Multilayered coating film, coated article, and metod for producing coated article

Abstract

The present disclosure addresses the problem of providing a multilayered coating film which is recognizable as a black color and, despite this, gives a sense of moderate shading. One embodiment of the multilayered coating film comprises a first coating film, a second coating film, and a clear coating film in this order. The first coating film contains a black pigment, the second coating film contains a glittering black flaky pigment and a black pigment, the chroma C* 15 in the L*C*h color system is 6 or less, the lightness L* 110 in the L*C*h color system is 3 or less, the ratio L* 15 / L* 110 of the lightness L* 15 and the lightness L* 110 in the L*C*h color system is 9-24, and the glitter intensity Si15 is 2-10.

Description

Multilayer coating film, coated article, and method for manufacturing coated article

[0001] The present disclosure relates to multi-layer coatings, coated articles, and methods for making coated articles.

[0002] On the surface of a substrate, such as an automobile body, multiple coatings with various functions are sequentially formed to protect the substrate while also imparting a beautiful appearance and excellent design. A common method for forming such multiple coatings is to form a primer coating, such as an electrodeposition coating, on the substrate, which has excellent conductivity, and then sequentially form an intermediate coating and a topcoat coating as needed. Among these coatings, the topcoat coating, consisting of a base coating and a clear coating, in particular, significantly influences the appearance and design of the coating. In particular, in the case of automobiles, the appearance and design of the topcoat coating, consisting of a base coating and a clear coating, formed on the vehicle body, are extremely important.

[0003] The appearance of a paint film formed on an automobile is closely related to the automobile's appearance value, such as its luxurious feel. Furthermore, automobile buyers tend to seek automobiles with paint films that offer excellent design. Diversifying consumer preferences and a desire for originality are driving demand for more distinctive designs. For example, black paint films are an important color gamut that enjoys a certain share of the automotive paint market. Patent Document 1 discloses a multilayer paint film formation method that includes steps for forming a colored paint film, a glossy paint film, and a clear paint film, and that can form a multilayer paint film with excellent jet-blackness and glossiness.

[0004] International Publication No. 2019 / 142639

[0005] While the multilayer coating film disclosed in Patent Document 1 is a coating film with excellent jet blackness and brilliance, recent consumer trends have demanded designs that are soft and not too flashy. However, many effect black colors using luminous materials use mica or glass flakes, which bring out the color of the luminous material or have a solid-like appearance. On the other hand, even if black is expressed using only aluminum flakes, there is a problem that the brightness increases due to strong reflection, making it difficult to recognize as black at first glance. Therefore, there was a need for a technology that combines a soft shadow effect that is not too solid-like and a brightness that is perceived as black without being too shiny.

[0006] The present disclosure has been made in view of the above, and aims to provide a multilayer coating film that is recognizable as black and has a moderate sense of shading.

[0007] In order to solve the above problems, the present disclosure provides the following aspects.

[0008] [1] A multi-layer coating film comprising a first coating film, a second coating film, and a clear coating film in this order, wherein the first coating film contains a black pigment, and the second coating film contains a shiny black scale-like pigment and a black pigment, and an L based on the spectral reflectance of incident light incident at an angle of 45 degrees to the surface of the multi-layer coating film and reflected light received at an angle of 15 degrees to the specular reflected light. ＊ C ＊ Chroma C in the h color system ＊ １５ is 6 or less, and the L is based on the spectral reflectance of reflected light received at an angle of 110 degrees relative to the specular reflection light when incident light is incident at an angle of 45 degrees to the surface of the multi-layer coating film. ＊ C ＊ Lightness L in the h color system ＊ 110 is 3 or less, and L is based on the spectral reflectance of reflected light received at an angle of 15 degrees relative to the specular reflection light when incident light is incident at an angle of 45 degrees to the surface of the multi-layer coating film. ＊ C ＊ Lightness L in the h color system ＊ 15 and the lightness L ＊ 110 The ratio L ＊ 15 / L＊ 110 is 9 or more and 24 or less, and a light receiving unit is arranged in a direction perpendicular to the surface of the multilayer coating film, and light is irradiated onto the surface of the multilayer coating film at an angle of 15 degrees with respect to the perpendicular direction, and the brilliance intensity Si measured by the light receiving unit is １５ A multi-layer coating film, wherein the number of layers is 2 or more and 10 or less.

[0009] [2] The multi-layer coating film according to [1], wherein the lustrous black scale-like pigment contained in the second coating film is a scale-like pigment having a titanium sintered layer.

[0010] [3] The multilayer coating film according to [1] or [2], wherein the lustrous black scale-like pigment contained in the second coating film is a scale-like pigment having a titanium sintered layer on a mica flat plate substrate.

[0011] [4] The multilayer coating film according to any one of [1] to [3], wherein the content of the lustrous black scale pigment contained in the second coating film is 10% by mass or more and 30% by mass or less in terms of PWC, and the content of the black pigment contained in the second coating film is 2% by mass or more and 12% by mass or less in terms of PWC.

[0012] [5] The multilayer coating film according to any one of [1] to [4], wherein the content of the black pigment contained in the first coating film is 1.5 mass % or more and 5 mass % or less in terms of PWC.

[0013] [6] The multilayer coating film according to any one of [1] to [5], wherein the average particle size of the glittering black scale-like pigment contained in the second coating film is 5 to 14 μm.

[0014] [7] A coated article comprising: a substrate; and the multilayer coating film according to any one of [1] to [6] provided on the substrate.

[0015] [8] A method for forming a multilayer coating film by sequentially coating a first coating composition, a second coating composition, and a clear coating composition on a substrate, wherein the first coating composition contains a black pigment, and the second coating composition contains a shiny black scale pigment and a black pigment, and wherein the L ＊ C ＊Chroma C in the h color system ＊ １５ is 6 or less, and the L is based on the spectral reflectance of reflected light received at an angle of 110 degrees relative to the specular reflection light when incident light is incident at an angle of 45 degrees to the surface of the multi-layer coating film. ＊ C ＊ Lightness L in the h color system ＊ １１０ is 3 or less, and L is based on the spectral reflectance of reflected light received at an angle of 15 degrees relative to the specular reflection light when incident light is incident at an angle of 45 degrees to the surface of the multi-layer coating film. ＊ C ＊ Lightness L in the h color system ＊ １５ and the lightness L ＊ １１０ The ratio L ＊ １５ / L ＊ １１０ is 9 or more and 24 or less, and a light receiving unit is arranged in a direction perpendicular to the surface of the multilayer coating film, and light is irradiated onto the surface of the multilayer coating film at an angle of 15 degrees with respect to the perpendicular direction, and the brilliance intensity Si measured by the light receiving unit is １５ is 2 or more and 10 or less.

[0016] According to the present disclosure, it is possible to provide a multilayer coating film that is recognizable as black and has a moderate sense of shading.

[0017] The present inventors have conducted research with the aim of developing a coating film with a paint color that is excellent in design. In this research, they have investigated a coating film that is recognizable as black but also has a moderate sense of shading, with the aim of developing a coating film with a unique appearance within the range of black, which is generally recognized as having a luxurious feel.

[0018] When aluminum flakes are used to impart a moderate shade to the paint film, the highlight brightness increases. Such a paint film has a so-called metallic gray color and is difficult to recognize as black. Furthermore, when mica is used, the shade tends to appear whitish, increasing the brightness at first glance or imparting saturation, making it difficult to recognize as a jet-black color. Furthermore, when high-reflectivity aluminum flakes or interference mica are used in small amounts to maintain a black shade, the desired design becomes overly shiny and grainy. Thus, it has been difficult to create a paint film that is recognizable as black while also having a moderate shade.

[0019] The present inventors conducted research aimed at solving the above-mentioned problems. They discovered through experiments that by combining specific first and second coating films, it is possible to provide a multi-layer coating film that is recognizable as black and has a moderate sense of shading, and thus completed the present invention. Below, the first coating composition that forms the first coating film and the second coating composition that forms the second coating film will be described in order.

