JPH08170034A - Metallic coating composition and formation of film - Google Patents

Abstract

PURPOSE: To obtain a metallic coating composition containing an aluminum flake pigment capable of simultaneously imparting strong brightness and excellent appearance to a film and to provide an industrial method for forming the film. CONSTITUTION: This metallic coating composition contains (A) 100 pts.wt. solids of a film-forming resin and (B) 0.1-30 pts.wt. aluminum flake pigment having 20±5μm average particle diameter D50 , 0.5-1μm particle average thickness and >=2.7 slope (n) in a Rosin-Rammler chart. Furthermore, the method for forming a film is to undercoat a substrate surface to be coated with the metallic coating composition, topcoat the resultant coated surface with a clear coating material and simultaneously cure the undercoat and topcoat.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a metallic coating composition which gives a strong glittering feeling and an excellent coating film appearance suitable for industrial coating for automobiles, bicycles, home electric appliances and parts thereof. The present invention relates to an industrially advantageous coating film forming method.

[0002]

2. Description of the Related Art Conventionally, industrial paints having a composition containing aluminum flake pigment have been widely used as industrial paints which give a coating a glittering, high-grade metallic feel. However, since it is difficult to obtain a coating film that expresses a glittering and bright brilliance with a coating composition containing aluminum flake pigments, development of coatings and coating methods containing metallic pigments different from aluminum flake pigments are actively conducted. Has been done.

For example, JP-A-1-254279 discloses a metallic coating consisting of iron oxide particles containing at least 80% by weight of α-iron oxide crystals having a specific plate-like morphology and a vehicle, which is a colored coating in a low lightness region. Japanese Patent Laid-Open No. 1-108278 discloses a coating finishing method in which a clear coating is further applied on a film, and a specific amount is applied to an inorganic compound coating layer coated on the entire surface of a ceramic scaly substrate such as mica. A metallic coating film containing a pigment in which a metal or an alloy is scattered in an island shape by electroless plating is also disclosed.
Japanese Patent No. 239769 proposes a metallic coating material containing flake-shaped particles obtained by coating the surface of glass flakes with silver as a metallic pigment, and a coating method therefor. Among them, the metallic paint using α-iron oxide, unlike the aluminum flake pigment type, can impart a unique glittering effect that gives a metallic feeling even if the viewpoint angle is shifted, but has a high specific gravity of 5.2. There is a problem that it easily sediments. In addition, iron oxide has a color tone of yellowish brown to black gray, which is a limitation that is limited to coating in a dark color region. On the other hand, interference mica plated with metal components in the form of islands and glass flakes coated with silver are expensive pigments, and even if they have excellent designability, they are difficult to put into practical use and are a limitation for general-purpose painting. There is.

As a metallic finishing method different from the above-mentioned technique, Japanese Unexamined Patent Publication (Kokai) No. 2-107377 discloses a metal having a circular or elliptical shape or a rounded thickness of 0.3 to 1 A method has been proposed in which a metallic paint containing a metal powder having a particle diameter of 0.5 μm and a particle size of 44 μm or less is supplied to a coating gun through a circulation pipe.
The use of brass powder, stainless powder is disclosed. However, in this technology, since relatively thick particles with a maximum thickness of up to 1.5 μm are used as the metal powder, the phenomenon of particles protruding from the coating surface cannot be fully avoided, and clearing occurs multiple times. There is a drawback that a good appearance cannot be ensured unless a coat is applied.

[0005]

In recent years, as the needs have become more diversified and individuality has become more important, it has been attempted to use the above-mentioned new bright metallic pigments from the viewpoint of coating color. However, since aluminum flake pigments have accumulated manufacturing technology for many years, and the experience of being heavily used in paints and paintings is unavoidable, it would be industrially possible to develop aluminum flake pigments with a strong luster that has never existed before. It is extremely beneficial.

It is generally known that the brilliance of an aluminum flake pigment has a correlation with the particle size, and the brilliance feeling increases as the particle size increases, but on the other hand, when the particle size increases, the aluminum flake pigment is formed at the time of coating film formation. The particles are likely to protrude from the coating film due to the disordered or overlapping orientations of the above, and there is a problem that even if clear coating is carried out, the coating film becomes a lumpy or flicker-like coating and the appearance is impaired.

