JPH0630724B2 - Partial coating film repair method - Google Patents

Description

The present invention relates to a method for partially repairing a coating film. More specifically, it relates to a method for partially repairing a coating film having an overcoating film having a small hiding power, such as a coating film containing a titanized mica pigment or a pearlescent pigment.

[Prior Art] A coating having a top coating film containing a titanized mica pigment or a pearlescent pigment is generally called a pearl coating and is used for coating an automobile body or the like due to its unique design effect.

In the pearl coating, the basic color of the coating is the coating color of the underlying colored coating film of the above-mentioned top coating film, and the hiding power of the top coating film is small in order to give the appearance of the coating color of this colored coating film. Therefore, it is difficult to adopt a normal repairing method when partially repairing the pearl coating, and for example, the following repairing method has been proposed (see Japanese Patent Publication No. 57-60910).

That is, as shown in FIG. 4, the pearl coating contains a colored undercoat film (21), a titanized mica pigment or a pearlescent pigment on an article (20) on which an electrodeposition coating film or the like is previously formed. Low hiding power top coat (22) and clear coat (2
3) is formed in order, but if there is a defective part in this coating film that reaches the colored base coating film (21), in order to carry out partial repair, first try to repair the coating object (20). Base polishing is performed until the colored undercoat film (21) is reached on the portion to be etched.
In FIG. 4, (A) shows the ground surface of the base. Next, repair the colored undercoat so that the colored undercoat (21) and the overcoat (22) appearing on the base sharpening surface (A) are completely covered.
(21a) is formed, and then a repair top coat film (22a) is formed on the repair colored base coat film (21a) to such an extent as to cover it, and a repair clear coat film (23a) is further formed on the repair colored top coat film (23a). Finish painting.

[Problems to be Solved by the Invention] However, there are the following problems when the above-mentioned repair method is used.

That is, when spraying the repair paint onto the repair part, it is a normal method to apply 1 from the center of the repair part to the outside, but as described above, the top coat film (22) has almost no hiding power. There is no colored base coat (21) on the base sharpened surface (A)
It is difficult to distinguish the boundary part (B) between the top coating film (22) and the top coating film (22) and the boundary part (C) between the top coating film (22) and the clear coating film (23). It is very difficult to exactly overlap the outer peripheral portions of the repaired colored base coat (21a) and the repair top coat (22a) as shown in FIG.

Therefore, repair colored base coat (21a) and repair top coat
The overlap in the outer peripheral part of (22a) is not sufficient, and a band-shaped mark remains on the outer peripheral part, and the above-mentioned top coating film (22
If (a) overlaps too much, if a titanized mica pigment with a strong interference color is used, the interference color of the overlap portion becomes too strong and the repaired part becomes conspicuous.

Even when trying to apply the above-mentioned repair method to partial repair of the coating film when the defective portion remains in the top coating film (22) (that is, when the base sharpening is stopped with the top coating film (22)),
The above-mentioned problems occur due to the low hiding power of the top coat film (22).

In view of the above points, the present invention is a pearl coating and the like.
It is an object of the present invention to provide a partial repair method in which a good finish at the boundary between a coating film in a non-repaired portion and a repair coating film can be performed relatively easily.

[Means for Solving Problems] The present invention forms a top coat film using a top coat paint having a low hiding power on a colored base coat film formed on a coating material, and further, the above-mentioned top coat paint. When repairing a coating film formed by forming a clear coating film using the same type of clear coating resin and a coating resin to a depth reaching the top coating film,
After the base is sharpened to the depth of reaching the depth of the top coat, the repair top coat of the same paint color and the same type of resin as the top coat, but with a low pigment concentration and viscosity. The coating is applied in a strip shape on the outer peripheral portion of the base sharpening surface so as to partially overlap with the clear coating film, and then a repair topcoat coating film is formed on the entire repair portion using the same type of paint as the topcoat coating material, Further, the present invention relates to a method for partially repairing a coating film, in which a repair clear coating film is formed by wet-on-wet using a coating material of the same type as the above-mentioned clear coating material and then baked and dried.

[Examples] Next, a method for partially repairing a coating film of the present invention will be described with reference to the drawings.

1 to 3 are schematic explanatory views showing the method of the present invention in the order of steps.

The coating film to be partially repaired according to the present invention is, as shown in FIG. 1, an article to which an electrodeposition coating film or the like is previously formed.
(1), a colored base coating film (2), a low hiding power top coating film (3) and a clear coating film (4) are sequentially formed, especially a low hiding power top coating film (3 ) Is preferably applied to a pearl coating film containing a titanized mica pigment or a pearlescent pigment.

