JPWO2012002095A1 - Anti-stain coating composition with excellent durability - Google Patents

Abstract

The present invention relates to a stain-resistant coating composition that can form a coating film excellent in stain resistance and corrosion resistance retention against rainwater, etc., particularly in a coating film having a luster of less than semi-gloss with a matting agent or the like. It is an object of the present invention to provide a stain-resistant coating composition suitable for forming a top coat film. As an invention for solving such problems, a resin binder containing a polyester resin component containing a specific fatty acid-modified polyester resin and a melamine resin component containing a butyl etherified melamine resin, a specific organosilicate and / or a condensate thereof A coating composition containing the ingredients is provided.

Description

  The present invention relates to a stain-resistant coating composition that can form a coating film having excellent stain resistance retention over time mainly against rainwater and the like, particularly a stain-resistant coating composition suitable for forming a top coating film on a coated metal plate, The present invention relates to a method for forming a coating film excellent in rainwater stain resistance using a stain-resistant coating composition, and a coated metal plate on which a cured coating film is formed from the stain-resistant coating composition.

  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-containing paints, acrylic resin-containing paints, polyester-containing paints, and the like, but these paints are exposed outdoors. As a result, there is a drawback that the surface of the coated material is easily soiled by the influence of dust, iron powder, rain (acid rain), sunlight, and the like, and the appearance of the coating film is deteriorated.

  In order to solve this problem, the applicant of the present invention contains an organic solvent-containing coating composition (1) containing a hydroxyl group-containing fluororesin and an amino resin crosslinking agent as a reaction-curable organic resin, or a hydroxyl group-containing fluororesin and / or a hydroxyl group-containing composition. A paint comprising an organic solvent-containing paint composition (2) containing an acrylic resin and a (blocked) polyisocyanate compound crosslinking agent as a reaction-curable organic resin, and a tetraalkyl silicate and / or a condensate thereof. A top coating composition having excellent stain resistance, characterized in that the contact angle of water on the surface of the coating film after acid treatment with water is 70 degrees or less has been proposed (see Patent Document 1 International Publication WO94). No. 06870).

  However, the top coating composition of Patent Document 1 has insufficient resistance to contamination against rainwater, such as rain streak stains, when used outdoors, and is resistant to rainwater, etc. even in the initial stage of outdoor use. Contamination was not sufficient.

  In addition, as a coating composition for precoated steel sheets excellent in stain resistance, workability and coating film appearance against rain-stain contamination, (A) a polyol resin having a hydroxyl number of 5 to 300 and a number average molecular weight of 500 to 20000, (B) A thermosetting resin composition comprising an amino resin, (C) an alkoxysilane compound, and (D) a curing catalyst has been proposed. However, the coating film obtained from this thermosetting resin composition has good anti-fouling property against long-term rain-stain contamination over time. In the case where a coating film having a gloss less than semi-gloss (60 ° gloss is about 50 or less) by adding an agent or the like, the stain resistance and the corrosion resistance were insufficient.

International Publication WO94 / 06870 JP-A-10-67945

  The present invention relates to a stain-resistant paint composition capable of forming a coating film excellent in stain resistance and corrosion resistance retention against rainwater and the like, and in particular, a stain-resistant paint suitable for forming a top coat film of a glossy coated metal plate having a semi-gloss or less. It is to provide a composition.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a resin containing a polyester resin component containing a specific fatty acid-modified polyester resin and a melamine resin component containing a butyl etherified melamine resin. A coating composition containing a specific organosilicate and / or its condensate component in the binder is particularly resistant to rainwater and the like in a coating film having a gloss less than semi-gloss (60 ° gloss is about 50 or less). The present inventors have found that a coating film excellent in retainability can be formed, and have completed the present invention.

That is, the present invention includes the following inventions:
Item 1, (A) a polyester resin containing 50 to 100% by mass of a fatty acid-modified polyester resin (A1) having a number average molecular weight of 5000 to 30000, a hydroxyl value of 5 to 100 mgKOH / g, and an oil length of 3 to 30% as a solid content. There,
The fatty acid-modified polyester resin (A1)
(A1): a polybasic acid containing an alicyclic polybasic acid (a1-1),
(A2): an alcohol containing a trihydric or higher polyhydric alcohol (a2-1), and (a3): obtained by reaction of a fatty acid,
In the reaction, the content of the alicyclic polybasic acid (a1-1) in the polybasic acid (a1) is within the range of 50 to 100 mol% based on the total amount of the polybasic acid (a1), and the alcohol ( a polyester resin in which the content of the trihydric or higher polyhydric alcohol (a2-1) in a2) is in the range of 10 to 70 mol% based on the total amount of the alcohol (a2);
(B) Melamine resin containing 50-100% by mass of butyl etherified melamine resin (B1) as a solid content; and (C) Organosilicate represented by the following general formula and / or a condensate thereof:
General _{^{formula: (R 1) n -Si- (}} OR 2) 4-n
[Wherein, R ¹ is an alkyl group having 1 to 18 carbon atoms or a phenyl group optionally substituted with an epoxy group or a mercapto group, R ² is an alkyl group having 1 to 6 carbon atoms, and n is 0 or 1. ]
Containing
(C) The antifouling paint composition whose solid content of a component is 0.1-50 mass% on the basis of the solid content total amount of (A) component and (B) component.
Item 2, In the reaction for obtaining the fatty acid-modified polyester resin (A1), the total content of the alicyclic polybasic acid (a1-1) in the polybasic acid component (a1) is the total amount of the polybasic acid component (a1). The contamination-resistant paint composition according to Item 1, which is within a range of 85 to 100 mol% based on
Item 3, based on the total solid content of the polyester resin component (A) and the melamine resin component (B), the polyester resin component (A) is 50 to 90% by mass, and the melamine resin component (B) is solid. Item 3. The antifouling paint composition according to Item 1 or 2 containing 10 to 50% by mass.
Item 4, the alicyclic polybasic acid (a1-1) is 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid 3-methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid and 1,3,5-cyclohexanetricarboxylic acid Any one of Items 1 to 3, which is at least one selected from the group consisting of a carboxylic acid, an anhydride of the alicyclic polyvalent carboxylic acid, and a lower alkyl ester of the alicyclic polyvalent carboxylic acid. The antifouling coating composition according to Item.
Item 5, a trihydric or higher polyhydric alcohol (a2-1) is glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol And a mannitol trihydric or higher alcohol; a polylactone polyol compound obtained by adding a lactone compound to the trihydric or higher alcohol; and at least one selected from the group consisting of tris (hydroxyalkyl) isocyanurate 5. The antifouling paint composition according to any one of 1 to 4.
Item 6, fatty acid (a3) is coconut oil fatty acid, cottonseed oil fatty acid, hempseed 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, Monovalent carboxylic acid of at least one linear hydrocarbon selected from the group consisting of dehydrated castor oil fatty acid, safflower oil fatty acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid Item 6. The antifouling paint composition according to any one of Items 1 to 5, which is an acid.
Item 7. The contamination-resistant paint composition according to any one of Items 1 to 6, further comprising a matting agent (D).
Item 8. The antifouling paint according to Item 7, which contains the matting agent (D) in a solid content of 0.1 to 30% by mass with respect to the total solid content of the polyester resin (A) and the melamine resin (B). Composition.
Item 9. A step of forming a primer coating with a chromium-free primer coating on one or both surfaces of a metal plate, and at least one of the formed primer coatings, any one of Items 1-8 A method of forming a coating film, comprising the step of forming a top coating film with the antifouling paint composition described in 1.
Item 10. A step of forming a primer coating with a chromium-free primer coating on one or both sides of a metal plate, and at least one of the formed primer coatings, any one of Items 1-8 A method for producing a coated metal sheet, comprising a step of forming a top coat film with the antifouling paint composition described in 1.
Item 11. A coated metal sheet obtained by the method according to Item 11, Item 9 or 10.

