Luminescent pigment dispersion and method for forming multi-layer coating film

Abstract

A glittering pigment dispersion containing a wetting agent (A), a glittering pigment (B), nanocellulose (C) and water (D), The solid content is 0.1 to 10 parts by mass relative to 100 parts by mass of the total of all components of the glitter pigment dispersion, The nanocellulose (C) is a glittering pigment dispersion comprising at least one selected from the group consisting of phosphate group-containing nanocellulose (C1), carboxyl group-containing nanocellulose (C2), and sulfonic acid group-containing nanocellulose (C3).

Description

[Technical field]

[0001] The present invention relates to a luster pigment dispersion and a method for forming a multilayer coating film. [Background technology]

[0002] The main purpose of applying paint is to protect the material and to impart a beautiful appearance. For industrial products, the appearance, especially the "texture," is important in terms of enhancing the product's appeal. The texture desired by consumers for industrial products is diverse, but in recent years, in the field of automobile exterior panels and automobile parts, there has been a demand for a metallic or pearlescent luster (hereinafter, metallic luster and pearlescent luster will be collectively referred to as "metallic or pearlescent luster").

[0003] Metallic or pearlescent luster is a texture that has no grainy surface like a mirror, and furthermore, appears shiny when the coated plate is viewed near specular reflected light (highlights), but appears dark when viewed in areas away from specular reflected light where the reflected light intensity is relatively low (shades), i.e., there is a large difference in brightness between the highlight and shade areas.

[0004] Techniques for imparting such metallic or pearlescent luster to the surface of industrial products include metal plating and metal vapor deposition (e.g., Patent Document 1). However, if a metallic or pearlescent luster could be imparted by a paint, it would be advantageous from the standpoint of simplicity and cost, and furthermore, if the paint was water-based, it would be even more advantageous from the standpoint of environmental impact.

[0005] Patent Document 2 discloses an aqueous base coating composition that contains a photoluminescent pigment obtained by pulverizing a vapor-deposited metal film to produce metal flakes, and an aqueous cellulose derivative having an acid value of 20 to 150 mg KOH / g (solids content), the aqueous cellulose derivative being the main binder resin, and the photoluminescent pigment content is 20 to 70 mass % in terms of PWC.

[0006] However, the coating film formed by the paint described in Patent Document 2 was insufficient in metallic or pearlescent luster.

[0007] On the other hand, Patent Document 3 discloses a glittering pigment dispersion containing water, a scaly aluminum pigment, and a cellulose-based viscosity modifier, the dispersion containing 0.1 to 10 parts by mass of solids per 100 parts by mass of all components of the glittering pigment dispersion, having a viscosity measured using a B-type viscometer in the range of 400 to 10,000 mPa sec at a rotation speed of 6 revolutions per minute, and containing 30 to 200 parts by mass of the scaly aluminum pigment as solids per 100 parts by mass of the total amount of components other than the scaly aluminum pigment in the total solids.

[0008] The coating film formed using the brilliant pigment dispersion described in Patent Document 3 has excellent metallic luster, but wrinkles may occur at the edge parts, where the film thickness tends to be thicker than in general parts, and sagging may occur at vertical parts. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 63-272544 [Patent Document 2] Japanese Patent Publication No. 2009-155537 [Patent Document 3] International Publication No. 2017 / 175468 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a glittering pigment dispersion which is capable of forming a coating film which has excellent metallic or pearlescent metallic or pearlescent luster, is free from wrinkles at edge portions which tend to be thicker than general portions, and is free from sagging at vertical portions. [Means for solving the problem]

[0011] The present invention includes subject matter described in the following paragraphs.

[0012] Item 1. A glittering pigment dispersion containing a wetting agent (A), a glittering pigment (B), nanocellulose (C) and water (D), The solid content is 0.1 to 10 parts by mass relative to 100 parts by mass of the total of all components of the glitter pigment dispersion, The nanocellulose (C) is a glittering pigment dispersion comprising at least one selected from the group consisting of phosphate group-containing nanocellulose (C1), carboxyl group-containing nanocellulose (C2), and sulfonic acid group-containing nanocellulose (C3).

[0013] Item 2. The bright pigment dispersion according to Item 1, wherein the bright pigment (B) contains an aluminum pigment.

[0014] Item 3. The glittering pigment dispersion according to item 1 or 2, wherein the phosphate group-containing nanocellulose (C1) contains a phosphate group-containing cellulose nanofiber (C11) and / or a phosphate group-containing cellulose nanocrystal (C12).

[0015] Item 4. The cellulose (C) comprises a carboxyl group-containing nanocellulose (C2), and the carboxyl group-containing nanocellulose (C2) comprises a carboxyl group-containing cellulose nanofiber (C21) and / or a carboxyl group-containing cellulose nanocrystal (C22). The brilliant pigment dispersion according to any one of Items 1 to 3.

[0016] Item 5. The cellulose (C) comprises a sulfonic acid group-containing nanocellulose (C3), and the sulfonic acid group-containing nanocellulose (C3) comprises a sulfonic acid group-containing cellulose nanofiber (C31) and / or a sulfonic acid group-containing cellulose nanocrystal (C32). The glittering pigment dispersion according to any one of Items 1 to 4.

[0017] Item 6. The content ratio of the phosphate group-containing nanocellulose (C1) to at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3) is in the range of 1 / 99 to 50 / 50 by mass ratio of the phosphate group-containing nanocellulose (C1) to at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3). The luster pigment dispersion according to any one of items 1 to 5.

[0018] Item 7. Step (1): A step of applying a base coating material (X) onto an object to be coated to form an uncured base coating film; Step (2): A step of applying the glittering pigment dispersion (Y) according to any one of items 1 to 6 onto the base coating film formed in step (1) to form an uncured glittering coating film; Step (3): A step of applying a clear coating (Z) onto the glossy coating film formed in step (2) to form an uncured clear coating film; and Step (4): A method for forming a multilayer coating film, comprising a step of simultaneously heating and curing the uncured base coating film formed in step (1), the uncured glossy coating film formed in step (2), and the uncured clear coating film formed in step (3). Effect of the Invention

[0019] According to the present invention, it is possible to provide a brilliant pigment dispersion which is capable of forming a coating film which has an excellent metallic or pearlescent luster, is free of wrinkles at edge portions which tend to be thicker than general portions, and is free of sagging at vertical portions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] As used herein, the singular forms (a, an, the) are intended to include both the singular and the plural unless otherwise expressly stated in the specification or clearly contradictory in context.

[0021] In this specification, the term "comprise" is a concept that encompasses "consist essentially of" and "consist only of."

[0022] In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In addition, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from an example. Furthermore, in this specification, a numerical value connected with "~" means a numerical range that includes the numerical values ​​before and after "~" as the lower and upper limits.

[0023] In this specification, the term "edge portion" refers to the end portion of the substrate. Examples of edge portions include the edge of the substrate and the corner formed by the intersection of two surfaces of the substrate.

[0024] In this specification, the term "vertical portion" refers to a portion that extends in a substantially vertical direction when the substrate is placed at a fixed position.

[0025] In this specification, the "general part" refers to a part that does not come into contact with other members and occupies the majority of the area of ​​the object to be coated or one of its members, such as the main body, excluding edge parts.

[0026] The brilliant pigment dispersion of the present invention is a brilliant pigment dispersion containing a wetting agent (A), a brilliant pigment (B), nanocellulose (C) and water (D), The solid content is 0.1 to 10 parts by mass relative to 100 parts by mass of the total of all components of the glitter pigment dispersion, The nanocellulose (C) is a glittering pigment dispersion containing phosphate group-containing nanocellulose (C1) and at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3).

[0027] Wetting agent (A) The wetting agent (A) in the brilliant pigment dispersion of the present invention can be any material that is effective in helping to uniformly orient the brilliant pigment dispersion on the substrate when the brilliant pigment dispersion is applied to the substrate, without any particular restrictions.

[0028] Materials having such an action may be called, in addition to wetting agents, wetting agents, leveling agents, surface conditioners, defoamers, surfactants, superwetters, etc., and the above-mentioned wetting agents also include wetting agents, leveling agents, surface conditioners, defoamers, surfactants, and superwetters.

[0029] Examples of the wetting agent (A) include silicone wetting agents, acrylic wetting agents, vinyl wetting agents, fluorine wetting agents, acetylene diol wetting agents, etc. The wetting agents can be used alone or in appropriate combination of two or more.

[0030] As the wetting agent (A), it is preferable to use an acetylene diol-based wetting agent and / or a wetting agent having an ethylene oxide chain, from the viewpoint of obtaining a glittering pigment dispersion and a method for forming a multilayer coating film that are excellent in water resistance and capable of forming a metallic or pearlescent luster, and further have high stability.

[0031] In particular, it is preferable to use, as the wetting agent (A), a wetting agent which is an ethylene oxide adduct of an acetylenic diol.

[0032] Examples of commercially available wetting agents (A) include the Dynol series, Surfynol series, and Tego series manufactured by Evonik Industries, the BYK series manufactured by BYK-Chemie, the Granol series and Polyflow series manufactured by Kyoeisha Chemical Co., Ltd., and the Disparlon series manufactured by Kusumoto Chemical Co., Ltd.

[0033] The content of the wetting agent (A) in the brilliant pigment dispersion of the present invention is preferably 1.5 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 2.5 to 20 parts by mass, in terms of solids content, based on 100 parts by mass of the solids content of the brilliant pigment dispersion, from the viewpoint of forming a coating film that is excellent in metallic or pearlescent metallic or pearlescent luster and that does not cause wrinkles at edge portions which tend to be thicker than general portions, and does not cause sagging at vertical portions.

[0034] Bright pigment (B) Examples of the glittering pigment (B) in the glittering pigment dispersion of the present invention include vapor-deposited metal flake pigments, aluminum flake pigments, and optical interference pigments. One or more of these pigments can be appropriately selected and used depending on the texture required for the resulting coating film. From the viewpoint of obtaining a coating film with excellent metallic luster, vapor-deposited metal flake pigments and aluminum flake pigments are preferred. On the other hand, from the viewpoint of obtaining a coating film with excellent pearlescent luster, optical interference pigments are preferred.

[0035] The vapor-deposited metal flake pigment can be obtained by depositing a metal film on a base substrate, peeling off the base substrate, and then pulverizing the vapor-deposited metal film. Examples of the base substrate include films.

[0036] The metal material of the metal film is not particularly limited, but examples thereof include aluminum, gold, silver, copper, brass, titanium, chromium, nickel, nickel chromium, stainless steel, etc. Among these, aluminum or chromium is particularly preferred from the viewpoints of availability and ease of handling. In this specification, a vapor-deposited metal flake pigment obtained by vapor-depositing aluminum is referred to as a "vapor-deposited aluminum flake pigment," and a vapor-deposited metal flake pigment obtained by vapor-depositing chromium is referred to as a "vapor-deposited chromium flake pigment."

[0037] The vapor-deposited aluminum flake pigment is preferably surface-treated with silica from the viewpoints of storage stability and obtaining a coating film excellent in metallic luster.

[0038] Examples of commercially available products that can be used as the vapor-deposited aluminum flake pigment include the "METALURE" series (product name, manufactured by Ecart), the "Hydroshine WS" series (product name, manufactured by Ecart), the "Decomet" series (product name, manufactured by Schlenk), and the "Metasheen" series (product name, manufactured by BASF).

[0039] Examples of commercially available products that can be used as the above-mentioned vapor-deposited chrome flake pigment include the "Metalure Liquid Black" series (product name, manufactured by Ecart Co., Ltd.).

[0040] The average thickness of the vapor-deposited metal flake pigment is preferably 0.01 to 1.0 μm, and more preferably 0.015 to 0.1 μm.

[0041] The average particle size (D50) of the vapor-deposited metal flake pigment is preferably 1 to 50 μm, and more preferably 5 to 20 μm.

