Glittering pigment dispersion, glittering paint composition, and method for forming multi-layered coating film

Abstract

Provided is a photoluminescent pigment dispersion liquid which contains: a silica-treated aluminum pigment (A) having an amino group at the surface; a first dispersing resin (B); and water. The solids content in the silica-treated aluminum pigment (A) having an amino group at the surface is 90 mass% or more. The first dispersing resin (B) is a polymer of a composition containing: an acidic functional group-containing polymerizable unsaturated monomer (b1); a polyoxyalkylene chain-containing non-ionic polymerizable unsaturated monomer (b2); and another polymerizable unsaturated monomer (b3). The water content is 90 mass% or more relative to the amount of solvent in the photoluminescent pigment dispersion liquid.

Description

[Technical field]

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

[0002] In recent years, from the perspective of protecting the global environment, there has been a demand to reduce the amount of volatile organic compounds (VOCs) emitted from paints, and the replacement of solvent-based paints with water-based paints is progressing rapidly in various fields.

[0003] More recently, there has been a demand to reduce the amount of volatile organic compounds (VOCs) contained in water-based paints.

[0004] On the other hand, the coating film formed by applying paint is expected to protect the object being painted and also to give it a design (beautiful appearance). In particular, metallic paint colors are popular as they exude a sense of luxury.

[0005] However, when the amount of organic solvent is reduced in order to reduce the amount of volatile organic compounds (VOCs) in metallic paint colors, the dispersibility of the aluminum pigment deteriorates, making it difficult to obtain a paint film with high luster.

[0006] Patent Document 1 describes an aluminum pigment composition for water-based paints that contains at least an aluminum pigment, a rheology control agent, and an organic solvent, the organic solvent having a solubility parameter of 6 to 12 and a solubility in water at 20°C of 30% by mass or less, the rheology control agent being added in an amount of 2.5 parts by mass per 100 parts by mass of solids in a resin emulsion and the viscosity being measured using a B-type viscometer, the viscosity B60 at 60 revolutions and the viscosity B6 at 6 revolutions are both in the range of 0.3 to 30 Pa·s, and the thixotropic index B6 / B60, which is the ratio of B6 to B60, is 1 to 60. This aluminum pigment composition for water-based paints describes that the orientation of the aluminum pigment after application is improved, thereby improving metallic unevenness, and thus making it possible to achieve a color tone and appearance comparable to those of organic solvent-based paints.

[0007] Although the above-mentioned aluminum pigment composition for water-based paint has good luster, in recent years, there has been a demand for further reduction in the amount of volatile organic compounds (VOCs). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2009-242457 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to provide a brilliant pigment dispersion that can be used to produce a brilliant coating composition that has a low content of volatile organic compounds (VOCs) and is capable of forming a coating film with excellent brilliant properties. [Means for solving the problem]

[0010] According to the present invention, there are provided a glittering pigment dispersion, a glittering coating composition, and a method for forming a multilayer coating film, which include the following aspects.

[0011] Item 1. A brilliant pigment dispersion comprising a silica-treated aluminum pigment (A) having an amino group on its surface, a first dispersing resin (B), and water, The solid content of the silica-treated aluminum pigment (A) having an amino group on its surface is 90 mass% or more, and The first dispersion resin (B) is a polymer of a composition containing a polymerizable unsaturated monomer (b1) having an acidic functional group, a nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain, and another polymerizable unsaturated monomer (b3), A brilliant pigment dispersion, the content of water being 90 mass % or more based on the amount of the solvent in the brilliant pigment dispersion.

[0012] Item 2. The brilliant pigment dispersion according to Item 1, wherein the silica-treated aluminum pigment (A) having an amino group on its surface includes a silica-treated aluminum pigment (A1) having an amino group and an alkyl group on its surface.

[0013] Item 3. The brilliant pigment dispersion liquid according to Item 1 or 2, wherein the polymerizable unsaturated monomer (b1) containing an acidic functional group includes a polymerizable unsaturated monomer containing a carboxyl group.

[0014] Item 4. The brilliant pigment dispersion liquid according to any one of Items 1 to 3, further comprising a second dispersing resin (C) which is a polymer of a composition containing a polymerizable unsaturated monomer (c1) containing at least one functional group selected from the group consisting of a tertiary amino group and a quaternary ammonium salt group, a nonionic polymerizable unsaturated monomer (c2) having a polyoxyalkylene chain, and another polymerizable unsaturated monomer (c3).

[0015] Item 5. A glittering coating composition comprising the glittering pigment dispersion according to any one of items 1 to 4 and a film-forming resin.

[0016] Item 6. The following steps (1) to (4): Step (1): A step of applying a colored coating composition (X) onto an object to be coated to form a colored coating film; Step (2): A step of applying the glittering coating composition (Y) described in Item 5 onto the colored coating film obtained in Step (1) to form a glittering coating film; Step (3): A step of applying a clear coating composition (Z) onto the glossy coating film obtained in step (2) to form a clear coating film; Step (4): A method for forming a multilayer coating film, comprising a step of simultaneously curing the multilayer coating film including the color coating film, the glossy coating film and the clear coating film formed in steps (1), (2) and (3), respectively, by heating the multilayer coating film. Effect of the Invention

[0017] By using the brilliant pigment dispersion of the present invention, it is possible to produce a brilliant coating composition that has a low content of volatile organic compounds (VOCs) and is capable of forming a coating film with excellent brilliant properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] In this specification, the term "comprise" is a concept that encompasses "consist essentially of" and "consist only of." 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, the upper or lower limit of a numerical range described in this specification, including the claims, may be replaced with the upper or lower limit shown in the examples or a value that can be unambiguously derived from the examples. 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.

[0019] The bright pigment dispersion of the present invention will be described in further detail below.

[0020] Bright pigment dispersion The brilliant pigment dispersion of the present invention is a brilliant pigment dispersion containing a silica-treated aluminum pigment (A) having an amino group on its surface, a first dispersing resin (B), and water, The solid content of the silica-treated aluminum pigment (A) having an amino group on its surface is 90 mass% or more, and The first dispersion resin (B) is a polymer of a composition containing a polymerizable unsaturated monomer (b1) having an acidic functional group, a nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain, and another polymerizable unsaturated monomer (b3), The content of water in the brilliant pigment dispersion is 90 mass % or more based on the amount of the solvent in the brilliant pigment dispersion.

[0021] From the viewpoint of producing a glittering coating composition with a low content of volatile organic compounds (VOCs), the content of the water is preferably 92% by mass or more, more preferably 94% by mass or more, based on the amount of the solvent in the glittering pigment dispersion. Examples of the solvent include water and organic solvents. The amount of the solvent in the glittering pigment dispersion is the total amount of one or more solvents contained in the glittering pigment dispersion.

[0022] Silica-treated aluminum pigment having amino groups on its surface (A) The silica-treated aluminum pigment (A) having amino groups on its surface has a solid content of 90% by mass or more. In particular, from the viewpoint of producing a bright coating composition with a low content of volatile organic compounds (VOCs), the solid content is preferably 95% by mass or more, and more preferably 99% by mass or more.

[0023] The silica-treated aluminum pigment (A) having an amino group on its surface can be produced by reacting an aluminum pigment whose surface has been silica-treated with a silane coupling agent. Such modification of silica-treated aluminum pigments with amino groups is known.

[0024] The silica-treated aluminum pigment (A) having amino groups on its surface interacts with the acidic functional groups of the first dispersing resin (B) because of the amino groups on its surface, improving the dispersibility of the silica-treated aluminum pigment (A), and the glittering coating composition containing the silica-treated aluminum pigment (A) can form a coating film with excellent glittering properties.

[0025] From the viewpoint that the glittering coating composition containing the silica-treated aluminum pigment (A) forms a coating film having excellent glittering properties, the silica-treated aluminum pigment (A) preferably has an average particle size in the range of 1 to 100 μm, more preferably in the range of 5 to 50 μm, and even more preferably in the range of 7 to 30 μm, and the thickness is preferably in the range of 0.01 to 1.0 μm, and even more preferably in the range of 0.02 to 0.5 μm.

[0026] From the viewpoints of dispersibility and the water resistance and luster of the coating film formed, the silica-treated aluminum pigment (A) having an amino group on its surface preferably contains a silica-treated aluminum pigment (A1) having an amino group and an alkyl group on its surface.