[0020] First Coating Composition The first coating film in the present disclosure is a cured coating film of a first coating composition. The first coating composition is a coating composition containing a first film-forming resin and a black pigment.

[0021] The first coating composition contains a first film-forming resin. Examples of the first film-forming resin include acrylic resin, polyester resin, polyurethane resin, epoxy resin, fluororesin, and silicone resin. The first coating composition may be an aqueous coating composition or a solvent-based coating composition.

[0022] When the first coating composition is an aqueous coating composition, the first coating film-forming resin preferably contains, for example, an acrylic resin emulsion (including an acrylic silicone resin emulsion, an acrylic urethane resin emulsion, etc.), an acrylic resin dispersion (including an acrylic silicone resin dispersion, an acrylic urethane resin dispersion, etc.), a water-soluble acrylic resin, a polyester resin dispersion, a polyurethane resin dispersion, an epoxy resin dispersion, etc. These resins may be used alone or in combination of two or more. The resins can be prepared by methods commonly used by those skilled in the art. Commercially available products may also be used as the resins.

[0023] Preferred embodiments include, for example, an embodiment using either or both of an acrylic resin emulsion and a water-soluble acrylic resin, an embodiment using an acrylic resin emulsion, a water-soluble acrylic resin, and a polyester resin dispersion, and an embodiment using an acrylic resin emulsion, a water-soluble acrylic resin, and a polyurethane resin dispersion.

[0024] The acrylic resin emulsion can be prepared, for example, by emulsion polymerization of a mixture of α,β-ethylenically unsaturated monomers. Preferred α,β-ethylenically unsaturated monomers used in the preparation of the acrylic resin emulsion include (meth)acrylic acid esters, α,β-ethylenically unsaturated monomers having an acid group, and α,β-ethylenically unsaturated monomers having a hydroxyl group.

[0025] Examples of the (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, dihydrodicyclopentadienyl (meth)acrylate, etc. In this specification, (meth)acrylic acid ester refers to both acrylic acid ester and methacrylic acid ester.

[0026] Examples of α,β-ethylenically unsaturated monomers having an acid group include acrylic acid, methacrylic acid, crotonic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl succinic acid, ω-carboxy-polycaprolactone mono(meth)acrylate, isocrotonic acid, α-hydro-ω-((1-oxo-2-propenyl)oxy)poly(oxy(1-oxo-1,6-hexanediyl)), maleic acid, fumaric acid, itaconic acid, 3-vinylsalicylic acid, 3-vinylacetylsalicylic acid, 2-acrylamido-2-methylpropanesulfonic acid, p-hydroxystyrene, and 2,4-dihydroxy-4′-vinylbenzophenone.

[0027] Examples of α,β-ethylenically unsaturated monomers having a hydroxyl group include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, allyl alcohol, methallyl alcohol, and adducts thereof with ε-caprolactone. Among these, preferred are hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyethyl (meth)acrylate, and adducts thereof with ε-caprolactone.

[0028] The α,β-ethylenically unsaturated monomer mixture may further contain other α,β-ethylenically unsaturated monomers. Examples of other α,β-ethylenically unsaturated monomers include polymerizable amide compounds, polymerizable aromatic compounds, polymerizable nitriles, polymerizable alkylene oxide compounds, polyfunctional vinyl compounds, polymerizable amine compounds, α-olefins, dienes, polymerizable carbonyl compounds, polymerizable alkoxysilyl compounds, and other polymerizable compounds. The α,β-ethylenically unsaturated monomers can be selected from a variety of types as needed, depending on the purpose.

[0029] The acrylic resin emulsion can be prepared by emulsion polymerization of the above-mentioned α,β-ethylenically unsaturated monomer mixture. The emulsion polymerization is not particularly limited and can be carried out using a conventional method. Specifically, for example, an emulsifier is dissolved in an aqueous medium containing water or, if necessary, an organic solvent such as an alcohol or ether (e.g., dipropylene glycol methyl ether, propylene glycol methyl ether, etc.), and the above-mentioned α,β-ethylenically unsaturated monomer mixture and a polymerization initiator are added dropwise with heating and stirring. An α,β-ethylenically unsaturated monomer mixture previously emulsified using an emulsifier and water may also be added dropwise in the same manner.

[0030] The polymerization initiator and emulsifier may be those commonly used by those skilled in the art. If necessary, the molecular weight may be adjusted using a mercaptan such as lauryl mercaptan and a chain transfer agent such as α-methylstyrene dimer. The reaction temperature, reaction time, and the like may be appropriately selected within ranges commonly used by those skilled in the art. The acrylic resin emulsion obtained by the reaction may be neutralized with a base, if necessary.

[0031] The acrylic resin emulsion preferably has a number average molecular weight having a lower limit of 3000. The acrylic resin emulsion preferably has a hydroxyl value (solid content hydroxyl value) having a lower limit of 20 mgKOH / g and an upper limit of 180 mgKOH / g, and an acid value (solid content acid value) having a lower limit of 1 mgKOH / g and an upper limit of 80 mgKOH / g.

[0032] In this specification, the number average molecular weight is a value determined by GPC using polystyrene as a standard. In this specification, the acid value and hydroxyl value are values ​​calculated from the monomer composition used in the preparation based on the JIS regulations.

[0033] The water-soluble acrylic resin can be prepared, for example, by solution polymerizing a monomer mixture containing an α,β-ethylenically unsaturated monomer that can be used to prepare the acrylic resin emulsion, and then solubilizing the resulting monomer with a basic compound.The acrylic resin dispersion can be prepared, for example, by solution polymerizing a monomer mixture containing an α,β-ethylenically unsaturated monomer that can be used to prepare the acrylic resin emulsion, and then dispersing the resulting monomer with a basic compound.

[0034] The polyester resin dispersion can be prepared, for example, by condensing a polyhydric alcohol component with a polybasic acid component and dispersing the resulting mixture with a basic compound. The polyurethane resin dispersion can be prepared, for example, by polymerizing a polyol compound, a compound having an active hydrogen group and a hydrophilic group in the molecule, and an organic polyisocyanate, optionally using a chain extender and a polymerization terminator, and then dissolving or dispersing the resulting polymer in water.

[0035] When the first coating composition is an aqueous coating composition, it is preferable to use a curing agent that reacts with the first film-forming resin. Such a curing agent is a film-forming component that reacts with the first film-forming resin to form a coating film. Examples of curing agents that can be used include melamine resins, blocked isocyanate compounds, epoxy compounds, aziridine compounds, carbodiimide compounds, oxazoline compounds, and metal ions. These may be used alone or in combination with two or more. The above components can be prepared by methods commonly used by those skilled in the art. Commercially available products may also be used as the above components. It is more preferable to use either or both of a melamine resin and a blocked isocyanate compound as the curing agent.

[0036] The melamine resin may be a water-soluble melamine resin and / or a water-insoluble melamine resin. The melamine resin has a structure in which hydrogen atoms or substituents (such as alkyl ether groups and methylol groups) are bonded to the periphery of a melamine nucleus (triazine nucleus) via three nitrogen atoms. The melamine resin is generally composed of a polynuclear compound in which multiple melamine nuclei are bonded to each other. Alternatively, the melamine resin may be a mononuclear compound consisting of a single melamine nucleus.

[0037] Commercially available melamine resins may be used. Specific examples of commercially available melamine resins include the Cymel series (trade name) manufactured by Allnex, specifically Cymel 202, Cymel 204, Cymel 211, Cymel 232, Cymel 235, Cymel 236, Cymel 238, Cymel 250, Cymel 251, Cymel 254, Cymel 266, Cymel 267, Cymel 272, Cymel 285, Cymel 301, Cymel 303, Cymel 325, Cymel 327, Cymel 350, Cymel 370, Cymel 701, Cymel 703, and Cymel 1141; and the U-Ban (trade name) series manufactured by Mitsui Chemicals, Inc. These may be used alone or in combination of two or more.

