JP2017110033A - Coating Composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition which can suppress a generation amount of fume such as silica fume at the time of baking, can keep stain resistance for a long period of time in outdoor exposure, and can form a coating film excellent in coating film hardness and workability.SOLUTION: There are provided a coating composition which contains a hydroxyl group-containing resin (a), a crosslinking agent (b) and a sulfosuccinic acid alkaline earth metal salt-based anionic surfactant (c), where the coating composition contains 0.1-20 pts.mass of the sulfosuccinic acid alkaline earth metal salt-based anionic surfactant (c) with respect to 100 pts.mass of the total solid content of the hydroxyl group-containing resin (a) and the crosslinking agent (b); and a coating film forming method which includes forming a primer coating film on one surface or both surfaces on a metal plate, and forming a coating film formed of the coating composition on at least one surface of the primer coating film.SELECTED DRAWING: Figure 1

Description

  The present invention can suppress the generation amount of fume such as silica fume at the time of baking, and can maintain the contamination resistance for a long period of time when exposed outdoors. Furthermore, it is related with the coating composition which can form a coating film with favorable coating-film hardness and workability.

  Conventionally, outdoor base materials (for example, buildings, display objects, guard fences, appliances, machines, etc.) have been coated with an outdoor paint excellent in weather resistance for the purpose of decoration or protection. Examples of outdoor paints include polyurethane resin paints, fluororesin paints, silicon resin paints, acrylic resin paints, and polyester paints.

  In some cases, fumes generated when baking and drying the above-described coating film of the coating material accumulate in the drying furnace and fall on the coating plate, thereby reducing the finish. Further, when the obtained coated plate is exposed outdoors, there is a problem that the surface of the coated object becomes dirty due to the influence of smoke, dust, iron powder, rain (acid rain), sunlight, and the like.

  For example, Patent Document 1 includes a polyester resin component (A) containing 50 to 100% by mass of a specific fatty acid-modified polyester resin (A1) and a cross-linking agent component containing 50 to 100% by mass of a butyl etherified melamine resin (B1). A coating composition containing (B), an organosilicate component (C) and a surfactant component (D) is disclosed. However, although the coating composition described in Patent Document 1 shows improvement in stain resistance, the amount of fumes generated during baking of the coating film was large.

  Patent Document 2 discloses an anionic antistatic agent selected from sodium alkylsulfonate, sodium dialkylsulfosuccinate, sodium alkylbenzenesulfonate, alkyl phosphate compound, polyalkylene oxide and ammonium sulfate in Examples, and polyester. A coating composition containing a resin, a melamine resin or the like is disclosed. However, the coating film obtained by applying Patent Document 2 has insufficient contamination due to outdoor exposure, particularly contamination due to outdoor exposure over a long period of time.

JP 2014-12748 A Japanese Patent Laying-Open No. 2015-189889

 The problem to be solved by the present invention is that the amount of fume generated during baking can be suppressed, the anti-contamination property can be maintained for a long time when exposed outdoors, and a coating film having good coating film hardness and workability can be formed. It is to provide a coating composition.

  As a result of intensive studies, the present inventors have found a coating composition containing a hydroxyl group-containing resin (a), a crosslinking agent (b), and an alkaline earth metal salt based on a sulfosuccinic acid alkaline metal salt (c). 0.1 to 20 parts by mass of sulfosuccinic acid alkaline earth metal salt-based anionic surfactant (c) with respect to 100 parts by mass of the solid content of the hydroxyl group-containing resin (a) and the crosslinking agent (b) It has been found that the problem can be achieved by the coating composition contained.

That is, the present invention
1. A coating composition containing a hydroxyl group-containing resin (a), a crosslinking agent (b) and a sulfosuccinic acid alkaline earth metal salt anionic surfactant (c), wherein the hydroxyl group-containing resin (a) and a crosslinking agent ( a coating composition containing 0.1 to 20 parts by mass of a sulfosuccinic acid alkaline earth metal salt-based anionic surfactant (c) with respect to a total solid content of 100 parts by mass with b)
2. The coating composition according to item 1, wherein the alkaline earth metal sulfosuccinate metal salt-based surfactant (c) is represented by the following formula (1):

Formula (1)
(R ¹ and R ^{2 in} formula (1) are the same or different and each represents an alkyl group having 1 to 15 carbon atoms, and M ²⁺ is selected from Ca ²⁺ , Mg ²⁺ , Ba ²⁺ , Sr ²⁺ and Zn ^2+. Represents a divalent metal ion)
3. Furthermore, 1 item | term or 2 which contains 0.1-10 mass parts of following anionic surfactant (d) with respect to 100 mass parts of solid content total of hydroxyl-containing resin (a) and a crosslinking agent (b). The coating composition according to Item,
Anionic surfactant (d): alkyldiphenyl ether disulfonate-based anionic surfactant (d1), polyoxyethylene alkyl ether sulfate-based anionic surfactant (d2), alkylbenzene sulfonate-based surfactant 3. At least one anionic surfactant selected from at least one anionic surfactant selected from an anionic surfactant (d3) and a sulfosuccinate-based anionic surfactant (d4) Any one of 1-3 which contains 0.1-20 mass parts of nitrogen atom containing resin (e) of the following characteristics with respect to 100 mass parts of solid content total of hydroxyl-containing resin (a) and a crosslinking agent (b). A coating composition according to claim 1;
Nitrogen atom-containing resin (e): A polymerizable unsaturated monomer having an amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (e11) or a nitrogen atom-containing heterocyclic ring (with respect to the total amount of all the constituent monomers) e12) and at least one nitrogen atom-containing polymerizable unsaturated monomer (e1) selected from N-substituted (meth) acrylamide compound (e13) (e1) of 5 to 70% by mass, and other polymerizable unsaturated compounds 4. Copolymer resin of monomer mixture of 30 to 95% by weight of monomer (e2) A primer coating film is formed on one side or both sides of a metal plate, and a coating film is formed with the coating composition according to any one of items 1 to 4 on at least one side of the primer coating film. Coating film forming method,
It is related with the coating metal plate obtained by the coating-film formation method of 6.5.

The coating composition of the present invention can suppress the amount of fume generation such as silica fume during baking,
In addition, it is possible to maintain stain resistance over a long period of time when exposed outdoors, and to form a coating film with good coating film hardness and workability.

  The coating composition of the present invention can reduce the maintenance of the drying furnace because the amount of fumes generated during baking is small, and can obtain a coated article with excellent finish because there is little dropping of fumes from the ceiling of the drying furnace. it can.

  In addition, the coating composition of the present invention further improves stain resistance by containing other anionic surfactants, nitrogen atom-containing resins, ionic liquids, fluorosurfactants and the like as necessary. Can be achieved.

The model figure of the apparatus which tests the fume generation amount at the time of baking is shown.

  The coating composition of the present invention is a coating composition containing a hydroxyl group-containing resin (a), a crosslinking agent (b) and a sulfosuccinic acid alkaline earth metal salt-based anionic surfactant (c). 0.1-20 parts by mass of the alkaline earth metal salt based on sulfosuccinic acid metal salt is contained with respect to 100 parts by mass of the total solid content of the resin (a) and the crosslinking agent (b). Details will be described below.

Hydroxyl-containing resin (a)
Examples of the hydroxyl group-containing resin (a) include polyester resins, epoxy resins, acrylic resins, acrylic epoxy resins, silicon-modified polyester resins, silicon-modified acrylic resins, acrylic urethane resins, urethane resins, polyvinyl alcohol resins, and polyglycerin resins. Can be mentioned. Among these resins, a hydroxyl group-containing polyester resin is particularly preferable from the viewpoints of coating film hardness and processability.

The hydroxyl group-containing polyester resin can be usually produced by an esterification reaction or a transesterification reaction with the polybasic acid component (a1) and the polyhydric alcohol component (a2). As said polybasic acid component (a1), an alicyclic polybasic acid component, an aliphatic polybasic acid component, an aromatic polybasic acid component, etc. can be used, for example.

  As the alicyclic polybasic acid component, generally, a compound having one or more alicyclic structures (mainly 4 to 6-membered rings) and two or more carboxyl groups in one molecule, an acid anhydride of the compound And an esterified product of the compound. Examples of the alicyclic polybasic acid component include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3- Alicyclic polycarboxylic acids such as methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid An anhydride of these alicyclic polyvalent carboxylic acids; a lower alkyl esterified product of these alicyclic polyvalent carboxylic acids, and the like. An alicyclic polybasic acid component can be used individually or in combination of 2 or more types.