[0027] The silica-treated aluminum pigment (A1) having an amino group and an alkyl group on the surface can be produced by reacting an aluminum pigment having a silica-treated surface with a silane coupling agent. Such modification of silica-treated aluminum pigments with amino groups and alkyl groups is known.

[0028] From the viewpoint of producing a brilliant coating composition that has a low content of volatile organic compounds (VOCs) and is capable of forming a coating film with excellent brilliant properties, the content of the silica-treated aluminum pigment (A) having amino groups on its surface in the brilliant pigment dispersion of the present invention is preferably 60 to 95 parts by mass, more preferably 65 to 93 parts by mass, and even more preferably 70 to 90 parts by mass, based on 100 parts by mass of the solids in the brilliant pigment dispersion.

[0029] First Dispersion Resin (B) The first dispersion resin (B) is a polymer of a composition containing a polymerizable unsaturated monomer (b1) containing an acidic functional group, a nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain, and another polymerizable unsaturated monomer (b3).

[0030] Examples of the polymerizable unsaturated monomer (b1) containing an acidic functional group include a polymerizable unsaturated monomer containing a carboxyl group, a polymerizable unsaturated monomer containing a phosphoric acid group, and a polymerizable unsaturated monomer containing a sulfonic acid group. Of these, it is preferable to include a polymerizable unsaturated monomer containing a carboxyl group.

[0031] The polymerizable unsaturated monomer containing a carboxyl group is a compound having one or more carboxyl groups and one polymerizable unsaturated group in one molecule, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, etc. These may be used alone or in combination of two or more.

[0032] The polymerizable unsaturated monomer having a phosphoric acid group is a compound having one or more phosphoric acid groups and one polymerizable unsaturated group in one molecule, and examples thereof include acid phosphooxyethyl (meth)acrylate, acid phosphooxypropyl (meth)acrylate, acid phosphooxypoly(oxyethylene)glycol (meth)acrylate, acid phosphooxypoly(oxypropylene)glycol (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0033] The polymerizable unsaturated monomer containing a sulfonic acid group is a compound having one or more sulfonic acid groups and one polymerizable unsaturated group in one molecule, and examples thereof include 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth)acrylate, allylsulfonic acid, 4-styrenesulfonic acid, etc.; sodium salts and ammonium salts of these sulfonic acids, etc. These may be used alone or in combination of two or more.

[0034] In this specification, the polymerizable unsaturated group refers to an unsaturated group capable of undergoing radical polymerization. Examples of such polymerizable unsaturated groups include vinyl groups and (meth)acryloyl groups.

[0035] In addition, in this specification, "(meth)acrylate" means acrylate or methacrylate. "(meth)acrylic acid" means acrylic acid or methacrylic acid. "(meth)acryloyl" means acryloyl or methacryloyl. "(meth)acrylamide" means acrylamide or methacrylamide.

[0036] The proportion of the polymerizable unsaturated monomer (b1) containing an acidic functional group in the monomers constituting the first dispersion resin (B) is preferably 1 to 30 mass%, more preferably 3 to 25 mass%, and even more preferably 5 to 20 mass%, based on the total amount of the polymerizable unsaturated monomer (b1) containing an acidic functional group, the nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain, and the other polymerizable unsaturated monomer (b3).

[0037] The nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain is a monomer having a polyoxyalkylene chain and a polymerizable unsaturated group in one molecule. Examples of the polyoxyalkylene chain include a polyoxyethylene chain, a polyoxypropylene chain, and a block chain of polyoxyethylene and polyoxypropylene.

[0038] The molecular weight of the polyoxyalkylene chain is preferably within the range of 150-3,000, and more preferably 300-2,500.

[0039] The nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain is, for example, a monomer represented by the following formula (1): CH2=C(R 3 )COO(C n H 2n O) m -R 4 (1) (In the formula, R 3 represents a hydrogen atom or a methyl group, and R 4 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, m is an integer of 4 to 60, preferably 6 to 50, and n is 2 or 3, preferably 2, wherein m oxyalkylene units (C n H 2n O) may be the same or different from each other) Examples of the compound include those represented by the following formula:

[0040] Specific examples of the nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain include tetraethylene glycol (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, ethoxytetraethylene glycol (meth)acrylate, n-butoxytetraethylene glycol (meth)acrylate, tetrapropylene glycol (meth)acrylate, methoxytetrapropylene glycol (meth)acrylate, ethoxytetrapropylene glycol (meth)acrylate, n-butoxytetrapropylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and ethoxypolyethylene glycol (meth)acrylate. These may be used alone or in combination of two or more.

[0041] The proportion of the nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain in the monomers constituting the first dispersion resin (B) is preferably 50 to 95 mass%, more preferably 55 to 93 mass%, and even more preferably 60 to 90 mass%, based on the total amount of the polymerizable unsaturated monomer (b1) containing an acidic functional group, the nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain, and the other polymerizable unsaturated monomer (b3).

[0042] The other polymerizable unsaturated monomer (b3) is a compound having one polymerizable unsaturated bond in one molecule other than the above monomers (b1) and (b2), and specific examples thereof are listed below. (i) Alkyl or cycloalkyl (meth)acrylates: for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, tricyclodecanyl (meth)acrylate, and the like. (ii) Polymerizable unsaturated monomers having an isobornyl group: isobornyl (meth)acrylate, etc. (iii) Polymerizable unsaturated monomers having an adamantyl group: adamantyl (meth)acrylate, etc. (iv) Polymerizable unsaturated monomers having a tricyclodecenyl group: tricyclodecenyl (meth)acrylate, etc. (v) Aromatic ring-containing polymerizable unsaturated monomers: benzyl (meth)acrylate, styrene, α-methylstyrene, vinyltoluene, and the like. (vi) Polymerizable unsaturated monomers having an alkoxysilyl group: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane, and the like. (vii) Polymerizable unsaturated monomers having a fluorinated alkyl group: perfluoroalkyl (meth)acrylates such as perfluorobutylethyl (meth)acrylate and perfluorooctylethyl (meth)acrylate; fluoroolefins, and the like. (viii) Polymerizable unsaturated monomers having a photopolymerizable functional group such as a maleimide group. (ix) Vinyl compounds: N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate, etc. (x) Nitrogen-containing polymerizable unsaturated monomers: (meth)acrylonitrile, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, methylene bis(meth)acrylamide, ethylene bis(meth)acrylamide, adducts of glycidyl (meth)acrylate and amine compounds, and the like. (xi) Polymerizable unsaturated monomers having two or more polymerizable unsaturated groups in one molecule: allyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, etc. (xii) Epoxy group-containing polymerizable unsaturated monomers: glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, allyl glycidyl ether, and the like. (xiii) Polymerizable unsaturated monomers having an ultraviolet absorbing functional group: 2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2-hydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole, and the like. (xiv) Light-stable polymerizable unsaturated monomers: 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, and the like. (xv) Polymerizable unsaturated monomers having a carbonyl group: acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrol, vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone), and the like. (xvi) Polymerizable unsaturated monomers having an acid anhydride group: maleic anhydride, itaconic anhydride, citraconic anhydride, etc. (xvii) Hydroxyl group-containing polymerizable unsaturated monomers: monoesters of polyhydric alcohols and (meth)acrylic acid, such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2,3-dihydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. [other than the nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain]; compounds obtained by ring-opening polymerization of the above monoesters of polyhydric alcohols and (meth)acrylic acid with ε-caprolactone, and the like.

[0043] The proportion of the other polymerizable unsaturated monomer (b3) in the monomers constituting the first dispersion resin (B) is preferably 1 to 25 mass%, more preferably 2 to 15 mass%, and even more preferably 3 to 10 mass%, based on the total amount of the polymerizable unsaturated monomer (b1) containing an acidic functional group, the nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain, and the other polymerizable unsaturated monomer (b3).

[0044] The polymerization of the monomer constituting the first dispersion resin (B) can be carried out by a method known per se, such as a solution polymerization method in an organic solvent or an emulsion polymerization method in water, among which the solution polymerization method is preferred. As a polymerization method by the solution polymerization method, for example, a method can be mentioned in which a mixture of a polymerizable unsaturated monomer (b1) containing an acidic functional group, a nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain, and other polymerizable unsaturated monomers (b3) and a radical polymerization initiator is dissolved or dispersed in an organic solvent, and usually heated at a temperature of about 80°C to about 200°C for about 1 to 10 hours while stirring to polymerize.