[0038] Blocked isocyanate compounds can be prepared by adding a blocking agent having an active hydrogen to a polyisocyanate such as trimethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, etc. In such blocked isocyanate resins, the blocking agent dissociates upon heating to generate isocyanate groups, which react with functional groups in the resin component to cure.

[0039] The amount of curing agent is preferably 10 to 80% by mass, more preferably 15 to 60% by mass, based on the paint resin solids mass (the solids mass of the film-forming components including the film-forming resin and the curing agent).

[0040] The first coating composition contains a black pigment. Suitable examples of the black pigment include carbon black, graphite, iron black, composite metal oxides such as iron chromium and bismuth manganese, perylene-based black pigments, and azomethiazo-based pigments.

[0041] The black pigment is preferably contained in the first coating film in a PWC (Pigment Weight Concentration) content of 1.5% by mass or more and 5% by mass or less.

[0042] The first coating composition may contain other pigments in addition to the black pigment, as needed, provided that the amount of these other pigments does not impair the performance of the first coating film. Examples of other pigments include color pigments and extender pigments. Examples of color pigments include various inorganic and organic color pigments. Examples of color pigments include blue pigments such as Prussian blue, ultramarine blue, cobalt blue, copper phthalocyanine blue, and indanthrone blue; yellow pigments such as lead yellow, synthetic yellow iron oxide, bismuth vanadate, titanium yellow, zinc yellow, ochre, monoazo yellow, disazo yellow, isoindolinone yellow, metal complex azo yellow, quinophthalone yellow, and benzimidazolone yellow; red pigments such as iron oxide, transparent iron oxide, monoazo red, quinacridone red, azo lake (Mn salt), perylene red, and perylene maroon; orange pigments such as quinacridone magenta, anthanthrone orange, dianthraquinonyl red, pyrazolone orange, benzimidazolone orange, and diketopyrrolopyrrole chrome vermilion; green pigments such as chlorinated phthalocyanine green and brominated phthalocyanine green; and purple pigments such as dioxazine violet and perylene violet. white pigments such as titanium dioxide; and the like.

[0043] Examples of extender pigments include calcium carbonate, barium sulfate, clay, talc, etc. The pigments may further contain an anti-rust pigment, if necessary.

[0044] When the first coating composition is an aqueous coating composition, the aqueous first coating composition may contain, in addition to the above components, additives commonly used by those skilled in the art, such as surface conditioners, viscosity control agents, thickeners, antioxidants, UV inhibitors, and antifoaming agents. For example, the use of a viscosity control agent can impart thixotropy and adjust coating workability. Examples of viscosity control agents include crosslinked or non-crosslinked resin particles, polyamide-based agents such as swollen dispersions of fatty acid amides, amide-based fatty acids, and phosphate salts of long-chain polyaminoamides, polyethylene-based agents such as colloidal swollen dispersions of polyethylene oxide, and organic bentonite-based agents such as organic acid smectite clay and montmorillonite. When these additives are used, they can be used in amounts commonly used by those skilled in the art.

[0045] The first aqueous coating composition may further contain a phosphate group-containing organic compound in addition to the above components, if necessary.

[0046] The aqueous first coating composition may contain water as a solvent, and optionally a water-soluble or water-miscible organic solvent.

[0047] The first aqueous coating composition can be produced by a method commonly used by those skilled in the art, such as kneading and dispersing the first film-forming resin, black pigment, curing agent, and other components and additives as needed using a disperser, homogenizer, kneader, etc. In the production method, it is preferable to prepare a paste containing the black pigment and an optional pigment dispersant in advance and mix them together. Commercially available pigment dispersants can be used as the pigment dispersant.

[0048] When the first coating composition is a solvent-based coating composition, examples of the first coating film-forming resin include acrylic resins, polyester resins (including urethane-modified polyester resins), etc. These resins may be used alone or in combination of two or more.

[0049] The acrylic resin can be prepared, for example, by solution polymerization of a monomer mixture containing an α,β-ethylenically unsaturated monomer. The acrylic resin preferably has a number average molecular weight of 1,000 to 20,000. The acrylic resin also preferably has an acid value (solid content acid value) of 1 to 80 mgKOH / g, more preferably 10 to 45 mgKOH / g. The hydroxyl value (solid content hydroxyl value) is also preferably 10 to 200 mgKOH / g.

[0050] Commercially available acrylic resins may be used, such as the Dianale HR series manufactured by Mitsubishi Rayon Co., Ltd.

[0051] The amount of acrylic resin is preferably 30 to 80% by mass, more preferably 35 to 70% by mass, based on the paint resin solid content mass (solid content mass of the coating film-forming components).

[0052] The polyester resin may be, for example, a hydroxyl group-containing polyester resin, which can be prepared by polycondensation of an acid component such as a polycarboxylic acid and / or an acid anhydride with a polyhydric alcohol.

[0053] When the first coating composition is a solvent-based coating composition, it is preferable to use a curing agent that reacts with the first film-forming resin. Examples of curing agents that can be used include melamine resins and blocked isocyanate compounds. These may be used alone or in combination of two or more. The above components can be prepared by methods commonly used by those skilled in the art. Commercially available products may also be used as the above components.

[0054] The curing agent preferably contains a melamine resin. The melamine resin is not particularly limited, and methylated melamine resin, butylated melamine resin, methyl-butyl mixed melamine resin, etc. can be used. Examples include the Cymel series commercially available from Allnex and the U-Ban series commercially available from Mitsui Chemicals. The amount of melamine resin is preferably 10 to 50% by mass, and more preferably 15 to 40% by mass, based on the paint resin solids mass (the solids mass of the film-forming components including the film-forming resin and curing agent).

[0055] The curing agent preferably further contains a blocked isocyanate compound. The blocked isocyanate compound can be prepared by addition reaction of a polyisocyanate with a blocking compound such as a compound having an active methylene group, a ketone compound, or a caprolactam compound. Commercially available blocked isocyanate compounds may be used. Examples of commercially available blocked isocyanate compounds include the Duranate series manufactured by Asahi Kasei Corporation and the Sumidur series manufactured by Sumika Covestro Urethane Co., Ltd.

[0056] The amount of the blocked isocyanate compound contained in the first coating composition is preferably 10 to 30 mass %, more preferably 15 to 25 mass %, based on the paint resin solids mass (the solids mass of the coating film-forming components including the coating film-forming resin and the curing agent).

[0057] The solvent-based first coating composition contains the first film-forming resin and a black pigment. The black pigment may be the same as that described above. In addition to the components described above, the solvent-based first coating composition may contain additives commonly used by those skilled in the art, such as a curing catalyst, a surface conditioner, an ultraviolet absorber, and an antioxidant.

[0058] The solids concentration and viscosity of the solvent-based first coating composition can be appropriately adjusted by diluting it with an organic solvent at the time of application. Examples of organic solvents that can be used include ester-based solvents, ether-based solvents, alcohol-based solvents, ketone-based solvents, aliphatic hydrocarbon-based solvents, and aromatic solvents.

[0059] The solvent-based first coating composition may further contain a phosphoric acid group-containing organic compound in addition to the above components, if necessary.

[0060] The solvent-based first coating composition can be produced by a method commonly used by those skilled in the art, such as kneading and dispersing the first coating film-forming resin, curing agent, pigment, phosphate group-containing organic compound, additives, etc., using a disperser, homogenizer, kneader, etc. In the above production method, it is preferable to previously prepare a paste containing the black pigment and, if necessary, a pigment dispersant, and then mix them.

[0061] Second Coating Composition The second coating film in the present disclosure is a cured coating film of a second coating composition. The second coating composition is a coating composition containing a second coating film-forming resin, a lustrous black scale-like pigment, and a black pigment. Like the first coating composition, the second coating composition may be an aqueous coating composition or a solvent-based coating composition. Such a second coating composition can be prepared by the same procedure as for the first coating composition.

