JP2012025823A - Coating composition and method for forming coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition capable of forming a coating film which has depth feeling due to high chroma entirely and lightness and hue variation from highlight (near specularly reflected light) to shade (oblique direction) and can be applied to various industrial products, particularly an automotive outer panel; and to provide a method for forming the coating film, by which such a coating film can be formed.SOLUTION: The coating composition contains: a scale-like interference pigment obtained by coating a translucent scale-like base material with a metal oxide; and a colored metallic pigment obtained by forming an amorphous silicon oxide layer and a metal layer on a scale-like metallic base material and further coating the surface with metal particles. The method for forming the coating film includes applying the coating composition onto a base material and further applying a clear coating.

Description

  The present invention relates to a coating composition and a coating film forming method capable of forming a coating film having a sense of depth by changing the brightness and hue from highlight (near regular reflection light) to shade (diagonal direction) with high saturation as a whole. Is.

  In industrial products such as automobiles, metallic paint colors whose appearance changes depending on the viewing angle are particularly popular, and especially when the hue changes depending on the viewing angle and the overall color saturation is excellent in depth, It is attracting attention as a paint color. As a method of forming a composite coating film that maintains a feeling of saturation and expresses a strong glitter feeling, Patent Document 1 discloses a two-coat one-baking process using a glittering pigment-containing coating composition containing colored aluminum and alumina flakes. A method for forming a composite coating film by the method for forming a coating film is described. However, in the method disclosed in Patent Document 1, a paint color that changes in lightness with high saturation and brightness that appears in highlights and darkness in shades can be obtained. However, since the hue does not change, the color change depending on the observation angle becomes monotonous. There was a problem.

JP-A-11-35856

  The present invention relates to a coating composition and a coating film forming method capable of forming a coating film having a sense of depth by changing the brightness and hue from highlight (near regular reflection light) to shade (diagonal direction) with high saturation as a whole. Is.

The present invention
1. Includes a scale-like interference pigment in which a translucent scale-like substrate is coated with a metal oxide, and a colored metal pigment in which a metal particle is further coated on a surface on which an amorphous silicon oxide layer and a metal layer are formed on a scale-like metal substrate. Metallic paint composition,
2. 2. The metallic coating composition according to 1, wherein the transparent scaly substrate is one selected from glass flakes, alumina flakes and silica flakes, and the metal oxide is titanium oxide.
3. 1 item in which the total content of the scaly interference pigment and the colored metal pigment is in the range of 0.1 to 25 parts by mass as the solid content with respect to 100 parts by mass of the resin solid content as the vehicle-forming component in the coating composition. Or the metallic paint composition according to item 2,
4). The metallic paint composition according to any one of items 1 to 3, wherein the mass ratio of the scaly interference pigment and the colored metal pigment is within the range of 5/1 to 1/10 in the former / latter ratio.
5. Any one of the items 1 to 4 wherein the difference Δh between the hue angle of the interference color in the highlight of the scaly interference pigment and the hue angle of the interference color in the highlight of the colored metal pigment is in the range of 0 to 120. Metallic paint composition according to
6). The present invention relates to a coating film forming method in which a metallic paint composition described in 1 to 5 is applied to an object to be coated, and further a clear paint is applied.

  The present invention provides a coating composition and a coating film capable of forming a coating film having a sense of depth by changing the brightness and hue from highlight (near regular reflection light) to shade (diagonal direction) with high saturation as a whole. Can do.

The coating composition of the present invention expresses an interference color in the highlight (near specular reflection light) of the coating film obtained by painting, and the hue and brightness from the highlight (near specular reflection light) to the shade (diagonal direction). For the purpose of changing the color and expressing the particle feeling with highlights, it contains a scaly interference pigment in which a translucent scaly substrate is coated with a metal oxide.

  The scale-like interference pigment obtained by coating a translucent scaly substrate with a metal oxide in the present invention is a translucent scaly substrate coated with a metal oxide having a refractive index different from that of the substrate. Thus, it is a pigment that produces an interference color depending on the type of coated metal oxide and the thickness of the coating layer. As the translucent substrate, mica, artificial mica, glass flake, silica flake and alumina flake are known, and as the metal oxide to be coated, titanium oxide and iron oxide are known.

