JP2003033721A - Metallic coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a multi-layered metallic film excellent in brightness which glitters. SOLUTION: This method for forming a metallic film is characterized in that a metallic paint containing a metallic pigment (A), a clear metallic paint containing alumina flake of 0.03 to 0.5 wt.% (B) and a clear paint (C) are sequentially painted on an object to be painted.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a multilayer metallic coating film having excellent glitter and glitter. 2. Description of the Related Art In recent years, in the overcoating of an automobile outer panel, the design of the finished appearance has been diversified, and the development of a new design coating has been strongly desired.
There is a need for the development of a metallic coating film that forms a coating film with even better glitter. At present, a metallic coating containing a metallic pigment such as aluminum flake and a metallic coating formed by repeatedly applying a clear coating are widely used as a top coating of an automobile outer panel. The metallic coating film has different light reflectivity (brightness) depending on the viewing angle, and has an effect that the design is superior to that of the solid color coating film. [0004] In order to enhance the glitter, it has been proposed to increase the concentration of the metallic pigment or to increase the particle size. However, the glitter does not increase so much. There are problems such as surface glossiness, metallic unevenness, and mixed layers with the upper clear coating film. An object of the present invention is to solve the above-mentioned problems and to provide a method for forming a metallic coating film with more excellent glitter. Means for Solving the Problems As a result of intensive studies, the present inventors have now applied a metallic paint containing a metallic pigment, and have now provided a clear paint containing only a small amount of alumina flake on the coated surface. -It has been found that the above object can be achieved by applying a metallic paint, and the present invention has been completed. Thus, according to the present invention, a metallic paint containing a metallic pigment (A), a clear metallic paint (B) containing 0.03 to 0.5% by weight of alumina flake, and a clear paint ( A method for forming a metallic coating film, wherein C) is sequentially applied. Hereinafter, the method for forming a metallic coating film of the present invention (hereinafter referred to as “the present method”) will be described in more detail. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of the object to which the method of the present invention can be applied include an outer plate portion of a metal or plastic automobile body, and the like.
An undercoating such as a cationic electrodeposition coating and, if necessary, an intermediate coating may be applied to the substrate in advance, and the coating film may be cured. The metallic paint (A) is a paint that is applied to the surface of an object to form a metallic coating prior to the clear metallic paint (B). Specifically, for example, a resin composition and a metallic pigment are mixed and dispersed in an organic solvent and / or water, and if necessary, a usual coating material such as a coloring pigment, an anti-settling agent, an ultraviolet absorber, and a coating surface adjusting agent. And those prepared by blending additives. As the resin composition, for example, an acrylic resin having a crosslinkable functional group such as a hydroxyl group, an alkyd resin,
Base resin such as polyester resin, melamine resin,
(Block) A composition comprising a cross-linking agent such as a polyisocyanate compound, and the like, and the metallic pigment is a pigment exhibiting brilliancy, such as flaky aluminum and vapor-deposited aluminum. As the organic solvent, paint solvents such as hydrocarbon solvents, alcohol solvents, ether solvents, ester solvents, and ketone solvents can be used. Further, as a coloring pigment used as needed, for example, titanium oxide, zinc white, carbon black,
Cadmium red, molybdenum red, chrome yellow,
Inorganic pigments such as chromium oxide, Prussian blue, and cobalt blue; and organic pigments such as azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, sulene pigments, and perylene pigments. These coloring pigments
It can be used within a range that does not inhibit the metallic feeling of the coating film itself of the metallic paint (A). The ratio of the base resin to the crosslinking agent in the above resin composition is generally based on the total solid content of these two components, and the base resin is 50 to 90% by weight, particularly 65 to 80% by weight, and the crosslinking agent is 50 to 10% by weight, especially 35 to 20
% By weight. The metallic pigment is usually used per 100 parts by weight (solid content) of the resin composition,
It can be used in the range of 1 to 100 parts by weight, especially 3 to 50 parts by weight. Further, the coloring pigment is usually 200 parts by weight or less per 100 parts by weight (solid content) of the resin composition,
In particular, it can be used in the range of 0 to 150 parts by weight. The undercoat concealment film thickness of the metallic paint (A) is 1
It is preferably 5 μm or less, particularly preferably 13 μm or less.