[0062] The second film-forming resin may be the same as the first film-forming resin, and the first and second film-forming resins may have the same or different resin compositions.

[0063] The second coating composition contains a shiny black scaly pigment. The shiny black scaly pigment is preferably a scaly pigment having a titanium sintered layer, and more preferably a scaly pigment having a titanium sintered layer on a mica flat plate substrate. Instead of the mica flat plate substrate, the scaly pigment may use an aluminum flat plate substrate or a glass flat plate substrate. The shiny black scaly pigment exhibits brilliance due to the substrate such as the mica flat plate substrate, and the titanium sintered layer provides a black color.

[0064] The titanium sintered layer has a composition satisfying TiOx (0.50≦x≦1.90). This allows the titanium sintered layer itself to exhibit a black color. The titanium sintered layer is also a layer that exhibits a black color without completely concealing the brilliance of a substrate such as a mica flat plate substrate. The X value of TiOx more preferably satisfies 1.00≦x≦1.90, and even more preferably satisfies 1.10≦x≦1.90. The composition of the titanium sintered layer can be determined by observing the titanium sintered layer using a powder X-ray diffraction analyzer and quantitatively analyzing it using the RIR (Reference Intensity Ratio) method.

[0065] The thickness of the titanium sintered layer is preferably 50 to 1,000 nm, more preferably 100 to 600 nm. If the thickness is less than 50 nm, the titanium sintered layer may not sufficiently absorb visible light, which may make it difficult to achieve a highly attractive black color. If the thickness is more than 1,000 nm, the titanium sintered layer may excessively absorb visible light, which may prevent the gloss of a substrate such as a mica flat plate substrate from being fully exhibited.

[0066] The titanium sintered layer preferably uniformly covers the entire substrate and has a uniform thickness, but may be partially missing or may have an uneven thickness as long as the effects of the present disclosure are achieved. Multiple titanium sintered layers may be present in the bright black scaly pigment, and in that case, the composition and thickness of each titanium sintered layer preferably satisfy the above conditions, but the respective compositions and thicknesses may be the same or different.

[0067] The bright black scaly pigment may have an amorphous silicon compound layer in addition to the titanium sintered layer. The amorphous silicon compound layer is made of at least one of silicon oxide, silicon hydroxide, and silicon hydrate. By having the amorphous silicon compound layer on the bright black scaly pigment, the water resistance of the bright black scaly pigment can be improved.

[0068] The thickness of the amorphous silicon compound layer is preferably 10 to 1000 nm, which allows the brilliant black scaly pigment to maintain both sufficient water resistance and good hiding power at a high level.

[0069] The amorphous silicon compound layer preferably uniformly covers the entire substrate and has a uniform thickness, but may be partially missing or have an uneven thickness as long as the effects of the present disclosure are achieved. A plurality of amorphous silicon compound layers may be present in the bright black scaly pigment, and in this case, the composition and thickness of each amorphous silicon compound layer preferably satisfy the above conditions, but the respective compositions and thicknesses may be the same or different.

[0070] The bright black scaly pigment may have layers other than the titanium sintered layer and the amorphous silicon compound layer. For example, it may have a base layer made of at least one of oxide, hydroxide, and hydrate of molybdenum (Mo) and / or phosphorus (P), or a resin layer. The base layer can improve the water resistance of the bright black scaly pigment and can serve as a starting point for the growth of other layers on the base layer.

[0071] The resin layer can improve the chemical resistance of the glossy black scaly pigment, and can also improve adhesion between the resin contained in the second coating composition and the glossy black scaly pigment, thereby improving the physical properties of the second coating film. In order to achieve the above effects, the resin layer is preferably the outermost layer of the glossy black scaly pigment. The coating amount of the resin layer is preferably 0.5 to 100 parts by mass, and more preferably 1 to 50 parts by mass, relative to the substrate.

[0072] A suitable resin for the resin layer is a copolymer resin obtained by copolymerizing two or more polymerizable monomers, such as reactive monomers having a carboxyl group and / or a phosphate group, polyfunctional acrylic ester monomers having three or more functional groups, and polymerizable monomers having a benzene nucleus.

[0073] The above-mentioned lustrous black scaly pigment can be produced by forming a titanium sintered layer on the surface of a substrate, which is the object to be coated. When an amorphous silicon compound layer is interposed between the substrate and the titanium sintered layer, the titanium sintered layer is formed by reducing a titanium dioxide layer formed by hydrolysis. The reduction treatment is carried out by firing the substrate on which the titanium dioxide layer is formed in a reducing atmosphere. When an amorphous silicon compound layer is not interposed between the substrate and the titanium sintered layer, the titanium sintered layer is formed by reducing a titanium dioxide layer formed by a sol-gel process in the same manner as above.

[0074] The lustrous black scaly pigment may be a commercially available product, such as the Black Diamond (registered trademark) series manufactured by Ako Kasei Co., Ltd.

[0075] The glittering black scaly pigment preferably has an average particle size (D50) of 5 to 14 μm, which allows it to impart an appropriate graininess to the second coating film. The average particle size is more preferably 7 to 12 μm, and even more preferably 8 to 11 μm.

[0076] The lustrous black scaly pigment is a pigment having a major axis and a minor axis. In the second coating film, the lustrous black scaly pigment is preferably oriented so that the major axis direction is approximately perpendicular to the film thickness direction. The orientation direction of the lustrous black scaly pigment can be controlled by the film thickness of the second coating film, the non-volatile content (%) of the second coating composition, and the like.

[0077] The second coating composition contains a black pigment. The black pigment contained in the second coating composition may be the same as the black pigment contained in the first coating composition.

[0078] The glittering black scaly pigment is preferably contained in the second coating film at a PWC (Pigment Weight Concentration) content of 10% by mass to 30% by mass. The black pigment is preferably contained in the second coating film at a PWC (Pigment Weight Concentration) content of 2% by mass to 12% by mass. By containing the glittering black scaly pigment and the black pigment in the second coating film at the above-mentioned contents, the pigments can be oriented without gaps within the coating film, and a coating film that is recognizable as black but has an appropriate sense of shadow can be formed.

[0079] The second coating composition may contain pigments other than the pigments described above. Examples of other pigments include the extender pigments and anti-rust pigments exemplified in the first coating composition. Examples of extender pigments include calcium carbonate, barium sulfate, clay, and talc.

[0080] Multilayer Coating Film Formation The multilayer coating film of the present disclosure is a coating film having, in this order: a first coating film which is a cured coating film of the first coating composition; a second coating film which is a cured coating film of the second coating composition; and a clear coating film.

[0081] In forming the multilayer coating film of the present disclosure, the substrate to which the coating composition is applied is not particularly limited, and examples thereof include metals, plastics, and foams. The coating composition is particularly advantageous for use on metals and cast products, and is particularly suitable for use on metals that can be electrodeposited. Examples of such metals include iron, copper, aluminum, tin, zinc, and alloys containing these metals. These substrates may also be molded products. Specific examples of molded products include automobile bodies and parts thereof, such as passenger cars, trucks, motorcycles, and buses. It is more preferable that the metal substrates be chemically treated with a phosphate-based chemical conversion treatment agent, a zirconium-based chemical conversion treatment agent, or the like before electrodeposition coating. It is preferable that a cured electrodeposition coating film be formed on a substrate that has been chemically treated as needed. Either cationic or anionic electrodeposition coating compositions can be used to form the cured electrodeposition coating film. Using a cationic electrodeposition coating composition as the electrodeposition coating composition is preferable because it allows for the formation of a coating film with superior corrosion resistance.