[0042] The average particle size referred to here means the median diameter of the volume-based particle size distribution measured by a laser diffraction scattering method using a Microtrac particle size distribution measuring device MT3300 (product name, manufactured by Nikkiso Co., Ltd.) The thickness is defined as the average value of the measured values ​​of 100 or more particles obtained by observing the cross section of the coating film containing the bright pigment under a microscope and measuring the thickness using image processing software.

[0043] When the average particle size is equal to or less than the upper limit, no grainy feeling occurs in the multi-layer coating film, and when it is equal to or more than the lower limit, a large change in brightness from highlights to shades is maintained.

[0044] Aluminum flake pigments are generally produced by pulverizing and grinding aluminum in a ball mill or an attritor mill in the presence of a grinding medium using a grinding aid. As the grinding aid in the production process of the aluminum flake pigment, higher fatty acids such as oleic acid, stearic acid, isostearic acid, lauric acid, palmitic acid, myristic acid, etc., as well as aliphatic amines, aliphatic amides, and aliphatic alcohols are used. As the grinding medium, an aliphatic hydrocarbon such as mineral spirits is used.

[0045] The above-mentioned aluminum flake pigments can be roughly divided into leafing type and non-leafing type depending on the type of grinding aid. In the glitter pigment dispersion of the present invention, it is preferable to use non-leafing type aluminum pigments from the viewpoint of forming a metallic coating film having excellent water resistance, high gloss in highlights, small particle feeling and fine graininess. As the non-leafing type aluminum pigment, those with no particular surface treatment can be used, but those with the surface coated with resin, those with silica treatment, and those with the surface treated with phosphoric acid, molybdic acid, or a silane coupling agent can also be used. Those with one of the above various surface treatments can be used, but those with multiple types of treatments can also be used.

[0046] The above-mentioned aluminum flake pigment may be a colored aluminum pigment, such as an aluminum flake pigment having a surface coated with a colored pigment and then coated with a resin, or an aluminum flake pigment having a surface coated with a metal oxide such as iron oxide.

[0047] The above aluminum flake pigment is preferably used with an average particle size in the range of 1 to 100 μm from the viewpoint of forming a metallic coating film having high gloss in highlights, small graininess, and fine texture, more preferably with an average particle size in the range of 5 to 50 μm, and particularly preferably with an average particle size in the range of 7 to 30 μm. The thickness is preferably in the range of 0.01 to 1.0 μm, and particularly preferably with an average particle size in the range of 0.02 to 0.5 μm.

[0048] The bright pigment (B) in the bright pigment dispersion of the present invention can be a combination of the vapor-deposited metal flake pigment and the aluminum flake pigment. In this case, the blending ratio of the vapor-deposited metal flake pigment to the aluminum flake pigment is 9 / 1 to 1 / 9, preferably 2 / 8 to 8 / 2, by mass.

[0049] As the optical interference pigment, it is preferable to use an optical interference pigment in which a transparent or semi-transparent substrate is coated with titanium oxide. In this specification, a transparent substrate refers to a substrate that transmits at least 90% of visible light. A semi-transparent substrate refers to a substrate that transmits at least 10% to less than 90% of visible light.

[0050] The optical interference pigment is a glittering pigment in which the surface of a transparent or semitransparent scaly substrate, such as mica, artificial mica, glass, iron oxide, aluminum oxide, or various metal oxides, is coated with a metal oxide having a refractive index different from that of the substrate. Examples of the metal oxide include titanium oxide and iron oxide, and the optical interference pigment can exhibit a variety of different interference colors depending on the thickness of the metal oxide.

[0051] Specific examples of the optical interference pigment include the metal oxide-coated mica pigment, the metal oxide-coated alumina flake pigment, the metal oxide-coated glass flake pigment, and the metal oxide-coated silica flake pigment, which are shown below.

[0052] Metal oxide-coated mica pigments are pigments whose base material is natural or artificial mica, and whose surface is coated with a metal oxide. Natural mica is a scaly base material made by crushing mica ore. Artificial mica is synthesized by heating industrial raw materials such as SiO2, MgO, Al2O3, K2SiF6, and Na2SiF6, melting them at a high temperature of about 1500°C, and then cooling and crystallizing them. Compared to natural mica, it has fewer impurities and is uniform in size and thickness. Specific examples of the base material for artificial mica include fluorphlogopite (KMg3AlSi3O 10 F2), potassium tetrasilicic mica (KMg2.5 AlSiO 10 F2), sodium tetrasilicic mica (NaMg 2.5 AlSiO 10 F2), Na-taeniolite (NaMg2LiSi4O 10 F2), LiNa taeniolite (LiMg2LiSi4O 10 F2) are known.

[0053] Metal oxide-coated alumina flake pigments are pigments in which alumina flakes are used as a substrate, and the substrate surface is coated with a metal oxide. Alumina flakes refer to scaly (thin) aluminum oxide, which is colorless and transparent. The alumina flakes do not necessarily have to be aluminum oxide alone, and may contain oxides of other metals.

[0054] The metal oxide-coated glass flake pigment is a pigment that uses a scaly glass substrate and the surface of the substrate is coated with a metal oxide. The metal oxide-coated glass flake pigment has a smooth substrate surface, which causes strong light reflection.

[0055] The metal oxide-coated silica flake pigment is a pigment in which a scaly silica base material having a smooth surface and uniform thickness is coated with a metal oxide.

[0056] The above-mentioned optical interference pigment may be subjected to a surface treatment in order to improve dispersibility, water resistance, chemical resistance, weather resistance, and the like.

[0057] From the viewpoint of obtaining a coating film excellent in pearlescent luster, it is preferable to use the above-mentioned light interference pigment having an average particle size in the range of 5 to 30 μm, particularly 7 to 20 μm.

[0058] The particle size referred to here means the median size of the volume-based particle size distribution measured by a laser diffraction scattering method using a Microtrac particle size distribution measuring device MT3300 (product name, manufactured by Nikkiso Co., Ltd.).

[0059] From the viewpoint of obtaining a coating film excellent in pearlescent luster, it is preferable to use the above-mentioned light interference pigment having a thickness in the range of 0.05 to 1.0 μm, particularly 0.1 to 0.8 μm.

[0060] The luster pigment (B) in the luster pigment dispersion is preferably one having an average particle size within the range of 1 to 100 μm, more preferably one having an average particle size within the range of 5 to 50 μm, particularly preferably one having an average particle size within the range of 7 to 30 μm, from the viewpoint of forming a coating film having a high gloss in highlights, a small particle feel, and a dense metallic or pearlescent luster. The thickness is preferably one having a thickness within the range of 0.01 to 1.0 μm, particularly preferably one having a thickness within the range of 0.02 to 0.5 μm.

[0061] The content of the brilliant pigment (B) in the brilliant pigment dispersion of the present invention is preferably 5 to 80 parts by mass, more preferably 10 to 75 parts by mass, and even more preferably 15 to 70 parts by mass, based on 100 parts by mass of solids in the brilliant pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster and is free of wrinkles at edge portions which tend to be thicker than general portions, and free of sagging at vertical portions.

[0062] Nanocellulose (C) The nanocellulose (C) includes at least one selected from the group consisting of phosphate group-containing nanocellulose (C1), carboxyl group-containing nanocellulose (C2), and sulfonic acid group-containing nanocellulose (C3).

[0063] Nanocellulose is a term referring to nanostructured cellulose, which is made by finely disintegrating cellulose, the main component of plant cell walls, to the nano level. Specific examples include cellulose nanofibers, cellulose nanocrystals, cellulose nanowhiskers, and bacterial nanocellulose produced by bacteria.

[0064] In this paper, cellulose nanofibers are defined as compounds obtained by subjecting cellulose fibers to mechanical defibration and other processes, and cellulose nanocrystals are defined as compounds obtained by subjecting cellulose fibers to chemical processes such as acid hydrolysis.

[0065] The nanocellulose can be obtained by defibrating a cellulose raw material. Here, the cellulose raw material can be a plant material (e.g., wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp (softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, waste paper, etc.), animal material (e.g., ascidians), algae, microorganisms (e.g., acetic acid bacteria (Acetobacter)), or microbial products, any of which can be used. Preferably, the cellulose raw material is derived from a plant or microorganism, and more preferably, the cellulose raw material is derived from a plant.

[0066] Phosphate-containing nanocellulose (C1) From the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster and does not wrinkle at edge portions, which tend to be thicker than general portions, and does not sag at vertical portions, the phosphate group-containing nanocellulose (C1) preferably contains phosphate group-containing cellulose nanofibers (C11) and / or phosphate group-containing cellulose nanocrystals (C12), and more preferably contains phosphate group-containing cellulose nanofibers (C11).

[0067] The phosphate group-containing cellulose nanofiber (C11) has excellent metallic or pearlescent metallic or pearlescent luster, and from the viewpoint of forming a coating film that does not wrinkle at the edge portion where the film thickness is likely to be thicker than the general portion and does not sag at the vertical portion, the number average fiber diameter is preferably within the range of 2 to 500 nm, more preferably 2 to 250 nm, and even more preferably 2 to 150 nm. The number average fiber length is preferably within the range of 0.1 to 20 μm, more preferably 0.1 to 15 μm, and even more preferably 0.1 to 10 μm. The aspect ratio, which is the numerical value obtained by dividing the number average fiber length by the number average fiber diameter, is preferably within the range of 50 to 10,000, more preferably 50 to 5,000, and even more preferably 50 to 1,000.

[0068] The number average fiber diameter and number average fiber length are measured and calculated from images obtained by, for example, diluting a sample of phosphate group-containing cellulose nanofibers (C11) with water, dispersing the sample, casting the sample on a carbon film-coated grid that has been hydrophilized, and observing the result with a transmission electron microscope (TEM).

[0069] The method for producing the phosphate group-containing cellulose nanofiber (C11) is not particularly limited, and includes, for example, a step of introducing phosphate groups into a cellulose raw material and a defibration process. The phosphate group introduction process is a process of reacting a compound having a phosphate group and / or a salt thereof with the cellulose raw material in the presence of urea and / or a derivative thereof. This introduces phosphate groups into the hydroxyl groups of the cellulose raw material. The defibration process is a process of micronizing the fiber raw material into which the phosphate group has been introduced (hereinafter referred to as "phosphate group-introduced cellulose fiber") to the nano level. The above processing steps are performed in the order of the phosphate group introduction process and the defibration process. The phosphate group introduction process includes a step of introducing phosphate groups into cellulose, and may include, as desired, an alkali treatment process, a step of washing off excess reagents, a heat treatment process of cleaving condensed phosphate groups, and the like.

[0070] The compound having a phosphoric acid group and / or its salt is a compound that contains a phosphorus atom and can form an ester bond with cellulose. The compound that contains a phosphorus atom and can form an ester bond with a hydroxyl group of cellulose is, for example, at least one selected from phosphoric acid, a salt of phosphoric acid, a dehydration condensation product of phosphoric acid, a salt of a dehydration condensation product of phosphoric acid, diphosphorus pentoxide, and phosphorus oxychloride, or a mixture thereof, but is not particularly limited thereto. Any of these may contain water in the form of hydrate water or the like, or may be an anhydride that does not substantially contain water.

[0071] As the salt of the phosphate and the dehydration condensation product of phosphoric acid, a lithium salt, a sodium salt, a potassium salt, an ammonium salt, an organic ammonium salt, an organic phosphonium salt of each of phosphoric acid and the dehydration condensation product of phosphoric acid, as well as a salt with any compound exhibiting basicity can be selected, but there is no particular limitation.

[0072] The degree of neutralization of the phosphate and the salt of the dehydrated condensate of phosphoric acid is not particularly limited.

