JP2002205007A - Method of repairing white color based multiple coat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of repairing a white color based multiple coat. SOLUTION: The method of repairing the white color based multiple coat is performed by polishing and removing a defect part generated on the white color based multiple coat composed of an electrodeposition coat (A), an intermediate coat (B), a white color based base coat (C) having the L value of the coat, which is adjusted to >=8.5 by a titanium white pigment and an aluminum flake, a white pearl tone or silver pearl tone base coat coat (D) and a clear coat (E) until the electordeposition film is exposed and applying a repairing white color coating material (F) having the L value approximate to that of the white color base coat (C) and <=30 μm white-black covering thickness and next, forming successively the base coat (C), the base coat (D) and the clear coat (E).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white base coat coated on an object to be coated with an electrodeposition coating, an intermediate coating, a titanium white pigment and aluminum flake so that the L value becomes 85 or more. A method for repairing a defective portion generated in a multi-layer coating film composed of a white pearl-like or silver pearl-like base coat film and a clear coat film containing flaky mica powder coated with titanium oxide, in particular, the color in the repaired portion The present invention relates to a repairing method in which invisibility is prevented and smoothness and the like are improved.

[0002]

2. Description of the Related Art An electrodeposition coating film, an intermediate coating film, a white base coating film, a white pearl or silver pearl base coating film and a clear coating film are applied to an object to be coated such as an automobile outer panel. It is known to form a white multi-layer coating film consisting of (JP-A-8-16435).
No. 8). During the coating process for forming this multi-layer coating film, for example, during coating, moving to the next process, during heating and curing of the coating film, dust adheres to each coating surface, In some cases, the appearance of the finished product may be degraded due to generation of dents.

Conventionally, as a method of repairing these defective portions, for example, the portion is ground and removed until the electrodeposition coating film is exposed, and the above-mentioned white base coat coating film, base coat coating film and clear coat coating are applied to the portion. The film is formed, however, the white base coat film may be applied thinner than the concealed film thickness, and as a result, the electrodeposition film exposed through the white base coat film may be formed. There is a problem in that the multilayer coating film at the repaired portion is not sufficiently smooth.

[0004] An object of the present invention is to remove the electrodeposited coating to the extent that the electrodeposited coating is exposed in order to repair the defective portion generated in the above-mentioned white multilayer coating. It is an object of the present invention to provide a method capable of repairing a painted surface excellent in smoothness without any inconvenience even if it is painted thin.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the exposed electrodeposited coating film surface has an approximate L value of a white base coat coating film and a black-and-white opaque film thickness. 30
μm or less is applied beforehand by using a white paint for repair, then a white base coat, pearl base coat and clear coat are formed,
The inventors have found that the above problems can be solved, and have completed the present invention.

Thus, according to the present invention, the L value is 85 due to the electrodeposition coating film (A), the intermediate coating film (B), the titanium white pigment and the aluminum flake formed sequentially on the substrate.
The white base coat coating film (C) adjusted as described above, a white pearl tone or silver pearl tone base coat coating film containing titanium oxide-coated flaky mica powder (D), and a clear coat coating film (E) Defects generated in the white multi-layer coating film consisting of are removed by grinding so that the electrodeposition coating film (A) is exposed, and the L value is approximated to the white base coat coating film (C). And applying a white paint for repair (F) having a black-and-white opaque film thickness of 30 μm or less,
Next, there is provided a method for repairing a white-based multilayer coating film, characterized by sequentially forming the above-mentioned base coat coating film (C), base coat coating film (D) and clear coat coating film (E).

Hereinafter, the coating film repair method of the present invention will be described in more detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to an electrodeposition coating film (A), an intermediate coating film (B), a titanium white pigment and aluminum flake, which are sequentially formed on an object to be coated, to have an L value of 85 or more. A white base coat coating film (C), a white pearl or silver pearl base coating film containing titanium oxide-coated flaky mica powder (D), and a clear coating film (E). It relates to a method of repairing a defective portion generated in a white-based multilayer coating film.

[0009] First, the white multilayer coating film to be repaired by the present invention will be described.

As an object to be coated, a conductive base material which can be electrodeposited and which is an outer plate portion of an automobile such as a passenger car or a mini car can be suitably used. It is preferable that the substrate is subjected to degreasing, zinc phosphate treatment or the like before the electrodeposition coating.