  The antifouling paint composition of the present invention comprises a resin binder containing a polyester resin component containing a specific fatty acid-modified polyester resin and a melamine resin component containing a butyl etherified melamine resin, a specific organosilicate and / or condensation thereof. A coating composition containing physical components, and this coating composition has excellent anti-contamination property against rainwater and the like particularly in a coating film having a gloss less than semi-gloss (60 ° gloss is about 50 or less). A coating film can be formed.

  In addition, the specific fatty acid-modified polyester resin that is an essential component has 50 mol% or more of the polybasic acid component having an alicyclic polybasic acid, and thus has excellent weather resistance and hydrolysis resistance. The modified part is usually involved in the adsorption of the pigment component used in the antifouling paint composition.

  The reason why the coating film with the stain resistant coating composition of the present invention can form a coating film having excellent anti-staining property against rainwater etc., particularly when the coating film is semi-glossy or glossy. Although it is not clear, I think as follows.

  The fatty acid-modified polyester resin, which is a base resin of the stain-resistant coating composition of the present invention and uses a large amount of an alicyclic polybasic acid as a polybasic acid component, has good weather resistance and hydrolysis resistance, and is further a pigment. Since it also has an adsorbing part (fatty acid-modified part) with the component, it is considered to be advantageous for suppressing deterioration of the pigment component.

  A glossy film that is less than semi-glossy with a matting agent, etc. has a more uneven surface shape, better water wetting, and is exposed to more severe conditions regarding hydrolysis resistance. Therefore, when the conventional polyester paint system is used, the deterioration of the painted surface (choking, etc.) is accelerated, and the appearance is not good.

  The coating film obtained by the stain-resistant coating composition of the present invention has excellent hydrolysis resistance and suppresses deterioration of the pigment component, so that it has superior appearance and stain resistance compared to conventional polyester coating systems. It is considered that the retentivity can be exhibited.

Antifouling paint composition The antifouling paint composition of the present invention comprises the following polyester resin component (A), melamine resin component (B), and organosilicate and / or its condensate component (C). It is.

(A) Polyester resin component In the coating composition of the present invention, the polyester resin component (A) comprises 50 to 50% of the following fatty acid-modified polyester resin (A1) as a solid content with respect to the total solid content of the polyester resin component (A). Contains 100% by mass.

(A1) Fatty acid-modified polyester resin The fatty acid-modified polyester resin (A1), which is an essential component of the polyester resin component (A), is obtained by the reaction of the following polybasic acid component (a1), alcohol component (a2) and fatty acid (a3). It is done.

( A1) Polybasic acid component In the reaction for obtaining the fatty acid-modified polyester resin (A1), the polybasic acid component (a1) contains an alicyclic polybasic acid (a1-1), and a polybasic acid component (a1). The total content of the alicyclic polybasic acid (a1-1) is within the range of 50 to 100 mol% based on the total amount of the polybasic acid component (a1). The total content of the alicyclic polybasic acid (a1-1) is preferably in the range of 70 to 100 mol%, more preferably 85 to 100 mol%.

  The alicyclic polybasic acid (a1-1) is generally a compound having one or more alicyclic structures (for example, 4-6 membered rings) and two or more carboxyl groups in one molecule, the compound Acid anhydrides, esterified products of the compounds, for example, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid , 3-methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, etc. A carboxylic acid anhydride; an anhydride of the alicyclic polyvalent carboxylic acid; a lower alkyl esterified product of the alicyclic polyvalent carboxylic acid (wherein lower alkyl is, for example, carbon The number refers to the 1-5 degree alkyl.), And the like. Among them, 1,2-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic anhydride, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 4- Cyclohexene-1,2-dicarboxylic anhydride can be preferably used.

  Among the above, 1,2-cyclohexanedicarboxylic acid and 1,2-cyclohexanedicarboxylic acid anhydride are particularly preferable from the viewpoint of hydrolysis resistance.

  The said alicyclic polybasic acid (a1-1) can be used individually or in combination of 2 or more types.

  In the reaction for obtaining the fatty acid-modified polyester resin (A1), the polybasic acid component includes an alicyclic polybasic acid (a1-1), an aromatic polybasic acid (a1-2), and an aliphatic polybasic acid. (A1-3) can be included.

  The aromatic polybasic acid (a1-2) 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, aromatic polyvalent carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid; anhydride of the aromatic polyvalent carboxylic acid A lower alkyl esterified product of the aromatic polycarboxylic acid (herein, the lower alkyl refers to an alkyl having about 1 to 5 carbon atoms, for example). The aromatic polybasic acid (a1-2) can be used alone or in combination of two or more.

  The aliphatic polybasic acid (a1-3) 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. Specifically, for example, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, octadecanedioic acid, citric acid, etc. A carboxylic acid; an anhydride of the aliphatic polyvalent carboxylic acid; a lower alkyl esterified product of the aliphatic polyvalent carboxylic acid (herein, the lower alkyl refers to an alkyl having about 1 to 5 carbon atoms, for example). Is mentioned. The above aliphatic polybasic acids can be used alone or in combination of two or more.

  As said aliphatic polybasic acid (a1-3), it is preferable to use the dicarboxylic acid which has a C4-C18 alkyl chain. Examples of the dicarboxylic acid having an alkyl 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.

