JPH111641A - Process for forming double-layer coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a double-layer film having excellent brilliance and hiding power and high saturation by applying a metallic coating material containing a coloring pigment and iron-oxide-coated aluminum oxide flakes and a clear coating material. SOLUTION: The coloring pigment used is exemplified titanium oxide or carbon black. The aluminum flakes are based on alumina, flaky in shape and has a thickness of 0.1-10 μm and a longer direction size of 2-50 μm. The coating weight of the iron oxide is 0.1-60 pts.wt. per 100 pts.wt. flake. The cured film of the metallic coating material itself should be 5-40 μm. The amount of the flakes added is 1-30 pts.wt. per 100 pts.wt. solid matter of the resin composition. The metallic coating material is diluted with an organic solvent or water so that it may have a solid content of 25-50 wt.% during application and a viscosity of 10-30 sec (as measured with a Ford cup #4 at 20 deg.C). The thickness of the coating film of the clear coating material (e.g. crosslinking-group-containing acrylic resin) is 10-100 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a multi-layer coating film having excellent brilliancy and hiding properties and having high chroma.

[0002]

2. Description of the Related Art A method of forming a multilayer coating film by sequentially applying a metallic paint containing a mica flake and a coloring pigment and a clear paint is already known.

[0003] Although this multi-layer coating film has interference, it is inferior in brilliant glitter, and it has been difficult to finish the coating film with high chroma.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for forming a multi-layer coating film having excellent brilliancy and hiding properties, and having high chroma. The feature is that a paint containing a color pigment and an aluminum oxide flake whose surface is coated with iron oxide is used as a metallic paint. As a result, the above-mentioned object can be sufficiently achieved. Was.

[0005] That is, the present invention is characterized in that a metallic paint (A) and a clear paint (B) containing a color pigment and an aluminum oxide flake whose surface is coated with iron oxide are coated. It is intended to provide a coating film forming method (hereinafter, referred to as "the method of the present invention").

The method of the present invention will be described in more detail.

Metallic paint (A) : clear paint (B)
Prior to the coating is a paint applied to the object to be coated, a resin component,
A thermosetting liquid paint containing a coloring pigment, an aluminum oxide flake whose surface is coated with iron oxide, a solvent, and, if necessary, a extender pigment and other paint additives. .

As the resin component used for the metallic paint (A), a thermosetting resin composition is preferable, and specifically, an acrylic resin having a crosslinkable functional group such as a hydroxyl group, a polyester resin, an alkyd resin, a urethane resin, etc. Melamine resin, urea resin, polyisocyanate
And a compound used in combination with a crosslinking agent such as a compound (including a block body), and these can be used by dissolving or dispersing in an organic solvent and / or water.

Aluminum oxide flame coated with iron oxide
The main component is aluminum oxide (Al ₂ O ₃ ),
This is also called alumina, and has a scaly shape and a thickness of 0.1 to 1.0 μm, particularly 0.2 to 0.
5 μm, longitudinal dimension 2-50 μm, especially 10-30
μm is preferred. In addition, iron oxide (Fe
The coating of the aluminum oxide flake surface with ₂ O ₃ ) can be carried out by a method known per se, and the coating amount of the iron oxide is 100 parts by weight of the aluminum oxide flake.
It is preferably in the range of 0.1 to 60 parts by weight, especially 1 to 20 parts by weight.

The aluminum oxide flake coated with the iron oxide has a smooth surface, is more brilliant than mica flake, has excellent glitter, and shows a red color. Exhibits light interference.

In the metallic coating (A), if only aluminum oxide flakes coated with iron oxide are used as pigments, the hiding power of the coating film is not sufficient. Therefore, a coloring pigment is further added to improve the hiding power. It is preferable to include them.

Examples of the coloring pigment used in combination with the aluminum oxide flake coated with iron oxide include titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chrome ero, chromium oxide, and Prussian blue. , Pigments for solid color such as azo pigments, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, sullen pigments and perylene pigments; aluminum flakes, mica, mica coated with metal oxide, mica Metallic pigments such as iron oxide; and these are used in combination with aluminum oxide flakes coated with iron oxide within a range where a single coating film of metallic paint (A) can cover the substrate. Is done. Concerning the single cured coating film of the metallic paint (A), the concealing film thickness is 5 to 4
The range of 0 μm is suitable, and the color tone of the aluminum oxide flake coated with iron oxide itself is red, so that the color tone based on red color is suitable.

In the metallic paint (A), the amount of the aluminum oxide flakes coated with iron oxide is 1 to 30 parts by weight per 100 parts by weight of the solid content of the resin composition.
Particularly, 1 to 20 parts by weight is preferable.

The metallic paint (A) is prepared by mixing and dispersing a resin composition, an aluminum oxide flake coated with iron oxide, and a coloring pigment in a solvent such as an organic solvent or water to obtain a solid content at the time of coating. The content is 20 to 60% by weight, preferably 25 to 50% by weight, and the viscosity is 10 to 3%.
It is preferable to adjust the temperature to 0 sec / ford cup # 4/20 ° C.

In the method of the present invention, the metallic paint (A) may be directly applied to a metal or plastic object to be applied to an automobile or the like. For example, it is preferable to apply a coating such as a cationic electrodeposition coating) or an intermediate coating beforehand and apply it to a cured object.