[0007] The inventors of the present invention have conducted extensive research on the conditions for achieving both a strong brilliance and an excellent coating film appearance in a coating system containing an aluminum flake pigment, and as a result, a specific average particle diameter, a particle average thickness and The inventors have found that the above objects can be effectively achieved by selectively using an aluminum flake pigment having a particle size distribution, and have led to the development of the present invention.

Therefore, an object of the present invention is to provide a metallic coating composition containing an aluminum flake pigment capable of simultaneously imparting a strong glittering feeling and an excellent appearance to a coating film, and an industrial coating using the metallic coating composition. It is to provide a film forming method.

[0009]

MEANS FOR SOLVING THE PROBLEMS The metallic coating composition according to the present invention for achieving the above object has (A) 100 parts by weight of a coating film forming resin and (B) an average particle diameter D ₅₀ of 20 ±. 5 μm, average particle thickness 0.5 to 1 μm, rosin-
The composition is characterized in that 0.1 to 30 parts by weight of the aluminum flake pigment having a gradient n in the Lambler diagram of 2.7 or more is contained.

Among the paint components constituting the present invention, resins generally used for paints are used as the coating film forming resin (A) which is a vehicle. For example, an acrylic resin, a polyester resin, an alkyd resin, a fluororesin, etc. can be mentioned, and they are usually used by mixing with a crosslinking agent such as an amino resin or a blocked polyisocyanate compound. Further, these resins are not limited to one kind, and two or more kinds may be used in combination. In addition, a two-component polyurethane resin or silicone resin that can be cured by drying at room temperature is also used.

The aluminum flake pigment (B) used as the metallic pigment component has an average particle diameter D ₅₀ of 20 ± 5.
Particles having a particle size of .mu.m, an average particle thickness of 0.5 to 1 .mu.m, and a gradient n in the Rosin-Rammler diagram of 2.7 or more are selectively used. Each particle property specified in the present invention is obtained by the following measuring method. The average particle diameter D ₅₀ indicates a 50% value of the particle size distribution measured by a laser diffraction type particle size distribution measuring device. The average particle thickness (μm) is a value obtained by the formula [4000 / water surface coverage (cm ² / g)], and the measuring method is, for example, “Aluminum Handbook” (published April 15, 1972, 9th edition). , Japan Light Metals Association; Asakura Shoten), page 1243. A Rosin-Rammler diagram is [R = 100exp (−bD ⁿ )] (where R is the cumulative weight% from the maximum particle size to the particle size D, D is the particle size, and b is the particle size, b And n are constants), and the gradient n is represented by a straight line connecting cumulative weight% from the maximum particle size to the particle size D in the particle size diagram. The n value of the Rosin-Rammler formula is meant. A specific measurement method is to obtain an area-based particle size distribution using a laser diffraction particle size distribution measuring device, plot the obtained cumulative distribution for each particle size on a Rosin-Rammler diagram, and move the straight line in parallel. Then, draw an extrapolation line from the pole (Pol P) to obtain n.

Average particle diameter D of aluminum flake pigment (B)
_{When 50} is _less than 20 ± 5 μm, the particles become too fine and the glittering feeling does not appear. On the contrary, when the particle diameter exceeds ₅₀ %, the orientation of the particles is disturbed or they are overlapped and protrude from the coating surface, resulting in poor appearance. Like When the average particle thickness is in the range of 0.5 to 1 μm, it is relatively thicker than conventional aluminum flake pigments, difficult to deform, and has excellent surface smoothness. If the average particle thickness is less than the above range, it becomes impossible to enhance the brilliance, and if it exceeds the above range, protrusion due to defective orientation of the aluminum flake pigment. , The appearance of the coating film is poor. The particle properties with a gradient n of 2.7 or more in the rosin-Rammler diagram are characterized by a narrow particle size distribution of the aluminum flake pigment, and particles with a uniform particle size suppress diffuse reflection due to fine particles to give a bright feeling. With increasing, coarse particles are also reduced, leading to the formation of a good coating appearance. The more preferable particle properties of the aluminum flake pigment are that the average particle diameter D ₅₀ is 20 ± 2 μm.
, The slope n in the Rosin-Rammler diagram is 2.8 to
It is in the range of 3.5.

