JP6080162B2 - Paint composition - Google Patents

Description

  The present invention relates to a coating composition that has good storage stability, can maintain stain resistance over a long period of time when exposed outdoors, and can form a coating film with good coating film hardness and processability.

  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 paints used outdoors include polyurethane resin paints, fluororesin paints, silicone resin paints, acrylic resin paints, polyester paints, etc., but these paints are exposed outdoors. As a result, there is a drawback that the surface of the coating is easily soiled due to the influence of soot, sand dust, iron powder, rain (acid rain), sunlight, etc., and the stain resistance is lowered.

  Conventionally, a coating composition for a pre-coated steel sheet comprising (A) a polyol resin, (B) an amino resin, (C) an alkoxysilane compound, and (D) a curing catalyst and having excellent resistance to contamination against rainwater and workability is disclosed. (Patent Document 1).

  Also, it contains organosilicate and / or its condensate, boric acid compound, untreated silica fine particles, and colored pigments with respect to 100 parts by mass of the hydroxyl group-containing coating film-forming resin and amino resin crosslinking agent. On the other hand, the coating composition which can form the coating film excellent in stain resistance is disclosed (patent document 2).

  However, in the coating compositions described in Patent Document 1 and Patent Document 2, the alkoxysilane compound or organosilicate in the composition may adversely affect the storage stability of the coating composition. Furthermore, the coating film obtained by applying the coating composition has insufficient durability against contamination. In particular, a semi-gloss coating film to which a matting agent such as silica is added is resistant to contamination due to outdoor exposure. Sexual decline was significant.

JP-A-10-67945 JP 2008-81719 A

  The problem to be solved by the present invention is a coating composition that has good storage stability, can maintain stain resistance over a long period of time when exposed outdoors, and can form a coating film with good coating film hardness and workability. Is to provide.

As a result of intensive studies, the present inventors have found a coating composition containing a resin (a) containing a hydroxyl group and an amino group, a cross-linking agent (b), and an anionic surfactant (c). The problem can be achieved by a coating composition containing 1 to 20 parts by mass of an anionic surfactant (c) with respect to 100 parts by mass of the total solid content of the resin (a) containing a group and the crosslinking agent (b). I found it.
That is, the present invention
“1. A coating composition comprising a resin (a) containing a hydroxyl group and an amino group, a crosslinking agent (b), and an anionic surfactant (c), wherein the resin (a) contains a hydroxyl group and an amino group And a coating composition containing 1 to 20 parts by mass of an anionic surfactant (c) with respect to 100 parts by mass of the total solid content of the crosslinking agent (b),
2. The resin (a) containing a hydroxyl group and an amino group is added in an amount of 60 to 95 parts by mass with respect to the total solid content of the resin (a) containing a hydroxyl group and an amino group and 100 parts by mass of the crosslinking agent (b). ) In a proportion of 5 to 40 parts by mass,
3. The coating composition according to item 1 or 2, wherein the resin (a) containing a hydroxyl group and an amino group is an amino group-containing polyester resin and / or an amino group-containing acrylic resin,
4). The coating composition according to any one of 1 to 3, wherein the anionic surfactant (c) is an alkylsulfosuccinic acid-based anionic surfactant,
5. Any 1 item | term of 1-4 which contains 1-50 mass parts of urea resin particles (d) with respect to 100 mass parts of solid content total of resin (a) containing a hydroxyl group and an amino group, and a crosslinking agent (b). The coating composition according to Item,
6). A primer coating film is formed on one side or both sides of a metal plate, and a coating film is formed from the coating composition according to any one of 1 to 5 on at least one side of the primer coating film. A method of forming a coating film,
The coated metal plate obtained by the method for forming a coating film according to 7.6 ”.

  The present invention is a coating composition having good storage stability, and the coating film obtained by applying the coating composition can maintain stain resistance over a long period of time when exposed outdoors, and further, the coating film hardness Excellent workability.

  The coating composition of the present invention is a coating composition comprising a resin (a) containing a hydroxyl group and an amino group, a cross-linking agent (b), and an anionic surfactant (c), which contains a hydroxyl group and an amino group. It is a coating composition containing an anionic surfactant (c) and, if necessary, urea resin particles (d) with respect to a total solid content of 100 parts by mass of the resin (a) and the crosslinking agent (b). Details will be described below.

[Resin containing hydroxyl group and amino group (a)]
The resin (a) containing a hydroxyl group and an amino group is a resin having an amino group and a hydroxyl group in the molecule. The amino group may be any of primary, secondary and tertiary amino groups. Examples of the resin species include polyester resins, alkyd resins, acrylic resins, polybutadiene resins, and epoxy resins. Among these, it is preferable to use a polyester resin containing a hydroxyl group and an amino group and an acrylic resin containing a hydroxyl group and an amino group from the viewpoints of coating stability, processability, corrosion resistance, and weather resistance.

Polyester resin containing hydroxyl group and amino group The production method of the polyester resin containing hydroxyl group and amino group is not particularly limited. For example, the following method (1), method (2), and method (3) include: Can be mentioned. Hereinafter, the “polyester resin containing a hydroxyl group and an amino group” may be referred to as an “amino group-containing polyester resin”.

  Method (1): By using an amino group-containing compound as part of the acid component (a1) and / or alcohol component (a2), the esterification reaction or transesterification reaction of the acid component (a1) and alcohol component (a2) And a method for obtaining a polyester resin containing a hydroxyl group and an amino group.

  Method (2): A product obtained by reacting a polyester resin obtained by an esterification reaction or an ester exchange reaction with an acid component (a1) and an alcohol component (a2), a polyisocyanate compound and a monohydroxy tertiary amine. To obtain a polyester resin containing a hydroxyl group and an amino group.