[0045] Examples of the organic solvent include hydrocarbon solvents such as heptane, toluene, xylene, octane, and mineral spirits; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, and diethylene glycol monobutyl ether acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone; alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, sec-butanol, and isobutanol; ether solvents such as n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monomethyl ether; and aromatic petroleum solvents such as Swazol 310, Swazol 1000, and Swazol 1500 manufactured by Cosmo Oil Co., Ltd. These organic solvents can be used alone or in combination of two or more.

[0046] Examples of the radical polymerization initiator include ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, and methylcyclohexanone peroxide; peroxyketals such as 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxy)cyclohexane, and n-butyl-4,4-bis(tert-butylperoxy)valerate; hydroperoxides such as cumene hydroperoxide and 2,5-dimethylhexane-2,5-dihydroperoxide; 1,3-bis(tert-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, diisopropylbenzene peroxide, and tert-butyl peroxyketals. Examples of the polymerization initiator include dialkyl peroxides such as tylcumyl peroxide; diacyl peroxides such as decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, and 2,4-dichlorobenzoyl peroxide; peroxycarbonates such as bis(tert-butylcyclohexyl)peroxydicarbonate; organic peroxide-based polymerization initiators such as peroxyesters such as tert-butyl peroxybenzoate and 2,5-dimethyl-2,5-di(benzoylperoxy)hexane; and azo-based polymerization initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylpropionate)dimethyl, 1,1-azobis(cyclohexane-1-carbonitrile), azocumene 2,2'-azobismethylvaleronitrile, and 4,4'-azobis(4-cyanovaleric acid). The amount of these radical polymerization initiators used is not particularly limited, but is preferably 0.1 to 15 parts by weight, and more preferably 0.3 to 10 parts by weight, per 100 parts by weight of the total amount of polymerizable monomers.

[0047] From the viewpoints of the curability and water resistance of the resulting coating film, the first dispersing resin (B) preferably has a hydroxyl value in the range of 0.1 to 20 mgKOH / g, more preferably in the range of 0.5 to 15 mgKOH / g, and even more preferably in the range of 1 to 10 mgKOH / g.

[0048] From the viewpoint of interaction with the amino groups of the silica-treated aluminum pigment (A) having amino groups on its surface, the first dispersing resin (B) preferably has an acid value in the range of 5 to 200 mg KOH / g, more preferably in the range of 15 to 180 mg KOH / g, and even more preferably in the range of 30 to 150 mg KOH / g.

[0049] From the viewpoint of dispersion stability, etc., the first dispersion resin (B) preferably has a weight average molecular weight in the range of 1,000 to 50,000, more preferably in the range of 2,000 to 40,000, and further preferably in the range of 3,000 to 30,000.

[0050] From the viewpoint of producing a brilliant coating composition that has a low content of volatile organic compounds (VOCs) and is capable of forming a coating film with excellent brilliant properties, the content of the first dispersion resin (B) in the brilliant pigment dispersion of the present invention is preferably 0.1 to 20.0 parts by mass, more preferably 0.2 to 15.0 parts by mass, and even more preferably 0.3 to 10.0 parts by mass, based on 100 parts by mass of the solid content in the brilliant pigment dispersion.

[0051] From the viewpoint of producing a brilliant coating composition that has a low content of volatile organic compounds (VOCs) and is capable of forming a coating film with excellent brilliant properties, it is preferable that the brilliant pigment dispersion of the present invention further contains a second dispersing resin (C).

[0052] Second Dispersing Resin (C) The second dispersing resin (C) is a polymer of a composition containing a polymerizable unsaturated monomer (c1) containing at least one functional group selected from the group consisting of a tertiary amino group and a quaternary ammonium base, a nonionic polymerizable unsaturated monomer (c2) having a polyoxyalkylene chain, and another polymerizable unsaturated monomer (c3).

[0053] In the present invention, when a dispersing resin corresponds to both the first dispersing resin (B) and the second dispersing resin (C), it is considered to be included in the first dispersing resin (B).

[0054] Examples of polymerizable unsaturated monomers containing a tertiary amino group include N,N-dialkylaminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-di-t-butylaminoethyl (meth)acrylate, and N,N-dimethylaminobutyl (meth)acrylate; and N,N-dialkylaminoalkyl (meth)acrylamides such as N,N-dimethylaminoethyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylamide, and N,N-dimethylaminopropyl (meth)acrylamide.

[0055] Examples of quaternary ammonium base-containing polymerizable unsaturated monomers include (meth)acryloyloxyalkyltrialkylammonium salts such as 2-(methacryloyloxy)ethyltrimethylammonium chloride, 2-(methacryloyloxy)ethyltrimethylammonium bromide, and 2-(methacryloyloxy)ethyltrimethylammonium dimethylphosphate; and (meth)acryloylaminoalkyltrialkylammonium salts such as methacryloylaminopropyltrimethylammonium chloride and methacryloylaminopropyltrimethylammonium bromide.

[0056] The polymerizable unsaturated monomer (c1) containing at least one functional group selected from the group consisting of a tertiary amino group and a quaternary ammonium salt group preferably contains a polymerizable unsaturated monomer containing a tertiary amino group, from the viewpoint of producing a glittering coating composition which has a low content of volatile organic compounds (VOCs) and is capable of forming a coating film having excellent glittering properties.

[0057] The proportion of the polymerizable unsaturated monomer (c1) containing at least one functional group selected from the group consisting of the tertiary amino group and the quaternary ammonium base in the monomers constituting the second dispersion resin (C) is preferably 0.1 to 20 mass%, more preferably 0.5 to 15 mass%, and even more preferably 1 to 10 mass%, based on the total amount of the polymerizable unsaturated monomer (c1) containing at least one functional group selected from the group consisting of the tertiary amino group and the quaternary ammonium base, the nonionic polymerizable unsaturated monomer (c2) having a polyoxyalkylene chain, and the other polymerizable unsaturated monomer (c3).

[0058] As the nonionic polymerizable unsaturated monomer having a polyoxyalkylene chain (c2), the compounds described in the explanation section for the nonionic polymerizable unsaturated monomer having a polyoxyalkylene chain (b2) can be used.

[0059] The proportion of the nonionic polymerizable unsaturated monomer (c2) having a polyoxyalkylene chain in the monomers constituting the second dispersion resin (C) is preferably 1 to 50 mass%, more preferably 3 to 40 mass%, and even more preferably 5 to 30 mass%, based on the total amount of the polymerizable unsaturated monomer (c1) containing at least one functional group selected from the group consisting of a tertiary amino group and a quaternary ammonium base, the nonionic polymerizable unsaturated monomer (c2) having a polyoxyalkylene chain, and the other polymerizable unsaturated monomer (c3).