[0082] If necessary, the substrate may further have an intermediate coating film formed on the cured electrodeposition coating film. An intermediate coating composition is used to form the intermediate coating film. Examples of intermediate coating compositions that can be used include coating compositions containing a film-forming resin, a curing agent, various organic and / or inorganic coloring components, and extender pigments. The film-forming resin and curing agent are not particularly limited, and specifically, the film-forming resins and curing agents listed above for the aqueous coating composition can be used. From the perspective of various performance characteristics of the resulting intermediate coating film, a combination of an acrylic resin and / or polyester resin with an amino resin and / or isocyanate is preferably used as the film-forming resin in the intermediate coating composition.

[0083] Examples of methods for forming a coating film using the first coating composition and the second coating composition include the following: - A method in which the first coating composition and the second coating composition are applied sequentially to a substrate, and then a clear coating composition is applied. In this type of application, the first coating composition may be applied and heat-cured, and then the second coating composition may be applied and heat-cured. Alternatively, the first coating composition may be applied, and while the applied coating film is still in an uncured state, the second coating composition may be applied wet-on-wet, and then heat-cured. In the wet-on-wet application, preheating may be performed between coats as needed. Alternatively, the first coating composition and the second coating composition may be applied sequentially and dried at room temperature. Then, a clear coating composition is applied to the second coating film obtained by applying the second coating composition to form a clear coating film. - A method in which the first coating composition, the second coating composition, and the clear coating composition are applied sequentially wet-on-wet to a substrate. Specifically, this coating method involves sequentially applying a first coating composition, a second coating composition, and a clear coating wet-on-wet to form an uncured first coating film, a second coating film, and a clear coating film, and then simultaneously heat-curing these uncured coating films. In the wet-on-wet coating method, preheating may be performed between coats as needed.

[0084] The first and second coating compositions can be applied to a substrate by a method commonly used in the coatings field, such as air spray coating, airless spray coating, electrostatic spray coating, multi-stage coating (preferably two-stage coating) using air electrostatic spray coating, or a combination of air electrostatic spray coating and a rotary atomizer-type electrostatic coater.

[0085] The first coating composition is preferably applied so that the thickness of the first coating film after curing is within the range of 5 to 15 μm. The lower limit of the coating thickness may be 5.5 μm. The upper limit of the coating thickness may be 13 μm or 11 μm. The second coating composition is preferably applied so that the thickness of the second coating film after curing is within the range of 2 to 10 μm. The lower limit of the coating thickness may be 2.5 μm. The upper limit of the coating thickness may be 8 μm or 6 μm.

[0086] By setting the film thickness of the first coating film and the second coating film after curing within the above range, the jet blackness of the first coating film can be ensured, and the color of the first coating film can be moderately transparent through the second coating film. Note that if the film thickness of the second coating film after curing is thicker than the film thickness of the first coating film after curing, the brightness of the multi-layer coating film may become too high. For this reason, it is preferable that the film thickness of the first coating film after curing is thicker than the film thickness of the second coating film after curing.

[0087] The heating temperature and time when the first coating composition and second coating composition are applied and then heat-cured can be appropriately selected depending on the composition of the coating composition (water-based or solvent-based) and the type of substrate. The heating temperature can be appropriately selected, for example, from 80 to 180°C, preferably from 100 to 160°C. The heating time can be appropriately selected, for example, from 5 to 60 minutes, preferably from 10 to 30 minutes.

[0088] The clear coating composition is not particularly limited, and examples thereof include solvent-based, water-based, and powder-based clear coating compositions.

[0089] Preferred examples of the above-mentioned solvent-based clear coating composition include, from the viewpoints of transparency or acid etching resistance, a combination of an acrylic resin and / or a polyester resin with an amino resin and / or an isocyanate, or an acrylic resin and / or a polyester resin having a carboxylic acid / epoxy curing system.

[0090] Examples of the water-based clear coating composition include those containing the film-forming resins listed as examples of the solvent-based clear coating composition above, neutralized with a base to make them water-based. This neutralization can be carried out by adding a tertiary amine such as dimethylethanolamine or triethylamine before or after polymerization.

[0091] These solvent-based and water-based clear coating compositions preferably contain a viscosity control agent to ensure coating workability. Viscosity control agents that generally exhibit thixotropy can be used. Examples of viscosity control agents that can be used include those listed for the water-based coating compositions. Additionally, additives commonly used in the coating field may be included as needed.

[0092] As the powder-type clear coating composition, for example, powder coating compositions commonly used in the coating field, such as thermoplastic powder coating compositions and thermosetting powder coating compositions, can be used. Among these, thermosetting powder coating compositions are preferred in terms of coating film properties, etc. Specific examples of thermosetting powder coating compositions include epoxy-based, acrylic-based, and polyester-based powder clear coating compositions.

[0093] The clear coating composition can be applied using a coating method known to those skilled in the art in accordance with the application form of the clear coating composition. The dry film thickness of the clear coating film formed by applying the above-mentioned clear coating composition is generally preferably 10 to 80 μm, more preferably 20 to 60 μm.

[0094] A cured clear coating film can be formed by heat-curing the uncured clear coating film obtained by applying the clear coating composition. When the clear coating composition is applied on an uncured second base coating film, the uncured coating film is heat-cured by heating. From the viewpoint of curability and the physical properties of the resulting multilayer coating film, the heat-curing temperature is preferably set to 80 to 180°C, and more preferably set to 120 to 160°C. The heat-curing time can be set as desired depending on the temperature. Examples of heat-curing conditions include heating at a heat-curing temperature of 120°C to 160°C for 10 to 30 minutes. Depending on the type of coating composition, the coating composition may be applied and then dried at room temperature to form a coating film, and then, for example, a reactive-curing clear coating composition may be applied to form a clear coating film.

[0095] The multilayer coating film of the present disclosure has an L based on the spectral reflectance of incident light incident at an angle of 45 degrees to the surface of the multilayer coating film and reflected light received at an angle of 15 degrees to the specular reflected light. ＊ C ＊ Chroma C in the h color system ＊ １５ is 6 or less, and the L is based on the spectral reflectance of reflected light received at an angle of 110 degrees relative to the specular reflection light when incident light is incident at an angle of 45 degrees to the surface of the multi-layer coating film. ＊ C ＊ Lightness L in the h color system ＊ １１０ is 3 or less, and the L is based on the spectral reflectance of reflected light received at an angle of 15 degrees to the specular reflected light when incident light is incident at an angle of 45 degrees to the surface of the multi-layer coating film. ＊ C ＊ Lightness L in the h color system ＊ １５ and the lightness L ＊ １１０ The ratio L ＊ １５ / L ＊ １１０ is 9 or more and 24 or less, and a light receiving unit is arranged in a direction perpendicular to the surface of the multilayer coating film, and light is irradiated onto the surface of the multilayer coating film at an angle of 15 degrees to the perpendicular direction, and the luminance intensity Si measured by the light receiving unit is１５ The condition is that is between 2 and 10.

[0096] The above brightness L ＊ Is, L ＊ C ＊ This is a parameter in the L h color system and can be determined in accordance with JIS Z8729. ＊ C ＊ The L color system is a color system established by the International Commission on Illumination and is described in Section 4.2 of CIE Publication 15.2 (1986). ＊ C ＊ In the h color system, L ＊ represents brightness, and C ＊ represents the saturation, and h represents the hue angle. ＊ means that the brighter the measured substance is as the value increases, and the duller the value decreases. ＊ means that the brightness of the measured substance increases as the value increases, and the darkness increases as the value decreases. ＊ and saturation C ＊ can be measured using a commercially available multi-angle spectrophotometer. An example of a multi-angle spectrophotometer is BYK-maci (manufactured by BYK).

[0097] The above saturation C ＊ １５ , brightness L ＊ １１０ , and lightness L ＊ １５ Specifically, the incident light and reflected light refer to the reflected light at positions 15 degrees and 110 degrees, respectively, in the incident angle direction from the specularly reflected light of light irradiated at an angle of 45 degrees onto the multilayer coating film, with the position of the specularly reflected light being set to 0 degrees.

