JP2003096334A - Colored aluminum pigment, its production method, and coating material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a colored aluminum pigment which enables colorful tone design, has a high brightness, and can form a coating film having good appearance. SOLUTION: The colored aluminum pigment comprises aluminum flakes and a coloring pigment adhered to the surfaces of the aluminum flakes and has an average thickness of 0.1-0.4 μm and an average size of 5-20 μm. Preferably, the average thickness, average size, and aspect ratio (average size/average thickness) of the aluminum flakes are 0.01-0.1 μm, 5-20 μm, and 50-1,000, respectively. Preferably, the aluminum flakes are produced by vapor deposition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a colored aluminum pigment having an excellent finished appearance. For more details,
The present invention relates to colored aluminum pigments having an extremely low average thickness.

The present invention also relates to a method for producing the above colored aluminum pigment and a coating composition containing the above colored aluminum pigment.

[0003]

2. Description of the Related Art A coating film formed by using a metallic coating composition has a unique design in which a scale-like metallic pigment composition contained in the coating film reflects incident light from the outside and shines brightly. Show. The reflection of the light, combined with each color tone of the coating film, provides a unique appearance with excellent design.

Utilizing these characteristics, metallic pigment compositions containing aluminum flakes have been mainly used for metallic designs such as automotive finish, plastic finish, printing ink and resin molding. ing.

In addition, with the recent diversification of consumers' tastes, a highly bright metallic pigment composition having various colors colored in red, yellow, blue, orange, green, purple and the like and having an excellent finished appearance. Things are desired. However, since aluminum flakes are pigments that are originally achromatic and have a silver-white luster, they cannot satisfy the above-mentioned demands of consumers as they are.

Therefore, metallic pigment compositions containing inorganic flakes such as mica instead of aluminum flakes are also used. In this case, a coating film having a characteristic color tone such as a pearl tone can be obtained. However, a metallic pigment composition using inorganic flakes is not suitable for use as a main pigment composition because of its poor hiding power, and a coating film having a sufficient metallic luster cannot be obtained. It is not possible to sufficiently satisfy the above-mentioned demands of the person.

Further, in order to realize a colored metallic finish, it is also practiced to mix and use a coloring pigment and an aluminum flake or a pearl pigment. However, the color tone of the coating film obtained by this method has a design intermediate between that of the colored pigment composition and that of the metallic pigment composition, and the metallic feeling of the coating film is unavoidably deteriorated.

Many attempts have been made in order to solve these problems and satisfy the demands of consumers for various colors. For example, Japanese Patent No. 2622999, Japanese Patent No. 3026582, Japanese Patent Application Laid-Open No. 3-173318, Japanese Patent Application Laid-Open No. 7-220625, and Japanese Patent Application Laid-Open No. 10-35.
No. 672, Japanese Patent Laid-Open No. 9-67527, etc.
A colored metallic pigment composition in which the surface of a metal flake such as aluminum is coated with a metal oxide such as Ti or a Si oxide, and a method for producing the same are disclosed. However, the above-mentioned colored metallic pigment composition is limited in the color tone to be obtained, and does not allow a free color tone design that sufficiently satisfies the above-mentioned demands of consumers.

Further, as a colored aluminum pigment obtained by adhering a color pigment to the surface of aluminum flakes, there is disclosed in Japanese Patent Application Laid-Open No. 58-141248 and Japanese Patent Publication No. 5-508424.
Japanese Patent Laid-Open No. 1-315470, Japanese Patent Laid-Open No. 9-5
Colored aluminum pigments disclosed in Japanese Patent Publication No. 9532, etc. are mentioned. As a conventionally known colored aluminum pigment, a method in which a colored pigment is adhered to the surface of the aluminum flakes and further coated with a resin composition is generally used.

With respect to the colored aluminum pigment, various color tone designs are possible by selecting an appropriate coloring pigment or a combination of coloring pigments. Further, the colored aluminum pigment, diketopyrrolopyrrole-based, quinacridone-based, dioxazine-based, isoindolinone-based,
Organic pigments such as condensed azo type, slene type, perinone type, perylene type, phthalone type and phthalocyanine type, or inorganic pigments such as iron oxide and carbon black are generally used.

[0011] And, JP-A-9-124973,
JP-A-9-40885, JP-A-9-316357
Japanese Patent Laid-Open Publication No. 9-242242 discloses a colored aluminum pigment having improved adhesion between the aluminum flakes and the colored pigment for the purpose of solving problems such as discoloration, insufficient saturation, and complicated process.

However, since the colored aluminum pigment to which the above-mentioned colored pigment is adhered generally has a colored pigment layer having an average thickness of about 0.5 to 1 μm, the thickness of the entire colored aluminum pigment is larger than that of a normal aluminum pigment. . Therefore, when blended in a metallic coating composition, since the colored aluminum pigment is likely to stick out on the coating surface, the smoothness of the coating surface is impaired, and the coating film appearance often deteriorates. There is.

As a method for solving the above problems, a method of thinning the color pigment layer and a method of making the raw material aluminum flakes fine have been proposed. However, reducing the amount of the color pigment to be applied to make the color pigment layer thin causes a problem that the saturation deteriorates and the design property of the coating film is significantly impaired. However, it is not a sufficient solution because there is a problem that the image quality deteriorates and the feeling of metallitter is lost.

It is also conceivable to make the raw material aluminum flakes thin, and colored aluminum pigments in which thin aluminum flakes produced by a vapor deposition method are sandwiched between colored resin composition layers are also commercially available.

Further, in Japanese Patent Laid-Open No. 9-208867, a color pigment is attached to the surface of each metal particle, and the surface of the color metal pigment is coated with a polymer obtained by polymerizing a polymerizable monomer. A colored metal pigment composition having a thickness of 2 μm or less is disclosed.

However, even in the above-mentioned colored aluminum pigment, it is difficult to set the average thickness of the colored aluminum pigment to 0.4 μm or less. Therefore, the colored aluminum pigment is likely to stick out on the surface of the coating film, and the problem that the smoothness of the coating film surface is impaired and a good coating film appearance cannot be obtained has not been completely solved.

[0017]

Based on the above situation,
An object of the present invention is to provide a colored aluminum pigment which enables a variety of color tone designs while at the same time having high glitter and a good coating film appearance.

