Multilayer coating film and method for producing coated article

Abstract

To provide a multilayer coated film in which soft brightness and brilliance can be exhibited in a view from any angle, and a production method of a coated article including the multilayer coated film.SOLUTION: A multilayer coated film has a first coated film, a second coated film, and a clear coated film in this order. The first coated film contains a flaky metallic pigment having an average particle diameter of 3 μm or more and 13 μm or less, and the second coated film contains a flaky mica pigment having an average particle diameter of 3 μm or more and less than 15 μm and a brilliant pigment having an average particle diameter of 15 μm or more and 30 μm or less. In the multilayer coated film, a blazing area Sa15 at incidence angle of 15°, a blazing area Sa45 at incidence angle of 45°, and a blazing area Sa75 at incidence angle of 75°are provided at an average of 5 or more and 20 or less, and a standard deviation thereof are 3 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a multi-layer coating and a coated article. [Background technology]

[0002] Automobiles typically have a multi-layer paint film including a base paint film and a clear paint film. Traditionally, automobile exteriors have required a luxurious feel, and multi-layer paint films with a strong metallic finish and high flip-flop properties have often been formed. For example, Patent Document 1 discloses a multi-layer paint film whose metallic texture changes depending on the viewing angle and whose flip-flop properties are pronounced. Patent Document 2 discloses a multi-layer paint film with a sparkling sheen due to multi-directional reflection. Patent Document 3 discloses a multi-layer paint film that has high gloss in highlights and high brightness overall from highlights to shades. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 08-238451 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-275421 [Patent Document 3] International Publication No. 2017 / 135426 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the diversification of consumer tastes and the pursuit of originality have led to a wide variety of designs being required for multi-layer coating films. The present invention aims to provide a multi-layer coating film with a design different from that of Patent Documents 1 to 3, which has a low metallic tone and flip-flop effect and which expresses a soft shine and sparkle from any angle. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention provides the following aspects. [1] A multi-layer coating film having a first coating film, a second coating film, and a clear coating film in this order, the first coating film contains a scaly metallic pigment having an average particle diameter of 3 μm or more and 13 μm or less, the second coating film contains a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm, and a luster pigment having an average particle size of 15 μm or more and 30 μm or less, The luminous area Sa of the multilayer coating film at a light incident angle of 15° 15 , the luminous area Sa at a light incidence angle of 45° 45 , and the luminous area Sa at a light incidence angle of 75° 75 is a multi-layer coating film with an average of 5 to 20 and a standard deviation of 3 or less. [2] The multi-layer coating film according to [1] above, wherein the granularity value of the multi-layer coating film is 2 or more and 4.5 or less. [3] The multilayer coating film of [1] or [2] above, wherein in the second coating film, the ratio Wm / Wg of the mass Wm of the scaly mica pigment to the mass Wg of the bright pigment is 5 or more and 150 or less. [4] The lightness L of the multilayer coating film at a light incident angle of 45° and a light receiving angle of 15° * 15 The multi-layer coating film of [1] or [2] above, wherein the viscosity is 70 or more and 110 or less. [5] The object to be coated A coated article having the multilayer coating film of [1] or [2] above provided on the substrate. [6] A method for producing a coated article, comprising sequentially applying a first coating composition, a second coating composition, and a clear coating composition to an object to be coated to form a multi-layer coating film, The first coating composition contains a scaly metallic pigment having an average particle size of 3 μm or more and 13 μm or less, The second coating composition contains a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm, and a luster pigment having an average particle size of 15 μm or more and 30 μm or less, The luminous area Sa of the multi-layer coating film at a light incident angle of 15° 15 , the luminous area Sa at a light incidence angle of 45° 45 , and the luminous area Sa at a light incidence angle of 75° 75 A method for producing a coated article, wherein the average is 5 or more and 20 or less, and the standard deviation is 3 or less. [7] A multi-layer coating film having a first coating film, a second coating film, and a clear coating film in this order, the first coating film contains a scaly metallic pigment having an average particle diameter of 3 μm or more and 13 μm or less, the second coating film contains a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm, and a luster pigment having an average particle size of 15 μm or more and 30 μm or less, A multi-layer coating film, wherein in the second coating film, the ratio Wm / Wg of the mass Wm of the scaly mica pigment to the mass Wg of the bright pigment is 5 or more and 150 or less. [Effects of the Invention]

[0006] According to the present invention, there are provided a multi-layer coating film that exhibits a soft shine and sparkle when viewed from any angle, and a method for producing a coated article having this multi-layer coating film. DETAILED DESCRIPTION OF THE INVENTION

[0007] [Multi-layer coating] First embodiment A multilayer coating film according to one embodiment of the present disclosure comprises a first coating film, a second coating film, and a clear coating film, in that order. The first coating film contains a scaly metallic pigment having an average particle size of 3 μm or more and 13 μm or less. The second coating film contains a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm, and a luster pigment having an average particle size of 15 μm or more and 30 μm or less.

[0008] Brightness area Sa of multi-layer coating at a light incident angle of 15° 15 , the luminous area Sa at a light incidence angle of 45° 45 , and the luminous area Sa at a light incidence angle of 75° 75 has a mean between 5 and 20 and a standard deviation of 3 or less.

[0009] The first and second coatings are called metallic base coatings and affect the brilliance of the multi-layer coating. The second coating is located closer to the outer surface of the coated article than the first coating. The clear coating is located closer to the outer surface of the coated article than the second coating.

[0010] In this disclosure, two metallic base coatings are provided, with the lower first coating containing small scale metallic pigments, and the upper second coating containing small scale mica pigments and large luster pigments. This suppresses an excessive metallic texture and creates a soft shine while still retaining a bright sparkle.

[0011] The scale-like metallic pigment in the first coating is small, so it can express a metallic tone and a fine shine with reduced glare. The scale-like mica pigment in the second coating is also small, so there is a lot of diffuse reflection, making the multi-layer coating shine softly. The sparkle is a glittering appearance, and is expressed by the large luster pigment blended in the second coating. This large luster pigment has a luminous area Sa at a light incident angle of 15°. 15 , the luminous area Sa at a light incidence angle of 45° 45 , and the luminous area Sa at a light incidence angle of 75° 75 The formula is formulated so that the average is between 5 and 20. The combined effect of the first and second coatings with this composition allows the multi-layer coating to express a sparkling sparkle within a soft shine.

[0012] In addition, the multi-layer coating film according to the present disclosure has a luminous area Sa 15 ,Sa 45 ,Sa 75The standard deviation of is small. In other words, the multilayer coating film according to the present disclosure does not have the so-called flip-flop property (also called angle dependency) in which the brightness changes depending on the viewing angle, but rather allows a certain moderate brightness to be perceived when viewed from any direction, such as highlight / face / shade. In other words, the multilayer coating film according to the present disclosure allows a soft brightness and sparkle to be perceived when viewed from any angle.

[0013] The multi-layer coating film may have a color coating film interposed between the second coating film and the clear coating film. The color coating film may contain a color pigment but may not contain a luster pigment.

