JP2016155945A - Brilliant coating composition and multilayer coated film formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brilliant coating composition allowing for formation of a coated film extremely excellent in brilliant feeling in highlight even when a coloring pigment is blended, and a multilayer coated film formation method.SOLUTION: The brilliant coating composition is provided which contains a coated film forming resin and a titanium oxide-coated alumina flake pigment, and in which the titanium oxide-coated alumina flake pigment has a particle diameter of volume accumulation of 50% in a particle size distribution of 20 μm or more, a particle diameter of the volume accumulation of 90% in the particle size distribution of 35 μm or less and an average thickness in a thickness distribution of 0.5 to 1.0 μm, the titanium oxide-coated alumina flake pigment being 2 to 15 pts.mass based on 100 pts.mass of the coated film forming resin (solid component).SELECTED DRAWING: None

Description

  The present invention relates to a glitter coating composition and a method for forming a multilayer coating film that can form a coating film excellent in glitter feeling from a highlight (near regular reflected light) to a face (intermediate).

  In exterior colors of industrial products such as automobiles, metallic paint colors whose appearance changes depending on the viewing angle dominate. Among metallic paint colors, highlights (near specularly reflected light) and high brightness, and paint colors with a large color change from highlight to shade (diagonal direction) have the effect of making the applied industrial products more prominent. There is a popular paint color. Such a metallic paint color is, for example, as shown in Patent Document 1, using a metallic base coat paint and a clear paint containing a glittering pigment selected from an aluminum pigment, a mica pigment, and a metal oxide-coated alumina flake pigment, It can be obtained by a coating method of 2 coat 1 bake system, 3 coat 2 bake system, 4 coat 1 bake system or 4 coat 2 bake system.

  White-based paint colors are particularly popular because of their cleanliness, and white pearl colors and chromatic solid-like pearl colors that change slightly depending on the viewing angle are particularly attractive as both cleanliness and luxury. Has been.

  Patent Document 2 discloses a metallic coating composition containing two types of titanium oxide-coated alumina flakes as a bright pigment. This metallic paint composition may further contain an interference pearl pigment. By this metallic paint composition, the appearance is high in highlight, high gloss, excellent in compactness, and less yellowish, that is, white pearl color. A coating film can be formed. However, when a lot of colored pigments such as titanium oxide and chromatic pigments are blended in such a metallic coating composition, there is a problem that the glittering feeling of highlights becomes weak.

JP 2003-225610 A JP 2007-070424 A

  An object of the present invention is to provide a glittering paint composition and a method for forming a multilayer coating film, which can solve the above-mentioned problems and can form a coating film having a wide range of brightness from highlight to face.

  That is, the present invention relates to a glittering coating composition containing a film-forming resin (A) and a titanium oxide-coated alumina flake pigment, wherein the titanium oxide-coated alumina flake pigment has a particle size of 50% cumulative volume in the particle size distribution. Is 20 μm or more and the particle diameter of 90% of the cumulative volume in the particle size distribution is 35 μm or less, and the average thickness is 0.5 to 1.0 μm in the thickness distribution, and the film-forming resin (A) The present invention relates to a glittering paint composition containing 2 to 15 parts by mass of a titanium oxide-coated alumina flake pigment with respect to 100 parts by mass (solid content), and a multilayer coating film forming method using the same.

  According to the method of the present invention, by using a titanium oxide-coated alumina flake pigment having a relatively large particle size and a sharp distribution, a coating film which is excellent in brightness from the highlight to the face and does not cause white blur in the shade. Can be formed.

  The glittering paint composition of the present invention may be either a water-based paint or a solvent-based paint. Examples of the film-forming resin (A) used in the present invention include acrylic resins, polyester resins, alkyd resins, A polyurethane resin or the like can be used. The glittering paint composition of the present invention is preferably an aqueous paint, and particularly as a film-forming resin (A) component, a film-forming resin (b) other than the acrylic resin emulsion (a), (a) and a curing agent. A water-based paint containing (c) is desirable.

  The acrylic resin emulsion (a) is obtained by emulsifying and dispersing an acrylic resin in an aqueous medium, and examples thereof include an emulsion produced by emulsion polymerization of a polymerizable unsaturated monomer mixture.

  The acrylic resin emulsion (a) is particularly preferably a core-shell emulsion comprising a core part of the copolymer (I) and a shell part of the copolymer (II). Further, the copolymer (I) is contained in one molecule. It is obtained by copolymerizing a polymerizable unsaturated monomer (a1) having two or more polymerizable unsaturated groups and a polymerizable unsaturated monomer (a2) other than the polymerizable unsaturated monomer (a1). It is desirable that II) is obtained by copolymerizing a plurality of polymerizable unsaturated monomers (a3) from the viewpoint of improving the appearance and water resistance of the resulting coating film.

  Examples of the polymerizable unsaturated monomer (a1) include ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, and 1,6-hexanediol di (meth). Examples include acrylate, allyl (meth) acrylate, divinylbenzene, trimethylolpropane triacrylate, methylene bis (meth) acrylamide, ethylene bis (meth) acrylamide, and combinations thereof.

  In the present specification, “(meth) acrylate” means acrylate and / or methacrylate.

  The polymerizable unsaturated monomer (a2) other than the polymerizable unsaturated monomer (a1) (hereinafter sometimes simply referred to as “polymerizable unsaturated monomer (a2)”) is the polymerizable unsaturated monomer (a1). And a monomer having one polymerizable unsaturated group that can be copolymerized with the monomer, and a compound having a polymerizable unsaturated group such as a vinyl group or a (meth) acryloyl group.