The substrate to be coated includes an electrodeposition coating (A), an intermediate coating (B), a white basecoat (C), a basecoat (D) and a clearcoat (E). The white multi-layer coating film is preferably formed by the method described below.

The electrodeposited coating film (A) can be formed by applying an anionic electrodeposition paint or a cationic electrodeposition paint on an object to be coated, and is usually a cationic electrodeposition paint having excellent anticorrosion properties and the like. It is preferred to use

[0013] The cationic electrodeposition coating composition is prepared by blending, if necessary, a crosslinking agent, various pigments, and other additives with a known cationic electrodeposition coating material, for example, an aqueous solution or dispersion of a cationic polymer compound. Things can be used. Examples of the cationic polymer compound include those in which an amino group is introduced into an acrylic resin or an epoxy resin having a crosslinkable functional group such as a hydroxyl group, which is neutralized with an organic acid, an inorganic acid, or the like to make it water soluble. Alternatively, by dispersing in water, an aqueous solution or dispersion of the cationic polymer compound is obtained. As the crosslinking agent, for example, a block polyisocyanate compound, an alicyclic epoxy compound, or the like can be used.

The coating of the cationic electrodeposition paint on the object to be coated is carried out, for example, by immersing the object as a cathode in a cationic electrodeposition paint bath in which the solid content is adjusted to 10 to 35% by weight, under ordinary conditions. It can be carried out by applying a current, the thickness of the cured film is preferably in the range of 10 to 40 μm,
After washing with water, about 130 to about 200 ° C, preferably about 150 to
The coating is cured by heating at about 180 ° C. for about 10 to 40 minutes to form the electrodeposited coating (A). The intermediate coating for forming the intermediate coating film (B) can be applied to a substantially uncured electrodeposition coating film, but is generally applied to the cured electrodeposition coating surface. preferable.

The intermediate coating film (B) contains, for example, a resin component and a solvent as main components and, if necessary, an aqueous or organic solvent containing a coloring pigment, an extender pigment, and other paint additives. It is formed by applying an intermediate coating of a mold, whereby the smoothness, sharpness, gloss, etc. of the multilayer coating film can be improved.

As the resin component, a thermosetting resin composition is preferable. Specifically, a melamine resin or a block polyisocyanate is added to a base resin such as an acrylic resin, a polyester resin or an alkyd resin having a crosslinkable functional group such as a hydroxyl group. Those obtained by adding a crosslinking agent such as a compound,
As the solvent, an organic solvent, water, or the like can be used.

The intermediate coating is applied to the cross-linked and cured or substantially uncured electrodeposited coating (A) surface by using an electrostatic coating, an airless spray, an air spray, or the like to form a cured coating. It is preferable that the coating be performed so that is within a range of 10 to 50 μm. This coating film can be cured by heating at about 120 to about 170 ° C., preferably about 130 to about 160 ° C. for about 10 to 40 minutes, but in the present invention, either a cured or uncured intermediate coating film The white base coat coating film (C) can be formed on the coating surface of (B).

The white base coat coating film (C) is a white coating film adjusted to have an L value of 85 or more with titanium white pigment and aluminum flake. Titanium white pigment, aluminum flake, and solvent as main components, and, if necessary, a color pigment, extender, and other paint additives, etc., and a white color adjusted to have an L value of 85 or more. It can be formed using an aqueous or organic solvent type white paint which forms a system coating film.

The resin component of the white paint is preferably a thermosetting resin composition. Specifically, it can be used for a base resin such as an acrylic resin, a polyester resin, an alkyd resin, and a urethane resin having a crosslinkable functional group such as a hydroxyl group. And those obtained by adding a crosslinking agent such as a melamine resin or a blocked polyisocyanate compound, and these are used by being dissolved or dispersed in a solvent such as an organic solvent or water.

Titanium white pigment is a white pigment containing titanium dioxide as a main component and generally has an average particle size of 0.2 to 0.2.
Those having a diameter in the range of 0.35 μm, particularly 0.25 to 0.3 μm are preferred. The aluminum flakes are scaly metallic aluminum, and usually have a thickness of 0.1 to 1 μm, particularly 0.2 to 0.5 μm, and a particle size of 1 to 20 μm. Among them, those having an average particle diameter of 10 μm or less are preferable.