[0060] The other polymerizable unsaturated monomer (c3) is a compound having one polymerizable unsaturated bond in one molecule other than the above monomers (c1) and (c2), and specific examples thereof are listed below. (i) Alkyl or cycloalkyl (meth)acrylates: for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, tricyclodecanyl (meth)acrylate, and the like. (ii) Polymerizable unsaturated monomers having an isobornyl group: isobornyl (meth)acrylate, etc. (iii) Polymerizable unsaturated monomers having an adamantyl group: adamantyl (meth)acrylate, etc. (iv) Polymerizable unsaturated monomers having a tricyclodecenyl group: tricyclodecenyl (meth)acrylate, etc. (v) Aromatic ring-containing polymerizable unsaturated monomers: benzyl (meth)acrylate, styrene, α-methylstyrene, vinyltoluene, and the like. (vi) Polymerizable unsaturated monomers having an alkoxysilyl group: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane, and the like. (vii) Polymerizable unsaturated monomers having a fluorinated alkyl group: perfluoroalkyl (meth)acrylates such as perfluorobutylethyl (meth)acrylate and perfluorooctylethyl (meth)acrylate; fluoroolefins, and the like. (viii) Polymerizable unsaturated monomers having a photopolymerizable functional group such as a maleimide group. (ix) Vinyl compounds: N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate, etc. (x) Carboxyl group-containing polymerizable unsaturated monomers: (meth)acrylic acid, maleic acid, crotonic acid, β-carboxyethyl (meth)acrylate, etc. (xi) Hydroxyl group-containing polymerizable unsaturated monomers: monoesters of polyhydric alcohols and (meth)acrylic acid, such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2,3-dihydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. [other than the above-mentioned nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain]; compounds obtained by ring-opening polymerization of the above-mentioned monoesters of polyhydric alcohols and (meth)acrylic acid with ε-caprolactone, etc. (xii) Polymerizable unsaturated monomers having two or more polymerizable unsaturated groups in one molecule: allyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, etc. (xiii) Epoxy group-containing polymerizable unsaturated monomers: glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, allyl glycidyl ether, and the like. (xiv) Polymerizable unsaturated monomers having a sulfonic acid group: 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth)acrylate, allylsulfonic acid, 4-styrenesulfonic acid, and the like; sodium salts and ammonium salts of these sulfonic acids. (xv) Polymerizable unsaturated monomers having a phosphoric acid group: acid phosphooxyethyl (meth)acrylate, acid phosphooxypropyl (meth)acrylate, acid phosphooxypoly(oxyethylene)glycol (meth)acrylate, acid phosphooxypoly(oxypropylene)glycol (meth)acrylate, and the like. (xvi) Polymerizable unsaturated monomers having an ultraviolet absorbing functional group: 2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2-hydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole, and the like. (xvii) Light-stable polymerizable unsaturated monomers: 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, and the like. (xviii) Polymerizable unsaturated monomers having a carbonyl group: acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrol, vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone), and the like. (xix) Polymerizable unsaturated monomers having an acid anhydride group: maleic anhydride, itaconic anhydride, citraconic anhydride, etc.

[0061] The proportion of the other polymerizable unsaturated monomer (c3) in the monomers constituting the second dispersion resin (C) is preferably 45 to 90 mass%, more preferably 55 to 87 mass%, and even more preferably 65 to 85 mass%, based on the total amount of the polymerizable unsaturated monomer (c1) containing at least one functional group selected from the group consisting of a tertiary amino group and a quaternary ammonium base, the nonionic polymerizable unsaturated monomer (c2) having a polyoxyalkylene chain, and the other polymerizable unsaturated monomer (c3).

[0062] The monomer constituting the second dispersion resin (C) can be polymerized by a conventionally known method. From the viewpoint of the dispersibility of the silica-treated aluminum pigment (A) having an amino group on the surface, the second dispersion resin (C) is preferably an AB block polymer that can be obtained by an addition-fragmentation chain transfer polymerization method using an addition-fragmentation chain transfer agent. Specifically, a block polymer can be produced by adding and fragmenting chain transfer polymerization of the monomer components constituting the block in the presence of the addition-fragmentation chain transfer agent. The addition-fragmentation chain transfer polymerization can be carried out, for example, by a solution polymerization method in an organic solvent or an emulsion polymerization method in water. In addition, during polymerization, in addition to the addition-fragmentation chain transfer agent, a known radical polymerization initiator can be used in combination as desired.

[0063] As the addition fragmentation type chain transfer agent, for example, 2,4-diphenyl-4-methyl-1-pentene (sometimes abbreviated as "α-methylstyrene dimer" or "MSD") can be suitably used. MSD is preferably used in the first polymerization.

[0064] The AB block polymer preferably comprises an A block containing a polymerizable unsaturated monomer (c1) containing at least one functional group selected from the group consisting of a tertiary amino group and a quaternary ammonium base and another polymerizable unsaturated monomer (c3), and a B block containing a nonionic polymerizable unsaturated monomer (c2) having a polyoxyalkylene chain and another polymerizable unsaturated monomer (c3).

[0065] In the above-mentioned AB block polymer, the ratio (mass ratio) of the total amount of monomers constituting the A block to the total amount of monomers constituting the B block is preferably within the range of 10 / 90 to 60 / 40, and more preferably within the range of 20 / 80 to 50 / 50, from the viewpoint of the dispersibility of the silica-treated aluminum pigment (A) having amino groups on its surface.

[0066] From the viewpoints of the curability and water resistance of the resulting coating film, the second dispersing resin (C) preferably has a hydroxyl value in the range of 10 to 100 mgKOH / g, more preferably in the range of 20 to 80 mgKOH / g, and even more preferably in the range of 30 to 60 mgKOH / g.

[0067] From the viewpoint of interaction with the silica-treated aluminum pigment (A) having amino groups on its surface and the first dispersing resin (B), the second dispersing resin (C) preferably has an amine value in the range of 1 to 30 mg KOH / g, more preferably in the range of 3 to 25 mg KOH / g, and even more preferably in the range of 5 to 20 mg KOH / g.

[0068] From the viewpoint of dispersion stability, etc., the second dispersing resin (C) preferably has a weight average molecular weight in the range of 1,000 to 50,000, more preferably in the range of 2,000 to 40,000, and even more preferably in the range of 3,000 to 30,000.

[0069] From the viewpoint of producing a brilliant coating composition that has a low content of volatile organic compounds (VOCs) and is capable of forming a coating film with excellent brilliant properties, the content of the second dispersion resin (C) in the brilliant pigment dispersion of the present invention is preferably 1 to 25 parts by mass, more preferably 3 to 23 parts by mass, and even more preferably 5 to 20 parts by mass, based on 100 parts by mass of solids in the brilliant pigment dispersion.

[0070] Other Ingredients If necessary, the brilliant pigment dispersion of the present invention may further contain an organic solvent, a pigment other than the silica-treated aluminum pigment (A) having amino groups on its surface, a viscosity adjuster, an anti-settling agent, an ultraviolet absorber, a light stabilizer, and the like.

[0071] From the viewpoint of producing a brilliant coating composition that has a low content of volatile organic compounds (VOCs) and is capable of forming a coating film with excellent brilliant properties, the solids content of the brilliant pigment dispersion of the present invention is preferably within the range of 10 to 50 mass %, and more preferably within the range of 20 to 40 mass %.

[0072] Bright paint composition (Y) The glittering coating composition (Y) of the present invention is a glittering coating composition containing the glittering pigment dispersion of the present invention and a film-forming resin.

[0073] The content of water in the glittering coating composition (Y) of the present invention is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the amount of solvent in the glittering coating composition (Y), from the viewpoint of producing a glittering coating composition (Y) with a low content of volatile organic compounds (VOCs). Examples of the solvent include water and organic solvents. The amount of solvent in the glittering coating composition (Y) is the total amount of one or more solvents contained in the glittering coating composition (Y).

[0074] Examples of the film-forming resin include acrylic resin, polyester resin, epoxy resin, and urethane resin.

[0075] 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.

[0076] Examples of the polyester resin that can be used 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.

[0077] The epoxy resin may be, for example, a so-called bisphenol A type epoxy resin produced by a condensation reaction between bisphenol A and epichlorohydrin.

[0078] Examples of the urethane resin include a compound obtained by an addition reaction between a diisocyanate compound and a polyhydric alcohol, and a polymerized resin obtained by reacting the above-mentioned acrylic resin, polyester resin or epoxy resin with a diisocyanate compound.

[0079] The film-forming resin preferably has a sufficient amount of hydrophilic groups to be water-soluble or water-dispersible.

[0080] Examples of the hydrophilic group include a carboxyl group, a hydroxyl group, a methylol group, an amino group, a sulfonic acid group, and a polyoxyethylene bond, and among these, a carboxyl group is preferable.

[0081] The hydrophilic groups are preferably neutralized with sodium hydroxide, an amine compound, or the like to form an alkali salt.

[0082] 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. Furthermore, the resin can also be dispersed in water in the presence of an emulsifier, for example. In this case, the base resin does not need to contain the hydrophilic group.

[0083] The above-mentioned film-forming resins can be used alone or in combination of two or more kinds. From the viewpoint of forming a coating film having excellent luster, the content of the film-forming resin in the glittering coating composition (Y) of the present invention is preferably within the range of 30 to 85 parts by mass, more preferably within the range of 35 to 80 parts by mass, based on 100 parts by mass of the total solids in the glittering coating composition (Y).

[0084] The glittering coating composition (Y) of the present invention preferably further contains a curing agent.