  Method (3): The amino group-containing polyester resin comprises an acid component (a1) and an alcohol component (a2) containing at least one acid component selected from the group consisting of maleic anhydride, maleic acid, itaconic acid and itaconic anhydride, and A method for obtaining a polyester resin containing a hydroxyl group and an amino group by a Michael addition reaction between an unsaturated group-containing polyester resin obtained by the esterification reaction of the compound and a primary and / or secondary amino group-containing compound.

Acid component (a1)
As said acid component (a1), the compound normally used as a polybasic acid component at the time of manufacture of a polyester resin can be used, for example, an alicyclic polybasic acid component, an aliphatic polybasic acid component, aromatic A polybasic acid component or the like can be used.

  The alicyclic polybasic acid component generally comprises 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 the compound It is an esterified product of a 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.

  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, succinic acid Aliphatic polycarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, octadecanedioic acid, citric acid; Carboxylic anhydrides; lower alkyl esterified products of these aliphatic polycarboxylic 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 an esterified product of the aromatic compound, for example, phthalic acid , Isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid, and other aromatic polycarboxylic acids; anhydrides of these aromatic polycarboxylic acids; Examples include lower alkyl esterified products of polyvalent carboxylic acids. Also, monocarboxylic acids such as benzoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearyl acid, and dimethylolbutanoic acid can be used.

  In addition, amino group-containing acid compounds such as amino acids such as lysine, glycine and alanine; and aromatic aminocarboxylic acids such as 3-aminophthalic acid, 3-dimethylaminobenzoic acid, 4-methylaminobenzoic acid and 4-aminobenzoic acid Can also be used. These can be used alone or in combination of two or more. By using an amino group-containing acid compound, an amino group can be introduced into the polyester resin.

Alcohol component (a2)
As the alcohol component (a2), a polyhydric alcohol having two or more hydroxyl groups in one molecule can be preferably used. As said polyhydric alcohol, an alicyclic diol, an aliphatic diol, an aromatic diol etc. can be mentioned, for example.

  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, 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 polyhydric alcohol that can be used as the alcohol component (a2) other than the alicyclic diol, aliphatic diol and aromatic diol include, for example, glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2 , 6-hexanetriol, pentaerythritol, dipentaerythritol, tris (2-hydroxyethyl) isocyanurate, sorbitol, mannitol and other trihydric alcohols; lactone compounds such as ε-caprolactone in these trihydric or higher alcohols And a polylactone polyol compound to which is added.

  Examples of the alcohol component (a2) include monoalcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, stearyl alcohol, and 2-phenoxyethanol; glycidyl esters of propylene oxide, butylene oxide, and synthetic highly branched saturated fatty acids (trade names) Alcohol compounds obtained by reacting a monoepoxy compound with an acid such as “Cardura E10” (made by HEXION Specialty Chemicals) can also be used as necessary.

  Examples of the alcohol component (a2) include monoethanolamine, mono (2-hydroxypropyl) amine, monomethylaminoethanol, N- (2-hydroxypropyl) ethylenediamine, N-methylglucamine, and N-octylglucamine. Amino group-containing alcohol compounds such as diethanolamine, di (2-hydroxypropyl) amine, 3-methylamine-1,2-propanediol, 3-tert-butylamino-1,2-propanediol are used as necessary can do. These can be used alone or in combination of two or more. By using an amino group-containing alcohol compound, an amino group can be introduced into the polyester resin.

Production of amino group-containing polyester resin The amino group-containing polyester resin contains the amino group-containing compound (a3) as a part of the acid component (a1) and / or the alcohol component (a2), and the acid component (a1). And the alcohol component (a2) can be produced by an esterification reaction or a transesterification reaction in a nitrogen stream at 150 to 250 ° C. for 5 to 10 hours. ... Method (1)

  Examples of the amino group-containing compound (a3) include the amino group-containing acid compound and the amino group-containing alcohol compound.

  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 a part of carboxyl group in this polyester resin using the said alcohol component. Furthermore, after a polyester resin is first synthesized, an acid anhydride may be reacted to half-esterify the 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.
In addition, the amino group-containing polyester resin can be modified with a fatty acid, an oil or fat, a monoepoxy 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 diisocyanates such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, methylcyclohexane. -Aliphatic diisocyanates such as 2,6-diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,3- (isocyanatomethyl) cyclohexane; aromatics such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate Diisocyanates; organic polyisocyanates such as triisocyanate and higher polyisocyanates such as lysine triisocyanate Itself or an adduct of each of these organic polyisocyanates with a polyhydric alcohol, a low molecular weight polyester resin or water, or a cyclized polymer (for example, isocyanurate) of each of the above organic diisocyanates, a biuret type addition And the like. These can be used alone or in combination of two or more.

  The amino group-containing polyester resin reacts a polyester resin produced by an esterification reaction or a transesterification reaction with the acid component (a1) and the alcohol component (a2), a polyisocyanate compound, and a monohydroxy tertiary amine. An amino group-containing polyester resin can be obtained by reacting with the tertiary amino group-containing polyisocyanate compound thus obtained. ... Method (2)

  The above polyester resin is usually esterified in a suitable organic solvent at a temperature of about 150 to about 250 ° C., preferably about 160 to about 230 ° C. for about 1 to 6 hours, preferably about 1 to 5 hours. Or it can obtain by transesterification.