Another object of the present invention is to provide a coating composition using the above-mentioned colored aluminum pigment, which has various color tones, high brilliance and a good coating film appearance.

Another object of the present invention is to provide a method for producing the colored aluminum pigment.

[0020]

In order to solve the above-mentioned problems, the present inventors have proposed a colored aluminum pigment in which a variety of color tone designs of a type in which a colored pigment is adhered to the surface of aluminum flakes are easy to design. By using a colored aluminum pigment containing the above, and the average thickness of the colored aluminum pigment is 0.4 μm or less, the colored aluminum pigment is less likely to protrude on the coating surface, and the coating surface may be smoothed. After getting the idea, we made repeated studies. And
At the end of the study, in addition to thinning the aluminum flakes used as the base material, the adhesion between the color pigments and the aluminum flakes was improved so that sufficient chroma could be obtained even with a small amount of color pigments. By making the average thickness of the colored aluminum pigment 0.4 μm.
The inventors have found that the following can be achieved and completed the present invention.

That is, the colored aluminum pigment of the present invention is a colored aluminum pigment containing aluminum flakes and a colored pigment attached to the surface of the aluminum flakes, and the average thickness of the colored aluminum pigment is 0.1 to 0.1. The range is 0.4 μm, and the average particle size is 5 to 5.
It is in the range of 20 μm.

The aluminum flakes have an average thickness of 0.01 to 0.1 μm, an average particle size of 5 to 20 μm, and an aspect ratio (average particle size / average particle size).
The average thickness) is preferably in the range of 50 to 1000. Further, it is desirable that the aluminum flakes are aluminum flakes manufactured by a vapor deposition method.

The compound having an inorganic acid group is preferably adsorbed on the surface of the aluminum flakes. The surface of this color pigment is preferably coated with an amino compound having two amino groups in the molecule and not having a carboxyl group and / or a monobasic aromatic carboxylic acid. Further, the content of the color pigment is 1 with respect to 100 parts by mass of the aluminum flakes.
It is preferably in the range of 00 to 500 parts by mass.

The colored aluminum pigment of the present invention is
The surface of a colored aluminum pigment containing aluminum flakes and the colored pigment attached to the surface may be further coated with a resin composition. Here, the resin composition preferably contains a polymer synthesized from a polymerizable monomer. Further, the content of the resin composition is preferably in the range of 30 to 300 parts by mass with respect to 100 parts by mass of the aluminum flakes.

In the method for producing a colored aluminum pigment of the present invention, a solution containing a compound having an inorganic acid group is mixed with aluminum flakes so that the compound having the inorganic acid group is applied to the surface of the aluminum flakes. And a step of adsorbing the coloring pigment, which has two amino groups in the molecule and does not have a carboxyl group, and /
Alternatively, a step of dispersing in a non-polar solvent containing a monobasic aromatic carboxylic acid, aluminum flakes are added to a dispersion of a color pigment in a non-polar solvent and mixed, the color pigment is the surface of the aluminum flake. And the step of adhering to.

Further, in addition to the method for producing a colored aluminum pigment described above, the method for producing a colored aluminum pigment of the present invention further comprises adding a polymerizable aluminum pigment to a dispersion of a colored aluminum pigment comprising aluminum flakes having the colored pigment attached to the surface thereof. A monomer and a polymerization initiator are added and heated with stirring to polymerize the polymerizable monomer to synthesize a polymer,
A step of coating the surface of the colored aluminum pigment with a resin composition containing a polymer may be included.

Further, the coating composition of the present invention contains the above-mentioned colored aluminum pigment and a binder. Here, the content of the colored aluminum pigment is preferably in the range of 0.1 to 20 parts by mass with respect to 100 parts by mass of the binder.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail by showing embodiments.

<Definition and Arrangement of Terms> In the present specification, the aluminum flakes to which the coloring pigment is attached on the surface are referred to as the coloring aluminum pigment. Further, the coating composition is not limited to the ordinary coating composition containing an organic solvent, but includes an aqueous coating composition and a powder coating composition.

<Description of Aluminum Flakes> The average thickness of the aluminum flakes used in the present invention is 0.01.
Is preferably in the range of 0.1 to 0.1 μm, and 0.03 to
The range of 0.05 μm is more preferable. The average thickness is 0.
When the thickness is less than 01 μm, the aluminum flakes are crushed and finely divided in the step of producing the colored aluminum pigment, and the metallic feeling tends to be deteriorated. On the other hand, if the average thickness is more than 0.1 μm, the average thickness of the colored aluminum pigment may exceed 0.4 μm, and a good coating film appearance may not be obtained.

The aspect ratio (average particle size / average thickness) of the aluminum flakes used in the present invention is 50 to 50.
It is preferably in the range of 1000, and 100 to 500
Is more preferable. When the aspect ratio is less than 50, the metallic feeling of the coating film tends to be insufficient, and when the aspect ratio is more than 1000, there may arise a problem that the color tone of the coating composition is likely to change due to a dispersion operation. is there.

The average particle size of the aluminum flakes used in the present invention is preferably in the range of 5 to 20 μm, more preferably 7 to 15 μm. When the average particle size is smaller than 5 μm, the metallic feeling of the coating film tends to be insufficient. Further, if the average particle diameter is larger than 20 μm, the average particle diameter of the colored aluminum pigment naturally exceeds 20 μm, which may impair the appearance of the coating film.

The aluminum flakes used in the present invention are preferably aluminum flakes produced by a vapor deposition method. The aluminum flakes produced by the vapor deposition method have an average thickness of 0.02 to 0.05 μm.
m, the aspect ratio is in the range of 100 to 500, and the average particle size is in the range of 5 to 20 μm are commercially available and can be suitably used in the present invention.

Recently, in addition to the aluminum flakes formed by the vapor deposition method, the average thickness of 0.01 to 0.
Aluminum flakes having an aspect ratio of 50 to 1000 and an average particle diameter of 5 to 20 μm are produced, and the aluminum flakes can also be suitably used in the present invention. .

Here, the average particle diameter of the colored aluminum pigment is, for example, SALD-110 manufactured by Shimadzu Corporation.
It can be measured by a laser diffraction method using 0. The average thickness of the colored aluminum pigment is, for example, scanning electron microscope JXA-88 manufactured by JEOL Ltd.
00 can be measured by observing a cross section of the colored aluminum pigment.