Here, the undercoat concealing film thickness is the minimum cured film thickness in which the color tone of the lower coated surface cannot be visually observed through the single coating film of the metallic paint (A). Specifically, JISK5
Metallic paint (A) was applied to black-and-white checkered opacity test paper in accordance with the description of “hiding power” of 400 so that the film thickness was sequentially different, and after curing, the minimum film thickness at which the black-and-white checkered pattern was not visible Is the underlayer concealing film thickness. The metallic paint (A) has a viscosity of 10
~ 20 seconds / Ford Cup # 4/20 ° C, and this is airless spray, air spray, electrostatic coating, etc.
A film thickness (in a cured coating film) that is equal to or greater than the underlayer concealing film thickness, for example, 10 to 10
It can be painted to have a thickness of 20 μm. The metallic paint (A) thus formed is concealed so that the color of the ground is invisible and has a brilliant color, and is colored with a solid color pigment to such an extent that the brilliant color does not disappear. There is also. In the present method, the metallic coating material (A) is applied to the object to be coated, and the coating film is cured without being cured or after being heated at about 80 to about 180 ° C. for about 10 to 40 minutes. A clear metallic paint (B) is applied to the painted surface. The clear metallic paint (B) applied to the cured or uncured surface of the metallic paint (A) contains a very small amount of alumina flakes, that is, 0.03-0.
It is a clear paint contained in the range of 5% by weight. Specifically, for example, ordinary paint additives such as a coloring pigment, an anti-settling agent, an ultraviolet absorber, and a surface-adjusting agent may be added to the resin composition, alumina flake and organic solvent, if necessary. Organic solvent-type clear paints are included. As the above-mentioned resin composition, organic solvent and coloring pigment, those exemplified in the description of the metallic paint (A) can be used in the same manner. The ratio of the base resin to the cross-linking agent in the resin composition is generally based on the total solid content of these two components, and the base resin is 50 to 90% by weight, particularly 6% by weight.
5 to 80% by weight, and the crosslinker can be in the range of 50 to 10% by weight, especially 35 to 20% by weight. The coloring pigment can be used to such an extent that the transparency of the coating film of the coating material (B) is not substantially impaired. Usually, 100 parts by weight or less per 100 parts by weight (solid content) of the resin composition,
In particular, it can be in the range of 0 to 80 parts by weight. Alumina flakes are scaly aluminum oxide (Al ₂ O ₃ ) and have a thickness of 0.1 to
Those having a length of 1 μm, particularly 0.2 to 0.5 μm, and a longitudinal dimension of 2 to 50 μm, particularly 10 to 30 μm are preferred. Alumina flakes used in the clear metallic paint (B) according to the present invention include:
Also included are those whose surfaces are coated with a metal oxide such as titanium dioxide, iron monoxide, diiron trioxide, etc., and the coating thickness is in the range of 0.01 to 1 μm, particularly 0.05 to 0.5 μm. Is preferred. These alumina flakes have a light-transmitting property, are more brilliant than aluminum flakes, and exhibit an interference effect due to the metal oxide layer applied to the surface, and can be arbitrarily colored according to the coating thickness. . In the clear metallic paint (B),
The content ratio of the alumina flake is in the range of 0.03 to 0.5 part by weight, preferably 0.05 to 0.2 part by weight, per 100 parts by weight of the resin composition contained in the coating material (B). Can be. When the content ratio of alumina flakes is less than this range, it becomes difficult to obtain a coating film excellent in glitter aimed at by the present invention, and when it exceeds this range, flip-flop properties are reduced, and metallic unevenness is likely to occur. . The clear metallic paint (B) can be prepared by mixing and dispersing the resin composition, alumina flakes, and the above-mentioned paint additives in an organic solvent. Viscosities of 10 to 3% by weight within a range of 60 to 60% by weight, preferably 25 to 50% by weight.
It is preferable to adjust the temperature to 0 sec / Ford cup # 4/20 ° C. The clear metallic coating (B) has a thickness based on the cured coating, for example, 15 μm or more, on the cured or uncured coating surface of the colored coating (A) by air spray, airless spray, electrostatic coating or the like. It is preferable to apply the coating so as to have a thickness of 20 to 70 μm. In the present method, the uncured coating surface of the clear metallic coating material (B) coated in this manner or about 80% is applied.