The white base coat coating film (C) contains the above-mentioned titanium white pigment and aluminum flake, and in the present invention, the content thereof is adjusted so that the coloring degree of the coating film is 85 or more in L value, preferably Adjust so that it is 90 or more. Here, the L value is the lightness of the coating film, the L value 0 is pure black, the L value 100 is pure white, 85 or more is a grayish white or pure white, and 90 or more is almost pure white. . In the present invention, Suga Test Machine Co., trade name,
L value was measured using "Suga SM-5 color computer".

In order to obtain a white coating film having an L value of 85 or more, aluminum flake is generally used in a ratio of 0.1 to 5 parts by weight, particularly 0.3 to 2 parts by weight, per 100 parts by weight of titanium white pigment. It is preferable to mix and use these pigments at a ratio such that the total amount of these pigments falls within the range of 40 to 250 parts by weight, particularly 60 to 130 parts by weight, per 100 parts by weight of the resin solids. By containing both the titanium white pigment and the aluminum flake pigment in the amounts described above, a grayish white or pure white coating film is formed, glittering glitter is not recognized, and the substrate concealing property is excellent. Thin film (5 to 2 in thickness based on the cured coating film)
(Within a range of 0 μm). When a white pearl-like or silver pearl-like base coat (D) to be described later is formed on such a white base coat (C), a multilayer paint having high whiteness and excellent pearl luster is obtained. can get.

The white paint for forming the white base coat coating film (C) is formed by applying an electrostatic coating, an airless spray, an air coating, or the like onto the cross-linked or substantially uncured intermediate coating film (B). It is preferable to use a spray or the like to apply the cured coating film in a thickness of 5 to 20 μm. This coating film can be cured by heating at about 120 to about 170 ° C., preferably about 130 to about 160 ° C. for about 10 to 40 minutes. In the present invention, either the cured or uncured white base coat is applied. A white pearl or silver pearl base coat film (D) can be formed on the coated surface of the film (C).

The white-pearl or silver-pearl base coat coating film (D) is a coating film containing flaky mica powder coated with titanium oxide.
A water-based or solvent-based pearlescent paint comprising a resin component, a titanium oxide-coated flaky mica powder and a solvent as main components, and, if necessary, a coloring pigment, an extender pigment, and other paint additives. It can be formed by painting.

As the resin component of the pearl paint, a thermosetting resin composition is preferable. Specifically, the resin component is used for a base resin such as an acrylic resin, a polyester resin, an alkyd resin, and a urethane resin having a crosslinkable functional group such as a hydroxyl group. And those obtained by adding a crosslinking agent such as a melamine resin or a blocked polyisocyanate compound, and these are used by being dissolved or dispersed in a solvent such as an organic solvent or water.

The flaky mica powder coated with titanium oxide used in the pearl paint is generally called white mica or silver mica, and is distinguished from interference mica. Specifically, the surface of flaky mica powder is coated with titanium oxide, and generally has a maximum diameter of 5 to 60 μm, particularly 5 to 25 μm, and a thickness of 0.25 to 25 μm. Those having a size of 1.5 μm, particularly 0.5 to 1 μm are preferable. In order to finish the base coat film (D) in a white pearl or silver pearl tone, the coating thickness of titanium oxide is usually 90 to 160 nm based on the optical thickness, and the geometric thickness is It is preferable to adjust within the range of 40 to 70 nm based on the standard.

The amount of the flaky mica powder coated with titanium oxide is usually 3 to 3 parts by weight per 100 parts by weight of the solid content of the resin component.
A range of 20 parts by weight, especially 5 to 12 parts by weight, is suitable.

In the pearl paint, if necessary,
Silver plated glass flakes, titanium coated graphite,
Metallic titanium flake, plate-like iron oxide, phthalocyanine flake, and the like can be appropriately blended.

The pearl paint for forming the white pearl-like or silver pearl-like base coat film (D) is formed on the coated surface of the crosslinked and substantially uncured white base coat film (C). It is preferable to apply a cured coating by using electrostatic coating, airless spray, air spray or the like so that the film thickness is in the range of 5 to 20 μm. This coating can be cured by heating at about 120 to about 170 ° C., preferably about 130 to about 160 ° C. for about 10 to 40 minutes, but in the present invention, either a cured or uncured base coat coating ( A clear coat film (E) can be formed on the coated surface of D).

