JP2000051780A - Forming method of double-layered coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To strengthen the flip-flop property of a double-layered coating film formed by using an optical interferential coating material and to sufficiently develop the designed property based on the interference of light by applying a metallic coating material containing aluminum flakes on an object to be coated and then, applying an optical interferential coating material. SOLUTION: When an optical interferential double-layered coating film with a white pearly tone is formed on an object to be coated such as a metal or plastic made chassis outer plate of a car, a coating material containing aluminum flakes which forms a twinkling bright coating film is used as a metallic coating material and is applied on the object to be coated prior to the optical interferential coating material. The metallic coating material is preferably a thermosetting liquid coating material essentially consisting of a resin compsn., the aluminum flakes and a solvent and further, if necessary, containing a coloring pigment, an extender, a sedimentation preventing agent and additives for a coating material. Preferably, the aluminum flakes to be used have 5 to 50 μm particle size and are compounded by 5 to 25 pts.wt. to 100 pts.wt. of the resin solid content.

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 white par tone light interference multilayer coating film having excellent glitter and flip-flop properties.

[0002]

2. Description of the Related Art It is already known to apply a light interference coating to a solid color coating surface containing no brilliant pigment to form a light interference coating. However, there is a defect that the flip-flop property is weak and the design property based on the optical interference cannot be sufficiently exhibited.

[0003]

SUMMARY OF THE INVENTION It is a main object of the present invention to enhance the flip-flop property of a multi-layer coating film using a light interference paint and sufficiently exhibit a design property based on light interference. The present inventors have found that the object can be achieved by using an aluminum flake-containing metallic paint instead of the conventional solid color paint, and completed the present invention.

That is, the present invention relates to a method for forming a multi-layer coating film, which comprises applying an aluminum flake-containing metallic paint (A) to an object to be coated, and then applying a light interference paint (B). And further includes applying a clear paint (C) to the coated surface of the light interference paint (B).

Hereinafter, the method for forming a multilayer coating film according to the present invention will be described in detail.

[0006] Metallic paint (A) : A paint for forming a glittering glittering coating film containing aluminum flakes, which is applied to an object to be coated prior to the light interference paint (B).

Examples of the object to be coated include a metal or plastic automobile body outer panel, which is previously coated with an undercoat (eg, a cationic electrodeposition paint) or an intermediate coat (optional) and cured. It is preferable to keep it.

The metallic paint (A) contains a resin composition, aluminum flakes and a solvent as essential components, and further contains a coloring pigment, an extender pigment, an anti-settling agent, a paint additive and the like as required. Thermosetting liquid paints are preferred.

The resin composition is preferably a thermosetting type,
For example, 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 a crosslinker such as a melamine resin, a urea resin, and a polyisocyanate compound (including a block body). These may be used in combination, and these may be used after being dissolved or dispersed in a solvent such as an organic solvent and / or water.

Aluminum flakes are brilliant scaly pigments containing metallic aluminum as a main component, and the metallic paint (A) has an average particle size of 5 to 50 μm.
Particularly, those having a shape factor (aspect ratio) of 8 to 30 μm, a thickness of 0.1 to 5 μm, and an average particle diameter divided by the thickness within a range of about 5 to 100 can be suitably used.
Either the fing type or the non-leafing type may be used.

The solvent includes an organic solvent, water and the like. In particular, as the organic solvent, a normal coating solvent such as a hydrocarbon solvent, an ester solvent, an alcohol solvent, a ketone solvent, or an ether solvent can be used.

The ratio of the base resin to the crosslinking agent in the resin composition is 50 to 50% based on the total weight of both components.
90%, the latter in the range of 50 to 10%, and the aluminum flake in the range of 5 to 25 per 100 parts by weight of the resin composition.
A range of parts by weight is respectively suitable.

In the present invention, it is preferred that the metallic coating (A) alone completely covers the color tone of the base (for example, the surface to be coated, the surface of the undercoat or the surface of the intermediate coating). Therefore, the undercoat concealment film thickness of the single coating film is preferably equal to or smaller than the coating film thickness. In order to secure this concealment property, a metallic pigment (A) may be coated with a coloring pigment as necessary. Can be blended.

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 And pigments for coloring. The amount of these components is determined by the metallic paint (A)
It is sufficient that the glossiness of the coating film is not reduced and the concealing property is aimed at.

The color tone of the single coating film of the metallic paint (A) is either a metallic tone using only aluminum flakes or a colored metallic tone using a coloring pigment in combination.