[0085] Examples of the curing agent include amino resins, polyisocyanate compounds, blocked polyisocyanate compounds, etc. The curing agents may be used alone or in combination of two or more kinds.

[0086] When the bright coating composition (Y) of the present invention contains the above-mentioned curing agent, the content of the film-forming resin and the curing agent is preferably within the range of 50 to 90 mass %, particularly preferably 60 to 85 mass %, of the former, and preferably 10 to 50 mass %, particularly preferably 15 to 40 mass %, of the latter, based on the total mass of both components.

[0087] In addition to the above-mentioned components, the glittering coating composition (Y) of the present invention may contain, as desired, a coloring pigment, an extender pigment, a glittering pigment other than the silica-treated aluminum pigment (A) having amino groups on its surface, a curing catalyst, an ultraviolet absorber, an antifoaming agent, a viscosity modifier, a surface modifier, an organic solvent, etc.

[0088] 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 preferable.

[0089] When the glittering coating composition (Y) of the present invention contains the above-mentioned coloring pigment, the content of the coloring pigment is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, based on 100 parts by mass of the resin solid content in the glittering coating composition (Y).

[0090] Examples of the extender pigment include barium sulfate, talc, clay, kaolin, barium carbonate, calcium carbonate, silica, and alumina white.

[0091] When the glittering coating composition (Y) of the present invention contains the above-mentioned extender pigment, the content of the extender pigment is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, based on 100 parts by mass of the resin solids in the glittering coating composition (Y).

[0092] Examples of the luster pigment other than the silica-treated aluminum pigment (A) having an amino group on its surface include aluminum (including vapor-deposited aluminum) other than the silica-treated aluminum pigment (A) having an amino group on its surface, copper, zinc, brass, nickel, glass flakes, aluminum oxide, mica, aluminum oxide coated with titanium oxide and / or iron oxide, and mica coated with titanium oxide and / or iron oxide.

[0093] When the glittering coating composition (Y) of the present invention contains a glittering pigment other than the silica-treated aluminum pigment (A) having an amino group on its surface, the content of the glittering pigment is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, based on 100 parts by mass of the resin solids in the glittering coating composition (Y).

[0094] Examples of the curing catalyst include tin octylate, dibutyltin diacetate, dibutyltin di(2-ethylhexanoate), dibutyltin dilaurate, dioctyltin diacetate, dioctyltin di(2-ethylhexanoate), dibutyltin oxide, dibutyltin sulfide, dioctyltin oxide, dibutyltin fatty acid salts, lead 2-ethylhexanoate, zinc octylate, zinc naphthenate, zinc fatty acids, bismuth octanoate, bismuth 2-ethylhexanoate, bismuth oleate, bismuth neodecanoate, and bismuth versatic acid. Examples of compounds that can be used include organometallic compounds such as smuth, bismuth naphthenate, cobalt naphthenate, calcium octylate, copper naphthenate, and tetra(2-ethylhexyl)titanate; sulfonic acid group-containing compounds such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, and dinonylnaphthalenesulfonic acid; and phosphate group-containing compounds such as monobutyl phosphate, dibutyl phosphate, mono 2-ethylhexyl phosphate, di 2-ethylhexyl phosphate, alkyl ether phosphate, polyoxyethylene alkyl ether phosphate, and phosphate group-containing resins.

[0095] When used, the glittering coating composition (Y) of the present invention can be diluted by adding water and / or an organic solvent, etc., if necessary, and adjusted to an appropriate viscosity before coating.

[0096] The appropriate viscosity varies depending on the coating composition, but it is preferable to appropriately adjust the viscosity using water and / or an organic solvent so that the viscosity, measured at 20°C and 6 rpm using a B-type viscometer, is within the range of 2000 to 7000 mPa s. In addition, the coating solids concentration of the glittering coating composition (Y) is preferably 3 to 30 mass%, and more preferably about 5 to 25 mass%.

[0097] The glittering coating composition (Y) of the present invention may be either a one-component coating or a multi-component coating. However, it is preferable that the composition be a one-component coating, since this eliminates the need for a coating mixing step, which results in superior productivity, and it simplifies the maintenance of coating machines.

[0098] The glittering coating composition (Y) of the present invention can be applied to a substrate by a method known per se, such as air spray coating, airless spray coating, rotary atomization coating, curtain coating, etc., and electrostatic application may be performed during coating. Among these, air spray coating, rotary atomization coating, etc. are preferred. Furthermore, such coating methods can be performed once or several times until a desired film thickness is obtained.

[0099] The amount of the glittering coating composition (Y) of the present invention applied is preferably an amount that results in a cured film thickness of 0.5 to 20 μm, more preferably 1 to 15 μm, and even more preferably 2 to 10 μm.

[0100] Multi-layer coating method The method for forming a multilayer coating film of the present invention comprises the following steps (1) to (4): Step (1): A step of applying a colored coating composition (X) onto an object to be coated to form a colored coating film; Step (2): A step of applying the glittering coating composition (Y) of the present invention onto the colored coating film obtained in step (1) to form a glittering coating film; Step (3): A step of applying a clear coating composition (Z) onto the glossy coating film obtained in step (2) to form a clear coating film; Step (4): A method for forming a multilayer coating film, comprising a step of simultaneously curing the multilayer coating film including the color coating film, the glossy coating film and the clear coating film formed in steps (1), (2) and (3), respectively, by heating the multilayer coating film.

[0101] The above-mentioned substrate is not particularly limited, and examples thereof include outer panels of automobile bodies such as passenger cars, trucks, motorcycles, and buses, automobile parts, and outer panels of household electrical appliances such as mobile phones and audio equipment. Of these, the outer panels of automobile bodies and automobile parts are preferred.

[0102] The material of these substrates is not particularly limited. For example, metal materials such as iron, aluminum, brass, copper, tinplate, stainless steel, zinc-plated steel, zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.)-plated steel; resins such as polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, epoxy resin, and various plastic materials such as FRP; inorganic materials such as glass, cement, and concrete; wood; and fiber materials such as paper and cloth. Among these, metal materials and plastic materials are preferred.

[0103] The surfaces of the objects to which the multilayer coating film is applied may be metal surfaces such as the outer panels of automobile bodies, automobile parts, household electrical appliances, and the metal substrates such as the steel plates that make up these items, which have been subjected to surface treatments such as phosphate treatment, chromate treatment, and composite oxide treatment.

[0104] A coating film may be further formed on the object, which may or may not have been surface-treated. For example, the substrate to be coated may be surface-treated as necessary, and an undercoat coating film and / or an intermediate coating film may be formed thereon. For example, when the substrate to be coated is an automobile body, the undercoat coating film and / or intermediate coating film may be formed using a coating composition for undercoat and / or intermediate coating that is known per se and that is usually used in the painting of automobile bodies.

[0105] As the undercoat paint composition for forming the undercoat paint film, for example, an electrodeposition paint, preferably a cationic electrodeposition paint, can be used. Also, as the intermediate coat paint composition for forming the intermediate coat paint film, a paint made of a base resin having a crosslinkable functional group such as a carboxyl group, a hydroxyl group, or the like, such as an acrylic resin, a polyester resin, an alkyd resin, a urethane resin, or an epoxy resin, and an amino resin such as a melamine resin or a urea resin, or a crosslinking agent such as an optionally blocked polyisocyanate compound, together with a pigment, a thickener, and other optional components can be used.

[0106] As the colored coating composition (X), a thermosetting colored coating composition known for coating automobile bodies, etc., can be used, and for example, a thermosetting coating composition containing a base resin having a crosslinkable functional group, a crosslinking agent, a color pigment, and an extender pigment can be suitably used. In addition, a luster pigment can also be contained.

[0107] Examples of the crosslinkable functional group contained in the base resin include a carboxyl group, a hydroxyl group, and an epoxy group.

[0108] Examples of the base resin include acrylic resin, polyester resin, alkyd resin, and urethane resin.

[0109] Examples of the crosslinking agent include a melamine resin, a polyisocyanate compound, and a blocked polyisocyanate compound.

[0110] As the colored coating composition (X), either an aqueous coating composition or an organic solvent-based coating composition may be used, but from the viewpoint of reducing the environmental load, an aqueous coating composition is preferred.