  Specific examples of the polymerizable unsaturated monomer (a2) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl. (Meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (Meth) acrylate, stearyl (meth) acrylate, isostearyl acrylate (manufactured by Osaka Organic Chemical Industry, trade name), cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl Alkyl or cycloalkyl (meth) acrylate such as ru (meth) acrylate, cyclododecyl (meth) acrylate; polymerizable unsaturated monomer having isobornyl group such as isobornyl (meth) acrylate; adamantyl (meth) acrylate, etc. A polymerizable unsaturated monomer having an adamantyl group; vinyl aromatic compounds such as styrene, α-methylstyrene, vinyltoluene; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meta ) Polymerizable unsaturated monomer having alkoxysilyl group such as acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane; perfluorobutylethyl (meth) acrylate, perfluorooctyl Perfluoroalkyl (meth) acrylates such as chill (meth) acrylate; polymerizable unsaturated monomers having a fluorinated alkyl group such as fluoroolefin; monomers having a photopolymerizable functional group such as maleimide group; N-vinylpyrrolidone, ethylene , Vinyl compounds such as butadiene, chloroprene, vinyl propionate and vinyl acetate; carboxyl group-containing polymerizable unsaturated monomers such as (meth) acrylic acid, maleic acid, crotonic acid and β-carboxyethyl acrylate; (meth) acrylonitrile, ( Nitrogen-containing polymerizable unsaturated monomers such as (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, adducts of glycidyl (meth) acrylate and amines; 2-hydroxye (Meth) acrylic acid such as ru (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. Monoesterified product with dihydric alcohol, ε-caprolactone modified product of monoesterified product of (meth) acrylic acid and dihydric alcohol having 2 to 8 carbon atoms, N-hydroxymethyl (meth) acrylamide, allyl alcohol, molecule Hydroxyl-containing polymerizable unsaturated monomers such as (meth) acrylate having a polyoxyethylene chain having a terminal hydroxyl group; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) Acrylate, 3,4-epoxycyclohexylethyl (meth) Epoxy group-containing polymerizable unsaturated monomers such as acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and allyl glycidyl ether; (meth) acrylate having a polyoxyethylene chain whose molecular terminal is an alkoxy group; 2-acrylamide- 2-methylpropanesulfonic acid, allylsulfonic acid, sodium styrenesulfonate, sulfoethyl methacrylate and its sodium salt or ammonium salt-containing polymerizable unsaturated monomer; 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxy Phosphoric acid group-containing polymerizable unsaturated monomers such as ethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, 2-methacryloyloxypropyl acid phosphate; 2 Hydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2-hydroxy-4- (3-acryloyloxy-2-hydroxypropoxy) benzophenone, 2,2′-dihydroxy-4- (3-methacryloyloxy 2-hydroxypropoxy) benzophenone, 2,2'-dihydroxy-4- (3-acryloyloxy-2-hydroxypropoxy) benzophenone, 2- (2'-hydroxy-5'-methacryloyloxyethylphenyl) -2H-benzo Monomers having a UV-absorbing functional group such as triazole; 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloyloxy-2,2,6,6- Tetramethylpiperidine, 4-cyano-4- (me ) Acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl- 4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2, Monomers having UV stability such as 2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine; acrolein, diacetone acrylamide, diacetone methacrylamide , Acetoacetoxyethyl methacrylate, formylstyrene, 4 to 7 carbon atoms That vinyl alkyl ketones (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) carbonyl group-containing monomer compounds, such as, and combinations thereof.

  In producing the copolymer (I), the polymerizable unsaturated monomer (a1) is preferably 0.1 based on the total mass of the polymerizable unsaturated monomer (a1) and the polymerizable unsaturated monomer (a2). -20% by weight, more preferably 0.2-10% by weight, and even more preferably 0.7-4% by weight, and the polymerizable unsaturated monomer (a2) is a polymerizable unsaturated monomer. Based on the total mass of (a1) and the polymerizable unsaturated monomer (a2), it is preferably 80 to 99.9% by mass, more preferably 90 to 99.8% by mass, and even more preferably 96 to 99.%. A range of 3% by mass is preferable from the viewpoints of stability during production, improvement of water resistance and weather resistance of the resulting coating film, and the like.

  The plurality of polymerizable unsaturated monomers (a3) forming the shell portion of the copolymer (II) can be appropriately used from those listed in the polymerizable unsaturated monomer (a2), and the obtained core-shell type From the viewpoint of ensuring the stability of the emulsion in an aqueous medium, the shell portion of the copolymer (II) preferably contains a carboxyl group-containing monomer as the polymerizable unsaturated monomer (a3). As the carboxyl group-containing monomer, acrylic acid and / or methacrylic acid is particularly suitable. The amount of the carboxyl group-containing monomer is preferably 1 on the basis of the total mass of the plurality of polymerizable unsaturated monomers (a3) from the viewpoints of stability of the emulsion resin in an aqueous medium and water resistance of the resulting coating film. A range of -40% by mass, more preferably 6-25% by mass, and still more preferably 7-19% by mass is suitable from the viewpoint of storage stability and improvement of water resistance of the resulting coating film.

  In addition, the plurality of polymerizable unsaturated monomers (a3) forming the shell portion of the copolymer (II) can be used as at least a part of the components from the viewpoint of ensuring the stability of the obtained emulsion resin in an aqueous medium. In order to improve the stability of the emulsion resin in an aqueous medium, it is preferable to contain the hydroxyl group-containing monomer. As the hydroxyl group-containing monomer, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate are particularly preferable. The amount of the hydroxyl group-containing monomer is generally based on the total mass of the plurality of polymerizable unsaturated monomers (a3) from the viewpoint of the stability of the emulsion resin in the aqueous medium and the water resistance of the resulting coating film. A range of 1 to 40% by mass, preferably 3 to 25% by mass, and more preferably 4 to 20% by mass is suitable from the viewpoint of storage stability and improvement of water resistance of the resulting coating film.

  The core-shell type emulsion forms, for example, a copolymer (I) by emulsion polymerization of a monomer mixture (1) containing the polymerizable unsaturated monomer (a1) and the polymerizable unsaturated monomer (a2) in the above ratio. Then, a monomer mixture (2) containing a plurality of polymerizable unsaturated monomers (a3) is added and emulsion polymerization is performed. The emulsion polymerization of the monomer mixture (1) can be performed by a method known per se, for example, using a polymerization initiator in the presence of an emulsifier. The monomer mixture (2) can optionally contain components such as a polymerization initiator, a chain transfer agent, a reducing agent, and an emulsifier.