  As the alicyclic polybasic acid component, in particular, 1,2-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic anhydride, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene- 1,2-dicarboxylic acid and 4-cyclohexene-1,2-dicarboxylic anhydride can be preferably used. Among the above, 1,2-cyclohexanedicarboxylic acid and 1,2-cyclohexanedicarboxylic anhydride can be particularly preferably used from the viewpoint of hydrolysis resistance.

  The aliphatic polybasic acid component is generally an aliphatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aliphatic compound, and an esterified product of the aliphatic compound, for example, Aliphatic polycarboxylic acids such as acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, octadecanedioic acid, citric acid; An anhydride of a polyvalent carboxylic acid; a lower alkyl esterified product of these aliphatic polyvalent carboxylic acids. An aliphatic polybasic acid component can be used individually or in combination of 2 or more types.

As the aliphatic polybasic acid component, it is preferable to use a dicarboxylic acid having an alkylene chain having 4 to 18 carbon atoms. Examples of the dicarboxylic acid having an alkylene chain having 4 to 18 carbon atoms include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, and octadecanedioic acid. Among them, adipic acid can be preferably used.
The aromatic polybasic acid component is generally an aromatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aromatic compound and a lower alkyl esterified product of the aromatic compound, For example, aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid; anhydrides of these aromatic polycarboxylic acids And lower alkyl esterified products of these aromatic polycarboxylic acids. An aromatic polybasic acid component can be used individually or in combination of 2 or more types.

  As the polyhydric alcohol component (a2), a polyhydric alcohol having two or more hydroxyl groups in one molecule can be preferably used. Examples of the polyhydric alcohol component (a2) include alicyclic diols, aliphatic diols, aromatic diols and trihydric or higher polyhydric alcohols.

  The alicyclic diol is generally a compound having one or more alicyclic structures (mainly 4- to 6-membered rings) and two hydroxyl groups in one molecule. Examples of the alicyclic diol include dihydric alcohols such as 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, hydrogenated bisphenol A, and hydrogenated bisphenol F; ε-caprolactone and the like in these dihydric alcohols. Examples include polylactone diol to which a lactone compound is added, and these can be used alone or in combination of two or more.

  The aliphatic diol is generally an aliphatic compound having two hydroxyl groups in one molecule. Examples of the aliphatic diol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3 -Butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3 -Pentanediol, 1,6-hexanediol, 1, -Hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol; polyethylene glycol, polypropylene glycol and poly Examples include polyether diol compounds such as butylene glycol, and these can be used alone or in combination of two or more.

  The aromatic diol is generally an aromatic compound having two hydroxyl groups in one molecule. Examples of the aromatic diol include ester diol compounds such as bis (hydroxyethyl) terephthalate; alkylene oxide adducts of bisphenol A and the like, and these can be used alone or in combination of two or more.

  Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol, and mannitol. A trilactone or higher alcohol; a polylactone polyol compound obtained by adding a lactone compound such as ε-caprolactone to the trihydric or higher alcohol; tris (2-hydroxyethyl) isocyanurate, tris (2-hydroxypropyl) isocyanurate, And tris (hydroxyalkyl) isocyanurate such as tris (2-hydroxybutyl) isocyanurate. Of these, trimethylolpropane is particularly preferable.

  The production of the hydroxyl group-containing polyester resin used in the present invention is not particularly limited, and can be performed according to a usual method. For example, the acid component having the polybasic acid component (a1) as an essential component and the polyhydric alcohol component (a2) are reacted in a nitrogen stream at 150 to 250 ° C. for 5 to 10 hours to perform esterification or transesterification. It can manufacture by performing reaction.

  In the esterification reaction or transesterification reaction, the acid component and alcohol component may be added at once, or may be added in several portions. Moreover, after synthesize | combining a carboxyl group-containing polyester resin first, you may esterify some carboxyl groups in this carboxyl group-containing polyester resin using the said alcohol component. Furthermore, after first synthesizing the hydroxyl group-containing polyester resin, the acid anhydride may be reacted to half-esterify the hydroxyl group-containing polyester resin.

In the esterification or transesterification reaction, a catalyst may be used to promote the reaction. As the catalyst, known catalysts such as dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, and tetraisopropyl titanate can be used.
Further, the hydroxyl group-containing polyester resin can be modified with a fatty acid, an oil, a fat, a monoepoxy compound, a monoalcohol compound, a polyisocyanate compound or the like during the preparation of the resin, or after the esterification reaction or the transesterification reaction.

  Examples of the fatty acid include coconut oil fatty acid, cottonseed oil fatty acid, hemp seed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty acid, dehydrated castor Examples include fatty acids such as oil fatty acids and safflower oil fatty acids; lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and the like.

  Examples of the fat include coconut oil, cottonseed oil, hemp seed oil, rice bran oil, fish oil, tall oil, soybean oil, linseed oil, tung oil, rapeseed oil, castor oil, dehydrated castor oil, safflower oil and the like.

Examples of the polyisocyanate compound used for the modification include aliphatic diisocyanate compounds such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, methylcyclohexane. -Aliphatic diisocyanate compounds such as 2,6-diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,3- (isocyanatomethyl) cyclohexane; aromatics such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate Diisocyanate compounds; organic poly- such as tri- or higher polyisocyanates such as lysine triisocyanate Isocyanate itself, or an adduct of each of these organic polyisocyanates with polyhydric alcohol, low molecular weight polyester resin or water, or a cyclized polymer of each of the above organic diisocyanates (for example, isocyanurate), biuret type addition And the like. These can be used alone or in combination of two or more.
The number average molecular weight of the hydroxyl group-containing resin (a) such as a hydroxyl group-containing polyester resin is preferably 2,000 to 30,000, particularly 3,000, from the viewpoints of the finish of the resulting coating film, coating film hardness, and processability. It is preferred to have a number average molecular weight in the range of ~ 25,000.

  In addition, the number average molecular weight in this specification is the value which converted the number average molecular weight measured using the gel permeation chromatograph (GPC) on the basis of the molecular weight of standard polystyrene.

  Specifically, “HLC8120GPC” (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL” and Four “TSKgel G-2000HXL” (trade name, all manufactured by Tosoh Corporation) can be used, and measurement can be performed under conditions of mobile phase tetrahydrofuran, measurement temperature of 40 ° C., flow rate of 1 mL / min, and detector RI. However, the nitrogen atom-containing resin (e) having at least one group selected from an amino group, an ammonium group, and a nitrogen atom-containing heterocyclic ring in the molecule can be obtained by a measurement method described later.

  The hydroxyl value of the hydroxyl group-containing resin (a) such as a hydroxyl group-containing polyester resin is in the range of 10 to 200 mgKOH / g, particularly 60 to 185 mgKOH / g, from the viewpoint of coating film hardness and stain resistance of the resulting coating film. preferable. The acid value of the hydroxyl group-containing resin (a) such as a hydroxyl group-containing polyester resin is 30 mgKOH / g or less, preferably in the range of 1 to 20 mgKOH / g from the viewpoint of processability and the like.

Crosslinking agent (b) The crosslinking agent (b) in the coating composition of the present invention may be used without particular limitation as long as it can react with the hydroxyl group of the hydroxyl group-containing resin (a) by heating to be cured. Examples thereof include melamine resin, benzoguanamine resin, urea resin, and polyisocyanate compound.

  As said melamine resin, a part or all of methylol group of methylolation melamine is C1-C8 monohydric alcohol, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol , Partially etherified or fully etherified melamine resins etherified with i-butyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like.

  Examples of commercially available melamine resins include Cymel 202, Cymel 232, Cymel 235, Cymel 238, Cymel 254, Cymel 266, Cymel 267, Cymel 272, Cymel 285, Cymel 301, Cymel 303, Cymel 325, Cymel 327, and Cymel 350. , Cymel 370, Cymel 701, Cymel 703, Cymel 1141 (manufactured by Nippon Cytec Industries, Inc.), Uban 20SE60 (manufactured by Mitsui Cytec Co., Ltd.), and the like.

  Examples of the benzoguanamine resin include methylolated benzoguanamine resins obtained by reaction of benzoguanamine and aldehyde. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like. In addition, those obtained by etherifying this methylolated benzoguanamine resin with one or more alcohols are also included in the benzoguanamine resin. Examples of the alcohol used for etherification include monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol, and 2-ethylhexanol. . Among these, a benzoguanamine resin obtained by etherifying at least a part of the methylol group of the methylolated benzoguanamine resin with a monohydric alcohol having 1 to 4 carbon atoms is preferable.