[0111] The coating method of the colored coating composition (X) is not particularly limited, but for example, a wet coating film can be formed by a coating method such as air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, etc. In these coating methods, electrostatic application may be performed as necessary. Among these, air spray coating or rotary atomization coating is particularly preferred. The coating amount of the colored coating composition (X) is preferably an amount that results in a cured film thickness of 5 to 30 μm, more preferably an amount that results in a cured film thickness of 7 to 20 μm.

[0112] When air spray coating, airless spray coating or rotary atomization coating is performed, the viscosity of the colored coating composition (X) is appropriately adjusted using a solvent such as water or an organic solvent so that it is within a viscosity range suitable for such coating, preferably within a viscosity range of about 15 to 60 seconds, particularly preferably about 20 to 50 seconds, at 20°C as measured by a Ford Cup No. 4 viscometer.

[0113] As the clear coating composition (Z), any of the thermosetting clear coating compositions known for painting automobile bodies and the like can be used, such as organic solvent-based thermosetting coating compositions containing a base resin having a crosslinkable functional group and a curing agent, water-based thermosetting coating compositions, and powder thermosetting coating compositions.

[0114] 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.

[0115] Preferred combinations of base resin / curing agent for the clear coating composition (Z) include carboxyl group-containing resin / epoxy group-containing resin, hydroxyl group-containing resin / polyisocyanate compound, hydroxyl group-containing resin / blocked polyisocyanate compound, hydroxyl group-containing resin / melamine resin, etc.

[0116] The clear coating composition (Z) may be a one-liquid coating material, or a multi-liquid coating material such as a two-liquid urethane resin coating material.

[0117] Furthermore, the above-mentioned clear coating composition (Z) may contain color pigments, luster pigments, dyes, etc., as necessary, to the extent that transparency is not impaired, and further may contain appropriate amounts of extender pigments, ultraviolet absorbers, light stabilizers, defoamers, thickeners, rust inhibitors, surface conditioners, etc.

[0118] The coating method of the clear coating composition (Z) is not particularly limited, but for example, a wet coating film can be formed by a coating method such as air spray coating, airless spray coating, rotary atomization coating, curtain coating, etc. In these coating methods, electrostatic application may be performed as necessary. Among these, air spray coating or rotary atomization coating is particularly preferred. The coating amount of the clear coating composition (Z) is preferably an amount that results in a cured film thickness of 10 to 50 μm, more preferably an amount that results in a cured film thickness of 20 to 40 μm.

[0119] When air spray coating, airless spray coating, or rotary atomization coating is performed, the viscosity of the clear coating composition (Z) is appropriately adjusted using a solvent such as an organic solvent so that the viscosity is within a range suitable for such coating, preferably within a range of about 15 to 60 seconds, and particularly preferably within a range of about 20 to 50 seconds, at 20°C as measured using a Ford Cup No. 4 viscometer.

[0120] The heating can be carried out 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 preferably within a range of 70 to 160° C., more preferably 90 to 150° C. The heating time is not particularly limited, but is preferably within a range of 10 to 60 minutes, more preferably 20 to 40 minutes. EXAMPLES

[0121] The present invention will be described in more detail below with reference to Production Examples, Examples, and Comparative Examples. Note that these Production Examples, Examples, and Comparative Examples are merely illustrative and are not intended to limit the scope of the present invention. In the Production Examples, Examples, and Comparative Examples, "parts" and "%" are based on mass unless otherwise specified. Furthermore, the film thickness of the coating film is based on the cured coating film.

[0122] 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.

[0123] On the electrocoated surface of the above-mentioned steel plate, "WP-523H" (product name: Kansai Paint Co., Ltd., acrylic / melamine resin-based water-based undercoat paint) was applied using an air spray to a film thickness of 20 μm based on the cured coating film. After leaving it for 3 minutes, it was preheated at 80°C for 3 minutes to form an uncured undercoat coating film, thereby preparing the coated article.

[0124] 2. Preparation of Paint Preparation of hydroxyl-containing acrylic resin emulsion (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, 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 described below and 5 parts of a 6% aqueous solution of ammonium persulfate were introduced into the reaction vessel and kept at 80°C for 15 minutes. Thereafter, the remaining monomer emulsion 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, 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 a hydroxyl-containing acrylic resin emulsion (1) with a solid content concentration of 45%. The resulting hydroxyl-containing acrylic resin emulsion (1) had a hydroxyl value of 43 mgKOH / g and an acid value of 12 mgKOH / g.

[0125] 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.

[0126] Preparation of Hydroxyl-Containing Polyester Resin (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 using a water separator while maintaining the temperature at 230°C and reacting until the acid value was 3mgKOH / 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, followed by cooling to 50°C or less, and neutralization by adding an equivalent amount of 2-(dimethylamino)ethanol to the acid group, followed by gradually adding deionized water to obtain a hydroxyl group-containing polyester resin (2) solution with a solid content concentration of 45% and a pH of 7.2. The resulting hydroxyl-containing polyester resin (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.

[0127] Manufacturing of color pigment dispersion paste Production Example 3 56 parts of the hydroxyl-containing polyester resin (2) solution obtained in Production Example 2 (25 parts solids), 60 parts of "JR-806" (manufactured by Teika Co., Ltd., trade name, rutile-type titanium dioxide), 1 part of "Carbon MA-100" (manufactured by Mitsubishi Chemical Co., Ltd., trade name, carbon black), 15 parts of "Variace B-35" (trade name, manufactured by Sakai Chemical Industry Co., Ltd., barium sulfate powder), and 5 parts of deionized water were mixed and adjusted to pH 8.0 with 2-(dimethylamino)ethanol. Next, the resulting mixture was placed in a wide-mouth glass bottle, glass beads with a diameter of about 1.3 mm were added as a dispersion medium, and the bottle was sealed, and the mixture was dispersed for 30 minutes using a paint shaker to obtain a color pigment dispersion paste (P-1).

[0128] Preparation of colored coating composition (X) Production Example 4 137 parts of the color pigment dispersion paste (P-1) obtained in Production Example 3, 25 parts (11 parts solids) of the hydroxyl-containing acrylic resin emulsion (1) obtained in Production Example 1, 20 parts (9 parts solids) of the polyester resin solution (2) obtained in Production Example 2, 78 parts (30 parts solids) of "Bayhydur VPLS2310" (trade name, manufactured by Sumika Covestro Urethane Co., Ltd., blocked polyisocyanate compound, 38% solids) and 72 parts (25 parts solids) of "Ucoat UX-8100" (trade name, manufactured by Sanyo Chemical Industries, Ltd., urethane emulsion, 35% solids) were uniformly mixed. Next, "UH-752" (trade name, manufactured by ADEKA Corporation, thickener), 2-(dimethylamino)ethanol and deionized water were added to the resulting mixture to obtain a color coating composition (X-1) having a pH of 8.0, a coating solid content of 48%, and a viscosity of 30 seconds according to Ford Cup No. 4 at 20 ° C.

[0129] Preparation of the first dispersion resin (B) Production Example 5 A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, a nitrogen inlet tube and a dropping device was charged with 75 parts of propylene glycol monomethyl ether and heated to 95°C, after which a mixture of 2 parts of styrene, 1.5 parts of n-butyl methacrylate, 1.5 parts of hydroxyethyl methacrylate, 12 parts of methacrylic acid, 83 parts of methoxypolyethylene glycol methacrylate (molecular weight about 496), 120 parts of propylene glycol monomethyl ether and 10 parts of 2,2'-azobis(2-methylbutyronitrile) was added dropwise over 4 hours, and the mixture was aged for 30 minutes after the end of the dropwise addition. Then, a mixture of 10 parts of propylene glycol monomethyl ether and 0.5 parts of 2,2'-azobis(2-methylbutyronitrile) was added dropwise over 1 hour, and the mixture was aged for 1 hour after the end of the dropwise addition. Then, the mixture was desolvated under reduced pressure, and propylene glycol monomethyl ether was removed until the solid content was 90% by mass. The resulting first dispersion resin (B-1) had a weight average molecular weight of 5,000, an acid value of 78 mg KOH / g, and a hydroxyl value of 6.5 mg KOH / g.

[0130] Manufacturing Examples 6 to 13 Solutions of first dispersion resins (B-2) to (B-9) with a solid content of 90 mass% were obtained in the same manner as in Production Example 5, except that the blending composition in Production Example 5 was as shown in Table 1. The weight average molecular weight, acid value, and hydroxyl value of each of the first dispersion resins are also shown in Table 2.