  Examples of the polyisocyanate compound to be reacted with the monohydroxy tertiary amine include aliphatic diisocyanates such as lysine diisocyanate, hexamethylene diisocyanate and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4- Alicyclic diisocyanates such as diisocyanate, methylcyclohexane-2,6-diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,3- (isocyanatomethyl) cyclohexane; tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate And aromatic diisocyanates. As the monohydroxy tertiary amine, for example, dialkylalkanolamines such as dimethylethanolamine and diethylethanolamine are preferably used. A tertiary amino group-containing polyisocyanate compound can be produced by the reaction of the polyisocyanate compound with a monohydroxy tertiary amine.

  The reaction between the polyisocyanate compound and the monohydroxy tertiary amine is usually performed in a suitable organic solvent at a temperature of about 40 to about 110 ° C., preferably about 50 to about 100 ° C. for about 1 to 6 hours, preferably 2 It can be performed in about 5 hours. The blending ratio of polyisocyanate compound and monohydroxy tertiary amine is polyisocyanate compound / monohydroxy tertiary amine (molar ratio) = 1/1 to 1 / 1.3, preferably 1/1 to 1 / 1.2. This range is also desirable from the viewpoint of paint stability.

The reaction between the polyester resin and the tertiary amino group-containing polyisocyanate compound is usually performed in a suitable organic solvent at a temperature of about 80 to about 200 ° C., preferably about 110 to about 180 ° C. for about 1 to 6 hours, Preferably, it can be obtained by carrying out in about 1 to 5 hours.
The amino group-containing polyester resin is esterified with an acid component (a1) and an alcohol component (a2) containing at least one acid component selected from the group consisting of maleic anhydride, maleic acid, itaconic acid and itaconic anhydride. An amino group-containing polyester resin can be obtained by a Michael addition reaction between the unsaturated group-containing polyester resin obtained by the reaction and a primary and / or secondary amino group-containing compound. ... Method (3)
The unsaturated group-containing polyester resin is usually obtained by esterification or transesterification in a suitable organic solvent at a temperature of about 150 to 250 ° C., preferably about 160 to 230 ° C. for about 1 to 5 hours. Can do.

  The Michael addition reaction between the unsaturated group-containing polyester resin and the primary and / or secondary amino group-containing compound is usually performed in a suitable organic solvent at a temperature of about 40 to 150 ° C. for 1 to 5 hours. By carrying out to the extent, a polyester resin containing a hydroxyl group and an amino group can be obtained.

  Examples of the primary and / or secondary amino group-containing compounds include known compounds such as butylamine, 2-aminoethanol, and diethanolamine. The blending ratio (molar ratio) between the unsaturated group contained in the unsaturated group-containing polyester resin and the primary and / or secondary amino group-containing compound is 2/1 to 0.5 / 1, further 1.3. A range of from / 1 to 0.9 / 1 is preferable from the viewpoint of reducing unreacted primary and / or secondary amino group-containing compounds.

  The amino group-containing polyester resin used in the coating composition of the present invention has an amine value of 1 to 100 mgKOH / g, preferably 5 to 30 mgKOH / g, and a hydroxyl value of 10 to 250 mgKOH / g, preferably 30 to 30 mgKOH / g. It is 200 mgKOH / g, and the number average molecular weight is preferably 1,000 to 20,000, more preferably 2,000 to 8,000 from the viewpoints of storage stability, processability and stain resistance.

  In this specification, the number average molecular weight and the weight average molecular weight are values obtained by converting the number average molecular weight and the weight average molecular weight measured using a gel permeation chromatograph (GPC) based on the molecular weight of standard polystyrene. is there. 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” are used as columns. ”And“ TSKgel G-2000HXL ”(trade names, all manufactured by Tosoh Corporation), and can be measured under the conditions of mobile phase tetrahydrofuran, measurement temperature 40 ° C., flow rate 1 mL / min, and detector RI. it can.

Acrylic resin containing a hydroxyl group and an amino group In the coating composition of the present invention, an acrylic resin containing a hydroxyl group and an amino group can be used according to the required coating film performance. The method for producing an acrylic resin containing a hydroxyl group and an amino group is not particularly limited, and examples thereof include the following methods (1) to (3). Hereinafter, the “acrylic resin containing a hydroxyl group and an amino group” may be referred to as an “amino group-containing acrylic resin”.

  Method (1): A mixture of a hydroxyl group-containing polymerizable unsaturated monomer, an amino group-containing polymerizable unsaturated monomer, and other polymerizable unsaturated monomers is, for example, about 50 ° C. to about 50 ° C. in the presence of an inert gas such as nitrogen. Amino group-containing acrylics are obtained by radical copolymerization in an organic solvent maintained at about 300 ° C., preferably about 60 ° C. to 250 ° C., for about 1 hour to about 24 hours, preferably about 2 hours to about 10 hours. A resin can be obtained.

Method (2): A hydroxyl group-containing polymerizable unsaturated monomer, an epoxy group-containing polymerizable unsaturated monomer, and other polymerizable unsaturated monomers are, for example, about 50 ° C. to about 300 ° C. in the presence of an inert gas such as nitrogen. The acrylic resin is obtained by radical copolymerization in an organic solvent maintained at about 60 ° C., preferably about 60 ° C. to 250 ° C., for about 1 hour to about 24 hours, preferably about 2 hours to about 10 hours. An amino group-containing acrylic resin can be obtained by reacting the epoxy group of the resin with a compound containing a primary or secondary amino group.

  Method (3): The hydroxyl group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers are, for example, about 50 ° C. to about 300 ° C., preferably about 60 ° C. to 250 ° C. in the presence of an inert gas such as nitrogen. An acrylic resin is obtained by radical copolymerization in an organic solvent maintained at a temperature of about 1 hour to about 24 hours, preferably about 2 hours to about 10 hours, and then the polyisocyanate compound is bonded to the hydroxyl group of the acrylic resin. An amino group-containing acrylic resin can be obtained by reacting a product obtained by reacting with a monohydroxy tertiary amine.