[0073] Among these, phosphoric acid, a sodium salt of phosphoric acid, a potassium salt of phosphoric acid, or an ammonium salt of phosphoric acid is preferred from the viewpoints of high efficiency of introduction of phosphate groups, easier improvement of defibration efficiency in the defibration step described below, low cost, and ease of industrial application. Phosphoric acid, ammonium dihydrogen phosphate, or sodium dihydrogen phosphate is more preferred.

[0074] Examples of the urea and / or its derivatives include, but are not limited to, urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, benzoleinurea, hydantoin, etc. Among these, urea is preferred because it is low cost, easy to handle, and easily forms hydrogen bonds with fiber raw materials having hydroxyl groups.

[0075] In addition to the above compounds, amides or amines may be included in the reaction system. Examples of amides include formamide, dimethylformamide, acetamide, and dimethylacetamide. Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, and hexamethylenediamine. Among these, triethylamine in particular is known to act as a good reaction catalyst.

[0076] The amount of phosphate groups introduced into the cellulose raw material is not particularly limited, but is preferably 0.10 to 3.65 mmol / g, more preferably 0.20 to 3.00 mmol / g, and even more preferably 0.50 to 2.00 mmol / g per gram (mass) of fine cellulose fiber.

[0077] The content of the phosphate group-containing nanocellulose (C1) in the brilliant pigment dispersion of the present invention is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 7.5 parts by mass, and even more preferably 0.3 to 5 parts by mass, based on 100 parts by mass of solids in the brilliant pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edge portions which tend to be thicker than general portions, and does not develop sagging at vertical portions.

[0078] Carboxyl group-containing nanocellulose (C2) The carboxyl group-containing nanocellulose (C2) preferably contains carboxyl group-containing cellulose nanofibers (C21) and / or carboxyl group-containing cellulose nanocrystals (C22), and more preferably contains carboxyl group-containing cellulose nanofibers (C21), from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster and does not cause wrinkles at edge portions where the film thickness tends to be thicker than in general portions, and does not cause sagging at vertical portions.

[0079] The carboxyl group-containing cellulose nanofiber (C21) preferably has a carboxyl group amount of 0.80 to 1.10 mmol / g, more preferably 0.85 to 1.10 mmol / g, and even more preferably 0.90 to 1.10 mmol / g, relative to the bone dry mass of the cellulose nanofiber.

[0080] Carboxyl group-containing cellulose nanofibers (C21) can be obtained by defibrating oxidized cellulose obtained by introducing carboxyl groups into a cellulose raw material using a known method. One method for introducing carboxyl groups into a cellulose raw material is, for example, to oxidize the cellulose raw material in water using an oxidizing agent in the presence of an N-oxyl compound, a bromide, an iodide, or a mixture thereof. This oxidation reaction selectively oxidizes the primary hydroxyl group at the C6 position of the pyranose ring on the cellulose surface. As a result, a carboxyl group (-COOH) or a carboxylate group (-COO-) can be introduced onto the surface.

[0081] The term "N-oxyl compound" refers to a compound capable of generating a nitroxy radical. Any compound that can promote the desired oxidation reaction can be used as the N-oxyl compound. For example, 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) and its derivatives (e.g., 4-hydroxyTEMPO) can be mentioned.

[0082] The amount of the N-oxyl compound is not particularly limited as long as it is a catalytic amount capable of oxidizing the raw cellulose. The amount is preferably 0.01 mmol to 10 mmol, more preferably 0.01 mmol to 1 mmol, and even more preferably 0.05 mmol to 0.5 mmol, per 1 g of bone dry cellulose. The concentration of the N-oxyl compound is preferably about 0.1 mmol / L to 4 mmol / L in the reaction system.

[0083] Bromides are compounds that contain bromine, including alkali metal bromides that can dissociate and ionize in water, while iodides are compounds that contain iodine, including alkali metal iodides.

[0084] The amount of bromide or iodide can be selected within a range that can promote the oxidation reaction. The total amount of bromide and iodide is preferably 0.1 mmol to 100 mmol, more preferably 0.1 mmol to 10 mmol, and even more preferably 0.5 mmol to 5 mmol, per 1 g of bone-dry cellulose.

[0085] The oxidizing agent may be any known oxidizing agent, such as halogen, hypohalous acid, halous acid, perhalogen acid or their salts, halogen oxides, peroxides, etc. Among these, sodium hypochlorite is preferred, which is inexpensive and has a low environmental impact.

[0086] The amount of the oxidizing agent is preferably 0.5 mmol to 500 mmol, more preferably 0.5 mmol to 50 mmol, and even more preferably 1 mmol to 25 mmol, per 1 g of bone-dry cellulose. Also, for example, the amount of the oxidizing agent is preferably 1 mol to 40 mol per 1 mol of the N-oxyl compound.

[0087] The cellulose oxidation process can proceed efficiently even under relatively mild conditions. Therefore, the reaction temperature is preferably 4°C to 40°C, and may be room temperature of about 15°C to 30°C. As the reaction proceeds, carboxyl groups are generated in the cellulose, and the pH of the reaction solution decreases. In order to efficiently proceed with the oxidation reaction, it is preferable to add an alkaline solution such as an aqueous sodium hydroxide solution during the reaction to maintain the pH of the reaction solution at 8 to 12, preferably about 9 to 12, and more preferably about 10 to 12. The reaction medium is preferably water, for reasons such as ease of handling and the fact that side reactions are unlikely to occur.

[0088] The reaction time in the oxidation reaction can be appropriately set depending on the degree of progress of the oxidation, and is usually 0.5 to 6 hours.

[0089] The oxidation reaction may be carried out in two stages. For example, the carboxylated cellulose obtained by filtering after the completion of the first stage reaction is oxidized again under the same or different reaction conditions, thereby enabling efficient oxidation without reaction inhibition by table salt produced as a by-product in the first stage reaction.

[0090] Another example is a method of oxidizing cellulose raw materials by contacting them with an ozone-containing gas, which oxidizes at least the 2- and 6-hydroxyl groups of the pyranose ring and decomposes the cellulose chain.

[0091] The ozone concentration in an ozone-containing gas is 50 g / m 3 ~250g / m 3 It is preferable that the thickness is 50 g / m 3 ~220g / m 3 The amount of ozone added to the cellulose raw material is preferably 0.1 to 30 parts by mass, and more preferably 5 to 30 parts by mass, based on 100 parts by mass of the solid content of the cellulose raw material.

[0092] The ozone treatment temperature is preferably 0° C. to 50° C., and more preferably 20° C. to 50° C. The ozone treatment time is not particularly limited, but is about 1 minute to 360 minutes, and preferably about 30 minutes to 360 minutes.

[0093] After the ozone treatment, an additional oxidation treatment may be performed using an oxidizing agent. The oxidizing agent used in the additional oxidation treatment is not particularly limited, and examples thereof include chlorine compounds such as chlorine dioxide and sodium chlorite, oxygen, hydrogen peroxide, persulfuric acid, and peracetic acid. For example, the additional oxidation treatment can be performed by dissolving these oxidizing agents in a polar organic solvent such as water or alcohol to prepare an oxidizing agent solution, and immersing the cellulose raw material in the solution.

[0094] The amount of carboxyl groups, which indicates the degree of modification of oxidized cellulose, can be adjusted by controlling reaction conditions such as the amount of oxidizing agent added and reaction time. The amount of carboxyl groups is preferably 0.80 to 1.10 mmol / g, more preferably 0.85 to 1.10 mmol / g, and even more preferably 0.90 to 1.10 mmol / g, based on the bone dry mass of oxidized cellulose. In this specification, when indicating the degree of modification, the amount of carboxyl groups refers to the total amount of carboxyl groups (-COOH) and carboxylate groups (-COO-).

[0095] The amount of carboxyl groups, etc. can be calculated using the following formula from the amount of sodium hydroxide (a) consumed in the neutralization stage of weak acid, where the change in electrical conductivity is gradual, by preparing 60 ml of a 0.5% by mass slurry of oxidized pulp, adding a 0.1 M aqueous hydrochloric acid solution to adjust the pH to 2.5, and then dropping a 0.05 N aqueous sodium hydroxide solution to measure the electrical conductivity until the pH reaches 11.

[0096] Amount of carboxyl groups (mmol / g pulp) = a (ml) x 0.05 / mass of oxidized pulp (g).

[0097] In principle, the degree of modification does not change during the defibration treatment described below, so the degree of modification of oxidized cellulose can be regarded as the degree of modification of the defibrated cellulose nanofibers. (Defibrilization) The device used for defibration is not particularly limited, but examples include devices of high-speed rotation type, colloid mill type, high pressure type, roll mill type, ultrasonic type, etc., and a high-pressure or ultra-high pressure homogenizer is preferable, and a wet high-pressure or ultra-high pressure homogenizer is more preferable. The device is preferably capable of applying a strong shear force to the cellulose raw material or oxidized cellulose (usually a dispersion liquid). The pressure that the device can apply is preferably 50 MPa or more, more preferably 100 MPa or more, and even more preferably 140 MPa or more. The device is preferably a wet high-pressure or ultra-high pressure homogenizer that can apply the above pressure to the cellulose raw material or oxidized cellulose (usually a dispersion liquid) and can apply a strong shear force. This allows efficient defibration. The number of treatments (passes) in the defibration device may be one or two or more, and two or more are preferred.

[0098] In the dispersion process, oxidized cellulose is usually dispersed in a solvent. The solvent is not particularly limited as long as it can disperse oxidized cellulose, but examples include water, organic solvents (e.g., hydrophilic organic solvents such as methanol), and mixtures thereof. Since the cellulose raw material is hydrophilic, it is preferable that the solvent is water.

[0099] The solids concentration of oxidized cellulose in the dispersion is usually 0.1% by mass or more, preferably 0.2% by mass or more, and more preferably 0.3% by mass or more. This ensures that the amount of liquid relative to the amount of cellulose fiber raw material is appropriate and efficient. The upper limit is usually 10% by mass or less, and preferably 6% by mass or less. This allows fluidity to be maintained.

[0100] The order of the defibration treatment and the dispersion treatment is not particularly limited, and either may be performed first, or they may be performed simultaneously, but it is preferable to perform the defibration treatment after the dispersion treatment. Each combination of treatments needs to be performed at least once, and may be repeated two or more times.

[0101] Prior to the defibration or dispersion treatment, a pretreatment may be carried out as necessary. The pretreatment may be carried out using a mixing, stirring, emulsifying or dispersing device such as a high-speed shear mixer.

[0102] The average fiber diameter of the carboxyl group-containing cellulose nanofiber (C21) is preferably 3 nm or more or 500 nm or less, more preferably 3 nm or more or 50 nm or less, and even more preferably 3 nm or more or 20 nm or less. The average fiber length is preferably 60 nm or more or less than 2500 nm, more preferably 75 nm or more or less than 2250 nm, and even more preferably 90 nm or more or less than 900 nm. The average fiber diameter and average fiber length of the carboxyl group-containing cellulose nanofiber (C21) can be measured, for example, by preparing a 0.001 mass% aqueous dispersion of the carboxyl group-containing cellulose nanofiber (C21), spreading this diluted dispersion thinly on a mica sample stage, and drying it by heating at 50 ° C to prepare an observation sample, and measuring the cross-sectional height of the shape image observed with an atomic force microscope (AFM), thereby calculating the number average fiber diameter or number average fiber length.

[0103] The average aspect ratio of the carboxyl group-containing cellulose nanofibers (C21) is preferably 20 or more and less than 50, more preferably within the range of 25-45, and even more preferably within the range of 30-45.

[0104] The content of the carboxyl group-containing nanocellulose (C2) in the brilliant pigment dispersion of the present invention is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 3 to 20 parts by mass, based on 100 parts by mass of solids in the brilliant pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edge portions which tend to be thicker than general portions, and does not develop sagging at vertical portions.