  The core-shell type emulsion has a copolymer (I) formed from a monomer mixture (1) containing a polymerizable unsaturated monomer (a1) and a polymerizable unsaturated monomer (a2) as a core, and a plurality of polymerizable unsaturated monomers. It is a core / shell type emulsion having a copolymer (II) formed from a monomer mixture (2) containing the monomer (a3) as a shell. The ratio of the copolymer (I) to the copolymer (II) in the core-shell type emulsion is generally 5 / in the solid content mass ratio of the copolymer (I) / copolymer (II) from the viewpoint of metallic unevenness of the resulting coating film. It is suitable to be in the range of 95 to 95/5, particularly 30/70 to 92/8, more particularly 40/60 to 90/10. Generally, when the ratio of the copolymer (I) to the copolymer (II) is less than 5/95, the metallic unevenness tends to become prominent, and when it exceeds 95/5, the uniformity of the decorative layer is increased. It may be damaged.

  As the acrylic resin emulsion (a), a single-layer acrylic resin emulsion obtained by emulsion polymerization in one step can also be used.

  The acrylic resin emulsion (a) obtained as described above is preferably from 5 to 90 mgKOH / g, more preferably from 8 to 50 mgKOH / g, and even more preferably from the viewpoints of storability and water resistance of the resulting coating film. It has a resin acid value in the range of ˜35 mg KOH / g. The acrylic resin emulsion (a) is preferably in the range of 1 to 70 mgKOH / g, more preferably 2 to 50 mgKOH / g, and still more preferably 5 to 30 mgKOH / g, from the viewpoint of the water resistance of the resulting coating film. The resin has a hydroxyl value of

  As the film-forming resin (b) other than the acrylic resin emulsion (a), polyester resin, acrylic resin other than (a), alkyd resin, polyurethane resin, silicone resin, epoxy resin and the like can be used.

  The polyester resin is an oil-free or oil-modified carboxyl group-containing polyester resin prepared by an esterification reaction using a polyhydric alcohol and a polybasic acid, and optionally a monobasic acid, an oil component, and the like. Obtained by neutralization.

  The polyester resin preferably contains both hydroxyl groups and carboxyl groups, preferably 10 to 300 mg KOH / g, more preferably 50 to 250 mg KOH / g, and even more preferably 80 to 180 mg KOH / g. Is suitable having an acid value in the range of 1 to 200 mg KOH / g, more preferably 15 to 100 mg KOH / g, and even more preferably 25 to 60 mg KOH / g.

  The polyester resin generally has a number average molecular weight in the range of 1,000 to 50,000, more preferably 1,300 to 20,000.

  In this specification, the number average molecular weight and the weight average molecular weight use tetrahydrofuran as a solvent, use “HLC-8120GPC” (trade name, manufactured by Tosoh Corporation) as a gel permeation chromatograph, and use “ A total of four TSKgel G4000HXL, two TSKgel G3000HXL, and one TSKgel G2000HXL (trade name, all manufactured by Tosoh Corporation) were used as detectors, and a differential refractometer was used. Used, mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 mL / min.

  In addition, a basic substance can be used for neutralization of the carboxyl group of the polyester resin. The basic substance is preferably water-soluble, specifically, for example, ammonia, methylamine, ethylamine, propylamine, butylamine, dimethylamine, trimethylamine, triethylamine, ethylenediamine, morpholine, 2- (methylamino) ethanol, Examples include 2- (dimethylamino) ethanol, diethanolamine, triethanolamine, diisopropanolamine, and 2-amino-2-methylpropanol, and combinations thereof.

  The acrylic resin is other than the acrylic resin emulsion (a), for example, a monomer mixture containing a hydrophilic group-containing monomer such as the carboxyl group-containing polymerizable unsaturated monomer, a hydroxyl group-containing polymerizable unsaturated monomer, or the like. A carboxyl group-containing acrylic resin obtained by copolymerization by a solution polymerization method or the like, particularly a weight average molecular weight of 1,000 to 200,000, preferably 2,000 to 100,000, more preferably 3,000. Examples include carboxyl group-containing acrylic resins in the range of -80,000, and more preferably 5,000-70,000.

  The carboxyl group of the acrylic resin can be neutralized using the above basic substance. The acrylic resin preferably has a hydroxyl value in the range of 1 to 200 mgKOH / g, more preferably 2 to 100 mgKOH / g, and still more preferably 3 to 80 mgKOH / g, and preferably 1 to 200 mgKOH / g. Preferably have an acid value in the range of 2 to 150 mg KOH / g, and more preferably 5 to 100 mg KOH / g.

  Examples of the curing agent (c) include amino resins, polyisocyanate compounds, blocked polyisocyanate compounds, epoxy group-containing compounds, carboxyl group-containing compounds, carbodiimide group-containing compounds, hydrazide group-containing compounds, and semicarbazide group-containing compounds. It is done. Of these, amino resins that can react with hydroxyl groups, polyisocyanate compounds and blocked polyisocyanate compounds, and carbodiimide group-containing compounds that can react with carboxyl groups are preferred. A hardening | curing agent can be used individually or in combination of 2 or more types.

  When the film-forming resin (A), the film-forming resin (b) other than the acrylic resin emulsion (a), and the curing agent (c) are used as the film-forming resin (A) component in the glittering paint composition of the present invention. The content of the acrylic resin emulsion (a) is 5 to 60 mass in terms of solid content, based on 100 mass parts of the total resin solid content, in terms of the appearance, water resistance, weather resistance, and the like of the resulting coating film. Parts, preferably 10 to 55 parts by weight, and the film-forming resin (b) other than the acrylic resin emulsion (a) is 5 to 60 parts by weight, preferably 10 to 55 parts by weight, and the curing agent (c) is solid. It is desirable to use within a range of 5 to 50 parts by mass, preferably 10 to 45 parts by mass.