[0014] (Luminous area Sa) The sparkle area Sa reflects the area of ​​the shiny part on the coating surface (sparkle area) and is an index of sparkle. The larger the sparkle area Sa, the stronger the metallic texture. Sparkle area Sa 15 , bright area Sa 45 and luminous area Sa 75 The average is between 5 and 20. Therefore, it does not have a strong metallic look, but rather a soft shine. 15 , Sa 45 , and Sa 75 The average of the luminous area Sa may be 8 or more, and may be 10 or more. 15 , Sa 45 , and Sa 75 The average may be 19 or less, or may be 18 or less.

[0015] Bright area Sa 15 , Sa 45 , and Sa 75 The standard deviation of the brilliance area Sa is less than 3. This allows the multi-layer coating to have a consistent brilliance no matter what angle you look at it from. 15 , Sa 45 , and Sa 75 The standard deviation of the luminous area Sa may be 2.95 or less, or may be 2.90 or less. 15 , Sa 45 , and Sa 75The standard deviation of may be 0.1 or more.

[0016] The luminous area Sa is calculated as follows: Light is irradiated from the clear coating side of the multi-layer coating at an incident angle of 15°, and the coating surface is photographed from the normal direction with a CCD camera. The obtained image is analyzed using an image analysis algorithm that uses a histogram of brightness levels, and a two-dimensional analysis is performed. This results in the luminous area Sa 15 Repeat this procedure except that the incident angle is changed to 45° and 75°, and the luminous area Sa 45 and Sa 75 The light source may be, for example, an LED light. The luminous area Sa can be obtained using, for example, a spectrophotometer "BYK-mac i" manufactured by BYK.

[0017] The glittering area Sa is affected by the size and content of the glittering pigment. The glittering area Sa is particularly affected by the size and content of the glittering pigment contained in the second coating film. For example, when the mass ratio of the mass Wm of the small particle size mica pigment to the mass Wg of the large particle size glittering pigment is 5 or more and 150 or less, the glittering area Sa 15 , Sa 45 , and Sa 75 The mean can be between 5 and 20, and the standard deviation can be less than 3.

[0018] Standard deviation is an index that shows the dispersion of data. The standard deviation of the luminous area Sa is 15 , bright area Sa 45 and luminous area Sa 75 The difference between each of these values ​​and the average is squared, the sum is then divided by the total number of data points (3 in this case) and the positive square root is calculated.

[0019] (Granularity value) The graininess value of the multilayer coating film may be 2 or more and 4.5 or less. The graininess value reflects the uniformity of light and dark areas in a multilayer coating film irradiated with diffused light, and is an index of the density of the coating film. The smaller the graininess value (hereinafter referred to as G value), the denser the film and the stronger the perceived metallic texture. When the G value is 2 or more and 4.5 or less, the impression of density is given, while the metallic texture is suppressed. The G value may be 2.3 or more, or may be 2.5 or more. The G value may be 4.3 or less, or may be 4.0 or less.

[0020] The G value is calculated as follows: Diffused light is irradiated from a light source installed inside a white-painted hemisphere toward the clear coating of a multi-layer coating. The multi-layer coating is photographed from its normal direction with a CCD camera, and the image is analyzed using a specific image analysis algorithm. This gives the G value. The G value can be obtained, for example, using the "BYK-mac i" manufactured by BYK.

[0021] (Lightness L * 15 ) Lightness L of multi-layer coating film at a light incident angle of 45° and a light receiving angle of 15° * 15 is 110 or less. * 15 is calculated from the spectral reflectance of light incident on a multi-layer coating at an incident angle of 45° and received at an angle of 15° relative to the specular reflection. * C * Lightness L in the h color system * In metallic base coatings, the lightness L * The larger the value, the stronger the metallic texture.

[0022] The light receiving angle of 15° is the so-called highlight condition, and the lightness L is lower than the shade and face conditions. * The lightness L under conditions where brightness is more easily perceived * 15 By keeping the lightness L below 110, the metallic texture is suppressed and a soft shine is easily obtained. *15 The lightness L may be 105 or less, or may be 100 or less. * 15 may be 70 or more, and may be 75 or more.

[0023] Lightness L * L * C * is a parameter in the h color system. * represents the brightness, and C represents the * represents the saturation and h represents the hue angle. * The larger the value, the more vivid the color, and the smaller the value, the more dull the color. * As the value of increases, the measured substance becomes brighter, and as the value decreases, the measured substance becomes darker.

[0024] L * C * h color system is CIEL * a * bColor system (CIE1976L * a * b * Calculated based on the CIE1976L color space. * a * b * The color space can be calculated in accordance with JIS Z 8781-4. * a * The b color system is defined by the International Commission on Illumination and is described in Section 4.2 of CIE Publication 15.2 (1986). Lightness L * 15 can be obtained, for example, using "BYK-mac i" manufactured by BYK.

[0025] Lightness L * 15 is measured using a coated article in which a gray coating film (intermediate coating film) is provided between the substrate and the first coating film.

[0026] (First coating) The first coating film contains a scaly metallic pigment having an average particle size of 3 μm or more and 13 μm or less (hereinafter referred to as a small particle size metallic pigment). The first coating film is typically a cured product of a first paint composition containing the small particle size metallic pigment and a first coating film-forming resin.

[0027] The first coating film may have a film thickness after curing of 3 μm or more and 13 μm or less. The cured film thickness of the first coating film may be 3.5 μm or more. The cured film thickness of the first coating film may be 10 μm or less, or may be 8 μm or less.

[0028] <Small particle size metallic pigment> Small particle size metallic pigments are scale-like metallic pigments with an average particle size of 3 μm to 13 μm. Small particle size metallic pigments suppress glare while expressing a fine sparkle.

[0029] Examples of materials for metallic pigments include aluminum, copper, zinc, iron, nickel, tin, and alloys thereof, and aluminum is particularly preferred.

[0030] The term "scaly" refers to a shape in which the aspect ratio (average major axis of the pigment / average thickness of the pigment) exceeds 1.0. The aspect ratio of a scaly pigment is, for example, 20 or more and 300 or less. The aspect ratio of a scaly pigment may be 30 or more. The aspect ratio of a scaly pigment may be 200 or less.

[0031] The average particle size of the small particle size metallic pigment may be 4 μm or more, or 5 μm or more. The average particle size of the small particle size metallic pigment may be 12 μm or less, or 10 μm or less. Multiple types of small particle size metallic pigments with different average particle sizes may be used in combination.

[0032] The average particle size of a scaly pigment is the average value of the long diameter. The average particle size is obtained by observing the scaly pigment using a shape analysis laser microscope (for example, VK-X 250 manufactured by Keyence Corporation) and averaging the long diameters (maximum lengths) of 100 arbitrarily selected scaly pigment particles.

[0033] The average thickness of the small particle diameter metallic pigment is, for example, 0.01 μm or more and 0.1 μm or less. The average thickness of the small particle diameter metallic pigment may be 0.04 μm or more. The average thickness of the small particle diameter metallic pigment may be 0.08 μm or less. This can further increase the density of the multilayer coating film.