The metallic paint (A) is used for 10 to 25 seconds /
Adjust the viscosity of the hood cup to 4/20 ° C and use electrostatic coating, air spray, airless spray, etc. to directly apply to metal or plastic objects such as automobile outer panels.
Alternatively, an undercoat paint (for example, a cationic electrodeposition paint) or an intermediate coat paint (optional) is applied to the object to be coated, and the object to be cured is coated with a film having a thickness of 5 to 25 μm based on the cured film. It is preferable to paint on.

The electrodeposition paint is an undercoat paint applied to a conductive object to be coated, and an anion type can be used, but a cationic type having excellent corrosion resistance is preferably used.

As the cationic electrodeposition coating material, a known one prepared by mixing a pigment or various additives as necessary with an aqueous solution or aqueous dispersion of a salt of a cationic polymer compound can be used. For example, examples of the cationic polymer compound include those in which a cationic group formed by modifying an acrylic resin or an epoxy resin with an amino compound or the like is introduced, and this is neutralized with an organic acid or an inorganic acid to form an aqueous solution. Alternatively, it can be made into an aqueous dispersion. Further, a block polyisocyanate compound, an alicyclic epoxy resin or the like can be suitably used as a crosslinking agent. A metallic coating object is immersed in a bath of a cationic electrodeposition coating material as a cathode, and electricity is applied under normal conditions to perform electrodeposition coating. The coating thickness is 10 to 30 based on the cured coating.
μm is preferred, and crosslinking and curing can be performed by heating at 140 to 200 ° C. for 10 to 40 minutes.

The intermediate coating composition is to be applied to the undercoating surface, and a liquid composition comprising a resin composition and a solvent as main components and, if necessary, a coloring pigment, an extender pigment, additives and the like can be used. It is preferable to improve the smoothness, sharpness, gloss and the like of the formed multilayer coating film. As a resin composition, a crosslinker such as a melamine resin, a urea resin, and a polyisocyanate compound (including a block body) is blended with 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. Compositions. Organic solvents and / or water can be used as solvents. This intermediate coating composition is applied to a cured or uncured undercoating surface by electrostatic coating, air spraying, airless spraying, or the like to form a cured coating film having a thickness of 10 to 50 μm, and is heated at 100 to 170 ° C. for 10 to 40 minutes. It is cross-linked and cured by heating.

The coating of the metallic paint (A) is about 100 to
Crosslinking and curing can be performed by heating at a temperature of about 200 ° C. for 10 to 40 minutes. In the present invention, after the coating film of the metallic paint (A) is cured or in an uncured state,
The light interference coating (B) is applied to the coated surface.

Light interference coating (B) : applied to the cured or uncured surface of metallic coating (A).
It is a liquid paint containing a resin composition and a light interference pigment, which are dissolved or dispersed in an organic solvent and / or water. Since the single coating film contains the light interference pigment, the light interference pattern And the base material concealing property is low, and the metallic feeling of the coating film of the metallic paint (A) adjacent to the lower layer can be seen through.

The resin composition may be, for example, an acrylic resin having a crosslinkable functional group such as a hydroxyl group, a polyester resin, or an alkyd resin, or a base resin such as an amino resin such as a melamine resin or a urea resin, or a (block) polyisocyanate. Thermosetting compositions obtained by blending various crosslinking agents. The light interference pigment is a flaky particle pigment having a light interference effect, and examples thereof include mica, mica coated with a metal oxide such as titanium oxide and iron oxide, and mica coated with a coloring pigment. , Its average particle size is 5-50μ
m, particularly preferably in the range of 10 to 40 μm, and the amount thereof is in the range of 1 to 25 parts by weight, preferably 3 to 20 parts by weight, per 100 parts by weight of the resin composition. The light interference paint (B) is obtained by mixing the above components and dispersing them in a solvent such as an organic solvent and / or water. The coating film hiding power of the light interference coating (B) is preferably 50 μm or more, and this coating film is crosslinked and cured by heating at 100 to 170 ° C. for 10 to 40 minutes.

The light interference paint (B) is formed by applying an electrostatic coating to the cured or cured coating surface of the metallic paint (A).
Coat with an air spray or an airless spray so as to be thinner than the concealed film thickness.
Crosslink and cure by heating for ~ 40 minutes. Light interference paint (B) on the cured surface of the cured metallic paint (A)
No paint film is mixed between the two.