[0098] The brightness intensity Si １５Specifically, the sparkle intensity (S) can be calculated from an image obtained by placing, for example, an imaging means as a light receiving unit perpendicular to the surface of the multilayer coating film, irradiating the surface of the multilayer coating film with light at an angle of 15 degrees relative to the perpendicular direction and photographing the surface of the multilayer coating film with the imaging means. Specifically, the image obtained by the imaging means is analyzed using an image analysis algorithm that uses a brightness level histogram, and two-dimensional analysis is performed to calculate the light brightness parameter, which can be calculated as sparkle intensity (S value). A CCD chip is used as the imaging means.

[0099] The brightness intensity Si １５ can be calculated, for example, by measuring using the above-mentioned multi-angle spectrophotometer.

[0100] In this specification, the chroma C of the multi-layer coating film ＊ , brightness L ＊ The measurements of the luster intensity Si and the gloss intensity Si refer to values ​​measured using a multilayer coating film composed of a cured coating film of the first coating composition, a cured coating film of the second coating composition, and a clear coating film. More specifically, the first coating composition is spray-coated on a steel plate coated with a cationic electrodeposition coating composition and then a medium gray cured intermediate coating film is formed on the coated plate, followed by wet-on-wet spray-coating of the second coating composition, and then wet-on-wet spray-coating of the clear coating composition so that the dry film thickness is 35 μm, and then the uncured three-layer coating film is heat-cured at 140° C. for 30 minutes, and the measurements are made using the resulting multilayer coating film.

[0101] In the multilayer coating film of the present disclosure, the chroma C ＊ １５ The condition is that the saturation C ＊ １５ is preferably 3 or less.

[0102] In the multilayer coating film of the present disclosure, the lightness L ＊ １１０ The condition is that the lightness L is 3 or less. ＊ １１０ The multi-layer coating film preferably has a chroma C of 1.6 or less. ＊ １５and lightness L ＊ １１０ is within the above range and the coating film is recognizable as black.

[0103] In the multi-layer coating film of the present disclosure, the lightness L ＊ １５ and the lightness L ＊ １１０ The ratio L ＊ １５ / L ＊ １１０ One of the features of the multi-layer coating film is that the L ＊ １５ / L ＊ １１０ is within the above range, and the coating film has a smooth shading effect from highlights to shades and an appropriate shading effect. ＊ １５ / L ＊ １１０ If L is less than 9, the appearance will be flat, ＊ １５ / L ＊ １１０ If L exceeds 24, the contrast becomes too strong and the appearance becomes metallic, and it is not possible to obtain a suitable sense of shadow. ＊ １５ / L ＊ １１０ is preferably 12 or more and 19 or less.

[0104] In the multilayer coating film of the present disclosure, the brilliance intensity Si １５ is 2 or more and 10 or less. １５ is an index showing the intensity of the brilliance, and the higher the value, the stronger the brilliance. The above multi-layer coating film is recognized as having a certain intensity of brilliance (moderate graininess) under so-called highlight light receiving angle conditions. Brilliance intensity Si １５ is preferably 4 or more and 8 or less.

[0105] As described above, the multilayer coating film of the present disclosure is a coating film that can be recognized as black, yet has an original design with a moderate sense of shading.

[0106] The preferred embodiments of the present disclosure have been described above. The present disclosure is not limited to the above embodiments, and can be modified within the scope of the present disclosure.

[0107] Examples of the present disclosure will be described below, but the present disclosure is not limited to these examples. In the examples, "parts" and "%" are by mass unless otherwise specified.

[0108] Production Example 1 Production of Acrylic Resin Emulsion (Film-Forming Resin) 633 parts of deionized water was added to a reaction vessel, and the temperature was raised to 80° C. while mixing and stirring in a nitrogen stream. Next, a monomer emulsion consisting of a first-stage monomer mixture of 75.65 parts by mass of styrene (ST), 178.96 parts by mass of methyl methacrylate (MMA), 75.94 parts by mass of n-butyl acrylate (BA), 64.45 parts by mass of 2-ethylhexyl acrylate (2-EHA), and 105.00 parts by mass of hydroxyethyl methacrylate (HEMA), 25.00 parts of Aqualon HS-10 (polyoxyethylene alkylpropenylphenyl ether sulfate, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), 25.00 parts of Adeka Reasoap NE-20 (α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-hydroxyoxyethylene, manufactured by ADEKA Corporation), and 400 parts of deionized water, and an initiator solution consisting of 1.2 parts of ammonium persulfate and 500 parts of deionized water were added dropwise to the reaction vessel in parallel over 1.5 hours. After completion of the dropwise addition, the mixture was aged for 1 hour at the same temperature. Furthermore, at 80°C, a second-stage monomer mixture of 53.65 parts by mass of styrene (ST), 178.96 parts by mass of methyl methacrylate (MMA), 75.94 parts by mass of n-butyl acrylate (BA), 64.45 parts by mass of 2-ethylhexyl acrylate (2-EHA), 105.00 parts by mass of hydroxyethyl methacrylate (HEMA), and 22 parts by mass of acrylic acid, a monomer emulsion of 10 parts of Aqualon HS-10 and 250 parts of deionized water, and an initiator solution of 3.0 parts of ammonium persulfate and 500 parts of deionized water were added dropwise to the reaction vessel in parallel over 1.5 hours. After completion of the dropwise addition, the mixture was aged for 2 hours at the same temperature. The mixture was then cooled to 40°C and filtered through a 400 mesh filter, after which 100 parts of deionized water and 1.6 parts of dimethylaminoethanol were added to adjust the pH to 6.5, yielding an acrylic resin emulsion having an average particle size of 150 nm, a nonvolatile content of 35%, a solids acid value of 20 mgKOH / g, and a hydroxyl value of 100 mgKOH / g.

[0109] Production Example 2 Production of Phosphate Group-Containing Organic Compound A 1-liter reaction vessel equipped with a stirrer, a temperature regulator, and a condenser was charged with 40 parts of ethoxypropanol, and 121.7 parts of a monomer solution consisting of 40 parts of a solution obtained by dissolving 20 parts of Phosmer PP (acid phosphooxyhexa(oxypropylene)monomethacrylate manufactured by Unichemical Co., Ltd.) in 4 parts of styrene, 35.96 parts of n-butyl acrylate, 18.45 parts of ethylhexyl methacrylate, 13.92 parts of 2-hydroxyethyl methacrylate, 7.67 parts of methacrylic acid, and 20 parts of ethoxypropanol, and 121.7 parts of a monomer solution consisting of 1.7 parts of azobisisobutyronitrile was added dropwise at 120°C over 3 hours, and stirring was continued for an additional 1 hour. The resulting phosphate group-containing organic compound had an acid value of 105 mgKOH / g, including a phosphate group value of 55 mgKOH / g, a hydroxyl group value of 60 mgKOH / g, a number average molecular weight of 6,000, and a nonvolatile content of 63%.

[0110] Example 1 Preparation of First Coating Composition Pigment Dispersion Paste 3 parts of black pigment R5000 (Laven 5000), 18.6 parts of pigment dispersant Dispex (registered trademark) Ultra PA 4550 (manufactured by BASF), 36.0 parts of ion-exchanged water, and 0.5 parts of antifoaming agent BYK-011 were mixed and dispersed using a stirrer such as a disper to obtain a pigment dispersion paste. Note that the number of parts of each component above is the number of parts in the pigment paste.