  Specific examples of the benzoguanamine resin include, for example, My Coat 102, My Coat 105, My Coat 106 (all of which are manufactured by Mitsui Cytec Co., Ltd.), Nicalac SB-201, Nicalac SB-203, Nicalac SB-301, Nicalac SB. -303, Nicalac SB-401 (all of which are manufactured by Sanwa Chemical Co., Ltd.), etc .; methyl etherified benzoguanamine resins such as Cymel 1123 (manufactured by Mitsui Cytec Co., Ltd.); mixed etherified benzoguanamine resins of ethyl ether; A mixture of methyl ether and butyl ether such as Coat 136 (Mitsui Cytec Co., Ltd.), Nicalac SB-255, Nicalac SB-355, Nicalac BX-37, Nicalac BX-4000 (all of which are manufactured by Sanwa Chemical Co., Ltd.) , And the like butyl etherified benzoguanamine resins such as Mycoat 1128 (manufactured by Mitsui Cytec Ltd.); Le benzoguanamine resin.

  The urea resin is obtained by a condensation reaction of urea and formaldehyde, and can be dissolved or dispersed in a solvent or water.

  Examples of the polyisocyanate compound include compounds having two or more isocyanate groups in one molecule, for example, aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate; tetramethylene diisocyanate, hexamethylene diisocyanate, dimer Aliphatic diisocyanates such as acid diisocyanate and lysine diisocyanate; Alicyclic diisocyanates such as methylene bis (cyclohexyl isocyanate), isophorone diisocyanate, methylcyclohexane diisocyanate, cyclohexane diisocyanate, and cyclopentane diisocyanate; Addendum; this Et polyisocyanate and a low molecular weight or high molecular weight polyol compound (e.g., acrylic polyols, polyester polyols, polyether polyols, etc.) and there may be cited an isocyanate group excess obtained by reacting the free isocyanate group-containing prepolymer.

  Furthermore, as the polyisocyanate compound, the free isocyanate group of the polyisocyanate compound is a phenol compound, oxime compound, active methylene compound, lactam compound, alcohol compound, mercaptan compound, acid amide compound, imide compound, amine compound, imidazole. A blocked polyisocyanate compound blocked with a blocking agent such as a series compound, a urea series compound, a carbamic acid series compound, or an imine series compound can also be used.

  As a mixing ratio of the hydroxyl group-containing resin (a) and the crosslinking agent (b), based on the total solid content of both, the hydroxyl group-containing resin (a) is 60 to 95 parts by mass, preferably 70 to 70 parts by mass. 90 parts by mass and 5 to 40 parts by mass, preferably 10 to 30 parts by mass of the crosslinking agent (b) are preferable from the viewpoint of coating film hardness and workability.

Anionic surfactants based on alkaline earth metal sulfosuccinate (c)
The coating composition of the present invention comprises a sulfosuccinic acid alkaline earth metal salt-based anionic surfactant (c) (hereinafter referred to as a sulfosuccinic acid alkaline earth metal salt-based anionic surfactant (c). abbreviated as c)). As the surfactant (c), for example, a compound represented by the following formula (1) can be used. Among the surfactants (c), an anionic surfactant based on calcium sulfosuccinate is particularly preferable for improving coating stability, processability and stain resistance.

Formula (1)
(R ¹ and R ^{2 in} formula (1) are the same or different and each represents an alkyl group having 1 to 15 carbon atoms, and M ²⁺ is selected from Ca ²⁺ , Mg ²⁺ , Ba ²⁺ , Sr ²⁺ and Zn ^2+. Represents a divalent metal ion)
Examples of the surfactant (c) include the following compounds A to E.

          Compound A

          Compound B

          Compound C

          Compound D

          Compound E

Compound F
In addition, the compounding quantity of surfactant (c) in the coating composition of this invention is surfactant (c) with respect to a solid content total of 100 mass parts of hydroxyl-containing resin (a) and a crosslinking agent (b). 0.1 to 20 parts by mass, preferably 0.1 to 10 parts by mass is desirable for improving the anti-contamination property, particularly the long-term anti-staining property. In addition, said surfactant (c) can be used individually or in mixture of 2 or more types.

Anionic surfactant (d)
Furthermore, the coating composition of this invention can contain an anionic surfactant (d) as needed. Examples of the anionic surfactant (d) include alkyldiphenyl ether disulfonate-based anionic surfactant (d1), polyoxyethylene alkyl ether sulfate-based anionic surfactant (d2), and alkylbenzene. Examples thereof include at least one anionic surfactant selected from a sulfonate-based anionic surfactant (d3) and a sulfosuccinate-based anionic surfactant (d4).

Alkyl diphenyl ether disulfonate anionic surfactant (d1)
The alkyldiphenyl ether disulfonate-based anionic surfactant (d1) (hereinafter sometimes abbreviated as anionic surfactant (d1)) is an alkyl having the structural formula represented by the following general formula (2). A diphenyl ether disulfonic acid or its metal salt can be mentioned. Among these, alkyl diphenyl ether disulfonic acid sodium salt is particularly preferable from the viewpoint of improving stain resistance.

Formula (2)
(R in the formula (2) represents an alkyl group having 1 to 15 carbon atoms, and M ⁺ represents H ⁺ , Na ⁺ , K ⁺ , Li ⁺ , NH ⁴⁺ or an organic ammonium ion)
Examples of commercially available anionic surfactants (d1) include Perex SS-L, Perex SS-H (Kao Corporation), New Coal 261-A, New Coal 271-A (Nippon Emulsifier Co., Ltd.) and the like. It is done.

Polyoxyethylene alkyl ether sulfate anionic surfactant (d2)
As the polyoxyethylene alkyl ether sulfate ester-based anionic surfactant (d2) (hereinafter sometimes abbreviated as anionic surfactant (d2)), a structure represented by the following general formula (3) Mention may be made of the polyoxyethylene alkyl ether sulfates of the formula or their metal salts. Among these, polyoxyethylene alkyl ether sulfate sodium salt is particularly preferable from the viewpoint of improving stain resistance.

Formula (3)
(R in Formula (3) may be a hydrocarbon group having 1 to 50 carbon atoms, n represents 1 to 400, M ⁺ represents H ⁺ , Na ⁺ , K ⁺ , Li ^+. Represents NH ₄ ⁺ or an organic ammonium ion)
Examples of commercially available anionic surfactants (d2) include New Coal 707SN, New Coal 714SF, New Coal 2308SF, New Coal 2360SN,
New Coal 1525-SFC (above, Nippon Emulsifier Co., Ltd.), Latem E-118B, Laterum E-150, Latem WX, Latem PD-140 (above, Kao Corporation) and the like.
Alkylbenzenesulfonate anionic surfactant (d3)
Examples of the alkylbenzene sulfonate-based anionic surfactant (d3) (hereinafter sometimes abbreviated as anionic surfactant (d3)) include alkylbenzenesulfone having the structural formula represented by the following general formula (4). An acid or its metal salt can be mentioned. Among these, alkylbenzenesulfonic acid sodium salt is particularly preferable from the viewpoint of improving the stain resistance.

Formula (4)
(R in Formula (4) represents a hydrocarbon group having 1 to 15 carbon atoms, and M ⁺ represents H ⁺ , Na ⁺ , K ⁺ , Li ⁺ , NH ₄ ⁺ or an organic ammonium ion)
Examples of commercial products of the anionic surfactant (d3) include New Coal 210, New Coal 220-L (Nippon Emulsifier Co., Ltd.), Neoperex G-15, Neoperex G-25 (Kao Co., Ltd.) and the like. It is done.

Sulfosuccinate anionic surfactant (d4)
Examples of the sulfosuccinate anionic surfactant (d4) (hereinafter sometimes abbreviated as anionic surfactant (d4)) include dialkylsulfosuccinic acid having the structural formula represented by the following general formula (5). Or the metal salt can be mentioned.

^R 1, ^{R 2} in the formula (5) (Equation (5) are the same or different and each represents an alkyl group having 1 to 15 carbon atoms, ^{M +} is ^{H +, Na +, K +} , Li +, NH ₄ represents ⁺ or organic ammonium ion)
Specific examples include dialkylsulfosuccinic acid ester salts, sodium dioctylsulfosuccinate, sodium dihexylsulfosuccinate, sodium dicyclohexylsulfosuccinate, sodium diamylsulfosuccinate, sodium diisobutylsulfosuccinate and the like. Among these, a dialkylsulfosuccinic acid sodium salt is particularly preferable from the viewpoint of improving stain resistance.

  Commercially available products of the anionic surfactant (d4) include Perex OT-P, Perex TR, Perex CS, Perex TA (Kao Corporation), New Coal 290-A, New Coal 290-M, New Coal 291- M, New Coal 291-PG, New Coal 291-GL, New Coal 292-PG, New Coal 293 (Nippon Emulsifier Co., Ltd.), Neo Coal SW-C, Neo Coal YSK, Neo Coal P (Daiichi Kogyo Seiyaku Co., Ltd.) It is done.