The multi-layer coating film of the present invention is achieved by applying the metallic paint (A) and the light interference paint (B) by the two-coat one-bake system or the two-coat two-bake system as described above. Yes, but this light interference paint (B)
The present invention also includes a multi-layer coating film obtained by applying a clear coating (C) to the cured or uncured coating surface and heating and curing the coating.

Clear paint (C) : This is applied to the coated surface of the cured or uncured light interference paint (B), and is a colorless transparent or colored transparent mixture obtained by mixing a resin composition and a solvent. It is a liquid composition that forms a coating film.

The resin composition is prepared by mixing a crosslinking resin such as an amino resin such as a melamine resin and a urea resin or a polyisocyanate with a base resin such as an acrylic resin, a polyester resin and an alkyd resin having a crosslinking functional group. A composition comprising: Further, Japanese Patent Application Laid-Open No. 62-8 / 1987
4137, JP-A-62-87288, JP-A-1-39653, JP-A-2-4577,
(JP-A-1-39653, JP-A-2-4577, JP-A-1-39653, JP-A-2-457
7, JP-A-1-39653, JP-A-2-4
No. 577), a thermosetting resin composition which does not require the use of the amino resin as a crosslinking agent can also be suitably used. As the solvent, an organic solvent and / or water can be used, and it is prepared by dissolving or dispersing the thermosetting resin composition in this. If necessary, a color pigment, a metallic pigment, a light interference pigment, an ultraviolet absorber and the like can be blended in the clear paint (C) to such an extent that transparency is not impaired.

The clear paint (C) is obtained by mixing the above-mentioned components, and mixing and dispersing them in a solvent such as an organic solvent and / or water.

The clear coating (C) is applied to the coating surface of the cured or uncured light interference coating (B) by using an electrostatic coating, an air spray, an airless spray, or the like, based on the cured coating film. It is preferable to apply the coating so as to have a thickness of 50 μm.

The multilayer coating film according to the present invention comprises a metallic coating (A), a light interference coating (B) and a clear coating (C).
It can also be obtained by painting with a coat 1 bake method, a coat 3 bake method, and a coat 3 bake method. The cross-linking and curing of the single-layer or multi-layer coating film in these coating methods is performed by heating at 100 to 180 ° C. for 10 to 40 minutes.

[0030]

The multilayer coating film of the present invention has a metallic coating film on the lower layer and a light interference coating film on the upper layer, so that light rays reach the metallic coating film through the light interference coating film. And again passes through the light interference coating. Therefore, since the light reflection from the metallic coating film is strong and shines white, the light interference of the light interference coating film on the upper layer is combined with the light interference coating film to form a white paint color-like multilayer coating film having a strong flip-flop property. Was.

Examples and comparative examples according to the present invention will be described below. All parts and percentages are based on weight, and the thickness of the coating film is for the cured coating film.

1. Sample 1) Coated object Degreasing and zinc phosphate treated steel sheet (JIS G314
1, a size of 400 × 300 × 0.8 mm, a cationic electrodeposition paint (“ELECRON 9400HB”, manufactured by Kansai Paint Co., Ltd., trade name, epoxy resin polyamine-based cationic resin, block polyisocyanate as a curing agent The compound containing the compound is electrodeposited by a conventional method so as to have a film thickness of 20 μm, cured by heating at 170 ° C. for 20 minutes, and then coated on the coated surface with an intermediate coating (“Lugagabe middle coating”). White ”, manufactured by Kansai Paint Co., Ltd., trade name, polyester resin / melamine resin type, organic solvent type), coated to a thickness of 30μ, and cured by heating at 140 ° C for 30 minutes.
It was an object to be coated.

2) Metallic paint (A) Organic solvent-based paint obtained by blending aluminum flakes and the like in a ratio shown in Table 1 per 100 parts by weight (solid content) of a resin component comprising a hydroxyl group-containing acrylic resin and a melamine resin. .

[0034]

[Table 1]

Note 1) Acrylic resin: hydroxyl value 110, number average molecular weight 25000 Note 2) Melamine resin: butyl etherified melamine resin Note 3) Aluminum flake: Toyo Aluminum Co., non-leafing aluminum flake, thickness 0.2μ, average particle size 10μ Note 4) Carbon black: CABOT, BLACK
PERLS1300 Note 5) White titanium: “CR97” trade name, manufactured by Ishihara Sangyo Co., Ltd.