  The scaly interference pigment to be included in the coating composition of the present invention is not particularly limited, but has high transparency from the viewpoint of interference color expression and particle feeling in the highlight of the coating film obtained by coating. It is preferable to use a glass flake, silica flake or alumina flake having a smooth surface and a narrow particle size distribution, which is coated with titanium oxide.

  The scale-like interference pigment preferably has an average particle size in the range of 3 to 40 μm from the viewpoint of the finish of the coated film and the brightness of the highlight, more preferably the particle size. The diameter is in the range of 5 to 30 μm, particularly preferably in the range of 6 to 25 μm. It is preferable to use a thickness in the range of 0.05 to 0.5 μm. The particle size and thickness here means a numerical value obtained by observing the scaly interference pigment with an optical microscope or an electron microscope, or a numerical value measured with a particle size distribution measuring apparatus using a laser such as a laser diffraction method. To do.

  Further, the content of the scaly interference pigment is within the range of 0.01 to 25 parts by mass in total with respect to 100 parts by mass of the resin solid content in the paint from the point of finish of the coating film obtained by coating. Is preferable, more preferably in the range of 0.03 to 23 parts by mass, and particularly preferably in the range of 0.05 to 20 parts by mass.

  In the coating composition of the present invention, an amorphous silicon oxide layer and a metal layer are formed on a metal substrate for the purpose of changing the hue and lightness from a highlight to a shade for a coating film obtained by painting. The surface further contains a colored metal pigment coated with metal particles.

  Examples of the metal substrate in the colored metal pigment to be blended in the coating composition of the present invention include aluminum, copper, zinc, titanium, iron, nickel, chromium, and alloys thereof. Among these, it is preferable to use aluminum as the metal base because it strongly expresses the interference color in the highlight of the coating film obtained by painting.

  The colored metal pigment blended in the coating composition of the present invention has an amorphous silicon oxide layer formed on the surface of the bright metal substrate. The amorphous silicon oxide layer may be formed directly on the surface of the metal substrate, but in order to stabilize the adhesion between the metal substrate and the amorphous silicon oxide layer, the metal substrate and the amorphous silicon oxide layer One or more intermediate layers may be interposed between the membrane layers. When two or more layers are interposed, two or more layers having the same composition may be stacked, or layers having different compositions may be stacked.

  Although it does not restrict | limit as an intermediate | middle layer, For example, the layer which consists of a single film | membrane or the film of at least any one of the oxide, hydroxide, and hydrate containing molybdenum and / or phosphorus can be mentioned.

  The colored metal pigment to be blended in the coating composition of the present invention may be one in which an amorphous silicon oxide layer is formed after oxidizing the surface of the bright metal substrate to form a metal oxide layer. In the colored metal pigment, by forming a metal oxide layer, there is an advantage that an amorphous silicon oxide film can be grown from the metal oxide layer as a starting point.

  In the colored metal pigment blended in the coating composition of the present invention, either the metal oxide layer or the intermediate layer may be formed, or both the metal oxide layer and the intermediate layer may be formed. When both the metal oxide layer and the intermediate layer are formed, the metal oxide surface modified layer is formed on the surface of the metal base material, and the intermediate layer is formed thereon, whereby the metal base material and the intermediate layer are formed. Adhesion with the layer is improved.

  In the colored metal pigment blended in the coating composition of the present invention, an amorphous silicon oxide film layer is formed on the surface of the metal substrate. This provides an effect that a layer having a refractive index different from that of the base material is present on the surface of the metal base material, and an interference color is developed. As a method for forming an amorphous silicon oxide film layer, for example, a method of stirring or kneading a metal base material and a solution containing a silicon compound in a slurry state or a paste state while maintaining a basic or acidic state can be adopted. Thereby, an amorphous silicon oxide film layer can be formed on the surface of the metal substrate, the surface of the metal oxide layer or the intermediate layer.

  The thickness of the amorphous silicon oxide film layer is preferably within the range of 10 to 500 nm from the viewpoint of stabilizing the adsorption of metal particles described later and increasing the saturation of the coating film obtained by coating. More preferably, it is in the range of 10 to 100 nm.

  In the colored metal pigment blended in the coating composition of the present invention, a metal layer is formed on the surface of the amorphous silicon oxide film layer. Due to the formation of the metal layer, the interference color having high saturation in the coating film obtained by depositing and coating the metal particles densely and uniformly due to the good adsorption state of the metal particles and the metal layer described later. Can be expressed. The metal layer preferably includes at least one selected from Sn (tin), Pd (palladium), Pt (platinum), and Au (gold), and preferably includes any one of Sn and Pd. .