The titanium oxide-coated alumina flake pigment (B) used in the glittering paint composition of the present invention is composed of natural or synthetic alumina flakes (aluminum oxide: Al ₂ O ₃ ) and titanium oxide (TiO ₂ ) as a main component. The metal oxide is preferably a pigment that is produced by coating uniformly to produce an interference color, and the volume accumulation in the particle size distribution is 50 in terms of the glitter of the resulting coating film. % Particle diameter is 20 μm or more, and the particle diameter of 90% volume accumulation in the particle size distribution is 35 μm or less, and the average thickness in the thickness distribution is 0.5 to 1.0 μm, preferably 0.6 to It is a scaly glittering pigment having a thickness of 0.8 μm, and has a relatively large particle size distribution and thickness distribution as compared with a conventional titanium oxide-coated alumina flake pigment.

  Here, the particle size distribution means a numerical value measured by a particle size distribution measuring device that is measured based on a laser diffraction / scattering method for obtaining a particle size distribution using scattered light when light is irradiated to the particles. The particle size with a volume accumulation of 50% in the particle size distribution is a particle size corresponding to 50% of the volume accumulation from the smaller particle size side, and the particle size of 90% is a volume accumulation from the smaller particle size side. Is a particle diameter corresponding to 90%.

  The thickness distribution is an index indicating what kind of thickness of particles are included in the particle group to be measured, and specifically, the particle group to be measured. A predetermined number (preferably 100 or more) of flaky particles are extracted from the sample, and the thickness thereof is measured using an electron microscope to obtain the average thickness and thickness distribution.

  In the glittering paint composition of the present invention, the titanium oxide-coated alumina flake pigment is used with respect to 100 parts by mass (solid content) of the film-forming resin (A) in terms of the glitter feeling of the resulting coating film. 2 to 15 parts by mass, preferably 4 to 12 parts by mass of (B).

  The glittering paint composition of the present invention can further contain other scaly glittering pigments. Other scaly glittering pigments include, for example, scaly metal pigments such as aluminum, copper, nickel alloys, and stainless steel, scaly metal pigments whose surfaces are coated with metal oxides, and scaly particles that are chemically adsorbed with colored pigments on the surface. Metal pigments, scaly aluminum pigments having an aluminum oxide layer formed by causing an oxidation-reduction reaction on the surface, aluminum solid solution plate iron oxide pigments, glass flake pigments, glass flake pigments whose surfaces are coated with metal oxides, Glass flake pigments with colored pigment chemisorbed on the surface, glass flake pigments coated with metal on the surface, interference mica pigments coated with titanium dioxide on the surface, reduced mica pigments with reduced interference mica pigments, and colored pigments on the surface Colored mica pigment adsorbed or coated with iron oxide on the surface, Graphite coated with titanium dioxide on the surface Examples include pigments, titanium dioxide-coated scale pigments such as silica flake pigments coated with titanium dioxide on the surface, plate-like iron oxide pigments, hologram pigments, synthetic mica pigments, cholesteric liquid crystal polymer pigments with a helical structure, and bismuth oxychloride pigments. It is done.

  When using the said other scale-like luster pigment, the compounding quantity is in the range of 0.1-15 mass parts with respect to 100 mass parts (solid content) of the said film-forming resin (A). The range of 0.1 to 5 parts by mass is more preferable.

  The glittering paint composition of the present invention can further contain a white pigment and / or a chromatic pigment. Examples of white pigments include titanium oxide, zinc white, and zinc sulfide. Titanium oxide is preferable in terms of chemical resistance and design.

  The chromatic pigment is a colored pigment excluding an achromatic pigment such as a white pigment and a black pigment, for example, yellow iron oxide, titanium yellow, monoazo yellow, condensed azo yellow, azomethine yellow, bismuth vanadate, benzimidazolone, Yellow pigments such as isoindolinone, isoindoline, quinophthalone, benzidine yellow and permanent yellow; orange pigments such as permanent orange; red iron oxide, naphthol AS azo red, ansanthrone, anthraquinonyl red, perylene maroon, quinacridone red, di Red pigments such as ketopyrrolopyrrole red and permanent red; purple pigments such as cobalt violet, quinacridone violet and dioxazine violet; blue pigments such as cobalt blue, phthalocyanine blue and slen blue Mention may be made of the green pigments such as phthalocyanine green. Chromatic pigments can be used alone or in combination of two or more.

  When a titanium oxide pigment is used as the white pigment, the blending amount is 100 parts by mass (solid content) of the film-forming resin (A) from the viewpoint of the concealability and brightness of the coating film obtained by coating. On the other hand, it is preferably in the range of 1 to 100 parts by mass, more preferably in the range of 3 to 90 parts by mass.

  In the case of using the chromatic pigment, the blending amount thereof is based on 100 parts by mass (solid content) of the film-forming resin (A) from the viewpoint of the concealability of the coating film obtained by painting, brightness, and hue. It is preferably within the range of 0.01 to 15 parts by mass, more preferably within the range of 0.01 to 5 parts by mass.

  The glitter paint composition of the present invention is further used for various paints such as thickeners, curing catalysts, ultraviolet absorbers, light stabilizers, antifoaming agents, plasticizers, surface conditioners, anti-settling agents, etc. Additives can be included.

  The glittering paint composition of the present invention can be applied to the substrate surface by a method such as electrostatic coating, air spraying, airless spraying, and the film thickness is 5 to 20 μm based on the cured coating film, preferably The range of 5 to 17 μm is appropriate.

  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. Depending on these materials, it can be appropriately degreased or surface treated to form a substrate. In particular, the base material is preferably a metal material itself, various materials plated or vapor-deposited with metal, and those materials subjected to degreasing or surface treatment.

  In addition, an undercoat film or an intermediate coat film can be formed on the material or the like to form a substrate. The undercoating film is formed to conceal the surface of the material or impart anticorrosion and rustproofing properties to the material, and can be obtained by applying an undercoating paint, drying and curing. The undercoat paint type is not particularly limited, and examples thereof include an electrodeposition paint and a primer. The intermediate coating film is formed to conceal the surface of the material or the undercoating film, or to provide adhesion or chipping resistance. The intermediate coating is applied on the surface of the material or the undercoating film. It can be obtained by drying and curing. The type of intermediate coating material is not particularly limited, and known types can be used. For example, an organic solvent-based or water-based intermediate coating material containing a thermosetting resin composition and a pigment as essential components can be used.