The alkyldiphenyl ether disulfonate-based anionic surfactant (d1), polyoxyethylene alkyl ether sulfate-based anionic surfactant (d2), alkylbenzenesulfonate-based anionic surfactant ( At least one anionic surfactant selected from d3) and sulfosuccinate-based anionic surfactants (d4) is [anionic surfactant (d1) + Anionic surfactant (d2) + anionic surfactant (d3)] / anionic surfactant (d4) = 20/80 to 75/25 (mass ratio), preferably 44/56 to 70/30 ( The range of (mass ratio) is desirable for obtaining a coating film excellent in stain resistance, coating film hardness, and processability.
In addition, when using anionic surfactant (d), the compounding quantity is 0.1-20 mass with respect to 100 mass parts of solid content total of hydroxyl-containing resin (a) and a crosslinking agent (b). Part, preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight, is preferable in that a coating film excellent in stain resistance, coating film hardness and workability can be obtained. .

Nitrogen-containing resin (e)
Furthermore, the coating composition of this invention can contain nitrogen atom containing resin (e) as needed. Examples of the nitrogen atom-containing resin (e) include resins having nitrogen atom-containing groups such as amino groups, ammonium bases, and amide groups in the molecule, nitrogen atom-containing heterocycles, and the like, for example, epoxy containing nitrogen atoms Examples thereof include resins, modified epoxy resins, acrylic resins, alkyd resins, and polyester resins. Further, the nitrogen atom-containing resin (e) can be used after being neutralized.

  Among the nitrogen atom-containing resins (e), an amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (e11), a polymerizable unsaturated monomer having a nitrogen atom-containing heterocyclic ring (e12), and N-substituted. Copolymerizing a monomer mixture of at least one nitrogen atom-containing polymerizable unsaturated monomer (e1) selected from the (meth) acrylamide compound (e13) which may be added and the other polymerizable unsaturated monomer (e2). The acrylic resin obtained by is preferable for improving the stain resistance.

  Hereinafter, an amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (e11), a polymerizable unsaturated monomer having a nitrogen atom-containing heterocyclic ring (e12), and an N-substituted (meth) acrylamide compound ( At least one nitrogen atom-containing polymerizable unsaturated monomer (e1) selected from e13) may be referred to as “nitrogen atom-containing polymerizable unsaturated monomer (e1)”.

  Examples of the amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (e11) include 2-aminoethyl (meth) acrylate, Nt-butylaminoethyl (meth) acrylate, and N, N-dimethylamino. Ethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl ( Amino group-containing aminoalkyl (meth) acrylate monomers such as (meth) acrylate, N, N-dimethylaminobutyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) Acrylamide, N, N-diethylami Amino group-containing (meth) acrylamide compounds such as ethyl (meth) acrylamide, N, N-dipropylaminoethyl (meth) acrylamide, methacryloyloxyethyltrimethylammonium chloride (acrylic ester DMC, trade name, manufactured by Mitsubishi Rayon Co., Ltd.), etc. Examples include quaternary ammonium base-containing unsaturated monomers.

  As the polymerizable unsaturated monomer (e12) having a nitrogen atom-containing heterocyclic ring, (1) for example, a vinylpyropidone compound such as 1-vinyl-2-pyrrolidone and 1-vinyl-3-pyrrolidone, (2) for example, Vinyl pyridine compounds such as 2-vinyl pyridine, 4-vinyl pyridine, 5-methyl-2-vinyl pyridine, 5-ethyl-2-vinyl pyridine, (3) for example, 1-vinyl imidazole, 1-vinyl-2-methyl Vinyl imidazole compounds such as imidazole, (4) vinyl quinoline compounds such as 2-vinyl quinoline, (5) vinyl piperidine compounds such as 3-vinyl piperidine, N-methyl-3-vinyl piperidine, (6) , Morpholine compounds having a polymerizable unsaturated group such as acryloylmorpholine and methacryloylmorpholine It can be mentioned. Among these polymerizable unsaturated monomers (e12) having a nitrogen atom-containing heterocyclic ring, (1) a vinylpyrrolidone compound (preferably 1-vinyl-2-pyrrolidone etc.), (3) a vinylimidazole compound, (6) polymerization A morpholine compound having a polymerizable unsaturated group is preferred, and (1) a vinylpyrrolidone compound and (6) a morpholine compound having a polymerizable unsaturated group are more preferred.

  The N-substituted (meth) acrylamide compound (e13) is a monomer having no amino group, such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide butyl ether. N-methylol methacrylamide butyl ether, N-ethyl acrylamide, N-ethyl methacrylamide, Nn-propyl acrylamide, Nn-propyl methacrylamide, N-isopropyl acrylamide, N-isopropyl methacrylamide, N-cyclopropyl acrylamide N-cyclopropyl methacrylamide, diacetone acrylamide, diacetone methacrylamide, N-hydroxymethyl acrylamide, N-hydroxymethyl methacryl Mido, N-hydroxyethylacrylamide, N-hydroxyethylmethacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, N-methyl, N -Ethyl acrylamide, N-methyl, N-ethyl methacrylamide, N-methylol acrylamide methyl ether, N-methylol methacrylamide methyl ether, N-methylol acrylamide ethyl ether, N-methylol methacrylamide ethyl ether, N-methylol acrylamide propyl ether N-methylol methacrylamide propyl ether, N-methylol acrylamide butyl ether, N-methylol methacrylamide butyl ether, etc. Can. These monomers can be used alone or in combination of two or more.

  Examples of the other polymerizable unsaturated monomer (e2) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. C2-C8 hydroxyalkyl ester of acrylic acid or methacrylic acid, monoesterified product of polyhydric alcohol such as polyethylene glycol mono (meth) acrylate and acrylic acid or methacrylic acid, polyether polyol such as polybutylene glycol Monoether of a hydroxyl group-containing polymerizable unsaturated monomer such as 2-hydroxyethyl (meth) acrylate; ε-caprolactone-modified vinyl obtained by ring-opening polymerization of ε-caprolactone to 2-hydroxyethyl (meth) acrylate Nil monomer (for example, “Placcel FA-1” “Placcel FA-2” “Placcel FA-3” “Placcel FA-4” “Placcel FA-5” “Placcel FM-1” “Placcel FM-2” “Placcel FM-” 3 ”,“ Placcel FM-4 ”,“ Placcel FM-5 ”(all of which are manufactured by Daicel Chemical Industries, Ltd., trade names)) and the like; for example, methyl (meth) acrylate, ethyl ( (Meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, n-octyl (meth) acrylate, 2- Ethylhexyl (meth) acrylate, decyl (meth) acrylate, undecyl (Meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate “Osaka Organic Chemical Co., Ltd.”, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, di Acrylic ester compound or methacrylic ester compound which may contain a ring structure having 1 to 24 carbon atoms such as cyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, benzyl (meth) acrylate, etc .; styrene, vinyl Aromatic ring-containing vinyl compounds such as toluene and α-methylstyrene; vinyl ester compounds such as vinyl propionate and vinyl acetate; nitrile compounds of acrylonitrile and methacrylonitrile; glycidyl (meth) acrylate , 3,4-epoxycyclohexylmethyl (meth) acrylate, vinylcyclohexene monoepoxide, N-glycidyl acrylamide, allyl glycidyl ether and other epoxy group-containing vinyl compounds; acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, etc. Carboxylic group-containing vinyl compounds; acid anhydride group-containing vinyl compounds such as maleic anhydride, itaconic anhydride, and hymic anhydride. These can be used alone or in combination of two or more.

  The compounding amount of the nitrogen atom-containing polymerizable unsaturated monomer (e1) and the other polymerizable unsaturated monomer (e2) when producing the nitrogen atom-containing resin (e) is the total amount of the nitrogen atom-containing resin (e). Nitrogen atom-containing polymerizable unsaturated monomer (e1): 5 to 70% by mass, preferably 15 to 65% by mass, other polymerizable unsaturated monomer (e2): 30 to 95% by mass with respect to the total amount of monomer components %, Preferably in the range of 35 to 85% by mass is desirable for improving the coating film performance.

  In particular, the amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (e11) is 1 to 30% by mass, preferably 5 to 25% by mass, based on the total amount of all monomers constituting the nitrogen atom-containing resin (e). %, A polymerizable unsaturated monomer having a nitrogen atom-containing heterocyclic ring (e12) 4 to 60% by mass, preferably 10 to 55% by mass, and an N-substituted (meth) acrylamide compound (e13) 0 to 20 % By mass, preferably 0-15% by mass ("0% by mass" means not blended), and other polymerizable unsaturated monomer (e2) 30-95% by mass, preferably 35-85% by mass It is preferable that it is in the range from the viewpoint of the durability of the coating film to stain resistance, the coating film hardness, and the workability.