[0111] First coating composition 182 parts of the acrylic resin emulsion of Production Example 1, 2.2 parts of dimethylaminoethanol, 40 parts of Cymel 327 (mixed alkylated melamine resin, manufactured by Allnex, solids content 90%), 69.0 parts of the pigment dispersion paste, 5 parts of the phosphate group-containing organic compound of Production Example 2, 0.4 parts of lauryl acid phosphate, 50 parts of butyl cellosolve, Noigen EA-207D (amphiphilic compound, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., number average molecular weight 4200, solids content 55%) 5.5 parts (3 parts in terms of solids), 3 parts of linoleic acid (manufactured by Kishida Chemical Co., Ltd.) were uniformly dispersed and the pH was adjusted to 8.1. Dimethylaminoethanol was added, and the mixture was diluted with deionized water to prepare an aqueous coating composition having a resin solids concentration of 32.0% by mass.

[0112] Preparation of second coating composition Pigment dispersion paste 3 parts of black pigment R5000 (Laven 5000), 18.6 parts of pigment dispersant Dispex (registered trademark) Ultra PA 4550 (manufactured by BASF), 36.0 parts of ion-exchanged water, and 0.5 parts of antifoaming agent BYK-011 were mixed and dispersed using a stirrer such as a disper to obtain a pigment dispersion paste.

[0113] Second coating composition: 182 parts of the acrylic resin emulsion of Production Example 1, 2.2 parts of dimethylaminoethanol, 40 parts of Cymel 327 (mixed alkylated melamine resin, manufactured by Allnex, solids content 90%), 69.0 parts of the pigment dispersion paste prepared by the above procedure, and Black 1000, a brilliant black scale-like pigment. Diamond (registered trademark) M010 (manufactured by Ako Kasei Co., Ltd., average particle size 10 μm, active ingredient 100%) was used relative to 100 mass of resin solids. 20 parts, 5 parts of the phosphate group-containing organic compound of Production Example 2, 0.4 parts of lauryl acid phosphate, 50 parts of butyl cellosolve, 5.5 parts (3 parts in terms of solids) of Noigen EA-207D (amphiphilic compound, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., number average molecular weight 4200, solids content 55%), and 3 parts of linoleic acid (manufactured by Kishida Chemical Co., Ltd.) were uniformly dispersed, and dimethylaminoethanol was added to adjust the pH to 8.1. The mixture was diluted with deionized water to prepare an aqueous coating composition having a resin solids concentration of 15.8 mass%.

[0114] Formation of multi-layer coating film A zinc phosphate-treated dull steel plate, 0.8 mm thick, 30 cm long and 40 cm wide, was electrodeposited with the cationic electrodeposition coating composition "Power Top U-50" (manufactured by Nippon Paint Automotive Coatings) to a dry film thickness of 20 μm and baked at 160°C for 30 minutes. Onto this coated plate, a medium gray intermediate coating composition "OP-30P Middle Gray" (manufactured by Nippon Paint Automotive Coatings, polyester-melamine paint, pre-diluted to 25 seconds (measured at 20°C using a No. 4 Ford cup)) was air spray painted using an Anest Iwata air spray gun W-101-132G to a dry film thickness of 35 μm, and then baked and cured at 140°C for 30 minutes to form a cured intermediate coating film with a lightness of 60 (light receiving angle 45°). Next, the first paint composition was air spray coated to a dry film thickness of 11 μm under conditions of room temperature 23 ° C. and humidity 68%. After setting for 4 minutes, the coating was preheated at 80 ° C. for 5 minutes. After preheating, the second paint composition was air spray coated wet-on-wet to a dry film thickness of 4 μm under conditions of room temperature 23 ° C. and humidity 68%. After setting for 4 minutes, the coating was preheated at 80 ° C. for 5 minutes. After preheating after coating with the second paint composition, the coated plate was allowed to cool to room temperature, and a clear paint, MACFLOW-O-1810 (a solvent-based clear paint manufactured by Nippon Paint Automotive Coatings Co., Ltd.), was air spray coated to a dry film thickness of 35 μm and allowed to set for 7 minutes. The coated plate was then baked in a dryer at 140 ° C. for 30 minutes to obtain a coated test plate having a multi-layer coating film.

[0115] Other Examples and Comparative Examples Multilayer coating films were prepared in the same manner as in Example 1, except that the compositions of the first and second coating compositions, the brightness of the intermediate coating film, and the film thickness of the multilayer coating film were as shown in the tables below. In each table, the formulation of each coating composition other than the pigment component is the same as in Example 1, so it is omitted. The content of the pigment component in each table indicates the PWC (Pigment Weight Concentration) in the paint.

[0116] Details of the abbreviations in the table below are as follows: Pigment A-1: ​​Black Diamond M010-1, manufactured by Ako Kasei, base material: natural mica, coating material: sintered titanium and titanium oxide, average particle size: 10 μm Pigment A-2: Black Diamond M010-2, manufactured by Ako Kasei, base material: natural mica, coating material: sintered titanium and titanium oxide, average particle size: 10 μm Pigment A-3: Ronastar Diamond Black IQ, manufactured by Merck, base material: Al ２ O ３ , Covering material: TiO ２ / SiO ２ / Fe ２ O ３ , average particle size: 10 μm Pigment A-4: NK Black, manufactured by Nihon Koken Kogyo, base material: Al ２ O ３ , coating material: black iron oxide (iron tetroxide: Fe ３ O ４ ), average particle size: 11 μm Pigment A-5: Talc Black, manufactured by Nihon Koken Kogyo Co., Ltd. Base material: talc, Coating material: black iron oxide (iron tetroxide: Fe ３ O ４ ), average particle size: 8 μm Pigment A-6: FD-5090, manufactured by Asahi Kasei, substrate: aluminum, coating material: - (none), average particle size: 9 μm Pigment A-7: ST1018RSJ3, manufactured by Nippon Sheet Glass, substrate: glass flake, coating material: TiO ２ , average particle size: 18 μm Pigment A-8: Xirallic NXT M260-60 Panthera Silver, manufactured by Merck, substrate: alumina flakes, coating material: iron titanate (FeTiO ３ ), average particle size: 20 μm. Pigment A-9: Iriodin 602 WNT, manufactured by Merck, substrate: mica, coating material: iron titanate (FeTiO ３), metal oxide (black), average particle size: 19 μm. Pigment A-10: SB-10, manufactured by Asahi Kasei Corporation, base material: ground aluminum pigment, coating material: none, average particle size: 10 μm. Pigment A-11: 93-0647, manufactured by Toyo Aluminum Corporation, base material: aluminum, coating material: - (none), average particle size: 20 μm. Pigment A-12: IRIODIN NEW TG BLUE WNT / IRIODIN 612 RUTILE WNT, manufactured by Merck & Co., Ltd., base material: mica, coating material: iron titanate (FeTiO ３ ), average particle size: 7 μm. Pigment A-13: Iriodin 121 / 221 / 111 / 219, manufactured by Merck, base material: mica, coating material: titanium oxide, average particle size: 10 μm / 10 μm / 7 μm / 20 μm, respectively. Pigment A-14: Luxan CFX B502, manufactured by Eckart, base material: glass flake, coating material: TiO ２ , average particle size: 25 μm Pigment A-15: A-903S / A-781D, manufactured by CQV, base material: artificial mica, coating material: TiO ２ , average particle size: 20 μm Pigment A-16: A-781K-SP / A-761-SP, manufactured by CQV, base material: artificial mica, coating material: TiO ２ , average particle size: 18 μm / 20 μm, respectively. Pigment A-17: UC-6700 / 4640NS / CP-315, manufactured by Nippon Boshū Kogyo, Toyo Aluminum, and Asahi Kasei, respectively. Base material: aluminum flake. Coating material: none. Average particle size: 16 μm / 12 μm / 15 μm, respectively.

[0117] Pigment B-1: R5000, manufactured by Birla, carbon black. Pigment B-2: E-2020, manufactured by Cabot, carbon black. Pigment B-3: EH8082, manufactured by Sun Chemical, perylene black. Pigment B-4: FW200, manufactured by Orion, carbon black.