  Examples of the hydroxyl group-containing polymerizable unsaturated monomer include, for example, glycols having 2 to 20 carbon atoms such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and (meth) acrylic acid. Monoesterified product, addition product of 2-hydroxyethyl (meth) acrylate and caprolactone (for example, Plaxel FA-2 and FM-3 as trade names manufactured by Daicel Corporation), N-hydroxymethylacrylamide, N-hydroxymethyl Examples include methacrylamide, N-hydroxyethylacrylamide, N-hydroxyethylmethacrylamide N-substituted (meth) acrylamide compounds and the like. These can be used alone or in combination of two or more.

  Examples of the amino group-containing polymerizable unsaturated monomer include aminoethyl (meth) acrylate, Nt-butylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl ( (Meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminobutyl (meth) ) Acrylate, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dipropylaminoethyl (meth) acrylamide Contains amino groups such as ) And an amino group-containing aminoalkyl (meth) acrylate monomers such as acrylamide compound.

  Examples of other polymerizable unsaturated monomers other than the hydroxyl group-containing polymerizable unsaturated monomer and the amino group-containing polymerizable unsaturated monomer include (meth) acrylic acid alkyl esters having 1 to 22 carbon atoms and (meth) acrylic acid. An alkoxyalkyl ester having 2 to 18 carbon atoms, an epoxy group-containing polymerizable unsaturated monomer, a carboxyl group-containing polymerizable unsaturated monomer, a polymerizable unsaturated monomer having a nitrogen atom-containing heterocyclic ring, and optionally N-substituted. A (meth) acrylamide compound, a monomer having an isocyanate group and a polymerizable unsaturated group in one molecule, styrene, α-methylstyrene, vinyltoluene, acrylonitrile, vinyl acetate, vinyl chloride and the like can be used.

Examples of the alkyl ester having 1 to 22 carbon atoms of the (meth) acrylic acid include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, Examples include octyl (meth) acrylate, lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate.
Examples of the alkoxyalkyl ester having 2 to 18 carbon atoms of (meth) acrylic acid include methoxybutyl (meth) acrylate and methoxyethyl (meth) acrylate. Examples of the epoxy group-containing polymerizable unsaturated monomer include glycidyl acrylate and glycidyl methacrylate.

  Examples of the carboxyl group-containing polymerizable unsaturated monomer include acrylic acid, methacrylic acid, maleic acid, itaconic acid, fumaric acid, mesaconic acid, and anhydrides and half-esterified products thereof.

  Examples of the polymerizable unsaturated monomer having a nitrogen atom-containing heterocyclic ring include vinylpyropidone compounds such as 1-vinyl-2-pyrrolidone and 1-vinyl-3-pyrrolidone, 2-vinylpyridine, 4-vinylpyridine, 5 -Vinylpyridine compounds such as methyl-2-vinylpyridine and 5-ethyl-2-vinylpyridine; vinylimidazole compounds such as 1-vinylimidazole and 1-vinyl-2-methylimidazole; vinylquinoline compounds such as 2-vinylquinoline , Vinyl piperidine compounds such as 3-vinylpiperidine and N-methyl-3-vinylpiperidine, morpholine compounds such as acryloylmorpholine and methacryloylmorpholine.

  Examples of the N-substituted (meth) acrylamide compound include acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide butyl ether, N-methylol methacrylamide butyl ether, N-ethyl. Acrylamide, N-ethylmethacrylamide, Nn-propylacrylamide, Nn-propylmethacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, N-cyclopropylacrylamide, N-cyclopropylmethacrylamide, diacetoneacrylamide , Diacetone methacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N Diethyl methacrylamide, 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 Examples thereof include ethyl ether, N-methylol acrylamide propyl ether, N-methylol methacrylamide propyl ether, N-methylol acrylamide butyl ether, N-methylol methacrylamide butyl ether and the like. In addition, the (meth) acrylamide compound which may be N-substituted is a monomer having no amino group. These monomers can be used alone or in combination of two or more. The said other polymerizable unsaturated monomer can be used 1 type or in combination of 2 or more types.

  The amine value of the amino group-containing acrylic resin used in the coating composition of the present invention is 1 to 100 mgKOH / g, preferably 5 to 50 mgKOH / g, and the hydroxyl value is 10 to 250 mgKOH / g, preferably 30 to 200 mgKOH / g. The number average molecular weight is g in the range of 1,000 to 100,000, and preferably in the range of 2,000 to 30,000 from the viewpoint of coating stability and workability.

[Crosslinking agent (b)]
The crosslinking agent (b) in the coating composition of the present invention is not particularly limited as long as it can be cured by heating and reacting with the hydroxyl group in the resin (a) containing a hydroxyl group and an amino group. Melamine resin, benzoguanamine resin, urea resin, blocked polyisocyanate and the like.

  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.], Nicarak SB-201, Nicarac SB-203, Nicarac SB-301, Nicarac SB. -303, Nicalac SB-401 [above, both are manufactured by Sanwa Chemical Co., Ltd.] and other methyl etherified benzoguanamine resins; Cymel 1123 [above, manufactured by Mitsui Cytec Co., Ltd.], etc. Mixed etherified benzoguanamine resins of methyl ether and ethyl ether, etc. Methyl ether and butyl ether such as My Coat 136 [above, manufactured by Mitsui Cytec Co., Ltd.], Nicarak SB-255, Nicarac SB-355, Nicarac BX-37, Nicarac BX-4000 [over all, manufactured by Sanwa Chemical Co., Ltd.] Etherified benzoguanamine resins; Mycoat 1128 [above, Mitsui Cytec] and the like butyl etherified benzoguanamine resins such as.