  The metal layer may be formed directly on the surface of the amorphous silicon oxide film layer, but another layer may be interposed between the amorphous silicon oxide film layer and the metal layer. Examples of the other layers include layers made of oxides or hydroxides such as aluminum and cerium. The deposition method of the metal layer is not particularly limited. For example, a metal alkoxide for forming a metal layer is hydrolyzed and deposited by a sol-gel method, or a metal salt solution containing a metal for forming a metal layer is used. A method of neutralizing and adding an alkali is preferable. In addition, when the metal particle mentioned later is formed by electroless plating, it is preferable to use the water-soluble metal salt containing the metal for making it into a metal layer.

  By the method as described above, a catalyst layer of Sn, Pd, Pt, Au or the like is supported as a metal layer in the colored metal pigment to be blended in the coating composition of the present invention. Thereafter, metal particles can be formed on the surface of the metal layer by electroless plating. When the metal pigment on which the metal layer is formed is immersed in an electroless plating solution, the reducing agent in the plating solution is oxidized on the surface of the metal layer due to the catalytic activity of the metal layer. The metal ions in the electroless plating solution are reduced by the electrons released at this time, the metal is deposited on the surface of the metal layer, and metal particles are generated.

  In the colored metal pigment blended in the coating composition of the present invention, the thickness of the metal layer is preferably 30 nm or less. In this case, good saturation and interference color are imparted by the resulting colored metal pigment. The thickness of the metal layer is preferably further in the range of 0.1 to 10 nm. The thickness of the metal layer can be confirmed as a metal layer formed between the amorphous silicon oxide film layer and the metal particles in, for example, a high magnification observation of about 3 million times with a transmission electron microscope (TEM). it can.

  The metal layer may be deposited uniformly or non-uniformly on the surface of the amorphous silicon oxide film layer. For example, even when the thickness of the metal layer is so thin that it cannot be observed by TEM, when the metal layer is deposited, the metal particles may be deposited densely and uniformly.

  In the colored metal pigment to be blended in the coating composition of the present invention, metal particles are deposited so as to directly cover a part of the surface of the metal layer. The colored metal pigment has a portion where metal particles are not formed, that is, a portion not covered with metal particles. As a result, interference between the reflected light from the surface of the metal particles and the reflected light from the surface of the metal base material, which is the base material passing through the amorphous silicon oxide film layer, occurs, and the coloring exhibits a highly saturated interference color. It is a metal pigment. In addition, since the metal particles are directly formed on the surface of the metal layer, the adhesion between the metal layer and the metal particles is improved, and the interference color is rich in various colors and changes.

  Examples of the metal particles include Al (aluminum), Ti (titanium), Cr (chromium), Fe (iron), Co (cobalt), Ni (nickel), Cu (copper), Zn (zinc), Ru (ruthenium). And particles containing one or more selected from Rh (rhodium), Pd (palladium), Ag (silver), Sn (tin), Pt (platinum), Au (gold), and alloys thereof. When the metal particles contain one or more selected from these metals and metal alloys, a colored metal pigment exhibiting a highly saturated interference color can be obtained. Particularly preferable metal particles include particles containing one or more selected from Cu, Ni, and Ag.

  The average particle size of the metal particles is preferably 50 nm or less. In this case, the colored metal pigment surface having a portion where the metal particles are formed and a portion where the metal particles are not formed has a relatively smooth surface form and can give a metallic film having an excellent finished appearance. A metal pigment is obtained. The average particle size of the metal particles is more preferably 30 nm or less.

  Furthermore, in the colored metal pigment to be blended in the coating composition of the present invention, the thickness of the amorphous silicon oxide film layer is in the range of 10 to 500 nm, and the average particle size of the metal particles is 50 nm or less. Particularly preferred. In this case, an interference color with particularly high saturation is expressed.