(A2) Alcohol component In the reaction for obtaining the fatty acid-modified polyester resin (A1), the alcohol component (a2) contains a trihydric or higher polyhydric alcohol (a2-1), and is trivalent in the alcohol component (a2). The total content of the polyhydric alcohol (a2-1) is in the range of 10 to 70 mol% based on the total amount of the alcohol component (a2). The total content of the trihydric or higher polyhydric alcohol (a2-1) is preferably in the range of 20 to 65 mol%, more preferably 30 to 60 mol%.

  Examples of the trihydric or higher polyhydric alcohol (a2-1) include glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, Trivalent or higher alcohols such as sorbitol and mannitol; polylactone polyol compounds obtained by adding a lactone compound such as ε-caprolactone to these trivalent or higher alcohols; tris (2-hydroxyethyl) isocyanurate, tris (2- And tris (hydroxyalkyl) isocyanurate such as hydroxypropyl) isocyanurate and tris (2-hydroxybutyl) isocyanurate.

  Of these, trimethylolpropane is particularly preferred from the viewpoint of increasing the molecular weight of the fatty acid-modified polyester resin (A1) and improving the reactivity of the modification reaction with the fatty acid (a3).

  In the reaction for obtaining the fatty acid-modified polyester resin (A1), the alcohol (a2) component includes a trihydric or higher polyhydric alcohol (a2-1), a dihydric alcohol (a2-2), and a monoalcohol (a2- 3) can be used.

  Examples of the dihydric alcohol (a2-2) include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, and 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-4,3-pentanediol, 3-methyl-1,5 -Pentanediol, 2,2,4-trimethyl-1,3- Nthanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, water Dihydric alcohols such as hydrogenated bisphenol A and hydrogenated bisphenol F; polylactone diols obtained by adding lactone compounds such as ε-caprolactone to these dihydric alcohols; ester diol compounds such as bis (hydroxyethyl) terephthalate; alkylenes of bisphenol A Examples include oxide adducts, polyether diol compounds such as polyethylene glycol, polypropylene glycol, and polybutylene glycol.

  Examples of the monoalcohol (a2-3) 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) Examples thereof include alcohol compounds obtained by reacting a monoepoxy compound such as “Cardura E10” and HEXION Specialty Chemicals) with an acid.

( A3) Fatty acid In the reaction for obtaining the above fatty acid-modified polyester resin (A1), the fatty acid (a3) is a monovalent carboxylic acid of a linear hydrocarbon, such as coconut oil fatty acid, cottonseed oil fatty acid, hemp oil fatty acid, rice bran Fatty acids such as 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 oil fatty acid, safflower oil fatty acid; lauric acid, myristic acid, palmitic acid , Stearic acid, oleic acid, linoleic acid, linolenic acid and the like. The said fatty acid can be used individually or in combination of 2 or more types.

  Of these, those having a low degree of unsaturation, specifically those having an iodine value of 20 or less, particularly 10 or less, are preferred from the viewpoint of weather resistance. The iodine value is a numerical value serving as an index representing the degree of unsaturation of the compound, and is represented by the number of g of iodine absorbed by 100 g of the sample. The measurement can be performed according to the standard of JIS K 5421.

  From the viewpoint of the degree of unsaturation, coconut oil fatty acid, lauric acid, myristic acid, palmitic acid, stearic acid, especially coconut oil fatty acid can be suitably used as the fatty acid (a3).

  The production of the fatty acid-modified polyester resin (A1) is not particularly limited, and can be performed according to a usual method. For example, the polybasic acid component (a1), the alcohol component (a2), and the fatty acid (a3) are reacted at 150 to 250 ° C. for 5 to 10 hours in a nitrogen stream to perform an esterification reaction or a transesterification reaction. A method is mentioned.

  The modification with the fatty acid (a3) is performed simultaneously with the esterification reaction or transesterification reaction of the polybasic acid component (a1) and the alcohol component (a2), or after the esterification reaction or after the transesterification reaction. Can do.

  The polybasic acid component (a1), alcohol component (a2), and fatty acid (a3) may be added at once, or may be added in several portions. Moreover, after synthesize | combining a carboxyl group-containing fatty acid modified polyester resin first, you may esterify this carboxyl group-containing fatty acid modified polyester resin using the said alcohol component (a2). Furthermore, after first synthesizing a hydroxyl group-containing fatty acid-modified polyester resin, the acid anhydride may be reacted to half-esterify the hydroxyl group-containing fatty acid-modified 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 fatty acid-modified polyester resin (A1) can be modified with a monoepoxy compound during the preparation of the resin or after the preparation. As the monoepoxy compound, for example, a glycidyl ester of a synthetic highly branched saturated fatty acid (trade name “Cardura E10”, manufactured by HEXION Specialty Chemicals) can be suitably used.

  The fatty acid-modified polyester resin (A1) may have a number average molecular weight in the range of 5000 to 30000, preferably 7000 to 25000, and more preferably 10000 to 20000, from the viewpoint of processability and smoothness of the resulting coating film. Is preferred.

  The fatty acid-modified polyester resin (A1) generally has a hydroxyl value in the range of 5 to 100 mgKOH / g, preferably 10 to 90 mgKOH / g, more preferably, from the viewpoint of curability of the resulting coating film. Preferably has a hydroxyl value in the range of 40-80 mg KOH / g.

  The fatty acid-modified polyester resin (A1) has an oil length in the range of 3 to 30%, preferably an oil length in the range of 5 to 20%, from the viewpoint of the weather resistance of the resulting coating film. It is preferable to have Here, the oil length is mass% of the fatty acid component (a3) with respect to the total amount of the polybasic acid component (a1), the alcohol component (a2) and the fatty acid component (a3) which are constituent components.

  In addition, the fatty acid-modified polyester resin (A1) preferably has a glass transition temperature in the range of 0 to 50 ° C., preferably 10 to 40 ° C., from the viewpoint of the hardness and workability of the resulting coating film. .

  The adjustment of the number average molecular weight and the hydroxyl value of the fatty acid-modified polyester resin (A1) is, for example, equivalent of the carboxyl group in the polybasic acid component (a1) and the fatty acid component (a3) and the hydroxyl group in the alcohol component (a2). The ratio (COOH / OH) can be adjusted, or the reaction time in the esterification reaction or transesterification reaction can be adjusted.

  The equivalent ratio (COOH / OH) of the carboxyl group in the polybasic acid component (a1) and the hydroxyl group in the alcohol component (a2) is generally 0.5 to 0.98, preferably 0.6 to It is preferable to be within the range of 0.95.