  As a method for obtaining a nitrogen atom-containing resin (e) by copolymerizing a monomer mixture comprising the nitrogen atom-containing polymerizable unsaturated monomer (e1) and the other polymerizable unsaturated monomer (e2), a radical known per se is used. A polymerization method is preferably used, and a bulk polymerization method, a solution polymerization method, a bulk-suspension two-stage polymerization method in which suspension polymerization is performed after the bulk polymerization, and the like can be used.

  As a method for obtaining the nitrogen atom-containing resin (e), any known method can be used, and the solution polymerization method is particularly preferable. Examples of the method by the solution polymerization method include a method in which the monomer mixture is dissolved or decomposed in an organic solvent and heated in the presence of a polymerization initiator with stirring at a temperature of usually about 80 ° C to 200 ° C. . The reaction time is usually preferably 1 to 10 hours.

  In the production of the nitrogen atom-containing resin (e), as the polymerization initiator, a polymerization initiator generally used in a production method such as an acrylic polymer is used, and the amount thereof is usually a nitrogen atom-containing polymerizable unsaturated monomer. It exists in the range of 0.1-20 mass% with respect to the total amount of (e1) and another polymerizable unsaturated monomer (e2).

    Examples of the polymerization initiator include azo polymerization initiators such as 2,2′-azobisisobutylnitrile, azobis-2-methylbutyronitrile, azobisdivaleronitrile; t-butylperoxyisobutyrate, t -Butylperoxy-2-ethylhexanoate, t-amylperoxy 3,5,5-trimethylhexanoate, t-butylperoxyisopropyl carbonate, 2,2-bis (4,4-di-t-butyl Peroxycyclohexyl) propane and other organic peroxide polymerization initiators.

    Examples of the organic solvent include hydrocarbon solvents such as heptane, toluene, xylene, octane and mineral spirit; 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, cyclohexanone; alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, sec-butanol, isobutanol; n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene Ether solvents such as glycol monoethyl ether; SWAZOL 310, SWAZOL 1000, SWAZOL 15 manufactured by Cosmo Oil Co., Ltd. Aromatic such as 0 petroleum solvents and the like.

    These organic solvents can be used alone or in combination of two or more. At the time of copolymerization, the organic solvent is usually used in a range of 400% by mass or less based on the total amount of the nitrogen atom-containing polymerizable unsaturated monomer (e1) and the other polymerizable unsaturated monomer (e2). Is done.

    In the copolymerization reaction to obtain the nitrogen atom-containing resin (e), the method for adding the monomer component and the polymerization initiator is not particularly limited, but the polymerization initiator is from the initial polymerization stage to the late polymerization stage rather than being charged all at the initial stage of polymerization. It is preferable to divide and drop over the range from the viewpoint of suppressing the formation of defective cross-linked products.

    The nitrogen atom-containing resin (e) obtainable by the copolymerization reaction has a weight average molecular weight of 5,000 to 30,000, more preferably 8,000 to 20,000. It is suitable from the viewpoint of easy handling (resin viscosity not very high), coating film hardness, and workability.

  The weight average molecular weight is when the nitrogen atom-containing resin (e) is a nitrogen atom-containing resin (e) having at least one group selected from an amino group, an ammonium group, and a nitrogen atom-containing heterocyclic ring in the molecule. , "HLC-8120GPC" (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and "TSKgel Super-H3000" and two "TSKgel Super-H2500" (Tosoh) are used as columns. Using a differential refractometer as a detector, tetrahydrofuran (containing 0.5% by mass of triethanolamine), measurement temperature 25 ° C., flow rate It can be determined under the condition of 0.6 mL / min.

    The compounding amount of such a nitrogen atom-containing resin (e) is 0.1 to 20 parts by mass, preferably 2 with respect to 100 parts by mass in total of the solid contents of the hydroxyl group-containing resin (a) and the crosslinking agent (b). It is preferable that the content is ˜16 parts by mass, more preferably 3 to 10 parts by mass because a coating film excellent in contamination resistance, coating film hardness, and workability can be obtained.

Other components The coating composition of this invention can contain a fluorine-type surfactant as another component as needed. Examples of the fluorosurfactant include a fluorosurfactant having a perfluoroalkyl group and / or a perfluoroalkenyl group in the molecule. Examples of the fluorosurfactant include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant.

  Examples of the fluorosurfactant include a sulfonate type containing a perfluoroalkyl group, a carboxylate type containing a perfluoroalkyl group, a sulfonate type containing a perfluoroalkenyl group, and a perfluoroalkenyl. Carboxylate type anionic fluorosurfactant containing a group; Betaine amphoteric fluorosurfactant containing a perfluoroalkyl group; Quaternary ammonium containing a perfluoroalkyl group or a perfluoroalkenyl group Salt-type cationic fluorosurfactants; nonionic fluorosurfactants such as ethylene oxide adducts containing perfluoroalkyl groups, amine oxides containing perfluoroalkyl groups, and oligomers containing perfluoroalkyl groups Agents.

  Among the above-mentioned fluorosurfactants, a quaternary ammonium salt type cationic fluorosurfactant containing a perfluoroalkyl group or a perfluoroalkenyl group is preferred for improving the stain resistance.

  A commercial item can be used as said fluorosurfactant, for example, MEGAFAC F-110, MEGAFACCF-113, MEGAFAC F-120, MEGAFAC F-812, MEGAFAC F-142D, MEGAFAC F-144D, MEGAFAC F-150, MEGAFAC F-171, MEGAFACCF-173, MEGAFAC F-177, MEGAFAC F-183, MEGAFAC F-195, MEGAFAC F-824, MEGAFAC F-833, MEGAFAC F-114, MEGAFAC F-410, MEGAFAC F-493, MEGAFAC F-494, MEGAFAC F-443, MEGAFAC F-444, MEGAFAC F-445, MEGAFAC F-446, MEGAFAC F-4 0, MEGAFAC F-471, MEGAFAC F-474, MEGAFAC F-475, MEGAFAC F-477, MEGAFAC F-478, MEGAFAC F-479, MEGAFAC F-480SF, MEGAFAC F-482, MEGAFAC F-482, MEGAFAC F- 484, MEGAFAC F-486, MEGAFAC F-487, MEGAFAC F-487, MEGAFAC F-172D, MEGAFAC F-178K, MEGAFAC F-178RM, MEGAFAC R-08, MEGAFAC R-30, MEGAFAC F-472SF, MEGAFAC BL- 20, MEGAFAC R-61, MEGAFAC R-90, MEGAFAC ESM-1, MEGAFAC MCF-350SF (or more DIC Corporation, trade name), Aftergent 100, Aftergent 100C, Aftergent 110, Aftergent 150, Aftergent 150CH, Aftergent A, Aftergent 100A-K, Aftergent 300, Aftergent 310, Aftergent 320 , Aftergent 400SW, FTX-400P, Aftergent 251, Aftergent 215M, Aftergent 212MH, Aftergent 250, Aftergent 222F, Aftergent 212D, Aftergent 501L, Aftergent 501N, Aftergent 501K, FTX-218, FTX -209F, FTX-213F, FTX-233F, footage 245F, FTX-208G, FTX-240G, FTX-206D, FTX 220D, FTX-230D, FTX-240D, FTX-207S, FTX-211S, FTX-220S, FTX-230S, FTX-750FM, FTX-730FM, FTX-730FL, FTX-710FS, FTX-710FL, FTX-710FL FTX-750LL, FTX-730LS, FTX-730LM, FTX-730LL, FTX-710LL (manufactured by Neos), BYK-300, BYK-302, BYK-306, BYK-307, BYK-310, BYK-315 BYK-320, BYK-322, BYK-323, BYK-325, BYK-330, BYK-331, BYK-333, BYK-337, BYK-340, BYK-344, BYK-370, BYK-375, BYK -377, B K-350, BYK-352, BYK-354, BYK-355, BYK-356, BYK-358N, BYK-361N, BYK-357, BYK-390, BYK-392, BYK-UV3500, BYK-UV3510, BYK- UV3570, BYK-Silclean 3700 (above, manufactured by Big Chemie Japan, trade name), TEGO Rad2100, TEGO Rad2200N, TEGO Rad2250, TEGO Rad2300 ", TEGO Rad2500, TEGO Rad2600, TEGO Rad2700 (above, trade name, manufactured by TEGO) Is mentioned. The above-mentioned fluorosurfactants can be used alone or in combination of two or more.