  The metal particles formed in the colored metal pigment to be blended in the coating composition of the present invention are formed so as to cover a part of the metal layer without completely covering the metal layer. It is preferable that the interval between the metal particles is 10 nm or less. In the present invention, two or more metal particles may be deposited on the metal layer, but it is preferable that the metal particles are deposited in a single layer as a single particle. In this case, the light is scattered in the amorphous silicon oxide film layer by the reflected light from the metal pigment of the base material and the reflected light from the metal particles, and the saturation is reduced by the interference of the reflected light passing between the metal particles. A high interference color is imparted. Furthermore, it is preferable that each metal particle is deposited on the metal layer without contacting each other. Most typically, the metal particles are preferably deposited in a single layer on the metal layer so that the metal particles do not contact each other and the distance between the metal particles is 10 nm or less.

  In addition, the precipitation state of metal particles, an average particle diameter, and the space | interval of metal particles can be evaluated by cross-sectional observation using a transmission electron microscope (TEM), for example. In this case, as a sample preparation for observation, a method of processing the cross section of the colored metal pigment on which the metal particles are formed by FIB (Focused Ion Beam) can be preferably employed. Since this method can determine a processing location while looking at a scanning ion microscope (SIM) image, it can process a specific portion in a sample. Processing is performed by the method described above, and the cross section of the metal particles is observed at a magnification of 3 to 3 million using a transmission electron microscope (TEM).

  Although the formation method of a metal particle is not specifically limited, A vacuum evaporation method, sputtering method, a chemical vapor deposition method, an electroless plating method etc. are suitable. Among these methods, the electroless plating method is particularly suitable because it can deposit metal particles uniformly and obtain good chroma.

  The colored metal pigment to be blended in the coating composition of the present invention is preferably one having an average particle diameter (D50) in the longitudinal direction within the range of 1 to 50 μm from the viewpoint of the finish of the coating film. It is more preferable to use those within the range of 30 μm, and it is particularly preferable to use those within the range of 5 to 25 μm. Moreover, it is preferable to use the thing within the range of 0.01 micrometer-10 micrometers, and it is especially preferable to use the thing within the range of 0.1 micrometer-5 micrometers. As the colored metal pigment to be blended in the coating composition of the present invention, specifically, a colored metal pigment disclosed in International Publication No. WO2007 / 094253 can be used.

  Further, the ratio of the content of the scaly interference pigment and the colored metal pigment is within the range of 5/1 to 1/10 as the mass ratio of the scaly interference pigment to the colored metal pigment in terms of hiding power and finish. Is preferred. In terms of achieving both saturation and shading (change in brightness from highlight to shade), the content of the colored metal pigment is preferably equal to or more than that of the scaly interference pigment, specifically, The mass ratio of the scaly interference pigment and the colored metal pigment is preferably in the range of 1/1 to 1/5.

  In the coating composition of the present invention, L * C * h between the highlight color of the scaly interference pigment and the highlight color of the colored metal pigment from the point of saturation of the coating film obtained by painting. The hue angle difference Δh in the color system is preferably a combination in the range of 0 to 120 degrees, more preferably in the range of 0 to 60 degrees. The L * C * h color system is a color system designed based on the L * a * b * color system specified by the International Commission on Illumination in 1976 and adopted in JIS Z 8729. H represents a hue angle, and is an angle moved counterclockwise with the red axis as 0 ° in the chromaticity diagram. The difference Δh in hue angle means the minimum value of the difference angle between the hue angle h1 of one color and the hue angle h2 of the other color. The highlight color of the scaly interference pigment and the colored metal pigment in this specification means a color observed at the highlight angle of the coating film containing only the scaly interference pigment or the colored metal pigment as a colorant. Examples of specific measurement methods are given below. 15 parts by mass of the scaly interference pigment or colored metal pigment is mixed per 100 parts by mass of a resin component comprising a hydroxyl group-containing acrylic resin (hydroxyl value 100, number average molecular weight 20000) and melamine resin, and the mixture is stirred and mixed. A coating obtained by diluting to an appropriate viscosity and preparing an organic solvent-type coating having a solid content of about 25% is applied as a cured coating on a coating plate on which a black (N-2) coating is previously formed. X-Rite Co., Ltd. was coated with air spray to a film thickness, allowed to stand at room temperature for 15 minutes, and then heated and dried at 140 ° C. for 30 minutes using a hot air dryer. Using MA-68II (trade name) manufactured by MA, the hue angle calculated from the spectral reflectance when the light irradiated to the coating film at an angle of 45 degrees is received at an angle of 25 degrees with respect to the regular reflection light h can be obtained.