  In the present invention, from the viewpoint of making the unevenness on the substrate surface inconspicuous, it is desirable that the substrate surface is a coating surface having a lightness L * value of 70 or more, preferably 75 to 95. The lightness L * value is the value in the L * a * b * color system calculated from the reflectance of a 30 μm thick cured coating film measured with an integrating sphere type spectrocolorimeter (mode excluding regular reflection light). Lightness L * value. Examples of the integrating sphere type spectrocolorimeter include CR-400, CR-410 (trade name, manufactured by Konica Minolta) and the like.

  In the method of the present invention, the above-mentioned glitter coating composition can be coated on the substrate surface to form a glitter coating, and then the clear coating composition can be coated thereon to form a clear coating. . After the application of the glitter coating composition, setting can be performed as necessary, or preheating, air blowing, or the like can be performed under heating conditions that do not substantially cure.

  Clear coating compositions include, for example, organic solvent-type thermosetting coating compositions, aqueous thermosetting coating compositions, thermosetting powder coating compositions and the like containing a base resin having a crosslinkable functional group and a curing agent. Can be mentioned.

  Examples of the crosslinkable functional group possessed by the base resin include a carboxyl group, a hydroxyl group, an epoxy group, and a silanol group. Examples of the base resin include acrylic resin, polyester resin, alkyd resin, urethane resin, epoxy resin, and fluorine resin. Examples of the curing agent include polyisocyanate compounds, blocked polyisocyanate compounds, melamine resins, urea resins, carboxyl group-containing compounds, carboxyl group-containing resins, epoxy group-containing resins, and epoxy group-containing compounds.

  In addition, the clear coating composition can contain, if necessary, a color pigment, a bright pigment, a dye, a matting agent, etc. to such an extent that the transparency is not impaired. Stabilizers, antifoaming agents, thickeners, rust inhibitors, surface conditioners, and the like can be included as appropriate.

  The clear coating can be applied by a method such as electrostatic coating, air spraying, airless spraying, and the film thickness is suitably in the range of 20 to 40 μm based on the cured coating film.

  In the method of the present invention, the coating film made of the glitter coating composition and the clear coating composition can be simultaneously cured by heating. The heating means can be performed by, for example, hot air heating, infrared heating, high frequency heating, and the like, and the heating temperature is preferably 80 to 180 ° C, more preferably 100 to 160 ° C. The heating time is preferably 10 to 60 minutes, and more preferably 15 to 40 minutes.

  In the method of the present invention, the first colored coating composition is applied to the surface of the substrate to form the first colored coating film, and then the second colored coating composition is applied thereon, After forming the colored coating film, a clear coating composition is applied thereon to form a clear coating film, and the first colored coating film, the second colored coating film, and the clear coating film are heated and cured at a time. In the layer coating film forming method, the above-described glittering coating composition can be used as the second colored coating composition.

  The first colored coating composition may be any one of a water-based paint and a solvent-based paint containing a film-forming resin and a color pigment. Examples of the film-forming resin include an acrylic resin, a polyester resin, and an alkyd resin. Polyurethane resin or the like can be used, and the same film-forming resin as the above-described glittering paint composition can be used. As a coloring pigment, a white pigment can be contained, and when a titanium oxide pigment is used as a white pigment, the blending amount thereof is 1 to 100 parts by mass with respect to 100 parts by mass (solid content) of the film-forming resin. Is preferably in the range of 3 to 90 parts by mass. Moreover, the 1st coloring coating composition can contain the luster pigment containing the above-mentioned titanium oxide coating | coated alumina flake pigment (B) as needed.

  The first colored coating composition and the second colored coating composition can be applied by a method such as electrostatic coating, air spray, airless spray, and the film thickness is 5 to 20 μm based on each cured coating film. The clear coating composition can be applied by a method such as electrostatic coating, air spray, airless spray, etc., and the film thickness is 20 based on the cured coating film. The range of ˜40 μm, preferably 25 to 35 μm is appropriate.

  The coating films of the first colored coating composition, the second colored coating composition, and the clear coating composition can be simultaneously heated and cured. The heating means can be performed by, for example, hot air heating, infrared heating, high frequency heating, and the like, and the heating temperature is preferably 80 to 180 ° C, more preferably 100 to 160 ° C. The heating time is preferably 10 to 60 minutes, and more preferably 15 to 40 minutes.

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 and production example 1 of acrylic resin emulsion (a)
A reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dropping device, 128 parts of deionized water, “ADEKA rear soap SR-1025” (trade name, manufactured by ADEKA, emulsifier, active ingredient 25 %) 2 parts were charged, stirred and mixed in a nitrogen stream, and heated to 80 ° C.

  Next, 1% of the total amount of the following monomer emulsion for core part and 5.3 parts of 6% ammonium persulfate aqueous solution were introduced into the reaction vessel and kept at 80 ° C. for 15 minutes. Thereafter, the remainder of the monomer emulsion for the core part was dropped into a reaction vessel maintained at the same temperature over 3 hours, and aging was performed for 1 hour after completion of the dropping. Next, the following monomer emulsion for shell part was added dropwise over 1 hour, and after aging for 1 hour, it was cooled to 30 ° C. while gradually adding 40 parts of 5% 2- (dimethylamino) ethanol aqueous solution to the reaction vessel, The mixture was discharged while being filtered through a 100 mesh nylon cloth to obtain an acrylic resin emulsion (a) having an average particle diameter of 100 nm and a solid content of 30%. The obtained acrylic resin emulsion had an acid value of 33 mgKOH / g and a hydroxyl value of 25 mgKOH / g.

  Monomer emulsion for core part: 40 parts of deionized water, 2.8 parts of “ADEKA rear soap SR-1025”, 2.1 parts of methylenebisacrylamide, 2.8 parts of styrene, 16.1 parts of methyl methacrylate, 28 of ethyl acrylate The monomer emulsion for the core part was obtained by mixing and stirring the part and 21 parts of n-butyl acrylate.