  The urea resin is obtained by a condensation reaction of urea and formaldehyde, and can be dissolved or dispersed in a solvent or water. The polyisocyanate compound is a compound having two or more isocyanate groups in one molecule. For example, aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate; tetramethylene diisocyanate, hexamethylene diisocyanate, Aliphatic diisocyanates such as dimer acid diisocyanate and lysine diisocyanate; Alicyclic diisocyanates such as methylene bis (cyclohexyl isocyanate), isophorone diisocyanate, methylcyclohexane diisocyanate, cyclohexane diisocyanate and cyclopentane diisocyanate; Type addenda; this Et polyisocyanate and a low molecular weight or high molecular weight polyol compound (e.g., acrylic polyols, polyester polyols, polyether polyols, etc.) and an isocyanate group excess obtained by reacting the free isocyanate group-containing prepolymer can be mentioned a. Furthermore, the free isocyanate groups of these polyisocyanate compounds are converted into phenolic compounds, oxime compounds, active methylene compounds, lactam compounds, alcohol compounds, mercaptan compounds, acid amide compounds, imide compounds, amine compounds, imidazole compounds, urea systems. A blocked polyisocyanate blocked with a blocking agent such as a compound, a carbamic acid compound or an imine compound can also be used.

  In addition, as a mixing ratio of the resin (a) containing a hydroxyl group and an amino group and the crosslinking agent (b), the resin (a) containing a hydroxyl group and an amino group in a solid content based on the total solid content of both of them is 100 parts by mass. 60-95 parts by mass, preferably 70-90 parts by mass, cross-linking agent (b) 5-40 parts by mass, preferably 10-30 parts by mass, are adhering to the base material, curable and workable. From the point of view, it is preferable.

[Anionic surfactant (c)]
In the coating composition of the present invention, the presence of the anionic surfactant (c) can improve the detergency of contaminants adhered to the coating surface. Examples of the anionic surfactant (c) include an anionic surfactant (c1) containing a sulfonic acid group or a sulfonate group, a fatty acid salt type anionic surfactant, and other anionic surfactants. Is mentioned.

  Examples of the anionic surfactant (c1) containing a sulfonic acid group or a sulfonic acid group include a monoalkylsulfosuccinic acid ester salt, a dialkylsulfosuccinic acid ester salt, a sulfosuccinic acid alkyl disalt, a polyoxyethylene alkylsulfosuccinic acid disalt, Sodium alkylamine oxide bistridecyl sulfosuccinate, sodium dioctyl sulfosuccinate, sodium dihexyl sulfosuccinate, sodium dicyclohexylsulfosuccinate, sodium diamylsulfosuccinate, sodium diisobutylsulfosuccinate, disodium isodecylsulfosuccinate, disodium N-octadecylsulfosuccinate amide N- (1,2-dicarboxyethyl) -N-octadecylsulfosuccinic acid amide tetrasodium Anionic surfactants of succinic acid type; for example, alkylbenzene sulfonic acid type anionic surfactants such as sodium dodecylbenzene sulfonate; alkyl diphenyl ether disulfonic acid type anionic surfactants such as sodium dodecyl diphenyl ether disulfonate; Anionic surfactants based on ammonium sulfate ester having a polyoxyalkylene group, such as ammonium oxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether ammonium sulfate, polyoxyethylene polycyclic phenyl ether ammonium sulfate; mono- or didodecyl diphenyl Sodium oxide disulfonate, sodium diisopropylnaphthalenesulfonate, sodium naphthalenesulfonate formalin condensate, alkyl Sulfoacetates, alpha-olefin sulfonate, and the like. These anionic surfactants containing sulfonic acid groups or sulfonic acid groups may be used alone or in combination of two or more.

  Examples of fatty acid salt type anionic surfactants include higher fatty acid potassium salts. Examples of other anionic surfactants include polyoxyalkylene alkyl ether phosphates, special anion-containing types, and polyacrylic acid Na salts. Among the above anionic surfactants (c), an anionic surfactant (c1) preferably containing a sulfonic acid group or a sulfonate group, particularly preferably having the structural formula represented by the following general formula (1) Dialkylsulfosuccinic acid sodium salt is good for improving stain resistance.

Formula (1)
(Wherein R ¹ and R ² are the same or different and each represents an alkyl group having 1 to 15 carbon atoms)
In addition, as a commercial item of sulfosuccinic acid type anionic surfactant (c1), Lapisol A80 (Nippon Yushi Co., Ltd.), AEROSOL TR-70, AEROSOL TR-601, OT-75, AEROSOL OT-100, AEROSOL WA-300, AEROSOL AY-100 (above, Cytec), Perex OT-P, Perex TR, Perex CS, Perex TA (above, manufactured by Kao Corporation); New Call 290-A, New Call 290-M, New Call 291-M, New Coal 291-PG, New Coal 291-GL, New Coal 292-PG, New Coal 293 (above, manufactured by Nippon Emulsifier Co., Ltd.), Neocoal SW-C, Neocoal YSK, Neocole P (above, Daiichi Kogyo) Pharmaceutical Co., Ltd.).

  In addition, the compounding quantity of anionic surfactant (c) is based on 100 mass parts of solid content of resin (a) containing a hydroxyl group and an amino group, and a crosslinking agent (b), and anionic surfactant ( It is preferable that c) is 1 to 20 parts by mass, preferably 2 to 10 parts by mass, because a coating film excellent in stain resistance, coating film hardness, and workability can be obtained.