[0034] The average thickness of the scaly pigments is obtained by observing the cross section of a coating film containing the scaly pigments using a transmission electron microscope (TEM) and averaging the thicknesses of 100 arbitrarily selected scaly pigments.

[0035] The small particle size metallic pigment may or may not be surface-treated. Examples of compounds used for surface treatment include metal oxide compounds, phosphorus compounds, amine compounds, and silane compounds.

[0036] Examples of metal oxide compounds include metal oxides containing transition metal elements, their alkali metal salts, and their ammonium salts. Specific examples include molybdenum trioxide, molybdic acid, alkali metal molybdates, ammonium molybdates, vanadic acid, alkali metal vanadates, and ammonium vanadates. Examples of alkali metals include sodium and potassium. Examples of metal oxide compounds include at least one selected from the group consisting of molybdic acid, alkali metal molybdates, ammonium molybdates, vanadic acid, alkali metal vanadates, and ammonium vanadates.

[0037] Examples of phosphorus compounds include organic phosphates, organic phosphites, organic phosphonic acids, and amine salts of these compounds. The phosphorus compounds may be used alone or in combination of two or more.

[0038] Examples of the amine compound include linear or branched primary amines, linear or branched secondary amines, linear or branched tertiary amines, alicyclic primary amines, alicyclic secondary amines, alicyclic tertiary amines, aromatic group-containing primary amines, aromatic group-containing secondary amines, and aromatic group-containing tertiary amines. The amine compound may have a substituent (e.g., a hydroxyl group). The amine compound may be used alone or in combination of two or more.

[0039] Examples of silane compounds include alkoxysilane compounds, vinyl group-containing silane coupling agents, epoxy group-containing silane coupling agents, styryl group-containing silane coupling agents, (meth)acrylic group-containing silane coupling agents, amino group-containing silane coupling agents, isocyanate group-containing silane coupling agents, ureido group-containing silane coupling agents, mercapto group-containing silane coupling agents, acid anhydride group-containing silane coupling agents, and partial condensates thereof. The silane compounds may be used alone or in combination of two or more.

[0040] The surface treatment of the small particle diameter metallic pigment can be carried out under treatment conditions commonly used by those skilled in the art. The above surface treatments can be carried out either alone or in combination of two or more.

[0041] Commercially available small particle size metallic pigments include, for example, the Alpaste 46 series, 97 series (typically 0519), and 01 series (typically 01-0651) manufactured by Toyo Aluminum Co., Ltd.; the Aluminum Paste FD series manufactured by Asahi Kasei Corporation; and Metallux 4860 manufactured by Ecart.

[0042] The content of the small particle size metallic pigment, i.e., the mass ratio (PWC) of the small particle size metallic pigment to the solid content of the resin contained in the first coating composition, is, for example, 3 mass% or more and 13 mass% or less. The PWC of the small particle size metallic pigment may be 4 mass% or more, or 5 mass% or more. The PWC of the small particle size metallic pigment may be 10 mass% or less, or 8 mass% or less. The solid content of the resin refers to the solid content of all resin components, such as the first coating film-forming resin and curing agent described below.

[0043] Other Photochromic Pigments The first coating film may contain a luster pigment other than the small particle diameter metallic pigment. Examples of other luster pigments include mica pigments such as interference mica, white mica, and colored mica; graphite pigments; glass flake pigments; and scaly metallic pigments with an average particle size of more than 13 μm.

[0044] The content of other luster pigments (particularly the small-particle-size mica pigment and large-particle-size luster pigment described below) is within a range that does not impair the effects of the coating composition according to the present disclosure. The content of other luster pigments (PWC) may be, for example, less than 3 mass %, 1 mass % or less, or 0 mass %. The types and masses of the luster pigments blended into the first and second coating films may be different from each other.

[0045] (First paint composition) The first coating composition may include a small particle size metallic pigment and a first film-forming resin. The first coating composition may further include a curing agent capable of reacting with the first film-forming resin.

[0046] The first coating composition may be water-based or solvent-based. A water-based first coating composition may contain water as a solvent, and optionally a water-soluble or water-miscible organic solvent. A solvent-based first coating composition may contain, for example, an ester-based solvent, an ether-based solvent, an alcohol-based solvent, a ketone-based solvent, an aliphatic hydrocarbon-based solvent, or an aromatic solvent. The first coating composition may be diluted with a suitable solvent before use.

[0047] The first coating composition is prepared by kneading and dispersing the small particle size metallic pigment, the first film-forming resin, the curing agent, etc. using a disperser, homogenizer, kneader, etc. A pigment paste may be prepared in advance using a pigment such as the small particle size metallic pigment and a pigment dispersant, and this may then be mixed with the first film-forming resin, etc.

[0048] 《First coating film forming resin》 Examples of the first coating film-forming resin include acrylic resin, acrylic silicone resin, polyester resin, polyurethane resin, epoxy resin, fluororesin, and silicone resin. These may be used alone or in combination of two or more. Among these, acrylic resin is preferred.

[0049] In the aqueous coating composition, these resins may be contained as an emulsion, a dispersion, or in a state dissolved in a solvent.

[0050] For example, acrylic resin emulsions can be prepared by emulsion polymerization of α,β-ethylenically unsaturated monomers. Examples of α,β-ethylenically unsaturated monomers include (meth)acrylic acid esters, α,β-ethylenically unsaturated monomers having an acid group, and α,β-ethylenically unsaturated monomers having a hydroxyl group. The monomers can be used alone or in combination of two or more.

[0051] Examples of (meth)acrylic acid esters 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, and dihydrodicyclopentadienyl (meth)acrylate. (Meth)acrylic acid esters refer to acrylic acid esters and methacrylic acid esters.

[0052] 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.

[0053] 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 of these with ε-caprolactone.

[0054] Other α,β-ethylenically unsaturated monomers may be used in combination. 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.

[0055] The emulsion polymerization method is not particularly limited. For example, an emulsifier is dissolved in an aqueous medium containing water or, if necessary, an organic solvent such as an alcohol or an ether (e.g., dipropylene glycol methyl ether, propylene glycol methyl ether, etc.), and an α,β-ethylenically unsaturated monomer and a polymerization initiator are added dropwise under heating and stirring. The α,β-ethylenically unsaturated monomer may be previously emulsified with an emulsifier.

[0056] Polymerization initiators and emulsifiers commonly used by those skilled in the art can be used. If necessary, a chain transfer agent such as a mercaptan (e.g., lauryl mercaptan) or α-methylstyrene dimer may be used to adjust the molecular weight. The reaction temperature, reaction time, and other parameters can be appropriately selected within the ranges commonly used by those skilled in the art. The resulting acrylic resin emulsion is neutralized with a base, if necessary.

[0057] The acrylic resin (acrylic resin emulsion) obtained by emulsion polymerization may have a number average molecular weight of 3,000 or more. The acrylic resin may have a hydroxyl value (solid content hydroxyl value) of 20 mgKOH / g or more and 180 mgKOH / g or less. The acrylic resin may have an acid value (solid content acid value) of 1 mgKOH / g or more and 80 mgKOH / g or less.