As the aluminum flake pigment having the above-mentioned particle properties, for example, atomized aluminum spherical powder whose particle size is selected in advance by primary classification or the like is pulverized with a pulverization aid, an aliphatic or aromatic hydrocarbon solvent. It can be obtained by performing wet pulverization with a pulverizer in the coexistence of a medium and the like, performing sieve classification in a wet state, and then performing solid-liquid separation with a filter press or the like, and the particle shape is a round or rounded flat shape. However, the uneven fracture surface present at the end of the flake is extremely small.

The metallic coating composition of the present invention contains 0.1 to 30 parts by weight, preferably 5 to 25 parts by weight of an aluminum flake pigment based on 100 parts by weight of the coating film-forming resin (A). To do. When the content of the aluminum flake pigment is less than 0.1 parts by weight, the brilliance cannot be exhibited, and when it exceeds 30 parts by weight, the pigment concentration becomes too high and the orientation of the aluminum flake pigment is disturbed, resulting in a coating film. This causes a phenomenon that particles are projected on the surface.

Other flake pigments, color pigments, various additives and the like can be used in common in the above paint system. Examples of the flake pigment include plate-shaped iron oxide, phthalocyanine flake, graphite, titanium dioxide-coated mica, and colored mica. These are used in an amount that does not impair the glitter of the aluminum flake pigment. As the coloring pigment, those conventionally used for paints are used.For example, as an organic pigment, an azo lake pigment, a phthalocyanine pigment, an indigo pigment, a perinone pigment, a perylene pigment, a quinophthalone pigment, a dioxazine pigment, Examples thereof include quinacridone-based pigments, isoindolinone-based pigments, metal complex pigments, and the like. Examples of inorganic pigments include yellow lead, yellow iron oxide, red iron oxide, carbon black, and titanium dioxide. The addition amount of the coloring pigment is arbitrarily set according to the hue of the coating color.

Other additives include, for example, a curing catalyst such as dodecylbenzenesulfonic acid, a benzotriazole-based ultraviolet absorber, a benzophenol-based antioxidant,
Surface modifiers such as silicone and organic polymers, anti-sagging agents,
Thickeners, crosslinkable polymer particles (microgels), etc. are appropriately used. These components are usually used as the coating film forming resin 1.
The performance of the paint or coating film can be improved with a compounding amount of 5 parts by weight or less based on 00 parts by weight.

The metallic paint system of the present invention having the above component composition is generally an organic solvent type, but is not limited to this, and various forms such as a non-aqueous dispersion liquid type, an aqueous solution type and a water dispersion type. Can be configured as a paint. At the time of coating, it is diluted with a solvent such as an organic solvent or water to a viscosity suitable for coating, and the solid content during production is preferably 30 to 70% by weight, and the solid content during coating is preferably 10 to 50% by weight.

The coating film forming method according to the present invention comprises a process in which the surface of a substrate to be coated is base-coated with the above-mentioned metallic coating composition, and then a clear coating is top-coated, and the base coat and the top-coat are simultaneously cured.

The base material to be coated is an inorganic material such as glass, cement or concrete, including metals such as iron, aluminum, copper or alloys thereof,
Polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polyamide, polyacryl, polyester,
The resin moldings such as ethylene-polyvinyl alcohol copolymer, vinyl chloride resin, vinylidene chloride resin, polycarbonate and polyurethane, and plastic materials such as various FRPs, wood and fiber materials are applicable. In addition, it is optional to perform appropriate undercoating or precoating treatment on these coated substrates in advance.