  The coating composition of the present invention can contain a coloring pigment for the purpose of finely adjusting the hue of a coating film obtained by coating. The coloring pigment is not particularly limited, and specifically, inorganic pigments such as transparent iron oxide pigments, carbon black, titanium oxide pigments (including fine particle titanium oxide), azo pigments, and quinacridone types. Pigment, diketopyrrolopyrrole pigment, perinone pigment, perylene pigment, benzimidazolone pigment, isoindoline pigment, isoindolinone pigment, metal chelate azo pigment, phthalocyanine pigment, anthraquinone pigment, dioxazine Any one or more of organic pigments such as pigments, selenium pigments, indigo pigments and the like can be used in combination.

  When the color pigment is blended in the coating composition of the present invention, the content thereof is 0.01 to 100 mass parts of the resin solid content in the coating from the point of not inhibiting the hue change from highlight to shade of the coating film. It is preferably within the range of 30 parts by mass, more preferably 0.1 to 25 parts by mass, particularly preferably 0.2 to 20 parts by mass.

  The coating composition of the present invention can usually contain a resin component as a vehicle. Specific examples of the resin component include base resins such as acrylic resins, polyester resins, alkyd resins, and urethane resins having a crosslinkable functional group such as a hydroxyl group, melamine resins, urea resins, polyisocyanate compounds (block bodies). In combination with a crosslinking agent such as an organic solvent and / or a solvent such as water.

  Furthermore, in the coating composition of the present invention, if necessary, a solvent such as water or an organic solvent, a pigment dispersant, an anti-settling agent, a curing catalyst, an antifoaming agent, an antioxidant, an ultraviolet absorber, a surface conditioner Various additives such as rheology control agents, extender pigments and the like can be appropriately blended.

  The coating composition of the present invention is prepared by mixing and dispersing the aforementioned components. The solid content during coating is preferably adjusted to 12 to 60% by mass, preferably 15 to 50% by mass based on the coating composition.

  The coating film forming method of the present invention relates to a method of coating the coating composition on a substrate and curing and drying the coating composition.

  Next, the coating film forming method of the present invention will be described. In the coating film forming method of the present invention, the above-described material composition is coated on a substrate, and a clear coating is further coated on the obtained coating film.

  Base materials include metals such as iron, zinc, aluminum and magnesium, alloys containing these, molded products plated or vapor-deposited with these metals, and molded products made of glass, plastic, foam, etc. Can be mentioned. Furthermore, the base material can be appropriately subjected to degreasing treatment or surface treatment according to these materials. Furthermore, an undercoating film or an intermediate coating film can be formed on the substrate to form a substrate, and these coated substrates are particularly preferable.

  The undercoat film is formed to conceal the surface of the material or impart anticorrosion and rustproofness to the material, and can be obtained by applying an undercoat paint, drying and curing. it can. The type of the undercoat paint is not particularly limited, and examples thereof include an electrodeposition paint and a solvent-type primer.

  The intermediate coating film is formed to conceal the surface of the material or the undercoat film, to provide adhesion or chipping resistance, or to adjust the lightness of the multilayer coating film. It can be obtained by applying an intermediate coating on the surface of the material or undercoat, drying and curing. The type of intermediate coating is not particularly limited, and known ones can be used. For example, an organic solvent-based or water-based intermediate coating containing a thermosetting resin composition and a color pigment as essential components can be preferably used. .

In particular, when an undercoat film or an intermediate coat film is formed as a substrate, the above-mentioned coating composition can be applied after heating the undercoat film and the intermediate coat film and crosslinking and curing. Alternatively, the undercoating film can be heated to form an intermediate coating film after crosslinking and curing, and the above-described coating composition can be applied in an uncured state. Alternatively, the above-described coating composition may be applied in a state where the undercoat coating film and the intermediate coating film are uncured.

  The coating composition of the present invention can be applied to the above-mentioned various substrates by methods such as electrostatic coating, air spray, and airless spray, and the film thickness is in the range of 5 to 30 μm based on the cured coating film. Is preferable from the viewpoint of the smoothness of the coating film. Usually, it can be heated and dried and cured after being applied to a predetermined film thickness, but a clear paint described later can be applied in an uncured state. The coating composition itself of the coating composition of the present invention can be crosslinked and cured at a temperature of about 50 to about 180 ° C. in the case of a baking and drying type, and usually in the case of a room temperature drying type or a forced drying type. It can be cured at a temperature of room temperature drying to about 80 ° C.