[0058] The number average molecular weight is determined by the GPC method using polystyrene as the standard. The acid value and hydroxyl value are calculated from the monomer composition used in the preparation based on JIS regulations.

[0059] The acrylic resin dispersion can be prepared, for example, by solution polymerizing the above-mentioned α,β-ethylenically unsaturated monomer and dispersing the resultant with a basic compound.

[0060] The water-soluble acrylic resin can be prepared, for example, by solution polymerizing the above-mentioned α,β-ethylenically unsaturated monomer and then solubilizing it in water using a basic compound.

[0061] The acrylic resin incorporated into the solvent-based coating composition can be prepared, for example, by solution polymerization of an α,β-ethylenically unsaturated monomer. The acrylic resin has a number average molecular weight of, for example, 1,000 to 20,000. The acrylic resin may have an acid value (solid content acid value) of 1 mgKOH / g to 80 mgKOH / g. The acrylic resin may have a hydroxyl value (solid content hydroxyl value) of 101 mgKOH / g to 200 mgKOH / g.

[0062] Hardener The first coating composition may include a curing agent that reacts with the first film-forming resin to form the first coating therewith.

[0063] Examples of curing agents 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 of two or more. Among these, at least one of melamine resins and blocked isocyanate compounds may be used.

[0064] The melamine resin may be water-soluble or water-insoluble. 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. The melamine resin may also be a mononuclear compound consisting of one melamine nucleus.

[0065] Commercially available melamine resins may be used. 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.

[0066] The blocked isocyanate compound can be prepared by adding a blocking agent having an active hydrogen to a polyisocyanate such as trimethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, or isophorone diisocyanate.

[0067] The content of the curing agent may be 10% by mass or more and 80% by mass or less of the resin solid content contained in the first coating composition. The content of the curing agent may be 15% by mass or more. The content of the curing agent may be 60% by mass or less.

[0068] Other pigments The first coating composition may contain a pigment other than the luster pigment. Examples of the other pigment include a coloring pigment, an extender pigment, and an anti-rust pigment. The content of the other pigment is not particularly limited as long as the effect of the coating composition according to the present disclosure is not impaired.

[0069] 《Organic compounds containing phosphate groups》 The first coating composition may further contain a phosphate group-containing organic compound, which facilitates improving the dispersibility of the luster pigment, particularly the scaly metallic pigment.

[0070] The content of the phosphate group-containing compound may be 0.1% by mass or more and 15% by mass or less of the total solid content of the first coating composition. The content of the phosphate group-containing compound may be 1% by mass or more. The content of the phosphate group-containing compound may be 12% by mass or less.

[0071] The phosphate group-containing compound is not particularly limited as long as it has a phosphate group (-P(=O)(OR)2 (where each R is independently hydrogen or a hydrocarbon group)). Examples of the phosphate group-containing compound include at least one of an alkyl phosphate ester having an alkyl group with 4 to 30 carbon atoms and a phosphate group-containing polymer having a phosphate group value of 5 mgKOH / g or more and 300 mgKOH / g or less.

[0072] <Alkyl phosphate ester> The alkyl phosphate ester has an alkyl group having 4 to 30 carbon atoms. Examples of the alkyl phosphate ester include monoalkyl phosphate ester, dialkyl phosphate ester, and mixtures thereof. In the dialkyl phosphate ester, the two alkyl groups may be the same or different. The dialkyl phosphate ester preferably has the same two alkyl groups.

[0073] Examples of alkyl groups having 4 to 30 carbon atoms include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, docosyl, tetracosyl, hexacosyl, and octacosyl. The alkyl group may be linear or branched.

[0074] Examples of alkyl phosphate esters include butyl acid phosphate (a mixture of monobutyl phosphate ester and dibutyl phosphate ester), 2-ethylhexyl acid phosphate (a mixture of mono-2-ethylhexyl phosphate ester and di-2-ethylhexyl phosphate ester), isodecyl acid phosphate (a mixture of monoisodecyl phosphate ester and diisodecyl phosphate ester), dilauryl acid phosphate, lauryl acid phosphate (a mixture of monolauryl phosphate ester and dilauryl phosphate ester), tridecyl acid phosphate (monotridecyl phosphate), Examples of suitable oleic acid phosphates include monostearyl acid phosphate, distearyl acid phosphate, stearyl acid phosphate (a mixture of monostearyl phosphate and distearyl phosphate), isostearyl acid phosphate (a mixture of monoisostearyl phosphate and diisostearyl phosphate), oleyl acid phosphate (a mixture of monooleyl phosphate and dioleyl phosphate), and behenyl acid phosphate (a mixture of monobehenyl phosphate and dibehenyl phosphate).

[0075] <Phosphate group-containing polymer> The phosphate group-containing polymer has a phosphate value of 5 mgKOH / g or more and 300 mgKOH / g or less. The phosphate group value of the phosphate group-containing polymer may be 10 mgKOH / g or more, or 50 mgKOH / g or more. The phosphate group value of the phosphate group-containing polymer may be 250 mgKOH / g or less, or 150 mgKOH / g or less.

[0076] The phosphate value is calculated based on JIS K5601 2-1 Acid Value Measurement Method. Specifically, the acid value is the number of milligrams of potassium hydroxide (KOH) required to neutralize the free acid in 1 g of nonvolatile matter of the product.

[0077] The number average molecular weight of the phosphate group-containing polymer is, for example, 1,000 or more and 50,000 or less. The number average molecular weight of the phosphate group-containing polymer may be 3,000 or more, or 5,000 or more. The number average molecular weight of the phosphate group-containing polymer may be 30,000 or less, or 20,000 or less.

[0078] Examples of phosphate group-containing polymers include acrylic resins, polyester resins, polyether resins, and epoxy resins, each having a phosphate group value of 5 mgKOH / g or more and 300 mgKOH / g or less. These may be used alone or in combination of two or more. Among these, phosphate group-containing acrylic resins are preferred from the viewpoint of water resistance. The phosphate group-containing acrylic resin can be obtained, for example, by polymerizing a phosphate group-containing α,β-ethylenically unsaturated monomer, or by copolymerizing this monomer with another α,β-ethylenically unsaturated monomer that does not contain a phosphate group.

[0079] Additives The first coating composition may contain additives commonly used by those skilled in the art, such as surface conditioners, viscosity control agents, thickeners, antioxidants, ultraviolet inhibitors, and antifoaming agents.

[0080] (Second coating) The second coating film contains a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm (hereinafter referred to as a small particle size mica pigment) and a luster pigment having an average particle size of 15 μm or more and 30 μm or less (hereinafter referred to as a large particle size luster pigment). The second coating film is typically a cured product of a second paint composition containing the small particle size mica pigment, the large particle size luster pigment, and a second coating film-forming resin.

[0081] The second coating film may have a film thickness after curing of 3 μm or more and 15 μm or less. The cured film thickness of the second coating film may be 3.5 μm or more. The cured film thickness of the second coating film may be 13 μm or less, or may be 10 μm or less.