The aluminum flakes used in the present invention may be composed of aluminum alone or an aluminum-based alloy, and the purity thereof is not particularly limited.

Even if the metal flakes or the flakes for metallic pigments made of a material other than metal are used in place of the aluminum flakes, the same average thickness and aspect ratio as those of the aluminum flakes used in the present invention can be realized. It would be easily understood by those skilled in the art that, if possible, the same effect as aluminum flakes can be obtained.

The surface of the aluminum flakes of the present invention may have a grinding aid adhering thereto, which is not preferable from the viewpoint of the adhesion with the color pigment. Unsaturated fatty acids are usually used as grinding aids. As the unsaturated fatty acid used here, for example, oleic acid,
Examples thereof include linoleic acid, linoleic acid, ricinoleic acid, elaidic acid, zomarinic acid, gadoleic acid and erucic acid. The amount of the grinding aid varies depending on the application and is not particularly limited, but generally, the aluminum flakes 10 are used.
The range of 0.1 to 20 parts by mass is usually used with respect to 0 parts by mass, and the range of 0.5 to 10 parts by mass is preferable.

<Description of Coloring Pigment> The coloring raw material used in the present invention is not particularly limited, and any coloring pigment generally used for coloring metal pigments can be suitably used. Specific examples include phthalocyanine, halogenated phthalocyanine,
Quinacridone, diketopyrrolopyrrole, isoindolinone, azomethine metal complex, perylene, perinone, indanthrene, anthraquinone, dioxazine, benzimidazolone, condensed azo, triphenylmethane, quinophthalone, anthrapyrimidine, titanium oxide, iron oxide, carbon Black, ultramarine, dark blue, cobalt blue, chrome green, bismuth vanadate, spinel and the like can be mentioned.

The color pigment preferably has a primary particle diameter in the range of 0.01 to 0.1 μm, and preferably 0.0
More preferably, it is in the range of 2 to 0.05 μm. When the primary particle size is less than 0.01 μm, it tends to be difficult to disperse the pigment, and when the primary particle size exceeds 0.1 μm, it tends to be difficult to uniformly adhere to the aluminum flakes.

Here, the content of the color pigment in the colored aluminum pigment used in the present invention is preferably in the range of 100 to 500 parts by mass, and 200 to 400 parts by mass with respect to 100 parts by mass of the aluminum flakes. Ranges are more preferred. When the content of the color pigment is less than 100 parts by mass, sufficient saturation tends not to be obtained, and when the content of the color pigment exceeds 500 parts by mass, the appearance of the coating film is impaired or the color pigment is colored. Dropout may occur easily.

In the case of a chromatic aluminum pigment such as the colored aluminum pigment of the present invention, a preferable range of saturation is 5 <(a ² + b ² ) ^1/2 <60. here,
(A ² + b ² ) ^1/2 is a colorimetric value measured by a color difference meter of a coated plate coated with a coating material containing a chromatic color aluminum pigment alone under the condition that the base is sufficiently hidden.

The state of adhesion of the coloring pigment on the surface of each particle of the aluminum flakes used in the present invention may be such that the surface of the particle is partially covered, but the color pigment should be uniformly adhered to the entire surface of the particle. preferable. Further, it is more preferable that the thickness of the color pigment layer on the surface of the particles is one particle of the color pigment. By uniformly adhering the coloring pigment to the entire surface of the aluminum flake particles, the particles of the individual aluminum flakes can be colored efficiently and vividly, and the fixing of the coloring pigment to the surface of the metal pigment becomes easy.

<Explanation of Method for Adhering Color Pigment to Aluminum Flake> The method for adhering the color pigment to the aluminum flake used in the present invention is not particularly limited, but, for example, JP-A-1-315470. Japanese Patent Laid-Open No. 9-40885 and Japanese Patent Laid-Open No. 9-595.
The method described in JP-A No. 32, JP-A-9-124973, etc. can be preferably used.

Further, in order to improve the adhesion between the aluminum flakes used in the present invention and the color pigment, it is desirable that the aluminum flakes do not contain organic additives such as fatty acids. Further, it is desirable to adsorb a compound containing an inorganic acid group on the surface of the aluminum flakes in advance.

The inorganic acid group adsorption layer functions to increase the number of active points on the surface of the aluminum flakes to facilitate the adhesion of the coloring pigment and at the same time enhance the adhesion. As a result, the color pigment can be uniformly and firmly attached to the surface of the aluminum flakes.

Preferred examples of the inorganic acid group (hereinafter, simply referred to as an inorganic acid group) contained in the compound attached to the surface of the aluminum flakes used in the present invention include carbonic acid, boric acid, sulfuric acid, nitric acid, phosphoric acid and phosphorous acid. Hypophosphorous acid, silicic acid, chromic acid, molybdic acid, tungstic acid,
Examples thereof include inorganic acid groups possessed by titanic acid, vanadic acid, tantalic acid, and condensates thereof. Among the inorganic acid groups, inorganic acids such as phosphoric acid, molybdic acid, tungstic acid, vanadic acid, and condensates thereof such as pyrophosphoric acid, polyphosphoric acid, polymolybdic acid, polytungstic acid, phosphomolybdic acid, and phosphotungstic acid. Acid groups are particularly preferred. Here, polymolybdic acid and polytungstic acid are represented by the general formula M _X O _Y .mH ₂ O ₂ .nH ₂ O
(Here, M represents metal Mo or metal W,
m, n, X and Y represent positive integers) and hydrogen peroxide and a peroxide polyacid derived from metal Mo or metal W.

The method for adsorbing the inorganic acid group on the surface of the aluminum flakes used in the present invention is not particularly limited, but for example, an acid having an inorganic acid group or a compound such as an ammonium salt may be mixed with water or alcohol. System solvents, glycol ether solvents, ketone solvents, dissolved in a hydrophilic solvent such as, is added to the mixture of the organic solvent and aluminum flakes, in a slurry state or paste state, stirring and mixing or kneading,
A method of reacting and adsorbing an inorganic acid group on the surface of the aluminum flake is preferable.