In addition, the number average molecular weight and the weight average molecular weight in this specification are based on the number average molecular weight and the weight average molecular weight measured by gel permeation chromatograph (manufactured by Tosoh Corporation, “HLC8120GPC”) based on the molecular weight of standard polystyrene. This is the converted value. In this measurement, the columns are “TSK-gel G4000H _XL ”, “TSK-gel G3000H _XL ”, “TSK-gel G2500H _XL ”, “TSK-gel G2000H _XL ” (both trade names, manufactured by Tosoh Corporation). The measurement conditions of mobile phase tetrahydrofuran, measurement temperature 40 ° C., flow rate 1 mL / min, detector RI were used.

  Moreover, in this specification, glass transition temperature (Tg) is based on a differential thermal analysis (DSC).

  As the polyester resin component (A), in addition to the fatty acid-modified polyester resin (A1), a normal oil-free polyester resin (A2) that is not modified with a normal fatty acid can be included.

  The oil-free polyester resin (A2) is a polyester resin obtained by an esterification reaction or a transesterification reaction of the polybasic acid component (a1) and the alcohol component (a2) by a conventional method, and the polybasic acid component (a1) and As an alcohol component (a2), it can manufacture in the same way as the method illustrated by the said fatty acid modified polyester resin (A1), using what was illustrated by the said fatty acid modified polyester resin (A1).

  In this invention, solid content of fatty-acid modified polyester resin (A1) is 50-100 mass% with respect to solid content total amount of a polyester resin component (A). In particular, from the viewpoint of weather resistance and corrosion resistance retention of the obtained coating film, it is preferably in the range of 60 to 100% by mass, more preferably 70 to 100% by mass.

(B) Melamine resin component
In the coating composition of the present invention, the melamine resin component (B) contains the following butyl etherified melamine resin (B1) in a solid content of 50 to 100% by mass with respect to the total solid content of the melamine resin component (B). .

(B1) Butyletherified melamine resin A butyletherified melamine resin is a methylolated melamine resin that is an addition reaction product (either a monomer or a multimer) of melamine and an aldehyde component such as formaldehyde or paraformaldehyde. It is a melamine resin obtained by etherifying a part or all of the methylol groups therein with n-butyl alcohol or isobutyl alcohol. Here, the butyl etherified melamine resin includes a melamine resin obtained by etherifying some or all of the methylol groups in the methylolated melamine resin with n-butyl alcohol, a melamine resin etherified with isobutyl alcohol, n-butyl alcohol, and Any melamine resin etherified with isobutyl alcohol is included. The number average molecular weight of the butyl etherified melamine resin is preferably in the range of 800 to 8000, more preferably in the range of 1000 to 5000, from the viewpoint of the processability of the obtained coating film and the stain resistance. The butyl etherified melamine resin (B1) can be used alone or as a mixture of two or more.

  Commercially available products of butyl etherified melamine resin (B1) include, for example, Uban 20SE, Uban 225 (all of which are manufactured by Mitsui Chemicals, Inc.), Super Becamine J820-60, Super Becamine L-117-60, Super Examples include Becamine L-109-65, Super Becamine 47-508-60, Super Becamine L-118-60, Super Becamine G821-60 (all of which are manufactured by DIC Corporation).

  As a melamine resin component (B), melamine resins (melamine resin (B2)) other than the said butyl etherified melamine resin (B1) can be included.

  Specifically, for example, a methylol group in a methylolated melamine resin, which is an addition reaction product of melamine and an aldehyde component such as formaldehyde or paraformaldehyde (which may be either a monomer or a multimer). A part or all of the melamine resin, n-butyl alcohol and / or isobutyl alcohol etherified with one or more alcohols other than n-butyl alcohol and isobutyl alcohol, and other than n-butyl alcohol and isobutyl alcohol Mention may be made of melamine resins etherified with one or more alcohols. Examples of alcohols other than n-butyl alcohol and isobutyl alcohol used for etherification include monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, 2-ethylbutanol and 2-ethylhexanol. Can do. Specific examples of the melamine resin (B2) include melamine resin etherified with methyl alcohol (methyl etherified melamine resin), melamine resin etherified with methyl alcohol and butyl alcohol (methyl / butyl mixed etherified melamine resin), and the like. It is done.

  Examples of the melamine resin etherified with methyl alcohol include Sumimar M-100, Sumimar M-40S, Sumimar M-55 (all trade names, manufactured by Sumitomo Chemical Co., Ltd.), Cymel 300, Cymel 303, Cymel 325, Cymel 327, Cymel 350, Cymel 370, Cymel 730, Cymel 736, Cymel 738 (all are trade names manufactured by Nippon Cytec Industries, Inc.), Mellan 522, Mellan 523 (all are Hitachi Chemical Industries, Ltd.) Co., Ltd., trade name), Nicarak MS17, Nicarak MS15, Nicarak MS001, Nicarak MX430, Nicarak MX650 (all are Sanwa Chemical Co., Ltd., trade name), Resimin 740, Resimin 741, Resimin 747 (all above, all Monsanto Ltd., methyl etherified melamine resins trade name).

  Examples of the melamine resin etherified with methyl alcohol and butyl alcohol include Cymel 232, Cymel 235, Cymel 202, Cymel 238, Cymel 254, Cymel 266, Cymel 272, Cymel 1130, Cymel XV-514, Cymel XV805 (all Methyl / butyl mixed etherification such as Nippon Cytec Industries Co., Ltd. (trade name), Sumimar M66B (Sumitomo Chemical Co., Ltd., trade name), Resimin 753, Resimin 755 (all of which are manufactured by Monsanto) Mention may be made of melamine resins.

  In this invention, solid content of a butyl etherified melamine resin (B1) is 50-100 mass% with respect to solid content total amount of a melamine resin component (B). In particular, from the viewpoint of workability of the obtained coating film and retention of stain resistance, it is preferably in the range of 70 to 100% by mass, more preferably 80 to 100% by mass.

  The butyl etherified melamine resin (B1) has a lower polarity than the methyl etherified melamine resin, methyl / butyl mixed etherified melamine resin, and the like, and has good compatibility with the polyester resin (A) as the base resin. Therefore, the coating film obtained from the antifouling paint composition containing the butyl etherified melamine resin (B1) has excellent uniformity of crosslinking.

  The butyl etherified melamine resin (B1) is less likely to be localized on the surface layer in the coating film than the methyl etherified melamine resin and the methyl / butyl mixed etherified melamine resin. Therefore, the coating film obtained from the stain-resistant coating composition containing the butyl etherified melamine resin (B1) has excellent weather resistance.

