JP2001321722A - Method for coating internal and external plate of automotive body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of coating the internal and external plates of an automotive body by which the number of coating constituent items for an intermediate coating for an internal plate can be decreased, and the incompatibility of an external plate and the internal plate in terms of coloring can be lessened. SOLUTION: The method for coating the internal and external plates of an automotive body is carried out using a black-color flatting coating as the intermediate coating (C) for coating the internal plate of the automotive body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating an outer plate portion and an inner plate portion of an automobile body, and more particularly to a method for coating an intermediate coating material for an inner plate portion capable of reducing a variety of types. The present invention relates to a novel method for coating an inner / outer panel of an automobile body, which can reduce a sense of color discomfort with an inner panel.

[0002]

2. Description of the Related Art A cationic electrodeposition coating is applied to the inner and outer plates of an automobile body and heat-cured to form an undercoating film. A coating method for an automobile body, which comprises applying a coating material, heating and curing both of these coating films at the same time, then applying a top coating material on the outer panel and curing the top coating film, is already known. And is widely adopted. In addition, in order to reduce the discomfort of colors between the outer panel and the inner panel, the coating color of the intermediate coating for the inner panel and the coating of the top coating for the outer panel are approximated or matched. I was However,
Such a system has the drawback that the same number of intermediate coats as the color of the top coat must be prepared, which requires a large amount of material, personnel and time.

An object of the present invention is to eliminate the above-mentioned drawbacks in a method for coating an outer plate and an inner plate of an automobile body.

[0004]

Means for Solving the Problems As a result of earnest studies, the present inventors have found that the above object can be achieved by using a black matting paint as an intermediate coating for coating the inner plate. As a result, the present invention has been completed.

Thus, the present invention provides a method for coating the inner and outer panels of an automobile body, which comprises using a black matting paint as the intermediate coating (C) for coating the interior panel of the automobile body. .

The present invention further applies a cationic electrodeposition coating (A) to the inner and outer plates of an automobile body, heat-curs, and then applies an intermediate coating (B) to the outer plates to cure. Without applying the intermediate coating (C) to the inner plate,
After heating and simultaneously curing both the coatings of the inner plate and the outer plate, the outer plate is coated with a top coating (D), and the coating is cured. In the method, there is provided a method for coating the inner and outer panels of an automobile body, wherein a black mat paint is used as an intermediate coating (C) for coating an inner panel.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the coating method of the present invention will be described in more detail.

[0008] The present invention is directed to an automobile body for a passenger car,
It is the body of a mini car, bus, etc. The outer plate portion is a portion facing the outside of the vehicle body such as a door, a hood, a hood, and, for example, a hood, a panel roof, a trunk lid, a fender, a bumper, a door outside, a pillar, an apron, and the like. Also, as the inner plate,
For example, the back of the hood, the back of the trunk lid, the door opening, the back of the gasoline injection, and the like can be given. The material of the outer plate portion and the inner plate portion constituting these vehicle bodies is mainly made of metal, but plastic products may be present together.

In the method of the present invention, first, a cationic electrodeposition paint (A) is first applied as a primer to the metal parts of the inner and outer panels of the vehicle body. As the cationic electrodeposition coating material (A), a known one can be used. For example, a cationic electrodeposition paint obtained by blending a crosslinking agent, a pigment, and other various additives with an aqueous solution or aqueous dispersion of a salt of a cationic polymer compound, if necessary, can be used. Examples of the cationic polymer compound include those in which a cationic group is introduced by modifying a base resin such as an epoxy resin or an acrylic resin with an amino compound, which is neutralized with an organic acid or an inorganic acid. Into an aqueous solution or dispersion. As the crosslinking agent, a blocked polyisocyanate compound, an alicyclic epoxy resin, or the like can be suitably used.

[0010] The electrodeposition coating has, for example, a solid content of 5 to 5%.
In a bath of the cationic electrodeposition paint (A) adjusted to 40% by weight, a metal automobile body having an inner plate portion and an outer plate portion as main constituent members is immersed as a cathode, and a normal condition is applied to the anode. Can be carried out by energizing with. The thickness of the electrodeposition coating film is preferably in the range of 10 to 40 μm in the cured coating film,
The coating film can be cured by heating at about 140 to about 200 ° C. for about 10 to 40 minutes. This electrodeposition coating film is formed on both the inner plate portion and the outer plate portion.