  Monomer emulsion for shell part: 17 parts of deionized water, 1.2 parts of “ADEKA rear soap SR-1025”, 0.03 part of ammonium persulfate, 3 parts of styrene, 5.1 parts of 2-hydroxyethyl acrylate, 5 parts of methacrylic acid .1 part, 6 parts of methyl methacrylate, 1.8 parts of ethyl acrylate and 9 parts of n-butyl acrylate were mixed and stirred to obtain a monomer emulsion for shell part.

Production and production example 2 of film-forming resin (b) other than (a)
A reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dropping device was charged with 35 parts of propylene glycol monopropyl ether, heated to 85 ° C., then 30 parts of methyl methacrylate, 2-ethylhexyl acrylate 20 Parts, n-butyl acrylate 29 parts, 2-hydroxyethyl acrylate 15 parts, acrylic acid 6 parts, propylene glycol monopropyl ether 15 parts and 2,2′-azobis (2,4-dimethylvaleronitrile) 2.3 parts. The mixture was added dropwise over 4 hours and aged for 1 hour after completion of the addition. Thereafter, a mixture of 10 parts of propylene glycol monopropyl ether and 1 part of 2,2′-azobis (2,4-dimethylvaleronitrile) was added dropwise over 1 hour, followed by aging for 1 hour after completion of the addition. Further, 7.4 parts of diethanolamine was added to obtain a hydroxyl group-containing acrylic resin solution (b-1) having a solid content of 55%. The obtained hydroxyl group-containing acrylic resin had an acid value of 47 mgKOH / g, a hydroxyl value of 72 mgKOH / g, and a weight average molecular weight of 58,000.

Production Example 3
In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and water separator, 109 parts of trimethylolpropane, 141 parts of 1,6-hexanediol, 126 parts of 1,2-cyclohexanedicarboxylic acid anhydride and adipine 120 parts of acid was charged, and the temperature was raised from 160 ° C. to 230 ° C. over 3 hours, followed by a condensation reaction at 230 ° C. for 4 hours. Next, in order to introduce a carboxyl group, the resulting condensation reaction product was added with 38.3 parts of trimellitic anhydride, reacted at 170 ° C. for 30 minutes, and then diluted with 2-ethyl-1-hexanol. Thus, a hydroxyl group-containing polyester resin solution (b-2) having a solid content of 70% was obtained. The obtained hydroxyl group-containing polyester resin had an acid value of 46 mgKOH / g, a hydroxyl value of 150 mgKOH / g, and a number average molecular weight of 1,400.

Production and production example 4 of glitter pigment dispersion
In a stirring and mixing vessel, 10 parts of titanium oxide-coated alumina flake pigment having a particle size of 50% cumulative volume in the particle size distribution of 21 μm, a particle size of 90% cumulative volume in the particle size distribution of 35 μm, and an average thickness of 0.7 μm , 35 parts of 2-ethyl-1-hexanol, 8 parts of a phosphoric acid group-containing resin solution (Note 1) and 0.2 part of 2- (dimethylamino) ethanol were mixed uniformly to give a bright pigment dispersion (P- 1) was obtained.
(Note 1) Phosphate group-containing resin solution: Mixing 27.5 parts of methoxypropanol and 27.5 parts of isobutanol in a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dropping device The solvent was added and heated to 110 ° C. Next, 25 parts of styrene, 27.5 parts of n-butyl methacrylate, 20 parts of branched higher alkyl acrylate (trade name “isostearyl acrylate” manufactured by Osaka Organic Chemical Co., Ltd.), 7.5 parts of 4-hydroxybutyl acrylate, phosphoric acid 121.5 parts of a mixture comprising 15 parts of a group-containing polymerizable monomer (Note 2), 12.5 parts of 2-methacryloyloxyethyl acid phosphate, 10 parts of isobutanol and 4 parts of t-butylperoxyoctanoate over 4 hours In addition to the above mixed solvent, a mixture of 0.5 part of t-butyl peroxyoctanoate and 20 parts of isopropanol was added dropwise over 1 hour. Thereafter, the mixture was aged while stirring for 1 hour to obtain a phosphate group-containing resin solution having a solid content concentration of 50%. The acid value due to the phosphate group of the phosphate group-containing resin was 83 mgKOH / g, the hydroxyl value was 29 mgKOH / g, and the weight average molecular weight was 10,000.
(Note 2) Phosphoric acid group-containing polymerizable monomer: put 57.5 parts monobutyl phosphoric acid and 41 parts isobutanol in a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dropping device, After raising the temperature to 90 ° C., 42.5 parts of glycidyl methacrylate was added dropwise over 2 hours. Then, after further aging with stirring for 1 hour, 59 parts of isopropanol was added to obtain a phosphate group-containing polymerizable monomer solution having a solid concentration of 50%. The acid value due to the phosphate group of the obtained monomer was 285 mgKOH / g.

Production Example 5
In Production Example 4, a bright pigment dispersion (P-2) was obtained in the same manner as in Production Example 4 except that the amount of the titanium oxide-coated alumina flake pigment was changed from 10 parts to 3 parts.

Production Example 6
In Production Example 4, a bright pigment dispersion (P-3) was obtained in the same manner as in Production Example 4 except that the amount of the titanium oxide-coated alumina flake pigment was changed from 10 parts to 15 parts.

Production Example 7
In Production Example 4, a bright pigment dispersion (P-4) was obtained in the same manner as in Production Example 4, except that the titanium oxide-coated alumina flake pigment was replaced with “Xirallic T60-10WNT Crystal Silver” (Note 3). It was.
(Note 3) “Xiallic T60-10WNT Crystal Silver”, manufactured by Merck & Co., Inc., particle size with a volume accumulation of 50% in the particle size distribution is 18 μm, particle size with a volume accumulation of 90% in the particle size distribution is 29.8 μm, and average thickness is 0 Titanium oxide coated alumina flake pigment which is 5 μm.