  Moreover, in order to accelerate | stimulate the hardening reaction of a polyester resin component (A) and a melamine resin component (B), a curing catalyst can be used as needed. As the curing catalyst for promoting the curing reaction, a sulfonic acid compound or a neutralized product of a sulfonic acid compound can be generally used.

  Examples of the sulfonic acid compound include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, and the like. Examples of the neutralizing agent in the neutralized product of the sulfonic acid compound include basic compounds such as primary amine, secondary amine, tertiary amine, ammonia, caustic soda, and caustic potash.

  In the stain resistant paint composition of the present invention, the solid content ratio of the polyester resin component (A) and the melamine resin component (B) is based on the total solid content of the polyester resin component (A) and the melamine resin component (B). The polyester resin component (A) is 50 to 90% by mass and the melamine resin component (B) is 10 to 50% by mass. In particular, the polyester resin component (A) is 60 to 80% by mass and the melamine resin component (B) is 20 to 40% by mass, so that the resulting coating film has curability, stain resistance, mechanical strength, and workability. From the viewpoints of solvent resistance, corrosion resistance, weather resistance and the like.

(C) Organosilicate and / or its condensate component (C) component of the present invention,
General _{^{formula: (R 1) n -Si- (}} OR 2) 4-n
[Wherein, R ¹ is an alkyl group having 1 to 18 carbon atoms or a phenyl group optionally substituted with an epoxy group or a mercapto group, R ² is an alkyl group having 1 to 6 carbon atoms, and n is 0 or 1. ]
It is the organosilicate represented by these, and / or its condensate.

  Component (C) contained in the coating composition of the present invention is used for the coating film to exhibit a hydrophilic effect on the surface of the substrate efficiently after coating. From the viewpoint of this effect, the above organosilicate is used. The condensate is more preferred.

Specific examples of R ¹ in the above general formula include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, pentyl, hexyl, heptyl, n-octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, Examples include tetradecyl, hexadecyl, octadecyl, glycidyl, methylglycidyl (2-methylglycidyl), mercaptomethyl, 2-mercaptoethyl, 2-mercaptopropyl, 3-mercaptopropyl, 4-mercaptobutyl, phenyl, p-mercaptophenyl groups, etc. be able to.

  Specific examples of the organosilicate of component (C) include tetrafunctional silanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraisobutoxysilane; methyltrimethoxysilane, methyl Triethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, methyltri-n-butoxysilane, methyltriisobutoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, phenyltriisopropoxysilane, phenyltri n-butoxysilane, phenyltriisobutoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, lauryltrimethoxysilane, lauryltrieth Shishiran, mercaptomethyl trimethoxysilane, mercaptoethyl trimethoxy silane, mercaptomethyl triethoxysilane, mercaptopropyl triethoxysilane, mercaptopropyl trimethoxysilane, include trifunctional silanes such as mercaptopropyltriethoxysilane. Examples of the condensate of the organosilicate include a condensate of one or a combination of two or more of these tetrafunctional or trifunctional silanes.

  The organosilicate condensate can be produced by a conventional method. Examples of commercially available products include MKC silicate MS51, MS56, MS57, MS56S, MS56SB5, MS58B15, MS58B30, ES40, EMS31, BTS (all of which are Mitsubishi). Chemical Co., Ltd., trade name), methyl silicate 51, ethyl silicate 40, ethyl silicate 40T, ethyl silicate 48 (all are trade names, manufactured by Colcoat Co., Ltd.), KR500, KR9218, X-41-1805, X-41-1810, X-41-1818, X-41-1053, X-41-1056 (all are trade names manufactured by Shin-Etsu Chemical Co., Ltd.) and the like. Further, these organosilicate condensates can be obtained by single hydrolysis or by partial hydrolysis condensation using a combination of two or more. The organosilicate condensate is a branched or linear condensate, and the degree of condensation is preferably 2 to 100, and preferably 2 to 20. In the coating composition of the present invention, the (C) component organosilicate or organosilicate condensate may be used alone or in combination of two or more.

In the organosilicate and / or condensate thereof represented by the above general formula, the OR ² group has a methoxy group and an alkoxy group having 2 to 6 carbon atoms, and a methoxy group / an alkoxy group having 2 to 6 carbon atoms; It is preferable from the viewpoint of the pot life after the preparation of the paint that the ratio of the number is in the range of 95/5 to 30/70.

  In the coating composition of the present invention, the solid content of the component (C) is 0.1 to 50% by mass, preferably 0, based on the total solid content of the component (A) and the component (B). It is 5-30 mass%, More preferably, it is 1-20 mass%.

  When the amount of the component (C) is within the above range, the effect of containing the component (C) is more exhibited, and the initial stain resistance of the resulting coating film, the retention of stain resistance, and the coating obtained It is also suitable from the viewpoint of mechanical strength and durability of the film.

  In the coating composition of the present invention, in addition to the components (A), (B) and (C) described above, hydrolysis accelerators such as acidic surfactants and boric acid compounds, colored pigments, silica fine particles, etc. Extender pigments, organic resin powders, inorganic aggregates, pigment dispersants, UV absorbers, UV stabilizers, antifoaming agents, surface conditioners and other paint additives, solvents and other known materials conventionally used in paints Can also be included.

  The acidic surfactant and boric acid compound have the action of promoting hydrolysis of the organosilicate and / or the condensate component (C) thereof. Hydrolysis accelerators such as surfactants and boric acid compounds that exhibit acidity can be used from the viewpoint of improving stain resistance, although the pot life of the coating composition of the present invention is shortened when used in combination.

  Examples of the surfactant exhibiting acidity include phosphate ester salts such as polyoxyethylene phosphate ester and alkyl phosphate ester salt; for example, alkyl or alkylbenzene sulfonate salts such as sodium lauryl sulfonate and sodium dodecylbenzene sulfonate, Alkyl naphthalene sulfonates such as sodium isopropyl naphthalene sulfonate, sulfonates such as alkyl diphenyl ether sulfonate; sulfate esters such as alkyl or alkyl benzene sulfate, (poly) oxyethylene alkyl phenyl ether sulfate; eg alkyl sulfosuccinic acid A surfactant such as a carboxylate such as a salt may be used. Examples of the boric acid compound include trialkyl borate such as trimethyl borate, triethyl borate, tributyl borate; boric acid and the like. The solid content of these hydrolysis accelerators is 30% by mass or less, particularly 0.5 to 20% by mass, more particularly 1 to 4%, based on the total solid content of the components (A) and (B). It is preferable that it is 10 mass%.