The clear coat coating film (E) is a colorless and transparent or colored and transparent coating film. The coating film contains, for example, a resin component and a solvent as main components. Can be formed by applying a clear paint in which a coloring pigment, an extender pigment, and other paint additives are blended to such an extent that the paint is not impaired.

The resin component used in the clear paint is preferably a thermosetting resin composition, and specifically, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, or a urethane resin having a crosslinkable functional group such as a hydroxyl group. And a cross-linking agent such as a melamine resin or a blocked polyisocyanate compound, which is used by being dissolved or dispersed in a solvent such as an organic solvent or water.

The clear paint for forming the clear coat film (E) is formed by applying an electrostatic coating, an airless spray, an air spray to the cross-linked or substantially uncured base coat film (D). It is preferable to apply such as to make the cured coating film thickness in the range of 10 to 100 μm. The coating itself is about 120 to about 170
The composition can be cured by heating at about 130 ° C., preferably about 130 ° C. to about 160 ° C. for about 10 to 40 minutes.

The multi-layer coating film composed of the white base coating film (C), the base coating film (D) and the clear coating film (E) is formed at a temperature of about 120 to about 170 ° C., preferably about 120 to about 170 ° C., according to a three-coat one-bake method. About 130 to about 160 and 10 to 40
By heating for about a minute, the multilayer coating film composed of three layers can be simultaneously cured.

As described above, an electrodeposition coating film (A), an intermediate coating film (B), a white base coat coating film (C), a base coat coating film (D), and a clear coat coating film ( During the coating process for forming a white-based multilayer coating film consisting of E), for example, during coating, moving to the next process, or during heat curing of the coating film, the coating film floats on each coating surface. There is a case where the finished appearance is deteriorated due to the attachment of garbage, dents and the like.

The present invention relates to a method for repairing a defective portion generated in a white multilayer coating film as described above,
It is preferable to carry out as follows.

According to the present invention, even when the electrodeposited film is ground and removed to the extent that the electrodeposited film is exposed in order to repair a defective portion generated in the white-based multilayer coating film, the coating surface has no inflammation and has excellent smoothness. Specifically, the present invention provides a method of repairing, specifically, grinding and removing a defective portion generated in a white-based multilayer coating film to such an extent that the electrodeposition coating film (A) is exposed. First, the L value of the white base coat coating film (C) and the black and white concealment film thickness of 3
After the repair white paint (F) having a thickness of 0 μm or less is applied, a white base coat (C), a base coat (D), and a clear coat (E) are sequentially formed.

For grinding and removing the defective portion generated in the white-based multilayer coating film, for example, sandpaper, water-resistant abrasive paper, steel wool, or the like is used to polish the coated surface within the narrowest possible area around the defective portion. Then, it is ground to such an extent that the surface of the electrodeposition coating film underneath is exposed. This can be done manually, or it can be done using an electric polishing device or the like. The polishing area is preferably as narrow as possible around the defective portion, but the range varies depending on the size and number of the defective portions, and the entire surface of the object to be coated may be polished.

In the present invention, the L-value of the white base coat film (C) used in the step of coating the object to be coated is approximated to the ground surface, and the black-and-white opaque film thickness is 30 μm or less. A certain white paint for repair (F) is applied.

The L value of the white paint for repair (F) in the state of a single coating film is similar to that of the white base coat coating film (C) used in the above-mentioned coating process. It is preferable that the value is lower by about 1 to 10, especially about 1 to 5 than the value. The white paint for repair (F) has a black and white hiding film thickness of 30 μm.
m or less, especially in the range of 15 to 23 μm. "Black and white concealed film thickness" means white paint for repair (F)
Is coated on the surface to be printed with a black and white lattice pattern, and the minimum film thickness (cured coating film) through which the lattice pattern cannot be visually observed.