The coating may be applied directly to the substrate to be coated, but in the case of automobile coating, for example, usually, after surface chemical conversion treatment, undercoating and intermediate coating with an electrodeposition coating and the like, the coating film is cured. And then paint. The painting operation uses an atomizing type painting machine and is performed by air spray painting, electrostatic painting, or the like. The base coat film is 10-25 μm
It is preferable that the film is formed in the dry film thickness range. When the film thickness is less than 10 μm, the underlayer hiding property is reduced, which causes color unevenness.

Then, a clear top coating is applied as a top coat on the base coat. As the clear paint, generally used transparent resins are used, but if necessary, color pigments and various additive components may be blended within the range not impairing the transparency. 2 for base coat and top coat
Coat 1 bake method simultaneously cures to form a composite coating. The preferable dry film thickness of the formed top coat is 30 to 60 μm.

[0022]

According to the metallic coating composition of the present invention, the aluminum flake pigment (B) having a specific particle property is contained in a proportion of 0.1 to 30 parts by weight based on 100 parts by weight of the coating film forming resin (A). Has a function of giving the formed coating film a high glittering feeling and an excellent appearance. That is, the average particle diameter D _{50 of} the aluminum flake pigment (B) in the particle diameter range of 20 ± 5 μm effectively functions to suppress the phenomenon of particles protruding from the coating surface and give a good coating appearance. At the same time, it imparts a strong glittering feeling. The aluminum flake morphology having an average particle thickness in the range of 0.5 to 1 μm is relatively thicker than conventional aluminum flake pigments, is hard to be deformed, and has excellent surface smoothness. Eggplant Furthermore, the narrow particle size distribution with a gradient n of 2.7 or more in the rosin-Rammler diagram results in particles having a uniform particle size dispersed in the coating film, which suppresses diffuse reflection due to fine particles to enhance the brilliance and to make the particles coarse. The particles also function to reduce and form a good coating appearance. These respective actions synergistically realize the formation of a coating film having a constantly high glitter metallic reflection feeling and an excellent appearance.

Further, according to the coating film forming method of the present invention, two coats and one bake coating of a base coat and a top coat are applied by virtue of the effect of imparting an excellent luster and a coating film appearance by the above-mentioned metallic paint composition. Since it is possible to form a normal glittering metallic coating film, it becomes possible to form an industrially advantageous coating film by a simple coating process.

[0024]

【Example】

Example 1 Acrylic resin (styrene / methyl methacrylate / ethyl acrylate / hydroxyethyl methacrylate / methacrylic acid copolymer, number average molecular weight of about 20,000, hydroxyl value 45, acid value 15, solid content 50%) 80 solid weight And melamine resin (trade name “U-VAN 20SE” manufactured by Mitsui Toatsu Chemicals, Inc., solid content 60%) mixed with 20 solid parts by weight of the coating film forming resin 100 solid parts by weight, the average particle diameter D ₅₀ is 20 μm. 16 parts by weight of an aluminum flake pigment having an average particle thickness of 0.7 μm and a gradient n of the rosin-Rammler diagram of 3.0 was blended in an organic solvent (toluene / xylene / ethyl acetate / butyl acetate = 70/15). / 10/5) was stirred and mixed with a dissolver so as to have a viscosity suitable for coating, to prepare a metallic paint (silver metallic color).

Using this metallic paint, a coating film was formed by the following painting process. Cationic electrodeposition paint [Nippon Paint Co., Ltd., "Power Top U-50"] is applied to a 0.8 mm thick dull steel plate base material that has been subjected to chemical conversion treatment with zinc phosphate so that the dry coating film becomes 25 μm. After that, it was baked at 160 ° C. for 30 minutes. An intermediate coating [“Olga S-90 Sealer” manufactured by Nippon Paint Co., Ltd.] was air-sprayed onto the surface of the electrodeposition coating film so that the dry coating film had a thickness of 40 μm.
A test plate was prepared by baking at 0 ° C. for 30 minutes. The surface of this test plate was coated with the above metallic paint in a dry coating film of 16 to 2
It was painted so as to be 0 μm. The coating was performed using an electrostatic coating machine [Auto REA, manufactured by Randsburg Gema Co., Ltd.] at an atomization pressure of 2.8 kg / cm ² , and the atmosphere of the booth during coating was maintained at a temperature of 25 ° C. and a humidity of 75%. After setting for 3 minutes after painting, clear acrylic / melamine resin-based paint [Nippon Paint Co., Ltd., “Superlac O-
100 ″] was applied to a dry film thickness of about 35 μm. Then, after setting for about 10 minutes at room temperature,
It was baked at 140 ° C. for 30 minutes.