[0082] Small particle size mica pigment Small particle size mica pigments are scaly mica pigments with an average particle size of 3 μm to 13 μm. Small particle size mica pigments give multi-layer coatings a soft shine.

[0083] The average particle size of the small-sized mica pigment may be 4 μm or more, or 5 μm or more. The average particle size of the small-sized mica pigment may be 12 μm or less, or 10 μm or less. Multiple types of small-sized mica pigments with different average particle sizes may be used in combination.

[0084] The average thickness of the small particle size mica pigment is, for example, 0.01 μm or more and 0.1 μm or less. The average thickness of the small particle size mica pigment may be 0.04 μm or more. The average thickness of the small particle size mica pigment may be 0.08 μm or less. This makes it easier to achieve appropriate brightness for the multilayer coating film.

[0085] The small particle size mica pigment may or may not be surface coated. The small particle size mica pigment may be, for example, interference mica, white mica, or colored mica.

[0086] The content of the small-particle size mica pigment, i.e., the mass ratio (PWC) of the small-particle size mica pigment to the solid content of the resin contained in the second coating composition, is, for example, 3% by mass or more and 13% by mass or less. The PWC of the small-particle size mica pigment may be 4% by mass or more, or 5% by mass or more. The PWC of the small-particle size mica pigment may be 10% by mass or less, or 8% by mass or less. The solid content of the resin refers to the solid content of all resin components, such as the second coating film-forming resin and curing agent described below.

[0087] <Large particle size luminous pigment> Large particle size bright pigments are bright pigments with an average particle size of 15 μm or more and 30 μm or less. Large particle size bright pigments tend to specularly reflect light, which creates a sparkling effect. Bright pigments are generally scaly.

[0088] The average particle size (average major axis size) of the large particle size bright pigment may be 16 μm or more, or 18 μm or more. The average particle size of the large particle size bright pigment may be 28 μm or less, or 25 μm or less.

[0089] The average thickness of the large particle diameter bright pigment is, for example, 0.01 μm or more and 0.1 μm or less. The average thickness of the large particle diameter bright pigment may be 0.04 μm or more. The average thickness of the large particle diameter bright pigment may be 0.08 μm or less.

[0090] The large particle size bright pigment is not particularly limited as long as its average particle size is 15 μm or more and 30 μm or less. The large particle size bright pigment may be a metallic pigment, a mica pigment, or one of the other bright pigments described above. In particular, the large particle size bright pigment may be a scaly metallic pigment and / or a scaly mica pigment. Multiple large particle size bright pigments with different average particle sizes and / or types may be used in combination.

[0091] The content of the large particle size bright pigment, i.e., the mass ratio (PWC) of the large particle size bright pigment to the solid content of the resin contained in the second coating composition, is, for example, 0.05% by mass or more and 5% by mass or less. The PWC of the large particle size bright pigment may be 0.1% by mass or more, or 0.2% by mass or more. The PWC of the large particle size bright pigment may be 4.5% by mass or less, or 4% by mass or less. When the large particle size bright pigment is a scaly aluminum pigment or other metallic bright pigment, its PWC may be 0.05% by mass or more and 2.5% by mass or less.

[0092] The mass ratio Wm / Wg of the mass Wm of the small particle size mica pigment to the mass Wg of the large particle size bright pigment may be 5 or more and 150 or less. When the amount of the large particle size bright pigment is sufficiently less than the amount of the small particle size mica pigment, glare is suppressed and a soft shine is easily obtained. As a result, the brilliance area Sa 15 , Sa 45 , and Sa 75The average and standard deviation of the above may fall within the above ranges. The mass ratio: Wm / Wg may be 7 or greater, or may be 8 or greater. The mass ratio: Wm / Wg may be 130 or less, or may be 125 or less. When the large particle size bright pigment is a scaly aluminum pigment or other metallic bright pigment, the mass ratio: Wm / Wg may be 20 or greater and 150 or less.

[0093] Other Photochromic Pigments The second coating film may contain a luster pigment other than the small particle size mica pigment and the large particle size luster pigment, such as the above-mentioned small particle size metallic pigment, graphite pigment, glass flake pigment, and scaly mica pigment with an average particle size of more than 15 μm.

[0094] The content of other bright pigments (particularly the above-mentioned small particle diameter metallic pigments) is within a range that does not impair the effects of the coating composition according to the present disclosure. The content of other bright pigments (PWC) may be, for example, less than 3 mass %, 1 mass % or less, or 0 mass %.

[0095] (Second paint composition) The second coating composition may include a small particle size mica pigment, a large particle size effective pigment, and a second film-forming resin.

[0096] The second film-forming resin may be the same as the first film-forming resin. The first film-forming resin and the second film-forming resin may be the same or different. In addition, the second coating composition may contain the same components as the first coating composition.

[0097] (clear coating) The clear coating film protects the first and second coating films and is a cured product of the clear coating composition.

[0098] The clear coating film may have a thickness of 10 μm or more and 80 μm or less after curing. The cured film thickness of the clear coating film may be 20 μm or more. The cured film thickness of the clear coating film may be 60 μm or less.

[0099] The clear coating composition may be solvent-based, water-based, or powder-type. From the viewpoints of transparency or acid etching resistance, the solvent-based clear coating composition may contain an acrylic resin and / or polyester resin as a film-forming resin and an amino resin and / or isocyanate as a curing agent. The solvent-based clear coating composition may also contain an acrylic resin and / or polyester resin having a carboxylic acid and / or an epoxy group.

[0100] The clear coating composition may contain the above-mentioned various pigments to the extent that the transparency and the effects of the coating composition according to the present disclosure are not impaired. The clear coating composition may contain various additives as needed. Examples of additives include ultraviolet absorbers, antioxidants, antifoaming agents, surface conditioners, and pinhole inhibitors.

[0101] Second embodiment A multilayer coating film according to another embodiment of the present disclosure comprises a first coating film, a second coating film, and a clear coating film in this order, the first coating film containing a scaly metallic pigment (the small particle size metallic pigment described above) having an average particle size of 3 μm or more and 13 μm or less, and the second coating film containing a scaly mica pigment (the small particle size mica pigment described above) having an average particle size of 3 μm or more and less than 15 μm, and a luster pigment (the large particle size luster pigment described above) having an average particle size of 15 μm or more and 30 μm or less. In the second coating film, the ratio Wm / Wg of the mass of the scaly mica pigment Wm to the mass Wg of the luster pigment is 5 or more and 150 or less. This allows the luster area Sa described above to be reduced. 15 , Sa 45 , Sa 75 The average can be between 5 and 20, with a standard deviation of less than 3. This multi-layer coating can also create a soft shine with a sparkling sparkle.

[0102] The granularity value of the above multi-layer coating film at a light incident angle of 45° may be 2 or more and 4.5 or less. The lightness L of the above multi-layer coating film at a light incident angle of 45° and a light receiving angle of 15° * 15 can be between 70 and 110.