  When mix | blending the fluorine-type surfactant in the coating composition of this invention, the compounding quantity is 0.1-0.1 with respect to 100 mass parts of solid content total of hydroxyl-containing resin (a) and a crosslinking agent (b). Containing 10 parts by weight, preferably 0.2 to 5 parts by weight, more preferably 0.3 to 3 parts by weight, can suppress the amount of fume generated during baking, and can be resistant to contamination, coating film hardness, and workability. From the viewpoint of

Moreover, the coating composition of this invention can contain an ionic liquid as another component as needed. The ionic liquid is a liquid compound salt composed only of ions (anions, cations). Examples of the anion component of such an ionic liquid include halide ions, SCN ⁻ , BF ⁴⁻ , ClO ⁴⁻ , PF ^6−, (CF ₃ SO ₂ ) ₂ N ⁻ , and (CF ₃ CF ₂ SO ₂ ). ₂ N ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ COO ⁻ , Ph ₄ B ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , PF ₃ (C ₂ F ₅ ) ₃ ^{— and the} like. Examples of the cation component include ammonium ions. Specifically, as the ionic liquid, for example, an ionic liquid listed in JP 2012-72130 A can be used.

  Examples of commercially available ionic liquids include amino ion AS100, amino ion AS200, amino ion AS300, amino ion AS400 (above, Japan Emulsifier, trade name); Exelcel IL-230 (manufactured by Daiichi Kogyo Seiyaku, trade name) can be mentioned.

  When using an ionic liquid, the compounding quantity is 0.1-20 mass parts with respect to 100 mass parts of solid content total amount of a hydroxyl-containing resin (a) and a crosslinking agent (b), Preferably it is 0.2. 10 to 10 parts by mass, more preferably 0.5 to 6 parts by mass is suitable for improving paint stability and stain resistance.

In addition, the coating composition of the present invention includes, as necessary, a lubricity imparting agent, a pigment, a curing catalyst, a pigment dispersant, an ultraviolet absorber, an ultraviolet stabilizer, an antifoaming agent, a surface conditioner, and a cationic surfactant. Further, known materials conventionally used in coating materials such as matting agents such as resin particles and fine silica powder, and organic solvents can be contained.
As the above-mentioned lubricity-imparting agent, conventionally known lubricants in the paint field can be used as long as they can impart slipperiness to the coating surface without deteriorating the appearance of the coating surface. Examples include polyolefin waxes such as polyethylene wax; polyether-modified silicone oil, higher fatty acid ester-modified silicone oil, modified silicone oil such as higher alkoxy-modified silicone oil; paraffin wax such as microcrystalline wax; montan wax, lanolin wax, carna Examples thereof include fatty acid ester waxes such as uba wax, beeswax and whale wax, and fluorine waxes such as ethylene tetrafluoride.

  Specific examples of the pigment include white pigments such as titanium white and zinc white; blue pigments such as cyanine blue and induslen blue; green pigments such as cyanine green and patina; organic red pigments such as azo and quinacridone. Inorganic red pigments such as Bengala; organic yellow pigments such as benzimidazolone, isoindolinone, isoindoline, and quinophthalone; yellow pigments such as titanium yellow, yellow lead, and yellow iron oxide; carbon black, graphite, pine Color pigments such as black pigments such as smoke; extender pigments such as clay, talc, barita and calcium carbonate; rust preventive pigments such as aluminum tripolyphosphate, zinc molybdate and vanadium pentoxide;

  The cationic surfactant is other than a fluorine-based surfactant and can be appropriately selected according to the purpose. For example, an alkylamine-based cationic surfactant, a quaternary ammonium salt-based cationic interface An active agent etc. are mentioned.

  Specifically, alkylamine cationic surfactants such as coconut amine acetate and stearylamine acetate; lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, distearyldimethylammonium chloride, And quaternary ammonium salt cationic surfactants such as alkylbenzyldimethylammonium chloride.

  Commercially available products of the above-mentioned cationic surfactants include acetamine 24, acetamine 86 (above, manufactured by Kao Corporation, alkylamine cationic surfactant), DISPER BYK-108, DISPER BYK-109, DISPER BYK-116, DISPER BYK-161 (above, manufactured by Big Chemie Japan, alkylamine-based cationic surfactant), coatamine 24P, coatamine 86P conch, coatamine 60W, coatamine 86W, coatamine D86P, sanizole C, sanizole B-50 (above, Kao Co., Ltd., quaternary ammonium salt cationic surfactant), cationogen TML, cationogen TMP, cationogen TMS, cationogen ES-O, cationogen ES-L, cationogen ES-P, cationogen DDM PG, Kachiogen S, Kachiogen BC-50, Kachiogen D2, Kachiogen TBB (manufactured by Dai-ichi Kogyo Seiyaku Co., quaternary ammonium salt type cationic surfactant), and the like.

  The curing catalyst is blended as necessary to promote the reaction between the hydroxyl group-containing resin (a) and the crosslinking agent (b). When the crosslinking agent (b) is an amino resin, A sulfonic acid compound or an amine neutralized product of a sulfonic acid compound is preferably used.

  Representative examples of the sulfonic acid compound include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, and the like. The amine in the amine neutralized product of the sulfonic acid compound may be any of primary amine, secondary amine, and tertiary amine. Among these, the amine neutralized product of p-toluenesulfonic acid and / or the amine neutralized product of dodecylbenzenesulfonic acid is preferable from the viewpoints of coating stability, reaction promoting effect, and obtained coating film properties.

  When the crosslinking agent (b) is a blocked polyisocyanate compound, examples of the curing catalyst include tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanote). And organic metal compounds such as dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, monobutyltin trioctate, lead 2-ethylhexinate and zinc octylate.

  From the viewpoint of coating film hardness, the curing catalyst is 0.1 to 5.0 parts by mass, preferably 0.00 with respect to 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a) and the crosslinking agent (b). 2 to 1.5 parts by weight are suitable.

Examples of the resin particles include powdered products obtained by pulverizing a resin obtained by a condensation reaction between urea and an aldehyde component, and an average particle size of 1 to 10 μm, preferably 2 to 8 μm is suitable. ing. The average particle diameter is a median diameter (d50) value of a volume-based particle size distribution measured by a laser diffraction scattering method using a Microtrac particle size distribution measuring device (trade name “MT3300”, manufactured by Nikkiso Co., Ltd.). As the aldehyde component, formaldehyde, acetaldehyde, crotonaldehyde, benzaldehyde or the like can be used. Among these, when formaldehyde is used, the condensation reaction is easy to proceed, which is convenient.
Examples of the commercially available resin particles include Pergo Pack M3, Pergo Pack M4, Pergo Pack M5 (Lonza Japan Co., Ltd., trade name), SOOFINE JJ POWDER (Hangzhou Seika Kogyo Co., Ltd., trade name), and the like.

  In the coating composition of the present invention, the resin particles blended as necessary can be blended according to the degree of the desired matting coating, when blended, and when blended Is usually 1 to 50 parts by weight, preferably 2 to 30 parts by weight, more preferably 3 to 15 parts by weight, based on 100 parts by weight of the total solid content of the hydroxyl group-containing resin (a) and the crosslinking agent (b). It is desirable that it is in the range of parts by mass from the viewpoint of obtaining paint stability and a matte coating film. In addition, blending the resin particles with the coating composition of the present invention is also desirable for improving stain resistance.

  The coating composition of the present invention comprises a hydroxyl group-containing resin (a), a crosslinking agent (b), a sulfosuccinic acid alkaline earth metal salt-based anionic surfactant (c), and optionally an anionic surfactant ( d), a nitrogen atom-containing resin (e), a fluorosurfactant, an ionic liquid, and the other components can be obtained by uniformly mixing. When applying the coating composition, Ford Cup No. Usually, it is preferable to adjust the solid content concentration within a range of 20 to 60% by mass so that a viscosity within a range of 10 to 100 seconds is obtained at 4 (20 ° C.).

Coating film forming method The coating film forming method of the present invention comprises forming a primer coating film on one side or both sides of a metal plate, and overcoating with the above-described coating composition of the present invention on at least one side of the primer coating film. A film is formed.

  Examples of the metal plate to be coated include cold-rolled steel plate, hot-dip galvanized steel plate, electrogalvanized steel plate, alloy galvanized steel plate (alloy galvanized steel plate such as iron-zinc, aluminum-zinc, nickel-zinc). , Aluminum plate, stainless steel plate, copper plate, copper plated steel plate, tin plated steel plate and the like.