[0105] In addition, the content ratio of the phosphate group-containing nanocellulose (C1) and the carboxyl group-containing nanocellulose (C2) in the brilliant pigment dispersion of the present invention is, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edge portions which tend to be thicker than general portions, and does not develop sagging at vertical portions, the mass ratio ((C1) / (C2)) of the phosphate group-containing nanocellulose (C1) to the carboxyl group-containing nanocellulose (C2) is preferably within the range of 1 / 99 to 50 / 50, more preferably within the range of 3 / 97 to 45 / 55, and even more preferably within the range of 5 / 95 to 40 / 60.

[0106] Sulfonic acid group-containing nanocellulose (C3) The sulfonic acid group-containing nanocellulose (C3) preferably contains sulfonic acid group-containing cellulose nanofiber (C31) and / or sulfonic acid group-containing cellulose nanocrystal (C32), and more preferably contains sulfonic acid group-containing cellulose nanocrystal (C32), from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster and does not cause wrinkles at edge portions where the film thickness tends to be thicker than in general portions, and does not cause sagging at vertical portions.

[0107] The sulfonic acid group-containing cellulose nanocrystal (C32) can be produced by a known method, for example, by a chemical treatment step of chemically treating a fiber raw material containing cellulose to introduce sulfo groups, and a step of hydrolyzing the amorphous portion with concentrated sulfuric acid or the like.

[0108] The number average fiber diameter of the sulfonic acid group-containing cellulose nanocrystal (C32) is preferably within the range of 1 to 50 nm, more preferably within the range of 1 to 30 nm, particularly preferably within the range of 1 to 15 nm, and even particularly preferably within the range of 1 to 5 nm, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, is free of wrinkles at edge portions which tend to be thicker than general portions, and is free of sagging at vertical portions.

[0109] Furthermore, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster and does not develop wrinkles at edge portions that tend to be thicker than general portions and does not develop sagging at vertical portions, the number average fiber length of the sulfonic acid group-containing cellulose nanocrystal (C32) is preferably within the range of 10 to 500 nm, more preferably within the range of 10 to 300 nm, particularly preferably within the range of 20 to 250 nm, and even particularly preferably within the range of 30 to 150 nm.

[0110] The number average fiber diameter and the number average fiber length are measured and calculated from images obtained by, for example, dispersing a sample prepared by diluting sulfonic acid group-containing cellulose nanocrystals (C32) with water, casting the resulting sample on a carbon film-coated grid that has been subjected to a hydrophilization treatment, and observing the resultant sample with a transmission electron microscope (TEM).

[0111] The ratio of the number average fiber length to the number average fiber diameter (number average fiber length / number average fiber diameter) of the sulfonic acid group-containing cellulose nanocrystal (C32) is preferably 3 or more and less than 50, more preferably 5 or more and less than 50, and even more preferably 10 or more and less than 50, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster and is free of wrinkles at edge portions which tend to be thicker than general portions and free of sagging at vertical portions.

[0112] The content of the sulfonic acid group-containing nanocellulose (C3) in the brilliant pigment dispersion of the present invention is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 3 to 20 parts by mass, based on 100 parts by mass of solids in the brilliant pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edge portions which tend to be thicker than general portions, and does not develop sagging at vertical portions.

[0113] In addition, the content ratio of the phosphate group-containing nanocellulose (C1) and the sulfonic acid group-containing nanocellulose (C3) in the brilliant pigment dispersion of the present invention is preferably within the range of 1 / 99 to 50 / 50, more preferably within the range of 3 / 97 to 45 / 55, and even more preferably within the range of 5 / 95 to 40 / 60, in terms of the mass ratio ((C1) / (C3)) of the phosphate group-containing nanocellulose (C1) to the sulfonic acid group-containing nanocellulose (C3), from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edge portions that tend to be thicker than general portions, and does not develop sagging at vertical portions.

[0114] In addition, the content ratio of the phosphate group-containing nanocellulose (C1) to at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3) in the brilliant pigment dispersion of the present invention is preferably within the range of 1 / 99 to 50 / 50, more preferably within the range of 3 / 97 to 45 / 55, and even more preferably within the range of 5 / 95 to 40 / 60, in terms of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not generate wrinkles at the edge portion, which is likely to be thicker than the general portion, and does not cause sagging at the vertical portion. The mass ratio ((C1) / [(C2) and (C3)]) of the phosphate group-containing nanocellulose (C1) to at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3) is preferably within the range of 1 / 99 to 50 / 50, more preferably within the range of 3 / 97 to 45 / 55, and even more preferably within the range of 5 / 95 to 40 / 60.

[0115] The content of nanocellulose (C) in the brilliant pigment dispersion of the present invention is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 3 to 20 parts by mass, based on 100 parts by mass of solids in the brilliant pigment dispersion, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster, does not develop wrinkles at edge portions which tend to be thicker than general portions, and does not develop sagging at vertical portions.

[0116] Luminous pigment dispersion The brilliant pigment dispersion of the present invention is a brilliant pigment dispersion containing a wetting agent (A), a brilliant pigment (B), nanocellulose (C) and water (D), The solid content is 0.1 to 10 parts by mass relative to 100 parts by mass of the total of all components of the glitter pigment dispersion, The nanocellulose (C) is a glittering pigment dispersion containing phosphate group-containing nanocellulose (C1) and at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3).

[0117] The content of water (D) in the brilliant pigment dispersion of the present invention is preferably within the range of 50 to 95 parts by mass, more preferably within the range of 60 to 90 parts by mass, and even more preferably within the range of 70 to 90 parts by mass, relative to 100 parts by mass of all components of the brilliant pigment dispersion, from the viewpoint of forming a coating film that is excellent in metallic or pearlescent metallic or pearlescent luster and that does not cause wrinkles at edge portions which tend to be thicker than general portions, and does not cause sagging at vertical portions.

[0118] Furthermore, from the viewpoint of forming a coating film that has excellent metallic or pearlescent metallic or pearlescent luster and that does not cause wrinkles at edge portions where the film thickness tends to be thicker than in general portions and that does not cause sagging at vertical portions, the solid content is preferably in the range of 0.5 to 8 parts by mass, and more preferably in the range of 1.5 to 6 parts by mass, relative to 100 parts by mass of all components of the brilliant pigment dispersion.

[0119] The bright pigment dispersion of the present invention may also contain a resin water dispersion from the viewpoint of the water resistance of the resulting coating film.

[0120] resin water dispersion The resin water dispersion is a dispersion in which a resin is dispersed in an aqueous solvent, and may contain, for example, at least one selected from the group consisting of a urethane resin water dispersion, an acrylic resin water dispersion, a polyester resin water dispersion, an olefin resin water dispersion, and a composite of these resins. The water dispersion may be modified.

[0121] Of these, from the viewpoint of the water resistance of the resulting coating film, preferred are urethane resin water dispersions and acrylic resin water dispersions, more preferred are hydroxyl group-containing urethane resin water dispersions and hydroxyl group-containing acrylic resin water dispersions, and especially preferred are hydroxyl group-containing acrylic resin water dispersions.

[0122] The hydroxyl-containing acrylic resin aqueous dispersion is particularly preferably of the core-shell type.

[0123] When the brilliant pigment dispersion of the present invention contains a resin water dispersion, the content thereof is preferably within the range of 1 to 60 parts by mass, and more preferably within the range of 5 to 40 parts by mass, based on 100 parts by mass of the solid content in the brilliant pigment dispersion.

[0124] Other Ingredients If necessary, the glittering pigment dispersion may further contain an organic solvent, a pigment other than the glittering pigment (B), a viscosity adjuster other than the nanocellulose (C), a binder resin other than the resin water dispersion, a crosslinkable component, a pigment dispersant, an anti-settling agent, an ultraviolet absorber, a light stabilizer, and the like.

[0125] Examples of pigments other than the above-mentioned luster pigment (B) include coloring pigments and extender pigments.

[0126] Examples of the color pigment include titanium oxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, threne pigments, perylene pigments, dioxazine pigments, and diketopyrrolopyrrole pigments. Of these, carbon black is preferably used.

[0127] When the brilliant pigment dispersion of the present invention contains a color pigment, the content thereof is preferably within the range of 0.1 to 10 parts by mass, and more preferably within the range of 0.5 to 5 parts by mass, based on 100 parts by mass of the solid content in the brilliant pigment dispersion.

[0128] Examples of the extender pigment include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and alumina white.

[0129] When the brilliant pigment dispersion of the present invention contains an extender pigment, the content thereof is preferably within the range of 0.1 to 10 parts by mass, and more preferably within the range of 0.5 to 5 parts by mass, based on 100 parts by mass of the solid content in the brilliant pigment dispersion.

[0130] As viscosity modifiers other than the nanocellulose (C), polyacrylic acid-based viscosity modifiers, polyamide-based viscosity modifiers, mineral-based viscosity modifiers, cellulose-based viscosity modifiers (excluding nanocellulose), polysaccharide-based viscosity modifiers, etc. can be used. Among them, it is preferable to use a polyacrylic acid-based viscosity modifier from the viewpoint of forming a coating film that does not wrinkle at the edge parts, which tend to be thicker than the general parts, and does not sag at the vertical parts.

[0131] Examples of the polyacrylic acid-based viscosity modifier include sodium polyacrylate and polyacrylic acid-(meth)acrylic acid ester copolymers.

[0132] Examples of commercially available polyacrylic acid viscosity modifiers include "PRIMAL ASE-60", "PRIMAL TT615", and "PRIMAL RM5" (all trade names) manufactured by The Dow Chemical Company, and "SN Thickener 613", "SN Thickener 618", "SN Thickener 630", "SN Thickener 634", and "SN Thickener 636" (all trade names) manufactured by San Nopco Ltd. The solid content acid value of the polyacrylic acid viscosity modifier is preferably within the range of 30 to 300 mgKOH / g, more preferably 80 to 280 mgKOH / g.

[0133] Examples of the polyamide-based viscosity modifier include polyamide amine salts and fatty acid polyamides.

[0134] Examples of mineral viscosity modifiers include swellable layered silicates having a 2:1 crystal structure.Specific examples include smectite clay minerals such as natural or synthetic montmorillonite, saponite, hectorite, stevensite, beidellite, nontronite, bentonite, and laponite, swellable mica clay minerals such as Na-type tetrasilicic fluorine mica, Li-type tetrasilicic fluorine mica, Na-salt type fluorine taeniolite, and Li-type fluorine taeniolite, and vermiculite, or substitutes or derivatives thereof, or mixtures thereof.

[0135] Examples of cellulose-based viscosity modifiers (excluding nanocellulose) include carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose, and hydroxypropylmethylcellulose.

[0136] Examples of polysaccharide viscosity modifiers include guar gum, xanthan gum, and locust bean gum.

[0137] When the brilliant pigment dispersion of the present invention contains a viscosity adjuster other than the nanocellulose (C), the content thereof is preferably within the range of 1 to 30 parts by mass, and more preferably within the range of 3 to 20 parts by mass, based on 100 parts by mass of the solid content in the brilliant pigment dispersion.

[0138] The crosslinkable component is a component for crosslinking and curing the glitter pigment dispersion by heating when the dispersion contains the resin water dispersion, and when the dispersion does not contain the resin water dispersion, the crosslinkable component may be a component for self-crosslinking, or a component for crosslinking and curing with a part of the colored paint forming the colored coating film described below or a part of the clear paint forming the clear coating film described below. Examples of the crosslinkable component include amino resins, urea resins, polyisocyanate compounds, blocked polyisocyanate compounds, epoxy group-containing compounds, carboxyl group-containing compounds, carbodiimide group-containing compounds, hydrazide group-containing compounds, semicarbazide group-containing compounds, and silane coupling agents. Among these, amino resins, polyisocyanate compounds, and blocked polyisocyanate compounds that can react with hydroxyl groups, and carbodiimide group-containing compounds that can react with carboxyl groups are preferred. As for the polyisocyanate compounds and blocked polyisocyanate compounds, those described in the section on clear coatings described below can be used. The above crosslinkable components can be used alone or in combination of two or more kinds.