[Urea resin particles (d)]
The coating composition of the present invention can reduce the gloss of the coating film by blending the urea resin particles (d) as necessary. For example, the 60 ° specular gloss is 1 to 65, preferably 60 °. A matte coating film with a specular gloss of 5 to 55 can be obtained. The urea resin particles (d) are in the form of a powder obtained by pulverizing a resin obtained by a condensation reaction between urea and an aldehyde component, and those having an average particle diameter of 1 to 10 μm, preferably 2 to 8 μm are suitable. . 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 commercially available urea resin particles (d) include Pergo Pack M3, Pergo Pack M4, Pergo Pack M5 (Lonza Japan, trade name), SOOFINE JJ POWDER (Hangzhou Seika Chemicals, trade name), and the like.
The urea resin particles (d) to be blended in the coating composition of the present invention as necessary are blended according to the degree of the desired matte coating film, when the matte coating film is used, and have hydroxyl groups and amino groups. In general, the amount of urea resin particles (d) is 1 to 50 parts by weight, preferably 2 to 30 parts by weight, more preferably 100 parts by weight in total of the solid content of the resin (a) and the crosslinking agent (b). Is preferably in the range of 3 to 15 parts by mass from the viewpoint of obtaining coating stability and a matte coating film.

  In addition, the coating composition of the present invention includes, as necessary, a pigment such as a lubricity imparting agent, a coloring pigment, an extender pigment, a curing catalyst, a pigment dispersant, an ultraviolet absorber, an ultraviolet stabilizer, an antifoaming agent, a surface. Other additives such as paint additives such as regulators, dehydrating agents and surfactants, matting agents such as fine silica powder, organic solvents, and other known materials conventionally used in paints can also be used.

  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 indanthrene 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; inorganic yellow pigments such as titanium yellow, yellow lead and yellow iron oxide; carbon black, graphite, Examples thereof include coloring pigments such as black pigments such as pine smoke; extender pigments such as clay, talc, barita and calcium carbonate; rust preventive pigments such as aluminum tripolyphosphate, zinc molybdate and vanadium pentoxide;

The curing catalyst is blended as necessary in order to promote the reaction between the resin (a) containing a hydroxyl group and an amino group and the crosslinking agent (b), and the crosslinking agent (b) is an amino resin. In some cases, 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), Mention may be made of organometallic compounds such as dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, monobutyltin trioctate, lead 2-ethylhexinate and zinc octylate.
The amount of curing catalyst is 0.1 to 5.0 parts by mass, preferably 0.2 to 0.1 parts by mass with respect to 100 parts by mass of the total solid content of the hydroxyl group- and amino group-containing resin (a) and crosslinking agent (b). 1.5 parts by weight is suitable.

  The coating composition of the present invention comprises a resin (a) containing a hydroxyl group and an amino group, a crosslinking agent (b), an anionic surfactant (c), and, if necessary, urea resin particles (d), the above other These components can be obtained by uniformly mixing.

Coating method of the present invention For coating the coating composition of the present invention, Ford Cup No. It is preferable to adjust so that the viscosity in the range of 10 to 100 seconds is obtained at 4 (20 ° C.). The coating film forming method using the coating composition of the present invention forms a primer coating film on one or both surfaces of a metal plate, and forms a top coating film by the coating composition on at least one surface of the primer coating film. It is characterized by doing.

  Specifically, the metal plate that is the object to be coated is a cold-rolled steel plate, hot-dip galvanized steel plate, electrogalvanized steel plate, alloy galvanized steel plate (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.

  When painting on a metal plate, the metal surface, which is the material to be coated, may be painted as it is if it is not contaminated with oil or other pollutants, but it is well known for improving adhesion and corrosion resistance with the coating film. It is desirable to apply a metal surface treatment. These known surface treatment methods include phosphate surface treatment, chromate surface treatment, zirconium surface treatment and the like.

  As a primer for forming a primer coating film on a metal plate, a known primer used in the colored color steel sheet coating field, the industrial machine coating field, the metal part coating field, or 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 material to be coated and the type of metal surface treatment. Epoxy-based and polyester-based primer coatings and their modified primer coatings are particularly suitable, and workability is particularly required. In this case, a polyester primer paint is suitable. The primer coating is applied by a known coating method such as roll coating or spray coating so that the primer coating thickness is 1 to 30 μm, preferably 2 to 20 μm, and it is usually at an ambient temperature of 80 to 300 ° C. for 5 seconds. When coil coating is applied for about 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.

  The present coating composition in the coating film forming method of the present invention is coated on at least one surface of the primer coating film. Examples of the coating method include curtain coating, roll coater coating, dip coating, and spray coating. Usually, the coating thickness after drying is 5 to 50 μm, preferably 8 to 25 μm. Is done.

  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.