The repairing white paint (F) having such characteristic values contains, for example, a resin component, a coloring pigment, and a solvent as main components, and may further include an extender pigment and other paint additives as necessary. In particular, using the same titanium white pigment and aluminum flake as described for the white paint used for forming the white base coat film (C) as the coloring pigment, the L value falls within the above range. It can be easily adjusted. Specifically, aluminum flakes are used in an amount of 0.1% per 100 parts by weight of titanium white pigment.
It is suitable to use in the range of 2 to 3 parts by weight, and it is preferable to use the titanium white pigment and aluminum flake in the range of 90 to 200 parts by weight per 100 parts by weight of the resin in total. As the resin component, a thermosetting resin composition is preferable.Specifically, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, or a urethane resin having a crosslinkable functional group such as a hydroxyl group, a melamine resin or a block polyisocyanate is used. Examples thereof include those obtained by adding a crosslinking agent such as a compound, and these are used by being dissolved or dispersed in a solvent such as an organic solvent or water.

The repairing white paint (F) is applied to a portion where the electrodeposited coating film surface is exposed and its peripheral portion by removing a defect portion generated in the white-based multilayer coating film by grinding. This painting is
It is performed by brush coating, airless spray, air spray, etc., and the coating film thickness is a cured coating film, for example, 3 to 25 μm.
m is preferable. The coating itself is about 120 to about 170
The composition can be cured by heating at about 130 ° C., preferably about 130 ° C. to about 160 ° C. for about 10 to 40 minutes.

According to the present invention, as described above, the defective portion of the white multi-layer coating film is removed by grinding, and the exposed electrodeposition coating surface and its peripheral portion are repaired with the white paint for repair (F). Is applied, and optionally cured, on the coated surface, the same base coat coating film (C) as used in the coating step,
The repair can be achieved by sequentially forming the base coat coating film (D) and the clear coat coating film (E). Specifically, a white paint for forming a white base coat film (C) on the cured or substantially uncured coating surface of the repair white paint (F) is formed by using an airless spray, an air spray, or the like. And the cured coating has a thickness of 3
パ ー ル 25 μm, and after curing the coating film or in a substantially uncured state, a pearl paint for forming a base coat coating film (D) on the coated surface is airless. Using a spray, air spray, etc., apply the coating with a cured coating so that the film thickness is in the range of 5 to 20 μm. After the coating is cured, or in a substantially uncured state, Apply a clear coating for forming a clear coating film (E) on the surface using an airless spray, air spray, or the like, and form a cured coating film having a thickness of 10 to 100 μm.
It is preferable to apply the coating so as to fall within the range. The multi-layer coating film formed on the repaired portion thus formed is about 12
0 to about 170 ° C, preferably about 130 to about 160 ° C.
By heating for about 0 to 40 minutes, the multilayer coating film can be cured at the same time. In the present invention, in particular, four coats of the repair white coat (F), the base coat coat (C), the base coat coat (D) and the clear coat coat (E) are used.
It is preferable to form by a baking method.

[0043]

According to the method of the present invention described above, the electrodeposition coating film (A), the intermediate coating film (B), the white basecoat coating film (C), the basecoat coating film (D) and the clear coat Even if the defect portion of the white multilayer coating film composed of the coating film (E) is removed by grinding and the electrodeposition coating film (A) is exposed,
The base coat film (C), which is subsequently painted by pre-painting a specific repair white paint (F)
Even if the film thickness is smaller than the concealing film thickness, it is possible to prevent the color scar at the repaired portion formed by forming the base coat film (D) and the clear coat film (E) thereon, and to improve the smoothness and the like. can do.

[0044]

EXAMPLES The method of the present invention will be described more specifically with reference to examples and comparative examples. All parts and percentages are based on weight, and the film thickness is for a cured coating film.

1. Preparation of sample 1) Cathodic electrodeposition paint “Electron 9400HB” for forming electrodeposition coating film (A) (manufactured by Kansai Paint Co., Ltd., obtained by mixing a block polyisocyanate compound as a curing agent with epoxy resin polyamine-based cation resin) 2) Intermediate coating for forming intermediate coating film (B) “Lugabake intermediate coating gray” (manufactured by Kansai Paint Co., trade name, polyester resin / melamine resin type, organic solvent type) 3) White base coating film ( C) White base coat for formation a) Hydroxyl group-containing acrylic resin (Note 1) 70 parts (solid content), butyl etherified melamine resin 30 parts (solid content), 100 parts of titanium white pigment (Note 2) and aluminum flake (Note) 3) A paint obtained by mixing and dispersing 0.8 parts in an organic solvent. The black-and-white opaque film thickness is 35 μm, and the L value of the single coated film (film thickness) is 92.