[0131] [Table 1]

[0132] [Table 2]

[0133] Preparation of the second dispersing resin (C) Manufacturing Example 14 A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, and a dropping device was charged with 18.2 parts of ethylene glycol monobutyl ether and 11.8 parts of 2,4-diphenyl-4-methyl-1-pentene, and the mixture was stirred and mixed in a nitrogen stream until the temperature reached 120°C. Then, the following monomer mixture I was added dropwise over 6 hours, and the mixture was aged at 120°C for 30 minutes. <Composition of Monomer Mixture I> Methyl methacrylate 87 parts N,N-Dimethylaminoethyl methacrylate 12 parts Tridecyl methacrylate 0.5 parts Lauryl methacrylate 0.5 parts 2,2'-Azobis(2-methylbutyronitrile) 3 parts Ethylene glycol monobutyl ether 6 parts Next, the following additional catalyst mixture was added dropwise to the aged product over 1 hour, and after aging at 120°C for 1 hour, 18 parts of ethylene glycol monobutyl ether and 22.7 parts of propylene glycol monobutyl ether were added so that the solid content concentration was 60%, to obtain a solution of polymer A, which is a macromonomer. The weight average molecular weight of the obtained polymer A was about 3000. <Additional catalyst mixture> 2,2'-Azobis(2-methylbutyronitrile) 0.5 parts Ethylene glycol monobutyl ether 9 parts Next, 41.7 parts of the above polymer A, which is a macromonomer, was charged into a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, and a dropping device, and the mixture was stirred and mixed in a nitrogen stream until the temperature reached 95°C. Then, the following monomer mixture II and monomer mixture III were dropped over 3 hours, and the mixture was aged at 95°C for 30 minutes. <Composition of Monomer Mixture II> Methyl methacrylate 45 parts 2-Hydroxyethyl methacrylate 10 parts 2,2'-Azobis(2-methylbutyronitrile) 0.9 parts Propylene glycol monobutyl ether 5 parts <Composition of Monomer Mixture III> Methoxypolyethyleneglycol methacrylate (molecular weight approximately 2080) 20 parts 20 parts deionized water Ethylene glycol monobutyl ether 5 parts The following additional catalyst mixture was then added dropwise to the aged product over 1 hour, and the mixture was aged at 95°C for 1 hour, after which 36 parts of propylene glycol monobutyl ether was added to give a solids concentration of 53%, to obtain a second dispersion resin (C-1) solution, which is an AB block polymer. The resulting polymer had a weight average molecular weight of about 15,000, an amine value of 9.5 mgKOH / g, and a hydroxyl value of 43 mgKOH / g. <Additional catalyst mixture> 2,2'-azobis(2-methylbutyronitrile) 0.375 parts Propylene glycol monobutyl ether 6 parts Preparation of Carboxylic Acid Group-Containing Dispersing Resin (3) Manufacturing Example 15 A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, a nitrogen inlet tube and a dropping device was charged with 35 parts of propylene glycol monopropyl ether and heated to 85°C, after which a mixture of 30 parts of methyl methacrylate, 20 parts of 2-ethylhexyl acrylate, 29 parts of n-butyl acrylate, 15 parts of 2-hydroxyethyl acrylate, 6 parts of acrylic acid, 15 parts of propylene glycol monopropyl ether and 2.3 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) was added dropwise over 4 hours, and the mixture was aged for 1 hour after the end of the dropwise addition. Then, a mixture of 10 parts of propylene glycol monopropyl ether and 1 part of 2,2'-azobis(2,4-dimethylvaleronitrile) was added dropwise over 1 hour, and the mixture was aged for 1 hour after the end of the dropwise addition. 7.4 parts of diethanolamine were further added to obtain a carboxylic acid group-containing dispersion resin (3) solution with a solid content of 55%. The resulting carboxylic acid group-containing dispersion resin (3) had an acid value of 47 mgKOH / g, a hydroxyl value of 72 mgKOH / g, and a weight average molecular weight of 58,000.

[0134] Preparation of phosphoric acid group-containing dispersing resin (4) Manufacturing Example 16 A mixed solvent of 27.5 parts of methoxypropanol and 27.5 parts of isobutanol was placed in a reaction vessel equipped with 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 dispersion resin (4) solution 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.

[0135] 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 of 50%. The acid value of the resulting monomer due to the phosphate group was 285 mgKOH / g.

[0136] Preparation of dispersion resin (5) containing nonionic polymerizable unsaturated monomer having amino group and polyoxyalkylene chain Manufacturing Example 17 20 parts of ethylene glycol monobutyl ether was charged into a four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet, and the temperature was raised to 95°C under nitrogen gas aeration. After reaching 95°C, the nitrogen gas aeration was stopped, and a mixture consisting of 10 parts of styrene, 40 parts of methyl methacrylate, 10 parts of 2-hydroxyethyl acrylate, 10 parts of dimethylaminoethyl methacrylate, 30 parts of methoxypolyethylene glycol methacrylate (molecular weight about 1000), 65 parts of ethylene glycol monobutyl ether, and 1 part of 2,2'-azobisisobutyronitrile was dropped over 3 hours. After aging for 2 hours while aerating nitrogen gas at 95°C, the mixture was cooled to 60°C and diluted with 15 parts of ethylene glycol monobutyl ether to obtain a nonionic polymerizable unsaturated monomer-containing dispersion resin (5) solution having an amino group and a polyoxyalkylene chain with a solid content of 50%. The resulting dispersion resin (5) containing a nonionic polymerizable unsaturated monomer having an amino group and a polyoxyalkylene chain had an amine value of 35.5 mgKOH / g, a hydroxyl value of 48.4 mgKOH / g and a number average molecular weight of 6,500.

[0137] Manufacture of glitter pigment dispersions Example 1 In a stirring and mixing vessel, 30 parts (solids: 30 parts) of aluminum pigment A (silica-treated aluminum pigment having amino groups and alkyl groups on the surface, average particle size (d50) 19 μm, average thickness 0.40 μm, solids concentration 100%), 80 parts of deionized water, and 2 parts (solids: 1.8 parts) of the first dispersion resin (B-1) obtained in Production Example 5 were uniformly mixed to obtain a brilliant pigment dispersion (P-2).

[0138] Examples 2 to 10 and Comparative Examples 1 to 4 Except for using the compositions shown in Table 2, the same procedure as in Example 1 was followed to obtain brilliant pigment dispersions (P-3) to (P-15).

[0139] [Table 3]

[0140] [Table 4]

[0141] Preparation of hydroxyl-containing acrylic resin emulsion (6) Manufacturing Example 18 In a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, and a dropping device, 130 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. Thereafter, the remaining monomer emulsion (1) was dropped into the reaction vessel kept at the same temperature over a period of 3 hours, and after the end of the dropping, the mixture was aged for 1 hour. Thereafter, the monomer emulsion (2) described below was dropped over a period of 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 a hydroxyl-containing acrylic resin emulsion (6) with a solid content concentration of 30%. The resulting hydroxyl-containing acrylic resin emulsion (6) had a hydroxyl value of 25 mgKOH / g and an acid value of 33 mgKOH / g.

[0142] 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).

[0143] 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).

[0144] Manufacture of acrylic resin for dispersing color pigments (7) Manufacturing Example 19 48 parts of ethylene glycol monobutyl ether was charged into a normal acrylic resin reaction tank equipped with a stirrer, a thermometer, and a reflux condenser, and the temperature was maintained at 110°C while being heated and stirred. 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 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 was completed, 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 a solution of acrylic resin (7) for dispersing color pigments with a solid content of 50%. The acrylic resin for dispersing color pigments (7) had a hydroxyl value of 43 mgKOH / g and a weight average molecular weight of about 20,000.