[0103] The first coating film is typically a cured product of a first coating composition containing a small particle size metallic pigment and a first film-forming resin. The second coating film is typically a cured product of a second coating composition containing a small particle size mica pigment, a large particle size luster pigment, and a second film-forming resin. Details of each component are as described above.

[0104] [Painted items] The coated article according to the present disclosure comprises a substrate and the above-described multi-layer coating film provided on the substrate. Specifically, the coated article comprises the substrate, the above-described first coating film provided on the substrate, the above-described second coating film provided on the first coating film, and the above-described clear coating film provided on the second coating film. The coated article provided with the above-described multi-layer coating film has a soft shine and sparkle when viewed from any angle.

[0105] (subject to be coated) Examples of materials for the substrate include metals, plastics, and foams. Metals (particularly cast metals) are particularly suitable, and metals that can be electrocoated are also suitable. Examples of such metals include iron, copper, aluminum, tin, zinc, and alloys containing these metals.

[0106] The shape of the substrate is not particularly limited, and may be flat or three-dimensional. Specific examples of the substrate include automobile bodies and parts thereof, such as passenger cars, trucks, motorcycles, and buses.

[0107] The metal substrate may have been subjected to a chemical conversion treatment using a phosphate-based chemical conversion treatment agent, a zirconium-based chemical conversion treatment agent, or the like, and may have been subjected to electrodeposition coating. The electrodeposition coating composition may be either a cationic type or an anionic type. A cationic electrodeposition coating composition can form a coating film with excellent corrosion resistance.

[0108] The metal substrate may have an electrodeposition coating and an intermediate coating applied thereon. The intermediate coating is usually applied to improve the adhesion and durability of the multi-layer coating. The intermediate coating composition may contain, for example, a film-forming resin, a curing agent, a color pigment, and an extender pigment. Examples of the film-forming resin and curing agent include those contained in the first film-forming composition.

[0109] [Manufacturing method for coated articles] The method for producing a coated article according to the present disclosure comprises sequentially applying a first coating composition, a second coating composition, and a clear coating composition to an article to be coated, thereby forming a multi-layer coating film.

[0110] In one embodiment, the multi-layer coating film is produced by sequentially applying a first coating composition and a second coating composition to an object to be coated, curing them, and then applying and curing a clear coating composition.

[0111] When the second coating composition is applied, the first coating composition may be cured or uncured. For example, the first coating composition may be applied and then heated to obtain a cured first coating film, after which the second coating composition may be applied. Alternatively, the first coating composition may be applied, and then the second coating composition may be applied on the uncured first coating film. In the latter case, preheating may be performed after application of the first coating composition and before application of the second coating composition.

[0112] In another embodiment, the multilayer coating film is produced by successively applying a first coating composition, a second coating composition, and a clear coating composition wet-on-wet to a substrate, and then curing these coating compositions all at once. Preheating may be performed after applying the first coating composition and before applying the second coating composition, and after applying the second coating composition and before applying the clear coating composition.

[0113] Examples of coating methods include air spray coating, airless spray coating, electrostatic spray coating, multi-stage coating (preferably two-stage coating) using air electrostatic spray coating, and coating that combines air electrostatic spray coating with a rotary atomizer-type electrostatic coater.

[0114] Each coating composition is cured, for example, at a heating temperature of 80°C to 180°C (preferably 100°C to 160°C) for a heating time of 5 to 60 minutes (preferably 10 to 30 minutes). [Example]

[0115] The present invention will be described in more detail with reference to the following examples, but is not limited thereto. In the examples, "parts" and "%" are by weight unless otherwise specified.

[0116] [Production of acrylic resin emulsion] A reaction vessel was charged with 633 parts of deionized water and heated to 80°C while mixing and stirring in a nitrogen stream. Separately, 75.65 parts by weight of styrene (ST), 178.96 parts by weight of methyl methacrylate (MMA), 75.94 parts by weight of n-butyl acrylate (BA), 64.45 parts by weight of 2-ethylhexyl acrylate (2-EHA), and 105.00 parts by weight of hydroxyethyl methacrylate (HEMA) were mixed to prepare a first-stage monomer mixture. Next, this monomer mixture was mixed with 25.00 parts of Aqualon HS-10 (polyoxyethylene alkylpropenylphenyl ether sulfate, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 25.00 parts of Adeka Reasoap NE-20 (α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-hydroxyoxyethylene, manufactured by Asahi Denka Co., Ltd.), and 400 parts of deionized water to prepare a monomer emulsion. Separately, an initiator solution consisting of 1.2 parts ammonium persulfate and 500 parts deionized water was prepared. The monomer emulsion and the initiator solution were added dropwise to the reaction vessel over 1.5 hours. After the addition was completed, the mixture was aged at the same temperature for 1 hour.

[0117] A second-stage monomer mixture was prepared by mixing 53.65 parts by weight of styrene (ST), 178.96 parts by weight of methyl methacrylate (MMA), 75.94 parts by weight of n-butyl acrylate (BA), 64.45 parts by weight of 2-ethylhexyl acrylate (2-EHA), 105.00 parts by weight of hydroxyethyl methacrylate (HEMA), and 22 parts by weight of acrylic acid. This monomer mixture was then mixed with 10 parts of Aqualon HS-10 and 250 parts of deionized water to prepare a monomer emulsion. Separately, an initiator solution consisting of 3.0 parts of ammonium persulfate and 500 parts of deionized water was prepared. The monomer emulsion and initiator solution were added dropwise to the reaction vessel over 1.5 hours. After the addition was completed, the mixture was aged at the same temperature for 2 hours.

[0118] The reaction mixture was then cooled to 40°C and filtered through a 400-mesh filter. Finally, 100 parts of deionized water and 1.6 parts of dimethylaminoethanol were added to the reaction mixture to adjust the pH to 6.5. In this way, an acrylic resin emulsion was obtained with an average particle size of 150 nm, a nonvolatile content of 35%, a solid acid value of 20 mgKOH / g, and a hydroxyl value of 100 mgKOH / g.

[0119] [Production of phosphate group-containing organic compounds] A 1-liter reaction vessel equipped with a stirrer, temperature controller, and condenser was charged with 40 parts of ethoxypropanol. Separately, 20 parts of Hosmer PP (acid phosphooxyhexa(oxypropylene) monomethacrylate, manufactured by Unichemical Co.) were dissolved in 20 parts of ethoxypropanol to prepare a solution. A monomer solution was prepared by mixing 40 parts of this solution with 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 1.7 parts of azobisisobutyronitrile. 121.7 parts of the monomer solution were added dropwise to the reaction vessel at 120°C over 3 hours. Stirring was continued for another hour to obtain a phosphate group-containing organic compound. The phosphate group-containing organic compound thus obtained had an acid value of 105 mgKOH / g, a phosphate value of 55 mgKOH / g, a hydroxyl value of 60 mgKOH / g, a number average molecular weight of 6,000, and a nonvolatile content of 63%.