Production and Production Example 1 of Resin (a) Containing Hydroxyl Group and Amino Group Amino group-containing polyester resin No. 1 Production of one solution
By the following steps 1 to 3, the amino group-containing polyester resin No. One solution was prepared.
Step 1: A reactor (1) equipped with a thermometer, a stirrer, a heating device, and a rectifying tower was charged with 1079 parts of isophthalic acid, 407 parts of adipic acid, 315 parts of neopentyl glycol, and 802 parts of trimethylolpropane at 160 ° C. The temperature was raised to 160 ° C. to 230 ° C. over 3 hours. 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 and the water separator, and water and xylene are azeotroped to remove condensed water. And cooled to obtain a polyester resin solution.
Step 2: Charge 69 parts of dimethylethanolamine and 171 parts of isophorone diisocyanate in a reaction apparatus (2) equipped with a thermometer, stirrer, heating device and rectifying tower, and gradually raise the temperature to 90 ° C. and react for 3 hours. Thus, a product mainly composed of a tertiary amino group-containing isocyanate compound was obtained.
Step 3: Next, 240 parts of the product mainly composed of the tertiary amino group-containing isocyanate compound obtained in Step 2 was added to the polyester resin solution obtained in Step 1, and reacted at 160 ° C. for 1 hour, and further cyclohexanone. Was added to adjust the solid content, amino group-containing polyester resin No. 60 having a resin solid content of 60%. One solution was obtained. Amino group-containing polyester resin no. 1 had an amine value of 18 mg KOH / g, a hydroxyl value of 160 mg KOH / g, and a number average molecular weight of 3,000.

Production Example 2 Amino Group-Containing Polyester Resin No. 2-solution production thermometer, stirrer, heating device, and reactor equipped with rectification tower were charged with 1079 parts isophthalic acid, 407 parts adipic acid, 315 parts neopentyl glycol, 802 parts trimethylolpropane, and 60 parts diethanolamine The temperature was raised to 160 ° C., and the temperature was gradually raised from 160 ° C. to 230 ° C. over 3 hours.
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 and the water separator, and water and xylene are azeotroped to remove condensed water. The solid content was adjusted by adding cyclohexanone to obtain an amino group-containing polyester resin No. 60 having a resin solid content of 60%. Two solutions were obtained. Amino group-containing polyester resin no. 2 had an amine value of 13 mg KOH / g, a hydroxyl value of 164 mg KOH / g, and a number average molecular weight of 3,000.

Production Example 3 Production of polyester resin A solution
A reactor equipped with a thermometer, a stirrer, a heating device and a rectifying tower was charged with 1079 parts of isophthalic acid, 407 parts of adipic acid, 466 parts of neopentyl glycol and 802 parts of trimethylolpropane, and the temperature was raised to 160 ° C. The temperature was gradually raised from 160 ° C. to 230 ° C. over 3 hours. Next, after continuing the reaction at 230 ° C. for 30 minutes, the rectifying column was replaced with a water separator, and 124 parts of xylene was added to the contents, and xylene was also added to the water separator to azeotrope water and xylene. The condensed water was removed, the reaction was continued until the acid value reached 10 mgKOH / g, the mixture was cooled, and 855 parts of cyclohexanone was added to the reaction product to obtain a polyester resin A solution having a solid content of 55%. The obtained polyester resin A had an amine value of 0 mgKOH / g, a hydroxyl value of 184 mgKOH / g, and a number average molecular weight of 3,000.

Production Example 4 Production of amino group-containing acrylic resin solution
A reactor equipped with a thermometer, a stirrer, a heating device and a rectifying tower was charged with 246 parts of propylene glycol monomethyl ether and maintained at 110 ° C. after nitrogen substitution. In this, the "monomer mixture" shown below was dripped over 3 hours. One hour after the completion of dropping, a solution prepared by dissolving 5 parts of 2,2′-azobis (2-methylbutyronitrile) in 56 parts of propylene glycol monomethyl ether was added dropwise over 1 hour. After completion of the dropwise addition, this was further maintained at 110 ° C. for 1 hour, and then methyl isobutyl ketone was added to contain an amino group having an amine value of 35 mgKOH / g, a hydroxyl value of 80 mgKOH / g, a number average molecular weight of 16,000, and a resin solid content of 75%. An acrylic resin was obtained.
"Monomer mixture"
Styrene 30 parts methyl methacrylate 6 parts n-butyl acrylate 6 parts 2-ethylhexyl methacrylate 24 parts Plaxel FM-3 (trade name, manufactured by Daicel Chemical Industries) 24 parts N, N-dimethylaminoethyl methacrylate 10 parts.

Example 1 Coating composition no. No. 1 polyester resin No. 1 containing hydroxyl groups and amino groups obtained in Production Example 1. 80 parts (solid content) of 1 solution, 20 parts (solid content) of Cymel 303 (Note 1), 5 parts of New Coal 291-GL (Note 3), 120 parts of Type CR-95 (Note 8), dodecylbenzenesulfonic acid To 0.5 part, an organic solvent (a mixed solvent of cyclohexanone / swazole 1500 = 40/60 (mass ratio)) was added for dilution, and the coating composition No. having a viscosity of 80 seconds (Ford Cup # 4, 25 ° C.) was used. 1 was obtained.

Examples 2-18 Coating composition No. 2-No. A coating composition No. 1 was prepared in the same manner as in Example 1 except that the contents shown in Production Table 1 in Table 18 were used. 2-No. 18 was obtained.

(Note 1) Cymel 303: Nihon Cytec Industries, Ltd., trade name, methyl etherified melamine resin (Note 2) Block polyisocyanate compound A: Oxime blocked product of hexamethylene diisocyanate trimer, solid content 37% by mass, NCO 3.6% content
(Note 3) New Coal 291-GL: Trade name, Nippon Emulsifier Co., Ltd., dialkylsulfosuccinic acid sodium salt of the structural formula represented by the above formula (1) (Note 4) New Coal 292-PG: Trade name, Japan Emulsifier Stock Company, dialkylsulfosuccinic acid sodium salt of the structural formula represented by the above formula (1) (Note 5) New Coal 293: trade name, Nippon Emulsifier Co., Ltd., monoalkylsulfosuccinic acid of the structural formula represented by the following formula (2) Disodium salt

Formula (2)
(R ³ in the formula represents an alkyl group having 1 to 15 carbon atoms)
(Note 6) SOOFINE JJ POWDER: manufactured by Hangzhou Seika Kogyo Co., Ltd., trade name, urea resin particles, average particle size 2.5 μm
(Note 7) Silicia 445: manufactured by Fuji Silysia Chemical Co., Ltd., trade name, silica fine powder, matting agent (Note 8) Type CR-95: trade name, manufactured by Ishihara Sangyo Co., Ltd., titanium white.