The amount of the inorganic acid group to be adsorbed on the surface of the aluminum flakes used in the present invention is preferably in the range of 0.05 to 5 parts by mass with respect to 100 parts by mass of the aluminum flakes. When the amount of the inorganic acid group is less than 0.05 parts by mass, the color pigment tends not to be sufficiently attached to the surface of the aluminum flake, and when the amount of the inorganic acid group exceeds 5 parts by mass, the aluminum flake is formed. Problems such as agglomeration may occur.

The amount of the solvent used in the present invention is
300 to 3 with respect to 100 parts by mass of aluminum flakes
It is preferably in the range of 000 parts by mass, and 500 to 1
The range of 500 parts by mass is more preferable. If the amount of the solvent used is less than 300 parts by mass, the viscosity of the solution tends to be too high, and it becomes difficult for the aluminum flakes to diffuse uniformly. If the amount of the solvent used exceeds 3000 parts by mass, the time required for adsorption Tends to be too long.

Further, it is also preferable to coat the surface of the color pigment used in the present invention with an amino compound having two amino groups in the molecule and not having a carboxyl group and / or a monobasic aromatic carboxylic acid. .

As described above, even by coating the surface of the color pigment with the amino compound and / or the carboxylic acid, the hetero-aggregation phenomenon in a non-polar solvent is utilized to separate the color pigment from the aluminum flakes. The adhesiveness can be increased.

Examples of the amino compound having two amino groups and no carboxyl group in the molecule used in the present invention include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, Such as aliphatic diamine having 6 to 12 carbon atoms, 1,7-diaminoheptane, 1,8-
Diaminooctane, 1,10-diaminodecane, 1,1
2-diaminododecane, o-phenylenediamine, m-
Phenylenediamine, p-phenylenediamine, 1,8
-Diaminonaphthalene, 1,2-diaminocyclohexane, stearyl propylene diamine, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N
-Β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane and the like can be preferably used.

Among the above amino compounds, the number of carbon atoms is 6 to 1.
2 aliphatic diamines, N-β- (aminoethyl) -γ-
One or more selected from the group consisting of aminopropyltrimethoxysilane and N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane are excellent in the effect of improving the adhesion between the color pigment and the aluminum flakes. Therefore, it is particularly preferable.

As the above-mentioned monobasic aromatic carboxylic acid,
For example, benzoic acid, vinyl benzoate, salicylic acid, aminobenzoic acid (anthranilic acid, m-aminobenzoic acid,
p-aminobenzoic acid, etc.), 3-amino-4-methylbenzoic acid, aminohydroxybenzoic acid (p-aminosalicylic acid, etc.), naphthoic acid (1-naphthoic acid, 2-naphthoic acid, etc.), naphthenic acid, aminonaphthoic acid. Acids (3-amino-2-naphthoic acid, etc.), cinnamic acid, aminocinnamic acid, etc. can be preferably used.

Among the above carboxylic acids, benzoic acid, aminobenzoic acid, aminohydroxybenzoic acid, naphthoic acid,
One or more selected from the group consisting of aminonaphthoic acid, cinnamic acid, and aminocinnamic acid are particularly preferable because they have an excellent effect of improving the adhesion between the color pigment and the aluminum flakes.

In the colored aluminum pigment of the present invention, the total content of the amino compound having two amino groups in the molecule and having no carboxyl group and / or the monobasic aromatic carboxylic acid is the color pigment. It is preferably in the range of 0.2 to 100 parts by mass with respect to 100 parts by mass,
The range of 0.5 to 50 parts by mass is more preferable.

When the total content of the amino compound and / or the carboxylic acid is less than 0.2 part by mass, it may be difficult to adhere the color pigment to the aluminum flakes with sufficient adhesion strength. Further, when the total content of the amino compound and / or the carboxylic acid exceeds 100 parts by mass, the coloring pigment is adhered to the aluminum flakes and then the surface is coated with a resin. Tend to be insufficiently fixed to the coating composition, and excess amino compound and / or carboxylic acid may cause thickening of the coating composition, and the weather resistance of the coating film tends to deteriorate. .

In addition to the amino compound and / or the carboxylic acid, a dispersant such as a surfactant or a chelate compound and an ultraviolet absorber may be attached to the color pigment used in the present invention.

The method for coating the surface of the color pigment with the amino compound and / or the carboxylic acid is not particularly limited, but, for example, it has two amino groups in the molecule and a carboxyl group is formed. Preferred is a method comprising the step of dispersing a colored pigment in a non-polar solvent containing an amino compound and / or a monobasic aromatic carboxylic acid that does not have it. Further, a surfactant, a dispersant such as a chelate compound, an ultraviolet absorber, and the like may be added to the nonpolar solvent, if necessary.

Here, the non-polar solvent used in the present invention is preferably an aliphatic hydrocarbon, an aromatic hydrocarbon or a mixture thereof having a boiling point in the range of 100 to 250 ° C. Specific examples of the non-polar solvent include normal paraffin, isoparaffin, toluene, xylene, solvent naphtha,
Examples include kerosene, mineral spirits, and petroleum benzine. Further, if necessary, a small amount of an alcohol solvent or an ester solvent may be added to assist the dispersion of the color pigment.

As a method for dispersing the color pigment,
Although not particularly limited, a dispersion method using a grinding medium such as a ball mill, a bead mill and a sand mill is preferable.

The amount of the solvent used is 100
It is preferably in the range of 300 to 3000 parts by mass, more preferably in the range of 500 to 1500 parts by mass, relative to parts by mass. If the amount of the solvent used is less than 300 parts by mass, the viscosity of the dispersion tends to be too high, and it may be difficult for the color pigment to uniformly diffuse. If the amount of the solvent used exceeds 3000 parts by mass, the time required for adhesion may increase. Tends to be too long.

<Description of Method for Adhering Color Pigment to Aluminum Flake> In the present invention, the method for adhering the color pigment to the aluminum flake is not particularly limited, and a conventionally known method can be used.
It is preferred to include the step of mixing the aluminum flakes with a dispersion of the color pigment in a non-polar solvent and adhering the color pigment to the surface of the aluminum flake.

As the aluminum flakes used in the present invention, aluminum flakes having an inorganic acid group adsorbed on the surface are preferable. Further, the color pigment used in the present invention is a color pigment whose surface is coated with an amino compound having two amino groups in a molecule and not having a carboxyl group and / or a monobasic aromatic carboxylic acid. Is preferred.