Production Example 8
In Production Example 4, a bright pigment dispersion (P-5) was obtained in the same manner as in Production Example 4 except that the titanium oxide-coated alumina flake pigment was replaced by “Twincle Pearl SXD-SO” (Note 4) in its entirety.
(Note 4) “Twinple Pearl SXD-SO”, manufactured by Nihon Koken Kogyo Co., Ltd., particle size distribution with 50% cumulative volume in particle size distribution is 20 μm or more, particle size with 90% cumulative volume in particle size distribution is 41 μm, average thickness is 0 Synthetic mica substrate titanium oxide pigment which is 5 μm.

Production Example 9
In Production Example 4, a bright pigment dispersion (P-6) was obtained in the same manner as in Production Example 4 except that the titanium oxide-coated alumina flake pigment was replaced by “Metashine ST1018RS-JA1” (Note 5). .
(Note 5) “Metashine ST1018RS-JA1”, manufactured by Nippon Sheet Glass Co., Ltd., particle size with a volume accumulation of 50% in the particle size distribution is 18 μm, particle size with a volume accumulation of 90% in the particle size distribution is 31.6 μm, and average thickness is 1 Titanium oxide coated glass flake pigment which is 0.0 μm.

Production Example 1 of water-based glittering paint
In an agitation and mixing container, 120 parts of the acrylic resin emulsion (a) obtained in Production Example 1 (solid content 36 parts), 28.5 parts of the polyester resin solution (b-2) obtained in Production Example 3 (20 parts solid content) , 53 parts of bright pigment dispersion (P-1) obtained in Production Example 4 (4 parts of resin solid content), 18 parts of acrylic resin solution (b-1) obtained in Production Example 2 (10 parts of solid content), And 37.5 parts (30 parts solid content) of melamine resin (trade name “Cymel 325” (manufactured by Nippon Cytec Industries, Ltd., solid content 80%)), and further mixed with polyacrylic acid thickener (product Name “Primal ASE-60”, manufactured by Rohm and Haas), 2- (dimethylamino) ethanol and deionized water, pH 8.0, paint solids 25%, viscosity at 20 ° C. according to Ford Cup No. 4 40 Aqueous glitter in seconds A paint (X-1) was obtained.

Example 2
Example 1 Example 1 except that 46 parts of the glitter pigment dispersion (P-2) obtained in Production Example 5 were used instead of 53 parts of the glitter pigment dispersion (P-1) obtained in Production Example 4. In the same manner as in Example 1, an aqueous glittering paint (X-2) was obtained.

Example 3
Example 1 Example 1 except that 58 parts of the glitter pigment dispersion (P-3) obtained in Production Example 6 were used instead of 53 parts of the glitter pigment dispersion (P-1) obtained in Production Example 4. In the same manner as in Example 1, an aqueous glittering paint (X-3) was obtained.

Comparative Example 1
Example 1 is the same as Example 1 except that the same amount of the glitter pigment dispersion (P-4) obtained in Production Example 7 is used instead of the glitter pigment dispersion (P-1) obtained in Production Example 4. Similarly, an aqueous glittering paint (X-4) was obtained.

Comparative Example 2
Example 1 is the same as Example 1 except that the same amount of the glitter pigment dispersion (P-5) obtained in Production Example 8 is used instead of the glitter pigment dispersion (P-1) obtained in Production Example 4. In the same manner, an aqueous glittering paint (X-5) was obtained.

Comparative Example 3
Example 1 is the same as Example 1 except that the same amount of the glitter pigment dispersion (P-6) obtained in Production Example 9 is used instead of the glitter pigment dispersion (P-1) obtained in Production Example 4. Similarly, an aqueous glittering paint (X-6) was obtained.

Production and production example 10 of water-based coloring base paint
36 parts of the hydroxyl group-containing acrylic resin solution (b-1) obtained in Production Example 2 (20 parts of resin solid content), 90 parts of “JR-806” (trade name, rutile type titanium oxide manufactured by Teika), “Carbon MA” -100 "(trade name, carbon black, manufactured by Mitsubishi Chemical Corporation) and 5 parts of deionized water were mixed, adjusted to pH 8.0 with 2- (dimethylamino) ethanol, and then 30 minutes with a paint shaker Dispersion gave a pigment dispersion paste.

  Next, 131 parts of the obtained pigment dispersion paste, 67 parts of the hydroxyl group-containing acrylic resin emulsion (a) obtained in Production Example 1 (30 parts of resin solid content), and the hydroxyl group-containing polyester resin solution obtained in Production Example 3 (b- 2) 28.5 parts (resin solid content 20 parts) and melamine resin (trade name “Cymel 325” (manufactured by Nippon Cytec Industries, Ltd., solid content 80%) 37.5 parts (solid content 30 parts) are uniformly mixed. Furthermore, a polyacrylic acid thickener (trade name “Primal ASE-60”, manufactured by Rohm and Haas), 2- (dimethylamino) ethanol and deionized water were added to adjust the pH to 8.0, and the coating solid content was 50. %, An aqueous colored base paint having a viscosity of 40 seconds according to Ford Cup No. 4 at 20 ° C was obtained.

Preparation of test article (T-1): "ELECRON GT-10" (trade name, Kansai Paint) on cold-rolled steel sheet treated with zinc phosphate measuring 45cm long x 30cm wide x 0.8mm thick A thermosetting epoxy resin-based cationic electrodeposition coating) manufactured by the company is electrodeposited so as to have a dry film thickness of 20 μm, and cured by heating at 170 ° C. for 30 minutes, and then an intermediate coating “Amirac TP- 65-2 White "(trade name, manufactured by Kansai Paint Co., Ltd., polyester resin / amino resin system, organic solvent-type intermediate coating) is applied to a dry film thickness of 30 μm, and cured by heating at 140 ° C. for 30 minutes. The test object (T-1) was obtained. The lightness L * value of the cured coating film with a thickness of 30 μm by this intermediate coating was 85.

Preparation of test article (T-2) In the test article (T-1), instead of the intermediate coating "Amirac TP-65-2 white", the intermediate coating "Amirac TP-" was prepared. A test article (T-2) was obtained in the same manner except that “65-2 dark gray” (trade name, manufactured by Kansai Paint Co., Ltd., polyester resin / amino resin type, organic solvent type intermediate coating) was used. The lightness L * value of the cured coating film with a thickness of 30 μm by this intermediate coating was 20.