  Examples of the extender pigment include silica fine particles, talc, mica powder, and barita. The solid content of the extender pigment is 0.1 to 20% by mass, particularly 0.5 to 15% by mass, more particularly 1 to 10% by mass, based on the total solid content of the components (A) and (B). It is preferable that

  Further, the coating composition of the present invention may contain a matting agent (D) for the purpose of adjusting the gloss so that the resulting coating film has a finished appearance such as matte or semi-gloss. The matting agent (D) is used to reduce the gloss of the resulting coating film, and may be either an organic matting agent or an inorganic matting agent. Moreover, these can be used individually or in combination of 2 or more types.

  The stain resistant paint composition of the present invention can form a paint film having excellent finish of stain resistance and corrosion resistance, in particular, in a paint film having a finished appearance with reduced gloss such as matte and semi-gloss. .

  Examples of the organic matting agent include organic resin fine particles that are not completely melted by baking at the time of coating film formation. The organic resin fine particles usually have an average particle diameter of 3 to 80 μm, preferably 5 to 60 μm, from the viewpoint of coating film appearance, coating workability, and the like. Examples of organic matting agents include fluorine resins such as polyvinylidene fluoride and polytetrafluoroethylene, polyamides, acrylic resins, polyurethanes, phenol resins, silicone resins, polypropylene, and polyamides such as nylon 11 and nylon 12. be able to.

  Examples of the inorganic matting agent include silica, mica, alumina, talc, clay, calcium carbonate, barium sulfate and the like.

  The said matting agent (D) can be used individually or in combination of 2 or more types. Matting agent (D) Solid content is 0.1-30 mass% with respect to the solid content total amount of said (A) component and (B) component, It is preferable that it is 0.5-20 mass% especially. .

  The antifouling coating composition of the present invention can be produced by uniformly mixing the above components (A) to (C) and, if necessary, the above other components. Preferably, the pigment component is prepared by previously mixing and dispersing a part of the resin component (A) and / or a pigment dispersant to prepare a pigment paste, and mixing the pigment paste with the remaining components. it can.

  The coating composition of the present invention may be a one-pack type paint, but the two-component mixture is prepared immediately before use by separating the organosilicate and / or its condensate as component (C) from other components. It can also be a mold paint. From the viewpoint of storability and the like, a two-component paint is preferred.

  As a method of forming a coating film using the anti-stain coating composition of the present invention, the coating composition is adjusted to a desired viscosity by adding an organic solvent or the like as necessary, and then air spray, electrostatic air Using a spray, roll coater, flow coater, dipping coater, brush, bar coater, applicator, etc., the coating film thickness after drying is usually 0.5 to 300 μm, preferably 5 to 50 μm. And a method of heating and curing at 80 to 300 ° C. for about 5 seconds to 1 hour. As the coating method, spray coating or roll coater coating is preferable among the above methods.

Coating film forming method The coating film forming method of the present invention comprises forming a primer coating film with a chromium-free primer coating which does not contain a chromium-containing rust-preventing component on one or both surfaces of a metal plate. It is a coating film forming method characterized by forming a top coating film with the antifouling coating composition of the present invention on at least one of the films.

In other words, the method for forming a coating film according to the present invention includes a step of forming a primer coating film on one or both surfaces of a metal plate with a primer coating using a chromium-free primer coating, and at least one of the formed primer coating films. Furthermore, it is a coating film forming method characterized by including the process of forming a top coat film with the said contamination | pollution resistant coating composition of this invention.

  Moreover, the manufacturing method of the coating metal plate containing each process of the said coating-film formation method, and the coating metal plate obtained by the said coating-film formation method or the manufacturing method of a coating metal plate are also provided by this invention.

  The coating film forming method of the present invention can be used for both pre-coating and post-coating. Preferable examples of use include coating on the above-mentioned outdoor base materials (for example, buildings, display objects, guard fences, appliances, machines, etc.).

  Examples of the metal plate to be coated in the coating film forming method of the present invention include cold rolled steel plate, hot dip galvanized steel plate, electrogalvanized steel plate, alloy galvanized steel plate (iron-zinc, aluminum-zinc, nickel-zinc, etc. Alloy galvanized steel plate), aluminum plate, stainless steel plate, copper plate, copper plated steel plate, tin plated steel plate and the like.

  When painting on metals, the primer can be applied as it is if the metal surface, which is the material to be coated, is not contaminated with oil or other contaminants, but in order to improve the adhesion and corrosion resistance with the coating film. It is desirable to apply a known metal surface treatment. These known surface treatment methods include phosphate surface treatment, chromate surface treatment, zirconium surface treatment and the like.

  In the present invention, as a primer for forming a primer coating film on a metal plate, a chromium-free primer coating characterized by not containing a chromium-containing rust preventive component is used from the viewpoint of environmental protection. If the said primer is a chromium free primer coating, the well-known primer used in the coloring color steel plate coating field | area, the industrial machine coating field | area, the metal component coating field | area, etc. can be applied.

   The chromium-free primer coating is appropriately selected depending on the type of material to be coated and the type of metal surface treatment. In particular, epoxy-based and polyester-based primer coatings and their modified primer coatings are suitable, and polyester-based primer coatings are suitable when workability is particularly required.

  As a specific means for forming the primer coating film, there is exemplified a means for applying a primer coating and then heating and curing as necessary. In this case, 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. Usually, the ambient temperature is 80 to 300 ° C. For 5 seconds to 1 hour to cure. In the case of pre-coating, it is preferable to cure by heating for 15 seconds to 120 seconds under the condition that the maximum material reaching temperature is 140 to 250 ° C.

  The layer structure of the primer coating is not particularly limited. For example, the primer coating may be a single layer or a second primer coating (intermediate coating) formed on the first primer coating. It may be a layer. 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.

  Next, in the coating film forming method of the present invention, a top coating film is formed from at least one of the primer coating films formed on one side or both sides of the metal plate by the stain resistant coating composition of the present invention. The That is, the top coat film is formed so as to overlap on at least one side of the formed primer coat film. Here, "on at least one of the primer coatings" refers to the top of the primer coating formed on one side when the primer coating is formed on one side of the metal plate, When a primer coating is formed on both sides of the upper surface, it is formed on or on the primer coating formed on one side of the metal plate among the primer coatings formed on both sides. It points on the applied primer coating.

  As a specific means for forming the top coat film, there is exemplified a means for applying the antifouling coating composition of the present invention and then heating and curing as necessary. Examples of the coating method include curtain coating, roll coater coating, dip coating, and spray coating. The film thickness is usually applied such that the coating thickness after drying is in the range of 5 to 50 μm, preferably 8 to 25 μm.

