that the coating films formed by these paints partially overlap. 1. A coating method, which comprises applying a forced drying treatment to a portion of the coating film formed with the paint that overlaps with the hard chip paint prior to applying the hard chip paint.