  The clear coating in the method of the present invention is a coating to be applied to the uncured or cured coating surface of the above-described coating composition. The clear coating is mainly composed of a resin component and a solvent, and, if necessary, other coating additives. Is a liquid paint that forms a colorless or colored transparent coating film.

As the clear paint in the method of the present invention, conventionally known clear paints can be used without limitation. For example, a liquid or powdery coating composition containing a base resin and a crosslinking agent can be applied. Examples of the base resin include acrylic resin, polyester resin, alkyd resin, fluororesin, urethane resin, and silicon-containing resin containing a crosslinkable functional group such as a hydroxyl group, a carboxyl group, a silanol group, and an epoxy group. It is done. As a crosslinking agent, a melamine resin capable of reacting with the functional group of the base resin, urea resin, polyisocyanate compound, block polyisocyanate compound, epoxy compound or resin, carboxyl group-containing compound or resin, acid anhydride, Examples thereof include alkoxysilane group-containing compounds or resins. Further, if necessary, additives such as a solvent such as water and an organic solvent, a curing catalyst, an antifoaming agent, an ultraviolet absorber, a rheology control agent, an antioxidant, and a surface conditioner can be appropriately blended.

In the clear paint in the method of the present invention, a color pigment can be blended in a timely manner as long as transparency is not impaired. As the color pigment, one or a combination of two or more conventionally known pigments for ink and paint can be blended. The amount of addition may be determined as appropriate, but is 30 as a solid content with respect to 100 parts by mass of the resin solid content in the clear coating film.
It is within a range of not more than mass parts, preferably 0.01 to 15 mass parts, particularly preferably 0.1 to 10 mass parts.

  The clear coating in the method of the present invention can be applied by a method such as electrostatic coating, air spray, airless spray, and the film thickness is preferably in the range of 15 to 70 μm based on the cured coating film. The clear coating film itself can be crosslinked and cured usually at a temperature of about 50 to about 180 ° C. in the case of a baking dry type, and usually in the case of a normal temperature drying type or a forced drying type. It can be crosslinked and cured at a temperature of about 80 ° C.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to only these examples. “Part” and “%” are based on mass.
(Production Example 1) Production of hydroxyl group-containing acrylic resin In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, and dropping device, 50 parts of ethylene glycol monoethyl ether acetate was stirred and mixed, and the temperature was raised to 135 ° C. Warm up. Subsequently, the following monomer / polymerization initiator mixture was dropped into a reaction vessel maintained at the same temperature over 3 hours, and aging was performed for 1 hour after the completion of the dropping. Thereafter, a mixture composed of 10 parts of ethylene glycol monoethyl ether acetate and 0.6 part of 2,2′-azobis (2-methylpropionitrile) was dropped into a reaction vessel maintained at 135 ° C. over 1 hour 30 minutes. Aged for another 2 hours. Next, ethylene glycol monoethyl ether acetate was distilled off under reduced pressure to obtain a hydroxyl group-containing acrylic resin solution having a resin solid content of 65%. The obtained hydroxyl group-containing resin had a hydroxyl value of 54 mgKOH / g and a number average molecular weight of 20,000. Here, the number average molecular weight means that measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve.
Monomer / polymerization initiator mixture:
38 parts of methyl methacrylate, 17 parts of ethyl acrylate, 17 parts of n-butyl acrylate, 7 parts of hydroxyethyl methacrylate, 20 parts of lauryl methacrylate and 1 part of acrylic acid and 2,2′-azobis A mixture consisting of 2 parts of (2-methylpropionitrile).
Examples 1-4, Comparative Examples 1-3
(Preparation of coating composition)
Resin which is a vehicle forming component comprising 75 parts of the hydroxyl group-containing acrylic resin solution obtained in Production Example 1 as a solid content and 25 parts of Euban 28-60 (trade name, butyl etherified melamine resin, manufactured by Mitsui Chemicals) as a solid content. A bright pigment and a colored pigment are blended at a ratio shown in Table 1 with respect to 100 parts of the solid content, and stirred and mixed, and further diluted with an organic solvent to prepare an organic solvent-type paint having a solid content of about 25%. Then, coating compositions 1 to 7 used in Examples and Comparative Examples were prepared.