In the present invention, the intermediate coating (B) and the intermediate coating (C) are applied to the cured electrodeposition coating films on the outer plate portion and the inner plate portion thus formed.

The intermediate coating material (B) for the outer panel portion contains, for example, a thermosetting resin composition and an organic solvent, and, if necessary, further contains a coloring pigment, an extender pigment and other additives for the coating material. Can be used a liquid intermediate coating material known per se.

The thermosetting resin composition includes, for example, a base resin such as an acrylic resin, a polyester resin, and an alkyd resin having a crosslinkable functional group such as a hydroxyl group, an amino resin such as a melamine resin and a urea resin, and a block polyisocyanate. Compounds containing a crosslinking agent such as a compound may be used. As the organic solvent, for example, ordinary paint solvents such as hydrocarbons, alcohols, esters, ethers, and ketones can be used. Intermediate paint (B)
Is preferably the same as or close to that of the top coat (D), or a gray color.

The intermediate coating (B) can be applied by a known method such as electrostatic coating, airless spray coating or air spray coating, and its film thickness is 10 to 40 μm based on the cured coating film. Is preferably within the range.

In the present invention, the intermediate coating (B) is applied to the outer plate portion, and the intermediate coating (C) is continuously applied to the electrodeposition cured coating surface of the inner plate portion without curing the coating film. Painted.

The intermediate coating (C) for the inner plate portion is a coating having a black color tone and capable of forming a matte coating film.
Specifically, for example, a liquid paint containing a thermosetting resin composition, a black pigment, and an organic solvent, and further containing, if necessary, other coloring pigments, extenders and paint additives is used. can do.

Examples of the thermosetting resin composition include a base resin such as an acrylic resin, a polyester resin and an alkyd resin having a crosslinkable functional group such as a hydroxyl group, an amino resin such as a melamine resin and a urea resin, and a block polyisocyanate. Compounds containing a crosslinking agent such as a compound may be used. Examples of the black pigment include carbon black, lamp black, graphite, iron black and the like. Further, as the organic solvent, for example, hydrocarbon-based, alcohol-based,
Usable paint solvents such as ester, ether and ketone can be used.

The intermediate coating (C) is a single coated film,
The color tone is to form a black and matte coating film, specifically, for example, a black pigment as described above, if necessary, in combination with other coloring pigments other than black, the coating film The matte color of the Munsell chart is in the range of 0 to 5, especially 0 to 3, and the gloss of the coated surface is 60% or less in terms of a 60-degree specular reflectance, particularly 30% or less. Preferably.

The intermediate coating (C) can be applied by a known method such as electrostatic coating, airless spray coating or air spray coating, and its film thickness is 5 to 20 μm based on the cured coating film. Is preferably within the range.

Next, both the intermediate coating applied to the outer plate and the intermediate coating applied to the inner plate as described above are heated and simultaneously cured. Heating is preferably performed at about 100 to about 170 ° C. for about 10 to 40 minutes,
By this heating, both intermediate coating films can be cured simultaneously.

In the method of the present invention, a top coat (D) is applied on the cured middle coat of the outer plate portion coated with the middle coat (B) as described above, and the top coat is cured. Let it.

The top coat (D) is applied to impart aesthetics, weather resistance and the like to the outer plate, and a known top coat having these functions can be used. Specifically, a liquid paint containing a thermosetting resin composition and an organic solvent, and further containing a coloring pigment, an extender pigment, and a paint additive as necessary can be used.

Examples of the thermosetting resin composition include a base resin such as an acrylic resin, a polyester resin and an alkyd resin having a crosslinkable functional group such as a hydroxyl group, an amino resin such as a melamine resin and a urea resin, and a block polyisocyanate. Compounds containing a crosslinking agent such as a compound may be used. As the color pigment, for example, a solid color pigment,
Known pigments for paints such as metallic pigments and light interference pigments are included. As the organic solvent, for example, ordinary paint solvents such as hydrocarbons, alcohols, esters, ethers and ketones can be used.