The metallic coating (A) can be applied by a method such as electrostatic coating, air spraying or airless spraying. It is preferably in the range of ４０40 μm or more. The coating film itself can be cross-linked and cured at a temperature of about 100 to about 170 ° C. In the present method, the following clear coating is applied to the coated surface which has been cross-linked and cured or not cross-linked and cured without being cross-linked. Paint (B).

Clear paint (B ): The clear paint (B) is
This is a paint applied to the uncured or cross-linked cured paint surface of the metallic paint (A). The paint contains a resin component and a solvent as main components and, if necessary, does not impair the transparency of the paint film. It is a liquid paint that forms a colorless or colored transparent coating film, which is formed by mixing a coloring pigment and other paint additives.

The resin component used in the clear paint (B) is as follows:
A thermosetting resin composition is preferable, 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, a carboxyl group, or an epoxy group, a melamine resin, or a urea resin. ,
Examples thereof include those used in combination with a crosslinking agent such as a polyisocyanate compound (including a block body), a carboxy group-containing compound (resin), and an epoxy group-containing compound (resin), and the solvent includes an organic solvent and / or water. Can be used.

The clear paint (B) can be applied to the coating surface of the uncured or cross-linked cured metallic paint (A) by a method such as electrostatic coating, air spray, or airless spray. , Its film thickness is 10 to 10 based on the cured coating
It is preferable that the thickness be in the range of 100 μm. The coating of the clear coating (B) itself can be cross-linked and cured at a temperature of about 100 to about 170 ° C.

In the present method, an undercoat paint (for example, a cationic electrodeposition paint) or an intermediate paint (optional) is applied directly to an object to be coated such as a metal or a plastic or these objects to be cured and cured. A metallic paint (A) is applied to the object to be coated, and the coating film is crosslinked and cured, or the uncrosslinked cured coated surface is coated with a clear coating material (B).
The coating is cured by heating at a temperature of 00 to about 170 ° C. for 10 to 40 minutes to cure the coating. Can be achieved.

[0021]

According to the present invention, a multi-layer coating film having excellent glittering and hiding properties and high chroma was able to be formed.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. Parts and percentages are by weight unless otherwise specified.

1. Sample 1) Coated object Degreasing and zinc phosphate treated steel sheet (JIS G314
1. Cationic electrodeposition paint (“Elecron 9400HB”, manufactured by Kansai Paint Co., Ltd., trade name, epoxy resin polyamine-based cationic resin as a curing agent for block size polyisocyanate compound on 400 × 300 × 0.8 mm size) Is applied by a conventional method so as to have a film thickness of 20 μm (as a cured coating film), and is heated at 170 ° C. for 20 minutes for crosslinking and curing. ("LuGabeque middle coating gray", Kansai Paint Co., Ltd.)
(Trade name, polyester resin / melamine resin type, organic solvent type) was applied so as to have a thickness of 30 μm (as a cured coating film), and was heated at 140 ° C. for 30 minutes to be crosslinked and cured.

3) Metallic paints (A-1) to (A-)
2) An organic solvent in which aluminum oxide flakes, coloring pigments, and the like coated with iron oxide are mixed at a ratio shown in Table 1 per 100 parts by weight (solid content) of a resin component composed of a hydroxyl group-containing acrylic resin and a melamine resin. Mold paint.

[0025]

[Table 1]

* 1) Hydroxyl group-containing acrylic resin: hydroxyl value 110, number average molecular weight 25,000. * 2) Melamine resin: butyl etherified melamine resin * 3) Iron oxide-coated aluminum oxide: Aluminum oxide flake surface coated with iron oxide, aluminum oxide flake (Al ₂ O ₃ ) 0.2-0.5μ thickness
m, the longitudinal dimension is 15 to 20 μm, and the coating amount of iron oxide is 5 parts by weight per 100 parts by weight of aluminum oxide flake.

* 4) Mica coated with iron oxide: "EM Lasset" (manufactured by Marl, trade name) * 5) Color pigment: "Perylene Marn 6436" (manufactured by Bayer, trade name) 4) Clear paint (B) "Ru Gabe Kuclear", manufactured by Kansai Paint Co., Ltd., trade name, acrylic resin / amino resin type, organic solvent type.

2. Examples and Comparative Examples Metallic paints (A-1) to
(A-2) using a mini-bell type rotary electrostatic coating machine
The coating was performed at a temperature of 20 ° C. and a humidity of 75%. The coating film thickness
μm (as a cured coating). The clear coating (B) was applied to the uncured coating surface of the metallic coating at a bus temperature of 20 ° C. and a humidity of 75% using a mini-bell type rotary electrostatic coating machine. The coating thickness is 45 μm (as a cured coating). After leaving it indoors for 3 minutes, it was heated at 140 ° C. for 30 minutes in a hot-air circulation drying oven to simultaneously cure a two-layer coating film composed of a metallic paint and a clear paint.

3. Performance Test Results Table 2 shows the coating process of the paint and the performance test results of the obtained multilayer coating film.

[0030]

[Table 2]

Test Method Brightness: The glitter was visually evaluated.は is good, and △ is slightly inferior.

Concealment: Measured on black-and-white concealment paper.

Saturation: Measured with a Lab colorimeter.

[0034]

(Equation 1)

Claims (2)

[Claims] 1. A method for forming a multilayer coating film comprising applying a metallic paint (A) and a clear paint (B) containing a color pigment and aluminum oxide flakes whose surfaces are coated with iron oxide. . 2. The method according to claim 1, wherein the object to be coated is an automobile body.