[0139] When the brilliant pigment dispersion of the present invention contains the above-mentioned crosslinkable component, the content thereof is preferably within the range of 0.5 to 100 parts by mass, more preferably within the range of 1 to 95 parts by mass, and even more preferably within the range of 2 to 90 parts by mass, in terms of the water resistance of the resulting coating film, based on 100 parts by mass of the content of the brilliant pigment (B) in the brilliant pigment dispersion of the present invention.

[0140] When the brilliant pigment dispersion of the present invention contains the above-mentioned binder resin and / or crosslinkable component, from the viewpoint of the metallic or pearlescent luster and water-resistant adhesion of the obtained coating film, the total content of the binder resin and the crosslinkable component is preferably within the range of 1 to 200 parts by mass, more preferably within the range of 2 to 150 parts by mass, and even more preferably within the range of 3 to 100 parts by mass, based on 100 parts by mass of the solid content of the brilliant pigment (B) in the brilliant pigment dispersion.

[0141] viscosity The brilliant pigment dispersion of the present invention has an excellent metallic or pearlescent metallic or pearlescent luster, and from the viewpoint of forming a coating film that does not develop wrinkles at edge portions (where the film thickness tends to be thicker than in general portions) and does not develop sagging in vertical portions, the viscosity at a rotation speed of 6 revolutions per minute (6 rpm) is preferably within the range of 400 to 10,000 mPa sec, more preferably within the range of 500 to 8,000 mPa sec, and even more preferably within the range of 600 to 6,000 mPa sec.

[0142] The viscosity is defined as the viscosity 1 minute after the start of measurement under certain conditions. Specifically, the prepared glitter pigment dispersion is placed in a specified container, and a rotary stirrer is used to set the rotation speed to 1000 rpm and stir and mix until homogenous. Then, measurement is started at a temperature of 20°C with a B-type viscometer at 6 rpm, and the viscosity is defined as the viscosity 1 minute after the start (also referred to as "B6 value" in this specification). The viscometer used here is "LVDV-I" (trade name, BROOKFIELD, B-type viscometer). The rotation speed of 6 rpm is a general condition for controlling the viscosity of a pseudoplastic liquid.

[0143] Multi-layer coating method The method for forming a multilayer coating film of the present invention comprises the steps of: Step (1): A step of applying a base coating (X) onto an object to be coated to form an uncured base coating film; Step (2): A step of applying the glittering pigment dispersion of the present invention onto the base coating film formed in step (1) to form an uncured glittering coating film; Step (3): A step of applying an uncured clear coating (Z) onto the glossy coating film formed in step (2) to form a clear coating film; and Step (4): A method for forming a multilayer coating film, comprising a step of simultaneously heating and curing the uncured base coating film formed in step (1), the uncured glossy coating film formed in step (2), and the uncured clear coating film formed in step (3).

[0144] Object to be coated The multilayer coating film of the present invention is formed on the substrate shown below.

[0145] Examples of the substrate include metals such as iron, zinc, and aluminum, alloys containing these metals, and molded products made of these metals, as well as molded products and films made of glass, plastics, foams, and the like. These materials can be degreased or surface-treated as appropriate to produce the substrate. Examples of the surface treatment include phosphate treatment, chromate treatment, and complex oxide treatment. Furthermore, if the substrate is made of metal, it is preferable that a primer coating film is formed on the surface-treated metal material using a cationic electrodeposition paint or the like. Furthermore, if the substrate is made of plastic, it is preferable that a primer coating film is formed on the degreased plastic material using a primer paint.

[0146] Base paint (X) As the base coating material (X), specifically, a known thermosetting coating material containing a base resin, a crosslinking agent, a pigment, and a solvent such as an organic solvent and / or water as main components can be used.

[0147] The base resin used in the base coating material (X) may be a thermosetting resin, a room temperature curing resin, etc., but from the viewpoints of water resistance, chemical resistance, weather resistance, etc., a thermosetting resin is preferable.

[0148] As the base resin, a resin having good weather resistance and transparency is suitable, and specific examples thereof include acrylic resin, polyester resin, epoxy resin, and urethane resin.

[0149] Examples of the acrylic resin include resins obtained by copolymerizing α,β-ethylenically unsaturated carboxylic acids, (meth)acrylic acid esters having functional groups such as hydroxyl groups, amide groups, methylol groups, and epoxy groups, and other (meth)acrylic acid esters, styrene, and the like.

[0150] Examples of the polyester resin include polyester resins obtained by a condensation reaction between a polyhydric alcohol such as ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, trimethylolpropane, or pentaerythritol and a polycarboxylic acid component such as adipic acid, isophthalic acid, terephthalic acid, phthalic anhydride, hexahydrophthalic anhydride, or trimellitic anhydride.

[0151] An example of the epoxy resin is a so-called bisphenol A type epoxy resin, which is produced by a condensation reaction between bisphenol A and epichlorohydrin.

[0152] Examples of urethane resins include compounds obtained by an addition reaction between a diisocyanate compound and a polyhydric alcohol, and those obtained by reacting the above-mentioned acrylic resins, polyester resins or epoxy resins with a diisocyanate compound to increase the molecular weight.

[0153] The base coating material (X) may be either an aqueous coating material or a solvent-based coating material, but from the viewpoint of reducing VOC of the coating material, it is preferable that the base coating material is an aqueous coating material. When the base coating material (X) is an aqueous coating material, the base resin is a resin containing a sufficient amount of hydrophilic groups, such as carboxyl groups, hydroxyl groups, methylol groups, amino groups, sulfonic acid groups, polyoxyethylene bonds, etc., most commonly carboxyl groups, to make the resin water-soluble or water-dispersible, and the hydrophilic groups are neutralized to form an alkali salt, thereby making the base resin water-soluble or water-dispersible. The amount of hydrophilic groups, such as carboxyl groups, is not particularly limited and can be selected arbitrarily depending on the degree of water-solubilization or water-dispersion, but generally, it can be about 10 mgKOH / g or more, preferably within the range of 30 to 200 mgKOH / g, based on the acid value. Examples of alkaline substances used for neutralization include sodium hydroxide and amine compounds.

[0154] The resin can also be dispersed in water by emulsion polymerization of the polymerizable component in the presence of a surfactant or a water-soluble resin. The resin can also be dispersed in water in the presence of an emulsifier, for example. In this case, the base resin may not contain any hydrophilic groups at all, or may contain less hydrophilic groups than the water-soluble resin.

[0155] The crosslinking agent is used to crosslink and harden the base resin by heating, and any of the crosslinking components exemplified in the description of the bright pigment dispersion of the present invention can be used.

[0156] The ratio of each of the above components in the base coating material (X) can be selected as necessary. From the viewpoints of water resistance, finish, etc., it is generally preferable that the base resin and crosslinking agent are within the ranges of 60 to 90 mass %, particularly 70 to 85 mass %, and the latter are within the ranges of 10 to 40 mass %, particularly 15 to 30 mass %, based on the total mass of both components.

[0157] The pigment provides the base coating film formed from the base paint (X) with brilliance, color, and base hiding properties, etc. The type and amount of the pigment can be appropriately adjusted depending on the hue or brightness required for the multilayer coating film.

[0158] Examples of the pigment include luster pigments, color pigments, and extender pigments.

[0159] The cured film thickness of the base coating film obtained from the base paint (X) is preferably within the range of 3 μm to 50 μm, more preferably within the range of 5 to 45 μm, and even more preferably within the range of 7 to 40 μm, from the viewpoints of the hiding power of the base and the metallic or pearlescent luster of the multilayer coating film.

[0160] The base coating material (X) can be applied according to a conventional method. When the base coating material (X) is a water-based coating material, for example, deionized water and, if necessary, additives such as a thickener and an antifoaming agent are added to the base coating material (X) to adjust the solid content to about 10 to 70% by mass and the viscosity to 500 to 6000 cps / 6 rpm (B-type viscometer), and then the base coating material can be applied to the surface of the substrate by spray coating, rotary atomization coating, etc. In particular, from the viewpoint of forming a multi-layer coating film that does not cause wrinkles at the edge part, which is likely to be thicker than the general part, it is preferable to set the solid content within the range of 10 to 20% by mass. When applying, electrostatic application can also be performed as necessary.

[0161] From the viewpoint of color stability, the base paint (X) has a black-and-white hiding film thickness of preferably 80 μm or less, more preferably 10 to 60 μm, and even more preferably 15 to 50 μm. In this specification, the term "black-and-white hiding film thickness" refers to a value measured by attaching a black-and-white checkered pattern hiding rate test paper specified in 4.1.2 of JIS K5600-4-1 to a steel plate, applying the paint at an angle so that the film thickness changes continuously, drying or curing the paint, and visually observing the coated surface under diffuse daylight, and measuring the minimum film thickness at which the black-and-white boundary of the checkered pattern of the hiding rate test paper becomes invisible using an electromagnetic film thickness meter.

[0162] When the photoluminescent pigment dispersion of the present invention is applied onto an uncured base coating film of the base coating material (X), after application of the base coating material (X), the coating can be left at room temperature for 15 to 30 minutes, or heated at a temperature of 50 to 100°C for 30 seconds to 10 minutes, and then the photoluminescent pigment dispersion of the present invention can be applied.

[0163] Coating with photoluminescent pigment dispersion (Y) The bright pigment dispersion (Y) of the present invention can be applied by electrostatic coating, air spray, airless spray, etc. These coating methods may be electrostatically applied as necessary. In the multi-layer coating film forming method of the present invention, rotary atomization type electrostatic coating is particularly preferred.

[0164] The dry thickness of the glittering coating film is preferably 0.025 to 3 μm, and more preferably 0.15 to 2.5 μm.

[0165] After applying the above-mentioned glittering pigment dispersion (Y), the coating may be left at room temperature for 15 to 30 minutes, or heated at a temperature of 50 to 100° C. for 30 seconds to 10 minutes, and then the clear coating (Z) may be applied.

[0166] Clear paint (Z) The clear coating material (Z) may be any known thermosetting clear coating material composition. Examples of the thermosetting clear coating material composition include organic solvent-based thermosetting coating materials containing a base resin having a crosslinkable functional group and a curing agent, water-based thermosetting coating materials, and powder thermosetting coating materials.

[0167] Examples of the crosslinkable functional group of the base resin include a carboxyl group, a hydroxyl group, an epoxy group, a silanol group, etc. Examples of the type of base resin include an acrylic resin, a polyester resin, an alkyd resin, a urethane resin, an epoxy resin, a fluororesin, etc. Examples of the curing agent include a polyisocyanate compound, a blocked polyisocyanate compound, a melamine resin, a urea resin, a carboxyl group-containing compound, a carboxyl group-containing resin, an epoxy group-containing resin, an epoxy group-containing compound, etc.

[0168] Preferred combinations of base resin / curing agent for the clear coating (Z) include carboxyl group-containing resin / epoxy group-containing resin, hydroxyl group-containing resin / polyisocyanate compound, hydroxyl group-containing resin / blocked polyisocyanate compound, and hydroxyl group-containing resin / melamine resin.

[0169] The clear coating material (Z) may be a one-liquid coating material, or may be a multi-liquid coating material such as a two-liquid coating material.

[0170] Of these, the clear coating material (Z) is preferably a two-component clear coating material containing the following hydroxyl group-containing resin and polyisocyanate compound, from the viewpoint of adhesion of the resulting coating film.

[0171] Hydroxyl-containing resin As the hydroxyl group-containing resin, any conventionally known resin containing a hydroxyl group can be used without any restrictions. Examples of the hydroxyl group-containing resin include hydroxyl group-containing acrylic resin, hydroxyl group-containing polyester resin, hydroxyl group-containing polyether resin, and hydroxyl group-containing polyurethane resin. Preferred examples include hydroxyl group-containing acrylic resin and hydroxyl group-containing polyester resin, and particularly preferred examples include hydroxyl group-containing acrylic resin.