(Note 1) Hydroxyl group-containing acrylic resin: hydroxyl value 110, number average molecular weight 25,000.

(Note 2) Titanium white pigment: rutile type titanium oxide pigment, particle size 0.25 to 0.30 μm.

(Note 3) Aluminum flake: Toyo Aluminum, non-leafing aluminum paste,
Thickness 0.2-0.5 μm, average particle size 10 μm or less.

B) Hydroxyl-containing acrylic resin (Note 1) 70
(Solid content), 30 parts (solid content) of butyl etherified melamine resin, 100 parts of titanium white pigment (Note 2) and 0.5 part of aluminum flake (Note 3) are mixed and dispersed in an organic solvent. The black-and-white opaque film thickness is 40 μm, and the L value of the single coated film (film thickness) is 94.

4) Pearl paint for forming a pearly base coat (D) a) Hydroxyl group-containing acrylic resin (Note 4) 70 parts (solid content), methyl / butyl mixed etherified melamine resin 30
(Solid content) and 10 parts of a scaly mica pigment coated with titanium oxide (Note 5) in an organic solvent.

(Note 4) Hydroxyl group-containing acrylic resin: hydroxyl value 100, number average molecular weight 20,000.

(Note 5) Flake mica pigment coated with titanium oxide: maximum diameter 10 to 20 μm, thickness 0.5 to 1 μm, optical thickness of titanium oxide about 140 nm, geometric thickness about 6
0 nm, trade name “Oriodin 103R”, manufactured by Merck.

5) Clear coat for forming clear coat coating film (E) "Luga Bake Clear" manufactured by Kansai Paint Co., Ltd.
Acrylic resin / melamine resin type, organic solvent type.

5) Repair white paint (F) a) 70 parts of hydroxyl-containing acrylic resin (Note 1) (solid content), 30 parts of butyl etherified melamine resin (solid content), 100 parts of titanium white pigment (Note 2), A paint obtained by mixing and dispersing 1.5 parts of aluminum flakes (Note 3) and 0.1 parts of X yellow (Note 6) in an organic solvent. Black and white concealed film thickness is 2
At 0 μm, the L value of the single coated film (film thickness) is 88. Paste, thickness 0.2-0.5 μm, average particle size 10 μm or less.

(Note 6) X erotic-: yellow pigment.

B) Hydroxyl-containing acrylic resin (Note 1) 70
Part (solid content), 30 parts of butyl etherified melamine resin (solid content), 100 parts of titanium white pigment (Note 2), 1.3 parts of aluminum flake (Note 3) and X yellow (Note 6)
0.1 is mixed and dispersed in an organic solvent. The black-and-white opaque film thickness is 22 μm, and the L value of the single coated film (film thickness) is 89.

2. Examples and Comparative Examples Example 1 A steel plate (JIS G31) which had been degreased and surface-treated with zinc phosphate
41, a size of 400 × 300 × 0.8 mm) is coated with a cationic electrodeposition coating by a conventional method so as to have a film thickness of 20 μm, and is cured by heating at 170 ° C. for 20 minutes to form an electrodeposition coating film. On this coated surface, an intermediate coating material “Luga Bake Intermediate Gray” was applied so as to have a thickness of 20 μm.
For 30 minutes to cure and form an intermediate coating film.
Then, a white base coat a) was applied to the intermediate coated surface so as to have a film thickness of 10 μm and left at room temperature for 3 minutes.
m, and left at room temperature for 3 minutes. Then, the uncured coated surface was coated with a clear coating material “Luga Bake Clear” to a thickness of 30 μm, and left at room temperature for 3 minutes. C. for 30 minutes to simultaneously cure a three-layer coating consisting of a white base coating (C), a pearly base coating (D) and a clear coating (E).

A part (about 10 cm in diameter) of the multilayer coating film thus obtained was ground with sandpaper until the surface of the electrodeposition coating film was exposed.