With respect to the coating film thus formed, the luster and the appearance of the coating film were evaluated by the following measuring methods. (1) Glittering property: Using a microscopic gloss meter (manufactured by Suga Test Instruments Co., Ltd.), the conditions of the optical system are irradiated at an incident angle of 30 ° from the perpendicular of the coated surface, and the light receiving angle is 20 ° from the opposite direction. It was set to receive light, the measurement width was 20 mm, and the reflection characteristics were recorded at a pitch interval of 0.2 mm. 3.8 mm in 0.2 mm steps
It moved to and measured the reflection characteristic of 20 pieces in total. The waveform of each reflection characteristic was subjected to data processing (in accordance with JIS B0601), and the average value of 20 pieces was obtained with the intensity of the glitter feeling as the root mean square value (Rq). The high root mean square value (Rq) indicates that the amplitude of the reflection characteristic waveform is large and the glittering feeling is high.
In addition, the brightness (L ^* ) was measured with a color computer [SM-5, manufactured by Suga Test Instruments Co., Ltd.], and the ratio (Rq) to the root mean square value (Rq) was measured.
/ L ^* ) was calculated, and this value is also an index of glitter. (2) Appearance of coating film: Using a portable image clarity measuring device [manufactured by Suga Test Instruments Co., Ltd.], NSIC was determined. The large NSIC indicates that the sharpness and the sharpness are high and the appearance of the coating film is excellent.

The brightness and the appearance of the coating film were evaluated by visual observation according to the following criteria. (3) Luminance: ◎… Luminance is very strong ○… Luminance is strong △… Luminance is slightly recognized ×… Luminance is weak (2) Appearance of the coating film: ○… Flicker (feeling of foreign matter) No ×… A lot of flicker (feeling of foreign matter)

The evaluation results obtained are shown in Table 1 in comparison with the particle properties of the aluminum flake pigment used in the metallic paint.

Example 2 The aluminum flake pigment of Example 1 has an average particle diameter D ₅₀ of 2
Preparation of metallic paint and film formation under the same conditions as in Example 1 except that the aluminum flake pigment had a particle size of 0 μm, an average particle thickness of 0.6 μm, and a rosin-Rammler diagram gradient n of 2.8. I went. The obtained evaluation results are shown in Table 1 together with the particle properties of the aluminum flake pigment used in the metallic paint.

Example 3 The aluminum flake pigment of Example 1 has an average particle diameter D ₅₀ of 2
Preparation of metallic paint and formation of coating film under the same conditions as in Example 1 except that the aluminum flake pigment has a particle size of 2 μm, an average particle thickness of 0.7 μm, and a rosin-Rammler diagram gradient n of 2.9. I went. The obtained evaluation results are shown in Table 1 together with the particle properties of the aluminum flake pigment used in the metallic paint.

Comparative Example 1 The aluminum flake pigment of Example 1 had an average particle diameter D ₅₀ of 3
Preparation of a metallic paint and formation of a coating film under the same conditions as in Example 1 except that the aluminum flake pigment has a particle size of 0 μm, an average particle thickness of 1.0 μm, and a rosin-Rammler diagram gradient n of 2.6. I went. The obtained evaluation results are shown in Table 1 together with the particle properties of the aluminum flake pigment used in the metallic paint.

Comparative Example 2 The aluminum flake pigment of Example 1 had an average particle diameter D ₅₀ of 1.
Preparation of metallic paint and formation of coating film under the same conditions as in Example 1 except that the aluminum flake pigment had a particle size of 7 μm, an average particle thickness of 0.3 μm, and a gradient n of the rosin-Rammler diagram of 2.3. I went. The obtained evaluation results are shown in Table 1 together with the particle properties of the aluminum flake pigment used in the metallic paint.