Preparation Example 4 of Test Coating Plate
In a coating environment at a temperature of 23 ° C. and a humidity of 75%, the water-based glittering paint (X-1) obtained in Example 1 was applied to the test object (T-1) on a rotary atomizing bell. Using a mold coating machine “ABB Cartridge Bell Coating Machine” (trade name, manufactured by ABB), paint to a dry film thickness of 15 μm, leave an interval of 1 minute, preheat at 80 ° C. for 3 minutes, Next, “Majicron KINO-1210” (trade name, manufactured by Kansai Paint Co., Ltd., acrylic resin-based solvent-based clear coat paint) was applied on the uncured coating surface to a dry film thickness of 40 μm and left for 7 minutes. Then, a test coated plate was produced by heating at 140 ° C. for 30 minutes to simultaneously cure these coating films.

Examples 5-6, Comparative Examples 4-6
In Example 4, the test coated plates of Examples 5 to 6 and Comparative Examples 4 to 6 were prepared in the same manner as in Example 4 except that the water-based glittering paint shown in Table 1 was used. Each of the obtained test coated plates was subjected to the following evaluation test. The results are also shown in Table 1.

Example 7
In a coating environment at a temperature of 23 ° C. and a humidity of 75%, the water-based glittering paint (X-1) obtained in Example 1 is applied to the test object (T-2) on a rotary atomizing bell. Using a mold coating machine “ABB Cartridge Bell Coating Machine” (trade name, manufactured by ABB), paint to a dry film thickness of 15 μm, leave an interval of 1 minute, preheat at 80 ° C. for 3 minutes, Next, “Majicron KINO-1210” (trade name, manufactured by Kansai Paint Co., Ltd., acrylic resin-based solvent-based clear coat paint) was applied on the uncured coating surface to a dry film thickness of 40 μm and left for 7 minutes. Then, a test coated plate was produced by heating at 140 ° C. for 30 minutes to simultaneously cure these coating films.

Comparative Examples 7-9
In Example 7, the test coated plates of Comparative Examples 7 to 9 were produced in the same manner as in Example 7 except that the water-based glittering paint shown in Table 1 was used. Each of the obtained test coated plates was subjected to the following evaluation test. The results are also shown in Table 2.

Evaluation test (* 1) L25-L45: For each test coating plate, light reflected from an angle of 45 degrees was specularly reflected using a multi-angle spectrocolorimeter MA-68 (trade name, manufactured by X-Rite). From the L * 25 value and the L * 45 value calculated from the spectral reflectance received at an angle of 25 degrees with respect to the light and the spectral reflectance received at 45 degrees with respect to the regular reflection light (L * 25-L * 45) Calculated. The smaller the value, the better the brightness from the highlight to the face.

  (* 2) Visual evaluation: The prepared coated plate is illuminated with an artificial sun lamp (manufactured by Celic, color temperature 6500K), and the angle with respect to the illumination of the test plate is observed to observe the cloudiness and glitter of the shade visually. Evaluated. 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. In addition, the finish was comprehensively evaluated according to the following criteria.

Shade cloudiness:
3: No turbidity in shade 2: Slightly turbid in shade 1: White turbidity in shade

Brightness of highlight (particle feeling in the vicinity of specular reflection):
4: The highlight feels strong.

    3: There is a sense of highlight.

    2: The brightness of the highlight is weak.

    1: There is no highlight feeling.

Finished finish comprehensive evaluation A: Total 7 points O: Total 5-6 points Δ: Total 3-4 points X: Total 2 points.

Example 8
In a coating environment at a temperature of 23 ° C. and a humidity of 75%, the water-based colored base paint obtained in Production Example 10 is applied to the test object (T-1) by a rotary atomization type bell type coating machine “ABB cartridge”. "Bell coating machine" (trade name, manufactured by ABB) was applied to a dry film thickness of 10 µm, and after an interval of 1 minute, the aqueous glittering paint (X-) obtained in Example 1 was used. 1) Using a rotary atomizing bell type coating machine “ABB cartridge bell coating machine” (trade name, manufactured by ABB), a dry film thickness of 7 μm was applied and an interval of 1 minute was applied. Thereafter, preheating was performed at 80 ° C. for 3 minutes, and then “Magiclon KINO-1210” (trade name, manufactured by Kansai Paint Co., Ltd., acrylic resin-based solvent-based clear coat paint) was dried onto the uncured coating film with a thickness of 40 μm. Painted to be And allowed to stand for 7 minutes to prepare a test coated plate by curing these coatings at the same time by heating at 140 ° C. 30 min.

  The obtained test coating plate had a good finish with a strong shade of highlight and no turbidity.

Claims (5)

A glittering paint composition comprising a film-forming resin (A) and a titanium oxide-coated alumina flake pigment (B),
The titanium oxide-coated alumina flake pigment is (B), the particle size with a volume accumulation of 50% in the particle size distribution is 20 μm or more, and the particle size with a volume accumulation of 90% in the particle size distribution is 35 μm or less. The average thickness is 0.5 to 1.0 μm,
A glittering coating composition comprising 2 to 15 parts by mass of a titanium oxide-coated alumina flake pigment (B) with respect to 100 parts by mass (solid content) of the film-forming resin (A). A multi-layer coating is formed by coating the glitter coating composition according to claim 1 on a substrate surface to form a glitter coating and then coating the clear coating composition thereon to form a clear coating. Method. After coating the first colored coating composition on the substrate surface and forming the first colored coating film, after coating the second colored coating composition thereon and forming the second colored coating film In this method, a clear coating composition is applied thereon to form a clear coating film, and the first colored coating film, the second colored coating film and the clear coating film are heated and cured at a time. Then, the glitter coating composition according to claim 1 is used as the second colored coating composition. The method for forming a multilayer coating film according to claim 2 or 3, wherein the substrate surface is a coating surface having a lightness L * value of 70 or more. The coated article obtained by the multilayer coating-film formation method of any one of Claim 2 thru | or 4.