Here, the non-polar solvent used in the present invention is preferably an aliphatic hydrocarbon, an aromatic hydrocarbon or a mixture thereof having a boiling point in the range of 100 to 250 ° C. Specific examples of the non-polar solvent include normal paraffin, isoparaffin, toluene, xylene, solvent naphtha,
Examples include kerosene, mineral spirits, and petroleum benzine. Further, if necessary, a small amount of an alcohol solvent or an ester solvent may be added to assist the dispersion of the color pigment.

As a method of dispersing the aluminum flakes and the color pigment, a dispersion method using a grinding medium such as a ball mill, a bead mill, a sand mill is preferable, but a dispersion method using stirring with a stirrer or a disper is also preferable.

When using aluminum flakes having an inorganic acid group adsorbed thereon, the aluminum flakes are added to a slurry containing a color pigment, and then solid-liquid separated and kneaded into a paste by a kneader mixer or the like. Is also preferable.

The colored aluminum pigment thus obtained shows a vivid color tone because the colored pigment is uniformly attached to the surface of each particle of the aluminum flakes.
It also has an excellent metallic luster.

Here again, the amount of non-polar solvent used is 300 to 3000 with respect to 100 parts by weight of the aluminum flakes.
It is preferably in the range of parts by mass, 500 to 1500
The range of parts by mass is more preferable. The amount of solvent used is 300
If it is less than parts by mass, the viscosity of the dispersion tends to be too high, and it tends to be difficult for the aluminum flakes and the color pigment to diffuse uniformly. If the amount of solvent used exceeds 3000 parts by mass, the time required for adhesion is long. Tends to be too much.

<Explanation of Film of Resin Component> The surface of the colored aluminum pigment containing the aluminum flakes used in the present invention and the colored pigment attached to the surface is further covered with a film of the resin composition. Good.

The resin composition comprises a polymerizable monomer i
It is preferable that the resin composition contains a polymer synthesized by n-situ polymerization. Where in-si
Tu polymerization means polymerizing a polymerizable monomer in the step of producing a colored aluminum pigment to polymerize it, and specifically, the aluminum flakes having the colored pigment attached thereto are dispersed in a solvent to form a slurry. A polymerizing monomer is added to the above state and stirred and mixed, and a polymerization initiator is further added to cause a polymerization reaction to deposit a polymer on the surface of the aluminum flakes.

Here, the resin composition plays a role in fixing the color pigment to the aluminum flakes by penetrating into the gap between the color pigment and the aluminum flakes, and improving the adhesion between the color pigment and the aluminum flakes. As well as weathering, water resistance of colored aluminum pigment,
It also plays a role in improving chemical resistance, electrical insulation, suitability as a powder coating, storage stability, etc.

The resin composition may be composed only of a polymer synthesized by in-situ polymerization from a polymerizable monomer, and may contain other components in addition to the polymer.

The polymerizable monomer is not particularly limited, but specific examples include acrylic acid, methacrylic acid, methyl methacrylate, butyl acrylate,
2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, acrylic acid-
2-hydroxybutyl, 2-methoxyethyl acrylate, 2-diethylaminoethyl acrylate, butyl methacrylate, octyl methacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1, 9-nonanediol diacrylate,
Neopentyl glycol diacrylate, tripropylene glycol diacrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate,
Pentaerythritol triacrylate, trisacryloxyethyl phosphate, ditrimethylolpropane tetraacrylate, styrene, α-methylstyrene,
Vinyltoluene, divinylbenzene, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, maleic acid, crotonic acid, itaconic acid, polybutadiene, linseed oil, soybean oil, epoxidized soybean oil, epoxidized polybutadiene, cyclohexene vinyl mono Examples thereof include oxides and divinylbenzene monooxide.

The content of the resin composition coated on the colored aluminum pigment is 30 to 30 relative to 100 parts by mass of the aluminum flakes contained in the colored aluminum pigment.
It is preferably in the range of 0 parts by mass, more preferably in the range of 50 to 200 parts by mass. Content of resin composition is 3
When it is less than 0 parts by mass, the color pigment tends to drop off, and when the content of the resin composition exceeds 300 parts by mass, the metallic feel and the smoothness of the coating film tend to be deteriorated.

<Coating Method of Colored Aluminum Pigment with Resin Composition> In the present invention, the method of coating the colored aluminum pigment with the resin composition is not particularly limited, and a conventionally known method can be used. , A step of dispersing a colored aluminum pigment containing aluminum flakes and the colored pigment adhered to the surface in a solvent, and adding the polymerizable monomer and the polymerization initiator to the dispersion. And heating with stirring to polymerize the polymerizable monomer to synthesize a polymer, and coat the surface of the colored aluminum pigment with a resin composition containing the polymer.

As the dispersion, the dispersion obtained in the step of adhering the color pigment to the aluminum flakes may be used as it is, and the dispersion may be once solid-liquid separated to form a paste or powder. You may use what dispersed the aluminum pigment again in the solvent.

Here, the solvent is preferably a hydrocarbon solvent or an alcohol solvent, and among these solvents, a hydrocarbon solvent is particularly preferable. Specific examples of the hydrocarbon solvent include hexane, heptane, octane, mineral spirits, and other aliphatic hydrocarbon solvents, benzene,
Aromatic hydrocarbon solvents such as toluene, solvent naphtha, and xylene are included.

The amount of the solvent used is 1
It is preferably in the range of 300 to 3000 parts by mass, more preferably in the range of 500 to 1500 parts by mass, relative to 00 parts by mass. If it is less than 300 parts by mass, the viscosity of the reaction liquid tends to be too high, and it becomes difficult to uniformly diffuse the reaction components. If it exceeds 3000 parts by mass, the reaction time tends to be too long.

The polymerization initiator is preferably a polymerization initiator such as benzoyl peroxide, isobutyl peroxide, azobisisobutyronitrile. The polymerization reaction is preferably carried out in an oxygen-free atmosphere, particularly preferably in an inert gas such as nitrogen or argon.

Further, the reaction temperature of the polymerization reaction is 50 to 15
It is preferably in the range of 0 ° C, more preferably in the range of 70 to 100 ° C. When the reaction temperature is lower than 50 ° C, the efficiency of the polymerization reaction tends to be insufficient, and when the reaction temperature exceeds 150 ° C, the polymerization reaction rapidly proceeds, so that the amount of the pigment on the surface of the colored aluminum pigment is sufficient. The polymer tends to not precipitate.