[0120] The number average molecular weight was measured using a GPC apparatus with the trade name "HLC8220GPC" (manufactured by Tosoh Corporation) and four columns with the trade names "Shodex F-606M" and "Shodex KF-603" (both manufactured by Showa Denko K.K.), under the following conditions: mobile phase: tetrahydrofuran, measurement temperature: 40°C, flow rate: 0.6 cc / min, and detector: RI.

[0121] The acid value and phosphate value of phosphate-containing organic compounds were calculated based on the definition of acid value in JIS K5601 2-1 (the number of milligrams of potassium hydroxide (KOH) required to neutralize the free acid in 1 g of sample (non-volatile matter)). The hydroxyl value was calculated based on the definition of hydroxyl value in JIS K0070 (the number of milligrams of potassium hydroxide required to neutralize the acetic acid bonded to the hydroxyl group when 1 g of sample is acetylated).

[0122] [Example 1] (1) Preparation of first coating composition 182 parts of the above acrylic resin emulsion, 2.2 parts of dimethylaminoethanol, 40 parts of Cymel 327 (mixed alkylated melamine resin, manufactured by Allnex, solids content 90%), 8 parts of small particle size metallic pigment (aluminum, average particle size 7 μm, average thickness 0.1 μm) per 100 parts by mass of resin solids, 5 parts of the above phosphate group-containing organic compound, 0.4 parts of lauryl acid phosphate, 50 parts of butyl cellosolve, 5.5 parts of Noigen EA-207D (amphiphilic compound, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., number average molecular weight 4200, solids content 55%) (3 parts in terms of solids), and 3 parts of linoleic acid (manufactured by Kishida Chemical Co., Ltd.) were uniformly dispersed. Dimethylaminoethanol was added to this dispersion to adjust the pH to 8.1, and the mixture was diluted with deionized water to prepare an aqueous first coating composition with a resin solids concentration of 12%.

[0123] (2) Preparation of second coating composition 182 parts of the above acrylic resin emulsion, 2.2 parts of dimethylaminoethanol, 40 parts of Cymel 327 (mixed alkylated melamine resin, manufactured by Allnex, solid content 90%), 27.86 parts of small particle size mica pigment (average particle size 7 μm, average thickness 0.18 μm) per 100 parts by mass of resin solids, 0.96 parts of large particle size luster pigment (scale-like aluminum pigment, average particle size 20.2 μm, average thickness 0.36 μm) per 100 parts by mass of resin solids, 5 parts of the above phosphate group-containing organic compound, 0.4 parts of lauryl acid phosphate, 50 parts of butyl cellosolve, 5.5 parts of Noigen EA-207D (amphiphilic compound, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., number average molecular weight 4200, solid content 55%) (3 parts in terms of solids), and 3 parts of linoleic acid (manufactured by Kishida Chemical Co., Ltd.) were uniformly dispersed. Dimethylaminoethanol was added to this dispersion to adjust the pH to 8.1, and the dispersion was diluted with deionized water to prepare a water-based second coating composition with a resin solids concentration of 15%.

[0124] (3) Formation of multi-layer coating A zinc phosphate-treated, 0.8 mm thick, 30 cm long, and 40 cm wide dull steel plate 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. The resulting coated plate was then air-sprayed with the 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)) using an Anest Iwata W-101-132G air spray gun to a dry film thickness of 35 μm, and then baked and cured at 140°C for 30 minutes. This resulted in a coated substrate with an electrodeposition coating and an intermediate coating.

[0125] The first coating composition was applied to a substrate by air spray at a room temperature of 23°C and a humidity of 68% to a dry film thickness of 4 μm. After setting for 4 minutes, the coating was preheated at 80°C for 5 minutes to form an uncured first coating film. The second coating composition was then applied to the uncured first coating film by wet-on-wet air spray at a room temperature of 23°C and a humidity of 68% to a dry film thickness of 12 μm. After setting for 4 minutes, the coating was preheated at 80°C for 5 minutes to form an uncured second coating film. The coated plate was allowed to cool to room temperature, and a clear coating, Macflow-O-1810 (a solvent-based clear coating manufactured by Nippon Paint Automotive Coatings Co., Ltd.), was then applied by air spray to a dry film thickness of 35 μm. The coating was then set for 7 minutes to form an uncured clear coating film. The coated plate was then baked in a dryer at 140°C for 30 minutes to obtain a coated article with a multi-layer coating film.

[0126] [Examples 2 to 5, Comparative Examples 1 to 6] Except for changing the amount and type of luster pigment as shown in Table 1, first and second coating compositions were prepared in the same manner as in Example 1, and coated articles were obtained. However, in Comparative Examples 1 to 3, only one layer was formed as the metallic base coating. In Comparative Example 1, no clear coating was formed. The aluminum pigment and mica pigment used as other luster pigments were both scaly.

[0127] [evaluation] The coated articles were subjected to the following evaluations, and the evaluation results are shown in Table 1.

[0128] (1) Bright area Sa Using a spectrophotometer "BYK-mac i" manufactured by BYK, light was irradiated from the clear coating side of the multi-layer coating at angles of incidence of 15°, 45° and 75°, and an image was taken with a CCD camera from the normal direction to measure the luminous area Sa. 15 , Sa 45 , and Sa 75 asked for.

[0129] (2) G-value Using a spectrophotometer "BYK-mac i" manufactured by BYK, diffused light was irradiated from the clear coating side of the multi-layer coating, and an image was taken from the normal direction with a CCD camera to determine the G value (graininess).

[0130] (3) Lightness L * 15 Using a BYK spectrophotometer "BYK-mac i," light is irradiated from the clear coating side of the multi-layer coating at an incident angle of 45°, and the lightness L is calculated from the spectral reflectance of the light received at an angle of 15° to the specular reflected light. * 15 asked for.

[0131] [Table 1]

[0132] The multi-layer coating films of Examples 1 to 5 have a luminous area Sa 15 , Sa 45 , and Sa75 The average of the values ​​was 5 or more and 20 or less, and the standard deviation was 3 or less, and no matter what angle it was viewed from, a sparkle was expressed in a soft shine. Furthermore, the multilayer coating films of Examples 1 to 5 had a G value of 2 or more and 4.5 or less, and while they were dense, the metallic texture was suppressed. In addition, the lightness L * 15 Since the value is 110 or less, it can be seen that the metallic tone is suppressed and a soft shine is obtained.

[0133] The coating film of Comparative Example 1 has only one layer of metallic base coating film blended with small particle diameter metallic pigment. Therefore, the standard deviation of the glitter area Sa is large, and the angle dependency of the design is high. The metallic base coating films of Comparative Examples 2 and 3 have only one layer blended with two types of aluminum pigment, one with small particle diameter and one with large particle diameter. Therefore, both the average value and standard deviation of the glitter area Sa are large, and the texture has a strong metallic tone, and the angle dependency of the design is high. Furthermore, the G value and lightness L * 15 The gloss area Sa was large, and the desired soft shine could not be obtained. Comparative Examples 4 and 5 have two layers of metallic base coating, but the luster pigment contained is only aluminum. Therefore, the standard deviation of the luster area Sa was large, and the angle dependency of the design was high. Furthermore, the G value and lightness L * 15 On the other hand, the two-layer metallic base coating film of Comparative Example 6 uses only mica pigment as the luster pigment. Since it does not contain a luster pigment with a large particle size, the sparkle in the highlights is weakened and the luster area Sa 15 As a result, the standard deviation of the glitter area increased, and the design became angle-dependent. In addition, the G value became excessively small, emphasizing the metallic tone and failing to achieve the desired soft shine.