  When the coating composition of the present invention is pre-coated, the coating method is not limited, but curtain coating and roll coater coating are preferred from the economical viewpoint of pre-coated steel sheet coating. When roll coater coating is applied, a bottom feed method (so-called natural reverse coating or natural coating) using two rolls is preferable from the viewpoint of practicality. Alternatively, a top feed or bottom feed method using three rolls can be performed from the viewpoint of achieving the best uniformity of the coating surface.

  The curing condition of the top coat film by the coating composition of the present invention is usually about 15 seconds 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 production examples and examples. The present invention is not limited to the following examples. Hereinafter, “parts” and “%” are based on mass.

Production and production example 1 of polyester resin
The following raw materials were charged into a flask equipped with a thermometer, stirrer, heating device and rectification tower:
1,2-cyclohexanedicarboxylic anhydride 150.9 parts (0.98 mol)
Neopentyl glycol 38.9 parts (0.37 mol)
9.6 parts (0.06 mol) of butylethylpropanediol
77.8 parts (0.57 mol) of trimethylolpropane
Coconut fatty acid 44.1 parts (0.21 mol)
Dibutyltin oxide (catalyst) 0.03 part.

  Next, the temperature was raised to 160 ° C. while stirring the contents, the temperature was gradually raised from 160 ° C. to 230 ° C. over 3 hours, and the reaction was continued at 230 ° C. for 30 minutes, and then the rectification column was replaced with a water separator. In order to promote the removal of by-product condensed water, 5% xylene was added to the total charge, and the reaction was further proceeded at 230 ° C. When the acid value reached 4 mgKOH / g, the heating was stopped, 1500 (hydrocarbon solvent) was added for dilution to obtain a polyester resin (A1-1) solution having a solid content of 65%.

  The obtained resin had a number average molecular weight of 15,000, a hydroxyl value (mg number of potassium hydroxide required to neutralize 1 g of resin) 75 mg KOH / g, oil length 14.7%, iodine value 5>. .

Production Examples 2-13
With the formulation shown in Table 1 below, in the same manner as in Production Example 1, solutions of the respective polyester resins (A1-2) to (A1-13) having a solid content of 65% were obtained. The composition ratio of each component in Table 1 is a molar ratio.

  Table 1 shows the number average molecular weight, hydroxyl value, oil length, and iodine value of each resin. In addition, the polyester resins (A1-7) to (A1-13) of Production Examples 7 to 13 are resins for comparative examples.

Production of antifouling paint composition and performance test Examples 1 to 18 and Comparative Examples 1 to 10
A paint was formed using the compositions shown in Tables 2 and 3 below. 1-28 were obtained. Antifouling paint composition No. 19 to 28 are coating compositions for comparative examples.

  KP color 8620 primer (manufactured by Kansai Paint Co., Ltd., polyester primer for pre-coated steel sheets) on each of the front and back surfaces of a molten 55% aluminum-galvanized steel sheet (galvalume steel sheet) having a thickness of 0.35 mm subjected to chemical conversion treatment ) Was coated so that the dry film thickness was 5 μm, heated so that the maximum material arrival temperature was 220 ° C., and baked for 40 seconds to obtain a primer-coated steel sheet. On the surface of the primer-coated steel sheet, each of the anti-stain coating compositions obtained as described above is applied with a bar coater so that the dry film thickness is about 15 μm, so that the maximum material temperature reaches 230 ° C. Each coated steel sheet was obtained by heating and baking for 50 seconds. The following performance test was done about each obtained coated steel plate.

  The test results are also shown in Table 2 and Table 3. In addition, the quantity of each component in Table 2 and Table 3 is solid content mass. In addition, when making the stain-resistant paint composition into a paint, the white pigment, titanium dioxide, was dispersed. Further, a mixed solvent of cyclohexanone / swazol 1500 (manufactured by Maruzen Petroleum Co., Ltd., aromatic high-boiling solvent) = 60/40 (mass ratio) was used for adjusting the viscosity of the coating composition. During coating, the viscosity of the coating composition was adjusted to about 100 seconds (25 ° C.) with Ford Cup # 4.

Note that (Note 1) to (Note 11) in Tables 2 and 3 are as follows.
(Note 1) Uban 20SE-60: manufactured by Mitsui Chemicals, Inc., butyl etherified melamine resin, weight average molecular weight of about 4000.
(Note 2) Super Becamine J820-60: Trade name “Super Becamine J-820-60”, manufactured by DIC Corporation, n-butyl etherified melamine resin solution.
(Note 3) Super Becamine L-118-60: Trade name “Super Becamine L-118-60”, manufactured by DIC Corporation, n-butyl etherified melamine resin solution.
(Note 4) Cymel 303: Low molecular weight methyl etherified melamine resin manufactured by Nippon Cytec Industries, Ltd. The content of hexakis (methoxymethyl) melamine is 60% by weight or more.
(Note 5) Sumidur BL3175: a methyl ethyl ketone oxime block compound of trimethylolpropane adduct type hexamethylene diisocyanate manufactured by Sumika Bayer Urethane Co., Ltd.
(Note 6) MS56S: trade name “MKC silicate MS56S” manufactured by Mitsubishi Chemical Corporation, methyl esterified silicate which is a condensate of tetramethoxysilane.
(Note 7) MS58B30: manufactured by Mitsubishi Chemical Corporation, trade name “MKC silicate MS58B30”, methyl / butyl mixed esterified silicate which is a condensate of tetraalkoxysilane, the ratio of methyl / butyl number is 70/30.
(Note 8) X-41-1805: manufactured by Shin-Etsu Chemical Co., Ltd., trade name, condensate of mercaptoalkyl group-containing trialkoxysilane, carbon number of mercaptoalkyl group is 18 or less, carbon number of alkoxy group is 6 or less It is.
(Note 9) Thyroid 161W: manufactured by GRACEGMMB, trade name, organically treated silica fine powder, oil absorption 170 ml / 100 g.
(Note 10) Nacure 5225: An isopropanol solution of a neutralized secondary amine of dodecylbenzenesulfonic acid manufactured by King Industries, USA. The degree of neutralization of dodecylbenzenesulfonic acid / amine is about 1.1 (molar ratio). The active ingredient is about 33% by weight, of which dodecylbenzenesulfonic acid / amine (mass ratio) is about 8/25. The numerical values in Table 2 are parts by mass of solid content of dodecylbenzenesulfonic acid.
(Note 11) Formate TK-1: A curing catalyst that is an organic tin solution manufactured by Takeda Pharmaceutical Co., Ltd., and a dissociation catalyst for a blocked polyisocyanate compound.

  The performance tests in Tables 2 and 3 were performed according to the following methods and evaluation criteria.

60 ° gloss:
According to JISK-54007.6 (1990), the 60-degree specular gloss was measured in accordance with the 60-degree specular gloss.