Comparative Example 3 The aluminum flake pigment of Example 1 was used, and the average particle diameter D ₅₀ was 1.
Aluminum flake pigment having a particle property of 3 μm, an average particle thickness of 0.3 μm, and a gradient n of the Rosin-Rammler diagram of 2.7, manufactured by Toyo Aluminum Co., Ltd., “Aluminum paste”.
7640NS ″] and the other conditions were the same as in Example 1 except that the metallic paint was prepared and the coating film was formed. The obtained evaluation results are shown in comparison with the particle properties of the aluminum flake pigment used in the metallic paint. It is also listed in 1.

[0034]

[Table 1]

From the results shown in Table 1, each of the examples satisfying the requirements of the present invention exhibits higher glitter and an excellent coating film appearance than the comparative examples. On the other hand, the average particle size is 30 μm
Comparative Example 1 having a coarseness and a gradient n of less than 2.7 is excellent in brilliance, but has an extremely poor coating appearance, and Comparative Example 2 having a low gradient n and an average particle thickness of less than 0.5 μm has a good coating appearance. However, it was confirmed that the glittering feeling was deteriorated, and in Comparative Example 3 in which the average particle size was small and the average particle thickness was thin, the glittering feeling was extremely lowered due to diffused reflection.

Example 4 The amount of aluminum flake pigment in the metallic coating composition of Example 1 was adjusted to 22.5 parts by weight, and 6.3 parts by weight of carbon black coloring pigment was added thereto. The coloring pigment was 1.7 parts by weight of carbon black for color ["Degussa Carbon FW200P" manufactured by Degussa Co.] and acrylic resin varnish (styrene / methyl methacrylate / ethyl acrylate / hydroxyethyl methacrylate / methacrylic acid). Copolymer, number average molecular weight of about 20,000, hydroxyl value
45, acid value 15, solid content 50%) 56.7 parts by weight are premixed with a dissolver, and the particle size is 10μ by a sand grind mill.
Disperse to m or less, then melamine resin varnish [trade name "Uban 20SE" manufactured by Mitsui Toatsu Chemicals, Inc.,
Solid content 60%] 22.9 parts by weight, triethylamine 0.
5 parts by weight and 18.2 parts by weight of an organic solvent (toluene / xylene / ethyl acetate / butyl acetate = 70/15/10/5) were added and mixed with a dissolver for 20 minutes to use a primary color paste. Otherwise, a metallic paint was prepared under the same conditions as in Example 1, and a metallic paint (gray metallic color) was prepared by mixing an appropriate amount of the metallic paint and the primary color paste so that the lightness (L ^* value) was around 38 and forming a coating film. Done,
The obtained evaluation results are shown in Table 2 in comparison with the particle properties of the aluminum flake pigment used in the metallic paint.

Example 5 Among the metallic paint compositions of Example 4, the kind of aluminum flake pigment was changed to that of Example 2, and the other conditions were the same as in Example 4 except that the metallic paint was prepared and the coating film was formed. The evaluation results are shown in Table 2 together with the particle properties of the aluminum flake pigment used in the metallic paint.

Example 6 Among the metallic paint compositions of Example 4, the type of aluminum flake pigment was changed to that of Example 3, and the other conditions were the same as in Example 4 except that the metallic paint was prepared and the coating film was formed. The evaluation results are shown in Table 2 together with the particle properties of the aluminum flake pigment used in the metallic paint.

Comparative Example 4 Among the metallic paint compositions of Example 4, the type of aluminum flake pigment was changed to that of Comparative Example 1, and the other conditions were the same as in Example 4 except that the metallic paint was prepared and the coating film was formed. The evaluation results are shown in Table 2 together with the particle properties of the aluminum flake pigment used in the metallic paint.

Comparative Example 5 Among the metallic paint compositions of Example 4, the type of aluminum flake pigment was changed to that of Comparative Example 2, and the other conditions were the same as in Example 4 except that the metallic paint was prepared and the coating film was formed. The evaluation results are shown in Table 2 together with the particle properties of the aluminum flake pigment used in the metallic paint.