[0172] The hydroxyl value of the hydroxyl-containing acrylic resin is preferably within the range of 80 to 200 mgKOH / g, more preferably within the range of 100 to 180 mgKOH / g, from the viewpoint of the scratch resistance and water resistance of the coating film.

[0173] The weight average molecular weight of the hydroxyl-containing acrylic resin is preferably within the range of 2,500 to 40,000, and more preferably within the range of 5,000 to 30,000, from the viewpoint of the acid resistance and smoothness of the coating film.

[0174] In this specification, the weight average molecular weight is a value calculated from a chromatogram measured by a gel permeation chromatograph based on the molecular weight of standard polystyrene. The gel permeation chromatograph used was "HLC8120GPC" (manufactured by Tosoh Corporation). Four columns, "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL", and "TSKgel G-2000HXL" (all of which are product names manufactured by Tosoh Corporation), were used, and the measurement was performed under the following conditions: mobile phase: tetrahydrofuran, measurement temperature: 40°C, flow rate: 1 cc / min, and detector: RI.

[0175] The glass transition temperature of the hydroxyl-containing acrylic resin is preferably −40° C. to 20° C., and particularly preferably within the range of −30° C. to 10° C. If the glass transition temperature is −40° C. or higher, the coating film has sufficient hardness, and if it is 20° C. or lower, the coating film can maintain its surface smoothness.

[0176] Polyisocyanate Compounds The polyisocyanate compound is a compound having at least two isocyanate groups in one molecule, and examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of the polyisocyanates.

[0177] Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate (common name: lysine diisocyanate), isocyanate); and aliphatic triisocyanates such as 2-isocyanatoethyl 2,6-diisocyanatohexanoate, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, and 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyloctane.

[0178] Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: isophorone diisocyanate), 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, alicyclic diisocyanates such as 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or mixtures thereof, methylene bis(4,1-cyclohexanediyl) diisocyanate (common name: hydrogenated MDI), and norbornane diisocyanate; 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2-(3-isocyanatopropyl)-2-isocyanatopropyl ,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 2-(3-isocyanatopropyl)-2,6-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 3-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 6-(2-isocyanatoethyl)-bicyclo(2.2.1)heptane alicyclic triisocyanates such as 2-isocyanatoethyl)-2-isocyanatomethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, 5-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane, and 6-(2-isocyanatoethyl)-2-isocyanatomethyl-2-(3-isocyanatopropyl)-bicyclo(2.2.1)heptane.

[0179] Examples of the aromatic aliphatic polyisocyanate include aromatic aliphatic diisocyanates such as methylenebis(4,1-phenylene)diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene (common name: tetramethylxylylene diisocyanate) or a mixture thereof; and aromatic aliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene.

[0180] Examples of the aromatic polyisocyanate include aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate (common name: 2,4-TDI) or 2,6-tolylene diisocyanate (common name: 2,6-TDI) or a mixture thereof, 4,4'-toluidine diisocyanate, and 4,4'-diphenyl ether diisocyanate; aromatic triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene; and aromatic tetraisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate.

[0181] Examples of the polyisocyanate derivatives include the above-mentioned polyisocyanate dimers, trimers, biurets, allophanates, uretdione, uretoimine, isocyanurates, oxadiazinetriones, polymethylene polyphenyl polyisocyanates (crude MDI, polymeric MDI), crude TDI, etc. The polyisocyanate derivatives may be used alone or in combination of two or more.

[0182] The above polyisocyanates and derivatives thereof may be used alone or in combination of two or more kinds.

[0183] Among aliphatic diisocyanates, hexamethylene diisocyanate compounds can be preferably used, and among alicyclic diisocyanates, 4,4'-methylenebis(cyclohexylisocyanate) can be preferably used. Among these, in particular, from the viewpoints of adhesion, compatibility, etc., derivatives of hexamethylene diisocyanate are most suitable.

[0184] The polyisocyanate compound may be a prepolymer obtained by reacting the polyisocyanate or its derivative with a compound having an active hydrogen group, such as a hydroxyl group or an amino group, which is reactive with the polyisocyanate under an isocyanate group excess condition. Examples of the compound reactive with the polyisocyanate include polyhydric alcohols, low molecular weight polyester resins, amines, water, etc.

[0185] As the polyisocyanate compound, blocked polyisocyanate compounds, which are compounds in which the isocyanate groups in the above polyisocyanates and their derivatives are blocked with a blocking agent, can also be used.

[0186] Examples of the blocking agent include phenol-based agents such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; lactam-based agents such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propiolactam; aliphatic alcohol-based agents such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, and lauryl alcohol; ether-based agents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate ... Alcohol-based compounds such as ethyloxyethyl methacrylate; oxime-based compounds such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime; active methylene-based compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone; butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, and methylthiophenol. mercaptans such as ethylthiophenol; acid amides such as acetanilide, acetaniside, acetotoluide, acrylamide, methacrylamide, acetic amide, stearic acid amide, benzamide; imides such as succinimide, phthalic acid imide, maleic acid imide; amines such as diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, dibutylamine, butylphenylamine; imidazoles such as imidazole and 2-ethylimidazole;Examples of the azole compounds include urea compounds such as urea, thiourea, ethyleneurea, ethylenethiourea, and diphenylurea; carbamic acid ester compounds such as N-phenyl phenylcarbamate; imine compounds such as ethyleneimine and propyleneimine; sulfite compounds such as sodium bisulfite and potassium bisulfite; and azole compounds. Examples of the azole compounds include pyrazole compounds or pyrazole derivatives such as pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole; imidazole compounds or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole, and 2-phenylimidazole; and imidazoline derivatives such as 2-methylimidazoline and 2-phenylimidazoline.

[0187] When blocking (reacting with a blocking agent), a solvent may be added as necessary. The solvent used in the blocking reaction is preferably one that is not reactive with isocyanate groups, and examples of the solvent include ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, and N-methyl-2-pyrrolidone (NMP).

[0188] The polyisocyanate compounds can be used alone or in combination of two or more kinds.

[0189] In the present invention, from the viewpoint of the curability and scratch resistance of the coating film, the equivalent ratio (OH / NCO) of the hydroxyl group of the hydroxyl-containing resin to the isocyanate group of the polyisocyanate compound is preferably within the range of 0.5 to 2.0, more preferably 0.8 to 1.5.

[0190] When a two-component clear coating containing a hydroxyl-containing resin and a polyisocyanate compound is used as the clear coating (Z), the hydroxyl-containing resin and the polyisocyanate compound are preferably in a separated form from the standpoint of storage stability, and the two are preferably mixed together just before use.

[0191] As the clear coating material (Z), a one-component coating material may be used. Combinations of base resin and curing agent in one-component coating materials include carboxyl group-containing resin / epoxy group-containing resin, hydroxyl group-containing resin / blocked polyisocyanate compound, and hydroxyl group-containing resin / melamine resin.

[0192] The clear coating material (Z) may further contain, as necessary, additives such as solvents such as water or organic solvents, curing catalysts, antifoaming agents, and ultraviolet absorbing agents.

[0193] The above clear coating (Z) can be appropriately blended with a coloring pigment within a range that does not impair transparency. As the coloring pigment, one or more of the conventionally known pigments for inks and coatings can be blended in combination. The amount of the pigment to be added can be appropriately determined, but is 30 parts by mass or less, preferably 0.01 to 10 parts by mass, relative to 100 parts by mass of the vehicle-forming resin composition in the clear coating.

[0194] The form of the clear coating material (Z) is not particularly limited, but it is usually used as an organic solvent-based coating material composition. In this case, the organic solvent used can be various organic solvents for coating materials, such as aromatic or aliphatic hydrocarbon solvents; ester solvents; ketone solvents; ether solvents, etc. The organic solvent used can be the one used when preparing the hydroxyl group-containing resin, etc., or can be added appropriately.

[0195] The solid content concentration of the clear coating material (Z) is preferably about 30 to 70 mass %, and more preferably within the range of about 40 to 60 mass %.

[0196] The above-mentioned clear coating material (Z) is applied on the above-mentioned glittering coating film. The application of the clear coating material (Z) is not particularly limited and can be performed in the same manner as the above-mentioned colored coating material (X), for example, it can be performed by a coating method such as air spray, airless spray, rotary atomization coating, curtain coat coating, etc. These coating methods may be electrostatically applied as necessary. Among these, rotary atomization coating by electrostatic application is preferred. The application amount of the clear coating material (Z) is preferably an amount that is usually about 10 to 50 μm in terms of the cured film thickness.

[0197] In addition, when applying the clear coating material (Z), it is preferable to appropriately adjust the viscosity of the clear coating material (Z) using a solvent such as an organic solvent so that the viscosity is within a viscosity range suitable for the coating method, for example, in rotary atomization coating using electrostatic application, the viscosity is within a range of about 15 to 60 seconds when measured at 20°C using a Ford Cup No. 4 viscometer.

[0198] The method for forming a multilayer coating film of the present invention includes a step of simultaneously heating and curing the base coating film, the glittering coating film and the clear coating film.

[0199] The heating can be performed by known means, for example, a drying oven such as a hot air oven, an electric oven, or an infrared induction heating oven. The heating temperature is suitably within the range of 70 to 150° C., preferably 80 to 140° C. The heating time is not particularly limited, but is preferably within the range of 10 to 40 minutes, more preferably 20 to 30 minutes. EXAMPLES

[0200] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples. In addition, "parts" and "%" are all based on mass.

[0201] [1] Preparation of the object to be coated A degreased and zinc phosphate-treated steel plate (JIS G3141, size 400 mm x 300 mm x 0.8 mm) was electrocoated with cationic electrodeposition paint "Elecron GT-10" (product name: manufactured by Kansai Paint Co., Ltd., epoxy resin polyamine cationic resin using a blocked polyisocyanate compound as a curing agent) to a film thickness of 20 μm based on the cured coating, and heated at 170°C for 20 minutes to crosslink and cure, forming an electrodeposition coating film.

[0202] On the obtained electrodeposition coating surface of the steel plate, "TP-90 No. 8101 Gray" (product name, manufactured by Kansai Paint Co., Ltd., hydroxyl group / melamine and blocked isocyanate group curing type one-component organic solvent-based paint) was applied using an air spray to a film thickness of 40 μm based on the cured coating film, and after leaving it for 7 minutes, it was heated at 140°C for 30 minutes to form an intermediate coating film, thereby preparing a coated article.

[0203] [2] Preparation of paint Manufacture of acrylic resin water dispersion (R-1) Manufacturing Example 1 In a reaction vessel equipped with a thermometer, a thermostat, a stirring device, a reflux condenser and a dropping device, 70.7 parts of deionized water and 0.52 parts of "Aqualon KH-10" (trade name, Daiichi Kogyo Seiyaku Co., Ltd., emulsifier, active ingredient 97%) were charged, stirred and mixed in a nitrogen stream, and heated to 80 ° C. Then, 1% of the total amount of the monomer emulsion described below and 5 parts of a 6% aqueous solution of ammonium persulfate were introduced into the reaction vessel and held at 80 ° C. for 15 minutes. Thereafter, the remaining monomer emulsion was dropped into the reaction vessel held at the same temperature over 3 hours, and after the end of the dropping, the mixture was aged for 1 hour, and then cooled to 30 ° C. while gradually adding 40 parts of a 5% aqueous solution of 2-(dimethylamino)ethanol to the reaction vessel, and the mixture was discharged while filtering through a 100-mesh nylon cloth, to obtain an acrylic resin water dispersion (R-1) with a solid concentration of 45%. The resulting acrylic resin water dispersion (R-1) had a hydroxyl value of 43 mgKOH / g and an acid value of 12 mgKOH / g.