Then, a white paint for repair (F) a) was applied to the ground portion so as to have a thickness of 10 μm and left at room temperature for 3 minutes, and then a white base coat a) was applied to the portion. After coating at 10 μm and leaving at room temperature for 3 minutes, this uncured coated surface was coated with a pearlescent paint a) to a film thickness of 10 μm and left at room temperature for 3 minutes. A clear paint “Luga Bake Clear” is applied to the cured coating surface to a thickness of 30 μm, left at room temperature for 3 minutes, and then heated at 140 ° C. for 30 minutes to simultaneously cure these four-layer coatings. Repair painting was performed. The multi-layer coating film in the repair-applied portion had no color scale and good smoothness.

Example 2 A steel plate (JIS G31) degreased and surface-treated with zinc phosphate
41, a size of 400 × 300 × 0.8 mm) is coated with a cationic electrodeposition coating by a conventional method so as to have a film thickness of 20 μm, and is cured by heating at 170 ° C. for 20 minutes to form an electrodeposition coating film. On this coated surface, an intermediate coating material “Luga Bake Intermediate Gray” was applied so as to have a film thickness of 20 μm.
For 30 minutes to cure and form an intermediate coating film.
Then, a white base coat b) was applied to the intermediate coated surface so as to have a film thickness of 10 μm and allowed to stand at room temperature for 3 minutes.
m, and left at room temperature for 3 minutes. Then, the uncured coated surface was coated with a clear coating material “Luga Bake Clear” to a thickness of 30 μm, and left at room temperature for 3 minutes. C. for 30 minutes to simultaneously cure a three-layer coating consisting of a white base coating (C), a pearly base coating (D) and a clear coating (E).

A part (about 10 cm in diameter) of the multilayer coating film thus obtained was ground with sandpaper until the surface of the electrodeposition coating film was exposed.

Then, a repairing white paint (F) b) was applied to the ground portion so as to have a thickness of 10 μm, left at room temperature for 3 minutes, and a white base coat a) was applied to the portion. After coating at 10 μm and leaving at room temperature for 3 minutes, this uncured coated surface was coated with a pearlescent paint a) to a film thickness of 10 μm and left at room temperature for 3 minutes. A clear paint “Luga Bake Clear” is applied to the cured coating surface to a thickness of 30 μm, left at room temperature for 3 minutes, and then heated at 140 ° C. for 30 minutes to simultaneously cure these four-layer coatings. Repair painting was performed. The multi-layer coating film in the repair-applied portion had no color scale and good smoothness.

Comparative Example 1 The procedure of Example 1 was repeated except that the application of the white paint for repair (F) a) in Example 1 was omitted. In addition, color scale was observed and the smoothness was insufficient.

COMPARATIVE EXAMPLE 2 Except that the application of the repair white paint (F) b) in Example 2 was omitted, the treatment was carried out in the same manner as in Example 1. In addition, color scale was observed and the smoothness was insufficient.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Seiichi Honda 1-10-10, Shinsayama, Sayama City, Saitama Prefecture Inside Honda Motor Co., Ltd. (72) Inventor Toshiaki Sunaga 1-10-10, Shinsayama, Sayama City, Saitama Prefecture (1) Inside Honda Motor Co., Ltd. (72) Inventor Mitsuru Muramoto 7-3 Satsuki-cho, Kanuma City, Tochigi Prefecture Inside Kansai Paint Co., Ltd. (72) Inventor Yozo 7-3, Satsuki-cho, Kanuma City, Tochigi Kansai Inside Paint Co., Ltd. (72) Inventor Michiaki Morita 7-3 Satsuki-cho, Kanuma City, Tochigi Prefecture Kansai Paint Co., Ltd. F term (reference)

Claims (1)

[Claims] 1. The L value was adjusted to 85 or more by an electrodeposition coating film (A), an intermediate coating film (B), a titanium white pigment, and aluminum flakes sequentially formed on an object to be coated. A white base coat (C), a white pearl or silver pearl base coat containing titanium oxide-coated flaky mica powder (D) and a clear coat (E). The defect part generated in the above is ground and removed to the extent that the electrodeposition coating film (A) is exposed,
In that part, the L value is the above white base coat coating film (C)
And applying a white paint for repair (F) having a black-and-white concealing film thickness of 30 μm or less, and then applying the base coat (C), base coat (D) and clear coat (E) A method for repairing a white-based multilayer coating film, which is formed sequentially.