Comparative Example 1 Paint composition No. 19
80 parts (solid content) of the polyester resin solution obtained in Production Example 1, 20 parts (solid content) Cymel 303 (Note 1), 120 parts of Type CR-95 (Note 8), 0.5 part of dodecylbenzenesulfonic acid, An organic solvent (mixed solvent of cyclohexanone / swazole 1500, 40/60) was added for dilution, and the coating composition No. having a viscosity of 80 seconds (Ford Cup # 4, 25 ° C.) was used. 19 was obtained.

Comparative Examples 2 to 14 Coating composition No. 20-No. 32
Except for the contents shown in Table 3, the coating composition No. 20-No. 32 was obtained.

(Note 9) Byron KS-1430V: manufactured by Toyobo Co., Ltd., polyester resin, number average molecular weight 12,000, amine value 0 mgKOH / g.

(Note 10) Storage stability: Each coating composition was put into a 500 mL glass container, 400 mL of the coating composition was stored in a temperature-controlled room at 40 ° C., and the state after storage for 90 days was evaluated according to the following criteria.
◎ indicates that when the paint composition is manually stirred with a spatula, it immediately returns to its pre-storage state without any problems.
A mark indicates that the coating composition settles and a cake layer is observed, but returns to the state before storage without agglomeration by stirring for less than 10 minutes (500 rpm using a stirring blade with a diameter of 2 cm).
Δ indicates that the coating composition settles and a cake layer is observed, but stirring for 10 to 60 minutes (diameter 2c
At 500 rpm using a stirring blade of m, the state returns to the state before storage without aggregation.
In x, the coating composition settles and a cake layer is observed, and even if stirring is performed for more than 60 minutes (500 rpm using a stirring blade having a diameter of 2 cm), cohesive solids remain.

Preparation of test plate Zinc-aluminum alloy plated steel plate (G) with a primer coating of 3μm in dry film thickness
L material, plate thickness 0.35 mm) on the coating composition No. obtained in the above examples and comparative examples with a roll coater. 1-No. No. 31 was 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 a test plate. Tables 1 to 3 show the results of testing using each test plate in accordance with the test conditions described below.

(Note 11) Initial appearance of painted surface:
In the case of ○, there are no paint surface abnormalities such as repelling or dents on the paint surface, and no cloudiness is observed.
Δ indicates no coating surface abnormality such as repellency or dent, but clouding is observed on the coating surface.
In x, coating surface abnormalities such as repellency and dents are observed on the coating surface.

  (Note 12) Pencil hardness: The coating film on the test plate was subjected to a pencil scratch test specified in JIS K 5600-5-4 (1999) and evaluated by tearing the coating film. Higher hardness is preferred.

(Note 13) Outdoor exposure test: Using the test plate as an outdoor exposure test piece (100 x 300 mm), the installation table that modeled the eaves is at an angle of 4 degrees from the vertical so that the coating film faces the north side. Attach and conduct an exposure test on the rooftop of Kansai Paint Co., Ltd. in Ota-ku, Tokyo. The color difference (△ E) from the initial coating plate in JIS 2 months after the start of exposure and 12 months after the start of exposure Based on Z8370, it was measured using a multi-light source spectrocolorimeter MSC-5N manufactured by Suga Test Instruments 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 14) Workability: In a room at 20 ° C., the test plate was bent 180 degrees with a vise with the coating surface on the outside, and the degree of cracking was evaluated on the coating film at the bent portion.
◎: 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 15) 60 degree specular gloss:
The 60-degree specular reflectance was measured according to the 60-degree specular gloss specified in JIS Z 8741 (1997).

  It is possible to provide a coating composition that has good storage stability, can maintain stain resistance when exposed outdoors, and can form a coating film with good processability.

Claims (6)

A polyester resin containing a hydroxyl group and an amino group having an amine value of 5 to 30 mgKOH / g, and / or an acrylic resin (a) containing a hydroxyl group and an amino group having an amine value of 5 to 50 mgKOH / g, a crosslinking agent (b ) And an anionic surfactant (c), which is anionic to the total solid content of 100 parts by mass of the resin (a) and the crosslinking agent (b) containing a hydroxyl group and an amino group. A coating composition containing 1 to 20 parts by mass of a surfactant (c). The resin (a) containing a hydroxyl group and an amino group is added in an amount of 60 to 95 parts by mass with respect to the total solid content of the resin (a) containing a hydroxyl group and an amino group and 100 parts by mass of the crosslinking agent (b). The coating composition of Claim 1 which contains 5-40 mass parts. The coating composition according to claim 1 or 2 , wherein the anionic surfactant (c) is an alkylsulfosuccinic acid-based anionic surfactant. Urea resin particles (d), any one of claims 1 to 3 containing 1 to 50 parts by mass relative to the solid content per 100 parts by weight of the resin containing a hydroxyl group and an amino group (a) and the crosslinking agent (b) 2. The coating composition according to item 1. A primer coating film is formed on one surface or both surfaces of a metal plate, and a coating film is formed from the coating composition according to any one of claims 1 to 4 on at least one surface of the primer coating film. A method of forming a coating film characterized by A coated metal sheet having a coating film of the coating composition according to claim 1 .