JPH111642A - 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 sequentially applying a metallic coating material containing a coloring pigment and iron-oxide-coated aluminum oxide flakes and a clear coating material and effecting the crosslinking and curing by heating after every application or simultaneously effecting the crosslinking and curing after the later application. SOLUTION: The coloring pigment used is exemplified titanium oxide or carbon black. The aluminum flakes are flaky in shape and has a thickness of 0.1-1.0 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 thickness of the coating film of the clear coating material (e.g. crosslinking- group-containing acrylic resin) is 10-100 μm. The coated surface is prepared by a 3-coat-1-bake(3C1B) system comprising curing by heating to 100-170 deg.C for 10-40 min and in addition 3C2B and 3C3B systems.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a colored paint (particularly,
Red paint), metallic paint containing aluminum oxide flakes whose surface is coated with iron oxide, and clear paint are successively applied to give a pearly, high-brightness multi-layer coating film with excellent glitter. To a method for forming

[0002]

2. Description of the Related Art A method of forming a multilayer coating film by sequentially applying a metallic coating material and a clear coating material containing a coloring coating material, a titanium oxide-coated mica powder, and a clear coating material is already known. However, this multi-layer coating film has a defect that although it has an excellent par feeling, it is inferior in glittering glitter and it is difficult to obtain a coating film with high chroma. .

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming a layered coating film which is based on a colored coating film, has a par tone, is excellent in glitter, and has high chroma.

That is, the present invention is characterized in that a colored paint (A), a metallic paint (B) containing an aluminum oxide flake whose surface is coated with iron oxide (B), and a clear paint (C) are applied. The present invention provides a method for forming a multilayer coating film (hereinafter, referred to as "the method of the present invention").

The method will be described in more detail.

[0006] Colored paint (A ): A paint applied to an object to be coated prior to the metallic paint (B), containing a resin component, a colored pigment, a solvent, and, if necessary, an extender pigment and other paints. It is a thermosetting liquid paint containing an additive for use.

The color tone of the colored paint (A) is not limited at all, and may be either chromatic or achromatic. However, the aluminum oxide flake itself whose surface is coated with the iron oxide of the metallic paint (B) is not limited. Since it is a red type, it is more preferable to use a paint which forms a similar type red type coating film, since a multi-layered coating film having a high red color and excellent glitter can be formed.

As such a colored coating (A), a thermosetting liquid coating containing a resin component, a coloring pigment and a solvent, and further containing an extender pigment and other coating additives as necessary is suitable. It is.

The resin component in the coating material (A) is preferably a thermosetting resin composition, and specifically, a base resin such as an acrylic resin, a polyester resin, an alkyd resin or an urethane resin having a crosslinkable functional group such as a hydroxyl group. Is used in combination with a crosslinking agent such as a melamine resin, a urea resin, and a polyisocyanate compound (including a block body). These are dissolved or dispersed in a solvent such as an organic solvent and / or water. .

As the color pigment, for example, titanium oxide,
Solids such as zinc white, carbon black, cadmium red, molybdenum red, chrome ero, chromium oxide, prussian bull, cobalt bull, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, sulene pigments and perylene pigments Color pigments and the like can be mentioned, and in particular, it is preferable to use a red pigment to obtain a red colored paint (A).

In the method of the present invention, the colored paint (A) comprises:
It can be applied directly to metal or plastic objects such as automobiles. However, these objects are usually applied to undercoats (eg, cationic electrodeposition paints) or intermediate coats (can be omitted). Is preferably applied to an object which has been previously coated and cured.

The colored paint (A) can be applied by a method such as electrostatic coating, air spray, or airless spray, and its film thickness is generally in the range of 5 to 40 μm based on the cured coating film. preferable. The coating itself is about 100 to about 17
The cross-linking and curing can be performed at a temperature of 0 ° C., and in the method of the present invention, the following metallic coating (B) is applied to the coated surface which has been cross-linked and cured without being cross-linked and cured.