[0204] Monomer emulsion: 50 parts of deionized water, 10 parts of styrene, 40 parts of methyl methacrylate, 35 parts of ethyl acrylate, 3.5 parts of n-butyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 1.5 parts of acrylic acid, 1.0 part of "Aqualon KH-10" and 0.03 parts of ammonium persulfate were mixed and stirred to obtain a monomer emulsion.

[0205] Preparation of hydroxyl-containing polyester resin solution (R-2) Manufacturing Example 2 In a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a water separator, 174 parts of trimethylolpropane, 327 parts of neopentyl glycol, 352 parts of adipic acid, 109 parts of isophthalic acid and 101 parts of 1,2-cyclohexanedicarboxylic anhydride were charged, and the temperature was raised from 160 ° C to 230 ° C over 3 hours, and the generated condensed water was distilled off by a water separator while maintaining the temperature at 230 ° C, and the reaction was continued until the acid value was 3 mg KOH / g or less. 59 parts of trimellitic anhydride was added to this reaction product, and an addition reaction was carried out at 170 ° C for 30 minutes, and then the mixture was cooled to 50 ° C or less, and 2- (dimethylamino) ethanol was added in an equivalent amount to the acid group to neutralize it, and deionized water was gradually added to obtain a hydroxyl group-containing polyester resin solution (R-2) with a solid content concentration of 45%. The resulting hydroxyl-containing polyester resin solution (R-2) had a hydroxyl value of 128 mgKOH / g, an acid value of 35 mgKOH / g, and a weight average molecular weight of 13,000.

[0206] Preparation of phosphoric acid-containing resin solution (R-3) Production Example 3 A mixed solvent of 27.5 parts of methoxypropanol and 27.5 parts of isobutanol was placed in a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device, and heated to 110 ° C., and 25 parts of styrene, 27.5 parts of n-butyl methacrylate, 20 parts of "isostearyl acrylate" (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd., branched higher alkyl acrylate), 7.5 parts of 4-hydroxybutyl acrylate, 15 parts of the following phosphoric acid group-containing polymerizable monomer, 12.5 parts of 2-methacryloyloxyethyl acid phosphate, 10 parts of isobutanol and 4 parts of t-butyl peroxy octanoate were added to the mixed solvent over 4 hours, and a mixture of 0.5 parts of t-butyl peroxy octanoate and 20 parts of isopropanol was added dropwise for 1 hour. After that, the mixture was stirred and aged for 1 hour to obtain a phosphoric acid group-containing resin solution (R-3) with a solid content concentration of 50%. The acid value due to the phosphate group of this resin was 83 mgKOH / g, the hydroxyl value was 29 mgKOH / g, and the weight average molecular weight was 10,000.

[0207] Phosphate-containing polymerizable monomer: 57.5 parts of monobutyl phosphate and 41 parts of isobutanol were placed in a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device, and the temperature was raised to 90°C. After that, 42.5 parts of glycidyl methacrylate were dropped over 2 hours, and the mixture was further stirred and aged for 1 hour. Then, 59 parts of isopropanol were added to obtain a phosphate-containing polymerizable monomer solution with a solid content concentration of 50%. The acid value of the resulting monomer due to the phosphate group was 285 mgKOH / g.

[0208] Manufacture of color pigment dispersion (P-1) Production Example 4 56 parts (solid content 25 parts) of the hydroxyl group-containing polyester resin solution (R-2) obtained in Production Example 2, 1.5 parts of "RAVEN 5000 ULTRA III BEADS" (trade name, carbon black pigment, manufactured by COLUMBIAN CARBON CO.), and 5 parts of deionized water were mixed, and the pH was adjusted to 8.0 with 2-(dimethylamino)ethanol. Next, the resulting mixture was placed in a wide-mouthed glass bottle, glass beads with a diameter of about 1.3 mm were added as a dispersion medium, and the bottle was sealed. The mixture was dispersed for 30 minutes using a paint shaker to obtain a color pigment dispersion (P-1).

[0209] Manufacture of glitter pigment dispersion (P-2) Production Example 5 In a stirring and mixing vessel, 10.8 parts (solid content 8 parts) of “GX-3100” (product name, aluminum pigment paste, manufactured by Asahi Kasei Metals Corporation, metal content 74%), 35 parts of 2-ethyl-1-hexanol, 8 parts (solid content 4 parts) of the phosphate group-containing resin solution (R-3) obtained in Production Example 3, and 0.2 parts of 2-(dimethylamino)ethanol were uniformly mixed to obtain a brilliant pigment dispersion (P-2).

[0210] Manufacture of base paint (X) Production Example 6 62.5 parts of the pigment dispersion paste (P-1) obtained in Production Example 4, 54 parts of the glittering pigment dispersion (P-2) obtained in Production Example 5, 44.4 parts (20 parts solids) of the acrylic resin water dispersion (R-1) obtained in Production Example 1, 60 parts (21 parts solids) of "U-coat UX-8100" (product name, urethane emulsion, manufactured by Sanyo Chemical Industries, Ltd., 35% solids), and 37.5 parts (30 parts solids) of "Cymel 325" (product name, melamine resin, manufactured by Nippon Cytec Industries, 80% solids) were uniformly mixed. Next, "UH-752" (product name, manufactured by ADEKA Corporation, thickener), 2-(dimethylamino)ethanol, and deionized water were added to the resulting mixture to obtain a base paint (X-1) having a pH of 8.0, a paint solids content of 25%, and a viscosity of 3000 mPa·s when measured using a B-type viscometer at 20°C and a rotation speed of 6 rpm.

[0211] Production Example 7 62.5 parts of the pigment dispersion paste (P-1) obtained in Production Example 4, 54 parts of the glittering pigment dispersion (P-2) obtained in Production Example 5, 44.4 parts (20 parts solids) of the acrylic resin water dispersion (R-1) obtained in Production Example 1, 60 parts (21 parts solids) of "U-coat UX-8100" (product name, urethane emulsion, manufactured by Sanyo Chemical Industries, Ltd., 35% solids), and 37.5 parts (30 parts solids) of "Cymel 325" (product name, melamine resin, manufactured by Nippon Cytec Industries, 80% solids) were uniformly mixed. Next, "UH-752" (product name, manufactured by ADEKA Corporation, thickener), 2-(dimethylamino)ethanol, and deionized water were added to the resulting mixture to obtain a base paint (X-2) having a pH of 8.0, a paint solid content of 14%, and a viscosity of 3500 mPa·s when measured using a B-type viscometer at 20°C and a rotation speed of 6 rpm.

[0212] Manufacture of acrylic resin water dispersion (R-4) Production Example 8 In a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device, 154 parts of deionized water and 0.52 parts of "Aqualon KH-10" were charged, and the mixture was stirred and mixed in a nitrogen stream and heated to 80°C. Next, 1% of the total amount of the monomer emulsion (1) described below and 5.3 parts of a 6% aqueous solution of ammonium persulfate were introduced into the reaction vessel and kept at 80°C for 15 minutes. After that, the remaining monomer emulsion (1) was dropped into the reaction vessel kept at the same temperature over 3 hours, and after the end of the dropping, the mixture was aged for 1 hour. After that, the following monomer emulsion (2) was dropped over 1 hour, and after aging for 1 hour, the mixture was cooled to 30°C while gradually adding 40 parts of a 5% aqueous solution of dimethylethanolamine to the reaction vessel, and the mixture was discharged while filtering through a 100-mesh nylon cloth, to obtain an acrylic resin water dispersion (R-4) with a solid content concentration of 28%. The resulting acrylic resin water dispersion (R-4) had a hydroxyl value of 25 mgKOH / g and an acid value of 33 mgKOH / g.

[0213] Monomer emulsion (1): 42 parts of deionized water, 0.72 parts of "Aqualon KH-10", 2.1 parts of methylenebisacrylamide, 2.8 parts of styrene, 16.1 parts of methyl methacrylate, 28 parts of ethyl acrylate and 21 parts of n-butyl acrylate were mixed and stirred to obtain a monomer emulsion (1).

[0214] Monomer emulsion (2): 18 parts of deionized water, 0.31 parts of "Aqualon KH-10", 0.03 parts of ammonium persulfate, 5.1 parts of methacrylic acid, 5.1 parts of 2-hydroxyethyl acrylate, 3 parts of styrene, 6 parts of methyl methacrylate, 1.8 parts of ethyl acrylate, and 9 parts of n-butyl acrylate were mixed and stirred to obtain a monomer emulsion (2).

[0215] Manufacturing acrylic resin solution (R-5) Production Example 9 A normal acrylic resin reaction tank equipped with a stirrer, a thermometer, and a reflux condenser was charged with 48 parts of ethylene glycol monobutyl ether, heated and stirred to maintain the temperature at 110°C. A mixture consisting of 10 parts of styrene, 40 parts of methyl methacrylate, 25 parts of n-butyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 3 parts of methacrylic acid, 5 parts of N,N-dimethylaminoethyl methacrylate (solid content, dissolved in 10 parts of deionized water and mixed), 10 parts of "NF Bisome PEM6E" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name, polyethylene glycol monomethacrylate, molecular weight about 350), 4 parts of azobisisobutyronitrile, and 20 parts of isobutyl alcohol was added dropwise over 3 hours. After the dropwise addition, the mixture was aged at 110°C for 30 minutes, and then an additional catalyst mixture consisting of 25 parts of ethylene glycol monobutyl ether and 0.5 parts of azobisisobutyronitrile was added dropwise over 1 hour. The mixture was then aged at 110°C for 1 hour and cooled to obtain an acrylic resin solution (R-5) with a solid content of 50%. The acrylic resin solution (R-5) had a hydroxyl value of 43 mgKOH / g and a weight average molecular weight of about 20,000.

[0216] Manufacture of color pigment dispersion (P-3) Manufacturing Example 10 10.2 parts (5.1 parts in terms of solid content) of the acrylic resin solution (R-5) obtained in Production Example 9, 3 parts of "RAVEN 5000 ULTRA III BEADS" (trade name, carbon black pigment, manufactured by COLUMBIAN CARBON CO.), and 39.4 parts of deionized water were mixed and dispersed for 2 hours using a paint shaker to obtain a color pigment dispersion (P-3) with a solid content of 15.4%.

[0217] Production of carboxyl group-containing cellulose nanofiber (C21) Manufacturing Example 11 5 g (bone-dry) of bleached softwood-derived dissolving kraft pulp (Buckeye DKP) was added to 500 ml of an aqueous solution containing 19.5 mg (0.025 mmol per 1 g of bone-dry cellulose) of TEMPO (Sigma Aldrich) and 514 mg (1.0 mmol per 1 g of bone-dry cellulose) of sodium bromide, and the mixture was stirred until the pulp was uniformly dispersed. After adding 8 ml of 2 M aqueous sodium hypochlorite solution to the reaction system, the pH was adjusted to 10.3 with 0.5 N aqueous hydrochloric acid to start the oxidation reaction. During the reaction, the pH in the system decreased, but was adjusted to pH 10 by successively adding 3.0 N aqueous sodium hydroxide solution. After reacting for 2 hours, the mixture was filtered through a glass filter and thoroughly washed with water to obtain carboxylated cellulose. The amount of carboxyl groups in the obtained carboxylated cellulose was 0.94 mmol / g. Then, hydrogen peroxide was added to the 5% (w / v) slurry of oxidized cellulose at 2% (w / v) relative to the oxidized cellulose, and the pH was adjusted to 12 with 1M sodium hydroxide. This slurry was hydrolyzed at 80°C for 2 hours. This was adjusted to 4.0% (w / v) with water and treated five times with an ultra-high pressure homogenizer (20°C, 140MPa) to obtain a carboxyl group-containing cellulose nanofiber dispersion (C21-1). The carboxyl group amount of the carboxyl group-containing cellulose nanofiber dispersion (C21-1) was 0.94mmol / g, the average fiber diameter was 6.9nm, the average fiber length was 235nm, and the aspect ratio was 34.