[0145] Production of hydroxyl-containing polyester resin (8) Manufacturing Example 20 In a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a water separator, 109 parts of trimethylolpropane, 141 parts of 1,6-hexanediol, 126 parts of hexahydrophthalic anhydride and 120 parts of adipic acid were charged and heated, and the temperature was raised from 160°C to 230°C over 3 hours, and then condensation reaction was carried out at 230°C for 4 hours. Next, in order to add carboxyl groups to the obtained condensation reaction product, 38.3 parts of trimellitic anhydride were further added, and the reaction was carried out at 170°C for 30 minutes, and then diluted with 2-ethyl-1-hexanol to obtain a hydroxyl group-containing polyester resin (8) solution with a solid content concentration of 70%. The obtained hydroxyl group-containing polyester resin (8) had a hydroxyl value of 150 mgKOH / g, an acid value of 46 mgKOH / g and a weight average molecular weight of 6,400.

[0146] Manufacturing of color pigment dispersion paste (P-16) Manufacturing Example 21 16 parts (8 parts in terms of solids) of the acrylic resin (7) for dispersing color pigment obtained in Production Example 19, 5 parts of "RAVEN 5000 ULTRA III BEADS" (trade name, carbon black pigment, manufactured by Columbia Carbon Co.), and 70 parts of deionized water were mixed and dispersed for 2 hours using a paint shaker to obtain a color pigment dispersion paste (P-16) with a solids content of 14.3%.

[0147] Manufacture of glittering paint composition (Y) Example 11 112 parts (31.8 parts solids) of the glittering pigment dispersion liquid (P-2) obtained in Example 1, 91 parts (13 parts solids) of the color pigment dispersion paste (P-16) obtained in Production Example 21, 83.3 parts (25 parts solids) of the hydroxyl-containing acrylic resin emulsion (6) obtained in Production Example 18, 35.7 parts (25 parts solids) of the hydroxyl-containing polyester resin (8) solution obtained in Production Example 20, 37.5 parts (30 parts solids) of "Cymel 325" (trade name, manufactured by Allnex Co., Ltd., melamine resin, 80% solids), and 20.4 parts (10.2 parts solids) of the phosphoric acid group-containing dispersion resin (4) solution obtained in Production Example 16 were uniformly mixed. Next, "Primal ASE-60" (product name, Rohm and Haas, thickener, solids content 28%), 2-(dimethylamino)ethanol and deionized water were added to the obtained mixture to obtain a glittering coating composition (Y-1) having a pH of 7.8, a coating solids content of 14%, and a viscosity of 2000 mPa s when measured at 20°C and 6 rpm using a B-type viscometer. The water content in the glittering coating composition (Y-1) was 89 mass% based on the solvent amount in the glittering coating composition (Y).

[0148] Examples 12 to 21, Comparative Examples 5 to 8 Each of the glittering coating compositions (Y-2) to (Y-15) was obtained in the same manner as in Example 11, except that the blending compositions were as shown in Table 3 below.

[0149] [Table 5]

[0150] [Table 6]

[0151] 3. Preparation of test plates Example 22 The colored coating composition (X-1) obtained in Production Example 4 was electrostatically coated on the substrate prepared in "1. Preparation of substrate" above, using a rotary atomizing bell-type coating machine, so that the cured film thickness was 12 μm, and the substrate was left for 2 minutes to form a colored coating film. Furthermore, the glittering coating composition (Y-1) obtained in Example 11 was coated on the colored coating film, using a robot bell manufactured by ABB Corporation, under conditions of a booth temperature of 23°C and a humidity of 68%, so that the dried coating film thickness was 4 μm. The substrate was left for 3 minutes, and then preheated at 80°C for 3 minutes to form a glittering coating film. Next, on this glossy coating film, a clear coating composition (Z-1) "Magicron KINO-1210TW" (trade name, manufactured by Kansai Paint Co., Ltd., an acrylic resin-based organic solvent-based clear coating composition containing a carboxyl group-containing resin and an epoxy group-containing resin) was applied to form a dry coating film of 35 μm using a robot bell manufactured by ABB Corporation under conditions of a booth temperature of 23°C and a humidity of 68%, to form a clear coat coating film. After coating, it was left at room temperature for 7 minutes, and then heated at 140°C for 30 minutes using a hot air circulation drying oven to simultaneously dry the multi-layer coating film to obtain a test panel.

[0152] Examples 23 to 32, Comparative Examples 9 to 12 Test panels were obtained in the same manner as in Example 22, except that the paints shown in Table 4 were used.

[0153] [Table 7]

[0154] [Table 8]

[0155] [Table 9]

[0156] Coating evaluation The test panels thus obtained were evaluated for the following items, and the results are shown in Table 4.

[0157] Brilliance grade Sg(15°) value: A CCD chip was placed in the perpendicular direction to the planar direction of the measurement target surface of each test plate to capture the measurement target surface, and the CCD chip was used to take images of the measurement target surface with light irradiated on the measurement target surface from an angle of 15° to the perpendicular direction, and the brilliance grade Sg(15°) value was evaluated by analyzing the obtained images with an image analysis algorithm using a histogram of brightness levels. A multi-angle colorimeter (manufactured by BYK, product name: BYK-mac i) was used for the measurement. The smaller the value, the less graininess there is. A value of 10 or less is considered to be acceptable.

[0158] FF value: Using a multi-angle colorimeter BYK-mac i (product name, manufactured by BYK-Gardner), L with a light receiving angle of 15 degrees * Value (L * 15 values) and a light receiving angle of 110 degrees L * Value (L * 110 value) and calculate using the following formula. The larger the value, the greater the change in luminance depending on the observation angle, and the more excellent the brilliance. A value of 50 or more is considered a pass. FF value = L at 15 degree light receiving angle * Value (L * 15 values) - L with a light receiving angle of 110 degrees * Value (L * 110 value). The test panels of Examples 22-32 passed both the brilliance grade Sg value and FF value, and the multi-layer coating film had excellent brilliance. On the other hand, the test panels of Comparative Examples 9 and 10 failed the brilliance grade Sg value, and Comparative Examples 11 and 12 failed the FF value.

Claims

1. A brilliant pigment dispersion comprising a silica-treated aluminum pigment (A) having an amino group on its surface, a first dispersing resin (B), and water, The solid content of the silica-treated aluminum pigment (A) having an amino group on its surface is 90 mass% or more, and The average particle size of the silica-treated aluminum pigment (A) having an amino group on its surface is 1 to 100 μm, and The first dispersion resin (B) is a polymer of a composition containing a polymerizable unsaturated monomer (b1) having an acidic functional group, a nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain, and another polymerizable unsaturated monomer (b3), Based on the total amount of the polymerizable unsaturated monomer (b1) containing an acidic functional group, the nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain, and the other polymerizable unsaturated monomer (b3), the proportion of the polymerizable unsaturated monomer (b1) containing an acidic functional group is 1 to 30 mass%, and the proportion of the nonionic polymerizable unsaturated monomer (b2) having a polyoxyalkylene chain is 50 to 95 mass%, and A brilliant pigment dispersion, the content of water being 90 mass % or more based on the amount of the solvent in the brilliant pigment dispersion.

2. 2. The brilliant pigment dispersion according to claim 1, wherein the silica-treated aluminum pigment (A) having an amino group on its surface comprises a silica-treated aluminum pigment (A1) having an amino group and an alkyl group on its surface.

3. 3. The brilliant pigment dispersion according to claim 1, wherein the polymerizable unsaturated monomer (b1) containing an acidic functional group includes a polymerizable unsaturated monomer containing a carboxyl group.

4. 3. The brilliant pigment dispersion according to claim 1 or 2, further comprising a second dispersing resin (C) which is a polymer of a composition containing a polymerizable unsaturated monomer (c1) containing at least one functional group selected from the group consisting of a tertiary amino group and a quaternary ammonium salt group, a nonionic polymerizable unsaturated monomer (c2) having a polyoxyalkylene chain, and another polymerizable unsaturated monomer (c3).

5. A glittering paint composition comprising the glittering pigment dispersion according to claim 1 or 2 and a film-forming resin.

6. The following steps (1) to (4): Step (1): A step of applying a colored coating composition (X) onto an object to be coated to form a colored coating film; Step (2): A step of applying the glittering coating composition (Y) according to claim 5 onto the colored coating film obtained in step (1) to form a glittering coating film; Step (3): A step of applying a clear coating composition (Z) onto the glossy coating film obtained in step (2) to form a clear coating film; Step (4): A method for forming a multilayer coating film, comprising a step of simultaneously curing the multilayer coating film including the color coating film, the glossy coating film and the clear coating film formed in steps (1), (2) and (3), respectively, by heating the multilayer coating film.

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