  If the surface of the metal plate to be coated is not contaminated with oil or other contaminants, primer coating may be used as it is, but a known metal surface treatment is applied to improve adhesion to the coating and corrosion resistance. Is desirable. Known metal surface treatment methods include phosphate surface treatment, chromate surface treatment, zirconium surface treatment and the like.

  As a primer paint for forming a primer coating on a metal plate, a known primer paint used in the colored color steel sheet coating field, industrial machine coating field, metal part coating field and the like can be applied. From the viewpoint of environmental protection, it is preferable to use a chromium-free primer coating that does not contain a chromium-based rust preventive component.

  The chrome-free primer coating is appropriately selected depending on the type of metal plate or metal surface treatment, and in particular, epoxy primer coating, polyester primer coating, and modified primer coatings thereof are suitable, and workability is particularly required. Is preferably a polyester primer coating. The primer coating is applied by a known coating method such as roll coating or spray coating so that the dry film thickness is 1 to 30 μm, preferably 2 to 20 μm, and usually at an ambient temperature of 80 to 300 ° C. When coil coating is applied for about 5 seconds to 1 hour, it is preferably cured by heating for 15 seconds to 120 seconds under the condition that the maximum material reaching temperature is 140 to 250 ° C.

  The primer coating film may be a single layer or two layers in which a second primer coating film (intermediate coating film) is formed on the first primer coating film. When the primer film has two layers, the first primer film has an anticorrosion function, and the second primer film (intermediate film) has processability and chipping resistance. The primer coating can also have different functions.

  In the coating film forming method of the present invention, the coating composition of the present invention which is a top coating is applied on at least one side of the primer coating. Examples of the coating method include curtain coating, roll coater coating, dip coating, and spray coating. Usually, the coating is performed so that the dry film thickness is in the range of 5 to 50 μm, preferably 8 to 30 μm.

  When the coating composition of the present invention is applied by coil coating, the coating method is not limited, but curtain coating and roll coater coating are recommended in view of the economics of coil coating. When roll coater coating is applied, the bottom feed method (so-called reverse coating or natural coating) using a normal two-roll system is practically performed, but the uniformity of the coating surface is best. Therefore, a top feed or bottom feed method using three rolls can be performed.

  The method for forming a coating film according to the present invention may include a step of curing the coating film of the coating composition of the present invention obtained in the above step. The conditions for curing the coating film with the coating composition of the present invention are usually about 15 to 30 minutes at a material maximum temperature of 120 to 260 ° C. In the field of pre-coating, which is applied by coil coating or the like, it is usually carried out at a raw material maximum temperature of 160 to 260 ° C. for a baking time of 15 to 90 seconds.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited in any way by the following examples. Hereinafter, both “parts” and “%” are based on mass.

Manufacture of polyester resin solution
Production Example 1 Polyester resin no. Production of one solution
The following “mixture (1)” was charged into a reactor equipped with a thermometer, a stirrer, a heating device and a rectifying tower, the temperature was raised to 160 ° C., and the temperature was gradually raised from 160 ° C. to 230 ° C. over 3 hours. did. Next, after continuing the reaction at 230 ° C. for 30 minutes, the rectifying column is replaced with a water separator, xylene is added to the contents, xylene is also added to the water separator, and water and xylene are azeotropically condensed. After removing water and reacting until the acid value reached 5 mgKOH / g, the reaction mixture was cooled, cyclohexanone was added to the reaction product, and polyester resin No. 5 having a solid content of 55% was added. One solution was obtained. The obtained polyester resin No. 1 had an acid value of 5 mg KOH / g, a hydroxyl value of 72 mg KOH / g, and a number average molecular weight of 3,100.
“Mixture (1)”
Isophthalic acid 0.6 mol Adipic acid 0.3 mol 1,4-cyclohexanedimethanol 0.3 mol Neopentyl glycol 0.6 mol Trimethylolpropane 0.1 mol.

Production Example 2 Polyester Resin No. Production of solution 2 Polyester resin No. 2 was prepared in the same manner as in Production Example 1 except that the contents of Table 1 were used. Two solutions were obtained.

Production Example 3 Polyester Resin No. 3. Production of solution “Mixture (2)” was charged into a reactor equipped with a thermometer, a stirrer, a heating device and a rectifying tower, heated to 160 ° C., and gradually increased from 160 ° C. to 230 ° C. over 3 hours. The temperature rose. Next, after continuing the reaction at 230 ° C. for 30 minutes, the rectifying column is replaced with a water separator, xylene is added to the contents, xylene is also added to the water separator, and water and xylene are azeotropically condensed. Water was removed, the reaction was allowed to proceed until the acid value became 3 mgKOH / g or less, the mixture was cooled, 0.5 mol of hexahydrophthalic anhydride was added at 140 ° C., held at 140 ° C. for 2 hours, and then cooled.
Thereafter, cyclohexanone was added to the reaction product to obtain polyester resin No. 5 having a solid content of 55%. Three solutions were obtained. The obtained resin had an acid value of 33 mgKOH / g, a hydroxyl value of 137 mgKOH / g, and a number average molecular weight of 2,400.
"Mixture (2)"
Hexahydrophthalic anhydride 0.5 mol Isophthalic acid 0.4 mol 3,3-pentanedimethanol 0.2 mol Neopentyl glycol 0.2 mol Trimethylolpropane 0.6 mol

Production and production example 4 of nitrogen atom-containing resin (e) 1 Preparation of solution To a 4 liter flask equipped with a thermometer, reflux condenser and stirrer, 28 parts of Swazol 1000 (Cosmo Oil Co., Ltd., aromatic hydrocarbon organic solvent) and 85 parts of toluene were added. A mixture of 15 parts N, N-dimethylaminoethyl methacrylate, 50 parts 1-vinyl-2-pyrrolidone, 15 parts 2-hydroxyethyl methacrylate, 20 parts 2-ethylhexyl methacrylate and 4 parts azobismethylbutyronitrile, Next, it was made to react at 110 degreeC under nitrogen gas. Next, solid content was adjusted with toluene and nitrogen atom containing resin No. 5 with a solid content of 55 mass%. One solution was obtained.
Nitrogen atom-containing resin no. The solid content of one solution had an amine value of 35 mgKOH / g, a hydroxyl value of 33 mgKOH / g, and a weight average molecular weight of 11,000.

Production Examples 5 to 8 Nitrogen atom-containing resin solution No. 2-No. 5 production
A nitrogen atom-containing resin solution No. 1 was prepared in the same manner as in Production Example 4 except that the monomer mixture having the composition shown in Table 2 was used. 2-No. 5 was obtained.

(Note 3) Acryester DMC78: Mitsubishi Rayon Co., Ltd., trade name, methacryloyloxyethyltrimethylammonium chloride, quaternary ammonium base-containing polymerizable saturated monomer
(Note 4) Plaxel FM-3: Daicel Chemical Industries, Ltd., trade name, ε-caprolactone-modified vinyl monomer of 2-hydroxyethyl methacrylate.

Production Example 1 of Coating Composition 1 manufacture
Polyester resin solution No. obtained in Production Example 1 80 parts (solid content) 1, Cymel 303 (Note 5) 20 parts (solid content), Compound A (Note 7) 8 parts (solid content), Taipei CR-95 (Note 20) 120 parts and dodecylbenzenesulfone An organic solvent (a mixed solvent of cyclohexanone / swazole 1500 = 40/60 (mass ratio)) is added to 0.5 part of an acid, diluted, mixed, and coated with a viscosity of 80 seconds (Ford Cup # 4, 25 ° C.). No. 1 was obtained.

Examples 2-31 Coating composition No. 2-No. 31 production
Except for the contents shown in Tables 3 to 4, the coating composition No. 2-No. 31 was obtained.

Comparative Example 1 Paint composition No. Production of polyester resin No. 32 obtained in Production Example 1 80 parts (solid content) of 1 solution, 20 parts (solid content) of Cymel 303 (Note 5), 8 parts (solid content) of sodium dodecyl sulfate, 120 parts of Type CR-95 (Note 20), 0 parts of dodecylbenzenesulfonic acid .5 parts, an organic solvent (cyclohexanone / swazol 1500, 40/60 mixed solvent) was added to dilute, and the viscosity was 80 seconds (Ford Cup # 4, 25 ° C.). 32 was obtained.

Comparative Examples 2 to 23 Coating composition No. 33-No. 54 production
Except for the contents shown in Table 5, the coating composition No. 33-No. 54 was obtained.

(Note 5) Cymel 303: manufactured by Daicel Ornex Co., Ltd., trade name, methyl etherified melamine resin
(Note 6) Sumijoule BL3175: trade name, methyl ethyl ketone oxime blocked polyisocyanate of isocyanurate type trimer of hexamethylene diisocyanate manufactured by Sumika Bayer Urethane Co., Ltd.