The reaction time of the polymerization reaction is 0.5 to 2
It is preferably in the range of 4 hours. Reaction time 0.5
If the time is less than the time, the polymerization reaction tends not to proceed sufficiently, and even if the reaction time exceeds 24 hours, the polymerization reaction hardly progresses any more and conversely the productivity per hour decreases.

Here, the amount of the polymerization initiator compounded is preferably 0.5 to 20 parts by mass as a ratio to 100 parts by mass of the resin composition coated on the surface of the aluminum flakes. If the amount of the polymerization initiator is too small, the polymerization reaction may not proceed and the expected amount of the film may not be formed, and if the amount of the polymerization initiator is too large, the polymerization may rapidly progress and The flakes tend to agglomerate and tend to be disadvantageous in terms of color tone.

After the polymerization reaction is completed, it is preferable to remove most of the solvent from the dispersion using a filter or the like to obtain a paste. The paste-like colored metallic pigment composition can be used as it is when used in a general paint, but when used in a powder paint, the paste-like colored aluminum pigment is depressurized to below atmospheric pressure. It is preferable that the solvent is further removed by heating in the range of 50 to 150 ° C. with mixing to obtain a powder having a solvent content of 5% by mass or less, preferably 2% by mass or less.

As the filtering device, a filter press, a pan filter, etc. can be preferably used. For heating and mixing under reduced pressure, a vacuum kneader mixer, a vacuum dryer or the like can be preferably used.

In the colored aluminum pigment of the present invention, if necessary, a pigment dispersant, a defoaming agent, an anti-settling agent,
You may mix | blend additives, such as a curing catalyst, and coloring pigments other than the coloring aluminum pigment used for this invention.

<Description of Size of Colored Aluminum Pigment>
The colored aluminum pigment of the present invention contains aluminum flakes and a colored pigment attached to the surface of the aluminum flakes. That is, the colored aluminum pigment of the present invention is a composition containing the colored aluminum pigment.

The average thickness of the colored aluminum pigment of the present invention must be in the range of 0.1 to 0.4 μm,
It is preferably in the range of 0.15 to 0.35 μm.
The average particle size of the colored aluminum pigment of the present invention is 5 to
It must be in the range of 20 μm, and preferably in the range of 7 to 15 μm.

When the average thickness is less than 0.1 μm, the colored aluminum pigment is deformed or crushed during the manufacturing process of the coating composition using the colored aluminum pigment, and the color tone is impaired. The average thickness is 0.4 μm.
When it exceeds, the colored aluminum pigment is likely to project on the surface of the coating film, and a good coating appearance cannot be obtained. And
When the average particle size is less than 5 μm, the metallic feeling of the coating film becomes insufficient. Further, when the average particle size is larger than 20 μm, the appearance of the coating film is impaired.

By using the colored aluminum pigment of the present invention containing the colored aluminum pigment satisfying the above conditions, the colored aluminum pigment is less likely to project on the surface of the coating film. Therefore, the surface of the coating film becomes smooth, and a coating film having high glitter and a good coating appearance can be obtained.

<Description of Coating Composition of the Present Invention> The coating composition of the present invention contains the colored aluminum pigment of the present invention and a binder.

The binder used in the coating composition of the present invention is not particularly limited, and binders generally used in coating compositions containing an aluminum pigment can be used.
As the binder used in the coating composition of the present invention, one kind or two or more kinds of resins can be used.

Specific examples of the binder used in the coating composition of the present invention include thermosetting acrylic resin / melamine resin, thermosetting acrylic resin / CAB / melamine resin, thermosetting polyester (alkyd) resin / melamine resin. ,
Examples thereof include combinations of resins such as thermosetting polyester (alkyd) resin / CAB / melamine resin, isocyanate-curing urethane resin / room temperature-curing acrylic resin, water-diluting acrylic emulsion resin / melamine resin.

The solvent used in the coating composition of the present invention is not particularly limited to an organic solvent, and a solvent generally used in a coating composition containing a colored aluminum pigment can be used, and hydrophilic solvent such as water can be used. The solvent can also be used. Further, when the coating composition of the present invention is a powder coating composition, it may not contain a solvent.

Specific examples of the solvent usable in the coating composition of the present invention include mineral spirit, hexane,
Aliphatic hydrocarbons such as heptane, cyclohexane and octane, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as chlorobenzene, trichlorobenzene, perchlorethylene and trichloroethylene, methanol, ethanol and n-propyl. Alcohols, alcohols such as n-butanol, ketones such as n-propanone and 2-butanone, esters such as ethyl acetate and propyl acetate, organic solvents such as ethers such as tetrahydrofuran, diethyl ether and ethyl propyl ether , Or a hydrophilic solvent such as water. It is preferable to use two or more kinds of these solvents in a mixture, and the composition of the solvent is determined in consideration of the solubility of the binder, the film forming characteristics, the coating workability and the like.

When the coating composition of the present invention is a solution type, the amount of the solvent used is preferably in the range of 50 to 3000 parts by mass, and 250 to 1000 parts by mass with respect to 100 parts by mass of the colored aluminum pigment. Ranges are more preferred. If it is less than 50 parts by mass, the viscosity of the coating composition becomes too high, and it tends to be difficult for the colored aluminum pigment and the binder to uniformly diffuse, which may cause a problem in coating workability. On the other hand, if the amount exceeds 3000 parts by mass, the solid content of the coating film becomes too thin, and the metallic feel and brightness of the coating film tend to decrease.

When the coating composition of the present invention is used as a powder coating material, the colored aluminum pigment in the form of a paste is mixed at a pressure of less than atmospheric pressure while mixing 50 to 150.
It is preferable to further remove the solvent by heating in the range of ° C to obtain a powdery solvent content of 5% by mass or less, preferably 2% by mass or less.

If necessary, the coating composition of the present invention may contain additives such as a pigment dispersant, a defoaming agent, an anti-settling agent, a curing catalyst, and other coloring agents other than the colored aluminum pigment of the present invention. You may mix a pigment.