A clear paint (C) is further applied to the coated surface which is cured by heating at about 170 ° C. for about 10 to 40 minutes. The clear paint (C) applied to the cured or uncured coating surface of the clear metallic paint (B) is a paint that forms a colorless transparent or colored transparent coating. Liquid paints obtained by blending ordinary paint additives such as color pigments, anti-settling agents, ultraviolet absorbers, and coating surface adjusters, if necessary, with the resin composition and the organic solvent can be used. As the resin composition, the coloring pigment and the organic solvent, those exemplified in the description of the metallic paint (A) can be used in the same manner. The ratio of the base resin to the crosslinking agent in the resin composition is generally based on the total solid content of these two components, and the base resin is 50 to 90% by weight, particularly 65 to 90% by weight.
80% by weight and the crosslinking agent is 50 to 10% by weight, in particular 3%
It can be in the range of 5 to 20% by weight. Further, the compounding amount of the coloring pigment does not impair the transparency of the clear coating film,
In addition, the glossy coating film of the clear metallic paint (B) can be set in a visible range through the coating film. The clear paint (C) has a viscosity of 10 to 2
0 seconds / Ford cup # 4/20 ° C, and adjust it by airless spray, air spray, electrostatic coating, etc.
The cured or uncured coating surface of the clear metallic coating (B) is usually a cured coating film having a thickness of 10 to 80 μm, especially 20 to 80 μm.
The coating can be performed so as to have a thickness of 60 μm. In the present method, after the clear paint (C) is applied in this manner, 3C1B, 3C2B, 3C3B
By heating at about 80 to about 170 ° C., preferably about 120 to about 160 ° C. for about 10 to 40 minutes in a manner, the clear coating alone or the clear coating and the underlying coating are cured together. Thus, an intended multilayer metallic coating film can be formed. The metallic coating film formed by the present method is a multilayer coating film formed by sequentially applying a metallic paint (A), a clear metallic paint (B) and a clear paint (C). The feature is that a "double metallic coating" that allows the metallic coating based on the metallic coating (A) adjacent to the lower layer to be visible through the metallic coating based on the clear metallic coating (B). It is formed. The metallic coating film alone of the metallic coating material (A) shows a brilliant feeling due to the metallic pigment contained therein, but in the present method, a coating film of the clear metallic coating material (B) is further formed on the coated surface. Therefore, the design effect can be significantly improved by the synergistic effect of the two coating films. That is, the alumina flakes contained in the clear metallic paint (B) are brilliantly shining, and in particular, exhibit the shine of diamonds scattered under sunlight, and the shine can be arbitrarily colored with an interference color. The metallic coating (A) adjacent to the lower layer, which can be seen through this coating and can be visually observed, has a synergistic effect with the metallic feeling of the metallic coating to form a multilayer coating excellent in design. it can. Further, since the content of alumina flakes in the clear metallic coating (B) is specified to be very small, the coating of the coating (B) has a glossy appearance and a mixed layer with an adjacent coating (also referred to as "mold"). No occurrence of metallic pigment sedimentation, metallic unevenness, etc. is observed at all, and a multi-layer metallic coating film having excellent smoothness and sharpness can be obtained. The present invention will now be described more specifically with reference to examples and comparative examples. All parts and percentages are on a weight basis, and film thicknesses are for cured coatings. The amount is a solid content. 1. Sample 1) Coated steel sheet (150 × 80 × 0.8 m in size) coated with cationic electrodeposition paint and intermediate paint, and the coating was cured.
m) was taken as an object to be coated. 2) Metallic paint (A) 70 parts of hydroxyl-containing acrylic resin, butyl melamine resin 3
0 parts, 30 parts of flaky aluminum powder and 5 parts of cyanine blue were mixed and dispersed in an organic solvent (xylene / ethyl acetate = 1/1 weight ratio), and the viscosity was 15 seconds / Ford cup #
Adjusted to 4/20 ° C. Underlayer concealment film thickness 12 μm. 3) Clear metallic paint (B) a): 70 parts of hydroxyl-containing acrylic resin, 30 parts of butylmelamine resin and titanium flake coated alumina flake (thickness 0.3 to 0.4 μm, longitudinal dimension 15 to 25 μm)
0.1 part was mixed and dispersed in an organic solvent (xylene / ethyl acetate = 1/1 weight ratio), and the viscosity was 13 seconds / Ford cup #
Adjusted to 4/20 ° C. b): 70 parts of a hydroxyl group-containing acrylic resin, 30 parts of butyl melamine resin and 0.15 part of titanium dioxide-coated alumina flake (same as above) were mixed with an organic solvent (xylene / ethyl acetate = 1).