Comparative Example 6 Among the metallic paint compositions of Example 4, the type of aluminum flake pigment was changed to that of Comparative Example 3, and the other conditions were the same as in Example 4 except that the metallic paint was prepared and the coating film was formed. The evaluation results are shown in Table 2 together with the particle properties of the aluminum flake pigment used in the metallic paint.

[0042]

[Table 2]

From the results shown in Table 2, the lightness and the root mean square value are relatively low in these examples due to the addition of the black color pigment, but the evaluation difference between the examples and the comparative examples. Was almost the same as in Table 1.

The preferred embodiments of the present invention, including the above-mentioned examples, are listed below. (1) The average particle diameter D ₅₀ of the aluminum flake pigment is 20 ± 2μ
A metallic coating composition having m and a method for forming a coating film. (2) A metallic coating composition and a method of forming a coating film, wherein the gradient n in the rosin-Rammler diagram of the aluminum flake pigment is 2.8 to 3.5. (3) The average particle diameter D ₅₀ of the aluminum flake pigment is 20 ± 2μ
A metallic coating composition and a method of forming a coating film, wherein m is m, the average particle thickness is 0.5 to 1 μm, and the gradient n in the Rosin-Rammler diagram is 2.8 to 3.5. (4) The content of aluminum flake pigment is 10
A metallic coating composition and a coating film forming method, wherein the amount is 5 to 25 parts by weight per 0 solid parts by weight. (5) A metallic coating composition and a method for forming a coating film in which an aluminum flake pigment and a coloring pigment are used in combination. (6) A metallic coating composition and a coating forming method, wherein the coating forming resin is at least one kind of acrylic resin, polyester resin, alkyd resin or fluororesin. (7) The average particle diameter D ₅₀ is 20 with respect to 100 parts by weight of the coating film forming resin containing at least one kind of acrylic resin, polyester resin, alkyd resin or fluororesin and a crosslinking agent.
A metallic coating composition containing 5 to 25 parts by weight of an aluminum flake pigment having a particle property of ± 2 μm, a particle average thickness of 0.5 to 1 μm, and a gradient n in the Rosin-Rammler diagram of 2.8 to 3.5; Coating film forming method.

[0045]

As described above, according to the present invention, by using the aluminum flake pigment having a specific particle property, it is possible to skillfully suppress the diffuse reflection even though it is a fine particle, and it is difficult to provide with the conventional aluminum flake pigment. It is possible to provide a metallic coating composition that simultaneously exhibits a high glittering feeling and an excellent coating film appearance. Further, according to the coating film forming method of the present invention, the coating operation can be performed in an efficient process by the two-coat one-bake coating system using the coating composition having the above-mentioned composition. Therefore, it is extremely useful for the purpose of forming a high-quality glitter coating film on various kinds of substrates to be coated, including external surface coating of automobile bodies where high-quality coating color is required.

[Procedure amendment]

[Submission date] January 30, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

Comparative Example 3 The aluminum flake pigment of Example 1 was used in the form of particles having an average particle diameter D ₅₀ of 13 μm, an average particle thickness of 0.3 μm and a gradient n of 2.7 in the Rosin-Rammler diagram. A metallic paint was prepared and a coating film was formed under the same conditions as in Example 1 except that the pigment was used. The obtained evaluation results are shown in Table 1 together with the particle properties of the aluminum flake pigment used in the metallic paint.

Claims (2)

[Claims] 1. (A) 100 parts by weight of a coating film forming resin, (B) an average particle diameter D ₅₀ of 20 ± 5 μm, an average particle thickness of 0.5 to 1 μm, and a gradient n in the Rosin-Rammler diagram of 2. A metallic coating composition comprising 0.1 to 30 parts by weight of an aluminum flake pigment of 7 or more. 2. A method for forming a coating film, comprising: coating the surface of a substrate to be coated with the metallic coating composition according to claim 1 and then topcoating the clear coating; and simultaneously curing the basecoat and the topcoat. .