Processability:
In a room at 20 ° C., the test plate was bent 180 degrees with the coating surface facing outward, and the T number at which no crack 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. 2T for 3 sheets, 3T for 3 sheets, 4T for 4 sheets, 5T for 5 sheets, and 6T for 6 sheets. The results were determined by: : A: In the 4T bending process, almost no cracks are observed.
B: Clear cracks are observed in 4T bending, but almost no cracks are observed in 6T bending.
C: Clear cracks are observed in 6T bending.

Outdoor exposure test:
An outdoor exposure test specimen (100 x 300 mm) is attached to the installation base that models the eaves so that the coating film faces the north side, and an exposure test is conducted on the roof of Kansai Paint Co., Ltd. in Kanzaki-cho, Amagasaki City. Contamination resistance and rain-strip stain resistance (rain-stained stains) were evaluated according to the following criteria. Contamination resistance was measured by using a multi-light source spectrocolorimeter MSC-5N manufactured by Suga Test Instruments Co., Ltd. based on JISZ8370. Rain resistance stain resistance was judged visually.

Contamination resistance:
The following criteria were evaluated by ΔE before and after the outdoor exposure test:
S: ΔE is less than 2,
A: ΔE is 2 or more and less than 3,
B: ΔE is 3 or more and less than 5
C: ΔE is 5 or more.

Rain resistant stain resistance:
Rain traces after outdoor exposure tests were evaluated according to the following criteria:
S: Rain traces are not seen,
A: Slight traces of rain stripes are observed,
B: There are quite a few traces of rain
C: Rain traces remain dark.

Accelerated weather resistance:
Evaluation was made according to the following criteria by the degree of occurrence of chalking of the coated plate after the 7-cycle (161 hours) hydrogen peroxide xenon test:
S: No choking is observed,
A: Slight occurrence of choking is observed or slight whitening of the coating film is observed.
B: Whitening is recognized, there is no glossiness, and choking has occurred slightly.
C: Significant choking is observed.

Comprehensive evaluation:
In the stain resistant paint composition, it is important that the workability of the object to be coated, the stain resistance of the resulting coating film, the rain-stain stain resistance and the accelerated weather resistance are all high. Therefore, comprehensive evaluation was performed according to the following criteria.
S: Evaluation of workability, stain resistance, rain-stain stain and accelerated weather resistance are all S or A, and at least one is S.
A: Processability, stain resistance, rain-stain stain and accelerated weather resistance are all evaluated as A.
B: Processability, stain resistance, rain-stain stain and accelerated weather resistance are all evaluated as S, A or B, and at least one is B. C: Evaluation of scratch resistance, initial adhesion, and weather resistance. At least one of them is C.

Claims (11)

(A) A polyester resin containing 50 to 100 mass% of a fatty acid-modified polyester resin (A1) having a number average molecular weight of 5000 to 30000, a hydroxyl value of 5 to 100 mgKOH / g, and an oil length of 3 to 30% as a solid content,
The fatty acid-modified polyester resin (A1)
(A1): a polybasic acid containing an alicyclic polybasic acid (a1-1),
(A2): an alcohol containing a trihydric or higher polyhydric alcohol (a2-1), and (a3): obtained by reaction of a fatty acid,
In the reaction, the content of the alicyclic polybasic acid (a1-1) in the polybasic acid (a1) is within the range of 50 to 100 mol% based on the total amount of the polybasic acid (a1), and the alcohol ( a polyester resin in which the content of the trihydric or higher polyhydric alcohol (a2-1) in a2) is in the range of 10 to 70 mol% based on the total amount of the alcohol (a2);
(B) Melamine resin containing 50-100% by mass of butyl etherified melamine resin (B1) as a solid content; and (C) Organosilicate represented by the following general formula and / or a condensate thereof:
General _{^{formula: (R 1) n -Si- (}} OR 2) 4-n
[Wherein, R ¹ is an alkyl group having 1 to 18 carbon atoms or a phenyl group optionally substituted with an epoxy group or a mercapto group, R ² is an alkyl group having 1 to 6 carbon atoms, and n is 0 or 1. ]
Containing
(C) The antifouling paint composition whose solid content of a component is 0.1-50 mass% on the basis of the solid content total amount of (A) component and (B) component.   In the reaction for obtaining the fatty acid-modified polyester resin (A1), the total content of the alicyclic polybasic acid (a1-1) in the polybasic acid component (a1) is based on the total amount of the polybasic acid component (a1). The antifouling paint composition according to claim 1, which is in the range of 85 to 100 mol%.   Based on the total solid content of the polyester resin component (A) and the melamine resin component (B), the polyester resin component (A) is 50 to 90% by mass as the solid content, and the melamine resin component (B) is 10 as the solid content. The antifouling paint composition according to claim 1, which is contained in an amount of ˜50 mass%.   The alicyclic polybasic acid (a1-1) is 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3- An alicyclic polycarboxylic acid of methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid and 1,3,5-cyclohexanetricarboxylic acid, The antifouling paint composition according to claim 1, which is at least one selected from the group consisting of an anhydride of the alicyclic polyvalent carboxylic acid and a lower alkyl esterified product of the alicyclic polyvalent carboxylic acid. .   A trihydric or higher polyhydric alcohol (a2-1) is glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol and mannitol. 2. A trilactone or higher alcohol; a polylactone polyol compound obtained by adding a lactone compound to the trihydric or higher alcohol; and at least one selected from the group consisting of tris (hydroxyalkyl) isocyanurate. The antifouling paint composition as described.   Fatty acid (a3) is 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 oil It is a monovalent carboxylic acid of at least one linear hydrocarbon selected from the group consisting of fatty acids, safflower oil fatty acids, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid The antifouling paint composition according to claim 1.   Furthermore, the antifouling paint composition according to claim 1, further comprising a matting agent (D).   The antifouling paint composition according to claim 7, wherein the matting agent (D) is contained in an amount of 0.1 to 30% by mass as a solid content with respect to the total solid content of the polyester resin (A) and the melamine resin (B). . The step of forming a primer coating with a chromium-free primer coating on one or both surfaces on a metal plate, and at least one of the formed primer coatings, with the stain resistant coating composition according to claim 1 A method for forming a coating film comprising a step of forming a top coating film. The step of forming a primer coating with a chromium-free primer coating on one or both surfaces on a metal plate, and at least one of the formed primer coatings, with the stain resistant coating composition according to claim 1 A method for producing a coated metal sheet, comprising a step of forming a top coat film.   A coated metal plate obtained by the method according to claim 9 or 10.