[0118] Pigment C-1: 400RG, manufactured by Tosoh, Quinacridone Red Pigment C-2: G-314, manufactured by Sanyo Dyes, Cyanine Blue Pigment C-3: BLUE6480, manufactured by Sun Chemical, Threne Blue Pigment C-4: 5206H / FVP336, manufactured by Dainichiseika Color & Chemicals / Clariant, Cyanine Blue / Dioxane Violet Pigment C-5: CR-97, manufactured by Ishihara Sangyo Kaisha, Titanium

[0119] The multi-layer coating films formed in the above Examples and Comparative Examples were evaluated as follows. The evaluation results are shown in the following table.

[0120] Brightness strength of multi-layer coating film Si １５ Measurement of brightness intensity Si １５ was measured using a BYK-maci (multi-angle (6-angle) colorimeter, glitter and particle feel meter) manufactured by BYK.

[0121] Multi-layer coating saturation C ＊ １５ Measurement of chroma C ＊ １５ The values ​​were measured using a BYK-maci (multi-angle (6-angle) colorimeter, glitter and particle feel meter) manufactured by BYK.

[0122] Lightness L of multi-layer coating ＊ １５ and lightness L ＊ １１０ Measurement of lightness L ＊ １５ and lightness L ＊ １１０ was measured using a BYK-maci (multi-angle (6-angle) colorimeter, glitter and particle feel meter) manufactured by BYK.

[0123] Appearance Evaluation of Multilayer Coating Films The coated test panels having the multilayer coating films formed in each of the Examples and Comparative Examples were visually observed and evaluated according to the following criteria: A and B were considered to be acceptable.

[0124] Evaluation criteria A: While it can be recognized as black, there is a soft feeling and a moderate sense of shading. B: Although a slight color and brightness can be felt, it is recognized as being within the black category, but at the same time, there is a soft feeling and a moderate sense of shading. C: The brightness and brightness in the highlights are high, so it falls outside the black category and is not a coating that is "black but also has softness and a sense of shading." D: Only the black color is visible and the sense of shading and softness cannot be recognized. E: Although it is a dark color, the color can be recognized, so it falls outside the black category. F: The brightness and brightness in the highlights are high, and although it is a dark color, the color can be recognized, so it falls outside the black category. G: The brightness and brightness in the highlights are high, so it falls outside the black category and the sense of shading and softness cannot be recognized.

[0125]

[0126]

[0127]

[0128] It was confirmed that all of the multi-layer coating films of the Examples were coating films that could be recognized as black, yet had a suitable sense of shading.

[0129] The multi-layer coating films of Comparative Examples 1 and 2 have a chroma of C ＊ １５ This is an example where the value exceeds 6. In this example, the coating film lacked denseness and had high saturation, so it fell outside the black color category.

[0130] The multi-layer coating films of Comparative Examples 3 to 8 have a brightness of L ＊ １１０ exceeds 3, L ＊ １５ / L ＊ １１０ This is an example where the value is 9 or less. In this example, the coating film does not have a proper sense of shading, or is outside the black color category.

[0131] The multi-layer coating films of Comparative Examples 9 to 11 are L ＊ １５ / L ＊ １１０ In this example, L is outside the range of 9 to 24. ＊ １５ / L＊ １１０ If it is too low, there will be no appropriate shadow effect. ＊ １５ / L ＊ １１０ If the value is too high, the luminance and brightness in the highlights will be too high, and the coating will fall outside the black range.

[0132] The multi-layer coating films of Comparative Examples 23 and 24 have a brightness intensity of Si １５ is outside the range of 2 or more and 10 or less. １５ If the value is too low, only black is visible, and the sense of shadow and softness cannot be recognized. １５ If the value is too high, the luminance and brightness in the highlights will be too high, and the coating will fall outside the black range.

[0133] The multilayer coating film of the present disclosure is a coating film that can be recognized as black, yet has a moderate sense of shading and is excellent in design. Coated articles having the above multilayer coating film can be suitably used as various articles (for example, automobile bodies and parts thereof such as passenger cars, trucks, motorcycles, and buses).

Claims

1. A multi-layer coating film comprising a first coating film, a second coating film, and a clear coating film in this order, wherein the first coating film contains a black pigment, and the second coating film contains a lustrous black scale-like pigment and a black pigment, and the L is determined based on the spectral reflectance of incident light incident at an angle of 45 degrees to the surface of the multi-layer coating film and reflected light received at an angle of 15 degrees to the specular reflected light. ＊ C ＊ Chroma C in the h color system ＊ １５ is 6 or less, and the L is based on the spectral reflectance of reflected light received at an angle of 110 degrees relative to the specular reflection light when incident light is incident at an angle of 45 degrees to the surface of the multi-layer coating film. ＊ C ＊ Lightness L in the h color system ＊ １１０ is 3 or less, and L is based on the spectral reflectance of reflected light received at an angle of 15 degrees relative to the specular reflection light when incident light is incident at an angle of 45 degrees to the surface of the multi-layer coating film. ＊ C ＊ Lightness L in the h color system ＊ １５ and the lightness L ＊ １１０ The ratio L ＊ １５ / L ＊ １１０ is 9 or more and 24 or less, and a light receiving unit is arranged in a direction perpendicular to the surface of the multilayer coating film, and light is irradiated onto the surface of the multilayer coating film at an angle of 15 degrees with respect to the perpendicular direction, and the brilliance intensity Si measured by the light receiving unit is １５ A multi-layer coating film, wherein the number of layers is 2 or more and 10 or less.

2. The multi-layer coating film according to claim 1, wherein the lustrous black scale-like pigment contained in the second coating film is a scale-like pigment having a titanium sintered layer.

3. A multi-layer coating film according to claim 1 or 2, wherein the lustrous black scale-like pigment contained in the second coating film is a scale-like pigment having a titanium sintered layer on a mica flat plate substrate.

4. A multi-layer coating film as described in any one of claims 1 to 3, wherein the content of the lustrous black scale-like pigment contained in the second coating film is 10% by mass or more and 30% by mass or less in terms of PWC, and the content of the black pigment contained in the second coating film is 2% by mass or more and 12% by mass or less in terms of PWC.

5. A multi-layer coating film according to any one of claims 1 to 4, wherein the content of the black pigment contained in the first coating film is 1.5 mass % or more and 5 mass % or less in terms of PWC.

6. A multi-layer coating film according to any one of claims 1 to 5, wherein the average particle size of the lustrous black scale-like pigment contained in the second coating film is 5 to 14 μm.

7. A coated article comprising: a substrate; and a multilayer coating film according to any one of claims 1 to 6 provided on said substrate.

8. A method for forming a multi-layer coating film by sequentially applying a first coating composition, a second coating composition, and a clear coating composition to an object to be coated, wherein the first coating composition contains a black pigment, and the second coating composition contains a lustrous black scale-like pigment and a black pigment, and wherein the L is calculated based on the spectral reflectance of incident light incident at an angle of 45 degrees to the surface of the multi-layer coating film and reflected light received at an angle of 15 degrees to the regular reflected light. ＊ C ＊ Chroma C in the h color system ＊ １５ is 6 or less, and the L is based on the spectral reflectance of reflected light received at an angle of 110 degrees relative to the specular reflection light when incident light is incident at an angle of 45 degrees to the surface of the multi-layer coating film. ＊ C ＊ Lightness L in the h color system ＊ １１０ is 3 or less, and L is based on the spectral reflectance of reflected light received at an angle of 15 degrees relative to the specular reflection light when incident light is incident at an angle of 45 degrees to the surface of the multi-layer coating film. ＊ C ＊ Lightness L in the h color system ＊ １５ and the lightness L ＊ １１０ The ratio L ＊ １５ / L ＊ １１０ is 9 or more and 24 or less, and a light receiving unit is arranged in a direction perpendicular to the surface of the multilayer coating film, and light is irradiated onto the surface of the multilayer coating film at an angle of 15 degrees with respect to the perpendicular direction, and the brilliance intensity Si measured by the light receiving unit is １５ is 2 or more and 10 or less.

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