Usually, a thermosetting amino alkyd resin paint is used as a colored paint (2) that gives a colored base coat (2), and a top coat (3)
A thermosetting acrylic resin coating is used as a clear coating (4) that gives a top coating (3) and a clear coating (4), and therefore the colored base coating (2) is once baked and dried, and then the top coating is applied. (3) is formed, and then a clear coating film (4) is formed by wet on wet, and finally a top coating film (3)
The clear coating film (4) is baked and dried together to complete the coating. However, the type of paint used to form the coating film to be repaired by the present invention is not particularly limited.

When partially repairing the pearl paint coating film as described above according to the method of the present invention, as shown in FIG. 1, first, the repaired portion is overcoated over a relatively large range by an appropriate means such as water resistant abrasive paper (3). Grind the base to reach, clean the base grinding surface (X) with degreasing, and dry it.

Next, the base sharpening surface (X) is subjected to repair coating according to the method of the present invention.

In the present invention, unlike the conventional method, as shown in FIG. 2, first, a preliminary repair top coat is applied to the top coat film (3) of the outer periphery of the base polishing surface (X) and the polishing surface of the clear coating film (4). Coating film (3
b) is formed into a strip, this coating (3b) is the base polishing surface (X)
The strip-shaped repair coating film is formed on the outer peripheral portion of the repair portion because the strip-shaped repair coating film is formed on the outer peripheral portion.

Repair topcoat paint (3b) used to form the repair topcoat film (3b)
As b), the same coating color and the same type of resin as those of the above-mentioned top coating composition (3), but the pigment concentration and viscosity adjusted to be low are used.

The above-mentioned topcoat paint for repair (3b) having a low viscosity as described above is used because the coating film of this paint needs to be relatively thin and therefore the leveling property must be good. For example, while the thermosetting acrylic resin paint used as the top coat paint (3) has a viscosity of about 13 to 15 seconds (measured by Ford cup # 4 (20 ° C), the same applies below), Thus, a thermosetting acrylic resin paint as the top coat paint for repair (3b) having a viscosity of about 10 to 12 seconds is used.

In the top coating (3b), it is necessary to reduce the pigment concentration (the concentration with respect to the solid content, the same applies below) when the top coating (3a) overlaps, for example, in the case of pearl coating that exhibits an interference color. This is to prevent the interference color from becoming abnormally strong. 3/4 to 1 of the pigment concentration in the normal topcoat (3)
It is about / 2.

The topcoat paint for repair (3b) can be prepared by mixing the topcoat paint (3) and the clear paint (4) in an appropriate ratio, so it is not necessary to prepare a special paint specially, and it is convenient. is there.

The topcoat paint for repair (3b) is applied in a strip shape on the outer peripheral portion of the base polishing surface (X). Conventional spraying of repair paint is performed while moving the spray gun in the direction from the center to the outer periphery because the outer periphery of the base polishing surface (X) is also sprayed at the same time as the center. When the method is applied as it is, the boundary part (Y) between the top coating film (3) and the clear coating film (4)
Since it is difficult to distinguish between the two, problems such as insufficient or excessive superposition occur. However, in the present invention, as described above, the spray gun is applied to the outer peripheral portion of the base polishing surface (X) while moving along the boundary line of the coating film, so that it is difficult to distinguish the boundary portion (Y), The paint can be applied to the desired area relatively accurately.

As shown in Fig. 2, the repair topcoat (3b) is usually a clear coating with the inclined surface of the base polishing surface (X) on the topcoat (3).
It is provided so that it partially overlaps with (4).

Normally, the next coating film is formed in a wet state of the repairing top coating film (3b), and thus the top coating film (3b) is baked and dried at the time when the coating of the entire repaired part is completed.

After the preliminary repair coating is applied to the outer peripheral portion of the base polishing surface (X) as described above, the entire repair portion is painted as shown in FIG.

That is, as shown in FIG. 3, a repair top coating film (3a) and a repair clear coating film (4a) are formed on the entire repair portion.

Topcoat for repair (3a) for forming repair topcoat (3a)
As the above, the same as the above-mentioned top coating composition (3) is used.
As the clear coating for repair (4a) for forming the repair clear coating film (4a), the same one as the above-mentioned clear coating (4) is used.

The repair clear coating film (4a) is formed on the repair top coating film (3a) by wet on wet.

In the present invention, the outer peripheral portion of the base sharpening surface (X) has already been subjected to the preliminary repair coating as described above,
The topcoat paint (3a) and clear paint (4a) for repair are applied by a special method by moving the spray gun from the center to the outer periphery in the same way as the conventional spraying method for repair paint. Even without paying attention, it is possible to obtain a repair coating film having a good outer peripheral finish. Top coat paint in that case
(3a) may be applied on the top coat film (3) that has been sharpened so as to cover the preliminary repair top coat film (3b) at the outer peripheral portion. Finally, the clear paint (4a) is applied to the entire repair area and baked to complete the repair painting.

Next, the method of the present invention will be described with reference to Examples and Comparative Examples.

In the following examples and comparative examples, the coating test pieces prepared as described below were subjected to partial repair.