As the top coat (D), those which form a colorless transparent coating, a colored transparent coating, a solid color opaque coating, a metallic coating, a light interference coating and the like can be used. Alone or in combination of two or more
In a method known per se, one coat one bake method (1C1
B) 2 coats 1 bake method (2C1B), 2 coats 2
Bake method (2C2B), 3 coats 1 bake method (3C
1B) It is possible to form an overcoat film of a single layer or a multi-layer coating of two or more layers by coating by a three-coat two-bake method (3C2B) or the like.

The total thickness of the top coat is 20 to 20 for the cured coat.
Preferably within the range of 100 μm, from about 100 to about 180 ° C.
By heating for about 10 to 40 minutes.

[0026]

According to the method of the present invention described above,
(1) By using a paint capable of forming a black and matte coating film as the intermediate coating material (C) for the inner plate portion, various arbitrary coatings can be applied to the outer plate portion with the top coating material (D). Even if a colored top coat is formed, almost no color discomfort with the inner plate part is recognized. (2) Therefore, the coating color of the top coat (D) applied to the outer plate part is changed variously. However, the intermediate coating used for coating the inner plate may be the above intermediate coating (C) alone, and the number of intermediate coatings for the inner plate can be extremely reduced. In this case, a remarkable effect is obtained that one type of matte paint may be used.

[0027]

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 thickness of the coating film is that of a cured coating film.

Example 1 0.8 mm thick after degreasing and zinc phosphate conversion treatment
(Electron 2000, manufactured by Kansai Paint Co., Ltd., trade name, epoxy resin polyamine / block polyisocyanate compound system) with a film thickness of 20 μm on the entire surface of a dull steel plate (30 × 40 cm in size). The coating was cured by heating at 170 ° C. for 30 minutes.

Next, an intermediate coating (B) (polyester resin / melamine resin organic solvent type, gray color) is applied to one side (corresponding to the outer plate portion) of the steel sheet so as to have a thickness of 15 μm and cured. No other surface (corresponding to the inner plate portion) intermediate coating (C) (polyester resin / melamine resin organic solvent type, black, Maansell chart N value 1, 60 ° mirror reflectance of cured coating film 15%) The coating was applied to a thickness of 15 μm, left at room temperature for 2 minutes, and then heated at 140 ° C. for 30 minutes to simultaneously cure both intermediate coating films.

Thereafter, "Magiclon Silver" (manufactured by Kansai Paint Co., trade name, acrylic resin / melamine resin organic solvent type metallic paint) is applied to the coated surface of the intermediate paint (B) to a thickness of 15 μm. Then, without curing, "Magiclon Clear" (manufactured by Kansai Paint Co., Ltd., trade name, acrylic resin / melamine resin organic solvent type clear paint) was applied to a film thickness of 30 μm, and then cured at room temperature.
Then, the mixture was heated at 140 ° C. for 30 minutes to simultaneously cure both top coats.

When the surface corresponding to the outer plate portion and the surface corresponding to the inner plate portion of the obtained coated steel sheet were compared, no discomfort in color was recognized.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Eisaku Okada 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Shigeru Shigeru Shigeru Nakamura, 1st place in Miyoshi-cho, Nishikamo-gun, Aichi Prefecture Kansai Paint Kanji Paint Co., Ltd. (72) Inventor Yasushi Nakao Aichi, Nishikamo-gun, Miyoshi-cho, Oaza, 1st floor, Kanji Paint Co., Ltd. F term (reference) 4D075 AE06 BB89X CA47 CB02 DA06 DB02 DC12 EA05

Claims (2)

[Claims] 1. A method for coating an inner / outer panel of an automobile body, wherein a black mat paint is used as an intermediate coating (C) for coating an inner panel portion of the automobile body. 2. An inner coating portion and an outer coating portion of an automobile body are coated with a cationic electrodeposition coating material (A) and heat-cured, and then an outer coating portion is coated with an intermediate coating material (B) and cured. After applying the intermediate coating (C) to the inner plate, heating and simultaneously curing the coatings of the inner plate and the outer plate, and then applying the top coating (D) to the outer plate. A method for coating the inner and outer panels of an automobile body, comprising curing the top coat, wherein a black mat paint is used as an intermediate coating (C) for coating the inner panel. Painting method.