  (Note 7) Compound A:

(Note 8) Compound B:

(Note 9) Compound C:

(Note 10) Compound D:

(Note 11) Compound E:

(Note 12) Compound F:

(Note 13) New Coal 271-A: Nippon Emulsifier Co., Ltd., trade name, alkyldiphenyl ether disulfonic acid anionic surfactant (d1)
(Note 14) New Coal 707SN: manufactured by Nippon Emulsifier Co., Ltd., trade name, polyoxyethylene alkyl ether sulfate-based anionic surfactant (d2)
(Note 15) New Coal 210: Nippon Emulsifier Co., Ltd., trade name, alkylbenzene sulfonate anionic surfactant (d3)
(Note 16) New Coal 290-A: Nippon Emulsifier Co., Ltd., trade name, sulfosuccinic acid anionic surfactant (d4)
(Note 17) Footent 310: manufactured by Neos Co., Ltd., trade name, quaternary ammonium salt type cationic fluorosurfactant containing fluorocarbon group or perfluoroalkenyl group, fluorosurfactant (note 18) ) Footent 501L: Neos Co., Ltd., trade name, carboxylate-type anionic fluorosurfactant having a perfluoroalkenyl group (Note 19) Amino ion AS100: Nihon Emulsifier Co., Ltd., trade name, ionic liquid (Note 20) Taipei CR-95: Ishihara Sangyo Co., Ltd., trade name, titanium white
(Note 21) MKC silicate MS56S: Mitsubishi Chemical Corporation, trade name, methyl esterified silicate which is a condensate of tetramethoxysilane (Note 22) MKC silicate MS58B30: Trade name, tetraalkoxysilane Condensate methyl / butyl mixed esterified silicate (Note 23) SOOFINE JJ POWDER: manufactured by Hangzhou Seika Co., Ltd., trade name, urea resin particles, average particle size 2.5 μm.

Creating test plates
On a zinc-aluminum alloy-plated steel sheet (GL material, sheet thickness 0.35 mm) on which a primer coating film having a dry film thickness of 3 μm was formed, a coating composition No. obtained in the above Examples and Comparative Examples was obtained with a roll coater. 1-No. 54 were each coated to a dry film thickness of 18 μm and baked for 40 seconds under the condition that the maximum material arrival temperature was 220 ° C. to obtain each test plate. Tables 3 to 5 show the results of testing according to the test conditions described below using each test plate.

(Note 24) Fume generation:
Using the test set of the model diagram shown in FIG. 1, fume generated from the painted plate was evaluated by the following process.
Step 1: The test plate (1) is preheated at 140 ° C. for 3 minutes.
Step 2: Next, a preheated test plate (1) is placed on a hot plate (3) that has been set to 230 ° C., and the test plate (1) is mounted with a vacuum (2) for preventing fumes coming out of the painted plate from escaping. Enclose.
Step 3: Place a steel plate (4) on the back plate (2) to collect fumes from the paint plate, and put a 4 liter round can (5) with ice water on the steel plate (4). Put it on and leave it for 40 seconds to cool the generated fumes immediately.
Step 4: The test plate (1) was renewed and the operations of Steps 1 to 3 were repeated 10 times. Thereafter, the steel plate (4) was taken out and the appearance was evaluated according to the following criteria.

◎ shows slight interference of fume on the steel plate (4) but no interference feeling. ○ indicates that the fume adheres to the steel plate (4), but there is no interference, but there is no cloudiness or dirt.
For Δ, fume adheres to the steel plate (4), and a feeling of interference is observed, and cloudiness or dirt is observed.
In x, fume adheres to the steel plate (4), and it is cloudy or the adhesion of spear is remarkably observed.

(Note 25) Initial coating surface appearance:
○ indicates that the paint surface is not abnormal or cloudy, such as repellency, dents, or bumps.
Δ indicates no coating surface abnormality such as repellency, dents, or irregularities, but clouding is observed on the coating surface.
In x, an abnormality in the paint surface such as repellency, dents, or irregularities is observed on the paint surface.

  (Note 26) Pencil hardness: A pencil scratch test specified in JIS K 5600-5-4 (1999) was performed on the coating film of the test plate, and evaluation was performed by tearing the coating film. A higher pencil hardness is preferred.

(Note 27) Outdoor exposure test:
Attach a test piece (test plate cut to a size of 100 x 300 mm) at an angle of 4 degrees from the vertical so that the coating film faces the north side on a mounting table that models the eaves. An exposure test was conducted on the roof of Kansai Paint Co., Ltd. in Tokyo, and the color difference (ΔE) from the initial coated plate was evaluated based on JIS Z8370 in “2 months after the start of exposure” and “24 months after the start of exposure”. It was measured using a multi-light source spectrocolorimeter MSC-5N manufactured by Kikai Co., Ltd. and evaluated according to the following criteria.
◎: △ E is less than 1
○: △ E is 1 or more and less than 2
△ is △ E is 2 or more and less than 5,
×: ΔE is 5 or more.

(Note 28) Workability: In a room at 20 ° C., the test plate was bent 180 degrees with a vise with the coating surface facing outside, and the T number at which no cracking occurred at the bent portion was displayed. The T number is 0T when bending 180 degrees without anything inside the bent part, 1T, 2 when a sheet of the same thickness as the test plate is folded. In the case of a sheet, 2T,... (The same applies hereinafter)... The results were determined by:
◎: No cracking observed in 2T bending
○: cracks are recognized in 2T folding, but cracks are not observed in 4T folding
Δ is cracked in 4T folding, but cracked in 6T folding
In x, cracks are recognized in the 6T bending process.
(Note 29) 60 degree specular gloss: 60 degree specular reflectivity was measured according to the 60 degree specular gloss specified in JIS Z 8741 (1997).

   It is possible to reduce the amount of fumes generated during baking, maintain a stain resistance over a long period of time when exposed outdoors, and provide a coated plate with good workability.

1. Paint plate 2. 2. A way to keep fumes from the paint board from escaping. 3. Hot plate 4. Steel plate for collecting fumes from the painted plate. 4 liter round cans with ice water to cool generated fumes immediately

Claims (6)

A coating composition containing a hydroxyl group-containing resin (a), a crosslinking agent (b) and a sulfosuccinic acid alkaline earth metal salt anionic surfactant (c), wherein the hydroxyl group-containing resin (a) and a crosslinking agent ( The coating composition which contains 0.1-20 mass parts of sulfosuccinic-acid alkaline-earth metal salt type anionic surfactant (c) with respect to 100 mass parts of solid content with b). An alkaline surfactant metal salt of sulfosuccinic acid alkaline earth metal salt (c)
The coating composition of Claim 1 represented by following formula (1).

Formula (1)
(R ¹ and R ^{2 in} formula (1) are the same or different and each represents an alkyl group having 1 to 15 carbon atoms, and M ²⁺ is selected from Ca ²⁺ , Mg ²⁺ , Ba ²⁺ , Sr ²⁺ and Zn ^2+. Represents a divalent metal ion) Furthermore, 0.1-10 mass parts of following anionic surfactant (d) is contained with respect to 100 mass parts of solid content total of hydroxyl-containing resin (a) and a crosslinking agent (b) or 3. The coating composition according to 2.
Anionic surfactant (d): alkyldiphenyl ether disulfonate-based anionic surfactant (d1), polyoxyethylene alkyl ether sulfate-based anionic surfactant (d2), alkylbenzene sulfonate-based surfactant At least one anionic surfactant selected from an anionic surfactant (d3) and a sulfosuccinate-based anionic surfactant (d4) The nitrogen atom-containing resin (e) having the following characteristics is contained in an amount of 0.1 to 20 parts by mass with respect to 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a) and the crosslinking agent (b). The coating composition according to any one of the above.
Nitrogen atom-containing resin (e): A polymerizable unsaturated monomer having an amino group or quaternary ammonium base-containing polymerizable unsaturated monomer (e11) or a nitrogen atom-containing heterocyclic ring (with respect to the total amount of all the constituent monomers) e12) and at least one nitrogen atom-containing polymerizable unsaturated monomer (e1) selected from N-substituted (meth) acrylamide compound (e13) (e1) of 5 to 70% by mass, and other polymerizable unsaturated compounds Monomer (e2) 30-95% by weight of monomer mixture copolymer resin A primer coating film is formed on one side or both sides on a metal plate, and a coating film is formed with the coating composition according to any one of claims 1 to 4 on at least one side of the primer coating film. A method for forming a coating film. A coated metal plate obtained by the coating film forming method according to claim 5.

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