3) Light interference coating (B) (B-1): 70 parts of a hydroxyl group-containing acrylic resin (Note 6),
30 parts of butylated melamine resin (Note 7) and scaly mica coated with titanium oxide (maximum diameter 10-20 μm, thickness 0.5-1)
μ, an organic solvent-type paint comprising 10 parts of a product name “Iriodin 103R” (trade name, manufactured by Merck). Solid content 20%.

Note 6) Hydroxyl group-containing acrylic resin: hydroxyl value 100, number average molecular weight 20,000.

Note 7) Butylated melamine resin: A mixed methyl / butyl etherified melamine resin.

(B-2): The resin solid content of an aqueous emulsion of a resin composition comprising 65 parts of a hydroxyl group-containing acrylic resin (Note 8), 15 parts of a urethane resin (Note 9) and 20 parts of a melamine resin (Note 10) is 100. Per part by weight (solid content)
Titanium oxide-coated scaly mica (above “Iriodin 103
R ") A water-based paint adjusted to have a solid content of 20% by adding 10 parts.

Note 8) Hydroxyl-containing acrylic resin: An emulsion having an average particle size of 0.1 μm and a hydroxyl value of 35. Neutralized with dimethylethanolamine.

Note 9) Urethane resin: water-extended emulsion. Neutralized with triethylamine.

Note 10) Melamine resin: "U-Van 28S
E "(manufactured by Mitsui Toatsu Chemicals, Inc., trade name, hydrophobic melamine resin).

4) Clear paint (C) "Lugabek clear", manufactured by Kansai Paint Co., Ltd., trade name, acrylic resin / amino resin type, organic solvent type.

2. EXAMPLES AND COMPARATIVE EXAMPLES Metallic paint (A) was applied to the intermediate cured coating surface of the object to be coated using a mini-bell type rotary electrostatic coating machine at a temperature of 20 ° C. and a humidity of 75.
% And left at room temperature for 3 minutes. Paint thickness is 15μ
m. Then, a light interference paint (B) was applied to the uncured metallic coating film surface at a temperature of 20 ° C. and a humidity of 75% using a REA gun, and left at room temperature for 3 minutes. The film thickness is 15
１８18 μm. Thereafter, the coating was heated at 140 ° C. for 30 minutes in a hot-air circulating drying oven to simultaneously cross-link and cure two layers of a metallic coating and a light interference coating.

Further, the metallic paint (A) and the light interference paint (B) were applied as described above, and the system coated with (B-1) was allowed to stand at room temperature for 3 minutes, and then (B-2) After preheating at 80 ° C. for 10 minutes, the uncured coating surface of the light interference coating (B) is applied to the clear coating (C).
Using a mini-bell type rotary electrostatic coating machine, temperature 20 ℃,
Painted at 75% humidity. The coating thickness is 40 μm. After leaving it indoors for 10 minutes, it was heated at 140 ° C. for 30 minutes in a hot air circulating drying oven to simultaneously crosslink and cure three layers of a metallic coating, a light interference coating and a clear coating. .

Table 2 shows the coating process of the metallic paint (A), the light interference paint (B) and the clear paint (C), and the performance test results of the obtained multilayer coating film.

[0047]

[Table 2]

The test method is as follows.

F / F property: The result of visual observation of flip-flop property. ○ indicates that the color tone is clearly changed depending on the observation angle and the design is excellent. Δ indicates that the color tone is little changed depending on the observation angle. Poor, × indicates no change in color tone depending on the viewing angle, indicating poor design.

Glossiness: This is the result of visually evaluating the glossiness of the coated surface. 良好 indicates good glossiness, Δ indicates slightly poor glossiness, and X indicates slightly poor glossiness.

Claims (5)

[Claims] 1. A method for forming a multi-layer coating film, comprising coating an object to be coated with a metallic paint containing aluminum flakes (A) and then applying a light interference paint (B). 2. A method for forming a multilayer coating film, comprising sequentially applying an aluminum flake-containing metallic paint (A), a light interference paint (B) and a clear paint (C) to an object to be coated. 3. The metal flake (A) according to claim 1, wherein the aluminum flake has a particle size of 5 to 50 μm and a compounding amount of 5 to 25 parts by weight per 100 parts by weight of the resin solid content. Method for forming a multilayer coating film. 4. The undercoat concealed film thickness of the metallic paint (A) is as follows:
3. A cured film having a thickness of 5 to 25 [mu] m.
2. The method for forming a multilayer coating film according to item 1. 5. The method according to claim 1, wherein the object to be coated is an outer plate of an automobile body.