[0134] The present disclosure includes the following aspects. [1] A multi-layer coating film having a first coating film, a second coating film, and a clear coating film in this order, the first coating film contains a scaly metallic pigment having an average particle diameter of 3 μm or more and 13 μm or less, the second coating film contains a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm, and a luster pigment having an average particle size of 15 μm or more and 30 μm or less, The luminous area Sa of the multi-layer coating film at a light incident angle of 15° 15 , the luminous area Sa at a light incidence angle of 45° 45 , and the luminous area Sa at a light incidence angle of 75° 75 is a multi-layer coating film with an average of 5 to 20 and a standard deviation of 3 or less. [2] The multi-layer coating film according to [1] above, wherein the granularity value of the multi-layer coating film is 2 or more and 4.5 or less. [3] The multilayer coating film of [1] or [2] above, wherein in the second coating film, the ratio Wm / Wg of the mass Wm of the scaly mica pigment to the mass Wg of the bright pigment is 5 or more and 150 or less. [4] The lightness L of the multilayer coating film at a light incident angle of 45° and a light receiving angle of 15° * 15 The multi-layer coating film according to any one of the above [1] to [3], wherein the viscosity coefficient is 70 or more and 110 or less. [5] The object to be coated A coated article having a multilayer coating film according to any one of the above [1] to [4] provided on the substrate. [6] A method for producing a coated article, comprising sequentially applying a first coating composition, a second coating composition, and a clear coating composition to an object to be coated to form a multi-layer coating film, The first coating composition contains a scaly metallic pigment having an average particle size of 3 μm or more and 13 μm or less, The second coating composition contains a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm, and a luster pigment having an average particle size of 15 μm or more and 30 μm or less, The luminous area Sa of the multi-layer coating film at a light incident angle of 15° 15 , the luminous area Sa at a light incidence angle of 45° 45 , and the luminous area Sa at a light incidence angle of 75° 75A method for producing a coated article, wherein the average is 5 or more and 20 or less, and the standard deviation is 3 or less. [7] A multi-layer coating film having a first coating film, a second coating film, and a clear coating film in this order, the first coating film contains a scaly metallic pigment having an average particle diameter of 3 μm or more and 13 μm or less, the second coating film contains a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm, and a luster pigment having an average particle size of 15 μm or more and 30 μm or less, A multi-layer coating film, wherein in the second coating film, the ratio Wm / Wg of the mass Wm of the scaly mica pigment to the mass Wg of the bright pigment is 5 or more and 150 or less. [8] The object to be coated A coated article having the multi-layer coating film of [7] above provided on the substrate. [9] A method for producing a coated article, comprising sequentially applying a first coating composition, a second coating composition, and a clear coating composition to an object to be coated, to form a multi-layer coating film having a first coating film, a second coating film, and a clear coating film, The first coating composition contains a scaly metallic pigment having an average particle size of 3 μm or more and 13 μm or less, The second coating composition contains a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm, and a luster pigment having an average particle size of 15 μm or more and 30 μm or less, A method for producing a coated article, wherein in the second coating film, the ratio Wm / Wg of the mass Wm of the scaly mica pigment to the mass Wg of the bright pigment is 5 or more and 150 or less. [Industrial Applicability]

[0135] The multilayer coating film of the present disclosure has a soft shine and sparkle when viewed from any angle, and can therefore impart new designs to a variety of coated objects.

Claims

1. A multi-layer coating film having a first coating film, a second coating film, and a clear coating film in this order, the first coating film contains a scaly metallic pigment having an average particle diameter of 3 μm or more and 13 μm or less, the second coating film contains a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm, and a luster pigment having an average particle size of 15 μm or more and 30 μm or less, The first coating film is a cured product of a first coating composition, the first coating composition contains the scaly metallic pigment and a first film-forming resin, the mass ratio of the scaly metallic pigment is 3 mass% or more and 13 mass% or less with respect to the solid content of the resin contained in the first coating composition, The second coating film is a cured product of a second coating composition, the second coating composition contains the scaly mica pigment, the bright pigment, and a second coating film-forming resin; The mass ratio of the bright pigment is 0.05 mass% or more and 5 mass% or less with respect to the solid content of the resin contained in the second coating composition, In the second coating film, the ratio Wm / Wg of the mass Wm of the scaly mica pigment to the mass Wg of the bright pigment is 5 or more and 150 or less, the lightness L*15 of the multilayer coating film at a light incident angle of 45° and a light receiving angle of 15° is 110 or less; The luminous area Sa of the multilayer coating film at a light incident angle of 15° １５ , the luminous area Sa at a light incident angle of 45° ４５ , and the luminous area Sa at a light incident angle of 75° ７５ is a multi-layer coating film having an average of 5 to 20 and a standard deviation of 3 or less.

2. The multi-layer coating film according to claim 1, wherein the graininess value of the multi-layer coating film is 2 or more and 4.5 or less.

3. The lightness L of the multilayer coating film at a light incident angle of 45° and a light receiving angle of 15° ＊ １５ The multilayer coating film according to claim 1 or 2, wherein the viscosity is 70 or more and 110 or less.

4. The object to be coated A coated article comprising the multi-layer coating film according to claim 1 or 2 provided on the substrate.

5. A method for producing a coated article, comprising sequentially applying a first coating composition, a second coating composition, and a clear coating composition to an object to be coated, to form a multilayer coating film having a first coating film, a second coating film, and a clear coating film in this order; the first coating composition contains a scaly metallic pigment having an average particle size of 3 μm or more and 13 μm or less and a first coating film-forming resin; the mass ratio of the scaly metallic pigment is 3 mass% or more and 13 mass% or less with respect to the solid content of the resin contained in the first coating composition, the second coating composition comprises a scaly mica pigment having an average particle size of 3 μm or more and less than 15 μm, a luster pigment having an average particle size of 15 μm or more and 30 μm or less, and a second coating film-forming resin; The mass ratio of the bright pigment is 0.05 mass% or more and 5 mass% or less with respect to the solid content of the resin contained in the second coating composition, In the second coating film, the ratio Wm / Wg of the mass Wm of the scaly mica pigment to the mass Wg of the bright pigment is 5 or more and 150 or less, the lightness L*15 of the multilayer coating film at a light incident angle of 45° and a light receiving angle of 15° is 110 or less; The luminous area Sa of the multilayer coating film at a light incident angle of 15° １５ , the luminous area Sa at a light incident angle of 45° ４５ , and the luminous area Sa at a light incident angle of 75° ７５ The method for producing a coated article, wherein the average is 5 or more and 20 or less, and the standard deviation is 3 or less.

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