Steel plate with a size of 300 mm × 450 mm and a thickness of 0.8 mm (Material: JIS
G 3141) is preliminarily degreased and chemically treated, then dried film thickness 20μ
m electrodeposition coating film was applied.

Apply the coloring paint shown in Table 1 on the electrodeposition coating film,
It was baked and dried at a temperature of 20 ° C. for 20 minutes (keep) to form a colored base coating film (2) having a thickness of 25 μm.

Next, the surface of the colored base coating film (2) was water-polished using a # 500 water-resistant abrasive paper, thoroughly washed with water, and then dried.
Then, after degreasing the water-polished surface with ethyl alcohol, the top-coat paint shown in Table 2 was applied to a dry film thickness of 15 μm to form a top-coat coating film (3), and the coating film was wet. Further, the clear coating material shown in Table 3 was applied so as to have a dry film thickness of 25 μm to form a clear coating film (4), which was then baked and dried at 140 ° C. for 20 minutes (keep).

Example A scratch of 2 cm in length reaching the top coating film (3) was marked at the center of the coating film of the above-mentioned coating test piece with the edge of a 100-yen coin, and the scratch was mainly made with # 500 water-resistant abrasive paper. The base was sharpened until the scratch disappeared in a substantially circular area with a diameter of about 10 cm, washed thoroughly with water, and then degreased with ethyl alcohol.

Next, repair coating was performed as shown in FIGS.

First, use the topcoat for repair shown in Table 4 as the base polishing surface (X)
Part of the clear coating film (4) on top of the outer coating film (3)
And the average dry film thickness is about 10 μm
Was applied in the form of a strip to form a preparatory repair top coat (3b). The topcoat paint for repair shown in Table 4 is the topcoat paint shown in Table 2 and the clear paint shown in Table 3 at 7: 3.
It was prepared by mixing (solid content weight ratio).

The top coat (3b) is applied using a spray gun as a base.
It was carried out while moving along the outer peripheral portion of (X), but it was possible to easily apply the coating material to a predetermined region in a predetermined thickness.

Then, with the top coat film (3b) in a wet state, the top coat paint shown in Table 2 is ground and applied to the entire top coat film (3) to a height similar to this, and wet To form a repair top coat film (3a), and then apply the clear paint shown in Table 3 to the same thickness as the clear coat film (4) to form the repair clear coat film (4a). After that, these wet coatings were baked and dried at 140 ° C. for 20 minutes (keep) to complete the repair coating.

The coating surface condition of the coating test piece that had been subjected to repair painting was visually inspected, but no significant difference was found between the unrepaired part and the repaired part, especially the peripheral part, in terms of color difference, gloss, tint, etc. I couldn't do it.

Comparative Example The repair part of the above-mentioned coating test piece was subjected to base polishing in the same manner as in the example, and then repair coating was performed according to the conventional repair paint spraying method.

Apply the spray paint shown in Table 2 to the central part of the repaired part so that the top coat film (3) appearing on the base sharpening surface (X) and the clear coat film (4) partially overlap. Is applied while moving in the direction of the outer peripheral portion to form a wet repair top coat film, and further, a clear paint shown in Table 3 is applied to form a wet repair clear coat film.
Then, it was baked and dried at 140 ° C. for 20 minutes (keep).

When applying the topcoat paint, it becomes difficult to distinguish the boundary (Y) between the topcoat paint film (3) and the clear paint film (4) as the topcoat paint is sprayed. Was very difficult.

[Effects of the Invention] When partially repairing a coating film having an overcoating film with a small hiding power such as pearl coating, first, the boundary part between the non-repaired part and the repaired part is intensively repair-coated, thereby Repairs with a good finish have become relatively easy to perform.

[Brief description of drawings]

1 to 3 are schematic explanatory views showing the partial repairing method of the present invention in the order of steps, and FIG. 4 is a schematic explanatory view showing a conventional method. (Main symbols in the drawing) (2): Colored base coat (3): Top coat (3a), (3b): Repair top coat (4): Clear coat (4a): Repair clear coat

Claims (1)

[Claims] 1. A topcoat coating film is formed by using a topcoat paint having a low hiding power on a colored undercoat film formed on an object to be coated, and further a clear paint of the same kind as the topcoat paint and the coating resin is further formed thereon. When partially repairing a coating film formed by using a clear coating film to a depth reaching the top coating film, after subjecting the coating of the repaired part to a base polishing to a depth reaching the top coating film, A topcoat paint for repair, which has the same paint color and the same kind of resin as the above topcoat paint, and whose pigment concentration and viscosity have been adjusted to a low level, is formed on the outer periphery of the base polishing surface so as to partially overlap the clear paint film. Apply to
After that, a repair topcoat coating film is formed on the entire surface of the repaired portion using the same type of paint as the topcoat paint, and further a repair clear coating film is formed on the wet-on-wet using the same type of paint as the clear paint. A method for partially repairing a coating film, which comprises baking and drying afterwards.