The amount of the colored aluminum pigment compounded in the coating composition of the present invention is preferably in the range of 0.1 to 20 parts by mass with respect to 100 parts by mass of the binder,
The range of 0.2 to 5 parts by mass is more preferable. When the blending amount is less than 0.1 parts by mass, the design property excellent in metallic feeling may not be obtained, and when the blending amount exceeds 20 parts by mass, the sharpness of the coating film tends to be deteriorated. is there.

The coating composition of the present invention can be suitably used in the fields of automobiles, motorcycles, bicycles, aircraft, ships, other mechanical products, electric products, communication devices, daily necessities, stationery, cosmetics, buildings and the like. it can.

[0102]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

<Example 1><Preparation of colored aluminum pigment> Commercially available colored pigment (IRGAZIN manufactured by Ciba Specialty Chemicals Co., Ltd.)
DPP RUBINE TR) 10 g and benzoic acid 0.5
g, dispersant (Kawaken Fine Chemicals Co., Ltd., Planeact ALM) 0.5 g, mineral spirits 10 g
Was added, and the mixture was subjected to ball mill dispersion for 24 hours in a pot mill having a diameter of 5 cm and an internal volume of 500 cc into which 500 g of glass beads having a diameter of 1 mm was inserted.

Thereafter, 25 g (2.5 g as a metal content) of aluminum pigment (KM100, average thickness 0.03 μm, average particle size 10 μm, aluminum content 10%) produced by a commercially available vapor deposition method, phosphoric acid was used. 1
g, isopropanol (hereinafter referred to as IPA) 3 g
It was dissolved in the mixture and was pretreated by adding it to the pot mill, 20 g of mineral spirit was further added, and the mixture was further ball-milled for 1 hour.

The resulting slurry is mixed with mineral spirits 5
The composition was separated from the glass beads by washing out with 00 g, and then filtered to obtain a composition containing an aluminum pigment having a coloring pigment attached (hereinafter referred to as a primary coloring aluminum pigment).

20 g (as a solid content) of the primary colored aluminum pigment obtained in the above step was dispersed in 200 g of mineral spirit, and 0.5 g of acrylic acid, 0.5 g of trimethylolpropane triacrylate, and styrene of 0.1 g were added to the obtained slurry. 5 g and epoxidized polybutadiene 0.5 g were added, and azobisisobutylnitrile as a polymerization initiator was added as a polymerization initiator while heating and stirring at 80 ° C. in nitrogen.
05 g was added to polymerize the monomer, and the polymer was deposited on the surface of the primary colored aluminum pigment.

After the above treatment, the slurry was subjected to solid-liquid separation to obtain a paste-like colored aluminum pigment having a solid content of 40%.

<Preparation of coating composition> Composition of coating composition (parts represent parts by weight) Colored aluminum pigment (solid content) 10 parts Thermosetting acrylic resin (solid content) 80 parts Butylated melamine resin (Solid content) 20 parts Ethyl acetate 100 parts Toluene 100 parts IPA 100 parts Next, using the obtained colored aluminum pigment, a coating composition having the above composition was prepared.

<Examples 2 to 5, Comparative Examples 1 to 5> Example 1
Colored aluminum pigments were produced under the conditions shown in Tables 1 and 2 in the same manner as in. Next, a coating composition was prepared with the same composition as in Example 1 using the colored aluminum pigment.

<Performance Evaluation and Composition Analysis of Coating Composition>
The performance and composition of the obtained coating composition were evaluated based on the following test methods. The obtained evaluation results are shown in Tables 1 and 2.

(I) Average Particle Size of Colored Aluminum Pigment The average particle size is SALD-1100 manufactured by Shimadzu Corporation.
Was measured by a laser diffraction method.

(Ii) Average Thickness of Colored Aluminum Pigment The average thickness is the scanning electron microscope JX manufactured by JEOL Ltd.
It was measured by observing a cross section of a colored aluminum pigment using A-8800.

(Iii) Measurement of Resin Coating Amount of Colored Aluminum Pigment The solid content of the slurry containing the colored aluminum pigment before and after the resin coating step was measured and calculated from the increment of the solid content.

<Preparation of coating film> First, a surface-treated steel sheet (JIS G3310 steel sheet on which a cationic electrodeposition coating for automobiles has been electrodeposited as a base material to which the obtained coating composition is applied is subjected to a zinc phosphate chemical conversion treatment. Prepared by applying an intermediate coating of polyester resin / melamine resin.

Next, using the coating compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 5 as a coating composition for a base coat, coating was performed until the base of the base material was completely hidden to form a base coat. Obtained.

Formulation of coating composition for clear coat (parts represent parts by mass) Thermosetting acrylic resin (solid content) 80 parts Butylated melamine resin (solid content) 20 parts Ethyl acetate 50 parts Toluene 50 parts 50 parts of IPA and then 2 parts of the coating composition for clear coat having the above-mentioned composition
Coat 1 bake method, air spray painting, 140 ℃
And baked for 30 minutes to form a metallic coating film. In addition,
The thickness of the clear coat layer was adjusted to 40 μm.

<Evaluation of Performance of Coating Film> The performance of the obtained coating film was evaluated based on the following test methods. The obtained evaluation results are shown in Tables 1 and 2.

(I) Measurement of concealed film thickness The minimum film thickness of the base coat layer, which completely conceals the base material of the substrate, was measured by PIG- manufactured by BYK Gardner GmbH.
Using a Universal type film thickness meter, it was measured by a direct observation method to obtain a hidden film thickness.

(Ii) Appearance Evaluation The appearance of the coating film obtained was visually observed and evaluated on a scale of 5 according to the following criteria.

5: The surface of the coating film is mirror-like and very smooth 4: The surface of the coating film is close to mirror-like and almost no unevenness is seen 3: A little unevenness is seen on the surface of the coating 2: Coating Substantial unevenness is seen on the film surface 1: The surface of the coating film is wavy and many unevenness is seen (iii) Measurement of specular reflectance Deflection gloss meter (Suga Test Instruments Co., Ltd., UGV / 5K) Type) according to JIS K5400, incident angle 60 °,
The specular reflectance of the coating film surface was measured at an acceptance angle of 60 °.

(Iv) Measurement of Saturation Using a color difference meter (SM-6-CH type manufactured by Suga Test Instruments Co., Ltd.), a coating film was formed by a 45 ° -0 ° system L ^* a ^* b ^* colorimetric system. Was measured ((a ² + b ² ) ^1/2 ).