/ 1 weight ratio) and adjusted to a viscosity of 13 seconds / Ford cup # 4/20 ° C. 4) Clear paint (C) 70 parts of a hydroxyl group-containing acrylic resin and 30 parts of a butyl melamine resin are mixed and dispersed in an organic solvent (xylene) to give a viscosity of 2
Adjusted to 0 sec / Ford Cup # 4/20 ° C. 2. EXAMPLES AND COMPARATIVE EXAMPLES Example 1 A metallic paint (A) was applied to an object to be coated to a thickness of 13 μm, left at room temperature for 3 minutes, and then a clear metallic paint (B) a) was applied to a thickness of 20 μm. 30 at 140 ° C
After heating for 2 minutes to cure both coatings, apply a clear coating (C) to the coated surface to a thickness of 35 μm, leave at room temperature for 3 minutes, and then heat at 140 ° C. for 30 minutes to clear coating. Was cured. The coating film of the clear metallic coating material (B) shows a red glow as if scattered with diamonds when exposed to sunlight, and the metallic coating film adjacent to the lower layer which can be seen through the coating film. Due to the synergistic effect with the metallic feeling of the metallic coating by (A), a multilayer coating excellent in design was able to be formed. Also,
There is no sedimentation of the metallic pigment of the clear-metallic paint (B) itself. The properties were also good. Example 2 A metallic paint (A) was applied to an object to be coated to a thickness of 13 μm, left at room temperature for 3 minutes, and then a clear metallic paint (B).
After b) was applied to a thickness of 20 μm and heated at 140 ° C. for 30 minutes to cure both coatings, a clear coating (C) was applied to the coated surface to a thickness of 35 μm and left at room temperature for 3 minutes. After heating at 140 ° C. for 30 minutes, the clear coating film was cured. The coating film of the clear metallic coating material (B) shows a red shine like a diamond strewn when exposed to sunlight, and the metallic coating film adjacent to the lower layer which can be seen through the coating film. Due to the synergistic effect with the metallic feeling of the metallic coating by (A), a multilayer coating excellent in design was able to be formed. Also,
There is no sedimentation of the metallic pigment of the clear-metallic paint (B) itself. The properties were also good. Example 3 A metallic paint (A) was applied to an object to be coated to a thickness of 13 μm, left at room temperature for 3 minutes, and then a clear metallic paint (B).
b) is coated at a film thickness of 20 μm, left at room temperature for 3 minutes, and then the clear paint (C) is coated at a film thickness of 35 μm on the coated surface, left at room temperature for 3 minutes, and then heated at 140 ° C. for 30 minutes. These three-layer coatings were simultaneously cured. The coating film of the clear metallic coating material (B) shows a red glow as if scattered with diamonds when exposed to sunlight, and the metallic coating film adjacent to the lower layer which can be seen through the coating film. Due to the synergistic effect with the metallic feeling of the metallic coating by (A), a multilayer coating excellent in design was able to be formed. Also,
There is no sedimentation of the metallic pigment of the clear-metallic paint (B) itself, and no gloss of the formed multi-layer coating film, no mixed layer with the adjacent coating film (also referred to as "mold"), no generation of metallic unevenness, and the like are observed at all. The properties were also good. COMPARATIVE EXAMPLE 1 A metallic paint (A) a) was applied to an object to be coated to a thickness of 13 μm, left at room temperature for 3 minutes, and a clear paint (C) was applied to the coated surface to a thickness of 35 μm. After leaving the mixture at room temperature for 3 minutes, it was heated at 140 ° C. for 30 minutes to simultaneously cure both coating films. Compared with Example 1, the formed multilayer coating film has less brilliant feeling, is inferior in design, and furthermore, the formed multilayer coating film is observed to have gloss, metallic unevenness, and the like.
The smoothness was not sufficient.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hirohisa Tashiro             Kansai Pain, 7-3 Satsuki-cho, Kanuma City, Tochigi Prefecture             G (72) Inventor Katsunori Sato             Kansai Pain, 7-3 Satsuki-cho, Kanuma City, Tochigi Prefecture             G F term (reference) 4D075 AE03 AE17 BB26Y CB04                       CB13 DA23 DC12 EA05 EA19                       EA43 EB22 EB32 EB35 EB38                       EB39 EB45 EC01 EC11 EC23

Claims (1)

Claims: 1. A metallic paint containing a metallic pigment (A), a clear-metallic paint (B) containing 0.03 to 0.5% by weight of alumina flakes, and a clear paint ( A method for forming a metallic coating film, wherein C) is sequentially applied.