Metallic paint (B ): clear paint (C)
Prior to this, it is a coating applied to the cured or uncured coating surface of the colored coating (A), which contains a resin component, an aluminum oxide flake whose surface is coated with iron oxide, and a solvent. This is a thermosetting liquid paint which is prepared by blending a coloring pigment, an extender pigment, and other paint additives in accordance therewith.

The resin component used in the metallic coating (B) is preferably a thermosetting resin composition, and specifically, an acrylic resin having a crosslinkable functional group such as a hydroxyl group, a polyester resin, an alkyd resin, a urethane resin and the like. Melamine resin, urea resin, polyisocyanate
And a cross-linking agent such as a compound (including a block compound).

Aluminum oxide flame coated with iron oxide
The main component is aluminum oxide (Al ₂ O ₃ ),
This is also referred to as alumina, and has a scaly shape and a thickness of 0.1 to 1.0 μm, particularly 0.2 to 0.1 μm.
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.

The coating film of the metallic coating material (B) containing aluminum oxide flakes coated with iron oxide is brilliant and has an excellent brilliant feeling, but has insufficient hiding power. The coating film of (A) can be seen through. The metallic paint (B) may contain a color pigment to such an extent that the coating of the lower colored paint (A) is not obstructed from being seen through. As such a coloring pigment, for example,
The above-mentioned pigments for solid color, and metallic pigments such as aluminum flake, mica, mica coated with a metal oxide, and mica-like iron oxide;

In the metallic coating (B), the amount of the aluminum oxide flake 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 10 parts by weight is preferable.

The metallic paint (B) is prepared by mixing and dispersing a resin composition, aluminum oxide flakes coated with iron oxide and the like in a solvent such as an organic solvent or water, and the solid content at the time of coating is prepared. 20 to 60% by weight,
Preferably, the viscosity is 25 to 50% by weight, and the viscosity is 10 to 30 seconds /
It is preferred that the temperature be adjusted to ford cup # 4/20 ° C.

In the method of the present invention, the metallic paint (B) is a paint to be applied to the cured or uncured coating surface of the above-mentioned colored paint (A), for example, electrostatic coating, air spray, airless spray. For example, the thickness is preferably in the range of 10 to 40 μm based on the cured coating film. The coating film itself can be cross-linked and cured at a temperature of about 100 to about 170 ° C. In the method of the present invention, the following clear coating is applied to the uncrosslinked-cured coated surface after crosslinking or without crosslinking. Paint (C).

The method of the present invention can be applied to the uncured coated surface of the metallic paint (B) thus coated, or
The following clear coating (C) is applied to the coating surface which has been crosslinked and cured by heating at 170 ° C. for 10 to 60 minutes.

Clear paint (C ): The clear paint (C) is
A paint to be applied to the uncured or cross-linked cured surface of the metallic paint (B), which contains a resin component and a solvent as main components and, if necessary, to such an extent that the transparency of the paint film is not impaired. 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 (C) is preferably a thermosetting resin composition, and specifically, an acrylic resin, a polyester resin, or an alkyd resin having a crosslinkable functional group such as a hydroxyl group, a carboxyl group, or an epoxy group. And a base resin such as a urethane resin in combination with a crosslinking agent such as a melamine resin, a urea resin, a polyisocyanate compound (including a block body), a carboxyl group-containing compound (or resin), and an epoxy group-containing compound (or resin). Organic solvents and / or water can be used as the solvent.

The clear paint (C) can be applied to the coating surface of the uncured or crosslinked-cured metallic paint (B) 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 paint (C) itself can be cross-linked and cured at a temperature of about 100 to about 170 ° C.

In the method of the present invention, 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 metal or plastic, or these objects to be cured. After applying a colored paint (A) to the object to be coated and crosslinking and curing the coating film, or applying a metallic paint (B) to the uncrosslinked cured coating surface, the coating film is crosslinked and cured. After that, or on the uncrosslinked and cured coating surface, a clear coating material (C) is applied.
So-called three-coat one-bake method (3C1B), wherein the coating is cured by heating at a temperature of 10 to 40 minutes.
This can be achieved by a coating method using a coat 2 bake method (3C2B) and a 3 coat 3 bake method (3C3B).