[0218] Preparation of cellulose nanocrystals (C32) containing sulfonic acid groups Manufacturing Example 12 "Celluforce NCC" (product name, manufactured by Celluforce, number average diameter 2.3-4.5 nm, number average length 44-108 nm, specific surface area 400 m2 / g, sulfonic acid group-containing cellulose nanocrystals, solids concentration 100%) was gradually added to deionized water stirred with a magnetic stirrer to give a solids concentration of 4%, and stirring was continued for 2 hours to obtain a sulfonic acid group-containing cellulose nanocrystal dispersion (C32-1).

[0219] Manufacturing of glitter pigment dispersions Example 1 Into a stirring mixing vessel, 4830 parts of distilled water, 15 parts (15 parts solids) of "Dynol-604" (trade name, manufactured by Evonik Industries, acetylene diol-based surface conditioner, solids content 100%), 434.8 parts (200 parts solids) of "Alpaste EMR-B6360" (trade name, manufactured by Toyo Aluminum Co., Ltd., solids content 46%, non-leafing aluminum flakes, average particle size D50: 10.3 μm, thickness: 0.19 μm, surface treated with silica), 150 parts (3 parts solids) of phosphoric acid group-containing cellulose nanofiber dispersion (C11-1) (number average fiber diameter 4 nm, amount of phosphoric acid group introduced 1.00 mmol / g, solids concentration 2.0%), 675 parts (27 parts solids) of the carboxyl group-containing cellulose nanofiber dispersion (C21-1) obtained in Production Example 11, and "Primal ASE-60" (trade name, Dow Chemical Company, polyacrylic acid-based viscosity modifier, 28% solids aqueous dispersion) 118.9 parts (33.3 parts solids), "TINUVIN 479-DW(N)" (trade name, BASF Company, ultraviolet absorber, 40% solids) 25 parts (10 parts solids), "TINUVIN 123-DW(N)" (trade name, BASF Company, light stabilizer, 50% solids) 13.2 parts (6.6 parts solids), and 52.6 parts (8.1 parts solids) of the color pigment dispersion (P-3) obtained in Production Example 10 were added and mixed with stirring to prepare a glittering pigment dispersion (Y-1). The solids of the resulting glittering pigment dispersion (Y-1) were 4.8%, and the paint viscosity "B6 value" was 1100 mPa·s.

[0220] Examples 2 to 10 and Comparative Examples 1 to 6 The procedure of Example 1 was repeated except for using the compositions shown in Table 1 to obtain brilliant pigment dispersions (Y-2) to (Y-16).

[0221] [Table 1]

[0222] [Table 2]

[0223] [Table 3]

[0224] (*1) “Xirallic T61-10 Micro Silver”: Product name, manufactured by Merck, 100% solids, titanium oxide-coated alumina flake pigment, average particle size 11.8 μm.

[0225] Comparative Example 7 As the glittering pigment dispersion (Y-17), a commercially available product "WBC-713T No. 1F7" (product name, manufactured by Kansai Paint Co., Ltd., acrylic melamine resin-based water-based base coat paint, silver paint color, solid content 23%, aluminum pigment-containing, nanocellulose (C)-free) was used.

[0226] Preparation of clear paint (Z) Clear paint (Z-1) "KINO6510" (product name: Kansai Paint Co., Ltd., hydroxyl group / isocyanate group curing type acrylic resin / urethane resin based two-liquid organic solvent type paint) was used as the clear paint (Z-1).

[0227] Creating test panels (1) Preparation of test plates for evaluating wrinkles, 60° specular gloss (60° gloss) and flip-flop properties Example 11 The base paint (X-1) was electrostatically coated onto the substrate prepared in [1] above using a rotary atomizing bell-type coater in a vertical position, so that the cured film thickness was 9 μm, and the substrate was left for 2 minutes to form an uncured base coating film.

[0228] Next, the glittering pigment dispersion (Y-1) prepared in Example 1 was applied onto the uncured base coating film in a vertical position using a robot bell manufactured by ABB Corp., under conditions of a booth temperature of 23°C and humidity of 68%, so that the dry coating film had a thickness of 0.7 μm. After leaving it for 3 minutes, it was preheated in a vertical position at 80°C for 3 minutes to form a glittering coating film.

[0229] Next, the clear coating (Z-1) was applied vertically onto the uncured glittering coating film using a robot bell manufactured by ABB Co., Ltd., under conditions of a booth temperature of 23°C and humidity of 68%, so that the film thickness of the dried coating film was 35 μm, forming a clear coating film. After coating, the plate was left at room temperature for 7 minutes, and then heated vertically at 140°C for 30 minutes in a hot air circulation drying oven to simultaneously dry the multi-layer coating film, and a test plate was prepared for evaluating wrinkles, 60° specular gloss (60° gloss), and flip-flop properties.

[0230] Here, the thickness of the dry coating film of the glittering coating film was calculated from the following formula. The same applies to the following examples. x=sc / sg / S*10000 x: Film thickness [μm] sc: Painted solid content [g] sg: Paint film specific gravity [g / cm 3 ] S: Evaluation area of ​​coating solids [cm 2 ]

[0231] Examples 12 to 21 and Comparative Examples 8 to 14 Test panels for evaluating wrinkles, 60° specular gloss (60° gloss) and flip-flop properties were obtained in the same manner as in Example 11, except that the paint, glittering pigment dispersion, and film thickness were as shown in Table 2.

[0232] (2) Preparation of test plates for evaluating sagging of vertical sections Example 11 On the long side of the substrate prepared in [1], 17 punch holes with a diameter of 5 mm were punched at 2 cm intervals in a row 3 cm from the end. Each punch hole was punched 10 cm away from the 400 mm long side.

[0233] Next, a test substrate was arranged so that the 400 mm side extended horizontally and the 300 mm side extended vertically. Base paint (X-1) was electrostatically coated onto the substrate in a vertical position using a rotary atomizing bell-type coater to a cured film thickness of 9 μm, and the substrate was left to stand for 2 minutes to form an uncured base coating film.

[0234] Next, the photochromic pigment dispersion (Y-1) prepared in Example 1 was applied onto the uncured base coating in a vertical position using an ABB Robot Bell at a booth temperature of 22°C and humidity of 78%, with a film thickness gradient to obtain a dry coating film thickness of approximately 0.5 μm to 4 μm in the longitudinal direction, and the coating was left for 3 minutes. It was then preheated at 80°C for 3 minutes in a vertical position to form a photochromic coating film.

[0235] Next, the clear coating (Z-1) was applied vertically onto the uncured glittering coating film using a robot bell manufactured by ABB Co., Ltd., under conditions of a booth temperature of 23°C and humidity of 68%, so that the film thickness of the dried coating film was 35 μm, forming a clear coating film. After coating, the plate was left at room temperature for 7 minutes, and then heated vertically at 140°C for 30 minutes in a hot air circulation drying oven, whereby the multi-layer coating film was simultaneously dried to obtain a test plate for evaluating sagging in the vertical portion.

[0236] Examples 12 to 21 and Comparative Examples 8 to 14 A test plate for evaluating sagging in a vertical portion was obtained in the same manner as in Example 11, except that the paint, the glittering pigment dispersion, and the film thickness were as shown in Table 2.

[0237] [Table 4]

[0238] [Table 5]

[0239] Coating evaluation Each test panel obtained as described above was evaluated for the following items, and the results are shown in Table 2.

[0240] Wrinkles The edges of each test plate were visually inspected and rated according to the following criteria, with A and B being acceptable. A: No wrinkles are observed and the coating film has an extremely excellent appearance. B: Almost no wrinkles are observed, and the coating film has excellent appearance. C: Wrinkles are noticeable or significant, and the coating appearance is poor.

[0241] 60° mirror gloss (60° gloss) The 60° gloss value was measured using a gloss meter (micro-TRI-gloss, manufactured by BYK-Gardner). The higher the value, the better. In the examples and comparative examples using aluminum pigments, a value of 122 or more is acceptable, and in the examples and comparative examples using optical interference pigments, a value of 97 or more is acceptable.

[0242] Flip-flopping A multi-angle colorimeter (BYK, product name: BYK-mac i) was used to measure the L* value at a light receiving angle of 15 degrees (L*15 value) and the L* value at a light receiving angle of 75 degrees (L*75 value), and the FF value of the coating film was calculated and evaluated using the following formula. In the examples and comparative examples using an aluminum pigment, a value of 8.0 or more was considered a pass, and in the examples and comparative examples using a light interference pigment, a value of 2.8 or more was considered a pass. FF value = L*15 value / L*75 value

[0243] Vertical section sag For each test panel, the position where sagging of the coating film was observed 3 mm from the bottom edge of the punch hole was examined, and the film thickness at that position (sagging limit film thickness (μm)) was measured to evaluate the sagging of the vertical part. The larger the sagging limit film thickness, the better the result. A thickness of 4 μm or more is acceptable.

[0244] In Table 2, the "-" in the sagging limit film thickness for Comparative Example 14 indicates that no sagging occurred at a dry film thickness of 4 μm for the brilliant pigment dispersion (Y-1).

[0245] Although the embodiments and examples of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical concept of the present invention are possible.

Claims

1. A glittering pigment dispersion containing a wetting agent (A), a glittering pigment (B), nanocellulose (C) and water (D), The solid content is 0.1 to 10 parts by mass relative to 100 parts by mass of the total of all components of the brilliant pigment dispersion, The nanocellulose (C) comprises at least one selected from the group consisting of phosphate group-containing nanocellulose (C1), carboxyl group-containing nanocellulose (C2), and sulfonic acid group-containing nanocellulose (C3). A glittering pigment dispersion.

2. The brilliant pigment dispersion according to claim 1 , wherein the brilliant pigment (B) contains an aluminum pigment.

3. The brilliant pigment dispersion according to claim 1, wherein the phosphate group-containing nanocellulose (C1) comprises a phosphate group-containing cellulose nanofiber (C11) and / or a phosphate group-containing cellulose nanocrystal (C12).

4. The cellulose (C) comprises a carboxyl group-containing nanocellulose (C2), and the carboxyl group-containing nanocellulose (C2) comprises a carboxyl group-containing cellulose nanofiber (C21) and / or a carboxyl group-containing cellulose nanocrystal (C22). The brilliant pigment dispersion according to any one of claims 1 to 3.

5. The cellulose (C) comprises a sulfonic acid group-containing nanocellulose (C3), and the sulfonic acid group-containing nanocellulose (C3) comprises a sulfonic acid group-containing cellulose nanofiber (C31) and / or a sulfonic acid group-containing cellulose nanocrystal (C32). The brilliant pigment dispersion according to any one of claims 1 to 3.

6. The content ratio of the phosphate group-containing nanocellulose (C1) to at least one selected from the group consisting of carboxyl group-containing nanocellulose (C2) and sulfonic acid group-containing nanocellulose (C3) is in the range of 1 / 99 to 50 / 50 in terms of mass ratio of the phosphate group-containing nanocellulose (C1) to at least one selected from the group consisting of the carboxyl group-containing nanocellulose (C2) and the sulfonic acid group-containing nanocellulose (C3). The brilliant pigment dispersion according to any one of claims 1 to 3.

7. Step (1): A step of applying a base coating material (X) onto a substrate to form an uncured base coating film; Step (2): A step of applying the glittering pigment dispersion (Y) according to claim 1 onto the base coating film formed in step (1) to form an uncured glittering coating film. Step (3): A step of applying an uncured clear coating (Z) onto the glossy coating film formed in step (2) to form a clear coating film; and Step (4): A method for forming a multilayer coating film, comprising a step of simultaneously heating and curing the uncured base coating film formed in step (1), the uncured glossy coating film formed in step (2), and the uncured clear coating film formed in step (3).