(Creation of test plate)
Preparation of base material Degreased and zinc phosphate-treated steel plate (JISG3141, size 400 × 300 × 0.8 mm), cationic electrodeposition paint “Electron 9400HB” (trade name: manufactured by Kansai Paint Co., Ltd., epoxy resin polyamine cationic resin (Using a block polyisocyanate compound as a curing agent) is electrodeposited so as to have a film thickness of 20 μm based on the cured coating film, and heated at 170 ° C. for 20 minutes to be crosslinked and cured to be electrodeposited. A membrane was obtained.

On the obtained electrodeposition coating surface, an intermediate coating “Lugabek intermediate coating gray” (trade name: manufactured by Kansai Paint Co., Ltd., polyester resin / melamine resin type, organic solvent type) is applied by air spray. Based on the film, it was coated to a film thickness of 30 μm, heated at 140 ° C. for 30 minutes to be crosslinked and cured, and a coated plate on which an intermediate coating film was formed was used as a base material.
(2) Coating of coating compositions 1-7 and clear coating The coating compositions 1-7 were applied to the substrate using an air spray so as to have a cured coating film thickness of 20 μm. Let stand in a laboratory at 15 ° C for about 15 minutes, and then apply a clear paint "Lugave Kukuriya" (trade name: manufactured by Kansai Paint, acrylic resin / amino resin type, organic solvent type) to minibell type rotary electrostatic Using a coating machine, the coating was applied to a thickness of 30 μm as a cured coating film under conditions of a boot temperature of 25 ° C. and a humidity of 75%. After coating, the sample was allowed to stand at room temperature for 15 minutes, and then heated in a hot-air circulating drying oven at 140 ° C. for 30 minutes to simultaneously dry and cure the multilayer coating film to obtain a test plate.
(Evaluation)
The design properties of the test plate were evaluated in the following manner, and the results are shown in Table 1.
(1) Evaluation of shading feeling Using MA-68II (trade name, multi-angle spectrophotometer, manufactured by x-Rite), the light irradiated from 45 degrees on the test plate was 15 with respect to specular reflection light. Y15 in the XYZ color system when receiving light at a degree and Y45 when receiving light at 45 degrees were obtained, and the FF value was obtained from the following formula.
(Formula) FF = 2 × (Y15−Y45) / (Y15 + Y45)
(2) Evaluation by visual observation The prepared coated plate is illuminated with an artificial sun lamp (manufactured by Celic, color temperature 6500K), and observed by changing the angle with respect to the illumination of the test plate, and saturation, depth and highlight (correct) The hue change from the vicinity of the reflected light) to the shade (oblique direction) was evaluated visually according to the following criteria. The evaluation was conducted by a total of 5 designers and 3 engineers engaged in color development for 3 years or more, and the average score was adopted.
Saturation 4: Saturation is high.
3: There is saturation.
2: Saturation is poor.
1: There is no saturation.
Deep feeling 4: Strong feeling of depth.
3: There is a feeling of depth.
2: A feeling of depth is poor.
1: There is no sense of depth.
Hue change 3: There is a large hue change.
2: There is a small hue change.
1: There is almost no hue change.

The coating composition and the coating film forming method of the present invention can be applied to various industrial products, particularly automobile outer plates.

Claims (6)

Includes a scale-like interference pigment in which a translucent scale-like substrate is coated with a metal oxide, and a colored metal pigment in which a metal particle is further coated on a surface on which an amorphous silicon oxide layer and a metal layer are formed on a scale-like metal substrate. Paint composition. The coating composition according to claim 1, wherein the transparent scaly substrate is one selected from glass flakes, alumina flakes and silica flakes, and the metal oxide is titanium oxide. The total content of the scaly interference pigment and the colored metal pigment is in the range of 0.1 to 25 parts by mass as the solid content with respect to 100 parts by mass of the resin solid content as the vehicle forming component in the coating composition. The coating composition according to 1 or 2, The coating composition according to any one of claims 1 to 3, wherein the mass ratio of the scaly interference pigment and the colored metal pigment is in the range of 5/1 to 1/10 in terms of the former / latter ratio. The difference Δh between the hue angle of the interference color in the highlight of the scaly interference pigment and the hue angle of the interference color in the highlight of the colored metal pigment is in the range of 0 to 120. 5. The coating composition according to Item. A method of forming a coating film, wherein a coating composition according to claim 1 is applied to an object to be coated, and further a clear coating is applied.