Further, the method of the present invention comprises the steps of:
In 2B, any or all of the room temperature standing in these steps can be replaced by pre-drying at a temperature of about 50 to about 100 ° C. This predrying is preferably carried out to such an extent that the gel fraction of each coating film is not more than 60% by weight.

[0027]

According to the present invention, it has become possible to form a high-chroma multilayer coating film having a pearly tone and excellent glitter.

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) Colored paint (A-1) Per 100 parts by weight (solid content) of a resin component comprising a hydroxyl group-containing acrylic resin and a melamine resin, a titanium white pigment,
An organic solvent-type paint comprising aluminum flakes and carbon black in the proportions shown in Table 1.

[0031]

[Table 1]

* 1) Hydroxyl group-containing acrylic resin: hydroxyl value 110, number average molecular weight 25,000. * 2) Melamine resin: butyl etherified melamine resin 4) Metallic paint (B-1) Hydroxyl group-containing acrylic resin * 3) 70 parts, butylated melamine resin * 4) 30 parts and aluminum oxide resin coated with iron oxide -K * 5) An organic solvent type paint containing 8 parts. Solid content 20%.

* 3) Hydroxyl group-containing acrylic resin: hydroxyl value 100, number average molecular weight 20,000. * 4) Butylated melamine resin: methyl-butyl mixed air
Melamine resin * 5) Aluminum oxide flake coated with iron oxide:
It is coated with 10 parts of iron oxide per 100 parts of aluminum oxide flake, and has a thickness of 0.2 to 0.5 μm and a longitudinal dimension of 10 to 30 μm.

5) Metallic paint (B-2) An organic solvent paint comprising 70 parts of a hydroxyl group-containing acrylic resin * 3), 30 parts of a butylated melamine resin * 4) and 8 parts of colored mica * 6). Solid content 20%.

* 6) Colored mica: (iron oxide-coated mica,
"EM Russet" manufactured by Marl Co., Ltd., trade name, thickness is 0.
6) Clear paint (C) "Lu-Gabec clear", manufactured by Kansai Paint Co., Ltd., trade name, acrylic resin / amino resin, organic solvent type .

2. EXAMPLES AND COMPARATIVE EXAMPLES Color coating (A-1) was applied to the intermediate coating surface of the object to be coated using a mini-bell type rotary electrostatic coating machine at a bus temperature of 20 ° C. and a humidity of 75.
% Painted. The coating thickness is 20μm (as a cured coating)
And Metallic paints (B-1) to (B-2) were applied to the uncured coating surface of the colored paint using a REA gun at a bus temperature of 20 ° C. and a humidity of 75%. The film thickness is 10-13μ
m (as a cured coating). Thereafter, the clear paint (C) was applied to the uncured coating surface of each of the metallic paints (B-1) to (B-2) using a mini-bell type rotary electrostatic coater.
The coating was performed at a temperature of 20 ° C. and a humidity of 75%. The coating thickness is 25
μm (as a cured coating). After leaving it indoors for 3 minutes, it was heated at 140 ° C. for 30 minutes in a circulating hot air drying oven to simultaneously crosslink and cure three layers of coatings consisting of a colored base paint, 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.

[0038]

[Table 2]

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

Hiding power: Measured on black-and-white concealing paper.

Saturation: Measured with a Lab colorimeter.

[0042]

(Equation 1)

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09C 1/40 C09C 1/40

Claims (4)

[Claims] 1. A multi-layer coating film characterized by applying a colored paint (A), a metallic paint (B) containing an aluminum oxide flake whose surface is coated with iron oxide, and a clear paint (C). Forming method. 2. A three-coating method in which the above-mentioned colored paint (A), metallic paint (B) and clear paint (C) are applied sequentially and then heated to cross-link and cure the three layers simultaneously. 2. The method according to claim 1, wherein the method is a baking method. 3. The method according to claim 1, wherein the colored paint (A) is a red paint. 4. The method according to claim 1, wherein the object to be coated is an automobile body.