(V) Evaluation of metallic feeling The appearance of the coating film obtained was visually observed and evaluated on a scale of 5 according to the following criteria.

5: Very bright glitter feeling on the surface of the coating film 4: Very bright glitter feeling on the surface of the coating film 3: A little glittering feeling on the surface of the coating film 2: Coating Glittering sensation on the film surface is hardly felt 1: Glittering sensation on the coating film surface is hardly felt

[0124]

[Table 1]

[0125]

[Table 2]

Here, Tables 1 and 2 show the composition of the colored aluminum pigment and the evaluation results of the colored aluminum pigment and the coating film. Further, in Tables 1 and 2, the blending amount described in * 1 is expressed in parts by mass relative to 100 parts by mass of the aluminum flakes, and the saturation described in * 2 is expressed in (a ² + b ² ) ^1/2. , RUBINETR
IRGA manufactured by Ciba Specialty Chemicals Co., Ltd.
ZIN DPP RUBINE TR
R-3 is Toyo Ink Mfg. Co., Ltd. CYANINE BLU
EMR-3, 5GLT is Ciba Specialty Chemicals IRGAZINE YELLOW 5G
It means LT.

From the results shown in Table 1 and Table 2, Example 1
It can be seen that the average thickness of the colored aluminum pigments contained in the coating compositions obtained in Examples 1 to 5 is significantly smaller than that in Comparative Examples 1 to 5. As a result, it can be seen that the concealed film thickness of the coating films obtained in Examples 1 to 5 is significantly smaller than that in Comparative Examples 1 to 5.

Further, in the coating films obtained in Examples 1 to 5, since the amount of the colored aluminum pigment protruding from the coating film was small, either visual appearance evaluation, specular reflectance or visual metallic feeling evaluation was conducted. It can be seen that one or more evaluation items are significantly superior to Comparative Examples 1 to 5.

The embodiments and examples disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[0130]

In the present invention, the average thickness is 0.01.
It could not be obtained conventionally by using very thin aluminum flakes in the range of 0.1 μm to 0.1 μm, and by further improving the adhesion of the aluminum flakes and the color pigment to reduce the thickness of the color pigment layer. It has become possible to produce colored aluminum pigments having an average thickness in the range of 0.1 to 0.4 μm.

The colored aluminum pigment of the present invention has a structure in which the colored pigment is attached to the aluminum flakes, so that various color tone designs are possible. Further, the colored aluminum pigment of the present invention is excellent in high brilliance because the colored pigment layer is thin. Further, since the colored aluminum pigment of the present invention has a small average thickness of the colored aluminum pigment, the colored aluminum pigment is unlikely to project onto the surface of the coating film, and the coating film can have a good appearance in which the surface of the coating film is smooth.

Further, since the coating composition of the present invention contains the above-mentioned colored aluminum pigment, in the coating film using the coating composition, the colored aluminum pigment is unlikely to project onto the surface of the coating film and the coating surface is smooth. Becomes for that reason,
A coating film using the coating composition of the present invention has various color tones, high glitter and good appearance.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4J037 AA05 CA14 CB09 CB16 CB28                       CC16 CC23 DD05 DD10 DD23                       EE03 EE04 EE12 EE23 EE28                       EE43 FF02 FF09                 4J038 CG001 DA161 DD001 DG001                       HA066 KA08 KA15 KA20                       NA01

Claims (13)

[Claims] 1. A colored aluminum pigment containing aluminum flakes and a colored pigment attached to the surface of the aluminum flakes, wherein the colored aluminum pigment has an average thickness of 0.1 to 0.4 μm. A colored aluminum pigment having an average particle size in the range of 5 to 20 μm. 2. The average thickness of the aluminum flakes is 0.
It is in the range of 01 to 0.1 μm and the average particle size is 5 to 20 μm.
m aspect ratio, aspect ratio (average particle size / average thickness)
Is in the range of 50 to 1000, and the colored aluminum pigment according to claim 1. 3. The colored aluminum pigment according to claim 1, wherein the aluminum flakes are aluminum flakes produced by a vapor deposition method. 4. The colored aluminum pigment according to claim 1, wherein a compound having an inorganic acid group is adsorbed on the surface of the aluminum flake. 5. The surface of the color pigment is coated with an amino compound having two amino groups in the molecule and not having a carboxyl group and / or a monobasic aromatic carboxylic acid. The colored aluminum pigment according to any one of claims 1 to 4. 6. The colored aluminum pigment according to claim 1, wherein the content of the colored pigment is in the range of 100 to 500 parts by mass with respect to 100 parts by mass of the aluminum flakes. 7. The coloring according to claim 1, wherein the surface of the colored aluminum pigment containing aluminum flakes and the coloring pigment attached to the surface is further coated with a resin composition. Aluminum pigment. 8. The colored aluminum pigment according to claim 7, wherein the resin composition contains a polymer synthesized from a polymerizable monomer. 9. The colored aluminum pigment according to claim 7, wherein the content of the resin composition is in the range of 30 to 300 parts by mass with respect to 100 parts by mass of the aluminum flakes. 10. A step of mixing a solution containing a compound having an inorganic acid group and aluminum flakes to adsorb the compound having an inorganic acid group on the surface of the aluminum flakes, and a color pigment in the molecule. Dispersing in a non-polar solvent containing an amino compound having two amino groups and not having a carboxyl group and / or a monobasic aromatic carboxylic acid, and a color pigment in an aluminum flake in a non-polar solvent The method for producing a colored aluminum pigment according to claim 1, further comprising: 11. The method for producing a colored aluminum pigment according to claim 10, further comprising a polymerizable monomer and a polymerization initiator in a dispersion of the colored aluminum pigment comprising aluminum flakes having the color pigment attached to the surface thereof. Of the colored aluminum pigment, characterized in that it comprises a step of coating the surface of the colored aluminum pigment with a resin composition containing a polymer by adding the Production method. 12. A coating composition containing the colored aluminum pigment according to claim 1 and a binder. 13. The coating composition according to claim 12, wherein the content of the colored aluminum pigment is in the range of 0.1 to 20 parts by mass with respect to 100 parts by mass of the binder.